As semiconductor technologies move toward 90nm generation and below, contact hole is one of the most challenging
features to print in the semiconductor manufacturing process. There are two principal difficulties in order to define small
contact hole pattern on wafer. One is insufficient process margin besides poor resolution compared with line & space
pattern. The other is that contact hole should be made through pitches and sometimes random contact hole pattern should
be fabricated. Therefore advanced ArF lithography scanner should be used for small contact hole printing with RETs
(Resolution Enhancement Techniques) such as immersion lithography, OPC(Optical Proximity Correction), PSM(Phase
Shift Mask), high NA(Numerical Aperture), OAI(Off-Axis Illumination), SRAF(Sub-resolution Assistant Feature), mask
biasing and thermal flow. Like this, ArF lithography propose the method of enhancing resolution, however, we must
spend an enormous amount of CoC(cost of ownership) to utilize ArF photolithography process than KrF.
In this paper, we suggest the method of contact holes patterning by using KrF lithography tool in 90nm sFlash(stand
alone Flash)devices. For patterning of contact hole, we apply RETs which combine OAI and Model based OPC.
Additionally, in this paper we present the result of hole pattern images which operate ArF lithography equipment. Also,
this study describes comparison of two wafer images that ArF lithography process which is used mask biasing and Rule
based OPC, KrF lithography process which is applied hybrid OPC.