Diamond is quite commonly regarded to as the ultimate semiconductor material because of its outstanding combination of materials properties. Yet, its relatively slow technological progress has limited its utility in commercial applications. A challenge exists for diamond technologists to seek out potential niche applications based on current capability as well as to advance the state-of-the-art in growth and device processing for next generation microelectronics.

This presentation discusses early research surrounding bias-enhanced nucleation, a technique discovered circumstantially to promote diamond nucleation on pristine silicon. The discussion follows the progression of results from initial nucleation studies to later work involving epitaxial nucleation on Si(100) and TiC(111). This is truly an example of an enabling technology, as the epitaxially-textured films have been targeted for a host of applications. It was recognized very early in these studies that the substrate significantly affected the nucleation enhancement process, whereby the carbide formers appeared most suitable. While initial work was focused on negative DC substrate biasing, our attention later turned to cyclic and unipolar-pulsed biasing as a means of simplifying the processing of the highly oriented diamond. An investigation into duty cycle and bias frequency effects provided interesting and unanticipated results, enabling insight into this epitaxial nucleation process. The presentation then turns to an evaluation of the thermal attributes of bias-nucleated, epitaxially-textured diamond by comparing the in-plane thermal conductivity of highly oriented vs. randomly oriented diamond, and measuring their temperature-dependent thermal properties. Inferences may be made from this data regarding the defects responsible for their respective thermal properties. Finally, more recent efforts to wafer bond single-side polished Si(100) to smooth, epitaxially-textured diamond are presented. These silicon-on-diamond substrates were successfully fused at temperatures 750°C under an applied stress as low as ~10 MPa. This work highlights the effect of surface preparation on the bonding effectiveness and the materials reactions that occur at the fusion interface.