Substrate breakdown voltage improvement for group III-nitride on a silicon substrate

摘要

A method of making a high-electron mobility transistor (HEMT) includes forming an unintentionally doped gallium nitride (UID GaN) layer over a silicon substrate, a donor-supply layer over the UID GaN layer, a gate, a passivation layer over the gate and portions of the donor-supply layer, an ohmic source structure and an ohmic drain structure over the donor-supply layer and portions of the passivation layer. The source structure includes a source contact portion and an overhead portion. The overhead portion overlaps the passivation layer between the source contact portion and the gate, and may overlap a portion of the gate and a portion of the passivation layer between the gate and the drain structure.

主权项

1. A method comprising:
providing a silicon substrate; epitaxially growing a gallium nitride (GaN) layer over the silicon substrate; epitaxially growing a donor-supply layer over the GaN layer; forming a gate on the donor-supply layer; depositing a passivation film over the gate and the donor-supply layer; etching a portion of the passivation film to form a source opening and a drain opening exposing a portion of the donor-supply layer, wherein the source opening and the drain opening are disposed on opposite sides of the gate, wherein a top surface of the passivation film over at least a portion of the gate is not flat; depositing ohmic metal layers over the source opening, the drain opening and the passivation film; and etching a portion of the ohmic metal layers to form a source structure and a drain structure, wherein the source structure comprises a source overhead portion disposed over at least a portion of the passivation film between the source structure and the gate.