EUV lithography (EUVL) is the candidate for next generation lithography to be introduced by the semiconductor industry to HVM (high volume manufacturing) in 2013. The power of the EUVL light source has to be at least 115W at a wavelength of 13.5nm. A laser produced plasma (LPP) is the main candidate for this light source but a cost effective laser driver is the key requirement for the realization of this concept. We are currently developing a high power and high repetition rate CO2 laser system to achieve 50 W intermediate focus EUV power with a Tin droplet target.
A high conversion efficiency (CE) from laser energy to EUV in-band energy is the most important issue for the concept to be realized. A CE of more than 2 % has been obtained with a Tin target and a CO2 laser which is also predicted by numerical simulation analysis. The high CE requires a short laser pulse of less than 15 ns.
This paper describes the development of a CO2 laser system that is based on RF-excited, axial flow CO2 laser amplifiers. The system produces a short pulse length about 15 ns and a nominal average power of several kW at a repetition rate of 100 kHz,
An output power of 2.6 kW has been achieved with a pulse length between 15~30 ns at 130 kHz repetition rate at small signal amplification. The phase distortion of the laser beam after amplification is negligible and the beam can be focused to about 150&mgr;m diameter in 1/e2. The conceptual design of the CO2 laser system for LPP EUVL light source, and the laser performance are reported. The further increase of the amplification efficiency is discussed to obtain 5 kW average output power.
We evaluated Sn debris generated from a CO2 laser (10.um) and a Nd:YAG laser (1064nm) plasma. Experiments were
performed with bulk Sn-plates (t=1mm) and freestanding Sn-foils (t=15um). Quartz Crystal Microbalances (QCM) were
used for debris analysis. We observed a drastically lower deposition for the CO2 laser driven plasma compared with the
Nd:YAG laser plasma. In addition, several Sn coated targets with different Sn thickness were investigated for the CO2
drive laser with respect to the generated plasma debris. In general, a 100nm Sn coated glass target generated more debris
than the solid Sn target. Especially, we observed for the Sn-plate target that the deposition rate is smaller than the erosion
(sputter) rate caused by the plasma ions.
We develop a laser produced plasma light source for high volume manufacturing (HVM) EUV lithography. The light
source is based on a short pulse, high power, high repetition rate CO2 master oscillator power amplifier (MOPA) laser
system and a Tin droplet target. A maximum conversion efficiency of 4.5% was measured for a CO2 laser driven Sn
plasma having a narrow spectrum at 13.5 nm. In addition, low debris generation was observed. The CO2 MOPA laser
system is based on commercial high power cw CO2 lasers. We achieve an average laser power of 3 kW at 100 kHz with a
single laser beam that has very good beam quality. In a first step, a 50-W light source is developing. Based on a 10-kW
CO2 laser this light source is scalable to more than 100 W EUV in-band power.
Extreme ultraviolet lithography (EUVL) is the candidate for next generation lithography to be introduced by the
semiconductor industry to HVM (high volume manufacturing) in 2013. The power of the EUVL light source has to be at
least 115W at a wavelength of 13.5nm. A laser produced plasma (LPP) is the main candidate for this light source but a
cost effective laser driver is the key requirement for the realization of this concept. We are currently developing a high
power and high repetition rate CO2 laser system to achieve 50 W intermediate focus EUV power with a Tin droplet
target.
We have achieved CE of 2.8% with solid Tin wire target by a transversely excited atmospheric (TEA) CO2 laser MOPA
system with pulse width, pulse energy and pulse repetition rate as 10~15 ns, 30 mJ and 10 Hz, respectively. A CO2 laser
system with a short pulse length less than 15 ns, a nominal average power of a few kW, and a repetition rate of 100 kHz,
based on RF-excited, fast axial flow CO2 laser amplifiers is under development. Output power of about 3 kW has been
achieved with a pulse length of 15 ns at 130 kHz repletion rate in a small signal amplification condition with P(20) single
line. The phase distortion of the laser beam after amplification is negligible and the beam can be focused to about 150&mgr;m
diameter in 1/e2. The CO2 laser system is reported on short pulse amplification performance using RF-excited fast axial
flow lasers as amplifiers. And the CO2 laser average output power scaling is shown towards 5~10 kW with pulse width
of 15 ns from a MOPA system.
Laser produced plasma is the candidate for high quality, 115 W EUV light source for the next generation lithography. Cost effective laser driver is the key requirement for the realization of the concept as a viable scheme. A CO2 laser driven LPP system with a Xenon or Tin droplet target, is therefore a promising light source alternative. We are developing a high power and high repetition rate CO2 laser system to achieve 10 W intermediate focus EUV power. High conversion efficiency (CE) from the laser energy to EUV in-band energy, is the primarily important issue for the concept to be realized. Experimental and numerical simulation analysis of a Xenon plasma target shows that a short laser pulse less than 15 ns is necessary to obtain high CE by a CO2 laser. This paper describes on the development of a CO2 laser system with a short pulse length less than 15 ns, a nominal average power of a few kW, and a repetition rate of 100 kHz based on RF-excited, axial flow CO2 laser amplifiers. Output power of 1 kW has been achieved with a pulse length 15 ns at 100 kHz repletion rate in a small signal amplification condition. The phase distortion during the amplification is negligible and the beam is focused down to 100μm diameter onto a fast Xenon jet. The conceptual design of the CO2 laser system for LPP EUV light source, and amplification performance in short pulse using RF-excited axial flow laser as amplifiers, are reported. Additional approach to increase the amplification efficiency is discussed.
A CO2 laser driven Xe droplet plasma is presented as a light source for EUV lithography. A short-pulse TEA CO2 master oscillator power amplifier system and a pre-pulse Nd:YAG laser were used for initial experiment with 0.6% of CE from a Xe jet. A target technology is developed for high average power experiments based on a Xe droplet at 100kHz. Magnetic field ion mitigation is shown to work well in the pre-pulsed plasma combined with a CO2 laser main pulse. This result is very promising with respect to collector mirror lifetime extension by magnetic field mitigation. A master oscillator power amplifier (MOPA) CO2 laser system is under development with a few kW and 100 kHz repetition rate with less than 15ns laser pulse width using a waveguide Q-switched CO2 laser oscillator and RF-excited fast axial flow CO2 laser amplifiers.
Laser produced plasma EUV source is the candidate for high quality, 115 W EUV light source for the next generation lithography. Cost effective laser driver is the key requirement for the realization of the concept as a viable scheme. A CO2 laser driven LPP system with a Xenon droplet target is therefore a promising light source alternative for EUV. We are developing a high power and high repetition rate CO2 laser system to achieve 10 W intermediate focus EUV power.
High conversion efficiency (CE) from the laser energy to EUV in-band energy is the primarily important issue for the concept to be realized. Numerical simulation analysis of a Xenon plasma target shows that a short laser pulse less than 15 ns is necessary to obtain a high CE by a CO2 laser. This paper describes on the development of a CO2 laser system with a short pulse length less than 15 ns, a nominal average power of a few kW, and a repetition rate of 100 kHz, based on RF-excited, axial flow CO2 laser amplifiers.
Output power of 1 kW has been achieved with a pulse length 15 ns at 100 kHz repletion rate in a small signal amplification condition with P(20) single line. The CO2 laser system is reported on the conceptual design for a LPP EUV light source, and amplification performance in CW and short pulse using RF-excited axial flow lasers as amplifiers. Additional approach to increase the amplification efficiency is discussed.
A CO2 laser driven Xe jet plasma is presented as light source system for EUV lithography. A short-pulse TEA C02 master oscillator power amplifier system and a pre-pulse Nd:YAG laser were used for plasma generation. The dependence of EUV plasma parameters, e.g. conversion efficiency, plasma image and in-band and out-of-band spectra, on the delay time between the pre-pulse and the main pulse laser was investigated. A maximum conversion efficiency of 0.6 % was obtained at a delay time of about 200 ns. In addition, characteristics of fast ions were measured by the time-of-flight method. The peak energy of the fast ion energy distribution decreased significantly at delay times larger than 200 ns. This result is very promising with respect to collector mirror lifetime extension by magnetic field mitigation.
Laser produced plasma EUV source is the candidate for high quality, 115 W EUV light source for the next generation lithography. Cost effective laser driver is the key requirement for the realization of the concept as a viable scheme. A CO2 laser driven LPP system with a Xenon droplet target is therefore a promising light source alternative for EUV. We are developing a high power and high repetition rate CO2 laser system to achieve 10 W intermediate focus EUV power. High conversion efficiency (CE) from the laser energy to EUV in-band energy is the primarily important issue for the concept to be realized. Numerical simulation analysis of a Xenon plasma target shows that a short laser pulse less than 15 ns is necessary to obtain a high CE by a CO2 laser. This paper describes on the development of a CO2 laser system with a short pulse length less than 15 ns, an average power of a few kW, and a repetition rate of 100 kHz based on RF-excited, axial flow CO2 laser modules. Various issues are reported on the laser system design, namely l00W seeder, parasitic oscillation suppression, small signal gain and saturation fluence, and beam quality. Additional approach to increase the amplification efficiency is discussed.
Acknowledgement: This work was supported by NEDO.
The status of the next generation lithography laser produced plasma light source development at EUVA is presented. The light source is based on a Xenon jet target and a Nd:YAG driver laser. The laser, having a master oscillator power amplifier (MOPA) configuration, operates at 10 kHz repetition rate and generates an average output power of 1.5 kW. The fwhm pulsewidth is 6 ns. The EUV system currently delivers an average EUV source power of 9.1 W (2% bandwidth, 2π sr) with a conversion efficiency of 0.6 %. Based on the development it is concluded that solid-state Nd:YAG laser technology can be cost efficiently used to produce 10 W level EUV light sources. In order to generate an average power of 115 W for a future extreme ultraviolet (EUV) light source, however, the cost of a Nd:YAG based LPP source will be too high. Therefore RF-CO2 laser technology will be used. The designed CO2 driver laser system has a MOPA configuration. The oscillator has ns-order pulsewidth and the laser system operates at a repetition rate of 100 kHz. Due to its inert cleanliness Xenon droplets will be the target material.
New light source technology for ArF lithography under 65nm node is introduced. That is “GigaTwin” platform based on “Injection Lock” technology. The new product named GT40A is 60W (4000Hz, 15mJ), 0.18pm high power ultra narrowed ArF laser. The “Injection Lock” technology provides higher performance and lower CoO. GT40A has enabled the target of more than 60ns pulse duration by natural long pulse and optical pulse stretcher. Combination of “Injection Lock” technology and Gigaphoton’s key technologies; “Higher resolution” technology, “Magnetic bearing” technology and “G-electrode” technology promise durable and reliable performance of GT40A. These technologies enable the target of chamber maintenance interval more than 12 billion pulses. The GT40A will be release into market by 4Q 2004. We introduce latest development data of GT40A, which is developed new high power “Injection Lock” laser platform for VUV/DUV lithography system.
ArF-dry microlithography is currently switching from pre-production to mass-production and the target node is shifted from 90 nm to 65 nm. ArF-wet or F2 laser lithography will then be an important player for the next generation node below 45 nm. Therefore, high throughput and high-resolution exposure tools for VUV lithography require VUV light sources (ArF and F2 lasers) with high power and narrow bandwidth. In this paper, we describe the beam quality of the new- type injection lock (MOPO, master oscillator power oscillator) ArF laser system we developed and compare it with the beam quality of a master oscillator power amplifier (MOPA) ArF laser system. A high power and narrow bandwidth ArF laser can be achieved with twin laser chambers in a MOPA or an injection lock laser configuration. Compared to the MOPA system, the injection lock laser system has an excellent performance (e.g. high efficiency, long pulse duration and narrow spectrum). On the other hand, the injection lock system has some disadvantages in beam quality showing high spatial coherence, broadband emission and having a beam profile with a hole. These technical issues have been solved, however, with the following two new breakthrough-technologies: (1) a new-type injection lock system having low spatial coherence and a beam profile with no hole and (2) the optimization of the injection seed energy and discharge timing between the twin chambers for low broadband emission. The spatial coherence, the broadband spectrum and the beam profile of the new-type injection lock system were measured with a Young’s interferometer, a wide range spectrometer with etalons and a 2-dimensional beam profiler, respectively. The new-type injection lock ArF laser system had a lower spatial coherence than a conventional injection lock system, a very low broadband emission level thus preventing deterioration of exposure tools resolution, and a beam profile with no hole. Moreover, we reconfirmed that the new-type injection lock system has the same excellent performance as the conventional injection lock system.
The roadmap of semiconductor fabrication predicts that the semiconductor market will demand 65 nm node devices from 2004/2005. Therefore, an Ultra-Line-Narrowed F2 laser for dioptric projection systems has been developed under the ASET project of “The F2 Laser Lithography Development Project”. The target of this project is to achieve a F2 laser spectral bandwidth below 0.2 pm (FWHM) and an average power of 25 W at a repetition rate of 5 kHz. The energy stability (3-sigma) target is less than 10%. Simultaneously, it is also required to establish the technology of evaluating the optical performance. An Oscillator-Amplifier arrangement at 2 kHz was developed as a first step of an Ultra-Line-Narrowed F2 laser system. With this laser system, we achieved the basic study of the synchronization technology for line narrowing operation using two system arrangements: MOPA (Master Oscillator/Power Amplifier) and Injection Locking. Based on this experience we have developed the 5 kHz system. With the 5 kHz Line-Narrowed Injection Locking system, we have achieved a spectral bandwidth of <0.2 pm with an output energy of >5 mJ and a pulse to pulse energy stability of <10%. The feasibility of a 5 kHz Ultra-Line-Narrowed F2 Laser for Dioptric Projection Systems has been demonstrated.
We have developed an ultra-line-narrowed, high-repetition-rate, high-power injection-locked F2 laser system for 157 nm dioptric projection systems under the ASET project “F2 Laser Lithography Development Project”. A spectral bandwidth of < 0.2 pm (FWHM), an output power of > 25 W, and an energy stability (3-sigma) of < 10 % at 5 kHz repetition rate was successfully obtained by using a low-power ultra-line-narrowed oscillator laser and a high-gain multi-pass amplifier laser. These parameters satisfy the requirements of exposure tools. A numerical simulation code that can simulate the spectral dynamics of the F2 laser under different operation modes such as free running operation, line-narrowed operation, and injection-locked operation, has also been developed. Using this simulation code, it is found that the instantaneous spectral bandwidth narrows monotonously during the laser pulse, and a narrower spectral output can be obtained by seeding the tail area of the line-narrowed F2 laser pulse. And the line-narrowing operation of the oscillator laser and the behavior of the injection-locked laser system can be predicted very precisely with this simulation code. The development of F2 laser for microlithography will be accelerated by this new simulation code.
The roadmap of semiconductor fabrication predicts that the semiconductor market will demand 65 nm node devices from 2004/2005. Therefore, an Ultra-Line-Narrowed F2 laser for dioptric projection systems is being developed under the ASET project 'The F2 Laser Lithography Development Project.' The target of this project is to achieve a F2 laser spectral bandwidth below 0.2 pm (FWHM) and an average power of 25W at a repetition rate of 5 kHz. Accurate measurements of the laser spectrum and of the laser wavelength stability are therefore very important. We therefore developed a VUV wavemeter with a Br-lamp to measure the absolute F2 laser wavelength. We obtained 157.631 nm for the main F2 laser transition using the Br-lamp reference lines at 157.4840 nm and 157.6385 nm. We have also developed a VUV high-resolution spectrometer to measure spectral profiles, which was calibrated by 157 nm coherent light source (157CLS). The 157CLS is a very narrow line-width, which can be approximated by delta function. The 157CLS had a line-width of 0.008 pm (Full-Width-At-Half- Maximum, FWHM) and a power of 0.1 mW. The instrument function of the high-resolution spectrometer measured by the 157CLS was 0.10 pm (FWHM). As a result, the deconvolved FWHM of the ultra-line narrowed F2 laser is 0.12 pm, the deconvolved spectral purity containing 95% of the total energy (E95) was less than 0.45 pm.
The roadmap of semiconductor fabrication predicts that the semiconductor market will demand 65 nm node devices from 2004/2005. Therefore, an Ultra-Line-Narrowed F2 laser for dioptric projection systems is currently being developed under the ASET project of The F2 Laser Lithography Development Project. The target of this project is to achieve a F2 laser spectral bandwidth below 0.2 pm (FWHM) and an average power of 25 W at a repetition rate of 5 kHz. The energy stability (3-sigma) target is less than 10%. An Oscillator-Amplifier arrangement at 2 kHz was developed as a first step of an Ultra-Line-Narrowed F2 laser system. With this laser system, we did the basic study of the synchronization technology for line narrowing operation using two system arrangements: MOPA (Master Oscillator/Power Amplifier) and Injection Locking. Based on this experience we have developed the 5 kHz system. With the 5 kHz Line-Narrowed Injection Locking system, we have achieved a spectral bandwidth of < 0.2 pm with an output energy of > 5 mJ and an energy pulse to pulse stability of 10%. The feasibility of a 5 kHz Ultra-Line-Narrowed F2 Laser for Dioptric Projection Systems has been demonstrated.
The Association of Super-Advanced Electronics Technologies (ASET) started The F2 Laser Lithography Development Project in March 2000, to clarify solutions of base F2 lithography technologies. In this project, we are developing an ultra line-narrowed F2 laser light source for exposure tools tat are employing dioptric projection optics. We have developed an intermediate engineering injection- locking laser system that has an oscillator laser and an amplifier to study the feasibility of an ultra line-narrowed F2 laser. A spectral bandwidth of <0.2pm (FWHM) at a repetition rate of 1000Hz and an average power of 14W has been achieved with this laser system. The laser output performance dependence on the relative delay between oscillator laser and amplifier is also measured.
It is predicted that the semiconductor market will demand 70 nm devices from 2004 or 2005. Hence, F2 laser microlithography systems have to be developed according to this time frame. At ASET, 'The F2 Laser Lithography Development Project' started in March 2000, as a 2-year project to fulfill this market requirement. The final target of this project is to achieve a F2 laser spectral bandwidth of 0.2 pm (FWHM) at a repetition rate of 5000 Hz and an average power of 25 W. These specifications meet the demand of dioptric projection system. We have done a feasibility study for a high efficiency line narrowing design to achieve the ultra narrow spectral bandwidth and the high output power. In addition, we have developed an intermediate engineering laser system consisting of an oscillator laser and an amplifier. With this laser system we have performed the line-narrowed operation using two arrangements: Master Oscillator Power Amplifier (MOPA) and Injection Locking. With this Oscillator-Amplifier system and have achieved a spectral bandwidth (convoluted) of FWHM <0.2 pm with both systems: MOPA and Injection Locking. The maximum output energy was >20 mJ for MOPA and >15 mJ for Injection Locked operation.
An ultra narrow line width of the F2 laser, narrower than 0.2pm, is required for a CaF2 only refractive optics exposure system. Also, a low peak laser power is needed for the extension of the optics lifetime. These ultra narrow line width and low peak power are achievable by long pulse duration. We, Association of Super-Advanced Electronics Technologies (ASET), are developing an ultra line narrowed F2 laser below 0.2pm, with 5mJ high output energy, by adopting a 2-stage F2 laser system, which consists of an oscillator and an amplifier. The oscillator for this 2-stage system is required to have an ultra narrow line width of below 0.2pm. We have developed F2 laser with very long laser pulse duration of over 65ns (Tis: the integral squire pulse width), in a free running operation. And, by installing a line-narrowing module (LNM) in this F2 laser, an ultra narrow line width of below 0.2 pm (FWHM, deconvolved) has been realized. This F2 laser was successfully used for the oscillator of 2-stage system.
We have succeeded in the development of an excimer laser with ultra narrow bandwidth applicable to high N.A. scanners targeting on the 0.13micrometers -design rule. Key word of our solution for 0.13micrometers -design rule was 'extended technologies of currently available KrF excimer laser unit. As the result we could shorten development time remarkably. The narrower the laser spectrum, the less the influence of chromatic aberration on exposure projection lens; this is a well-known fact. We have developed the technologies to achieve spectral bandwidths less than 0.5pm, 20 percent narrower than our current model G20K. In order to attain this number, the major design change was made on line narrowing module, which was redesigned to minimize the dispersion of wavelength element. In addition gas condition was fine-tuned for the new line narrowing module. Integrated energy stability has been improved within +/- 0.35 percent with 35 pulses window by the introduction of a high efficiency pules power module and a faster gas circulation system. The rest of oscillation performances and durability equate with the base model G20K. The intelligent gas control system extended gas exchange interval up to 200 million pulses or 7 days. The G20K already passed through 10 billion-pulse test. Total energy loss was within 4mJ which is small enough to be compensated by gas injection and voltage change; it is a unique compensation system of Komatsu.
In the semiconductor industry, it is one of the most important issues to reduce manufacturing cost of the semiconductor device by increasing throughput. We have succeeded in the development of the high repetition rate excimer laser technology, and obtained the prospect of low CoO of the laser device. In this paper, we present the performance and advanced technologies of the newest model of the KrF excimer laser for microlithography; KLES-G20K. The laser achieves 20 W of output power with 0.6 pm bandwidth at 2 kHz. The pulse to pulse energy stability, 3 sigma is less than 6 percent and integrated energy stability is within +/- 0.4 percent. By our estimation, more than 50 percent of CoO of the laser device is cut by adopting developed machine compared to a present one.
We present the performance and durability of the newest model of the KrF excimer laser for microlithography KLES-G10K. The laser achieves 10 W of output power with 0.7 pm bandwidth at 1000 Hz with newly developed solid state pulsed power module and the high precise narrowing module. The durability of laser tube achieves 5 billion pulses with the new radio frequency preionization scheme, which reduces consumption of fluorine gas and maintenance of laser tube drastically.
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