MEMS Mirror Device Single Substrate Integration

The patent merges multiple substrates into a single semiconductor substrate, integrating the mirror support structure, comb electrodes, and cavity formation all within one substrate. This eliminates the need for multiple separate substrates while maintaining structural integrity through unified material properties and simplified interfacial connections.

The single semiconductor substrate serves multiple functions: supporting the mirror structure, forming the comb electrodes, creating the cavities, and providing the mechanical foundation for the entire MEMS device. This multi-functional integration reduces the number of components and simplifies the overall device architecture.

The etching process is segmented into multiple stages with different etching gases and parameters. Different regions of the substrate receive tailored etching treatments: isotropic etching for cavity formation, anisotropic etching for electrode patterning, and selective etching for releasing the mirror structure. This segmentation allows efficient formation of complex 3D structures while managing gas exposure.

The patent employs parameter changes in the etching process by varying gas composition, pressure, temperature, and power across different etching steps. This enables precise control over etch rate, selectivity, and anisotropy to create the required complex structures within a single substrate without excessive gas exposure.

The patent transitions from purely vertical cavity etching to a combination of vertical and lateral etching approaches. By forming the cavity with controlled depth and using lateral release structures, the mirror achieves sufficient swing range while limiting the vertical etch depth that would cause excessive gas impingement on the support table.

The patent introduces intermediate structures such as release holes and sacrificial layers that mediate between the deep cavity requirement and the gas impingement constraint. These intermediaries allow the etching process to proceed to the required depth while controlling gas flow and pressure to minimize support table exposure.

Multiple functional components that would traditionally require separate substrates are merged into a single semiconductor substrate, including the mirror support beam, comb electrodes, and cavity structures. This integration eliminates multiple assembly steps, alignment operations, and bonding processes, dramatically improving manufacturing efficiency.

All structural components and electrodes are preliminarily formed within the single substrate before final assembly. The comb electrodes, cavity structures, and support beams are all created in advance during the substrate processing stage, eliminating the need for post-assembly operations and reducing total manufacturing time.