Complicated Signal Processing Methods for Very Deep Sub-micro (VDSM) Poly Etching Endpoint Detection

Difficulties in VDSM poly gate etching process was summarized firstly. Secondly, traditional endpoint detection techniques of optical emission spectroscopy (OES) and interferometer endpoint detection (IEP) were introduced in detail. At last, by constructing new endpoint detection system, and applying multi-robust algorithms, the endpoint is pre-found for the patterned 90 nm wafers which expected give very important guidance to the endpoint detection of sub-90 nm VDSM etching process.