The dry / wet combined etching process is used to assist the application of diamond wafer in device heat dissipation

The increasing power level with the highly localized heat generation in the channel region will introduce severe self-heating in devices. From the perspective of near junction thermal dissipation, integrating diamond thin film on the top of the GaN-based devices has been demonstrated to be an effective way for device thermal management and performance improvement. While, most research mainly focus on the diamond growth and the interface optimization . The integration fabrication of devices with diamond heat spreader is still lacking and full of challenges, in which a very important issue is the low damage removal of the diamond and SiN interlayer.

To solve this problem, Anderson et al. used a two-step etch process for diamond thin film to reduce the damage to AlGaN surface and achieve a smooth surface after the diamond etching, while this method is difficult to calibrate during its operation]. Then they proposed a sacrificial gate process to protect the AlGaN surface during the diamond etching, while there is still deterioration of the off-state characteristics due to the fluorination of the AlGaN surface after removal of the sacrificial gate.They analyzed the interface and thermal properties of sin-passivated AlGaN / GaN heterojunction samples using polycrystalline diamond heat conduction sheets. The strain and 2DEG variation were estimated. For device fabrication, a dry/wet combined etching process was proposed for the partial removal of the diamond and the SiN interlayer, which enables no degradation of the off-state current for the fabricated device with diamond heat spreader. Finally, the enhanced thermal performance of the fabricated device was analyzed using electro-thermal simulation.

CSMH focuses on the research and production of diamond wafers. At present, it has diamond wafers, diamond heat sinks, GaN on diamond, AlN on diamond and other products. Among them, high-power semiconductor lasers packaged by diamond heat sinks have been used in optical communications. In the fields of laser diodes, power transistors, and electronic packaging materials, it can provide customers with diamond thermal management solutions.