Anisotropic Silicon Etching Using <tex>$RuO_2$</tex> Thin Film as a Mask Layer by TMAH Solution

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J. Korean Ceram. Soc. > Volume 34(10); 1997 > Article

Journal of the Korean Ceramic Society 1997;34(10): 1021.

$RuO_2$를 마스크 층으로 TMAH에 의한 이방성 실리콘 식각

이재복, 오세훈, 홍경일, 최덕균

한양대학교 무기재료공학과

Anisotropic Silicon Etching Using $RuO_2$ Thin Film as a Mask Layer by TMAH Solution

ABSTRACT

RuO2 thin film has reasonably good conductivity and stiffness and it is thought to substitute for the cantilever beam made up of Pt and Si3N4 double layers in microactuators. Therefore, anisotopic Si etching was performed using RuO2 thin film as a mask layer in 25 wt. % TMAH water solution. In the etching temperature ranging from 6$0^{circ}C$ to 75$^{circ}C$, the etch rates of all the crystallographic directions increased linearly as the etching temperature increased. The etch rate ratio(selectivity) of [111]/[100] which varied from 0.08 to 0.14, was not sensitive to temperature. The activation energies for [110] direction, [100] direction and [111] direction were 0.50, 0.66 and 1.04eV, respectively. RuO2 cantilever beam with a clean surface was formed at the etching temperatures of 6$0^{circ}C$ and $65^{circ}C$. But the damages due to formation of pin holes on RuO2 surface were observed beyond 7$0^{circ}C$. The tensile stress of RuO2 thin films caused the cantilever bending upward. As a result, it was demonstrated that the formation of conducting oxide RuO2 cantilever beam which can replace the role of an electrode and supporting layer could be possible by TMAH solution.

Key words: Anisotropic Si etching, $RuO_2$, TMAH, Cantilever beam