Takahito Kumazaki

Femtosecond extreme-ultraviolet quasi-continuum generation by an intense femtosecond Ti:sapphire laser

A femtosecond broadband extreme-ultraviolet quasi-continuum was generated by an intense femtosecond Ti:sapphire laser by two nonlinear optical processes. The first process is the generation of the broadband harmonics by focusing the blueshifted laser pulse through a rare gas. The spectral blueshift is caused by self-phase modulation owing to ionization of the target gas. The second process is the generation of broadband even-order harmonics by the superposition of the second-harmonic electric field upon the fundamental.

Power up: 120 Watt injection-locked ArF excimer laser required for both multi-patterning and 450 mm wafer lithography

193nm ArF excimer lasers are widely used as light sources for the lithography process of semiconductor production. At first, ArF excimer lasers have been used in semiconductor productions at the 90nm node and recently ArF excimer lasers have begun to be used for the 32nm node, by the progress in the immersion technology and the double-patterning technology. Furthermore, considering current status of development of the lithography technology using a next-generation light source, or extreme ultraviolet (EUV) light source, the start of mass production with the next-generation light source is estimated to start from 2015. Therefore, there is a need for extension of 193nm immersion lithography technology. By using the multi-patterning and double-patterning technology, design rules below limit at single exposure is possible. However, throughput is reduced due to increased lithography processes. In order to improve a decrease in throughput, a high power ArF excimer laser and larger size wafer (450mm in diameter) is needed. We have developed a new high power laser with the concept of eco-friendly. In this paper, we will introduce technologies used for our latest ArF excimer laser having tunable output power between 90W and 120W and report its performance data.

Reliable high power injection locked 6 kHz 60W laser for ArF immersion lithography

Reliable high power 193nm ArF light source is desired for the successive growth of ArF-immersion technology for 45nm node generation. In 2006, Gigaphoton released GT60A, high power injection locked 6kHz/60W/0.5pm (E95) laser system, to meet the demands of semiconductor markets. In this paper, we report key technologies for reliable mass production GT laser systems and GT60A high durability performance test results up to 20 billion pulses.

The ArF laser for the next-generation multiple-patterning immersion lithography supporting green operations

Multiple patterning ArF immersion lithography has been expected as the promising technology to satisfy tighter leading edge device requirements. One of the most important features of the next generation lasers will be the ability to support green operations while further improving cost of ownership and performance. Especially, the dependence on rare gases, such as Neon and Helium, is becoming a critical issue for high volume manufacturing process. The new ArF excimer laser, GT64A has been developed to cope with the reduction of operational costs, the prevention against rare resource shortage and the improvement of device yield in multiple-patterning lithography. GT64A has advantages in efficiency and stability based on the field-proven injection-lock twin-chamber platform (GigaTwin platform). By the combination of GigaTwin platform and the advanced gas control algorithm, the consumption of rare gases such as Neon is reduced to a half. And newly designed Line Narrowing Module can realize completely Helium free operation. For the device yield improvement, spectral bandwidth stability is important to increase image contrast and contribute to the further reduction of CD variation. The new spectral bandwidth control algorithm and high response actuator has been developed to compensate the offset due to thermal change during the interval such as the period of wafer exchange operation. And REDeeM Cloud™, new monitoring system for managing light source performance and operations, is on-board and provides detailed light source information such as wavelength, energy, E95, etc.

The next-generation ArF excimer laser for multiple-patterning immersion lithography with helium free operation

Multiple patterning ArF immersion lithography has been expected as the promising technology to satisfy tighter leading edge device requirements. A new ArF excimer laser, GT64A has been developed to cope with the prevention against rare resource shortage and the reduction of operational costs. GT64A provides the sophisticated technologies which realize the narrow spectral bandwidth with helium free operation. A helium gas purge has usually been employed due to the low refractive index variation with temperature rises within a line narrowing module(LNM). Helium is a non-renewable resource and the world’s reserves have been running out. Nitrogen gas with an affordable price has been used as an alternative purge gas of helium on the restrictive condition of low thermal loads. However, the refractive index variation of nitrogen gas is approximately ten times more sensitive to temperature rises than that of helium, and broadens a spectral bandwidth in the high duty cycle operations. The new LNM design enables heat effect in laser shooting at optical elements and mechanical components in the vicinity of an optical path to be lower. This reduces thermal wavefront deformation of a laser beam without helium gas purge within LNM, and narrows a spectrum bandwidth without helium purge. Gigaphoton proved that the new LNM enabled E95 bandwidth without control to improve a lot with nitrogen purge.

Technology for monitoring shot-level light source performance data to achieve high-optimization of lithography processes

Gigaphoton has developed a new monitoring system that provides shot-level light source performance data to FDC systems during exposure time. The system provides basic monitoring data (e.g. Energy, Wavelength, Bandwidth, etc.) and beam performance data, such as Beam Profile, Pointing, Divergence, Polarization can also be monitored using a new metrology tool called the Beam Performance Monitor (BPM) module. During exposure time the system automatically identifies the start and end timing of the wafer and each shot based on the burst of firing signals from the scanner, and stores the measured data in sequence. The stored data is sorted by wafer or by shot, and sent to REDeeM Piece which in turn converts the data to the users protocol and send it to the FDC system. The user also has the option to directly view or download the stored data using a GUI. Through this monitoring system, users can manage light sources data at the shot or reticle level to facilitate optimization of performance and running cost of the light source for each process. This monitoring system can be easily retrofitted to Gigaphotons current ArF laser light sources. The beam splitter of the BPM was specially designed to bend only a small fraction of the source beam, so we are able to simply install the BPM without the need for special optical alignment.

Extremely long life and low-cost 193nm excimer laser chamber technology for 450mm wafer multipatterning lithography

193nm ArF excimer lasers are widely used as light sources for the lithography process of semiconductor production. 193nm ArF exicmer lasers are expected to continue to be the main solution in photolithography, since advanced lithography technologies such as multiple patterning and Self-Aligned Double Patterning (SADP) are being developed. In order to apply these technologies to high-volume semiconductor manufacturing, the key is to reduce the total operating cost. To reduce the total operating cost, life extension of consumable part and reduction of power consumption are an important factor. The chamber life time and power consumption are a main factor to decide the total operating cost. Therefore, we have developed the new technology for extension of the chamber life time and low electricity consumption. In this paper, we will report the new technology to extend the life time of the laser chamber and to reduce the electricity consumption.

A reliable higher power ArF laser with advanced functionality for immersion lithography

193nm ArF eximer lasers are expected to continue to be the main solution in photolithography, since advanced lithography tecnologies such as Multiple patterning and Self-aligned double patterning (SADP) are being developed. In order to appliy these tecnologies to high-volume semiconductor manufactureing, the key is to contain chip manufactureing costs. Therefore, improvement on Reliability, Availability and Maintainability of ArF excimer lasers is important.[1] We works on improving productivity and reducing downtime of ArF exmer lasers, which leads to Reliability, Availability and Maintainability improvemnet. First in this paper, our focus drilling tecnique, which increases depth of focus (DoF) by spectral bandwidth tuning is introdueced. This focus drilling enables to increase DoF for isolated contact holes. and it not degrades the wafer stage speed.[2] Second, a technique which eables to reduce gas refill time to zero is introduced. This technique reduces downtime so Availavility is expected to improve. In this paper, we report these tecniques by using simulation resutls and partially experimental resutls provided by a semiconductor manufacturer.

Ultra-line-narrowed F 2 laser for microlithography

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.

Extremely long life excimer laser technology for multi-patterning lithography

Multi-patterning techniques with ArF immersion lithography is expected to continue as main solution for manufacturing IC chips. The reduction of laser downtime has great impact on the productivity of chipmakers. The laser downtime is closely related to the lifetime of consumable parts of the laser. Gigaphoton developed new laser modules, chamber and LNM (Line Narrowing Module) which have longer lifetime than current one. New chamber demonstrated 1.2 times longer lifetime than current chamber. New LNM demonstrated 1.8 times longer lifetime than current LNM. These new modules will help to reduce the downtime of the laser.