GROUP III NITRIDE EPITAXIAL SUBSTRATE AND METHOD FOR MANUFACTURING THE SAME

• US 20140209862A1
• Filed: 07/11/2012
• Published: 07/31/2014
• Est. Priority Date: 07/11/2011
• Status: Active Grant

• Current Assignee: Dowa Electronics Materials Co. Ltd. (DOWA Holdings Company Limited)
• Original Assignee: Dowa Electronics Materials Co. Ltd. (DOWA Holdings Company Limited)
• Inventors: Ikuta, Tetsuya, Shibata, Tomohiko
• Granted Patent: US 10,727,303 B2
• Time in Patent Office: Days
• US Class Current: 257/22
• CPC Class Codes: C30B 25/02 Epitaxial-layer growth
• CPC Class Codes: C30B 29/403 AIII-nitrides
• CPC Class Codes: C30B 29/68 Crystals with laminate structure, e.g. "superlattices"
• CPC Class Codes: H01L 21/02381 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/02458 Nitrides
• CPC Class Codes: H01L 21/02507 Alternating layers, e.g. superlattice
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 29/15 Structures with periodic or quasi periodic potential variation, e.g. multiple quantum wells, superlattices such structures applied for the control of light G02F1/017, applied in semiconductor lasers H01S5/34
• CPC Class Codes: H01L 29/155 Comprising only semiconductor materials H01L29/154 takes precedence
• CPC Class Codes: H01L 29/2003 Nitride compounds
• CPC Class Codes: H01L 29/66462 with a heterojunction interface channel or gate, e.g. HFET, HIGFET, SISFET, HJFET, HEMT
• CPC Class Codes: H01L 29/7787 with wide bandgap charge-carrier supplying layer, e.g. direct single heterostructure MODFET
• CPC Class Codes: H01L 33/007 comprising nitride compounds

Abstract

Provided is a Group III nitride epitaxial substrate that can suppress the occurrence of breakage during a device formation process and a method for manufacturing the same. A Group III nitride epitaxial substrate according to the present invention includes a Si substrate, an initial layer in contact with the Si substrate, and a superlattice laminate, formed on the initial layer, including a plurality of sets of laminates, each of the laminates including, in order, a first layer made of AlGaN with an Al composition ratio greater than 0.5 and 1 or less and a second layer made of AlGaN with an Al composition ratio greater than 0 and 0.5 or less. The Al composition ratio of the second layer progressively decreases with distance from the substrate.

Claims

1. A Group III nitride epitaxial substrate comprising:

an Si substrate;

an initial layer in contact with the Si substrate; and

a superlattice laminate, formed on the initial layer, including a plurality of sets of laminates, each of the laminates including, in order, a first layer made of AlGaN with an Al composition ratio greater than 0.5 and 1 or less and a second layer made of AlGaN with an Al composition ratio greater than 0 and 0.5 or less, wherein

the Al composition ratio of the second layer progressively decreases with distance from the Si substrate.

2. The Group III nitride epitaxial substrate according to claim 1, wherein

the superlattice laminate includes a plurality of superlattice layers each including a plurality of sets of the first layer and the second layer made of AlGaN with a constant Al composition ratio, the first layer and the second layer being alternately stacked, and

the Al composition ratio of the second layer of each superlattice layer in the superlattice laminate is smaller as a position of the superlattice layer is more distant from the Si substrate.

3. The Group III nitride epitaxial substrate according to claim 1, wherein a difference between the Al composition ratio of the second layer closest to the Si substrate and the Al composition ratio of the second layer farthest from the Si substrate is 0.02 or more.

4. The Group III nitride epitaxial substrate according to claim 1, wherein the first layer is AlN.

5. The Group III nitride epitaxial substrate according to claim 1, wherein the initial layer includes an AlN layer and an AlGaN layer on the AlN layer, and an Al composition ratio of the AlGaN layer in the initial layer is larger than the Al composition ratio of the AlGaN layer in the second layer closest to the substrate.

6. The Group III nitride epitaxial substrate according to claim 1, further comprising a main laminate formed by epitaxial growth, on the superlattice laminate, of a Group III nitride layer including at least a GaN layer.

7. The Group III nitride epitaxial substrate according to claim 1, wherein in a state with the superlattice laminate as an uppermost layer, an amount of warpage yielding a convex lower side is 130 μ

m or less.

8. A method for manufacturing a Group III nitride epitaxial substrate comprising:

a first step of forming, on an Si substrate, an initial layer in contact with the Si substrate; and

a second step of forming a superlattice laminate, on the initial layer, including a plurality of sets of laminates, each of the laminates including, in order, a first layer made of AlGaN with an Al composition ratio greater than 0.5 and 1 or less and a second layer made of AlGaN with an Al composition ratio greater than 0 and 0.5 or less, wherein

in the second step, the Al composition ratio of the second layer is caused to decrease progressively with distance from the substrate.