Patent Publication Number: US-2016237569-A1

Title: Semiconductor manufacturing apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from the prior U.S. Provisional Patent Application No. 62/115,331 filed on Feb. 12, 2015, the entire contents of which are incorporated herein by reference. 
    
    
     FIELD 
     Embodiments relate to a semiconductor manufacturing apparatus. 
     BACKGROUND 
     A CVD (Chemical Vapor Deposition) apparatus is conventionally used in a semiconductor manufacturing process. A heater that heats a wafer is provided in a chamber of the CVD apparatus, for example, to control a deposition rate in a film formation process. The heater has a pocket (that is, a counterbore part) surrounded by a sidewall to mount the wafer thereon. The wafer transported to the CVD apparatus is supported above the heater by lift pins and then the lift pins are lowered to mount the wafer on a mount face, which is the bottom face of the pocket. 
     However, the wafer may be deviated from the mount face due to deviation in support positions of the wafer by the lift pins, or the like. If the wafer is deviated from the mount face, the wafer may run the sidewall over, which causes a gap between the wafer and the mount face. In this case, the temperature of the wafer is locally lowered due to the gap and thus the film thickness in the plane of the wafer becomes non-uniform. For example, in a process that is sensitive to the temperature of a wafer such as a non-doped silicate glass (NSG) film, the deposition rate is increased in a portion where the temperature is locally lowered as compared to other portions, which locally increases the film thickness. 
     Therefore, to improve the uniformity in the film thickness, it is required to eliminate positional deviation of the wafer with respect to the mount face to enable a gap between the wafer and the mount face to be eliminated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic cross-sectional view of a semiconductor manufacturing apparatus  1  according to a first embodiment; 
         FIG. 2  is a plan view of a heater  12  of the semiconductor manufacturing apparatus  1  shown in  FIG. 1 ; 
         FIG. 3A  shows a semiconductor substrate  2  supported by lift pins  16  of the semiconductor manufacturing apparatus  1  shown in  FIG. 1 ,  FIG. 3B  shows the semiconductor substrate  2  having positional deviation, and  FIG. 3C  shows the semiconductor substrate  2  from which the positional deviation has been eliminated; 
         FIG. 4  is a plan view of the heater  12 , showing a modification of the first embodiment; 
         FIG. 5  shows the semiconductor manufacturing apparatus  1  according to a second embodiment; and 
         FIG. 6  shows the semiconductor substrate  2  from which positional deviation has been eliminated in the semiconductor manufacturing apparatus  1  shown in  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION 
     According to an embodiment, a semiconductor manufacturing apparatus includes a heater, a sidewall, and a moving mechanism. The heater is capable of heating a semiconductor substrate. The sidewall is located at an outer edge of the heater and protrudes upward from a mount face of the heater on which the semiconductor substrate is mounted. The moving mechanism relatively moves at least a part of the sidewall and the heater in a substantially perpendicular direction with respect to the mount face. 
     Embodiments will now be explained with reference to the accompanying drawings. The present invention is not limited to the embodiments. 
     First Embodiment 
     First, an embodiment of a semiconductor manufacturing apparatus in which a part of a sidewall is a moving part is explained as a first embodiment.  FIG. 1  is a schematic cross-sectional view of a semiconductor manufacturing apparatus  1  according to the first embodiment.  FIG. 2  is a plan view of a heater  12  of the semiconductor manufacturing apparatus  1  shown in  FIG. 1 .  FIG. 1  is also a cross-sectional view along a line I-I in  FIG. 2 . 
     The semiconductor manufacturing apparatus  1  shown in  FIG. 1  is a plasma CVD apparatus that performs a film formation process through plasma CVD. The semiconductor manufacturing apparatus  1  includes a susceptor  12  and a showerhead electrode  13  that face each other in a vertical direction D 1  inside a chamber  11 . A semiconductor substrate  2  (a wafer) (see  FIG. 3 ) can be mounted on the susceptor  12 . The susceptor  12  functions as an electrode that produces plasma and functions also as a heater (explained later). The showerhead electrode  13  is a hollow electrode having nozzles. A source gas is supplied into the showerhead electrode  13  from a supply source (not shown) of the source gas via a pipe  14 . The showerhead electrode  13  discharges the supplied source gas toward the semiconductor substrate  2  through the nozzles. A high-frequency wave is applied by a power supply (not show) to the showerhead electrode  13  or the susceptor  12 . The source gas discharged into the chamber  11  in a vacuum state is ionized by an electric field based on the high-frequency wave, thereby becoming deposition species. 
     The deposition species move onto the semiconductor substrate  2 , thereby forming a film. 
     The susceptor  12  has a function of a heater capable of heating the semiconductor substrate  2 . The susceptor  12  is hereinafter referred to also as “heater  12 ”. The heater  12  can, for example, incorporate therein a heating wire that generates heat due to application of current and heat the semiconductor substrate  2  using generated heat of the heating wire. With the heater  12 , the deposition rate (that is, the film formation rate) can be adjusted by heating the semiconductor substrate  2 . 
     The heater  12  has a mount face  121  on which the semiconductor substrate  2  is mounted. The mount face  121  is, for example, a circular area on a surface of the heater  12 . 
     The semiconductor manufacturing apparatus  1  also includes a plurality of lift pins  16  that mounts the semiconductor substrate  2  on the mount face  121 . The lift pins  16  extend in the vertical direction D 1  to pass through the heater  12 . The lift pins  16  can be moved (raised) to a substrate reception position (explained later) to support the semiconductor substrate  2  transported into the chamber  11 . The lift pins  16  can be moved (lowered) to a substrate mount position (explained later) while supporting the semiconductor substrate  2 , thereby mounting the semiconductor substrate  2  on the mount face  121 . 
     Respective lower ends of the lift pins  16  are coupled together by an annular first coupling ring  17 . The first coupling ring  17  is fixed to a first drive rod  18  that raises or lowers the lift pins  16  together. The first drive rod  18  extends downward to pass through the chamber  11  and is connected at a lower end to a first servo mechanism  19  outside the chamber  11 . The first servo mechanism  19  can, for example, include a motor, a gear that converts a rotational motion of the motor to a translational motion in the vertical direction D 1  and that transmits the translational motion to the first drive rod  18 , and a controller for the motor. 
     The semiconductor manufacturing apparatus  1  also includes a sidewall  110  provided at an outer edge of the heater  12 . As shown in  FIG. 2 , the sidewall  110  is annular and surrounds the entire periphery of the mount face  121 . As shown in  FIG. 1 , the sidewall  110  protrudes upward from the mount face  121 . A portion  1101  of a top face of the sidewall  110  in a predetermined range on an inner side (the side of the center of the heater  12 ) is inclined downward as approaching the heater  12 . The inclined portion  1101  of the top face of the sidewall  110  is hereinafter referred to also as “inclined face  1101 ”. 
     The sidewall  110  forms a counterbore part C together with the mount face  121 . Specifically, the mount face  121  forms the bottom face of the counterbore part C and the top face (the inclined face  1101 ) of the sidewall  110  forms the side face of the counterbore part C. The inclination angle of the inclined face  1101  is substantially uniform (including uniform) all around the sidewall  110 . Although not limited thereto, the inclination angle of the inclined face  110  can be, for example, 45 degrees with respect to the mount face  121 . 
     If the semiconductor substrate  2  is deviated from the mount face  121 , the semiconductor substrate  2  becomes a state partially running the sidewall  110  over, that is, a state inclined with respect to the mount face  121 . In this case, because the inclined face  1101  is provided on the sidewall  110 , the semiconductor substrate  2  slides in a radial direction D 2  along the inclined face  1101  under its own weight. Due to being capable of sliding, the semiconductor substrate  2  can modify the mount position to bring the entire rear surface into contact with the mount face  121 . That is, positional deviation of the semiconductor substrate  2  from the mount face  121  can be eliminated. The sidewall  110  has an annular shape and thus, in whichever radial direction D 2  the semiconductor substrate  2  is deviated from the mount face  121 , the semiconductor substrate  2  can be in contact with the inclined face  1101  in the direction of deviation. Accordingly, in whichever direction the semiconductor substrate  2  is deviated, the positional deviation of the semiconductor substrate  2  can be eliminated using the inclination of the inclined face  1101 . When the semiconductor substrate  2  is thus moved along the inclined face  1101  to an appropriate position under its own weight, no problems occur. However, if the semiconductor substrate  2  runs the sidewall  110  over and then stops, process variation occurs in the plane of the semiconductor substrate  2  as described above. 
     For example, when the positional deviation of the semiconductor substrate  2  is small, the positional deviation can be eliminated by using the inclination of the inclined face  1101  in the manner as described above. However, if the positional deviation of the semiconductor substrate  2  is large, it is difficult to reliably eliminate the positional deviation only by using the inclination of the inclined face  1101 . When the positional deviation is large, the semiconductor substrate  2  stops due to frictional force or the like before reaching the bottom of the inclined face  1101  even if the semiconductor substrate  2  can slide on the inclined face  1101 . In this case, the semiconductor substrate  2  is kept running the sidewall  110  over and the positional deviation cannot be eliminated. 
     To address this problem, the semiconductor manufacturing apparatus  1  includes a moving part  1102  and a moving mechanism  111  to reliably eliminate positional deviation of the semiconductor substrate  2  from the mount face  121 . 
     As shown in  FIG. 2 , the moving part  1102  is a part of the sidewall  110  and a plurality (three, for example) of the moving parts  1102  are provided along the outer edge of the mount face  121  at substantially equal intervals (including equal intervals). 
     The moving parts  1102  are movable in a substantially perpendicular direction (including a perpendicular direction) with respect to the mount face  121 . The moving parts (movable parts)  1102  can have an arbitrary shape as long as it has the inclined face  1101  and a claw shape, a pin shape, a rod shape, or the like can be used. 
     As shown in  FIG. 1 , the moving parts  1102  pass through the heater  12  to extend to below the heater  12 . An annular second coupling ring  1103  that couples the moving parts  1102  together is fixed to respective lower ends of the moving parts  1102 . 
     The moving mechanism  111  relatively moves at least a part of the sidewall  110  and the heater  12  in a direction substantially perpendicular to the mount face  121 . Specifically, the moving mechanism  111  moves the moving parts  1102  in the vertical direction D 1 . More specifically, the moving mechanism  111  includes a second drive rod  1111  that drives the moving parts  1102 , and a second servo mechanism  1112  serving as a power source of the second drive rod  1111 . The second drive rod  1111  extends in the vertical direction D 1  and is fixed at an upper end to the second coupling ring  1103 . A portion of the second drive rod  1111  on the side of a lower end passes through the chamber  11  to be drawn outside. The lower end of the second drive rod  1111  is connected to the second servo mechanism  1112  outside the chamber  11 . 
     The second servo mechanism  1112  transmits power in the vertical direction D 1  to the second drive rod  1111 . The second servo mechanism  1112  can include, for example, a motor, a gear that converts a rotational motion of the motor to a translational motion in the vertical direction D 1  and that transmits the translational motion to the second drive rod  1111 , and a controller for the motor. 
     With the moving parts  1102  and the moving mechanism  111 , the inclined faces  1101  of the moving parts  1102  can be raised with respect to the mount face  121 . With rise of the inclined faces  1101  of the moving parts  1102 , the angles (the inclinations) of the semiconductor substrate  2  with respect to the inclined faces  1101  and the mount face  121  change and thus a balance of force (frictional force or moment) that is stopping (immobilizing) the semiconductor substrate  2  is lost between the semiconductor substrate  2 , and the inclined faces  1101  and the mount face  121 . This enables the semiconductor substrate  2  to slide on the inclined faces  1101  under its own weight and thus the positional deviation of the semiconductor substrate  2  can be reliably eliminated. 
     An operation example of the semiconductor manufacturing apparatus  1  shown in  FIG. 1  is explained next with reference to  FIGS. 3 .  FIG. 3A  shows the semiconductor substrate  2  supported by the lift pins  16  of the semiconductor manufacturing apparatus  1  shown in  FIG. 1 .  FIG. 3B  shows the semiconductor substrate  2  having positional deviation.  FIG. 3C  shows the semiconductor substrate  2  from which the positional deviation has been eliminated. In  FIGS. 3A and 3B , arrows indicate a moving direction of the lift pins  16 . In  FIG. 3C , arrows indicate a moving direction of the moving parts  1102 . 
     First, the lift pins  16  are raised by power of the first servo mechanism  19  (see  FIG. 1 ) from a reference position to a substrate reception position where the semiconductor substrate  2  is received.  FIG. 3A  shows the lift pins  16  raised to the substrate reception position. The reference position can be a position where upper ends of the lift pins  16  are on the same level as the mount face  121  (see  FIG. 1 ). In this case, the reference position matches a substrate mount position where the semiconductor substrate  2  is mounted on the mount face  121 . 
     At the substrate reception position, the semiconductor substrate  2  is transported by a transport robot (not shown) to the upper ends of the lift pins  16 . The lift pins  16  then receive the transported semiconductor substrate  2 . Specifically, as shown in  FIG. 3A , the lift pins  16  support the rear surface of the transported semiconductor substrate  2  from below. The moving parts  1102  are at a position (a reference position) on the same level as other portions of the sidewall  110  until the lift pins  16  are moved to the substrate mount position. 
     Next, the lift pins  16  are lowered by power of the first servo mechanism  19  to the substrate mount position while supporting the semiconductor substrate  2 . Subsequently, as shown in  FIG. 3B , the lift pins  16  mounts the semiconductor substrate  2  on the mount face  121  at the substrate mount position. At that time, the semiconductor substrate  2  may run the sidewall  110  over due to deviation of the semiconductor substrate  2  from the mount face  121 . In a case where the positional deviation of the semiconductor substrate  2  is large, even if the semiconductor substrate  2  can slide along the inclined face  1101 , the slide of the semiconductor substrate  2  is restricted by frictional force with the inclined faces  1101  or the mount face  121  and consequently the semiconductor substrate  2  stops while running the inclined face  1101  over. 
     Next, the moving parts  1102  are raised by the moving mechanism  111 . With rise of the moving parts  1102 , a balance of force (the frictional force or moment) that is stopping the semiconductor substrate  2  is lost and thus the semiconductor substrate  2  becomes capable of sliding easily along the inclined faces  1101  of the moving parts  1102  under its own weight. Accordingly, the mount position of the semiconductor substrate  2  is modified from a position where the semiconductor substrate  2  is running the sidewall  110  over to a position where the semiconductor substrate  2  falls into place on the mount face  121 , thereby eliminating the positional deviation. 
     Subsequently, the moving parts  1102  are lowered by the moving mechanism  111  from the most raised position to a position on the same level as other portions of the sidewall  110 . 
     Thereafter, the source gas is supplied into the chamber  11  and plasma is produced between the susceptor  12  as the electrode and the electrode  13 , thereby forming a film on the semiconductor substrate  2 . During formation of a film, the semiconductor substrate  2  is heated by the heater  12  to control the deposition rate of the film. At that time, because the positional deviation of the semiconductor substrate  2  is eliminated, there is no gap between the semiconductor substrate  2  and the mount face  121 . Therefore, a local temperature decrease in the semiconductor substrate  2  due to a gap can be avoided and the deposition rate in the plane of the semiconductor substrate  2  can be uniformized. Uniformization of the deposition rate can enhance the uniformity in the film thickness in the plane of the semiconductor substrate  2 . 
     As described above, with the semiconductor manufacturing apparatus  1  according to the first embodiment, the moving parts  1102  can be raised with respect to the mount face  121  and thus positional deviation of the semiconductor substrate  2  can be reliably eliminated. As a result, the uniformity in the film thickness can be enhanced. 
     The first embodiment is also applicable to formation of a non-doped silicate glass film on the semiconductor substrate  2 . A film formation process of a non-doped silicate glass film is a process sensitive to the temperature and the film thickness is likely to become non-uniform due to a local temperature decrease in the semiconductor substrate  2  based on a gap between the mount face  121  and the semiconductor substrate  2 . Because positional deviation of the semiconductor substrate  2  can be eliminated according to the first embodiment, the gap between the semiconductor substrate  2  and the mount face  121  can be reliably eliminated. Because the gap can be eliminated, respective portions of the semiconductor substrate  2  can be heated uniformly and a local temperature decrease can be avoided. As a result, a non-doped silicate glass film with a uniform thickness can be formed. The first embodiment is applicable to a formation process of films other than the non-doped silicate glass film. 
     The first embodiment is also applicable to a film formation process using thermal CVD. When the first embodiment is applied to the thermal CVD, it suffices to provide a stage having a heater incorporated therein instead of the susceptor  12 . The first embodiment is also applicable to reactive ion etching (RIE). 
     (Modification) 
     A modification of the first embodiment in which the entire sidewall is a moving part is explained next. In the explanations of the present modification, as for constituent elements identical to those shown in  FIG. 1 , like reference characters as those in  FIG. 1  are used and redundant explanations thereof will be omitted.  FIG. 4  is a plan view of the heater  12 , showing a modification of the first embodiment. 
     As shown in  FIG. 4 , in the present modification, the entire annular sidewall  110  is the moving part  1102  capable of moving upward with respect to the mount face  121 . That is, in the present modification, the moving part  1102  is provided all around the mount face  121 . The inside diameter of the moving part  1102  is larger than the diameter of the semiconductor substrate  2 . 
     In the present modification, for example, the moving part  1102  incorporates therein a heating wire, thereby having a function of a heater. 
     According to the present modification, the moving part  1102  is provided all around the mount face  121 . Therefore, in whichever radial direction D 2  the semiconductor substrate  2  is deviated, the semiconductor substrate  2  can be brought into contact with the inclined face  1101  of the moving part  1102  in the direction of the deviation. Accordingly, the present modification enables positional deviation to be more reliably eliminated. 
     Second Embodiment 
     An embodiment of a semiconductor manufacturing apparatus having a movable heater is explained next as a second embodiment. In the explanations of the second embodiment, as for constituent elements identical to those described in the first embodiment, like reference characters as those in the first embodiment are used and redundant explanations thereof will be omitted. 
       FIG. 5  shows the semiconductor manufacturing apparatus  1  according to the second embodiment.  FIG. 6  shows the semiconductor substrate  2  from which positional deviation has been eliminated in the semiconductor manufacturing apparatus  1  shown in  FIG. 5 . In  FIG. 6 , an arrow indicates a moving direction of the heater  12 . While the sidewall  110  is operated in the first embodiment, the heater  12  is moved in the second embodiment. Also when the heater  12  is moved in this way, the sidewall  110  can be caused to protrude relatively from the mount face  121  and thus the position of the semiconductor substrate  2  can be modified. Therefore, it suffices that the moving mechanism  111  relatively moves the sidewall  110  and the heater  12 . 
     In the second embodiment, the heater  12  is movable in the vertical direction D 1 . Furthermore, in the second embodiment, the moving mechanism  111  moves the heater  12 . Specifically, the moving mechanism  111  includes a support column  1113  and a third servo mechanism  1114 . A portion of the support column  1113  on the side of a lower end passes through the chamber  11  to be drawn outside. The lower end of the support column  1113  is connected to the third servo mechanism  1114  outside the chamber  11 . 
     The third servo mechanism  1114  transmits power in the vertical direction D 1  to the support column  1113 . The third servo mechanism  1114  can include, for example, a motor, a gear that converts a rotational motion of the motor to a translational motion in the vertical direction D 1  and that transmits the translational motion to the support column  1113 , and a controller for the motor. In the second embodiment, the sidewall  110  has an annular shape that surrounds the entire periphery of the mount face  121  and passes through the heater  12  to extend downward similarly to the modification ( FIG. 4 ) of the first embodiment. The sidewall  110  can also function as the moving part  1102  similarly in the first embodiment or can be fixed in an immovable state. 
     With the moving mechanism  111  according to the second embodiment, the heater  12 , that is, the mount face  121  can be lowered as shown in  FIG. 6 . By lowering the heater  12 , a balance of force (frictional force or moment) that is immobilizing the semiconductor substrate  2  can be lost similarly to the first embodiment. Accordingly, similarly to the first embodiment, the semiconductor substrate  2  can easily slide toward the mount face  121  under its own weight. The lift pins  16  can be lowered together with the heater  12  to prevent the lift pins  16  from interfering with slide of the semiconductor substrate  2 . 
     Therefore, according to the second embodiment, the heater  12  can be lowered and thus positional deviation of the semiconductor substrate  2  can be reliably eliminated as in the first embodiment. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.