Solar cell and method of manufacturing the same

• US 20040112426A1
• Filed: 12/10/2003
• Published: 06/17/2004
• Est. Priority Date: 12/11/2002
• Status: Abandoned Application

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Hagino, Masato
• Application Number:
  US10/731,009
• Publication Number:
  US 20040112426A1
• Time in Patent Office: Days
• US Class Current: 136/261
• CPC Class Codes: H01L 31/022425 for solar cells
• CPC Class Codes: H01L 31/0236 Special surface textures
• CPC Class Codes: H01L 31/02363 of the semiconductor body itself, e.g. textured active layers
• CPC Class Codes: Y02E 10/547 Monocrystalline silicon PV cells

Abstract

A solar cell includes a dopant diffusion layer formed on the side of a light-receiving surface of a silicon wafer and a light-receiving surface passivation film formed on the dopant diffusion layer. The light-receiving surface passivation film has an opening portion. The solar cell further includes a light-receiving surface electrode formed on the opening portion of the light-receiving surface passivation film. The dopant diffusion layer has a first region covered with the light-receiving surface passivation film and a second region under the opening portion of the light-receiving surface passivation film, and there is a difference between a dopant concentration in the first region and a dopant concentration in the second region. Thus, a solar cell suitable for manufacturing a mass-produced commercial solar battery at low cost and high efficiency as well as a method of manufacturing the same can be provided.

Claims

1. A solar cell comprising:

a dopant diffusion layer formed on a side of a light-receiving surface of a silicon wafer;

a light-receiving surface passivation film formed on said dopant diffusion layer, said light-receiving surface passivation film having an opening portion; and

a light-receiving surface electrode formed on the opening portion of said light-receiving surface passivation film, wherein

said dopant diffusion layer has a first region covered with said light-receiving surface passivation film and a second region under the opening portion of said light-receiving surface passivation film, and there is a difference between a dopant concentration in said first region and a dopant concentration in said second region.

2. The solar cell according to claim 1, wherein

said light-receiving surface passivation film is any one of a silicon oxide film, an amorphous silicon film, a silicon nitride film, a titanium oxide film, and an aluminum oxide film.

3. The solar cell according to claim 1, wherein

the opening portion of said light-receiving surface passivation film in the light-receiving surface of the silicon wafer has the same shape and size as a portion where said light-receiving surface electrode is formed, and a selective emitter cell structure is formed where a dopant is diffused at high concentration only in a portion in contact with said light-receiving surface electrode.

4. The solar cell according to claim 1, wherein

the opening portion of said light-receiving surface passivation film in the light-receiving surface of the silicon wafer is larger than a portion where said light-receiving surface electrode is formed, whereby even if misalignment occurs in forming said light-receiving surface electrode, said light-receiving surface electrode is formed on a portion where a dopant is diffused at high concentration.

5. The solar cell according to claim 1, further comprising a back surface passivation film formed on a back surface of said silicon wafer, said back surface passivation film having an opening portion, wherein

a back surface field layer that is a dopant diffusion layer on a side of the back surface of said silicon wafer is formed at least in a region under the opening portion of said back surface passivation film on the side of the back surface of said silicon wafer.

6. The solar cell according to claim 5, wherein

said back surface passivation film is any one of a silicon oxide film, an amorphous silicon film, and a silicon nitride film.

7. A method of manufacturing a solar cell, comprising:

a step of forming, on a light-receiving surface of a silicon wafer, a light-receiving surface passivation film having an opening portion; and

a light-receiving surface dopant diffusion step of forming, on a side of the light-receiving surface of said silicon wafer, a dopant diffusion layer having a difference between a dopant concentration in a first region covered with said light-receiving surface passivation film and a dopant concentration in a second region under the opening portion of said light-receiving surface passivation film, wherein

in said light-receiving surface dopant diffusion step, a PN junction is formed by applying an organic solvent solution containing a dopant onto the silicon wafer using a spin coater and introducing said silicon wafer in a furnace to diffuse the dopant into said silicon wafer.

8. The method of manufacturing a solar cell according to claim 7, wherein

said organic solvent solution containing a dopant is an organic solvent solution containing a dopant and titanium.

9. A method of manufacturing a solar cell, comprising:

a step of forming, on a light-receiving surface of a silicon wafer, a light-receiving surface passivation film having an opening portion; and

a light-receiving surface dopant diffusion step of forming, on a side of the light-receiving surface of said silicon wafer, a dopant diffusion layer having a difference between a dopant concentration in a first region covered with said light-receiving surface passivation film and a dopant. concentration in a second region under the opening portion of said light-receiving surface passivation film, wherein

in said light-receiving surface dopant diffusion step, a PN junction is formed by diffusing a solution containing a dopant rendered in a gaseous state into the silicon wafer.

10. A method of manufacturing a solar cell, comprising:

a step of forming, on a light-receiving surface of a silicon wafer, a light-receiving surface passivation film having an opening portion; and

a light-receiving surface dopant diffusion step of forming, on a side of the light-receiving surface of said silicon wafer, a dopant diffusion layer having a difference between a dopant concentration in a first region covered with said light-receiving surface passivation film and a dopant concentration in a second region under the opening portion of said light-receiving surface passivation film, wherein

in said light-receiving surface dopant diffusion step, a PN junction is formed by supplying a dopant into the silicon wafer through ion implantation.

11. A method of manufacturing a solar cell, comprising:

a step of forming, on a light-receiving surface of a silicon wafer, a light-receiving surface passivation film having an opening portion;

a step of forming, on a back surface of said silicon wafer, a back surface passivation film having an opening portion;

a light-receiving surface dopant diffusion step of forming, on a side of the light-receiving surface of said silicon wafer, a dopant diffusion layer having a difference between a dopant concentration in a first region covered with said light-receiving surface passivation film and a dopant concentration in a second region under the opening portion of said light-receiving surface passivation film; and

a back surface dopant diffusion step of forming a back surface field layer on a side of the back surface of said silicon wafer, wherein

in said back surface dopant diffusion step, a localized back surface field layer structure is formed by applying a paste including aluminum to the back surface of said silicon wafer by screen-printing and introducing said silicon wafer in a furnace to form the back surface field layer only in a region under the opening portion of said back surface passivation film on the side of the back surface of said silicon wafer.

12. A method of manufacturing a solar cell, comprising:

a step of forming, on a light-receiving surface of a silicon wafer, a light-receiving surface passivation film having an opening portion;

a step of forming, on a back surface of said silicon wafer, a back surface passivation film having an opening portion;

a light-receiving surface dopant diffusion step of forming, on a side of the light-receiving surface of said silicon wafer, a dopant diffusion layer having a difference between a dopant concentration in a first region covered with said light-receiving surface passivation film and a dopant concentration in a second region under the opening portion of said light-receiving surface passivation film; and

a back surface dopant diffusion step of forming a back surface field layer on a side of the back surface of said silicon wafer, wherein

in said back surface dopant diffusion step, a localized back surface field layer structure is formed by diffusing a solution containing a dopant rendered in a gaseous state into the back surface of said silicon wafer to form the back surface field layer only in a region under the opening portion of said back surface passivation film on the side of the back surface of said silicon wafer.

13. A method of manufacturing a solar cell, comprising:

a step of forming, on a light-receiving surface of a silicon wafer, a light-receiving surface passivation film having an opening portion;

a step of forming, on a back surface of said silicon wafer, a back surface passivation film having an opening portion;

a light-receiving surface dopant diffusion step of forming, on a side of the light-receiving surface of said silicon wafer, a dopant diffusion layer having a difference between a dopant concentration in a first region covered with said light-receiving surface passivation film and a dopant concentration in a second region under the opening portion of said light-receiving surface passivation film; and

a back surface dopant diffusion step of forming a back surface field layer on a side of the back surface of said silicon wafer, wherein

in said back surface dopant diffusion step, a localized back surface field layer structure is formed by supplying a dopant to the back surface of said silicon wafer through ion implantation to form the back surface field layer only in a region under the opening portion of said back surface passivation film on the side of the back surface of said silicon wafer.