# US 7,608,526 B2 · Strained layers within semiconductor buffer structures

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- Number: US 7,608,526 B2
- Document ID: US7608526B2
- Status: Granted
- Kind: B2
- Application number: 11/491,616
- Filed: 2006-07-24
- Published: 2008-01-24
- Granted: 2009-10-27
- Earliest claimed: 2006-07-24
- Assignees: ASM America, Inc.; S.O.I. Tec Silicon on Insulator Technologies
- Inventors: Nyles W. Cody; Christophe Figuet; Mark Kennard
- Web page: https://patentgrep.com/patent/US7608526B2

## CPC

- H10P 14/2905: {Silicon, silicon germanium or germanium}
- H10P 14/3211: {Silicon, silicon germanium or germanium}
- H10P 14/3254: {Graded layers}
- H10P 14/3411: {Silicon, silicon germanium or germanium}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

A semiconductor workpiece including a substrate, a relaxed buffer layer including a graded portion formed on the substrate, and at least one strained transitional layer within the graded portion of the relaxed buffer layer and method of manufacturing the same. The at least one strained transitional layer reduces an amount of workpiece bow due to differential coefficient of thermal expansion (CTE) contraction of the relaxed buffer layer relative to CTE contraction of the substrate

## Claims

### Claim 1

A method of manufacturing a semiconductor workpiece, the method comprising:
providing a substrate;
depositing a relaxed buffer layer on the substrate; and
during depositing the relaxed buffer layer, depositing at least one strained transitional layer wherein depositing the relaxed buffer layer comprises depositing silicon and germanium in an epitaxial deposition reactor, wherein depositing the relaxed buffer layer comprises:
depositing a first portion of the relaxed buffer layer by flowing silicon and germanium precursors, a germanium concentration in the first portion of the relaxed buffer layer increasing as the first portion of the relaxed buffer layer is deposited;
after depositing the first portion of the relaxed buffer layer, depositing a first strained transition layer by pausing flowing the germanium precursors; and
after depositing the first strained transition layer, depositing a second portion of the relaxed buffer layer by resuming flowing the germanium precursors, a germanium concentration in the second portion of the relaxed buffer layer increasing as the second portion of the relaxed buffer layer is deposited.

### Claim 2 (depends on 1)

The method of claim 1, further comprising cooling the workpiece, wherein the at least one strained transitional layer is configured to reduce workpiece bow due to differential thermal contraction of the relaxed buffer layer relative to the substrate during cooling.

### Claim 3 (depends on 1)

The method of claim 1, further comprising cooling the workpiece, wherein the at least one strained transitional layer tends to counter an amount of stresses in the workpiece due to differential coefficient of thermal expansion (CTE) contraction of the relaxed buffer layer relative to CTE contraction of the substrate during cooling.

### Claim 4 (depends on 1)

The method of claim 1, wherein depositing the at least one strained transitional layer comprises depositing silicon in the epitaxial deposition reactor.

### Claim 5 (depends on 1)

The method of claim 1, wherein depositing the at least one strained transitional layer comprises depositing silicon and germanium in the epitaxial deposition reactor, the germanium concentration lower in the at least one strained transitional layer than at the surfaces of the relaxed buffer layer proximate to the at least one strained transitional layer.

### Claim 6 (depends on 1)

The method of claim 1, wherein a highest germanium concentration in the relaxed buffer layer is between about 15% and 25%.

### Claim 7 (depends on 6)

The method of claim 6, wherein depositing the relaxed buffer layer comprises depositing one to two strained transitional layers.

### Claim 8 (depends on 1)

The method of claim 1, wherein depositing the relaxed buffer layer further comprises:
after depositing the second portion of the relaxed buffer layer, depositing a second strained transition layer by pausing flowing the germanium precursors; and
after depositing the second strained transition layer, depositing a third portion of the relaxed buffer layer by resuming flowing the germanium precursors, a germanium concentration in the third portion of the relaxed buffer layer increasing as the third portion of the relaxed buffer layer is deposited.

### Claim 9 (depends on 1)

The method of claim 1, wherein a highest germanium concentration in the relaxed buffer layer is between about 25% and 35%.

### Claim 10 (depends on 9)

The method of claim 9, wherein depositing the relaxed buffer layer comprises depositing two to three strained transitional layers.

### Claim 11 (depends on 1)

The method of claim 1, wherein a highest germanium concentration in the relaxed buffer layer is between about 35% and 45%.

### Claim 12 (depends on 11)

The method of claim 11, wherein depositing the relaxed buffer layer comprises depositing three to five strained transitional layers.

### Claim 13 (depends on 1)

The method of claim 1, wherein the at least one strained transitional layer is configured to reduce the threading dislocation density to less than about 4×103/cm2.

### Claim 14 (depends on 1)

The method of claim 1, further comprising depositing a strained active layer on the relaxed buffer layer.

### Claim 15 (depends on 14)

The method of claim 14, wherein the strained active layer comprises silicon.

### Claim 16 (depends on 14)

The method of claim 14, wherein the strained active layer has a threading dislocation density less than about 104/cm2.

### Claim 17 (depends on 14)

The method of claim 14, wherein the strained active layer has a threading dislocation density less than about 4×103/cm2.

### Claim 18 (depends on 14)

The method of claim 14, further comprising transferring the strained active layer to a receiving substrate.

### Claim 19 (depends on 18)

The method of claim 18, wherein transferring the strained active layer to the receiving substrate comprises:
after depositing the strained active layer, creating a region of weakness in the relaxed buffer layer, the region of weakness configured to facilitate splitting of the workpiece;
after depositing the strained active layer, associating the receiving substrate with the strained active layer to form a composite structure; and
splitting the composite structure at the region of weakness in the relaxed buffer layer.

### Claim 20 (depends on 19)

The method of claim 19, wherein creating a region of weakness in the relaxed buffer layer comprises implanting with hydrogen.

### Claim 21 (depends on 1)

The method of claim 1, wherein depositing the relaxed buffer layer comprises:
depositing a germanium concentration in the relaxed buffer layer proximate to a bottom surface of the at least one strained transitional layer; and
depositing the germanium concentration in the relaxed buffer layer proximate to a top surface of the at least one strained transitional layer.

### Claim 22 (depends on 1)

An integrated circuit manufactured by the method of claim 1.

### Claim 23

A method of manufacturing a semiconductor workpiece, the method comprising:
providing a substrate;
depositing a first portion of a relaxed buffer layer on the substrate by flowing silicon precursors and germanium precursors while increasing a germanium concentration in the growing first portion of the relaxed buffer layer;
after depositing the first portion of the relaxed buffer layer, pausing flowing the germanium precursors while continuing to flow the silicon precursors; and
after pausing flowing the germanium precursors, depositing a second portion of the relaxed buffer layer by resuming flowing the germanium precursors and increasing a germanium concentration in the growing second portion of the relaxed buffer layer.

### Claim 24 (depends on 23)

The method of claim 23, wherein increasing the germanium concentration in the growing first portion of the relaxed buffer layer comprises reducing flowing the silicon precursors.

### Claim 25 (depends on 23)

The method of claim 23, wherein increasing the germanium concentration in the growing first portion of the relaxed buffer layer comprises increasing flowing the germanium precursors.

### Claim 26 (depends on 23)

The method of claim 23, wherein a duration of pausing flowing the germanium precursors is between about 0.1 and 10 seconds.

### Claim 27 (depends on 23)

The method of claim 23, wherein a duration of pausing flowing the germanium precursors is between about 0.5 and 5 seconds.

### Claim 28 (depends on 23)

The method of claim 23, wherein a duration of pausing flowing the germanium precursors is a time for a rotatable susceptor holding the workpiece to rotate at least once.

### Claim 29 (depends on 23)

The method of claim 23, wherein pausing flowing the germanium precursors comprises depositing strained silicon.

### Claim 30 (depends on 29)

The method of claim 29, wherein the deposited strained silicon is between about 1 and 10 nm thick.

### Claim 31 (depends on 29)

The method of claim 29, wherein the deposited strained silicon is between about 6 and 8 nm thick.

### Claim 32 (depends on 23)

The method of claim 23, wherein pausing flowing the germanium precursors comprises depositing strained silicon germanium.

### Claim 33 (depends on 23)

The method of claim 23, further comprising depositing a strained active layer on the relaxed buffer layer.

### Claim 34 (depends on 33)

The method of claim 33, wherein the strained active layer comprises silicon.

### Claim 35 (depends on 33)

The method of claim 33, further comprising transferring the strained active layer to a receiving substrate.

### Claim 36 (depends on 35)

The method of claim 35, wherein transferring the strained active layer to the receiving substrate comprises:
before depositing the strained active layer, creating a region of weakness in the relaxed buffer layer, the region of weakness configured to facilitate splitting of the workpiece;
after depositing the strained active layer, associating the receiving substrate with the strained active layer to form a composite structure; and
splitting the composite structure at the region of weakness in the relaxed buffer layer.

### Claim 37 (depends on 36)

The method of claim 36, wherein creating the region of weakness in the relaxed buffer layer comprises implanting with hydrogen.

### Claim 38 (depends on 23)

The method of claim 23, wherein depositing the second portion of the relaxed buffer layer comprises flowing the germanium precursors such that a germanium concentration in the first portion of the relaxed buffer layer proximate to a bottom surface of the strained transitional layer is substantially the same as a germanium concentration in the second portion of the relaxed buffer layer proximate to a top surface of the strained transitional layer.

### Claim 39 (depends on 23)

An integrated circuit manufactured by the method of claim 23.