Abstract:
A cathode discharge device is provided. The cathode discharge apparatus includes an anode, a cathode and plural cathode chambers. The cathode is located inside the anode, where the cathode has plural flow channels and at least one flow channel hole, and the plural flow channels are connected to one another through the flow channel hole. The plural cathode chambers are located inside the cathode, wherein each of the cathode chambers has a chamber outlet and a chamber inlet connected with at least one of the flow channels.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a cathode discharge apparatus, especially to a hollow cathode discharge apparatus for the large area coating. 
       BACKGROUND OF THE INVENTION 
       [0002]    Under the condition of the predictable shortage of the fossil fuel in the near future, looking for the substituted energies becomes an urgent issue. Among various substituted energies, the solar energy is the one with the best economy and environment protection. Therefore, several countries, such as USA and Germany, have included the solar energy as the national energy development project. However, the utilization rate of the solar energy is limited due to the conversion efficiency of the solar cell. There are two ways to raise the utilization rate. One is to raise the conversion efficiency of the solar cell, and the other is to reduce the production cost of the solar cell. Nevertheless, it is not easy to raise the conversion efficiency of the solar cell owing to the solid state properties of the semiconductor, but it is feasible to enlarge the exposure area of the solar cell. 
         [0003]    The main manufacturing method of the thin film solar cell includes plasma enhanced chemical vapor deposition (PECVD). Since the size of the glass oft he buildings in the metropolis becomes larger, the manufacturing processes of the thin film solar cell for these glass substrates with large sizes have the trend toward the enlarged size and the continuous manufacturing. This trend meets the generation evolution of the substrate size of the thin film transistor liquid crystal display (TFT-LCD). Recently, the great progresses have been being made for the optoelectronic technologies, e.g. solar cells, TFT-LCD, etc., which necessitate the plasma apparatuses capable of performing the large area continuous manufacturing processes. Currently, the plasma apparatuses have the uniformity problem for the large-size plasma processes applied to TFT-LCD, thin film solar cells, etc. 
         [0004]    In order to eliminate the above problem, the new technical solutions are proposed in the present invention by introducing the newly developed plasma hollow cathode discharge apparatus for the large area deposition processes for optoelectronic devices, e.g. solar cells. By stabilizing the pressure in the flow channels filled with the working gas, the plasma generated by the cathode discharge apparatus of the present invention has the properties of high uniformity and high dissociation to enhance the deposition rate. Accordingly, the present invention can solve the above mentioned problem, can greatly promote the manufacturing technologies, product performance, product quality and reliability of the optoelectronic apparatus, e.g. solar cells, can reduce the production cost at the same time, and finally make great contributions to the customers. The present invention is described below. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention provides the cathode discharge apparatus able to generate the plasma with high uniformity and high ionization. 
         [0006]    In accordance with one aspect of the present invention, a cathode discharge apparatus is provided. The cathode discharge apparatus comprises an anode, a cathode and plural cathode chambers. The cathode is located inside the anode, wherein the cathode has plural flow channels and at least one flow channel hole, and the plural flow channels are connected to one another through the flow channel hole. The plural cathode chambers are located inside the cathode, wherein each of the cathode chambers has a chamber outlet and a chamber inlet connected with at least one of the flow channels. 
         [0007]    In one embodiment, the cathode discharge apparatus further comprises an insulator separating the anode from the cathode. 
         [0008]    In another embodiment, the cathode discharge apparatus further comprises a flow channel inlet for feeding the cathode discharge apparatus with a working gas therethrough, wherein the working gas flows into the cathode chambers through the flow channel inlet, one of the flow channels, the at least one flow channel hole, another one of the flow channels and the chamber inlets, sequentially. 
         [0009]    In one embodiment, the working gas is selected from a group consisting of hydrogen, helium, argon, oxygen, nitrogen, ammonia, silane, and a combination thereof. 
         [0010]    In one embodiment the working gas inside the cathode chambers generates plasma spouted through the chamber outlets. 
         [0011]    In one embodiment, the plasma is spouted through the chamber outlets along plural spouting directions unparallel to one another. 
         [0012]    In one embodiment, the cathode further comprises a first and a second portions, which are made in one of one piece and separate pieces. 
         [0013]    In one embodiment, each of the cathode chambers comprises a first and a second portions, the first portion of the cathode chamber is located inside the first portion of the cathode, and the second portion of the cathode chamber is located inside the second portion of the cathode. 
         [0014]    In one embodiment, the first and the second portions of the cathode chambers are different in at least one of shape and size. 
         [0015]    In one embodiment, the cathode discharge apparatus further comprises an electrical feedthrough connected with the cathode. In accordance with another aspect of the present invention, another cathode discharge apparatus is provided. The cathode discharge apparatus comprises an anode, plural cathodes and plural electrical feedthroughs. The plural cathodes are located inside the anode, wherein each of the cathodes has at least one flow channel and at least one cathode chamber having a chamber outlet and a chamber inlet connected with the flow channel. The plural electrical feedthroughs are connected with the cathodes. 
         [0016]    In one embodiment, the cathode discharge apparatus further comprises a power supply electrically connected with at least one of the electrical feedthroughs. 
         [0017]    In one embodiment, the cathode discharge apparatus further comprises at least one flow channel inlet for feeding the cathode discharge apparatus with a working gas therethrough, wherein the working gas flows into the at least one cathode chamber through the flow channel inlet, the flow channel and the chamber inlet, sequentially. 
         [0018]    In one embodiment the working gas inside the cathode chamber generates plasma spouted through the chamber outlet. 
         [0019]    In accordance with a further aspect of the present invention, a cathode discharge apparatus is provided. The cathode discharge apparatus comprises plural cathode discharge units and an electrode connecting element. Each of the plural cathode discharge units comprises an anode, an insulator, a cathode, plural cathode chambers and plural electrical feedthroughs. The cathode is located inside the anode, wherein the anode and the cathode are separated by the insulator, and the cathode has at least one flow channel internally. The plural cathode chambers are located inside the cathode, wherein each of the cathode chambers has a chamber outlet and a chamber inlet connected with the flow channel. The plural electrical feedthroughs are connected with the cathode. The electrode connecting element is electrically connected with at least one of the electrical feedthroughs. 
         [0020]    In one embodiment, the at least one flow channel comprises a first flow channel, a second flow channel and at least one flow channel hole communicating the first and the second flow channels. 
         [0021]    In one embodiment, the cathode discharge apparatus further comprises at least one flow channel inlet for feeding the cathode discharge apparatus with a working gas therethrough, wherein the working gas flows into the cathode chambers through the first flow channel, the flow channel hole, the second flow channel and the chamber inlets, sequentially. 
         [0022]    In one embodiment, the working gas is selected from a group consisting of hydrogen, helium, argon, oxygen, nitrogen, ammonia, silane, and a combination thereof. 
         [0023]    In one embodiment, plasma is generated by the working gas inside the cathode chambers, and the plasma is spouted through the chamber outlets. 
         [0024]    In one embodiment, the cathode discharge apparatus further comprises a power supply electrically connected to the electrode connecting element, wherein the power supply provides power to the cathode through the electrode connecting element and the electrical feedthroughs. 
         [0025]    The above objects and advantages of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed descriptions and accompanying drawings, in which: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]      FIG. 1  is the schematic diagram showing the cross section of the cathode discharge apparatus from the side view according to the first embodiment of the present invention; 
           [0027]      FIG. 2  is the schematic diagram showing the cross section of the cathode discharge apparatus in  FIG. 1  along the A-A′ line according to the first embodiment of the present invention; 
           [0028]      FIG. 3  is the schematic diagram showing the cross section of the cathode discharge apparatus according to the second embodiment of the present invention; 
           [0029]      FIG. 4  is the schematic diagram showing the cross section of the cathode discharge apparatus according to the third embodiment of the present invention; 
           [0030]      FIG. 5  is the schematic diagram showing the 3-dimensinal view of the cathode discharge apparatus according to the third embodiment of the present invention; 
           [0031]      FIG. 6  is the schematic diagram showing the cross section of the cathode discharge apparatus according to the fourth embodiment of the present invention; and 
           [0032]      FIG. 7  is the schematic diagram showing the 3-dimensional view of the cathode discharge apparatus according to the fourth embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0033]    The present invention will now be described more specifically with reference to the following embodiments. It is to be noted that the following descriptions of several embodiments of this invention are presented herein for the purposes of illustration and description only; it is not intended to be exhaustive or to be limited to the precise form disclosed. 
       First Embodiment 
       [0034]      FIG. 1  is the schematic diagram showing the cross section of the cathode discharge apparatus from the side view according to the first embodiment of the present invention.  FIG. 2  is the schematic diagram showing the cross section of the cathode discharge apparatus in  FIG. 1  along the A-A line according to the first embodiment of the present invention. Please refer to  FIG. 2 . The cathode discharge apparatus  10 A includes the anode  11 , the cathode  21  and the cathode chamber  25 . The cathode  21  is located inside the anode  11 . The insulators  22   a ,  22   b  and  22   c  separate the cathode  21  and anode  11 . 
         [0035]    The cathode  21  includes plural cathode chambers  25 , and can be divided into the first portion  21   a  and the second portion  21   b , which may be two pieces contacted with each other for facilitating the machining process, or may be made in one piece. Each of the cathode chambers  25  can be divided into the first portion  25   a  and the second portion  25   b , where the first portion  25   a  of the cathode chamber  25  is located in the first portion  21   a  of the cathode  21 , and the second portion  25   b  of the cathode chamber  25  is located in the second portion  21   b  of the cathode  21 . 
         [0036]    Please refer to  FIGS. 1 and 2 . Inside the first portion  21  a of the cathode  21 , there are the first flow channel  23   a , the second flow channel  23   b , the flow channel holes  23   c , the first portion  25   a  of the cathode chamber  25  and the chamber inlet  27   a . The chamber outlet  27   b  is located inside the anode  11  and below the second portion  25   b  of the cathode chamber  25 . 
         [0037]    Please refer to  FIG. 2 . The cathode discharge apparatus  10 A may include the electrical feedthrough  41  and the power supply  43 . The electrical feedthrough  41  is electrically connected with the cathode  21 . The power supply  43  provides power to the cathode  21  via the electrical feedthrough  41 . 
         [0038]    It can be seen in  FIG. 1  that the cathode  21  and the anode  11  are separated by several insulators  22 . The cathode discharge apparatus  10 A may include the electrical feedthroughs  41   a  and  41   b , several vacuum sockets  44   a - f  plugged with the electrical feedthroughs  41   a  and  41   b , and the electrode connecting element  42 . The power supply  43  in  FIG. 2  (not shown in the  FIG. 1 ) is electrically connected with the electrode connecting element  42 , and can provide power to the cathode  21  via the electrode connecting element  42  and the electrical feedthroughs  41   a  and  41   b.    
         [0039]    Please refer to  FIG. 1  again. The working gas  26  is fed into the first flow channel  23   a  via the flow channel inlets  24   a  and  24   b  in two ends, and flows successively through several flow channel holes  23   c , the second flow channel  23   b  and the chamber inlets  27   a  into the cathode chambers  25 . The working gas  26  inside the cathode chambers  25  can be ionized to generate the plasma  5  (shown in  FIG. 2 , not in  FIG. 1 ), which is injected through the chamber outlets  27   b.    
         [0040]    The first portion  25   a  and the second portion  25   b  of the cathode chamber  25  can be designed to have the shapes of cylinder, cone, cuboid and pyramid. In this embodiment, the cylinder shape is chosen. The cross section area of the second portion  25   b  of the cathode chamber  25  can be larger than that of the first portion  25   a  of the cathode chamber  25 . Therefore, the plasma will be expanded when flowing into the second portion  25   b  of the cathode chamber  25 , and will be injected through the chamber outlet  27   b . On the other hand, the cross section areas of these two portions can be equal. 
         [0041]    The first flow channel  23   a  and the second flow channel  23   b  can be designed to be parallel or unparallel to each other. The working gas is usually selected from a group consisting of hydrogen, helium, argon, oxygen, nitrogen, ammonia and silane, based on the desired coating material. For instance, the ammonia and the silane are chosen when the desired coating material is silicon nitride; the silane is chosen when the desired coating material is silicon. The argon is inert gas, can not be reacted with other material easily, and can be used to generate the plasma. 
         [0042]    Although the working gas  26  is fed via the flow channel inlets  24   a  and  24   b  in the two ends, the pressure in the second flow channel  23   b  can be evenly distributed. Due to the design of the first flow channel  23   a , the second flow channel  23   b  and the flow channel holes  23   c  in this embodiment, the working gas  26  will flow into the second flow channel  23   b  via the flow channel holes  23   c  after the working gas  26  has saturated the first flow channel  23   a . The working gas pressure is uniformly distributed in any portion of the second flow channel  23   b  owing to the design of the distributed flow channel holes  23   c.    
         [0043]    In the conventional technique, there is only one flow channel. Thus, the gas pressure in the portions of the flow channel close to he flow channel inlets in the two ends will be much higher than that in the center portion of the flow channel. Accordingly, the working gas pressure inside the cathode chambers  25  close to two ends will be much higher than that inside the cathode chambers  25  located in the center portion. The working gas pressure inside the cathode chambers has the strong influence on the plasma density, which in turn would strongly affect the thickness and the density of the coating film. In the conventional technique, the variation of the plasma density along the whole tier of cathode chambers is quite large, especially when the tubular cathode is quite long and quantity of the cathode chambers is very large for large area deposition. That is to say, the uniformity problem of the plasma density becomes quite serious for the large area deposition by using the conventional techniques. 
         [0044]    In this embodiment, the working gas pressure in any portion of the second flow channel  23   b  is evenly distributed due to the design of the first flow channel  23   a , the second flow channel  23   b  and the flow channel holes  23   c . Accordingly, the working gas pressure in each of cathode chambers  25  is almost equal, so the uniformity of the plasma density can be greatly improved to solve the problem of the conventional technique, and thus the present invention can successfully conquer the technical bottleneck of the large area deposition. 
       Second Embodiment 
       [0045]    The cathode discharge apparatus of the present embodiment is almost identical to that in the first embodiment. The only difference between the present embodiment and the first embodiment is: in the first embodiment, the cathode chambers  25  are designed to be parallel to one another and are oriented vertically downward, so the plasma is injected vertically downward via the chamber outlets  27   b ; while in the present embodiment, the cathode chambers  25  are designed to tilt at an angle relative to the vertical direction. The  FIG. 3  is the schematic diagram showing the cross section of the cathode discharge apparatus according to the second embodiment of the present invention. The difference between the present embodiment and the first embodiment can be told by referring to  FIGS. 2 and 3  simultaneously. The cathode chambers of the present embodiment tilts at a small angle, e.g. 5-30 degree, relative to the vertical direction, and can be aligned in a way, where the odd-numbered cathode chambers tilt counterclockwise at a small angle, e.g. −12 degree; while the even-numbered cathode chambers tilt clockwise at a small angle, e.g. +12 degree. This design of the present embodiment can expand the injected area by the plasma. 
         [0046]    Third Embodiment 
         [0047]    Please refer to  FIG. 4 , which is the schematic diagram showing the cross section of the cathode discharge apparatus according to the third embodiment of the present invention. In this embodiment, the cathode discharge apparatus  100  includes an anode  110  and two cathodes  121   a  and  121   b , where the structure of each cathode is almost the same as that of the first embodiment. That is to say, two parallel aligned tubular cathodes  121   a  and  121   b  are enclosed inside the anode  110 , and share the single anode  110 . The two cathodes  121   a  and  121   b  have the electrical feedthroughs  141   a  and  141   b , respectively. The cathode discharge apparatus  100  can contain the electrode connecting element  142  and the power supply  143 , both of which are electrically connected, and the power supply  143  can provide power to the cathodes  121   a  and  121   b  through the electrode connecting element  142  and the electrical feedthroughs  141   a  and  141   b.    
         [0048]      FIG. 5  is the schematic diagram showing the 3-dimensinal view of the cathode discharge apparatus according to the third embodiment of the present invention. General speaking, the portion of the cathode close to the power input point, i.e. the position of the electrical feedthroughs, have the higher received power than the portion of the cathode far away from the power input point. Please refer to  FIG. 5 . In this embodiment, the electrical feedthrough  141   a  is located close to one end of the cathode  121   a , which is not shown in  FIG. 5 , and the electrical feedthrough  141   b  is located close to the opposite end of the cathode  121   b , which is not shown in  FIG. 5 . 
         [0049]    Since the electrical feedthroughs  141   a  and  141   b  are located close to two ends of the cathodes  121   a  and  121   b , the power density can be well balanced through the two cathodes  121   a  and  121   b , and the uniformity of the plasma can be well improved, especially for the large area coating. The cathode discharge apparatus  100  in  FIG. 5  can further contain several vacuum sockets  144 , which positions can be adjusted according to the practical necessity so as to reach the optimum uniformity of the power distribution by taking the consideration of the influence of the input power quantity on the power distribution. 
         [0050]    Fourth Embodiment 
         [0051]    Please refer to  FIG. 6 , which is the schematic diagram showing the cross section of the cathode discharge apparatus according to the fourth embodiment of the present invention. In this embodiment, the cathode discharge apparatus  200  includes two cathode discharge units  210   a  and  210   b , each of which has almost the same structure as that of the cathode discharge apparatus  10 A in the first embodiment. That is to say, it looks like that two cathode discharge apparatuses  10 A are aligned in parallel. The two cathode discharge units  210   a  and  210   b  have the electrical feedthroughs  241   a  and  241   b , respectively. The cathode discharge apparatus  200  contains the electrode connecting element  242  and the power supply  243 , both of which are electrically connected, and the power supply  243  can provide the power to the cathodes of the cathode discharge units  210   a  and  210   b  through the electrode connecting element  242  and the electrical feedthroughs  241   a  and  241   b.    
         [0052]      FIG. 7  is the schematic diagram showing the 3-dimensinal view of the cathode discharge apparatus according to the fourth embodiment of the present invention. General speaking, the portion of the cathode close to the power input point, i.e. the position of the electrical feedthrough, has the higher received power than the portion of the cathode far away from the power input point. Please refer to  FIG. 7 . In this embodiment, the electrical feedthrough  241   a  is located close to one end of the cathode discharge unit  210   a , which is not shown in  FIG. 7 , and the electrical feedthrough  241   b  is located close to the opposite end of the cathode discharge unit  210   b , which is not shown in  FIG. 7 . 
         [0053]    Since the electrical feedthroughs  241   a  and  241   b  are located close to two ends of the cathode discharge units  210   a  and  210   b , the power density can be well balanced through the two cathode discharge units  210   a  and  210   b , and the uniformity of the plasma can be well improved, especially for the large area coating. The cathode discharge apparatus  200  in  FIG. 7  can further contain several feedthrough sockets  244 , which positions can be adjusted according to the practical necessity so as to reach the optimum uniformity of the electrical power distribution. 
         [0054]    To sum up, the new cathode discharge apparatus with the novel technical concept and design in the present invention can provide the uniform power to each portion of the cathode, and can provide the working gas with the uniform pressure in each of cathode chamber so as to reach the uniform distribution of the whole plasma. Therefore, the problem of the poor plasma distribution for the large area coating in the current technologies can be solved, and the technical bottleneck for the large area coating can be successfully conquered. The present invention can contribute the great benefits for those industries hungering for the large area coating technology, e.g. the industries of liquid crystal displays, solar cells, etc., and can farther make great contributions to the environmental conservation. 
         [0055]    While the invention has been described in terms of what is presently considered to be the most practical embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.