JP2010089243A - Method for detecting origin height position of chuck table - Google Patents

Abstract

A method for detecting the height of an origin of a chuck table capable of detecting the height of the origin without causing an annular recess in a holding part of the chuck table is provided.
A measuring needle 151a of a first height detector 15a is brought into contact with an upper surface of a base portion 62 of a chuck table 6 from a retracted position to detect the height position of the base portion, and a second height detector 15b. The measuring needle 151b is brought into contact with the holding surface of the holding portion 61 of the chuck table from the retracted position to detect the height position of the holding portion, the measuring needle of the first height detector and the first The measuring needle of the height detector 2 is positioned at the retracted position, the chuck table is positioned at the next detection position by rotating the chuck table by a predetermined angle, the height position detecting process, and the chuck table positioning process. Repeatedly performing an average value of a plurality of height positions of the base portion and an origin height position calculating step of calculating an average value of the height positions of the holding portion.
[Selection] Figure 3

Description

  The present invention relates to a method for detecting an origin height position of a chuck table provided in a grinding apparatus for grinding a workpiece such as a semiconductor wafer.

  As is well known to those skilled in the art, in a semiconductor device manufacturing process, a semiconductor wafer on which a plurality of devices such as ICs and LSIs are formed is ground by a grinding device on a back surface before being divided into individual chips. The thickness is formed. A grinding apparatus for grinding a back surface of a semiconductor wafer includes a holding part having a holding surface for holding a wafer as a workpiece, a chuck table having a base part surrounding and supporting the holding part, and a holding part for the chuck table A grinding unit having a grinding wheel for grinding the wafer held on the holding surface, and a grinding feed mechanism for grinding and feeding the grinding unit in a direction perpendicular to the holding surface of the holding portion of the chuck table. .

Such a grinding apparatus is provided with a thickness measuring means for measuring the thickness of a wafer as a workpiece held on the holding surface of the holding portion constituting the chuck table. The thickness measuring means includes a first height detector for detecting the height position of the upper surface of the base portion constituting the chuck table, and an upper surface of the workpiece held by the holding surface of the holding portion constituting the chuck table. And a second height detector for detecting the height position. Then, the workpiece is processed with a difference between the height position of the upper surface of the workpiece detected by the second height detector and the height position of the upper surface of the base of the chuck table detected by the first height detector. We are looking for the thickness of things. (For example, see Patent Document 1)
JP 63-102872 A

  In such a thickness measuring means, in order to eliminate the influence of mechanical strain that occurs over time, the measuring needle of the first height detector is periodically brought into contact with the upper surface of the base portion of the chuck table. While detecting the height position of the origin of the base part, the measuring needle of the second height detector is brought into contact with the holding surface of the holding part of the chuck table to detect the height position of the origin of the holding part. Correct the difference between the height position (H2) of the origin of the upper surface of the holding unit detected by the height detector and the height position (H1) of the origin of the upper surface of the base detected by the first height detector. It is calculated as the value (S) (S = H1-H2). Then, when the thickness of the workpiece held on the holding surface of the holding portion constituting the chuck table is detected as described above, the influence of the mechanical distortion that occurs over time by correcting with the correction value (S). Is lost.

  Thus, the detection of the height position of the origin of the chuck table base and the origin of the chuck table holding portion is performed by the measurement needle of the first height detector and the measurement of the second height detector. Since the needle is brought into contact with the upper surface of the base of the chuck table and the holding surface of the holding part and the chuck table is rotated and detected at predetermined angles and the average value is calculated, this origin detection is performed a plurality of times. When implemented, an annular recess is formed in the upper surface of the base portion of the chuck table and the holding surface of the holding portion. In particular, when an annular dent is formed on the holding surface of the holding portion, there is a problem in that the annular dent is transferred to the ground workpiece and the quality of the workpiece is lowered.

  The present invention has been made in view of the above-described facts, and a main technical problem thereof is a chuck table that can detect the height position of the origin without causing an annular recess in the holding surface of the holding portion of the chuck table. It is to provide an origin height position detection method.

In order to solve the above main technical problem, according to the present invention, a chuck table having a holding part having a holding surface for holding a workpiece, a base part surrounding and supporting the holding part, and the chuck table Grinding means for grinding the workpiece held on the holding surface of the holding portion, and a grinding feed mechanism for grinding and feeding the grinding means in a direction perpendicular to the holding surface of the holding portion of the chuck table. A chuck table origin height position detecting method for detecting an origin height position of a chuck table in a grinding apparatus using a thickness measuring means comprising a first height detector and a second height detector. ,
The measuring needle of the first height detector is brought into contact with the upper surface of the base of the chuck table from the retracted position to detect the height position of the base, and the measuring needle of the second height detector is A height position detecting step of detecting the height position of the holding portion by contacting the holding surface of the holding portion of the chuck table from the retracted position;
Positioning of the chuck table for positioning the measuring needle of the first height detector and the measuring needle of the second height detector at the retracted position and rotating the chuck table by a predetermined angle to the next detecting position Process,
The height position detecting step and the chuck table positioning step are repeatedly performed to detect a plurality of height positions of the base portion and obtain an average value thereof, and to detect a plurality of height positions of the holding portion. Including an origin height position calculating step for obtaining the average value,
A chuck table origin height position detecting method is provided.

  According to the chuck table origin height position detecting method according to the present invention, the height position detecting step and the chuck table positioning step are repeatedly performed, and the height position detecting step is performed with the chuck table rotating intermittently and stopped. Therefore, even if the measuring needle of the second height detector comes into contact with the holding surface of the holding portion of the chuck table, an annular recess is not generated on the holding surface of the holding portion. Therefore, the annular recess is not transferred to the ground surface of the workpiece that has been held and held by the holding surface of the holding portion of the chuck table.

  Hereinafter, a preferred embodiment of a method for detecting an origin height position of a chuck table according to the present invention will be described in more detail with reference to the accompanying drawings.

FIG. 1 is a perspective view of a grinding apparatus for carrying out the method for detecting the origin height position of the chuck table according to the present invention.
The grinding device in the illustrated embodiment includes a device housing 2 having a substantially rectangular parallelepiped shape. A stationary support plate 21 is erected on the upper right end of the device housing 2 in FIG. Two pairs of guide rails 22, 22 and 23, 23 extending in the vertical direction are provided on the inner surface of the stationary support plate 21. A rough grinding unit 3 as a rough grinding means is mounted on one guide rail 22, 22 so as to be movable in the vertical direction, and a finish grinding unit 4 as a finish grinding means is vertically mounted on the other guide rail 23, 23. It is mounted to move in the direction.

  The rough grinding unit 3 includes a unit housing 31, a rough grinding wheel 33 attached to a wheel mount 32 rotatably attached to the lower end of the unit housing 31, and a wheel mount 32 attached to the upper end of the unit housing 31. An electric motor 34 that rotates in a direction indicated by an arrow 32a and a moving base 35 on which the unit housing 31 is mounted are provided. As is well known, the rough grinding wheel 33 includes an annular grindstone base and a plurality of grindstone segments mounted on the lower surface of the grindstone base, and the grindstone base is fastened to the wheel mount 32 with a fastening bolt screw 331. Installed by. Guided rails 351 and 351 are provided on the moving base 35, and the guided rails 351 and 351 are movably fitted to the guide rails 22 and 22 provided on the stationary support plate 21. The rough grinding unit 3 is supported so as to be movable in the vertical direction. The grinding apparatus in the illustrated embodiment includes a grinding feed mechanism 36 that feeds the moving base 35 of the rough grinding unit 3 along the guide rails 22 and 22. The grinding feed mechanism 36 includes a male screw rod 361 that is disposed on the stationary support plate 21 in a vertical direction parallel to the guide rails 22 and 22 and is rotatably supported, and a pulse motor 362 for rotationally driving the male screw rod 361. And a female screw block (not shown) that is mounted on the moving base 35 and is screwed with the male screw rod 361. By driving the male screw rod 361 forward and reverse by a pulse motor 362, the rough grinding unit 3 is moved up and down. It is moved in the direction (direction perpendicular to the holding surface of the chuck table described later).

  The finish grinding unit 4 is also configured in the same manner as the rough grinding unit 3, and includes a unit housing 41 and a finish grinding wheel 43 attached to a wheel mount 42 rotatably attached to the lower end of the unit housing 41. An electric motor 44 that is mounted on the upper end of the unit housing 41 and rotates the wheel mount 42 in a direction indicated by an arrow 42a, and a moving base 45 on which the unit housing 41 is mounted are provided. As is well known, the finish grinding wheel 43 includes an annular grindstone base and a plurality of grindstone segments mounted on the lower surface of the grindstone base, and the grindstone base is fastened to the wheel mount 42 with a fastening bolt screw 431. Installed by. Guided rails 451 and 451 are provided on the moving base 45, and the guided rails 451 and 451 are movably fitted to the guide rails 23 and 23 provided on the stationary support plate 21. The finish grinding unit 4 is supported so as to be movable in the vertical direction. The grinding apparatus in the illustrated embodiment includes a grinding feed mechanism 46 that moves the moving base 45 of the finish grinding unit 4 along the guide rails 23 and 23. The grinding feed mechanism 46 includes a male screw rod 461 that is disposed on the stationary support plate 21 in a vertical direction parallel to the guide rails 23 and 23 and is rotatably supported, and a pulse motor 462 for rotationally driving the male screw rod 461. And a female screw block (not shown) that is mounted on the moving base 45 and is screwed with the male screw rod 461. By driving the male screw rod 461 forward and backward by a pulse motor 462, the finish grinding unit 4 is moved up and down. It is moved in the direction (direction perpendicular to the holding surface of the chuck table described later).

  The grinding apparatus in the illustrated embodiment includes a turntable 5 disposed so as to be substantially flush with the upper surface of the apparatus housing 2 on the front side of the stationary support plate 21. The turntable 5 is formed in a relatively large-diameter disk shape, and is appropriately rotated in a direction indicated by an arrow 5a by a rotation driving mechanism (not shown). In the illustrated embodiment, three chuck tables 6 are arranged on the turntable 5 so as to be rotatable in a horizontal plane with a phase angle of 120 degrees. As shown in FIG. 2, the chuck table 6 includes a holding portion 61 having a holding surface for holding a workpiece, and a base portion 62 that surrounds and supports the holding portion 61. The base portion 62 is formed in a disk shape with a ceramic material, and a circular fitting recess 621 is provided on the upper surface, and the suction holding chuck constituting the holding portion 61 is fitted into the fitting recess 621. Yes. The suction holding chuck constituting the holding portion 61 is formed in a disk shape from a porous ceramic material, and is fitted into the fitting concave portion 621 of the base portion 62. Thus, the upper surface (holding surface) of the suction holding chuck constituting the holding portion 61 fitted in the fitting recess 621 of the base portion 62 is formed flush with the upper surface of the base portion 62, and the suction constituting the holding portion 61 is formed. A workpiece is placed on the upper surface (holding surface) of the holding chuck. The fitting recess 621 formed in the base 62 constituting the chuck table 6 is connected to a suction means (not shown). Accordingly, the work piece is placed on the upper surface (holding surface) of the suction holding chuck constituting the holding portion 61, and the suction means (not shown) is operated to operate the upper surface (holding surface) of the suction holding chuck constituting the holding portion 61. ) The workpiece can be sucked and held. The chuck table 6 configured in this way is rotated by a pulse motor 60.

  Returning to FIG. 1, the description will be continued. The three chuck tables 6 arranged on the turntable 5 have a workpiece loading / unloading area A and a rough grinding machining area B as the turntable 5 rotates as appropriate. , And the finish grinding area C and the workpiece loading / unloading area A.

  The illustrated grinding apparatus includes a first cassette 7 that is disposed on one side with respect to a workpiece loading / unloading area A and stocks a semiconductor wafer that is a workpiece before grinding, and a workpiece loading / unloading. Between the second cassette 8 which is disposed on the other side with respect to the area A and stocks the semiconductor wafer which is the workpiece after grinding, and between the first cassette 7 and the workpiece loading / unloading area A Centering means 9 for centering the workpiece to be disposed, a spinner cleaning means 11 disposed between the workpiece loading / unloading area A and the second cassette 8, and a first cassette 7 Workpiece transporting means 12 for transporting the semiconductor wafer, which is a work piece contained in the semiconductor wafer, to the centering means 9 and transporting the semiconductor wafer cleaned by the spinner cleaning means 11 to the second cassette 8, and centering Placed on means 9 Workpiece loading means 13 for transporting the aligned semiconductor wafer onto the chuck table 6 positioned in the workpiece loading / unloading area A, and on the chuck table 6 positioned in the workpiece loading / unloading area A A workpiece unloading means 14 for conveying the ground semiconductor wafer placed on the cleaning means 11 to the cleaning means 11 is provided. A plurality of semiconductor wafers W as workpieces are accommodated in the first cassette 7 with the protective tape T attached to the surface. At this time, the semiconductor wafer W is accommodated with the back surface facing upward.

  The illustrated grinding apparatus includes a first height detector 15a and a second height detection as means for measuring the thickness of a workpiece disposed adjacent to the rough grinding region B and the finish grinding region C, respectively. A container 15b is provided. The first height detector 15a and the second height detector 15b as means for measuring the thickness of the workpiece will be described with reference to FIG. The first height detector 15a and the second height detector 15b are respectively the measuring needles 151a and 151b, the working positions of the measuring needles 151a and 151b shown by solid lines in FIG. Actuating means 152a and 152b are provided. The actuating means 152a and 152b are constituted by, for example, electromagnetic solenoids, and when they are de-energized (OFF), the upper surfaces of the base 62 of the chuck table 6 as shown by a solid line in FIG. In addition, the measuring needle 151a is positioned at a working position that comes into contact with the holding surface (or the upper surface of the workpiece held on the holding surface of the holding portion 61), which is the upper surface of the holding portion 61. And 151b are operated to a retracted position separated from the operating position as indicated by a two-dot chain line in FIG. The first height detector 15a and the second height detector 15b configured as described above are each configured to hold and hold the upper surface of the base portion 62 of the chuck table 6 when the measuring needles 151a and 151b are positioned at the operation positions, respectively. The height position of the holding surface (or the upper surface of the workpiece held by the holding unit 61), which is the upper surface of the unit 61, is measured, and the measurement signal is sent to the control means described later.

  The illustrated grinding apparatus includes the control means 10 shown in FIG. The control means 10 includes a central processing unit (CPU) 101 that performs arithmetic processing according to a control program, a read-only memory (ROM) 102 that stores a control program and the like, and read / write random access as a storage means that stores arithmetic results and the like. A memory (RAM) 103, an input interface 104, and an output interface 105 are provided. Detection signals from the first height detector 15a, the second height detector 15b, and the like are input to the input interface 104 of the control means 10 configured as described above, and the rough grinding unit is output from the output interface 105. The control signal is output to the electric motor 34 of No. 3 and the electric motor 44 of the finish grinding unit 4, the pulse motor 362 of the grinding feed mechanism 36, the pulse motor 462 of the grinding feed mechanism 46, the pulse motor 60 that rotationally drives the chuck table, etc. To do.

The grinding apparatus in the illustrated embodiment is configured as described above, and the operation thereof will be described below.
Prior to starting the grinding operation, an origin height position detecting step for detecting the origin height position of the chuck table 6 is performed. This origin height position detection step is performed, for example, before starting the grinding work for the day. The origin height position detection step is first performed on the chuck table 6 positioned in the rough grinding area B as shown in FIG. Then, in a state where the chuck table 6 is stopped in the rough grinding area B, the control means 10 controls the operating means 152a and 152b of the first height detector 15a and the second height detector 15b. The measuring needles 151a and 151b are positioned at working positions that come into contact with the upper surface of the base portion 62 of the chuck table 6 and the upper surface (holding surface) of the suction holding chuck constituting the holding portion 61 as shown by the solid line in FIG. Thus, the first height detector 15a and the second height detector 15b in which the measuring needles 151a and 151b are positioned at the operation positions detect the height positions of the base 62 and the holding unit 61, respectively. The detection signal is sent to the control means 10 (height position detection step). The control means 10 to which the detection signals sent from the first height detector 15 a and the second height detector 15 b are input temporarily stores the height positions in a random access memory (RAM) 103.

  Next, the control means 10 controls the operating means 152a and 152b of the first height detector 15a and the second height detector 15b to retract the measuring needles 151a and 151b as indicated by a two-dot chain line in FIG. Position to position. Then, by driving the pulse motor 60, the chuck table 6 is rotated by, for example, 30 degrees in the direction indicated by the arrow 6a in FIG. 1 and positioned at the next detection position (chuck table positioning step).

  When the chuck table positioning step described above is performed and the chuck table 6 is positioned at the next detection position, the height position detection step is performed. Thus, the height position of the base 62 and the holding part 61 of the chuck table 6 can be measured every 30 degrees by performing the height position detecting step and the chuck table positioning step 12 times. Then, the control means 10 obtains the average value of the height position of each of twelve positions of the base 62 and the holding part 61 of the chuck table 6, and calculates the average value of each of the origin 62 height position (H 1) and the holding part 61. Is temporarily stored in the random access memory (RAM) 103 as the origin height position (H2) (origin height position calculation step). When the origin height position (H1) of the base portion 62 and the origin height position (H2) of the holding portion 61 are obtained in this way, the control means 10 determines the origin height position (H1) of the base portion 62 and the holding portion 61. Is obtained as a correction value (Sa) (Sa = H2−H1), and this correction value (Sa) is temporarily stored in the random access memory (RAM) 103.

  Further, the above-described height position detecting step, chuck table positioning step, and origin height position calculating step are performed on the chuck table 6 positioned in the finish grinding region C, and the origin height position (H1 ) And the origin height position (H 2) and the correction value (Sb) of the holding unit 61 are temporarily stored in the random access memory (RAM) 103. Next, the turn table 5 is rotated 120 degrees, and the above-described height position detection step, chuck table positioning step, and chuck table 6 positioned in the rough grinding region B and the finish grinding region C are respectively described above. An origin height position calculation step is performed, and the origin height position (H1) of the base portion 62, the origin height position (H2) of the holding portion 61, the correction value (Sa), and the correction value (Sb) are stored in a random access memory (RAM). ) 103 temporarily stored. Further, the turn table 5 is further rotated 120 degrees, and the above-described height position detection step, chuck table positioning step, and chuck table 6 positioned in the rough grinding region B and the finish grinding region C are respectively described above. An origin height position calculation step is performed, and the origin height position (H1) of the base portion 62, the origin height position (H2) of the holding portion 61, the correction value (Sa), and the correction value (Sb) are stored in a random access memory (RAM). ) The first height detector disposed in the rough grinding region B and the finish grinding region C with respect to the three chuck tables 6 disposed in the turntable 5 by temporarily storing in 103) The origin height position (H1) of the base portion 62 and the origin height position (H2) of the holding portion 61, the correction value (Sa), and the correction value (Sb) can be obtained by 15a and the second height detector 15b. .

  As described above, since the above-described height position detection step is performed in a state where the chuck table 6 is intermittently rotated and stopped, the measuring needle 151b of the second height detector 15b is held by the holding portion 61 of the chuck table 6. Even if it contacts the holding surface which is the upper surface of this, an annular dent is not generated in the holding surface of the holding portion 61.

If the origin height position detecting step for detecting the origin height position of the chuck table 6 is performed as described above, a grinding operation is performed.
That is, the semiconductor wafer W, which is a workpiece before grinding, accommodated in the first cassette 7 is conveyed by the vertical movement and forward / backward movement of the workpiece conveying means 12, and is placed on the centering means 9 and is placed in six pieces. Centered by radial movement toward the center of the pin 91. The semiconductor wafer W placed on the centering means 9 and centered is adsorbed to constitute a holding portion 61 of the chuck table 6 positioned in the workpiece loading / unloading area A by the turning operation of the workpiece loading means 14. It is mounted on the upper surface (holding surface) of the holding chuck. Then, a suction means (not shown) is operated to suck and hold the semiconductor wafer W on the upper surface (holding surface) of the suction holding chuck constituting the holding portion 61. Next, the turntable 5 is rotated 120 degrees in the direction indicated by the arrow 5a by a rotation drive mechanism (not shown), and the chuck table 6 on which the semiconductor wafer W is placed is positioned in the rough grinding region B.

  When the chuck table 6 on which the semiconductor wafer W is placed is positioned in the rough grinding area B in this way, the control means 10 activates the operation means 152a of the first height detector 15a as shown in FIG. By controlling, the measuring needle 151a is positioned at the working position where it contacts the upper surface of the base 62 of the chuck table 6. Further, as shown in FIG. 5, the control means 10 controls the actuating means 152a of the second height detector 15b to hold the measuring needle 151b on the upper surface (holding surface) of the holding portion 61 of the chuck table 6. It is positioned at the working position in contact with the upper surface (back surface) of the semiconductor wafer W, which is a workpiece.

  Next, the control means 10 drives the pulse motor 60 to rotate the chuck table 6 in the direction indicated by the arrow 6a in FIG. On the other hand, the control means 10 drives the electric motor 34 of the rough grinding unit 3 to rotate the rough grinding wheel 33 in the direction indicated by the arrow 32a in FIG. 1 at a rotational speed of, for example, 6000 rpm, and the pulse motor of the grinding feed mechanism 36. The rough grinding unit 3 is lowered (advanced) at a rough grinding feed rate of, for example, 3 μm / second by driving the forward rotation 362 forward. As a result, the grinding wheel 33 is pressed against the back surface (upper surface) of the semiconductor wafer W held on the holding surface of the chuck table 6 to perform rough grinding.

  In the rough grinding, the first height detector 15a and the second height detector 15b are used as thickness measuring means for the workpiece disposed adjacent to the rough grinding region B. The height position (Ha1) of the base 62 constituting the chuck table 6 and the height position (Ha2) of the upper surface (back surface) of the semiconductor wafer W that is a workpiece held on the upper surface (holding surface) of the holding portion 61 are It is input to the control means 10. Then, the control means 10 includes a height position signal (Ha2) of the semiconductor wafer W, a height position signal (Ha1) of the upper surface of the base 62 constituting the chuck table 6, and a protective tape attached to the surface of the semiconductor wafer W. Based on the thickness (t) of T and the correction value (Sa) stored in the random access memory (RAM) 103, the thickness (h) of the semiconductor wafer W is calculated. The thickness (h) of the semiconductor wafer W can be obtained by h = Ha2-Ha1-t-Sa. When the thickness (h) of the semiconductor wafer W reaches the first predetermined thickness (h1: for example, the finished thickness of the semiconductor wafer plus 50 μm), the control means 10 drives the pulse motor 362 of the grinding feed mechanism 36. Is stopped and spark-out grinding is performed for a predetermined time (for example, 15 seconds), and then the pulse motor 362 of the grinding feed mechanism 36 is driven in reverse to raise (retreat) the rough grinding unit 3 at a retracting speed of, for example, 10 mm / second. .

  The upper surface (holding surface) of the suction holding chuck constituting the holding portion 61 of the next chuck table 6 positioned in the workpiece loading / unloading area A during the rough grinding is described above. As described above, the semiconductor wafer W before grinding is placed. Then, by operating a suction means (not shown), the semiconductor wafer W is sucked and held on the upper surface (holding surface) of the suction holding chuck constituting the holding portion 61 of the chuck table 6. Next, the turntable 5 is rotated 120 degrees in the direction indicated by the arrow 5a, the chuck table 6 holding the semiconductor wafer W subjected to rough grinding is positioned in the finish grinding area C, and the semiconductor before grinding is processed. The chuck table 6 holding the wafer W is positioned in the rough grinding area B.

  Thus, on the back surface of the semiconductor wafer W before rough grinding held on the upper surface (holding surface) of the suction holding chuck constituting the holding portion 61 of the chuck table 6 positioned in the rough grinding processing area B, The rough grinding process is executed by the rough grinding unit 3. On the other hand, on the back surface 15b of the semiconductor wafer W which is held on the upper surface (holding surface) of the suction holding chuck constituting the holding portion 61 of the chuck table 6 positioned in the finish grinding area C and which has been subjected to rough grinding, a finish grinding unit is provided. 4 is used for finish grinding. That is, by driving the pulse motor 60, the chuck table 6 is rotated in the direction indicated by the arrow 6a at a rotational speed of, for example, 300 rpm. On the other hand, the control means 10 drives the electric motor 44 of the finish grinding unit 4 to rotate the finish grinding wheel 43 in the direction indicated by the arrow 42a in FIG. 1 at a rotational speed of, for example, 6000 rpm, and the pulse motor 462 of the grinding feed mechanism 46. Is driven forward to lower (advance) the finish grinding unit 4 at a finish grinding feed rate of, for example, 1 μm / second. As a result, the finish grinding wheel 43 is pressed against the back surface (upper surface) of the semiconductor wafer W held on the upper surface (holding surface) of the suction holding chuck constituting the holding portion 61 of the chuck table 63, and finish grinding is performed. .

  In the finish grinding, the chuck table 6 detected by the first height detector 15a and the second height gauge 17b as the thickness measuring means of the workpiece disposed adjacent to the finish grinding zone C. And the height position (Hb2) of the upper surface (back surface) of the semiconductor wafer W, which is a workpiece held on the upper surface (holding surface) of the holding portion 61, is the control means 10. Has been entered. Then, the control means 10 includes a height position signal (Hb2) of the semiconductor wafer W, a height position signal (Hb1) of the upper surface of the base 62 constituting the chuck table 6, and a protective tape attached to the surface of the semiconductor wafer W. Based on the thickness (t) of T and the correction value (Sb) stored in the random access memory (RAM) 103, the thickness (h) of the semiconductor wafer W is calculated. The thickness (h) of the semiconductor wafer W can be obtained by h = Hb2-Hb1-t-Sb. When the predetermined thickness (h) of the semiconductor wafer W reaches the second predetermined thickness (finished thickness of the semiconductor wafer), the control means 10 stops driving the pulse motor 462 of the grinding feed mechanism 46. After performing the spark-out grinding for a predetermined time (for example, 15 seconds), the pulse motor 462 of the grinding feed mechanism 46 is driven in reverse to raise (retreat) the finish grinding unit 4 at a retreat speed of, for example, 10 mm / second.

  As described above, rough grinding is performed on the semiconductor wafer W before rough grinding, which is held by the chuck table 6 positioned in the rough grinding area B, and is held by the chuck table 6 positioned in the finish grinding area C. When finish grinding is performed on the finished semiconductor wafer W, the turntable 5 is rotated 120 degrees in the direction indicated by the arrow 5a, and the chuck table 6 holding the finish-finished semiconductor wafer W is moved to the workpiece. Position in loading / unloading area A. The chuck table 6 holding the semiconductor wafer W rough-ground in the rough grinding zone B is held in the finish grinding zone C, and the chuck holding the semiconductor wafer W before grinding in the workpiece loading / unloading zone A. The table 6 is moved to the rough grinding area B, respectively.

  The chuck table 6 that has returned to the work-in / out area A via the rough grinding area B and the finish grinding area C releases the suction holding of the semiconductor wafer W that has been subjected to the finish grinding. Then, the finish-ground semiconductor wafer W on the chuck table 6 positioned in the workpiece loading / unloading area A is unloaded to the spinner cleaning unit 11 by the workpiece unloading unit 14. The semiconductor wafer W transported to the spinner cleaning means 11 is spin-dried while the grinding debris adhering to the back surface (surface to be ground) and the side surface is cleaned and removed. The semiconductor wafer W thus cleaned and spin-dried is transported and stored in the second cassette 8 by the workpiece transport means 12.

  In the above-described rough grinding and finish grinding, the upper surface (holding surface) of the holding portion 61 of the chuck table 6 that holds the semiconductor wafer W is not formed with an annular recess even if the above-described height position detection step is performed. The annular recess is not transferred to the back surface (surface to be ground) of the semiconductor wafer W held on the upper surface (holding surface) of the holding portion 61 of the chuck table 6 and subjected to rough grinding and finish grinding.

  As mentioned above, although this invention was demonstrated based on embodiment of illustration, this invention is not limited only to embodiment, A various deformation | transformation is possible in the range of the meaning of this invention. For example, in the illustrated embodiment, the present invention is applied to a grinding apparatus having a rough grinding unit and a finish grinding unit. However, the present invention is applied to a grinding apparatus having one grinding unit as a grinding means. May be.

The perspective view of the grinding device for enforcing the origin height position detection method of the chuck table by the present invention. The front view which fractures | ruptures and shows the principal part of the chuck table with which the grinding apparatus shown in FIG. 1 is equipped. Explanatory drawing which shows the relationship between the chuck table with which the grinding apparatus shown in FIG. 1 is equipped, and the 1st height detector and 2nd height detector as a workpiece thickness measuring means. FIG. 2 is a block diagram showing the configuration of control means provided in the grinding apparatus shown in FIG. 1. Explanatory drawing of the height position detection process in the origin height position detection method of the chuck table by this invention.

Explanation of symbols

2: equipment housing 3: rough grinding unit 33: grinding wheel 36: grinding feed means 4: finish grinding unit 43: grinding wheel 46: grinding feed means 5: turntable 6: chuck table 61: chuck table holding part 62: chuck Table base 7: First cassette 8: Second cassette 9: Temporary table 10: Control means 11: Spinner cleaning means 12: Workpiece conveying means 13: Workpiece carrying means 14: Workpiece carrying means 15a: first height detector 15b: second height detector
W: Semiconductor wafer
T: Protective tape

Claims (1)

Grinding a workpiece held on the holding surface of the holding portion of the chuck table, and a chuck table having a holding portion having a holding surface for holding the workpiece and a base portion surrounding and holding the holding portion. The first height position of the chuck table in the grinding apparatus comprising a grinding means and a grinding feed mechanism for grinding and feeding the grinding means in a direction perpendicular to the holding surface of the holding portion of the chuck table is set to the first height position. A chuck table origin height position detecting method for detecting using a thickness measuring means comprising a height detector and a second height detector,
The measuring needle of the first height detector is brought into contact with the upper surface of the base of the chuck table from the retracted position to detect the height position of the base, and the measuring needle of the second height detector is A height position detecting step of detecting the height position of the holding portion by contacting the holding surface of the holding portion of the chuck table from the retracted position;
Positioning of the chuck table for positioning the measuring needle of the first height detector and the measuring needle of the second height detector at the retracted position and rotating the chuck table by a predetermined angle to be positioned at the next detecting position Process,
The height position detecting step and the chuck table positioning step are repeatedly performed to detect a plurality of height positions of the base portion and obtain an average value thereof, and to detect a plurality of height positions of the holding portion. Including an origin height position calculating step for obtaining the average value,
A method for detecting the origin height position of a chuck table.

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