JP2008087104A - Grinding method - Google Patents

Abstract

In a grinding apparatus of a type in which the height of a holding surface of a chuck table is changed, the height of the changing holding surface is always grasped, and a grindstone fixing surface of a grinding wheel is processed during a feed operation of a grinding means. It reliably prevents contact with objects and holding surfaces.
Interlock control for preventing the wheel base 36 of the grinding wheel 35 from coming into contact with the chuck table 20 and the wafer 1 does not depend on the height of the grindstone 37, the wheel base 36, the chuck table upper surface 20A and the wafer. 1 is performed based on the interval with 1.
[Selection] Figure 6

Description

  The present invention relates to a method for grinding a thin plate-like substrate such as a semiconductor wafer, and more particularly, an apparatus for grinding by pressing a grindstone fixed to a wheel base against a workpiece held on a chuck table. The present invention relates to a grinding method in the case of using a grinding device in which the height of the workpiece holding surface of the chuck table changes.

  Thin semiconductor substrates used as materials for semiconductors and electronic components include, for example, those made of a single crystal material such as silicon and those made of a compound having a plurality of elements. These substrates slice raw material ingots. Then, after chamfering, lapping, and etching, grinding is performed to reduce the thickness to a predetermined thickness and flatten the surface.

  In this type of grinding process, the work piece is adsorbed and held on a vacuum chuck type chuck table having a holding surface made of porous ceramics, and the grinding wheel of the grinding wheel is rotated and pressed against the exposed surface. A grinding apparatus of the type for grinding is used. In such a grinding apparatus, the thickness of the workpiece is measured by a thickness gauge before and after grinding and during grinding, and when the measured thickness reaches the target thickness, the grindstone removes the workpiece. Control to stop the feeding operation to be pressed is performed.

  As the grinding wheel provided in the grinding apparatus as described above, a grinding wheel having an annular or annularly arranged grindstone fixed to one end surface of an annular wheel base made of aluminum or the like is preferably used. . Examples of the grindstone include those formed by mixing diamond abrasive grains in a binder such as vitrified. Since the grinding wheel grindstone gradually wears out and may disappear, interlock control is necessary to prevent the grinding wheel from being fed beyond the distance between the chuck table holding surface and the wheel base grindstone fixing surface. It is said. Usually, in a grinding machine, a work called a pre-operation setup is performed to control the feed amount of the grinding wheel by inputting the distance between the cutting edge (lower end) of the grinding wheel and the holding surface of the chuck table to the machine. By inputting the height of the grindstone that can be used at the time of this setup, interlock control is performed to prevent the wheel base from coming into contact with the chuck table even when the grindstone disappears (see Patent Document 1, etc.) ).

JP 08-243905 A

  In the above-described grinding apparatus, there is a case where a process called self-grinding is performed by periodically grinding the holding surface of the chuck table by its own grinding wheel. By performing this self-grinding, for example, the holding surface of the chuck table and the grinding surface of the grindstone are set to an equal distance, and as a result, the workpiece is ground to a uniform thickness. By the way, the height of the holding surface gradually decreases by self-grinding the chuck table, and therefore the distance of the holding surface of the chuck table to the wheel base grindstone fixing surface changes each time self-grinding is performed. It will be. This means that the mechanical positional relationship between the wheel base and the chuck table changes when the apparatus is assembled.

  Specifically, the holding surface of the chuck table is lowered, and the distance between the holding surface and the grindstone fixing surface of the wheel base is longer than the initial one. Here, when the grindstone is continuously used, the grindstone is worn out, and in addition to this, the interval between the holding surface of the chuck table and the grindstone fixing surface of the wheel base becomes long. Even if normal interlock control is continued, the wheel base does not contact the chuck table.

  By the way, the height of a grindstone may change by replacing another grinding wheel with a wheel mount during use or dressing a grindstone in use. In this case, the distance between the cutting edge (lower end) of the grindstone and the holding surface of the chuck table is re-entered into the device. If the input value is incorrect or forgotten, the interlock If control is not performed correctly and grinding is continued in this state and the grindstone disappears, the grinding means is further fed toward the workpiece, and the wheel base comes into contact with the workpiece and the chuck table. There was a risk of it.

  Therefore, the present invention provides a grinding apparatus of a type in which the height of the holding surface of the chuck table changes, always grasps the changing height of the holding surface, and the grindstone fixing surface of the grinding wheel is determined during the feeding operation of the grinding means. An object of the present invention is to provide a grinding apparatus having an interlock function that can prevent contact with a workpiece or a holding surface.

  The present invention is provided with a chuck table having a holding surface for holding a plate-like workpiece and the holding surface of the chuck table so as to be able to approach and separate, and is held on the holding surface by an approaching feeding operation. Grinding means including at least grinding means having a grinding wheel for grinding a workpiece, and feed means having a grinding means position recognizing unit for recognizing the position of the grinding means approaching and separating from the holding surface Comprises a spindle shaft and a wheel mount having a mounting surface fixed to the tip of the spindle shaft and to which a grinding wheel is mounted. The grinding wheel has a grindstone fixing surface substantially parallel to the holding surface of the chuck table. A grinding apparatus comprising a wheel base having a thickness and a grindstone that is fixed to a grindstone fixing surface of the wheelbase and that actually grinds a workpiece. In this method, the workpiece A is ground by setting a distance A between the holding surface of the chuck table and the mounting surface of the wheel mount to a predetermined distance and grinding recognized by the grinding means position recognition unit at this time. The initial position Z1 of the means is stored, and the wheel base thickness T is subtracted from the value of the distance A to obtain the distance B between the wheel base grindstone fixing surface and the chuck table holding surface, and the distance B and From the value of the initial position Z1 of the grinding means, the limit position Z2 of the grinding means immediately before the grindstone fixing surface comes into contact with the holding surface is obtained, the thickness W of the workpiece held on the chuck table is measured, and the grinding means Based on the limit position Z2 and the thickness W of the workpiece, the grinding means position recognition unit makes contact between the wheel base grindstone fixing surface and the workpiece held on the chuck table holding surface. Recognizes the position Z3, on the basis of the position Z3, grinding wheel fixing surface of the grinding wheel to the workpiece is characterized in that to terminate the grinding before abutting.

  According to the present invention, while the grinding wheel of the grinding means is rotated together with the spindle shaft, the grinding means is fed toward the workpiece held by the chuck table by the feeding portion of the feeding means, and the grinding wheel of the grinding wheel is fed to the surface of the workpiece. Is a method of grinding a workpiece by pressing. In this method, according to the present invention, the height of the grindstone of the grinding wheel to be mounted on the mount surface of the wheel mount is controlled by interlock control for preventing the grindstone fixing surface of the wheel base from coming into contact with the workpiece or the holding surface of the chuck table. This is performed by accurately grasping the distance between the wheel base grindstone fixing surface, the chuck table holding surface and the workpiece. The specific method is as described above, and according to the interlock control according to the present invention, the grinding means position recognition unit provided in the feeding means of the grinding means grasps the limit position Z2 above, thereby The grindstone fixing surface is prevented from coming into contact with the holding surface of the chuck table, and by grasping the position Z3, the grindstone fixing surface of the wheel base is prevented from coming into contact with the chuck table.

  In the above method, the initial position Z1 of the grinding means is set based on the distance A between the mounting surface of the wheel mount and the holding surface of the chuck table. For this reason, the thickness T of the wheel base is subtracted from the distance A. There is a need. Therefore, as a method that does not require this subtraction, the distance B 'between the wheel base grindstone fixing surface and the chuck table holding surface may be set directly. That is, the interval B ′ is set, and the initial position Z1 ′ of the grinding means recognized by the grinding means position recognition unit at this time is stored. From the values of the interval B ′ and the initial position Z1 ′, the grindstone fixing surface is stored. Is set to the limit position Z2 of the grinding means just before contacting the holding surface. The subsequent flow of interlock control is the same as in the above method.

  The present invention also includes a method for performing interlock control based on a distance C between the holding surface of the chuck table and a reference surface set on the chuck table base. This distance C can be measured by a thickness measuring means for measuring the thickness of the workpiece.

  That is, this method measures and stores this distance C, and subtracts the distance C from the distance D between the mount surface of the wheel mount and the reference surface to obtain the distance E between the mount surface of the wheel mount and the holding surface of the chuck table. Then, the wheel base thickness T is subtracted from the distance E to obtain a distance B between the wheel base grindstone fixing surface and the chuck table holding surface, and the distance B is recognized by the grinding means position recognition unit. From the value of the initial position Z1 ″ of the grinding means at the distance D, which is the device-specific and stationary positional relationship, the limit position Z2 of the grinding means immediately before the grindstone fixing surface abuts the holding surface is obtained, and the chuck The thickness W of the workpiece held on the table is measured, and based on the limit position Z2 of the grinding means and the thickness W of the workpiece, the grinding means position recognizing portion Recognizing a position Z3 where the workpiece held on the holding surface of the chuck table comes into contact, and based on this position Z3, the grinding is finished before the grindstone fixing surface of the grinding wheel comes into contact with the workpiece. It is characterized by.

  According to the present invention, the interlock control for preventing the wheel base of the grinding wheel from coming into contact with the chuck table and the workpiece is independent of the height of the grindstone, the wheel base, the holding surface of the chuck table, and the workpiece. Since the distance between the chuck table and the workpiece is changed, the grinding wheel fixing surface of the grinding wheel comes into contact with the chuck table holding surface and the workpiece during the feed operation of the grinding means. There is an effect that this can be surely prevented.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[1] Configuration and Schematic Operation of Grinding Apparatus FIG. 1 shows a grinding apparatus 10 that uses a semiconductor wafer such as a silicon wafer (hereinafter abbreviated as a wafer) as a workpiece and grinds the surface of the wafer. FIG. 2 shows an example of a wafer to be ground. This wafer 1 is obtained by, for example, slicing a raw material ingot, then adjusting the thickness by lapping, and then forming a double-sided machine. The material layer is obtained by removing the damaged layer by etching. A V-shaped notch 2 indicating a crystal orientation is formed on the outer peripheral edge of the wafer 1. The thickness of the wafer 1 is, for example, about 800 μm, and the thickness of, for example, about 20 μm is removed by the grinding apparatus 10.

  A grinding apparatus 10 shown in FIG. 1 includes a rectangular parallelepiped base 11 whose upper surface is horizontal. In FIG. 1, the longitudinal direction, the width direction, and the vertical direction of the base 11 are shown by the Y direction, the X direction, and the Z direction, respectively. At one end portion of the base 11 in the Y direction, a column 12 arranged in the X direction is erected in a pair. On the base 11, a processing area 11A for grinding the wafer 1 is provided on the column 12 side in the Y direction, and the wafer 1 before processing is supplied to the processing area 11A on the side opposite to the column 12, and An attachment / detachment area 11B for collecting the processed wafer 1 is provided.

  In the processing area 11A, a disk-shaped turntable 13 whose rotation axis is parallel to the Z direction and whose upper surface is horizontal is rotatably provided. The turntable 13 is rotated in the direction of arrow R by a rotation drive mechanism (not shown). A plurality (three in this case) of disk-shaped chuck tables 20 whose rotation axis is parallel to the Z direction and whose upper surface is horizontal are rotated at equal intervals in the circumferential direction on the outer periphery of the turntable 13. Arranged freely.

  These chuck tables 20 are of a generally known vacuum chuck type and suck and hold the wafer 1 placed on the upper surface. As shown in FIGS. 3 and 4, the chuck table 20 has a configuration in which a circular adsorption area 22 made of a porous ceramic material is provided at the center of the upper surface of a disc-shaped frame 21. An annular upper surface 21a of the frame body 21 is formed around the suction area 22, and the upper surface 21a and the upper surface 22a of the suction area 22 are both horizontal and flat on the same plane 20A. Each chuck table 20 is independently rotated or rotated in one direction or both directions by a rotation drive mechanism (not shown) provided in the turntable 13, and revolves when the turntable 13 rotates. It becomes a state.

  As shown in FIG. 1, in a state where two chuck tables 20 are arranged in the X direction on the column 12 side, a grinding unit (grinding means) 30 is disposed immediately above the chuck tables 20. Each chuck table 20 is positioned at three positions, that is, a grinding position below each grinding unit 30 and an attachment / detachment position closest to the attachment / detachment area 11 </ b> B by rotation of the turntable 13. There are two grinding positions, and a grinding unit 30 is provided for each of these grinding positions. In this case, the grinding position on the upstream side (back side in FIG. 1) in the transfer direction indicated by the arrow R of the chuck table 20 by the rotation of the turntable 13 is the primary grinding position, and the downstream grinding position is the secondary grinding position. . Rough grinding is performed at the primary grinding position, and finish grinding is performed at the secondary grinding position.

  Each grinding unit 30 is fixed to a slider 40 attached to the column 12 so as to be movable up and down. The slider 40 is slidably mounted on a guide rail 41 extending in the Z direction, and can be moved in the Z direction by a ball screw type feed mechanism (feed means) 43 driven by a servo motor 42. Each grinding unit 30 is moved up and down in the Z direction by the feed mechanism 43 and grinds the exposed surface of the wafer 1 held by the chuck table 20 by a feed operation that approaches the chuck table 20 by lowering. The feed mechanism 43 includes a position recognition unit (not shown) that recognizes the position of the grinding unit 30 that moves up and down.

  As shown in FIG. 3, the grinding unit 30 includes a cylindrical spindle housing 31 whose axial direction extends in the Z direction, a spindle shaft 32 coaxially and rotatably supported in the spindle housing 31, and a spindle housing. A motor 33 that is fixed to the upper end of 31 and rotationally drives the spindle shaft 32 and a disk-like wheel mount 34 that is coaxially fixed to the lower end of the spindle shaft 32 are provided. A grinding wheel 35 is detachably attached to a mount surface 34a, which is the lower surface of the wheel mount 34, by attachment means such as screwing.

  The grinding wheel 35 has a plurality of grinding wheels 37 arranged and fixed to a grinding wheel fixing surface 36a, which is the lower surface of an annular wheel base 36 made of aluminum or the like. The grindstone 37 is formed by mixing diamond abrasive grains in a binder such as vitrified, for example. For example, a grinding wheel 35 to which a grindstone 37 containing abrasive grains of # 2000 to # 8000 is fixed is attached to the wheel mount 34 of the grinding unit 30 for primary grinding disposed above the primary grinding position. A grinding wheel 35 to which a grindstone 37 containing, for example, # 10000 or more abrasive grains is fixed is attached to the wheel mount 34 of the grinding unit 30 for secondary grinding disposed above the secondary grinding position. The wheel mount 34 and the grinding wheel 35 are provided with a grinding water supply mechanism (not shown) for supplying grinding water for cooling and lubrication of the grinding surface or discharging grinding debris, and a water supply line is connected to the mechanism. ing.

  As shown in FIG. 1, on a base 11, a chuck table in which a thickness measuring gauge 50 configured by a combination of a reference side height gauge 51 and a wafer side height gauge 52 is located on a primary grinding side and a secondary grinding side. 20, respectively. As shown in FIG. 3, the reference-side height gauge 51 is such that the tip of the swinging reference probe 51a contacts the upper surface 21a of the frame body 21 of the chuck table 20 that is not covered with the wafer 1, and the height position of the upper surface 21a Is detected. The wafer-side height gauge 52 detects the height position of the upper surface of the wafer 1 when the tip of the oscillating variable probe 52a contacts the upper surface of the wafer 1 held by the chuck table 20, that is, the surface to be ground. .

  According to the thickness measurement gauge 50, the thickness of the wafer 1 is measured based on the value obtained by subtracting the measurement value of the reference side height gauge 51 from the measurement value of the wafer side height gauge 52. As shown in FIG. 4, when the wafer 1 is ground to the target thickness: t1, the original thickness: t2 is first measured before grinding, and (t2-t1) is taken as the grinding amount. The thickness measurement point of the wafer 1 by the wafer-side height gauge 52, that is, the contact point of the variable probe 52a is preferably an outer peripheral portion close to the outer periphery of the wafer 1 as indicated by a broken line in FIG.

  The grinding unit 30 moves down the grinding wheel 35 at a predetermined speed (for example, about 0.3 to 0.5 μm / second) while the grinding wheel 35 rotates at, for example, 2000 to 5000 rpm, so that the grindstone 37 of the grinding wheel 35 becomes the surface of the wafer 1. , Thereby grinding the surface. During grinding, the wafer 1 is rotated in the same direction as the grinding wheel 35 together with the chuck table 20, but the rotation speed of the chuck table 20 is set to about 300 rpm at the maximum from about 10 rpm. The amount of grinding by the grinding unit 30 is controlled by measuring the thickness of the wafer 1 with the thickness measuring gauge 50.

  As shown in FIG. 4, a grinding wheel 35 having a grinding outer diameter equal to the diameter of the grinding wheel 37 larger than the radius of the chuck table 20 is used, and the grinding wheel 35 has a grinding outer peripheral edge by the grinding stone 37. It is positioned facing the wafer 1 so as to pass through the center of rotation of the chuck table 20, that is, the center of the wafer 1. Due to this positional relationship, the entire surface of the rotating wafer 1 is uniformly ground by the grindstone 37 of the grinding wheel 35.

  The wafer 1 is first ground by the grinding unit 30 at the primary grinding position, and then transferred to the secondary grinding position by rotating the turntable 13 in the R direction shown in FIG. Next is ground.

  Reference numeral 60 in FIG. 1 is a set-up sensor provided on the base 11. Although this setup sensor 60 is only shown for the chuck table 20 on the secondary grinding side in FIG. 1, it is also provided for the chuck table 20 on the primary grinding side (in the grinding unit 30 on the primary grinding side). Not shown)

  As shown in FIG. 5, the set-up sensor 60 has a switch 62 that is turned ON / OFF by a sensor probe 61 that can move up and down, and is fixed to the tips of two horizontally extending plate springs 63. Yes. These leaf springs 63 are bent in the vertical direction, and are fixed to the upper end of the post 64. The post 64 is vertically and rotatably supported on the base 11. A shaft 65 on which a gear 65a is formed extends coaxially at the lower end of the post 64, and a pinion gear 66a of a motor 66 is coupled to the gear 65a. The post 64 is rotated by the operation of the motor 66, and the setup sensor 60 is rotated in the horizontal direction in accordance with this rotation.

  The set-up sensor 60 is located immediately above the chuck table 20 as shown by the solid line in FIG. 1 and is disposed at a detection position between the chuck table 20 and the grinding unit 30. It is retracted to the outside of the table 13. As shown in FIG. 5, when the setup sensor 60 is arranged on the chuck table 20, the sensor probe 61 comes close to the upper surface of the chuck table 20. From this state, the grinding unit 30 descends and the wheel mount 34 and the like are set up. When the upper surface of the sensor 60 is touched and pushed down, the sensor probe 61 moves relatively upward and the switch 62 is turned on. When the grinding unit 30 is raised, the switch 62 is turned off.

  As shown in FIG. 1, a two-bar link pickup robot 70 that moves up and down is installed in the center of the attachment / detachment area 11B. Around the pickup robot 70, a supply cassette 71, an alignment table 72, a supply arm 73, a recovery arm 74, a spinner type cleaning device 75, and a recovery cassette 76 are arranged counterclockwise as viewed from above. ing. The cassettes 71 and 76 accommodate the plurality of wafers 1 in a horizontal posture and in a stacked state at regular intervals in the vertical direction, and are set at predetermined positions on the base 11.

  The wafer 1 to be ground is first taken out from the supply cassette 71 by the pickup robot 70, placed on the alignment table 72, and determined at a certain position. Next, the wafer 1 is picked up from the alignment table 72 by the supply arm 73 and placed on the chuck table 20 waiting at the attachment / detachment position with the surface to be ground facing up. The wafer 1 is transferred to the primary grinding position and the secondary grinding position in this order by the rotation of the turntable 13 in the R direction, and the surface is ground as described above by the grinding unit 30 at these grinding positions.

  The wafer 1 for which the secondary grinding has been completed is returned to the attaching / detaching position by further rotating the turntable 13 in the R direction. The wafer 1 on the chuck table 20 returned to the attachment / detachment position is picked up by the recovery arm 74, transferred to the cleaning device 75, washed with water and dried. The wafer 1 cleaned by the cleaning device 75 is transferred and accommodated in the collection cassette 76 by the pickup robot 70.

[2] Self-grinding of chuck table The above is the configuration of the grinding apparatus 10, and when the wafer 1 is ground with this apparatus 10, the upper surface of the chuck table 20 (the upper surface of the frame body 21) by the grinding wheel 35 of the grinding unit 30. This grinding process called self-grinding, in which 21a and the upper surface 22a) of the suction area 22 are ground and processed flatly, is performed periodically. The self-grinding is performed to place the wafer 1 horizontally on the chuck table 20 and grinds the extremely hard adsorption area 22, so that the grindstone 37 of the grinding wheel 35 is made of metal or vitrified of about # 600. Used.

  Self-grinding of the chuck table 20 is performed by lowering the grinding unit 30 by the feed mechanism 43 while rotating the chuck table 20 and pressing the grindstone 37 of the rotating grinding wheel 35 against the upper surface of the chuck table 20. The self-grinding is performed so that the grinding outer peripheral edge of the grinding wheel 35 used by the grindstone 37 passes through the center of rotation of the chuck table 20 as shown in FIG. 4, whereby the entire upper surface of the chuck table 20 is ground flat. Is done.

  Self-grinding of the chuck table 20 is periodically performed every time a predetermined amount of the wafer 1 is ground, and setup is performed each time self-grinding is performed. In the grinding apparatus of the present embodiment, the setup and the interlock control based on the setup are performed as follows. The setup and interlock control are performed by a control unit (not shown).

[3] Embodiment of setup and interlock control (a) Method for setting the distance between the chuck table and the wheel mount (without grinding wheel)
As shown in FIG. 6, first, the grinding wheel 35 is not attached to the wheel mount 34 of the grinding unit 30, while the set-up sensor 60 is arranged at a detection position on the chuck table 20. Then, by lowering the grinding unit 30 by the feed mechanism 43, the mount surface 34a of the wheel mount 34 is brought closer to the setup sensor 60, and when the switch 62 is turned on by contact, the position recognition of the feed mechanism 43 is performed. The initial position Z1 of the grinding unit 30 recognized by the section is stored. At this time, the known height of the setup sensor 60 is set as a distance A between the chuck table upper surface (holding surface) 20 </ b> A and the mount surface 34 a of the wheel mount 34.

  Next, the thickness T of the wheel base 36 attached to the wheel mount 34 is subtracted from the value of the interval A to obtain an interval B between the grindstone fixing surface 36a of the wheel base 36 and the chuck table upper surface 20A. From the value of B and the initial position Z1 of the grinding unit, the limit position Z2 of the grinding unit immediately before the grindstone fixing surface 36a abuts on the chuck table upper surface 20A is obtained.

  Next, based on the thickness W of the wafer 1 measured by the thickness measurement gauge 50 and the limit position Z2 of the grinding unit 30, the position recognition unit of the feed mechanism 43 performs the grindstone fixing surface 36a of the wheel base 36 and the chuck table 20. A position Z3 where the upper wafer 1 abuts is recognized.

  The setup is thus completed. Thereafter, the grinding wheel 35 is attached to the mount surface 34a of the wheel mount 34, and grinding of a predetermined number of wafers 1 is started. When grinding, the grinding unit 30 fed toward the wafer 1 by the feeding mechanism 43 is controlled so as not to reach the last recognized position Z3. Thus, the grinding can be finished before the grindstone fixing surface 36a of the wheel base 36 comes into contact with the surface of the wafer 1.

(B) How to set the distance between chuck table and wheel mount (with grinding wheel)
As shown in FIG. 7, from the state where the wheel base 36 without a grindstone is attached to the wheel mount 34 of the grinding unit 30, the grinding unit 30 is lowered by the feed mechanism 43 and brought close to the setup sensor 60 arranged at the detection position. The initial position Z1 ′ of the grinding unit 30 recognized by the position recognition unit of the feed mechanism 43 is stored when the switch 62 is turned on by contact. At this time, the height of the setup sensor 60 is set as a distance B ′ between the chuck table upper surface 20A and the grindstone fixing surface 36a of the wheel base 36. Here, when the grindstone 37 is not fixed to the wheel base 36 and it is difficult to use such a wheel base 36, a dummy of the wheel base 36 (the same height as the wheel base 36 actually used) is used. May be attached to the wheel mount 34 instead of the wheel base 36.

  Next, the limit position Z2 of the grinding unit 30 immediately before the grindstone fixing surface 36a of the wheel base 36 abuts against the chuck table upper surface 20A is obtained from the values of the interval B 'and the initial position Z1'. Similarly to the above method, based on the thickness W of the wafer 1 measured by the thickness measuring gauge 50 and the limit position Z2 of the grinding unit 30, the position recognition unit of the feed mechanism 43 is used for the grindstone fixing surface of the wheel base 36. A position Z3 where 36a abuts on the wafer 1 on the chuck table 20 is recognized.

  The setup is thus completed. Thereafter, the wheel base 36 without a grindstone (or a dummy of the wheel base 36) is removed from the wheel mount 34 and replaced with a grinding wheel 35 with a grindstone that is normally used, and a predetermined number of wafers 1 are obtained. Start grinding. Also in this case, control is performed so that the grinding unit does not reach the position Z3 recognized last.

(C) Interval setting method using a block gauge As a method for recognizing the interval A between the chuck table upper surface 20A and the mount surface 34a of the wheel mount 34 or the interval B 'between the grindstone fixing surface 36a of the wheel base 36, There is also a method of using a block gauge 90 shown in FIG. The block gauge 90 has a flat bottom surface, and the top surface is formed in three steps from the lowest step portion 91 to the middle step portion 92 to the highest step portion 93 in a stepped manner. Each step 91-93 is parallel to the lower surface, and the respective heights 91a, 92a, 93a are accurately recognized in advance.

  FIG. 8 shows a state in which the distance A is set using the block gauge 90 in the “setting method of the distance between the chuck table and the wheel mount (without grinding wheel)” in (a). In this case, the block gauge 90 is placed on the chuck table upper surface 20A, the grinding unit 30 to which the grinding wheel 35 is not attached is lowered, and the mounting surface 34a of the wheel mount 34 is moved to an arbitrary step portion of the block gauge 90 ( In FIG. 8, the initial position Z1 of the grinding unit 30 recognized by the position recognition unit of the feed mechanism 43 is stored when approaching the upper surface of the stepped portion 91) and making contact. At this time, the height of the stepped portion with which the wheel mount 34 contacts (the height 91a of the stepped portion 91) is set as an interval A between the chuck table upper surface 20A and the mount surface 34a of the wheel mount 34. Thereafter, setup and interlock control are performed in the same manner as in the method (a).

  FIG. 9 shows a state in which the above-mentioned distance B ′ of the “setting method of the distance between the chuck table and the wheel mount (with grinding wheel)” in (b) is set using a block gauge 90. In this case, the grinding unit 30 in which the wheel base 34 without the grinding wheel (or the dummy wheel base) is attached to the wheel mount 34 is lowered, and the grinding wheel fixing surface 36 a of the wheel base 36 is placed on the chuck table 20. The initial position Z1 ′ of the grinding unit 30 recognized by the position recognition unit of the feed mechanism 43 is stored at the time of contact with an arbitrary step part (step part 91 in FIG. 9) of the block gauge 90. At this time, the height of the stepped portion in contact with the wheel base 36 (the height 91a of the stepped portion 91) is set as the interval B 'between the chuck table upper surface 20A and the grindstone fixing surface 36a of the wheel base 36. Thereafter, setup and interlock control are performed in the same manner as in the method (b).

(D) Method of Using the Reference Surface of the Turntable Next, setup and interlock control are performed using the reference surface 101 which is the upper end surface of the reference block 100 provided on the turntable 13 shown in FIG. An embodiment will be described.

  As shown in FIG. 11, the turntable 13 includes a turntable base 13a that is rotatably supported by the base 11, and a cover 13b that covers the top of the turntable base 13a. In FIG. 1, the cover 13a of the turntable 13 is shown. The chuck table 20 is fixed to the upper end of a cylindrical chuck table base 20a that is rotatably supported by the turntable base 13a. The chuck table 20 is located upward from a hole formed in the cover 13a of the turntable 13. It protrudes.

  The reference block 100 is fixed on the turntable base 13a, and its upper end protrudes upward from a hole formed in the cover 13b. The reference surface 101 is set to be horizontal similarly to the upper surface of the cover 13b, and is positioned above the cover 13b and below the chuck table upper surface 20A.

  The reference block 100 is arranged at a position where the probes 51a and 52a of the thickness measurement gauges 50 can come into contact with the reference surface 101 as the turntable 13 rotates. The height position can be measured. Further, the reference block 100 is arranged at a position where the setup sensor 60 at the detection position can come into contact with the reference surface 101 when the turntable 13 rotates.

A setup and interlock control method using the reference surface 101 is as follows.
The variation probe 52a of the thickness measurement gauge 50 is brought into contact with the chuck table upper surface 20A to measure the height position of the chuck table upper surface 20A. Subsequently, the turntable 13 is rotated to move the reference surface 101 to a position corresponding to the thickness measurement gauge 50, and the height position of the reference surface 101 is measured by bringing the variable probe 52a into contact with the reference surface 101. Then, the measured value of the reference surface 101 is subtracted from the measured value of the chuck table upper surface 20A, and the distance C between them is obtained and stored.

  Next, the turntable 13 is rotated to position the reference surface 101 below the grinding unit 30 and the setup sensor 60 is positioned at a detection position above the reference surface 101. Next, as in the method (a), the grinding unit 30 in which the grinding wheel 35 is not attached to the wheel mount 34 is lowered, the mount surface 34a of the wheel mount 34 contacts the setup sensor 60, and the switch 62 is turned ON. The initial position Z1 ″ of the grinding unit 30 recognized by the position recognition unit of the feed mechanism 43 at that time is stored. Here, the known height of the setup sensor 60 is set as the distance D between the chuck table upper surface 20A and the mount surface 34a of the wheel mount 34. The initial position Z1 ″ of the grinding unit 30 recognized by the position recognition unit of the grinding unit 30 at the distance D is a unique and immovable positional relationship of the grinding apparatus 10. Therefore, the value of the initial position Z1 ″ of the grinding unit 30 recognized by the position recognition unit at the distance D may be measured every time it is set up, but once measured, it is stored as device information. , It may be read out and used during setup.

  Next, the distance C is subtracted from the distance D to obtain the distance E between the mount surface 34a of the wheel mount 34 and the chuck table upper surface 20A. Then, from this distance E, the thickness T of the wheel base 36 of the grinding wheel 35 to be mounted is subtracted to obtain the distance B between the grindstone fixing surface 36a of the wheel base 36 and the chuck table upper surface 20A. From the value of the initial position Z1 ″, the limit position Z2 of the grinding unit 30 immediately before the grindstone fixing surface 36a of the wheel base 36 contacts the chuck table upper surface 20A is obtained.

  Thereafter, the method is similar to the method (a) described above. Based on the thickness W of the wafer 1 measured by the thickness measurement gauge 50 and the limit position Z2 of the grinding unit 30, the position recognition unit of the feed mechanism 43 is operated. The position Z3 where the grindstone fixing surface 36a of the wheel base 36 and the wafer on the chuck table abut is recognized, and the setup is completed. Thereafter, a grinding wheel 35 with a grindstone is attached to the mount surface 34a of the wheel mount 34, and grinding of a predetermined number of wafers 1 is started, and the grinding unit 30 is controlled so as not to reach the position Z3.

  Each of the above setup methods and the interlock control for preventing the wheel base 36 based on the setup from coming into contact with the wafer 1 depend on the height of the grindstone 37 of the grinding wheel 35 mounted on the mount surface 34a of the wheel mount 34. Instead, it is based on accurately grasping the distance between the grindstone fixing surface 36a of the wheel base 36 and the wafer 1 held on the chuck table 20.

  Meanwhile, another grinding wheel 35 having a different height of the grindstone 37 is used as the wheel mount 34 in place of the grinding wheel 35 in use between the self-grinding of the chuck table 20 and the next self-grinding. In some cases, the wheel 37 may be replaced or the used grinding wheel 37 may be dressed. In the past, interlock control was performed by re-entering the new wheel height into the equipment. However, if the input value of the wheel height is incorrect or you forget to enter it, If the control is not performed correctly and the grindstone disappears, there is a risk that the wheel base 36 contacts the wafer 1 or the chuck table 20.

  However, in the present embodiment, not the height of the grindstone 37 but the distance B between the grindstone fixing surface 36a of the wheel base 36 and the wafer 1 held on the chuck table 20 is obtained, and the wheel base 36 is determined based on the distance B. By recognizing the position Z3 of the grinding unit 30 in contact with the wafer 1, the risk that the wheel base 36 in which the grindstone 37 has disappeared contacts the wafer is reliably avoided. Further, the wheel base 36 is prevented from coming into contact with the chuck table 20 by recognizing the limit position Z2 of the grinding unit 30.

1 is a perspective view of a grinding apparatus that can suitably perform a grinding method according to an embodiment of the present invention. It is the (a) perspective view and (b) side view of the wafer ground by the grinding method which concerns on one Embodiment. It is the (a) perspective view and (b) side view which show the state which grinds the wafer surface with the grinding unit with which the grinding-work apparatus of one Embodiment comprises. It is a side view which shows the state which grinds the wafer surface with the grinding unit. It is a side view which shows the setup sensor which the grinding-work apparatus of one Embodiment comprises. It is a side view which shows the method of setting up a grinding unit using a setup sensor. It is a side view which shows the other method of setting up a grinding unit using a setup sensor. It is a side view which shows the method of setting up a grinding unit using a block gauge. It is a side view which shows the other method of setting up a grinding unit using a block gauge. It is a perspective view of a block gauge. It is a side view which shows the attachment structure of the reference | standard block which has a reference | standard surface used for the setup of a grinding unit.

Explanation of symbols

1 ... Semiconductor wafer (workpiece)
DESCRIPTION OF SYMBOLS 10 ... Grinding apparatus 20 ... Chuck table 20A ... Upper surface (holding surface) of chuck table
30 ... Grinding unit (grinding means)
32 ... Spindle shaft 34 ... Wheel mount 34a ... Mount surface 35 ... Grinding wheel 36 ... Wheel base 36a ... Whetstone fixing surface 37 ... Whetstone 43 ... Feed mechanism (feed means)
50 ... Thickness measurement gauge 101 ... Reference plane

Claims (4)

A chuck table having a holding surface for holding a plate-like workpiece;
Grinding means having a grinding wheel that is provided so as to be able to approach and separate from the holding surface of the chuck table and grinds a workpiece held on the holding surface by an approaching feeding operation;
A feed means having at least a grinding means position recognizing part for making the grinding means approach and separate from the holding surface and recognizing its position;
The grinding means includes a spindle shaft, and a wheel mount that is fixed to a tip of the spindle shaft and has a mount surface on which the grinding wheel is mounted.
The grinding wheel has a wheel base having a predetermined thickness having a grindstone fixing surface substantially parallel to the holding surface of the chuck table, and a grindstone that is fixed to the grindstone fixing surface of the wheel base and actually grinds the workpiece. A method of grinding a workpiece using a grinding apparatus comprising:
An interval A between the holding surface of the chuck table and the mount surface of the wheel mount is set to a predetermined interval, and an initial position Z1 of the grinding means recognized by the grinding means position recognition unit at this time is stored. ,
The wheel base thickness T is subtracted from the value of the distance A to obtain a distance B between the wheel base fixing surface of the wheel base and the holding surface of the chuck table, and the distance B and the grinding means From the value of the initial position Z1, obtain the limit position Z2 of the grinding means immediately before the grindstone fixing surface comes into contact with the holding surface,
Measure the thickness W of the work piece held on the chuck table,
Based on the limit position Z2 of the grinding means and the thickness W of the workpiece, the grinding means position recognition unit is held on the grindstone fixing surface of the wheel base and the holding surface of the chuck table. Recognize the position Z3 where the object abuts,
A grinding method characterized in that, based on the position Z3, grinding is terminated before the grindstone fixing surface of the grinding wheel comes into contact with the workpiece. A chuck table having a holding surface for holding a plate-like workpiece;
Grinding means having a grinding wheel that is provided so as to be able to approach and separate from the holding surface of the chuck table and grinds a workpiece held on the holding surface by an approaching feeding operation;
A feed unit having at least a feed unit for moving the grinding unit toward and away from the holding surface, and a grinding unit position recognition unit for recognizing the position of the grinding unit moved by the feed unit;
The grinding means includes a spindle shaft, and a wheel mount that is fixed to a tip of the spindle shaft and has a mount surface on which the grinding wheel is mounted.
The grinding wheel has a wheel base having a predetermined thickness having a grindstone fixing surface substantially parallel to the holding surface of the chuck table, and a grindstone that is fixed to the grindstone fixing surface of the wheel base and actually grinds the workpiece. A method of grinding a workpiece using a grinding apparatus comprising:
An interval B ′ between the holding surface of the chuck table and the grindstone fixing surface of the wheel base is set to a predetermined interval, and an initial position Z1 ′ of the grinding means recognized by the grinding means position recognition unit at this time. From the values of the interval B ′ and the initial position Z1 ′, the limit position Z2 of the grinding means immediately before the grindstone fixing surface comes into contact with the holding surface is set.
Measure the thickness W of the work piece held on the chuck table,
Based on the limit position Z2 of the grinding means and the thickness W of the workpiece, the grinding means position recognition unit is held on the grindstone fixing surface of the wheel base and the holding surface of the chuck table. Recognize the position Z3 where the object abuts,
A grinding method characterized in that, based on the position Z3, grinding is terminated before the grindstone fixing surface of the grinding wheel comes into contact with the workpiece. A chuck table base;
A chuck table supported by the chuck table base and having a holding surface for holding a plate-like workpiece;
Grinding means having a grinding wheel that is provided so as to be able to approach and separate from the holding surface of the chuck table and grinds a workpiece held on the holding surface by an approaching feeding operation;
A feed unit having at least a feed unit for moving the grinding unit toward and away from the holding surface, and a grinding unit position recognition unit for recognizing the position of the grinding unit moved by the feed unit;
The grinding means includes a spindle shaft, and a wheel mount that is fixed to a tip of the spindle shaft and has a mount surface on which the grinding wheel is mounted.
The grinding wheel has a wheel base having a predetermined thickness having a grindstone fixing surface substantially parallel to the holding surface of the chuck table, and a grindstone that is fixed to the grindstone fixing surface of the wheel base and actually grinds the workpiece. A method of grinding a workpiece using a grinding apparatus comprising:
A distance C between the holding surface of the chuck table and a reference surface set on the chuck table base is measured and stored, and the mount surface of the wheel mount which is a device-specific and stationary positional relationship in the grinding means The initial position Z1 '' of the grinding means recognized by the grinding means position recognition unit at the distance D between the wheel mount and the reference surface is stored or recognized, the distance C is subtracted from the distance D, Obtain the distance E between the mounting surface and the holding surface of the chuck table,
The wheel base thickness T is subtracted from the distance E to obtain a distance B between the grindstone fixing surface of the wheel base and the holding surface of the chuck table, and the distance B and the initial position of the grinding means From the value of Z1 ″, the limit position Z2 of the grinding means immediately before the grindstone fixing surface comes into contact with the holding surface is obtained,
Measure the thickness W of the work piece held on the chuck table,
Based on the limit position Z2 of the grinding means and the thickness W of the workpiece, the grinding means position recognition unit is held on the grindstone fixing surface of the wheel base and the holding surface of the chuck table. Recognize the position Z3 where the object abuts,
A grinding method characterized in that, based on the position Z3, grinding is terminated before the grindstone fixing surface of the grinding wheel comes into contact with the workpiece.   4. The grinding method according to claim 3, wherein the distance C is measured by a thickness measuring unit that measures the thickness of the workpiece.

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