In this paper we present a status update of the exposure tool developments for sub 65 nm CD's. Main development path is 157-nm lithography. ASML follows a two step approach volume will be presented.Step 1 is based on the Micrascan step and scans platform and step 2 is based on the TWINSCAN platform. The progress of the development and first results on prototypes are discussed. This includes optics, purging, and pellicle status. The impact of CaF 2 birefringence (intrinsic and stress induced) on lens performance is evaluated. Experimental data on optical path purging is presented. The pellicle status is reviewed, and results of hard pellicle testing in KrF scanners are presented. For the Micrascan system, first imaging and overlay results are presented.
SVG Lithography (SVGL) has established and is executing a comprehensive program for the development of an advanced 157nm Lithography Exposure System capable of processing 7Onm critical dimensions for three years now. This paper presents the approach, and details the present state of the challenges in the development of 1 57nm lithography. It also describes the SVGL 157nm program approach and provides some insight into the progress made to date addressing the challenges. Specific attention is paid to addressing 3 critical areas: Molecular contamination/purging, optical coating, and optical surfacing.
This keynote paper looks at the window of opportunity for 157nm lithography. The issues and challenges of the new 157nm lithography are identified and reviewed in the context of optical scanning system development. Major developments associated with the solution to problems are detailed: Optical material development; birefringence of optical materials; convergence of optics designs; contamination purging; and 157nm laser illumination. Micrascan VII and AT systems are highlighted.Resolution performance is projected against the Semiconductor Industry Association Roadmap. Both measured data as well as predictions of system performance are given. The window of opportunity for 157nm lithography is confirmed.
Grading the refractive index period of a rugate is a technique for depositing broad band reflectors using rugate technology. The principle advantage of this technique is the ability to deposit long and short pass reflectors in parallel with other rugate spectral features and thus generate complex performance in a single optical film. Variation of the amplitude of the index profile as the period is changed allows for good edge definition for long or short pass designs. Several of these devices were fabricated and measured performance is presented. These devices demonstrate rugate properties of harmonic suppression and superposition with other rugate structures.
Optical thin films generated by the co-deposition of two or more materials exhibit a refractive index proportional to the indices of the components in proportion to the mixing ratio. The coevaporation of Ti2O3 and SiO requires strict control of rates and chamber environmental parameters to maintain proper stoichiometry and film performance. Films are oxidized to TiO2 and SiO2 at the substrate. A broad-band photometer monitors film development in the visible region. Photometer scans are acquired by the control computer every 10 seconds. Film absorption, index, and optical thickness are found to be sensitive to rate as well as trace amounts of water vapor. Absorption is due to unconverted SiO, and although the film will convert on chamber venting or a post bake, absorption inhibits reliable interpretation of photometer results. Reliable results are achieved by using a rule-based computer algorithm during source ramp-up and rate stabilization to verify system readiness. Environmental parameters are compared to a data base of previous runs to verify normal status. Photometer scans and scan-to-scan differences are checked for normal behavior. Computer rules are performance goal-oriented, and system status is weighed against the desired film spectral performance.
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