Improvement of Pattern-to-Pattern Critical Dimension Variation by Model Based Method in Gate Polycrystalline Silicon Etching Process

Abstract

In this study, we investigated the dependence of critical dimension (CD) bias on pattern dimension (width, space and pitch) in detail and quantitatively in gate etch process. The mechanism of CD bias dependence was estimated from the characteristic of each etching step. Based on the etching mechanism, the numerical model was generated by using linear combination of functions of pattern dimension which have strong correlation to CD bias dependence. For the purpose of improving the pattern-to-pattern gate CD variation, the correction of line width of mask was carried out to compensate CD bias dependence by using this model. This model accurately predicted CD bias dependence, and pattern-to-pattern CD variation was improved in gate etch process successfully.