EP2368275A2 - Procédé de dépôt de silicium microcristallin sur un substrat - Google Patents

Procédé de dépôt de silicium microcristallin sur un substrat

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Publication number
EP2368275A2
EP2368275A2 EP09801654A EP09801654A EP2368275A2 EP 2368275 A2 EP2368275 A2 EP 2368275A2 EP 09801654 A EP09801654 A EP 09801654A EP 09801654 A EP09801654 A EP 09801654A EP 2368275 A2 EP2368275 A2 EP 2368275A2
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EP
European Patent Office
Prior art keywords
plasma
layer
chamber
silicon
microcrystalline
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Application number
EP09801654A
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German (de)
English (en)
Inventor
Aad Gordijn
Thilo Kilper
Bernd Rech
Sandra Schicho
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Forschungszentrum Juelich GmbH
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Forschungszentrum Juelich GmbH
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Publication of EP2368275A2 publication Critical patent/EP2368275A2/fr
Withdrawn legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
    • C23C16/24—Deposition of silicon only
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
    • C23C16/50—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges
    • C23C16/505—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges using radio frequency discharges
    • C23C16/509—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges using radio frequency discharges using internal electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers
    • H01L31/075—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers the potential barriers being only of the PIN type, e.g. amorphous silicon PIN solar cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers
    • H01L31/075—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers the potential barriers being only of the PIN type, e.g. amorphous silicon PIN solar cells
    • H01L31/076—Multiple junction or tandem solar cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/1804—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof comprising only elements of Group IV of the Periodic Table
    • H01L31/182—Special manufacturing methods for polycrystalline Si, e.g. Si ribbon, poly Si ingots, thin films of polycrystalline Si
    • H01L31/1824—Special manufacturing methods for microcrystalline Si, uc-Si
    • 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
    • Y02E10/545—Microcrystalline 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
    • 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
    • Y02E10/548—Amorphous 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 depositing microcrystalline silicon on a substrate.
  • Microcrystalline silicon ( ⁇ c-Si. ⁇ ) is a material that is used in particular in solar cells as an absorber material. Today, it is produced in many laboratories by means of the PECVD process (plasma-enhanced chemical vapor deposition) from silicon-containing gas (typically silane) and hydrogen.
  • PECVD process plasma-enhanced chemical vapor deposition
  • silicon-containing gas typically silane
  • hydrogen typically hydrogen
  • High quality layers of microcrystalline silicon can be deposited in different deposition regimes.
  • the PECVD PECVD
  • the silane / hydrogen mixture is admitted into the plasma chamber and a corresponding amount of gas is pumped while simultaneously burning in the plasma chamber, a plasma which causes the dissociation of silane and hydrogen molecules and thus the generation of precursors for the growing microcrystalline silicon layer ,
  • the hydrogen is needed to influence the layer growth. However, only a small portion of the hydrogen used is incorporated into the produced silicon layer, typically less than 10%. The remaining hydrogen is pumped out.
  • the closed-chamber CVD process (CC-CVD).
  • This investigated process runs cyclically (discontinuously) and essentially comprises two process steps.
  • a small amount of the reactive process gas (silicon-containing gas, z. SiH 4 or a ClVSi ⁇ U mixture) in a ratio of about 25% reactive gas to hydrogen through the chamber.
  • This step serves to refresh the gas atmosphere after a process cycle.
  • the plasma burns at low power (about 10 W), so that an ultra-thin silicon layer is deposited.
  • both the pumping power from the chamber and the gas supply into the chamber are interrupted. By delaying the shutdown of the hydrogen supply, the deposition pressure is increased and the silane concentration is lowered to ⁇ 5%.
  • the plasma now burns at about 60 W.
  • the process gases are gradually decomposed and the deposited layer continues to grow.
  • the layer is etched by H radicals.
  • the etch rate continues to increase due to the increasing proportion of hydrogen in the plasma, until finally a balance between layer growth and etching is achieved.
  • Atoms that are weakly bound are preferentially etched, eventually forming a network with stronger bonds.
  • the entire deposition process takes place as a continuous sequence of these two steps (layer by layer) to the desired layer thickness. It is reported by a crystalline volume fraction of more than 90%. Due to the cyclic change of the process conditions, this process is very expensive. It differs fundamentally from the standard PECVD method, and is not yet suitable for use in industry. So far no solar cell has been realized with this method.
  • VHFGD Static closed chamber procedure
  • VHFGD very high frequency glow dis- charge deposition process
  • the deposition chamber plasma chamber
  • a small silane flow is admitted into the chamber and an appropriate amount of gas is simultaneously pumped out.
  • Deposition takes place at VHF excitation and at low pressure (0.1 mbar).
  • the low silane gas flow ensures that silane depletion occurs.
  • the initial rapid deposition of silicon is due to the increase in dissociated! Hydrogen braked. After about one minute, static conditions with a small ratio of [SiH *] / [H ⁇ ] prevail, allowing for continuous microcrystalline growth.
  • the deposition Since the deposition is started with a pure silane plasma and only added later by the decomposition of the silane hydrogen, the deposited layer has a pronounced amorphous incubation layer ( ⁇ 0.1 nm) as a first layer. This may be the case with the use of such layers in components, in particular in solar cells cause a significant impairment of the function. Thus, in solar cells whose absorber layer was produced by this method, only an efficiency of 2.5% could be achieved.
  • DE 103 08 381 A1 discloses a method for depositing microcrystalline silicon for the absorber layer, which likewise has low hydrogen consumption. For this purpose, a lot of hydrogen is started, and after the plasma start the hydrogen supply is radically reduced. In contrast to methods 1 and 2, however, it is possible with this method to achieve significantly higher solar cell efficiencies of up to 7%.
  • the quantities produced per unit time are an important criterion.
  • the thickness of the solar cell is a criterion.
  • a layer thickness of> 1 ⁇ m has become established as the optimized solar cell for the ⁇ c-Si: H absorber layer.
  • This provides single solar cells with an efficiency greater than or equal to 8% when using a ZnO / Ag back contact.
  • a back contact the side facing away from the light is called.
  • a front contact the light-facing side is called.
  • the object of the invention is to provide a rapid method for the deposition of microcrystalline silicon on a substrate, which nevertheless leads to high efficiencies of the solar cells.
  • the method for depositing microcrystalline silicon on a substrate in a plasma chamber system comprises the steps of:
  • the plasma chamber system Before the start of the plasma, the plasma chamber system has a reactive, silicon-containing gas and hydrogen or exclusively hydrogen, the plasma is started, the chamber system is continuously fed exclusively reactive, silicon-containing gas after the plasma start or the chamber system is after the plasma continuously adding a mixture comprising a reactive silicon-containing gas and hydrogen, wherein the concentration of reactive, silicon-containing gas is set greater than 0.5% upon delivery to the chamber, and
  • the plasma power is set between 0.1 and 2.5 W / cm 2 electrode surface, and a deposition rate of greater than 0.5 nm / s is selected and a microcrystalline layer is deposited on the substrate, which has a thickness of 1000 nm does not exceed.
  • the reason for this is that optimum ⁇ c-Si: H absorber layer properties are not achieved by a high crystalline content, but that materials in the transition region with amorphous and crystalline fractions show the best properties.
  • the cause of these favorable properties is considered to be an optimal interfacial passivation of the silicon crystallites by amorphous silicon.
  • the process gases silicon-containing gas and hydrogen
  • the plasma start inert gases such as argon
  • the method according to the invention advantageously has the features which are particularly advantageous for mass production of solar cells on an industrial scale.
  • This is the deposition of a comparatively thin ⁇ c-Si: H absorber layer with simultaneously high deposition rate. It is irrelevant whether the microcrystalline absorber layer is deposited for a single cell or for a stacked solar cell. Only the measure of increasing the deposition rate in thin microcrystalline absorber layers solves the object of the invention, regardless of the substrate selected and the associated structure of the solar cell.
  • plasma chamber system includes all common plasma chambers for the deposition of solar cells.
  • the method can therefore basically be used for single chambers as well as for combined plasma chamber systems of several single chambers.
  • the plasma chamber system can, for example, be a single chamber for the production of intrinsic a-Si: H and ⁇ c-Si: H absorber layers (i-chamber), a further single chamber for the production of p- or n-doped a-Si: H and ⁇ c Si: H layers (doping chamber) and a loading chamber for the insertion and removal of substrates include.
  • H absorber layers having a layer thickness of less than 1000 nm no appreciable loss of efficiency due to a deposition rate increase takes place any more. All combinations of intermediate values for the deposition rate and the layer thickness are allowed.
  • a deposition rate increase for example from 1 to 2.5 nm / s, leads to a significant loss of efficiency.
  • the deposition rate can be selected up to 5 nm / s depending on the plasma power or generator power.
  • a boron-containing (for example trimethylboron B (CH 3 ) 3 ) or phosphorus-containing gas (for example phosphine PH 3 ) can additionally be mixed with the process gas mixture comprising silicon-containing gas and H 2 .
  • the i-chamber and the doping chamber are preferably separated from one another via a lock gate.
  • the i-chamber may include one or more different high-frequency electrodes, which may have a "showerhead" design for homogeneous gas injection, and whose electrode surface may be vertically or horizontally aligned.
  • the substrate to be coated may be moved to the electrode by means of a transport system Once the substrate has reached its final position, a heater system ensures that the substrate is heated to the desired substrate temperature before deposition begins, for example, the distance between the radio frequency electrode and the substrate can be set between 5 and 25 mm ,
  • deposition rate is defined as the thickness of the deposited absorber layer per unit time.
  • the deposition rate increases in principle with the increase in plasma power or generator power.
  • a plasma excitation frequency of 13.56 to about 100 MHz with an electrode spacing of 5 to 25 millimeters, preferably 10 to 25 millimeters can be selected.
  • the deposition pressure in the plasma chamber is preferably set between 1 and 25 mbar in the plasma chamber or in the plasma chambers.
  • An increase in the deposition pressure leads, with otherwise constant process parameters, to a lower crystalline volume fraction of the growing layer.
  • the method may be conducted, so in a further, particularly advantageous embodiment of the invention is that the base pressure "is 6 mbar or even more, that is to say z. B. 10 '5 mbar or z. B. 10" in the plasma chamber system at least 10 4 mbar. All Intermediate values are possible.
  • the base pressure is the prevailing pressure in the plasma chamber or in the plasma chamber system in the evacuated state prior to the introduction of the process gases and depends inter alia on the design of the chamber and the purity of the gases used.
  • the plasma chamber or the plasma chamber system of a small laboratory plant has a base pressure of about 10 -8 mbar, which is due to the high levels of purity under which the prior art processes must be operated in order to achieve the desired high levels
  • the realization has become established that the oxygen content in ⁇ c-Si: H absorber layers should not exceed a certain limit, otherwise the achievable efficiency of both ⁇ c-Si: H based single solar cells and a-Si H / ⁇ c-Si: H-based stacked solar cells experienced significant and undesirable losses in efficiency
  • the oxygen content in the ⁇ c-Si: H absorber layer always remained below an allowable limit to achieve high cell efficiencies, this limit
  • the ⁇ c-Si: H absorber layer contains about 2 ⁇ 10 19 / cm 3 oxygen atoms and standard layer thicknesses of> 1000 nm for the ⁇ c-Si: H absorber layer. This was associated with high plant costs
  • the achievable cell efficiency possibly slightly decreases, but this disadvantage in addition to the shorter production time due to the layer thickness reduction and possibly lower claims on the purity of the process (the gases) and the cells produced in relation to the Oxygen content is overcompensated, and that in this case, the solar cell production time due to an increase in the deposition rate of the ⁇ c-Si: H absorber layer can be significantly reduced again without additional loss of efficiency.
  • the production can thus be carried out with significantly lower requirements for the process purity, which brings significant cost advantages, namely lower system costs and lower process gas costs.
  • thinner a-Si: H / ⁇ c-Si: H based stacked solar cells degrade less.
  • the difference in the stabilized efficiency against a-Si: H / ⁇ c-Si: H based stacked solar cells having the standard total layer thickness becomes smaller than that at the initial efficiency.
  • the method can be carried out in a further embodiment of the invention so as to regulate the flows of the gases supplied to the chamber and derived from the chamber or gas mixtures such that forms a constant deposition pressure during the process.
  • a deposition rate between about 1.0 to 2.5 nm / s can be selected and a microcrystalline layer with a thickness of 200 to 800 nm, in particular from 400 to 600 nm, can be deposited.
  • ⁇ c-Si H single solar cells with an efficiency of about 7-8% can also be regularly realized with the mentioned method for all combinations of intermediate values.
  • the chamber can be fed continuously only with reactive, silicon-containing gas in a volume flow of 0.5 sccm to 20 sccm / 100 cm 2 coating area, in particular from 0.5 sccm to 10 sccm / 100 cm 2 coating area , This applies z.
  • the chamber or the chamber system before starting the plasma start has hydrogen without silicon-containing gas.
  • the gas mixture present in the chamber can be at least partially diverted from the chamber. Inert gases may be added to this process.
  • the method for depositing the microcrystalline silicon can be used in particular for the production of stacked solar cells.
  • the solar cell in the case of a tandem configuration has a nipnip configuration in its finished state.
  • As a metal ZnO layer or a metal-Sn ⁇ 2 layer or another TCO layer can be selected.
  • Single cells are manufactured without the corresponding a-Si: H content.
  • a glass-TCO-a-Si. ⁇ -layer system plus a microcrystalline p-layer deposited thereon can also be selected as the substrate, for example. It is also possible to choose a metal-TCO-a-Si. ⁇ -layer system plus a microcrystalline p-layer deposited thereon.
  • the solar cell has a pin-pin configuration in its finished state in these cases. For single cells, substrates without the corresponding a-Si: H content are selected. Of course, other substrates for the production of Stacked solar cells are used.
  • the solar cells produced by this method thus have at least one n-i-p structure or one p-i-n structure, wherein the absorber layer is microcrystalline.
  • ⁇ c-Si: H single solar cells which are produced with this inventive method at a particularly advantageous deposition rate of 2.5 nm / s, an efficiency of about 7-8%. They are characterized in that the ⁇ c-Si: H absorber layer has a thickness of less than 1000 nanometers.
  • Single solar cells have an efficiency of 7-8% despite high deposition rates and low layer thicknesses. In stacked solar cells correspondingly higher efficiencies can be achieved.
  • the solar cells produced by this method can have more than 2 * 10 19 to about 1 * 10 21 cm "3 oxygen atoms in the microcrystalline absorber layer.
  • An a-Si: H / ⁇ c-Si: H-based stacked solar cell particularly advantageously has a total layer thickness of all absorber layers of less than 1000 nanometers.
  • the microcrystalline absorber layer preferably has an oxygen content of more than 2 ⁇ 10 19, in particular up to 10 21 oxygen atoms / cm 3, preferably with respect to the production costs per watt of peak solar module nominal power.
  • the substrate used was a glass TCO layer system (TCO), plus a microcrystalline p layer deposited thereon.
  • TCO glass TCO layer system
  • the glass has a thickness of about 1 millimeter
  • the TCO layer has a thickness of about 500 nanometers
  • the p-layer has a thickness of about 10 nanometers.
  • a plasma chamber system was selected in which the doped p- and n-layer and the undoped absorber layer were deposited in different chambers.
  • the named substrate is first positioned parallel to the showerhead high-frequency electrode with an electrode spacing of 10 mm and heated in vacuo to a substrate temperature of 200 ° C.
  • the base pressure is in this case 10 "7 mbar.
  • the plasma chamber can be coated up to a size of 30x30 cm 2 in the substrates, continuously with a hydrogen flow rate of 4000 sccm (corresponding 444.4 sccm per 100 cm 2 to be coated substrate surface) and a silane flux of 57 sscm at 1 nm / s deposition rate (this corresponds to 6.3 sccm per 100 cm 2 of substrate surface to be coated) and 102 sccm of silane flow at 2.5 nm / s deposition rate (this corresponds to 11.3 sccm each 100 cm 2 of substrate surface to be coated) flooded while the plasma chamber pressure continuously during the entire deposition process to 9.3 mbar regulated.
  • a hydrogen flow rate 4000 sccm (corresponding 444.4 sccm per 100 cm 2 to be coated substrate surface) and a silane flux of 57 sscm at 1 nm / s deposition rate (this corresponds to 6.3 sccm per 100 cm 2 of substrate surface to
  • the gas mixture present in the chamber is completely discharged from the chamber. In this case, a constant deposition pressure is formed.
  • a plasma is ignited between the substrate and the showerhead RF electrode and then regulated to a specific generator power.
  • the plasma excitation frequency is 40.68 MHz.
  • the generator power must be set to a value of 800 W (corresponds to 0.6 W / cm 2 electrode area).
  • a generator power of 1800 W (corresponding to 1.3 W / cm 2 electrode area) must be set.
  • ⁇ c-Si H absorber layer deposition
  • all specified process parameters remain unchanged.
  • the deposition time required results from the desired ⁇ c-Si: H absorber layer thickness and the ⁇ c-Si: H deposition rate associated with the respective production process.
  • the ⁇ c-Si: H absorber layer deposition ends when the generator is switched off after the set deposition time has elapsed.
  • the ⁇ c-Si: H absorber layer is deposited close to the ⁇ c-Si: H / a-Si: H transition and therefore optimized with respect to the layer properties.
  • ⁇ c-Si: H absorber layer produced by this process, an n-doped layer was deposited to produce a ⁇ c-Si: H single solar cell. This has a thickness of about 20 nanometers.
  • the back contact was made of ZnO / Ag (80 nanometers ZnO and 700 nanometers Ag).
  • the cell efficiency of this single cell reached the following values:
  • Second exemplary embodiment Production of a ⁇ c-Si: H absorber layer on a substrate at additionally high base pressure
  • the substrate used was a glass TCO layer system (TCO), plus a microcrystalline p layer deposited thereon.
  • TCO glass TCO layer system
  • the glass has a thickness of about 1 millimeter
  • the TCO layer has a thickness of about 500 nanometers
  • the p-layer has a thickness of about 10 nanometers.
  • a plasma chamber system was chosen in which the doped p- and n-layer and the undoped absorber layer were deposited in different chambers.
  • the plasma chamber In the evacuated state, the plasma chamber has a base pressure of approximately 10 -8 mbar
  • a base pressure of approximately 10 -8 mbar
  • an artificial air leak is attached to the chamber, the strength of which is controlled by a needle valve can be adjusted.
  • the base pressure in the plasma chamber also increases. The base pressure acts as a measure of the strength of the air leak and thus the built-in amount of oxygen.
  • the substrate is first positioned parallel to the showerhead RF electrode with an electrode spacing of 10 mm and heated in vacuum to a substrate temperature of 200 ° C. Thereafter, the plasma chamber, in which substrates can be coated to a size of 10x10 cm 2 , is continuously flooded with a hydrogen flux of 360 sccm and a silane flow of 5.0 sccm (about 1.4% silane concentration) and the plasma chamber pressure at 13 , 3 mbar regulated.
  • the gas mixture present in the chamber is completely discharged from the chamber. In turn, a constant deposition pressure is formed.
  • the process gases are admitted through the showerhead high-frequency electrode into the process chamber.
  • a plasma is ignited between the substrate and the showerhead RF electrode and then regulated to a generator power of about 60 W (corresponding to about 0.4 W / cm 2 electrode area), so that a ⁇ c-Si: H deposition rate of 0.7 nm / s is achieved.
  • the plasma excitation frequency is 13.56 MHz.
  • ⁇ c-Si H absorber layer deposition
  • all specified process parameters remain unchanged.
  • the required deposition time results from the desired ⁇ c-Si: H absorber layer thickness and the ⁇ c-Si: H deposition rate associated with the manufacturing process.
  • the deposition of the ⁇ c-Si: H absorber layer ends when the generator is switched off after the set deposition time has elapsed.
  • the ⁇ c-Si: H absorber layer is deposited close to the ⁇ c-Si: H / a-Si: H transition and therefore optimized with respect to the layer properties.
  • ⁇ c-Si. ⁇ absorber layer On the ⁇ c-Si. ⁇ absorber layer produced by this process, an n-doped layer was deposited to produce a ⁇ c-Si: H single solar cell. This has a thickness of about 20 nanometers. The back contact was made of Ag (700 nanometers). Depending on the base pressure set in the plasma chamber via the needle valve and the ⁇ c-Si: H absorber layer thickness, the cell efficiency reached the following values:
  • Example 3 compared to Example 1 and Example 2 has a good 100 nanometers lower absorber layer thickness, which at this absorber layer thickness level is responsible for the loss of efficiency of 1, 6%.
  • Example 3 in Table 2 has, with a comparable to the first embodiment, a thick absorber layer of 530 nanometers and with a back contact made of ZnO / Ag corresponding to an efficiency of about 7%.
  • a-Si: H amorphous
  • ⁇ c-Si: H microcrystalline
  • the total thickness of the active layers is essentially influenced by the thickness of the ⁇ c-Si: H absorber layers.
  • An example of a-Si: H / ⁇ c-Si: H-based stacked solar cells are a-Si: H / ⁇ c-Si: H tandem solar cells, which consist of exactly one a-Si. ⁇ top cell and one ⁇ c-Si: H bottom cell.
  • the top cell is the cell into which the light first enters.
  • the ⁇ c-Si: H absorber layer contributes about 75% of the total thickness of the active layer of an a-Si: H / ⁇ c-Si: H tandem solar cell.
  • the ⁇ c-Si: H bottom absorber layer with a thickness of 1000-3000 nanometers has by far the largest single layer thickness, its deposition rate decisively determines the annually achievable output of a production plant ,
  • a glass TCO-a-SiiH top cell layer system (TCO Engl, transparent conductive oxide) plus deposited thereon microcrystalline p-layer.
  • the glass has a thickness of approximately 1 millimeter
  • the TCO layer has a thickness of approximately 500 nanometers
  • the a-Si: H top cell has an adapted thickness of each due to the series connection to the ⁇ c-Si: H bottom cell about 140-390 nanometers up. This means that, depending on the ⁇ c-Si: H absorber layer thickness, the absorber layer thickness of the a-Si: H top cell was adjusted so that both single cells supply the same current.
  • the deposited thereon microcrystalline p-layer has a thickness of about 10 nanometers.
  • the substrate is first positioned parallel to the showerhead RF electrode with an electrode spacing of 10 mm and heated in vacuum to a substrate temperature of 200 ° C.
  • the base pressure is from about 10 -7 mbar.
  • the plasma chamber in which substrates can be coated to a size of 30x30 cm 2 , is continuously flooded with a hydrogen flux of 2700 sccm and silane flow of 24 sccm (0.9% silane concentration) and the plasma chamber pressure at 13.3 mbar regulated.
  • the gas mixture present in the chamber is completely discharged from the chamber. In turn, a constant deposition pressure is formed.
  • the process gases are admitted through the showerhead high-frequency electrode into the process chamber.
  • a plasma is ignited between the substrate and the showerhead high-frequency electrode and then regulated to a generator power of about 500 W (corresponds to about 0.4 W / cm 2 electrode surface), so that a ⁇ c-Si: H deposition rate. te of 0.7 nm / s is achieved.
  • the plasma excitation frequency is 13.56 MHz.
  • the deposition time required results from the desired ⁇ c-Si: H absorber layer thickness and the ⁇ c-Si: H deposition rate associated with the respective production process.
  • the ⁇ c-Si: H absorber layer deposition ends when the generator is switched off Expiration of the set deposition time.
  • the ⁇ c-Si: H absorber layer is deposited close to the ⁇ c-Si: H / a-Si: H transition and therefore optimized with respect to the layer properties.
  • a microcrystalline n-type layer was deposited to produce the a-Si: H / ⁇ c-Si: H tandem solar cell. This has a thickness of about 20 nanometers.
  • the back contact was made of ZnO / Ag (80 nanometers ZnO and 700 nanometers Ag).
  • the a-Si: H / ⁇ c-Si: H tandem solar cell thus has a ⁇ c-Si: H bottom cell on an a-Si: H top cell.
  • the a-Si: H / ⁇ c-Si: H tandem solar cells were then exposed in a degradation experiment for 1000 hours at a cell temperature of 50 ° C to an irradiance of 100 mW / cm 2 in order to determine the stabilized cell efficiency , The following values resulted:
  • the a-Si: H / ⁇ c-Si: H tandem solar cell no. 4 has a total layer thickness of the active semiconductor layers (pinpin without front and back contact) of about 640 nanometers.

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Abstract

L'invention concerne un procédé pour le dépôt de silicium microcristallin sur un substrat dans un système de chambre plasma, comprenant les étapes suivantes : le système de chambre plasma contient avant l'amorçage du plasma au moins un gaz réactif contenant du silicium, et de l'hydrogène, ou uniquement de l'hydrogène; amorçage du plasma; après l'amorçage du plasma, alimentation en continu du système de chambre plasma soit uniquement avec du gaz réactif contenant du silicium, soit au moins avec un mélange de gaz réactif contenant du silicium et d'hydrogène, la concentration en gaz réactif contenant du silicium étant réglée à une valeur supérieure à 0,5% lors de son apport dans la chambre; réglage de la puissance du plasma entre 0,1 et 2,5 W/cm2 de surface d'électrode; sélection d'une vitesse de dépôt supérieure à 0,5 nm/s et dépôt d'une couche microcristalline d'une épaisseur inférieure à 1000 nanomètres sur le substrat.
EP09801654A 2008-12-18 2009-11-18 Procédé de dépôt de silicium microcristallin sur un substrat Withdrawn EP2368275A2 (fr)

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DE102008063737A DE102008063737A1 (de) 2008-12-18 2008-12-18 Verfahren zur Abscheidung von mikrokristallinem Silizium auf einem Substrat
PCT/DE2009/001649 WO2010069287A2 (fr) 2008-12-18 2009-11-18 Procédé de dépôt de silicium microcristallin sur un substrat

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EP2740817A1 (fr) * 2012-12-05 2014-06-11 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude PECVD à couche mince de silicium microcristallin utilisant de l'hydrogène et des mélanges de silanes
DE102013102074A1 (de) 2013-03-04 2014-09-04 Schmid Vacuum Technology Gmbh Anlage und Verfahren zur Beschichtung von Substraten mit polykristallinem Silizium

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WO2007149945A2 (fr) * 2006-06-23 2007-12-27 Applied Materials, Inc. Procédés et dispositif de dépôt d'un film de silicium microcristallin pour dispositif photovoltaïque

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DE3119631A1 (de) * 1981-05-16 1982-11-25 Messerschmitt-Bölkow-Blohm GmbH, 8000 München "photovoltaische solarzelle"
JP2001355073A (ja) * 2001-04-27 2001-12-25 Canon Inc 堆積膜形成装置
US7186663B2 (en) * 2004-03-15 2007-03-06 Sharp Laboratories Of America, Inc. High density plasma process for silicon thin films
DE10308381B4 (de) * 2003-02-27 2012-08-16 Forschungszentrum Jülich GmbH Verfahren zur Abscheidung von Silizium
JP4025744B2 (ja) * 2004-03-26 2007-12-26 株式会社カネカ 積層型光電変換装置の製造方法
JP5259189B2 (ja) * 2005-10-03 2013-08-07 シャープ株式会社 シリコン系薄膜光電変換装置の製造方法
JP2008115460A (ja) * 2006-10-12 2008-05-22 Canon Inc 半導体素子の形成方法及び光起電力素子の形成方法
JP4630294B2 (ja) * 2007-01-29 2011-02-09 シャープ株式会社 光電変換装置及びその製造方法

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WO2007149945A2 (fr) * 2006-06-23 2007-12-27 Applied Materials, Inc. Procédés et dispositif de dépôt d'un film de silicium microcristallin pour dispositif photovoltaïque

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DE102008063737A9 (de) 2010-10-07
JP5746633B2 (ja) 2015-07-08
WO2010069287A3 (fr) 2011-03-03
JP2012512534A (ja) 2012-05-31
WO2010069287A2 (fr) 2010-06-24
US20110284062A1 (en) 2011-11-24
CN102257630A (zh) 2011-11-23

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