【Substrate Papers】Ultra-Wide Bandgap Semiconductor Direct Wafer Bonding: AlN/Diamond and Ga₂O₃/SiC

      Researchers from University of Florida have published a dissertation titled " Ultra-Wide Bandgap Semiconductor Direct Wafer Bonding: AlN/Diamond and Ga₂O₃/SiC " in ECS Meeting Abstracts.

Abstract

      Ultra-wide bandgap (UWBG) semiconductors present unique opportunities for the advancement of power devices and optoelectronics due characteristics like higher critical fields or higher carrier mobilities as compared to conventional silicon. However, these materials systems individually face various challenges in one type of doping or low thermal conductivity. Combining different UWBG materials to create thermal management layers or devices like pn-diodes (PND) presents a solution to overcome an individual material’s disadvantages. Diamond, for example, can be easily doped p-type with boron, but n-type doping is significantly more difficult due to hydrogen passivation, dopant solubility, and deep donor formation. To create a PND, p-type diamond can be combined with n-type AlN, which instead has difficulty with p-type doping. Additionally, diamond, owing to is high thermal conductivity (2200 W/m-K), is well suited for thermal management layers to help dissipate heat as devices are further miniaturized and increased power densities and temperatures negatively impact device lifetimes. However, as promising as AlN and diamond may be, substrates of either are still significantly expensive and only small 2” and 1” wafers, respectively, are readily and commercially available. As such, Ga₂O₃ is also of interest due to its ability to be conveniently grown from melt in addition to the standard high critical field expected of UWBG semiconductors although its very low thermal conductivity remains an issue. To counteract, SiC, also readily available, can be used as a heat-spreading substrate for Ga₂O₃-based devices. Heterogenous integration through epitaxy, however, is faced with thermal expansion coefficient and lattice mismatch challenges that can cause excessive threading dislocations and poor film qualities. Therefore, we aim to address these challenges by demonstrating and optimizing direct wafer bonding of these UWBG semiconductors.

DOI：

https://doi.org/10.1149/MA2026-01331489mtgabs