SBIR-STTR Award

Gallium Nitride (GaN) has numerous fundamental figures of merit which provide advantages over SiC and Si, which are, respectively, the current state-of-the-art and standard material systems for power devices. With the Baliga figure of merit, respectively, ~ 5 and ~850 higher than SiC and Si, GaN-based technology will enable >10kV power switching devices. Yet, establishing complex device geometries and doping profiles required for the manufacturing of efficient high-voltage and high-frequency devices remained to be the major hurdle in the field. To realize this, reliable ion implantation followed by post-implantation damage removal and electrical activation by annealing would be critical for the selective area doping. However, unlike SiC and Si material systems, GaN is thermodynamically unstable at high temperatures, prohibiting the use of conventional annealing methods such as Rapid Thermal Annealing (RTA) to anneal structural damage from GaN devices. Annealing to satisfactorily reduce implant-induced damage typically requires temperatures ~2/3, the melting point of the crystal, which is ~1400-1500 C for GaN. But GaN surface decomposes only at a temperature of ~850 C at atmospheric pressure. 0xA0 In this project, we propose to develop a multicycle rapid thermal annealing (MRTA) system with ultrafast sub-second heating and cooling cycle rates (>1000 K/s) that allows shorter temperature pulses (but multiple times) and thereby achieve higher maximum peak temperature in GaN without decomposing the material. The short cycled multiple heating pulses provide better conditions for diffusional processes in GaN, results in better restoration of the device structure damaged by ion implantation, and improves activation of the implanted dopants while also preserving the integrity of the GaN surface.

Benefit:
The historical challenge with hole activation in GaN-based devices is well known and, for decades, stunted the ability for GaN to reach the world stage. Multiple rapid thermal annealing (MRTA) method developed in this project will provide a game-changing opportunity For a successful demonstration of post ion implant annealing in GaN and related alloys. For the advancement of comprehensive integration of GaN power devices into high power military, industrial, and consumer apparatus applications. 0xA0 The higher quality devices will attract the potential customer in R&D, University, and small groups doing high quality, low volume parts. 0xA0 As adoption grows, three levels of market commercialization may emerge. These are, 0xA0 i) Foundry-like services to improve quality of devices with MRTA for early adoption players, ii) Equipment offering that production customers will purchase for their factories, and iii) continued R&D, Universities who dont process enough material to a tool but need to drive quality through a service-based provider.

Keywords:
Ion Implantation, Ion Implantation, Annealing, magnesium, radiation cooling, convection cooling, Induction Heating, GaN, pressurized vessel, MRTA

Future DoD and Navy missions require advances in current high voltage power electronics technology. For this, Gallium Nitride (GaN) is a suitable materials candidate given the numerous fundamental figures of merit that make it superior to SiC and Si, respectively, the current state-of-the-art and standard material systems for power electronic devices. With the Baliga figure of merit, respectively, ~ 5 and ~850 higher than SiC and Si, GaN-based technology will enable >10kV power switching devices. However, establishing complex device geometries and doping profiles required to manufacture efficient high-voltage and high-frequency devices remained the major hurdle in the field. To overcome this, reliable ion implantation followed by post-implantation damage removal and electrical activation of dopants by annealing would be critical for the selective area doping. Unlike SiC and Si material systems, GaN is thermodynamically unstable at high temperatures, prohibiting the use of conventional annealing methods to anneal structural damage in GaN devices. Annealing to adequately remove implant-induced damage would usually require temperatures ~2/3 of the crystal's melting point, which is ~1400-1500 C for GaN. But GaN surface decomposes only at a temperature of ~850 C at atmospheric pressure. In this Phase II program, we propose to design and build a Multicycle rapid thermal annealing (MRTA) system with ultrafast sub-second heating and cooling cycle rates (>1000 K/s). The MRTA allows shorter temperature pulses and achieves a higher maximum peak temperature in GaN without decomposing the material. The short cycled multiple heating pulses provide better conditions for diffusional processes in GaN, better restore the device structure damaged by ion implantation, and improve activation of the implanted dopants while also preserving the the GaN surface integrity. The final MRTA system will be capable of delivering

Benefit:
The challenge with hole activation in GaN-based devices is well known and, for decades, impeded the ability for GaN to reach the world stage. The development of the Multiple rapid thermal annealing (MRTA) system in this project will provide a game-changing opportunity for the following reasons. 1. It will enable for successful demonstration of post ion implant annealing in GaN and related alloys. 2. For the advancement of comprehensive integration of GaN power devices into high power military, industrial, and consumer apparatus applications. The higher quality devices will attract potential customers in R&D, University, and small groups doing high quality, low volume parts. As adoption grows, three levels of market commercialization may emerge. These are, i) Foundry-like services to improve quality of devices with MRTA for early adoption players, ii) Equipment offering that production customers will purchase for their factories, and iii) continued R&D, Universities who do not process enough material to a tool but need to drive quality through a service-based provider.

Keywords:
GaN, implantation, Induction Heating, Heating/cooling cycles, Activation, convection cooling, MRTA, pressurized vessel