In this work, we report fabrication of completely planar microstructures for MEMS using RF sputtered ZnO as a new sacrificial material and RF sputtered SiO2 as a structural material. The microstructures fabricated by conventional surface micromachining process have two bends around the anchor point. These have been eliminated using a new modified process, which results in completely planar microstructures. For this purpose, trench formation and planarization techniques have been integrated with surface micromachining process. Different planarization techniques have been explored in the present work. Chemical mechanical polishing (CMP) using 1% HCl solution results in completely planarized surface over the trench area. The deposition of ZnO sacrificial layer was carried out in a RF (13.56 MHz) sputtering system using ZnO target. The silicon dioxide, used as structural layer material, was also deposited in the same sputtering system. Issues related with the selection of the appropriate sacrificial/structural layer materials, the deposition process and the sacrificial layer etching are addressed.
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