Dense lines created by spacer DPT scheme: process control by local dose adjustment using advanced scanner control

In this paper we present a methodology to investigate and optimize the CD balance between the four features of a final 32nm lines and space pattern created by spacer pitch doubling. Metrology (SEM and scatterometry) was optimized to measure and separate the two lines and the two spaces of the 32nm features. In case a space unbalance emerged during the various processing steps such as etch and deposition, this was compensated by calculating and feed-back local dose offsets to the scanner. For the spacer process used in this study we observe 20..40% improvement in space CDU and space balance, when applying the dose corrections.