JP5669518B2 - Wafer transfer mechanism - Google Patents

Description

  The present invention relates to a wafer transport mechanism that holds and transports a wafer such as a semiconductor wafer.

  In a semiconductor device manufacturing process, a semiconductor device is formed in each region partitioned by a plurality of division lines called streets on the surface of a semiconductor wafer. The semiconductor wafer is ground to a predetermined thickness by a grinding device and then processed along a street by a dicing device to be divided into individual devices, thereby manufacturing semiconductor devices such as IC and LSI.

  The grinding apparatus cleans the chuck table for holding the wafer, a grinding means for grinding the wafer held on the chuck table, a wafer transport mechanism for carrying the ground wafer out of the chuck table, and the ground surface of the carried wafer The wafer can be processed into a desired thickness (see, for example, JP-A-2003-300155).

  A grinding apparatus that grinds the back surface of a wafer is required to thinly grind the wafer and to prevent fine grinding dust from adhering to the ground surface of the wafer after grinding. In some cases, the back surface of the wafer is ground with a grinding machine, and then a sub-device (rewiring layer) is formed on the back surface of the wafer. In such a case, contamination such as grinding dust adhering to the back surface of the wafer is the reference value. Must be less than

  Conventionally, when a ground wafer is unloaded from a chuck table, the wafer is sucked by a vacuum suction pad attached to the tip of a rotatable arm and transported from the chuck table to the cleaning unit. doing.

JP 2003-300155 A

  However, in a wafer transfer device that uses a suction pad, the wafer immediately after grinding is transferred to a cleaning unit to clean the ground surface, but the back surface of the wafer dries due to suction of the suction pad of the wafer transfer mechanism. Thus, there is a problem that contamination exceeding the reference value adheres to the back surface of the wafer and it is difficult to remove contamination such as grinding scraps even if the cleaning unit cleans.

  The present invention has been made in view of the above points, and the object of the present invention is to convey a wafer that does not contaminate the ground surface of the wafer after grinding and does not cause grinding dust to adhere to the ground surface. Is to provide a mechanism.

According to the present invention, there is provided a wafer transport mechanism for holding and transporting a wafer, comprising: an arm; and a holding pad for sucking and holding the wafer supported by elastic support means at the tip of the arm. The pad includes an annular suction holding portion that sucks and holds the outer periphery of the wafer, a concave portion that forms a space between the annular suction holding portion and a wafer that is sucked and held, and a liquid that supplies liquid to the concave portion. a supply unit, seen including a plurality of discharge portions formed in a groove shape to the sucking and holding portion of the annular discharging the liquid from the recess, and a recess in the discharge portion of said plurality of holding the wafer the A wafer transfer mechanism is provided that communicates with the outside of the holding pad .

  According to the wafer conveyance mechanism of the present invention, since the outer peripheral portion of the wafer after grinding is held by the annular suction holding portion, there are few portions in contact with the wafer grinding surface, and the wafer grinding surface is always made of a water layer. Since the wafer is transported from the chuck table to the cleaning unit while filling, the ground surface does not dry, and contamination that exceeds the reference value can be prevented.

It is a surface side perspective view of a semiconductor wafer. It is a back surface side perspective view of a semiconductor wafer in the state where a protective tape was stuck on the surface. It is a perspective view of the grinding device provided with the wafer conveyance mechanism of the present invention. It is a perspective view of the wafer conveyance mechanism which concerns on this invention embodiment. It is principal part sectional drawing of a wafer conveyance mechanism. It is a back surface side perspective view of a holding pad. It is a perspective view of the holding pad part which shows the state where water is discharged from the discharge part.

  Hereinafter, a wafer conveyance mechanism according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view of a semiconductor wafer 11 before being processed to a predetermined thickness. The semiconductor wafer 11 shown in FIG. 1 is made of, for example, a silicon wafer having a thickness of 700 μm, and a plurality of streets (division lines) 13 are formed in a lattice shape on the surface 11a. Devices 15 such as IC and LSI are formed in a plurality of partitioned areas.

  The semiconductor wafer 11 configured as described above includes a device region 17 in which the device 15 is formed, and an outer peripheral surplus region 19 that surrounds the device region 17. A notch 21 is formed on the outer periphery of the semiconductor wafer 11 as a mark indicating the crystal orientation of the silicon wafer.

  Before grinding the back surface 11b of the semiconductor wafer 11, the protective tape 23 is attached to the front surface 11a of the semiconductor wafer 11 by a protective tape attaching process. Therefore, the front surface 11a of the semiconductor wafer 11 is protected by the protective tape 23, and the back surface 11b is exposed as shown in FIG. Instead of the protective tape 23, a rigid protective member such as glass may be used.

  Next, with reference to FIG. 3, a grinding apparatus that employs the wafer conveyance mechanism of the embodiment of the present invention will be described. Reference numeral 4 denotes a base of the grinding apparatus 2, and two columns 6a and 6b are provided upright at the rear of the base. A pair of guide rails (only one is shown) 8 extending in the vertical direction is fixed to the column 6a.

  A rough grinding unit 10 is mounted along the pair of guide rails 8 so as to be movable in the vertical direction. The rough grinding unit 10 is attached to a moving base 12 whose housing 20 moves up and down along a pair of guide rails 8.

  The rough grinding unit 10 includes a housing 20, a spindle (not shown) rotatably accommodated in the housing 20, a servo motor 22 that rotationally drives the spindle, and a plurality of rough grinding grinding wheels fixed to the tip of the spindle. A grinding wheel 24 having 26 is included.

  The rough grinding unit 10 includes a rough grinding unit moving mechanism 18 including a ball screw 14 and a pulse motor 16 that move the rough grinding unit 10 up and down along a pair of guide rails 8. When the pulse motor 16 is pulse-driven, the ball screw 14 rotates and the moving base 12 is moved in the vertical direction.

  A pair of guide rails 19 (only one is shown) 19 extending in the vertical direction are also fixed to the other column 6b. A finish grinding unit 28 is mounted along the pair of guide rails 19 so as to be movable in the vertical direction.

  The finish grinding unit 28 is attached to a moving base (not shown) in which the housing 36 moves in the vertical direction along the pair of guide rails 19. The finish grinding unit 28 includes a housing 36, a spindle (not shown) rotatably accommodated in the housing 36, a servo motor 38 that rotationally drives the spindle, and a grinding wheel 42 for finish grinding fixed to the tip of the spindle. A grinding wheel 40 is included.

  The finish grinding unit 28 includes a finish grinding unit moving mechanism 34 including a ball screw 30 and a pulse motor 32 that move the finish grinding unit 28 in the vertical direction along the pair of guide rails 19. When the pulse motor 32 is driven, the ball screw 30 rotates and the finish grinding unit 28 is moved in the vertical direction.

  The grinding device 2 includes a turntable 44 disposed so as to be substantially flush with the upper surface of the base 4 on the front side of the columns 6a and 6b. The turntable 44 is formed in a relatively large-diameter disk shape, and is rotated in a direction indicated by an arrow 45 by a rotation drive mechanism (not shown).

  On the turntable 44, three chuck tables 46 are arranged so as to be rotatable in a horizontal plane, spaced from each other by 120 ° in the circumferential direction. The chuck table 46 has a suction part formed in a disk shape by a porous ceramic material, and sucks and holds the wafer placed on the holding surface of the suction part by operating a vacuum suction means.

  The three chuck tables 46 arranged on the turntable 44 are rotated in accordance with the turntable 44, so that the wafer loading / unloading area A, rough grinding area B, finish grinding area C, and wafer loading / unloading are performed. The region A is sequentially moved.

  A front portion of the base 4 includes a first wafer cassette 50, a second wafer cassette 66, a wafer transfer robot 54 having a link mechanism 51 and a hand 52, and a positioning table 56 having a plurality of positioning pins 58. A wafer carry-in mechanism (loading arm) 60, a wafer carry-out mechanism (unloading arm) 62, and a spinner cleaning unit 64 are disposed.

  The spinner cleaning unit 64 has a spinner table 68 that rotates while sucking and holding the wafer. Reference numeral 70 denotes a cover of the spinner cleaning unit 64. The wafer carry-out mechanism 62 constitutes the wafer conveyance mechanism of the embodiment of the present invention.

  The ground wafer 11 is transported to the spinner cleaning unit 64 to clean the ground surface. However, when the ground surface of the wafer is sucked and transported by the suction pad, the ground surface is brought into contact with the ground surface of the wafer. There is concern about contamination.

  Further, there has been a problem that the back surface of the wafer dries due to suction of the suction pad during wafer transport, and the grinding dust adheres to the ground surface of the wafer and does not fall off even when cleaned by the spinner cleaning unit 64. A wafer transport mechanism 62 according to an embodiment of the present invention that solves this problem will be described in detail with reference to FIGS.

  As shown in FIG. 4, the wafer transfer mechanism 62 includes a column 72 that is movable in the vertical direction, an arm 74 that is rotatably attached to the distal end portion of the column 72, and a holding member that is attached to the distal end portion of the arm 74. A pad (suction pad) 76.

  As shown in FIG. 5, an insertion hole 75 is formed at the distal end portion of the arm 74, and a support portion 78 of the holding pad 76 is inserted into the insertion hole 75, and the holding pad 76 and the arm 74 are interposed between them. By holding the coil spring 80, the holding pad 76 is elastically supported at the tip of the arm 74.

  As best shown in FIG. 6, the holding pad 76 forms a space between the annular suction holding portion 82 for sucking and holding the outer periphery of the wafer 11 and the wafer 11 surrounded by the annular suction holding portion 82. A circular recess 84 is formed. And the level | step difference h of the suction holding | maintenance part 82 and the circular recessed part 84 is formed about 1-2 mm.

  A plurality of suction holes 86 are formed in the annular suction holding portion 82, and as shown in FIG. 5, these suction holes 86 are connected to a suction source 92 through an annular suction path 88 and a suction port 90. Yes. The annular suction holding portion 82 is further formed with a plurality of (four in the present embodiment) discharge portions 94.

  A plurality of (four in this embodiment) supply holes 96 for supplying water to the circular recesses 84 are formed in the circular recess 84, and these supply holes 96 are flexible on the surface of the holding pad 76. As shown in FIG. 5, it is connected to the water source 100 through a simple pipe 98.

  Hereinafter, the operation of the wafer conveyance mechanism (wafer carry-out mechanism) 62 of the embodiment of the present invention configured as described above will be described. The wafer 11 that has been subjected to the rough grinding by the rough grinding unit 10 and the finish grinding by the finish grinding unit 28 is positioned in the wafer carry-in / out area A by rotating the turntable 44.

  Next, the arm 74 of the wafer transport mechanism 62 is rotated so that the holding pad 76 is positioned on the wafer 11 held on the chuck table 46, and the column 72 is lowered to place the holding pad 76 on the back surface (grinding surface) of the wafer 11. ) It is brought into contact with 11b.

  After the suction holding of the chuck table 46 is released, the outer peripheral portion of the wafer 11 is sucked and held by the annular suction holding portion 82 of the holding pad 76. Therefore, a space is formed by the circular recess 84 between the ground surface of the wafer 11 and the holding pad 76, and the wafer 11 is sucked and held by the holding pad 76 only at the outer peripheral portion thereof.

  Water is supplied from a supply hole 96 connected to the water source 100 into the circular concave portion 84, and the circular concave portion 84 that sucks and holds the wafer 11 is filled with water. As shown in FIG. The drainage 102 is discharged from the formed discharge portion 94.

  In this state, the column 72 is moved upward by a predetermined distance, the wafer 11 is lifted from the chuck table 46, and the arm 74 is further rotated so that the wafer 11 is sucked and held by the holding pad 76. The wafer 11 is conveyed to the table 68 and the suction of the annular suction holding portion 82 of the holding pad 76 is released.

  In the spinner cleaning unit 64, the wafer 11 is sucked and held by the spinner table 68, and the wafer 11 is cleaned while rotating the spinner table 68. When the cleaning of the wafer 11 is completed, the wafer 11 is spin-dried by the spinner cleaning unit 64, and then the wafer 11 is sucked and held by the hand 52 of the wafer transfer robot 54, and the wafer 11 is accommodated in a predetermined position of the second wafer cassette 62. To do.

  According to the wafer transport mechanism 62 of the above-described embodiment, since the outer peripheral portion of the wafer 11 after grinding is transported while being held by the annular suction holding portion 82, the wafer contact surface is less in contact with the wafer grinding surface. Since the wafer 11 is transported while always forming a layer of water on the ground surface, the ground surface of the wafer 11 is not dried, and contamination of the contaminated wafer ground surface by grinding debris and the like is thoroughly prevented. It can be conveyed from the chuck table 46 to the cleaning unit 64.

2 Grinding device 10 Rough grinding unit 11 Semiconductor wafer 23 Protective tape 28 Finish grinding unit 44 Turntable 46 Chuck table 62 Wafer transport mechanism (wafer carry-out mechanism)
64 Spinner cleaning unit 76 Holding pad 82 Annular suction holding part 84 Circular recess 86 Suction hole 94 Discharge part 96 Supply hole

Claims (1)

A wafer transfer mechanism for holding and transferring a wafer,
Arm,
A holding pad for sucking and holding a wafer supported by elastic support means at the tip of the arm;
The holding pad is configured to suck and hold the outer periphery of the wafer, a concave portion forming a space between the annular suction holding portion and the wafer held and sucked, and supply liquid to the concave portion. a liquid supply portion that, viewed contains a plurality of discharge portions formed in a groove shape to the sucking and holding portion of the annular discharging the liquid from the recess, and
The wafer discharge mechanism , wherein the plurality of discharge portions communicate the recess and the outside of the holding pad when holding the wafer.

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