# US 2014/0154834 A1 · Use of dopants with different diffusivities for solar cell manufacture

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- Number: US 2014/0154834 A1
- Document ID: US20140154834A1
- Status: Published application
- Kind: A1
- Application number: 13/890,592
- Filed: 2013-05-09
- Published: 2014-06-05
- Earliest claimed: 2008-03-05
- Assignees: Varian Semiconductor Equipment Associates, Inc.
- Applicants: Varian Semiconductor Equipment Associates, Inc.
- Inventors: Nicholas P.T. Bateman; Atul Gupta; Christopher Hatem; Deepak Ramappa
- Web page: https://patentgrep.com/patent/US20140154834A1

## CPC

- H10H 20/8215: {characterised by crystalline imperfections, e.g. dislocations; characterised by the distribution of dopants, e.g. delta-doping}
- H10F 10/146: {Back-junction photovoltaic cells, e.g. having interdigitated base-emitter regions on the back side}
- H10F 71/128: {Annealing}
- H10F 77/148: {Shapes of potential barriers}
- H10F 77/219: {Arrangements for electrodes of back-contact photovoltaic cells}
- H10P 30/204: {into Group IV semiconductors}
- H10P 30/21: {of electrically active species}
- H10P 30/225: {of a molecular ion, e.g. decaborane}
- H10P 30/28: characterised by an annealing step, e.g. for activation of dopants
- H10F 77/70: Surface textures, e.g. pyramid structures
- Y02E 10/547: Monocrystalline silicon PV cells
- Y02P 70/50: Manufacturing or production processes characterised by the final manufactured product
- H10H: INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- 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

A method of tailoring the dopant profile of a substrate by utilizing two different dopants, each having a different diffusivity is disclosed. The substrate may be, for example, a solar cell. By introducing two different dopants, such as by ion implantation, furnace diffusion, or paste, it is possible to create the desired dopant profile. In addition, the dopants may be introduced simultaneously, partially simultaneously, or sequentially. Dopant pairs preferably consist of one lighter species and one heavier species, where the lighter species has a greater diffusivity. For example, dopant pairs such as boron and gallium, boron and indium, phosphorus and arsenic, and phosphorus and antimony, can be utilized.

## Claims

### Claim 1

A method of creating a desired dopant profile in a solar cell, comprising:
selectively implanting a first dopant and a second dopant at least partially simultaneously into a region of a surface of said solar cell using patterned ion implantation, wherein said region is less than an entirety of said surface and wherein said second dopant has a similar conductivity and higher diffusivity than said first dopant; and
performing a thermal cycle to diffuse said first dopant and said second dopant into said solar cell, wherein said second dopant diffuses deeper into said solar cell than said first dopant; and
applying contacts to said solar cell, wherein said contacts are applied to said region with high concentration of said first dopant.

### Claim 2 (depends on 1)

The method of claim 1, wherein said first dopant and said second dopant are selected from the group consisting of nitrogen, phosphorus, arsenic, antimony, bismuth, boron, aluminum, gallium, and indium.

### Claim 3 (depends on 1)

The method of claim 1, wherein a flood implant is performed.

### Claim 4 (depends on 1)

The method of claim 1, wherein said first dopant is arsenic and said second dopant is phosphorus.

### Claim 5 (depends on 1)

The method of claim 1, wherein said first dopant is gallium and said second dopant is boron.

### Claim 6 (depends on 1)

The method of claim 1, wherein said patterned ion implantation comprises implanting through a stencil mask.

### Claim 7

A method of creating a desired dopant profile in a solar cell, comprising:
selectively implanting a first dopant and a second dopant at least partially simultaneously into a region of a surface of said solar cell through a stencil mask, wherein said region is less than an entirety of said surface and wherein said second dopant has a similar conductivity and higher diffusivity than said first dopant; and
performing a thermal cycle to diffuse said first dopant and said second dopant into said solar cell, wherein said second dopant diffuses deeper into said solar cell than said first dopant; and
applying contacts to said solar cell, wherein said contacts are applied to said region with high concentration of said first dopant.

### Claim 8 (depends on 7)

The method of claim 7, wherein said first dopant and said second dopant are selected from the group consisting of nitrogen, phosphorus, arsenic, antimony, bismuth, boron, aluminum, gallium, and indium.

### Claim 9 (depends on 7)

The method of claim 7, wherein a flood implant is performed.

### Claim 10 (depends on 7)

The method of claim 7, wherein said first dopant is arsenic and said second dopant is phosphorus.

### Claim 11 (depends on 7)

The method of claim 7, wherein said first dopant is gallium and said second dopant is boron.

### Claim 12

A method of creating a desired dopant profile in a solar cell, comprising:
selectively implanting a first dopant and a second dopant at least partially simultaneously into a region of a surface of said solar cell using patterned ion implantation, wherein said region is less than an entirety of said surface and wherein said second dopant has a similar conductivity and higher diffusivity than said first dopant, wherein said region with high concentration of said first dopant is configured for use with contacts on said solar cell.

### Claim 13 (depends on 12)

The method of claim 12, wherein said first dopant and said second dopant are selected from the group consisting of nitrogen, phosphorus, arsenic, antimony, bismuth, boron, aluminum, gallium, and indium.

### Claim 14 (depends on 12)

The method of claim 12, wherein a flood implant is performed.

### Claim 15 (depends on 12)

The method of claim 12, wherein said first dopant is arsenic and said second dopant is phosphorus.

### Claim 16 (depends on 12)

The method of claim 12, wherein said first dopant is gallium and said second dopant is boron.

### Claim 17 (depends on 12)

The method of claim 12, wherein said patterned ion implantation comprises implanting through a stencil mask.

### Claim 18 (depends on 12)

The method of claim 12, further comprising: performing a thermal cycle to diffuse said first dopant and said second dopant into said solar cell, wherein said second dopant diffuses deeper into said solar cell than said first dopant; and
applying contacts to said solar cell, wherein said contacts are applied to said region with high concentration of said first dopant.