JP2013098248A - Holding table - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a holding table capable of suppressing cost more than before even in the case of holding a plurality of holding tables in accordance with the depth of a circular concave part of a wafer and improving workability that occurs during exchanging the holding tables.SOLUTION: A holding table 2 holding a wafer having a circular concave part formed on a rear face and an annular reinforcement part for surrounding the circular concave part includes: a hat-shaped base 4 which has a cylindrical rising part 12 with a concave part holding part 10 for being fitted into the circular concave part to hold the circular concave part formed on an upper edge, and a spacer support part 8 for surrounding the circumference of the cylindrical rising part and whose one end communicates with the concave part holding part 10 and the other end has a first suction path; and an annular spacer 6 mounted detachably on the spacer support part 8 of the hat-shaped base 4 to have an opening into which the cylindrical rising part 12 is fitted. The thickness of the annular spacer 6 is set on the basis of a value obtained by subtracting the depth of the circular concave part of the wafer from the thickness of the cylindrical rising part 12 of the hat-shaped base 4.

Description

  The present invention relates to a holding table that holds a wafer having a circular recess formed on the back surface and an annular reinforcing portion surrounding the circular recess in a state where the surface is exposed.

  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 or polishing the back surface before cutting along the street. In recent years, in order to achieve a reduction in weight and size of electrical equipment, it has been required to make the wafer thinner, for example, about 50 μm.

  Such thin wafers are difficult to handle and may be damaged during transportation. Accordingly, there is disclosed a grinding 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 surrounding the circular recess is formed on the back surface of the wafer corresponding to the outer peripheral surplus region. Proposed in the Gazette.

  In order to remove the annular reinforcing portion by cutting the boundary between the annular reinforcing portion and the circular concave portion with a cutting blade after dicing the wafer and dividing the wafer into individual devices after the grinding, It is necessary to hold the wafer on the back surface with a holding table (chuck table). The same applies to the case where the wafer is held by the holding table without removing the annular reinforcing portion and is diced.

  The same applies to the case where the wafer is held by the spinner table of the spinner cleaning apparatus after the dicing is completed, and Japanese Patent Application Laid-Open No. 2010-16146 discloses a hat-shaped holding table that holds a wafer having a circular concave portion and an annular reinforcing portion without damaging the wafer. Is disclosed.

JP 2007-19461 A JP 2010-16146 A

  In the hat-shaped holding table as disclosed in Patent Document 2, it is necessary to set the height of the convex portion of the holding table in accordance with the depth of the circular concave portion of the wafer in order to avoid breakage of the wafer.

  That is, it is necessary to have a plurality of types of holding tables according to the depth of the circular concave portion of the wafer, which is expensive, and the holding table has to be changed according to the depth of the circular concave portion of the wafer. There is a problem that is bad.

  In particular, when the holding table of the cutting device is replaced, the workpiece holding surface height of the holding table with respect to the cutting blade changes, so it is necessary to re-examine the origin of the cutting blade with respect to a new holding table. The work becomes complicated.

  The present invention has been made in view of the above points, and the object of the present invention is to reduce the cost compared to the conventional case even when a plurality of holding tables are held according to the depth of the circular concave portion of the wafer. A further object is to provide a holding table capable of improving the poor workability caused by exchanging the holding table in accordance with the depth of the circular concave portion of the wafer.

  According to the present invention, there is provided a holding table for holding a wafer having a circular concave portion formed on the back surface and an annular reinforcing portion surrounding the circular concave portion in a state where the surface is exposed, It has a columnar rising part having a concave part holding part for holding a circular concave part at the upper end, and a spacer support part that surrounds the cylindrical rising part below the concave part holding part, and one end is in the concave part holding part A hat-shaped base having a first suction path that is communicated and connected to the suction source at the other end, and is detachably attached to the spacer support portion of the hat-shaped base, and the columnar rising portion is fitted. An annular spacer having an opening, and the thickness of the annular spacer is set based on a value obtained by subtracting the depth of the circular concave portion of the wafer from the thickness of the cylindrical rising portion of the hat-shaped base. Keep Table is provided.

  Preferably, the back surface of the wafer is attached to an adhesive tape, the outer peripheral portion of the adhesive tape is attached to an annular frame, and the concave holding portion holds the circular concave portion of the wafer via the adhesive tape, The annular spacer includes an annular reinforcing portion supporting region for supporting the annular reinforcing portion of the wafer via the adhesive tape, an annular frame supporting region for supporting the annular frame via the adhesive tape, and the annular reinforcing portion supporting region. And a tape suction portion for sucking and holding the adhesive tape between the wafer formed between the annular frame support region and the inner peripheral edge of the annular frame, one end communicating with the suction portion, and the other end being the suction portion A second suction path connected to the source.

  According to the holding table of the present invention, even when handling a plurality of wafers having different depths of circular recesses, it is sufficient to have a plurality of annular spacers corresponding to the depths of the circular recesses of the wafer. The cost can be reduced compared with the case where the holding table is held.

  Since only the annular spacer has to be exchanged according to the depth of the circular concave portion of the wafer, workability is improved as compared with the prior art. In particular, since it is not necessary to change the holding surface height of the holding table in the cutting apparatus, it is not necessary to perform the origin return again, and the workability is improved as compared with the prior art.

  When the wafer is attached to the adhesive tape and the outer periphery of the adhesive tape is attached to the annular frame, tension is applied toward the outer periphery of the wafer by the weight of the annular frame or the clamp that clamps the annular frame. There is a problem that the wafer may be damaged.

  In the holding table according to the second aspect, since the annular frame is placed on the annular spacer and the adhesive tape is sucked and held between the inner periphery of the annular frame and the outer periphery of the wafer, such a problem is solved.

It is a partially broken longitudinal sectional view of a wafer suitable for holding on the holding table of the present invention in a state where the adhesive tape is attached to the back surface having a circular recess and the outer peripheral portion of the adhesive tape is attached to the annular frame. . It is a disassembled perspective view of the holding table concerning embodiment of this invention. It is a perspective view of the holding table shown in FIG. It is a longitudinal cross-sectional view of the holding table shown in FIG. It is a longitudinal cross-sectional view of the holding table concerning embodiment of the state which attracted and held the wafer. It is a partially broken perspective view of a spinner cleaning apparatus that employs the holding table of the present invention as a spinner table.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1, a partially broken longitudinal sectional view of a wafer 11 suitable for holding with a holding table of the present invention is shown. The wafer 11 has a device region 15 having a plurality of devices 13 formed on the surface thereof, and an outer peripheral surplus region 17 surrounding the device region 15.

  The back surface of the wafer 11 corresponding to the device region 15 is ground to form a circular concave portion 19, and the annular reinforcing portion 21 including the outer peripheral surplus region 17 surrounding the circular concave portion 19 is formed on the outer peripheral portion of the wafer 11. .

  When the wafer 11 having such a shape is cut by a cutting device and divided into individual devices 13, the adhesive tape T is adhered to the back surface of the wafer 11, and the outer peripheral portion of the adhesive tape T is attached to the annular frame F. Adhere. As a result, the wafer 11 is supported by the annular frame F via the adhesive tape T, and in this state, the wafer 11 is put into a cutting apparatus having the holding table of the present invention.

  Referring to FIG. 2, an exploded perspective view of the holding table 2 according to the embodiment of the present invention is shown. FIG. 3 is a perspective view of the holding table 2, and FIG. 4 is a longitudinal sectional view of the holding table 2.

  The holding table 2 includes a hat-shaped base 4 and an annular spacer 6 placed on the hat-shaped base 4. The hat-shaped base 4 is fitted into a spacer support 8 that supports the annular spacer 6 and a circular recess 19 of the wafer 11 formed on the inner peripheral side of the spacer support 8 to hold the circular recess 19. 10 has a cylindrical rising portion 12 formed at the upper end.

  The recess holding part 10 is made of, for example, porous ceramics. As shown in FIG. 4, the recess holding part 14 is selectively supplied to the negative pressure suction source 22 via a suction path 20 and a switching valve (not shown). Connected.

  The annular spacer 6 has an opening 14 into which the cylindrical rising portion 12 of the hat-shaped base 4 is fitted. Three concentric suction grooves 16 are formed on the surface of the annular spacer 6, and these suction grooves 16 are connected by connecting grooves 18 formed radially. As shown in FIG. 4, the intermediate suction groove 16 is selectively connected to the negative pressure suction source 22 via a suction path 28 formed in the annular spacer 6 and a suction path 30 formed in the hat-shaped base 4. .

  When the wafer 11 as shown in FIG. 1 is sucked and held by the holding table 2 of the present embodiment, first, the opening 14 of the annular spacer 6 is fitted into the columnar rising portion 12 of the hat-shaped base 4 to form an annular shape. The spacer 6 is placed on the hat-shaped base 4 and the holding table 2 is assembled as shown in FIG.

  As shown in FIG. 4, the annular spacer 6 includes an annular frame support region 24 that supports the annular frame F via the adhesive tape T, and an annular reinforcement portion that supports the annular reinforcement portion 21 of the wafer 11 via the adhesive tape T. A suction groove 16 for sucking and holding the adhesive tape T between the wafer 11 formed between the support region 26, the annular frame support region 24 and the annular reinforcement support region 26 and the inner peripheral edge of the annular frame F is formed. And a tape suction portion.

  Referring to FIG. 5, there is shown a longitudinal sectional view of a state in which the wafer 11 supported by the annular frame F via the adhesive tape T is sucked and held by the holding table 2. The concave holding portion 10 and the suction groove 16 are connected to a negative pressure suction source 22, the circular concave portion 19 of the wafer 11 is sucked and held by the concave holding portion 10, and the outer periphery of the wafer 11 and the annular frame are held by the tape suction portion having the suction groove 16. The adhesive tape T between the inner periphery of F is sucked and held.

  Here, the thickness of the annular spacer 6 is calculated. For example, when the circular recess 19 having a thickness of 100 μm is formed by grinding the back surface of a φ8 inch wafer, the thickness of the φ8 inch wafer is 725 μm, so the depth of the circular recess is 675 μm.

  When the height of the rising portion 12 of the hat-shaped base 4 is 20 mm, the thickness of the annular spacer 6 is preferably 20 mm−0.675 mm = 19.325 mm ± 0.01 mm. More preferably, the thickness of the annular spacer 6 is 19.325 mm ± 0.005 mm.

  When the thickness error of the annular spacer 6 is ± 0.02 mm or more, when the wafer 11 is sucked and held by the holding table 2, stress is generated at the boundary portion between the circular recess 19 and the annular reinforcing portion 21, and the wafer 11 is damaged. This is because there is a risk of it.

  As shown in FIG. 5, after the wafer 11 is sucked and held by the holding table 2, the wafer 11 is cut along the planned division line by a cutting blade of a cutting device, and the wafer 11 is divided into individual chips (devices) 13.

  When the holding table 2 of the present embodiment is employed in a chuck table of a cutting apparatus, chips (devices) 13 that are not completely cut are not generated in the outer peripheral portion of the wafer 11, and a defective device is not formed.

  Although the annular reinforcing portion 21 is not completely cut by cutting with a cutting blade, the annular reinforcing portion 21 portion is completely broken by the adhesive tape expanding process, which is a subsequent process of the wafer cutting process. Never become.

  In the holding table 2 of the present embodiment, even when a plurality of wafers 11 having different depths of the circular recesses 19 are handled, it is only necessary to prepare a plurality of annular spacers 6 according to the depth of the circular recesses 19 of the wafer 11. The cost can be reduced as compared with the case of holding a plurality of holding tables as in the prior art.

  Further, since only the annular spacer 6 needs to be replaced in accordance with the depth of the circular recess 19 of the wafer 11, workability is improved as compared with the prior art. In particular, since the holding surface height of the holding table 2 does not change in the cutting apparatus, the workability is improved as compared with the prior art because it is not necessary to re-examine the cutting blade.

  In addition, the holding table (chuck table) of the cutting apparatus is provided with a clamp that clamps the annular frame F. When the annular frame F is clamped and pulled down, it is moved in the outer circumferential direction of the wafer by its own weight or clamping. There is a problem that there is a risk of damaging the wafer due to the tension.

  In the holding table 2 of the present invention, the annular frame F is placed on the annular spacer 6 so that the adhesive tape T between the inner periphery of the annular frame F and the outer periphery of the wafer 11 is sucked and held. it can.

  Referring to FIG. 6, there is shown a partially broken perspective view of an embodiment in which the holding table of the present invention is adopted in the spinner table of the spinner cleaning device 32. The spinner cleaning device 32 includes a spinner table mechanism 34 and a cleaning water receiving mechanism 36 disposed so as to surround the spinner table mechanism 34.

  The spinner table mechanism 34 includes a spinner table 38, an electric motor 40 that rotationally drives the spinner table 38, and a support mechanism 42 that supports the electric motor 40 so as to be movable in the vertical direction.

  The spinner table 38 includes a hat-shaped base 41 and an annular spacer 43 placed on the hat-shaped base 41. The hat-shaped base 41 has a columnar rising portion 46 formed at the upper end of a concave portion holding portion 44 that fits into the circular concave portion 19 of the wafer 11 and holds the circular concave portion 19. Four pendulum clamps 48 are arranged on the outer periphery of the spinner table 38.

  The spinner table 38 is connected to the output shaft 40 a of the electric motor 40. The support mechanism 42 includes a plurality (three in the present embodiment) of support legs 50 and a plurality (three in the present embodiment) of air cylinders 52 attached to the electric motors 40 respectively connected to the support legs 50. It consists of.

  The cleaning water receiving mechanism 36 is attached to the cleaning water receiving container 54, three support legs 56 (only two are shown in FIG. 6) that support the cleaning water receiving container 54, and the output shaft 40 a of the electric motor 40. Cover member 57.

  The spinner cleaning device 32 includes a cleaning water supply nozzle 58 and an air supply nozzle 60 for cleaning the wafer 11 after being cut and held by the spinner table 38. After the wafer 11 is diced or after the annular reinforcing portion 21 of the wafer 11 is circle-cut, if the spinner cleaning device 32 having the spinner table 38 having such a configuration is used, cleaning is performed between the adhesive tape T and the wafer 11. It is possible to prevent water from entering and the annular reinforcing portion 21 from floating.

2 Holding table 4 Hat-shaped base 6 Annular spacer 8 Spacer support part 10 Recessed holding part 11 Wafer 12 Cylindrical rising part 14 Opening 15 Device area 16 Suction groove 17 Peripheral surplus area 19 Circular recessed parts 20, 28, 30 Suction path 21 Annular reinforcement Portion 22 Negative pressure suction source 32 Spinner cleaning device 34 Spinner table 40 Hat-shaped base 42 Annular spacer 44 Recess holder 46 Cylindrical rising portion T Adhesive tape F Annular frame

Claims (2)

A holding table that holds a wafer having a circular recess formed on the back surface and an annular reinforcing portion surrounding the circular recess in a state where the surface is exposed,
There is a columnar rising part formed at the upper end of a concave holding part that fits into the circular concave part and holds the circular concave part, and a spacer support part that surrounds the cylindrical rising part below the concave holding part. A hat-shaped base having a first suction path formed with one end communicating with the recess holding portion and the other end connected to a suction source;
An annular spacer that is detachably attached to the spacer support portion of the hat-shaped base and has an opening into which the columnar rising portion is fitted;
The holding table is characterized in that the thickness of the annular spacer is set based on a value obtained by subtracting the depth of the circular concave portion of the wafer from the thickness of the cylindrical rising portion of the hat-shaped base. The back surface of the wafer is attached to an adhesive tape, and the outer periphery of the adhesive tape is attached to an annular frame.
The concave holding portion holds the circular concave portion of the wafer via the adhesive tape,
The annular spacer includes an annular reinforcing portion supporting region for supporting the annular reinforcing portion of the wafer via the adhesive tape, an annular frame supporting region for supporting the annular frame via the adhesive tape, and the annular reinforcing portion supporting region. And a tape suction portion for sucking and holding the adhesive tape between the wafer formed between the annular frame support region and the inner peripheral edge of the annular frame, one end communicating with the suction portion, and the other end being the suction portion The holding table according to claim 1, further comprising a second suction path connected to the source.

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