# US 9,520,293 B2 · Method for producing mechanically flexible silicon substrate

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- Number: US 9,520,293 B2
- Document ID: US9520293B2
- Status: Granted
- Kind: B2
- Application number: 14/238,526
- Filed: 2012-08-15
- Published: 2014-08-28
- Granted: 2016-12-13
- Earliest claimed: 2011-08-15
- Assignees: King Abdullah University of Science and Technology
- Applicants: Muhammad M. Hussain; Jhonathan P. Rojas
- Inventors: Muhammad M. Hussain; Jhonathan P. Rojas
- Web page: https://patentgrep.com/patent/US9520293B2

## CPC

- H10P 50/642: {Chemical etching}
- H10P 14/66: {characterised by the type of materials}
- H10P 90/12: {Preparing bulk and homogeneous wafers}
- H10W 42/00: Arrangements for protection of devices (arrangements for thermal protection H10W40/00)
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

A method for making a mechanically flexible silicon substrate is disclosed. In one embodiment, the method includes providing a silicon substrate. The method further includes forming a first etch stop layer in the silicon substrate and forming a second etch stop layer in the silicon substrate. The method also includes forming one or more trenches over the first etch stop layer and the second etch stop layer. The method further includes removing the silicon substrate between the first etch stop layer and the second etch stop layer.

## Claims

### Claim 1

A method for making a thin silicon substrate, comprising:
providing a silicon substrate;
forming a first etch stop layer in a bulk portion of the silicon substrate;
forming a second etch stop layer in the bulk portion of the silicon substrate;
forming one or more trenches over the first etch stop layer and the second etch stop layer;
removing the silicon substrate of the bulk portion between the first etch stop layer and the second etch stop layer by delivering chemical etchant through the formed one or more trenches; and
detaching a top silicon layer from the silicon substrate to form the thin silicon substrate.

### Claim 2 (depends on 1)

The method of claim 1, wherein the thin silicon substrate is flexible.

### Claim 3 (depends on 2)

The method of claim 2, further comprising producing high performance electronics directly on the flexible thin silicon substrate without any transfer process.

### Claim 4 (depends on 1)

The method of claim 1, wherein forming the first etch stop layer comprises implanting ions into the silicon substrate at a first depth.

### Claim 5 (depends on 4)

The method of claim 4, wherein forming the second etch stop layer comprises implanting ions into the silicon substrate at a second depth between the first depth and a surface of the silicon substrate, wherein the first etch stop layer and the second etch stop layer define a channel for delivery of the chemical etchant to remove the silicon substrate, and wherein at least one of the first depth and the second depth define, in part, a thickness of the formed thin silicon substrate.

### Claim 6 (depends on 1)

The method of claim 1, wherein the first etch stop layer comprises a Boron layer.

### Claim 7 (depends on 1)

The method of claim 1, wherein the second etch stop layer comprises a Boron layer.

### Claim 8 (depends on 1)

The method of claim 1, wherein forming one or more trenches comprises forming a protective layer over the silicon substrate.

### Claim 9 (depends on 8)

The method of claim 8, further comprising forming a photoresist layer over the protective layer.

### Claim 10 (depends on 9)

The method of claim 9, further comprising etching the photoresist layer, the protective layer and a portion of the silicon substrate.

### Claim 11 (depends on 10)

The method of claim 10, further comprising removing the photoresist layer.

### Claim 12 (depends on 11)

The method of claim 11, further comprising forming a vertical sidewall layer inside each of the one or more trenches.

### Claim 13 (depends on 12)

The method of claim 12, further comprising removing a portion of the vertical sidewall layer.

### Claim 14 (depends on 13)

The method of claim 13, further comprising removing the protective layer.