Abstract:
A gas shower device having gas curtain comprises a first gas shower unit for injecting a reaction gas, thereby forming a reaction gas region, and a second gas shower unit. The second gas shower unit arranged around a periphery of the first gas shower unit comprises a buffer gas chamber for providing a buffer gas, and a curtain distribution plate. The curtain distribution plate further comprises a plurality through holes for injecting the buffer gas, thereby forming a gas curtain around a periphery of the reaction gas region. In another embodiment, an apparatus for depositing film is provided by utilizing the gas shower device having gas curtain, wherein the gas curtain prevents the reaction gas in the reaction gas region from being affected directly by a vacuum pressure so that a residence time of reaction gas can be extended thereby increasing the utilization of reaction gas and film-forming efficiency.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application also claims priority to Taiwan Patent Application No. 101140760 filed in the Taiwan Patent Office on Nov. 2, 2012, the entire content of which is incorporated herein by reference. 
       TECHNICAL FIELD 
       [0002]    The present disclosure relates to a gas spraying technique, and more particularly, to a gas shower device with gas curtain and a film deposition apparatus using the same. 
       BACKGROUND 
       [0003]    In any current device for enabling a metal organic chemical vapor deposition (MOCVD) process, the showerhead design can be the major factor affecting the flow field uniformity and deposition rate in the MOCVD process. In recent years, showerheads are arranged at position at the top of a process chamber and covering an area corresponding to a wafer carrier inside the process chamber. Thereby, the showerheads that are disposed above the wafer carrier are used for spraying a reaction gas to a wafer loaded on the wafer carrier. 
         [0004]    In a MOCVD process for manufacturing light emitting diode (LED) epitaxial wafers, the flow field uniformity and residence time of the reaction gases that are being projected out of the showerheads are the key factors affecting the LED binning and production cost. That is, when the reaction gases inside the process chamber are distributed uniformly for a long period of residence time, not only the gas utilization ratio is improved, but also the MOCVD deposition rate is enhanced, and as a consequence, the power consumption and production cost are reduced. 
         [0005]    For a film deposition process, the use of conventional showerheads for spraying reaction gases can generally cause a flow stagnation zone to happen in the center area of a process chamber due to overly concentrated distribution of reaction gases, and also the wavelength uniformity at wafer edge can be adversely affected. Consequently, a conventionally means for controlling the spraying of reaction gases into a process chamber while pumping the reaction gases to be exhausted out of the process chamber through a side of the process chamber is used for improving the flow field uniformity in the process chamber. 
         [0006]    Nevertheless, although the flow field uniformity can be improved by the drawing of vacuum pump, the reaction gases are going to be drawn away from the wafer faster than it is intended in an ideal condition after the reaction gases is sprayed on the wafer. Thus, the residence time of the reaction gases inside the process chamber is shortened, and as a consequence, the utilization rate of the reaction gases is reduced and eventually the deposition rate is adversely affected. In addition, since the closer to the vacuum pump the reaction gases inside the process chamber will get more sparsely distributed, the wavelength uniformity at wafer edge can also be adversely affected. 
       SUMMARY 
       [0007]    The present disclosure relates to a gas shower device with gas curtain and a film deposition apparatus using the same, according to which there is a gas curtain being provided surrounding the showerheads of the gas shower device so as to be used for confining the spray of a reaction gas in a specific area for controlling the reaction gas inside a process chamber to reach a specific concentration and also increasing the residence time of the reaction gas inside a reaction zone of the process chamber Thereby, the utilization rate of the reaction gas is improved, the deposition rate is enhanced and thus the production cost can be reduced. 
         [0008]    In an exemplary embodiment, the present disclosure provides a gas shower device having gas curtain, which comprises a first gas shower unit for injecting a reaction gas, thereby forming a reaction gas region; and a second gas shower unit, arranged around a periphery of the first gas shower unit, further comprising: a buffer gas chamber for providing a buffer gas, and a being connected to the buffer gas chamber circumferentially furnished at the periphery of the first shower unit, and having a plurality of through-holes provided for letting the buffer gas to pass therethrough to generate a gas curtain surrounding the periphery of the process gas region. 
         [0009]    In another exemplary embodiment, the present disclosure provides a film deposition apparatus, which comprises: a process chamber, a first shower unit, a vacuum pump and a second shower unit; wherein, the first and the second shower units are arranged on top of the process chamber for injecting a reaction gas into the process chamber and thus forming a reaction gas region; the vacuum pump is arranged coupling to the process chamber for causing a vacuum negative pressure to build inside the process chamber; the second shower unit that is located on top of the process chamber is further being arranged surrounding the first shower unit and is further comprised of: a buffer gas chamber for providing a buffer gas, and a gas curtain distribution plate, being connected to the buffer gas chamber circumferentially furnished at the periphery of the first shower unit, and having a plurality of through-holes provided for letting the buffer gas to pass therethrough to generate a gas curtain surrounding the periphery of the process gas region. 
         [0010]    Further scope of applicability of the present application will become more apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the disclosure, are given by way of illustration only, since various changes and modifications within the spirit and scope of the disclosure will become apparent to those skilled in the art from this detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The present disclosure will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present disclosure and wherein: 
           [0012]      FIG. 1  is a sectional view of a gas shower device with gas curtain according to an embodiment of the present disclosure. 
           [0013]      FIG. 2A  is a sectional view of a distribution plate in a second shower unit according to an embodiment of the present disclosure. 
           [0014]      FIG. 2B  is a top view of a distribution plate in a second shower unit according to an embodiment of the present disclosure. 
           [0015]      FIG. 3  is a top view of a panel being formed as the integration of the distribution plates of the first and the second shower units according to an embodiment of the present disclosure. 
           [0016]      FIG. 4  is a sectional view of a film deposition apparatus according to an embodiment of the present disclosure. 
           [0017]      FIG. 5A  and  FIG. 5B  are schematic diagrams showing respectively a flow field inside a process chamber when there is no gas curtain existed and when there is gas curtain existed. 
           [0018]      FIG. 6  is a sectional view of a film deposition apparatus according to another embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing. 
         [0020]    Please refer to  FIG. 1 , which is a sectional view of a gas shower device with gas curtain according to an embodiment of the present disclosure. As shown in  FIG. 1 , the gas shower device  2  in this embodiment is comprised of: a first shower unit  20  and a second shower unit  21 , in which the first shower unit  20  is provided for injecting a reaction gas  90  and thus forming a reaction gas region  92 . In this embodiment, the first shower unit is configured with a reaction gas supply chamber  200  and a gas distribution plate  201 . Moreover, the reaction gas supply chamber  200  is formed with an accommodation space  2000  therein for receiving the reaction gas  90  that is being fed into the accommodation space  200  via at least one channel  202 ; and the gas distribution plate  201  is further configured with a plurality of gas holes  2010  for injecting the reaction gas  90  onto a substrate. In this embodiment, the first shower unit  20  is formed in a circular shape, and correspondingly, both the gas distribution plate  201  and the reaction gas supply chamber  200  are circular structures. It is noted that although the first shower unit is formed in a circular shape, but it is not limited thereby. In addition, the first shower unit  20  in the embodiment of  FIG. 1  is designed to provide only one kind of reaction gas, but it is also not limited thereby, and thus the first shower unit  20  can be designed to provide a plurality of reaction gases at the same time. 
         [0021]    The second shower unit  21  is arranged surrounding the periphery of the first shower unit  20 . In this embodiment, the first shower unit  20  is formed in a circular shape, and as a consequence, the second shower unit  21  should be formed as a ring that is connected to the circular first shower unit  20 . In addition, there is a cooling unit  22  to be arranged at a position between the first shower unit  20  and the second shower unit  21  that is used for cooling the first shower unit  20 . It is noted that the cooling unit  22  can be disposed at any position at will in the gas shower device of the present disclosure, and thus is not limited by the present embodiment. 
         [0022]    Moreover, the second shower unit  21  is further configured with a buffer gas chamber  210  and a curtain distribution plate  211 . The buffer gas chamber  210  that is arranged surrounding the first shower unit  20  is formed with an accommodation space  2100  for receiving a buffer gas  91 . The curtain distribution plate  211  is connected to the bottom of the buffer gas chamber  210  and is also arranged surrounding the first shower unit  20 . In  FIG. 1 , the curtain distribution plate  211  is configured with a plurality of through holes  212  that are provided for the buffer gas  92  to be injected therethrough, and thereby forming a gas curtain  93  surrounding a periphery of the reaction gas region  92 . The buffer gas can be the same gas as the reaction gas  90 , or can be some other kind of gas that is different from and is not react with the reaction gas, or can simply be an inert gas, such as nitrogen or helium, but is not limited thereby. 
         [0023]    In the embodiment shown in  FIG. 1 , each of the plural through holes  212  is a vertical via hole that is arranged parallel in a Z-axis direction. However, in another embodiment shown in  FIG. 2A , each of the plural through holes  212   a  can be a oblique via hole that is arranged formed an included angle with the Z-axis direction. Consequently, by the oblique through holes  212   a , the gas curtain induced from the injection of the curtain distribution plate  211  is a spiral gas curtain, as shown in  FIG. 2A . In the embodiments shown in  FIG. 1  and  FIG. 2A , the cross section of each of the through holes can be a circular or a polygon. Please refer to  FIG. 2B , which is a top view of a distribution plate in a second shower unit according to an embodiment of the present disclosure. In the embodiment shown in  FIG. 2B , the cross section of each of the trough holes  212 B is formed in a shape like a slit, and also can be used for generating a gas curtain. Similarly, each of the slit-like through holes  212   b  can also be a vertical via hole, as those shown in  FIG. 1 , or can be an oblique via hole, as those shown in  FIG. 2A . 
         [0024]    Please refer to  FIG. 3 , which is a top view of a panel being formed as the integration of the distribution plates of the first and the second shower units according to an embodiment of the present disclosure. In this embodiment, the gas distribution plate  201  of the first shower unit  20  is integrally formed with the curtain distribution plate  211  of the second shower unit  21 , by that the gas holes  2010  and the through holes  212  are formed on a same plate  23  in a manner that the via holes  231  that are located within an area defined by the dotted line  230  are arranged at positions corresponding to the first shower unit  20  for allowing the reaction gas to flow therethrough, and the via holes  232  located outside the area defined by the dotted line  230  are arranged at positions corresponding to the second shower unit  21  for allowing the buffer gas to flow therethrough. Thus, by the integrated plate  23  of  FIG. 3 , the buffer gas is able to flow through the via holes  232  and form a gas curtain enclosing the reaction gas region formed from the injection of the reaction gas through the via holes  231 . 
         [0025]    Please refer to  FIG. 4 , which is a sectional view of a film deposition apparatus according to an embodiment of the present disclosure. In the embodiment shown in  FIG. 4 , the film deposition apparatus  3  is a MOCVD device, but it is not limited thereby and thus can be a plasma enhanced chemical vapor deposition (PECVD) device, an atmosphere pressure chemical vapor deposition (APCVD) device, or a low pressure chemical vapor deposition (LPCVD) device for instance. As shown in  FIG. 4 , the film deposition apparatus  3  comprises: a process chamber  30 , a vacuum pump  31  and a gas shower device  2 , in which the process chamber  30  is formed with an processing space  300  where is provided for a platform  32  to be arranged therein while allowing the platform  32  to move up and down in a Z-axis direction. Accordingly, a substrate  94  that is to be processed is carried on the platform  32 , and in an embodiment, the substrate  94  can be an LED substrate. The vacuum pump  31  is arranged connecting to the openings formed respectively on two sides of the process chamber  30 , and used for causing a vacuum negative pressure to build inside the processing space  300  of the process chamber  30 . The gas shower device  2  is substantially the gas shower device shown in  FIG. 1 , and thus will not be described further herein. 
         [0026]    Operationally, a reaction gas  90  is injected into the processing space  300  of the process chamber  30  from a first shower unit  20  that is arranged on top of the process chamber  30 , by that a reaction gas region  92  is formed inside the processing space  300 . During the injection of the reaction gas  90  for forming the reaction gas region  92 , the vacuum pump  31  is activated for vacuuming the processing space  300  of the process chamber  30  for causing a vacuum negative pressure to build inside the process chamber  30 . Simultaneously, the second shower unit  21  drive a buffer gas  91  to flow from the buffer gas chamber  3100  to be projected out of the curtain distribution plate  211  through the plural through holes  212  so as to form a gas curtain  93  surrounding the reaction gas region  92 . As a consequence, due to the isolation enabled by the gas curtain  93 , the vacuum negative pressure caused by the vacuum pump  31  will have no affection upon the flowing of the reaction gas  90  inside the reaction gas region  92 , so that the residence time of the reaction gas  90  inside the process chamber  300  can be prolonged. In addition, also due to the shielding effect induced by the gas curtain  92 , the reaction gas  90  injected from the first shower unit  20  can maintain to flow vertically downward to the substrate  94  without being affected by the vacuum negative pressure caused by the vacuum pump  31 , which is beneficiary to the increasing of film deposition rate since the residence time of the reaction gas  90  inside the reaction gas region  92  is improved. It is noted that the improvement over the residence time of the reaction gas  90  inside the reaction gas region  92  is also beneficiary to the increasing of the utilization rate of the reaction gas  90 . 
         [0027]    Please refer to  FIG. 5A  and  FIG. 5B , which are schematic diagrams showing respectively a flow field inside a process chamber when there is no gas curtain existed and when there is gas curtain existed.  FIG. 5A  shows a flow field inside a process chamber without the protection of a gas curtain, while  FIG. 5B  shows a flow field inside a process chamber with the protection of a gas curtain. As shown in  FIG. 5A , in a condition when the flow of reaction gas  90  encounters the rotating platform  32  and is flowing without the protection of a gas curtain, there will be a great amount of reverse flow  95  being induced, which can easily be attracted by the vacuum negative pressure so as to flow out of the process chamber, and thus, the residence time of the reaction gas  90  inside the process chamber is reduced. On the other hand, as shown in  FIG. 5B , by the protection of the gas curtain, the amount of reverse flow is reduced so that the residence time of the reaction gas  90  is increased and thus both the gas utilization rate and the deposition rate can be improved. Please refer to  FIG. 6 , which is a sectional view of a film deposition apparatus according to another embodiment of the present disclosure. The film deposition apparatus of  FIG. 6  is constructed basically the same as the one shown in  FIG. 4 , but is different in that: in this embodiment of  FIG. 6 , the gas distribution plate of the first shower unit  20  is integrally formed with the curtain distribution plate of the second shower unit  21 , by that the g gas distribution plate and the curtain distribution plate are formed on a same plate  23  in a manner that the via holes  231 are arranged at positions corresponding to the first shower unit  20  for allowing the reaction gas  90  to flow therethrough so as to form a reaction gas region  92 , and the via holes  232  are arranged at positions corresponding to the second shower unit  21  for allowing the buffer gas to flow therethrough so as to formed a gas curtain  93  surrounding the periphery of the reaction gas region  92 . 
         [0028]    With respect to the above description then, it is to be realized that the optimum dimensional relationships for the parts of the disclosure, to include variations in size, materials, shape, form, function and manner of operation, assembly and use, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present disclosure.