Silicon wafer etching by pulsed high-power inductively coupled Ar/CF <sub/>4</sub> plasma with 150 kHz band frequency

摘要： A silicon wafer etching using a burst pulse high-power inductively coupled plasma (ICP) is investigated. A 200 μs 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 1019 m?3 and 2.8 eV where the wafer is, respectively. In the case of Ar plasma, the silicon etching rate is 0.01 μm min?1 with 1000 V negative bias. The etching rate increases to 0.23 μm 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.