doi: https://doi.org/10.1016/j.cap.2022.11.007

Authors : Jaemin Song, Myeonggeon Lee, Sangwon Ryu, Yunchang Jang, Seolhye Park, Gon-Ho Kim

Abstract: Ion-induced etch damage on trench surfaces of Ge₂Sb₂Te₅ (GST) by reactive ion etching (RIE) is investigated with Ar/SF₆ capacitively coupled plasma (CCP). Etch damage on the sidewall increases with higher plasma density and decreases with the bias power. The roughness of the bottom decreases with the bias power due to the ion sputtering. It is demonstrated that the optimum process condition to minimize the ion-induced damage can be obtained from the feature analysis of the virtual metrology, which was developed with plasma information parameters named PI-VM, and it predicted the GST etch rate and surface roughness. It reveals that the energetic ions play a crucial role in removing the halogenated surfaces by high-energy ion sputtering. In addition, the sidewall damage by the lower F radicals is significant because the collisional diffused F radicals are enhanced in the high-density plasma. It explains the control of bias power required to achieve the profiling etch in the high-density plasma.