Low-cost, Low-defect, 2" GaN Epi-ready Substrates Processed with E-Grinding

SixPoint Materials requests the Phase IIC project to make a transition from R&D to pilot production of low-cost, low-defect, 2" gallium nitride (GaN) epi-ready substrates developed in this SBIR project. GaN substrates are the key material for high-end, energy-efficient semiconductor devices for energy, defense, and industrial applications. However, the majority of GaN substrates used in the US are currently imported from overseas. SixPoint believes that the US must establish a reliable domestic manufacturer of GaN substrates because it is a critical strategic material for the national energy policy, security, and economy. Significant effort has been exerted to develop cost-effective near-equilibrium ammonothermal (NEAT) growth of bulk GaN crystals under the ARPA-E SWITCHES program and their wafering/polishing process under this DOE SBIR Phase I/II/IIB program. Combining the NEAT crystal growth process and the innovative wafering/polishing process, we successfully demonstrated low-defect 2" GaN substrates as well as 1400V p-n diodes fabricated on NEAT GaN substrates. We started to supply 2" GaN substrates to collaborators and customers in 2019. Although the ARPA-E SWITCHES program officially ended on 3/9/2020, SixPoint is working on two subcontracting projects under the ARPA-E OPEN 2018 program, one subcontracting project the DOE EERE program, and one subcontracting project under the Office of Naval Research power device project. Additionally, SixPoint sells 2" GaN substrates to research institutions and commercial customers like Toyota. Based on the feedback from the substrate users, SixPoint is currently refining our product of 2" GaN substrates. However, the production yield of 2" NEAT GaN substrates is too low (about 10%) to start pilot production. Additionally, SixPoint currently has only one production reactor. We need to install two more reactors to produce enough quantity to build a profitable business. Low production yield is primarily caused by the cracking during the crystal growth and back-end wafering process. Although the cracking during the crystal growth is being addressed in the ARPA-E projects, cracking during the wafering process has not been addressed yet. In this SBIR Phase IIC project, we will tackle the cracking problems during the wafering process by tracking detailed crack generations in each wafering step (e.g. slicing). Also, we will increase production capacity so that we can start pilot production of GaN substrates at the end of this SBIR Phase IIC project. The proposed SBIR Phase IIC project will work on the following two tasks: Address the yield problem during wire-saw slicing, grinding, lapping, mechanical polishing, and chemical mechanical polishing (CMP) of 2" GaN substrates. This task is conducted with the DOE funds ($1.1M). Addition of two production reactors to SixPoint’s current location. SixPoint aims to become profitable with stable operation of three production reactors. This task is conducted with investment from the third party ($1.1M). Currently, SixPoint is soliciting Series C round of $2M~$3M to both industry partners and financial investors (i.e., venture capitalists). Recognizing the requirement of a third-party matching fund of this program, we are reaching out to venture capitalists at this moment.