# US 9,520,531 B2 · Systems and methods for depositing and charging solar cell layers

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- Number: US 9,520,531 B2
- Document ID: US9520531B2
- Status: Granted
- Kind: B2
- Application number: 13/954,099
- Filed: 2013-07-30
- Published: 2014-02-27
- Granted: 2016-12-13
- Earliest claimed: 2010-07-27
- Assignees: Amtech Systems, LLC
- Applicants: Amtech Systems, Inc.
- Inventors: Jeong-Mo Hwang
- Web page: https://patentgrep.com/patent/US9520531B2

## CPC

- H10F 71/129: {Passivating}
- H01J 37/32082: {Radio frequency generated discharge (H01J37/32357, H01J37/32366, H01J37/32394 and H01J37/32403 take precedence)}
- H01J 37/32146: {Amplitude modulation, includes pulsing}
- H01J 37/32706: {Polarising the substrate}
- H10F 10/14: Photovoltaic cells having only PN homojunction potential barriers
- H10F 77/311: {for photovoltaic cells}
- H10F 77/315: {the coatings being antireflective or having enhancing optical properties}
- Y02E 10/547: Monocrystalline silicon PV cells
- Y02P 70/50: Manufacturing or production processes characterised by the final manufactured product
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

Systems and methods of the present invention may be used to charge a layer (such as a passivation layer and/or antireflective layer) of a solar cell (e.g., wafer) with a positive or negative charge. The layer may retain the charge to improve operation of the solar cell. The charged layer may include any suitable dielectric material capable of retaining either a negative or a positive charge. Systems and methods of the present invention permit in-situ charging of a layer. Charging of a layer may be accomplished during or after deposition of the layer including after completing the whole solar cell process, in other words, on a finished cell.

## Claims

### Claim 1

A method, performed by a system, for charging a layer of a wafer, the method comprising:
forming the layer on the wafer, the layer comprising no permanently stored charge;
generating a plasma from an inert gas, the plasma comprising electrons and positive ions, the wafer positioned proximate to the plasma, the layer oriented toward the plasma;
providing a pulse to the wafer to electrically bias the wafer; and responsive to the electrical bias, extracting at least one of electrons and positive ions from the plasma to substantially permanently charge the layer of the wafer.

### Claim 2 (depends on 1)

The method of claim 1 wherein:
the plasma further comprises photons having a magnitude of energy of about 3 eV; and
the photons from the plasma generate electron-hole pairs in the silicon that cooperate with the at least one of electrons and positive ions extracted from the plasma to charge the layer.

### Claim 3 (depends on 1)

The method of claim 1 wherein:
providing comprises applying a positive bias; and
extracting comprises moving electrons from the plasma to the layer to negatively charge the layer.

### Claim 4 (depends on 1)

The method of claim 1 wherein:
providing comprises applying a negative bias; and
extracting comprises moving positive ions from the plasma to the layer to positively charge the layer.

### Claim 5 (depends on 1)

The method of claim 1 wherein:
the plasma further comprises photons having a magnitude of energy of about 3 eV;
providing comprises applying a negative bias; and
extracting comprises moving positive ions from the plasma to a surface of the layer whereby the positive ions attract electrons from electron-hole pairs generated in the silicon by the photons into the layer to negatively charge the layer.

### Claim 6 (depends on 1)

The method of claim 1 wherein:
providing comprises providing the pulse at a starting time and terminating the pulse at an ending time, an amount of time between the starting time and the ending time being the duration of the pulse; and
the duration of the pulse is in the range of 1 microsecond to 500 seconds.

### Claim 7 (depends on 1)

The method of claim 1 wherein a magnitude of the pulse is between 1 and 5,000 volts.

### Claim 8

A method, performed by a system, for charging a layer of a wafer, the method comprising:
forming the layer on the wafer, the layer comprising no permanently stored charge;
generating a plasma from an inert gas, the plasma comprising electrons and positive ions, the wafer positioned proximate to the plasma, the layer oriented toward the plasma;
electrically biasing the wafer to establish an electric field between the wafer and the plasma;
responsive to the electric field, extracting charged particles from the plasma to substantially permanently charge the layer.

### Claim 9 (depends on 8)

The method of claim 8 wherein:
electrically biasing comprises applying a positive voltage to the wafer; and
extracting comprises moving electrons from the plasma into the layer to negatively charge the layer.

### Claim 10 (depends on 8)

The method of claim 8 wherein:
electrically biasing comprises applying a negative voltage to the wafer; and
extracting comprises moving positive ions from the plasma into the layer to positively charge the layer.

### Claim 11 (depends on 8)

The method of claim 8 wherein:
the plasma further comprises photons having a magnitude of energy of about 3 eV;
electrically biasing comprises applying a negative voltage to the wafer; and
extracting comprises moving positive ions from the plasma to a surface of the layer whereby the positive ions attract electrons from electron-hole pairs generated in the silicon by the photons into the layer to negatively charge the layer.

### Claim 12 (depends on 8)

The method of claim 8 wherein:
electrically biasing comprises providing a pulse to the wafer, the pulse having a starting time and an ending time, an amount of time between the starting time and the ending time being the duration of the pulse; and
the duration of the pulse is in the range of 1 microsecond to 500 seconds.

### Claim 13 (depends on 8)

The method of claim 8 wherein biasing comprises providing a pulse to the wafer having a magnitude of between 1 and 5,000 volts.

### Claim 14 (depends on 8)

The method of claim 8 wherein the layer comprises a dielectric layer formed of silicon nitride (SiNx).

### Claim 15 (depends on 8)

The method of claim 8 wherein the layer comprises a dielectric layer formed of aluminum oxide (AlOx).

### Claim 16

A method, performed by a system, for charging a layer of a wafer, the method comprising:
forming the layer on the wafer, the layer comprising no permanently stored charge;
generating a plasma from an inert gas, the plasma comprising electrons, positive ions, and photons, the photons having a magnitude of energy of at least about 3 eV, the wafer positioned proximate to the plasma, the layer oriented toward the plasma;
applying a pulse to the wafer for a duration to electrically bias the wafer;
responsive to the electrical bias, extracting at least one of electrons and positive ions from the plasma to substantially permanently charge the layer of the wafer; and
responsive to the photons, generating electron-hole pairs in the silicon that cooperate with the at least one of electrons and positive ions to charge the layer.

### Claim 17 (depends on 16)

The method of claim 16 wherein:
applying comprises applying a negative bias; and
extracting comprises moving positive ions from the plasma to a surface of the layer whereby the positive ions attract electrons from electron-hole pairs into the layer to negatively charge the layer.

### Claim 18 (depends on 17)

The method of claim 17 wherein the layer comprises a stacked structure.

### Claim 19 (depends on 17)

The method of claim 17 wherein the stacked structure comprises silicon nitride (SiNx) sandwiched between silicon oxide (SiOx).

### Claim 20 (depends on 16)

The method of claim 16 wherein the duration is in the range of 1 microsecond to 500 seconds.

### Claim 21 (depends on 16)

The method of claim 16 wherein biasing comprises providing a pulse to the wafer having a magnitude of between 1 and 5,000 volts.