Micro-manufacturing technology of a three-dimensional curved surface diamond structure for gyroscope applications

摘要

A novel three-dimensional (3D) micro-manufacturing technology of a curved surface diamond structure used for a micro birdbath resonator gyroscope (μ-BRG) with integrated curved electrodes is presented. The integrated curved electrodes with the same curvature as the birdbath shell are embedded using a self-aligned process, which avoids the extra assembly process, ensures the symmetry and improves the driving capacity of the μ-BRG. The capacitive gap is defined by the sacrificial layer, and a uniform and small gap distance(2 μm) between the curved electrodes and the birdbath shell is obtained. The μ-BRGs with a diameter of 1.2 mm and a thickness of 2 μm have been demonstrated by employing boron-doped microcrystalline diamond films deposited using hot filament chemical vapor deposition(HFCVD). In this paper, the device structure and basic working principle of the gyroscope are described. The key steps in the fabrication process, such as isotropic wet etching of the bulk silicon for a birdbath mold, photoresist spray-coating for patterning the curved electrodes, and deposition and etching of diamond films, are considered in detail and well solved. The radial deviation of the etched birdbath mold is about 0.31% for the ～560 μm radius shell and the surface roughness of the birdbath mold is favorable (Rq=4.933 nm, Ra=3.945 nm). The key techniques described in this paper can be applied to the fabrication of other 3D micro devices.