Leakage barrier for GaN based HEMT active device

摘要

An improved HEMT formed from a GaN material system is disclosed which has reduced gate leakage current and eliminates the problem of current constrictions resulting from deposition of the gate metal over the step discontinuities formed over the gate mesa. One or more GaN based materials are layered and etched to form a gate mesa with step discontinuities defining source and drain regions. In order to reduce the leakage current, the step discontinuities are back-filled with an insulating material, such as silicon nitride (SiN), forming a flat surface relative to the source and drain regions, to enable to the gate metal to lay flat. By back-filling the source and drain regions with an insulating material, leakage currents between the gate and source and the gate and drain are greatly reduced. In addition, current constrictions resulting from the deposition of the gate metal over a step discontinuity are virtually eliminated.

主权项

1. A process for forming a single high electron mobility transistor (HEMT) comprising:
depositing at least one layer of Gallium Nitride (GaN) based materials on a substrate; forming a single mesa from GaN based materials on said substrate, said mesa defining a top surface and opposing vertical sidewalls, wherein said top surface forms a gate region and said substrate adjacent said sidewalls further forms drain and source regions adjacent said opposing vertical sidewalls; depositing on top of said drain and source regions an insulating material in contact with said vertical sidewalls and flush with said top surface of said mesa; depositing gate metal on said top surface of said mesa and defining a gate contact, said gate metal overlapping said insulating material on top of said drain and source regions; and forming source and drain contacts in contact with said top surface of said insulating material deposited on top of said drain and source regions at least partially in direct contact with the same top surface on which said gate metal is deposited, the source and drain contacts extending to an outside edge of the insulating material that is flush with the top surface.