SBIR-STTR Award

Microwave Plasma Enhanced Chemical Vapor Deposition(PECVD) of diamond films using halogen based chemistries is proposed in order to develop a low temperature diamond deposition process. The unique properties of diamond, an insulator with the highest room temperature thermal conductivity, make it an attractive material to be used for improving the thermal dissipation properties of high power density microelectronic devices. Recent reports indicate that halogen based chemistries have allowed a significant reduction of the deposition temperature required for diamond deposition in thermal cvd reactors . Such a reduction in temperature would allow the deposition of the diamond palms dlrectly over high power mlcroelectronics chips. In this work, we propose the use of microwave pecvd since it has consistently generated (in hydrogen-methane chemistries) diamond films of the highest quality with thermal conductivities which approach that of natural diamond. Operation of the chip after diamond deposition would provide a proop-of-principle experiment for the peasibility of the proposed approach. High thermal conductivity diamond films deposited at low temperatures would greatly enhance the kind of materials over which these films can be deposited (mostly ceramics and repractory metals). A significant reduction on the deposition temperature would allow deposmon on e.g. aluminum and in principle over plastics. Diamond films directly deposited on completed microelectronic devices could have a significant impact on the levels of device integration that can be attained in si or gaas based devices.

Diamond films on devices are an excellent candidate for dissipation of self-generated thermal loads in integrated circuits and multichip modules. In fact, due to the potential advantages of incorporating diamond film deposition as another step in semiconductor manufacturing, a low temperature deposition process on completed devices is extremely desirable. However, development of such a process using chemical vapor deposition (CVD) of diamond at practical rates (near 1 micron/hour) and at low temperatures (in the 400 to 500 degrees range) has so far eluded researchers. Microwave plasma enhanced CVD of diamond using halogen-based chemistries has been used successfully during Phase I to achieve deposition at temperatures as low as 200 degrees C. For Phase II, we propose a halogen-based chemistry, high power density microwave discharge as a sound approach to achieving CVD diamond deposition at the practical rates previously mentioned. The proposed technique is based on the already demonstrated success of the high power density process in increasing the diamond deposition rates by a factor of 20 in C/H/O systems. Higher circuit integration and faster clock speeds will require diamond for thermal management. A low temperature deposition process will also allow deposition on glass, fiber optics, and other optical elements. Wear- and corrosion-resistant diamond coatings on non-refractory materials such as steels will be possible.