Abstract:
A chemical vapor deposition apparatus is equipped to control the width of a gas discharge path between a susceptor and an inner surface of a chamber without having to resort to redesign and remanufacturing of the apparatus. The chemical vapor deposition apparatus includes: a chamber; a susceptor positioned inside the chamber and on which a substrate can be loaded; a shower head injecting a processing gas toward the substrate; and a guide unit detachably installed inside the chamber to guide the processing gas such that the processing gas injected from the shower head is discharged through a chamber hole formed in the chamber.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATION 
       [0001]    This application claims the benefit of Korean Patent Application No. 10-2009-0068831, Filed on Jul. 28, 2009, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to a semiconductor manufacturing apparatus for forming a thin layer, and more particularly to a chemical vapor deposition apparatus. 
         [0004]    2. Description of the Related Art 
         [0005]    Metal organic chemical vapor deposition (MOCVD) is a technique for depositing a thin layer onto a substrate by reacting, for example, a group-III gas and a group-V gas with the substrate in a heated reactor. Using MOCVD, it is possible to build up many thin layers with the ability to precisely control the thickness or chemical composition of each thin layer. As such MOCVD is widely used in semiconductor manufacturing processes. 
         [0006]    After forming a thin layer in a processing chamber of a reactor, the residual gas in the processing chamber is discharged out of the processing chamber. When the atmosphere temperature drops below the evaporation temperature of the residual gas being discharged, this could induce formation of undesired particles in the processing chamber. The undesired particles may drop onto the substrate in the processing chamber, and it would create difficulties in acquiring the thin layer having a uniform layer quality or a uniform layer thickness distribution. Also, these undesired particles could attach onto a gas discharge path, causing the warm-keeping effect. This warm-keeping effect refers to the temperature difference created between the preset and the actual temperatures of the processing chamber, and this temperature difference will negatively influence the quality of the thin layer. 
         [0007]    Furthermore, when uniform flow distribution of processing gas is not achieved, for example, due to a vortex generated in the gas discharge path, even more undesirable particles may be generated. One reason behind the causes of vortex generation is the improper width of the gas discharge path between the susceptor and the nearby wall of the processing chamber. 
         [0008]    In a conventional MOCVD apparatus, the width of the gas discharge path between the susceptor and the wall of the processing chamber is fixed by design such that it would not be possible to control the width of the gas discharging path. Therefore, when the fluid flow distribution of the processing gas in the chamber is not proper, it may become necessary that the apparatus be again designed and manufactured. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention provides a chemical vapor deposition apparatus having a constitution that can control the width of the gas discharge path between the susceptor and the wall of the processing chamber without again designing and manufacturing the chemical vapor deposition apparatus. 
         [0010]    According to an aspect of the present invention, a chemical vapor deposition apparatus includes: a chamber; a susceptor positioned inside the chamber and on which a substrate is loaded; a shower head injecting a processing gas toward the substrate; and a guide unit detachably installed inside the chamber to guide the processing gas such that the processing gas injected from the shower head is discharged through a chamber hole formed in the chamber. 
         [0011]    According to another aspect of the present invention, a guide unit is used in a chemical vapor deposition apparatus including a chamber, a susceptor positioned inside the chamber and on which a substrate is loaded, and a shower head injecting a processing gas toward the substrate, and the guide unit is detachably installed inside the chamber to guide the processing gas injected from the shower head to a chamber hole formed in the chamber. 
         [0012]    According to another aspect of the present invention, a method for controlling a discharge path of a chemical vapor deposition apparatus including a chamber, a susceptor positioned inside the chamber and on which a substrate is loaded, and a shower head injecting a processing gas toward the substrate, the method includes installing a guide unit guiding the processing gas to a chamber hole formed in the chamber in order to control the width of the discharge path through which the processing gas passes. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which: 
           [0014]      FIG. 1  is a cross-sectional view of a chemical vapor deposition apparatus according to an embodiment of the present invention showing a replaceable guide unit installed inside a chamber; 
           [0015]      FIG. 2  is a cross-sectional view of a chemical vapor deposition apparatus with a guide unit in place for purposes of eliminating substantially the irregular air flow inside a chamber according to an embodiment of the present invention; 
           [0016]      FIG. 3  is a cross-sectional view of a chemical vapor deposition apparatus with a subsidiary plate placed therein for purposes of eliminating substantially the irregular air flow inside a chamber according to an embodiment of the present invention; 
           [0017]      FIGS. 4-5  are cross-sectional views of a chemical vapor deposition apparatus according to an embodiment of the present invention showing opening of a chamber to replace a guide unit therein; 
           [0018]      FIG. 6  is cross-sectional view of a chemical vapor deposition apparatus showing a different size guide unit replaced in a chamber according to an embodiment of the invention manually or by a robot or by other ways of automated procedure; and 
           [0019]      FIG. 7  is a flowchart of a method for controlling the gas discharge path of a chemical vapor deposition apparatus according to an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    The present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the present invention are shown. The present invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. In the figures, the dimensions of layers and regions may be exaggerated for clarity of illustration. Like reference numerals in the drawings denote like elements. 
         [0021]      FIG. 1  is a cross-sectional view of a chemical vapor deposition apparatus according to an embodiment of the present invention showing a guide unit  610  (which can be replaced as it will be explained in more detail below with respect to  FIGS. 5-7 ) in place inside a chemical vapor deposition apparatus comprising a first chamber  100  and a second chamber  200 . The present embodiment is applicable to other various chemical vapor deposition apparatuses as well as a general MOCVD apparatus. 
         [0022]    As shown in  FIG. 1 , the first chamber  100  and the second chamber  200  are coupled to each other to form a chemical vapor deposition apparatus. The chemical vapor deposition apparatus is supplied with a main processing gas G 1  into the second chamber  200 , which could be a combination of any predetermined number of processing gases, and  FIG. 1  is designed to supply the main processing gas G 1  made of two types of processing gases. The first chamber  100  is formed with a first gas inlet  101  to supply a first processing gas and a second gas inlet (not shown in the cross-sectional view of  FIG. 1 ) to supply a second processing gas. The first and second gas inlets may be formed through the upper surface of the first chamber  100  as is the case with the first inlet  101  shown in  FIG. 1 . 
         [0023]    An inert gas inlet  102  may be formed through a side surface of the first chamber  100  to supply an inert gas G 2  into the second chamber  200 . 
         [0024]    A plurality of chamber holes  201  through a side surface of the second chamber  200  as shown in  FIG. 1  to exhaust the main processing gas G 1  and the inert gas G 2  residually remaining after forming a thin layer on the substrate S. 
         [0025]    A shower head  300  supplies the main processing gas G 1  toward the substrate S for forming a thin layer in the second chamber  200 . The main processing gas G 1  according to an embodiment of the present invention comprises a first processing gas and a second processing gas, and the product obtained by the reaction between the first and second processing gases is deposited on the substrate S to form a thin layer. The first processing gas could be a gas including a group-III element, and the second processing gas could be a gas including a group-V element according to an embodiment of the present invention. 
         [0026]    A first gas distribution space  310  receives the first processing gas introduced through the first gas inlet  101  and distributes it to a plurality of first gas supply pipes  330  into the second chamber  200 . A second gas distribution space  320  receives the second processing gas introduced through the second gas inlet (not shown in  FIG. 1 ) and distributes it to a plurality of second gas supply pipes  340  into the second chamber  200 . The first and second distribution spaces  310 ,  320  may be formed inside the shower head  300 . The first processing gas supplied through the first gas supply pipe  330  and the second processing gas supplied through the second gas supply pipe  340  are mixed to form the processing gas Gl. 
         [0027]    An inert gas injection unit  400  injects the inert gas G 2  into the second chamber  200  so as to accelerate the discharge of the processing gas G 1 . The inert gas injection unit  400  may be formed in a ring or doughnut shape encircling the shower head  300  at its outer circumference nearer to the sidewall of the first chamber  100 . The inert gas injection unit  400  has a plurality of penetration holes formed on the lower surface thereof. The inert gas G 2  is introduced through the inert gas inlet  102  to an inert gas room  401 , and the inert gas G 2  may be injected downwardly into the second chamber  200  through the plurality of penetration holes. 
         [0028]    The substrate S is loaded on an upper surface of the susceptor  500  so that a thin layer can be formed on the upper surface of the substrate. A heater (not shown) may be provided inside the susceptor  500 . 
         [0029]    To form a thin layer of uniform thickness, a rotating member  501  capable of rotating the susceptor  500  may be provided below the susceptor  500 . In an embodiment of the present invention as shown in  FIG. 1 , the substrate S and the susceptor  500  rotate as a single body. 
         [0030]    A guide unit  610  is placed inside the second chamber  200  to guide the processing gas G 1  and the inert gas G 2  remaining after the thin layer is formed into the chamber hole  201  through which the residual gases G 1 , G 2  are exhausted out of the second chamber. The portions of the guide unit  610  include a first wall portion  611  formed with a first wall portion hole  615 , a curved portion  612 , and a second wall portion  613 . 
         [0031]    As shown in  FIG. 1 , the first wall portion  611  is nearer to the sidewall of the second chamber  200 , and the second wall portion  613  is connected to the first wall portion  611  by the curved portion  612 . The second wall portion  613  is spaced apart by a distance d 1  from the first wall portion  611 . The guide unit  610  may be made of quartz and may resemble a tub shape. The second wall portion  613  is spaced apart by a predetermined distance from the susceptor  500  to avoid the friction that may be caused due to the rotating susceptor  500 . However, it is preferable that the distance between the second wall portion  613  and the rotating susceptor  500  be maintained as close to each other as possible so that the residual gas that ought to be exhausted out of the second chamber  200  is not introduced into the gap in between the second wall portion  613  and the susceptor  500 . 
         [0032]    The first wall portion hole  615  of the first wall portion  611  may be aligned with the chamber hole  201  of the second chamber  200  to allow a continuous path of the residual gas being exhausted. 
         [0033]    When the spacing dl between the second wall portion  613  and the first wall portion  611  is very large (see  FIG. 1 ), the residual gas made of the processing gas GI and the inert gas G 2  remaining after formation of the thin layer on the substrate S may not be discharged smoothly out of the second chamber  200  due to irregular fluid flow (vortex) formed inside the second chamber  200 . Due to this irregular fluid flow, the particles precipitated from the processing gas may excessively attach onto the discharge path, and the particles attached onto the discharge path are one cause of the warm-keeping effect. This will likely lead to the temperature of a reaction space  800  being higher than the preset temperature and will negatively influence the quality of the thin layer being formed. 
         [0034]      FIG. 2  is a cross-sectional view of a chemical vapor deposition apparatus with a guide unit  620  in place for purposes of eliminating substantially the irregular air flow inside the second chamber  200  according to an embodiment of the present invention. 
         [0035]    As shown in  FIG. 2 , the guide unit  620  is installed such that a second wall portion  623  is spaced apart by a distance d 2  (where d 1 &gt;d 2 ) from a first wall portion  621  and thus an irregular fluid flow is not generated inside a reaction space  800 . The first wall portion  621  may be disposed cylindrically so as to form a concentric circle with the susceptor  500 . 
         [0036]    Whether a vortex is formed inside the second chamber  200  can be confirmed by observing the areas of intense particle accumulation on specific portions of the chemical vapor deposition apparatus, or by performing a computer simulation based on the shape of the reaction space  800  inside the second chamber  200 , or by using a sensor detecting fluid flows inside the reaction space  800 . 
         [0037]    The guide unit  620  guides the main processing gas GI and the inert gas G 2  that are remaining after the thin layer is formed into a plurality of first wall portion holes  625 . The flowing gases GI and G 2  that have passed through the first wall portion holes  625  are then discharged out of the second chamber  200  through a plurality of chamber holes  201  via an extending portion  624 . 
         [0038]      FIG. 3  is a cross-sectional view of a chemical vapor deposition apparatus with a subsidiary plate  700  placed therein also for purposes of eliminating substantially the irregular air flow inside the second chamber  200  according to an embodiment of the present invention. 
         [0039]    By placing the subsidiary plate  700  inside the second chamber  200 , the width of the fluid discharge path (that is, the width between the second wall  613  and the subsidiary plate  700 ) is further narrowed to d 3  (where d 1 &gt;d 2 &gt;d 3 ). A subsidiary plate hole  703  is formed through a portion of a subsidiary plate main body  701 . The subsidiary plate hole  703  may be formed at a position facing the first wall portion hole  615 . A connecting portion  702  connecting the subsidiary plate hole  702  and the first wall portion hole  615  may be provided in the side surface of the subsidiary plate main body  701 . 
         [0040]      FIG. 4-5  are cross-sectional views of a chemical vapor deposition apparatus according to an embodiment of the present invention showing the first chamber  100  being separated from the second chamber for replacement of guide unit  610 . 
         [0041]    Now referring to  FIGS. 4-5 , when an irregular fluid flow is detected inside a reaction space  800 , the first chamber  100  may be opened to remove the guide unit  610  from the second chamber  200  manually or by a robot or by other ways of automated procedure for the purposes of replacing the guide unit  610  with other types of guide unit such as  620  shown in  FIG. 2  or for the purposes of inserting a subsidiary plate (such as  700  shown in  FIG. 3 ) in order to narrow the width of the discharge path of the residual processing gas being exhausted out of the second chamber. 
         [0042]      FIG. 6  is cross-sectional view of a chemical vapor deposition apparatus shows a guide unit  620  having a different size than the guide unit  610  shown in  FIGS. 4-5  installed in the second reaction chamber  200  manually or by a robot or by other ways of automated procedure. 
         [0043]    As shown in  FIG. 6 , the guide unit  620  having the first wall portion  621  and the second wall portion  623  spaced apart by d 2  may be installed in the second chamber  200  between the susceptor  500  and the sidewall of the second chamber  200 . The first chamber  100  which has been separated can then is reassembled back together with the second chamber  200 . 
         [0044]      FIG. 7  is a flowchart of a method for controlling the gas discharge path of a chemical vapor deposition apparatus according to an embodiment of the present invention. 
         [0045]    After operating the chemical vapor deposition apparatus, whether a vortex is formed in the second chamber  200  is checked at step S 10  by various methods as described above. For example, whether a vortex is formed inside the second chamber may be confirmed by separating the first and second chambers  100 ,  200  and observing areas of intense particle accumulation on one or more specific portions of the guide unit, or by performing a computer simulation based on a shape of the reaction space, or by using a sensor detecting fluid flow of the reaction space. 
         [0046]    When it is determined that a vortex was generated at step S 10 , the first chamber  100  is separated from the second chamber  200  at step S 11 . 
         [0047]    Next, the guide unit in the second chamber  200  is replaced with another guide unit of smaller size or narrowed width of the discharge path through which the residual processing gas flows to exit out of the second chamber  200  at step S 12 . Alternatively, a subsidiary plate may be inserted to realize a width of the discharge path narrower than that provided by the existing guide unit through which the residual processing gas flows to exit out of the second chamber  200  at step S 12 . The step S 12  is performed because it was determined that the width of the processing gas discharge path was large enough to generate a vortex. 
         [0048]    At step S 13 , the first and second chambers are reassembled. 
         [0049]    Next, at step S 14 , the operation of the chemical vapor deposition apparatus is resumed. 
         [0050]    Thereafter at step S 10 , the second chamber  200  is checked again to determine whether a vortex is generated inside the second chamber  200 . When a vortex is detected, the steps S 11 -S 14  are repeated. When a vortex is not detected, the pressure of the processing gas being discharged or the discharge rate of the processing gas is checked against a set value at step S 20  to determine whether the discharge pressure or the discharge rate is high. The discharge pressure or the discharge rate can be detected by using a pressure sensor or the like. 
         [0051]    When it is determined that the discharge pressure or the discharge rate is high compared to the preset value at step S 20 , the first chamber  100  is separated from the second chamber  200  at step S 21 . 
         [0052]    Next, the guide unit in the second chamber  200  is replaced with with another guide unit of a larger size or wider width of the discharge path through which the residual processing gas flows to exit out of the second chamber  200  at step S 22 . The step S 22  is performed because the high discharge pressure or the high discharge rate compared to the preset value is caused by the width of the discharge path being smaller than the optimal width. 
         [0053]    Next, at step S 23 , the first and second chambers are reassembled, and the operation of the chemical vapor deposition apparatus is resumed at step S 24 . Thereafter at step S 20 , the second chamber  200  is checked again to determine whether the discharge pressure or the discharge rate is higher than the set value. When it is determined that the discharge pressure or the discharge rate is high compared to the preset value at step S 20 , the steps S 21 - 24  are repeated. When it is determined that the discharge pressure or the discharge rate is not very high or sufficiently optimal in comparison to the present value at step S 20 , it can be determined that the discharge path is properly formed in the second chamber without causing a vortex of fluid flow therein during the operation. Hence, the operation of the chemical vapor deposition apparatus can continue. 
         [0054]    Of course, the steps S 20 -S 24  related to detecting whether or not the discharge pressure or the discharge rate is high in comparison to the preset value may be performed prior to the steps S 10 -S 14  of detecting whether or not a vortex is generated. 
         [0055]    According to an embodiment of the present invention, even if the discharge path of the residual gas to exit the second chamber  200  is not properly designed, the discharge path can be controlled properly by replacing only the guide unit or inserting an additional part (for example, the subsidiary plate  700  in  FIG. 3 ) for the guide unit without having to redesign and/or reequip the chemical vapor deposition apparatus. 
         [0056]    While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. Therefore, future modifications to the embodiments of the present invention cannot depart from the technical scope of the present invention.