Apparatus for loading and re-slicing semiconductor wafer

Abstract: The present invention provides an apparatus for loading an unprocessed semiconductor wafer doped in advance with impurity diffusion layers on the both sides or not doped, re-slicing the wafer and unloading two sheets of re-sliced wafer as processed wafers upon completion of re-slicing the unprocessed wafer into two sheets to a recovery wafer magazine thus as a total system for operating the aforementioned processes for improving the productivity of cutting processes of the semiconductor wafer production, more particularly provides an improved loading and unloading mechanism arranged between a storage space of both unprocessed and processed wafers and a re­ slicing mechanism, chucking mechanisms and wafer magazines in the storage space. The loading and unloading mechanism comprises a loading manipulator and an unloading manipulator, wherein the loading manipulator receives an unprocessed wafer from the storage space and then conveys and loads the wafer on chucking mechanism which is operated in combination with a re-slicing mechanism, and then the unloading manipulator recovers two sheets of re-sliced wafers from the chucking mechanism and further unload them into another wafer magazine. During the unloading manipulator is unloading the two sheets of re-sliced wafers into the magazine, simultaneously the loading manipulator will take out a new unprocessed wafer, wherein the new wafer is conveyed at a stand-by position and await until the completion of re-slicing an earlier wafer on the chucking mechanism.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for re-slicing a semiconductor wafer, particularly for re-slicing the semiconductor wafer from its periphery edge into two sheets through the center portion of the semiconductor wafer to obtain thinner sheets, and more particularly to an improvement in loading an unprocessed wafer on a re-slicing machine and unloading the processed wafer from the same machine. 2. Description of the Prior Art Japanese Patent Publication No. JP 64-19729 and Japanese Patent Publication No. JP 1-293613 disclose the processes of dividing a semiconductor wafer made of single crystal silicon, for making substrates for discrete components to be used for transistors, diodes or the like. In order to avoid the waste of costly raw material such as the single crystal silicon, a semiconductor wafer is re-sliced into two sheets of substantially equal thickness so that two substrates for the discrete components are simultaneously obtained. U.S. Patent No. 4261781 discloses a process for re-slicing a semiconductor wafer into two sheets. However, this patent is not directed to a process for making a substrate for a discrete component. In general, however, not only the U.S. patent document but also the other patent documents disclosed above, do not set forth an apparatus for a re-slicing process in co-operation with a loading and unloading apparatus. On the other hand, the Applicant of the present invention has disclosed in Japanese Patent Application No. JP 2-10727 corresponding to EP-A-348 783, published on Jan. 16, 1990 a process for re-slicing a semi-conductor wafer and an apparatus for loading an unprocessed wafer on a re-slicing machine and then unloading the processed wafer from the re-slicing machine. Generally, a requirement for such an apparatus for re-slicing semiconductor wafers is to provide the following apparatus since conventional wafers are handled one by one. Such apparatus should include: (a) a loading mechanism to load an unprocessed semiconductor wafer on a re-slicing machine; (b) a slicing mechanism to re-slice the above unprocessed wafer which has been loaded by the above loading mechanism; and (c) an unloading mechanism to unload the processed wafer from the re-slicing machine. Conventionally, since it is time-consuming to load and unload the semiconductor wafer as positioned as described in the above paragraphs (a) and (c) (other than paragraph (b)) by using conventional re-slicing systems, it is necessary to improve the total productivity relating to paragraphs (a) and (c). In other words, it is necessary to speed up the loading and unloading steps of the semiconductor wafer onto and from a slicing machine. However, the above apparatus involves disadvantages since the semiconductor wafer is easily breakable due to the thin shape and breakable properties, and may therefore break upon speeding up of the loading of the semiconductor wafer. SUMMARY OF THE INVENTION An object of the present invention is to provide a re-slicing aparatus capable of improving the total efficiency of the re-slicing process including the loading of semiconductor wafers without any damage from chipping of the semiconductor wafers during the re-slicing process in order to solve the aforementioned disadvantages. It is a more specific object of the present invention to provide an apparatus for slicing semiconductor wafers, which comprises: a slicing mechanism (1) provided with a slicing saw (12) for slicing an unprocessed semiconductor wafer (W) into two processed wafer slices having substantially the same thickness; a chucking mechanism (2) adapted to chuck an unprocessed wafer (W) continuously until the wafer has been sliced by the slicing mechanism (1); a drive mechanism (3,4) adapted to drive the chucking mechanism (2) such that the wafer presents itself to the slicing saw blade edge, subsequently to move the chucking mechanism (2) and the slicing saw (12) relatively together in a direction disposed in the plane of the slicing saw (12) to slice the unprocessed wafer (W) and afterwards to retract the chucking mechanism with processed wafers (W′) upon completetion of the slicing process; a loading and unloading mechanism (5), comprising a loading manipulator (52) and an unloading manipulator (52′), adapted to effect the loading and unloading of said unprocessed and processed wafers between an unprocessed wafer storage means (6), the chucking mechanism (2) and a processed wafer recovery means (7); characterised in that the chucking mechanism (2) comprises two opposed chucks (21,22) for holding the two slices of processed wafer (W′), the clearance between said chucks being adjustable by moving one of said chucks so as to allow the insertion of the loading and unloading mechanism in the intervening space to effect the unloading of the said slices. The loading and unloading mechanism (5) is preferably adapted to transfer the processed wafer (W′) into the processed wafer recovery means (7) and transfer an unprocessed wafer (W) from the unprocessed wafer storage means (6) to a stand-by position during the slicing of a previously-loaded unprocessed wafer (W). Furthermore, the chucking mechanism preferably comprises a pair of vacuum chucks (21,22) and the loading and unloading mechanism (5) comprises a loading manipulator (51c) with a single vacuum cup (53′) located at its free end and an unloading manipulator (51d) with double vacuum cups (53′) located at its free end, arranged so that the chucking mechanism (2) receives an unprocessed semiconductor wafer from said loading manipulator (51c) and then chucks one side of said unprocessed wafer with one of the vacuum chucks (22), and the opposite side with the other vacuum chuck (21), so as to hold both slices of the processed wafer (W′) upon completion of the slicing process until the wafer slices are removed from the chucking mechanism (2) by the unloading manipulator (51d). The pair of vacuum chucks (21,22) may be adapted to maintain a predetermined spacing, thereby to deliver the two wafer slices (W′) simultaneously to the double vacuum cups (53′) of the unloading manipulator (51d) upon insertion thereof into said intervening space. The unprocessed wafer storage means (6) and the processed wafer recovery means (7) are preferably arranged in parallel to each other to form a storage space, said storage means and said recovery means each comprising a wafer magazine and further comprising feeder mechanisms to feed them intermittently along their longitudinal direction, and in that the loading and unloading mechanism is capable of operating vertically in said storage space in cooperation with the said feeder mechanisms. The loading and unloading mechanism (5) may be provided with both a loading means (51c) for said unprocessed wafer and unloading means (51d) for said processed wafer attached to one another to form a combined loading and unloading system. The unprocessed wafer (W) may consist of a processed wafer doped in advance with impurity diffusion layers on both sides and without an impurity diffusion layer in its plane core portion. A loading an unloading mechanism is arranged between the chucking mechanism and a storage space for storing the unprocessed and processed wafer magazines, which are provided to load a sheet of the unprocessed wafer on the chucking mechanism through conveying devices from the storage space of the unprocessed wafers which are contained in a wafer magazine, and to unload the two sheets of processed wafers upon completion of the re-slicing process from the chucking mechanism into another wafer magazine provided in the storage space through the conveying devices. The loading mechanism further is provided to convey the unprocessed wafer in a stand-by position which is the nearest position for the chucking mechanism to await until the completion of re-slicing an ealier wafer on the chucking mechanism. A storage space for storing a pair of wafer magazines comprises an unprocessed wafer magazine to load in advance a plurality of the unprocessed wafers within the magazine, and a processed wafer magazine to unload two sheets of the processed wafers into the processed wafer magazine from an unloading manipulator of the loading and unloading mechanism. The present invention is further advantageous in that the chucking mechanism includes a pair of oppositely arranged vacuum chucks with an adjustable space between them. The loading and unloading mechanism includes a loading manipulator having a single vacuum cup on the end thereof and an unloading manipulator having double vacuum cups on the end thereof, wherein the chucking mechanism will receive an unprocessed semiconductor wafer from the loading manipulator and then hold it by one of the vacuum chucks. The other vacuum chuck will then hold the opposite side of the unprocessed wafer just before the completion of re-slicing of the unprocessed wafer. Furthermore, the pair of vacuum chucks of the chucking mechanism will be able to maintain a predetermined distance from the space between them so as to be able to deliver two sheets of the re-sliced wafers simultaneously into the space between the double vacuum cups of the unloading manipulator. The present invention is also advantageous in that the chucking mechanism comprises a pair of vacuum chucks which are opposed with a space between both vacuum chucks. The space is adjustable between both vacuum chucks, and one chuck is fixed with the longitudinal feeder and the other chuck is detachably movable toward the fixed chuck along an axis. When they are operated, the fixed chuck will hold the inside surface of an unprocessed wafer, firstly, and the other movable chuck will then hold the outside surface of the wafer from the outer position, so as to hold the outside wafer according to the progress of the re-slicing process, whereafter both wafers are held separately by the pair of vacuum chucks with an intervening space for the insertion of the unloader. The present invention is still further advantageous in that the loading and unloading mechanism comprises a storage space comprising both an unprocessed wafer magazine and a processed wafer magazine which are parallel with each other. These wafer magazines further comprise a feeder mechanism to feed the magazines intermittently along their longitudinal direction with a respective predetermined one pitch according to their loading and unloading operation in co-operation with the loading and unloading mechanism, which is capable of operating vertically in the range of the storage space. The present invention is also advantageous in that the loading and unloading mechanism incorporates the loading system of an unprocessed wafer with the unloading system of a processed wafer, wherein they are adjacently placed in a common system. The present invention is still more advantageous in that the unprocessed wafer includes a semiconductor wafer for manufacturing a substrate to be used for discrete components and further comprises a processed wafer doped in advance with impurity diffusion layers on both sides thereof without any impurity diffusion layer in the inside of the plane core portion thereof. Thus, in accordance with the present invention, the total time consumption of the above various processes can be reduced by allowing the re-slicing, loading and unloading processes to proceed simultaneously by the synchronized operation of the loading and unloading mechanism, and further making the chucking mechanism perform the inherent function of holding an unprocessed wafer without any damage, such as chipping off, as well as by making the loading and unloading mechanism stay at a stand-by position which is apart from the re-slicing mechanism for facilitating the secure handling of the unprocessed wafer. It is therefore advantageous in that it can perform the re-slicing process efficiently without any damage of the wafer, whereby it can reduce the production cost of re-slicing the wafer. Further, in accordance with the present invention the apparatus can unload the two sheets of processed wafers easily and securely by making possible the adjustment of the space between the oppositely spaced vacuum chucks, whereby it can further improve the above mentioned effects. Still further, the present invention can simplify the structure of the loading and unloading mechanism, whereby it can minimize the occupation area of installing the system. Finally, the present invention can produce a substrate for descrete components effectively at an optimum production cost. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1(A) is a schematic plan view partially illustrating an example of an apparatus such as a re-slicing mechanism, a chucking mechanism and other operations for re-slicing a semiconductor wafer according to the present invention; FIG. 1(B) is a schematic plan view partially illustrating an example upon completion of re-slicing process; FIGS. 2(A)-2(J), are a series of side views schematically illustrating the movements of the loading and unloading mechanisms; FIGS. 2A1, 2A2, 2B1, 2D1 and 2E1, are a series of plan views schematically illustrating the movement of the re-slicing mechanism, loading and unloading mechanisms; FIGS. 3(A) and 3(B) are schematic section views illustrating the sections of wafer magazines for loading unprocessed and processed wafers respectively; FIG. 4(A) is a front view illustrating a constructional example of a semiconductor wafer to be processed by the re-slicing mechanism of the present invention; FIG. 4(B) is a side view of Fig. 4(A); FIG. 4(C) is a partially enlarged section view of FIG. 4(B); and FIG. 5 is a section view illustrating a constructional example of semiconductor wafer to be processed according to the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now in detail, the preferred embodiment of the present invention is described in the drawings as follows: In FIG. 1 and FIG. 2, a practical example of the present invention is shown as a horizontal-type system which is capable of saving space of the system in both the longitudinal and lateral directions. As shown in FIG. 1(B), the Y-axis illustrates a longitudinal direction and the X-axis illustrates an axis substantially perpendicular thereto. As shown in FIG. 2(C), the Z,Z′ axis illustrates vertical directions and X,X′ illustrates the lateral direction. Directions X and Z are the directions approaching the chucking mechanism and X′ and Z′ are the directions leading from the chucking mechanism. The system comprises a re-slicing mechanism 1; chucking mechanisms 2 which act in cooperation with the re-slicing process, the loading, and unloading processes of unprocessed and processed semiconductor wafers; longitudinal and lateral feeder mechanism 3, 4 which act to feed the chucking mechanism 2 for positioning a work piece held on the chucking mechanism 2, and loading and unloading mechanisms 5 which serve for loading and unloading the work piece. The re-slicing mechanism 1 comprises an ID saw 12, which is known as a doughnut-shaped thin blade bonded with abrasive grains such as diamond grains, a ring shaped tension member 13, which tension the ID blade mechanically, and tension head 11, which is rotated at high speed through a shaft driven by a motor. It is preferred that the blade surface of IF saw 12 be vertical so as to re-slice an unprocessed semiconductor wafer into two sheets through substantially the center portion of the core thickness as shown in Fig. 1(A). Chucking mechanism 2 comprises a pair of vacuum chucks, such as the inside chuck 22 and the outside chuck 21, which are opposed separately with a clearance between both vacuum chucks. The clearance is adjustable by an L-shaped rod 23 fixed with the outside chuck 21 and driven by a clearance adjusting drive source 24, such as an air cylinder, servomotor or the like. Vacuum chucks 22, 21 are formed of an air permeable porous construction material and sealingly communicate with a vacuum pump (not shown in the drawings) so as to cause a strong vacuum action over all the surface of vacuum chucks 22, 21 to attract a semiconductor wafer with the vacuum surface of the inside chuck 22 or the surface of the outside chuck 21. Chucking mechanisms 2 further provide an element 25 through a longitudinal feeder mechanism 3 to feed the chucking mechanism 2 itself toward the re-slicing mechanism 1 together with the held semiconductor wafer. With respect to the operation of the vacuum chucks 22, 21 of the chucking mechanism 2, the vacuum chucks 22, 21 are operated to load an unprocessed wafer and then unload the processed wafer after the re-slicing. In the loading step of the unprocessed wafer, it is only possible to load and hold the wafer on the inside chuck 22 and further unload the wafer from the chuck 22 when the outside chuck 21 is separated from the inside chuck 22 with a maximum clearance between them other than during the re-slicing operation. With respect to the re-slicing operation of the unprocessed wafer held on the inside chuck 22, this operation is characterised in that the re-slicing work for the unprocessed wafer is done by the holding by the inside chuck 22 only during half of the re-slicing operation; however, in the last stage of the re-slicing operation or just before the completion of re-slicing work at the latest, the outside chuck 21 will move inwardly to hold the outside surface of the unprocessed wafer so as to carefully approach to hold such a thin wafer from outside. That is, now both sides of the wafer are held between the inside chuck 22 and outside chuck 21 accordingly in order to continuously hold both wafers which have been re-sliced from one sheet of an unprocessed wafer into two sheets of processed wafers upon the completion of the re-slicing operation. Longitudinal feeder mechanism 3, for positioning the chucking mechanism 2 with an unprocessed wafer against the ID saw, comprises a driving mechanism which is driven by a servomotor or the like (not shown in the drawings) and an automatic thickness controller (not shown in the drawings). The above driving mechanism is directed to feed and position an unprocessed wafer held with the inside chuck 22 of the chucking mechanism 2 at the correct position for re-slicing the unprocessed wafer from substantially the center portion of core thickness of the wafer against the active blade edge of ID saw 12 in co-operation with the mechanism, and then is driven to retract the processed wafers which have been re-sliced into two sheets and held by both chucks 22, 21 for unloading two sheets of the wafers so as to avoid the re-slicing mechamism 1 as shown in Fig. 1(B). Lateral feeder mechanism 4 comprises a servo-motor or the like, which is operated upon the completion of positioning at the right position for re-slicing the wafer against the ID saw by the above longitudinal feeder mechanism. The lateral feeder mechanism 4 feeds the chucking mechanism 2 together with the unprocessed wafer laterally so as to re-slice the wafer into two sheets at the correct position or it may optionally be moved vertically. As a requirement of this step, the operation of the above longitudinal feeder mechanism 3 is prohibited while the lateral feeder mechanism 4 is under operation by using an interlock-circuit in the controller to switch each operation between the longitudinal and lateral feeders mechanism 3, 4 respectively. The loading and unloading mechamism 5 is illustrated in Fig. 2(A) in detail. Fig. 2(A) is a side view schematically illustrating the configuration of loading and unloading mechanism 5 in rotation to the storage space of wafer-magazines 6, 7 and the chucking mechanism 2 for the unprocessed wafer W in the storage space. One magazine is loaded with a plurality of unprocessed wafers W, which are shown upright in side view in Fig. 2(A), and the other magazine 7 is now shown as empty in Fig. 2(A) but later receives wafers W′ as shown in Fig. 2(H). The loading and unloading mechanism 5 is illustrated schematically in Fig. 2(A) as a gantry crane type conveyor extending over and between the storage space of wafer magazines 6, 7 and the chucking mechanism with unprocessed wafer W so as to initially take out an unprocessed wafer W from wafer magazine 6. Wafer W is lifted up, and then conveyed laterally while hanging shows from a main conveyer 51a toward the upper portion of the chucking mechanism 2 in order to descend and load the unprocessed wafer W on the inside chuck 22. Upon the completion of re-slicing the wafer W, i.e. two sheets of wafers W′, these wafers W′ are sent back along the above described course in reverse, which is the concept of the loading and unloading mechanism 5. The construction of the loading and unloading mechanism 5 comprises a conveyer portion 51, a main conveyer 51a, a subconveyer 51b and H-shaped loaders including a loading manipulator 51c and unloading manipulator 51d. This combination of loading and unloading manipulators 51c, 51d operates to immediately load an unprocessed wafer, which is in the stand-by position upon the completion of unloading the two sheets of the processed wafers W′ through the function of the unloading manipulator 51d by shifting the stand-by position of the unprocessed wafer W to the loading position of the wafer W on the inside chuck 22. The shifting movement between the loading and unloading manipulators 51c, 51d is operated by the sub-conveyer 51b. The loading manipulator 51c further includes an arm portion which is operated up and down, a hinge arm 52a with a pivot portion 52b, which is operated by a rotary actuator or the like, and a single vacuum cup 53′, which is operated by a rotary actuator or the like, and a single vacuum cup 53′, which is provided on the end portion of the hinge arm 52a to be capable of attracting and holding an unprocessed wafer W by pneumatic vacuum action. The unloading manipulator 51d further includes an arm portion 52′, which is operated up and down, a hinge arm 52a′ with a pivot portion 52b′ which is operated by a rotary actuator or the like, a servo-motor M provided along the same axis as the hinge arm 52a′ to rotate the arm 52a′ through a 180° angle, and double vacuum cups 53′ provided on the end portion of the hinge 52a′ to be capable of attracting and holding the two sheets of processed wafers W′ by pneumatic vacuum action. The hinge arms 52a, 52a′ operate to orientate the slice base portion of an unprocessed wafer at the last position of the re-slicing process when the wafer is re-sliced by the ID saw by bending up the hinge arms to an L-shape from the half way positions of the arms. Regarding the necessity of the rotary solenoid type motor, since two sheets of processed wafers W′ are simultaneously unloaded by the double vacuum cups 53′, 53′ of the unloading manipulator 51d, with both plane re-sliced surfaces being face to face, it is necessary to unload the two sheets of the wafers W′ into the wafer magazine 7 in the same direction but not face to face. Therefore, one sheet of wafer W′ is unloaded first and then the other wafer is lifted up and turned around through a 180° angle so as to be in the same direction with the earlier wafer W′ in the wafer magazine 7. Magazines 6, 7 each comprise a rack type magazine having a plurality of vertical grooves in both interior walls, of the magazine body for receiving both side periphery edges of the semiconductor wafers along the vertical grooves in both interior walls and at a predetermined pitch. The respective magazine is mounted on a feeder 6′, 7′ which is driven by a step motor or the like, wherein the magazine is fed at a predetermined pitch so as to be synchronized with a working pace of loading and unloading the unprocessed and processed semiconductor wafers W, W′. Referring now in detail to the operation of the loading and unloading mechanism 5, the re-slicing process of the semiconductor wafer is illustrated in the series of FIG. 2(A) to FIG. 2(J) as follows:- 1) FIG. 2(A) illustrates the loading and unloading mechanism 5 being in a stand-by position, wherein the sub-conveyer 51b is positioned at the most right side of the main conveyer 51a through a hanging rod. H-shaped loading and unloading manipulators 51c, 51d are positioned at the most left side of the sub-conveyer 51b through a hanging rod fixed between these manipulators 51c, 51d and an unprocessed wafer is held in a stand-by position by the single vacuum cup 53′ of the hinge arm 52a, which is bent in an L-shape. Thus, when the unprocessed wafer W is in the stand by position as described above, on the other hand an earlier unprocessed wafer W is under the operation of re-slicing process by the re-slicing mechanism 2 as illustrated in FIG. 2(A1), which is illustrated as a plan view so as to facilitate the understanding of the re-slicing process as simultaneous proceeding together with the loading and unloading process. As described previously, the re-slicing process of the earlier wafer W is commenced by holding the wafer on the inside chuck 22, however, to approach the last stage of the re-slicing process, the other chuck, i.e. the outside chuck 21, will move inwardly to hold the opposite side of the wafer in order to be prepared when the wafer has been completely re-sliced. Upon the completion of this re-slicing process, the outside chuck 21 is again moved back to the outside while holding one of processed wafer W′ as shown in FIG. 2(A2) so as to provide a necessary space between both wafers W, W′ in order to allow the insertion of the double vacuum cups 53′. 2) FIG. 2(B) illustrates the hinge arm 52a′ descending into the enlarged space between both chucks 22, 21 to receive the two sheets of processed wafers W′, W′ simultaneously by using the double vacuum cups 53′ from these chucks 22, 21 as shown in Fig. 2(B1). 3) FIG. 2(C) illustrates the unloading manipulator 51d pulling up the hinge arm 52a′ together with the two sheets of the processed wafers W′, W′ and the sub-conveyor 51b moves the hanging rod of the manipulators 51c, 51d to the most right side. According to this movement of the manipulators 51c, 51d to the right side, a next unprocessed wafer has been positioned at the nearest position to the inside chuck 22 of the chucking mechanism 2 which is now empty. 4) FIG. 2(D) illustrates the hinge arm 52a′ being kept intact in the paragraph 3) position, together with two sheets of the processed wafers W′, W′ and the other hinge arm 52a of the loading manipulator 51c descends into the space which is still enlarged between both chucks 22, 21, which are all empty, to load one sheet of the unprocessed wafer W on the inside chuck 22 while bending up the hinge 52a into an L-shape as shown in FIG. 2(D). 5) FIG. 2(E) illustrates the loading manipulator 51c pulling up the hinge arm 52a to the same level with the other hinge arm 52a′. On the other hand, the chucking mechanism starts to be fed by the horizontal feeder mechanism 3 (see FIGS. 1(A) and 1(B) for positioning at the correct position for re-slicing the unprocessed wafer W through substantially the center portion of core thickness of the wafer W in cooperation with an automatic thickness control. Upon the decision of the right positioning, the horizontal feeder mechanism 3 is locked and the vertical feeder mechanism 4 operates chucking mechanism 2 to re-slice the wafer (see FIGS. 1(A) and 1(B). 6) FIG. 2(F) illustrates the main conveyer 51a moving the hanging rod of the manipulators 51c, 51d to the leftmost side to be above the storate space of the wafer magazines 6, 7 of the unprocessed and processed wafers. 7) FIG. 2(G) illustrates both hinge arms 52a, 52a′ being straightened out downwardly and then descending together into both wafer magazines 6, 7. In the first stroke, the single vacuum cup 53′ catches a new unprocessed wafer W from the wafer magazine 6, and the double vacuum cups 53′ release one of the two sheets of processed wafers W′, W′ into wafer magazine 7. 8) FIG. 2(H) illustrates both manipulators 51c, 51d, pulling up their hinge arms 52a, 52a′ simultaneously together with the new unprocessed wafer W, on the single vacuum cup 53′ and the remainder piece of processed wafer W′ on the double vacuum cups 52c. 9) FIG. 2(I) illustrates that first the processed wafer magazine 7 is mechanically fed by one pitch along the Y-axis, for receiving the remaining processed wafers W′, i.e. the longitudinal direction of wafer magazine 7 (see FIG. 2(A) by the feeder 7′, while hinge arms 52a, 52a′ are lifted in the paragraph 8) step. Second, only the hinge arm 52a′ is rotated through a 180° angle by operating the motor for making the facing direction of the remaining wafer W′ the same as the first wafer W′ which was loaded into the wafer magazine, and then the hinge arm 52a′ is further lowered to release the remaining wafers W′ from the double vacuum cups 53′ into the processed wafer magazine 7. Third, the other hinge arm 52a is bent up again as an L-shape together with the new unprocessed wafer W. 10) FIG. 2(J) illustrates the hinge arm 52a′ being lifted up and bent up as an L-shape. Both wafer magazines 6, 7 are fed at one pitch respectively along the y-axis direction for the preparation of further loading and unloading steps. After that, manipulators 51c, 51d are further moved to the stand-by position upon the chucking mechanism 2 as illustrated in the paragraph 1) step. Then these 10 steps from 1 to 10 are repeated continuously. FIGS. 3, 4 and 5 illustrate a relationship between an unprocessed semiconductor wafer W, with a slice base or a processed semiconductor wafer W′ and wafer magazines 6, 7. According to the prior art disclosed previously in the description of the present invention, it is known that it is advantageous to mount a thin slice base in advance on the periphery edge of an unprocessed wafer before the re-slicing process of the unprocessed semi-conductor wafer in order to prevent the wafer's edge from any chipping off damage during the re-slicing process by a slicing machine. In view of the advantage of preparing the slice base mounted in advance on the periphery edge of a semi-conductor wafer, the semi-conductor wafer used in the present invention is adapted with the slice base as is usual. Thus, FIGS. 3(A), 3(B) and 4 illustrate an angle range for mounting the slice base on the wafer edge in accordance with the known art. FIGS. 3(A) and 3(B) further show a plurality of unprocessed or processed wafers W or W′ having flat portions, such as an orientation flat on the upper or left side of the wafer W or W′. These wafers are loaded in wafer magaziness 6 or 7 in the storage space. As a modification of mounting the slice base on the wafer edge, in FIGS. 4(A), 4(B) and 4(C), the present invention suggests that a continuous slit Wa or groove is carved in advance along all of the circumference of unprocessed wafer W with an approximately 1 mm depth and a width being wider than the blade core thickness of the ID saw 12. Then, a quick solidifying type adhesive C is filled into the continuous slit Wa or groove as a substitute for a slice base. In this modification, it is further suggested to chamfer both corner edges Wc, Wc of the bottom surface of the unprocessed wafer and also the corner edges Wb, Wb of the opening portion of the continuous slit Wa since the slit corner chamfer edges Wb facilitate the filing of the adhesive C into the slit, and the bottom corner chamfer edges Wc are effective to handle the wafer during the processes before and after the re-slicing process. FIG. 5 illustrates a mold type slice base C being formed as a C-shape so as to cover the end of the semiconductor wafer W by molding an adhesive material C simultaneously on a wafer edge. This is useful to prevent the wafer edge from chipping off damage during the re-slicing process, as provided in earlier application Ser. No. 07/590,806 by the Applicant of the present invention. This invention is not limited to the above illustrated preferred embodiment, for example, the above preferred embodiment can be modified in that the main conveyor 51a may use a rodless cylinder, however, it may also use a stepping motor or the like. Further, it can incorporate the main conveyer 51a with the sub-conveyer 51b. In other words, the main conveyer 51a can be modified to be usable without any sub-conveyer 51b by providing a special type rodless cylinder capable of stopping the movement of the main conveyer 51a sensitively at any position, so as to be usable as a substitute for the sub-conveyer 51b; that is there is not any definite reason that this invention must use two conveyers such as the main and subconveyers 51a, 51b separately. As another option, the above illustrated preferred embodiment is described as the chucking mechanism 2 with an unprocessed wafer W being fed against the re-slicing mechanism, i.e. ID saw, by using the lateral feeder mechanism 4, however, it may be possible to feed the re-slicing mechanism 1 itself and not the chucking mechanism. Regarding further modifications for the hinge arms 52a, 52a′ with pivot portions 52b, 52b′ of the loading and unloading mechanism 5 of the present invention illustrated in the above preferred embodiment, basically this hinge arm rotation of a 90° angle is only to load an unprocessed wafer on the inside chuck 22 of the chucking mechanism 2 so as to face the orientation flat portion of the unprocessed wafer W upwardly to allow the wafer W to be started to be re-sliced first by the ID saw and then finished at the slice base portion as marked 8 in FIG. 3(A); however, this feature only depends on the initial loading direction of the unprocessed wafers into wafer magazine 6 in the storage space. In other words, in this embodiment, it is only necessary that initially the plurality of unprocessed wafers W were loaded in the wafer magazine 6 so as to face the orientation flat portion to the right side and to face the slice base to the left side, therefore, it was required to rotate the wafer in a counterclockwise direction at a 90° angle. In view of the above situation, the loading direction of the plurality of unprocessed wafers W in the wafer magazine 6 can be modified so as to face the orientation flat portion upwardly as illustrated in FIG. 3(A) in case of vertical re-slicing or FIG. 3(B) in case of lateral re-slicing. As the result of this modification of wafer loading direction, the loading and unloading manipulators 51c, 51d can be modified to be only straight without the hinge arms 52a, 52a′ with the pivot portions 52b, 52b′ in the present invention although the hinge arm is advantageous for reducing the total height of the whole system.

Claims: An apparatus for slicing semiconductor wafers, comprising: a slicing mechanism (1) provided with a slicing saw (12) for slicing an unprocessed semiconductor wafer (W) into two processed wafer slices having substantially the same thickness; a chucking mechanism (2) adapted to chuck an unprocessed wafer (W) continuously until the wafer has been sliced by the slicing mechanism (1); a drive mechanism (3,4) adapted to drive the chucking mechanism (2) such that the wafer presents itself to the slicing saw blade edge, subsequently to move the chucking mechanism (2) and the slicing saw (12) relatively together in a direction disposed in the plane of the slicing saw (12) to slice the unprocessed wafer (W) and afterwards to retract the chucking mechanism with processed wafers (W′) upon completetion of the slicing process; a loading and unloading mechanism (5), comprising a loading manipulator (52) and an unloading manipulator (52′), adapted to effect the loading and unloading of said unprocessed and processed wafers between an unprocessed wafer storage means (6), the chucking mechanism (2) and a processed wafer recovery means (7); characterised in that the chucking mechanism (2) comprises two opposed chucks (21,22) for holding the two slices of processed wafer (W′), the clearance between said chucks being adjustable by moving one of said chucks so as to allow the insertion of the loading and unloading mechanism in the intervening space to effect the unloading of the said slices. An apparatus according to claim 1, characterised in that the loading and unloading mechanism (5) is adapted to transfer the processed wafer (W′) into the processed wafer recovery means (7) and transfer an unprocessed wafer (W) from the unprocessed wafer storage means (6) to a stand-by position during the slicing of a previously-loaded unprocessed wafer (W). An apparatus according to claim 1 or 2, characterised in that the chucking mechanism comprises a pair of vacuum chucks (21,22) and the loading and unloading mechanism (5) comprises a loading manipulator (51c) with a single vacuum cup (53′) located at its free end and an unloading manipulator (51d) with double vacuum cups (53′) located at its free end, arranged so that the chucking mechanism (2) receives an unprocessed semiconductor wafer from said loading manipulator (51c) and then chucks one side of said unprocessed wafer with one of the vacuum chucks (22), and the opposite side with the other vacuum chuck (21), so as to hold both slices of the processed wafer (W′) upon completion of the slicing process until the wafer slices are removed from the chucking mechanism (2) by the unloading manipulator (51d). An apparatus according to claim 3, characterised in that the pair of vacuum chucks (21,22) are adapted to maintain a predetermined spacing, thereby to deliver the two wafer slices (W′) simultaneously to the double vacuum cups (53′) of the unloading manipulator (51d) upon insertion thereof into said intervening space. An apparatus according to any of claims 1 to 4, characterised in that the unprocessed wafer storage means (6) and the processed wafer recovery means (7) are arranged in parallel to each other to form a storage space, said storage means and said recovery means each comprising a wafer magazine and further comprising feeder mechanisms to feed them intermittently along their longitudinal direction, and in that the loading and unloading mechanism is capable of operating vertically in said storage space in cooperation with the said feeder mechanisms. An apparatus according to any of claims 1 to claim 5, characterised in that the loading and unloading mechanism (5) is provided with both a loading means (51c) for said unprocessed wafer and unloading means (51d) for said processed wafer attached to one another to form a combined loading and unloading system. An apparatus according to any of claims 1 to claim 6, characterised in that the unprocessed wafer (W) consists of a processed wafer doped in advance with impurity diffusion layers on both sides and without an impurity diffusion layer in its plane core portion.

Inventors: IBARAKI TADASHI, SATO TSUTOMU, IBARAKI, TADASHI, SATO, TSUTOMU
Applicants: NAOETSU DENSHI KOGYO KK, NAOETSU ELECTRONICS COMPANY
Application year: 1990
Main classification: H01L21
IPC codes: H01L21, B28D5, B28D1