Abstract:
The present invention aims to provide a technology, which uses an apparatus having a simple configuration to efficiently form a film with uniform film thickness and film quality when continuously forming a film by vacuum deposition of highly reactive lithium. A vacuum deposition system of the present invention has a vacuum deposition chamber wherein an evaporation material is deposited on a substrate by deposition, a substrate supplying/replacing system, connected to the vacuum deposition chamber, for performing supplying and replacing the substrate to and from the vacuum deposition chamber, and a material supplying/replacing system, connected to the vacuum deposition chamber, for performing the supplying and the replacing of the evaporation material to and from the vacuum deposition chamber.

Description:
[0001]    This application is a continuation of International Application No. PCT/JP2010/57011, filed on Apr. 20, 2010, which claims priority to Japan Patent Application No.2009-103431, filed on Apr. 21, 2009. The contents of the prior applications are herein incorporated by references in their entireties. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention is related to a technology for manufacturing a lithium secondary battery using a solid electrolyte; and in particular, a technology for forming an anode layer by vacuum deposition. 
         [0004]    2. Description of the Background Art 
         [0005]    Conventionally, a lithium ion secondary battery has been widely known as a power source for mobile phones and personal computers. 
         [0006]    However, since lithium ion secondary batteries use liquid electrolytes, liquid leakage and fires may occur, which poses a problem regarding their safety. 
         [0007]    For this reason, recently, all-solid lithium secondary batteries, which use a solid material as the material for the electrolytes, have been proposed, and are being developed. 
         [0008]    In particular, as an all-solid lithium secondary battery using a solid material, an all-solid lithium secondary battery made of a thin film shows promise for use as a power source of card-type electronic components or the like. 
         [0009]    In an all-solid lithium secondary battery made of a thin film, an anode consisting of lithium (Li) is formed by vacuum deposition. However, since lithium is a material that is highly reactive to water and air, when an evaporation material consisting of lithium is brought into a deposition chamber, it is necessary to pay sufficient attention to atmosphere of transport pathways. 
         [0010]    Furthermore, in a conventional technology, in the case of continuously forming films by vacuum deposition of lithium, the film thickness is controlled by using a shutter mechanism or a film thickness monitor. However, in such a conventional technology, the structural arrangement of the apparatus is complicated; and also, the film thickness or film quality may change as a result of deterioration of lithium due to changes in the lithium over time, changes in the atmosphere, or the like. 
         [0011]    As a prior art document related to the present invention, see JP-A 2007-214109. 
       SUMMARY OF THE INVENTION 
       [0012]    The present invention was created in consideration of the above-described problems in the conventional technology, aiming to provide a technology, by use of an apparatus having a simple configuration, which can efficiently form films with uniform film thickness and film quality, when continuously forming films by vacuum deposition of highly reactive lithium. 
       Means for Solving the Problem 
       [0013]    The present invention, which was created to solve the above-described problems, is a vacuum deposition system having a vacuum deposition chamber in which an evaporation material is deposited on a substrate by deposition, a substrate supplying/replacing system, which is connected to the vacuum deposition chamber, for performing supply and replacement of the substrate between the vacuum deposition chamber and the substrate supplying/replacing system, and a material supplying/replacing system, which is connected to the vacuum deposition chamber, for performing supply and replacement of the evaporation material between the vacuum deposition chamber and the material supplying/replacing system, wherein the material supplying/replacing system is provided with a material loading region in which the evaporation material is disposed in an evaporation container in an atmosphere that is blocked from ambient air, and an evaporation container transport region in which the evaporation container is transported to and from the vacuum deposition chamber, and wherein a heating means for heating the evaporation container, supplied from the material supplying/replacing system, is provided within the vacuum deposition chamber. 
         [0014]    In the present invention, the material supplying/replacing system is also effective when it has a material loading chamber in which the evaporation material is disposed in the evaporation container in a dry atmosphere that is blocked from ambient air, and a material supplying/replacing chamber which is connected to the material loading chamber and in which supply and replacement of the evaporation material is performed to and from the vacuum deposition chamber in a vacuum. 
         [0015]    In the present invention, the heating means is also effective when it is a heater of lamp-heating mechanism. 
         [0016]    Further, the present invention is a method of vacuum deposition with the use of one of the above-described vacuum deposition systems, including the steps of disposing a predetermined amount of an evaporation material in the evaporation container in the material loading region, transporting the evaporation container from the material loading region into the inside of the vacuum deposition chamber and supplying the evaporation material, performing vacuum deposition on the substrate by heating the evaporation container within the vacuum deposition chamber, and then ejecting the evaporation container from the vacuum deposition chamber after the completion of the vacuum deposition to return it to the material loading region of the material supplying/replacing system. 
         [0017]    In the present invention, it is also effective when the supply and the replacement of the evaporation material is performed with the use of a container transport member, to which a plurality of the evaporation containers can be mounted so as to be capable of being attached and removed at will, to transport the container transport member. 
         [0018]    The present invention is most effective when the evaporation material consists of lithium. 
         [0019]    In the case of the apparatus of the present invention, it has a substrate supplying/replacing system, which is connected to the vacuum deposition chamber, for performing the supply and the replacement of the substrate between the vacuum deposition chamber and the substrate supplying/replacing system, and a material supplying/replacing system, which is connected to the vacuum deposition chamber, for performing the supply and the replacement of the evaporation material between the vacuum deposition chamber and the material supplying/replacing system; and the material supplying/replacing system is provided with a material loading region in which the evaporation material is disposed in an evaporation container in a dry atmosphere that is blocked off to ambient air, and an evaporation container transport mechanism which transports the evaporation container to and from the vacuum deposition chamber. Consequently, moisture or the like is prevented from attaching to the evaporation material and the evaporation container; and thus, deterioration of the evaporation material can be prevented, when transporting a highly reactive lithium evaporation material into the vacuum deposition chamber, and when returning the evaporation container from the vacuum deposition chamber to the material supplying/replacing system after the completion of deposition. 
         [0020]    According to the present invention, a heating means for heating the evaporation container supplied from the material supplying/replacing system is provided within the vacuum deposition chamber; and by heating the evaporation container to apply vacuum deposition on the substrate, the evaporation material can be heated rapidly and the evaporation container can be cooled rapidly after the completion of the deposition. 
         [0021]    In the present invention, since the evaporation material can be completely used up during deposition, by setting the amount of evaporation material, for example, to an amount which will completely evaporate in one deposition process, a thin film of a desired film thickness can be formed with an apparatus having a simple configuration, without using a shutter or a film thickness monitor. Further, deterioration of the lithium evaporation material, particularly caused by changes over time or changes in the atmosphere, can be unfailingly prevented. 
         [0022]    Further, in the method of the present invention, after deposition using an evaporation container accommodating lithium, for example, the evaporation material can be supplied in a state in which the inside of the vacuum deposition chamber is in a high vacuum, by repeating the step of returning the evaporation container to the material loading region. 
         [0023]    In the method of the present invention, if the evaporation material is supplied and replaced with the use of a container transport member to which a plurality of the evaporation containers can be mounted and capable of being attached and removed at will, to transport the container transport member, the efficiency of each step can be greatly increased, since the plurality of evaporation containers can be transported collectively to supply and replace the evaporation material. 
       EFFECTS OF THE INVENTION 
       [0024]    According to the present invention, a film with uniform film thickness and film quality can be efficiently formed with the use of an apparatus having a simple structural arrangement, when continuously forming films by vacuum deposition of highly reactive lithium. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]      FIG. 1  is a schematic front view of an embodiment of the vacuum deposition system according to the present invention. 
           [0026]      FIG. 2(   a ) is a plan view of a tray main body showing an example of a material transport tray used in the embodiment. 
           [0027]      FIG. 2(   b ) is a plan view showing a state in which an evaporation container is mounted to the material transport tray. 
           [0028]      FIG. 2(   c ) is a cross-sectional view along the line A-A of  FIG. 2(   b ). 
           [0029]      FIG. 3  is an explanatory diagram ( 1 ) showing one example of a deposition process in the embodiment. 
           [0030]      FIG. 4  is an explanatory diagram ( 2 ) showing one example of a deposition process in the embodiment. 
           [0031]      FIG. 5  is an explanatory diagram ( 3 ) showing one example of a deposition process in the embodiment. 
           [0032]      FIG. 6  is an explanatory diagram ( 4 ) showing one example of a deposition process in the embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0033]    A preferred embodiment of the present invention will be explained in detail below in reference to the drawings. 
         [0034]      FIG. 1  is a schematic front view of an embodiment of the vacuum deposition system according to the present invention. 
         [0035]    As shown in  FIG. 1 , a vacuum deposition system  1  used in the present embodiment has a vacuum deposition chamber  2  connected to a vacuum evacuation system, which is not illustrated. The vacuum deposition chamber  2  is constituted so as to introduce, for example, argon (Ar) gas, which is a noble gas. 
         [0036]    A substrate holder  20  for holding a substrate  50  is provided in the upper portion within the vacuum deposition chamber  2 . The substrate holder  20  is constituted so as to rotate the substrate  50  in a state of being oriented to the horizontal direction by means of, for example, a driving motor  21  disposed in the upper portion of the vacuum deposition chamber  2 . 
         [0037]    Meanwhile, a heater (heating means)  22  for heating an evaporation material  10  accommodated inside an evaporation container  7 , to be explained later, is disposed on a lower portion within the vacuum deposition chamber  2 . 
         [0038]    In the present invention, although not particularly limited, it is preferable, from the viewpoint of rapidly heating the evaporation material  10  and rapidly cooling the evaporation container  7 , to use a heater of lamp-heating mechanism as the heater  22  so that the evaporation container  7 , which accommodates the evaporation material  10 , is heated indirectly from a predetermined distance, as will be explained below. 
         [0039]    In the present embodiment, a substrate supplying/replacing system  3  for performing supply and replacement of the substrate  50  between the vacuum deposition chamber  2  and the substrate supplying/replacing system  3 , and a material supplying/replacing system  4  for performing the supply and the replacement of the evaporation material  10  between the vacuum deposition chamber  2  and the material supplying/replacing system  4 , are connected to the vacuum deposition chamber  2 . 
         [0040]    The substrate supplying/replacing system  3  has a substrate transport chamber  31  which is connected to the vacuum deposition chamber  2  via a gate valve  30 . 
         [0041]    The substrate transport chamber  31  is formed into, for example, a vertically long shape and is connected to the vacuum evacuation system, which is not illustrated. A substrate transport robot  32 , which can move up and down with the substrate  50  being placed thereon, is disposed within the substrate transport chamber  31 . 
         [0042]    In the present embodiment, a substrate loading chamber  34  is connected via a gate valve  33  to, for example, the upper-side portion of the substrate transport chamber  31 ; and a substrate removal chamber  36  is connected via a gate valve  35  to, for example, the lower-side portion of the substrate transport chamber  31 . 
         [0043]    The substrate loading chamber  34  and the substrate removal chamber  36  are both connected respectively to the vacuum evacuation system, which is not illustrated. 
         [0044]    Meanwhile, the material supplying/replacing system  4  has a material replacing chamber  43  connected to the vacuum deposition chamber  2  via a gate valve  40 . The material replacing chamber  43  is connected to the vacuum evacuation system which is not illustrated, and is divided into a first material replacing chamber  41  and a second material replacing chamber  42 . 
         [0045]    The material replacing chamber  43  is constituted so as to introduce, for example, argon (Ar) gas. 
         [0046]    A tray transport robot  44  for supplying/replacing a material transport tray (container transport member)  6  is provided within the first material replacing chamber  41  adjacent to the vacuum deposition chamber  2 . 
         [0047]    A material loading chamber (material loading region)  45  explained later is connected to the second material replacing chamber  42  via a gate valve  46 . 
         [0048]      FIGS. 2(   a ) to ( c ) illustrate an example of the material transport tray used in the present embodiment:  FIG. 2(   a ) is a plan view of the tray main body;  FIG. 2(   b ) is a plan view illustrating a state in which evaporation containers are mounted to the tray main body; and  FIG. 2(   c ) is a cross-sectional view along the line A-A of  FIG. 2(   b ). 
         [0049]    As shown in  FIG. 2(   a ), the material transport tray  6  of the present embodiment has a tray main body  60  made of, for example, a flat plate member. 
         [0050]    As the material of the tray main body  60 , for example, an inorganic material (such as, silica glass), a metal material (such as, stainless steel), a carbon material or the like can be used. 
         [0051]    A plurality of mounting holes  61  in the shape of, for example, a circle, for mounting the evaporation containers (boats)  7  are provided on the tray main body  60  so as to penetrate through the tray main body  60 . 
         [0052]    In the present example, 3×3=nine mounting holes  61  are provided in a matrix on the tray main body  60 . 
         [0053]    In the present example, the evaporation container  7  made of, for example, a metal material (such as, stainless steel), and has a hull part  70  in an approximately cup-shape (a cylindrical shape with a bottom); and on an edge portion of the opening of the hull part  70 , a ring-shaped flange  71  in the shape of, for example, a ring, is provided. 
         [0054]    The hull part  70  of the evaporation container  7  has an outer diameter that is slightly smaller than that of the mounting holes  61  of the tray main body  60 , and the flange  71  is formed with a slightly larger diameter than that of the mounting holes  61  of the tray main body  60 . 
         [0055]    Due to such constitution, when the hull parts  70  of the evaporation containers  7  are inserted from above into the mounting holes  61  of the tray main body  60 , the flanges  71  of the evaporation containers  7  abut on the surface of the tray main body  60 , so that each of the evaporation containers  7  is positioned in a predetermined position. 
         [0056]    As shown in  FIG. 2(   c ), the material transport tray  6  of the present embodiment is such that the evaporation materials  10  are inserted to be placed with each of the evaporation containers  7  being mounted to the tray main body  60 ; and thereby, each of the evaporation materials  10  is transported in a state of being accommodated in each of the evaporation containers  7 , along with the tray main body  60 . 
         [0057]    In the present embodiment, the evaporation materials  10  are supplied to the material transport tray  6  within the above-described material loading chamber  45  (see,  FIG. 1 ). 
         [0058]    The material loading chamber  45  is composed of a glove box that can be handled by a human hand. 
         [0059]    The dew point temperature within the material loading chamber  45  can be maintained at the extent of −50° C. to −60° C.; and a dry atmosphere that is blocked off to ambient air can be maintained by introducing, for example, argon (Ar) gas into the material loading chamber  45 . 
         [0060]    In the material loading chamber  45 , the evaporation materials  10  consisting of lithium having a predetermined size and shape (for example, a particle shape) are inserted into the evaporation containers  7  mounted to the tray main body  60  by human hand, for example, one at a time. 
         [0061]    In the case of the present invention, the amount of the evaporation material  10  accommodated in each of the evaporation container  7  is not particularly limited, but from the viewpoint of preventing film thickness or film qualities from changing due to changes over time or the like, it is preferable to set it to an amount which can completely evaporate in one deposition step. 
         [0062]    The amount of evaporation material  10  accommodated in each of the evaporation container  7  can be appropriately modified, depending on size of the substrate or the positions of the evaporation containers  7  on the tray main body  60  or the like. 
         [0063]    A plurality of material transport trays  6 , with the evaporation materials  10  being accommodated in each of the evaporation containers  7  are mounted on a material supply cassette  8  and stored within the material loading chamber  45 . 
         [0064]    If needed, the material supply cassette  8  is transported into the second material replacing chamber  42  by human hand. 
         [0065]    A material cassette raising/lowering mechanism  47  for raising and lowering the material supply cassette  8  is provided at a lower part within the second material replacing chamber  42 . 
         [0066]    The material cassette raising/lowering mechanism  47  has a stage  47   a,  which is driven in an up-down direction by, for example, a drive motor  48  provided at a lower part of the second material replacing chamber  42 ; and the material cassette raising/lowering mechanism  47  is configured to raise and lower the stage  47   a  in a state of, for example, mounting to support one material supply cassette  8 . 
         [0067]      FIGS. 3 to 6  are explanatory diagrams illustrating one example of a deposition process in the present embodiment. 
         [0068]    As shown in  FIG. 3 , when carrying out deposition of the evaporation material  10  consisting of lithium on the substrate  50  in the present embodiment, the substrate  50 , which has been transported into the substrate transport chamber  31  via the substrate loading chamber  34 , is transported into the vacuum deposition chamber  2  by the substrate transport robot  32  to be mounted onto the substrate holder  20 . 
         [0069]    In the meantime, the material supply cassette  8 , with the evaporation materials  10  having been mounted onto the material transport tray  6  in advance, is transported into the second material replacing chamber  42  by human hand. With the use of the tray transport robot  44 , one material transport tray  6  at a predetermined position (in this example, the one at the top rank) is transported into the vacuum deposition chamber  2  via the first material replacing chamber  41 ; and the material transport tray  6  is then positioned at a predetermined film-forming position within the vacuum deposition chamber  2 , for example, a position above and separated from the heater  22 . 
         [0070]    In this state, the pressure within the vacuum deposition chamber  2  is adjusted to a predetermined value; and as shown in  FIG. 4 , all of the evaporation materials  10  in the evaporation containers  7  are evaporated to form a lithium layer on the substrate  50  by operating the heater  22  to heat the evaporation materials  10  via the evaporation containers  7 . 
         [0071]    In this process, the deposition is carried out with the drive motor  21  being operated so as to rotate the substrate  50  toward the horizontal direction. 
         [0072]    From the viewpoint of performing efficient continuous deposition, for example, as shown in  FIG. 4 , it is preferable to transport the substrate  50 , which is next in line to be subjected to deposition, into the substrate loading chamber  34  in advance during deposition. 
         [0073]    Also, from the viewpoint of performing efficient continuous deposition, for example, as shown in  FIG. 4 , it is preferable to carry out the insertion work of the evaporation materials  10  into the evaporation containers  7  mounted to the tray main body  60  within the material loading chamber  45  as appropriately needed. 
         [0074]    After the completion of the deposition process, as shown in  FIG. 5 , the substrate  50  which has been detached from the substrate holder  20  is transported into the substrate transport chamber  31  by the substrate transport robot  32 . 
         [0075]    Further, the substrate transport robot  32  is lowered, in order that the substrate  50  is transported into the substrate removal chamber  36  via a gate valve  35 ; and then the substrate  50  is discharged from the substrate removal chamber  36  with the use of a substrate transport robot, which is not illustrated. 
         [0076]    On the other hand, the material transport tray  6  with all the evaporation materials  10  having been used up is transported from the vacuum deposition chamber  2  into the second material replacing chamber  42  via the first material replacing chamber  41  with the use of the tray transport robot  44 , and then mounted at its original position, at the top rank of the material supply cassette  8 . 
         [0077]    Subsequently, as shown in  FIG. 6 , the substrate transport robot  32  is raised in the substrate transport chamber  31 , in order that the substrate  50  within the substrate loading chamber  34  be transported into the vacuum deposition chamber  2  via the substrate transport robot  32  and then mounted to the substrate holder  20 . 
         [0078]    In the meantime, the drive motor  48  is operated to raise the cassette raising/lowering mechanism  47  within the second material replacing chamber  42 ; and then the material transport tray  6  at, for example, the middle rank of the material supply cassette  8  is transported into the vacuum deposition chamber  2  via the first material replacing chamber  41  with use of the tray transport robot  44 . This material transport tray  6  is then positioned at a film-forming position within the vacuum deposition chamber  2 , for example, a film-forming position above the heater  22 . 
         [0079]    As explained above, inside the vacuum deposition chamber  2 , the heater  22  is operated to heat the evaporation materials  10  via the evaporation containers  7 , so that all of the evaporation materials  10  within each of the evaporation containers  7  are evaporated to form a Li layer on the substrate  50 . 
         [0080]    After the completion of the deposition, the above-described process is repeated. In other words, the substrate  50  upon which deposition has been completed is transported into the substrate removal chamber  36  via the substrate transport chamber  31  with the use of the substrate transport robot  32 , and then the substrate  50  is discharged from the substrate removal chamber  36 . 
         [0081]    Also, the material transport tray  6  to which the deposition has been completed is transported from the vacuum deposition chamber  2  into the second material replacing chamber  42  via the first material replacing chamber  41  with the use of the tray transport robot  44 , and then mounted to its original position of the material supply cassette  8 . 
         [0082]    Afterwards, when all of the evaporation materials  10  on the material transport tray  6  of the material supply cassette  8  within the second material replacing chamber  42  have been used up, the material supply cassette  8  is returned to the material loading chamber  45  by human hand; and a new material supply cassette  8  is transported into the second material replacing chamber  42  by human hand. 
         [0083]    Then, the above-described process is repeated. 
         [0084]    The evaporation containers  7  as to which a deposition has been completed should be washed with the use of pure water. 
         [0085]    The lithium can be efficiently and almost completely removed with the use of pure water. 
         [0086]    The present embodiment includes a substrate supplying/replacing system  3 , which is connected to the vacuum deposition chamber  2 , for performing the supply and the replacement of the substrate  50  between the vacuum deposition chamber  2  and the substrate supplying/replacing system  3 , and a material supplying/replacing system  4 , which is connected to the vacuum deposition chamber  2 , for performing the supply and the replacement of the evaporation material  10  between the vacuum deposition chamber  2  and the material supplying/replacing system  4 ; and the material supplying/replacing system  4  has a material loading region (material loading chamber  45 ) in which the evaporation material  10  is disposed in the evaporation container  7  in a dry atmosphere that is blocked off to ambient air, a tray transport robot  44  which transports the evaporation container  7  to and from the vacuum deposition chamber  2 , which leads moisture or the like to be prevented from attaching to the evaporation material  10  and the evaporation container  7 , and thereby deterioration of the evaporation material  10  can be prevented, when transporting the evaporation material  10 , consisting of highly reactive lithium, into the vacuum deposition chamber  2 , and when returning the evaporation container  7  from the vacuum deposition chamber  2  to the material supplying/replacing system  4  after the completion of deposition. 
         [0087]    Further, according to the present embodiment, a heater  22  for heating the evaporation containers  7  supplied from the material supplying/replacing system  4  is provided within the vacuum deposition chamber  2 ; and by heating the evaporation containers  7  to perform vacuum deposition on the substrate  50 , the evaporation materials  10  can be rapidly heated, and the evaporation containers  7  can be rapidly cooled after the completion of the deposition. 
         [0088]    In the case of the present embodiment, since the evaporation material  10  can be completely used up during deposition, a film of a desired film thickness can be formed with the use of an apparatus having a simple configuration without using a shutter or a film thickness monitor, by setting the amount of evaporation material  10 , for example, to an amount which will completely evaporate in one deposition step. Further, deterioration of the evaporation material  10  consisting of lithium particularly caused by changes over time or changes in the atmosphere can be reliably prevented. 
         [0089]    In addition, as in the present embodiment, after deposition with the use of the evaporation containers  7  accommodating lithium, for example, by repeating the step of returning the evaporation containers  7  to the material loading chamber  45 , the evaporation materials  10  can be supplied in a state in which the inside of the vacuum deposition chamber  2  is in a high vacuum. 
         [0090]    Meanwhile, in the present embodiment, since the evaporation materials  10  are supplied and replaced by transporting the material transport tray  6 , to which a plurality of evaporation containers  7  can be mounted capable of being attached and removed at will, the plurality of evaporation containers  7  can be transported collectively to supply and replace the evaporation materials  10 , and the efficiency of each step can be greatly increased. 
         [0091]    The present invention is not limited to the above-described embodiment, and various modifications can be made. 
         [0092]    For example, in the above-described embodiment, the evaporation containers  7  are mounted to the material transport tray  6  for supplying and replacing the evaporation materials  10 , but the present invention is not limited to this embodiment, and, for example, a transport robot or the like can be used to supply and replace a plurality of the evaporation containers  7 . 
         [0093]    However, from the view point of the efficiency in the deposition process, it is preferable to mount the evaporation containers  7  to the material transport tray  6  for supplying and replacing the evaporation materials  10  as in the above-described embodiment. 
         [0094]    Further, the arrangement formation of the chambers in the above-described embodiment is one example, and it can be appropriately modified in accordance with processes as needed. For example, the material supplying/replacing system can also be constituted as one large chamber. 
         [0095]    In addition, the present invention can be applied to substrates of various materials, shapes, and sizes (such as, a silicon substrate, a ceramic substrate, a heat-resistant resin substrate, a mica substrate or the like). 
         [0096]    Moreover, although the present invention can be applied to materials other than lithium, it is most effective in a technology for manufacturing a lithium secondary battery using lithium in an anode.