Parameter Dependence of RIE Induced Radiation Damage in Silicon Dioxide

Radiation damage in silicon dioxide films exposed to reactive ion etching (RIE) in CF4 has been investigated. Capacitance-voltage ((C-V) and photocurrent-voltage (photo I-V) techniques were used to monitor charge trapping and location after the films were incorporated into MOS capacitors. Blanket etched films were used to study the trapping characteristics of bulk, neutral, radiation-induced traps as a function of position in the reactor, rf peak-topeak voltage, and pre-RIE high temperature annealing. The trapping characteristics of films etched in a CF4 + H2 mixture were also studied. Oxide films etched in CF4 + H2 show reduced trapping when compared with oxides etched in CF4. The ability of gate electrode materials to shield an underlying oxide during RIE was also tested. It was determined that aluminum and n+ polysilicon are effective in shielding oxide from RIE induced radiation damage. © 1981, The Electrochemical Society, Inc. All rights reserved.