Study of OPC for AAPSM reticles using various mask fabrication techniques

AAPSM masks require OPC correction through pitch in order to print a linear dark line response vs the design CDs. The masks also require correction for the clear intensity imbalance caused by the phased etched Qz wall edge. The clear intensity can be balanced by two approaches;(or a combination of the two) data biasing or wet undercut etching of the Qz etched opening. IC manufacturers would like to use one OPC model that will work for any mask fabrication approach. This paper shows that there is no OPC difference observed in either the aerial image or the printed image of several OPC learning patterns. The study includes CD through pitch for dense (1:1) L/S Patterns and Isolated Line CD vs line-space ratio. The images were analyzed for the dark line linearity, the clear CD balance though pitch, and the clear CD balance with focus (phase error effects -PES).