Hybrid etching process and its application in thermopile infrared sensor

This paper presents a hybrid silicon etching processing technique for removing the entire bulk silicon to release microstructure. The proposed method that combines a back-side wet anisotropic pre-etching and a front-side XeF₂ dry isotropic post-etching differs from previous works in silicon micromachining. Wet anisotropic pre-etching enhances the low-cost of the proposed method while the XeF₂ dry post-etching avoids the stiction problem and makes the release process easier. By using this low-cost and high-yield hybrid etching process technique, the micro-structure can be released in a short time. Due to the fact that the whole bulk silicon is removed and the loss mechanism due to the bulk silicon can be eliminated, the device´s performance can also be significantly enhanced. A thermopile infrared sensor using the proposed hybrid etching process is also demonstrated.