Since the early 1980's, the resolution of optical projection lithography has improved dramatically primarily due to three factors: increases in projection lens numerical aperture, reduction of the imaging source wavelength, and continued reduction of the k1 factor. These three factors have been enabled by the concurrent improvements in lens making technology, DUV light sources, photoresist technology, and resolution enhancement techniques. The DUV light source, excimer KrF and ArF lasers, has entered main stream production and now images more than 50% of the critical layers in today's leading edge devices. Looking forward to both immersion lithography and beyond to EUV lithography, new light source technologies must be created to enable the continued progression of shrinking feature sizes embodied by Moore's law.
Semiconductor chip manufacturing is on the verge of a new production process node driving critical feature sizes below 100 nm. The next generation of 193 nm Argon Fluoride laser, the NanoLithTM 7000, has been developed in response to this recent technology development in the lithography industry. The NanoLithTM 7000, offering 20 Watts average output power at 4 kHz repetition rate, is designed to support the highest exposure tool scan speeds for maximum productivity and wafer throughput. Technology improvements to support the move from pilot production to full production will be described. With core technology defined and performance to specification established, attention turns to cost of operation, which is closely tied to module lifetime and reliability. Here we present results of the NanoLithTM 7000 system lifetest tracking all optical performance data over a 4.4 Billion shot. The system is operated in firing modes ranging from 1-4 kHz, and up to 75% duty cycle. Overall system performance measured to date both in the lab and in the field suggests that this laser meets all the production requirements for 193 nm lithography.
The next generation 193 nm (ArF) laser has been designed and developed for high-volume production lithography. The NanoLithTM 7000, offering 20 Watts average output power at 4 kHz repetition rates is designed to support the highest exposure tool scan speeds for maximum productivity and wafer throughput. Fundamental design changes made to the laser core technologies are described. These advancements in core technology support the delivery of highly line-narrowed light with <EQ 0.35 pm FWHM and <EQ 0.95 pm at 95% included energy integral, enabling high contrast imaging from exposure tools with lens NA exceeding 0.75. The system has been designed to support production lithography, meeting specifications for bandwidth, dose stability (+/- 0.3% in 20 ms window) and wavelength stability (+/- 0.05 pm average line center error in 20 ms window) across 2 - 4 kHz repetition rates. Improvements in optical materials and coatings have led to increased lifetime of optics modules. Optimization of the discharge electrode design has increased chamber lifetime. Early life-testing indicates that the NanoLithTM core technologies have the potential for 400% reduction of cost of consumables as compared to its predecessor, the ELX-5000A and has been discussed elsewhere.
Fused silica samples from seven different suppliers were exposed at low fluence; nominally 0.1 mJ/cm2, for tens of billions of pulses. These materials are used in the manufacture of projection and other optics needed for DUV microlithography. The fluence level chosen for the exposures was intended to be close to that seen by some of the critical lenses in the projection assembly. Rather than the 'compaction' reported by many workers, most of the samples exhibited the opposite effect. The reduction of optical path by DUV radiation or 'rarefaction', as we have called it, is a physical phenomenon not known or published previous to our work. Dat and experimental conditions are presented which will hopefully lead to the ultimate full understanding of the rarefaction process.
Advances in optical coating and materials technology have made possible the development of instruments with substantially improved efficiency in the extreme ultraviolet/far ultraviolet (EUV/FUV) spectral region. For example, the development of chemical vapor deposited (CVD) SiC mirrors provides an opportunity to extend the range of normal incidence instruments down to 60 nm. The EUV performance and some applications of optical coatings including MgG2 protected aluminum, CVD- SiC, SiC films, boron carbide films, and multilayer coatings will be discussed. Contamination sensitivity and cleaning will be addressed.
Ion-beam-deposited boron carbide thin films have been produced and evaluated as normal- incidence, reflective coatings in the extreme ultraviolet. Reflectances of over 28% were obtained for wavelengths longer than 58 nm and as high as 38.6% at 92 nm, for a freshly deposited coating. Optical constants of sputtered boron carbide were calculated from experimental observations using the reflectance-versus-angle method. X-ray photoelectron spectroscopy analysis of the deposited film was performed in order to investigate its chemical composition and effects on the long-term stability of the coating's reflectivity.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.