Ralf Takke

KrF-excimer-laser-induced absorption and fluorescence bands in fused silica related to the manufacturing process

Transient and permanent UV absorption bands and fluorescence bands induced by 248 nm excimer laser radiation in fused silica are reported. It is shown that the permanent absorption measurements are not suitable to characterize the material with respect to transmission of high power laser pulses. In fused silica samples with high OH - content recovery of the 210 nm absorption band is observed after the end of irradiation. In samples with low OH - content no quick re covery is observed. 1 .

Modified fused silica for 157-nm mask substrates

The 1999 SIA roadmap predicts a severe acceleration of the reduction of feature sizes down to 100 nm in 2003 and further down to 70 nm in 2005, respectively. One of the most promising candidates to achieve this demanding goal is the 157 nm optical microlithography. But today there are still many uncertainties whether this technology will be ready in time for the semiconductor industry. The material for the mask substrates, for example is regarded as one of the potential showstoppers for this generation of optical microlithography. For present generations of optical microlithography (i-line, DUV and 193 nm) fused silica is the material of choice for mask substrates. Its superior mechanical, thermal and optical properties make it an ideal substrate material.

State of the Art Optical Materials for Lithographic Systems for Semiconductor Manufacturing

193 nm lithography has enabled semiconductor manufacturing to achieve nm resolution. Highest quality optical materials and optics are an essential part of this. Important optical properties of and test methods for these materials will be reported.