Integrated circuits (ICs) are becoming more complex, requiring the supply of large amounts of power, and the dissipation of large amounts of heat. Traditionally, heat dissipation has been handled by convection technologies, such as fans, liquid cooling and heat pipes, or conduction methods that use metals such as copper. These solutions increase the complexity of the system, and add to the size, weight and power of the electronic device. Additionally, new materials such as gallium nitride (GaN) are capable of handling higher voltages and delivering higher output powers than conventional power amplifiers. Unfortunately, these new materials create an even larger thermal load, requiring new methods of heat dissipation. Significant research and development efforts have gone in to developing new thermal management for GaN and similar high power devices.
The most promising methods to dissipate heat involve the integration of diamond as a heat sink. This approach has proved successful, since diamond has the largest thermal conductivity of any material. However, limitations arise due to issues involving the material integration. Diamond has to be grown or deposited at specific temperatures, which limits when it can be integrated with the GaN device. Similarly, the large thermal mismatch between diamond and GaN causes high levels of mechanical stress between the two materials. By using a process that integrates the diamond into the GaN substrate early in the manufacturing process and places the heat sink in contact with the active area of the power amplifier, dramatic performance improvements can be achieved. This technology aims to utilize unique semiconductor processing and growoth methods to overcome the problem of distance between the device and heat sink. In this method, the diamond film is embedded in a trench in the starting substrate. Subsequently, GaN epitaxial layers are grown over the top of the diamond This unique processing method places the diamond only a few microns from the active device area, thus maximizing heat dissipation.
- The diamond thin film is in close proximity to the active area, allowing the dissipation of high heat loads.
- The thin film deposition is completed prior to standard wafer fabrication. This allows for high temperature diamond thin film growth, without exceeding the thermal budget of later processing steps.
- By embedding the diamond film in a narrow channel, there are no bulk mechanical stresses associated with the coefficient of thermal expansion (CTE) mismatch between diamond and GaN.
- Defense and aerospace industries. These are the primary users of high power RF electronics, commonly used in radar applications.
- Optics applications, including high power laser diodes, and light emitting diodes (LEDs).
- High power RF devices, such as radar and communications
Intellectual Property Status: This technology is patent pending under US Patent application number 14/964,217 filed 12/09/2015.