This PDF file contains the front matter associated with SPIE Proceedings Volume 9425, including the Title Page, Copyright information, Table of Contents, Authors, Introduction (if any), and Conference Committee listing.

Multi-patterning technology using 193nm immersion lithography has been used since the 22nm logic node generation and it appears that it will continue to be used as far as the 14nm generation. At the same time, the industry trend is to simplify pattern design and reduce complexity in lithography though single directional (1D) layout[1]. On the other hand, there is increasing concern about pattern placement error in the application of this technology. This paper focuses on pattern placement variation in the process steps of pattern formation in 1D layout design, presents the results of a study on the effects of factors other than overlay accuracy on microscopic behavior, and describes techniques for improving pattern placement.

We have synthesized a new resist molecule and investigated its high-resolution capability. The material showed resolved line-spaces with 14 nm half-pitch (hp) and the potential to pattern 11 nm hp features. Line edge roughness values as low as 3.15 nm were seen in optimized formulations. The dose-to-size is estimated at around 20-30 mJ/cm². The role of the molecule in the patterning process was studied by comparing it with structurally similar compounds. Furthermore we present first results from exposures of our materials at the Berkeley Micro Exposure Tool. Finally it is also demonstrated that the material works as a resist in 100 kV electron beam lithography as well.

This study describes the recent progress of negative-tone imaging with EUV exposure (EUV-NTI) compared with positive-tone development (PTD). NTI uses organic solvent-based developer to provide low swelling and smooth-dissolving behavior. Therefore, EUV-NTI is expected to offer several advantages in terms of performance, especially for improving line-width roughness (LWR), which is expected to resolve the resolution, LWR, and sensitivity (RLS) tradeoff. Herein, novel chemical amplified resist materials for EUV-NTI are investigated to improve LWR and sensitivity. Results indicate that the EUV-NTI has better performance than PTD, with ‘single digit mJ/cm²,while maintaining the LWR performance. Furthermore, EUV-NTI processing such as the pre-applied bake (PAB) temperature, post-exposure bake (PEB) temperature, development procedure, and rinse procedure are very effective for improving the lithographic performance. In addition, the lithographic performance with NXE3100 scanner is also reported.

This work focuses on the application of a high speed atomic force microscope for the in situ visualization / quantification of the pattern formation phenomenon during resist dissolution. Specifically, this paper discusses on the quantification of various factors (e.g. pattern roughness, defects, etc.) that affect pattern quality. Comparing two typical positive-tone, extreme-ultraviolet lithography resists of dissimilar lithographic performance, results show that the differences in LER between such resists already exists even during the resist dissolution. This implies the significance of the dissolution process in further improving the final LER of lines-and-spaces (L/S) patterns. Moreover, results have shown the effectiveness of applying the same analysis technique in understanding pattern defect dynamics during dissolution, not only for L/S but also for contact hole (CH) patterns. Preliminary investigations on CH pattern formation during dissolution showed position-dependent variabilities / randomness in the timing of CH formation. Such variabilities in timing imply possible pointers in defining the origin of missing CH defects, from the resist dissolution point-of-view.

The main roadblock for EUV lithography to be successfully adopted for high-volume manufacturing is the current lack of source power. One way to help mitigate this problem is to optimize the photoresist by increasing both absorbance and quantum yield. The latter represents the ratio between the sums of generated acids and absorbed photons. Yield is also thought to be limited by the number of generated electrons per absorbed photon, or electron yield, that may be generated after a photo absorption event.

While absorbance is relatively easy to measure, yields are extremely difficult to quantify, and the debate on upper limits is far from settled. In this paper, we present how, using synchrotron light with tunable energy, we directly measured dispersion curves and electron yield for ArF, KrF and EUV photoresists using X-ray Absorption Spectroscopy.

Knowing the electron yield allowed us to better model organic EUV materials: stochastic simulations show how both electron yield and blur are very similar for organic materials, and how the electron blur is not a fixed property of the material, but may vary spatially, depending on a combination of photoresist formulation and local photon absorption density.

It is desirable to simultaneously improve the resolution, line-edge roughness (LER), and sensitivity of extreme ultraviolet (EUV) resist materials. In a resist film, nanometer-scale inhomogeneous structures may have significant direct effects on the resolution and LER along with indirect effects on sensitivity. This study will evaluate the inhomogeneity of photoacid generators (PAGs) in a hybrid-type EUV resist film using molecular-dynamics simulations. The results show the inhomogeneity of PAG positions and motions in the resist film. Moreover, PAG anions show larger diffusion coefficients than PAG cations. These results can be elucidated in terms of the free volumes in the resist matrix and the molecular structures of PAG, such as the bulky phenyl groups of PAG cations and the fluorine-atom interactions in PAG anions.

Two approaches which achieve the further evolution of NTD (Negative Tone Development) process are shown in this article. One is ACCEL (Advanced Chemical Contrast Enhancement Layer) process that can improve the lithography performance and the other is DTD (Dual Tone Development) process that can shrink patterning pitch below the limit of single exposure process. ACCEL is an additionally provided layer which is coated on a surface of NTD resist film before exposure and removed by NTD developer. ACCEL can enhance the acid distribution and dissolution contrast of the NTD resist. In fact, lithography performances such as exposure latitude (EL) and DOF improved dramatically by applying ACCEL compared to the NTD resist without ACCEL. We consider that suppression of excessive acid diffusion and material transfer between the resist layer and the ACCEL layer are the causes of the contrast enhancement. DTD process is one of the simplest pitch shrink method which is achieved by repeating PTD and NTD process. Feasibility study of DTD patterning has been demonstrated so far. However, Exposure latitude margin and CDU performance were not sufficient for applying DTD to HVM. We developed the novel DTD specific resist under a new concept, and 32 nm half pitch (hp) contact hole (CH) pattern was successfully formed with enough margins. DTD line and space (L/S) patterning are also demonstrated and 24 nm hp L/S pattern can be resolved. k1 factors of DTD CH and L/S patterns reach to 0.20 and 0.15, respectively.

Many different types of non-traditional resist designs have shown promise for future generations of patterning, but there is a greater need for understanding and developing additives and ancillary materials for these novel resists compared to traditional polymeric positive tone systems which are quite mature. With the goal of meeting some of these needs, we carried out multiple different studies of negative tone molecular resists based on epoxide cross-linking. We have developed methods for controlling cross-linking in these materials using photo-decomposable nucleophiles (PDNs) which have shown resolution improvements in one resist from 26 nm down to 18 nm so far. Aqueous base developed systems have been made by introducing phenol groups to these resists. Although the first molecule designed successfully patterns in aqueous base, its performance is limited compared to organic solvent development. A series of di-functional epoxide molecular resists have been made and generally show much worse sensitivity than a fourfunctional epoxide resist. Underlayers (ULs) have been designed specifically to leverage the high reactivity of epoxides to create ULs that can cross-link to the resist. These ULs improve the adhesion of some of these molecular resists, but also show significant sensitivity improvements compared to imaging on bare silicon. Sensitivity in one resist was improved by 5-12 mJ/cm² simply by using the UL.

Immersion based 20nm technology node and below becoming very challenging to chip designers, process and integration due to multiple patterning to integrate one design layer . Negative tone development (NTD) processes have been well accepted by industry experts for enabling technologies 20 nm and below. 193i double patterning is the technology solution for pitch down to 80 nm. This imposes tight control in critical dimension(CD) variation in double patterning where design patterns are decomposed in two different masks such as in litho-etch-litho etch (LELE). CD bimodality has been widely studied in LELE double patterning. A portion of CD tolerance budget is significantly consumed by variations in CD in double patterning.

The objective of this work is to study the process variation challenges and resolution in the Negative Tone Develop Process for 20 nm and Below Technology Node. This paper describes the effect of dose slope on CD variation in negative tone develop LELE process. This effect becomes even more challenging with standalone NTD developer process due to q-time driven CD variation. We studied impact of different stacks with combination of binary and attenuated phase shift mask and estimated dose slope contribution individually from stack and mask type. Mask 3D simulation was carried out to understand theoretical aspect. In order to meet the minimum insulator requirement for the worst case on wafer the overlay and critical dimension uniformity (CDU) budget margins have slimmed. Besides the litho process and tool control using enhanced metrology feedback, the variation control has other dependencies too. Color balancing between the two masks in LELE is helpful in countering effects such as iso-dense bias, and pattern shifting. Dummy insertion and the improved decomposition techniques [2] using multiple lower priority constraints can help to a great extent. Innovative color aware routing techniques [3] can also help with achieving more uniform density and color balanced layouts.

A series of five negative tone epoxide functionalized molecular resists have been synthesized and have had their glass transition temperature (T_g) and lithographic contrast behavior characterized. Introducing rigid structural features in the form of aromatic rings to a resist was found to increase its glass transition temperature. All resists but one, BHPF-2Ep, were found to have poor film stability which required the use of an underlayer. A trend was observed where PEB conditions performed at temperatures much higher than the T_g of the molecular resist was found to induce propagation of polymerization outside of exposed regions. Di-functionalized resists were observed to have poor sensitivity due to their low degree of functionalization. A resist was synthesized (BHPF-2Ep) which was capable of resolving features down to 20 nm with an imaging dose of 70.5 mJ/cm².

Through the continuous scaling with extension of 193-immersion lithography, the multi-patterning process with the grid-based design has become nominal process for fine fabrication to relax tight pitch designs^[1]. In self-aligned type multiple patterning, 7 nm node gate pattern was reported^[2],[3] and it was become a focal point LER on core-pattern is essential category to control pattern placement variations. Though CD uniformity (CDU) on line pattern in self-aligned double patterning (SADP) is relatively stable caused in high thickness controllability of spacer deposition films, the variations of CDU and LER on first core pattern impinge the CDU on space and pitch pattern. In previous study, pattern fidelity of single exposure patterning was improved through photoresist smoothing process using direct-current superposition technique^[4],[5].

In this paper, we will report that photoresist smoothing work in an efficient way to pattern fidelity control in self-aligned type multiple patterning.

In the presented work solvent-free film preparation from tailored molecular glass resists, their thermal analysis, the characterization of etch resistance for plasma etching transfer processes, and the evaluation of the patterning performance using scanning probe lithography (SPL) tools, in particular electric field and thermal based SPL, are demonstrated. Therefore a series of fully aromatic spiro-based and tris-substituted twisted resist materials were systematically investigated. The materials feature very high glass transition temperatures of up to 173 °C, which allows solvent-free thin film preparation by physical vapor deposition (PVD) due to their high thermal stability. The PVD prepared films offer distinct advantages compared to spin coated films such as no pinholes, defects, or residual solvent domains, which can locally affect the film properties. In addition, PVD prepared films do not need a post apply bake (PAB) and can be precisely prepared in the nanometer range layer thickness. An observed sufficient plasma etching resistance is promising for an efficient pattern transfer even by utilizing only 10 nm thin resist films. Their lithographic resolution potential is demonstrated by a positive and a negative tone patterning using electric field, current controlled scanning probe lithography (EF-CC-SPL) at the Technical University of Ilmenau or thermal scanning probe lithography (tSPL) investigations at the IBM Research - Zurich. High resolution tSPL prepared patterns of 11 nm half pitch and at 4 nm patterning depth are demonstrated.

In order to improve line width roughness (LWR) of chemically amplified resists (CARs) without trade-offs with other lithographic performances such as exposure latitude (EL) and sensitivity, we investigated effects of the spatial fluctuation of sensitivity on LWR of ArF resists. Compared a statistical model with experiments, it was clarified that LWR of ArF resists was caused by the fluctuation of sensitivity due to the fluctuation of the PAG and quencher concentration. Furthermore, we developed novel photoactive materials such as a transparent PAG and an nPAG-1Amine which were predicted to be useful for reducing the statistical fluctuation of sensitivity by the theoretical model. LWR was successfully improved using these photoactive materials. This study not only provided new insight into the root cause of LWR, but also proved efficacy of the theory-based material design.

Spin coating has been used as a photoresist application method for many years, and consequently certain defects have been recognized through each resist generation; i-line, KrF, ArF, ArF immersion and, most recently, EUV. Last year we reported an in-situ analysis via high-speed video camera that proved to be useful for understanding defect formation such as non-uniformity spots within organic film coatings and post-develop water-mark defects. In this study, fingerprints known as ‘tiger stripes’ around the wafer’s edge were analyzed. This phenomenon, for example, is directly related to the wafer spin-speed and air-flow during the coat-processing. Utilizing a high-speed camera and 3D simulation, we reveal the mechanism of fingerprint generation for tiger stripe phenomena, confirm the mechanism with several different spin-speeds, and correlate these to defect inspection results. Furthermore, we will discuss the expansion to 450mmm wafers.

One of the key challenges to high resolution resist patterning is probing the resist properties at length scales commensurate with the pattern size. Using a new scanning probe microscopy (SPM), Peak Force™ tapping, we map exposure dependent nanoscale modulus of the exposed/developed resist patterns with sub-10 nm resolution. By innovative electron beam exposure pattern design, the SPM technique reveals that resist modulus follows the height contrast profile, but with a shift to higher exposure doses. SEM image analysis of patterned resist structures confirm that the best line-space patterns are achieved at exposure dose where modulus reaches its maximum and shows how modulus can be used to probe patternability of resist systems.

Lack of progress in reducing linewidth roughness of lithographic features has led to investigations of the use of post-lithography process smoothing techniques. But it remains unclear whether such postprocessing will sufficiently reduce the detrimental effects of feature roughness. Thus, there is a need to understand the efficacy of post-processing on not just roughness reduction, but on the negative device impacts of roughness. This work derives model equations of how roughness impacts lithographic performance, and incorporates smoothing using post-processing. These models clearly show that post-process smoothing works best by increasing the correlation length. Increasing the correlation length is very effective at reducing high-frequency roughness that impacts within-feature variations, but is not very effective at reducing low-frequency roughness that impacts feature-tofeature variations. It seems that post-process smoothing is not a substitute for reducing the initial roughness of resist features.

Contact Hole (CH) Local Critical Dimension Uniformity (LCDU) has a direct impact on device performance. As a consequence, being able to understand and quantifying the different LCDU contributors and the way they evolve during the various process steps is critical. In this work the impact of etch process on LCDU for different resists and stacks is investigated on ASML NXE:3100 and NXE:3300. LCDU is decomposed into shot noise, mask, and metrology components. The design of the experiment is optimized to minimize the decomposition error. CD and LCDU are monitored and found to be stable.

We observed that the net effect of the etch process is to improve LCDU, although the final LCDU is both stack- and resist-dependent. Different resists demonstrate the same LCDU improvement, so that the LCDU after etch will depend on the initial resist performance. Using a stack different from the one used to set up the etch process can undermine the LCDU improvement.

The impact of the various etch steps is investigated in order to identify the physical mechanisms responsible for the LCDU improvement through etch. Both top-down and cross section Scanning Electron Microscopy (SEM) are used. The step-by-step analysis of the etch process showed that the main LCDU improvement is achieved during oxide etch, while the other process steps are either ineffective or detrimental in terms of LCDU. The main cause of the LCDU improvement is then attributed to the polymerization of the CH surface happening during the oxide etch.

Finally, the LCDU improvement caused by the etch process is investigated as a function of the initial LCDU after litho in a relatively broad range (2-15nm). The ratio between LCDU after litho over LCDU after etch is investigated as a function of the initial LCDU after litho for two different resists. The results indicate that the impact of etch on LCDU is characterized by a single curve, specific to the etch process in use and independent of the resist type. In addition, we observe that the percentage LCDU improvement is constant above a certain threshold, in agreement with the throughpitch results.

We have developed a series of fullerene containing materials for use as organic hard masks. Films with a thickness of up to 250 nm were deposited via spin coating. After a crosslinking bake the films exhibit good thermal stability – in the best case a mass loss of less than 3% at 400 °C is seen. Etch resistance of the different formulations are presented and hig-hresolution patterning is demonstrated. During the transfer into silicon no adverse “wiggling” is observed at high resolution. We attribute this to the low levels of aliphatic hydrogen present in the materials.

Numerous block copolymer (BCP) systems can be used in directed self-assembly (DSA) processes to form patterns useful in lithography, especially lines and spaces with lamellar phase systems and vias/pillars with cylindrical phase systems. However, most of these BCP systems with attractive pattern formation capabilities have limited plasma etch contrast between the polymer domains. One potential solution to greatly enhance this etch contrast is a recently developed technique called sequential infiltration synthesis (SIS). SIS is a self-limiting synthesis technique, like atomic layer deposition, where organometallic (OM) precursor vapours and oxidants are introduced into self-assembled block copolymer systems in multiple cycles. In the first half of each cycle the OM precursor selectively reacts with one polymer domain, and in the second half of the cycle the oxidant reacts with the OM groups in the polymer film to selectively form metallic compounds in one of the polymer domains. Thus, the polymer pattern is transformed into a metallic mask with much enhanced plasma etch contrast. We report the effects of such a block-selective SIS process of metallic compounds on the feature sizes, roughness and profiles of patterns formed with BCP systems.

The self-assembling behavior of thermally annealed PS-b-PMMA block copolymer derivatives (GEN2 BCPs) was evaluated using a substrate modified by a random copolymer, commonly called a ‘brush’. Similar to PS-b-PMMA, surface modification using the random copolymer brush served as an effective technique for controlling the domain orientation of the GEN2 BCP and yielded aligned features with pitches below 24nm. Non-preferential and weakly preferential random copolymers were also defined and applied to DSA using a graphoepitaxial approach. Finally, a Dry Development Rinse Process (DDRP)^[1] was tested as a method to prevent pattern collapse and improve pattern transfer for GEN2 BCPs.

To extend scaling beyond poly(styrene-b-methyl methacrylate) (PS-b-PMMA) for directed self-assembly (DSA), high quality organic high-_x block copolymers (HC series) were developed and applied to implementation of sub-10 nm L/S DSA. Lamellae-forming block copolymers (BCPs) of the HC series showed the ability to form vertically oriented polymer domains conveniently with the in-house PS-r-PMMA underlayers (AZEMBLY EXP NLD series) without the use of an additional topcoat. The orientation control was achieved with low bake temperatures (≤200 °C) and short bake times (≤5 min). Also, these process-friendly materials are compatible with existing 193i-based graphoepitaxy and chemoepitaxy DSA schemes. In addition, it is notable that 8.5 nm organic lamellae domains were amenable to pattern development by simple dry etch techniques. These successful demonstrations of high-_x L/S DSA on 193i-defined guiding patterns and pattern development can offer a feasible route to access sub-10 nm node patterning technology.

Directed Self-Assembly (DSA) is being extensively evaluated for application in semiconductor process integration.^1-7 Since 2011, the number of publications on DSA at SPIE has exploded from roughly 26 to well over 80, indicating the groundswell of interest in the technology. Driving this interest are a number of attractive aspects of DSA including the ability to form both line/space and hole patterns at dimensions below 15 nm, the ability to achieve pitch multiplication to extend optical lithography, and the relatively low cost of the processes when compared with EUV or multiple patterning options.

Tokyo Electron Limited has focused its efforts in scaling many laboratory demonstrations to 300 mm wafers. Additionally, we have recognized that the use of DSA requires specific design considerations to create robust layouts. To this end, we have discussed the development of a DSA ecosystem that will make DSA a viable technology for our industry, and we have partnered with numerous companies to aid in the development of the ecosystem. This presentation will focus on our continuing role in developing the equipment required for DSA implementation specifically discussing defectivity reduction on flows for making line-space and hole patterns, etch transfer of DSA patterns into substrates of interest, and integration of DSA processes into larger patterning schemes.

Directed Self Assembly (DSA) processes offer the promise of providing alternative ways to extend optical lithography cost-effectively for sub-10nm nodes and present itself as an alternative pitch division approach. As a result, DSA has gained increased momentum in recent years, as a means for extending optical lithography past its current limits. The availability of a DSA processing line can enable to further push the limits of 193nm immersion lithography and overcome some of the critical concerns for EUV lithography.

Inpria is developing directly patternable, metal oxide hardmasks as robust, high-resolution photoresists for EUV lithography. Targeted formulations have achieved 13nm half-pitch at 35 mJ/cm² on an ASML’s NXE:3300B scanner. Inpria’s second-generation materials have an absorbance of 20/μm, thereby enabling an equivalent photon shot noise compared to conventional resists at a dose lower by a factor of 4X. These photoresists have ~40:1 etch selectivity into a typical carbon underlayer, so ultrathin 20nm films are possible, mitigating pattern collapse. In addition to lithographic performance, we review progress in parallel advances required to enable the transition from lab to fab for such a metal oxide photoresist. This includes considerations and data related to: solvent compatibility, metals cross-contamination, coat uniformity, stability, outgassing, and rework.

We have developed organometallic carboxylate compounds [R_nM(O₂CR’)₂] capable of acting as negativetone EUV resists. Overall, the best and fastest resists contain antimony, are pentavalent and the carboxylate group contains a polymerizable olefin (e.g. acrylate, methacrylate or styrenecarboxylate). Evidence suggests that high sensitivity is achieved through the polymerization of olefins in the exposed region. We have performed a systematic sensitivity study of molecules of the type R_nM(O₂CR’)₂ where we have studied seven R groups, four main group metals (M), and three polymerizable carboxylate groups (O₂CR’). We found that the greatest predictor of sensitivity of the R_nSb(O₂CR’)₂ resists is their level of polymerizable olefins. We mathematically define the polymerizable olefin loading (POL) as the ratio of the number of olefins vs. the number of non-hydrogen atoms. Linear and log plots of E_max vs. POL for a variety of molecules of the type R₃Sb(O₂CR’)₂ lend insight into the behaviour of these resists.

Extreme Ultra Violet (EUV) Lithography is being thought to be one of the most promising candidate technologies to replace current optical lithography for the high-volume manufacturing of semiconductor devices at the 10 nm node and below. Through-put still seems to be under the target, so EUV resist materials are strongly required high resolution (R) with high sensitivity (S) and low line edge/width roughness (L). However, the chemically amplified resists should overcome RLS-trade-off. We focused on the development of EUV resist by the combination of the low activation energy protecting group (PG) and high quantum yield PAG for overcoming RLS trade-off.

Directed self-assembly (DSA) of block copolymers (BCP) is attracting a growing amount of interest as a technique to expand traditional lithography beyond its current limits. It has recently been demonstrated that chemoepitaxy can be used to successfully direct BCP assembly to form large arrays of high-density features using the ‘LiNe’ flow. This process uses lithography and trim-etch to produce a “prepattern” of stripes of alternating chemical composition, which in turn guide the formation of assembled BCP structures. The entire process is predicated on the preferential interaction of the respective BCP domains with particular regions of the underlying prepattern. The natural and relative strength of these interactions are at least partially responsible for many aspects of the resulting assembled BCP film, including equilibrium morphology, type and persistence of kinetically trapped defects, and domain roughness. This study develops the understanding of how various guiding chemistries ultimately govern BCP morphology and characteristics in the LiNe flow. In particular, the work focuses on how stronger affinity between chemical patterns and the guided BCP film leads to faster assembly, lower ultimate defectivity levels, and better incommensurability tolerance, as well as the relationship between pattern strength and domain roughness. One issue in generating finely controllable chemical patterns is that all materials are affected to some degree by processing, which can modify or weaken the guiding ability of the pattern. This investigation addresses the non-idealities introduced in production processing and explores how this knowledge can be employed in improving BCP DSA for lithography.

The patterning potential of block copolymer (BCP) materials via various directed self-assembly (DSA) schemes has been demonstrated for over a decade. We have previously reported the HONEYCOMB flow; a process flow where we utilize Extreme Ultraviolet Lithography and Oxygen plasma to guide the assembly of cylindrical phase BCPs into regular hexagonal arrays of contact holes [1, 2]. In this work we report the development of a new process flow, the CHIPS flow, where we use ArFi lithography to print guiding patterns for the chemo-epitaxial DSA of BCPs. Using this process flow we demonstrate BCP assembly into hexagonal arrays with sub-25 nm half-pitch and discuss critical steps of the process flow. Additionally, we discuss the influence of under-layer surface energy on the DSA process window and report contact hole metrology results.

Directed Self-Assembly (DSA) is one of the leading candidates for next generation patterning in IC manufacturing. With the continued delay of EUV and the increasing costs of evermore complex multipatterning techniques, DSA has the potential to produce small, well-defined features on a tight pitch. The graphoepitaxy DSA approach can be used to form single or multiple uniform contact holes (cylinders) well below the resolution limit of the optical exposure tool in a pre-pattern template. The utility of these patterns in the semiconductor manufacturing process is dependent on the capability of the process to control the size, edge roughness and placement of these DSA structures in the presence of reasonable levels of variation in the DSA material, the processing of that material and the pre-pattern template. In this study, a 3-D Self-Consistent Field Theory (SCFT) model has been developed to describe the behavior of such DSA systems. The utility of the simulator to describe actual physical behavior is explored, by fine tuning the SCFT model input parameters against experimental data for certain pre-pattern configurations and then evaluating the model predictions for other separate pre-pattern shapes. Two separate calibration studies are presented, one with 2-D guide patterns, in which multiple holes are positioned in a 2-D irregular array, and the other with 1-D structures, where the holes are distributed along one direction only. Pattern contours are extracted from CD-SEM images. A metric that measures the CD and placement is used to evaluate the modeled contours against the experimental contours.

While directed self-assembly based on poly(styrene)-block-poly(methylmethacrylate) block copolymers (BCP) for contact shrink or multiplication applications approaches industrial maturity, new systems with the ability to self-assemble with sub-20 nm features need to be evaluated taking into account the integration requirements (in terms of solvent, thermal budget, etching capability,…). In this contribution, two different systems Si-containing BCP systems will be presented targeting line/space applications. These two systems are characterized by a high segregation strength allowing the design of block copolymers with sub-20 nm period while high etching contrast inherent to the Si-containing block could be achieved between the different blocks. Firstly original poly(dimethylsilacyclobutane)-blockpoly( methylmethacrylate) (PDMSB-b-PMMA) block copolymers showing hexagonal arrays of PDMBS cylinders have been developed. Study of the PDMSB-b-PMMA self-assembly both on free surface and on patterned substrates show its high potential since long range order arrays can be obtained by a rapid thermal annealing treatment. Besides preliminary results on their track integration is discussed with a demonstration of density multiplication up to 18. The second system consists of poly(dimethylsiloxane)-block-poly(lactid acid) block chains which self-assemble into PDMS cylinders in thin film configuration. Such block copolymer system provides an easy access to line/space arrays of parallel PDMS cylinders which can be subsequently transferred into the desired stack layers through plasma etching.

Recently, directed self-assembly (DSA) method is focused on as a next generation lithography technique. We performed the DPD simulations to analyze the self-assembling process of block copolymer in DSA using OCTA (in detail, see http://octa.jp) system. Using DPD simulation, we can obtain the phase separated structures at each moment consisted by block copolymer chains. As those structures are consisted by polymer chains, an analysis can be done on those structures. In this paper, we study the dynamics of end particles in the defect annihilation process to understand the dynamics of self-assembling of block copolymer in DSA. From our analysis, the end particles moves in advance than the change of domain structure in the defect annihilation process.

Since the pattern pitch is getting smaller and smaller, the pattern collapse issue has been getting sever problem in the lithography process. Pattern collapse is one of the main reasons for minimizing of process margin at fine pitch by ArF-immersion or EUV lithography. The possible major cause of pattern collapse is the surface tension of the rinsing liquid and the shrinkage of resist pattern’s surface. These surface tension or shrinkage are occurred in the spin drying process of the rinsing liquid. The influence of surface tension against very small pitch pattern is particularly severe. One of the most effective solution for this problem is thinning of the resist film thickness, however this strategy is reaching to its limits in terms of substrate etching process anymore. Recently the tri-layer resist process or hard mask processes have been used, but there is a limit to the thinning of resist film and there is no essential solution for this problem. On the other hand, dry development process such a supercritical drying method or DSA patterning by dry etching have been known as an ultimate way to suppress the pattern collapse issue. However, these processes are not applied to the mass production process right now because these have some problems such a defect issue, requirement of the special equipment and so on. We newly developed the novel process and material which can prevent the pattern collapse issue perfectly without using any special equipment. The process is Dry Development Rinse process (DDR process), and the material used in the process is Dry Development Rinse material (DDR material). DDR material is containing the special polymer which can replace the exposed and developed part. And finally, the resist pattern is developed by dry etching process without any pattern collapse issue. In this paper, we will discuss the approach for preventing the pattern collapse issue in ArF and EUV lithography process, and propose DDR process and DDR material as the solution.

This paper presents a heuristic model for scanning helium ion beam lithography (SHIBL) in a EUV chemically amplified resist. The model employs a point-spread function to account for all physical and chemical phenomena involved in the resist activation. Ion shot noise effects are accounted for using Poisson statistics. Our model shows a good agreement with earlier single-pixel SHIBL experiments for determining line width as a function of dose for a desired line-and-space pattern. Furthermore, we propose optimized-pixel-dose SHIBL to improve exposure latitude, LCDU and LWR. Dose optimization is advantageous to single-pixel exposure when the feature size is at least about twice the width of the FWHM of the point-spread function. We confirm this by comparing our modeling results for single-pixel and optimizedpixel- dose exposure modes for line-and-space patterns

Self-aligned multiple patterning technique has enabled the further down scaling through 193 immersion lithography extension [1-5]. In particular, focus on the logic device scaling, we have finished the verification of patterning technology of up to 10nm node [6-7], we will discuss about some patterning technologies that are required to 7nm node. For critical layers in FinFET devices that presume a 1D cell design, there is also a need not just for the scaling of grating patterns but also for pattern cutting process. In 7nm node, cutting number increase in metal or fin layer, and also pattern splitting of contact or via is complicated, so both cost reduction and process controllability including EPE are strongly required. For example, inverse hardmask scheme in metal layer can improve CD variation of the Cu wiring. Furthermore hole pattern shrink technology in contact layer, by the combination with the exposure technique which has k1 0.25 or less, can achieve both cost reduction and reducing the numbers of pitch splitting. This paper presents the possibility of immersion-based multiple patterning techniques for up to 7nm node.

Pattern collapse currently limits the achievable resolution of the highest resolving EUV photoresists available. The causes of pattern collapse include the surface tension of the rinse liquid and the shrinkage of the resist pattern during the drying step. If these collapse mechanisms can be successfully mitigated with process approaches that do not require changes to the resist itself, the ultimate resolution of existing EUV resists can be improved. Described here is a dry development rinse process, applicable to existing EUV photoresists, which prevents pattern collapse to both improve ultimate resolution and the process window of currently resolvable features. Reducing the burden of collapse prevention on the resist also allows improvements in line width roughness (LWR) and cross section profile and provides additional degrees of freedom for future resist design.

Directed Self-Assembly (DSA) of Block Co-Polymer (BCP) with conventional lithography is being thought as one of the potential patterning solution for future generation devices manufacturing. Many studies have been reported to fabricate the aligned patterns both on grapho and chemoepitaxy for semiconductor application^{1, 2}. The hole shrink and multiplication by graphoepitaxy are one of the DSA implementation candidates in terms of relatively realistic process and versatility of chip design. The critical challenges on hole shrink and multiplication by using conventional Poly (styrene-b-methyl methacrylate) (PS-b-PMMA) BCP have been reported such as CD uniformity, placement error3 and defectivity. It is needed to overcome these challenging issues by improving not only whole process but materials. From the material aspect, the surface treatment material for guide structure, and process friendly BCP material are key development items on graphoepitaxy. In this paper, it will be shown in BCP approach about conventional PS-b-PMMA with additives and new casting solvent as PS-b-PMMA extension for CD uniformity and placement error improvement and then it’ll be discussed on what is the key factor and solution from BCP material approach.

It is well known that metal oxide films are useful as hard mask material in semiconductor industry for their excellent etch resistance against plasma etches. In the advanced lithography processes, in addition to good etch resistance, they also need to possess good wet removability, fill capability, in high aspect ratio contacts or trenches. Conventional metal containing materials can be applied by chemical vapor deposition (CVD) or atomic layer deposition (ALD). Films derived from these techniques have difficulty in controlling wet etch, have low throughput and need special equipment. This leads to high costs. Therefore it is desirable to develop simple spin-on coating materials to generate metal oxide hard masks that have good trench or via filling performances using spin track friendly processing conditions. In this report, novel spin-on type inorganic formulations providing Ti, W, Hf and Zr oxide hard masks will be described. The new materials have demonstrated high etch selectivity, good filling performances, wet removal capability, low trace metals and good shelf-life stability. These novel AZ® Spin-on metal hard mask formulations can be used in several new applications and can potentially replace any metal, metal oxide, metal nitride or silicon-containing hard mask films currently deposited using CVD process in the semiconductor manufacturing process.

Cleaning processes account for over 25% of processing in microelectronic manufacturing [1], suggesting electronics to be one of the most chemical intensive markets in commerce. Industry roadmaps exist to reduce chemical exposure, usage, and waste [2]. Companies are encouraged to create a safer working environment, or green factory, and ultimately become certified similar to LEED in the building industry [3]. A significant step in this direction is the integration of aqueous-based photoresist (PR) strippers which eliminate regulatory risks and cut costs by over 50%. One of the largest organic solvent usages is based upon thick PR removal during bumping processes [4-6]. Using market projections and the benefits of recycling, it is estimated that over 1,000 metric tons (mt) of residuals originating from bumping processes are incinerated or sent to a landfill. Aqueous-based stripping would eliminate this disposal while also reducing the daily risks to workers and added permitting costs. Positive-tone PR dissolves in aqueous strippers while negative-tone systems are lifted-off from the substrate, bumps, pillars, and redistribution layers (RDL). While the wafers are further processed and rinsed, the lifted-off PR is pumped from the tank, collected onto a filter, and periodically back-flushed to the trash. The PR solids become a non-hazardous plastic waste while the liquids are mixed with the developer stream, neutralized, filtered, and in most cases, disposed to the sewer. Regardless of PR thickness, removal processes may be tuned to perform in <15min, performing at rates nearly 10X faster than solvents with higher bath lives. A balanced formula is safe for metals, dielectrics, and may be customized to any fab.

Inpria is pioneering a novel approach to EUV photoresist. Directly patternable metal oxide thin films have shown resolution better than 10nm half-pitch, with robust etch resistance, and efficient use of photons through high EUV absorbance. Inpria’s Gen2 photoresists are cast from commonly used organic coating solvents and are developed in typical negative tone develop (NTD) organic solvents. This renders them compatible with CLEAN TRACK LITHIUS Pro-EUV coater/developer system (Tokyo Electron Limited; TEL) and solvent drains. The presence of metal in the photoresist demands additional scrutiny and process development to minimize contamination risks to other tools and wafers. In this paper, we review progress in developing coat processes that reduce metal contamination levels below typical industry levels. We demonstrate minimization of trace metals contamination from wafer-to-coater/developer, and wafer-to-wafer from the spin coat process. This will also include results from surface analyses of frontside edge exclusion and backside of wafer using best-known analytical methods. In addition, we discuss results of coat uniformity and defectivity optimization. Wet clean compatibility and dry etch rate by using conventional Si-ARC/OPL etching recipe will also be presented. In conjunction with this work, we identify potential contamination pathways and means for managing contamination risk. We furthermore review equipment compatibility issues for using Inpria’s metal oxide photoresists.

A photosensitive polyimide system based on amine catalyzed imidization of a precursor poly(amic ester) is described. The material is based on the meta ethyl ester of pyromellitic dianhydride and 2,2’ bis(trifluoromethyl)benzidine and acts as a negative tone resist when formulated with a photobase generator. The material exhibits a dielectric constant of 3.0 in the GHz range, a coefficient of thermal expansion of 6±2 ppm/K, and can be patterned to aspect ratios of greater than 2 when formulated with a high efficiency cinnamide type photobase generator.

This work focuses on the investigation of dual tone patterning mechanism with hybrid inorganic/organic photoresists. Hafnium oxide (HfO₂) modified with acrylic acid was prepared and the influence of electrolyte solutions as well as pH on its particle size change was investigated. The average particle size and zeta potential of the nanoparticles in different electrolyte solutions were measured. The results show that addition of different concentrations of electrolytes changed the hydrodynamic diameter of nanoparticles in water. Increased concentration of tetramethyl ammonium hydroxide (TMAH) caused the zeta potential of nanoparticles to change from positive to negative and its hydrodynamic diameter to increase from 40 nm to 165 nm. In addition, increasing concentration of triflic acid led to the decrease of particle size and zeta potential.

The role of photoresist has become more important for down scaling of electric devises. One of the key factors which identify the photoresist is a diffusion of acid through the lithography process. The ‘top coat method’ was proposed for measuring the distance of diffusion of acid which was generated from PAG and calculating the diffusion coefficient^1-3. In this method, top coat material containing PAG (2^nd layer) is coated on a PAG-free resist (1^st layer), then the exposure and PEB processes are performed. The generated acid in 2^nd layer during the exposure diffuses into 1^st layer when the PEB is performed. After that, we can obtain the acid diffusion length based on the quantity of film removed by the development. In this work, we applied TOF-SIMS measurement with gas cluster ion beam (GCIB) etching to the samples that were prepared for top coat method. This measurement has revealed the distribution of diffusing PAG and residual protecting groups of the resin in the resist (1^st layer). The diffusion length of the acid which is obtained by the top coat method has corresponded to the depth profile of the acid and the deprotection rate which is acquired by TOFSIMS with GCIB. We can estimate the marginal deprotection rate which is needed for the development by the result of these two methods. It has also been clear that the distributions of acid shifted into the resist according to the PEB temperature.

The relation between resist composition and its development behavior was evaluated. The effect of a hydrophobic unit on a resist and on its development behavior was systematically investigated. The resist was exposed to extreme ultraviolet (EUV) or electron beam (EB) exposure, and the development behavior of the film was observed by high-speed atomic force microscopy (HS-AFM). The introduction of a hydrophobic group in the resist resulted in diminished swelling behavior and uniform dissolution. The resist resin cluster shape was also altered by the introduction of the hydrophobic group. These behaviors imply that the resin–resin and resin–tetramethylammonium hydroxide solution interactions differ. EUV lithography suffers from the photon issue that causes stochastic uniformity; however, in this study, we demonstrate the feasibility of achieving a better uniformity of resist patterning by altering the resist formulation.

Negative tone development (NTD) has dramatically gained popularity in 193 nm dry and immersion lithography, due to their superior imaging performance [1, 2 and 3].

Popular negative tone developers are organic solvents such as n- butyl acetate (n-BA), aliphatic ketones, or high-density alcohols such as Methyl Isobutyl Carbinol (MIBC). In this work, a comparative study between ultra-high molecular weight polyethylene (UPE) and polytetrafluoroethylene (PTFE) POU filtration for n-BA based NTD has been carried out.

Results correlate with the occurrence or the mitigation of micro bridges in a 45 nm dense line pattern created through immersion lithography as a function of POU membrane.

In this paper, we report the development of new xanthendiol derivatives applied to the negative-tone molecular resists for EB/EUVL. The new xanthendiol derivatives were easily synthesized by the condensation of aldehydes and dihydroxyaromatic compounds. We found 13,13’-biphenyl-bis(13H-benzoxanthen-2,11-diol) was showed the good applicability to the raw material for the resist for EB/EUVL. The EB patterning result showed the resist containing xanthendiol derivative could resolve the 20 nm half-pitch pattern, and 15 nm half-pitch patterns were partially resolved.

A newly light-scattering thermal cross-linking material based on self-assembly for forming the morphology of nanoparticle free polymer blends was reported. The material design concept to use light-scattering thermal cross-linking material with high uniformity of light on display panel from LED for high quality such as brightness and evenness, mechanical properties, and gas and water barrier properties. The high light scattering rate of 8 % at 350-450 nm of wavelength, fast cure film at 140 ºC and 120 s, and thermal stability at 190 ºC in bake condition for high productivity were indicated in the light-scattering thermal cross-linking material using the nanoparticle free polymers with carboxylic acid functional groups. These novel system using morphology of nanoparticle free polymer blends in light-scattering package material for a LCD using LED was a valuable approach to the design of material formulations for newly light-scattering thermal cross-linking material.

Various blends approaches based on PS-b-PMMA block-copolymers (BCP) systems are studied. The impacts of the different components in the blends on various basic characteristics of interest for lithographic applications are highlighted. More specifically, we show how such approaches can be managed to get a tight control over the different dimensions of the self-assembly, and reach lower defects levels than a single pure BCP. These methods could greatly help the BCP self-assembly technology to be introduced as an actual lithographic technic to further reduce achievable dimensions.

We investigated the eco-friendly electron beam (EB) and extreme-ultraviolet (EUV) lithography using a high-sensitive negative type of green resist material derived from biomass to take advantage of organic solvent-free water spin-coating and tetramethylammonium hydroxide(TMAH)-free water-developable techniques. A water developable, non-chemically amplified, high sensitive, and negative tone resist material in EB lithography was developed for environmental affair, safety, easiness of handling, and health of the working people, instead of the common developable process of TMAH. The material design concept to use the water-soluble resist material with acceptable properties such as pillar patterns with less than 100 nm in high EB sensitivity of 10 μC/cm² and etch selectivity with a silicon-based middle layer in CF₄ plasma treatment was demonstrated for EB and EUV lithography.

New “self-immolating” or “unzipping” polymers, materials that depolymerize in response to irradiation, were designed and prepared successfully. We studied several candidate polymers and ultimately chose two of them for further development. One is a polyester that aromatizes upon depolymerization. The unzipping reaction initiated by UV exposure in solution was confirmed. The polymer was then studied in thin films to assess its potential for use in formulating photoresists. The neat polymer was tested as a blend with novolac resin. The effect of unzipping polyester loading in novolac on the rate of dissolution of films in TMAH was studied. Inhibition occurs at 20−30% loading. The films were exposed with DUV light and patterning was observed. The sensitivity of the unzipping polyester formulation is low in part due to the low absorption of the polymer for UV light. However, the polymer showed higher sensitivity with EUV exposure and first contrast curves show sensitivity in the range of 20−25mJ/cm².

EUV lithography is the most favorable process for high volume manufacturing of semiconductor devices beyond 1X nm half-pitch at present. Many efforts have revealed effective proton sources in acid generation in EUV resists, and the effective proton generation and the control of the generated acid diffusion are required to improve the breakthrough of the resolution － line width roughness － sensitivity(RLS) trade-off. To clarify the lithographic performance of these derivatives, we synthesized the acrylic ter/tetrapolymers containing novel lactone derivatives - LCHO and LAATB - as model photopolymers and exposed the resist samples based on these polymers to EUV and EB radiation. On the basis of the lithographic performances of these photoresists, we evaluated the characteristics of lactone derivatives upon exposure to EUV radiation. We discuss the relationship between the chemical structures of these derivatives and lithographic performance.

A negative tone, aqueous base developable molecular glass resist, 3Ep, is presented that is developable in both standard organic solvents and aqueous base developers. The resist shows slightly better imaging performance in organic solvent versus aqueous base and shows a shift of E0 away from zero dose. Compared to a previously reported 4Ep resist, 3Ep appears to have a more controlled polymerization rate at equivalent conditions, which results in higher-quality patterned features. 3Ep also requires use of an underlayer to avoid de-wetting during aqueous base development.

In this paper, we summarize our development efforts for a top-coatless 193nm immersion positive tone development (PTD) contact hole (C/H) resist with improved litho and defect performances for logic application specifically with an advance node. The ultimate performance goal was to improve the depth of focus (DoF) margin, mask error enhancement factor (MEEF), critical dimension uniformity (CDU), contact edge roughness (CER), and defect performance. Also, the through pitch CD difference was supposed to be comparable to the previous control resist. Effects of polymer and PAG properties have been evaluated for this purpose. The material properties focused in the evaluation study were polymer activation energy (Ea), polymer solubility differentiated by polymerization process types, and diffusion length (DL) and acidity (pKa) of photoacid generator (PAG). Additionally, the impact of post exposure bake (PEB) temperature was investigated for process condition optimization. As a result of this study, a new resist formulation to satisfy all litho and defect performance was developed and production yield was further improved.

Newly eco-friendly high light transparency film with plant-based materials was investigated to future development of liquid crystal displays and optical devices with water repellency as a chemical design concept of nanoimprint lithography. This procedure is proven to be suitable for material design and the process conditions of ultraviolet curing nanoimprint lithography for green water-repellent film derived from biomass with high-light transparency. The developed formulation of advanced nanoimprinted materials design derived from lactulose and psicose, and the development of suitable UV nanoimprint conditions produced high resolutions of the conical shaped moth-eye regularly-nanostructure less than approximately 200 nm diameter, and acceptable patterning dimensional accuracy by the replication of 100 times of UV nanoimprint lithography cycles. The newly plant-based materials and the process conditions are expected as one of the defect less nanoimprint lithographic technologies in next generation electronic devices.

With the continuous demand for higher performance of computer chips and memories, device patterns and structures are becoming smaller and more complicated. Hard mask processes have been implemented in various steps in the devise manufacturing, and requirements for those materials are versatile. In this paper, novel organometal materials are presented as a new class of spin on solution in order to support the hard mask process. Type of metals, formulation scheme and processing conditions were carefully designed to meet the fundamental requirements as a spin on solution, and their characteristic properties were investigated in comparison to other conventional films such as spin on carbons (SOC), organic bottom anti-reflective coatings (oBARC) and inorganic films formed by chemical vapor deposition (CVD). Several advantages were identified with these SOMHM materials over other films which include 1) better thermal stability than SOC once fully cured, 2) reworkable with industry standard wet chemistry such as SC-1 where conventional Si-BARC is difficult to remove, 3) a wide range of optical constants to suppress reflection for photoresist imaging, 4) high etch resistance and 5) better gap filling property. Curing conditions showed a significant impact on the performance of SOMHM films, and X-ray photoelectron spectroscopy (XPS) was utilized to elucidate the trends. With SOMHM film as a BARC, photolithographic imaging was demonstrated under ArF immersion conditions with 40nm linewidth patterning.

Efforts to extend 193 nm lithography have introduced multiple patterning solutions to print a single level layer. Due to this increased complexity, defectivity on each layer is becoming very critical. Micro and multiple line bridges are one of the primary challenges in photolithography contributing to this complexity. These defects originate from several root causes and are difficult to eliminate. Point-of-use filtration plays a significant role on the mitigation of such defects. The impact of filtration rate and pressure was previously documented. In this research, we demonstrate that the combination of membrane and pore size selection, photoresist optimization, and hardware optimization can impact micro and multiple bridge mitigation in a 45 nm line/space pattern created through immersion lithography.

With the development of the lithography, the demand for critical dimension (CD) and CD uniformity (CDU) has reached a new level, which is harder and harder to achieve. There exists reflection at the interface between photo-resist and substrate during lithography exposure. This reflection has negative impact on CD and CDU control. It is possible to optimize the litho stack and film stack thickness on different lithography conditions. With the optimized stack, the total reflectivity for all incident angles at the interface can be controlled less than 0.5%, ideally 0.1%, which enhances process window (PW) most of the time. The theoretical results are verified by the experiment results from foundry, which helps the foundry achieve the mass production finally.

Negative tone shrink materials (NSM) suitable for resolution enhancement of negative tone development (NTD) 193nm immersion resists have been developed. While this technology is being expanded to integrated circuits (IC) manufacturing, there still have two major problems to apply various processes. One of them is shrink ID bias which means shrink differences between isolated (I) and dense (D) CDs, and the other one is Y/X shrinkage bias which means shrinkage differences between major axis (Y) and minor axis (X) of the elongated or oval shape pattern. While we have presented the improvement of shrink ID bias at SPIE2014 [1], the reduction of Y/X shrinkage bias was the examination theme for quite some time. In this paper, we present Y/X shrinkage bias of current NTD shrink material, new concept material for Y/X bias reduction and the result of new shrink material. Current NTD shrink model has Y/X bias of 1.6 (Y shrink=16nm) at a mixing bake (MB) of 150°C on AZ AX2110P NTD elongated pattern of X=70nm and Y=210nm ADI. This means shrinkage of Y has larger shrinkage than X and that makes difficult to apply shrink material. We expected that the characteristic shape of elongated pattern was one of the root-cause for Y/X bias, and then simulated how to achieve equivalent shrinkage at Y and X. We concluded that available resist volume per each Y and X unit was not equivalent and need new shrink concept to solve Y/X bias. Based on our new concept, we prepared new shrink material which has lower Y/X bias and larger shrink amount compared with current NTD shrink material. Finally we have achieved lower Y/X bias from 1.6 to 1.1 at MB150°C and moreover got higher shrinkage than current NTD shrink material from 10.1nm to 16.7nm.

It is well known that point-of-use (POU) filtration is an effective means of reducing microbridging defects in lithographic processes involving photoresists. To date, most of the optimization studies have been targeted toward understanding the microbridging defects in positive tone imaging (PTI) process. Considering that negative tone imaging (NTI) process has recently been introduced in advanced technology nodes, we focused our POU filtration studies on understanding the factors that modulate microbridging in NTI and PTI processes. Our studies pointed out that Nylon 6,6 membrane is distinctly more effective in reducing microbridging defects in NTI resists, whereas HDPE membranes show significant improvement in PTI resists. These results were rationalized based on the polarity differences of microbridges in PTI and NTI processes.

In order to understand the mechanism of the pattern wiggling distortion and to find control knobs for improving wiggle performance of spin-on carbon hard mask materials, we have developed analysis method of underlayer (UL) films by utilizing XPS depth profiling using Gas Cluster Ion Beam(GCIB-XPS). Differences of distributions of elemental compositions from the surface to the bottom of the processed or un-processed films have been visualized by GCIB-XPS analysis. Besides, these achievements allow us to identify fluoro substitution of oxygen during etching process as the control knob for the pattern wiggling distortion.

The high volume manufacturing with extreme ultraviolet (EUV) lithography is delaying due to its light source issue. Therefore, ArF-immersion lithography has still been the most promising technology for down scaling of device pitch. As the limitation of ArF-immersion single patterning is considered to be nearly 40nm half pitch (hp), ArF-immersion lithography has necessity to be extended by combining processes to achieve sub- 20nm hp patterning. Recently, there are many reports about the extension of ArF-immersion lithography, e.g., self-aligned multiple patterning (SAMP) and litho-etch-litho-etch (LELE) process. These methods have been realized by the combination of lithography, deposition, and etching. On the other aspect, 1-D layout is adopted for leading devices, which contains additional cut or block litho and etch processes to form 2-D like layout. Thus, according to the progress of down scaling technologies, number of processes increases and the cost of ownership (CoO) can not be neglected. Especially, the number of lithography steps and etching steps has been expanded by the combination of processes, and it has come to occupy a large portion of total manufacturing cost. We have reported that negative tone development (NTD) system using organic solvent developer have enough resolution to achieve fine narrow trench or contact hole patterning, since negative tone imaging enables to apply bright mask for these pattern with significantly high optical image contrast compared to positive tone imaging, and it has contributed high throughput multiple patterning. On the other hand, NTD system is found to be useful not only for leading device node, but also for cost effective process. In this report, we propose the cost effective process using NTD application. In the viewpoint of cost down at exposure tool, we have developed KrF-NTD resist which is customized for organic solvent developer. Our KrF-NTD resist has resolution comparable with ArF positive tone development (PTD) resist in narrow trench pattern, and it realizes downgrade of exposure tool. Also, we propose litho-litho-etch process with NTD resist. This method can reduce etching process and decrease total manufacturing cost more directly.

Recently there has been a great deal of effort focused on increasing EUV scanner source power; which is correlated to increased wafer throughput of production systems. Another way of increasing throughput would be to increase the photospeed of the photoresist used. However increasing the photospeed without improving the overall lithographic performance, such as local critical dimension uniformity (L-CDU) and process window, does not deliver the overall improvements required for a high volume manufacturing (HVM). This paper continues a discussion started in prior publications [Ref 3,4,6], which focused on using readily available process tooling (currently in use for 193 nm double patterning applications) and the existing EUV photoresists to increase photospeed (lower dose requirement) for line and space applications. Techniques to improve L-CDU for contact hole applications will also be described.