Advanced Overlay: Sampling and Modeling for Optimized Run-to-Run Control

In recent years overlay control schemes have become more complicated in order to meet the ever shrinking margins of advanced technology nodes. As a result, new challenges must be addressed for effective run-to-run overlay control. Two of these challenges are addressed in this study by new advanced analysis techniques: (1) sampling optimization for run-to-run control; and (2) bias-variance tradeoff in modeling. The sampling and modeling solutions proposed are validated by APC simulations to estimate run-to-run performance, lot-to-lot and wafer-to-wafer model term monitoring to estimate stability, and ultimately high volume manufacturing tests to monitor on-product overlay by densely measured overlay data.

 

ADDITIONAL ARTICLES

Through Pellicle Defect Inspection of EUV Masks using an ArF Based Inspection Tool

The use of EUV photomasks in a semiconductor manufacturing environment requires their periodic inspection to ensure they are continually free of defects that could impact device yield. The proposed use of a polycrystalline-based EUV pellicle to prevent fall-on particles would preclude periodic through-pellicle mask defect inspection using e-beam and DUV inspection tools. To use these types of defect inspection tools would require removal of the EUV pellicle before inspection. An alternate EUV pellicle material has been developed that is semi-transparent to 193nm wavelengths, thus allowing through-pellicle inspection using existing ArF-based mask inspection tools, thereby eliminating the need to remove the pellicle for defect inspection. In this work, we will conduct an initial evaluation of through-pellicle EUV mask defect inspection using an existing 193nm mask inspection tool.

 

ADDITIONAL ARTICLES