Abstract
The high-speed etching of a silicon wafer was experimentally investigated, focusing on the duty factor of 150 kHz band high-power burst inductively coupled plasma. The pulse burst width was varied in the range of 400–1000 µs and the repetition rate was set to 10 Hz. A mixture of argon (Ar) and carbon tetrafluoride (CF4) gas was used as the etching gas and injected into the vacuum chamber. The impedance was changed with time, and the coil voltage and current were changed to follow it. During the discharge, about 3 kW of power was applied. The electron temperature and plasma density were measured by the double probe method. The plasma density in the etching region was 1018–1019 m−3. The target current increased with t burst width. The etching rate of Ar discharge at burst width of 1000 µs was 0.005 µm/min. Adding CF4 into Ar, the etching rate became 0.05 µm/min, which was about 10 times higher. The etching rate increased with burst width.
Highlights
The high-speed etching of a silicon wafer was experimentally investigated, focusing on the duty factor of 150 kHz band high-power burst inductively coupled plasma
The frequency is set to 100–200 kHz, which is not necessary for the impedance matching circuit required in conventional Inductively coupled plasma (ICP) systems, and the resonance between the ICP inductance and the parallel capacitance produces high-density plasma of the order of 1019 m−3 [12,13,14,15,16,17]
The etching was operated in Ar and Ar/CF4 discharges, and the effects of the power and burst width were investigated
Summary
The high-speed etching of a silicon wafer was experimentally investigated, focusing on the duty factor of 150 kHz band high-power burst inductively coupled plasma. The coil voltage and current increased with the input power. CF4 contents : 15%, μs μs μs μs Figure 8 shows the target current for Ar discharge and Ar/CF4 discharge at each input power.
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