Direct Bonding of Diamond and Dissimilar Materials for Fabricating High Performace Power Devices

As thePower devices performance ofHigh performace semiconductor devicesDirect bonding increases, the output power density and reliability of the devices are greatly limited by self-heating during their operation. Diamond has the highest thermal conductivityThermal conductivity among materials and is the most promising material as a heat-spreading substrate. The integration of diamonds with semiconductor and heat sink materials is an efficient technique for improving the heat dissipationHeat dissipation efficiency of power devices. However, it is a big challenge to integrate diamonds with semiconductor materials such as siliconSilicon (SiSi), gallium nitrideGallium nitride (GaNGaN), and gallium arsenideGallium arsenide (GaAs) due to a large thermal expansion coefficient mismatch between them. In our works, we directly integrated diamond with Si, GaAsGaAs, GaN, copper (Cu), and aluminum (Al) using the surface-activated bondingSurface-activated bonding (SABSAB) method at room temperature. From the heat resistance measurementsHeat resistance measurements of the bonding interfaceBonding interface and the evaluation results of the nanostructure, compositional elements, and bonding state of the bonded interface before and after heat treatment, Si/diamond, GaAs/diamond, GaN/diamond, Cu/diamond, and Al/diamond bonding interfaces demonstrated good interfacial characteristics. The bonding interface exhibited high thermal stabilityThermal stability and excellent practicality. An intermediate layer was formed at the as-bonded interface, which was formed by Ar beam irradiationAr beam irradiation during the bonding process. The intermediate layer played an important role in releasing the residual stressResidual stress caused by thermal expansion mismatch between bonding materials. We fabricated AlGaN/GaNAlGaN/GaN high electron mobility transistorsHigh electron mobility transistors (HEMTsHEMTs) on a diamond by transferring AlGaN/GaN/3C-SiCSiC layers grown on Si to the diamond substrate. The performance of GaN transistorsGaN transistors formed on the diamond was 35% higher than that of GaNGaN transistors formed on Si. The thermal boundary resistance (TBR) of the Cu/diamond interface showed a low TBR value, which was as same as the theoretical value. These results demonstrated that the power module structure with a high heat dissipationHeat dissipation ability can achieve by integrating diamond with semiconductors and heat sink materials.