Abstract:
Provided is a semiconductor manufacturing system. The semiconductor manufacturing system includes a wafer loading boat, a complementary wafer loading boat, a door assembly, and a spacing controlling system. The wafer loading boat is mounted in the reaction tube and includes a plurality of wafer supporters on which the semiconductor wafer is rested on. The complementary wafer loading boat is located inside or outside of the wafer loading boat, moves vertically, includes a wafer holder that is devised to support the semiconductor wafer. The contact between the wafer and the holder in the center part of the wafer other than edges of the wafer is adjusted by moving one of the wafer loading boats vertically. The spacing controlling system is mounted in the door assembly, controls a space between the semiconductor wafer and the wafer holder, and maintains or adjusts a contact area of the semiconductor wafer with the wafer holder dynamically during the thermal processing. Thus, the mechanical deformation including warping, bowing, slip can be completely eliminated by supporting the wafer in the center part of the wafer with controlled contact area, resulting from ideal distribution of the gravitational force of the wafer. Also the reliability, uniformity and reproducibility of the thermal processing steps can be significantly enhanced due to the ability to control the gap between the wafer and the holder, and to control the contact area between the wafer and the holder dynamically even during the process at high temperatures, which has been never possible in the previous arts. In addition, it is possible to perform the thermal process without any mechanical damages to the semiconductor wafer having a diameter of 300 mm (12 inches) or greater.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This application claims the priority of Korean Patent Application No. 2002-75643, filed on Nov. 30, 2002, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.  
           [0002]    1. Field of the Invention  
           [0003]    The present invention relates to a semiconductor manufacturing system, and more particularly, to a semiconductor manufacturing system having a wafer loading boat by which a plurality of semiconductor wafers can be processed at a time.  
           [0004]    2. Description of the Related Art  
           [0005]    In general, a semiconductor manufacturing system in which a plurality of semiconductor wafers can be processed includes a wafer loading boat for loading the semiconductor wafers. The wafer loading boat comprises a plurality of supporting pillars which are arranged to form an accommodating space in a shape of a cylinder inside the wafer loading boat, an upper supporting board and a lower supporting board on which both ends of the supporting pillars are fixed. In the supporting pillars, slots are formed at vertical interval for supporting the semiconductor wafer. Thus, edges of the semiconductor wafer are then at least partially fitted in the slots and can be loaded horizontally. In order to minimize the contact area of the semiconductor wafer with the slots, there have been many attempts such as one where the slots are inclined upwardly at a predetermined angle with the semiconductor wafers. Thus, any defect such as mechanical deformation in a form of warp, bow and slip in the semiconductor wafer is prevented from occurring during the thermal process at high temperatures.  
           [0006]    However, as the diameter of the semiconductor wafer increases above 200 mm (8 inches), the center of the semiconductor wafer is seriously warped or bowed downwardly during the thermal process due to the gravitational force of the wafer at a high temperature more than 900° C. Thus, a degree of such curvature exceeds an elasticity limit, resulting in mechanical deformation of the wafer after completion of the thermal process. Therefore, such warping or bowing causes many problems to a silicon substrate of the semiconductor wafer.  
         SUMMARY OF THE INVENTION  
         [0007]    To solve the above-described and related problems, it is an object of the present invention to provide a semiconductor manufacturing system capable of preventing any mechanical deformation such as warping, bowing, and slip in a semiconductor wafer having a large diameter during a thermal process, thereby preventing any defect in the semiconductor wafer.  
           [0008]    The present invention also provides a reliable semiconductor manufacturing system even if both flatness and surface roughness of a semiconductor wafer are not sufficiently good enough, thereby enhancing reliability of the thermal processing system.  
           [0009]    In an aspect, the present invention provides a semiconductor manufacturing system having a reaction tube capable of performing a thermal process comprising dual boats inside the reaction tube;  
           [0010]    a wafer loading boat, which is mounted in the reaction tube, forms an accommodating space in a shape of a cylinder, and includes a plurality of wafer supporters on which the semiconductor wafer is rested on,  
           [0011]    a complementary wafer loading boat which is located inside or outside of the wafer loading boat within the reaction tube, includes a wafer holder supporter on which the wafer holder is rested on, where the wafer holder is devised to support the semiconductor wafer with at least a part of area in the middle of the wafer holder, where the wafer holder contacts the semiconductor wafer either at room temperature before processing or during high temperature processing, where the contact between the wafer and the holder at high temperatures can be achieved naturally by placing the wafer holder adjacent to the wafer beneath at room temperature when the semiconductor wafer bows within the elastic limit at high processing temperatures, and transfers a weight loaded to the wafer to its lower portion of the wafer holder,  
           [0012]    a door assembly which supports lower portions of the wafer loading boat and the complementary wafer loading boat, moves the wafer loading boat and the complementary wafer loading boat, and closes the reaction tube,  
           [0013]    and a spacing controlling system which is mounted in the door assembly, controls a space between the wafer loading boat and the complementary loading boat, which eventually controls the spacing between the semiconductor wafer and the wafer holder, maintains a contact area of the semiconductor wafer with the wafer holder, and dynamically controls the gap between the wafer and wafer holder during thermal processing.  
           [0014]    Here, the wafer loading boat comprises a plurality of supporting pillars which are arranged in parallel with each other to form an accommodating space in a shape of a cylinder, an upper board and a lower board which respectively fixes the supporting pillars at the same level, and a wafer supporter which is formed in the supporting pillars at a vertical interval and on which the semiconductor wafer is loaded horizontally. Here, one sidewall of the supporting pillars is opened, and the number of the supporting pillars is at least one forming a cylindrical shape. Thus, at least one supporting point can be obtained. A section of the supporting pillars may have a polygonal shape.  
           [0015]    The wafer supporter may be a protrusion protruded at a right angle with respect to the supporting pillars or a slot formed by grooving the supporting pillars.  
           [0016]    The complementary wafer loading boat comprises a plurality of complementary supporting pillars which are arranged at a predetermined interval to form an accommodating space in a shape of a cylinder inside or outside the wafer loading boat, and a wafer holder which is extended from the complementary supporting pillars to support the semiconductor wafer by making contact with at least a part other than both edges of the semiconductor wafer either at room temperature or during thermal processing by adjusting the gap between the wafer and wafer holder dynamically. It is desirable that the number of the complementary supporting pillars is at least one to form a cylindrical space.  
           [0017]    Here, the wafer holder has a shape of a plate on which the semiconductor wafer is rested, and the holder supporter is formed in the complementary supporting pillars to load the wafer holder horizontally at a vertical interval. The wafer holder includes a plurality of opening portions which are extended from the edge of the wafer holder toward a center of the wafer holder at a predetermined length and shape, thus the wafer supporters and pillars in the wafer loading boat can move through the wafer holder freely. Here, the holder supporter may be a slot formed by grooving the complementary supporting pillars or a protrusion type protruded from the complementary supporting pillars toward the accommodating space of the complementary wafer loading boat.  
           [0018]    The spacing controlling system comprises at least one weight sensor which supports at least a lower portion of the wafer loading boat and the complementary wafer loading boat and senses a weight of at least one of the wafer loading boat and the complementary wafer loading boat, a boat lifting driver which is connected to at least either the wafer loading boat or the complemetary wafer loading boat and lifts or moves vertically the loading boat connected to the boat lifting driver, and a space control part which is connected to the weight sensor, compares the sensed weight to a setting point and controls the boat lifting driver.  
           [0019]    It is preferable that the weight sensor be formed by using piezoelectric devices to sense a fine weight.  
           [0020]    It is preferable that the boat lifting driver moves electrically by a method of fine controlling of a motor, or hydraulically by a fluid pressure to guarantee accuracy and flexibility of operations of the boat lifting driver.  
           [0021]    It is preferable that the weight sensor and the boat lifting driver are electrically connected in series in the space control part to control operations of the boat lifting driver by a signal from the weight sensor.  
           [0022]    The semiconductor manufacturing system according to the present invention includes dual boats having a wafer loading boat in which the semiconductor wafer can be loaded and a complemetary wafer loading boat in which the wafer holder can be loaded to support the semiconductor wafer during processing by sensing a change in a weight of the wafer loading boat or complementary wafer loading boat. Thus, it is possible to perform the thermal process without any mechanical deformation of the semiconductor wafer having a large diameter by dynamically controlling the contact area of the semiconductor wafer with the wafer holder.  
           [0023]    In addition, a reaction gas is uniformly distributed to the semiconductor wafer by controlling the contact area. Therefore, uniformity in a semiconductor manufacturing process can be improved. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]    The above object and advantages of the present invention will become more apparent by describing in detail-preferred embodiments thereof with reference to the attached drawings in which:  
         [0025]    [0025]FIG. 1A is a schematic sectional view of a semiconductor manufacturing system according to the present invention;  
         [0026]    [0026]FIG. 1B is a sectional view showing FIG. 1A in more detail according to one embodiment of the present invention;  
         [0027]    [0027]FIG. 2 is an enlarged sectional view of a lower structure of a wafer loading boat and complementary wafer loading boat according to the present invention;  
         [0028]    [0028]FIG. 3A is a sectional view of a wafer loading boat and a complementary wafer loading boat mounted in a semiconductor manufacturing system of the present invention;  
         [0029]    [0029]FIG. 3B is a sectional view showing a combination of a wafer loading boat and a complementary wafer loading boat of FIG. 3A;  
         [0030]    [0030]FIG. 4A is a sectional view showing a semiconductor wafer which is loaded in a wafer loading boat of the present invention;  
         [0031]    [0031]FIG. 4B is a sectional view showing a semiconductor wafer during a thermal process at a high temperature;  
         [0032]    [0032]FIG. 5 is an enlarged sectional view of a door assembly which includes a spacing controlling system mounted in a semiconductor manufacturing system according to one embodiment of the present invention;  
         [0033]    [0033]FIG. 6 is a sectional view of a spacing controlling system mounted in a semiconductor manufacturing system according to another embodiment of the present invention; and  
         [0034]    [0034]FIGS. 7A and 7B are a schematic control flowchart and a block diagram which are applied to a spacing controlling system for controlling a space of a complementary wafer loading boat and a wafer loading boat. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0035]    The present invention will now be described more fully with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully transfer the concept of the invention to those skilled in the art.  
         [0036]    [0036]FIG. 1A is a schematic sectional view of a semiconductor manufacturing system according to the present invention to describe concept of the present invention. FIG. 1B is a sectional view showing FIG. 1A in more detail according to one embodiment of the present invention. FIG. 2 is an enlarged sectional view of a lower structure of a wafer loading boat and a complementary wafer loading boat according to the present invention.  
         [0037]    Referring to FIGS. 1A and 1B, a semiconductor manufacturing system of the present invention includes a reaction tube  30  which provides an accommodating space used for processing semiconductor wafers  100 . A semiconductor wafer loading boat  20 , in which the semiconductor wafers  100  are loaded, and a door assembly  50 , which supports the lower portion of the wafer loading boat  20 , inserts the wafer loading boat  20  in the reaction tube  30  and pulls the wafer loading boat  20  out from the reaction tube  30 , are included in the reaction tube  30 . In addition, a complementary wafer loading boat  10  is included in the reaction tube  30  and has a wafer holder  25  that is capable of supporting the bottom of the semiconductor wafer  100  loaded in the wafer loading boat  20  with contacting at least a part of the bottom of the semiconductor wafer  100 . A spacing controlling system  60  is included in the door assembly  50 . The spacing controlling system  60  supports the lower portions of the wafer loading boat  20  and the complementary wafer loading boat  10 , senses weights of the wafer loading boat  20  and the complementary wafer loading boat  10 , and controls a contact area of the semiconductor wafer  100  with the wafer holder  25  dynamically.  
         [0038]    The reaction tube  30  has an opening portion thereunder. A heating element  35  such as a resistance coil, which is capable of heating the reaction tube  30 , surrounds the reaction tube  30 . Thus, inside of the reaction tube  30  can be heated to a predetermined temperature during the thermal process.  
         [0039]    In the opening portion of the reaction tube  30 , the door assembly  50  is formed to lift or move downwardly the wafer loading boat  20  and to close the opening portion of the reaction tube  30  during the thermal process.  
         [0040]    Referring to FIGS. 1B and 2, the wafer loading boat  20  comprises a plurality of supporting pillars  21  arranged in parallel with each other to form a cylindrical space of which one sidewall is partially opened. Here, a section of the supporting pillars  21  may have a circular shape or a polygonal shape. In the lower and upper portions of the supporting pillars  21 , an upper board  20   a  and a lower board  20   b  are formed to respectively fix the supporting pillars  21  at the same level. The wafer loading boat  20  is fixed in the door assembly  50  through a boat cap  40  whose lower portion has a supporting structure.  
         [0041]    The complementary wafer loading boat  10  may be formed outside or inside the wafer loading boat  20 . Here, the complementary wafer loading boat  10  is outside the wafer loading boat  20 . That is, a plurality of complementary supporting pillars  11  are arranged in parallel with the supporting pillars  21  and forms a cylindrical space of which one sidewall is opened outside the cylindrical space formed by the supporting pillars  21 . In the lower and upper portions of the complementary supporting pillars  11 , a complementary upper board  10 a and an complementary lower board  10   b  are formed to respectively fix the complementary supporting pillars  11  at the same level. Further, the wafer holder  25  is extended to the complementary supporting pillars  11  so that it can support the bottom of the semiconductor wafer  100  loaded in the wafer loading boat  20 .  
         [0042]    [0042]FIGS. 3A and 3B are enlarged sectional views of portion ‘A’ of FIG. 1A for explaining the wafer loading boat  20  and the complementary wafer loading boat  10  in more detail. Here, FIG. 3A is a sectional view of the wafer loading boat  20  and the complementary wafer loading boat  10 , and FIG. 3B is a sectional view showing a combination of the wafer loading boat  20  and the complementary wafer loading boat  10  of FIG. 3A.  
         [0043]    Referring to FIG. 3A, a wafer supporter  21   a  is formed at the supporting pillars  21  at a predetermined vertical interval to support the semiconductor wafer  100  horizontally in both edges of the semiconductor wafer  100 . The wafer supporter  21   a  is formed in a shape of a slot type by grooving the supporting pillars  21  toward the accommodating space so that the semiconductor wafer  100  can be supported horizontally (hereinafter, the wafer supporter  21   a  is also referred to as the slot with the same reference numeral). Thus, a plurality of semiconductor wafers  100  can be loaded by resting the semiconductor wafer  100  on the slot  21   a.    
         [0044]    The complementary wafer loading boat  10  includes a wafer holder as the wafer holder  25  to support at least a part of the bottom of the semiconductor wafer  100  (hereinafter, the wafer holder  25  is also referred to as the wafer holder with the same reference numeral). A holder supporter  11   a  is formed in the complementary supporting pillars  11  to support the wafer holder  25  in edges of the wafer holder  25 . The holder supporter  11   a  may be in a shape of a slot type by grooving the complementary supporting pillars  11  toward the accommodating space of the complementary wafer loading boat  10 . The holder supporter  11   a  may be in a shape of a protrusion type protruded at a right angle with respect to the complementary supporting pillars  11  toward the accommodating space of the complementary wafer loading boat  10 . Here, the wafer holder  25  includes an opening portion (not shown) which is formed to correspond to the supporting pillars  21  so that the wafer loading boat  20  can be vertically lifted at a predetermined height from the complementary wafer loading boat  10 . Here, the opening portion (not shown) is extended from the center of the wafer holder  25  to a circumference of the wafer holder  25 . The opening portion (not shown) may have various shapes.  
         [0045]    Referring to FIG. 3B, the semiconductor wafer  100  is loaded in the wafer loading boat  20 . When the semiconductor wafer  100  is loaded in the wafer loading boat  20  for start of the thermal process, center portions and edges of the semiconductor wafer  100  is rested on the wafer holder  25 , and edges of the semiconductor wafer  100  are supported by the wafer supporter  21   a . Thus, a weight of the semiconductor wafer  100  is distributed to two parts, i.e., the wafer loading boat  20  and the complementary wafer loading boat  10 .  
         [0046]    [0046]FIGS. 4A and 4B are sectional views showing the semiconductor wafers prior to the thermal process and during the thermal process. Here, hatched portions are related to the complementary wafer loading boat  10 , and unhatched portions are related to the wafer loading boat  20 . The weight of the semiconductor wafer  100  is distributed to both the wafer loading boat  20  and the complementary wafer loading boat  10  through the wafer holder  25  and the wafer supporter  21   a.    
         [0047]    Referring to FIG. 4A, when the semiconductor wafer  100  is loaded in the wafer loading boat  20 , the semiconductor wafer  100  holds its equilibrium, and the weight of the semiconductor wafer  100  is distributed to the wafer supporter  21   a  and the wafer holder  25 . That is, the weight loaded to the complementary wafer loading boat  10  includes weights of the complementary wafer loading boat  10 , the wafer holder  25  and the center portions of the semiconductor wafer  100 . The weight loaded to the complementary wafer loading boat  10  includes weights of the wafer loading boat  20  and edges of the semiconductor wafer  100  which are rested on the wafer supporter  21   a.    
         [0048]    Referring to FIG. 4B, if the semiconductor wafer  100  is exposed to a high temperature of about 900° C. through 1350° C. during the thermal process, the semiconductor wafer  100  is expanded, and the center portions of the semiconductor wafer  100  is curved downwardly due to gravity and flowing of its silicon substrate. Thus, a partial weight is applied to the center portions of the wafer holder  25  due to such curvature of the semiconductor wafer  100 . The weight loaded to the complementary wafer loading boat  10  in which the wafer holder  25  is loaded increases, and thus a change increase in the weight loaded in the complementary wafer loading boat  10  occurs. Such change in the weight is sensed by the spacing controlling system  60 , and the spacing controlling system  60  controls the space between the semiconductor wafer  100  and the wafer holder  25  according to the sensed weight. That is, if the change in the weight is sensed, the spacing controlling system  60  moves the wafer holder  25  downwardly or upwardly with respect to the wafer supporter  21   a . Then, an additional weight of the wafer holder  25  is transferred to the wafer supporter  21   a , and then the weight turns to the weight of the semiconductor wafer  100  in its horizontal position. In contrast to this case, if the semiconductor wafer  100  is shrank at a low temperature, thus it turns to its original state, the weight of the complementary wafer loading boat  10  is reduced. Thus, the spacing controlling system  60  lifts the wafer holder  25  such that the weight of the complementary wafer loading boat  10  turns to the weight of the semiconductor wafer  100  in its horizontal position. As mentioned below, the spacing controlling system  60  drives a boat lifting driver dynamically to keep the contact area constant during thermal process.  
         [0049]    [0049]FIG. 5 is an enlarged sectional view of the wafer loading boat  20  and the door assembly  50  for explaining the spacing controlling system  60  mounted in the semiconductor manufacturing system according to the present invention.  
         [0050]    Referring to FIG. 5, the spacing controlling system  60  includes the boat cap  40 , which supports the lower portion of the wafer loading boat  20 , and a first weight sensor  61  which is extended to outside the door assembly  50  through the boat cap  40  to transfer the weight loaded to the wafer loading boat  20  to the lower portion of the wafer loading boat  20 , supports the lower portion of the wafer loading boat  20  and senses a change in the weight loaded to the wafer loading boat  20 . The spacing controlling system  60  also includes a second weight sensor  63  which is extended to outside the door assembly  50  through a structure included in the boat cap  40  to transfer the weight loaded to the complementary wafer loading boat  10  to the lower portion of the complementary wafer loading boat  10 , supports the lower portion of the complementary wafer loading boat  10  and senses a change in the weight of the complementary wafer loading boat  10 . Here, it is desirable that the first weight sensor  61  and the second weight sensor  63  be formed by using piezoelectric devices to control a electrical signal according to the change in the weight loaded in the wafer loading boat  20  or the complementary wafer loading boat  10 . Here, the lower portion of the complementary wafer loading boat  10  is fixed on a surface of the door assembly  50 . In the lower portion of the wafer loading boat  20 , a boat lifting driver  65  is connected to the wafer loading boat  20 , moves vertically the wafer loading boat  20  and controls dynamically the space between the wafer holder  25  and wafer supporter  21  a or the semiconductor wafer  100 . A spacing control part  67  is electrically connected to the first weight sensor  61 , the second weight sensor  63  and the boat lifting driver  65  to receive and computerize a signal sensed by the first and the second weight sensors  61  and  63 , and controls the boat lifting driver  65 . Here, the boat lifting driver  65  is dynamically operated on the basis of a difference between the weights sensed by the first and the second weight sensors  61  and  63 .  
         [0051]    [0051]FIG. 6 is a sectional view of a spacing controlling system mounted in a semiconductor manufacturing system according to another embodiment of the present invention. Here, the first and the second weight sensors  61  and  63  can be inside or outside the door assembly  50 . In this case, the first and the second weight sensors  61  and  63  of the spacing controlling system  60  are inside the door assembly  50 .  
         [0052]    Referring to FIG. 6, the boat lifting driver  65  is connected to the lower portion of the complementary wafer loading boat  10  in contrast to FIG. 5. Thus, the complementary wafer loading boat  10  can move vertically. When the semiconductor wafer  100  is curved downwardly, thus the weight loaded to the complementary wafer loading boat  10  increases, the complementary wafer loading boat  10  is lifted to reduce the weight loaded to the wafer loading boat  20  also.  
         [0053]    [0053]FIGS. 7A and 7B are a control flowchart and a block diagram showing a control of the contact area of the semiconductor wafer  100  with the wafer holder  25  by controlling the space between the wafer holder  25  and the wafer supporter  21   a  or semiconductor wafer  100  of a semiconductor manufacturing system according to the present invention.  
         [0054]    Referring to FIGS. 7A and 7B, after the semiconductor wafer  100  is loaded in the wafer loading boat  20  and is inserted into the reaction tube  30 , a recipe file having a setting point for spacing between the semiconductor wafer  100  and the wafer holder or the wafer holder is loaded and the thermal process starts (step S 1 ). Then, the first and the second weight sensors  61  and  63  start to sense a weight and transfer the weight signal to the space control part  67  (step S 2 ). The sensed weight is compared to the setting point, and the difference between the sensed weight and the setting point are calculated (step S 3 ). If the difference is not within a range of tolerance, the wafer loading boat  20  or the complementary wafer loading boat  10  are lifted or move downwardly at a predetermined height by sending a signal to the boat lifting driver  65  (step S 4 ). Here, the setting point may be presented as an electric setting point such as an electric current and voltage value or a real weight by the unit of gram or kilogram. Further, the setting point may be a weight loaded to the wafer loading boat  20  and the complementary wafer loading boat  10 , or the difference between the weights of the wafer loading boat  20  and the complementary wafer loading boat  10 . In general, the setting point for control is the difference between the weights loaded to the wafer loading boat  20  and the complementary wafer loading boat  10 .  
         [0055]    The thermal process is performed as follows.  
         [0056]    A temperature inside the reaction tube  30  is ramped up by the heating element  35  up to 900° C. to 1350° C. After the semiconductor wafer  100  is exposed to an environment at a high temperature, the semiconductor wafer  100  is expanded, and a silicon substrate of the semiconductor wafer  100  has a flowing characteristic. Then, the semiconductor wafer  100  is curved downwardly by gravity, thus the weight of the semiconductor wafer  100  is concentrated on the wafer holder  25 . The concentrated weight is transferred to the complementary wafer loading boat  10 , and then the second weight sensor  63  transfers an increase in the weight in type of electrical signal to the space control part  67 . The space control part  67  compares the signal indicating the increase in the weight to the setting point and drives the boat lifting driver  65  to move downwardly the wafer holder  25  at a predetermined height. Thus, the space between the wafer holder  25  and the wafer supporter  21   a  increases, and the weight loaded to the wafer holder  25  is distributed to the wafer supporter  21   a . Therefore, the weight sensed by the second weight sensor  63  of the complementary wafer loading boat  10  is reduced. Accordingly, the weight loaded to the wafer holder  25  by the semiconductor wafer  100  and the contact area of the semiconductor wafer  100  with the wafer holder  25  is maintained constantly by repeating dynamically operations described above during the thermal process. When the thermal process is completed, and the temperature is lowered, spacing control operations are performed reversely to the above operations. That is, when the temperature is lowered, the semiconductor wafer  100  is shrunk, and the semiconductor wafer  100 , which is curved at a high temperature, is planarized again. Thus, the weight loaded to the wafer holder  25  is reduced. Then, the first and the second weight sensors  61  and  63  sense the change in the weight, and the space control part  67  controls the boat lifting driver  65  to lift the wafer holder  25 . Thus, the weight has controlled at the setting point.  
         [0057]    As described above, in the semiconductor manufacturing system according to the present invention, the wafer loading boat  20  or the complementary wafer loading boat  10  are lifted up and down dynamically, so that the contact area of the semiconductor wafer  100  with the wafer holder  25  is maintained constantly. Thus, any defect due to curving of the semiconductor wafer  100  can be minimized, and planarity of the semiconductor wafer  100  can be greatly improved.  
         [0058]    In the semiconductor manufacturing system, the complementary wafer loading boat  10  may not be a cylindrical shape and may be formed to support the wafer holder  25  in the semiconductor wafer  100 . That is, two complementary supporting pillars  11  may be arranged in parallel with each other, and the wafer holder  25  may be rested on the complementary supporting pillars  11 . Thus, the change in the weight due to curving of the semiconductor wafer  100  can be sensed to control the space between the semiconductor Wafer  100  and the wafer holder  25 . Then, the complementary supporting pillars  11  and the supporting pillars  21  can be easily arranged, and a structure of the complementary wafer loading boat  10  can be simpler due to a small number of complementary supporting pillars  11 . Here, the wafer holder  25  can be fixed in the complementary supporting pillars  11 .  
         [0059]    In the present invention, the first and the second weight sensors  61  and  63  of the spacing controlling system  60  are included in both the wafer loading boat  20  and the complementary wafer loading boat  10 . However, the first and the second weight sensors  61  and  63  can be either the wafer loading boat  20  or the complementary wafer loading boat  10 . In addition, an electric pendulum valence can be used to sense the change in the weight and control the wafer loading boat  20  and the complementary wafer loading boat  10 . That is, a pendulum structure can be included between the wafer loading boat  20  and the complementary wafer loading boat  10  so as to keep a balance between the weights of the wafer loading boat  20  or the complementary wafer loading boat  10  by controlling them.  
         [0060]    In addition, in the present invention, the space between the semiconductor wafer  100  and the wafer holder  25  is controlled by moving either the wafer loading boat  20  or the complementary wafer loading boat  10 . However, the space can be controlled by moving both the wafer loading boat  20  and the complementary wafer loading boat  10 . For this, the boat lifting driver  65  has to be included in both the wafer loading boat  20  and the complementary wafer loading boat  10 . Thus, fine controlling the space can be easily achieved.  
         [0061]    In addition, the wafer holder  25  is sufficiently supported by the semiconductor wafer  100  in the present invention. However, when the semiconductor wafer  100  is loaded, the wafer holder  25  and the semiconductor wafer  100  can be loaded with being separated from each other at a predetermined distance considering curving at a high temperature.  
         [0062]    As described above, the semiconductor manufacturing system according to the present invention maintains the contact area of the semiconductor wafer with the wafer holder constantly, thereby preventing the semiconductor wafer from being curved during the thermal process at a high temperature.  
         [0063]    In addition, any physical defect in the semiconductor wafer can be reduced by maintaining the contact area of the lower portion of the semiconductor wafer with the wafer holder constantly.  
         [0064]    Further, the space between the semiconductor wafer and the wafer holder can be controlled, so that the semiconductor wafer can be loaded in various manners so as to prevent any defect in the semiconductor wafer according to a process.  
         [0065]    While this invention has been particularly described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and equivalents thereof.