A Study of 65nm Silicon Etch

Abstract

The control of shallow trench isolation (STI) depth uniformity and poly gate profile necessitates the combination of more advanced silicon etch methodologies, in-situ measurements, and various relevant integration schemes. This paper presents a study of the difficulties and corresponding solutions in 65nm silicon etch with respect to process development and mass production. In the development phase, the STI trench profile and the depth uniformity of the STI depth can be well controlled by etch recipe tuning. In the mass production phase, we need to extend additional focus on the impact from different products on the inter-field variation of STI depth. Results show a good correlation of the depth to the pattern density variation. Such relationship has been utilized in feed-forward mode to deliver a robust process control. In addition, we also address the influence of oxide variation in STI fabrication and STI step height difference on the corresponding poly gate profile and the pits defects.