Patent Publication Number: US-2016225650-A1

Title: Substrate holding device and semiconductor device manufacturing method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2015-016894, filed on Jan. 30, 2015; the entire contents of which are incorporated herein by reference. 
     FIELD 
     Embodiments described herein relate generally to a substrate holding device and a semiconductor device manufacturing method. 
     BACKGROUND 
     In manufacturing a semiconductor device, there is a case where a semiconductor wafer is deformed by receiving a stress, depending on a film formed on the semiconductor wafer. For example, in the case of a NAND type flash memory having a planar shape, residual stresses generated in the in-plane direction of a semiconductor wafer are isotropic, and so the semiconductor wafer is deformed into a bowl shape or umbrella shape. Further, in the case of a NAND type flash memory having a three-dimensional shape in which memory elements are three-dimensionally arranged, the memory cell region and the peripheral circuit region have different sectional structures. Consequently, residual stresses generated in the in-plane direction of a semiconductor wafer tend to be anisotropic, and so the semiconductor wafer is distorted into a saddle shape in some cases. 
     If a semiconductor wafer has been deformed as described above, when the semiconductor wafer is placed on a stage in a semiconductor manufacturing apparatus, such as a light exposure apparatus, and is held by vacuum suction, the semiconductor wafer cannot be held in a normal state, because of a decrease in holding force applied thereto. As a result, a process performed in the semiconductor manufacturing apparatus is adversely affected. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view schematically showing an example of a configuration of a semiconductor manufacturing apparatus including a substrate holding device according to a first embodiment; 
         FIGS. 2A and 2B  comprise views schematically showing a configuration of a stage according to the first embodiment; 
         FIGS. 3A to 3C  comprise views schematically showing an example of a configuration of a movable bottom portion according to the first embodiment; 
         FIG. 4  is a flow chart showing an example of a sequence of a substrate holding method and a semiconductor device manufacturing method according to the first embodiment; 
         FIGS. 5A to 5C  comprise views showing an example of a case where a wafer is deformed in a bowl shape; 
         FIGS. 6A and 6B  comprise views showing an example of a case where a wafer is deformed in an umbrella shape; 
         FIGS. 7A to 7C  comprise views showing an example of a case where a wafer is deformed in a saddle shape; 
         FIGS. 8A and 8B  comprise views showing a configuration of a substrate holding device according to a comparative example; 
         FIGS. 9A to 9D  comprise views showing an example where a wafer is held by vacuum suction on the substrate holding device according to the comparative example; 
         FIG. 10  is a sectional view schematically showing an example of a state where a wafer is mounted on the substrate holding device according to the first embodiment; 
         FIGS. 11A to 11D  comprise views showing an example of a configuration of a substrate holding device according to a second embodiment; 
         FIG. 12  is a flow chart showing an example of a substrate holding method according to the second embodiment; 
         FIGS. 13A and 13B  comprise views showing an example of a method of mounting a wafer deformed in a saddle shape; 
         FIGS. 14A and 14B  comprise views showing an example of a method of mounting a wafer deformed in a saddle shape; 
         FIGS. 15A and 15B  comprise views showing another configuration example of the substrate holding device according to the second embodiment; and 
         FIG. 16  is a view schematically showing an example of a configuration of a semiconductor manufacturing apparatus according to a third embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     According to one embodiment, a substrate holding device includes a chuck main body and movable bottom portions. The chuck main body includes a plurality of pins fixed to a bottom face part in a mounting area for a substrate. The movable bottom portions, the number of which is two or more, are disposed to cover the mounting area for the substrate and to be movable in an extending direction of the pins, in a state where the pins are inserted in the movable bottom portions. When the substrate is mounted on the chuck main body, gas is exhausted from a space between the substrate and the bottom face part, to hold the substrate by suction. 
     Exemplary embodiments of a substrate holding device and a semiconductor device manufacturing method will be explained below in detail with reference to the accompanying drawings. The present invention is not limited to the following embodiments. 
     First Embodiment 
       FIG. 1  is a view schematically showing an example of a configuration of a semiconductor manufacturing apparatus including a substrate holding device according to a first embodiment. Here, the semiconductor manufacturing apparatus is exemplified by a light exposure apparatus  1 . The light exposure apparatus  1  includes a chamber  10  made of aluminum or stainless steel and configured to form a highly airtight space. 
     Inside the chamber  10 , there is provided a light source  11 , an illumination optical system  12 , a mask holder  13 , a projection optical system  14 , and a stage  15  serving as a substrate holding device. The light source  11  is formed of a device for emitting exposure light having a predetermined wavelength. 
     The illumination optical system  12  irradiates a mask  131  on the mask holder  13  with the exposure light from the light source  11 . The illumination optical system  12  includes a plurality of mirrors (not shown) for guiding the exposure light from the light source  11  to the mask  131 . 
     The mask holder  13  holds the mask  131 . The mask holder  13  is configured to be movable in a direction parallel with the mask mounting face. 
     The projection optical system  14  projects the exposure light reflected by the mask  131  onto the stage  15 . The projection optical system  14  includes a plurality of mirrors (not shown). 
     The stage  15  supports a substrate or wafer  100  by a plurality of pins, and fixes the wafer  100  by a vacuum suction mechanism. 
       FIGS. 2A and 2B  comprise views schematically showing a configuration of the stage according to the first embodiment.  FIG. 2A  is a top view, and  FIG. 25  is a sectional view taken along a line A-A in  FIG. 2A . As shown in  FIG. 2E , the stage  15  includes a chuck main body  150 . The chuck main body  150  includes a bottom face part  151  and a side face part  152  which is disposed around the bottom face part  151  and formed higher than the upper surface of the bottom face part  151 . The bottom face part  151  has a circular shape in this example, but it may have another shape. The area surrounded by the bottom face part  151  and the side face part  152  is a recessed area  153 . The recessed area  153  is formed at a position corresponding to the mounting position for the wafer  100 . The bottom face part  151  includes an exhaust hole  158  formed near the center and penetrating the bottom face part  151  in the thickness direction. The exhaust hole  158  is a single hole formed near the center of the bottom face part  151  in this example, but it may be formed of a plurality of holes. 
     Inside the recessed area  153 , a plurality of pins  154  are provided. The pins  154  have a predetermined height. Each of the pins  154  has a conical shape. This is intended to reduce a risk of local defocus when a foreign contaminant intervenes between the wafer  100  and the stage  15 . Each of the pins  154  has a diameter size of about 0.1 to 1 mm, and a height of about several tens to several hundreds μm. Here, all of the pins  154  have the same height. The pins  154  are arranged at predetermined intervals in a two-dimensional state inside the recessed area  153 . The lower ends of the pins  154  are fixed to the bottom face part  151  of the chuck main body  150 . 
     Further, inside the recessed area  153 , two or more movable bottom portions  155  are provided. The movable bottom portions  155  are formed by dividing a bottom part fit in the recessed area  153  into two or more portions. In this example, as shown in  FIG. 2R , a bottom part having a circular shape is divided by five concentric circles having different radiuses, and is further divided by eight straight lines passing through the center. Consequently, eighty movable bottom portions  155  are provided inside the recessed area  153 . The movable bottom portions  155  are supported by the bottom face part  151  through support portions  156 . 
       FIGS. 3A to 3C  comprise views schematically showing an example of a configuration of a movable bottom portion according to the first embodiment.  FIG. 3A  is a top view of one movable bottom portion,  FIG. 3B  is a side view of the movable bottom portion, and  FIG. 3C  is a sectional view taken along a line B-B in  FIG. 3A . This movable bottom portion  155  includes pin insertion holes  1551  and exhaust holes  1552 , which penetrate the movable bottom portion  155  in the thickness direction. The pin insertion holes  1551  are formed at positions corresponding to the arrangement positions of the pins  154 . The exhaust holes  1552  are formed at positions surrounded by a plurality of pin insertion holes  1551 . However, the exhaust holes  1552  may be formed at arbitrary positions. 
     The support portions  156  support the movable bottom portions  155  above the bottom face part  151 . Each of the support portions  156  includes a rod  1561 . One end of the rod  1561  is connected to the lower side of the movable bottom portion  155 , and the other end of the rod  1561  is connected to an actuator (not shown), such as a motor. When the rods  1561  are moved by the actuators in a direction perpendicular to the lower surface of the bottom face part  151 , the position (height) of the upper surface of the movable bottom portion  155  can be changed. Here, the movable bottom portion  155  is moved in a range in which the upper surface of the movable bottom portion  155  is lower than the upper end of the pin  154 . 
     The side face part  152  of the chuck main body  150  is provided with an annular upper wall member  157  disposed on the top. The upper wall member  157  is configured to form a vacuum space between the wafer  100  and the chuck main body  150 , and to support the outer peripheral portion of the wafer  100 . 
     As shown in  FIG. 1 , the stage  15  is equipped with a substrate stage control unit  20 . The substrate stage control unit  20  is configured to obtain data about the shape of the wafer  100  to be placed on the stage  15 , and to quantize the substrate heights of the wafer  100  at respective regions in the in-plane direction, and thereby to control the positions of the upper surfaces of the movable bottom portions  155  based on the quantized data. 
     When the wafer  100  is to be mounted on the stage  15  having configuration described above, the substrate stage control unit  20  adjusts the heights of the movable bottom portions  155  inside the recessed area  153 , in accordance with the quantized data indicating the shape of the wafer  100  to be mounted. Thereafter, the wafer  100  is mounted on the stage  15  and is held by vacuum suction by use of an exhaust device (not shown). 
     Next, an explanation will be given of a semiconductor device manufacturing method including a step of holding the wafer  100  on the substrate holding device according to the first embodiment.  FIG. 4  is a flow chart showing an example of a sequence of a substrate holding method and a semiconductor device manufacturing method according to the first embodiment. At first, substrate shape data is obtained (step S 11 ). The substrate shape data is data indicating the heights of the wafer  100  at respective positions. Based on a reference value set for the heights of the wafer  100 , the data indicates how high or how low each of the positions of the wafer  100  is relative to the reference value. The substrate shape data in this case is topography data about the wafer  100 . For example, the substrate shape data can be obtained from a result of measurement made by a Fizeau interferometer. 
     Here, the substrate shape data may be created by use of overlay deviation data. The overlay deviation data is data about positional deviation of overlays, which is caused when circuit patterns are overlaid from below on the wafer  100 . The relational expression between the result of overlay deviation and the shape is generally known, and thus the shape of the wafer  100  can be obtained by use of this relational expression. 
     Further, the substrate shape data may be created by use of alignment data. Also in the case of this alignment data, the shape of the wafer  100  can be obtained as in the case of the overlay deviation data. 
     Further, the substrate shape data may be created by use of stress data. In this case, data about stresses in the materials of films formed on the wafer  100  is used to estimate distortion generated in the wafer  100  and thereby to create the substrate shape data. Any one of these deviations described above can be used as the substrate shape data. 
     Then, the substrate shape data is quantized (step S 12 ). The substrate shape data of analog value obtained in the step S 11  is converted into substrate shape data of digital value, by use of gradations. Consequently, the substrate shape data becomes discrete value data. For example, in a case where the movable bottom portions  155  have sixteen height levels, the substrate shape data of analog value can be converted into the digital values of sixteen gradations. 
     Then, the quantized substrate shape data is taken into the semiconductor manufacturing apparatus. For example, the substrate stage control unit  20  reads the quantized substrate shape data. The substrate stage control unit  20  changes the heights of the movable bottom portions  155  of the stage  15 , in accordance with the quantized substrate shape data (step S 13 ). 
     Thereafter, the wafer  100  is transferred into the semiconductor manufacturing apparatus, and the wafer  100  is mounted on the stage  15  (step S 14 ). Then, an exhaust device connected to the exhaust hole  158  of the stage  15  starts exhausting gas, to hold the wafer  100  by vacuum chucking (step S 15 ). 
     Then, a semiconductor manufacturing process is performed to the wafer  100  inside the semiconductor manufacturing apparatus (step S 16 ). For example, in the case of the light exposure apparatus shown in  FIG. 1 , a light exposure process is performed to a resist applied on the wafer  100 . As a result, the processes are completed. 
     Next, an explanation will be given of an example of adjusting the heights of the movable bottom portions  155  in accordance with the substrate shape data.  FIGS. 5A to 5C  comprise views showing an example of a case where a wafer is deformed in a bowl shape.  FIG. 5A  shows an example of the substrate shape data,  FIG. 5B  shows an example of the quantized substrate shape data, and  FIG. 5C  shows a state after move of the movable bottom portions. For example, in a case where residual stresses generated in the in-plane direction of a substrate are isotropic, as in a NAND type flash memory having a planar shape, the wafer is distorted into a bowl shape as shown in  FIG. 5A . 
       FIG. 5B  shows a state where this substrate shape data is quantized at a position of y=0. In  FIG. 5B , the vertical axis denotes gradations at y=0 of the stage  15 . For example, in  FIG. 5B , the range from x 0  to x 1  represents a site corresponding to a movable bottom portion  155  positioned on the leftmost side. The analog values of the substrate shape data at this site are averaged, and this average value is converted into a gradation, which is assumed to be a 5 . Also for the sites corresponding to the other movable bottom portions, such gradations are obtained. Consequently, quantized substrate shape data is obtained such that the gradations have the lowest value of a 1  at the central sites (from x 4  to x 6 ) and increase stepwise one by one therefrom toward the outer peripheral sites. 
     In accordance with the quantized substrate shape data shown in  FIG. 5B , the substrate stage control unit  20  moves the movable bottom portions  155  in the height direction to be into a state shown in  FIG. 5C . The upper surfaces of the movable bottom portions  155  are lower at the central sites, and the upper surfaces of the movable bottom portions  155  are higher at the outer peripheral sites. In this way, the upper surfaces of the movable bottom portions  155  are moved to form the same shape as the warpage of the wafer  100 . 
       FIGS. 6A and 6B  comprise views showing an example of a case where a wafer is deformed in an umbrella shape.  FIG. 6A  shows an example of the substrate shape data, and  FIG. 6B  shows a state after move of the movable bottom portions. In this case, as shown in  FIG. 6A , the wafer  100  is deformed in an umbrella shape such that it is highest at the center and is lowest at the outer peripheral sides. For example, in a case where residual stresses generated in the in-plane direction of a substrate are isotropic, as in a NAND type flash memory having a planar shape, the wafer is distorted into an umbrella shape as shown in  FIG. 6A . 
     Also in this case, the form of the stage  15  is changed in a similar way as in the case shown in  FIGS. 5A to 5C . This result is shown in  FIG. 65 . As in the deformation of the wafer  100 , the upper surfaces of the movable bottom portions  155  are higher at the central sites and are lower at the outer peripheral sites. 
       FIGS. 7A to 7C  comprise views showing an example of a case where a wafer is deformed in a saddle shape.  FIG. 7A  shows an example of the substrate shape data,  FIG. 75  is a sectional view taken along a line A-A in  FIG. 2A , and  FIG. 7C  is a sectional view taken along a line C-C in  FIG. 2A . For example, in the case of a NAND type flash memory having a three-dimensional shape, the wafer  100  has different sectional structures at different positions of the wafer, such as the memory cell region and the peripheral circuit region. Consequently, residual stresses tend to be generated in an anisotropic state. In this case, the wafer  100  is distorted into a saddle shape, as shown in  FIG. 7A . 
     For example, at a position of x=0, the height of the wafer  100  is higher near the central portion and becomes lower toward the outer peripheral sides. However, at a position of y=0, the height of the wafer  100  is lower near the central portion and becomes higher toward the outer peripheral sides. Consequently, at the A-A cross section shown in  FIG. 2A , corresponding to y=0, the upper surfaces of the movable bottom portions  155  are moved as shown in  FIG. 7B . Further, at the C-C cross section shown in  FIG. 2A , corresponding to x=0, the upper surfaces of the movable bottom portions  155  are moved as shown in  FIG. 7C . 
     As described above, the bottom part is formed of a large number of movable bottom portions  155 , and thus it can handle a wafer  100  deformed in a more complicated shape. 
     Here, effects obtained by the substrate holding device according to the first embodiment will be explained, as compared with a substrate holding device according to a comparative example.  FIGS. 8R and 8B  comprise views showing a configuration of the substrate holding device according to the comparative example.  FIG. 8A  is a top view, and  FIG. 8B  is a sectional view taken along a line D-D in  FIG. 8A . 
     The substrate holding device according to the comparative example includes a plurality of pins  154  provided inside a recessed area  153  of a chuck main body  150 . The pins  154  are fixed to a bottom face part  151  of the chuck main body  150 . Further, a side face part  152  is configured to make a vacuum space between the wafer  100  and the bottom face part  151 , and to support the outer peripheral portion of a wafer  100 . As described above, the substrate holding device according to the comparative example does not include movable bottom portions, but includes the bottom face part  151  as the bottom part of the chuck main body  150 . Consequently, the height of the bottom face part  151  cannot be changed depending on the position. 
     Next, the substrate holding device according to the comparative example will be explained, in relation to a sequence of holding the wafer  100  by vacuum suction. FIGS.  9 A to  9 D comprise views showing an example where a wafer is held by vacuum suction on the substrate holding device according to the comparative example. At first, as shown in  FIG. 9A , the wafer  100  is mounted on the substrate holding device (chuck main body  150 ). Here, it is assumed that the wafer  100  is strained in a bowl shape. Further, the substrate holding device is considered by dividing it into five regions R 1  to R 5 . These regions R 1  to R 5  have the same surface areas. 
     In the substrate holding device according to the comparative example, the height of the bottom face part  151  is constant over all the regions R 1  to R 5 , as described above. Consequently, as regards the volume of a space portion sandwiched between the bottom face part  151  and the wafer  100 , that of the region R 1  is almost equal to that of the region R 5 , that of the region R 2  is almost equal to that of the region R 4 , that of the region R 1  is larger than that of the region R 2 , and that of the region R 2  is larger than that of the region R 3 . Accordingly, the amount of gas suction necessary for completion of the suction holding is larger at positions closer to the regions R 1  and R 5  on the outer peripheral sides where the warpage amount is larger. 
     Along with the progress of gas exhaust, the position of the wafer  100  is changed, as shown in  FIGS. 9B and 9C . Then, as shown in  FIG. 9C , the amount of gas suction necessary for completion of the suction holding becomes larger at positions closer to the outer peripheral sides, and so the wafer  100  floats above the upper surface of the substrate holding device. Consequently, the gas leakage becomes larger at the outer peripheral portion of the wafer  100 . Thus, as shown in  FIG. 9D , the vacuum chuck ends up being incomplete. 
       FIG. 10  is a sectional view schematically showing an example of a state where a wafer is mounted on the substrate holding device according to the first embodiment. In a case where the wafer  100  is deformed in a bowl shape, the stage  15  serving as a substrate holding device according to the first embodiment changes the heights of the respective movable bottom portions  155 , in accordance with the shape of the wafer  100 . Consequently, when the wafer  100  is mounted on the stage  15 , the volumes of space portions sandwiched between the wafer  100  and the movable bottom portions  155  are almost equal to each other between the regions R 1  to R 5 . As a result, after the start of gas exhaust, the gas exhaust can be completed at the same time over all the regions R 1  to R 5 . Thus, there is provided an effect capable of accurately holding the wafer  100  by suction. Further, the wafer  100  is held in an almost ideal state, and so the subsequent step of a semiconductor manufacturing process can be performed with high accuracy. 
     According to the first embodiment, the bottom part of the substrate holding device is divided into two or more regions, so that the heights of the bottom part can be individually changed, in accordance with the shape of a wafer  100  to be mounted. Consequently, the volumes of space portions sandwiched between the bottom part and the wafer  100  are almost equal to each other between the divisional regions, and so the suction holding can be made at the same time over all the regions. As a result, there is provided an effect capable of holding a deformed wafer  100  by suction on the substrate holding device, while planarly reforming it into a normal state. Further, the bottom part of the substrate holding device is divided into a number of portions, and thereby provides an effect capable of handling a wafer  100  deformed in a more complicated shape. 
     Second Embodiment 
     In the first embodiment, an explanation has been given of a substrate holding device that can planarly reform a wafer even if the wafer is deformed in an arbitrary shape. In the second embodiment, an explanation will be given of a substrate holding device that can hold a wafer exemplified by a case where the wafer is deformed in a saddle shape, as shown in  FIG. 7A , in a NAND type flash memory having a three-dimensional shape. 
       FIGS. 11A to 11D  comprise views showing an example of a configuration of the substrate holding device according to the second embodiment.  FIG. 11A  is a top view,  FIG. 11B  is a sectional view taken along line E-E in  FIG. 11A ,  FIG. 11C  is a sectional view taken along line F-F in  FIG. 11A , and  FIG. 11D  is a view showing high and low features of the bottom face along with the view shown in  FIG. 11A . The substrate holding device  15 A includes a chuck main body  150 . The chuck main body  150  includes a bottom face part  151  and a side face part  152 , wherein the side face part  152  is disposed near the outer peripheral portion of the bottom face part  151  and surrounds inside. A recessed area  153  is formed by the bottom face part  151  and the side face part  152 . On the bottom face part  151 , pins  154  are arranged with the same height. Further, the height of the side face part  152  is adjusted such that the upper surface position of the side face part  152  is flush with the upper end positions of the pins  154 . 
     The bottom face part  151  is divided by two concentric circles C 1  and C 2  having different radiuses, and is further divided by two straight lines L 1  and L 2  passing through the center. Consequently, the bottom face part  151  is divided into eight regions R 11  to R 14  and R 21  to R 24 . Here, the four regions defined by the straight lines L 1  and L 2  inside the concentric circle C 1  are referred to as R 11  to R 14 . Further, the four regions defined by the straight lines L 1  and L 2  inside the concentric circle C 2  and outside the concentric circle C 1  are referred to as R 21  to R 24 . 
     In the second embodiment, the bottom face part  151  of the chuck main body  150  is provided with high floor portions  160 , so that the heights of the regions R 11 , R 13 , R 22 , and R 24  are higher than the heights of the regions R 12 , R 14 , R 21 , and R 23 . The high and low relationship of the bottom face is shown in  FIG. 11D . 
     The combination of the regions R 11  and R 21 , the combination of the regions R 12  and R 22 , the combination of the regions R 13  and R 23 , and the combination of the regions R 14  and R 24  have the same shape as each other, when seen in plan view. Further, the combination of the regions R 11  and R 21  and the combination of the regions R 13  and R 23  are categorized as first bottom regions that have the same high and low relationship of the bottom face as each other. The combination of the regions R 12  and R 22  and the combination of the regions R 14  and R 24  are categorized as second bottom regions that have the same high and low relationship of the bottom face as each other. Here, the first bottom region and the second bottom region are alternately arranged in the plane. 
     The heights of the high floor portions  160  are determined in accordance with the degree of deformation of the wafer  100  to be mounted. For example, if the average value of the differences between the maximum value and the minimum value at positions of the wafer  100  to be mounted is 100 μm, the step size is set to 100 μm, and, if it is 200 μm, the step size is set to 200 μm. 
     Further, a rotary member  159  is provided below the bottom face part  151  of the chuck main body  150 . The rotary member  159  is configured to rotate the chuck main body  150  in the in-plane direction. This is intended to adjust the positions of the high floor portions  160 , in accordance with the deformation of the wafer  100  in the plane. 
     Next, an explanation will be given of an example of a substrate holding method performed in the substrate holding device according to the second embodiment.  FIG. 12  is a flow chart showing an example of a substrate holding method according to the second embodiment. At first, substrate shape data is obtained (step S 31 ). Consequently, the substrate shape data is obtained about the wafer  100  deformed in a saddle shape, as shown in  FIG. 7A . 
     Then, the substrate shape data is used to calculate the angle deviation of a lower position on the outer peripheral side (or a higher position on the outer peripheral side) relative to a reference position on the wafer  100  (step S 32 ). For example, the lowest position on the outer peripheral side (or the highest position on the outer peripheral side) is obtained. Then, at the intersection between a line segment, which connects the lowest position on the outer peripheral side (or the highest position on the outer peripheral side) to the center of the wafer  100 , and a line segment, which connects the notch of the wafer  100  (the center of the notch) to the center of the wafer  100 , their crossing angle is obtained. 
     Thereafter, the substrate stage control unit  20  rotates the substrate holding device by the angle thus calculated (step S 33 ). Consequently, the positions of the high floor portions  160  of the chuck main body  150  are set to conform to the deformation of the wafer  100  to be mounted. Then, the wafer  100  is mounted on the chuck main body  150  thus rotated (step S 34 ). Thereafter, an exhaust device exhausts gas from inside the recessed area  153  of the chuck main body  150  to hold the wafer  100  by vacuum chucking (step S 35 ). Then, a semiconductor manufacturing process is performed to the wafer  100  (step S 36 ). 
     Each of  FIGS. 13A, 13B, 14A and 14B  comprises views showing an example of a method of mounting a wafer deformed in a saddle shape.  FIGS. 13A and 14B  show an example of the substrate shape data, and  FIGS. 13B and 14B  show an example of rotation of the substrate holding device. Here, it is assumed that the substrate holding device has a reference position present at the position shown in  FIG. 11D . Further, the reference position of the substrate holding device is set to correspond to a reference position provided on the wafer  100  to be mounted, such as the notch arrangement position. 
     In the substrate shape data shown in  FIG. 13A , it is assumed that the notch is present at a position of y=0. Further, the lowest position on the outer peripheral side is present at a position rotated by 45° in a counter-clockwise direction from the notch position serving as a reference. Accordingly, as shown in  FIG. 13B , the substrate stage control unit  20  rotates the substrate holding device by 45° (−45°) in a counterclockwise direction from the state shown in  FIG. 11D , and thereby perform positioning. 
     In the substrate shape data shown in  FIG. 14A , it is assumed that the notch is present at a position of y=0. Further, the lowest position on the outer peripheral side is present at a position rotated by 90° in a clockwise direction from the notch position serving as a reference. Accordingly, as shown in  FIG. 14B , the substrate stage control unit  20  performs positioning by rotating the substrate holding device by 90° in a clockwise direction from the state shown in  FIG. 11D . 
     In  FIGS. 11B and 11C , the high floor portions  160 , each of which has a flat upper surface, are respectively disposed at the regions R 11 , R 13 , R 22 , and R 24 , but this configuration is not limiting.  FIGS. 15A and 15B  comprise views showing another configuration example of the substrate holding device according to the second embodiment.  FIG. 15A  is a view corresponding to the line E-E sectional view shown in  FIG. 11A , and  FIG. 15B  is a view corresponding to the line F-F sectional view shown in  FIG. 11A . As shown in  FIGS. 15A and 15B , a sloped high floor portion  161  may be provided over the respective regions. In other words, the bottom face part  151  of the chuck main body  150  may be shaped in a saddle shape. 
     It should be noted that the configuration shown in  FIGS. 11A to 11D  are a mere example, and this does not limit the embodiment. For example, the bottom face part  151  may be divided by three or more concentric circles having different radiuses, and may be divided by three or more straight lines passing through the center. 
     According to the second embodiment, the bottom face part  151  of the chuck main body  150  of the substrate holding device has a shape with heights corresponding to a saddle shape, and the chuck main body  150  is configured to be rotatable in the plane. Further, the chuck main body  150  is rotated to set the shape of the bottom face part  151  of the chuck main body  150  to conform to the shape of a wafer  100 , and then the wafer  100  deformed in a saddle shape is mounted. Consequently, the volumes of space portions sandwiched between the respective regions of the wafer  100  and the bottom face part  151  are almost equal to each other, and so the suction holding can be made at the same time over all the regions. As a result, there is provided an effect capable of holding a wafer  100 , deformed in a saddle shape, by suction on the substrate holding device, while planarly reforming it into a normal state. 
     Third Embodiment 
     The second embodiment is specialized for a case where a wafer is deformed in a saddle shape. However, there is a case a wafer is not deformed in a saddle shape. In the third embodiment, an explanation will be given of a semiconductor manufacturing apparatus that can address such a case. 
       FIG. 16  is a view schematically showing an example of a configuration of a semiconductor manufacturing apparatus according to the third embodiment. As shown in  FIG. 16 , two semiconductor manufacturing apparatuses  2 A and  2 B are provided, along with a wafer transfer section  30  and a control unit  40 . The semiconductor manufacturing apparatuses  2 A and  2 D are apparatuses configured to perform semiconductor manufacturing processes of the same type, and each of them includes a semiconductor manufacture processing part  25 . For example, the semiconductor manufacture processing part  25  is formed of a light exposure processing part, etching processing part, or film formation processing part. The semiconductor manufacturing apparatuses  2 A and  2 B respectively include substrate holding devices having different configurations from each other. The semiconductor manufacturing apparatus  2 A includes a substrate holding device  15 C according to the comparative example, and the semiconductor manufacturing apparatus  2 B includes a substrate holding device  15 A according to the second embodiment. 
     In accordance with an instruction from a control unit, the wafer transfer section  30  transfers a wafer  100  to the semiconductor manufacturing apparatus  2 A or the semiconductor manufacturing apparatus  2 B. 
     The control unit  40  obtains substrate shape data, and determines, based on the substrate shape data, which one of the semiconductor manufacturing apparatus  2 A and the semiconductor manufacturing apparatus  2 B to transfer the wafer  100  to. For example, if the difference between the highest position and the lowest position in the substrate shape data is smaller than a predetermined threshold value, the control unit  40  treats the wafer  100  as being not deformed, and sends an instruction to the wafer transfer section  30  to transfer the wafer  100  to the semiconductor manufacturing apparatus  2 A. On the other hand, if the difference between the highest position and the lowest position in the substrate shape data is equal to or larger than the predetermined threshold value, the control unit  40  treats the wafer  100  as being deformed in a saddle shape, and sends an instruction to the wafer transfer section  30  to transfer the wafer  100  to the semiconductor manufacturing apparatus  2 B. 
     The wafer  100  is placed in the semiconductor manufacturing apparatus  2 B in the same manner as explained in the second embodiment, and so its detailed description will be omitted. 
     The example described above is provided with the semiconductor manufacturing apparatus  2 A configured to hold a wafer  100  considered as being not deformed, and the semiconductor manufacturing apparatus  2 B configured to hold a wafer  100  considered as being deformed in a saddle shape. However, this does not limit the embodiment. For example, three or more semiconductor manufacturing apparatuses may be provided. In this case, they are composed of one semiconductor manufacturing apparatus configured to hold a wafer  100  considered as being not deformed, and two semiconductor manufacturing apparatuses configured to hold a wafer  100  considered as being deformed in a saddle shape. In this case, the semiconductor manufacturing apparatuses configured to hold a wafer  100  considered as being deformed in a saddle shape are further categorized, in terms of the difference between the highest position and the lowest position in the substrate shape data, into two types, one of which is to handle a wafer having a difference of 100 μm or less and the other is to handle a wafer having a difference of larger than 100 μm. 
     According to the third embodiment, the semiconductor manufacturing apparatus configured to hold a wafer  100  considered as being not deformed, and the semiconductor manufacturing apparatus configured to hold a wafer  100  considered as being deformed in a saddle shape are provided, along with the control unit  40  configured to determine, based on the substrate shape data, which one of the semiconductor manufacturing apparatuses to transfer the wafer  100  to. Consequently, there is provided an effect capable of switching the substrate holding devices, in accordance with the degree of deformation of the wafer  100  to be processed. 
     The substrate holding device described above may be used as a substrate stage in various types of semiconductor manufacturing apparatuses, such as a light exposure apparatus, etching apparatus, and film formation apparatus. 
     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 embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments 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.