Plasma Etching III

Plasma etching is a critical step in semiconductor manufacturing. Optical emission spectroscopy (OES), as a non-intrusive technique, is widely used for endpoint detection in etching processes. However, as the requirements for etching precision continue to increase, there is a pressing need to monitor plasma states in real-time via OES to achieve fine control of process parameters within the reaction chamber. Nevertheless, actual etching process gases contain multiple components (e.g., O₂, CₓFᵧ), rendering traditional methods—which rely on calibrated spectral lines from pure Ar plasma for parameter monitoring—inapplicable in real etching environments due to the quenching effect. This effect causes severe distortion in measurement results. To address this issue, this paper constructs a collisional-radiative model (CRM) incorporating the quenching processes between Ar excited states and O₂/CₓFᵧ. We thoroughly investigate the impact of quenching on the kinetic mechanisms of Ar excited states. Based on this, we propose a plasma state monitoring method using Ar emission lines that is suitable for practical etching processe.

Funding acknowledgement

This work is financially supported by the National Natural Science Foundation of China under grant No. U22B2094