High electron mobility transistor device and methods for forming the same
AssigneeVanguard International Semiconductor Corporation
InventorsChi-Feng Hsieh, Tuan-Wei Wang, Chien-Jen Sun
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Abstract
A high electron mobility transistor device includes a substrate, a plurality of pairs of alternating layers, at least one stress-relief layer and a gallium nitride layer. The plurality of pairs of alternating layers is disposed over the substrate, and each pair of alternating layers includes a carbon-doped gallium nitride layer and an undoped gallium nitride layer. The stress-relief layer is disposed between the pairs of alternating layers. The gallium nitride layer is disposed over the alternating layers.
Claims17
A high electron mobility transistor device, comprising:
- a substrate;
- a buffer layer disposed over the substrate, wherein the buffer layer comprises a gradient buffer layer disposed over a superlattice buffer layer, and wherein the superlattice buffer layer comprises a plurality of pairs of AlN layers and AlGaN layers, the gradient buffer layer comprises a plurality of AlGaN layers with different concentrations, and one of the plurality of AlGaN layers of the gradient buffer layer is in contact with one of the AlN layers of the superlattice buffer layer;
- a plurality of pairs of alternating layers disposed over the substrate buffer layer, wherein each pair of alternating layers comprises a carbon-doped gallium nitride layer and an undoped gallium nitride layer, and a topmost layer of the pairs of alternating layers is a topmost undoped gallium nitride layer;
- a stress-relief layer disposed over the topmost undoped gallium nitride layer;
- a gallium nitride layer disposed over the stress-relief layer, wherein the stress-relief layer is in contact with the gallium nitride layer and the topmost undoped gallium nitride layer;
- and
- a barrier layer disposed over the gallium nitride layer, wherein a 2DEG is created at the interface between the gallium nitride layer and the barrier layer.
A method for forming high electron mobility transistor devices, comprising:
- forming a substrate;
- forming a buffer layer over the substrate, wherein the buffer layer comprises a gradient buffer layer formed over a superlattice buffer layer, and wherein the superlattice buffer layer comprises a plurality of pairs of AlN layers and AlGaN layers, the gradient buffer layer comprises a plurality of AlGaN layers with different concentrations, and one of the plurality of AlGaN layers of the gradient buffer layer is in contact with one of the AlN layers of the superlattice buffer layer;
- forming a plurality of pairs of alternating layers over the buffer layer, wherein each pair of alternating layers comprises a carbon-doped gallium nitride layer and an undoped gallium nitride layer, and a topmost layer of the pairs of alternating layers is a topmost undoped gallium nitride layer;
- forming a stress-relief layer over the topmost undoped gallium nitride layer;
- forming a gallium nitride layer over the stress-relief layer, wherein the stress-relief layer is in contact with the gallium nitride layer and the topmost undoped gallium nitride layer;
- and
- forming a barrier layer disposed over the gallium nitride layer, wherein a 2DEG is created at the interface between the gallium nitride layer and the barrier layer.
Dependencies are inferred from the claim text.