Silicon wafer etching by pulsed high-power inductively coupled Ar/CF4 plasma with 150 kHz band frequency

A silicon wafer etching using a burst pulse high-power inductively coupled plasma (ICP) is investigated. A 200 mu s wide burst of a 157 kHz power supply is employed to generate ICP with a repetition rate of 50 Hz. A rectangular pulsed voltage synchronized with the burst power supply is applied upto 1 kV at the wafer. Mixed gas of argon (Ar) and tetrafluoromethane (CF4) is supplied into the vacuum chamber. The plasma density and electron temperature are 10(19) m(-3) and 2.8 eV where the wafer is, respectively. In the case of Ar plasma, the silicon etching rate is 0.01 mu m min(-1) with 1000 V negative bias. The etching rate increases to 0.23 mu m min(-1) by adding CF4 into Ar and increases linearly with increasing the bias voltage. The target current and emission intensity of Ar+ and F-* are depended on bias voltage from -300 to -1000 V. The etching rate sharply increases by increasing CF4 content from 0% to 10%, and it becomes almost constant at 10%. The dependency of emission intensity of F* on CF4 content is similar to the dependency the etching rate. (C) 2020 The Japan Society of Applied