JP4634949B2 - Wafer holding pad - Google Patents

Description

  The present invention relates to a wafer holding pad for sucking and holding 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 substantially wafer-shaped semiconductor wafer, and devices such as ICs, LSIs, etc. are partitioned in the partitioned regions. Form. Then, the semiconductor wafer is cut along the streets to divide the region in which the device is formed to manufacture individual semiconductor chips. In addition, optical device wafers with gallium nitride compound semiconductors laminated on the surface of a sapphire substrate are also divided into individual optical devices such as light emitting diodes and laser diodes by cutting along the streets, and are widely used in electrical equipment. ing.

As described above, the wafer to be divided is formed to have a predetermined thickness by grinding or etching the back surface before cutting along the street. In recent years, it has been required to form a wafer with a thickness of 50 μm or less in order to reduce the weight and size of electrical equipment.
However, if the thickness of the wafer is formed to be 50 μm or less, the wafer tends to be damaged, and there is a problem that handling such as transport of the wafer becomes difficult.

  In order to solve the above-mentioned problem, the present applicant grinds the region corresponding to the device region on the back surface of the wafer to form the thickness of the device region to a predetermined thickness, and leaves the outer peripheral portion on the back surface of the wafer. Japanese Patent Application No. 2005-165395 has proposed a method of processing a wafer capable of forming a rigid wafer by forming an annular reinforcing portion.

  As described above, in order to transport a wafer formed to have a predetermined thickness, a full-surface suction pad that sucks and holds the entire surface of the wafer is generally used. However, if the wafer having the annular reinforcing portion provided on the outer peripheral portion and having the concave portion formed thereon is sucked and held by the entire suction pad, there is a problem that the thinly formed device region is bent and damaged.

  The present invention has been made in view of the above-mentioned facts, and the main technical problem thereof is that even a wafer in which an annular reinforcing portion is provided on the outer peripheral portion and a concave portion is formed can be sucked and held without being damaged. An object of the present invention is to provide a wafer holding pad that can be used.

In order to solve the main technical problem described above, according to the present invention, there is provided a wafer holding pad for holding a wafer having a device region having a plurality of devices formed on a surface and an outer peripheral surplus region surrounding the device region. And
A holding part having an annular suction holding surface corresponding to the outer peripheral surplus area and having a suction hole opened in the suction holding surface; and a support part for supporting the holding part.
A plurality of the holding portions having the annular holding surface are provided concentrically corresponding to the diameter of the wafer,
The support portion is formed with an air opening hole that opens the inside of the holding portion having the annular holding surface to the atmosphere.
A wafer holding pad is provided.

The suction hole includes a communication groove formed along the annular suction holding surface.
Further, in the peripheral marginal area of the wafer and a mark indicating the crystal orientation of the wafer is formed, the communication Tsumizo is preferably formed except the area where the mark is formed.

  According to the present invention, a wafer holding pad for holding a wafer having a device region and an outer peripheral surplus region surrounding the device region includes an annular suction holding surface corresponding to the outer peripheral surplus region. Since the suction hole is provided with a holding part, only the outer peripheral surplus area of the wafer is sucked and held by the annular suction holding surface, so that no negative pressure acts on the device area. Even a wafer in which a portion is provided and a recess is formed in the device region can be sucked and held without damaging the device region.

Hereinafter, preferred embodiments of a wafer holding pad according to the present invention will be described in more detail with reference to the accompanying drawings.
First, a method of processing a wafer provided with a device region in which a plurality of devices are formed on a surface sucked and held by a wafer holding pad according to the present invention and an outer peripheral surplus region surrounding the device region will be described.
FIG. 1 shows a perspective view of a semiconductor wafer as a wafer before being processed to a predetermined thickness. A semiconductor wafer 10 shown in FIG. 1 is made of, for example, a silicon wafer having a thickness of 700 μm, and a plurality of streets 101 are formed in a lattice shape on the surface 10a, and a plurality of streets partitioned by the plurality of streets 101 are provided. A device 102 such as an IC or LSI is formed in the region. The semiconductor wafer 10 configured as described above includes a device region 104 in which the device 102 is formed and an outer peripheral surplus region 105 surrounding the device region 104. Further, a notch 106 is formed on the outer periphery of the semiconductor wafer 10 shown in FIG. 1 as a mark indicating the crystal orientation of the silicon wafer. In addition, as a mark indicating the crystal orientation of the silicon wafer, there is an orientation flat mark.

  As shown in FIG. 2, the protective member 11 is stuck on the surface 10a of the semiconductor wafer 10 configured as described above (protective member sticking step). Therefore, the back surface 10b of the semiconductor wafer 10 is exposed.

  When the protective member attaching step is performed, the region corresponding to the device region 104 on the back surface 10b of the semiconductor wafer 10 is ground to form the device region 104 to a predetermined thickness, and the back surface 10b of the semiconductor wafer 10 is formed. The reinforcement part formation process which leaves the area | region corresponding to the outer periphery surplus area | region 105 in and forms an annular | circular reinforcement part is implemented. This reinforcement part formation process is implemented by the grinding apparatus shown in FIG.

  The grinding device 2 shown in FIG. 3 includes a device housing 20 having a substantially rectangular parallelepiped shape. A stationary support plate 21 is erected on the upper right end of the device housing 20 in FIG. On the inner side surface of the stationary support plate 21, a pair of guide rails 22 and 22 extending in the vertical direction are provided. A pair of guide rails 22 and 22 is mounted with a grinding unit 3 as grinding means so as to be movable in the vertical direction.

  The grinding unit 3 includes a unit housing 31, a grinding wheel 33 fastened by a fastening bolt 334 to a wheel mount 32 rotatably attached to the lower end of the unit housing 31, and an upper end of the unit housing 31. An electric motor 34 that rotates the wheel mount 32 in the direction indicated by the arrow 32a, an attachment member 35 to which the unit housing 31 is attached, and a moving base 36 to which the attachment member 35 is attached are provided. The grinding wheel 33 includes a disk-shaped base 331 and an annular grinding wheel 332 mounted on the lower surface of the base 331, and the base 331 is attached to the wheel mount 32 by a plurality of fastening bolts 334. It has been.

  The grinding unit 3 in the illustrated embodiment moves the moving base 36 along the pair of guide rails 22 and 22 to move the grinding wheel 33 in a direction perpendicular to the holding surface of the chuck table described later. It has. The vertical moving means 37 includes a male screw rod 371 that is disposed on the stationary support plate 21 in parallel with the pair of guide rails 22 and 22 and is rotatably supported, and a pulse for rotationally driving the male screw rod 371. A motor 372 and a female screw block (not shown) mounted on the moving base 36 and screwed with the male screw rod 371 are provided. By driving the male screw rod 371 forward and reversely by the pulse motor 372, the grinding unit 3 is It is moved in the vertical direction (direction perpendicular to the holding surface of the chuck table described later).

  The grinding device 2 in the illustrated embodiment includes a turntable 4 disposed so as to be substantially flush with the upper surface of the device housing 20 on the front side of the stationary support plate 21. The turntable 4 is formed in a relatively large-diameter disk shape, and is appropriately rotated in a direction indicated by an arrow 4a by a rotation driving mechanism (not shown). In the illustrated embodiment, two chuck tables 5 are disposed on the turntable 4 so as to be rotatable in a horizontal plane with a phase angle of 180 degrees. The chuck table 5 includes a disk-shaped base 51 and a suction holding chuck 52 formed in a disk shape by a porous ceramic material, and a workpiece placed on the suction holding chuck 52 (holding surface). Suction is held by operating a suction means (not shown). The chuck table 5 configured as described above is rotated in a direction indicated by an arrow 5a by a rotation driving mechanism (not shown) as shown in FIG. The two chuck tables 5 arranged on the turntable 4 are sequentially moved to the workpiece loading / unloading area A, the grinding area B and the workpiece loading / unloading area A as the turntable 4 rotates appropriately. I'm damned. The grinding device 2 in the illustrated embodiment includes wafer transport means 6 that unloads a semiconductor wafer 10 held on the chuck table 5 and subjected to grinding processing described later from the chuck table 5. The wafer transfer means 6 will be described in detail later.

  In order to carry out the reinforcing portion forming step using the grinding device 2 described above, the above-mentioned wafer transporting means (not shown) transported to the upper surface (holding surface) of the chuck table 5 positioned in the workpiece transporting / unloading area A. The protective member 11 side of the semiconductor wafer 10 is placed, and the semiconductor wafer 10 is sucked and held on the chuck table 5. Next, the turntable 4 is rotated 180 degrees in the direction indicated by the arrow 4a by a rotation drive mechanism (not shown), and the chuck table 5 on which the semiconductor wafer 10 is placed is positioned in the grinding region B. Here, the relationship between the semiconductor wafer 10 held on the chuck table 5 and the annular grinding wheel 332 constituting the grinding wheel 33 will be described with reference to FIG. The rotation center P 1 of the chuck table 5 and the rotation center P 2 of the annular grinding wheel 332 are eccentric, and the outer diameter of the annular grinding wheel 332 is a boundary line 106 between the device region 104 and the surplus region 105 of the semiconductor wafer 10. The annular grinding wheel 332 passes through the rotation center P1 of the chuck table 5 (the center of the semiconductor wafer 10).

  Next, as shown in FIGS. 3 and 4, while rotating the chuck table 5 in the direction indicated by the arrow 5a at 300 rpm and rotating the grinding wheel 332 in the direction indicated by the arrow 32a at 6000 rpm, the vertical movement means 37 is operated. Then, the grinding wheel 33, that is, the grinding wheel 332 is brought into contact with the back surface of the semiconductor wafer 10. Then, the grinding wheel 33, that is, the grinding wheel 332 is ground and fed downward by a predetermined amount at a predetermined grinding feed speed. As a result, on the back surface of the semiconductor wafer 10, a region corresponding to the device region 104 is ground and removed to form a circular recess 104b having a predetermined thickness (for example, 30 μm) as shown in FIG. A region corresponding to the region 105 is left and formed in the annular reinforcing portion 105b.

  If the reinforcement part formation process mentioned above was implemented, the turntable 4 was rotated 180 degree | times to the direction shown by the arrow 4a with the rotation drive mechanism which is not shown in figure, and the semiconductor wafer 10 in which the reinforcement part formation process was implemented was mounted. The chuck table 5 is positioned in the workpiece loading / unloading area A. The semiconductor wafer 10 subjected to the reinforcing portion forming step held by the chuck table 5 positioned in the workpiece loading / unloading area A is sucked and held by the holding pad 7 of the wafer transfer means 6 and transferred to the next step. .

Here, the wafer conveyance means 6 will be described with reference to FIGS.
6 to 8 includes a holding pad 7 configured according to the present invention and an operating arm 8 for supporting the holding pad 7. The base end of the operating arm 8 is shown in FIG. As shown in FIG. The rotating shaft 9 is rotated by a rotation driving means (not shown) and moved up and down by a moving means (not shown).

  As shown in FIGS. 7 and 8, the holding pad 7 includes a first annular holding portion 71 corresponding to the outer peripheral surplus region 105 of the semiconductor wafer 10, that is, the annular reinforcing portion 105b, and the first annular holding portion. A second annular holding portion 72 disposed concentrically on the radially outer side of 71, and a circular support portion 73 that supports the first annular holding portion 71 and the second annular holding portion 72; It is made up of. The first annular holding portion 71 includes an annular suction holding surface 711 corresponding to the outer peripheral surplus region 105 of the semiconductor wafer 10, that is, the annular reinforcing portion 105 b. The first annular holding portion 71 is provided with a suction hole 712 that opens to the annular suction holding surface 711. The suction hole 712 is a continuous groove formed along the annular suction holding surface 711 and is formed except for a region 711 a corresponding to the notch 106 as a mark indicating the crystal orientation of the semiconductor wafer 10. . A suction passage 713 communicates with the suction hole 712 formed in this way. The second annular holding portion 72 is formed in a size corresponding to a wafer having a diameter larger than that of the semiconductor wafer 10, and similarly to the first annular holding portion 71, an annular suction holding surface 721, A suction hole 722 opening in the annular suction holding surface 721 and a suction passage 723 are provided. In the first annular holding portion 71 and the second annular holding portion 72 configured as described above, the suction passage 713 and the suction passage 723 are respectively connected to the suction means 74 as shown in FIG.

  The suction means 74 includes a suction source 741, a first flexible pipe 742 and a second flexible pipe 743 that communicate the suction source 741 with the suction passage 713 and the suction passage 723, the first flexible pipe 742, It consists of a first electromagnetic on-off valve 744 and a second electromagnetic on-off valve 745 disposed on the second flexible pipe 743, respectively. The suction means 74 configured in this manner applies a negative pressure to the suction hole 712 from the suction source 741 via the first flexible pipe 742 and the suction passage 713 when the first electromagnetic on-off valve 744 is turned on and opened. Let me. When the second electromagnetic opening / closing valve 745 is turned ON to open the circuit, a negative pressure is applied to the suction hole 722 from the suction source 741 through the second flexible pipe 743 and the suction passage 723.

  In the illustrated embodiment, the circular support portion 73 is integrally formed with the first annular holding portion 71 and the second annular holding portion 72 by an appropriate synthetic resin, and the first annular The holding portion 71 and the second annular holding portion 72 are connected to the suction holding surface 711 and the surface opposite to the suction holding surface 721. The circular support portion 73 formed in this way has a plurality of atmosphere opening holes 731 and 732 that open the inside of the first annular holding portion 71 and the inside of the second annular holding portion 72 to the atmosphere, respectively. Is formed. Further, a support shaft portion 733 protrudes from the central portion of the upper surface of the support portion 73, and this support shaft portion 733 is attached to the distal end portion of the operating arm. A locking portion 733 a is provided at the upper end of the support shaft portion 733, and this locking portion 733 a is engaged with an engagement portion 81 formed on the operating arm 8. A compression coil spring 82 is disposed between the upper surface of the support portion 73 and the operating arm 8, and biases the support portion 73 downward in FIG.

The wafer transport means 6 in the illustrated embodiment is configured as described above, and the operation thereof will be described below.
The wafer transfer means 6 rotates the rotation shaft 9 by a predetermined angle from the state shown in FIG. 3 by a rotation drive mechanism (not shown), and the holding pad 7 attached to the tip of the operating arm 8 is loaded into and unloaded from the workpiece A It moves above the semiconductor wafer 10 held by the chuck table 5 positioned at the position. Next, the rotating shaft 9 is moved downward by a moving means (not shown), whereby the annular suction holding surface 711 of the first annular holding portion 71 of the holding pad 7 is moved to the semiconductor wafer 10 as shown in FIG. The outer peripheral surplus region 105 is placed on the upper surface of the annular reinforcing portion 105b. At this time, the region 711 a where the suction hole 712 is not formed in the annular suction holding surface 711 is set so as to be positioned at a position corresponding to the notch 106 as a mark indicating the crystal orientation of the semiconductor wafer 10. Then, the suction holding of the semiconductor wafer 10 by the chuck table 5 is released, and the first electromagnetic on-off valve 744 of the suction means 74 is turned on to open the circuit. As a result, a negative pressure acts on the annular suction holding surface 711 of the first annular holding portion 71 from the suction source 741 through the first flexible pipe 742, the suction passage 713, and the suction hole 712. The outer peripheral surplus region 105 of the semiconductor wafer 10, that is, the upper surface of the annular reinforcing portion 105 b is sucked and held by the suction holding surface 711.

  In this way, the holding pad 7 sucks and holds only the outer peripheral surplus region 105 of the semiconductor wafer 10, that is, the annular reinforcing portion 105 b, by the annular suction holding surface 711, so that no negative pressure acts on the device region 104. The formed device region 104 is not bent and damaged by the negative pressure. Further, the negative pressure acting on the suction holding surface 711 of the first annular holding portion 71 may leak and act on the first annular holding portion 71, but the supporting portion 73 constituting the holding pad 7 may Since the air release hole 731 is provided, the inside of the first annular holding portion 71 does not become negative pressure. Therefore, it is possible to prevent damage due to the device region 104 formed thinly of the semiconductor wafer 10 being bent by negative pressure. In the illustrated embodiment, the region 711 a where the suction hole 712 is not formed in the annular suction holding surface 711 of the holding pad 7 is positioned at a position corresponding to the notch 106 as a mark indicating the crystal orientation of the semiconductor wafer 10. Therefore, the negative pressure does not leak through the notch 106. In the illustrated embodiment, since the holding pad 7 includes the first annular holding portion 71 and the second annular holding portion 72, it can correspond to two types of wafers having different diameters.

  Although the example in which the wafer holding pad according to the present invention is applied to the conveying means of the grinding apparatus has been described above, the wafer holding pad according to the present invention is also applied to the conveying means for conveying the wafer between other processing apparatuses and processing apparatuses. be able to.

The perspective view which shows the semiconductor wafer before the grinding process in the wafer hold | maintained by the holding pad of the wafer by this invention The perspective view which shows the state which affixed the protection member on the surface of the semiconductor wafer shown in FIG. The perspective view of the grinding device for grinding the back surface of the semiconductor wafer shown in FIG. Explanatory drawing of the reinforcement part formation process which grinds the back surface of a semiconductor wafer with the grinding apparatus shown in FIG. Sectional drawing of the semiconductor wafer in which the reinforcement part formation process shown in FIG. 5 was implemented. The perspective view which expands and shows the principal part of the wafer conveyance means with which the grinding apparatus shown in FIG. 3 is equipped. The bottom view of the holding pad of the wafer comprised according to this invention which comprises the wafer conveyance means shown in FIG. AA sectional view taken on the line in FIG. Sectional drawing which shows the state which hold | maintained the semiconductor wafer with the holding pad of the wafer comprised according to this invention.

Explanation of symbols

2: grinding device 20: device housing 3: grinding unit 31: unit housing 32: wheel mount 33: grinding wheel 332: annular grinding wheel 4: turntable 5: chuck table 6: wafer transport means 7: holding pad 71: first 1 annular holding portion 711: annular suction holding surface 712: suction hole 713: suction passage 72: second annular holding portion 721: annular suction holding surface 722: suction hole 723: suction passage 74: suction means 741 : Suction source 742: first flexible pipe 743: second flexible pipe 744: first electromagnetic on-off valve 745: second electromagnetic on-off valve 8: operating arm 9: rotating shaft 10: semiconductor wafer 101: street 102 : Device 104: device region 105: surplus region 104b: circular recess 105b: annular reinforcing portion

Claims (3)

A wafer holding pad for holding a wafer comprising a device region having a plurality of devices formed on a surface and an outer peripheral surplus region surrounding the device region,
A holding part having an annular suction holding surface corresponding to the outer peripheral surplus area and having a suction hole opened in the suction holding surface; and a support part for supporting the holding part.
A plurality of the holding portions having the annular holding surface are provided concentrically corresponding to the diameter of the wafer,
The support portion is formed with an air opening hole that opens the inside of the holding portion having the annular holding surface to the atmosphere.
A wafer holding pad.   The wafer holding pad according to claim 1, wherein the suction hole includes a communication groove formed along the annular suction holding surface.   3. The wafer holding device according to claim 1, wherein a mark indicating a crystal orientation of the wafer is formed in a surplus area of the wafer, and the communication groove is formed excluding the area where the mark is formed. pad.

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