WO2008012098A2 - Silane-free plasma-assisted cvd deposition of silicon nitride as an antireflective film and for hydrogen passivation of photocells constructed on silicon wafers - Google Patents

Silane-free plasma-assisted cvd deposition of silicon nitride as an antireflective film and for hydrogen passivation of photocells constructed on silicon wafers Download PDF

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WO2008012098A2
WO2008012098A2 PCT/EP2007/006665 EP2007006665W WO2008012098A2 WO 2008012098 A2 WO2008012098 A2 WO 2008012098A2 EP 2007006665 W EP2007006665 W EP 2007006665W WO 2008012098 A2 WO2008012098 A2 WO 2008012098A2
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starting material
gaseous
hydrogen
silicon
photocells
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German (de)
French (fr)
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WO2008012098A3 (en
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Hans-Peter Reiser
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Hans-Peter Reiser
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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
    • C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
    • C23C16/34—Nitrides
    • C23C16/345—Silicon nitride
    • 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
    • C23C16/511—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 microwave discharges
    • 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
    • C23C16/515—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 pulsed discharges
    • 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
    • H01L31/02—Details
    • H01L31/0216—Coatings
    • H01L31/02161—Coatings for devices characterised by at least one potential jump barrier or surface barrier
    • H01L31/02167—Coatings for devices characterised by at least one potential jump barrier or surface barrier for solar cells
    • H01L31/02168—Coatings for devices characterised by at least one potential jump barrier or surface barrier for solar cells the coatings being antireflective or having enhancing optical properties for the 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
    • H01L31/186—Particular post-treatment for the devices, e.g. annealing, impurity gettering, short-circuit elimination, recrystallisation
    • H01L31/1868—Passivation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
    • H01L21/02112—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer
    • H01L21/02123—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon
    • H01L21/0217—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon the material being a silicon nitride not containing oxygen, e.g. SixNy or SixByNz
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
    • H01L21/02205—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates the layer being characterised by the precursor material for deposition
    • H01L21/02208—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates the layer being characterised by the precursor material for deposition the precursor containing a compound comprising Si
    • H01L21/02219—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates the layer being characterised by the precursor material for deposition the precursor containing a compound comprising Si the compound comprising silicon and nitrogen
    • H01L21/02222—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates the layer being characterised by the precursor material for deposition the precursor containing a compound comprising Si the compound comprising silicon and nitrogen the compound being a silazane
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02225—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer
    • H01L21/0226—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process
    • H01L21/02263—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase
    • H01L21/02271—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase deposition by decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition
    • H01L21/02274—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase deposition by decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition in the presence of a plasma [PECVD]
    • 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
    • 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 systems and methods for CVD deposition.
  • the cross section of a typical photocell mounted on a silicon wafer is shown in FIG.
  • the silicon wafer (the light absorber of the photocell) 3 is doped so that a p-n junction can form. Incident light is absorbed by the wafer and electron-hole pairs are formed by converting the photon energy.
  • the electric field established by the p-n junction forces electrons and holes to propagate in opposite directions to the wafer surfaces.
  • the electrons are collected by the backside electrode 4 while the front electrode 1 neutralizes the holes by injecting electrons into the surface of the doped silicon wafer 3. While the back metallic electrode generally covers the entire wafer surface, the front metallic electrode generally has a grid structure to allow light to penetrate into the wafer surface.
  • the front and rear electrodes may be connected by an electrical load to form an electric circuit, and an electric current will flow when the photocell is exposed to light.
  • the purpose of the anti-reflective layer 2 between the silicon wafer surface 3 and the front electrode 1 is to reduce light reflection on the silicon wafer surface. This layer changes the look of a shiny metal-like surface to a dark blue color.
  • the anti-reflective layer must be formed of an optically transparent material, such as oxides and nitrides, and the thickness of this layer is chosen in terms of its refractive index so that the optical thickness corresponds to a quarter of a specific wavelength of the incident light spectrum.
  • the front electrode grid 1 is applied to the anti-reflective layer 2. Electrical conductivity between the front electrode grid and silicon wafer is achieved by subsequently introducing the entire photocell into a high temperature environment, a so-called burn-in step.
  • Plasma assisted chemical vapor deposition which most commonly uses silane gas (chemical formula SiH 4 ) as a source of silicon (and hydrogen) and ammonia as a source of atomic nitrogen and hydrogen.
  • silane gas chemical formula SiH 4
  • ammonia as a source of atomic nitrogen and hydrogen.
  • the power required to split the starting material in the plasma is supplied as high frequency, very high frequency or microwave power. Usually, the deposition rates grow with increasing frequency.
  • Chemical vapor deposition is a process in which a thin film is deposited on a substrate surface by exposing chemicals to gaseous or chemical vapor Vapor phase react together to form a film.
  • the gases or vapors used for CVD are gases or compounds that contain the element or functional group of the elements that are to be deposited and that may be caused to react with the substrate or other gas to deposit a film.
  • the CVD reaction can be thermally activated, plasma induced, plasma assisted or activated by light in photon induced systems.
  • Silangas the source of silicon and hydrogen and no other unwanted atomic species, is an unstable and highly reactive compound, (and) ideal for high deposition rates.
  • silane its responsiveness, is also a big drawback.
  • silane gas ignites spontaneously without any additional energy input. This makes silane extremely dangerous and difficult to handle in a manufacturing environment.
  • Extensive and expensive safety equipment is required for storage, silane gas supply to the CVD reactor and removal of exhaust gases from the CVD reactor.
  • the added cost of security measures is a distinct disadvantage of CVD-based silicon nitride forming processes as compared to other methods such as cathode-erosion-based processes using solid silicon. Therefore, this invention, a silane-free CVD process for depositing anti-reflective silicon nitride coating and simultaneous hydrogen passivation, is a major step forward in reducing the cost of production of crystalline photocells.
  • gaseous or vaporous starting materials containing silicon, nitrogen and hydrogen are introduced into a vacuum vessel 10 by means of manifold systems 11 and 12.
  • a plasma source 5 operated with electromagnetic high-frequency energy, preferably with pulsed microwave energy, ignites a plasma discharge 6 under suitable vacuum conditions.
  • a silicon nitride film 2 is formed Form on the hot, prefabricated, based on silicon wafer 3 photocells 7, which are attached to a support and heater 8, while hydrogen atoms diffuse into the silicon wafer to passivate free compounds.
  • the silicon-containing starting material is not silane but an organosilicon compound such as hexamethyldisilazane.
  • FIG. 1 shows a cross section of a photocell mounted on silicon wafers. It mainly consists of a doped silicon wafer 3 as a light absorber, the rear electrode 4, the front electrode grid 1, and the anti-reflection film 2.
  • FIG. 2 illustrates an example of a reactor for applying an anti-reflective film to a photocell constructed on a silicon wafer by plasma enhanced chemical vapor deposition.
  • the reactor consists of a vacuum vessel 10, the photocells 7 attached to a support and heater 8, the plasma source 5 with a plasma 6, the pump nozzles 9, 9 'and the distribution systems 11 and 12 for the starting material.
  • Pre-machined silicon wafer based photocells 7 are placed in a vacuum container 10 and attached to a carrier and heating platform 8.
  • the residual gas pressure in the vacuum container must be low enough to avoid contamination of the applied film, especially by oxygen. Frequent venting of the container between operating cycles should therefore be avoided.
  • the operating cycle begins by the introduction of the feedstock gases or vapors into the vessel through gas distribution systems 11 and 12.
  • the silicon-containing feedstock system 11 is between the photocells 7 and the plasma source 5, and all other gaseous feedstock is replaced by another feedstock distribution system 12 on the opposite Side of the plasma source 5 admitted.
  • all the necessary starting materials could be supplied through a single manifold system, but then the plasma source 5 would undergo self-coating, which is generally undesirable.
  • the plasma discharge 6 is ignited at the plasma source 5 by electrical or electromagnetic energy supplied by suitable energy sources. It is also possible to continuously bring the photocells 7 into and out of the film forming process zone during the film forming process.
  • a power source for a very high electromagnetic frequency such as 2450 MHz, is chosen since high plasma densities resulting in high film deposition rates are desirable.
  • the gaseous or vaporous, non-silicon-containing feedstock flow which is introduced through the distribution system 12, moves through the plasma region 6 on its way to the vacuum pump nozzles 9, 9 '.
  • the molecules supplied may be dissociated, radicalized, excited, or ionized, depending on the nature of the interaction with plasma particles or plasma radiation.
  • Some of the starting material molecules will be in energized states as it propagates to the photocells 7 and pump nozzles 9, 9 ', which may be arranged as in FIG. 2, but may also be behind the carrier and heater 8.
  • the silicon-containing feedstock introduced through the manifold system 11 will also spread to the vacuum pump stubs 9, 9 '. Because the silicon-containing molecules do not traverse the plasma region, they are excited and disassembled by plasma radiation and by interaction with energetically-excited nitrogen-containing source material molecules. The variety of energetically excited species arriving at the surface of the silicon wafer forms the silicon nitride film and brings hydrogen atoms to the silicon wafer to passivate free bonds. However, the exact location of incorporation of the silicon-containing starting material may depend on general process conditions, desired deposition rates, and the permissible number of other atoms, such as carbon, in the anti-reflective film. It may therefore be necessary to directly expose the silicon-containing starting material molecules to the plasma.
  • the inventive step of this patent application is to replace silane gas with an organic silicon compound such as hexamethyldisilazane (chemical formula (CH 3 ) 3 -Si-NH-Si- (CH 3 ) 3 ), the efficient decomposition of the corresponding molecules and the concomitant ones Suppression of carbon atom inclusion in the anti-reflective film crucial.
  • the degree of molecular disassembly by the plasma discharge depends mainly on the plasma electron temperature, plasma density and intensity of the vacuum UV radiation of the plasma.
  • the decomposition should be such that carbon should remain as or form volatile hydrocarbon compounds which may eventually be removed from the process area by the vacuum pump stubs 9, 9 1 .
  • the flow rate ratio between the silicon-containing gaseous starting material and the remaining starting material should usually be selected so that stoichiometric silicon nitride (chemical formula Si 3 N 4 ) can be formed.
  • various types of silicon based photocells may require adjustments to the silicon nitride composition. All adjustments seek maximum values of the efficiency of the photocell. Should the hydrogen content of the silicon and nitrogen containing starting materials be insufficient for the passivation of the silicon wafer, molecular hydrogen can be added to the plasma process.
  • the plasma source 5 can be supplied with microwave energy (preferably 2450 MHz) and operated in a pulsed mode.
  • microwave energy preferably 2450 MHz
  • the peak heights of the pulses of preferred rectangular shape should be several times (for example: 5 times) higher than the comparable continuous wave level, which leads to acceptable results of the deposited films.
  • the pulse-to-pulse ratio should be set reciprocally to the peak power ratios.
  • Plasma source 5 and source material distribution systems 11, 12 as shown in Fig. 2 can be installed above or below the photocells 7.
  • the carrier and heater 8 must be aligned accordingly.

Abstract

The invention relates to a method for producing an antireflective silicon nitride film with simultaneous hydrogen atom diffusion in photocells based on silicon wafers during a chemical gas phase deposition process, wherein the method comprises a suitable vacuum chamber for CVD processes which comprise silicon-wafer-based photocells at a suitable increased temperature, at least one electromagnetic energy source to form at least one plasma discharge, to produce radicalized or energetically excited species from gaseous starting material, a first gaseous or vaporous starting material, which comprises only silicon, hydrogen, nitrogen and carbon, a second gaseous or vaporous starting material, which comprises only nitrogen and hydrogen, and a third gaseous or vaporous starting material, which comprises only hydrogen.

Description

Beschreibung description
Silan freie plasmagestützte CVD-Abscheidung von Siliziumnitrid als anti-reflektierendem Film und zur Wasserstoffpassivierung von auf Siliziumwafem aufgebauten PhotozellenSilane-free plasma-assisted CVD deposition of silicon nitride as an anti-reflective film and hydrogen passivation of silicon photocells
Bereich der ErfindungField of the invention
Die vorliegende Erfindung bezieht sich auf Systeme und Verfahren zur CVD-Abscheidung.The present invention relates to systems and methods for CVD deposition.
Hintergrund der ErfindungBackground of the invention
Der Querschnitt einer typischen auf einem Siliziumwafer aufgebauten Photozelle ist in Fig. 1 gezeigt. Der Siliziumwafer (der Lichtabsorber der Photozelle) 3 ist dotiert, so dass sich ein p-n Übergang bilden kann. Einfallendes Licht wird vom Wafer absorbiert und Elektron-Loch Paare werden durch Umwandlung der Photonenergie gebildet. Das elektrische Feld, das durch den p-n Übergang aufgebaut wird, zwingt Elektronen und Löcher sich in entgegengesetzten Richtungen zu den Waferoberflächen hin auszubreiten. Die Elektronen werden durch die rückseitige Elektrode 4 gesammelt, während die vordere Elektrode 1 die Löcher durch Injizieren von Elektronen in die Oberfläche des dotierten Siliziumwafers 3 neutralisiert. Während die hintere metallische Elektrode im allgemeinen die gesamte Waferoberfläche bedeckt, hat die vordere metallische Elektrode im allgemeinen eine Gitterstruktur, um zu ermöglichen, dass Licht in die Waferoberfläche eindringt.The cross section of a typical photocell mounted on a silicon wafer is shown in FIG. The silicon wafer (the light absorber of the photocell) 3 is doped so that a p-n junction can form. Incident light is absorbed by the wafer and electron-hole pairs are formed by converting the photon energy. The electric field established by the p-n junction forces electrons and holes to propagate in opposite directions to the wafer surfaces. The electrons are collected by the backside electrode 4 while the front electrode 1 neutralizes the holes by injecting electrons into the surface of the doped silicon wafer 3. While the back metallic electrode generally covers the entire wafer surface, the front metallic electrode generally has a grid structure to allow light to penetrate into the wafer surface.
Die vordere und hintere Elektrode können durch eine elektrische Last verbunden werden, um einen elektrischen Stromkreis zu bilden, und ein elektrischer Strom wird fließen, wenn die Photozelle Licht ausgesetzt wird. Der Zweck der anti-reflektierenden Schicht 2 zwischen der Siliziumwaferoberfläche 3 und der vorderen Elektrode 1 ist die Herabsetzung von Lichtreflexion an der Siliziumwaferoberfläche. Diese Schicht verändert das Aussehen einer glänzenden metallähnlichen Oberfläche in dunkelblaue Farbe. Im allgemeinen muss die anti-reflektierende Schicht aus einem optisch transparenten Material gebildet werden, wie Oxide und Nitride und die Dicke dieser Schicht wird in Bezug auf ihren Brechungsindex gewählt, so dass die optische Dicke einem Viertel einer spezifischen Wellenlänge des einfallenden Lichtspektrums entspricht. Vor oder während dem Aufbringen der anti-reflektierenden Schicht müssen Wasserstoffatome in die Siliziumwaferoberfläche diffundiert werden, um freie Bindungen der Siliziumatome im Kristallgitter des Siliziumwafers zu sättigen. Dies erfordert, dass sich der Wafer bei erhöhten Temperaturen befindet, gewöhnlich zwischen zweihundert und vierhundert Grad Celsius. Ohne diese Passivierung wirken diese ungesättigten Atombindungen als Abfangstellen für Elektronen die sich im Leitungsband befinden. Abgefangene Elektronen sind für den photovoltaischen Strom verloren und verschlechtern den Wirkungsgrad der Photozelle. Nach dem Aufbringen der anti- reflektierenden Schicht und der Wasserstoffpassivierung wird das vordere Elektrodengitter 1 auf die anti-reflektierende Schicht 2 aufgebracht. Elektrische Leitfähigkeit zwischen vorderem Elektrodengitter und Siliziumwafer wird erreicht durch ein anschließendes Einbringen der gesamten Photozelle in eine Hochtemperaturumgebung, einen sogenannten Einbrennschritt.The front and rear electrodes may be connected by an electrical load to form an electric circuit, and an electric current will flow when the photocell is exposed to light. The purpose of the anti-reflective layer 2 between the silicon wafer surface 3 and the front electrode 1 is to reduce light reflection on the silicon wafer surface. This layer changes the look of a shiny metal-like surface to a dark blue color. In general, the anti-reflective layer must be formed of an optically transparent material, such as oxides and nitrides, and the thickness of this layer is chosen in terms of its refractive index so that the optical thickness corresponds to a quarter of a specific wavelength of the incident light spectrum. Before or during the application of the anti-reflective layer, hydrogen atoms must be diffused into the silicon wafer surface in order to saturate free bonds of the silicon atoms in the crystal lattice of the silicon wafer. This requires that the wafer be at elevated temperatures usually between two and four hundred degrees Celsius. Without this passivation, these unsaturated atomic bonds act as scavenger sites for electrons in the conduction band. Trapped electrons are lost to the photovoltaic current and degrade the efficiency of the photocell. After the application of the anti-reflective layer and the hydrogen passivation, the front electrode grid 1 is applied to the anti-reflective layer 2. Electrical conductivity between the front electrode grid and silicon wafer is achieved by subsequently introducing the entire photocell into a high temperature environment, a so-called burn-in step.
Es ist heutzutage Stand der Technologie die Wasserstoffpassivierung des Siliziumwafers während des Aufbringens der anti-reflektierenden Schicht dadurch zu erreichen, dass ein entsprechenderIt is now state of the art to achieve the hydrogen passivation of the silicon wafer during the application of the anti-reflective layer by providing a corresponding
Prozess angewendet wird. Es ist allgemein anerkannt, einen auf Vakuumplasma basierendenProcess is applied. It is generally accepted, based on vacuum plasma
Siliziumnitrid Beschichtungsprozess in einer mit Wasserstoffatomen angereicherten Umgebung anzuwenden.Apply silicon nitride coating process in a hydrogen-enriched environment.
Primär gibt es zwei unterschiedliche Vakuumplasma Prozesse, die gegenwärtig angewendet werden um die Siliziumnitridschicht zu bilden:Primarily, there are two different vacuum plasma processes currently used to form the silicon nitride layer:
a. Kathodenabtragung von festen Siliziumtargets (Sputtern), wobei Argongas zur Plasmabildung und Ammoniak (chemische Formel NH3) als eine Quelle für atomaren Stickstoff und der Wasserstoff zur Passivierung verwendet werden. Zusätzliches Wasserstoffgas kann, wenn notwendig, dazugegeben werden. Die notwendige Energie für den Erosionsprozess wird als niederfrequenter Wechselstrom (im kHz Bereich) oder als Hochfrequenzleistung bereitgestellt. Gewöhnlich verringern sich die Ablagerungsraten mit zunehmender Frequenz.a. Cathode removal of solid silicon targets (sputtering) using argon gas for plasma formation and ammonia (chemical formula NH 3 ) as a source of atomic nitrogen and the hydrogen for passivation. Additional hydrogen gas may be added, if necessary. The necessary energy for the erosion process is provided as low-frequency alternating current (in the kHz range) or as high-frequency power. Usually, the deposition rates decrease with increasing frequency.
b. Plasma unterstützte chemische Gasphasenabscheidung (CVD), benutzt am häufigsten Silangas (chemische Formel SiH4) als Ausgangsmaterial für Silizium (und Wasserstoff) und Ammoniak als eine Quelle für atomaren Stickstoff und Wasserstoff. Die notwendige Leistung zur Aufspaltung des Ausgangsmaterials im Plasma wird als Hochfrequenz, sehr hohe Frequenz oder Mikrowellenleistung, geliefert. Gewöhnlich wachsen die Abscheidungsraten mit wachsender Frequenz.b. Plasma assisted chemical vapor deposition (CVD), which most commonly uses silane gas (chemical formula SiH 4 ) as a source of silicon (and hydrogen) and ammonia as a source of atomic nitrogen and hydrogen. The power required to split the starting material in the plasma is supplied as high frequency, very high frequency or microwave power. Usually, the deposition rates grow with increasing frequency.
Chemische Gasphasenabscheidung (CVD) ist ein Prozess, bei dem ein dünner Film auf einer Substratoberfläche dadurch abgeschieden wird, dass Chemikalien in der gasförmigen oder Dampfphase zusammen reagieren um einen Film zu bilden. Die Gase oder Dämpfe die für CVD verwendet werden sind Gase oder Verbindungen, die das Element oder die Funktionsgruppe der Elemente enthalten, die abgeschieden werden sollen und die veranlasst werden können mit dem Substrat oder anderem Gas zu reagieren um einen Film abzuscheiden. Die CVD Reaktion kann thermisch aktiviert, Plasma induziert, Plasma unterstützt oder durch Licht in Photon induzierten Systemen aktiviert werden.Chemical vapor deposition (CVD) is a process in which a thin film is deposited on a substrate surface by exposing chemicals to gaseous or chemical vapor Vapor phase react together to form a film. The gases or vapors used for CVD are gases or compounds that contain the element or functional group of the elements that are to be deposited and that may be caused to react with the substrate or other gas to deposit a film. The CVD reaction can be thermally activated, plasma induced, plasma assisted or activated by light in photon induced systems.
Silangas, die Quelle für Silizium und Wasserstoff und keine andere unerwünschte Atomart, ist eine instabile und sehr reaktionsfähige Verbindung, (und) ideal für hohe Ablagerungsraten. Aber der Hauptvorteil von Silan, seine Reaktionsfähigkeit, ist auch ein großer Nachteil. Wenn es bei Raumtemperatur in Kontakt mit Luft kommt, entzündet sich Silangas spontan ohne jede zusätzliche Energiezufuhr. Dies macht Silan extrem gefährlich und schwierig zu handhaben in einer Fertigungsumgebung. Umfangreiche und teuere Sicherheitseinrichtungen sind für Speicherung, Silangasversorgung des CVD Reaktors und die Abführung der Abgase vom CVD Reaktor notwendig. Die zusätzlichen Kosten für Sicherheitsmaßnahmen sind ein klarer Nachteil von auf CVD aufgebauten Siliziumnitrid bildenden Prozessen im Vergleich zu anderen Methoden, wie auf Kathodenerosion basierenden Prozessen die festes Silizium verwenden. Deshalb ist diese Erfindung, nämlich ein Silan freier CVD Prozess zur Ablagerung von anti-reflektierender Siliziumnitridbeschichtung und gleichzeitige Wasserstoffpassivierung, ein größerer Schritt vorwärts in Richtung Produktionskostenreduzierung von kristallinen Photozellen.Silangas, the source of silicon and hydrogen and no other unwanted atomic species, is an unstable and highly reactive compound, (and) ideal for high deposition rates. But the main advantage of silane, its responsiveness, is also a big drawback. When exposed to air at room temperature, silane gas ignites spontaneously without any additional energy input. This makes silane extremely dangerous and difficult to handle in a manufacturing environment. Extensive and expensive safety equipment is required for storage, silane gas supply to the CVD reactor and removal of exhaust gases from the CVD reactor. The added cost of security measures is a distinct disadvantage of CVD-based silicon nitride forming processes as compared to other methods such as cathode-erosion-based processes using solid silicon. Therefore, this invention, a silane-free CVD process for depositing anti-reflective silicon nitride coating and simultaneous hydrogen passivation, is a major step forward in reducing the cost of production of crystalline photocells.
Zusammenfassung der ErfindungSummary of the invention
Eine Methode um einen anti-reflektierenden Siliziumnitridfilm durch einen Silan freien, plasmaverstärkten CVD Prozess auf Siliziumwafer basierten Photozellen aufzubringen, und um gleichzeitig den Siliziumwafer durch Diffusion von Wasserstoffatomen durch die Oberfläche des Siliziumwafers zu passivieren.A method of applying an anti-reflection silicon nitride film by a silane-free plasma-enhanced CVD process to silicon wafer-based photocells and simultaneously passivating the silicon wafer by diffusion of hydrogen atoms through the surface of the silicon wafer.
In einer typischen Ausführung werden, wie in Fig. 2 gezeigt, Silizium, Stickstoff und Wasserstoff enthaltende gasförmige oder dampfförmige Ausgangsmaterialien in einen Vakuumbehälter 10 mittels Verteilersystemen 11 und 12 eingeführt. Eine mit elektromagnetischer Hochfrequenzenergie, vorzugsweise mit gepulster Mikrowellenenergie, betrieben Plasmaquelle 5 zündet unter geeigneten Vakuumbedingungen eine Plasmaentladung 6. Ein Siliziumnitridfilm 2 wird sich an den heißen, vorgefertigten, auf Siliziumwafer 3 basierten Photozellen 7 bilden, die an einer Träger und Heizvorrichtung 8 befestigt sind, während Wasserstoffatome in den Siliziumwafer eindiffundieren um freie Verbindungen zu passivieren. Es ist von Vorteil dass das Silizium enthaltende Ausgangsmaterial nicht Silan ist sondern eine Organosiliziumverbindung wie Hexamethyldisilazan.In a typical embodiment, as shown in FIG. 2, gaseous or vaporous starting materials containing silicon, nitrogen and hydrogen are introduced into a vacuum vessel 10 by means of manifold systems 11 and 12. A plasma source 5 operated with electromagnetic high-frequency energy, preferably with pulsed microwave energy, ignites a plasma discharge 6 under suitable vacuum conditions. A silicon nitride film 2 is formed Form on the hot, prefabricated, based on silicon wafer 3 photocells 7, which are attached to a support and heater 8, while hydrogen atoms diffuse into the silicon wafer to passivate free compounds. It is advantageous that the silicon-containing starting material is not silane but an organosilicon compound such as hexamethyldisilazane.
Kurze Beschreibung der ZeichnungenBrief description of the drawings
Figur 1 zeigt einen Querschnitt einer auf Siliziumwafer aufgebauten Photozelle. Es besteht hauptsächlich aus einem dotierten Siliziumwafer 3 als ein Lichtabsorber, der hinteren Elektrode 4, dem vorderen Elektrodengitter 1 und dem anti-reflektierenden Film 2.FIG. 1 shows a cross section of a photocell mounted on silicon wafers. It mainly consists of a doped silicon wafer 3 as a light absorber, the rear electrode 4, the front electrode grid 1, and the anti-reflection film 2.
Figur 2 veranschaulicht ein Beispiel eines Reaktors für das Aufbringen eines anti-reflektierenden Films auf eine Photozelle, die auf einem Siliziumwafer aufgebaut ist, durch Plasma verstärkte chemische Gasphasenabscheidung. Der Reaktor besteht aus einem Vakuumbehälter 10, den Photozellen 7, die an einem Träger und Heizvorrichtung 8 befestigt sind, der Plasmaquelle 5 mit einem Plasma 6, den Pumpstutzen 9, 9' und den Verteilungssystemen 11 und 12 für das Ausgangsmaterial.Figure 2 illustrates an example of a reactor for applying an anti-reflective film to a photocell constructed on a silicon wafer by plasma enhanced chemical vapor deposition. The reactor consists of a vacuum vessel 10, the photocells 7 attached to a support and heater 8, the plasma source 5 with a plasma 6, the pump nozzles 9, 9 'and the distribution systems 11 and 12 for the starting material.
Detaillierte BeschreibungDetailed description
Vorbearbeitete auf Siliziumwafer basierende Photozellen 7 (wie in Fig. 1 gezeigt, ohne die Siliziumnitridschicht 2 und das vordere Kontaktgitter 1) werden in einen Vakuumbehälter 10 gebracht und an einer Trägern und Heizplattform 8 angebracht. Der Restgasdruck im Vakuumbehälter muss niedrig genug sein, um Verunreinigungen des aufgebrachten Films, vor allem durch Sauerstoff, zu vermeiden. Häufiges Belüften des Behälters zwischen Betriebszyklen sollte deshalb vermieden werden.Pre-machined silicon wafer based photocells 7 (as shown in FIG. 1, without the silicon nitride layer 2 and the front contact grid 1) are placed in a vacuum container 10 and attached to a carrier and heating platform 8. The residual gas pressure in the vacuum container must be low enough to avoid contamination of the applied film, especially by oxygen. Frequent venting of the container between operating cycles should therefore be avoided.
Der Betriebszyklus beginnt durch das Einlassen der Ausgangsmaterialgase oder Dämpfe in den Behälter durch Gasverteilungssysteme 11 und 12. Vorzugsweise befindet sich das Silizium enthaltende Ausgangsmaterialverteilersystem 11 zwischen den Photozellen 7 und der Plasmaquelle 5, und alles andere gasförmigen Ausgangsmaterial wird durch ein anderes Ausgangsmaterialverteilersystem 12 auf der entgegengesetzten Seite der Plasmaquelle 5 eingelassen. Natürlich könnten alle notwendigen Ausgangsmaterialien durch ein einziges Verteilersystem zugeführt werden, aber dann würde die Plasmaquelle 5 Selbstbeschichtung erfahren, was im Allgemeinen nicht wünschenswert ist. Wenn sich alle Ausgangsmaterialgasflüsse bei einem geeigneten Druck für nicht magnetisierte CVD (üblicherweise zwischen 0,05 und 1 hPa) stabilisiert haben und die Träger und Heizvorrichtung 8 die Photozellen auf die gewünschte Temperatur aufgeheizt hat (gewöhnlich zwischen 200 und 400 0C, abhängig vom Prozess und Siliziumwafermaterial), wird die Plasmaentladung 6 an der Plasmaquelle 5 durch elektrische oder elektromagnetische Energie gezündet, die durch geeignete Energiequellen zugeführt wird. Es ist ebenfalls möglich die Photozellen 7 während des Filmbildungsprozesses kontinuierlich in die Filmbildungsprozesszone hinein und wieder herauszubringen.The operating cycle begins by the introduction of the feedstock gases or vapors into the vessel through gas distribution systems 11 and 12. Preferably, the silicon-containing feedstock system 11 is between the photocells 7 and the plasma source 5, and all other gaseous feedstock is replaced by another feedstock distribution system 12 on the opposite Side of the plasma source 5 admitted. Of course, all the necessary starting materials could be supplied through a single manifold system, but then the plasma source 5 would undergo self-coating, which is generally undesirable. When all of the feed gas flows have stabilized at a suitable pressure for non-magnetized CVD (typically between 0.05 and 1 hPa) and the carrier and heater 8 has heated the photocells to the desired temperature (usually between 200 and 400 ° C, depending on the process) and silicon wafer material), the plasma discharge 6 is ignited at the plasma source 5 by electrical or electromagnetic energy supplied by suitable energy sources. It is also possible to continuously bring the photocells 7 into and out of the film forming process zone during the film forming process.
Vorzugsweise wird eine Energiequelle für eine sehr hohe elektromagnetische Frequenz, wie 2450 MHz gewählt, da hohe Plasmadichten, die in hohen Filmauftragsraten resultieren, wünschenswert sind. Der gas- oder dampfförmige, nicht Silizium enthaltende Ausgangsmaterialfluss, welcher durch das Verteilungssystem 12 eingeleitet wird, bewegt sich durch das Plasmagebiet 6 auf seinem Weg zu den Vakuumpumpstutzen 9, 9'. Im Plasmagebiet können die zugeführten Moleküle dissoziiert, radikalisiert, angeregt oder ionisiert werden, abhängig von der Art der Wechselwirkung mit Plasmateilchen oder Plasmastrahlung. Ein gewisser Anteil der Ausgangsmaterialmoleküle wird in energetisch angeregten Zuständen sein, während er sich zu den Photozellen 7 und den Pumpstutzen 9, 9' ausbreitet, die wie in Fig. 2 angeordnet sein können, sich aber ebenso hinter der Träger und Heizvorrichtung 8 befinden können.Preferably, a power source for a very high electromagnetic frequency, such as 2450 MHz, is chosen since high plasma densities resulting in high film deposition rates are desirable. The gaseous or vaporous, non-silicon-containing feedstock flow, which is introduced through the distribution system 12, moves through the plasma region 6 on its way to the vacuum pump nozzles 9, 9 '. In the plasma region, the molecules supplied may be dissociated, radicalized, excited, or ionized, depending on the nature of the interaction with plasma particles or plasma radiation. Some of the starting material molecules will be in energized states as it propagates to the photocells 7 and pump nozzles 9, 9 ', which may be arranged as in FIG. 2, but may also be behind the carrier and heater 8.
Das Silizium enthaltende Ausgangsmaterial, das durch das Verteilersystem 11 eingelassen wird, wird sich ebenfalls zu den Vakuumpumpstutzen 9, 9' ausbreiten. Da die Silizium enthaltenden Moleküle nicht das Plasmagebiet durchqueren, werden sie durch Plasmastrahlung und durch Wechselwirkung mit energetisch angeregten, Stickstoff enthaltenden Ausgangsmaterialmolekülen, angeregt und zerlegt. Die Vielfalt von energetisch angeregten Spezies, die an der Oberfläche des Siliziumwafers ankommen, bildet den Siliziumnitridfilm und bringen Wasserstoffatome zum Siliziumwafer um freie Bindungen zu passivieren. Der genaue Ort der Einbringung des Silizium enthaltenden Ausgangsmaterials kann jedoch von den allgemeinen Prozessbedingungen, den gewünschten Ablagerungsraten und der zulässigen Anzahl anderer Atome, wie Kohlenstoff, in dem anti-reflektierenden Film abhängen. Es kann daher notwendig sein, die Silizium enthaltenden Ausgangsmaterialmoleküle dem Plasma direkt auszusetzen. Da der erfinderische Schritt dieser Patentanmeldung im Ersatz von Silangas durch eine organische Siliziumverbindung, wie Hexamethyldisilazan (chemische Formel (CH3)3-Si-NH-Si-(CH3)3) liegt, ist die wirksame Zerlegung der entsprechenden Moleküle und die gleichzeitige Unterdrückung von Kohlenstoffatomeinschluss in dem anti-reflektierenden Film entscheidend. Der Grad der molekularen Zerlegung durch die Plasmaentladung hängt hauptsächlich ab von Plasmaelektronentemperatur, Plasmadichte und Intensität der Vakuum-UV-Strahlung des Plasmas. Vorzugsweise sollte die Zerlegung so sein, dass Kohlenstoff als flüchtige Kohlewasserstoffverbindungen übrig bleibt oder solchen bilden sollte, die schließlich durch die Vakuumpumpstutzen 9, 91 aus dem Prozessgebiet abgeführt werden können.The silicon-containing feedstock introduced through the manifold system 11 will also spread to the vacuum pump stubs 9, 9 '. Because the silicon-containing molecules do not traverse the plasma region, they are excited and disassembled by plasma radiation and by interaction with energetically-excited nitrogen-containing source material molecules. The variety of energetically excited species arriving at the surface of the silicon wafer forms the silicon nitride film and brings hydrogen atoms to the silicon wafer to passivate free bonds. However, the exact location of incorporation of the silicon-containing starting material may depend on general process conditions, desired deposition rates, and the permissible number of other atoms, such as carbon, in the anti-reflective film. It may therefore be necessary to directly expose the silicon-containing starting material molecules to the plasma. Since the inventive step of this patent application is to replace silane gas with an organic silicon compound such as hexamethyldisilazane (chemical formula (CH 3 ) 3 -Si-NH-Si- (CH 3 ) 3 ), the efficient decomposition of the corresponding molecules and the concomitant ones Suppression of carbon atom inclusion in the anti-reflective film crucial. The degree of molecular disassembly by the plasma discharge depends mainly on the plasma electron temperature, plasma density and intensity of the vacuum UV radiation of the plasma. Preferably, the decomposition should be such that carbon should remain as or form volatile hydrocarbon compounds which may eventually be removed from the process area by the vacuum pump stubs 9, 9 1 .
Das Flussratenverhältnis zwischen dem Silizium enthaltenden gasförmigen Ausgangsmaterial und dem übrigbleibenden Ausgangsmaterial sollte gewöhnlich so gewählt werden, dass stöchiometrisch Siliziumnitrid (chemische Formel Si3N4) gebildet werden kann. Jedoch können verschiedene Arten von auf Silizium basierten Photozellen Anpassungen der Zusammensetzung des Siliziumnitrids erfordern. Alle Anpassungen erstreben maximale Werte des Wirkungsgrades der Photozelle. Sollte der Wasserstoffgehalt der Silizium und Stickstoff enthaltenden Ausgangsmaterialien für die Passivierung des Siliziumwafers nicht ausreichend sein, kann molekularer Wasserstoff dem Plasmaprozess zugefügt werden.The flow rate ratio between the silicon-containing gaseous starting material and the remaining starting material should usually be selected so that stoichiometric silicon nitride (chemical formula Si 3 N 4 ) can be formed. However, various types of silicon based photocells may require adjustments to the silicon nitride composition. All adjustments seek maximum values of the efficiency of the photocell. Should the hydrogen content of the silicon and nitrogen containing starting materials be insufficient for the passivation of the silicon wafer, molecular hydrogen can be added to the plasma process.
Um hohe Ablagerungsraten, sowie ein geeignetes Maß von molekularer Zerlegung des Ausgangsmaterials zu erhalten und um die räumliche Gleichverteilung des Anlagerungsprozesses zu erhöhen, kann die Plasmaquelle 5 mit Mikrowellenenergie versorgt (vorzugsweise 2450 MHz) und in einem gepulsten Mode betrieben werden. Vorzugsweise sollten die Peakhöhen der Pulse von bevorzugter Rechteckform einige Male (zum Beispiel: 5 mal) höher sein als der vergleichbare Dauerstrichpegel, der zu akzeptablen Ergebnissen der abgeschiedenen Filme führt. Das Puls-an zu Puls-aus Verhältnis sollte reziprok zu den Spitzenleistungsverhältnissen gesetzt werden.In order to obtain high deposition rates, as well as a suitable level of molecular decomposition of the starting material and to increase the spatial uniformity of the deposition process, the plasma source 5 can be supplied with microwave energy (preferably 2450 MHz) and operated in a pulsed mode. Preferably, the peak heights of the pulses of preferred rectangular shape should be several times (for example: 5 times) higher than the comparable continuous wave level, which leads to acceptable results of the deposited films. The pulse-to-pulse ratio should be set reciprocally to the peak power ratios.
Plasmaquelle 5 und Ausgangsmaterialverteilungssysteme 11 , 12 wie in Fig. 2 gezeigt, können oberhalb oder unterhalb der Photozellen 7 installiert werden. Die Träger und Heizvorrichtung 8 muss entsprechend ausgerichtet werden. Plasma source 5 and source material distribution systems 11, 12 as shown in Fig. 2 can be installed above or below the photocells 7. The carrier and heater 8 must be aligned accordingly.

Claims

Patentansprüche claims
1. Verfahren um einen anti-reflektierenden Siliziumnitridfilm auf, bei gleichzeitiger Wasserstoffatomdiffusion in, Siliziumwafer basierten Photozellen während eines chemischen Gasphasenabscheidungsprozesses zu erzeugen, wobei das Verfahren umfasst:A method of producing an anti-reflective silicon nitride film while hydrogen atomically diffusing into silicon wafer-based photocells during a chemical vapor deposition process, the method comprising:
einen geeigneten Vakuumbehälter für CVD-Prozesse die auf Siliziumwafer basierte Photozellen bei einer geeigneten erhöhten Temperatur enthalten wenigstens eine elektromagnetische Energiequelle um mindestens eine Plasmaentladung zu bilden, um radikalisierte oder energetisch angeregte Arten aus gasförmigem Ausgangsmaterial zu erzeugena suitable vacuum vessel for CVD processes, the silicon wafer based photocells at a suitable elevated temperature containing at least one electromagnetic energy source to form at least one plasma discharge to produce radicalized or energetically excited species of gaseous starting material
- ein erstes gasförmiges oder dampfförmiges Ausgangsmaterial, das nur Silizium, Wasserstoff, Stickstoff und Kohlenstoff enthält- A first gaseous or vaporous starting material containing only silicon, hydrogen, nitrogen and carbon
- ein zweites gasförmiges oder dampfförmiges Ausgangsmaterial, das nur Stickstoff und Wasserstoff enthält- A second gaseous or vaporous starting material containing only nitrogen and hydrogen
- ein drittes gasförmiges oder dampfförmiges Ausgangsmaterial, das nur Wasserstoff enthält.- A third gaseous or vaporous starting material containing only hydrogen.
2. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, dass das erste gasförmige oder dampfförmige Ausgangsmaterial eine sauerstofffreie Organosiliziumverbindung ist, vorzugsweise Hexamethyldisilazan, das die chemische Formel (CH3)3-Si-NH-Si-(CH3)3 hat.2. The method according to claim 1, characterized in that the first gaseous or vaporous starting material is an oxygen-free organosilicon compound, preferably hexamethyldisilazane, which has the chemical formula (CH 3 ) 3 -Si-NH-Si- (CH 3 ) 3 .
3. Verfahren nach Anspruch 1 oder Anspruch 2, dadurch gekennzeichnet, dass das zweite gasförmige oder dampfförmige Ausgangsmaterial Ammoniak ist, das die chemische Formel NH3 hat.3. The method according to claim 1 or claim 2, characterized in that the second gaseous or vaporous starting material is ammonia, which has the chemical formula NH 3 .
4. Verfahren nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, dass das dritte gasförmige oder dampfförmige Ausgangsmaterial molekularer Wasserstoff ist.4. The method according to any one of claims 1 to 3, characterized in that the third gaseous or vaporous starting material is molecular hydrogen.
5. Verfahren nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, dass die Energiequelle eine Mikrowellenenergiequelle ist, die vorzugsweise bei 915 MHz oder 2450 MHz arbeitet. 5. The method according to any one of claims 1 to 4, characterized in that the energy source is a microwave energy source, which operates preferably at 915 MHz or 2450 MHz.
6. Verfahren nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, dass die Energiequelle einen gepulsten Output erzeugen kann, bei welchem der Spitzenleistungspegel während der Pulse viel höher ist, verglichen zu einem Prozess bezogenen maximal akzeptierbaren Dauerstrichleistungspegel, wobei die Dauer der Puls-an Zeiten wesentlich kürzer ist, verglichen mit den entsprechenden Puls-aus Zeiten.A method according to any one of claims 1 to 5, characterized in that the power source can produce a pulsed output at which the peak power level during the pulses is much higher compared to a process-related maximum acceptable continuous power level, the duration of the pulse-on Times is significantly shorter compared to the corresponding pulse-off times.
7. Verfahren nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, dass der Arbeitsgasdruck innerhalb eines Bereiches zwischen 0.05 hPa und 1 hPa ist und bei welcher der Restgasdruck im Vakuumbehälter kleiner ist als 0.0001 hPa ist.7. The method according to any one of claims 1 to 6, characterized in that the working gas pressure within a range between 0.05 hPa and 1 hPa and wherein the residual gas pressure in the vacuum vessel is less than 0.0001 hPa.
8. Verfahren nach Anspruch 7, dadurch gekennzeichnet, dass das Plasma nicht in sichtbarem Kontakt ist mit der Oberfläche der auf Siliziumwafer basierten Photozellen steht.8. The method according to claim 7, characterized in that the plasma is not in visible contact with the surface of the silicon wafer based photocells.
9. Verfahren nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, dass die auf Siliziumwafer aufgebauten Photozellen im Vakuumbehälter während des Filmbildungsprozesses bewegt werden. 9. The method according to any one of claims 1 to 6, characterized in that the built-up on silicon wafer photocells are moved in the vacuum container during the film-forming process.
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109360866A (en) * 2018-09-25 2019-02-19 韩华新能源（启东）有限公司 A kind of preparation method of three layers of silicon nitride film
PL423097A1 (en) * 2017-10-09 2019-04-23 Politechnika Lodzka Method for producing one-layered optical filters with the light refractive index gradient

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2139025A1 (en) 2008-06-25 2009-12-30 Applied Materials, Inc. Arrangement for coating a cristalline silicon solar cell with an antireflection/passivation layer

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050255713A1 (en) * 2002-07-08 2005-11-17 Kohshi Taguchi Method and apparatus for forming nitrided silicon film
DE102004015217A1 (en) * 2004-03-23 2006-01-05 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Method for forming thin layers of silicon nitride on substrate surfaces

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4863755A (en) * 1987-10-16 1989-09-05 The Regents Of The University Of California Plasma enhanced chemical vapor deposition of thin films of silicon nitride from cyclic organosilicon nitrogen precursors
JP4119791B2 (en) * 2003-05-30 2008-07-16 サムコ株式会社 Method for producing carbon-containing silicon film using cathode coupling type plasma CVD apparatus
US7129187B2 (en) * 2004-07-14 2006-10-31 Tokyo Electron Limited Low-temperature plasma-enhanced chemical vapor deposition of silicon-nitrogen-containing films

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050255713A1 (en) * 2002-07-08 2005-11-17 Kohshi Taguchi Method and apparatus for forming nitrided silicon film
DE102004015217A1 (en) * 2004-03-23 2006-01-05 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Method for forming thin layers of silicon nitride on substrate surfaces

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
ABERLE A G: "Overview on SiN surface passivation of crystalline silicon solar cells" SOLAR ENERGY MATERIALS AND SOLAR CELLS, ELSEVIER SCIENCE PUBLISHERS, AMSTERDAM, NL, Bd. 65, Nr. 1-4, Januar 2001 (2001-01), Seiten 239-248, XP004217124 ISSN: 0927-0248 *
KRUGER ET AL: "Investigations of silicon nitride layers deposited in pulsed microwave generated ammonia-silane plasmas" SURFACE AND COATINGS TECHNOLOGY, ELSEVIER, AMSTERDAM, NL, Bd. 200, Nr. 1-4, 1. Oktober 2005 (2005-10-01), Seiten 639-643, XP005063592 ISSN: 0257-8972 *
MCCURDY PATRICK R ET AL: "Pulsed and continuous wave plasma deposition of amorphous, hydrogenated silicon carbide from SiH4/CH4 plasmas" JOURNAL OF VACUUM SCIENCE AND TECHNOLOGY A. VACUUM, SURFACES AND FILMS, AMERICAN INSTITUTE OF PHYSICS, NEW YORK, NY, US, Bd. 17, Nr. 5, September 1999 (1999-09), Seiten 2475-2484, XP012004735 ISSN: 0734-2101 *
SCHMIDT J ET AL: "SURFACE PASSIVATION OF SILICON SOLAR CELLS USING PLASMA-ENHANCED CHEMICAL-VAPOUR-DEPOSITED SIN FILMS AND THIN THERMAL SIO2/PLASMA SIN STACKS" SEMICONDUCTOR SCIENCE AND TECHNOLOGY, IOP, BRISTOL, GB, Bd. 16, Nr. 3, März 2001 (2001-03), Seiten 164-170, XP001030218 ISSN: 0268-1242 *

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PL423097A1 (en) * 2017-10-09 2019-04-23 Politechnika Lodzka Method for producing one-layered optical filters with the light refractive index gradient
CN109360866A (en) * 2018-09-25 2019-02-19 韩华新能源（启东）有限公司 A kind of preparation method of three layers of silicon nitride film
CN109360866B (en) * 2018-09-25 2021-07-20 韩华新能源（启东）有限公司 Preparation method of three-layer silicon nitride film

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