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.