Abstract:
Provided is a semiconductor manufacturing apparatus including: a reaction chamber including a gas supply inlet and a gas exhaust outlet, and into which a wafer is to be introduced; a process gas supply mechanism that supplies process gas into the reaction chamber from the gas supply inlet of the reaction chamber; a wafer retaining member that is arranged in the reaction chamber and that retains the wafer; a heater that heats the wafer retained by the wafer retaining member to a predetermined temperature; a rotation drive control mechanism that rotates the wafer retaining member together with the wafer; a gas exhaustion mechanism that exhausts gas in the reaction chamber from the gas exhaust outlet of the reaction chamber; and a drain that is disposed at a bottom portion near a wall surface in the reaction chamber and that collects and discharges oily silane that drips from the wall surface.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2011-007736 filed on Jan. 18, 2011, the entire contents of which are incorporated herein by reference. 
       BACKGROUND 
       [0002]    The present invention relates to a semiconductor manufacturing apparatus and a semiconductor manufacturing method used for performing deposition on a semiconductor wafer by using Si source gas, for example. 
         [0003]    In an epitaxial growth apparatus for Si, for example, H 2  gas as carrier gas and SiH 2 Cl 2  gas or SiHCl 3  gas as source gas are used, and gas in which the aforementioned are mixed is supplied as process gas to a reaction chamber. Then, a wafer temperature is made to be about 1100° C., and Si is grown epitaxially on a wafer by a hydrogen reduction reaction. 
         [0004]    At this occasion, reaction by-products such as polysilicon deposited on members such as a susceptor inside the reaction chamber are removed. Due to this, a cleaning (etching process) using Chlorine gas such as HCl gas is performed periodically. At this time, a Si—H—Cl polymer is generated as the by-product in the reaction chamber, is cooled near a ventilation outlet, and is deposited as oily silane (reactive polysiloxane). 
         [0005]    The oily silane deposited as aforementioned is usually removed upon a periodically performed maintenance of the reaction chamber so as to prevent a ventilation system from being clogged. However, upon an air ventilation, there is a problem that H 2  gas and HCl gas are generated by a surface reacting with water in the air. 
         [0006]    Further, when the reaction chamber undergoes the air ventilation, although the oily silane has the surface reacting with the water in the air to generate H 2  gas and HCl gas, the surface solidifies by turning into SiO 2 , and thereby further reaction can be suppressed. On a vertical surface, there is no problem because most of the deposited oily silane is solidified by turning into SiO 2 . 
         [0007]    However, when a certain amount of the oily silane is collected on a horizontal surface, unreacted oily silane in a lower layer of a solidified portion reacts vigorously upon exfoliating the oily silane. Due to this, there is a risk of ignition and explosion of the H 2  gas. This especially becomes a problem in a single wafer processing epitaxial growth apparatus, which frequency of the air ventilation is low and the oily silane is more likely to be collected. 
         [0008]    Thus, considerations are given to removing the oily silane without performing the air ventilation either in a wet process or a dry process. However, since the reaction of the lower layer is suppressed in the oily silane when the surface thereof is oxidized, there is a need to repeatedly perform oxidation and surface removal, which is a problem which effects a throughput. 
       SUMMARY 
       [0009]    According to an aspect of the present invention, there is provided a semiconductor manufacturing apparatus including: a reaction chamber including a gas supply inlet and a gas exhaust outlet, and into which a wafer is to be introduced; a process gas supply mechanism that supplies process gas into the reaction chamber from the gas supply inlet of the reaction chamber; a wafer retaining member that is arranged in the reaction chamber and that retains the wafer; a heater that is arranged in the reaction chamber and that heats the wafer retained by the wafer retaining member to a predetermined temperature; a rotation drive control mechanism that rotates the wafer retaining member together with the wafer; a gas exhaustion mechanism that exhausts gas in the reaction chamber from the gas exhaust outlet of the reaction chamber; and a drain that is disposed at a bottom portion near a wall surface in the reaction chamber and that collects and discharges oily silane that drips from the wall surface. 
         [0010]    Further, according to an aspect of the present invention, there is provided a semiconductor manufacturing method including: introducing a wafer into a reaction chamber; heating the wafer to a predetermined temperature; depositing on the wafer by rotating the wafer and supplying process gas including Si source gas on the wafer; and exhausting excessive process gas and discharging oily silane that is generated during the depositing and dripped from a wall surface of the reaction chamber from a drain arranged on a bottom surface of the reaction chamber to outside. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a cross sectional view showing a structure of an epitaxial deposition apparatus of a first embodiment; 
           [0012]      FIG. 2A  is a top view showing an oily silane receiving section of the first embodiment; 
           [0013]      FIG. 2B  is a perspective view showing the oily silane receiving section of the first embodiment; 
           [0014]      FIG. 3  is a cross sectional view showing a structure of an epitaxial deposition apparatus of a second embodiment; and 
           [0015]      FIG. 4  is a top view showing an oily silane receiving section of the second embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    Reference will now be made in detail to the present embodiment of the invention, an example of which is illustrated in the accompanying drawings. 
       First Embodiment 
       [0017]      FIG. 1  shows a cross sectional view of an epitaxial deposition apparatus as a semiconductor manufacturing apparatus in the present embodiment. As shown in the drawings, gas supply inlets  12   a  connected to a gas supply mechanism  12  configured to supply process gas containing source gas such as trichlorosilane, dichlorosilane and the like onto a wafer w at a predetermined flow rate from an upper portion of a reaction chamber  11  are arranged in the reaction chamber  11  in which the wafer w of, for example, φ200 mm undergoes a deposition step. On an inner wall of the reaction chamber  11 , a liner  11   a  that is formed, for example, of quartz and that can be detached upon cleaning the reaction chamber  11  is provided. At, for example, two positions in a lower portion of the reaction chamber  11 , there are provided gas exhaust outlets  13   a  connected to a gas exhaustion mechanism  13  configured to exhaust gas so as to control a pressure inside the reaction chamber  11  at a constant value (a normal pressure). At a bottom portion of the reaction chamber  11 , an oily silane receiving section  14   a  is arranged as an oily silane guiding groove that receives and guides the oily silane dripped from the wall surface of the reaction chamber  11 . Further, at a bottom surface of the oily silane receiving section  14   a , an oily silane discharge outlet  14   b  configured to discharge the oily silane is formed. A drain  14   c  configured to discharge the oily silane to outside of the reaction chamber  11  is connected to the oily silane discharge outlet  14   b . Further, under the drain  14   c , a tank  14   e  configured to collect the oily silane is connected via valves  14   d.    
         [0018]      FIG. 2A  shows a top view of the oily silane receiving section  14   a , and  FIG. 2B  shows a perspective view of the oily silane receiving section  14   a , respectively. As shown in  FIG. 2A , the oily silane receiving section  14   a , which is a leading section configured to lead the oily silane to the outside of the reaction chamber  11  from an outer periphery portion of the gas exhaust outlets  13   a , is formed around a rotation shaft  18   a . This oily silane receiving section  14   a  is formed of a SUS (Steel Use Stainless) to which a mirror processing is performed, for example. Further, when seen from a top side, the gas exhaust outlets  13   a  and the oily silane discharge outlets  14   b  are arranged alternately at identical intervals on a same circumference on the oily silane receiving section  14   a.    
         [0019]    Further, as shown in  FIG. 2B , the oily silane receiving section  14   a  has a taper angled from an apex portion toward a bottom portion so that the oily silane will not be collected in the oily silane receiving section  14   a  itself. Moreover, the gas exhaust outlets  13   a  are provided at a pair of apexes, and the oily silane discharge outlets  14   b  are provided at a pair of apexes on the oily silane receiving section  14   a . Due to this, it has a mechanism in which the oily silane that has dripped from the wall surface to the oily silane receiving section  14   a  is led to a direction toward the bottom portion, and is discharged from the oily silane discharge outlets  14   b  provided at the lowest position (bottom portion). Note that, the oily silane discharge outlets  14   b  are provided on every bottom portion of the oily silane receiving section  14   a . The number of the bottom portions can be changed voluntarily, for example, within one to four; and it is preferable to provide the number of the bottom portions to be two in the case where the number of the gas exhaust outlets  13   a  is two as shown in  FIG. 2B . 
         [0020]    Further, as shown in  FIG. 2B , since opening portions of the two gas exhaust outlets  13   a  are positioned higher than the apex portion of the oily silane receiving section  14   a , the oily silane that had dripped from the inner wall of the reaction chamber  11  onto the oily silane receiving section  14   a  does not intrude into the gas exhaust outlets  13   a . Further, pipes connecting the gas exhaust outlets  13   a  and the gas exhaustion mechanism  13  extend below the outer periphery portion of the oily silane receiving section  14   a.    
         [0021]    Further, a detect ion mechanism (not shown) configured to detect an amount of the oily silane, a gas exhausting pump (not shown) and the like are arranged inside the tank  14   e  as needed. 
         [0022]    At the upper portion of the reaction chamber  11 , a rectifying plate  15  configured to supply the process gas provided from the gas supply inlets  12   a  onto the wafer w in a rectified state is arranged. Further, underneath thereof, a susceptor  16  as a retaining member configured to retain the wafer w is arranged on a ring  17  as a rotating member. Note that, the retaining member may be an annular holder. The ring  17  is connected to a rotation drive control mechanism  18  configured of the rotation shaft  18   a  that rotates the wafer w at a predetermined rotational speed, a motor (not shown) and the like. 
         [0023]    A disc-shaped heater  19  configured, for example, of SiC so as to heat the wafer w is arranged inside the ring  17 . Note that, a pattern may be formed on the heater  19  so that a uniform heating may be realized. As the heater  19 , an annular heater for heating a peripheral portion of the wafer w may be used, and a reflector for heating effectively may be provided. 
         [0024]    By using the epitaxial deposition apparatus configured as above, for example, an Si epitaxial film is formed on the wafer w of φ200 mm. 
         [0025]    Firstly, the wafer w is conveyed into the reaction chamber  11 , and the susceptor  16  onto which the wafer w is mounted is mounted on the ring  17 . Then, a temperature of the heater  19  is controlled, for example, to be at 1500 to 1600° C. so that an in-plane temperature of the wafer w is uniformly retained at 1100° C. 
         [0026]    Then, the wafer w is rotated, for example, at 900 rpm by the rotation drive control mechanism  18 , and the process gas is supplied onto the wafer w from the gas supply mechanism  12  via the gas supply inlets  12   a  in the rectified state via the rectifying plate  15 . The process gas is diluted with diluent gas such as H 2  so that a concentration of dichlorosilane is adjusted, for example, to 2.5%, and is supplied, for example, at 50 SLM. 
         [0027]    Gases such as excessive dichlorosilane, process gas containing diluent gas, and HCl that is a by-product are exhausted downward from an outer periphery of the susceptor  16 . Further, these gases are exhausted from the gas exhaustion mechanism  13  via the gas exhaust outlets  13   a , and the pressure inside of the reaction chamber  11  is controlled at a constant value (for example, the normal pressure). In this manner, the Si epitaxial film is grown on the wafer w. 
         [0028]    At this time, though oily silane generated from gases such as the excessive process gas is deposited in a gap between the quartz liner  11   a  near the gas exhaust outlet  13   a  and the inner wall of the quartz liner  11   a  as well as the inner wall of the quartz liner  11   a , it is dripped to the oily silane receiving section  14   a  arranged at the outer periphery portion of the gas exhaust outlet  13   a , and is collected in the tank  14   e  through the oily silane discharge outlet  14   b , the drain  14   c , and the valve  14   d.    
         [0029]    Then, when the detection mechanism (not shown) detects that a predetermined amount of the oily silane is collected in the tank  14   e , the valve  14   d  is closed and the tank  14   e  is detached from a coupling joint. Then, the oily silane is processed in a safe environment such as inside a draft. At this time, it is possible to recycle by collecting generated gases such as H 2  and HCl. 
         [0030]    Note that, upon an maintenance of the reaction chamber  11 , the oily silane deposited on the wall surface and the like of the reaction chamber  11  mostly solidifies by turning into SiO 2  upon the air ventilation, but in order to further improve safety, it is preferable to supply O 2  gas in advance, thereby forming SiO 2  and then ventilate air. Solidified SiO 2  is removed together with other deposits (by-product). 
         [0031]    According to the present embodiment, by providing the drain  14   c  discharging the oily silane and the tank  14   e  storing the discharged oily silane at outside the reaction chamber  11  and processing by detaching the tank  14   e  from the reaction chamber  11 , a safe removal of the oily silane is enabled without decreasing a throughput. 
       Second Embodiment 
       [0032]    In the present embodiment, the configuration of the epitaxial deposition apparatus is similar to the first embodiment; however, it differs from the first embodiment in that a plurality of oily silane receiving sections is provided around the rotation shaft  18   a  by configuring a gas exhaustion in a lateral direction. 
         [0033]      FIG. 3  shows a cross sectional view of the epitaxial deposition apparatus as the semiconductor manufacturing apparatus in the present embodiment. The configuration is similar to the first embodiment, however, a gas exhaust outlet  23   a  connected via a pipe with a gas exhaustion mechanism  23  is arranged on a lower wall surface of a reaction chamber  21 , and at a bottom surface of the reaction chamber  21 , oily silane receiving sections  24   a  are provided. Further, at lower ends of the oily silane receiving sections  24   a , oily silane discharge outlets  24   b  configured to discharge the oily silane are formed. Drains  24   c  configured to discharge the oily silane to outside of the reaction chamber  21  are connected to the oily silane discharge outlets  24   b . Further, under the drains  24   c , tanks  24   e  configured to collect the oily silane are connected via valves  24   d.    
         [0034]    Note that, the oily silane receiving sections  24   a  preferably have a taper shape in which a diameter of the oily silane discharge outlets  24   b  is smaller than a diameter of opened portions on the bottom surface side of the reaction chamber  21  so that the oily silane will not be collected therein. 
         [0035]    By using the epitaxial deposition apparatus configured as above, similar to the first embodiment, for example, an Si epitaxial film is formed on the wafer w of φ200 mm. Then, similar to the first embodiment, the oily silane generated upon the deposition and deposited is collected in the tanks  24   e  via the oily silane receiving sections  24   a , the oily silane discharge outlets  24   b , the drains  24   c , and the valves  24   d , thereafter is processed similar to the first embodiment, and a similar maintenance is performed. 
         [0036]    According to the present embodiment, similar to the first embodiment, by providing the drains  24   c  discharging the oily silane and the tanks  24   e  storing the discharged oily silane at outside the reaction chamber  21  and processing by detaching the tanks  24   e  from the reaction chamber  21 , a safe removal of the oily silane is enabled without decreasing a throughput. 
         [0037]    According to the present embodiment, it becomes possible to perform maintenance safely on the semiconductor manufacturing apparatus that forms high quality films such as an epitaxial film on a semiconductor wafer. Further, even with improved safety, throughput is not decreased. Due to this, in a semiconductor device that is formed by going through an element forming step and a partition step, high productivity can be obtained. 
         [0038]    Especially, it can be used ideally as an epitaxial deposition apparatus configured to form a power semiconductor device such as a power MOSFET, IGBT and the like, which requires growing a thick film of 40 μm or more in an N-type base region, a P-type base region, an isolating region and the like. 
         [0039]    Further, in these embodiments, the case of forming an Si monocrystal layer (epitaxial film) has been explained, however, the present embodiments can be adapted to forming a poly-Si layer. Further, it can also be adapted to deposition, for example, an SiO 2  film, an Si 3 N 4  film and the like other than the Si film, and also to a GaAs layer and a compound semiconductor, for example, a GaAlAs, an InGaAs and the like. 
         [0040]    Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.