Reduction of plasma induced damage in an inductively coupled plasma using pulsed source power

Pulse-time-modulated plasmas have been proposed to overcome charging proble ms due to electron shading in ultralarge-scale integrated patterning. In th is article, we report the effectiveness of pulse-power modulation of a comm ercial, inductively coupled plasma system in reducing tapography-dependent charging, sensed by the reduction in the shift in threshold voltages of met aloxide-semiconductor transistors. This plasma-induced damage during metal etching can be significantly reduced by turning the 13.56 MHz radio frequen cy (rf) power to the transformer-coupled coil antenna on and off, while mai ntaining a continuous rf bias power at 13.56 MHz. At an optimum condition o f 50 mu s on and 50 mu s off, the severity of the device damage is reduced to nearly 1/5 that of continuous wave plasma. Thus, the use of pulse-time-m odulated plasma is an effective and promising technique for suppressing top ography-dependent charging during metal etching in a commercial reactor. (C ) 2000 American Vacuum Society. [S0734-211X(00)09902-9].