JP2006344778A - Wafer transfer apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wafer transfer apparatus which can prevent damage to a wafer caused by the missing of particles of a substance constituting an attractor for attracting and holding the wafer. <P>SOLUTION: The attractor 100 constituting the wafer transfer apparatus 1 is porously formed by the solid-phase sintering of a silicon carbide particle. Since a binder is not used, the particle constituting the attractor 100 is not internally provided in an unstable state, and the particle does not give any damage to the wafer W caused by being chopped on the wafer W. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wafer transfer apparatus that sucks and transfers a wafer.

  A wafer on which a plurality of devices such as IC and LSI are formed on the front surface is ground on the back surface by a grinding device and formed extremely thin so as to have a thickness of, for example, 100 μm or less. Divided.

  In a grinding apparatus for grinding the back surface of a wafer, a wafer cassette for storing a wafer before grinding, a wafer cassette for storing a ground wafer, and a wafer before grinding taken out from the wafer cassette are temporarily placed. And a temporary table for positioning, a chuck table for holding the wafer during grinding, a cleaning unit for cleaning the ground wafer, and the like. And in order to convey a wafer between each, the grinding device is equipped with the wafer conveyance apparatus which adsorb | sucks and conveys a wafer. Also, the same wafer transfer device may be used when transferring the wafer after back grinding to the next step.

  Such a wafer transfer device is provided with a suction pad formed of porous ceramics and having a suction part for sucking the wafer, and the suction pad can suck and transfer the wafer by a suction force supplied from a suction source. (For example, refer to Patent Document 1).

JP 2004-91196 A

  However, the suction part constituting the suction pad is mainly made of alumina ceramics, mixed with silicon dioxide, titanium dioxide or the like as a binder, and sintered at a temperature of about 1200 ° C. to form a porous shape. Therefore, the alumina ceramic particles not in contact with the binder are encapsulated in an unstable state inside the sintered body. Therefore, there is a problem that when the wafer is transported, the alumina ceramic particles are dropped and dropped onto the wafer, and the wafer is damaged when the suction pad is pressed against the wafer. Such a problem may occur both when the wafer is transferred in the grinding apparatus and when the wafer is transferred between the grinding apparatus and another apparatus.

  In addition, when a die attach film is attached to the back side of the wafer and the back side where the die attach film is attached is sucked by the suction part, the suction part is used to smoothly remove the wafer from the suction part. In some cases, the pad is coated with polytetrafluoroethylene, but since the coating is performed at a high temperature of 400 ° C., the suction portion also becomes high. Therefore, the alumina ceramic particles that are unstablely bonded to the binder drop off, and the same problem as described above also occurs in this case.

  Therefore, the problem to be solved by the present invention is to prevent the wafer from being damaged by the dropping of the particles of the substance constituting the suction unit provided in the wafer transfer device.

  The present invention relates to a wafer transfer device including at least a suction pad that sucks and holds a wafer and a moving unit that supports and moves the suction pad, and the suction pad is porous by solid-phase sintering of silicon carbide particles. It is comprised from the suction part formed in this, and the frame body which surrounds a suction part.

  The adsorption pad may be coated with polytetrafluoroethylene.

  In this invention, since the suction part which comprises an adsorption pad is formed in the porous form by the solid-phase sintering of a silicon carbide particle, it is not necessary to use a binder. Therefore, since the silicon carbide particles constituting the suction portion are not included in an unstable state, the particles do not fall on the wafer and damage the wafer.

  Further, even when the suction part is heated to a high temperature when the suction pad is coated with polytetrafluoroethylene, the suction part is firmly solid-bonded, so that particles do not fall off.

  A wafer transfer apparatus 1 shown in FIG. 1 includes at least a suction pad 10 that sucks and holds a wafer, and a moving unit 11 that supports and moves the suction pad 10. The moving part 11 includes a shaft part 110 that can be moved up and down and an arm part 111 connected to the shaft part 110, and the arm part 111 moves up and down as the shaft part 110 moves up and down. It is the structure which turns with the rotation of. The suction pad 10 attached to the tip of the arm unit 111 is also moved up and down as the arm unit 111 is moved up and down, and swung as the arm unit 111 is turned.

  As shown in FIG. 2, the suction pad 10 includes a suction unit 100 that sucks and holds a wafer and a frame body 101 that surrounds the suction unit 100, and the suction unit 100 solid-phase sinters silicon carbide particles. As a result, a porous shape is formed. The suction unit 100 communicates with a suction source (not shown) via a flow path 112 that passes through the inside of the moving unit 11, and the wafer W is held by a suction force that acts on the suction unit 100. In addition, a spring 12 is interposed between the suction pad 10 and the moving part 11 so as to relieve an impact when holding the wafer W. In the illustrated example, the protective tape T is attached to the surface of the wafer W, and the suction unit 100 sucks and holds the back side of the wafer W.

The suction pad 10 can be manufactured by the following method, for example.
(1) Silicon carbide particles having a particle size of about 50 to 100 μm are granulated with polyvinyl alcohol or the like, and a disk corresponding to the suction part 100 is formed by solid phase sintering.
(2) The frame body 101 is formed by granulating silicon carbide particles having a particle diameter of 1 μm or less with polyvinyl alcohol or the like.
(3) A disk corresponding to the suction part 100 is fitted into the frame body 101 and combined.
(4) The combined disk and frame 101 are sintered at a high temperature of 2000 ° C. for 1 hour.

  In this way, the suction part 100 of the suction pad 10 is configured by solid-phase sintering of silicon carbide particles without using a binder, so that the particles are not included in an unstable state. Therefore, the particles do not fall on the wafer and damage the wafer.

  The suction pad 10 may be coated with polytetrafluoroethylene (PTFE) in order to smoothly remove the held wafer W. The PTFE coating is performed by baking at a high temperature of 400 ° C., but even at such a high temperature, the silicon carbide particles that are firmly solid-bonded do not fall off.

  The wafer transfer apparatus 1 configured as described above is mounted on, for example, a grinding apparatus 2 shown in FIG. The grinding device 2 is a device for grinding the back surface of a wafer, and chuck tables 20a, 20b, 20c, and 20d that hold the wafer, and first grinding means 21 that grinds the wafer held on the chuck table. And second grinding means 22.

  The grinding apparatus 2 includes a first cassette 23a that stores a wafer before grinding and a second cassette 23b that stores a ground wafer. In the vicinity of the first cassette 23a and the second cassette 23b, a loading / unloading unit having a function of unloading the wafer before grinding from the first cassette 23a and loading the ground wafer into the second cassette 23b. 24 is arranged. The carry-in / out means 24 has a configuration in which a holding portion 241 for holding the wafer is provided at the tip of the bendable arm portion 240, and the position of the wafer before grinding is aligned with the movable range of the holding portion 241. Positioning means 25 and cleaning means 26 for cleaning the ground wafer are provided.

  A first wafer transfer device 27a is disposed in the vicinity of the alignment means 25, and a second wafer transfer device 27b is disposed in the vicinity of the cleaning means 26. The first wafer transfer device 27a is the wafer transfer device 1 shown in FIGS. 1 and 2, and has a function of transferring the unground wafer placed on the alignment means 25 to one of the chuck tables. The second wafer transfer device 27b is also the wafer transfer device 1 shown in FIGS. 1 and 2, and has a function of transferring the ground wafer held on one of the chuck tables to the cleaning means 26.

  The chuck tables 20a, 20b, 20c, and 20d are supported so as to be able to rotate and revolve by the turntable 28, and any one of the chuck tables is rotated by the turntable 28 so that the first wafer transfer device 27a and the second wafer are rotated. It is positioned in the vicinity of the transport device 27b.

  The first grinding means 21 is provided at a spindle 210 having a vertical axis, a housing 211 that rotatably supports the spindle 210, a motor 212 connected to one end of the spindle 210, and the other end of the spindle 210. The wheel mount 213, the grinding wheel 214 mounted on the wheel mount 213, and the grindstone 215 fixed to the lower surface of the grinding wheel 214, the spindle 210 is rotated by the drive of the motor 212, and the grindstone 215 is accordingly accompanied. Is also configured to rotate. As the grindstone 215, for example, a grindstone for rough grinding is used.

  The first grinding means 21 can be moved in the vertical direction by the first grinding feed means 29. The first grinding feed means 29 is composed of a guide rail 290 arranged in a vertical direction, a lifting plate 291 slidably contacting the guide rail 290, and a motor 292 that lifts and lowers the lifting plate 291, and is driven by the motor 292. As the elevating plate 291 is guided by the guide rail 290 and moved up and down, the first grinding means 21 is also moved up and down.

  The second grinding means 22 is provided at a spindle 220 having a vertical axis, a housing 221 that rotatably supports the spindle 220, a motor 222 connected to one end of the spindle 220, and the other end of the spindle 220. The wheel mount 223, the grinding wheel 224 attached to the wheel mount 223, and the grindstone 225 fixed to the lower surface of the grinding wheel 224, and the spindle 220 is rotated by the drive of the motor 222, and the grindstone 225 is accordingly accompanied. Is also configured to rotate.

  The second grinding means 22 can be moved in the vertical direction by the first grinding feed means 30. The first grinding feed means 30 is composed of a guide rail 300 arranged in a vertical direction, a lifting plate 301 that is in sliding contact with the guide rail 30, and a motor 302 that lifts and lowers the descending plate 301. As the plate 301 is guided by the guide rail 300 and moves up and down, the second grinding means 22 is also moved up and down.

  As shown in FIG. 4, a protective tape T for device protection is attached to the surface of the wafer W housed in the first cassette 23a. On the surface W1 of the wafer W, a plurality of devices D partitioned into streets S provided vertically and horizontally are formed. The wafer W accommodated in the first cassette 23a is transferred to the alignment 25 by the loading / unloading means 24, and after the center of the wafer W is aligned at a fixed position, the chuck table is set by the first wafer transfer device 27a. It is conveyed to 20a. In the chuck table 20a, the surface side to which the protective tape T is stuck is held.

  Next, the turntable 28 rotates counterclockwise by a predetermined angle (90 degrees in the illustrated example), so that the chuck table 20 a is moved directly below the first grinding means 21. Then, the wafer W rotates with the rotation of the chuck table 20a, and the grinding wheel 215 rotates with the rotation of the spindle 210. And descend. Then, the rotating grindstone 215 contacts the back surface W2 of the wafer W, and the back surface W2 is roughly ground.

  When the rough grinding is finished in this way, the chuck table 20a is rotated counterclockwise by a predetermined angle, whereby the wafer W is positioned immediately below the second cutting means 22. Then, while the wafer W rotates with the rotation of the chuck table 20a and the grindstone 225 rotates with the rotation of the spindle 220, the second grinding means 22 feeds the grinding grinding downward by the second grinding feed means 30. And descend. Then, the rotating grindstone 225 contacts the back surface W2 of the wafer W, and the back surface W2 is finish-ground.

  When the finish grinding is completed, the turntable 28 rotates counterclockwise by a predetermined angle, whereby the chuck table 20a is positioned in the vicinity of the second wafer transfer device 27b. Then, the wafer W is held by the second wafer transfer device 27b and transferred to the cleaning means 26. In the cleaning means 26, the wafer W is held in a state where the back surface W2 is exposed on the holding table 260, the holding table 260 is rotated, and cleaning water is sprayed to remove grinding dust adhering to the back surface W2. After cleaning the wafer W, the loading / unloading means 24 unloads the wafer W from the cleaning means 26 and stores it in the second cassette 23b.

  As described above, in the grinding apparatus 2, the wafer transfer apparatus 1 shown in FIGS. 1 and 2 is used for the first wafer transfer apparatus 27 a and the second wafer transfer apparatus, Since part 100 is formed by solid phase sintering of silicon carbide particles, there is no need to use a binder, and there are no unstable particles. Therefore, the particles do not fall during transportation and damage the wafer.

  When the back surface of the wafer W ground by the grinding device 2 is etched, if the wafer transfer device 1 is disposed between the grinding device 2 and the etching device, the wafer W is transferred to the etching device without being damaged. can do. Further, the wafer transfer device 1 can be mounted on devices other than the grinding device.

It is a perspective view which shows an example of a wafer conveyance apparatus. It is sectional drawing which shows a part of the wafer conveyance apparatus. It is a perspective view which shows an example of a grinding device. It is a perspective view which shows a wafer and a protective tape.

Explanation of symbols

1: Wafer transfer device 10: Suction pad 100: Suction unit 101: Frame 11: Moving unit 110: Shaft unit 111: Arm unit 112: Channel 2: Grinding devices 20a, 20b, 20c, 20d: Chuck table 21: No. One grinding means 210: Spindle 211: Housing 212: Motor 213: Wheel mount 214: Grinding wheel 215: Grinding wheel 22: Second grinding means 220: Spindle 221: Housing 222: Motor 223: Wheel mount 224: Grinding wheel 225: Grinding wheel 23a: first cassette 23b: second cassette 24 carry-in / out means 240: arm part 241: holding part 25: alignment means 26: cleaning means 27a: first wafer conveyance device 27b: second wafer conveyance device 28: Turntable 29: First grinding Ri means 290: guide rail 291: elevating plate 292: motor 30: second grinding feed means 300: guide rail 301: elevating plate 302: motor

Claims (2)

A wafer transfer device comprising at least a suction pad for sucking and holding a wafer, and a moving unit that supports and moves the suction pad,
The suction pad is a wafer transfer device including a suction part formed in a porous shape by solid-phase sintering of silicon carbide particles and a frame body surrounding the suction part.   The wafer conveyance device according to claim 1, wherein the suction pad is coated with polytetrafluoroethylene.

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