By Mario M. Pelella, VP of Engineering, sp3 Diamond Technologies
Interest in diamond continues to grow within traditional thermal and wear applications (packaging, tool coating) and beyond into new applications (semiconductor, MEMS/NEMS, optical, interposers, electrodes, sensors, wastewater treatment, acoustic) that were previously difficult to exploit.
Diamond’s unique physical and electrical properties, which include the highest known thermal conductivity, highest Young’s modulus (diamond is the hardest substance man has ever discovered), a wide band gap, excellent electrical insulator properties, very low thermal expansion, very high breakdown voltage, very high carrier mobility, high radiation hardness, chemical and biochemical inertness and the broadest electromagnetic transmission spectrum, makes this remarkable technology a key enabler to break through current limitations and extend the performance and scalability of existing products well into the future.
For the currently available diamond-deposition systems, hot-filament chemical vapor deposition (HFCVD) growth technology provides the most reliable, safest and most cost effective solution that enables high throughput and good uniformity, control, repeatability and ease of scaling over large areas. Although current deposition areas are in the 350 mm x 375 mm range, scaling the HFCVD technology deposition area to 1000mm x 1000mm is viable, unlike other diamond-growth technologies.
The next step in the evolution of the semiconductor industry is to establish an SOD (silicon-on-diamond) substrate platform that mitigates the thermal impact of ever increasing power densities and suppresses local hot spots that influence peak performance and reliability (FIT rates) specifications, especially for RF power circuits and 3D-ICs. Moreover, incorporating diamond solutions into the MtM (more-than-Moore) technology roadmap will help extend electronic device and sensor performance metrics for a broad array of applications. All the process integration pieces to fully embrace SOD technology have been demonstrated, although productizing a 200mm (or larger) SOD substrate platform for high volume is still an elusive goal for the industry. Government agencies and corporate research and development funding continue to champion the maturity and advancement of diamond technology, which will help shorten the commercialization cycle of this exceptional material.
Recent advances in diamond applications (diamond-on-silicon, MEMS, optical), including record folded-beam RF resonator performance with a Q value of 146,580 at 232.4 kHz, IR transmission values nearing the theoretical limit of 71 percent, brighter, more energy-efficient LED lamps, exceptional figure-of-merit for RF power devices that are 40-50 times better than Si substrates, and demonstrated diamond-based diodes, BJTs, FETs, SAW filters, and field-emission devices, suggest that its utilization into a broader scope of commercial products is not far away.