JP6373068B2 - Transport method - Google Patents

Description

  The present invention relates to a transport method for transporting a plate-like object such as a semiconductor wafer to a chuck table.

  In a small and light electronic device typified by a mobile phone, a semiconductor chip including an electronic circuit such as an IC or an LSI has an essential configuration. For example, a semiconductor chip is formed by dividing the surface of a semiconductor wafer made of a material such as silicon by a plurality of division lines called streets, forming an electronic circuit in each region, and then cutting the semiconductor wafer along the streets. Manufactured.

  In recent years, for the purpose of reducing the size and weight of semiconductor chips, there are increasing opportunities to process a semiconductor wafer thinly by a method such as grinding. However, when a semiconductor wafer is thinly processed, internal stress becomes obvious and the semiconductor wafer is likely to warp. This tendency is particularly remarkable in a semiconductor wafer having a large diameter.

  When the warpage of the semiconductor wafer becomes large, the semiconductor wafer cannot be properly adsorbed by the chuck table in the processing apparatus, which hinders subsequent processes. For example, in a semiconductor wafer having an outer peripheral portion warped upward, a gap is formed between the chuck table and the outer peripheral portion, and a sufficient adsorption force cannot be applied to the semiconductor wafer.

  Therefore, a transport mechanism including a suction pad that sucks the central portion of the semiconductor wafer and a pressing pin (pressing plate) that presses the outer peripheral portion of the semiconductor wafer against the chuck table has been proposed (for example, Patent Document 1, Patent). Reference 2). If this transport mechanism is used, the outer peripheral portion of the semiconductor wafer can be brought into close contact with the chuck table and a sufficient suction force can be applied.

JP 2005-109057 A Japanese Patent Laid-Open No. 2006-19566

  By the way, in the transport mechanism described above, a downward force is applied to the outer peripheral portion of the semiconductor wafer by lowering the pressing pin together with the suction pad. However, in this configuration, since the pressing pin must be lowered by a powerful motor or the like in order to bring the outer peripheral portion into close contact with the chuck table, the price of the processing apparatus including the transport mechanism increases.

  Further, when a downward force is applied to the outer peripheral portion of the semiconductor wafer with the pressing pin, each part of the transport mechanism is distorted by a reaction force applied to the pressing pin from the outer peripheral portion of the semiconductor wafer. In order to prevent problems such as a failure due to distortion, it is sufficient to reinforce a portion where distortion is likely to occur, but in this case as well, the price of the processing apparatus increases.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a transport method that can appropriately suck a workpiece with a chuck table without increasing the cost of a processing apparatus. is there.

According to the present invention, a temporary placement table for temporarily placing a plate-like workpiece, a chuck table having a holding surface for sucking and holding the workpiece, and a workpiece held on the chuck table are predetermined. And at least a conveying means for conveying the workpiece from the temporary placement table to the chuck table, the conveying means having a diameter larger than the workpiece and a flat suction surface. In a processing apparatus provided with a suction pad having a transporting method in which a workpiece whose outer peripheral portion is warped upward compared to the vicinity of the center is transported from the temporary placement table to the chuck table and is held on the chuck table. And placing the work piece whose outer peripheral part is warped upward relative to the vicinity of the center on the temporary placement table, and applying the suction pad of the conveying means to the work piece. Is lowered Te, and suction pads lowering step is to the entire outer peripheral portion is adhered to the adsorption pad is not near the center of the workpiece is brought into close contact with the adsorption pad in the workpiece, after performing the adsorption pad lowering step , by aspiration workpiece in the adsorption pad pressed against a workpiece by the force due to atmospheric pressure to the suction surface of the suction pad, the adsorption step of flat straightening a workpiece along the adsorption surface, adsorption The workpiece sucked by the pad is conveyed by the conveying means and placed on the chuck table, and the workpiece is adhered to the holding surface of the chuck table while the workpiece is adhered to the chuck table. And a workpiece transfer step of sucking and stopping suction of the workpiece by the suction pad of the conveying means.

  The conveyance method of the present invention includes a suction pad lowering step in which a suction pad having a diameter larger than that of the workpiece is lowered and the outer periphery of the workpiece warped upward is brought into close contact with the suction pad, A suction step for sucking the workpiece and correcting the workpiece flat along the suction surface of the suction pad, so that the workpiece that is warped upward is simply sucked by the suction pad. Work piece can be straightened.

  Therefore, in the subsequent workpiece transfer step, the workpiece sucked by the suction pad is placed on the chuck table, the workpiece is sucked by the chuck table and suction by the suction pad is stopped. The workpiece can be properly sucked by the chuck table. As described above, according to the conveying method of the present invention, since the workpiece warped upward is sucked with the suction pad and corrected to be flat, the workpiece can be chucked without increasing the cost of the processing apparatus. It can be sucked properly at the table.

It is a perspective view showing typically an example of composition of a grinding device using a conveyance method concerning this embodiment. FIG. 2A is a perspective view schematically illustrating an example of a workpiece conveyed by the conveyance method according to the present embodiment, and FIG. 2B schematically illustrates an example of the workpiece. It is sectional drawing. FIG. 3A is a cross-sectional view schematically showing the placement process and the suction pad lowering process, and FIG. 3B is a cross-sectional view schematically showing the suction pad lowering process. C) is a cross-sectional view schematically showing an adsorption step. FIG. 4A, FIG. 4B, and FIG. 4C are cross-sectional views schematically showing a workpiece transfer process.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The transport method according to the present embodiment includes a placement process (see FIG. 3A), a suction pad lowering process (see FIGS. 3A and 3B), and a suction process (see FIG. 3C). ) And a workpiece transfer step (see FIGS. 4A, 4B, and 4C).

  In the placing step, the workpiece warped upward is placed on a temporary placement table of the processing apparatus. In the suction pad lowering step, the suction pad having a diameter larger than that of the workpiece is lowered, and at least the outer peripheral portion of the workpiece is brought into close contact with the suction pad.

  In the suction process, the workpiece is sucked with the suction pad, so that the workpiece is straightened along the suction surface of the suction pad. In the workpiece transfer step, the workpiece sucked by the suction pad is placed on the chuck table, the workpiece is sucked by the chuck table, and suction by the suction pad is stopped. Hereinafter, the conveyance method according to the present embodiment will be described in detail.

  First, a configuration example of a processing apparatus that uses the transport method according to the present embodiment will be described. FIG. 1 is a perspective view schematically showing a configuration example of a grinding apparatus using the conveying method according to the present embodiment. Note that the conveyance method according to the present embodiment may be used in other processing apparatuses such as a cutting apparatus.

  As shown in FIG. 1, the grinding device (processing device) 2 includes a base 4 that supports each component. An opening 4 a is formed on the front end side of the upper surface of the base 4, and a transport mechanism 6 for transporting the disk-shaped workpiece 11 (see FIG. 2) is provided in the opening 4 a. Further, cassettes 8a and 8b capable of accommodating the workpiece 11 are placed in a region further forward of the opening 4a.

  FIG. 2A is a perspective view schematically showing an example of the workpiece 11 conveyed by the conveying method according to the present embodiment, and FIG. 2B is a schematic example of the workpiece 11. FIG. As shown in FIG. 2A, the workpiece 11 is a substantially circular plate-like object made of a semiconductor material such as silicon, and a notch 11a indicating a crystal orientation is formed on the outer peripheral edge. ing. As shown in FIG. 2B, the workpiece 11 is warped in a downwardly convex state, and the outer peripheral portion 11c is higher than the central portion (near the center) 11b.

  An alignment mechanism 10 for aligning the workpiece 11 is provided behind the placement area on which the cassette 8a is placed and the opening 4a. The alignment mechanism 10 includes a temporary placement table 12 on which the workpiece 11 is temporarily placed. For example, the alignment mechanism 10 is transported by the transport mechanism 6 from the cassette 8a and is centered on the workpiece 11 temporarily placed on the temporary placement table 12. Align.

  At a position adjacent to the alignment mechanism 10, a carry-in mechanism (conveying means) 14 that rotates while sucking and holding the workpiece 11 is disposed. The carry-in mechanism 14 includes a suction pad 14b (see FIG. 3A) that sucks the entire upper surface side of the workpiece 11, and transports the workpiece 11 aligned by the alignment mechanism 10 backward.

  A turntable 16 that is rotatable around a rotation axis extending in the vertical direction is disposed behind the carry-in mechanism 14. Three chuck tables 18 for sucking and holding the workpiece 11 are provided on the upper surface of the turntable 16. Note that the number of chuck tables 18 arranged on the turntable 16 is not necessarily limited to three.

  The workpiece 11 sucked and held by the suction pad 14 b of the carry-in mechanism 14 is carried into each chuck table 18. Each chuck table 18 is connected to a rotation mechanism (not shown) such as a motor, and rotates around a rotation axis extending in the vertical direction.

  The upper surface of each chuck table 18 is a holding surface 18c (see FIG. 4B, etc.) that holds the workpiece 11 by suction. The holding surface 18c is connected to a suction source (not shown) through a flow path 18d (see FIG. 4B and the like) formed inside the chuck table 18. The workpiece 11 carried into the chuck table 18 is sucked on the lower surface side by the negative pressure of the suction source acting on the holding surface 18c.

  Two support structures 20 extending upward are provided behind the turntable 16. A Z-axis movement table 24 is provided on the front surface of each support structure 20 via a Z-axis movement mechanism 22. Each Z-axis moving mechanism 22 includes a pair of Z-axis guide rails 26 parallel to the Z-axis direction, and a Z-axis moving table 24 is slidably installed on the Z-axis guide rails 26.

  A nut portion (not shown) is fixed to the rear surface side (back surface side) of each Z-axis moving table 24, and a Z-axis ball screw 28 parallel to the Z-axis guide rail 26 is screwed to the nut portion. ing. A Z-axis pulse motor 30 is connected to one end of each Z-axis ball screw 28. When the Z-axis ball screw 28 is rotated by the Z-axis pulse motor 30, the Z-axis moving table 24 moves in the Z-axis direction along the Z-axis guide rail 26.

  A grinding mechanism (processing means) 32 is provided on the front surface (surface) of each Z-axis moving table 24. Each grinding mechanism 32 includes a spindle housing 34 fixed to the Z-axis moving table 24. A spindle (not shown) is rotatably supported on each spindle housing 34.

  A grinding wheel 36 is attached to the lower end of each spindle. Each grinding wheel 36 includes a cylindrical wheel base formed of a metal material such as aluminum or stainless steel, and a plurality of grindstones arranged in an annular shape on the lower surface of the wheel base.

  When the workpiece 11 is sucked and held by the chuck table 18, the turntable 16 rotates to position the workpiece 11 below the grinding mechanism 32. Thereafter, the workpiece 11 can be ground by lowering the grinding mechanism 32 while rotating the chuck table 18 and the grinding wheel 36 and bringing the grinding wheel 36 into contact with the upper surface of the workpiece 11.

  At a position adjacent to the carry-in mechanism 14, a carry-out mechanism 38 that rotates while sucking and holding the workpiece 11 after grinding is provided. In front of the unloading mechanism 38 and behind the opening 4a, a cleaning mechanism 40 for cleaning the workpiece 11 after being unloaded by the unloading mechanism 38 is disposed. The workpiece 11 cleaned by the cleaning mechanism 40 is transported by the transport mechanism 6 and stored in the cassette 8b.

  Next, the conveyance method of this embodiment implemented with the grinding apparatus 2 mentioned above is demonstrated. In the transport method according to the present embodiment, first, a placing step of placing the workpiece 11 warped upward on the temporary placement table 12 of the grinding apparatus 2 is performed. FIG. 3A is a cross-sectional view schematically showing a placement process and a suction pad lowering process.

  As shown in FIG. 3A, the temporary placement table 12 includes a table body 12b fixed to the support base 12a. The table main body 12b is formed in a disk shape having a smaller diameter than the workpiece 11, and has a recess on the upper surface. A disc-shaped adsorption member 12c made of a porous material is fitted into the recess of the table body 12b.

  The upper surface of the adsorption member 12c is a holding surface that holds the workpiece 11 by suction. The holding surface is connected to a suction source (not shown) through a flow path 12d formed inside the support base 12a and the table body 12b.

  In the placing step, the workpiece 11 in the cassette 8a is transported by the transport mechanism 6 and placed on the temporary placement table 12, and then the negative pressure of the suction source is applied to the holding surface. Specifically, the workpiece 11 is placed on the temporary placement table 12 with the workpiece 11 warped upward.

  As a result, the workpiece 11 is sucked and held on the lower surface side by a negative pressure acting on the holding surface. The temporary placement table 12 is formed with a smaller diameter than the workpiece 11 and sucks only the lower surface side of the central portion 11b, so that even the workpiece 11 warped upward can be appropriately sucked and held.

  After performing the placing process, the suction pad lowering process is performed in which the suction pad 14b of the loading mechanism 14 is lowered to bring the outer peripheral portion 11c of the workpiece 11 into close contact with the suction pad 14b. FIG. 3B is a cross-sectional view schematically showing the suction pad lowering step.

  As shown in FIGS. 3A and 3B, the carry-in mechanism 14 includes a suction pad 14b connected to the support arm 14a. The suction pad 14b is formed in a disk shape having a larger diameter than the workpiece 11, and has a recess on the lower surface. A disc-shaped suction member 14c made of a porous material is fitted in the recess of the suction pad 14b.

  The lower surface of the suction member 14c is a suction surface that holds the workpiece 11 by suction. The suction surface is connected to a suction source (not shown) through a flow path 14d formed inside the support arm 14a and the suction pad 14b.

  In the suction pad lowering step, the support arm 14a of the carry-in mechanism 14 is turned to position the suction pad 14b above the temporary table 12 as shown in FIG. Next, the suction pad 14b is lowered toward the workpiece 11, and the outer peripheral portion 11c is brought into close contact with the suction pad 14b over the entire circumference as shown in FIG.

  After performing the suction pad lowering step, the suction step is performed in which the workpiece 11 is sucked by the suction pad 14b and the workpiece 11 is flattened along the suction surface of the suction member 14c (suction pad 14b). To do. FIG. 3C is a cross-sectional view schematically showing the adsorption process.

  In the suction step, the negative pressure of the suction source is applied to the suction surface of the suction member 14c (suction pad 14b) while the outer peripheral portion 11c of the workpiece 11 is in close contact with the suction pad 14b. As a result, the workpiece 11 is pressed against the suction surface of the suction member 14c (suction pad 14b) with an upward force due to atmospheric pressure.

  Thereby, the workpiece 11 can be corrected flatly along the suction surface of the suction member 14c (suction pad 14b). In this suction step, the suction pad 14b of the carry-in mechanism 14 may be slightly lowered in accordance with the suction of the workpiece 11. Thereby, the upper surface of the workpiece 11 can be adhered to the entire suction surface of the suction member 14c (suction pad 14b). For the same reason, the suction of the workpiece 11 by the temporary placement table 12 may be stopped.

  After performing the suction process, the workpiece 11 sucked by the suction pad 14b is placed on the chuck table 18, and the workpiece 11 is sucked by the chuck table 18 and suction by the suction pad 14b is stopped. Perform the workpiece transfer process. FIG. 4A, FIG. 4B, and FIG. 4C are cross-sectional views schematically showing a workpiece transfer process.

  As shown in FIGS. 4B and 4C, the chuck table 18 includes a table body 18b connected to the support base 18a. The upper surface of the table body 18b is a holding surface 18c that holds the workpiece 11 by suction. The holding surface 18c is connected to a suction source (not shown) through a flow path 18d formed inside the support base 18a and the table body 18b.

  As shown in FIGS. 4A and 4B, in the workpiece transfer step, first, the suction of the workpiece 11 by the temporary placement table 12 is stopped. Then, the workpiece 11 sucked and held by the suction pad 14 b is transported and placed on the holding surface 18 c of the chuck table 18.

  Thereafter, as shown in FIG. 4B, with the lower surface of the workpiece 11 in close contact with the holding surface 18c of the chuck table 18, a negative pressure of a suction source is applied to the holding surface 18c. Since the workpiece 11 is corrected to be flat by the suction pad 14b, the entire lower surface of the workpiece 11 can be appropriately sucked and held by the chuck table 18.

  Further, the suction of the workpiece 11 by the suction pad 14b is stopped, and the suction pad 14b is separated from the upper surface of the workpiece 11 sucked and held by the chuck table 18, as shown in FIG.

  As described above, in the conveyance method of the present embodiment, the suction pad 14b having a diameter larger than that of the workpiece 11 is lowered, and the outer peripheral portion 11c of the workpiece 11 that is warped upward is brought into close contact with the suction pad 14b. A suction pad lowering step, and a suction step of sucking the workpiece 11 with the suction pad 14b and correcting the workpiece 11 flat along the suction surface of the suction pad 14b (suction member 14c). The workpiece 11 can be flattened simply by sucking the workpiece 11 warped upward with the suction pad 14b.

  Therefore, in the subsequent workpiece transfer step, the workpiece 11 sucked by the suction pad 14b is placed on the chuck table 18, the workpiece 11 is sucked by the chuck table 18, and the suction pad 14b is used. By stopping the suction, the workpiece 11 can be appropriately sucked by the chuck table 18. As described above, according to the transport method of the present embodiment, the workpiece 11 that is warped upward is sucked by the suction pad 14b to be flattened, so that the price of the grinding device (processing device) 2 is increased. The workpiece 11 can be appropriately sucked by the chuck table 18 without any problem.

  Note that the configurations, methods, and the like according to the above-described embodiments can be modified as appropriate without departing from the scope of the object of the present invention.

11 Workpiece 11a Notch 11b Center part (near the center)
11c Outer peripheral part 2 Grinding device (processing device)
4 Base 4a Opening 6 Transport mechanism 8a, 8b Cassette 10 Alignment mechanism 12 Temporary placement table 12a Support base 12b Table body 12c Adsorption member 12d Flow path 14 Carry-in mechanism (transport means)
14a Support arm 14b Suction pad 14c Suction member 14d Channel 16 Turntable 18 Chuck table 18a Support base 18b Table body 18c Holding surface 18d Channel 20 Support structure 22 Z-axis moving mechanism 24 Z-axis moving table 26 Z-axis guide rail 28 Z Axis ball screw 30 Z-axis pulse motor 32 Grinding mechanism (processing means)
34 Spindle housing 36 Grinding wheel 38 Unloading mechanism 40 Cleaning mechanism

Claims (1)

Temporary placing table for temporarily placing a plate-like workpiece, a chuck table having a holding surface for sucking and holding the workpiece, and processing means for performing predetermined processing on the workpiece held on the chuck table And a conveying means for conveying a workpiece from the temporary placement table to the chuck table, the conveying means comprising a suction pad having a larger diameter than the workpiece and having a flat suction surface In the processing apparatus, the workpiece is transferred from the temporary table to the chuck table and held on the chuck table with the outer peripheral portion being warped upward compared to the vicinity of the center.
A placing step of placing the work piece in a state in which the outer peripheral portion is warped upward compared to the vicinity of the center on the temporary placement table;
The suction pad of the conveying means is lowered toward the workpiece, and the entire circumference of the outer peripheral portion of the workpiece is brought into close contact with the suction pad, but the vicinity of the center of the workpiece is not brought into close contact with the suction pad A descent process;
After performing the adsorption pad lowering step, by sucking a workpiece in the adsorption pad pressed against a workpiece by the force due to atmospheric pressure to the suction surface of the suction pad, flat workpiece along the adsorption surface An adsorption process to correct
The workpiece sucked by the suction pad is transferred by the transfer means and placed on the chuck table, and the workpiece is processed by the chuck table in a state where the workpiece is in close contact with the holding surface of the chuck table. And a workpiece transfer step of sucking the workpiece and stopping the suction of the workpiece by the suction pad of the conveying means.