NEAT method for high-quality, low-cost gallium nitride wafers

T. Hashimoto, E. Letts, D. Key
SixPoint Materials, Inc.,
United States

Keywords: bulk GaN wafer, ammonothermal, power electronics, solid-state lighting, leser projector, laser headlamp, 5G, radar


SixPoint Materials will address the price and supply problem of bulk GaN wafers with an innovative NEAT (near equilibrium ammonothermal) method. Gallium nitride (GaN) is a key material for semiconductor devices in energy-efficient power electronics, 5G power modules, and ultra high-power solid-state lighting including laser lighting. The total market of these devices is $5B in 2020. Bulk GaN wafers are indispensable for current and future high-end devices such as 10-20 kV power transistors, GaN-on-GaN LEDs, blue lasers and millimeter wave transistors for 5G; nevertheless, technology development and commercialization of these devices are seriously impeded by currently available high-cost and low-quality GaN wafers. The majority of bulk GaN wafers in the current market are produced by hydride vapor phase epitaxy (HVPE), which is low-efficiency and low-yield. Although the strong market pressure reduced the wafer price from $4,000/2" (in 2010) to $1,000/2" (in 2018), further cost reduction is extremely challenging with HVPE. Currently, 85% of GaN wafers are produced by the Japanese "big three". All of these companies produce GaN wafers with fully depreciated equipment; however, their business is not profitable. Therefore, an increase of production capacity will inevitably involve a price increase associated with depreciation cost. Although the market demand of bulk GaN wafers is increasing, this "lock-up" situation prevents an increase in wafer supply at lower cost. SixPoint's innovative NEAT method will break this situation. The NEAT method uses the same technology as quartz mass production. The excellent scalability will enable us to reduce the cost in half including depreciation costs of equipment. In addition, the defect density of NEAT bulk GaN wafers is 1/10th that of HVPE GaN. Because of these excellent characteristics of the NEAT method, SixPoint has been strongly supported by ARPA-E, DOE and Navy. We have demonstrated high-quality 2" bulk GaN wafers in 2018. In addition, we are developing colorless 2" bulk GaN wafers for LED applications and semi-insulating 2" bulk GaN wafers for 5G devices. SixPoint has established a strong patent portfolio with more than 80 allowed patents world-wide and more than 40 patents pending world-wide. Currently, we are producing 2" bulk GaN wafers with a pilot production reactor. Upon further investment, we are capable of growing the market volume of GaN wafers with the high-quality, high-volume, low-cost NEAT method. This will contribute to quicker development of energy-efficient GaN devices and 5G power modules.