A scatterometry-based CD uniformity control solution for Spacer Patterning Technology

Improving Critical Dimension Uniformity (CDU) for spacer double patterning features is a high priority for double patterning technology. In spacer double patterning the gaps between the spacers are established through various processes (litho, etch, deposition) with different process fingerprints and the CDU improvement of these gaps requires an improved control solution. Such a control solution is built upon two pillars: metrology and a control strategy. In this paper Spacer Patterning Technology CDU control using an angle resolved scatterometry tool is evaluated. CD results obtained with this scatterometer on CDU wafers are measured and the results are correlated with those from the traditional CD-SEM. CD wafer fingerprints are compared before and after applying the advanced control strategy and CDU improvements are reported. Based on the results it is concluded that scatterometry qualifies for a spacer process CDU control loop in a manufacturing environment.