Chamber maintenance and fault detection technique for a gate etch process via self-excited electron resonance spectroscopy

Abstract

With the introduction of 300mm wafer and sub-100nm technology processes, semiconductor manufacturers are gradually paying attention to efficient methods for process and equipment control, which is conventionally called advanced process control (APC) and advanced equipment control (AEC). As a potential strategy, an APC∕AEC technique by self-excited electron resonance spectroscopy (SEERS) was evaluated in a dynamic random access memory gate etch process, in terms of chamber maintenance and process control. Small changes in the chamber conditions after wet cleaning, which could not be detected under conventional monitoring methods, were identified by analyzing the electron collision rate of plasma. This event justifies that plasma monitoring is inevitable in chamber maintenance, especially considering that process results gradually tend to be affected by even small chamber changes in sub-100nm technology process era. Also, the first wafer effect, one of the most serious process drifts in an etch process, could be clearly detected by comparing average electron collision rates of plasma during each wafer process. In addition, a strong correlation between average electron collision rate and remaining oxide thickness enables us to control the gate etch process more tightly. Consequently, the APC∕AEC technique by SEERS is expected to be a potent strategy for plasma etch processes in semiconductor manufacturing.