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 gau ss) to a planar-spiral antenna configuration. Efficient power transfer and reduction of charged particle loss are possible by magnetizing th e low pressure plasma. Consequently, higher levels of plasma and ion c urrent 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 charact eristics of SiO2 and Si. An improvement of SiO2/Si etch selectivity wh ile maintaining a high SiO2 etch rate is obtained by applying the magn etic field to various fluorocarbon plasmas. Etch threshold ion energy and polymer film deposition rate increase with the external magnetic f ield for carbon-rich feed gases such as C4F8. Reactive ion etching (RI E) lag in fine holes is greatly reduced while keeping the high selecti vity under modest magnetic induction level. At higher magnetic inducti on level the RTE lag worsens and is accompanied by a considerable decr ease in the Si etch rate. (C) 1996 American Vacuum Society.