Patent Document

CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a divisional application of application Ser. No. 08/871,452, filed Jun. 9, 1997 now U.S. Pat. No. 6,039,811. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an apparatus and method for fabricating a polysilicon film for a semiconductor device. 
     2. Description of the Related Art 
     To manufacture a reliable semiconductor device:, one must keep the temperature of the apparatus uniform and minimize any contaminating particles. 
     Specifically, consider the case of forming a lower electrode with a hemispherical silicon grain (referred to as HSG-Si), in order to enlarge the electrostatic capacitance of a capacitor by increasing the area of the lower electrode. In this situation, it is critical to keep the temperature of the reaction chamber uniform and to keep the inside of the reaction chamber clean and free of contaminants. 
     Typically, to form the lower electrode with HSG-Si, a crystal growing step for forming crystal grains by migrating the amorphous silicon to the nucleus of crystalline silicon needs to be stable. Also, the speed of silicon surface migration for the growth of the crystal grain needs to be faster than the speed of the amorphous silicon crystallization in the lower amorphous silicon. 
     For the amorphous silicon to move toward the nucleus of the crystalline silicon, the amorphous silicon should have a free surface where the silicon atoms of the surface are not combined to any other atoms. When the surface is contaminated with other materials, the surface movement of the amorphous silicon atoms is impeded since the amorphous silicon atoms combine to the atoms of the other materials, thus making any further generation and growth of the nucleus impossible. Therefore, removing the surface contaminants on the wafer that is transferred to the reaction chamber, and keeping the inside of the chamber clean are important factors in semiconductor processing. 
     A general apparatus for fabricating the semiconductor device includes a cassette chamber in which a carrier having a wafer is loaded. The apparatus also contains a reaction chamber for performing a process, and a wafer cooling chamber after completing the process. A polyhedral transfer chamber having a robot arm is connected to the reaction chamber and cooling chambers for transferring the wafer to the respective chambers. 
     The structure of the reaction chamber is described as follows with reference to FIG. 1. A gate valve  31  that separates a wafer transfer chamber  10  and a reaction chamber  20  is disposed between the first side wall  30  of the reaction chamber and the wafer transfer chamber  10 . A gas vent opening  33  is formed on a second side wall  32  opposite to the first side wall  30 . A gas injection opening  35  is formed to pass through an upper wall  34  of the reaction chamber. Cooling jackets  40  and  42  are installed on the upper  34  and bottom  36  walls of the reaction chamber. A heating block  24 , having a heater  22  and a susceptor  26  for sustaining a wafer  28  on the heating block  24 , are installed inside the reaction chamber  20 . Also, a turbo pump  38  is connected to the second side wall  32 . 
     The operation of the apparatus of FIG. 1 will now be described. First, the wafer is transferred to the reaction chamber  20  after being transferred from the cassette chamber (not shown) and the wafer transfer chamber  10  by the robot arm. The pressure of the cassette chamber at the beginning of the transfer is about 1 mtorr. 
     However, air at a pressure of about 1 mtoor, which contains polluting particles, is also transferred from the cassette chamber to the wafer transfer chamber when the wafer is transferred. Therefore, the wafer transfer chamber is contaminated with the polluting particles. As a result, the reaction chamber  20  connected to the wafer transfer chamber  10  is also contaminated with the polluting particles. The surface of the wafer is thus contaminated by these polluting particles, such as moisture and carbon compounds, during the process of raising the temperature of the wafer  28  in the reaction chamber  20 , thus reducing the reliability of the processing. Especially, in the case of forming the lower electrode with the HSG-Si, it is impossible to increase the surface area since the speed of the surface migration of the amorphous silicon is reduced by adsorption of contaminants to the amorphous silicon. 
     In the next steps, the surface of the wafer  28  is cleaned to remove an organic material or a native oxide film existing on the surface of the wafer prior to the processing in the reaction chamber  20 . Therefore, a certain amount of moisture exists on the surface of the wafer  28  which is loaded in the cassette chamber (not shown) and the moisture is not completely evaporated and removed in the cassette chamber under the pressure of lmtorr. Therefore, vapor is continuously generated when the wafer  28  is transferred from the wafer transfer chamber  10  to the reaction chamber  20 . Especially in a process for forming the HSG-Si, the speed of the surface migration of the amorphous silicon is reduced by the vapor which is continuously generated. 
     Typically, a cooling gas, such as argon or helium is injected into a cooling chamber (not shown) at a pressure of 1 to 100 torr. The cooling gas flows into the wafer transfer chamber  10  connected to the cooling chamber, and then flows into the reaction chamber  20 , thus acting as a contaminant. As before, the speed of the surface migration of the amorphous silicon is reduced since the surface of the wafer  28  is contaminated by the cooling gas. 
     As shown in FIG. 1, the reaction chamber includes the cooling jackets  40  and  42  for keeping the temperature uniform on the upper and bottom walls  34  and  36  thereof. However, the temperature of the gate valve  31  separating the transfer chamber  10  and the reaction chamber  20 , the first side wall  30  adjacent to the gate valve  31  and the second side wall  32  opposite to the first side wall  30 , are all approximately 50° C. or higher than the upper  34  and bottom  36  walls, since the above three portions have no cooling jackets. Thus, the surface contaminants existing on the chamber walls and the wafer may exude in a gas form from the gate valve  31 , the first side wall  30 , and the second side wall  32 . Especially in the case of the process for forming the HSG-Si, it is impossible to achieve the desired surface increase effect since the exuded gas is adsorbed to the surface of the silicon. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an apparatus for fabricating a semiconductor device and associated methods using such an apparatus, which substantially overcomes the limitations and disadvantages of the conventional art. 
     To achieve such advantages, the apparatus for fabricating the semiconductor device according to the present invention comprises a cassette chamber, a wafer transfer chamber, a reaction chamber and a wafer cooling chamber. First, second, third and fourth cooling jackets are installed on a first side wall adjacent to the wafer transfer chamber, a second side wall opposite to the first side Mall, an upper wall, and a bottom wall, respectively. A gate valve is disposed between the reaction chamber and the wafer transfer chamber to separate the reaction chamber from the wafer transfer chamber. The gate valve has a fifth cooling jacket thereon. A wafer cooling chamber is connected to a side portion of the wafer transfer chamber. 
     A polysilicon film is fabricated with the above apparatus by adjusting the pressure of the cassette chamber to be less than 0.05 mtorr. Alternatively, the pressures of the cooling chamber and the wafer transfer chamber may be controlled to be less than 1.0 μtorr. A refrigerant, selected from the group consisting of cooling water, and mixture of the cooling water and ethylene glycol, is provided to the first through fifth cooling jackets of the above apparatus. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above objects and advantages of the present invention will become more apparent by describing in detail a preferred embodiment thereof with reference to the attached drawings in which: 
     FIG. 1 is a sectional view of a reaction chamber of a conventional semiconductor device fabricating apparatus; 
     FIG. 2 is a plan view of a semiconductor device fabricating apparatus according to an embodiment of the present invention; 
     FIG. 3 is a sectional view of the reaction chamber taken along the line III-Ill′ of FIG. 2; 
     FIG. 4 is a graph showing the relation between pumping down time and cassette chamber pressure; 
     FIGS. 5A to  5 E are scanning electron microscope photographs of the surface of a capacitor lower electrode formed by a method for fabricating a polysilicon film according to a first embodiment of the present invention and formed in the positions of the wafer shown in FIG. 5F; 
     FIGS. 6A and 6B are scanning electron microscope photographs of the surface of the capacitor lower electrode formed by a conventional semiconductor device fabricating apparatus, as a contrast group to the first embodiment; 
     FIG. 7A is a scanning electron microscope photograph of the surface of the capacitor lower electrode formed by a method for fabricating a polysilicon film according to a second embodiment of the present invention; 
     FIG. 7B is a scanning electron microscope photograph of the surface of the capacitor lower electrode formed by a conventional silicon film fabricating method, as a contrast group to the second embodiment; 
     FIG. 8 is a bar graph showing the value of the maximum capacitance of the capacitor shown in FIGS. 7A and 7B; 
     FIG. 9A is a scanning electron microscope photograph of the surface of the capacitor lower electrode formed by a polysilicon film fabricating method according to a third embodiment of the present invention; 
     FIG. 9B is a scanning electron microscope photograph of the surface of the capacitor lower electrode formed by a conventional polysilicon film fabricating method, as a contrast group to the third embodiment; 
     FIG. 10A shows the capacitances of the respective portions of the wafer after forming the capacitor lower electrode by a polysilicon film fabricating method according to a fourth embodiment of the present invention; 
     FIG. 10B shows the capacitance of the capacitor-lower electrode formed by the conventional polysilicon film fabricating method, as a contrast group to the fourth embodiment; and 
     FIG. 11 is a graph showing the reproducability of the process in the case of forming the capacitor by the polysilicon film fabricating method according to the fourth embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The semiconductor device fabricating apparatus of the present invention will first be described, followed by various methods for fabricating a polysilicon film using the disclosed apparatus. 
     Semiconductor Device Fabricating Apparatus 
     FIG. 2 is a plan view of a semiconductor device fabricating apparatus according to a preferred embodiment of the present invention. 
     Referring to FIG. 2, the semiconductor device fabricating apparatus includes a cassette chamber  200 , with a carrier  202  having a wafer  204  loaded therein, with the cassette chamber  200  separating the carrier  202  from atmosphere. A wafer transfer chamber  210 , having a robot arm  212 , transfers the wafer  204  to a reaction chamber  220 , where a process for fabricating a semiconductor device proceeds. A wafer cooling chamber  230  cools the wafer after the fabricating process is complete. 
     Five cooling jackets are installed on the reaction chamber  220  according to the embodiment of the present invention. They are described in detail with reference to FIG. 3 showing an exaggerated sectional view of the reaction chamber  220  taken along the line III-III′ of FIG.  2 . 
     Referring to FIG. 3, a gate valve  118  formed on a first side wall  300  separates the wafer transfer chamber  210  from the reaction chamber  220 . A first cooling jacket  400  and a second cooling jacket  410  are respectively formed on a first side wall  300  and a second side wall  320 . A gas injection opening  350  is formed to pass through an upper wall of the reaction chamber  340 . A third cooling jacket  420  is formed on the upper wall of the reaction chamber  340 . A fourth cooling jacket  430  is also formed outside of a bottom wall  360  of the reaction chamber  220 . A heating block  392  inside the reaction chamber  220  contains a heater  390  and a susceptor  394  for sustaining the wafer  204  on the heating block  392 . A turbo pump  380  is connected to the second side wall  320 . A fifth cooling jacket  440  is formed on the surface of the gate valve  118 . 
     A refrigerant, selected from the group consisting of cooling water and a mixture of the cooling water and ethylene glycol, is preferably used in the first to the fifth cooling jackets  400 ,  410 ,  420 ,  430 , and  440 . Also, it is preferable that the refrigerant have a temperature substantially less than 9° C., thus making the temperature in the reaction chamber  220  substantially less than 10° C. 
     In the semiconductor device fabricating apparatus according to the embodiment of the present invention, since the cooling jackets are installed on all the walls, including the upper and bottom walls of the reaction chamber, it is possible to prevent gas from being exuded from the chamber walls by supplying the refrigerant to the respective cooling jackets during the processing in the reaction chamber. 
     Method for Fabricating A Polysilicon Film 
     FIRST EMBODIMENT 
     The first embodiment of the polysilicon film fabricating method according to the present invention is as follows. The multi-chamber type semiconductor device fabricating apparatus shown in FIG. 2 is used in the first embodiment. In this embodiment, the reaction chamber does not have to include five cooling jackets as shown in FIG. 3, it being sufficient to include only two cooling jackets on the upper  34  and bottom  36  walls. 
     After loading the semiconductor wafer  204  for forming the polysilicon film in the cassette chamber  200 , the pressure of the cassette chamber  200  is adjusted to less than 0.05 mtorr by performing a pumping down operation for more than ten minutes. The reason why the pumping down should be performed for more than ten minutes is shown in FIG. 4, since the maximum pressure decrease is achieved in the first ten minutes. 
     The robot arm  212  transfers the wafer  204  from the cassette chamber  200  to the reaction chamber  220  via the wafer transfer chamber  210 . The polysilicon film is formed by injecting a source (reactant) gas into the reaction chamber, with the gas being selected from the group consisting of silane, disilane, and the gas mixture in which silane and disilane are mixed in the 30:1 to 1:30 ratio. The HSG-Si is thereafter formed by performing a thermal treatment thereon. The polysilicon film is preferably used as a lower electrode of the capacitor. 
     By keeping the pressure of the cassette chamber  200  to less than 0.05 mtorr, the influx of the atmospheric contaminants into the wafer transfer chamber  210  is prevented. Also, the moisture, generated by the wet pre-processing that removes the native oxide film or organic material on the surface of the wafer, can be completely evaporated from the surface of the wafer. Therefore, the problem that the remaining moisture on the surface of the wafer evaporates in the wafer transfer chamber or the reaction chamber and acts as a contaminant is solved since the influx of the contaminant gas into the wafer transfer chamber  210  or the reaction chamber  220  is prevented. 
     SECOND EMBODIMENT 
     The second embodiment of the polysilicon film fabricating method according to the present invention is different from the first embodiment in that the pressure of the cassette chamber  200  is not controlled, but the pressure of the wafer cooling chamber  230  is controlled to be about equal to that of the wafer transfer chamber  210 . 
     In particular, in this embodiment, the wafer whose reaction is completed is cooled in the cooling chamber  230  after adjusting the pressure of the wafer cooling chamber  230  to be equal to that of the wafer transfer chamber  210  without injecting a cooling gas. The pressure of the wafer cooling chamber  230  and the wafer transfer chamber  210  is preferably kept to less than about 1 μtorr. If the wafer is cooled in the wafer cooling chamber  230  without using the cooling gas, the pressures of the wafer transfer chamber and the reaction chamber do not increase since we do not inject the pressure of the cooling gas. Therefore, the problem that an increased pressure of the reaction chamber results in contamination of the surface of the wafer during the step of heating the wafer may be prevented. 
     THIRD EMBODIMENT 
     In the third embodiment of the present invention, the polysilicon film is fabricated using the reaction chamber shown in FIG. 3, including all the cooling jackets  400 ,  410 ,  420 ,  430  and  440 . 
     First, the wafer for forming the polysilicon film is loaded in the cassette chamber  200 . The robot arm  212  places the wafer on the susceptor  394  in the reaction chamber  220  through the wafer transfer chamber  210 . Then, the temperature of the reaction chamber  220  is raised to a certain temperature by the heater  390  in the heating block  392 . 
     The amorphous silicon film is formed to a predetermined thickness on the wafer using a source gas selected from the group consisting of silane, disilane, and the gas mixture in which silane and disilane are mixed in the 30:1 to 1:30 ratio. The polysilicon film is completed by forming the HSG-Si using a thermal treatment on the wafer on which the amorphous silicon film is formed. The polysilicon film is preferably used as a lower electrode of the capacitor. 
     When the process proceeds in the reaction chamber  220 , the problem that gas is exuded from the walls of the cooling chamber is prevented by supplying the refrigerant to the first to fifth cooling jackets  400 ,  410 ,  420 ,  430 , and  440 . Therefore, according to the third embodiment, it is possible to form the polysilicon film whose area is enlarged to a maximum extent. 
     The characteristics of the present invention are described in detail with reference to the following examples. However, the present invention is not restricted to the examples, and it is clearly understood that many variations can be made within the scope and spirit of the present invention by anyone skilled in the art. 
     EXAMPLE 1 
     A wafer having an insulating layer with a contact hole exposing a source region has already been formed and loaded on a susceptor  394  in the semiconductor device fabricating apparatus shown in FIG.  3 . The capacitor having an enlarged surface area is fabricated by forming an amorphous silicon layer to the thickness of 3000 Å by flowing the disilane gas. The HSG-Si is then formed by flowing the disilane gas at a rate of 18 sccm on the surface of the amorphous silicon layer while keeping the temperature of wafer to 620° C. During the above process, the temperature of the walls of the wafer cooling chamber are kept to about 10° C. by flowing the 9° C. refrigerant into the first to the fifth cooling jackets  400 ,  410 ,  420 ,  430  and  440 . 
     The scanning electron microscope (SEM) photographs of the lower electrode of the capacitor formed by the above process are shown in FIGS. 5A to  5 E. FIGS. 5A to  5 E show the photographs of the surface of the lower electrode of the capacitor formed in the positions of the wafer shown in FIG. 5F, respectively. Reference numerals  500 A,  500 B,  500 C,  500 D, and  500 E respectively denote the insulating layers. Reference numerals  502 A,  502 B,  502 C,  502 D, and  502 E respectively denote the surfaces of the lower electrodes on which the HSG-Si is formed. As noted from the above photographs, the surface area is maximized regardless of the position of the wafer on which the lower electrode is formed since HSG-Si is uniformly formed on the surface of the lower electrode. 
     To clearly check and compare the gas exudation feature of the present invention to that of the conventional art, the lower electrode of the capacitor is also formed in the conventional semiconductor device fabricating apparatus shown in FIG. 1, after controlling the processing conditions, such as reaction gas and temperature, to be equal to that of the present invention. The SEM photographs of the lower electrodes of a contrast group are shown in FIGS. 6A and 6B. FIGS. 6A and 6B respectively show the lower electrode formed in the reaction chamber which is adjacent to the wafer transfer chamber and the lower electrode formed in the reaction chamber which is adjacent to a vent portion. The reference numerals  600 A and  600 B respectively denote the insulating films. The reference numerals  602 A and  602 B respectively denote the surfaces of the lower electrodes on which the HSG-Si is formed. It is noted that there exist the portions in which the formation of the surface flection degrades. 
     When the lower electrode of the capacitor is formed using the semiconductor device fabricating apparatus according to the present invention, the temperature of the walls of the reaction chamber, especially, the gate valve  118 , the first wall  300  to which the gate valve  118  is connected, and the second wall  320  on which the vent portion is formed, can be kept low. Therefore, the problem that the formation of the surface flection degrades as the speed of the surface movement decreases due to the exuded gas is overcome since the gas exudation from the chamber walls is prevented. 
     EXAMPLE 2 
     To examine the relations between the pressure of the cassette chamber and the pressure of the wafer transfer chamber, and between the pressure of the cassette chamber and the pressure of the reaction chamber, the pressure between the respective chambers are measured and provided in Table 1 below: 
     
       
         
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
             
             
               
                   
                   
               
               
                   
                 wafer transfer chamber 
                 reaction chamber 
               
             
          
           
               
                   
                 cassette 
                 initial 
                 changed 
                 initial 
                 changed 
               
               
                   
                 chamber 
                 pressure 
                 pressure 
                 pressure 
                 pressure 
               
               
                   
                   
               
             
          
           
               
                 contrast group 
                  0.1 mtorr 
                 0.23 μtorr 
                  2.2 μtorr 
                 7.3 ntorr 
                 20 ntorr 
               
               
                 experimental 
                 0.02 mtorr 
                 0.23 μtorr 
                 0.23 μtorr 
                 7.3 ntorr 
                 13 ntorr 
               
               
                 group 
               
               
                   
               
             
          
         
       
     
     As noted from the results of the experimental group, in the case of controlling the pressure of the cassette chamber to about 0.02 mtorr, even though the gate valves between the cassette chamber  200  and the wafer transfer chamber  210  and between the cassette chamber  200  and the reaction chamber  220  are opened, the pressure in the wafer transfer chamber does not increase. 
     The lower electrode with the HSG-Si is also formed by depositing the amorphous silicon film after adjusting the pressure of the cassette chamber to be 0.05 mtorr and flowing the disilane source gas at a rate of 18 sccm while keeping the temperature of the wafer at 620° C. The SEM photograph of the surface of the lower electrode is shown in FIG.  7 A. 
     As a comparison, FIG. 7B shows the SEM photograph of the lower electrode formed by controlling the pressure of the cassette chamber to about  0 . lmtorr and controlling the other conditions to be equal to those of the example of FIG. 7A of the present invention. The reference numerals  700 A and  700 B respectively denote the insulating layers. The reference numerals  702 A and  702 B respectively denote the surfaces of the lower electrodes. 
     As noted from FIG. 7A, while it is possible to form a uniform HSG-Si on the surface of the lower electrode in the case of controlling the pressure of the cassette chamber to be 0.05 mtorr according to the present invention, the degradation of the surface flection is generated as shown from FIG. 7B by the atmospheric contaminants and the evaporated vapor from the wafer as in the conventional technology. 
     FIG. 8 is a bar graph showing the value of measuring the maximum capacitance of the capacitor shown in FIGS. 7A and 7B. This result shows the mean value of the maximum capacitance measured from 10 wafers. As noted from the graph, the capacitance of the capacitor formed by the present inventions is 65(fF/cell), which is twice that of the capacitor formed by the conventional technology, i.e., 30(fF/cell). 
     EXAMPLE 3 
     To examine the relations between the pressure of the cooling chamber  230  and the pressure of the wafer transfer chamber  210 , and between the pressure of the cooling chamber  230  and the pressure of the reaction chamber  220 , the pressure between the respective chambers are measured and provided in Table 2 below: 
     
       
         
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                 TABLE 2 
               
             
             
               
                   
                   
               
               
                   
                 wafer 
                 wafer transfer chamber 
                 reaction chamber 
               
             
          
           
               
                   
                 cooling 
                 initial 
                 changed 
                 initial 
                 changed 
               
               
                   
                 chamber 
                 pressure 
                 pressure 
                 pressure 
                 pressure 
               
               
                   
                   
               
             
          
           
               
                 contrast 
                 240 mtorr 
                 0.25 μtorr 
                  2.3 μtorr 
                 7.3 ntorr 
                 2.3 μtorr 
               
               
                 group 
               
               
                 experimental 
                  1 μtorr 
                 0.25 μtorr 
                 0.25 μtorr 
                 7.3 ntorr 
                  15 ntorr 
               
               
                 group 
               
               
                   
               
             
          
         
       
     
     As noted from the results of the contrast group, in the case of cooling the wafer in the wafer cooling chamber, the injected cooling gas raises the pressure of the wafer transfer chamber (0.25 μtorr→2.3 μtorr). Also, when transferring the wafer to the reaction chamber to perform another process on the wafer, the cooling gas raises the pressure of the reaction chamber (7.3 ntorr→2.3 μtorr). Such an increased pressure causes contamination of the surface of the wafer. 
     In the experimental group, where the cooling of the wafer in the wafer cooling chamber is carried out under a pressure that is about equal to that of the wafer transfer chamber, i.e., 1 μtorr without injecting the cooling gas, there is no change in the pressure in the wafer transfer chamber  210  and a slight change in the pressure in the reaction chamber  220 , thus suppressing the contamination of the reaction chamber  220 . 
     FIG. 9A is a SEM photograph of the surface of the lower electrode, in which the HSG-Si is formed by depositing the amorphous silicon film after equalizing the pressure of the wafer cooling chamber and the wafer transfer chamber at about 1 μtorr, and having a source gas of disilane flowing at a rate of 18 sccm while keeping the wafer temperature at about 620° C. 
     FIG. 9B is a SEM photograph of the lower electrode formed by injecting argon at a pressure of 240 mtorr as the cooling gas and controlling the other conditions to be equal to those of the example in FIG.  9 A. The reference numerals  900 A and  900 B denote the insulating layers. The reference numerals  902 A and  902 B denote the surface of the lower electrode. 
     It is noted from the result of FIG. 9A that a flection is uniformly formed on the surface of the amorphous silicon when the pressure of the wafer cooling chamber and the wafer transfer chamber are both kept under 1 μtorr. It is also noted from the result of FIG. 9B that it is impossible to obtain a desirable surface flection effect due to the reduction of the speed of the surface migration of the amorphous silicon atoms to the crystalline silicon when the wafer is cooled in the wafer cooling chamber using the cooling gas and the pressure of the wafer cooling chamber is higher than 1 μtorr. 
     EXAMPLE 4 
     FIG. 10A depicts the result of measuring the capacitances of the respective portions of the wafer after forming the lower electrode of the capacitor by controlling the pressure of the cassette chamber to be about 0.05 mtorr and that of the wafer cooling chamber and the wafer transfer chamber to be less than 1 μtorr and controlling the other conditions to be equal to those of Example 1 above. 
     The capacitances of the respective portions of the wafer after forming the lower electrode of the capacitor by a conventional processing condition using the conventional apparatus is shown in FIG.  10 B. The numbers in the respective blocks denote the capacitances. It is noted from FIGS. 10A and 10B that the lower electrodes have a uniform capacitance throughout the whole surface of the wafer when the lower electrode of the capacitor is formed by the present invention. 
     FIG. 11 is a graph showing the capacitance measured after continuously performing the process on the five wafers according to the fourth example. When the polycrystalline silicon film is formed using the semiconductor device fabricating apparatus according to the present invention, it is possible to obtain the uniform capacitance result. The reproducability is high compared with the conventional apparatus and method even though the process is continuously performed. 
     In particular, when the reaction chamber  220  includes all the cooling jackets like the apparatus of FIG. 3 of the present invention, the reliability of the processing performance is improved since it is possible to prevent gas from being exuded in the reaction chamber. Also, when the polycrystalline silicon film is formed using the semiconductor device fabricating apparatus according to the present invention, it is possible to prevent the reduction of the speed of the surface migration of the amorphous silicon due to the contaminants. Therefore, it is possible to repeatedly form a capacitor having high capacitance. 
     While preferred embodiments of the present invention have been described, it will be understood by those skilled in the art that various changes and modifications may be made, and equivalents may be substituted for elements thereof without departing from the true scope of the present invention. Therefore, it is intended that the present invention not be limited to the particular embodiments disclosed, but that the present invention include all embodiments falling within the scope of the appended claims.

Technology Category: 8