|Publication number||USH2207 H1|
|Application number||US 11/650,595|
|Publication date||Dec 4, 2007|
|Filing date||Jan 5, 2007|
|Priority date||Jan 5, 2007|
|Publication number||11650595, 650595, US H2207 H1, US H2207H1, US-H1-H2207, USH2207 H1, USH2207H1|
|Inventors||Martin D. Bijker|
|Original Assignee||Bijker Martin D|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (4), Referenced by (5), Classifications (6)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This invention relates to the process sequence in the production of solar cells from raw crystalline p-type silicon wafer material.
Process tests show that the cell efficiencies obtained with the current production lines can be improved significantly by inserting one or more additional process steps.
The process sequence of the existing production lines is shown in FIG. 1. The saw-damage and impurities present on the raw silicon wafers are removed with a wet etching. Simultaneously with this process a defined surface texture is obtained. A phosphorous containing precursor is deposited that serves as the phosphorous source during the emitter diffusion in a horizontal passage furnace. A phosphorous glass layer is formed during diffusion. This layer is removed with wet etching prior to the deposition of a SiNx anti-reflection coating. Front- and back-side metallization is realized by screen printing and firing of metallization pastes. Finally, laser ablation electrically isolates the emitter and collector at the edge of the wafer.
The cell efficiency obtained with the process sequence described in
It is, therefore, an object of the present invention to provide an improved process sequence for the production of solar cells from raw crystalline p-type silicon wafer material.
In a first embodiment of the invention, a process is provided for producing solar cells from a silicon wafer, comprising the steps of:
In a second embodiment of the invention, a process for producing a solar cell from a silicon wafer, comprising the steps of:
Other objects, features, and advantages of one or more embodiments of the present invention will seem apparent from the following detailed description, and accompanying drawings, and the appended claims.
Embodiments of the present invention will now be disclosed, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, in which
The surface condition prior to SiNx deposition is improved by providing additional process steps following the phosphorous glass removal and prior to the SiNx anti-reflection coating deposition.
In the first embodiment, as shown in FIG. 2(a), the wafer is submitted to a thermal anneal under oxygen atmosphere followed by a wet-chemical oxide removal. The anneal reduces the surface phosphorous concentration by diffusion, reduces lattice defects in the emitter and oxidizes the silicon surface.
In the second embodiment, as shown in FIG. 2(b), both a surface oxide is obtained and subsequently removed with wet chemistry. This sequence allows for an integration of the phosphorous glass removal, the wet-channel oxidation, and the SiOx removal into a single machine.
A combination of the two sequences described above is also envisioned.
While the specific embodiments of the present invention have been described above, it will be appreciated that the invention may be practiced otherwise than described. The description is not intended to limit the invention.
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|Citing Patent||Filing date||Publication date||Applicant||Title|
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|US8927317||Jun 16, 2011||Jan 6, 2015||Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.||Method for producing a selective doping structure in a semiconductor substrate in order to produce a photovoltaic solar cell|
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|WO2012000612A2 *||Jun 16, 2011||Jan 5, 2012||Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e. V.||Method for producing a selective doping structure in a semiconductor substrate in order to produce a photovoltaic solar cell|
|WO2012000612A3 *||Jun 16, 2011||Dec 20, 2012||Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e. V.||Method for producing a selective doping structure in a semiconductor substrate in order to produce a photovoltaic solar cell|
|Cooperative Classification||Y02P70/521, Y02E10/547, H01L31/1804|