Methods of Fabricating Nitride-Based Transistors with a Cap Layer and a Recessed Gate and Related Devices
AssigneeCree, Inc.
InventorsScott Sheppard, Richard Peter Smith
Life of this patent
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Abstract
An anneal of a gate recess prior to formation of a gate contact, such as a Schottky contact, may reduce gate leakage and/or provide a high quality gate contact in a semiconductor device, such as a transistor. The use of an encapsulation layer during the anneal may further reduce damage to the semiconductor in the gate recess of the transistor. The anneal may be provided, for example, by an anneal of ohmic contacts of the device. Thus, high quality gate and ohmic contacts may be provided with reduced degradation of the gate region that may result from providing a recessed gate structure as a result of etch damage in forming the recess.
Claims26
A method of fabricating a high electron mobility transistor (HEMT), comprising:
- forming a barrier layer;
- forming a cap layer on the barrier layer;
- forming ohmic contact recesses in the cap layer;
- forming ohmic contact material patterns in the ohmic contact recesses;
- forming a gate recess in the cap layer that extends to the barrier layer;
- forming an encapsulation layer on the cap layer, the ohmic contact material patterns and the gate recess;
- annealing the barrier layer, ohmic contact material patterns and cap layer with the gate recess, the ohmic contact material being annealed for a first time;
- removing the encapsulation layer;
- and then forming a gate contact in the annealed gate recess.
A method of fabricating a high electron mobility transistor, comprising:
- forming a first layer of GaN based semiconductor material on a substrate;
- forming a second layer of GaN based semiconductor material on the first layer, the second layer being configured to induce a two-dimensional electron gas in a region proximate an interface between the first layer and the second layer;
- forming a third layer of GaN based semiconductor material on the second layer of GaN based semiconductor material;
- forming ohmic contact recesses in the third layer of GaN based semiconductor material;
- forming ohmic contact material patterns in the ohmic contact recesses;
- forming a gate recess in the third layer that extends to the second layer;
- annealing the first layer, second layer, ohmic contact material patterns and third layer with the gate recess, the ohmic contact material being annealed for a first time;
- and then
- forming a gate contact in the annealed gate recess.
A high electron mobility transistor (HEMT), comprising:
- a barrier layer;
- a cap layer on the barrier layer;
- a gate recess in the cap layer that extends to the barrier layer;
- and
- a gate contact in the gate recess, wherein a sheet resistance of the barrier layer proximate the gate recess is substantially the same after an anneal of the barrier layer, the cap layer and the gate recess as an as grown sheet resistance of the barrier layer.
Dependencies are inferred from the claim text.