Abstract:
A manufacturing apparatus for a semiconductor device includes: a chamber configured to load a wafer into the chamber; a gas supplying mechanism configured to supply processed gas into the chamber; a gas discharging mechanism configured to discharge the gas from the chamber; a wafer supporting member configured to mount the wafer; a heater including a heater element configured to heat the wafer up to a predetermined temperature and a heater electrode molded integrally with the heater element; an electrode part connected to the heater electrode and configured to applied a voltage to the heater element via the heater electrode; a base configured to fix the electrode part; and a rotational drive control mechanism configured to rotate the wafer; wherein at least a part of a connection portion of the heater electrode and the electrode part is positioned under the upper surface of the base.

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. 2009-187390 filed on Aug. 12, 2009, the entire contents of which are incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to a manufacturing apparatus and method for a semiconductor device, for example, used for forming a film by supplying a reaction gas to the surface of a semiconductor wafer while heating the rear surface of the semiconductor wafer. 
         [0003]    In recent years, as a semiconductor device is requested to realize lower price and higher performance, higher productivity in film forming process of a wafer and higher quality such as improvement in uniformity in film thickness is also required. 
         [0004]    To satisfy such requirements, a back heating method is employed, which uses a single-wafer-processing epitaxial growth apparatus, supplies process gas while rotating a wafer at high speed of 900 rpm or higher in a chamber, and heats the wafer from the rear surface by using a heater. 
         [0005]    Generally, a heater element constituting a heater is fixed and connected to an electrode part serving as a supporter within its plane by using a bolt or the like. However, heat induces deformation at a connection portion and an increase in resistance accordingly. In view of this, Japanese Patent Application Laid-open No. 2007-288163 (FIGS. 1 and 2 and the like) discloses a heater electrode integrated with a heater element is provided in such a manner as to be connected to an electrode part under the heater element. 
       SUMMARY 
       [0006]    A semiconductor manufacturing apparatus in one aspect of the present invention includes: a chamber configured to load a wafer into the chamber; a gas supplying mechanism configured to supply processed gas into the chamber; a gas discharging mechanism configured to discharge the gas from the chamber; a wafer supporting member configured to mount the wafer; a heater including a heater element configured to heat the wafer up to a predetermined temperature and a heater electrode molded integrally with the heater element; an electrode part connected to the heater electrode and configured to applied a voltage to the heater element via the heater electrode; a base configured to fix the electrode part; and a rotational drive control mechanism configured to rotate the wafer; wherein at least a part of a connection portion of the heater electrode and the electrode part is positioned under the upper surface of the base. 
         [0007]    A semiconductor manufacturing method in one aspect of the present invention includes: loading a wafer in a chamber; applying a voltage, via a electrode part connected to a heater electrode at a connection portion under the upper end of the electrode part, to the heater element molded integrally with the heater electrode to generate heat to heat the wafer at a predetermined temperature; and rotating the wafer and supplying processed gas onto the wafer, to form a film on the wafer. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a cross-sectional view showing a manufacturing apparatus for a semiconductor device in one aspect of the present invention; 
           [0009]      FIG. 2  is a diagram illustrating a heater pattern in one aspect of the present invention; 
           [0010]      FIG. 3  is a cross-sectional view showing a manufacturing apparatus for a semiconductor device in another aspect of the present invention; and 
           [0011]      FIG. 4  is a cross-sectional view showing a manufacturing apparatus for a semiconductor device in a further aspect of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    Reference will now be made in detail to the present embodiment of the invention, an example of which is illustrated in the accompanying drawings. 
         [0013]    As described above, in a manufacturing apparatus for a semiconductor device, a heater electrode integrated with a heater element is provided in such a manner as to be connected to an electrode part under the heater element. At this time, the heater electrode is made of SiC doped with impurities whereas the electrode part is made of carbon containing impurities. Both of the heater electrode and the electrode part are subjected to SiC coating in order to prevent diffusion of the impurities. The heater electrode and the electrode part are connected near the middle between a base and a susceptor for fixing electronic parts or the like for the purpose of connection stability and fixing facility. 
         [0014]    However, these connection portions (i.e., joint ends) are not subjected to coating in order to secure conductivity. Moreover, in order to keep the treatment temperature of a wafer at about 1100° C., the temperature at the connection portion need be kept within a range of 700° C. to 900° C. Therefore, the impurities are diffused at the connection portion, thereby contaminating the wafer. Preferred embodiments below have been accomplished to solve such a problem. 
       First Embodiment 
       [0015]      FIG. 1  is a cross-sectional view showing an epitaxial growth apparatus as a semiconductor manufacturing apparatus in the present embodiment. As shown in  FIG. 1 , in a chamber  11  in which a wafer w having a diameter of, for example, 200 mm is subjected for film forming process, gas supply ports  12  connected to a gas supply mechanism (not shown) for supplying process gas containing a source gas such as trichlorosilane or dichlorosilane onto the wafer w at a predetermined flow rate from above the chamber  11  are provided. In a lower part of the chamber  11 , gas discharge ports  13  connected to a gas discharge mechanism (not shown) for discharging gas to control the pressure in the chamber  11  to predetermined pressure (ordinary pressure) are provided in two places. 
         [0016]    Rectifying plates  14  for supplying the processed gas supplied through the gas supply ports  12  onto the wafer w in a rectified state are provided in the upper portion of the chamber  11 . Under the rectifying plates  14 , a susceptor  15  functioning as a holding member for holding the wafer w on a ring  16  serving as a rotating member is disposed. The ring  16  is connected to a rotational drive control mechanism  17  constituted of a rotary shaft (not shown) for rotating the wafer w at a predetermined rotational speed, a motor (not shown) and the like. 
         [0017]    Inside of the ring  16  are housed an in-heater  18  and an out-heater  19  for heating the wafer w made of, for example, SiC. Under these heaters is disposed a disk-like reflector  20  for efficiently heating the wafer w. Additionally, a pushing-up shaft  21  is provided for vertically moving the wafer w in such a manner as to pierce the in-heater  18  and the reflector  20 . 
         [0018]    The in-heater  18  includes a heater element  18   a  having a predetermined pattern illustrated in  FIG. 2  and a heater electrode  18   b  molded integrally with the heater element  18   a . In contrast, the out-heater  19  includes an annular heater element  19   a  and a heater electrode  19   b  molded integrally with the heater element  19   a . The basic material of each of the heater electrodes  18   b  and  19   b  is conductive SiC which is doped with impurities such as N 2 . Furthermore, each of the heater electrodes  18   b  and  19   b  is coated with a high-purity SiC film. 
         [0019]    At the lower portion inside of the ring  16 , booth bars  22  serving as an electrode part to be connected to the heater electrodes  18   b  and  19   b  by using bolts or the like are disposed. The connection portion between electrode part and the heater electrode disposed under the upper end of the electrode part. The basic material of the booth bars  22  are carbon having conductivity, and further, the booth bar  22  is coated with a high-purity SiC film. Connection portion between the heater electrodes  18   b  and  19   b  and the booth bar  22  are not coated with the SiC film. The booth bar  22  is connected to an exterior power source (not shown) and further, by using bolts or the like to an electrode  24  to be fixed to a heater shaft  23 . 
         [0020]    Under the booth bar  22 , for example, a quartz base  25  is disposed. To the base  25  are fixed the supporter of the reflector  20  and the booth bar  22 . Cutouts are formed at the base  25  such that at least a part of the connection portion between each of the heater electrodes  18   b  and  19   b  and the booth bar  22  is lower than the upper surface of the base  25 . 
         [0021]    The position of the connection portion between each of the heater electrodes  18   b  and  19   b  and the booth bar  22  is preferably located such that the distance between the upper end and a wafer supporting surface of the susceptor  15  should be ranged 0.5 to 1.5 times of the diameter of the wafer w. If the distance is less than 0.5 time, the temperature at the connection portion becomes too high. In contrast, if the distance is more than 1.5 times, the volume of the apparatus is increased, and degrading the holding stability by the heater. 
         [0022]    With the above-described semiconductor manufacturing apparatus, an Si epitaxial film is formed on the Si wafer w of, for example, φ200 mm. 
         [0023]    First, the wafer w is loaded into the chamber  11 . The susceptor  15  having the wafer w mounted thereon is placed on the ring  16  by descending the pushing-up shaft  21 . And then, the electrode  23  connected to the exterior power source (not shown) applies a voltage to each of the heater electrodes  18   b  and  19   b  connected to the booth bars  22  at the cutouts at the base  25 , so as to control the in-heater  18  and the out-heater  19  in such a manner as to make the in-planar temperature of the wafer w uniform at, for example, 1100° C. 
         [0024]    Thereafter, the wafer w is rotated by the rotational drive control mechanism  17  at, for example, 900 rpm, and further, the processed gas is supplied onto the wafer w through the gas supply ports  12  in the rectified state via the rectifying plates  14 . The processed gas is prepared such that the concentration of trichlorosilane is adjusted to, for example, 2.5%, and for example, is supplied at 50 SLM. 
         [0025]    In the meantime, gases such as excessive gas of the processed gas containing trichlorosilane and dilute gas, and HCl as a reaction by-product are discharged downward from periphery of the susceptor  15 . In addition, the gases are discharged through the gas discharge ports  13  via the gas discharging mechanism (not shown) so that the pressure inside of the chamber  11  is controlled to be constant (for example, at an ordinary pressure). In this manner, the Si epitaxial film is grown on the wafer w. 
         [0026]    The heater electrode and the booth bar have been conventionally connected to each other in the middle of the susceptor because of the connection stability and the fixing facility. However, since the treatment temperature of the wafer is kept in a range from 900° C. to 1200° C. from the surface of the susceptor on which the wafer is placed to the position of less than 0.5 times (in the present preferred embodiment, 10 cm) of the diameter of the wafer, the temperature of the connection portion need be substantially kept within a range from 700° C. to 900° C. The connection portion is descended near the position of the base where the temperature need not be kept, so that the temperature of the connection portion can be reduced to 500-700° C. Consequently, it is possible to suppress the diffusion of the impurities from the connection portion, so as to restrain the contamination of the wafer. As a result, a switching speed can be increased or a leakage current can be reduced in a semiconductor device which is formed by using the above-described wafer. 
       Second Preferred Embodiment 
       [0027]    The configuration of a semiconductor manufacturing apparatus in the present preferred embodiment is identical to that in the first preferred embodiment except that a separation plate is disposed on a connection portion between a heater electrode and a booth bar. 
         [0028]    Specifically, as shown in  FIG. 3 , a separation plate  31  is disposed in such a manner as to partition each connection portion between heater electrodes  18   b  and  19   b  and booth bars  22  from heater elements  18   a  and  19   a . The separation plate  31  has a center portion and openings through which the heater electrodes  18   b  and  19   b , a supporter for a reflector, and the like penetrate. 
         [0029]    Even if impurities are diffused from the connection portions, the impurities never reach the heater electrodes  18   b  and  19   b  by providing such a separation plate, and therefore, contamination of a wafer can be more suppressed than in the first preferred embodiment. Consequently, like in the first preferred embodiment, a switching speed can be more increased or a leakage current can be more reduced in a semiconductor device which is formed by using the above-described wafer. 
         [0030]    Furthermore, it is preferable that a region under the separation plate  31  should be purged with H 2  or inert gas such as Ar. Specifically, as shown in  FIG. 4 , a purge gas inlet  41  and a purge gas outlet  42  are disposed in the region under the separation plate  31 . The purge gas such as H 2  contained in dilute gas such as processed gas is introduced through the purge gas inlet  41 , and then, is discharged outside of a heater unit (i.e., the ring  16 ) through the purge gas outlet  42  in such a manner as to prevent any circulation of the purge gas toward heater elements. The discharged purge gas is discharged outside of a chamber  11  through gas discharge ports  13 . In this manner, it is possible to more suppress contamination of a wafer. 
         [0031]    According to the present embodiment, a film such as an epitaxial film can be formed on a semiconductor wafer with high productivity. In addition, the yields of wafers and semiconductor devices manufactured through an element formation process and an element separation process can be improved and stable element characteristics of the semiconductor devices can be obtained. In particular, by applying to an epitaxial formation process of power semiconductor devices such as power MOSFET and IGBT, which require growth of a thick film having a thickness of 100 μm or more in an N-type base region, P-type base region or an insulation isolation region, satisfactory element characteristics can be obtained. 
         [0032]    While the epitaxial film is formed on an Si substrate in this embodiment, it can be applied to forming of a polysilicon layer and it can be applied also to other compound semiconductors, for example, a GaAs layer, a GaAlAs layer, and an InGaAs layer. It can also be applied to forming of an Sio 2  film and an Si 3 N 4  film, and in the case of SiO 2  film, monosilane (SiH 4 ) and gases of N 2 , O 2 , and Ar are fed, and in the case of Si 3 N 4  film, monosilane (SiH 4 ) and gases of NH 3 , N 2 , O 2 , and Ar are fed. 
         [0033]    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.