Patent Publication Number: US-2013236844-A1

Title: Substrate carrier and selenization process system thereof

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a substrate carrier and a selenization process system, and more specifically, to a substrate carrier having a heat-resistant metal frame with a protective layer formed thereon and a selenization process system thereof. 
     2. Description of the Prior Art 
     Generally, in a manufacturing process of a CIGS (copper indium gallium selenide) solar battery, a conventional method of forming a CIGS/CIGSS (copper indium gallium selenide sulfide) absorber film involves utilizing a co-evaporation process or a selenization process. 
     In the selenization process, a substrate carrier for carrying back electrode substrates into a selenization furnace is usually made of quartz or ceramics, so that the substrate carrier could have heat resistant and gas-corrosion (e.g. sulfide gas) resistant characteristics. However, since quartz and ceramics are expensive and brittle, the aforesaid design in which the substrate carrier is made of quartz or ceramics may greatly increase the material cost of the solar battery manufacturing process. Furthermore, the substrate carrier may be damaged easily by collision with other process components during the transportation process, so as to influence the productive capacity of the solar battery manufacturing process and result in unnecessary loss. 
     SUMMARY OF THE INVENTION 
     The present invention provides a substrate carrier for carrying a plurality of back electrode substrates into a furnace. Each back electrode substrate has a precursor layer formed thereon. The furnace is used for providing a process gas to react with the precursor layer so as to form a photoelectric transducing layer on each back electrode substrate. The substrate carrier includes a heat-resistant metal frame and a first protective layer. The heat-resistant metal frame has a plurality of slots for supporting the plurality of back electrode substrates. The first protective layer is formed on the heat-resistant metal frame for preventing a chemical reaction of the heat-resistant metal frame with the process gas. 
     The present invention further provides a selenization process system. The selenization process system includes a plurality of back electrode substrates, a furnace, and a substrate carrier. Each back electrode substrate has a precursor layer formed thereon. The furnace includes a reaction chamber, a gas input pipeline, and a heating device. The gas input pipeline is used for providing a process gas to the reaction chamber. The heating device is used for heating the reaction chamber to make the process gas react with the precursor layer so as to form a photoelectric transducing layer on each back electrode substrate. The substrate carrier is used for carrying the plurality of back electrode substrates into the furnace. The substrate carrier includes a heat-resistant metal frame and a first protective layer. The heat-resistant metal frame has a plurality of slots for supporting the plurality of back electrode substrates. The first protective layer is formed on the heat-resistant metal frame for preventing a chemical reaction of the heat-resistant metal frame with the process gas. 
     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an inner diagram of a selenization process system according to an embodiment of the present invention. 
         FIG. 2  is a diagram of a substrate carrier in  FIG. 1 . 
         FIG. 3  is a sectional diagram of the substrate carrier in  FIG. 2  along a sectional line A-A′. 
         FIG. 4  is a sectional diagram of a substrate carrier according to another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Please refer to  FIG. 1 , which is an inner diagram of a selenization process system  10  according to an embodiment of the present invention. The selenization process system  10  is applied to a solar battery manufacturing process. As shown in  FIG. 1 , the selenization process system  10  includes a plurality of back electrode substrates  12 , a furnace  14 , and a substrate carrier  16 . In general, the substrate of the back electrode substrate  12  could be a soda-lime glass, and the back electrode of the back electrode substrate  12  could be made of molybdenum (Mo) material. Each back electrode substrate  12  has a precursor layer  18  formed thereon. In this embodiment, the precursor layer  18  is an IB-group and IIIA-group chemical compound layer, such as Cu—Ga/In, Cu—Ga—In alloy, or Cu—Ga—In stacked layer. As for the process of forming the back electrode substrate  12  and the precursor layer  18 , it is commonly seen in the prior art. In brief, a sputtering machine or other electrode forming technology is utilized to form the back electrode on the substrate of the back electrode substrate  12 , and a thin-film deposition technology or other thin-film forming technology is then utilized to form the precursor layer  18  on the back electrode of the back electrode substrate  12 . 
     The furnace  14  could be a conventional selenization equipment for a selenization process of a solar battery. As shown in  FIG. 1 , the furnace  14  includes a reaction chamber  20 , a gas input pipeline  22 , and a heating device  24 . The gas input pipeline  22  is used for providing a process gas (e.g. H 2 Se or H 2 S) to the reaction chamber  20  to react with the precursor layer  18 . The heating device  24  is used for heating the reaction chamber  20  to a temperature (about 450° C. to 550° C.) in which the process gas could react with the precursor layer  18  of each back electrode substrate  12  respectively to form a corresponding photoelectric transducing layer. The photoelectric transducing layer could be, for example, a chalcopyrite structure of copper indium selenide (CIS), copper indium sulfide (CIS), copper indium gallium selenide (CIGS), or copper indium gallium selenide sulfide (CIGSS). As for the related component designs of the furnace  14 , they are commonly seen in the prior art and the related description is therefore omitted herein. 
     More detailed description for the design of the substrate carrier  16  is provided as follows. Please refer to  FIG. 1 ,  FIG. 2 , and  FIG. 3 .  FIG. 2  is a diagram of the substrate carrier  16  in  FIG. 1 .  FIG. 3  is a sectional diagram of the substrate carrier  16  in  FIG. 2  along a sectional line A-A′. The substrate carrier  16  is used for carrying the plurality of back electrode substrates  12  into the reaction chamber  20  (as shown in  FIG. 1 ) to perform the aforesaid selenization process. The substrate carrier  16  includes a heat-resistant metal frame  26  and a first protective layer  28 . In this embodiment, the heat-resistant metal frame  26  is preferably made of metal material capable of withstanding the high temperature (about 450° C. to 550° C.) of the aforesaid selenization process, such as molybdenum material, titanium (Ti) material, tantalum (Ta) material, or tungsten (W) material, so as to prevent the heat-resistant metal frame  26  form melting in the high temperature of the reaction chamber  20 . Furthermore, as shown in  FIG. 2 , the heat-resistant metal frame  26  has a plurality of slots  30  for supporting the back electrode substrates  12 , so that the back electrode substrates  12  could be conveyed steadily with the substrate carrier  16  into the reaction chamber  20  of the furnace  14  by a conventional automatic equipment (e.g. a robot arm or a conveyor belt). 
     In addition, the first protective layer  28  is formed on the heat-resistant metal frame  26  (as shown in  FIG. 3 ) and is preferably an oxide layer, a nitride layer, or a selenium layer in this embodiment. To be more specific, a conventional surface treatment (e.g. thermal processing or chemical processing) could be performed on the heat-resistant metal frame  26  to forma gas-corrosion resistant layer (i.e. the first protective layer  28 ) on the heat-resistant metal frame  26 , so as to prevent corrosion of the heat-resistant metal frame  26  caused by the process gas or prevent the heat-resistant metal frame  26  from reacting with the process gas to generate harmful chemical compound. Thus, the forming quality of the photoelectric transducing layer could be further improved. 
     It should be mentioned that the heat resistant design of the heat-resistant metal frame is not limited to the aforesaid embodiment. Please refer to  FIG. 4 , which is a sectional diagram of a substrate carrier  100  according to another embodiment of the present invention. Components both mentioned in this embodiment and the aforesaid embodiment represent components with similar structures or functions, and the related description is therefore omitted herein. The major difference between the substrate carrier  100  and the substrate carrier  16  is material of the heat-resistant frame and additional disposal of another protective layer. As shown in  FIG. 4 , the substrate carrier  100  includes a heat-resistant metal frame  102  and the first protective layer  28 . The heat-resistant metal frame  102  has the plurality of slots  30  for supporting the back electrode substrates  12 . The heat-resistant metal frame  102  further has a second protective layer  104  formed thereon corresponding to the first protective layer  28 . The second protective layer  104  could be made of heat-resistant metal material, such as molybdenum material, titanium material, tantalum material, or tungsten material, and a thickness of the second protective layer  104  is about 100 μm to 500 μm. In this embodiment, the heat-resistant metal frame  102  could be made of conventional metal material, such as stainless steel material. As for forming of the second protective layer  104 , a conventional surface treatment (e.g. thermal processing or chemical processing) could be performed on the heat-resistant metal frame  102  to form a heat resistant layer (i.e. the second protective layer  104 ) on the heat-resistant metal frame  102 . In such a manner, besides the gas-corrosion resistant characteristic due to utilizing the first protective layer  28 , the substrate carrier  100  could further have the heat resistant characteristic via the design in which the second protective layer  104  is additionally formed on the heat-resistant metal frame  102  (as shown in  FIG. 4 ). In addition, since the heat-resistant metal frame  102  could just be made of conventional metal material rather than heat-resistant metal material in this embodiment, the material cost of the solar battery manufacturing process could be further reduced. 
     Compared with the prior art, via the aforesaid design in which the substrate carrier has the heat-resistant metal frame and the protective layer formed on the heat-resistant metal frame, the substrate carrier of the present invention could have heat resistant and gas-corrosion resistant characteristics to prevent the heat-resistant metal frame from melting in the high temperature of the selenization process, being corroded by the process gas, or reacting with the process gas to form harmful chemical compound, so that the forming quality of the photoelectric transducing layer could be improved. Furthermore, since the heat-resistant metal frame is made of metal material rather than quartz or ceramics material, the present invention could not only reduce the material cost of the solar battery manufacturing process, but also increase the overall structural strength of the substrate carrier due to high strength and high rigidity of metal material. Thus, since the prior art problem that the substrate carrier may be damaged easily by collision with other process components during the transportation process could be solved accordingly, an automation design could be further applied to the selenization process system of the present invention for increasing the productive capacity of the solar battery manufacturing process. 
     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.