Epitaxial buffer structures grown on 200 mm engineering substrates for 1200 V E-mode HEMT application

Abstract

In this work, we demonstrate the epitaxial growth of a gallium-nitride (GaN) buffer structure qualified for 1200 V applications on 200 mm engineered poly-AlN substrates with hard breakdown >1200 V. The manufacturability of a 1200 V qualified buffer structure opens doors to high voltage GaN-based power applications such as in electric cars. Key to achieving the high breakdown voltage is careful engineering of the complex epitaxial material stack in combination with the use of 200 mm engineered poly-AlN substrates. The CMOS-fab friendly engineered poly-AlN substrates have a coefficient of thermal expansion (CTE) that closely matches the CTE of the GaN/AlGaN epitaxial layers, paving the way for a thicker buffer structure on large diameter substrates, while maintaining the mechanical strength of the substrates and reaching higher voltage operation.

Dislocation characterization in c-plane GaN epitaxial layers on 6 inch Si wafer with a fast second-harmonic generation intensity mapping technique

“…GaN(1 nm)/Al 0.26 Ga 0.74 N(20.5 nm)/AlN(1 nm)/GaN(1870 mm)/AlGaN(1000 nm)/AlN(175 nm) epitaxial layers were fabricated on 6 inch Si wafers (Wafer Works Corp.) by using the metalogranic chemical vapour deposition system (AIX G5 + C, Aixtron), which can be used in the application of high electron mobility transistors (HEMTs) [18,40]. It is noted that the used deposition system can produce eight GaN epitaxial layers on 6 inch Si wafers simultaneously.…”

A Brief Overview of the Rapid Progress and Proposed Improvements in Gallium Nitride Epitaxy and Process for Third-Generation Semiconductors with Wide Bandgap

“…In 2020, IMEC achieved a significant milestone by developing an epitaxial structure with a breakdown voltage of 650 V. Building on this success, in 2022, they were able to increase the breakdown voltage to 1200 V by using the 200 mm QST substrate, showcasing the potential of complex epitaxial material stacks and QST substrates for high-voltage power applications such as electric vehicles. To achieve high breakdown voltage, the coefficient of thermal expansion (CTE) of the poly-AlN substrate is a crucial factor [81,131]. IMEC has carefully designed the poly-AlN substrate to closely match the CTE of the GaN/AlGaN epitaxial layer, enabling thicker epitaxial structures to be grown on large diameter substrates while maintaining the mechanical strength of the substrate and achieving higher voltage operation.…”

“…In this chapter, we also explore another way to increase breakdown voltage, which was to reduce the critical electric field at the AlN/Si interface by increasing the thickness of the buffer layer. There were different structural concepts and optimized Figure 4a-c to achieve a target vertical breakdown voltage of at least 1200 V. Design grow stress relief layers with varying thicknesses for structures A, B, and C and evaluate their breakdown voltage under high and low-temperature conditions [81].…”

“…Recently, IMEC reported achieving a device of GaN on Si that reached 1200 V [77][78][79], with performance comparable to that of SiC. The fabrication process involved the use of a CMOS-fab process-friendly method in 2022 [80,81]. However, it is worth noting that the production of SiC substrates remains a high-energy-consuming industry.…”

Research progress and prospect of GaN Schottky diodes

“…In terms of GaN epitaxial growth, vertical GaN-based SBDs fabricated by homogeneous epitaxy of high-quality GaN drift layers on GaN substrates have achieved the highest BFOM of 1.1 GW cm −2 in vertical GaN devices [96]. The QST (Qromis substrate technology) substrate technology is proposed to grow GaN on Si substrate, which can reduce parasitic effects, has high thermal conductivity and the ability to grow thick buffer layers [97], and it has been proved that high performance GaN-based devices can be fabricated based on this method [98]. Researchers are also trying various approaches to realize effective P-type GaN SBD, including the use of 2DHG (two-dimensional hole gas) to improve the hole mobility problem and thus enhance the forward characteristics of the devices [99].…”