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
  • H10F10/00—Individual photovoltaic cells, e.g. solar cells
• • 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
• • 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
• • 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
  • H10F77/00—Constructional details of devices covered by this subclass
  • H10F77/30—Coatings
• • 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
  • H10F77/00—Constructional details of devices covered by this subclass
  • H10F77/30—Coatings
  • H10F77/306—Coatings for devices having potential barriers
  • H10F77/311—Coatings for devices having potential barriers for photovoltaic 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
  • 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 present invention relates to a method for producing a solar cell from a silicon substrate according to claim 1.
• Solar cells usually consist of a silicon substrate.
• solar cells are provided with a passivation layer.
• passivation layer To passivate silicon surfaces of solar cells, dielectric thin films have hitherto been used.
• silicon nitride films deposited primarily with a plasma process have become established.
• thermally grown silicon oxide layers offer significantly better passivation properties.
• the process requires a high thermal budget, which can adversely affect the diffusion profiles.
• Another disadvantage is that the process is inherently two-sided. However, since the passivation layer is typically required only on one side of the solar cell, the other side of the solar cell must be masked.
• the one-sidedness of the oxidation is achieved by front side masking with deposited SiN.
• a thin layer ( ⁇ 20 nm) of oxide is grown and then thickened by deposited oxide or nitride. Since the boundary layer between Si0 2 and Si is primarily relevant for the passivation, a passivation quality comparable to the purely thermal oxide is achieved by the layer stack.
• the disadvantage of this, however, is that the method is technically complex and expensive.
• the present invention relates to a method for producing a solar cell from a silicon substrate, which has a first main surface serving as a light incident side in use and a second main surface serving as a back side, with a passivation layer on the second main surface, comprising the following steps: Applying an oxide-containing layer to the second main surface of the silicon substrate; and heating the silicon substrate to a temperature of at least 800 ° C to densify the oxide-containing layer and to oxidize the interface between the oxide-containing layer and the second major surface of the substrate
• Silicon substrate for the formation of thermal oxide wherein an oxygen source releases oxygen for the oxidation.
• a process atmosphere of the silicon substrate in particular 0 2 and / or H 2 0 comprising, can act as an oxygen source.
• the oxide-containing layer can be applied such that it, in particular Si0 2 , Zr0 2 , SiO a N b and / or SiO a C b , wherein each b ⁇ a, comprising, is oxygen-permeable.
• the oxide-containing layer in particular comprising SiO 2
• SiH 4 can be applied to the second main surface of the silicon substrate by a CVD or a PECVD method, in particular using SiH 4 . This further reduces the cost of the process since the CVD and PECVD processes are very cost effective.
• the oxide-containing layer is applied uniformly to the second main surface.
• the oxide-containing layer may be a superstoichiometric oxide, in particular SiO 2 + x : H and / or a low-density oxide and / or a hygroscopic oxide Oxide, preferably BSG, PSG and / or TEOS oxide, and the oxide-containing layer may function as the oxygen source.
• a silicon oxide layer formed during heating of the silicon substrate therefrom may be etched away from the first main surface and a portion of the oxide-containing layer may be etched away from the second main surface.
• a dopant in particular boron, preferably by means of boron tribromide, and / or phosphorus, preferably by means of phosphorus oxychloride, can be further diffused into the two main surfaces after the application of the oxide-containing layer, wherein the dopant is diffused during the step of heating the silicon substrate the first major surface diffuses, and wherein the oxide-containing layer acts as a masking layer of the second major surface during heating.
• a doped layer can easily be formed on the first main surface of the silicon substrate, which can function as an emitter, while the dopant does not diffuse into the second main surface of the silicon substrate.
• Dopant-silicon compound layers formed during heating of the silicon substrate may be etched away from the first main surface and / or the second main surface.
• An advantage of this is that the silicon of the silicon substrate is exposed on the first major surface and the oxide-containing layer is exposed on the second major surface.
• a surface structure may be applied to the first main surface and / or the second main surface before the application of the oxide-containing layer.
• the second main surface can be planarized before the application of the oxide-containing layer.
• the application of the oxide-containing layer on the second main surface is significantly improved.
• the first main surface and / or the second main surface can be cleaned before the application of the oxide-containing layer, in particular with HNO 3 .
• An advantage of this is that the application of the oxide-containing layer is further improved.
• boron or phosphorus may also be diffused into the second major surface or implanted by ion implantation, which is activated upon heating of the silicon substrate, to create a back surface field (BSF) layer.
• BSF back surface field
• the back-surface field improves the efficiency of the solar cell because the back-surface field is a barrier to the electrons, which therefore does not gain access to the surface of the silicon substrate.
• a SiN anti-reflection layer may further be applied to the first main surface and / or the oxide-containing layer of the second main surface.
• the anti-reflection layer reflects less light from the silicon substrate, thereby providing more light into the substrate
• Silicon substrate penetrates. This increases the efficiency of the solar cell.
• one or more holes can be produced by means of a laser through the silicon substrate for connecting the first main surface to the second main surface, in particular by means of a laser, before the application of the oxide-containing layer.
• the advantage of this is that an electrical connection is formed from the first main surface to the second main surface or vice versa through the holes in a simple manner.
• a dopant in particular boron, preferably by means of boron tribromide, and / or phosphorus, preferably by means of phosphorus oxychloride, is diffused into both main surfaces; the dopant is diffused by heating the silicon substrate into the silicon substrate to form an emitter layer on the first major surface and an emitter layer on the second major surface; dopant-silicon compound layers formed by heating the silicon substrate are etched away from the first main surface and / or the second main surface; a masking layer, preferably SiN, is applied to the first major surface; and the emitter layer of the second main surface is removed, in particular by etching, wherein the SiN layer functions as a masking layer of the first main surface during the removal.
• a dopant in particular boron, preferably by means of boron tribromide, and / or phosphorus, preferably by means of phosphorus oxychloride, is diffused into both main surfaces; the dopant is diffused by heating the silicon substrate into
• Solar cell made of a silicon substrate with a passivation layer
• FIGS. 1 a to 1 d show a silicon substrate 1 in each case after steps of a method according to the invention for producing a solar cell from a silicon substrate with a passivation layer on the rear side of the silicon substrate
• FIG. La a silicon wafer or silicon substrate 1 is shown.
• the silicon substrate 1 is made of crystalline silicon 2 and has a first main surface 3, also called the front side, and a second main surface 4, also referred to as a back side, which is opposite the first main surface 3.
• FIG. 1b shows the silicon substrate 1 after the first method step.
• silicon dioxide is applied to the second main surface 4 of the silicon substrate 1 by a PECVD method.
• PECVD method instead of silicon dioxide, other oxide-containing layers are conceivable. Other methods for applying the layer are conceivable.
• the silicon substrate 1 is in a second process step to a
• the source of oxygen can be the
• the deposited oxide-containing layer 5 is permeable to oxygen, which is the case, for example, for SiO 2 and SiO a N b or SiO a C b , when b is much smaller than a.
• an oxide-containing layer are other oxygen-conducting metal oxides, such as. B. Zr0 2 .
• the oxygen source may also be the oxide-containing layer 5 itself.
• a superstoichiometric oxide is applied as the oxide-containing layer to the second main surface 4 of the silicon substrate 1.
• the superstoichiometric oxide releases water and / or oxygen during heating of the silicon substrate.
• the superstoichiometric oxide may be, for example
• Si0 2 + x H or a hygroscopic oxide such as BSG, PSG, or TEOS oxide.
• a low density oxide is useful to facilitate oxygen diffusion. This is typically the case in SiH 4 processes at low temperatures.
• An amorphous Si0 2 layer on the silicon substrate is produced by means of Si H 4 and an oxygen source by a PECVD method.
• an oxygen source for example, nitrous oxide or pure oxygen can act as an oxygen source for this purpose.
• the SiH 4 processes take place at temperatures between room temperature and about 500 ° C, preferably at a temperature around 200 ° C.
• Fig. Lc shows the silicon substrate 1 after heating.
• a silicon dioxide layer 6 has formed on the first main surface 3.
• a thermal oxide 6 has formed at the interface between the silicon 2 and the oxide-containing layer 5.
• a one-sided oxide, ie a solar cell with a passivation layer on only one side of the silicon 2 is now formed by etching the two main surfaces 3, 4. The etching removes the silicon dioxide layer on the first main surface 3 of the silicon substrate 1.
• On the second main surface 4 only part of the oxide-containing layer 5 is removed by the etching.
• FIGS. 2 a to 2 d show a silicon substrate 1 after successive steps of a further method according to the invention for producing a solar cell with a passivation layer on the rear side.
• a silicon-containing substrate 1 which comprises a wafer made of silicon 2
• phosphorus is diffused. This forms PSG 7,
• Phosphorus silicate glass on the first main surface 3 of the silicon substrate 1 and on the silicon dioxide 5 on the second main surface 4.
• the diffused phosphorus is driven by heating the silicon substrate 1 in the silicon 2 of the silicon substrate 1, to form an emitter. 8 on the first main surface 3 of the silicon substrate 1.
• a thermal oxide layer 6 is formed at the interface between the silicon 2 and the silicon dioxide 5 deposited on the second main surface 4 of the silicon substrate 1. The state of the layer sequence after this process step is shown in Fig. 2b.
• the PSG 7 is removed from the two main surfaces 3, 4.
• Fig. 2c the result after the etching of the two main surfaces 3, 4 is shown.
• the silicon 2 is now exposed, which comprises a thin layer 8 doped with phosphorus.
• Fig. 2c the state of the silicon substrate 1 is shown after this process step.
• a SiN antireflection layer 9 is then applied to the first main surface 3 of the silicon substrate 1.
• Fig. 2d the silicon substrate 1 is shown after completion of the process.
• the silicon substrate 1 has only on the back of a passivation layer comprising a thermal oxide 6.
• FIGS. 3 a to 3d show a silicon substrate 1 after successive steps of a further method according to the invention for producing a solar cell with a passivation layer on one side of the silicon substrate 1.
• a boron layer 10 is introduced as a back-surface field into the second main surface 4 of the silicon substrate 1, for example by diffusion.
• the silicon substrate 1 after this first step is shown in FIG. 3a.
• a silicon dioxide layer 5 is applied to the second main surface 4 of the silicon substrate 1.
• the sequence of layers after this step is shown in FIG. 3b.
• phosphorus is diffused to form an emitter 8.
• PSG 7 is formed on the first main surface 3 and on the silicon dioxide 5 on the second main surface 4.
• a thermal heat is generated at the interface between the silicon 2 and the silicon dioxide 5 deposited on the second main surface 4 Oxide layer 6.
• the thermal step of heating the silicon substrate 1 also activates the boron of the boron layer 10, and damages from the implantation steps are healed.
• the silicon substrate 1 after this process step is shown in FIG. 3c.
• a SiN antireflection layer 9 is then applied to the first main surface 3 of the silicon substrate 1.
• Step 7) of the previously known Sinto process i. Standard Cleaning 1 / Standard Cleaning 2-step, which is expensive and time-consuming to remove metal contamination, is omitted or can be omitted.
• the PERC cell produced by this process can be expanded to a PERT cell using a boron implant.
• the POCI 3 / BBr 3 diffusion additionally fulfills the function of activation of the implanted dose, so that a total of two high-temperature steps can be saved.
• New PERC process according to the present invention: 1) texture (+ backside planarization)
• this process can be combined with a MWT (metal wrap through) process flow.
• the proposed process flows are also applicable without restriction to a cell process flow with selective front diffusion.
• the quality of the backside passivation can be further improved by a long drive-in step of the front diffusion.

Landscapes

• Photovoltaic Devices (AREA)
• Formation Of Insulating Films (AREA)
• Weting (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=44625123

Family Applications (1)

Country Status (7)

Families Citing this family (16)

Family Cites Families (4)

• 2010
  • 2010-04-09 DE DE102010003784A patent/DE102010003784A1/de not_active Withdrawn
• 2011
  • 2011-02-16 JP JP2013503046A patent/JP5656095B2/ja not_active Expired - Fee Related
  • 2011-02-16 EP EP11703234A patent/EP2556545A2/de not_active Withdrawn
  • 2011-02-16 CN CN201180017924.7A patent/CN102822988B/zh not_active Expired - Fee Related
  • 2011-02-16 KR KR1020127029330A patent/KR20130050301A/ko not_active Withdrawn
  • 2011-02-16 US US13/640,165 patent/US20130089942A1/en not_active Abandoned
  • 2011-02-16 WO PCT/EP2011/052257 patent/WO2011124409A2/de not_active Ceased

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events