CVD diamond thin film technology for MEMS packaging

Due to its extreme hardness, chemical and mechanical stability, large band gap and highest thermal conductivity, poly-crystalline diamond (poly-C) is expected to be an excellent packaging material for biomedical and environmental MEMS devices. A poly-C thin film packaging technology has been developed to explore the application of this novel material on post-MEMS encapsulation packaging process. To study the poly-C thin film packaging a testchip was fabricated using PECVD deposited oxide as a sacrificial material. Large access ports were opened along the package edge to release thin film package using oxide etch. Then, additional poly-C growth was used to seal the access ports. In the test package, boron doped poly-C was also studied as the material for electrical feedthroughs that can be embedded into the undoped electrically insulating poly-C package. This poly-C thin film packaging process and the all-diamond packaging concept has been developed for the first time.