# US 2014/0197507 A1 · Buried waveguide photodetector

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- Number: US 2014/0197507 A1
- Document ID: US20140197507A1
- Status: Published application
- Kind: A1
- Application number: 13/741,416
- Filed: 2013-01-15
- Published: 2014-07-17
- Earliest claimed: 2013-01-15
- Assignees: International Business Machines Corporation
- Applicants: International Business Machines Corporation
- Inventors: SOLOMON ASSEFA; WILLIAM M. GREEN; STEVEN M. SHANK; YURII A. VLASOV
- Web page: https://patentgrep.com/patent/US20140197507A1

## CPC

- G02B 6/12004: {Combinations of two or more optical elements}
- G02B 6/131: {by using epitaxial growth (epitaxial growth for semiconductors H10P14/20)}
- G02B 6/132: by deposition of thin films
- G02B 6/136: by etching
- G02B 6/4257: {having a supporting carrier or a mounting substrate or a mounting plate (G02B6/3648 takes precedence)}
- G02B 6/4291: {by accessing the evanescent field of the light guide}
- H10F 10/165: the heterojunctions being Group IV-IV heterojunctions, e.g. Si/Ge, SiGe/Si or Si/SiC photovoltaic cells
- H10F 39/014: {of CMOS image sensors}
- H10F 39/18: Complementary metal-oxide-semiconductor [CMOS] image sensors; Photodiode array image sensors
- H10F 39/8033: {Photosensitive area}
- H10F 39/807: {Pixel isolation structures}
- H10F 71/1212: {consisting of germanium}
- H10F 71/1215: {comprising at least two Group IV elements, e.g. SiGe}
- H10F 77/122: comprising only Group IV materials
- H10F 77/413: {directly associated or integrated with the devices, e.g. back reflectors (directly associated or integrated with photovoltaic cells H10F77/42)}
- G02B 2006/12085: {Integrated}
- G02B 2006/121: {Channel; buried or the like}
- G02B 2006/12123: {Diode}
- H10D 84/0165: {the components including complementary IGFETs, e.g. CMOS devices}
- H10D 84/038: {using silicon technology, e.g. SiGe}
- H10F 55/26: {wherein the radiation-sensitive semiconductor devices have potential barriers}
- Y02E 10/50: Photovoltaic [PV] energy
- Y02E 10/547: Monocrystalline silicon PV cells
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A method of forming an integrated photonic semiconductor structure having a photodetector and a CMOS device may include forming the CMOS device on a first silicon-on-insulator region, forming a silicon optical waveguide on a second silicon-on-insulator region, and forming a shallow trench isolation (STI) region surrounding the silicon optical waveguide such that the shallow trench isolation electrically isolating the first and second silicon-on-insulator region. Within a first region of the STI region, a first germanium material is deposited adjacent a first side wall of the semiconductor optical waveguide. Within a second region of the STI region, a second germanium material is deposited adjacent a second side wall of the semiconductor optical waveguide, whereby the second side wall opposes the first side wall. The first and second germanium material form an active region that evanescently receives propagating optical signals from the first and second side wall of the semiconductor optical waveguide.

## Claims

### Claim 1

A method of forming an integrated photonic semiconductor structure having a photodetector device and a CMOS device comprising:
forming a well region for the CMOS device;
forming an isolation region for electrically isolating the photodetector device from the well region;
forming a semiconductor optical waveguide for propagating optical signals; and
depositing, within the isolation region, germanium material adjacent to a first portion of opposing side walls of the semiconductor optical waveguide, the first portion of the opposing sidewalls being substantially parallel with a travel direction of the propagating optical signals within the optical waveguide,
wherein the deposited germanium material forms an active region of the photodetector device for evanescently receiving the propagating optical signals from the first portion of the opposing sidewalls of the semiconductor optical waveguide structure.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
performing a thermal anneal process for simultaneously initiating activating well dopants within the well region and crystallizing the deposited germanium material that forms the active region.

### Claim 3 (depends on 2)

The method of claim 2, wherein the thermal anneal process comprises heating the integrated photonic semiconductor structure to a temperature of about 1030° C. for a period of about 5 seconds.

### Claim 4 (depends on 1)

The method of claim of claim 1, further comprising:
depositing an insulating oxide fill material over a second portion of the opposing side walls of the semiconductor optical waveguide, wherein the semiconductor optical waveguide comprises a core region and the insulating oxide fill material deposited over the second portion of opposing side walls comprises a cladding.

### Claim 5 (depends on 4)

The method of claim 4, wherein the insulating oxide fill material comprises a silicon dioxide (SiO2) material.

### Claim 6 (depends on 1)

The method of claim 1, wherein the deposited germanium material comprises a thickness of about 50-200 nm.

### Claim 7 (depends on 1)

The method of claim 1, wherein the depositing of the germanium material over the first portion of the opposing side walls comprises utilizing one of a physical vapor deposition (PVD) process, a plasma enhanced chemical vapor deposition (PECVD) process, a rapid thermal chemical vapor deposition (RTCVD) process, and a reduced pressure chemical vapor deposition (RPCVD) process.

### Claim 8 (depends on 1)

The method of claim 1, further comprising:
depositing an oxide liner within the isolation region prior to the depositing of the germanium material, wherein the oxide liner separates the first portion of the opposing side walls of the semiconductor optical waveguide from the adjacent deposited germanium material.

### Claim 9 (depends on 8)

The method of claim 8, wherein the oxide liner comprises a thickness of about 20-40 nm.

### Claim 10 (depends on 1)

The method of claim 1, wherein the isolation region comprises a shallow trench isolation (STI) region.

### Claim 11 (depends on 1)

The method of claim 1, wherein the semiconductor optical waveguide is formed from a silicon-on-insulator (SOI) layer located over a buried oxide (BOX) layer.

### Claim 12 (depends on 1)

The method of claim 1, wherein the CMOS device comprises an FET.

### Claim 13

A method of forming an integrated photonic semiconductor structure having a photodetector device and a CMOS device comprising:
forming the CMOS device on a first silicon-on-insulator region;
forming a silicon optical waveguide on a second silicon-on-insulator region;
forming a shallow trench isolation region surrounding the silicon optical waveguide, the shallow trench isolation electrically isolating the first and the second silicon-on-insulator region;
depositing, within a first region of the shallow trench isolation region, first germanium material adjacent a first side wall of the semiconductor optical waveguide; and
depositing, within a second region of the shallow trench isolation region, second germanium material adjacent a second side wall of the semiconductor optical waveguide, the second side wall opposing the first side wall;
wherein the deposited first and the deposited second germanium material form an active region of the photodetector device for evanescently receiving propagating optical signals from the first and the second side wall of the semiconductor optical waveguide.

### Claim 14 (depends on 13)

The method of claim 13, wherein the deposited first and the deposited second germanium material are respectively separated from the first and the second side wall of the semiconductor optical waveguide by an oxide liner.

### Claim 15 (depends on 14)

The method of claim 14, wherein the oxide liner comprises an oxide layer having a thickness of about 20-40 nm.

### Claim 16 (depends on 13)

The method of claim 13, wherein the shallow trench isolation region comprises a silicon dioxide (SiO2) fill material.

### Claim 17 (depends on 13)

The method of claim 13, wherein the deposited first and the deposited second germanium material each comprises a thickness of about 50-200 nm.

### Claim 18

An integrated photonic semiconductor structure comprising:
a substrate;
an isolation region;
a CMOS device located on the substrate;
a semiconductor optical waveguide structure located on the substrate and electrically isolated from the CMOS device by the isolation region, the semiconductor optical waveguide structure having a first side wall and a second side wall that opposes the first side wall;
a photodetector located within the isolation region, the photodetector having a first and a second germanium active region, the first germanium active region located adjacent to the first side wall of the waveguide structure and the second germanium active region located adjacent to the second side wall of the waveguide structure,
wherein the first and the second germanium active region evanescently receive propagating optical signals from the first and the second side wall of the semiconductor optical waveguide.

### Claim 19 (depends on 18)

The structure of claim 18, wherein the first germanium active region is separated from the first side wall of the semiconductor optical waveguide by a first oxide liner, and the second germanium active region is separated from the second side wall of the semiconductor optical waveguide by a second oxide liner.

### Claim 20 (depends on 19)

The structure of claim 19, wherein the first and the second oxide liner comprise oxide layers each having a thickness of about 20-40 nm.

### Claim 21 (depends on 18)

The structure of claim 18, wherein the shallow trench isolation region comprises a silicon dioxide (SiO2) fill material.

### Claim 22 (depends on 18)

The structure of claim 18, wherein the first and the second germanium active region comprises a thickness of about 50-200 nm.

### Claim 23 (depends on 18)

The structure of claim 18, wherein the semiconductor optical waveguide propagates optical signals having a wavelength of about 1550 nm.

### Claim 24 (depends on 18)

The structure of claim 18, wherein the semiconductor optical waveguide propagates optical signals having a wavelength of about 1310 nm.

### Claim 25

A design structure tangibly embodied in a machine readable medium for designing, manufacturing, or testing an integrated circuit, the design structure comprising:
a substrate;
an isolation region;
a CMOS device located on the substrate;
a semiconductor optical waveguide structure located on the substrate and electrically isolated from the CMOS device by the isolation region, the semiconductor optical waveguide structure having a first side wall and a second side wall that opposes the first side wall;
a photodetector located within the isolation region, the photodetector having a first and a second germanium active region, the first germanium active region located adjacent to the first side wall of the waveguide structure and the second germanium active region located adjacent to the second side wall of the waveguide structure,
wherein the first and the second germanium active region evanescently receive propagating optical signals from the first and the second side wall of the semiconductor optical waveguide.