This paper describes an anti-reflective layer (ARL) suitable for use in sub-half-micron and quarter-micron KrF excimer laser lithography. Advantages of the new anti-reflective layer include improved critical dimension (C.D.) control with the resist thickness and reduction of notching caused by reflection from the substrate. In contrast to a well-known anti-reflective coating (ARC) 1,2,3,4 is applied by spin coating, we studied amorphous carbon (a-C:H) film which we applied by plasma-enhanced chemical vapor deposition (PECVD). The new film has two major advantages: Its thickness is topographically conformal thanks to the CVD method, and it can be ashed together with the resist because it is an organic film. We determined the most suitable conditions for forming the a-C:H film, by experimental measurements of refractive index n and extinction coefficient k and by varying parameters in simulations. An a-C:H film only 350 Å thick provided sufficient protection against reflection and had a higher exposure/focus latitude than conventional films.

Date Published: 1 June 1992
PDF: 12 pages
Proc. SPIE 1674, Optical/Laser Microlithography V, (1 June 1992); doi: 10.1117/12.130334

Published in SPIE Proceedings Vol. 1674:
Optical/Laser Microlithography V
John D. Cuthbert, Editor(s)