Matching Poly Layer ADI and AEI Process Windows by Using ADI Index

摘要

As the critical-dimension of IC devices shrinks to below 90nm, it becomes very important to find an approach to control AEI CD more efficiently. This is especially so for poly gate patterning where not only photoresist dimension but also the photoresist profile plays an important role in defining final CD due to the impact of the photoresist profile on the etch process. In this paper, we will introduce an ADI index, which includes both CD and profile information collected by scatterometry system (KLA-Tencor SCD). With this ADI index, we can match the ADI process window with the AEI process window (exposure and focus window), and final AEI CD can be accurately predicted. This approach can also be effectively used in feed-forward Advanced Process Control (APC) poly patterning.