JP2008140832A - Pin chuck type chuck table and cutting working device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pin chuck type chuck table capable of uniformly cutting the height of a bump because the surface of a wafer can be held flatly in the wafer with its rear formed in a conical shape or an inverted conical shape by a backgrinding. <P>SOLUTION: A heater is embedded at the center of a table base for the chuck table 19, and a holding surface 27a formed by a large number of pins 27 can be deformed conically by heating the center of a base 22 by the heater. When the backside of the wafer 1 ground in the inverted conical shape is stuck fast to the holding surface 27a, the surface side is deformed in the inverted conical shape in place of the flattening of the backside. However, the holding surface 27a is deformed in the conical shape by heating and expanding the central section of the base 22 by the heater, and the surface of the wafer 1 is adjusted flatly. The heights of the bumps 4 are equalized by cutting the bumps 4 in the state. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pin chuck type chuck table that sucks and holds a wafer and a cutting apparatus using the pin chuck type chuck table.

  In the semiconductor chip, a rectangular area of a lattice shape is defined on a surface of a disk-shaped wafer by lines to be cut called streets, an electronic circuit is formed in these rectangular areas, and then the wafer is cut and divided along the streets. Manufactured in a process.

  By the way, in recent years, a flip chip or the like has been developed and put into practical use as a technology that enables further reduction in size and thickness of various devices. In the flip chip, a protruding electrode called a bump having a height of, for example, about 15 to 100 μm is formed on the surface of a semiconductor chip, and this bump is directly bonded to the electrode on the mounting substrate side. Also known is a technique for reducing the size by arranging or stacking a plurality of semiconductor chips on a substrate called an interposer.

  In any of the above techniques, the chip and the substrate or the chips are bonded together through a plurality of bumps formed on the surface of the semiconductor chip. In such device technology, in order to join all the bumps properly, the bump tips are cut together at the wafer stage before being divided into chips, and the bump height from the chip surface is made uniform. Processing to be done. In some cases, an insulating resin is pre-molded on the chip surface in order to prevent a short circuit between adjacent bumps, and a cutting technique for such a wafer is described in Patent Document 1, for example.

  In the above-mentioned Patent Document 1, the back surface of the wafer is adhered to and held on the surface of the chuck table, and the exposed front surface bumps and resin are cut by a rotating cutting blade. As the chuck table, a pin chuck type is also provided in addition to the suction surface having a flat surface formed of a porous body. This pin chuck type chuck table adsorbs and holds the wafer on a flat holding surface formed by the tips of a large number of pins, so that the cutting waste hardly adheres to the holding surface, and the wafer is adsorbed by the sandwiched cutting waste. It has an advantage that accuracy is not easily deteriorated (see Patent Document 2).

Japanese Patent Application Laid-Open No. 2000-173954 JP-A-10-092738

  The bump cutting process is performed after the wafer is ground to the predetermined thickness. The back surface grinding of a wafer is generally performed by grinding the back surface with a grindstone or the like while rotating the wafer. However, strictly speaking, the thickness of the back-ground ground wafer is difficult to be uniform. For example, the back surface, which is a grinding surface, may become an inverted conical shape that is recessed toward the center, or may be a conical shape that protrudes toward the center. If the back surface is shifted to bump cutting without being ground to a flat surface parallel to the front surface in this way, the back surface of the wafer that is brought into close contact with the holding surface of the chuck table is deformed flat, and the shape of the back surface is shifted to the front surface side. Will appear. That is, when the back surface is an inverted cone, the surface is deformed into an inverted cone, and when the back surface is a cone, the surface is deformed into a cone. When the surface of the wafer that should be flat is deformed in this way, and the tip of the bump is cut with the wafer thickness being uneven, the tip of the bump is aligned and the height is uniform. Although it can be seen, since the surface of the wafer, which is the bump forming surface, is not flat, there remains a problem that the height of the bumps is not uniform.

  Therefore, the present invention can cut the tip of the bump formed on the surface of the wafer so that the height of the bump from the wafer surface is uniform even if the back surface of the wafer has a conical shape or an inverted conical shape. It is an object of the present invention to provide a pin chuck type chuck table and a cutting device that can be processed into a single shape.

  The pin chuck type chuck table of the present invention is a pin chuck type chuck table in which a plurality of pins are erected on the surface of a flat base, and the holding surface of the wafer is formed by the tips of these pins. It is characterized by comprising holding surface adjusting means for adjusting to a conical shape in which the central portion is convex or an inverted conical shape in which the central portion is concave.

  According to the pin chuck type chuck table of the present invention, it can be used when cutting the tip of the bump formed on the surface of the wafer to make the height uniform, and in this case, the back surface of the wafer is as follows. It is used according to the shape.

  When the back surface of the wafer is formed in an inverted conical shape by back surface grinding, when the back surface is brought into close contact with the flat holding surface of the chuck table, the surface on which the bumps are formed is deformed into an inverted conical shape. Here, the holding surface is adjusted by the holding surface adjusting means so that the central portion of the holding surface of the chuck table is convex, and the wafer surface is corrected to be flat. From this state, when the tip of the bump is cut with a cutting tool having a cutting surface parallel to the wafer surface, the bump is processed to have a uniform height from the wafer surface.

  On the other hand, when the back surface of the wafer is formed in a conical shape by back surface grinding, when the back surface is brought into close contact with the flat holding surface of the chuck table, the surface on which the bumps are formed is deformed into a conical shape. Here, the holding surface is adjusted so that the central portion of the holding surface of the chuck table becomes concave by the holding surface adjusting means, and the wafer surface is corrected to be flat. From this state, when the tip of the bump is cut with a cutting tool having a cutting surface parallel to the wafer surface, the bump is processed to have a uniform height from the wafer surface.

  Specific examples of the holding surface adjusting unit include a heating unit and a pressurizing unit. In the case of a heating means, a necessary part of the base of the pin chuck type chuck table is heated by the heating means and the base is expanded to change the shape of the base, and accordingly, the height of the plurality of pins forming the holding surface Changes. By adjusting the heights of the plurality of pins, it is possible to form a conical or inverted conical holding surface corresponding to variations in wafer thickness. In the case of the pressurizing means, the height of the plurality of pins changes by pressurizing the back surface of the central part of the holding means in the direction of the holding surface, and the holding surface is conical by adjusting the height of the pins. Can be formed.

  Next, a cutting apparatus of the present invention includes a pin chuck chuck table that holds a wafer by suction, and a cutting means that is disposed so as to face the chuck table and cuts the wafer that is sucked and held by the chuck table. The chuck table of the present invention is used as the chuck table.

  According to the present invention, even for a wafer whose back surface has a conical shape or an inverted conical shape by back surface grinding, the bump tip formed on the surface of the wafer is cut to increase the bump height from the wafer surface. There exists an effect that it becomes possible to process uniformly.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[1] Semiconductor Wafer FIG. 1A shows a disk-shaped semiconductor wafer to which cutting is performed in the present embodiment. A plurality of semiconductor chips 2 are formed on the surface of the wafer 1. These semiconductor chips 2 are configured by forming an electronic circuit on the surface of a rectangular region partitioned in a lattice pattern by streets 3 that are scheduled cutting lines.

  As shown in FIG. 1B, each semiconductor chip 2 has a plurality of bumps 4 protruding from the surface. As shown in FIG. 2, a resin layer 5 that covers all the bumps 4 is molded on the surface of the wafer 1. For example, a resin such as polyimide is used for the resin layer 5, and a short circuit between adjacent bumps 4 is prevented by the resin layer 5. The bump 4 is bonded to an electrode of an electronic circuit formed on the semiconductor chip 2 and protrudes from the surface of the semiconductor chip 2. These bumps 4 are formed by, for example, a well-known stud bump forming method, and the heights are often uneven. Since the bumps 4 are covered with the resin layer 5 and buried in the resin layer 5, it is necessary to expose the bumps 4 by cutting so that the bumps 4 have the same height. Cutting for aligning the heights of the bumps 4 is performed after the back surface of the wafer 1 is ground and the wafer 1 is thinned to a thickness used as the semiconductor chip 2.

[2] Cutting Device Next, a cutting device according to an embodiment of the present invention will be described.
FIG. 3 shows the entire cutting apparatus 10, and the apparatus 10 includes a rectangular parallelepiped base 11. At one end in the longitudinal direction of the base 11, a wall portion 12 erected vertically with respect to the horizontal upper surface of the base 11 is integrally formed. In FIG. 3, the longitudinal direction, the width direction, and the vertical direction of the base 11 are shown as a Y direction, an X direction, and a Z direction, respectively. On the base 11, the wall 12 side from the substantially middle portion in the longitudinal direction is a cutting area 11a for cutting the wafer 1, and the opposite side supplies the unprocessed wafer to the cutting area 11a, and after the processing The detachable area 11b for collecting the wafer 1 is used.
Hereinafter, the cutting area 11a and the attachment / detachment area 11b will be described.

(I) Mechanism of Cutting Area As shown in FIG. 3, rectangular pits 13 are formed in the cutting area 11a. A pin chuck type chuck table 19 is provided in the pit 13 so as to be movable in the Y direction via a moving table 14. The movable table 14 is slidably provided on a guide rail disposed in the pit 13 and extending in the Y direction, and can be reciprocated in the same direction by an appropriate drive mechanism (not shown).

  One end of bellows-like covers 15 and 16 are attached to both ends of the moving table 14 in the moving direction, and the other ends of the covers 15 and 16 are the pits facing the inner surface of the wall portion 12 and the wall portion 12. Each is attached to the inner wall surface of 13. These covers 15 and 16 cover the moving path of the moving table 14 and prevent cutting chips and the like from falling on the moving path, and expand and contract as the moving table 14 moves.

  The chuck table 19 is placed on the movable table 14 and rotated in one direction or both directions by a rotation mechanism (not shown). Since the spindle unit 40 to be described later is a type that rotates a cutting tool tool, the chuck table 19 that holds the wafer 1 may not be freely rotatable but may be fixed. The chuck table 19 is a member according to the present invention and will be described in detail later.

  The chuck table 19 is moved to the wall 12 side together with the moving table 14 and is positioned at a predetermined processing position. A spindle unit 40 is disposed above the processing position. The spindle unit 40 is slidably mounted on a Z-axis linear guide 48 extending in the Z direction via a Z-axis slider 47, and is moved in the Z direction by a ball screw type feed mechanism 50 driven by a servo motor 49. It can be moved. The spindle unit 40 is moved up and down in the Z direction by the feed mechanism 50 and lowered to cut the exposed surface of the wafer 1 held by the chuck table 19 by a feed operation that approaches the chuck table 19. The chuck table 19 is moved back and forth between the machining position and the attachment / detachment position closest to the attachment / detachment area 11b by the reciprocating movement of the movable table 14.

  As shown in FIG. 3, the spindle unit 40 includes a cylindrical spindle housing 41 whose axial direction extends in the Z direction. In the spindle housing 41, a spindle shaft 51 shown in FIG. 4 is supported coaxially and rotatably. The spindle shaft 51 is driven to rotate by a spindle motor 42 fixed to the upper end portion of the spindle housing 41. A disc-shaped flange 43 is coaxially fixed to the lower end of the spindle shaft 51, and the cutting tool 44 is fixed to the flange 43. As shown in FIG. 3, in the spindle unit 40, the spindle housing 41 is fixed to the Z-axis slider 47.

  The cutting tool 44 is formed by attaching a cutting tool 46 to the lower surface of an annular frame 45, and the frame 45 is detachably attached to the flange 43 by means such as screwing. The cutting tool 46 has a blade portion made of diamond or the like fixed to the tip. The cutting tool 46 is fixed in a state in which the blade part is disposed below and protrudes downward from the outer peripheral part of the frame 45.

(II) Mechanism of Attachment / Removal Area As shown in FIG. 3, a polygonal pit 70 is formed at the center of the attachment / detachment area 11b. 71 is installed. Around the transfer robot 71, a recovery structure having the same structure as the supply cassette 72, the positioning table 73, the swing arm type supply arm 74, the cleaning nozzle 75, and the supply arm 74 is counterclockwise as viewed from above. An arm 76, a spinner type cleaning device 77, and a recovery cassette 78 are arranged.

  The supply cassette 72, the positioning table 73, and the supply arm 74 are means for supplying the wafer 1 to the chuck table 19. The recovery arm 76, the spinner type cleaning device 77, and the recovery cassette 78 chuck the wafer 1 whose back surface has been cut. Means for collecting from the table 19. Each cassette 72, 78 accommodates a plurality of wafers 1 in a stacked state, and is set at a predetermined position on the base 11. The cleaning nozzle 75 jets cleaning water toward the chuck table 19 positioned at the attachment / detachment position, and this operation is repeated each time the wafer 1 is cut.

[3] Details of Chuck Table Next, the chuck table 19 according to the present invention will be described with reference to FIG.
FIG. 5A shows a cross-sectional view of the chuck table 19, and FIG. 5B shows a plan view of the chuck table 19. The chuck table 19 includes a chuck table main body 21 and a table base 20 to which the chuck table main body 21 is fixed. The table base 20 is supported on the movable table 14. The chuck table main body 21 has a disk-shaped base 22. An annular frame 23 that protrudes upward is formed concentrically on the outer peripheral portion of the surface of the base 22 so as to leave the edge 24 of the outermost peripheral portion, and the inside of the frame 23 is an adsorption area. 25. The base 22 is fixed to the table base 20 with bolts 26 that pass through the edge 24.

  On the surface 25a of the suction area 25 of the base 22, a large number of pins 27 standing at right angles to the surface 25a are erected. These pins 27 are formed integrally with the base 22. The intervals between the adjacent pins 27 are substantially equal, and a flat holding surface 27 a for holding the wafer 1 is formed by the tips of a large number of pins 27. The size of the suction area 25 is set to be the same as the size of the wafer 1 or a size that allows the wafer 1 held on the holding surface 27 a to slightly protrude outside the frame body 23.

  In the suction area 25 of the base 22, a plurality (four in the illustrated example) of through holes 28 penetrating from the surface 25 a to the lower surface 25 b are formed, and the through holes 28 are formed in the table base 20. It leads to the hole 29. These suction holes 29 are connected to a vacuum pump (not shown), and when the vacuum pump is operated, air on the surface side of the base 22 is sucked into the vacuum pump through the through holes 28 and the suction holes 29, thereby 1 is adsorbed and held on the holding surface 27a. The chuck table 19 in which a large number of pins 27 are erected on the base 22 is made of stainless steel such as SUS430, for example, and the thickness of the base 22 is about 25 mm, for example.

  An electrothermal heater (holding surface adjusting means) 30 is embedded in the center of the table base 20. The upper surface of the heater 30 is flush with the surface of the flat table base 20, and the upper surface is in contact with the lower surface of the base 22. When the heater 30 is energized and the heater 30 generates heat, the base 22 is heated from the center and expands according to the heating temperature. When the central portion of the base 22 expands, as shown in FIG. 5A, the holding surface 27a rises upward in the center and deforms into a conical shape corresponding to the temperature gradient. The figure h shows the amount of rise of the central part of the holding surface 27a due to heating.

(III) A Series of Operations of the Cutting Device The configuration of the cutting device 10 has been described above. Next, the operation of the cutting processing for aligning the heights of the bumps 4 of the wafer 1 using the device 10 will be described. The wafer 1 is ground in advance and thinned to a predetermined thickness to be used as the semiconductor chip 2, and a plurality of such wafers 1 are accommodated in the supply cassette 72. First, one wafer 1 is pulled out from the supply cassette 72 by the transfer robot 71, and the wafer 1 is placed on the positioning table 73 with the back side facing up, and is determined at a fixed position. .

  The wafer 1 positioned on the positioning table 73 is picked up by vacuum suction from the positioning table 73 by the supply arm 74 and placed on the chuck table 19 waiting at the attachment / detachment position. The chuck table 19 is previously operated in vacuum, so that the wafer 1 is attracted and held on the holding surface 27 a of the chuck table 19. Next, the cutting tool 44 is rotated at a high speed by the spindle motor 42 (for example, 1000 rpm), and the cutting tool 44 is further cut to a predetermined amount by the feed mechanism 50, that is, the bump 4 is set to a predetermined height. Lower it to the height you want to align. Then, the moving table 14 is moved at a predetermined speed in the processing position direction below the spindle unit 40. Then, the surface of the wafer 1 covered with the resin layer 5 is cut by the cutting tool 44 of the cutting tool 44 and moved until the wafer 1 is covered by the frame 45, whereby the entire surface of the wafer 1 is cut flat. The The surface of the wafer 1 is in a state in which the flat tip surfaces of all the cut bumps are exposed between the cut flat resin layers 5. In addition, when performing this cutting process, if the chuck table 19 rotates, the wafer 1 may be rotated together with the chuck table 19.

  When cutting of the surface of the wafer 1 to make the height of the bumps 4 uniform, the moving table 14 is moved forward in the Y direction so that the wafer 1 is positioned at the attachment / detachment position, and the vacuum operation of the chuck table 19 is stopped to stop the wafer. 1 is in a state in which it can be detached from the chuck table 19. Next, the wafer 1 is transported from the chuck table 19 to the spinner type cleaning device 77 by the recovery arm 76 to be cleaned and dried, and then transferred and accommodated in the recovery cassette 78 by the transport robot 71.

[4] Action of Chuck Table The above is an example of the operation of the cutting apparatus 10, and next, the action of the chuck table 19 of this embodiment will be described.
As described above, the wafer 1 whose surface is cut as described above is ground in advance and thinned to a predetermined thickness, but the ground surface of the ground wafer 1 is directed toward the center. It may become an inverted conical shape. In such a wafer with a non-flat back surface, if the back surface is sucked and held on the chuck table to cut the surface, the unevenness of the back surface will be transferred to the surface, and the bump height will be reduced even if the surface is cut flat. There was a problem that could not be aligned. According to the chuck table 19 of the present embodiment, this problem can be solved as follows.

  FIG. 6A shows a wafer 1 in which a large number of bumps 4 are formed on the surface, and a resin layer 5 covering the bumps 4 is molded on the surface. FIG. 6B shows the wafer 1 whose back surface is ground, but this wafer 1 is formed in an inverted conical shape in which the ground back surface is recessed toward the center.

  In order to cut the tip of the bump 4 together with the resin layer 5, as shown in FIG. 6C, the back surface of the wafer 1 is brought into close contact with the flat holding surface 27a of the chuck table 19 and the surface to be cut is exposed. Here, as shown in the figure, the back surface of the wafer 1 that is in close contact with the holding surface 27a of the chuck table 19 has a reverse conical shape, but is deformed flatly, and the deformation is displaced to the front surface side so that the surface is It becomes an inverted cone shape. If the surface is cut in this state, the height of the bumps 4 becomes uneven, such that the outer peripheral side is low and the inner peripheral side is high.

  Therefore, the central portion of the base 22 is heated and expanded by the heater 30 to deform the holding surface 27a of the chuck table 19 into a conical shape as shown in FIG. Adjust the flat surface of the base to flat. As a result, the surface of the wafer 1 becomes parallel to the cutting surface of the cutting tool 44, and when this state is maintained and all the bumps 4 are cut together with the resin layer 5, the bumps 4 are processed to have a uniform height. The cutting is performed by rotating the cutting tool 44 of the spindle unit 40 and moving the chuck table 20 together with the moving table 14 to the processing position as described in the operation of the above-described cutting processing apparatus.

  The heating temperature of the base 22 by the heater 30 is required to be a temperature at which the surface of the wafer 1 becomes flat on the expanded base 22. For example, it is known from the linear expansion coefficient that SUS430, which is the material of the chuck table main body 21, expands by 3 μm in the thickness direction in about 10 seconds when it is raised by 12 ° C. from the ambient temperature. In addition to obtaining in advance data related to expansion according to such materials, the amount of deformation of the back surface (depth if inverted conical) is measured before cutting, and the heating temperature is determined from these data. can do.

  According to this embodiment, even if the wafer 1 having the ground back surface formed in an inverted conical shape is attracted and held on the chuck table 19, the surface of the wafer 1 is corrected to a flat shape. For this reason, the height of the pump 4 can be made uniform easily by cutting. Further, since the holding surface 27 a of the chuck table 19 is formed by the tips of a large number of pins 27, it is difficult for cutting waste generated by cutting to adhere to the tips of the pins 27. For this reason, the problem that the suction accuracy of the wafer deteriorates due to the cutting waste sandwiched between the wafer 1 and the chuck table 19 hardly occurs.

[5] Other Embodiments of Holding Surface Adjustment Unit In the above embodiment, the center of the base 22 of the chuck table main body 21 is heated and expanded by heating to deform the holding surface 27a into a conical shape. As a means for deforming the holding surface 27a in this way, as shown in FIG. 7, an actuator (holding surface adjusting means) 31 that pressurizes and deforms the center of the base 22 upward may be applied. The actuator 31 is composed of a piezo element or the like, and is embedded in the center of the upper surface of the table base 20. When the actuator 31 protrudes upward by being applied, the center of the base 22 is pushed up, whereby the holding surface 27a is conical. The surface of the wafer 1 is adjusted to be flat. The protrusion amount of the actuator 31 is determined based on a measured value obtained by measuring in advance the depth of the back surface of the wafer 1 that has become an inverted conical shape by grinding.

[6] When the back surface of the wafer is ground into a conical shape In the above embodiment, the back surface of the wafer 1 is ground into an inverted conical shape. However, in the present invention, the back surface is ground into a conical shape. This includes making the bump height uniform. FIG. 8 shows an example thereof, in which a heater is used in the same manner as the example shown in FIG. The heater 30 in this case is formed in an annular shape, and is disposed at a position almost directly below the frame body 23 in the outer peripheral portion of the table base 20. The upper surface of the heater 30 is flush with the surface of the table base 20 and is in contact with the lower surface of the base 22. When the heater 30 is energized and the heater 30 generates heat, the base 22 is heated from the outer peripheral portion and expands according to the heating temperature. When the outer peripheral portion of the base 22 expands, as shown in FIG. 8A, the holding surface 27a rises upward and is deformed into an inverted conical shape corresponding to the temperature gradient. In the figure, h indicates the amount of increase in the outer peripheral portion of the holding surface 27a due to heating.

According to this embodiment, the surface of the wafer 1 is adjusted to be flat as follows.
FIG. 9A shows the wafer 1 before back surface grinding. When the back surface of the wafer 1 is ground, the back surface is ground as shown in FIG. May be formed in a conical shape that protrudes toward the center.

  In order to cut the tip of the bump 4 together with the resin layer 5, when the wafer 1 is held in close contact with the flat holding surface 27a of the chuck table 19 as shown in FIG. The conical shape is deformed flat, and the deformation is dislocated to the surface side so that the surface becomes conical. If the surface is cut in this state, the height of the bumps 4 becomes uneven, such that the outer peripheral side is low and the inner peripheral side is high.

  In this case, the outer peripheral portion of the base 22 is heated and expanded by the heater 30, thereby deforming the holding surface 27a of the chuck table 19 into an inverted conical shape as shown in FIG. Make the surface flat. As a result, the surface of the wafer 1 becomes parallel to the cutting surface of the cutting tool 44, and when this state is maintained and all the bumps 4 are cut together with the resin layer 5, the bumps 4 are processed to have a uniform height.

BRIEF DESCRIPTION OF THE DRAWINGS (a) Perspective view of wafer to which cutting is performed in one embodiment of the present invention, (b) An enlarged plan view showing a semiconductor chip, (c) A side view. FIG. 2 is an enlarged side view of the wafer shown in FIG. 1. It is a perspective view of a grinding apparatus provided with the pin chuck type chuck table of the present invention. It is a side view which shows the state which is cutting the wafer surface with the spindle unit with which the grinding-work apparatus shown in FIG. 3 is provided. It is the (a) side view and (b) top view of the pin chuck type chuck table of one embodiment. (A) Side view of wafer before grinding, (b) Side view of wafer whose back surface is ground in an inverted conical shape, (c) Side view of a state where the wafer is simply adsorbed and held on the chuck table of one embodiment. (D) It is a side view in the state where the holding surface of the chuck table was deformed into a conical shape and the wafer surface was adjusted to be flat. It is other embodiment of this invention, Comprising: It is a side view of the chuck table which replaced the holding surface adjustment means with the actuator. It is other embodiment applied to the wafer by which the back surface was formed in cone shape, Comprising: (a) Side view of the chuck table by which a heating means is arrange | positioned at the outer peripheral part of a table base, (b) Plan view. (A) A side view of the wafer before grinding, (b) a side view of the wafer whose back surface is ground into a conical shape, (c) a side view in a state where the wafer is simply adsorbed and held on the chuck table of one embodiment, (D) It is a side view of the state which adjusted the wafer surface flatly by changing the holding surface of a chuck table to conical shape.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Wafer 19 ... Pin chuck type chuck table 22 ... Base 27 ... Pin 27a ... Holding surface 30 ... Heater (holding surface adjustment means)
31 ... Actuator (holding surface adjusting means)

Claims (4)

In a pin chuck type chuck table in which a plurality of pins are erected on the surface of a flat base, and a wafer holding surface is formed by the tips of these pins.
A pin chuck type chuck table comprising holding surface adjusting means for adjusting the holding surface into a conical shape having a convex central portion or an inverted conical shape having a concave central portion.   The said holding surface adjustment means is a heating means which adjusts a holding surface to a cone shape or a reverse cone shape by heating the required part of the said base and expanding this base. Pin chuck type chuck table as described in 1.   The said holding surface adjustment means is a pressurization means which adjusts a holding surface to a cone shape by pressurizing the back surface of the center part of the said holding means to the said holding surface direction. Pin chuck type chuck table. A pin chuck type chuck table that sucks and holds the wafer;
In a cutting apparatus provided with a cutting means arranged to face the chuck table and cutting the wafer held by the chuck table,
A wafer cutting apparatus according to any one of claims 1 to 3, wherein the chuck table is any one of claims 1 to 3.

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