Chemical vapor infiltration (CVI)—Part I: a new technique to achieve diamond composites

Abstract

Diamond/metal or diamond/ceramics penetration structures have a high potential as, e.g. heat sinks in the microelectronic industry and for tribological applications. To learn more about the basic principles in fabricating these new composites, we infiltrated porous structures of silicon carbide with diamond by chemical vapor infiltration (CVI). As a result we get a 3D penetration structures of diamond and substrate. This requires substrates with an open pored structure. An acceptable growth rate, a high amount of sp 3-bondings in the coating and the complete infiltration of the substrate are important requirements on the CVI-process. These requirements should be fulfilled with an effective variation of the process parameters gas pressure, gas flow, gas composition of the feed gas and the substrate temperature. The diffusion rate of the important gas species for diamond growth (H, CH 3) should be high compared to their durability. With a forced convection the transport rate of the gas species should be improved. For this, we designed a new hot filament apparatus for CVI, which allows some new operating states. Furthermore, we have investigated the fabrication of diamond penetration structures by CVI using a standard microwave plasma deposition reactor (ASTeX AX 6350) and a standard industrial hot filament apparatus (CC800D). Raman spectroscopy and SEM were used to characterize the diamond films.