Diamond Wafer - a superior, multipurpose material for high-power density application

Commercially, CVD diamond, with fully isotropic characteristics is readily available in six different grades with thermal conductivities ranging from 700 to 2000 W/mK and bulk resistivity from 0.001 Ωm for doped diamond to 1012 Ωm for undoped diamond.

When facing heat flux from high power density hot spots in optoelectronics, RF power amplifiers or matching of high frequency loads through use of resistive terminations, CVD diamond delivers improved reliability and increased power handling. These step changes impact a wide range of disruptive electronics, from solid state RF PAs to advanced ASICs and laser diodes to 5G wireless and phased array radar.

CVD diamond for RF packaging

In designing a system of thermal management, one must carefully consider both the material and the application methodology, in order to minimize channel temperatures and deliver long-term device operation. To date, the integration of SiC (400 W/mK) substrates with GaN has provided the best option for GaN HEMT and MMIC technology for high power applications. However, despite the use of SiC substrate, adequate heat spreading is still the limiting factor in determining the maximum power dissipation for GaN based electronics. As such, the path to long term reliability is often achieved by de-rating the maximum power dissipation. A far better heat spreading solution incorporating CVD diamond (2000 W/mK) has the potential for a factor of 3× or higher increase in power density relative to current state-of-the art GaN devices.

While GaN-based electronics are capable of delivering ultrahigh current and power densities performance, the failure of many high-end electronic systems is directly attributable to the lack of adequate thermal management.

Semiconductor devices continue to increase in power density. For high power RF and Optoelectronics, CVD diamond enables devices to run at higher power levels without increasing junction operating temperature, thereby increasing lifetimes and reliability.

An application example – To demonstrate the impact of a diamond heat spreader in a practical example, an RF- amplifier design was analyzed. In this example, a VDMOS (Vertical Diffused Metal Oxide Semiconductor) power amplifier package was initially made with a BeO (Beryllium oxide) heat spreader on a CuMo (Copper/Molybdenum) flange. The end user was interested in lowering the overall thermal resistance of the system design as well as avoiding the use of BeO due to its toxicity.

One of the key findings is the temperature profile junction-to-case for one of the optimal designs derived from one modelling. The CVD diamond heat spreader solution was found to have 30% lower thermal resistance at 0.300 mm in thickness at a thermal conductivity of 1000 W/mK. (The original solution used a 1.00 mm thick BeO heat spreader.) The improved thermal resistance of the diamond heat spreader has led to this device functioning with better linearity in its RF performance and with improved reliability due to its reduced junction temperature.

CSMH has the ability to design MPCVD equipment. It is the first domestic company to master the core process of MPCVD to produce 4-inch high-quality diamond wafer and realize mass production. Our capacity is 50,000 pcs per month. Between the thermal conductivity requirements of 1000~2000W/m.k, diamond heat sink is the first choice and the only optional heat sink material. CSMH can customize the thermal conductivity according to customer requirements. Currently, three standard products have been launched: TC1200, TC 1500, TC 1800.