90nm node contact hole patterning through applying model based OPC in KrF lithography

Abstract

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.