Patent Publication Number: US-7709932-B2

Title: Semiconductor wafer having a separation portion on a peripheral area

Description:
RELATED APPLICATIONS 
     This application is a divisional of application Ser. No. 10/751,657, filed Jan. 6, 2004, now U.S. Pat. No 7,195,988 which claims priority of Japanese Application No. 2003-189574, filed Jul. 1, 2003, the contents of which are hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a semiconductor wafer which has a support plate adhered to one or front surface thereof in the form of a flat surface with a semiconductor circuit formed thereon, and of which the other or rear surface is partially removed to reduce its thickness, and it also relates to a semiconductor device manufactured by using the semiconductor wafer as well as to a method of manufacturing semiconductor devices. 
     2. Description of the Related Art 
     In the past, there has been known a method for manufacturing semiconductor devices in which a support plate for reinforcing the mechanical strength of a semiconductor wafer is first attached or adhered to a flat front surface of the semiconductor wafer having a semiconductor circuit formed thereof, and then an opposite rear surface of the semiconductor wafer is partially removed to reduce its thickness, thereby providing the semiconductor devices. Such a method of manufacturing semiconductor devices is disclosed in Japanese patent application laid-open No. H10-335195, for example. 
     In this case, however, it is necessary to grind the rear surface of the semiconductor wafer to reduce the initial thickness thereof to about 1/10 thereof, and hence there arises the following problem. 
     That is, in general, semiconductor wafers having cleavage are highly brittle and are single crystal, so they are rapidly becoming easier to crack in accordance with the decreasing thickness thereof. Thus, it is extremely difficult to convey or transport the semiconductor wafers after they have been ground to a certain thickness or less. Therefore, each semiconductor wafer is attached or adhered to a support plate of a prescribed rigidity before grinding thereof. In this case, however, support plates adhered to semiconductor wafers, respectively, are made to have the same diameter as that of the semiconductor wafers adhered thereto due to the necessity of using in common the wafer conveyance or transportation system of processing equipment before and after the grinding of the rear surface of each semiconductor wafer. If, however, for instance, both of a semiconductor wafer and a support plate have a maximum amount of tolerance, the overall outside diameter of the semiconductor wafer and the support plate after adhered to each other will be increased by a positioning or registering error therebetween which would be generated upon adhering the support plate to the semiconductor wafer, so that it might become larger than an allowed entire outside diameter, thus resulting in difficulty in the handling thereof by a conveyance or transportation system of post-processing equipment. To avoid such a situation, there arises the following problem. That is, for instance, it is necessary to prepare jigs, attachments, etc., suited to fit the combined wafer and support plate into respective processing apparatuses, and in addition, it is also necessary to use or replace such jigs and attachments in individual cases, thus reducing the manufacturing efficiency. 
     Moreover, when the semiconductor wafer actually protrudes from the corresponding support plate, the protruded portion of the wafer is very easy to crack and would be causes of resultant defects and/or contamination, and hence the protruding of the semiconductor wafer from the support plate is not allowed in fact. As a result, extremely high accuracies are required in terms of the individual dimensions of the semiconductor wafer and the support plate as well as the total size or adhering positions thereof when they are adhered to each other. 
     SUMMARY OF THE INVENTION 
     The present invention is intended to obviate the above-mentioned problems, and has for its object to provide a semiconductor wafer in which a transportation system for the semiconductor wafer can be commonly used without any change before and after a support plate is adhered to the semiconductor wafer, and in which the finish accuracy of the semiconductor wafer and the positioning or registering accuracy of the semiconductor wafer and the support plate can be relaxed, thus making it possible to improve the efficiency of manufacturing semiconductor devices. 
     Another object of the present invention is to provide a semiconductor device which can be manufactured by using such a semiconductor wafer. 
     A further object of the present invention is to provide a method of manufacturing such a semiconductor device. 
     According to the present invention, there is provided a semiconductor wafer having a front surface which is a flat surface with a semiconductor circuit formed thereon and to which a support plate is adhered, and a rear surface of which is partially removed to reduce its thickness. On a peripheral portion of the semiconductor wafer, there is formed a separation portion which has a notch deeper than a finished thickness of the semiconductor wafer obtained by the partial removal of the rear surface thereof. The separation portion has a length which extends radially outward from the flat surface, and which is greater than a total sum of a maximum-minimum difference between the finish allowances of the diameters of the semiconductor wafer and the support plate, which has substantially the same diameter as that of the semiconductor wafer, and a maximum value of a positioning error between the semiconductor wafer and the support plate generated at the time of adhering them to each other. 
     The above and other objects, features and advantages of the present invention will become more readily apparent to those skilled in the art from the following detailed description of preferred embodiments of the present invention taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partial cross sectional view of a semiconductor wafer according to a first embodiment of the present invention. 
         FIGS. 2(I) through 2(V)  are views showing respective process steps of manufacturing semiconductor devices according to the first embodiment of the present invention. 
       FIGS.  3 (I) through  3 (VI) are views showing further respective process steps of manufacturing the semiconductor devices according to the first embodiment of the present invention. 
         FIG. 4  is a partial cross sectional view showing another example of a semiconductor wafer according to the first embodiment of the present invention. 
         FIG. 5  is a partial cross sectional view showing a further example of a semiconductor wafer according to the first embodiment of the present invention. 
         FIG. 6  is a partial cross sectional view showing a still further example of a semiconductor wafer according to the first embodiment of the present invention. 
         FIG. 7  is a partial cross sectional view showing a yet further example of a semiconductor wafer according to the first embodiment of the present invention. 
       FIGS.  8 (I) through  8 (IV) are views showing respective process steps of manufacturing semiconductor devices according to a second embodiment of the present invention. 
       FIGS.  9 (I) through  9 (VI) are views showing respective process steps of manufacturing semiconductor devices according to a third embodiment of the present invention. 
       FIGS.  10 (I) through  10 (VIII) are views showing respective process steps of manufacturing semiconductor devices according to a fourth embodiment of the present invention. 
         FIG. 11A  is a plan view of a semiconductor wafer of a different configuration. 
         FIG. 11B  is a plan view of a base after the semiconductor wafer of  FIG. 11A  is partially removed by grinding. 
         FIG. 12A  is a plan view of a semiconductor wafer of a further different configuration. 
         FIG. 12B  is a plan view of a base after the semiconductor wafer of  FIG. 12A  is partially removed by grinding. 
         FIG. 13A  is a plan view of a semiconductor wafer of a still further different configuration. 
         FIG. 13B  is a plan view of a base after the semiconductor wafer of  FIG. 13A  is partially removed by grinding. 
         FIG. 14A  is a plan view of a semiconductor wafer of a yet further different configuration. 
         FIG. 14B  is a plan view of a base after the semiconductor wafer of  FIG. 14A  is partially removed by grinding. 
         FIG. 15A  is a cross sectional view showing one process step of manufacturing semiconductor devices by using the semiconductor wafer shown in  FIG. 11A . 
         FIG. 15B  is a cross sectional view showing a process step following the one of  FIG. 15A . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Now, preferred embodiments of the present invention will be described in detail while referring to the accompanying drawings, with the same or corresponding parts or members thereof being identified by the same symbols throughout the following respective embodiments. 
     Embodiment 1 
       FIG. 1  is a partial cross sectional side view of a semiconductor wafer according to a first embodiment of the present invention.  FIGS. 2(I) through 2(V)  show respective process steps of a method of manufacturing semiconductor devices according to the first embodiment of the present invention. FIGS.  3 (I) through  3 (VI) shows respective process steps, subsequent to the process step of  FIG. 2(V) , of the method of manufacturing the semiconductor devices according to the first embodiment of the present invention. 
     The semiconductor wafer, generally designated at reference numeral  1 , has one or front surface in the form of a flat surface  1   a  on which a semiconductor circuit  2  is formed, and to which a support plate  3  is attached or adhered, and the other or rear surface of which is ground to reduce its thickness. The semiconductor wafer  1  has a disk-shaped configuration, and is formed on the peripheral portion of the front surface thereof with a separation portion in the form of a stepped portion  4 . The stepped portion  4  includes a notch having a vertical plane  4   b  vertically cut from the front surface of the wafer  1  and a bottom surface  4   a  horizontally cut into the vertical plane  4   b . The bottom surface  4   a  of the stepped portion  4  has a rear surface that is deeper than the thickness of a base  5  after partially removed by grinding, and the width of the bottom surface  4   a  is larger than a total sum of a maximum-minimum difference between the finish allowances of the diameters of the semiconductor wafer  1  and the support plate  3 , which has substantially the same diameter as that of the semiconductor wafer  1 , and a maximum value of a positioning or registering error between the semiconductor wafer  1  and the support plate  3  generated at the time of adhering them to each other. 
     A plurality of semiconductor devices  12  are produced from the above-mentioned semiconductor wafer  1  through respective manufacturing process steps, which will be described in detail below. 
     First of all, the peripheral portion of the front surface of a disk-shaped wafer main body is subjected to a step forming process to provide the stepped portion  4 , thus forming the semiconductor wafer  1  ( FIG. 2(I) ). Then, the semiconductor circuit  2  is formed on the flat surface  1   a  of the front surface of the semiconductor wafer  1  (FIG.  2 (II)). Thereafter, the support plate  3  having substantially the same diameter as that of the semiconductor wafer  1  is adhered or bonded to the front surface of the semiconductor wafer  1  having the stepped portion  4  by the use of an adhesive or binding material  7  (FIG.  2 (III)). At this time, there might be caused an adhesion error A between the semiconductor wafer  1  and the support plate  3 , as shown in this figure. Thereafter, the rear surface of the semiconductor wafer  1  is partially ground to remove the separation portion in the form of the stepped portion  4  until the thickness of the semiconductor wafer  1  is reduced to a finished thickness of about 1/10 of the initial thickness thereof, so that the base  5  is thereby formed (FIG.  2 (IV)). Subsequently, an insulating film  8  is formed on the rear surface of the base  5  to provide a semiconductor device body  6  ( FIG. 2(V) ). As a result, a block  11  is formed in which the semiconductor device body  6  is fixedly secured to the support plate  3  by means of the binding material  7 . 
     Continuously to this, the rear surface of the block  11  is adhered to a support film  10  that is arranged under tension on a lower surface of a ring-shaped frame  9  ( FIG. 3(I) ). Thereafter, ultraviolet rays are irradiated from a front surface side of the block  11  whereby the adhesive strength of the binding material  7  is lost, allowing the support plate  3  to be separated from the semiconductor device body  6  (FIGS.  3 (II) and  3 (III)). Then, the semiconductor device body  6  is divided by dicing to form a plurality of discrete semiconductor devices  12  (FIG.  3 (IV)). Finally, by irradiating ultraviolet rays on the support film  10  from the rear surface thereof, the adhesive strength of an adhesive layer on the surface of the support film  10  is lost so that the semiconductor devices  12  are peeled off from the support film  10 , thus completing the production of the semiconductor devices  12  (FIGS.  3 (V) and  3 (VI)). 
     In the semiconductor devices  12  of the above-mentioned construction, before performing a process of forming the semiconductor circuit  2 , the stepped portion  4  having the notch is formed on the peripheral portion of the semiconductor wafer  1  in such a manner that the notch is deeper than the finished thickness of the semiconductor wafer  1  and wider than the total sum of the maximum-minimum difference between the finish allowances of the diameters of the semiconductor wafer  1  and the support plate  3 , which has substantially the same diameter as that of the semiconductor wafer  1 , and the maximum value of the positioning or registering error between the semiconductor wafer  1  and the support plate  3  generated at the time of adhering them to each other. Then, the semiconductor wafer  1  is ground after it is adhered to the support plate  3 . As a result, the stepped portion  4  is eliminated or removed by the grinding process to form the base  5 , the outer diameter of which is less by the radial length of the notch of the stepped portion  4  than the outer diameter of the semiconductor wafer  1 . At this time, the width of the stepped portion  4  is set to be an appropriate value by taking into consideration of both of the errors including the finish allowances of the semiconductor wafer  1  and the support plate  3  and the positioning or registering error therebetween. Therefore, the base  5 , after the rear surface of the semiconductor wafer  1  has been ground, does not protrude outward from the outer periphery of the support plate  3 . 
     Accordingly, the conveyance or transportation system for the semiconductor wafer  1 , which has substantially the same diameter as that of the support plate  3  and which is formed on the front surface thereof with the semiconductor circuit  2 , can be used as it is, even in the respective process steps following the process step of forming the base  5  (FIG.  2 (IV)). 
     In addition, the diameter of the block  11 , after the rear surface of the semiconductor wafer  1  has been ground, is substantially the same as that of the support plate  3 , and hence the dimensional accuracy of the diameter of the block  11  is decided by the dimensional accuracy of the diameter of the support plate  3 . As a consequence, the finish accuracy of the semiconductor wafer  1  and the positioning or registering accuracy between the semiconductor wafer  1  and the support plate  3  are relaxed or mitigated. 
     Moreover, the size of the base  5  is smaller than the size of the support plate  3  in the process steps after the process step of FIG.  2 (IV). Thus, by utilizing such a difference between these sizes, the support plate  3 , when separated from the base  5 , can be peeled off in a direction away from the support film  10  to which the base  5  is adhered, initially at a portion of the support plate  3  not overlapping with the base  5 . As a result, workability in separating the support plate  3  from the base  5  can be improved in comparison with the case where a block comprising a base and a support plate, whose diameters are substantially the same with each other, is adhered to the support film  10 . 
     Although in the above description, the separation portion of the above-mentioned semiconductor wafer  1  comprises the stepped portion  4  having the vertical plane  4   b  perpendicular to the bottom surface  4   a , it may comprise a stepped portion  4 A having a slope or inclined surface  4   c  formed at an angle with respect to a bottom surface  4   a , as shown in  FIG. 4 . Further, the separation portion may comprise a stepped portion  4 B having a chamfer  4 d formed at a location at which a vertical plane  4   b  and a flat surface  1   a  cross each other, as shown in  FIG. 5 . 
     Furthermore, the semiconductor wafer  1  may have a thin wall portion  4 C with its thickness gradually decreasing from the flat surface  1   a  toward the peripheral portion thereof, as shown in  FIG. 6 . In this case, by grinding the rear surface of the semiconductor wafer  1  fixedly attached to the support plate  3  to a prescribed thickness B, the thin wall portion  4 C, which constitutes a separation portion having a notch, can be removed, and the diameter of the block  11  is decided by the diameter of the support plate  3  alone, as in the above-mentioned block  11 , thereby providing the same operational effects as those obtained by the semiconductor wafer  1  previously described. 
     Still further, as shown in  FIG. 7 , the separation portion may comprise a stepped portion  4 D which has an annular groove  4 e formed at an innermost diameter portion of the bottom surface  4   a , and a chamfer  4   d  formed at a location at which a vertical plane  4   b  and a flat surface  1   a  cross each other. 
     Embodiment 2 
     FIGS.  8 (I) through  8 (IV) show those process steps of a method of manufacturing semiconductor devices according to a second embodiment of the present invention which are different from the ones in the above-mentioned first embodiment. 
     Although in the first embodiment, reducing the thickness of the peripheral portion of the semiconductor wafer  1  is carried out in advance before the semiconductor circuit  2  is formed on the flat surface  1   a , it is necessary, according to this second embodiment, to decide the finished thickness of the semiconductor wafer  1  and the positioning or registering accuracy between the semiconductor wafer  1  and the support plate  3  before they are adhered to each other. 
     In actuality, there are many cases that the finished thickness of the semiconductor wafer  1  as required varies according to the kind and usage thereof. Accordingly, in cases where the manufacturing method as described in the first embodiment is adopted, it is necessary to prepare beforehand a variety of semiconductor wafers  1  with the processed configurations of their peripheral portions being changed in accordance with the kinds and uses thereof. 
     In contrast to this, according to this second embodiment, after the semiconductor circuit  2  has been formed on the flat surface  1   a  of the disk-shaped wafer main body  50 , the stepped portion  4  of a prescribed depth is formed on the peripheral portion of the wafer main body  50  by a step forming process according to the usage-of the semiconductor circuit  2  (FIGS.  8 (I) through  8 (III)). Therefore, in cases where the finished thickness of the semiconductor wafer as required varies according to the kind and usage thereof, the operational effects similar to those obtained in the first embodiment can be achieved even if the stepped portion  4  of a specific size has not been prepared beforehand. Here, note that the respective process steps in this second embodiment after the manufacturing process step of FIG.  8 (IV) are similar to the respective manufacturing process steps in the first embodiment shown in FIG.  2 (IV) and in  FIGS. 3(I) through 3(V) , and hence an explanation thereof is omitted. 
     Embodiment 3 
     FIGS.  9 (I) through  9 (IV) show those process steps of a method of manufacturing semiconductor devices according to a third embodiment of the present invention which are different from the ones in the above-mentioned first embodiment. 
     Although in the above-mentioned second embodiment, the separation portion in the form of the stepped portion  4 -is formed in the process step of FIG.  8 ( 111 ), this third embodiment is different from the second embodiment in that an annular groove  26 , being deeper than the thickness of the base  5  formed by grinding the rear surface of the semiconductor wafer  1 , is formed, instead of the stepped portion  4 , at a prescribed position of the peripheral portion of the semiconductor wafer  1  to provide a separation portion together with its outer periphery, as shown in FIG.  9 (III). 
     In this example, after the support plate  3  is adhered to the semiconductor wafer  1  (FIG.  9 (IV)), the rear surface of the semiconductor wafer  1  is ground (FIG.  9 (V)), whereby the outer peripheral portion of the semiconductor wafer  1  outside the groove  26  is simultaneously separated to form the base  5  (FIG.  9 (VI)). The subsequent manufacturing process steps of this third embodiment are similar to the respective process steps shown in FIG.  2 (IV) and in FIGS.  3 (I) through  3 (VI), and the operational effects of this embodiment are also similar to those obtained by the above-mentioned second embodiment. 
     Embodiment 4 
     FIGS.  10 (I) through  10 (VIII) show those process steps of a method of manufacturing semiconductor devices according to a fourth embodiment of the present invention. 
     Although the semiconductor devices  30  have penetration electrodes  23  electrically connected with semiconductor circuits  2  formed on their front surfaces, these semiconductor devices  30  are produced from a wafer main body  50  through respective manufacturing process steps. Hereinafter, the respective manufacturing process steps will be explained in detail. 
     First of all, a semiconductor circuit  2  is formed on a flat surface  1   a  of the disk-shaped wafer main body  50  ( FIG. 10(I) ). Then, a plurality of holes  20  extending from the semiconductor circuit  2  to the wafer main body  50  are formed by means of etching, and at the same time a separation portion in the form of an annular stepped portion  4  is formed on the peripheral portion of the wafer main body  50  to provide a semiconductor wafer  1  (FIG.  10 (II)). Thereafter, an electrically conductive material in the form of a metal is filled into the holes  20  to form electrode portions  21  (FIG.  10 (III)). Then, a support plate  3  having substantially the same diameter as that of the semiconductor wafer  1  is adhered to a front surface of the semiconductor wafer  1  having the separation portion with a notch in the form of the stepped portion  4  by the use of an adhesive or binding material  7  (FIG.  10 (IV)). After that, the rear surface of the semiconductor wafer  1  is partially ground to remove the stepped portion  4  until the thickness of the semiconductor wafer  1  is reduced to a finished thickness of about 1/10 of the initial thickness thereof, so that a base  5  is thereby formed. In this connection, note that the depth of the stepped portion  4  is the same as the depth of the holes  20 , so one end faces of the electrode portions  21  are exposed outward from the base  5  at the same time with the removal of the stepped portion  4  ( FIG. 10(V) ). Subsequently, the rear surface of the base  5  is etched to protrude the electrode portions  21  therefrom (FIG.  10 (VI)), after which a process of forming an insulating film  24  on the rear surface of the base  5  is carried out, and then a metal is attached to the one end faces of the electrode portions  21  to form the penetration electrodes  23 , whereby a block  31  having semiconductor devices  30  are formed (FIGS.  10 (VII) and  10 (VIII)). 
     Thereafter, the semiconductor devices  30  are separated from the block  31  by ultraviolet radiation, as in the above-mentioned first through third embodiments. 
     In the semiconductor devices  30  having the penetration electrodes  23 , the annular stepped portion  4  is formed on the peripheral portion of the wafer main body  50  at the same time when the holes  20  are formed through the wafer main body  50  by means of the etching process, as a result of which there is no necessity of particularly or independently providing a process step of forming the stepped portion  4 . In addition, the conveyance or transportation system for the semiconductor wafer  1  having the semiconductor circuit  2  formed on the front surface thereof can be used as it is, even in the respective process steps following the process step of forming the base  5  ( FIG. 10(V) ). 
     Moreover, the diameter of the block  31 , after the rear surface of the semiconductor wafer  1  has been ground to protrude the penetration electrodes  23  therefrom, becomes the diameter of the support plate  3 . Therefore, the dimensional accuracy of the diameter of the block  31  is decided by the dimensional accuracy of the diameter of the support plate  3 , and hence the accuracy of the semiconductor wafer  1  and the positioning or registering accuracy between the semiconductor wafer  1  and the support plate  3  are relaxed or mitigated. 
     Furthermore, since the depth of the notch or the stepped portion  4  is the same as the depth of the holes  20  in the wafer main body  50 , the one end faces of the electrode portions  21  can be exposed from the wafer main body  50  at the same time with the grinding of the stepped portion  4 , whereby the removal of the stepped portion  4  and the exposure of the one end faces of the electrode portions  21  can be carried out by one and the same process step, thus making it possible to improve the manufacturing efficiency. 
     Embodiment 5 
     Although in the above-mentioned respective embodiments, the semiconductor wafer  1  of a disk-shaped configuration has been described, the present invention is also applicable to a semiconductor wafer  1  with a base  5 , which takes a doughnut-shaped configuration after the rear surface of the semiconductor wafer  1  has been removed by grinding, as shown in  FIGS. 11A and 11B  and in  FIGS. 12A and 12B . In addition, the present invention is further applicable to another semiconductor wafer  1 , too, even if the configuration of the base  5  of the semiconductor wafer  1 , after the rear surface thereof has been partially removed by grinding, is substantially quadrangular, as shown in  FIGS. 13A and 13B  and  FIGS. 14A and 14B . 
     For instance, when semiconductor devices  12  are manufactured by the use of the semiconductor wafer  1  as shown in  FIG. 11A , a semiconductor circuit  2  is formed, in the course of manufacture, on a flat surface  1   a  of one or front surface of the semiconductor wafer  1  that has a separation portion in the form of a stepped portion  4  formed by subjecting the peripheral portion of a disk-shaped wafer main body at its front surface side to a step forming process. Thereafter, a support plate  3  having substantially the same diameter as that of the semiconductor wafer  1  is adhered to the front surface of the semiconductor wafer  1  by using a binding material  7  ( FIG. 15A ). Subsequently, the rear surface of the semiconductor wafer  1  is partially ground to remove the separation portion in the form of the stepped portion  4  until the thickness of the semiconductor wafer  1  is reduced to a prescribed finished thickness, thereby forming a base  5  ( FIG. 15B ). The following process steps are similar to the ones explained in the first embodiment. 
     As can be seen from the foregoing description, the present invention provides the following excellent advantages. 
     According to one aspect of the present invention, there is provided a semiconductor wafer having a front surface which is a flat surface with a semiconductor circuit formed thereon and to which a support plate is adhered, and a rear surface of which is partially removed to reduce its thickness. On a peripheral portion of the semiconductor wafer, there is formed a separation portion which has a notch deeper than a finished thickness of the semiconductor wafer obtained by the partial removal of the rear surface thereof. The separation portion has a length which extends radially outward from the flat surface, and which is greater than a total sum of a maximum-minimum difference between the finish allowances of the diameters of the semiconductor wafer and the support plate, which has substantially the same diameter as that of the semiconductor wafer, and a maximum value of a positioning error between the semiconductor wafer and the support plate generated at the time of adhering them to each other. With this construction, even after the semiconductor wafer and the support plate have been adhered to each other, it is possible to use a conveyance system as before without changing it in any way, and at the same time to relax the finish accuracy of the semiconductor wafer as well as the positioning or registering accuracy between the semiconductor wafer and the support plate. As a result, the efficiency of manufacturing semiconductor devices can be improved. 
     According to another aspect of the present invention, there is provided a semiconductor device formed by dividing a semiconductor device body into a plurality of semiconductor devices, the semiconductor device body comprising: a base formed by partially removing the rear surface of the above-mentioned semiconductor wafer thereby to eliminate the separation portion of the semiconductor wafer; and a semiconductor circuit formed on one surface of the base. The semiconductor device of this construction can improve the manufacturing efficiency thereof. 
     According to a further aspect of the present invention, there is provided a method of manufacturing semiconductor devices, the method comprising the steps of: forming the separation portion of the above-mentioned semiconductor wafer on a peripheral portion of a wafer main body at a front surface side thereof to provide the semiconductor wafer; forming a semiconductor circuit on the flat surface of the front surface of the semiconductor wafer; adhering a support plate of substantially the same diameter as that of the semiconductor wafer to the front surface of the semiconductor wafer by means of a binding material; partially removing the rear surface of the semiconductor wafer to eliminate the separation portion thereby to form a base; and processing a rear surface of the base. With this method, even after the semiconductor wafer and the support plate have been adhered to each other, a conveyance system can be used as before without any change, and the finish accuracy of the semiconductor wafer and the positioning or registering accuracy between the semiconductor wafer and the support plate can be relaxed. Accordingly, the efficiency of manufacturing semiconductor devices can be improved. In addition, since the size of the base is smaller than that of the support plate, separation workability in separating the support plate from the base can be improved. 
     According to a further aspect of the present invention, there is provided a method of manufacturing semiconductor devices, the method comprising: forming a semiconductor circuit on a flat surface of a front surface of a wafer main body; forming the separation portion of the above-mentioned semiconductor wafer on a peripheral portion of the wafer main body at a front surface side thereof to provide the semiconductor wafer; adhering a support plate of substantially the same diameter as that of the semiconductor wafer to the front surface of the semiconductor wafer by means of a binding material; partially removing the rear surface of the semiconductor wafer to eliminate the separation portion thereby to provide a base; and processing a rear surface of the base. With this method, even after the adhesion of the semiconductor wafer and the support plate to each other, a conveyance system can be used as before without any change, and the finish accuracy of the semiconductor wafer and the positioning or registering accuracy between the semiconductor wafer and the support plate can be relaxed, as a result of which the efficiency of manufacturing semiconductor devices can be improved. 
     In addition, since the size of the base is smaller than that of the support plate, separation workability in separating the support plate from the base can be improved. 
     Further, in cases where the finished thickness of the semiconductor wafer as required varies according to the kind and usage thereof, it is not necessary to prepare any separation portion of a specific size beforehand. 
     According to a still further aspect of the present invention, there is provided a method of manufacturing semiconductor devices, the method comprising the steps of: forming a semiconductor circuit on a flat surface of a front surface of a wafer main body; forming a plurality of holes that extend from the semiconductor circuit to the wafer main body; forming the separation portion of the above-mentioned semiconductor wafer on a peripheral portion of the wafer main body to provide the semiconductor wafer; filling a conductive material into the holes to form electrode portions; adhering a support plate of substantially the same diameter as that of the semiconductor wafer to the front surface of the semiconductor wafer by means of a binding material; partially removing the rear surface of the semiconductor wafer to eliminate the separation portion thereby to form a base and to expose one end faces of the electrode portions; partially removing a rear surface of the base to protrude the electrode portions therefrom; forming an insulating film on the rear surface of the base; and processing the one end faces of the electrode portions to form penetration electrodes. With this method, even after the adhesion of the semiconductor wafer and the support plate to each other, it is possible to use a conveyance system as before without any change thereof, and at the same time to relax the finish accuracy of the semiconductor wafer as well as the positioning or registering accuracy between the semiconductor wafer and the support plate, as a consequence of which the efficiency of manufacturing semiconductor devices can be improved. 
     While the invention has been described in terms of preferred embodiments, those skilled in the art will recognize that the invention can be practiced with modifications within the spirit and scope of the appended claims.