Substantial progress was reflected in several of the 65 presentations made during the symposium. In the pellicle arena, a soft polymer membrane material looks promising. Now, in addition to the transmissivity, the reliability looks positive as well. Samples are being sent to MIT Lincoln Laboratories' characterization facility for evaluation. As an added bonus, a backup material may have been identified in the form of a hard membrane, a modified fused silica material.
Results appear encouraging.
A year ago, the prospect of developing a thin, single-layer resist with adequate etch resistance looked doubtful, requiring considerable invention, according to Harbison. However, a couple of suppliers presented positive data identifying a feasible platform, the fundamental chemistry for 157 nm lithography. Once the likelihood of nitrogen purging to O 2 levels 2 cube required for catadioptic systems seemed improbable. While there are indications all suppliers plan to use a catadioptic design, combining reflective and refractive optics, there are various approaches. The use of a CaF 2 beamsplitter to effectively reduce beam path and system footprint is just one approach.