# US 10,770,657 B2 · High reliability phase-change material (PCM) radio frequency (RF) switch using trap-rich region

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- Number: US 10,770,657 B2
- Document ID: US10770657B2
- Status: Granted
- Kind: B2
- Application number: 16/692,802
- Filed: 2019-11-22
- Published: 2020-03-19
- Granted: 2020-09-08
- Earliest claimed: 2018-08-14
- Assignees: Newport Fab, LLC
- Applicants: Newport Fab, LLC
- Inventors: Gregory P. Slovin; Nabil El-Hinnawy; Jefferson E. Rose; David J. Howard
- Web page: https://patentgrep.com/patent/US10770657B2

## CPC

- H10N 70/021: {Formation of switching materials, e.g. deposition of layers}
- H10N 70/063: {by etching of pre-deposited switching material layers, e.g. lithography}
- H10N 70/231: {based on solid-state phase change, e.g. between amorphous and crystalline phases, Ovshinsky effect}
- H10N 70/823: {adapted for essentially horizontal current flow, e.g. bridge type devices}
- H10N 70/8613: {Heating or cooling means other than resistive heating electrodes, e.g. heater in parallel}
- H10N 70/8825: {Selenides, e.g. GeSe}
- H10N 70/8828: {Tellurides, e.g. GeSbTe}
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR

## Abstract

A semiconductor structure includes a semiconductor mesa situated on a semiconductor substrate, a trap-rich region comprising polycrystalline silicon adjacent to the semiconductor mesa, and a phase-change material (PCM) radio frequency (RF) switch. A heating element of the PCM RF switch is situated over the semiconductor mesa. An interconnect segment coupled to the PCM RF switch is situated over the trap-rich region. Alternatively, a semiconductor structure can include a trap-rich region adjacent to a single crystal region of the semiconductor substrate, where the trap-rich region is formed by implant damaging, and where the heating element of the PCM RF switch is situated over the single crystal region.

## Claims

### Claim 1

A semiconductor structure comprising:
a semiconductor mesa on a semiconductor substrate:
a trap-rich region adjacent to said semiconductor mesa;
a phase-change material (PCM) radio frequency (RF) switch, wherein a heating element of said PCM RF switch is situated over said semiconductor mesa;
wherein at least a portion of an interconnect segment coupled to said PCM RF switch is situated over said trap-rich region.

### Claim 2 (depends on 1)

The semiconductor structure of claim 1, wherein said semiconductor mesa comprises single crystal silicon.

### Claim 3 (depends on 1)

The semiconductor structure of claim 1, wherein said semiconductor substrate comprises high resistivity silicon substrate.

### Claim 4 (depends on 1)

The semiconductor structure of claim 1, wherein said trap-rich region comprises polycrystalline silicon.

### Claim 5 (depends on 1)

The semiconductor structure of claim 1, wherein said semiconductor mesa is a heat spreader for dissipating heat generated by said heating element.

### Claim 6 (depends on 1)

The semiconductor structure of claim 1, wherein said PCM RF switch includes a thermally conductive and electrically insulating segment situated over said heating element.

### Claim 7 (depends on 1)

The semiconductor structure of claim 1, wherein said PCM RF switch includes a PCM selected from the group consisting of germanium telluride (GeXTeY), germanium antimony telluride (GeXSbYTeZ), germanium selenide (GeXSeY), and any other chalcogenide.

### Claim 8

A method comprising:
etching a semiconductor substrate to form a semiconductor mesa on said semiconductor substrate;
forming a trap-rich layer over said semiconductor mesa and said semiconductor substrate;
removing said trap-rich layer from a top surface of said semiconductor mesa to form a trap-rich region adjacent to said semiconductor mesa;
forming a phase-change material (PCM) radio frequency (RF) switch, wherein a heating element of said PCM RF switch is situated over said semiconductor mesa;
forming an interconnect segment coupled to said PCM RF switch, wherein at least a portion of said interconnect segment is situated over said trap-rich region.

### Claim 9 (depends on 8)

The method of claim 8, further comprising, prior to said forming said trap-rich layer:
forming an oxide layer over said semiconductor mesa and said semiconductor substrate;
removing said oxide layer.

### Claim 10 (depends on 8)

The method of claim 8, wherein said PCM RF switch includes a thermally conductive and electrically insulating segment situated over said heating element.

### Claim 11

A semiconductor structure comprising:
a trap-rich region adjacent to a single crystal region of a semiconductor substrate;
a phase-change material (PCM) radio frequency (RF) switch, wherein a heating element of said PCM RF switch is situated over said single crystal region;
wherein at least a portion of an interconnect segment coupled to said PCM RF switch is situated over said trap-rich region.

### Claim 12 (depends on 11)

The semiconductor structure of claim 11, wherein said single crystal region comprises single crystal silicon.

### Claim 13 (depends on 11)

The semiconductor structure of claim 11, wherein said semiconductor substrate comprises high resistivity silicon substrate.

### Claim 14 (depends on 11)

The semiconductor structure of claim 11, wherein said trap-rich region comprises implant-damaged silicon.

### Claim 15 (depends on 11)

The semiconductor structure of claim 11, wherein said single crystal region is a heat spreader for dissipating heat generated by said heating element.

### Claim 16 (depends on 11)

The semiconductor structure of claim 11, wherein said PCM RF switch includes a thermally conductive and electrically insulating segment situated over said heating element.

### Claim 17 (depends on 11)

The semiconductor structure of claim 11, wherein said PCM RF switch includes a PCM selected from the group consisting of germanium telluride (GeXTeY), germanium antimony telluride (GeXSbYTeZ), germanium selenide (GeXSeY), and any other chalcogenide.

### Claim 18

A method comprising:
forming a mask over a semiconductor substrate;
implant damaging an exposed surface of said semiconductor substrate to form a trap-rich region adjacent to a single crystal region of said semiconductor substrate;
removing said mask;
forming a phase-change material (PCM) radio frequency (RF) switch, wherein a heating element of said PCM RF switch is situated over said single crystal region;
forming an interconnect segment coupled to said PCM RF switch, wherein at least a portion of said interconnect segment is situated over said trap-rich region.

### Claim 19 (depends on 18)

The method of claim 18, wherein said implant damaging uses an implant selected from the group consisting of argon (Ar), silicon (Si), germanium (Ge), krypton (Kr), xenon (Xe), carbon (C), oxygen (O), and nitrogen (N).

### Claim 20 (depends on 18)

The method of claim 18, wherein said PCM RF switch includes a thermally conductive and electrically insulating segment situated over said heating element.