Radiation imagery chemistry: process – composition – or product th – Radiation modifying product or process of making – Radiation mask
Patent
1999-01-11
2000-11-21
Rosasco, S.
Radiation imagery chemistry: process, composition, or product th
Radiation modifying product or process of making
Radiation mask
G03F 900
Patent
active
061500607
ABSTRACT:
A transmission lithography mask that utilizes a transparent substrate or a partially transparent membrane as the active region of the mask. A reflective single layer or multilayer coating is deposited on the membrane surface facing the illumination system. The coating is selectively patterned (removed) to form transmissive (bright) regions. Structural imperfections and defects in the coating have negligible effect on the aerial image of the mask master pattern since the coating is used to reflect radiation out of the entrance pupil of the imaging system. Similarly, structural imperfections in the clear regions of the membrane have little influence on the amplitude or phase of the transmitted electromagnetic fields. Since the mask "discards," rather than absorbs, unwanted radiation, it has reduced optical absorption and reduced thermal loading as compared to conventional designs. For EUV applications, the mask circumvents the phase defect problem, and is independent of the thermal load during exposure.
REFERENCES:
patent: 5279925 (1994-01-01), Berger et al.
patent: 5472811 (1995-12-01), Vasudev et al.
patent: 5514499 (1996-05-01), Iwamatsu et al.
patent: 5935737 (1999-08-01), Yan
patent: 5962174 (1999-10-01), Pierrat
Carnahan L. E.
Grzybicki Daryl S.
Rosasco S.
The Regents of the University of California
Thompson Alan H.
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