JP5306928B2 - Wafer transfer device - Google Patents

Description

  The present invention relates to a wafer transfer device that sucks and holds a wafer such as a semiconductor wafer.

  In the semiconductor device manufacturing process, a plurality of regions are partitioned by dividing lines called streets arranged in a lattice pattern on the surface of a semiconductor wafer having a substantially disk shape, and devices such as ICs and LSIs are placed in the partitioned regions. Form. Then, the semiconductor wafer is cut into individual semiconductor chips (devices) by cutting the semiconductor wafer along a street with a cutting device.

  The wafer to be divided is formed to a predetermined thickness by grinding the back surface before cutting along the street.In recent years, in order to achieve weight reduction and downsizing of electrical equipment, the thickness of the wafer has been increased. It is required to be thin, for example, about 50 μm.

  Such thin wafers are difficult to handle and may be damaged during transportation. Therefore, there is disclosed a processing method in which only the back surface corresponding to the device region of the wafer is ground to form a circular recess, and an annular reinforcing portion is formed on the back surface of the wafer corresponding to the outer peripheral surplus region surrounding the device region. Proposed in the Gazette.

  When transporting a wafer processed in this way, it is not possible to use a holding pad that sucks the entire surface of the wafer as is normally used. For example, the entire circular recess that has been ground very thinly is sucked and held. Or a method of sucking and holding only a rigid annular reinforcing portion (for example, see Japanese Patent Application Laid-Open No. 2007-258206).

JP 2007-19461 A JP 2007-258206 A

  However, when sucking the entire surface of a circular recess that has been ground very thinly, if the wafer size changes and the diameter of the circular recess changes, the recess does not fill the holding pad, or conversely, the holding pad is smaller than the recess. If it is too much, there is a problem that the concave portion is bent and damaged even if it is sucked and held. Therefore, it is necessary to change the size of the holding pad each time.

  On the other hand, when sucking only the annular reinforcing portion formed on the outer periphery, the annular reinforcing portion has a very narrow width of 1 to 3 mm, so the area is small for suction and the suction force is insufficient. Furthermore, in order to cope with chipped shapes unique to the semiconductor wafer such as notches and orientation flats formed on the outer periphery of the wafer, it is necessary to make a holding pad in which a non-suction area is formed in which the corresponding part is not sucked. In addition, it is necessary to align the non-suction region of the holding pad with the notch or orientation flat of the semiconductor wafer.

  The present invention has been made in view of such a point, and an object of the present invention is to provide a plurality of wafers having a circular recess corresponding to a device region and an annular reinforcing portion surrounding the circular recess. It is an object of the present invention to provide a wafer conveyance device having a holding pad that can accommodate the wafer size.

  According to the present invention, a device region in which a plurality of devices are formed and an outer peripheral surplus region surrounding the device region are formed on the surface, and a circular recess is formed on the back surface corresponding to the device region. A wafer transport device for sucking and holding a wafer having an annular reinforcing portion including the surplus area formed on the side thereof, wherein the wafer has a suction surface for sucking and holding the bottom surface of the circular recess and surrounds the suction surface. A substantially disc-shaped holding pad having an annular recess for accommodating the annular reinforcing portion, suction means for applying a negative pressure to the suction surface, and moving the holding pad between the first position and the second position And a plurality of concentric circular recesses corresponding to the diameter of the wafer.

  Preferably, the holding pad further includes an annular suction surface formed between a plurality of concentric annular recesses. The annular suction surface is selectively communicated with suction means.

  According to the present invention, the annular reinforcing portion of the wafer is inserted into the annular recess of the holding pad, and the entire surface of the circular recess corresponding to the device area of the wafer is sucked and held by the suction surface of the holding pad. Can be aspirated. Furthermore, since one holding pad has a concentric annular recess corresponding to a plurality of wafer sizes, it is not necessary to change the holding pad each time the wafer size is changed. Is possible.

  Further, in the form having an annular suction surface formed between a plurality of annular recesses, when sucking and holding a wafer having a large diameter, negative pressure is simultaneously applied to both the suction surface and the annular suction surface. The wafer can be sufficiently sucked and held.

It is a surface side perspective view of a semiconductor wafer. It is a back surface side perspective view of the semiconductor wafer by which the protective tape was stuck on the surface. It is an external appearance perspective view of the grinding device provided with the wafer conveyance device of the present invention. It is a perspective view which shows the relationship between the wafer hold | maintained at the chuck table at the time of grinding, and a grinding wheel. It is explanatory drawing of the circular recessed part grinding process implemented by the grinding device. It is sectional drawing of the semiconductor wafer in which the circular recessed part grinding process was implemented. 1 is a schematic perspective view of a wafer conveyance device according to an embodiment of the present invention. It is a bottom view of a holding pad. FIG. 9 is a sectional view taken along line 9-9 in FIG. 8. It is a longitudinal cross-sectional view of a state in which a semiconductor wafer is sucked and held from above a chuck table by a holding pad.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view of a semiconductor wafer before being processed to a predetermined thickness. A 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 13 are formed in a lattice shape on the surface 11a, and a plurality of streets partitioned by the plurality of streets 13 are formed. A device 15 such as an IC or LSI is formed in the region.

  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.

  A protective tape 23 is attached to the 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.

  Referring to FIG. 3, an external perspective view of the grinding device 2 is shown. The grinding apparatus 2 performs a grinding method in which a back surface corresponding to the device region 17 of the semiconductor wafer 11 is ground to form a circular recess, and an annular reinforcing portion including an outer peripheral surplus region 19 is formed on the outer peripheral side of the circular recess. Suitable for

  Reference numeral 4 denotes a base of the grinding apparatus 2, and a column 6 is erected on the rear side of the base 4. A pair of guide rails (only one is shown) 8 extending in the vertical direction is fixed to the column 6.

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

  The grinding unit 10 includes a housing 20, a spindle 25 rotatably accommodated in the housing 20, a servo motor 22 that rotationally drives the spindle 25, a mount 27 fixed to the tip of the spindle 25, and a detachable attachment to the mount 27. A grinding wheel 24 having a plurality of grinding wheels 26 that are fixedly secured is included.

  The grinding unit 10 includes a grinding unit moving mechanism 18 including a ball screw 14 and a pulse motor 16 that move the 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 chuck table mechanism 28 having a chuck table 50 is disposed at an intermediate portion of the base 4, and the chuck table mechanism 28 is moved in the Y-axis direction by a chuck table moving mechanism (not shown). A bellows 30 covers the chuck table mechanism 28.

  In the front portion of the base 4, a first wafer cassette 32, a second wafer cassette 34, a wafer transfer robot 36, a positioning mechanism 38 having a plurality of positioning pins 40, and a wafer carry-in mechanism (loading arm) 42 are provided. Also, a wafer carry-out mechanism (unloading arm) 44 and a spinner unit 46 are provided.

  Further, a cleaning water spray nozzle 48 for cleaning the chuck table 50 is provided at the approximate center of the base 4. The cleaning water spray nozzle 48 sprays cleaning water toward the chuck table 50 in a state where the chuck table 50 is positioned in the wafer loading / unloading area on the front side of the apparatus.

  The grinding operation of the grinding device 2 configured as described above will be described below. The semiconductor wafer 11 as shown in FIG. 2 accommodated in the first wafer cassette 32 is transported to the positioning mechanism 38 by the wafer transport robot 36 and positioned by the positioning pins 40.

  The positioned wafer 11 is sucked and held by the loading arm 42, conveyed to the chuck table 50 positioned in the wafer carry-in / out area, and sucked and held by the chuck table 50.

  The wafer 11 sucked and held on the chuck table 50 is moved in the Y-axis direction to a grinding region immediately below the grinding unit 10 by a chuck table moving mechanism (not shown). As shown in FIG. 4, the grinding wheel 24 detachably attached to the mount 27 with a bolt 29 grinds only the back surface corresponding to the device region 17 of the wafer 11 and surrounds the device region 17 with an outer peripheral surplus region 19. This grinding wheel is suitable for forming an annular reinforcing portion on the back surface of the wafer corresponding to the above.

  As best shown in FIG. 5, the rotation center P1 of the chuck table 50 and the rotation center P2 of the grinding wheel 24 are eccentric, and the outer diameter of the grinding wheel 26 is the device region 17 of the wafer 11 and the outer peripheral surplus region 19. Is set to be smaller than the diameter of the boundary line 52 and larger than the radius of the boundary line 52 so that the annular grinding wheel 26 passes through the rotation center P <b> 1 of the chuck table 50.

  While rotating the chuck table 50 in the direction indicated by the arrow a at 300 rpm and rotating the grinding wheel 24 in the direction indicated by the arrow b at 6000 rpm, the grinding feed mechanism 18 is operated to move the grinding wheel 26 of the grinding wheel 24 to the wafer 11. Make contact with the back of the. Then, the grinding wheel 24 is ground by a predetermined amount at a predetermined grinding feed speed.

  As a result, as shown in FIG. 6, the region corresponding to the device region 17 is ground to form a circular recess 31 and the region corresponding to the outer peripheral surplus region 19 remains on the back surface of the semiconductor wafer 11. An annular reinforcing portion 33 is formed.

  After the grinding, the wafer 11 is sucked and held by the unloading arm 44 after the chuck table 50 is moved to the carry-in / carry-out region, and is conveyed to the spinner unit 46. The wafer 11 that has been cleaned and spin-dried by the spinner unit 46 is gripped by the wafer transfer robot 36 and accommodated in the second wafer cassette 34.

  Hereinafter, an example in which the wafer conveyance device of the present invention is applied to the wafer carry-out mechanism 44 will be described in detail with reference to FIGS. The wafer unloading mechanism (unloading arm) 44 includes a holding pad 54 and an arm 56 that supports the holding pad 54 with a connecting portion 66 (see FIG. 9).

  The arm 56 is swung between the chuck table 50 and the spinner unit 46 shown in FIG. A coil spring 70 is interposed between the distal end portion of the arm 56 and the frame body 58 of the holding pad 54, so that the holding pad 54 is tiltably attached to the distal end of the arm 56.

  8 shows a bottom view of the holding pad 54, and FIG. 9 is a sectional view taken along line 9-9 of FIG. A frame 58 of the holding pad 54 is formed with a circular suction surface 60 that sucks the circular recess 31 of the semiconductor wafer 11 and an annular suction surface 62 that surrounds the circular suction surface 60.

  An annular recess 76 is formed between the circular suction surface 60 and the annular suction surface 62, and an annular recess 78 is formed between the annular suction surface 62 and the outer periphery of the frame body 54. The circular suction surface 60 and the annular suction surface 62 are made of a porous material such as porous ceramics, a resin in which a plurality of suction holes are formed, or the like.

  The circular suction surface 60 is connected to a vacuum suction source 80 via a plurality of concentric suction paths 64, a suction path 68 formed in the connecting portion 66, and a flexible pipe 82. An electromagnetic switching valve 84 is inserted in the middle of the flexible pipe 82, and the circular suction surface 60 is selectively communicated with the vacuum suction source 80 by switching the electromagnetic switching valve 84.

  The annular suction surface 62 is connected to the vacuum suction source 80 via an annular suction path 73, a suction path 74 in the connection pipe 72 and a flexible pipe 86. An electromagnetic switching valve 88 is inserted in the middle of the flexible pipe 86, and the annular suction surface 62 is selectively communicated with the vacuum suction source 80 by switching the electromagnetic switching valve 88.

  Referring to FIG. 10, a sectional view of the holding pad 54 in a state where the semiconductor wafer 11 on the chuck table 50 is sucked and held by the holding pad 54 is shown. The annular reinforcing portion 33 of the semiconductor wafer 11 is inserted into the annular recess 76, and the circular recess 31 of the wafer 11 is sucked and held by the circular suction surface 60.

  At this time, the electromagnetic switching valve 84 is switched to the connection position, and the circular suction surface 60 is communicated with the vacuum suction source 80. On the other hand, the electromagnetic switching valve 88 is switched to the shut-off position, so that no suction force acts on the annular suction surface 62.

  The semiconductor wafer 11 is, for example, an 8-inch wafer. In this case, the annular reinforcing portion 33 of the wafer 11 is inserted into the inner annular recess 76 as shown in FIG. 10, and the circular recess 31 of the wafer 11 is formed into a circular suction surface. 60 is held by suction.

  For example, in the case of a large-diameter wafer such as a 10-inch wafer, the annular reinforcing portion 33 of the wafer 11 is inserted into the outer circular recess 78, and both the electromagnetic switching valves 84 and 88 are switched to the connected state. 11 circular recesses 31 are sucked and held by the circular suction surface 60 and the annular suction surface 62.

  According to the wafer conveyance device of the above-described embodiment, since the holding pad 54 has the annular recesses 76 and 78 on the bottom surface, the annular reinforcing portion 33 of the wafer 11 is inserted into any of the annular recesses 76 and 78. Since the circular recess 31 of the wafer 11 is sucked and held by the circular suction surface 60, the wafer 11 can be sucked and held with a sufficient suction force.

  Further, since concentric annular recesses 76 and 78 corresponding to a plurality of wafer sizes are formed in the holding pad 54, it is not necessary to change the holding pad each time the wafer size is changed. Can be reduced.

  Further, since the annular suction surface 62 between the annular recesses 76 and 78 can be selectively communicated with the vacuum suction source 80, when sucking a wafer having a large diameter, it is negative over almost the entire area of the circular recess 31 of the wafer 11. When the wafer 11 can be sufficiently sucked by applying pressure, and the annular suction surface 62 exists outside the wafer 11 having a small diameter and held by suction, the electromagnetic switching valve 88 is shut off. By switching, foreign matters such as cutting dust do not adhere to the annular suction surface 62.

2 Grinding apparatus 10 Grinding unit 11 Semiconductor wafer 17 Device area 19 Peripheral surplus area 24 Grinding wheel 26 Grinding wheel 31 Circular recess 33 Annular reinforcing part 44 Unloading mechanism (unloading arm)
54 holding pad 60 circular suction surface 62 annular suction surfaces 76, 78 annular recess 80 vacuum suction source

Claims (2)

The device has a device region where a plurality of devices are formed and an outer peripheral surplus region surrounding the device region, a circular recess is formed on the back surface corresponding to the device region, and the surplus region is formed on the outer periphery of the circular recess. A wafer transfer device for sucking and holding a wafer formed with an annular reinforcing portion including:
A substantially disc-shaped holding pad having a suction surface that sucks and holds the bottom surface of the circular recess, and an annular recess that surrounds the suction surface and accommodates the annular reinforcing portion of the wafer;
Suction means for applying a negative pressure to the suction surface;
Moving means for moving the holding pad between a first position and a second position;
A wafer conveyance device, wherein a plurality of the annular recesses are provided concentrically corresponding to the diameter of the wafer. Further comprising an annular suction surface formed between the annular recesses provided in a plurality of concentric circles,
2. The wafer conveyance device according to claim 1, wherein the annular suction surface is selectively communicated with the suction means.

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