Relationship between localized wafer shape changes induced by residual stress and overlay errors

Abstract

The deposition of films with nonuniform residual stress can induce local changes in wafer shape and contribute to overlay errors with magnitudes that may be significant in advanced lithographic patterning processes. Understanding the fundamental relationship between residual stress, localized wafer shape changes, and overlay error is crucial for realizing new schemes to manage overlay errors, particularly at advanced nodes where feature sizes are smaller. In the present work, finite element modeling is used to quantitatively relate nonuniform residual stress in a deposited thin film to localized wafer shape changes and overlay errors. The results demonstrate that there is a strong correlation between localized shape variations induced by nonuniform residual stresses and noncorrectable overlay errors.