Highly uniform polycrystalline diamond coatings of three-dimensional structures

Diamond is highly desirable as a conformal thin-film coating for three-dimensional (3D) devices due to its extreme hardness, durability and biocompatibility, especially in the case of implantable medical devices and prosthetics. Recent advances in microwave plasma chemical vapour deposition (CVD) have enabled conformal coating of such 3D structures with nanodiamond films. However, these techniques have not been extended to micro-crystalline diamond, due to interactions between the 3D substrates and resonant microwave cavity. Here we demonstrate more uniform growth of CVD polycrystalline diamond (PCD) coatings on complex-shaped structures, with the use of in-cavity Faraday cages, to isolate the 3D sample from the microwave cavity. While this does disrupt the distribution of the microwave plasma, which surrounds the 3D structure, we show that growth of relatively uniform micro-crystalline and faceted PCD films is possible over the entirety of the exposed 3D sample surface. The resultant technique opens possibilities for the coating of complex 3D geometries with a wider range of diamond materials than has been possible to date.

Automated summary

The desire for diamond as a conformal thin-film coating for 3D devices due to its extreme hardness, durability, and biocompatibility has led to recent advancements in microwave plasma CVD techniques. By using in-cavity Faraday cages to isolate the 3D samples from the microwave cavity, more uniform growth of CVD polycrystalline diamond coatings on complex-shaped structures has been demonstrated. This technique disrupts the distribution of the microwave plasma around the 3D structure but still allows for growth of relatively uniform micro-crystalline and faceted PCD films over the entire exposed 3D sample surface.