# US 11,441,941 B2 · Superconducting nanowire single photon detector and method of fabrication thereof

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- Number: US 11,441,941 B2
- Document ID: US11441941B2
- Status: Granted
- Kind: B2
- Application number: 17/232,086
- Filed: 2021-04-15
- Published: 2021-08-05
- Granted: 2022-09-13
- Earliest claimed: 2019-04-16
- Assignees: Psiquantum, Corp.
- Applicants: PsiQuantum Corp
- Inventors: Chia-Jung Chung; Faraz Najafi; George Kovall; Vitor R. Manfrinato; Vimal Kamineni; Mark Thompson; Syrus Ziai
- Web page: https://patentgrep.com/patent/US11441941B2

## CPC

- G01J 1/0204: {Compact construction}
- G01J 1/0425: {using optical fibers}
- G01J 1/44: Electric circuits {(for command of an exposure part G03B7/02)}
- G01J 5/023: {Particular leg structure or construction or shape; Nanotubes}
- G01J 5/20: using resistors, thermistors or semiconductors sensitive to radiation, e.g. photoconductive devices
- H01B 12/06: Films or wires on bases or cores
- H10N 60/0156: {of devices comprising Nb or an alloy of Nb with one or more of the elements of group IVB, e.g. titanium, zirconium or hafnium}
- H10N 60/0241: {of devices comprising nitrides or carbonitrides}
- H10N 60/84: Switching means for devices switchable between superconducting and normal states
- G01J 2001/442: {Single-photon detection or photon counting}
- G01J 2005/208: {superconductive}
- Y02E 40/60: Superconducting electric elements or equipment; Power systems integrating superconducting elements or equipment
- G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N)
- H01B: CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES (selection for magnetic properties H01F1/00; waveguides H01P {; printed circuits H05K})
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A superconductor device is manufactured by depositing a barrier layer over a substrate including silicon, the barrier layer including silicon and nitrogen; depositing a seed layer for a superconductor layer over the barrier layer, the seed layer including aluminum and nitrogen; depositing the superconductor layer over the seed layer, the superconductor layer including a layer of a superconductor material, the barrier layer serving as an oxidation barrier between the layer superconductor material and the substrate; and depositing a silicon cap layer over the superconductor layer. In some embodiments, the superconductor device includes a waveguide and a metal contact at a sufficient distance from the waveguide to prevent optical coupling between the metal contact and the waveguide.

## Claims

### Claim 1

A method of manufacturing a superconductor device, comprising:
depositing a barrier layer over a substrate including silicon, the barrier layer including silicon and nitrogen;
depositing a seed layer for a superconductor layer over the barrier layer, the seed layer including aluminum and nitrogen;
depositing the superconductor layer over the seed layer, the superconductor layer including a layer of a superconductor material, the barrier layer serving as an oxidation barrier between the layer of the superconductor material and the substrate;
depositing a silicon cap layer over the superconductor layer;
patterning the silicon cap layer, the superconductor layer, the seed layer and the barrier layer to form a multilayer stack;
after forming the multilayer stack:
depositing a layer of protective material over the multilayer stack;
anisotropically etching the layer of protective material to form a plurality of sidewalls on sides of the multilayer stack; and
removing oxygen from the superconductor layer in an annealing process.

### Claim 2 (depends on 1)

The method of claim 1, further comprising obtaining the substrate, wherein obtaining the substrate comprises:
patterning a semiconductor layer of a semiconductor-on-insulator wafer to form a waveguide;
depositing a dielectric layer over the waveguide; and
planarizing the dielectric layer.

### Claim 3

A method of manufacturing a superconductor device, comprising:
depositing a barrier layer over a substrate including silicon, the barrier layer including silicon and nitrogen;
depositing a seed layer for a superconductor layer over the barrier layer, the seed layer including aluminum and nitrogen;
depositing the superconductor layer over the seed layer, the superconductor layer including a layer of a superconductor material, the barrier layer serving as an oxidation barrier between the layer of the superconductor material and the substrate;
depositing a silicon cap layer over the superconductor layer;
patterning the silicon cap layer, the superconductor layer, the seed layer and the barrier layer to form a multilayer stack;
after forming the multilayer stack:
depositing a dielectric layer; and
forming an electrical contact through the dielectric layer to a portion of the superconductor layer, wherein forming the electrical contact comprises:
etching a cavity in the dielectric layer to expose a portion of the silicon cap layer in the dielectric layer;
depositing a first metal to coat the portion of the silicon cap layer and exposed surfaces of the dielectric layer;
converting the portion of the silicon cap layer into a conductive compound; and
depositing a second metal to fill the cavity.

### Claim 4 (depends on 3)

The method of claim 3, wherein the first metal is selected from the group consisting of titanium, nickel, and cobalt, and wherein the second metal is selected from the group consisting of tungsten, aluminum, and copper.

### Claim 5 (depends on 3)

The method of claim 3, wherein the substrate includes a waveguide, and the portion of the silicon cap layer is located at a sufficient lateral distance from the waveguide to prevent optical coupling between the waveguide and the electrical contact.

### Claim 6 (depends on 1)

The method of claim 1, wherein the superconductor material includes niobium and one or more of nitrogen, titanium, aluminum, germanium, and tin.

### Claim 7 (depends on 6)

The method of claim 6, wherein the silicon cap layer includes one or more of amorphous silicon, polysilicon, and single-crystal silicon.

### Claim 8 (depends on 1)

The method of claim 1, wherein the superconductor material includes niobium nitride, and wherein the silicon cap layer includes amorphous silicon.

### Claim 9 (depends on 8)

The method of claim 8, further comprising depositing a protective layer after depositing the superconductor layer and before depositing the silicon cap layer, the protective layer including aluminum and nitrogen.

### Claim 10 (depends on 1)

The method of claim 1, further comprising, after forming the multilayer stack:
depositing a dielectric layer; and
forming an electrical contact through the dielectric layer to a portion of the superconductor layer, wherein forming the electrical contact comprises:
etching a cavity in the dielectric layer to expose a portion of the silicon cap layer in the dielectric layer;
depositing a first metal to coat the portion of the silicon cap layer and exposed surfaces of the dielectric layer;
converting the portion of the silicon cap layer into a conductive compound; and
depositing a second metal to fill the cavity.

### Claim 11 (depends on 10)

The method of claim 10, wherein the first metal is selected from the group consisting of titanium, nickel, and cobalt, and wherein the second metal is selected from the group consisting of tungsten, aluminum, and copper.

### Claim 12 (depends on 10)

The method of claim 10, wherein the substrate includes a waveguide, and the portion of the silicon cap layer is located at a sufficient lateral distance from the waveguide to prevent optical coupling between the waveguide and the electrical contact.

### Claim 13 (depends on 3)

The method of claim 3, further comprising obtaining the substrate, wherein obtaining the substrate comprises:
patterning a semiconductor layer of a semiconductor-on-insulator wafer to form a waveguide;
depositing a dielectric layer over the waveguide; and
planarizing the dielectric layer.

### Claim 14 (depends on 3)

The method of claim 3, wherein the superconductor material includes niobium and one or more of nitrogen, titanium, aluminum, germanium, and tin.

### Claim 15 (depends on 14)

The method of claim 14, wherein the silicon cap layer includes one or more of amorphous silicon, polysilicon, and single-crystal silicon.

### Claim 16 (depends on 3)

The method of claim 3, wherein the superconductor material includes niobium nitride, and wherein the silicon cap layer includes amorphous silicon.

### Claim 17 (depends on 16)

The method of claim 16, further comprising depositing a protective layer after depositing the superconductor layer and before depositing the silicon cap layer, the protective layer including aluminum and nitrogen.