[17p-P7-1~21] 13.4 Si wafer processing /Si based thin film /Interconnect technology/ MEMS/ Integration technology

▲ [17p-P7-3] Improvement of Poly-Si Wet Etching for Fusion Bonding of MEMS Pressure Sensor

Jirawat Jantawong¹, 〇Nithi Atthi¹, Apirak Pankiew¹, Chana Leepattarapongpan¹, Kathirgamasundaram Sooriakumar², Wutthinan Jeamsaksiri¹, Charndet Hruanun¹ (1.Nat.Elec.&Com.Tech.Center, 2.IR sensor&systems)

Keywords:Polysilicon, Fusion bonding, MEMS

In this paper, the effects of volume of NH₄F in HNO₃:DIW:NH₄F mixture to the etch rate and etch selectivity of poly-Si and SiO₂ were studied. The roughness of SiO₂ film after poly-Si etched and removed was investigated. By using poly-Si etching with 150:80:5 vol. ratio for 3 mins, the oxide surface roughness after poly-Si removed has increased from 3.1 to 10.5 nm. The high oxide roughness induced by wet etching posing treat to fusion bonding of MEMS pressure sensor. By using the poly-Si etchant of 150:80:4 vol. ratio, the poly-Si etch rate of 1847 A°/min and higher etch selectivity between poly-Si and SiO₂ of 29.4 were obtained. Therefore, the suppression of oxide surface roughness by using high selectivity poly-Si etchant is able to improve the performance of fusion bonding for MEMS pressure sensor devices.