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A method for forming a selective contact

A selective, contact technology, applied in the direction of photovoltaic power generation, laser welding equipment, electrical components, etc., can solve the problems of increasing complexity and laser system cost, technical complexity, and low throughput

Inactive Publication Date: 2012-12-26
艾思科集团公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] Obviously, a first disadvantage of the above technique is the fact that multiple laser beams need to simultaneously irradiate portions of the emitter layer corresponding to the finger electrodes, while the technique is complex and not cost effective
[0008] The second disadvantage is that the throughput of such systems is very low because the laser beam is continuously scanned along the full extension of the finger electrodes
[0009] A third disadvantage is the limited flexibility with regard to the shape and size of the part of the emitter layer to be illuminated
Since the diameter of conventional laser beams is smaller or of the same order as the width of conventional finger electrode columns, without (i) increasing the number of laser beams of a set of laser beams passing through the mask aperture, this would increase the complexity and cost of the laser optics system, or not (ii) repeat the annealing process multiple times along the direction of extension of the finger electrodes, which would lead to overlapping effects, lower throughput, and higher photovoltaic manufacturing costs , the width cannot increase appreciably

Method used

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Experimental program
Comparison scheme
Effect test

no. 1 approach

[0024] According to a first embodiment of the present invention, there is provided a method of forming a selective contact for a photovoltaic cell, the method comprising:

[0025] a. forming a doped contact layer on the surface of a semiconductor substrate;

[0026] b. using a laser beam to anneal a portion of the doped contact layer having a 2D pattern corresponding to at least a portion of a corresponding selective contact grid;

[0027] It is characterized in that the laser beam is pulsed and shaped according to the 2D pattern.

[0028] By using laser beams that are pulsed and shaped according to the 2D pattern corresponding to at least one portion of the corresponding selective contact grid, it is no longer necessary to use multiple laser beams to achieve simultaneous irradiation of doped Multiple parts of the contact layer. Obviously, this reduces complexity and laser equipment cost.

[0029] Another advantage of the present invention is that since a significant portio...

example 1

[0066] Conventional emitter contact formation process:

[0067] 1) POCl3 high-temperature furnace diffusion of bulk silicon to form a heavily doped n-type emitter layer

[0068] 2) Phosphosilicate glass etching

[0069] 3) SiNx arc / passivation layer deposition

[0070] 4) Align front side metallization by screen printing

[0071] The selective emitter formation process in the prior art is described as an example in WO 2009 / 128679:

[0072] 1) POCl3 low-temperature furnace diffusion of bulk silicon to form a lightly doped n-type emitter layer

[0073] 2) Selective laser annealing of the emitter layer

[0074] 3) Phosphosilicate glass etching

[0075] 4) SiNx arc / passivation layer deposition

[0076] 5) Align front side metallization by screen printing

[0077] The process of forming a selective emitter according to the present invention:

[0078] 1) POCl3 low-temperature furnace diffusion of bulk silicon to form a lightly doped n-type emitter layer

[0079] 2) Selectiv...

example 2

[0101] Described below is a conventional interdigitated back contact (IBC) solar cell fabrication process with 6 photolithographic steps and a final sintering and annealing step (as in Tom Markvart and Luis Castaner in Elsevier Photovoltaic, Fundamental Principles and application as described in the practical manual):

[0102] 1) FZ wafer with long oxidation life at the beginning

[0103] 2) N+ emitter lithography

[0104] 3) Oxide etching opens the N+ emitter region

[0105] 4) Phosphorus pre-deposition

[0106] 5) P+ emitter lithography

[0107] 6) Oxide etching opens the P+ emitter region

[0108] 7) Boron pre-deposition

[0109] 8) Make the back with a wafer structure (solar cell front side)

[0110] 9) Grow fine oxide or dielectric

[0111] 10) Contact photolithography

[0112] 11) Oxide or dielectric etch to open the contact area

[0113] 12) Level 1 Metallization

[0114] 13) Metal 1 photolithography

[0115] 14) Metal 1 etching

[0116] 15) Precipitation o...

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Abstract

The present invention is directed to a method for forming a selective contact for a photovoltaic cell comprising: a. forming a doped contact layer at the surface of a semiconductor substrate; b. annealing a portion of the doped contact layer with a laser beam, said portion having a 2D-pattern corresponding to at least a portion of a respective selective contact grid; characterized in that the laser beam is pulsed and shaped to the 2D-pattern. In addition, the present invention is also directed to a photovoltaic cell comprising a selective contact formed by that method.

Description

technical field [0001] The present invention relates to a method of forming selective contacts for photovoltaic cells using laser annealing. [0002] In addition, the invention also relates to a photovoltaic cell comprising a selective contact formed according to the method. Background of the invention [0003] In conventional photovoltaic cell fabrication, the formation of the emitter contact consists of three main steps, namely the formation of the emitter layer, which is a highly doped layer located in front of the bulk silicon substrate, the The bulk silicon substrate has a different dopant type than the bulk silicon substrate; an anti-reflective coating (ARC) is formed on the emitter layer; and alignment metallization. [0004] As is known to those of ordinary skill in the art, photovoltaic cell manufacturers seeking higher cell performance have invented so-called selective emitter technology. Selective emitter contacts consist of a given type of emitter layer that ex...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01L31/0224H01L31/18
CPCB23K26/063H01L33/58B23K26/0656H01L31/068H01L31/022425B23K26/067H01L31/028Y02E10/50H01L33/0095B23K26/073Y02E10/547B23K26/0622B23K26/066H01L31/04H01L31/0224H01L31/18
Inventor 蒂埃里·埃默罗
Owner 艾思科集团公司