Dr. Andrew J. Peters Profile

Dr. Andrew J. Peters

Postdoctoral Researcher at Univ of Minnesota

SPIE Involvement:

Author

Area of Expertise:

Block Polymers , Directed Self-Assmembly , Molecular Dynamics , Simulation , Micelles

Publications (18)

SPIE Journal Paper | 27 October 2017

Effect of chemoepitaxial guiding underlayer design on the pattern quality and shape of aligned lamellae for fabrication of line-space patterns

Benjamin D. Nation, Andrew J. Peters, Richard A. Lawson, Peter J. Ludovice, Clifford L. Henderson

JM3, Vol. 16, Issue 04, 043502, (October 2017) https://doi.org/10.1117/12.10.1117/1.JMM.16.4.043502

KEYWORDS: Line edge roughness, Line width roughness, Optical lithography, Double patterning technology, Interfaces, Directed self assembly, Polymers, Polymerization, Etching, Chemical species

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SPIE Journal Paper | 10 May 2016 Open Access

Calculations of the free energy of dislocation defects in lamellae forming diblock copolymers using thermodynamic integration

Andrew Peters, Richard Lawson, Benjamin Nation, Peter Ludovice, Clifford Henderson

JM3, Vol. 15, Issue 02, 023505, (May 2016) https://doi.org/10.1117/12.10.1117/1.JMM.15.2.023505

KEYWORDS: Directed self assembly, Thermodynamics, Polymers, Interfaces, Computer simulations, Polymerization, Systems modeling, Binary data, Thin films, Semiconductors

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SPIE Journal Paper | 8 March 2016

Coarse-grained molecular dynamics modeling of the kinetics of lamellar block copolymer defect annealing

Andrew Peters, Richard Lawson, Benjamin Nation, Peter Ludovice, Clifford Henderson

JM3, Vol. 15, Issue 01, 013508, (March 2016) https://doi.org/10.1117/12.10.1117/1.JMM.15.1.013508

KEYWORDS: Directed self assembly, Thin films, Interfaces, Polymers, Annealing, Diffusion, Scattering, Computer simulations, Process control

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Proceedings Article | 19 March 2015 Paper

Effect of χN and underlayer composition on self-assembly of thins films of block copolymers with energy asymmetric blocks

Richard Lawson, Andrew Peters, Benjamin Nation, Peter Ludovice, Clifford Henderson

Proceedings Volume 9423, 94231L (2015) https://doi.org/10.1117/12.2086047

KEYWORDS: Interfaces, Polymers, Thin films, Systems modeling, Molecular self-assembly, Computer simulations, Lithography, Physics, Visualization, Directed self assembly

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Proceedings Article | 19 March 2015 Paper

Effect of chemoepitaxial guiding underlayer design on the pattern quality and shape of aligned lamellae for fabrication of line-space patterns

Benjamin Nation, Andrew Peters, Richard Lawson, Peter Ludovice, Clifford Henderson

Proceedings Volume 9423, 94231J (2015) https://doi.org/10.1117/12.2085526

KEYWORDS: Line edge roughness, Chemical analysis, Optical lithography, Polymers, Double patterning technology, Data modeling, Molecular self-assembly, Chemical species, Thin films, Directed self assembly

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Proceedings Article | 19 March 2015 Paper

Coarse-grained molecular dynamics modeling of the kinetics of lamellar BCP defect annealing

Andrew Peters, Richard Lawson, Benjamin Nation, Peter Ludovice, Clifford Henderson

Proceedings Volume 9423, 94231Y (2015) https://doi.org/10.1117/12.2085518

KEYWORDS: Thin films, Polymers, Interfaces, Diffusion, Neodymium, Bridges, Annealing, Computer simulations, Process control, Directed self assembly

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SPIE Journal Paper | 20 August 2014

Simulation study of the effect of differences in block energy and density on the self-assembly of block copolymers

Richard Lawson, Andrew Peters, Benjamin Nation, Peter Ludovice, Clifford Henderson

JM3, Vol. 13, Issue 03, 031308, (August 2014) https://doi.org/10.1117/12.10.1117/1.JMM.13.3.031308

KEYWORDS: Interfaces, Polymers, Thin films, Computer simulations, Molecular self-assembly, Lithography, Physics, Picosecond phenomena, Manufacturing, Directed self assembly

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Proceedings Article | 28 March 2014 Paper

Simulation study of the effect of differences in block energy and density on the self-assembly of block copolymers

Richard Lawson, Andrew Peters, Benjamin Nation, Peter Ludovice, Clifford Henderson

Proceedings Volume 9049, 90490S (2014) https://doi.org/10.1117/12.2046603

KEYWORDS: Interfaces, Polymers, Thin films, Computer simulations, Lithography, Physics, Chemistry, Manufacturing, Photoresist materials, Directed self assembly

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Implementation of directed self-assembly (DSA) of block copolymers (BCPs) introduces a series of engineering challenges that have not been completely addressed in previous block copolymer and lithography studies. One of the required innovations for further DSA development and implementation is the accurate simulation of specific block copolymer chemistries and their interactions with interfaces. Many of the BCP simulation tools developed so far have limitations or difficulty in terms of matching many of the common issues found in experimental BCP systems such as polydispersity and different statistical segment lengths. One of the potentially most important issues is the fact that real BCPs often have block energy and/or density asymmetry, meaning that each block has a different homopolymer density and/or cohesive energy density (CED). A simulation of BCP behavior and DSA processes based on molecular dynamics (MD) of coarse-grained polymer chains has been developed that can independently parameterize and control the density and CED of each block to more accurately match the asymmetry found in experimental BCPs. This model was used to study the effect of block asymmetry on the order-disorder transition (ODT), domain scaling, and self-assembly of thin films of BCPs. BCPs whose blocks each have a different density show deviations from the mean-field ODT coexistence curve, exhibiting an order-disorder transition or co-existence curve that is asymmetric with shifts and tilts in the direction of majority highest density block. This impact of density and cohesive energy differences diblock copolymers on their phase behavior can explain some of the unexpected shapes found experimentally in BCP ODT curves. Asymmetry in the BCP block energy or density does not appear to have a significant effect on domain scaling behavior compared to the mean-field estimates. Self-assembly of thin films of BCPs with mismatches in CED shows significant deviations in the expected morphologies from ones simulated using equivalent densities and cohesive energy densities. The lowest CED block has a strong propensity to segregate to and “wet” the free interface at the top of the film because it has the lowest energy penalty for the loss of interactions with other chains at the free surface relative to the bulk. This gives rise to an effective “skinning” of the film by the lowest CED block for almost the entire potential range of underlayer compositions and film thicknesses. Such materials will be extremely difficult to successfully pattern transfer for a lithographically useful process because they will not form vertically aligned morphologies through the entire film thickness. This CED mismatch also gives rise to a large number of non-bulk morphologies and deviations from bulk behavior including changing vertical-to-horizontal morphologies through film depth, compression and expansion of domain sizes to match film thickness dimensions, and island and hole formation among others. Increasing the χN value can potentially suppress some of these non-idealities due to CED asymmetry, but the required χN to overcome these issues will differ from polymer to polymer depending on the magnitude of the CED asymmetry.

Proceedings Article | 28 March 2014 Paper

Predicting process windows for pattern density multiplication using block copolymer directed self-assembly in conjunction with chemoepitaxial guiding layers

Benjamin Nation, Andrew Peters, Richard Lawson, Peter Ludovice, Clifford Henderson

Proceedings Volume 9049, 90491C (2014) https://doi.org/10.1117/12.2046626

KEYWORDS: Polymers, Chemical species, Molecular self-assembly, Statistical modeling, Lithography, Computer simulations, Chemical analysis, Optical lithography, Physics, Directed self assembly

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Proceedings Article | 28 March 2014 Paper

Effect of guiding layer topography on chemoepitaxially directed self-assembly of block copolymers for pattern density multiplication

Benjamin Nation, Andrew Peters, Richard Lawson, Peter Ludovice, Clifford Henderson

Proceedings Volume 9049, 90492K (2014) https://doi.org/10.1117/12.2046629

KEYWORDS: Polymers, Computer simulations, Chemical species, Process modeling, Molecular self-assembly, Chemical engineering, Optical alignment, Semiconductor manufacturing, Feature extraction, Directed self assembly

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Proceedings Article | 28 March 2014 Paper

Understanding defects in DSA: calculation of free energies of block copolymer DSA systems via thermodynamic integration of a mesoscale block-copolymer model

Andrew Peters, Richard Lawson, Benjamin Nation, Peter Ludovice, Clifford Henderson

Proceedings Volume 9049, 90492E (2014) https://doi.org/10.1117/12.2046664

KEYWORDS: Polymers, Thermodynamics, Systems modeling, Monte Carlo methods, System integration, Molecular interactions, Semiconductors, Motion models, Polymerization, Directed self assembly

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Proceedings Article | 5 April 2013 Paper

Tuning domain size of block copolymers for directed self assembly using polymer blending: molecular dynamics simulation studies

Richard Lawson, Andrew Peters, Peter Ludovice, Clifford Henderson

Proceedings Volume 8680, 86801Z (2013) https://doi.org/10.1117/12.2021442

KEYWORDS: Polymers, Critical dimension metrology, Molecular self-assembly, Lithography, Interfaces, Image segmentation, Directed self assembly, Polymerization, Computer simulations, Silver

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A 10% batch-to-batch variation in molecular weight for a low polydispersity block copolymer (BCP) used for DSA lithography could result in more than a 6% change in critical dimension (CD). Therefore, there is a strong motivation and need to develop and understand methods for fine-tuning the domain size of DSA BCPs to meet the CD and pitch specifications that will be required for practical implementation of DSA processes. This study investigates two methods of fine-tuning the domain size of a specific batch of BCP through blending of the BCP with another polymer, either 1. a set of similar homopolymers (HPs) or 2. a similar BCP of different molecular weight. Each method was investigated and compared using a coarse grained molecular dynamics simulation. For BCP-HP blends, the domain size increases as the amount of HP increases because the HPs tend to slightly swell the BCP domains. A design heuristic was developed for guiding the determination of how much HP to add to obtain a desired pitch. For blends of different molecular weight BCPs, two different scaling regimes were identified; one regime is majority large chains and the other regime is majority small chains. Based on the simulation results, the domain scaling can be mapped across the full range of blends by simply measuring three points: the pure small chain domain size, the pure large chain domain size, and a 50/50 blend of the small and large chains. Comparing the two different blending methodologies, BCP blending with other BCPs is a more versatile approach because it can be used to either increase or decrease the domain size of a base BCP while HP blending can only increase the domain size. HP blending is also potentially problematic because the HPs tends to aggregate in the middle of each block’s half domain which can have a significant effect on CD uniformity due to the strong effect of local variations in the concentration of the HP and local variations in HP conformation. The use of BCP blends with other BCPs should be more favorable from a CD uniformity perspective because this approach is much less susceptible to initial local fluctuations than HP blends because all BCPs go to the A-B interface. The coarse grained molecular dynamics simulation is well suited for comparisons such as this and can produce design rules that are needed for experimental implementation of polymer blending with BCPs to tune domain size.

Proceedings Article | 5 April 2013 Paper

Coarse grained molecular dynamics model of block copolymer directed self-assembly

Richard Lawson, Andrew Peters, Peter Ludovice, Clifford Henderson

Proceedings Volume 8680, 86801Y (2013) https://doi.org/10.1117/12.2021439

KEYWORDS: Polymers, Molecular self-assembly, Polymerization, Lithography, Interfaces, Computer simulations, Systems modeling, Graphics processing units, Molecular interactions, Directed self assembly

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A model has been developed for the simulation of block copolymer (BCP) directed self-assembly (DSA) based on a coarse grained polymer model that anneals using molecular dynamics. The model uses graphics processing units (GPUs) to perform the calculations; this combined with the coarse graining means simulations times approach the speed of other more commonly used simulation techniques for BCPs. The model is unique in how it treats the pure phase blocks interactions with themselves (i.e. A-A and B-B interactions) and their interactions with each other. This allows for simulations that can potentially more accurately capture the differences between the properties of each block such as density and cohesive energy. The model is fully described and used to examine some of the issues that are unique to DSA lithographic applications of BCPs. We describe a method to calculate χ for the off-lattice MD system based on observation of the order-disorder transitions (ODT) for different degrees of polymerization N. The model is used to examine the transient, complex, non-classical morphologies that can occur through film thickness during a DSA process. During the phase separation process from a mixed initial state, the BCPs first locally phase separate to form small aggregate type structures. These aggregates then coalesce into larger features that approach the size of the equilibrium domain. These features then shift to match the guiding pattern on the underlayer followed by the slow elimination of defects. We also studied how the guiding patterns work in chemo-epitaxy DSA. The guiding patterns have a strong immediate effect on the BCP film nearest the interface and induce locally aligned self-assembly. Over time, this induced pattern tends to propagate up through the thickness of the film until the film is uniformly aligned to the guiding pattern. We also clearly see that the observed morphology at the top of the film gives no indication of the morphology through the depth, especially during the transient portions of the self-assembly process.

Proceedings Article | 5 April 2013 Paper

PS-b-PHOST as a high X block copolymers for directed self assembly: optimization of underlayer and solvent anneal processes

Nathan Jarnagin, Wei-Ming Yeh, Jing Cheng, Andrew Peters, Richard Lawson, Laren Tolbert, Clifford Henderson

Proceedings Volume 8680, 86801X (2013) https://doi.org/10.1117/12.2021420

KEYWORDS: Polymers, Annealing, Polymerization, Scanning electron microscopy, Picosecond phenomena, Thin films, Nitrogen, Directed self assembly, Polymer thin films, Glasses

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Proceedings Article | 26 March 2013 Paper

Effects of block copolymer polydispersity and xN on pattern line edge roughness and line width roughness from directed self-assembly of diblock copolymers

Andrew Peters, Richard Lawson, Peter Ludovice, Clifford Henderson

Proceedings Volume 8680, 868020 (2013) https://doi.org/10.1117/12.2021443

KEYWORDS: Line edge roughness, Polymers, Line width roughness, Inspection, Lithography, Neodymium, Polymerization, Edge roughness, Autoregressive models, Directed self assembly

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Proceedings Article | 16 April 2012 Paper

Detailed mesoscale dynamic simulation of block copolymer directed self-assembly processes: application of protracted colored noise dynamics

Andrew Peters, Richard Lawson, Peter Ludovice, Clifford Henderson

Proceedings Volume 8323, 83231T (2012) https://doi.org/10.1117/12.918077

KEYWORDS: Polymers, Computer simulations, Monte Carlo methods, Picosecond phenomena, Polymethylmethacrylate, Interfaces, Electron beam lithography, Stochastic processes, Lithography, Directed self assembly

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Proceedings Article | 16 April 2012 Paper

Investigation of high x block copolymers for directed self-asssembly: synthesis and characterization of PS-b-PHOST

Nathan Jarnagin, Jing Cheng, Andrew Peters, Wei-Ming Yeh, Richard Lawson, Laren Tolbert, Clifford Henderson

Proceedings Volume 8323, 832310 (2012) https://doi.org/10.1117/12.918081

KEYWORDS: Polymerization, Polymers, Optical lithography, Lithography, Scanning electron microscopy, Annealing, Molecular self-assembly, Directed self assembly, Glasses, FT-IR spectroscopy

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Proceedings Article | 16 April 2012 Paper

Directed self-assembly of poly(styrene)-block-poly(acrylic acid) copolymers for sub-20nm pitch patterning

Jing Cheng, Richard Lawson, Wei-Ming Yeh, Nathan Jarnagin, Andrew Peters, Laren Tolbert, Clifford Henderson

Proceedings Volume 8323, 83232R (2012) https://doi.org/10.1117/12.918073

KEYWORDS: Polymers, Optical lithography, Lithography, Etching, Polymerization, Plasma etching, Annealing, Solids, Plasma, Directed self assembly

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Directed self-assembly (DSA) of block copolymers is a promising technology for extending the patterning capability of current lithographic exposure tools. For example, production of sub-40 nm pitch features using 193nm exposure technologies is conceivably possible using DSA methods without relying on time consuming, challenging, and expensive multiple patterning schemes. Significant recent work has focused on demonstration of the ability to produce large areas of regular grating structures with low numbers of defects using self-assembly of poly(styrene)-b-poly(methyl methacrylate) copolymers (PS-b-PMMA). While these recent results are promising and have shown the ability to print pitches approaching 20 nm using DSA, the ability to advance to even smaller pitches will be dependent upon the ability to develop new block copolymers with higher χ values and the associated alignment and block removal processes required to achieve successful DSA with these new materials. This paper reports on work focused on identifying higher χ block copolymers and their associated DSA processes for sub-20 nm pitch patterning. In this work, DSA using polystyrene-b-polyacid materials has been explored. Specifically, it is shown that poly(styrene)-b-poly(acrylic acid) copolymers (PS-b-PAA) is one promising material for achieving substantially smaller pitch patterns than those possible with PS-b-PMMA while still utilizing simple hydrocarbon polymers. In fact, it is anticipated that much of the learning that has been done with the PS-b-PMMA system, such as development of highly selective plasma etch block removal procedures, can be directly leveraged or transferred to the PS-b-PAA system. Acetone vapor annealing of PS-b-PAA (M_w=16,000 g/mol with 50:50 mole ratio of PS:PAA) and its self-assembly into a lamellar morphology is demonstrated to generate a pattern pitch size (L₀) of 21 nm. The χ value for PS-b-PAA was estimated from fingerprint pattern pitch data to be approximately 0.18 which is roughly 4.5 times greater than the χ for PS-b-PMMA (_χPS-b-PMMA ~ 0.04).

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