Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F71/00—Manufacture or treatment of devices covered by this subclass
  • H10F71/121—The active layers comprising only Group IV materials
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
  • B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
  • B23K26/062—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam
  • B23K26/0622—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam by shaping pulses
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/36—Removing material
  • B23K26/362—Laser etching
  • B23K26/364—Laser etching for making a groove or trench, e.g. for scribing a break initiation groove
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/36—Removing material
  • B23K26/40—Removing material taking account of the properties of the material involved
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K2103/00—Materials to be soldered, welded or cut
  • B23K2103/50—Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/50—Photovoltaic [PV] energy
  • Y02E10/547—Monocrystalline silicon PV cells
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
  • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

• the invention relates to a method for separating silicon solar cells.
• silicon solar cells In the production of silicon solar cells, a large number of individual silicon solar cells are usually produced in a silicon wafer, which must be separated in a final manufacturing step, ie, separated from one another. In the prior art, this is done either with a mechanical sawing method or with a known example from WO 2008/084206 Al laser cutting method. If these methods are carried out in one stage, ie if a separation takes place in a single process step, then it may happen that the individual silicon solar cells are short-circuited, in particular during laser cutting. The reason for this is that a fusion zone is created in the kerf, which can be enriched with doping elements.
• the invention is therefore based on the object to provide a method for separating silicon solar cells, with which the above-mentioned disadvantages are avoided.
• This object is achieved according to the invention with a method having the features of claim 1.
• a method having the features of claim 1.
• a first step in a silicon solar cell containing silicon wafer with a first laser beam along a separation line in a pn junction in the silicon wafer adjacent
• a groove is introduced which has a depth reaching at least to the pn junction and extends to a lateral edge of the silicon wafer.
• the silicon wafer is placed on the groove directed second laser beam cut along the dividing line, wherein the melting material formed during cutting is expelled with a cutting gas flowing at least approximately in the direction of the second laser beam from the cutting groove formed during cutting.
• the groove extends at least as far as a depth of the silicon wafer in which the pn junction is located, at least laser melting in the melting zone results in a melt containing p-dopant. Since this is expelled towards the back of the silicon wafer, this can not attach to the n-doped side wall of the groove. As a result, a short-circuiting of the silicon solar cell arising at the edge can be avoided.
• first and second laser beams are pulsed, wherein the pulse duration of the first laser beam is shorter than the pulse duration of the second laser beam.
• First and second laser beam can be generated by two different lasers as well as by a laser, which can work in correspondingly different modes.
• FIG. 1 shows a silicon wafer containing a plurality of silicon solar cells in a schematic plan view onto one of its flat sides
• FIGS. 2, 4 and 6 each show a silicon wafer containing silicon solar cells at one of its edges in a longitudinal section along a dividing line during the execution of the first working step, at the beginning of the second working step or during the execution of the second working step,
• Fig. 3, 5 and 7 to the Figs. 1, 3 and 5 respectively corresponding step in a plan view in the direction of the dividing line on a narrow side of the silicon wafer.
• a silicon wafer 2 a plurality of fully processed silicon solar cells 4 are arranged, which in a subsequent, subsequently explained production step are separated from one another at predetermined separation lines 5, i. to be isolated.
• the silicon wafer 2 is constructed from a p-doped silicon substrate 6 serving as a base, which is provided on a rear side 8 with a metallic base contact 10.
• an n-doped emitter layer 12 has been produced by adding an n-type dopant on the front side 8 opposite the rear side 8, which is only a few microns thick, so that in a depth of only a few microns T is a dashed line pn junction 16 is located.
• the front side 14 of the silicon wafer 2 is also provided with an antireflection coating 18 and with a plurality of emitter contacts 20.
• a groove 22 is introduced in a first step with a first laser beam L 1 along one of the parting lines 5 by a laser ablation or laser ablation process into the front side 14 of the silicon wafer 2 adjacent to the pn junction 16 (incised) ) whose depth t extends at least to the depth T of the pn junction 16, which is typically about 1 ⁇ m.
• the ablation begins at a lateral edge 24 of the silicon wafer 2. In principle, however, the ablation can also begin at a point spaced from the edge of the silicon wafer 2. It is essential, however, that the finished groove 22 extends to the lateral edges 24 of the silicon wafer 2.
• the first laser beam L1 is pulsed, wherein the pulse durations are preferably in the nanosecond range and wavelengths in the range between 200 nm and 2000 nm are used. In principle, shorter pulse durations are also suitable, which are below the nanosecond range.
• the depth t of the groove 22 in this case preferably exceeds the depth t of the pn junction by several micrometers, for example by more than 10 ⁇ m. In practice, a depth of the groove 22 of about 12- 15 microns has been found to be suitable
• the substrate 2 is cut in a second step with a directed into the groove 22 second, preferably also pulsed laser beam L2 beginning at the lateral edge 24 along the dividing line 5 as shown in FIG.
• the meltable material M produced during the laser cutting process is blown with a cutting gas G flowing at high speed approximately in the direction of the second laser beam L2 from a cutting joint 28 formed at the beginning of the laser cutting and not yet reaching the rear side 8 laterally at the edge 24, i. with one in the direction of the second laser beam L2 oriented, directed towards the rear side flow component expelled. In this way it is prevented that during melting of the
• the p-doped region of the silicon substrate 6 forms a p-dopant enriched melt zone, which propagates to the n-doped side wall of the groove 22 and wets them.
• the melted material M enriched with p-type dopants does not come into contact with the n-doped emitter layer 12.
• the pulse durations of the second laser beam L2 are typically in the microsecond range, wherein the wavelength of the second laser beam L2 is preferably in the near infrared range.
• Feed the laser beam L2 in the direction of the dividing line 5 spreading separating gap is formed, from which the melt M to the back 8 can be expelled. In this way, the pn junction on the side walls of the separation gap is maintained.

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• Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Engineering & Computer Science (AREA)
• Plasma & Fusion (AREA)
• Mechanical Engineering (AREA)
• Photovoltaic Devices (AREA)
• Laser Beam Processing (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Related Child Applications (1)

Publications (1)

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Family Applications (1)

Country Status (5)

Cited By (4)

Families Citing this family (12)

Citations (2)

Family Cites Families (11)

• 2009
  • 2009-05-20 DE DE102009026410A patent/DE102009026410A1/de not_active Withdrawn
• 2010
  • 2010-05-17 WO PCT/EP2010/056708 patent/WO2010133536A1/de not_active Ceased
  • 2010-05-17 JP JP2012511246A patent/JP5462936B2/ja active Active
  • 2010-05-17 EP EP10719944A patent/EP2291867B1/de not_active Not-in-force
• 2011
  • 2011-02-04 US US13/020,972 patent/US20110124147A1/en not_active Abandoned

Patent Citations (2)

Non-Patent Citations (1)

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