In December 2017, the Shanghai Microtechnology Industry Research Institute (SITRI), a leading entity in the "Beyond Moore" innovation platform, launched the HV600/HV650 series of 8-inch silicon-based GaN epitaxial wafers specifically designed for surface-to-air applications. These wafers are characterized by high crystal quality, excellent material uniformity, strong voltage resistance, and superior reliability. Notably, their effective lifespan exceeds one million hours, marking a significant breakthrough in overcoming long-standing technical challenges in the application of silicon-based GaN materials. This development paves the way for industrial use of medium- and high-voltage silicon-based GaN power devices.
Compared to traditional semiconductor materials, GaN—a third-generation semiconductor—offers remarkable advantages such as a wide bandgap, high saturation velocity, high breakdown electric field, and excellent thermal and radiation resistance. These properties make it ideal for next-generation high-speed, high-efficiency power devices. Its potential applications span wireless charging, fast charging, cloud computing, 5G communications, laser radar, and new energy vehicles. Additionally, silicon-based GaN materials offer cost advantages, especially when using large-sized silicon wafers as substrates, enabling low-cost manufacturing that rivals conventional silicon-based power devices. As a result, silicon-based GaN technology is widely regarded as the mainstream direction in the future of power electronics.
Established in 2016, the Power Devices Division at SITRI has been focused on developing silicon-based gallium nitride materials for industrial applications. At the 3rd National Symposium on New Semiconductor Power Devices and Application Technologies, Dr. Yuan Li, head of the division, presented the latest progress on SITRI’s 8-inch silicon-based GaN epitaxial material project. The high reliability and uniformity of the HV600/HV650 series have drawn considerable attention and received widespread acclaim from industry professionals.
The epitaxial structure of the HV600/HV650 series is fully compatible with 8-inch silicon process lines. By utilizing a low-resistance 8-inch silicon substrate and employing pre-strain technology to address thermal mismatch issues between silicon and GaN, SITRI has optimized the epitaxial layer structure based on specific application needs.
Figure 1 illustrates the epitaxial structure of the HV600/HV650 series materials.
The material quality of the HV600/HV650 series is exceptional. To meet 600 V/650 V withstand voltage requirements, SITRI employs thick-film epitaxial growth technology over 4 microns. Through optimized GaN crystal growth control, they have resolved issues like wafer warping and crystal defects caused by lattice mismatch. The resulting materials are crack-free, with minimal warping (≤ ±50 μm) and low surface roughness (≤ 0.3 nm), meeting the demands of mass production for 8-inch power devices.
Figure 2 shows the wafer warpage of the HV600/HV650 series materials.
The defect density of the HV600/HV650 series is remarkably low. Using optimized GaN epitaxial defect control technology, SITRI achieves both high dislocation density and high crystal quality while maintaining high withstand voltage and thick film growth. Their XRD (002/102) half-widths are less than 400/500 arcseconds respectively.
Figures 3 and 4 display the HRXRD GaN (002) and (102) patterns of the HV600/HV650 series materials.
Material uniformity is another key strength of the HV600/HV650 series. The thickness variation of the 8-inch epitaxial layer and the Al variance of the AlGaN barrier layer are below 0.3% and 2%, respectively. This ensures high uniformity and yield in the mass production of large-size silicon-based GaN power devices, addressing critical bottlenecks in the industrial application of GaN devices.
Figure 5 presents the epitaxial thickness distribution of the HV600/HV650 series materials.
Figure 6 shows the Al component distribution of the AlGaN barrier layer in the HV600/HV650 series.
For high-voltage applications, the HV600/HV650 series demonstrates excellent pressure resistance. Meeting stringent industry standards for leakage current (1 μA/mm²), these materials achieve vertical withstand voltages of 640 V and 700 V. With a stricter leakage current criterion of 0.1 μA/mm, they exhibit lateral withstand voltages of 700 V and 760 V when the substrate is grounded, and 950 V and 1010 V when floating, fully meeting the needs of 600 V/650 V applications.
Figures 7, 8, and 9 illustrate the vertical and transverse withstand voltage characteristics of the HV600/HV650 series materials.
The forward conduction characteristics of the HV600/HV650 series are outstanding. They feature a two-dimensional electron gas concentration greater than 9×10¹² cmâ»Â², mobility exceeding 1800 cm²/V·s, and sheet resistance below 400 Ω/sq.
Figure 10 displays the square resistance distribution of the HV600/HV650 series materials.
Reliability is a core strength of the HV600/HV650 series. Based on optimized silicon-based GaN epitaxial growth technology, these materials demonstrate excellent performance under high-pressure TDDB testing, with an effective life of over one million hours (equivalent to 114 years) at nominal voltage.
Figure 11 shows the longitudinal high-voltage TDDB test results.
Additionally, the HV600/HV650 series exhibits excellent high-temperature performance. At 150°C and with the substrate grounded, the lateral leakage of 600 V and 650 V products is 0.7 and 0.6 μA/mm, respectively, both below the 1 μA/mm threshold. This ensures high efficiency and safety in the typical operating temperature range of power devices.
Figures 12 and 13 depict the transverse withstand voltage characteristics of the HV600 and HV650 series at high temperatures.
The HV600/HV650 series of 8-inch silicon-based GaN epitaxial wafers developed by SITRI have successfully overcome the material bottlenecks in the mass production of silicon-based GaN devices. Achieving industry-leading reliability with over one million hours of effective life, these products also come in smaller sizes such as 6-inch wafers, meeting diverse industry demands for silicon-based GaN epitaxial materials.
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