# US 2021/0344173 A1 · Fabrication of semiconductor structures

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- Number: US 2021/0344173 A1
- Document ID: US20210344173A1
- Status: Published application
- Kind: A1
- Application number: 16/865,973
- Filed: 2020-05-04
- Published: 2021-11-04
- Earliest claimed: 2020-05-04
- Assignees: International Business Machines Corporation
- Applicants: International Business Machines Corporation
- Inventors: Noelia Vico Trivino; Kirsten Emilie Moselund; Markus Scherrer
- Web page: https://patentgrep.com/patent/US20210344173A1

## CPC

- H01S 5/021: {Silicon based substrates}
- H01S 5/0217: {Removal of the substrate}
- H01S 5/0424: {lateral current injection}
- H01S 5/11: Comprising a photonic bandgap structure
- H01S 5/1225: {with a varying coupling constant along the optical axis}
- H01S 5/1228: {DFB lasers with a complex coupled grating, e.g. gain or loss coupling}
- H01S 5/32: comprising PN junctions, e.g. hetero- or double- heterostructures (H01S5/34, H01S5/36 take precedence)
- H10P 14/276: {Lateral overgrowth}
- H10P 14/69215: {the material being a silicon oxide, e.g. SiO2}
- H10P 50/642: {Chemical etching}
- G02B 6/1225: {comprising photonic band-gap structures or photonic lattices}
- G02B 6/131: {by using epitaxial growth (epitaxial growth for semiconductors H10P14/20)}
- H01S 5/0218: {Substrates comprising semiconducting materials from other groups of the Periodic Table than the materials of the active layer}
- H01S 5/1231: {Grating growth or overgrowth details}
- H01S 2304/04: MOCVD or MOVPE
- 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
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

The invention relates to a method for fabricating a semiconductor structure. The method comprises fabricating a photonic crystal structure of a first material, in particular a first semiconductor material and selectively removing the first material within a predefined part of the photonic crystal structure. The method further comprises replacing the first material within the predefined part of the photonic crystal structure with one or more second materials by selective epitaxy. The one or more second materials may be in particular semiconductor materials. The invention further relates to devices obtainable by such a method.

## Claims

### Claim 1

A method for fabricating a semiconductor structure, the method comprising:
fabricating a photonic crystal structure of a first material;
selectively removing the first material within a predefined part of the photonic crystal structure; and
replacing the first material within the predefined part of the photonic crystal structure with one or more second materials by selective epitaxy.

### Claim 2 (depends on 1)

The method as claimed in claim 1, wherein the predefined part of the photonic crystal structure is a central part of the photonic crystal structure.

### Claim 3 (depends on 1)

The method as claimed in claim 1, wherein fabricating the photonic crystal structure comprises:
providing a wafer comprising a layer of the first material; and
patterning the layer of the first material, thereby fabricating the photonic crystal structure of the first material.

### Claim 4 (depends on 3)

The method as claimed in claim 3, wherein the wafer is a silicon-on-insulator wafer comprising a silicon layer on an insulating layer.

### Claim 5 (depends on 3)

The method as claimed in claim 3, wherein replacing the first material with the one or more second materials comprises growing the one or more second materials in a lateral direction of the wafer.

### Claim 6 (depends on 5)

The method as claimed in claim 5, further comprising growing the one or more second materials with a predefined doping profile in the lateral direction of the wafer.

### Claim 7 (depends on 5)

The method as claimed in claim 5, further comprising growing two different second materials in the lateral direction of the wafer, thereby forming one or more lateral heterojunction.

### Claim 8 (depends on 1)

The method as claimed in claim 1, wherein selectively removing the first material within the predefined part of the photonic crystal structure comprises:
encapsulating the photonic crystal structure of the first material with a third material;
selectively removing a part of the third material in the predefined part of the photonic crystal structure to provide a window to the first material; and
selectively removing a part of the first material through the window, thereby creating a template structure of the third material, wherein a remaining part of the first material forms a seed structure for the one or more second materials.

### Claim 9 (depends on 8)

The method as claimed in claim 8, wherein selectively removing the predefined part of the first material through the window comprises performing a selective etching of the first material.

### Claim 10 (depends on 8)

The method as claimed in claim 8, wherein replacing the first material with the one or more second materials comprises growing the one or more second materials within the template structure of the third material from the seed structure.

### Claim 11 (depends on 1)

The method as claimed in claim 1, wherein the photonic crystal structure of the first material comprises a plurality of rods of the first material.

### Claim 12 (depends on 8)

The method as claimed in claim 8, further comprising removing the seed structure of the first material after the growing of the one or more second materials within the template structure.

### Claim 13 (depends on 1)

The method as claimed in claim 1, further comprising providing electrical contacts to the one or more second materials.

### Claim 14 (depends on 1)

The method as claimed in claims in claim 1, wherein patterning the first material comprises performing an etching based on HBr chemistry.

### Claim 15 (depends on 1)

The method as claimed in claim 1, wherein the growing of the one or more second materials is performed by one of: metal organic chemical vapor deposition (MOCVD); atmospheric pressure CVD; low or reduced pressure CVD; ultra-high vacuum CVD; molecular beam epitaxy (MBE); atomic layer deposition (ALD) and hydride vapor phase epitaxy.

### Claim 16 (depends on 1)

The method as claimed in claim 1, wherein the one or more second materials are optically active materials.

### Claim 17 (depends on 1)

The method as claimed in claim 1, wherein the one or more second materials are selected from the group consisting of: InP; InGaAs; AlGaAs; GaAs; GaN; InGaN; AlGaN; a ternary or a quaternary alloy thereof; group II-VI semiconductors and group IV semiconductors.

### Claim 18 (depends on 1)

The method as claimed in claim 1, wherein the first material is silicon.

### Claim 19 (depends on 1)

The method as claimed in claim 1, wherein the third material from the seed structure is a dielectric material, in particular an oxide.

### Claim 20 (depends on 1)

A semiconductor device obtainable by the method according to claim 1.

### Claim 21

A semiconductor device, comprising:
a semiconductor substrate;
an insulating layer on the semiconductor substrate; and
a photonic crystal structure on the insulating layer, the photonic crystal structure comprising a first material in an outer part and one or more second materials in a central part of the photonic crystal structure, wherein the one or more second materials are epitaxially grown semiconductor materials forming a gain structure which extends in a lateral direction of the substrate.

### Claim 22 (depends on 21)

The semiconductor device according to claim 21, wherein the first material is silicon and the one or more second materials are selected from the group consisting of: InP; InGaAs; AlGaAs; GaAs; GaN; InGaN; AlGaN; a ternary or a quaternary alloy thereof; group II-VI semiconductors and group IV semiconductors.

### Claim 23 (depends on 21)

The semiconductor device according to claim 21, wherein the one or more second materials comprise a predefined doping profile in the lateral direction of the substrate.

### Claim 24 (depends on 21)

The semiconductor device according to claim 21, wherein the central part comprises two different semiconductors materials forming a heterojunction in the lateral direction of the substrate.

### Claim 25 (depends on 21)

The semiconductor device according to claim 21, wherein the photonic crystal structure is 1-dimensional, 2-dimensional, or 3-dimensional photonic crystal lattice.