Effects of magnetic field on oxide etching characteristics in planar type radio frequency inductively coupled plasma

We have developed a new magnetized radio frequency inductively coupled high density plasma etching reactor. The essential part of the system is the application of a weak volumic magnetic field (less than 30 gauss) to a planar-spiral antenna configuration. Efficient power transfer and reduction of charged particle loss are possible by magnetizing the low pressure plasma. Consequently, higher levels of plasma and ion current density can be obtained compared with a nonmagnetized discharge. It is found that the degree of magnetization in the plasma source is one of the most important parameters that affects the etching characteristics of SiO2 and Si. An improvement of SiO2/Si etch selectivity while maintaining a high SiO2 etch rate is obtained by applying the magnetic field to various fluorocarbon plasmas. Etch threshold ion energy and polymer film deposition rate increase with the external magnetic field for carbon-rich feed gases such as C4F8. Reactive ion etching (RIE) lag in fine holes is greatly reduced while keeping the high selectivity under modest magnetic induction level. At higher magnetic induction level the RTE lag worsens and is accompanied by a considerable decrease in the Si etch rate. (C) 1996 American Vacuum Society.