Proceedings of the KIEE Conference (대한전기학회:학술대회논문집)

The Korean Institute of Electrical Engineers (대한전기학회)
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Measurement of residual stress of TEOS and PSG for MEMS

MEMS용 PSG와 TEOS의 열처리에 따른 잔류응력의 측정

  • Yi, Sang-Woo (School of Electrical Engineering, Seoul National University) ;
  • Lee, Sang-Woo (School of Electrical Engineering, Seoul National University) ;
  • Kim, Jong-Pal (School of Electrical Engineering, Seoul National University) ;
  • Park, Sang-Jun (School of Electrical Engineering, Seoul National University) ;
  • Lee, Sang-Chul (School of Electrical Engineering, Seoul National University) ;
  • Kim, Sung-Un (School of Electrical Engineering, Seoul National University) ;
  • Cho, Dong-Il (School of Electrical Engineering, Seoul National University)
  • 이상우 (서울대학교 전기공학부) ;
  • 이상우 (서울대학교 전기공학부) ;
  • 김종팔 (서울대학교 전기공학부) ;
  • 박상준 (서울대학교 전기공학부) ;
  • 이상철 (서울대학교 전기공학부) ;
  • 김성운 (서울대학교 전기공학부) ;
  • 조동일 (서울대학교 전기공학부)
  • Published : 1998.07.20
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Abstract

This paper investigates the residual stress of tetraethoxysilane (TEOS) and 7wt% phosphosilicate glass (PSG), which are commonly used as a sacrificial layer or etch mask in the fabrication of microelectromechanical systems (MEMS). In order to measure residual stress, $2{\mu}m$ thick TEOS and PSG stress measurement structures are fabricated. Polysilicon is used as the sacrificial layer. First the residual stress of an as-deposited 7wt% PSG flim and TEOS film are measured to be-0.3115% and -0.435%, respectively, which are quite large. These films are annealed from $500^{\circ}C$ to $800^{\circ}C$. Annealing has the effects of reducing residual stress. In the case of the 7wt% PSG film, the residual stress becomes +0.00715% after annealing at $625^{\circ}C$ for 150 minutes. In the case of TEOS film, the residual stress reduces to -0.2134% after same condition. Incidentally, this condition is the same condition for depositing a $2{\mu}m$ thick polysilicon at $625^{\circ}C$ at our low pressure chemical vapor deposition (LPCVD) furnace.

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