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Eta Research Develops Free-Standing GaN Substrates

May 30, 2018 by Paul Shepard

Eta Research is a Chinese company that was founded in 2015 with the main purpose to develop free-standing GaN wafers. They now report the successful production of 100 mm GaN wafers.

Eta Research uses the HVPE method to produce GaN wafers. The company has self-developed both their HVPE equipment and production process. A key process technology is the method of GaN separation from the substrate.

Eta Research has developed a unique method, not used by other companies in the industry, which greatly improves the yields and enhances the crystal quality. Additionally, the company uses high quality polishing equipment purchased from a reputable vendor with experience polishing GaN wafers.

The current production equipment can produce entire uncracked 100mm GaN wafers, but due to edge effects, the finished wafers must be cut to a smaller size. The company will soon be offering 2” and 3” GaN wafers for sale. They plan to retool to a larger size to produce 100mm finished GaN wafers by 2019.

The company’s R&D lab is located in Shanghai, China. Construction is already underway for a high capacity production facility located in Tongling, Anhui Province, China.

According Dr. Troy Baker CEO of Eta Research; “Our goal is to improve the energy efficiency and performance of GaN-based devices by using GaN substrates. In order for that to happen on a large scale, GaN substrates must become widely available for a reasonable price.

“We intend to control the cost through our new high yield separation process and the large scale of our new factory, while delivering a product with the characteristics – size, crystal quality, lattice curvature, electrical conductivity, and surface finish – that our customers require,” Dr. Baker concluded.

Hydride Vapor Phase Epitaxy

Hydride Vapor Phase Epitaxy (HVPE) is a process that can produce single crystal GaN. It is used for the growth of GaN substrates because of the high growth rate and high quality that can be attained. In this process, HCl gas is reacted with liquid gallium metal, which forms GaCl gas. Then the GaCl reacts with NH₃ gas at about 1,000 °C to form the solid crystal of GaN. Eta Research has developed our own HVPE equipment with the goal to cost effectively scale the production of GaN wafers.

Currently, the vast majority of GaN-based devices use foreign substrates such as Al₂O₃ and Si. Although foreign substrates are good for some applications, the dissimilar material causes defects to be placed in the GaN device layers as material is deposited. The defects can reduce the performance.

GaN substrates, especially with low defect density, offer the best choice for deposition of GaN device layers. Use of GaN substrates will improve the efficiency, power density, and other performance metrics of GaN devices.