| 主权项 |
1. A method for fabricating a vertical gallium nitride (GaN) power device, the method comprising:
providing a GaN substrate with a top surface and a bottom surface, wherein a root-mean-square (RMS) surface roughness at the bottom surface of the GaN substrate is more than 20 nm and less than 200 nm; forming a device layer contacting the top surface of the GaN substrate; forming a metal contact on a top surface of the vertical GaN power device; forming a backside metal contacting the bottom surface of the GaN substrate by:
forming an aluminum adhesion layer directly coupled to the bottom surface of the GaN substrate, wherein the aluminum adhesion layer comprises a first material;forming a diffusion barrier coupled to the aluminum adhesion layer, wherein the diffusion barrier comprises a second material, wherein the second material is different from the first material;forming a protection layer coupled to the diffusion barrier, wherein the protection layer comprises a third material, wherein the third material is different from the first and second materials;forming a fourth layer as part of the aluminum adhesion layer, wherein the fourth layer comprises a fourth material, wherein the fourth material is different from the first, second, and third materials; andforming a fifth layer as part of the protection layer, wherein the fifth layer comprises a fifth material, wherein the fifth material is different from the first, second, third and fourth materials,wherein the third and fifth materials are selected from gold and silver with a total layer thickness between 100 nm to 900 nm, andwherein the first, fourth, second, third and fifth materials are stacked in sequential order,wherein the vertical GaN power device is configured to conduct electricity between the metal contact and the backside metal. |
