RECTANGULAR CONTACT LITHOGRAPHY FOR CIRCUIT PERFORMANCE IMPROVEMENT

Abstract

An optical lithography method is disclosed that uses double exposure of a reusable a chromeless alternating phase-shifting template mask and a binary trim mask to fabricate regularly-placed rectangular contacts in standard cells of application-specific integrated circuits (ASICs). A first exposure of the reusable chromeless alternating phase-shifting template ask forms periodic dark lines on a wafer and a second exposure of binary tri mask remove the unwanted part of the dark lines and the small cuts of the dark lines left form the rectangular-placed contacts. All contacts are placed regularly in one direction while randomly in the perpendicular direction. The method of the invention can be used in the fabrication of standard cells in application-specific integrated circuits (ASICs) to decrease circuit area an improve circuit performance.