WO2010087613A2 - Method for manufacturing a cds/cdte thin film solar cell - Google Patents

Method for manufacturing a cds/cdte thin film solar cell Download PDF

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Publication number
WO2010087613A2
WO2010087613A2 PCT/KR2010/000490 KR2010000490W WO2010087613A2 WO 2010087613 A2 WO2010087613 A2 WO 2010087613A2 KR 2010000490 W KR2010000490 W KR 2010000490W WO 2010087613 A2 WO2010087613 A2 WO 2010087613A2
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Prior art keywords
thin film
cdte
cds
solar cell
sputtering chamber
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PCT/KR2010/000490
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French (fr)
Korean (ko)
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WO2010087613A3 (en
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이재근
이태석
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Lee Jae Geun
Lee Tae Seok
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Publication of WO2010087613A2 publication Critical patent/WO2010087613A2/en
Publication of WO2010087613A3 publication Critical patent/WO2010087613A3/en

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    • 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
    • H01L31/042—PV modules or arrays of single PV cells
    • H01L31/0445—PV modules or arrays of single PV cells including thin film solar cells, e.g. single thin film a-Si, CIS or CdTe 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 at least one potential-jump barrier or surface barrier
    • H01L31/072—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 at least one potential-jump barrier or surface barrier the potential barriers being only of the PN heterojunction type
    • H01L31/073—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 at least one potential-jump barrier or surface barrier the potential barriers being only of the PN heterojunction type comprising only AIIBVI compound semiconductors, e.g. CdS/CdTe 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
    • 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
    • H01L31/1828—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof the active layers comprising only AIIBVI compounds, e.g. CdS, ZnS, CdTe
    • H01L31/1836—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof the active layers comprising only AIIBVI compounds, e.g. CdS, ZnS, CdTe comprising a growth substrate not being an AIIBVI compound
    • 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
    • Y02E10/543—Solar cells from Group II-VI materials
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to a method for manufacturing a CdS / CdTe thin film solar cell, and more particularly, to a method for manufacturing a CdS / CdTe thin film solar cell using an inline, interbag or cluster system.
  • Silicon which is widely used as a solar cell material, has a problem of high manufacturing cost due to ingot growth and slicing process.
  • CdTe cadmium telluride
  • CGS copper indium gallium selenide
  • CdTe thin film solar cells for example, a chemical vapor deposition (CVD) method for forming a transparent conductive oxide (TCO) thin film and a closed space sublimation for forming a cadmium sulfide (CdS) thin film.
  • CVD chemical vapor deposition
  • CdS transparent conductive oxide
  • CdS closed space sublimation
  • CdTe cadmium sulfide
  • CdTe cadmium telluride
  • VTD vapor transport deposition
  • Techniques for forming CdS and CdTe thin films include CSS, VTD, thermal evaporation, e-beam deposition, and sputtering. Among them, only CSS and VTD have been successfully adopted to raise large area CdTe thin films.
  • CdS / CdTe thin film solar cells using these methods is that too many different techniques are required to form the necessary thin films. Therefore, this complicated production process leads to high manufacturing cost and low productivity.
  • the CSS and VTD methods used to form CdTe films require a relatively high process temperature (> 500 o C), which is more suitable for solar cells with higher visible light transmission than SnO 2 : F (fluorine-doped tin oxide). It can damage known TCO thin films such as aluminum-doped zinc oxide (ZnO: Al) or indium tin oxide (ITO).
  • an object of the present invention is to provide a CdS / CdTe thin film solar cell manufacturing method capable of improving productivity and manufacturing at a low process temperature according to the large area and high energy conversion efficiency.
  • a method of manufacturing a CdS / CdTe thin film solar cell in an in-line, inter-bag or cluster system comprises the steps of preparing a substrate, the transparent on the substrate in the first sputtering chamber Depositing a conductive oxide thin film, depositing a CdS thin film on said transparent conductive oxide thin film in a second sputtering chamber, depositing a CdTe thin film on said CdS thin film in a third sputtering chamber, and said heat treatment And treating the CdTe thin film with CdCl 2 in a chamber, wherein the third sputtering chamber is provided with a plurality of CdTe targets having a length greater than or equal to the length of the substrate, and the deposition of the CdTe thin film is performed by the plurality of CdTe targets. It provides deposition by sputtering generated by supplying a superimposed RF / DC power supply.
  • the deposition of the CdTe thin film is preferably deposited even during the transfer of the substrate.
  • the plurality of CdTe targets are preferably rotated during the process.
  • the CdS / CdTe thin film solar cell manufacturing method includes depositing a back contact thin film made of P-type zinc telluride, antimony telluride, or copper telluride on the CdTe thin film treated with CdCl 2 in a fourth sputtering chamber; And depositing a metal thin film made of molybdenum, gold, silver or nickel on the back contact thin film in the fifth sputtering chamber.
  • Each of the sputtering chambers is preferably provided with an unbalanced magnetron for non-equilibrium magnetic flux.
  • the transparent conductive oxide thin film, the CdS thin film, the back contact thin film and the metal thin film may be deposited using sputtering generated by supplying RF / DC power superimposed on each target of each sputtering chamber.
  • the overlapped RF / DC power supply is preferably supplied to the target through a matching box.
  • the present invention by manufacturing a CdS / CdTe thin film solar cell by supplying RF / DC power superimposed on the CdTe target in the in-line, inter-bag or cluster system, it is possible to reduce the manufacturing cost by improving the productivity according to the large area, In addition, the process temperature is low, it is possible to prevent degradation during manufacturing.
  • the present invention by providing a plurality of CdTe target having a length greater than or equal to the longitudinal length of the substrate in the lower portion of the substrate, it is possible to significantly reduce the time of the CdTe thin film process to improve the productivity of the entire manufacturing process, even at low A thin film can be obtained and the energy conversion efficiency can be improved.
  • the non-equilibrium magnetron method by applying the non-equilibrium magnetron method, it is possible to obtain very dense and low internal stress thin films by improving the plasma during sputtering to increase the ion current density.
  • the deposition of the thickest CdTe thin film by using a plurality of targets it is possible to significantly reduce the time of the CdTe thin film process to improve the productivity of the entire manufacturing process.
  • FIG. 1 is a view showing a Cds / CdTe thin film solar cell manufactured according to an embodiment of the present invention.
  • FIG. 2 is a view illustrating an inline magnetron sputtering system used for a method of manufacturing a CdS / CdTe thin film solar cell according to an embodiment of the present invention.
  • FIG. 3 is a view showing an inter-bag magnetron sputtering system used for the CdS / CdTe thin film solar cell manufacturing method according to an embodiment of the present invention
  • FIG. 4 is a diagram illustrating a cluster magnetron sputtering system used for a method for manufacturing a CdS / CdTe thin film solar cell according to an embodiment of the present invention.
  • FIG. 5 is a flowchart illustrating a method of manufacturing a CdS / CdTe thin film solar cell according to an embodiment of the present invention.
  • FIG. 6 is a diagram illustrating an example of a CdTe sputtering chamber according to an embodiment of the present invention.
  • FIG. 7 illustrates an RF / DC power supply unbalanced magnetron sputtering chamber used for a method of manufacturing a CdS / CdTe thin film solar cell according to an embodiment of the present invention.
  • FIG. 8 illustrates a scanning electron microscope (SEM) photograph of a cross section of a TCO, CdS, and CdTe thin film formed of an RF / DC non-equilibrium magnetron sputtering apparatus according to an embodiment of the present invention.
  • SEM scanning electron microscope
  • FIG. 9 is a diagram illustrating a scanning electron microscope (SEM) photograph of cross sections of TCO, CdS, and CdTe thin films after CdCl 2 heat treatment.
  • FIG. 10 is a view showing the electrical characteristics of the CdS / CdTe thin film solar cell manufactured according to an embodiment of the present invention.
  • FIG. 1 is a view showing a CdS / CdTe thin film solar cell manufactured according to an embodiment of the present invention.
  • the CdS / CdTe thin film solar cell 100 manufactured according to an embodiment of the present invention is formed on the transparent conductive oxide (TCO) thin film layer 120 and the TCO thin film layer 120 sequentially formed on the transparent substrate 110.
  • TCO transparent conductive oxide
  • the CdTe thin film layer 150 used as a type, the Te thin film layer 160 deposited on the CdTe thin film layer 150, and the back electrode thin film layer 170 deposited on the Te thin film layer 160 are formed.
  • the substrate 110 may be soda lime glass (SLG).
  • SLG soda lime glass
  • the TCO thin film layer 120 may be formed of fluorine-doped tin oxide (SnO 2: F), aluminum-doped zinc oxide (ZnO: Al), or indium tin oxide (ITO) having low resistance and high transparency in visible light. Indium Tin Oxide).
  • the high resistance thin film layer 130 is preferably an oxide layer made of tin oxide (SnO 2 ), zinc oxide (ZnO), indium oxide (In 2 O 3 ), or the like.
  • the back electrode thin film layer 170 is a back contact thin film layer 172 and back contact made of P-type zinc telluride (p-ZnTe), antimony telluride (Sb 2 Te 3 ), or copper telluride (Cu 1.4 Te).
  • a metal thin film layer 174 such as molybdenum (Mo), gold (Au), silver (Ag), or nickel (Ni), is deposited on the thin film layer 172.
  • back contact thin film layer 172 is deposited for ohmic contact, and metal thin film layer 174 is deposited to impart low area resistance to back contact thin film layer 172.
  • FIG. 2 is a view illustrating an inline magnetron sputtering system used for a method of manufacturing a CdS / CdTe thin film solar cell according to an embodiment of the present invention
  • FIG. 3 is a CdS / CdTe thin film solar cell according to an embodiment of the present invention.
  • FIG. 4 is a diagram illustrating an interbag magnetron sputtering system used for a manufacturing method
  • FIG. 4 is a diagram illustrating a cluster magnetron sputtering system used for a CdS / CdTe thin film solar cell manufacturing method according to an embodiment of the present invention.
  • This inline, interbag or cluster magnetron sputtering system 200 includes a load lock / buffer chamber 210, process chambers 220, and an unload lock / buffer chamber 230.
  • the process chambers 220 may include a first sputtering chamber 221 for depositing a TCO thin film layer 120 on a substrate and a material for depositing a high resistance thin film layer 130 on the TCO thin film layer 120.
  • the manufacture of the CdS / CdTe thin film solar cell according to an embodiment of the present invention is the sputtering chambers 221, 222, 223, 224, 226, 227, 228 of FIG. 2, 3, or 4 and the heat treatment chamber ( It is made sequentially in the process chambers 220 consisting of 225.
  • FIG. 3 is a flowchart illustrating a method of manufacturing a CdS / CdTe thin film solar cell according to an embodiment of the present invention.
  • a substrate is prepared to manufacture a CdS / CdTe thin film solar cell according to the present invention (S302). That is, the substrate 110 is provided to the load lock / buffer chamber 210 of the magnetron sputtering system 200 of FIGS. 2, 3, or 4.
  • the TCO thin film layer 120 is preferably formed of SnO 2: F, ZnO: Al, or Indium Tin Oxide (ITO) having low resistance and high transparency in visible light.
  • the thickness of the TCO thin film layer 120 is preferably 500 to 1000 nm, and the process temperature is preferably 200 to 300 ° C.
  • the second sputtering chamber 222 is a high resistance thin film layer on the TCO thin film layer 120 by magnetron sputtering. 130 is deposited (S306).
  • the high resistance thin film layer 130 tin oxide (SnO 2 ), zinc oxide (ZnO), indium oxide (In 2 O 3 ), or the like is used.
  • the thickness of the high resistance thin film layer 130 is preferably 30 to 150 nm, and the process temperature is preferably 200 to 300 ° C.
  • the high resistance thin film layer 130 may be omitted if it does not affect the efficiency of the CdS / CdTe thin film solar cell.
  • the third sputtering chamber 223 is a CdS thin film on the high resistance thin film layer 130 by magnetron sputtering.
  • the layer 140 is deposited (S308).
  • the thickness of the CdS thin film layer 140 is preferably 50 ⁇ 200nm
  • the process temperature is preferably 100 ⁇ 300 ° C.
  • the fourth sputtering chamber 223 is formed on the CdTe thin film layer 140 on the CdS thin film layer 140 by magnetron sputtering.
  • 150 is deposited (S310).
  • the thickness of the CdTe thin film layer 150 is preferably 2 to 4, and a process temperature of 200 to 300 ° C. is preferable.
  • the heat treatment chamber 225 exposes the CdTe thin film layer 150 to CdCl 2 vapor (S312).
  • the CdCl 2 vapor may include oxygen
  • the process temperature is preferably 380 ⁇ 420 ° C
  • the time is preferably 20 to 40 minutes.
  • the heat treatment chamber may be maintained at a high temperature for several minutes in a vacuum state.
  • the fifth sputtering chamber 226 is the CdTe thin film layer 150 by magnetron sputtering.
  • Te thin film layer 160 is deposited on (S314).
  • the thickness of the Te thin film layer 160 is preferably 20 to 50 nm, and the process temperature is preferably 150 to 300 ° C.
  • the Te thin film layer is formed by a wet etching process, while in the present invention, by using the same sputtering method used to form another thin film, the process can be simplified and productivity can be increased.
  • the Te thin film layer 160 may be omitted if it does not affect the efficiency of the CdS / CdTe thin film solar cell.
  • the sixth sputtering chamber 223 is formed on the Te thin film layer 160 by magnetron sputtering.
  • the layer 172 is deposited (S316). That is, p-ZnTe, Sb 2 Te 3 , or Cu 1.4 Te thin film is formed on the Te thin film layer 160 with a thickness of 50 to 100 nm at a process temperature of 150 to 300 ° C.
  • the seventh sputtering chamber 223 imparts a low area resistance to the back contact thin film layer 172.
  • the metal thin film layer 174 is deposited on the back contact thin film layer 172 by magnetron sputtering (S318).
  • the thickness of the metal thin film layer 174 is preferably 200 to 500 nm, and the process temperature is preferably room temperature.
  • the present invention can increase productivity by applying only one magnetron sputtering technique in an in-line, inter-bag or cluster system to all processes except heat treatment, and lower processes. Dense thin films can be obtained at temperature.
  • FIG. 6 is a diagram illustrating an example of a CdTe sputtering chamber according to an embodiment of the present invention.
  • the CdTe sputtering chamber 400 has four CdTe targets 410 to form a thick CdTe thin film layer 150. That is, a plurality of CdTe targets 410 are provided in the CdTe sputtering chamber 400 which deposits the thickest CdTe thin film layer 150 compared to other thin film layers. Therefore, when the CdTe sputtering chamber 400 deposits the CdTe thin film layer 150 on the CdS thin film layer 140, the deposition rate may be increased by N times, thereby significantly reducing the CdTe thin film process time, thereby improving productivity.
  • the plurality of CdTe target 410 is preferably rotated during the process in order to maximize the material use ratio.
  • the CdTe sputtering chamber 400 improves productivity by depositing the CdTe thin film layer 150 even when the substrate 110 formed up to the CdS thin film layer 140 is transferred in the CdTe sputtering chamber 400. have.
  • the CdTe target 410 used in the CdTe sputtering chamber 400 is composed of a bar target.
  • the plurality of CdTe targets 410 preferably have a length greater than or equal to the length of the substrate 110 at the bottom or the side of the substrate 110. If a plurality of CdTe targets are provided on the substrate 110 as in the prior art, impurities may also be deposited on the CdTe thin film layer during sputtering, thereby obtaining a dense thin film structure.
  • the bar target includes the TCO thin film layer 120, the high resistance thin film layer 130, the CdS thin film layer 140, the CdTe thin film layer 150, the Te thin film layer 160, and the rear electrode thin film layer 170.
  • the bar target preferably has a length greater than or equal to the longitudinal length of the substrate 110 so as to obtain uniform thin films of high efficiency suitable for a large area.
  • a planar target may be used instead of a bar target.
  • FIG. 7 illustrates an RF / DC power supply unbalanced magnetron sputtering chamber used for a method of manufacturing a CdS / CdTe thin film solar cell according to an embodiment of the present invention.
  • the inventors of the present invention confirmed that it is possible to maintain a relatively low deposition temperature and high deposition rate by supplying the magnetron by superimposing the RF power supply and the DC power supply to the magnetron instead of using only one of the RF power source and the DC power source when depositing the thin film layers.
  • the DC power supply also includes a pulsed DC power supply.
  • This RF / DC power source superimposition improves grain growth by impinging appropriate ions on the substrate while maintaining a relatively high deposition rate during thin film growth.
  • the present inventors confirmed that by applying an unbalanced magnetron method that generates non-balance magnetic flux rather than a general magnetron method, more target ions can reach the substrate to obtain a dense thin film and better adhesion. It was.
  • the present invention was able to obtain a very dense, low internal stress non-columnar thin film structure by increasing the ion current density by improving the plasma during sputtering using a non-balanced magnetron method.
  • the sputtering chamber 500 applied to the present invention is opposed to the substrate 110 supported by the substrate holder 520 which is fixedly disposed or movable in the vacuum chamber 510.
  • the cathode 530 is provided.
  • the back of the substrate holder 520 is provided with heating means (not shown) such as a heater for controlling the temperature of the substrate 110.
  • the target 532 is fixed to the substrate side of the cathode 530, and the magnetic circuit 540 is provided on the rear surface of the cathode 530.
  • the magnetic circuit 540 includes a permanent magnet 542 for generating a magnetic field and a base 544 supporting the permanent magnet 542.
  • This permanent magnet 542 is for generating an unbalanced magnetic field in magnetron sputtering, and the magnetic field strengths of the N pole and the S pole are different.
  • the discharge power supply unit 560 supplied to the cathode 530 includes a DC power supply 552 for applying a DC electric field and an RF power supply 554 for applying a high frequency electric field so as to overlap the DC electric field. .
  • the superimposed DC power supply 552 and the RF power supply 554 supply a voltage to the cathode 530 through the matching box 560. Meanwhile, an RF filter 562 is interposed between the DC power supply 552 and the matching box 560 to prevent the high frequency electric field from flowing into the DC power supply 552.
  • the DC power supply 552 is supplied with a power supply of 350 V or less, preferably a pulsed DC power supply having a pulse waveform.
  • the frequency of the pulse waveform is 5 to 350 KHz.
  • the frequency of the RF power supply 554 is 4MHz to 40MHz.
  • the superimposed DC power supply 552 and the RF power supply 554 are supplied to the cathode 530.
  • the superimposed DC power supply 552 and the RF power supply 554 are used to generate a plasma.
  • the configuration that can be supplied is called a magnetron in a broad sense.
  • the RF / (RF + (RF +) is preferable for manufacturing a CdS / CdTe thin film solar cell.
  • DC power ratio ranges from 20% to 50%.
  • the present invention provides a simpler and more economical TCO thin film layer using magnetron sputtering techniques in inline, interback or cluster systems, in particular RF / DC unbalanced magnetron sputtering techniques in inline, interbag or cluster systems.
  • 120, high resistance thin film layer 130, CdS thin film layer 140, CdTe thin film layer 150, Te thin film layer 160 and the back electrode thin film layer 170 can be deposited sequentially and the size of equipment This enables the production of solar cells with an area of 2200x2600 mm 2 or more, which is equivalent to the size of 8.5-generation large TFT-LCD panels.
  • the magnetron sputtering process in this in-line, interbag or cluster system allows the solar cell to be completed in less than two hours and is much lower than conventional CSS and VTD process temperatures (> 500 o C) for all processes except heat treatment.
  • process temperatures ⁇ 300 o C ensures the chemical purity and stability of the material of each thin film, leading to an increase in productivity.
  • RF / DC unbalanced magnetron sputtering technology in inline, interbag, or clusters provides greater than 10% thickness variation across the entire sputtering area, less than 5% temperature variation, and high target material utilization of 70% or more when using rotary sputtering targets. You can get it. All the advantages of this inline, interbag or clustered RF / DC unbalanced magnetron sputtering process can result in 10 to 12% energy conversion efficiencies in the production line.
  • FIG. 8 shows a scanning electron microscope (SEM) photograph of a cross section of TCO, CdS, and CdTe thin films deposited with an RF / DC non-equilibrium magnetron sputtering apparatus according to an embodiment of the present invention.
  • the TCO thin film layer 120 is about 300 nm
  • the CdS thin film layer 140 is about 180 nm
  • the CdTe thin film layer 150 is deposited to a thickness of about 2.4, and the boundaries of each thin film are very clear. It can be seen that the thickness is uniform.
  • FIG. 9 is a diagram illustrating a scanning electron microscope (SEM) photograph of cross sections of TCO, CdS, and CdTe thin films after CdCl 2 heat treatment.
  • this heat treatment process causes the CdTe grains to grow from sub-micrometers to micrometers in size and at the same time passivation of the crystal interface. As a result, the electrical characteristics of the CdS / CdTe thin film solar cell are improved.
  • FIG. 10 is a view showing the electrical characteristics of the CdS / CdTe thin film solar cell manufactured according to an embodiment of the present invention.
  • the average open circuit voltage (Voc) of the CdS / CdTe thin film solar cell according to the present invention is 750 ⁇ 850mV, short circuit current (Isc) 20 ⁇ 23mA, Fill Factor (FF) 62 ⁇ 74%, efficiency 10 ⁇ 13%. This is 1-5% higher efficiency than 8-9% efficiency of large-area CdTe thin film solar cells produced using existing VDT or CSS.
  • the present invention is to improve the productivity according to the large area to reduce the manufacturing cost and to prevent degradation during manufacturing at low process temperature to obtain high efficiency of the solar cell, CdS / CdTe thin film solar cell manufacturing method using an in-line, inter-bag or cluster system And CdS / CdTe thin film solar cells produced by the method.

Abstract

The present invention relates to a method for manufacturing a CdS/CdTe thin film solar cell in an in-line, interback, or cluster system, comprising the steps of: providing a substrate; depositing a transparent conductive oxide thin film on the substrate in a first sputtering chamber; depositing a CdS thin film on the transparent conductive oxide thin film in a second sputtering chamber; depositing a CdTe thin film on the CdS thin film in a third sputtering chamber; and treating the CdTe thin film with CdCl2 in a heat treatment chamber. The third sputtering chamber is provided with a plurality of CdTe targets having lengths longer than the vertical length of the substrate and arranged beneath the substrate. The deposition of the CdTe thin film is performed through sputtering for supplying overlapped RF/DC power to the plurality of CdTe targets. Thus, the method of the present invention improves the productivity of large area CdS/CdTe thin film solar cells, and can be used to obtain a dense thin film at a low processing temperature.

Description

ＣｄＳ／ＣｄＴｅ 박막 태양전지 제조 방법CDS / CDT thin film solar cell manufacturing method
본 발명은 CdS/CdTe 박막 태양전지 제조 방법에 관한 것으로, 특히 인라인, 인터백 또는 클러스터 시스템을 이용한 CdS/CdTe 박막 태양전지 제조 방법에 관한 것이다.The present invention relates to a method for manufacturing a CdS / CdTe thin film solar cell, and more particularly, to a method for manufacturing a CdS / CdTe thin film solar cell using an inline, interbag or cluster system.
태양광으로부터 직접 에너지를 얻어낼 수 있는 태양전지기술은 화석 연료 사용을 대체할 수 있는 유망한 기술이 되었다. 태양전지재료로 가장 널리 사용되고 있는 실리콘은 잉곳 성장과 슬라이싱 공정에 기인한 높은 제조단가가 문제시되고 있다. Solar cell technology, which can harvest energy directly from sunlight, has become a promising alternative to fossil fuel use. Silicon, which is widely used as a solar cell material, has a problem of high manufacturing cost due to ingot growth and slicing process.
태양전지를 생산하기 위해 사용되는 다른 재료로는 CdTe(cadmium telluride)와 CIGS(copper indium gallium selenide) 등이 있다. 이들 재료들은 박막 형태로 사용되고 제조 단가가 상대적으로 낮은 장점이 있을 뿐만 아니라 비교적 높은 에너지 변환 효율을 얻을 수 있기 때문에, 이들 재료들은 차세대 태양전지 기술개발에 매우 중요한 자리를 차지하게 되었다.Other materials used to produce solar cells include cadmium telluride (CdTe) and copper indium gallium selenide (CIGS). Since these materials are used in the form of thin films and have a relatively low manufacturing cost, they can achieve a relatively high energy conversion efficiency, and thus these materials have become very important for the development of next generation solar cell technology.
한편, CdTe 박막 태양전지를 생산하기 위해 여러 가지 기술이 시도되어 왔는데 예를 들면 TCO(transparent conductive oxide) 박막 형성에는 CVD(chemical vapor deposition) 방법, CdS(cadmium sulfide) 박막 형성에는 CSS(closed space sublimation) 또는 CBD(chemical bath deposition) 방법, CdTe(cadmium telluride) 박막 형성에는 CSS 또는 VTD(vapor transport deposition) 방법, 그리고 후면 전극(back contact)형성에는 스퍼터링(sputtering) 이나 스크린 프린팅(screen printing) 방법이 사용되고 있다. CdS와 CdTe박막을 형성하기 위한 기술로는 CSS, VTD, 열 증착(thermal evaporation), e-beam 증착, 스퍼터링 등이 사용되었고 이중 CSS와 VTD 만이 대면적 CdTe 박막을 올리는데 성공적으로 채택되었다.On the other hand, various techniques have been tried to produce CdTe thin film solar cells, for example, a chemical vapor deposition (CVD) method for forming a transparent conductive oxide (TCO) thin film and a closed space sublimation for forming a cadmium sulfide (CdS) thin film. ) Or chemical bath deposition (CBD) methods, CSS or vapor transport deposition (VTD) methods for CdTe (cadmium telluride) thin film formation, and sputtering or screen printing for back contact formation. It is used. Techniques for forming CdS and CdTe thin films include CSS, VTD, thermal evaporation, e-beam deposition, and sputtering. Among them, only CSS and VTD have been successfully adopted to raise large area CdTe thin films.
이러한 방법들을 이용하여 CdS/CdTe 박막 태양전지를 생산하는 경우의 문제점은 필요한 박막들을 형성하는데 있어서 너무 많은 다른 기술들이 요구된다는 것이다. 따라서 이러한 복잡한 생산과정은 높은 제조단가와 낮은 생산성을 가져오게 된다. 또한 CdTe 막을 형성하기 위해 사용되는 CSS와 VTD 방법은 비교적 높은 공정 온도(>500oC)를 필요로 하는데 이는 SnO2:F (fluorine-doped tin oxide)보다 높은 가시광 투과율로 태양전지에 더 적합한 것으로 알려진 ZnO:Al(aluminum-doped zinc oxide)나 ITO(indium tin oxide)등의 TCO 박막에 손상을 줄 수 있다.The problem with producing CdS / CdTe thin film solar cells using these methods is that too many different techniques are required to form the necessary thin films. Therefore, this complicated production process leads to high manufacturing cost and low productivity. In addition, the CSS and VTD methods used to form CdTe films require a relatively high process temperature (> 500 o C), which is more suitable for solar cells with higher visible light transmission than SnO 2 : F (fluorine-doped tin oxide). It can damage known TCO thin films such as aluminum-doped zinc oxide (ZnO: Al) or indium tin oxide (ITO).
상술한 문제점을 해결하기 위해, 본 발명은 대면적화에 따른 생산성 향상 및 낮은 공정온도에서의 제조가 가능하고 에너지 변환 효율이 높은 CdS/CdTe 박막 태양전지 제조 방법을 제공하는 것을 목적으로 한다. In order to solve the above problems, an object of the present invention is to provide a CdS / CdTe thin film solar cell manufacturing method capable of improving productivity and manufacturing at a low process temperature according to the large area and high energy conversion efficiency.
상술한 목적을 달성하기 위해, 본 발명에 따른 인라인, 인터백 또는 클러스터 시스템에서의 CdS/CdTe 박막 태양전지를 제조하는 방법은, 기판을 준비하는 단계와, 제1 스퍼터링 챔버에서 상기 기판 상에 투명 도전 산화 박막을 증착하는 단계와, 제2 스퍼터링 챔버에서 상기 투명 도전 산화 박막 상에 CdS 박막을 증착하는 단계와, 제3 스퍼터링 챔버에서 상기 CdS 박막 상에 CdTe 박막을 증착하는 단계와, 및 상기 열처리 챔버에서 상기 CdTe 박막을 CdCl2로 처리하는 단계를 포함하고, 상기 제3 스퍼터링 챔버에는 상기 기판의 세로길이 이상의 길이를 갖는 복수의 CdTe 타켓이 구비되며, 상기 CdTe 박막의 증착은 상기 복수의 CdTe 타켓에 중첩된 RF/DC 전원을 공급하여 발생하는 스퍼터링을 이용하여 증착하는 것을 제공한다.In order to achieve the above object, a method of manufacturing a CdS / CdTe thin film solar cell in an in-line, inter-bag or cluster system according to the present invention comprises the steps of preparing a substrate, the transparent on the substrate in the first sputtering chamber Depositing a conductive oxide thin film, depositing a CdS thin film on said transparent conductive oxide thin film in a second sputtering chamber, depositing a CdTe thin film on said CdS thin film in a third sputtering chamber, and said heat treatment And treating the CdTe thin film with CdCl 2 in a chamber, wherein the third sputtering chamber is provided with a plurality of CdTe targets having a length greater than or equal to the length of the substrate, and the deposition of the CdTe thin film is performed by the plurality of CdTe targets. It provides deposition by sputtering generated by supplying a superimposed RF / DC power supply.
상기 CdTe 박막의 증착은 상기 기판의 이송 중에도 증착되는 것이 바람직하다.The deposition of the CdTe thin film is preferably deposited even during the transfer of the substrate.
상기 복수의 CdTe 타켓은 공정 진행 중에 회전하는 것이 바람직하다. The plurality of CdTe targets are preferably rotated during the process.
상기 CdS/CdTe 박막 태양전지 제조 방법은 제4 스퍼터링 챔버에서 상기 CdCl2로 처리된 상기 CdTe 박막 상에 P형 텔루르화 아연, 텔루르화 안티몬, 또는 텔루르화 구리로 이루어지는 후면 접촉 박막을 증착하는 단계와, 및 제5 스퍼터링 챔버에서 상기 후면 접촉 박막 상에 몰리브덴, 금, 은 또는 니켈로 이루어지는 금속 박막을 증착하는 단계를 더 포함하는 것이 바람직하다.The CdS / CdTe thin film solar cell manufacturing method includes depositing a back contact thin film made of P-type zinc telluride, antimony telluride, or copper telluride on the CdTe thin film treated with CdCl 2 in a fourth sputtering chamber; And depositing a metal thin film made of molybdenum, gold, silver or nickel on the back contact thin film in the fifth sputtering chamber.
상기 각 스퍼터링 챔버에는 자속을 비평형하게 발생하는 비평형 마그네트론이 구비되는 것이 바람직하다.Each of the sputtering chambers is preferably provided with an unbalanced magnetron for non-equilibrium magnetic flux.
상기 투명 도전 산화 박막, 상기 CdS 박막, 상기 후면 접촉 박막 및 상기 금속 박막의 증착은 상기 각 스퍼터링 챔버의 각 타켓에 중첩된 RF/DC 전원을 공급하여 발생하는 스퍼터링을 이용하여 증착될 수 있다.The transparent conductive oxide thin film, the CdS thin film, the back contact thin film and the metal thin film may be deposited using sputtering generated by supplying RF / DC power superimposed on each target of each sputtering chamber.
상기 중첩된 RF/DC 전원은 매칭 박스를 통해 상기 타켓에 공급되는 것이 바람직하다.The overlapped RF / DC power supply is preferably supplied to the target through a matching box.
본 발명에 의하면, 인라인, 인터백 또는 클러스터 시스템에서의 CdTe 타켓에 중첩된 RF/DC 전원을 공급하여 CdS/CdTe 박막 태양전지를 제조함으로써, 대면적화에 따른 생산성을 향상시켜 제조원가를 줄일 수 있으며, 또한 공정온도가 낮아 제조시의 열화를 방지할 수 있다.According to the present invention, by manufacturing a CdS / CdTe thin film solar cell by supplying RF / DC power superimposed on the CdTe target in the in-line, inter-bag or cluster system, it is possible to reduce the manufacturing cost by improving the productivity according to the large area, In addition, the process temperature is low, it is possible to prevent degradation during manufacturing.
또한, 본 발명에 의하면, 기판의 하부에 기판의 세로길이 이상의 길이를 갖는 복수의 CdTe 타켓을 구비함으로써, CdTe 박막 공정의 시간을 현격히 줄여 전체 제조 공정의 생산성을 향상시킬 수 있으며, 낮은 공정에서도 치밀한 박막을 얻어 에너지 변환 효율을 높일 수 있다.In addition, according to the present invention, by providing a plurality of CdTe target having a length greater than or equal to the longitudinal length of the substrate in the lower portion of the substrate, it is possible to significantly reduce the time of the CdTe thin film process to improve the productivity of the entire manufacturing process, even at low A thin film can be obtained and the energy conversion efficiency can be improved.
또한, 본 발명에 의하면, 기판의 세로길이 이상의 길이를 갖는 막대형 타켓을 이용함으로써, 대면적에 적합한 고효율의 태양전지 박막들을 얻을 수 있다. In addition, according to the present invention, by using a rod-shaped target having a length greater than or equal to the length of the substrate, high efficiency solar cell thin films suitable for a large area can be obtained.
또한, 본 발명에 의하면, 비평형 마그네트론 방식을 적용함으로써, 스퍼터링시 플라즈마를 향상시켜 이온 전류 밀도를 증가시킴으로써 아주 치밀하고 내부 스트레스가 적은 박막들을 얻을 수 있다.In addition, according to the present invention, by applying the non-equilibrium magnetron method, it is possible to obtain very dense and low internal stress thin films by improving the plasma during sputtering to increase the ion current density.
또한, 본 발명에 의하면, 가장 두꺼운 CdTe 박막의 증착은 복수의 타켓을 이용함으로써, CdTe 박막 공정의 시간을 현격히 줄여 전체 제조 공정의 생산성을 향상시킬 수 있다.In addition, according to the present invention, the deposition of the thickest CdTe thin film by using a plurality of targets, it is possible to significantly reduce the time of the CdTe thin film process to improve the productivity of the entire manufacturing process.
도 1은 본 발명의 일실시예 따라 제조된 Cds/CdTe 박막 태양전지를 도시한 도면이다.1 is a view showing a Cds / CdTe thin film solar cell manufactured according to an embodiment of the present invention.
도 2는 본 발명의 일실시예에 따른 CdS/CdTe 박막 태양전지 제조방법을 위해 사용되는 인라인 마그네트론 스퍼터링 시스템을 도시한 도면이다.2 is a view illustrating an inline magnetron sputtering system used for a method of manufacturing a CdS / CdTe thin film solar cell according to an embodiment of the present invention.
도 3는 본 발명의 일실시예에 따른 CdS/CdTe 박막 태양전지 제조방법을 위해 사용되는 인터백 마그네트론 스퍼터링 시스템을 도시한 도면이고3 is a view showing an inter-bag magnetron sputtering system used for the CdS / CdTe thin film solar cell manufacturing method according to an embodiment of the present invention;
도 4는 본 발명의 일실시예에 따른 CdS/CdTe 박막 태양전지 제조방법을 위해 사용되는 클러스터 마그네트론 스퍼터링 시스템을 도시한 도면이다.4 is a diagram illustrating a cluster magnetron sputtering system used for a method for manufacturing a CdS / CdTe thin film solar cell according to an embodiment of the present invention.
도 5는 본 발명의 일실시예에 따른 CdS/CdTe 박막 태양전지를 제조하는 방법을 흐름도로 도시한 도면이다.5 is a flowchart illustrating a method of manufacturing a CdS / CdTe thin film solar cell according to an embodiment of the present invention.
도 6는 본 발명의 일실시예에 따른 CdTe 스퍼터링 챔버의 예를 도시한 도면이다.6 is a diagram illustrating an example of a CdTe sputtering chamber according to an embodiment of the present invention.
도 7는 본 발명의 일실시예에 따른 CdS/CdTe 박막 태양전지 제조방법을 위해 사용되는 RF/DC 전원 비평형 마그네트론 스퍼터링 챔버를 도시한 도면이다.FIG. 7 illustrates an RF / DC power supply unbalanced magnetron sputtering chamber used for a method of manufacturing a CdS / CdTe thin film solar cell according to an embodiment of the present invention.
도 8은 본 발명의 일실시예에 따른 RF/DC 비평형 마그네트론 스퍼터링 장비로 형성된 TCO, CdS, CdTe 박막 단면의 SEM(scanning electron microscope) 사진을 도시한다.FIG. 8 illustrates a scanning electron microscope (SEM) photograph of a cross section of a TCO, CdS, and CdTe thin film formed of an RF / DC non-equilibrium magnetron sputtering apparatus according to an embodiment of the present invention.
도 9은 CdCl2 열처리 후의 TCO, CdS, CdTe 박막 단면의 SEM(scanning electron microscope) 사진을 도시한 도면이다. FIG. 9 is a diagram illustrating a scanning electron microscope (SEM) photograph of cross sections of TCO, CdS, and CdTe thin films after CdCl 2 heat treatment.
도 10은 본 발명의 일실시예에 따라 제조된 CdS/CdTe 박막 태양전지의 전기적 특성을 도시한 도면이다. 10 is a view showing the electrical characteristics of the CdS / CdTe thin film solar cell manufactured according to an embodiment of the present invention.
이하, 본 발명의 일실시예에 따른 CdS/CdTe 박막 태양전지 제조 방법을 첨부한 예시 도면에 의거하여 상세히 설명한다.Hereinafter, a CdS / CdTe thin film solar cell manufacturing method according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.
도 1은 본 발명의 일실시예에 따라 제조된 CdS/CdTe 박막 태양전지를 도시한 도면이다.1 is a view showing a CdS / CdTe thin film solar cell manufactured according to an embodiment of the present invention.
본 발명의 일실시예에 따라 제조된 CdS/CdTe 박막 태양전지(100)은 투명 기판(110) 상에 순차적으로 형성된 투명 도전 산화(TCO) 박막 층(120), TCO 박막 층(120) 상에 증착된 고저항(HR : High Resistivity) 박막 층(130), 고저항 박막 층(130) 상에 증착되어 N 형으로 이용되는 CdS 박막 층(140), CdS 박막 층(140) 상에 증착되어 P 형으로 이용되는 CdTe 박막 층(150), CdTe 박막 층(150) 상에 증착된 Te 박막 층(160), Te 박막 층(160) 상에 증착된 후면 전극 박막 층(170)으로 이루어져 있다.The CdS / CdTe thin film solar cell 100 manufactured according to an embodiment of the present invention is formed on the transparent conductive oxide (TCO) thin film layer 120 and the TCO thin film layer 120 sequentially formed on the transparent substrate 110. Deposited on the high resistivity (HR) thin film layer (130), the high resistivity thin film layer (130), the CdS thin film layer (140) and the CdS thin film layer (140) used as N-type, The CdTe thin film layer 150 used as a type, the Te thin film layer 160 deposited on the CdTe thin film layer 150, and the back electrode thin film layer 170 deposited on the Te thin film layer 160 are formed.
여기서 기판(110)은 SLG(soda lime glass)일 수 있다.The substrate 110 may be soda lime glass (SLG).
그리고 TCO 박막 층(120)은 낮은 저항성과 가시광선에서의 높은 투명성을 갖는 불소가 도핑된 산화 주석(SnO2:F)나 알루미늄이 도핑된 산화 아연(ZnO:Al)이나 인듐 주석 산화물(ITO : Indium Tin Oxide)로 형성된다. The TCO thin film layer 120 may be formed of fluorine-doped tin oxide (SnO 2: F), aluminum-doped zinc oxide (ZnO: Al), or indium tin oxide (ITO) having low resistance and high transparency in visible light. Indium Tin Oxide).
고저항 박막 층(130)은 산화 주석(SnO2), 산화 아연(ZnO), 산화 인듐(In2O3) 등으로 이루어진 산화 층이 바람직하다.The high resistance thin film layer 130 is preferably an oxide layer made of tin oxide (SnO 2 ), zinc oxide (ZnO), indium oxide (In 2 O 3 ), or the like.
후면 전극 박막 층(170)은 P형 텔루르화 아연(p-ZnTe), 텔루르화 안티몬(Sb2Te3), 또는 텔루르화 구리(Cu1.4Te)로 이루어지는 후면 접촉 박막 층(172) 및 후면 접촉 박막 층(172) 상에 증착된 몰리브덴(Mo), 금(Au), 은(Ag) 또는 니켈(Ni) 등의 금속 박막 층(174)으로 이루어진다. 이 경우 후면 접촉 박막 층(172)은 저장 접촉(ohmic contact)을 위해 증착되며, 금속 박막 층(174)은 후면 접촉 박막 층(172)에 저면적 저항을 부여하기 위해 증착된다. The back electrode thin film layer 170 is a back contact thin film layer 172 and back contact made of P-type zinc telluride (p-ZnTe), antimony telluride (Sb 2 Te 3 ), or copper telluride (Cu 1.4 Te). A metal thin film layer 174, such as molybdenum (Mo), gold (Au), silver (Ag), or nickel (Ni), is deposited on the thin film layer 172. In this case, back contact thin film layer 172 is deposited for ohmic contact, and metal thin film layer 174 is deposited to impart low area resistance to back contact thin film layer 172.
도 2는 본 발명의 일실시예에 따른 CdS/CdTe 박막 태양전지 제조방법을 위해 사용되는 인라인 마그네트론 스퍼터링 시스템을 도시한 도면이고, 도 3는 본 발명의 일실시예에 따른 CdS/CdTe 박막 태양전지 제조방법을 위해 사용되는 인터백 마그네트론 스퍼터링 시스템을 도시한 도면이고, 도 4는 본 발명의 일실시예에 따른 CdS/CdTe 박막 태양전지 제조방법을 위해 사용되는 클러스터 마그네트론 스퍼터링 시스템을 도시한 도면이다.2 is a view illustrating an inline magnetron sputtering system used for a method of manufacturing a CdS / CdTe thin film solar cell according to an embodiment of the present invention, and FIG. 3 is a CdS / CdTe thin film solar cell according to an embodiment of the present invention. FIG. 4 is a diagram illustrating an interbag magnetron sputtering system used for a manufacturing method, and FIG. 4 is a diagram illustrating a cluster magnetron sputtering system used for a CdS / CdTe thin film solar cell manufacturing method according to an embodiment of the present invention.
이 인라인, 인터백 또는 클러스터 마그네트론 스퍼터링 시스템(200)은 로드 락/버퍼 챔버(210), 공정 챔버들(220), 그리고 언로드 락/버퍼 챔버(230)를 구비한다. This inline, interbag or cluster magnetron sputtering system 200 includes a load lock / buffer chamber 210, process chambers 220, and an unload lock / buffer chamber 230.
그리고 공정 챔버들(220)은 기판 상에 TCO 박막 층(120)을 증착하기 위한 제1 스퍼터링 챔버(221)와, TCO 박막 층(120) 상에 고저항 박막 층(130)을 증착하기 위한 제2 스퍼터링 챔버(222)와, 고저항 박막 층(130) 상에 CdS 박막 층(140)을 증착하기 위한 제3 스퍼터링 챔버(223)와, CdS 박막 층(140) 상에 CdTe 박막 층(150)을 증착하기 위한 제4 스퍼터링 챔버(224)와, CdTe 박막 층(150)을 CdCl2로 열처리하는 열처리 챔버(225)와, 열처리된 CdTe 박막 층(150) 상에 증착된 Te 박막 층(160)을 증착하기 위한 제5 스퍼터링 챔버(226)와, Te 박막 층(160) 상에 후면 접촉 박막 층(172)을 증착하기 위한 제6 스퍼터링 챔버(227)와 후면 접촉 박막 층(172) 상에 금속 박막 층(174)을 증착하기 위한 제7 스퍼터링 챔버(228)로 이루어진다.The process chambers 220 may include a first sputtering chamber 221 for depositing a TCO thin film layer 120 on a substrate and a material for depositing a high resistance thin film layer 130 on the TCO thin film layer 120. The second sputtering chamber 222, the third sputtering chamber 223 for depositing the CdS thin film layer 140 on the high resistance thin film layer 130, and the CdTe thin film layer 150 on the CdS thin film layer 140. A fourth sputtering chamber 224 for depositing a thin film, a heat treatment chamber 225 for heat treating the CdTe thin film layer 150 with CdCl 2 , and a Te thin film layer 160 deposited on the heat-treated CdTe thin film layer 150. A fifth sputtering chamber 226 for depositing metal on the back contact thin film layer 172 and a sixth sputtering chamber 227 for depositing metal on the Te thin film layer 160. And a seventh sputtering chamber 228 for depositing the thin film layer 174.
즉, 본 발명의 일실시예에 따른 CdS/CdTe 박막 태양전지의 제조는 도 2, 도 3 또는 도 4의 스퍼터링 챔버들(221, 222, 223, 224, 226, 227, 228) 및 열처리 챔버(225)로 이루어진 공정 챔버들(220)에서 순차적으로 이루어진다.That is, the manufacture of the CdS / CdTe thin film solar cell according to an embodiment of the present invention is the sputtering chambers 221, 222, 223, 224, 226, 227, 228 of FIG. 2, 3, or 4 and the heat treatment chamber ( It is made sequentially in the process chambers 220 consisting of 225.
도 3은 본 발명의 일실시예에 따른 CdS/CdTe 박막 태양전지를 제조하는 방법을 흐름도로 도시한 도면이다.3 is a flowchart illustrating a method of manufacturing a CdS / CdTe thin film solar cell according to an embodiment of the present invention.
먼저, 본 발명에 따라 CdS/CdTe 박막 태양전지를 제조하기 위해 기판을 준비한다(S302). 즉, 도 2, 도 3 또는 도 4의 마그네트론 스퍼터링 시스템(200)의 로드 락/버퍼 챔버(210)로 기판(110)을 제공한다.First, a substrate is prepared to manufacture a CdS / CdTe thin film solar cell according to the present invention (S302). That is, the substrate 110 is provided to the load lock / buffer chamber 210 of the magnetron sputtering system 200 of FIGS. 2, 3, or 4.
로드 락/버퍼 챔버(210)로 제공된 기판(110)이 제1 스퍼터링 챔버(221)로 이송되면, 제1 스퍼터링 챔버(221)는 마그네트론 스퍼터링에 의해 기판(110) 상에 TCO 박막 층(120)를 증착한다(S304). TCO 박막 층(120)은 낮은 저항성과 가시광선에서의 높은 투명성을 갖는 SnO2:F, ZnO:Al이나 ITO(Indium Tin Oxide)으로 형성되는 것이 바람직하다. 이 경우 TCO 박막 층(120)의 두께는 500~1000nm가 바람직하고, 공정 온도는 200~300oC가 바람직하다. When the substrate 110 provided to the load lock / buffer chamber 210 is transferred to the first sputtering chamber 221, the first sputtering chamber 221 is transferred to the TCO thin film layer 120 on the substrate 110 by magnetron sputtering. To deposit (S304). The TCO thin film layer 120 is preferably formed of SnO 2: F, ZnO: Al, or Indium Tin Oxide (ITO) having low resistance and high transparency in visible light. In this case, the thickness of the TCO thin film layer 120 is preferably 500 to 1000 nm, and the process temperature is preferably 200 to 300 ° C.
그리고 TCO 박막 층(120)이 증착된 기판(110)이 제2 스퍼터링 챔버(222)로 이송되면, 제2 스퍼터링 챔버(222)는 마그네트론 스퍼터링에 의해 TCO 박막 층(120) 상에 고저항 박막 층(130)을 증착한다(S306). 이 경우 고저항 박막 층(130)으로는 산화 주석(SnO2), 산화 아연(ZnO), 산화 인듐(In2O3) 등이 사용된다. 고저항 박막 층(130)의 두께는 30~150nm가 바람직하고, 공정온도는 200~300oC가 바람직하다. 그러나 이 고저항 박막 층(130)은 CdS/CdTe 박막 태양전지의 효율에 영향을 미치지 아니하는 경우라면 생략할 수 있다.When the substrate 110 on which the TCO thin film layer 120 is deposited is transferred to the second sputtering chamber 222, the second sputtering chamber 222 is a high resistance thin film layer on the TCO thin film layer 120 by magnetron sputtering. 130 is deposited (S306). In this case, as the high resistance thin film layer 130, tin oxide (SnO 2 ), zinc oxide (ZnO), indium oxide (In 2 O 3 ), or the like is used. The thickness of the high resistance thin film layer 130 is preferably 30 to 150 nm, and the process temperature is preferably 200 to 300 ° C. However, the high resistance thin film layer 130 may be omitted if it does not affect the efficiency of the CdS / CdTe thin film solar cell.
그리고 고저항 박막 층(130)이 증착된 기판(110)이 제3 스퍼터링 챔버(223)로 이송되면, 제3 스퍼터링 챔버(223)는 마그네트론 스퍼터링에 의해 고저항 박막 층(130) 상에 CdS 박막 층(140)을 증착한다(S308). 이 경우 CdS 박막 층(140)의 두께는 50~200nm가 바람직하고, 공정온도는 100~300oC가 바람직하다.When the substrate 110 on which the high resistance thin film layer 130 is deposited is transferred to the third sputtering chamber 223, the third sputtering chamber 223 is a CdS thin film on the high resistance thin film layer 130 by magnetron sputtering. The layer 140 is deposited (S308). In this case, the thickness of the CdS thin film layer 140 is preferably 50 ~ 200nm, the process temperature is preferably 100 ~ 300 ° C.
그리고 CdS 박막 층(140)이 증착된 기판(110)이 제4 스퍼터링 챔버(224)로 이송되면, 제4 스퍼터링 챔버(223)는 마그네트론 스퍼터링에 의해 CdS 박막 층(140) 상에 CdTe 박막 층(150)을 증착한다(S310). 이 경우 CdTe 박막 층(150)의 두께는 2~4가 바람직하고, 공정온도 200~300oC가 바람직하다.When the substrate 110 on which the CdS thin film layer 140 is deposited is transferred to the fourth sputtering chamber 224, the fourth sputtering chamber 223 is formed on the CdTe thin film layer 140 on the CdS thin film layer 140 by magnetron sputtering. 150 is deposited (S310). In this case, the thickness of the CdTe thin film layer 150 is preferably 2 to 4, and a process temperature of 200 to 300 ° C. is preferable.
그리고 CdTe 박막 층(150)이 증착된 후, 열처리 챔버(225)로 기판이 이송되면, 열처리 챔버(225)는 CdTe 박막 층(150)을 CdCl2 증기에 노출시킨다(S312). 이 경우 CdCl2 증기에는 산소를 포함할 수 있으며, 공정 온도는 380~420oC가 바람직하고, 시간은 20~40분이 바람직하다. 그리고, 처리 중에 형성된 잔류 CdCl2을 CdTe 박막 층(150)으로부터 전부 증발시키기 위해, 열처리 챔버를 진공상태에서 수분간 높은 온도로 유지할 수 있다.After the CdTe thin film layer 150 is deposited and the substrate is transferred to the heat treatment chamber 225, the heat treatment chamber 225 exposes the CdTe thin film layer 150 to CdCl 2 vapor (S312). In this case, the CdCl 2 vapor may include oxygen, the process temperature is preferably 380 ~ 420 ° C, the time is preferably 20 to 40 minutes. In addition, in order to completely evaporate the remaining CdCl 2 formed during the treatment from the CdTe thin film layer 150, the heat treatment chamber may be maintained at a high temperature for several minutes in a vacuum state.
이러한 CdCl2 열처리를 수행한 후, CdTe 박막 층(150)까지 형성된 기판(110)이 제5 스퍼터링 챔버(226)로 이송되면, 제5 스퍼터링 챔버(226)는 마그네트론 스퍼터링에 의해 CdTe 박막 층(150) 상에 Te 박막 층(160)을 증착한다(S314). 이 경우 Te 박막 층(160)의 두께는 20~50nm가 바람직하고, 공정 온도는 150~300oC가 바람직하다. 통상 Te 박막 층은 습식 에칭(wet etching) 공정에 의해 형성되는 반면 본 발명에서는 다른 박막의 형성에 사용되는 동일한 스퍼터링 방법을 사용함으로써 공정이 보다 단순하여지고 생산성을 높일 수 있다. 그러나 이 Te 박막 층(160)은 CdS/CdTe 박막 태양전지의 효율에 영향을 미치지 아니하는 경우라면 생략할 수 있다.After the CdCl 2 heat treatment is performed, when the substrate 110 formed up to the CdTe thin film layer 150 is transferred to the fifth sputtering chamber 226, the fifth sputtering chamber 226 is the CdTe thin film layer 150 by magnetron sputtering. Te thin film layer 160 is deposited on (S314). In this case, the thickness of the Te thin film layer 160 is preferably 20 to 50 nm, and the process temperature is preferably 150 to 300 ° C. Normally, the Te thin film layer is formed by a wet etching process, while in the present invention, by using the same sputtering method used to form another thin film, the process can be simplified and productivity can be increased. However, the Te thin film layer 160 may be omitted if it does not affect the efficiency of the CdS / CdTe thin film solar cell.
그리고, Te 박막 층(160)이 증착된 기판(110)이 제6 스퍼터링 챔버(227)로 이송되면, 제6 스퍼터링 챔버(223)는 마그네트론 스퍼터링에 의해 Te 박막 층(160) 상에 후면 접촉 박막 층(172)을 증착한다(S316). 즉, Te 박막 층(160) 상에 p-ZnTe, Sb2Te3, 또는 Cu1.4Te 박막을 공정 온도 150~300oC에서 두께 50~100nm로 형성한다. In addition, when the substrate 110 on which the Te thin film layer 160 is deposited is transferred to the sixth sputtering chamber 227, the sixth sputtering chamber 223 is formed on the Te thin film layer 160 by magnetron sputtering. The layer 172 is deposited (S316). That is, p-ZnTe, Sb 2 Te 3 , or Cu 1.4 Te thin film is formed on the Te thin film layer 160 with a thickness of 50 to 100 nm at a process temperature of 150 to 300 ° C.
마지막으로, 후면 접촉 박막 층(172)이 증착된 기판(110)이 제7 스퍼터링 챔버(227)로 이송되면, 제7 스퍼터링 챔버(223)는 후면 접촉 박막 층(172)에 저면적 저항을 부여하기 위해, 마그네트론 스퍼터링에 의해 후면 접촉 박막 층(172) 상에 금속 박막 층(174)을 증착한다(S318). 이 경우 금속 박막 층(174)의 두께는 200~500nm가 바람직하고, 공정온도는 상온이 바람직하다.Finally, when the substrate 110 on which the back contact thin film layer 172 is deposited is transferred to the seventh sputtering chamber 227, the seventh sputtering chamber 223 imparts a low area resistance to the back contact thin film layer 172. To do so, the metal thin film layer 174 is deposited on the back contact thin film layer 172 by magnetron sputtering (S318). In this case, the thickness of the metal thin film layer 174 is preferably 200 to 500 nm, and the process temperature is preferably room temperature.
이와 같이, 본 발명은 기존의 CdS/CdTe 박막 태양전지 제조방법과는 달리, 열처리를 제외한 모든 공정에 인라인, 인터백 또는 클러스터 시스템에서 마그네트론 스퍼터링 기술 한 가지만을 적용함으로써 생산성을 높일 수 있으며, 낮은 공정온도에서 치밀한 박막을 얻을 수 있다.As such, unlike the conventional CdS / CdTe thin film solar cell manufacturing method, the present invention can increase productivity by applying only one magnetron sputtering technique in an in-line, inter-bag or cluster system to all processes except heat treatment, and lower processes. Dense thin films can be obtained at temperature.
도 6는 본 발명의 일실시예에 따른 CdTe 스퍼터링 챔버의 예를 도시한 도면이다.6 is a diagram illustrating an example of a CdTe sputtering chamber according to an embodiment of the present invention.
CdTe 스퍼터링 챔버(400)는 두꺼운 CdTe 박막 층(150)을 형성하기 위해 4개의 CdTe 타켓(410)을 구비하고 있다. 즉, 다른 박막 층과 비교해 가장 두꺼운 CdTe 박막 층(150)을 증착하는 CdTe 스퍼터링 챔버(400)에는 복수의 CdTe 타켓(410)이 구비되어 있다. 따라서 CdTe 스퍼터링 챔버(400)는 CdS 박막 층(140) 상에 CdTe 박막 층(150)를 증착하는 경우 증착율을 N배로 증가시켜 CdTe 박막 공정 시간을 현격히 줄일 수 있으므로 생산성을 향상시킬 수 있다. 한편, 복수의 CdTe 타켓(410)은 재료 사용 비율을 극대화하기 위하여 공정 진행 중에 회전하는 것이 바람직하다.The CdTe sputtering chamber 400 has four CdTe targets 410 to form a thick CdTe thin film layer 150. That is, a plurality of CdTe targets 410 are provided in the CdTe sputtering chamber 400 which deposits the thickest CdTe thin film layer 150 compared to other thin film layers. Therefore, when the CdTe sputtering chamber 400 deposits the CdTe thin film layer 150 on the CdS thin film layer 140, the deposition rate may be increased by N times, thereby significantly reducing the CdTe thin film process time, thereby improving productivity. On the other hand, the plurality of CdTe target 410 is preferably rotated during the process in order to maximize the material use ratio.
또한, CdTe 스퍼터링 챔버(400)는 CdS 박막 층(140)까지 형성된 기판(110)이 CdTe 스퍼터링 챔버(400) 내부에서 이송되는 과정에서도 CdTe 박막 층(150)를 증착하도록 하여 생산성을 향상을 도모하고 있다.In addition, the CdTe sputtering chamber 400 improves productivity by depositing the CdTe thin film layer 150 even when the substrate 110 formed up to the CdS thin film layer 140 is transferred in the CdTe sputtering chamber 400. have.
또한, CdTe 스퍼터링 챔버(400)에서 이용되는 CdTe 타켓(410)는 막대형 타켓으로 이루어져 있다.In addition, the CdTe target 410 used in the CdTe sputtering chamber 400 is composed of a bar target.
또한, 도 6에 도시된 바와 같이 이 복수의 CdTe 타켓(410)은 기판(110)의 하부 또는 측면에서 기판(110)의 세로길이 이상의 길이를 갖는 것이 바람직하다. 종래에 같이 기판(110)의 상부에 복수의 CdTe 타켓을 구비하면, 스퍼터링 도중에 불순물도 함께 CdTe 박막 층에 증착이 되어 치밀한 박막 구조를 얻을 수 없다.In addition, as illustrated in FIG. 6, the plurality of CdTe targets 410 preferably have a length greater than or equal to the length of the substrate 110 at the bottom or the side of the substrate 110. If a plurality of CdTe targets are provided on the substrate 110 as in the prior art, impurities may also be deposited on the CdTe thin film layer during sputtering, thereby obtaining a dense thin film structure.
한편, 막대형 타켓은 TCO 박막 층(120), 고저항 박막 층(130), CdS 박막 층(140), CdTe 박막 층(150), Te 박막 층(160) 및 후면 전극 박막 층(170)을 형성하기 위해 이용될 수 있다. 이 경우 막대형 타켓은 대면적에 적합한 고효율의 균일한 박막들을 얻을 수 있도록 기판(110)의 세로길이 이상의 길이를 갖는 것이 바람직하다. 다만, TCO 박막 층(120)과 후면 전극 박막 층(170)의 증착시에는 막대형 타켓이 아닌 평면 타켓을 이용할 수도 있다.Meanwhile, the bar target includes the TCO thin film layer 120, the high resistance thin film layer 130, the CdS thin film layer 140, the CdTe thin film layer 150, the Te thin film layer 160, and the rear electrode thin film layer 170. Can be used to form. In this case, the bar target preferably has a length greater than or equal to the longitudinal length of the substrate 110 so as to obtain uniform thin films of high efficiency suitable for a large area. However, when the TCO thin film layer 120 and the rear electrode thin film layer 170 are deposited, a planar target may be used instead of a bar target.
도 7는 본 발명의 일실시예에 따른 CdS/CdTe 박막 태양전지 제조방법을 위해 사용되는 RF/DC 전원 비평형 마그네트론 스퍼터링 챔버를 도시한 도면이다.FIG. 7 illustrates an RF / DC power supply unbalanced magnetron sputtering chamber used for a method of manufacturing a CdS / CdTe thin film solar cell according to an embodiment of the present invention.
한편, 본 발명자들은 박막 층들의 증착시에 RF 전원이나 DC 전원 중 한 가지만 사용하는 대신 RF 전원과 DC 전원을 중첩하여 마그네트론에 공급함으로써, 비교적 낮은 증착 온도와 높은 증착율을 유지할 수 있음을 확인하였다. On the other hand, the inventors of the present invention confirmed that it is possible to maintain a relatively low deposition temperature and high deposition rate by supplying the magnetron by superimposing the RF power supply and the DC power supply to the magnetron instead of using only one of the RF power source and the DC power source when depositing the thin film layers.
즉, 박막 층들의 증착시 DC 전원의 이용함으로써 높은 공정 전압을 이용한 높은 증착율을 얻을 수 있었으며, RF 전원을 이용하여 적당한 에너지의 이온을 기판에 충돌시킴으로써 더 치밀하고 더 양질의 박막을 성장시킬 수 있었다. 이 경우 DC 전원은 펄스적인 DC 전원도 포함한다.In other words, high deposition rate using high process voltage could be obtained by using DC power for deposition of thin film layers, and more dense and better quality thin film could be grown by impinging ions of appropriate energy to substrate using RF power. . In this case, the DC power supply also includes a pulsed DC power supply.
이러한 RF/DC 전원 중첩 방식은 적당한 이온을 기판에 충돌시킴으로써 결정립 성장(grain growth)을 향상시키면서 또한 박막 성장 시에 비교적 높은 증착율을 유지할 수 있게 해준다. This RF / DC power source superimposition improves grain growth by impinging appropriate ions on the substrate while maintaining a relatively high deposition rate during thin film growth.
한편, 본 발명자들은 일반적인 마그네트론 방식이 아닌 자속을 비평형하게 발생하는 비평형(unbalanced) 마그네트론 방식을 적용함으로써, 보다 많은 타켓 이온들이 기판에 도달하게 하여 치밀한 박막과 더 우수한 접착력을 얻을 수 있음을 확인하였다.On the other hand, the present inventors confirmed that by applying an unbalanced magnetron method that generates non-balance magnetic flux rather than a general magnetron method, more target ions can reach the substrate to obtain a dense thin film and better adhesion. It was.
즉, 본 발명은 비평형 마그네트론 방식을 사용하여 스퍼터링시 플라즈마를 향상시켜 이온 전류 밀도를 증가시킴으로 아주 치밀하고, 내부 스트레스가 적은 비기둥형(non-columnar) 박막 구조를 얻을 수 있었다. That is, the present invention was able to obtain a very dense, low internal stress non-columnar thin film structure by increasing the ion current density by improving the plasma during sputtering using a non-balanced magnetron method.
도 7에서 알 수 있는 바와 같이, 본 발명에 적용되는 스퍼터링 챔버(500)는 진공조(510) 내에 고정 배치 또는 이동 가능하게 배치된 기판 홀더(520)에 지지되는 기판(110)과 대향하여, 캐소드(530)가 마련되어 있다. 기판 홀더(520)의 배면에는 기판(110)의 온도를 제어하기 위한 히터 등의 가열수단(미도시됨)이 마련되어 있다. As can be seen in FIG. 7, the sputtering chamber 500 applied to the present invention is opposed to the substrate 110 supported by the substrate holder 520 which is fixedly disposed or movable in the vacuum chamber 510. The cathode 530 is provided. The back of the substrate holder 520 is provided with heating means (not shown) such as a heater for controlling the temperature of the substrate 110.
그리고 캐소드(530)의 기판 측에는 타켓(532)이 고정되어 있고, 캐소드(530)의 배면에는 자기회로(540)가 마련되어 있다. 이 자기회로(540)는 자계를 발생시키기 위한 영구자석(542)과 이 영구자석(542)를 지지하는 베이스(544)를 포함한다. The target 532 is fixed to the substrate side of the cathode 530, and the magnetic circuit 540 is provided on the rear surface of the cathode 530. The magnetic circuit 540 includes a permanent magnet 542 for generating a magnetic field and a base 544 supporting the permanent magnet 542.
이 영구자석(542)는 마그네트론 스퍼터링에서의 비평형 자계를 발생시키기 위한 것으로, N극과 S극의 자계 강도가 다르다.This permanent magnet 542 is for generating an unbalanced magnetic field in magnetron sputtering, and the magnetic field strengths of the N pole and the S pole are different.
또한, 캐소드(530)에 공급되는 방전용 전원부(560)는 직류 전계를 인가하기 위한 DC 전원(552)과 이 직류 전계에 중첩될 수 있도록 고주파 전계를 인가하기 위한 RF 전원(554)을 포함한다. In addition, the discharge power supply unit 560 supplied to the cathode 530 includes a DC power supply 552 for applying a DC electric field and an RF power supply 554 for applying a high frequency electric field so as to overlap the DC electric field. .
이 중첩된 DC 전원(552)과 RF 전원(554)은 매칭 박스(560)를 통해 캐소드(530)에 전압을 공급한다. 한편, DC 전원(552)과 매칭 박스(560) 사이에는 DC 전원(552)에 고주파 전계의 유입을 방지하기 위한 RF 필터(562)가 개재되어 있다. The superimposed DC power supply 552 and the RF power supply 554 supply a voltage to the cathode 530 through the matching box 560. Meanwhile, an RF filter 562 is interposed between the DC power supply 552 and the matching box 560 to prevent the high frequency electric field from flowing into the DC power supply 552.
이 DC 전원(552)에는 350V 이하의 전원이 공급되고, 바람직하게는 펄스 파형을 갖는 펄스화된 DC 전원이 바람직하다. 이 경우 펄스 파형의 주파수는 5 내지 350KHz이다. 그리고 RF 전원(554)의 주파수는 4MHz 내지 40MHz이다.The DC power supply 552 is supplied with a power supply of 350 V or less, preferably a pulsed DC power supply having a pulse waveform. In this case, the frequency of the pulse waveform is 5 to 350 KHz. And the frequency of the RF power supply 554 is 4MHz to 40MHz.
한편, 도 7에서는 중첩된 DC 전원(552)과 RF 전원(554)을 캐소드(530)에 공급하고 있으나, 본 발명에서는 플라즈마를 생성하기 위해 중첩된 DC 전원(552)과 RF 전원(554)이 공급될 수 있는 구성을 넓은 의미로 마그네트론이라 한다. In FIG. 7, the superimposed DC power supply 552 and the RF power supply 554 are supplied to the cathode 530. However, in the present invention, the superimposed DC power supply 552 and the RF power supply 554 are used to generate a plasma. The configuration that can be supplied is called a magnetron in a broad sense.
그리고, 도 7의 스퍼터링 챔버를 이용하여 RF/(RF+DC) 전력비의 변화에 따른 방전 전압, 스퍼터율 및 저항률을 스케치한 결과, CdS/CdTe 박막 태양전지를 제조함에 있어서 바람직한 RF/(RF+DC) 전력비는 20% 내지 50%의 범위이다.As a result of sketching the discharge voltage, the sputtering rate and the resistivity according to the change of the RF / (RF + DC) power ratio using the sputtering chamber of FIG. 7, the RF / (RF + (RF +) is preferable for manufacturing a CdS / CdTe thin film solar cell. DC) power ratio ranges from 20% to 50%.
상술한 바와 같이, 본 발명은 인라인, 인터백 또는 클러스터 시스템에서의 마그네트론 스퍼터링 기술, 특히 인라인, 인터백 또는 클러스터 시스템에서의 RF/DC 비평형 마그네트론 스퍼터링 기술을 이용하여 보다 간단하고 경제적으로 TCO 박막 층(120), 고저항 박막 층(130), CdS 박막 층(140), CdTe 박막 층(150), Te 박막 층(160) 및 후면 전극 박막 층(170)을 순차적으로 증착할 수 있고 장비의 대형화로 현재 8.5세대 급의 대형 TFT-LCD 판넬 크기와 같은 2200x2600 mm2 또는 그 이상의 면적을 갖는 태양전지를 생산할 수 있다. As noted above, the present invention provides a simpler and more economical TCO thin film layer using magnetron sputtering techniques in inline, interback or cluster systems, in particular RF / DC unbalanced magnetron sputtering techniques in inline, interbag or cluster systems. 120, high resistance thin film layer 130, CdS thin film layer 140, CdTe thin film layer 150, Te thin film layer 160 and the back electrode thin film layer 170 can be deposited sequentially and the size of equipment This enables the production of solar cells with an area of 2200x2600 mm 2 or more, which is equivalent to the size of 8.5-generation large TFT-LCD panels.
또한 이러한 인라인, 인터백 또는 클러스터 시스템에서의 마그네트론 스퍼터링 공정을 이용하면 2시간 내로 태양전지를 완성할 수 있으며 열처리 공정을 제외한 모든 공정에서 기존의 CSS 와 VTD 공정 온도(>500oC)보다 훨씬 낮은 공정 온도(<300oC)를 사용함으로써 각 박막을 이루는 재료의 화학적 순수성과 안정성이 보장되고 이는 생산성의 향상을 가져오게 된다. In addition, the magnetron sputtering process in this in-line, interbag or cluster system allows the solar cell to be completed in less than two hours and is much lower than conventional CSS and VTD process temperatures (> 500 o C) for all processes except heat treatment. The use of process temperatures (<300 o C) ensures the chemical purity and stability of the material of each thin film, leading to an increase in productivity.
그리고 인라인, 인터백 또는 클러스터에서의 RF/DC 비평형 마그네트론 스퍼터링 기술은 전체 스퍼터링 면적에서 10% 이하의 두께 편차, 5% 이하의 온도 편차, 회전식 스퍼터링 타겟을 사용할 경우 70% 이상의 높은 타겟 재료 이용율을 얻을 수 있다. 이러한 인라인, 인터백 또는 클러스터 RF/DC 비평형 마그네트론 스퍼터링 공정의 모든 장점을 활용함으로써 생산라인에서 10 ~ 12%의 에너지 변환 고효율을 얻을 수 있다.In addition, RF / DC unbalanced magnetron sputtering technology in inline, interbag, or clusters provides greater than 10% thickness variation across the entire sputtering area, less than 5% temperature variation, and high target material utilization of 70% or more when using rotary sputtering targets. You can get it. All the advantages of this inline, interbag or clustered RF / DC unbalanced magnetron sputtering process can result in 10 to 12% energy conversion efficiencies in the production line.
도 8은 본 발명의 일실시예에 따른 RF/DC 비평형 마그네트론 스퍼터링 장비로 증착된 TCO, CdS, CdTe 박막 단면의 SEM(scanning electron microscope) 사진을 도시한다.FIG. 8 shows a scanning electron microscope (SEM) photograph of a cross section of TCO, CdS, and CdTe thin films deposited with an RF / DC non-equilibrium magnetron sputtering apparatus according to an embodiment of the present invention.
도 8에 도시된 바와 같이, TCO 박막 층(120)은 약 300nm, CdS 박막 층(140)은 약 180nm, 그리고 CdTe 박막 층(150)은 약 2.4의 두께로 증착되었으며 각 박막의 경계가 매우 뚜렷하고 두께가 균일함을 알 수 있다.As shown in FIG. 8, the TCO thin film layer 120 is about 300 nm, the CdS thin film layer 140 is about 180 nm, and the CdTe thin film layer 150 is deposited to a thickness of about 2.4, and the boundaries of each thin film are very clear. It can be seen that the thickness is uniform.
도 9은 CdCl2 열처리 후의 TCO, CdS, CdTe 박막 단면의 SEM(scanning electron microscope) 사진을 도시한 도면이다.FIG. 9 is a diagram illustrating a scanning electron microscope (SEM) photograph of cross sections of TCO, CdS, and CdTe thin films after CdCl 2 heat treatment.
도 8 및 도 9을 통해 비교할 수 있듯이, 이 열처리 공정에 의해 CdTe 결정립(grain)이 서브 마이크로 미터에서 마이크로 미터 크기로 성장하고 동시에 결정 경계면의 비활성화(passivation)가 이루어진다. 이에 의해 CdS/CdTe 박막 태양전지의 전기적 특성이 향상된다. As can be seen from FIGS. 8 and 9, this heat treatment process causes the CdTe grains to grow from sub-micrometers to micrometers in size and at the same time passivation of the crystal interface. As a result, the electrical characteristics of the CdS / CdTe thin film solar cell are improved.
도 10은 본 발명의 일실시예에 따라 제조된 CdS/CdTe 박막 태양전지의 전기적 특성을 도시한 도면이다. 10 is a view showing the electrical characteristics of the CdS / CdTe thin film solar cell manufactured according to an embodiment of the present invention.
본 발명에 따른 CdS/CdTe 박막 태양전지의 평균적인 오픈 회로 전압(Voc)는 750~850mV, 단락 회로 전류(Isc)는 20~23mA, Fill Factor(FF)는 62~74%, 효율은 10~13%이다. 이는 기존의 VDT 또는 CSS를 이용하여 생산되는 대면적 CdTe 박막 태양전지의 효율이 8~9%인 것에 비교해 1~5%의 높은 효율이다.The average open circuit voltage (Voc) of the CdS / CdTe thin film solar cell according to the present invention is 750 ~ 850mV, short circuit current (Isc) 20 ~ 23mA, Fill Factor (FF) 62 ~ 74%, efficiency 10 ~ 13%. This is 1-5% higher efficiency than 8-9% efficiency of large-area CdTe thin film solar cells produced using existing VDT or CSS.
본 발명의 보호 범위는 이하 특허청구범위에 의하여 해석되어야 마땅할 것이다. 또한, 본 발명이 속하는 기술 분야에서 통상의 지식을 가진 자라면 본 발명의 본질적인 특성에서 벗어나지 않는 범위에서 다양한 수정 및 변형이 가능할 것인 바, 본 발명과 동등한 범위 내에 있는 모든 기술 사상은 본 발명의 권리범위에 포함되는 것으로 해석되어야 할 것이다The protection scope of the present invention should be interpreted by the following claims. In addition, one of ordinary skill in the art to which the present invention pertains will be capable of various modifications and variations without departing from the essential characteristics of the present invention, all technical ideas within the scope equivalent to the present invention of the present invention Should be interpreted as being included in the scope of rights
본 발명은 대면적화에 따른 생산성을 향상시켜 제조원가를 줄이고 낮은 공정온도로 제조시의 열화를 방지하여 태양전지의 고효율을 얻기 위해, 인라인, 인터백 또는 클러스터 시스템을 이용한 CdS/CdTe 박막 태양전지 제조 방법 및 그 방법에 의해 제조된 CdS/CdTe 박막 태양전지에서 이용가능하다.The present invention is to improve the productivity according to the large area to reduce the manufacturing cost and to prevent degradation during manufacturing at low process temperature to obtain high efficiency of the solar cell, CdS / CdTe thin film solar cell manufacturing method using an in-line, inter-bag or cluster system And CdS / CdTe thin film solar cells produced by the method.

Claims (7)

  1. 인라인, 인터백 또는 클러스터 시스템에서의 CdS/CdTe 박막 태양전지를 제조하는 방법에 있어서, A method for manufacturing a CdS / CdTe thin film solar cell in an inline, interback or cluster system,
    기판을 준비하는 단계와,Preparing a substrate;
    제1 스퍼터링 챔버에서 상기 기판 상에 투명 도전 산화 박막을 증착하는 단계와,Depositing a transparent conductive oxide thin film on the substrate in a first sputtering chamber;
    제2 스퍼터링 챔버에서 상기 투명 도전 산화 박막 상에 CdS 박막을 증착하는 단계와,Depositing a CdS thin film on the transparent conductive oxide thin film in a second sputtering chamber;
    제3 스퍼터링 챔버에서 상기 CdS 박막 상에 CdTe 박막을 증착하는 단계와, 및Depositing a CdTe thin film on the CdS thin film in a third sputtering chamber, and
    열처리 챔버에서 상기 CdTe 박막을 CdCl2로 처리하는 단계를 포함하고,Treating the CdTe thin film with CdCl 2 in a heat treatment chamber,
    상기 제3 스퍼터링 챔버에는 상기 기판의 세로길이 이상의 길이를 갖는 복수의 CdTe 타켓이 구비되며, 상기 CdTe 박막의 증착은 상기 복수의 CdTe 타켓에 중첩된 RF/DC 전원을 공급하여 발생하는 스퍼터링을 이용하여 증착하는 것을 특징으로 하는 CdS/CdTe 박막 태양전지 제조 방법.The third sputtering chamber is provided with a plurality of CdTe targets having a length greater than or equal to the length of the substrate, and the deposition of the CdTe thin film uses sputtering generated by supplying RF / DC power superimposed on the plurality of CdTe targets. CdS / CdTe thin film solar cell manufacturing method characterized in that the deposition.
  2. 제1항에 있어서,The method of claim 1,
    상기 CdTe 박막의 증착은 상기 기판의 이송 중에도 증착되는 것을 특징으로 하는 CdS/CdTe 박막 태양전지 제조 방법.The deposition of the CdTe thin film is a CdS / CdTe thin film solar cell manufacturing method characterized in that the deposition during the transfer of the substrate.
  3. 제2항에 있어서,The method of claim 2,
    상기 복수의 CdTe 타켓은 공정 진행 중에 회전하는 것을 특징으로 하는 CdS/CdTe 박막 태양전지 제조 방법.The CdS / CdTe thin film solar cell manufacturing method characterized in that the plurality of CdTe target is rotated during the process.
  4. 제1항 내지 제3항 중 어느 한 항에 있어서,The method according to any one of claims 1 to 3,
    제4 스퍼터링 챔버에서 상기 CdCl2로 처리된 상기 CdTe 박막 상에 P형 텔루르화 아연, 텔루르화 안티몬, 또는 텔루르화 구리로 이루어지는 후면 접촉 박막을 증착하는 단계와, 및 Depositing a back contact thin film made of P-type zinc telluride, antimony telluride, or copper telluride on the CdTe thin film treated with CdCl 2 in a fourth sputtering chamber, and
    제5 스퍼터링 챔버에서 상기 후면 접촉 박막 상에 몰리브덴, 금, 은 또는 니켈로 이루어지는 금속 박막을 증착하는 단계를 더 포함하는 것을 특징으로 CdS/CdTe 박막 태양전지 제조 방법. And depositing a metal thin film made of molybdenum, gold, silver, or nickel on the back contact thin film in a fifth sputtering chamber.
  5. 제4항에 있어서,The method of claim 4, wherein
    상기 각 스퍼터링 챔버에는 자속을 비평형하게 발생하는 비평형 마그네트론이 구비되는 것을 특징으로 하는 CdS/CdTe 박막 태양전지 제조 방법. Each sputtering chamber is provided with a non-equilibrium magnetron for generating a non-equilibrium magnetic flux CdS / CdTe thin film solar cell manufacturing method characterized in that.
  6. 제5항에 있어서,The method of claim 5,
    상기 투명 도전 산화 박막, 상기 CdS 박막, 상기 후면 접촉 박막 및 상기 금속 박막의 증착은 상기 각 스퍼터링 챔버의 각 타켓에 중첩된 RF/DC 전원을 공급하여 발생하는 스퍼터링을 이용하여 증착되는 것을 특징으로 CdS/CdTe 박막 태양전지 제조 방법.The deposition of the transparent conductive oxide thin film, the CdS thin film, the back contact thin film and the metal thin film is deposited using sputtering generated by supplying RF / DC power superimposed on each target of each sputtering chamber. / CdTe thin film solar cell manufacturing method.
  7. 제6항에 있어서,The method of claim 6,
    상기 중첩된 RF/DC 전원은 매칭 박스를 통해 상기 타켓에 공급되는 것을 특징으로 하는 CdS/CdTe 박막 태양전지 제조 방법.The superimposed RF / DC power is supplied to the target through a matching box CdS / CdTe thin film solar cell manufacturing method characterized in that.
PCT/KR2010/000490 2009-01-28 2010-01-27 Method for manufacturing a cds/cdte thin film solar cell WO2010087613A2 (en)

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