[1P01-32] Poster session

[1P24] Control of the plasma etching rate of thin SiO₂ by the electrical resistivity of backside electrode materials

*Toshitaka Kubo¹, Satoru Takahashi², Chikatsu Iwase², Ryo Kanou², Shouta Shiba², Tetsuo Shimizu² (1. National Institute of Advanced Industrial Science and Technology (AIST) (Japan), 2. Sanyu Co., Ltd. (Japan))

The plasma etching rate of quartz substrates is significantly influenced by the electrical resistivity of backside electrode materials. In this study, backside electrodes with a wide range of resistivities (10^-8 to 10¹² Ωm) were employed to systematically investigate their effect on etching performance. Plasma etching experiments were conducted using an inward plasma system, and quartz plates with a thickness of 300 mm were used as samples. The results reveal a clear negative correlation between electrical resistivity and etching rate. Low-resistivity materials, such as metallic tantalum and semi-metallic graphite, exhibited relatively high etching rates of approximately 1.5 mm/min. In contrast, high-resistivity materials, including silicon carbide and glass, showed significantly reduced etching rates of around 1 mm/min or less. Notably, a transition in etching behavior was observed around a resistivity of approximately 1 Ωm. Although the electrode response to plasma is influenced by multiple factors, these findings indicate that the electrical resistivity of backside electrode materials is a dominant factor in determining the etching rate.

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