# US 7,611,914 B1 · Method of fabricating turning mirror using sacrificial spacer layer and device made therefrom

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- Number: US 7,611,914 B1
- Document ID: US7611914B1
- Status: Granted
- Kind: B1
- Application number: 11/472,225
- Filed: 2006-06-16
- Granted: 2009-11-03
- Earliest claimed: 2006-06-16
- Assignees: The United States of America as represented by the Director, National Security Agency
- Inventors: John L. Fitz; Daniel S. Hinkel; Scott C. Horst
- Web page: https://patentgrep.com/patent/US7611914B1

## CPC

- H01S 5/026: Monolithically integrated components, e.g. waveguides, monitoring photo-detectors, drivers (stabilisation of output H01S5/06)
- H01S 5/1071: {Ring-lasers}
- H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL

## Abstract

The present invention is a method of fabricating a waveguide using a sacrificial spacer layer. The first step in this process is to fabricate the underlying optical semiconductor structure. A trench is then etched in this structure resulting in an underlying L-shaped structure. A sacrificial spacer layer is deposited in the trench. The waveguide is created in the trench on the sacrificial spacer layer using a mask layer to angle the vertex of the L-shaped structure. User-defined portions of the sacrificial spacer layer are subsequently removed to create air gaps between the waveguide and the sidewalls of the trench in the optical semiconductor.

## Claims

### Claim 1

A method for creating an optical semiconductor device comprising the steps of:
a) selecting a coherent photonic emitter structure;
b) etching a trench of a user-definable width in the coherent photonic emitter structure such that the coherent photonic emitter structure is substantially L-shaped, where the trench has two walls and a floor, and includes;
c) depositing a sacrificial spacer layer on the two walls and floor of a user-definable section of the trench;
d) fabricating a waveguide on the sacrificial spacer layer; and
e) removing a user-definable portion of the sacrificial spacer layer, where a user-definable portion of the sacrificial spacer is left on at least the floor of the trench to anchor the waveguide.

### Claim 2 (depends on 1)

The method of claim 1, wherein the step of fabricating a waveguide on the sacrificial spacer layer further includes the steps of:
a) depositing a waveguide material on a user-definable portion of the sacrificial spacer layer; and
b) etching any excess waveguide material to form the waveguide.

### Claim 3 (depends on 2)

The method of claim 2, wherein the step of selecting a coherent photonic emitter structure comprises selecting a coherent photonic emitter structure, wherein the coherent photonic emitter structure comprises a base structure, a first cladding layer, a core layer, a second cladding layer, a cap layer and an upper contact.

### Claim 4 (depends on 3)

The method of claim 3, wherein the step of depositing a sacrificial spacer layer on the two walls and floor of a user-definable section of the trench comprises depositing a sacrificial spacer layer on the two walls and floor of the trench and a user-definable portion of the upper contact that is not within the trench.

### Claim 5 (depends on 4)

The method of claim 4, wherein the step removing a user-definable portion of the sacrificial spacer layer comprises removing a user-definable portion of the sacrificial spacer layer, wherein the user definable portion comprises the entire sacrificial spacer layer on the upper contact that is not within the trench and a user-definable portion of the remainder of the sacrificial spacer layer.

### Claim 6 (depends on 5)

The method of claim 5, wherein the step of depositing a sacrificial spacer layer on the two walls and floor of the trench comprises depositing a sacrificial spacer layer on the two walls and floor of the trench and a user-definable portion of the upper contact that is not within the trench and further wherein the sacrificial spacer layer is deposited by a conformal process.

### Claim 7 (depends on 5)

The method of claim 5, wherein the step of removing a user-definable portion of the sacrificial spacer layer comprises removing a user-definable portion of the sacrificial spacer layer, wherein the user definable portion comprises the entire sacrificial spacer layer on the upper contact that is not within the trench, wherein the removal is performed by a timed etch process.