Thermal mismatch compensation to produce free standing substrates by epitaxial deposition
AssigneeCBL Technologies, Inc.
InventorGlenn S. Solomon
Life of this patent
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Abstract
A method for producing thick, high quality GaN substrates uses an epitaxially deposited film is used as a substrate material for further device or epitaxial processing. The film is deposited using an epitaxial technique on a thin substrate called the disposable substrate. The deposited film is thick enough so that upon cooling the thermal mismatched strain is relieved through cracking of the lower disposable substrate and not the newly deposited epitaxy. The epitaxial film now becomes a platform for either further epitaxial deposition or device processing.
Claims30
A method for fabricating a thick layer of semiconductor material, the method comprising:
- depositing an epitaxial layer of the semiconductor material on a substrate at a growth temperature using a chemical vapor deposition technique, wherein the epitaxial layer has a thickness on the order of a thickness of the substrate, wherein the substrate is a compound substrate comprising a thin interlayer deposited upon a foundational substrate composed of a material selected from the group consisting of silicon, sapphire, and silicon carbide, and wherein the epitaxial layer and the substrate are thermally mismatched;
- and
- cooling down the epitaxial layer and the substrate, wherein thermal mismatch between the epitaxial layer and the substrate causes during the cooling down defect generation in the substrate and not in the epitaxy;
- whereby a thick, high quality layer of semiconductor material is produced.
A method for fabricating a thick layer of semiconductor material, the method comprising:
- depositing an epitaxial layer of the semiconductor material on a substrate at a growth temperature using a chemical vapor deposition technique, wherein the epitaxial layer has a thickness on the order of a thickness of the substrate, and wherein the epitaxial layer and the substrate are thermally mismatched;
- and
- cooling down the epitaxial layer and the substrate, wherein thermal mismatch between the epitaxial layer and the substrate causes during the cooling down defect generation in the substrate and not in the epitaxy;
- wherein the substrate is patterned such that the defect generation in the substrate during cooling down is facilitated;
- whereby a thick, high quality layer of semiconductor material is produced.
A layer of semiconductor material epitaxially deposited on a substrate, wherein the layer of semiconductor material has a thickness on the order of a thickness of the substrate, wherein the epitaxial layer and the substrate are thermally mismatched, wherein the substrate is patterned, and wherein defects are present in the substrate due to thermal mismatch.
A method of fabricating an epitaxial layer of semiconductor material on a thermally mismatched substrate without inducing thermal mismatch defects in the epitaxial layer, the method comprising:
- chemical vapor phase depositing the epitaxial layer of the semiconductor material on the thermally mismatched substrate at a growth temperature, wherein the deposited epitaxial layer is deposited to a thickness on the same order as a thickness of the substrate, wherein the substrate comprises a material chosen from the group consisting of sapphire, silicon, silicon oxide, silicon nitride, and silicon carbide, and wherein the epitaxial layer of semiconductor material comprises a material chosen from the group consisting of GaN, InN, AlN, and alloys of GaN, InN, and AlN;
- and
- generating thermal mismatch defects in the substrate by cooling down from the growth temperature the substrate and the deposited epitaxial layer, wherein the thermal mismatch defects generated in the substrate relieve thermal mismatch strain between the substrate and epitaxial layer caused by cooling;
- whereby the epitaxial layer is fabricated on a thermally mismatched substrate without inducing thermal mismatch defects in the bulk of the epitaxial layer.
A semiconductor material comprising:
- a substrate comprising a material chosen from the group consisting of sapphire, silicon, silicon oxide, silicon nitride, and silicon carbide;
- and
- an epitaxial layer comprising a material chosen from the group consisting of GaN, InN, AlN, and alloys of GaN, InN, and AlN;
- wherein the epitaxial layer is deposited on the substrate;
- wherein the substrate and epitaxial layer are thermally mismatched;
- wherein the epitaxial layer has a thickness on the same order as a thickness of the substrate;
- and
- wherein the substrate contains thermal mismatch defects caused by cooling down from the growth temperature the substrate and the epitaxial layer deposited on the substrate;
- and
- wherein the bulk of the epitaxial layer contains no thermal mismatch defects.
Dependencies are inferred from the claim text.