Takushi Motoyama

New antireflective layer for deep-UV lithography

ABSTRACT 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 ofnotching caused by reflection from the substrate. In contrast to a well-known anti-reflective coating (ARC) 1,2,3,4is applied by spin coating, we studied amorphous carbon (a-C:H) filmwhich we applied by plasma-enhanced chemical vapor deposition (PECYD). The new film has two major advantages: Its thickness is topographically conformal thanks to the CVDmethod, and it can be ashed together with the resist because it is an organic film. Wedetermined 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 350A thick provided sufficient protection against reflectionand had a higher exposure/focus latitude than conventional films.

Dry development of the top imaging layer for bilayer system in the down stream of O2/CF4 plasma

We investigated dry-develop resist as the top layer in a bilayer system. The resist consisted of polyacetylene with silicon atoms, PTMDSO (poly 4,4,7,74etramethyl-4,7-disila- 2-octyne) as a base polymer, and a phenyl azide as a photosensitive addition agent. 0.30 pm line and space negative patterns were resolved, when the resist exposed using a KrF excimer laser stepper system was developed in the down stream of 02/CF4 plasma. The sensitivity was around 100 mJ/cm2 and the oxygen plasma resistance was about 50 times greater than that of novolak resist.