| 초록 |
Angular dependences of etch rates of Si and fluorocarbon polymer in SF6, C4F8, and O2 plasmas for the advanced Bosch process widely used for deep MEMS etching were investigated using a TCP etcher. In SF6/Si etching, the normalized etch rate (NER) decreased with the ion-incident angle, which exceeded cosine values, independent of process conditions including the source power and bias voltage. On the other hand, in SF6/polymer etching, the NER nearly followed the cosine curve. These results indicate that the SF6/polymer etching is an ion-enhanced chemical sputtering while the SF6/Si etching is a spontaneous chemical etching. The NER of O2/polymer etching was highly dependent on the process condition. As the source power increased and the bias voltage decreased, the NERs decreased and became lower than cosine values. The characteristic curve in the case of C4F8/Si etching, representing the deposition rate, can be divided into five distinct regions: Si sputtering, pure polymer deposition, polymer suppression, ion-enhanced deposition, and polymer scattering. |
