JP2010052075A - Grinder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grinder for improving productivity by reducing a time until a grinding surface of a grinding wheel contacts with a workpiece and grinding actually starts without imparting damage to the workpiece. <P>SOLUTION: A control means 10 includes a storage means for storing the thickness of the workpiece W before processing held at a chuck table 8. When moving a grinding unit 3 by operating a grinding unit feed mechanism 5 while supplying a grinding fluid to the grinding wheel 324 by operating a grinding fluid supply means 4, the control means operates the grinding unit feed mechanism at first feed speed to a feed speed changing position where an interval between the grinding surface of the grinding wheel and the workpiece before processing reaches a predetermined interval operates the grinding unit feed mechanism at second feed speed lower than the first feed speed but higher than grinding feed speed from the feed speed changing position to a grinding wheel rotation speed is reduced to a predetermined value, and feeds the grinding unit at the grinding feed speed to a grinding finishing position. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a grinding apparatus for grinding a workpiece such as a semiconductor wafer to a predetermined thickness.

  For example, in a semiconductor device manufacturing process, a plurality of regions are partitioned by dividing lines called streets arranged in a lattice pattern on the surface of a semiconductor wafer having a substantially disk shape, and ICs, LSIs, etc. are partitioned in these partitioned regions. The circuit is formed. Then, the semiconductor wafer is cut along the streets to divide the region where the circuit is formed to manufacture individual devices. The semiconductor wafer is generally formed to have a predetermined thickness by grinding the back surface of the semiconductor wafer with a grinding device before dividing into individual devices.

  A grinding apparatus for grinding the back surface of such a semiconductor wafer includes a chuck table having a holding surface for holding a workpiece and a grinding for grinding the workpiece held on the holding surface of the chuck table. A grinding unit having a wheel; and a grinding unit feeding mechanism for grinding and feeding the grinding unit in a direction perpendicular to the mounting surface of the chuck table.

  Since the semiconductor wafer is made of a brittle material such as silicon, there is a risk of damage if the grinding wheel suddenly contacts. Therefore, in the conventional grinding apparatus, when the grinding unit feed mechanism is operated to move the grinding unit in the grinding feed direction, 40-60 mm until the distance between the grinding surface of the grinding wheel and the workpiece reaches, for example, 15 μm. After the grinding unit feed mechanism is operated at a high speed of / sec and the distance between the grinding surface of the grinding wheel and the workpiece reaches, for example, 15 μm, the same grinding feed speed as the grinding conditions (for example, 0.1 to 0.3 μm) The grinding unit feed mechanism is operated at a very slow speed.

  However, as soon as the distance between the grinding surface of the grinding wheel and the workpiece reaches, for example, 15 μm, the grinding unit feed mechanism is operated at the very slow grinding feed speed (for example, 0.1 to 0.3 μm / sec) that is the same as the grinding conditions. Then, it takes 50 to 150 seconds for the grinding surface of the grinding wheel to come into contact with the workpiece and actually start grinding, resulting in a problem of poor productivity.

In order to solve such a problem, the grinding unit feed mechanism at the first feed speed (40 to 60 mm / second) until the feed speed change position where the distance between the grinding surface of the grinding wheel and the workpiece reaches a predetermined distance. Until a contact between the grinding surface of the grinding wheel and the workpiece is detected from the feed speed change position, a second feed speed (1.0 to 3 that is slower than the first feed speed but faster than the grinding feed speed). When the contact between the grinding surface of the grinding wheel and the work piece is detected, the grinding feed speed (for example, 0.2 to 0.4 μm / second) is reached to the grinding end position. A grinding device that operates a grinding unit feed mechanism is disclosed in Patent Document 1 below.
JP 2004-322247 A

  Thus, in the grinding device disclosed in Patent Document 1, the grinding surface of the grinding wheel and the workpiece are moved from the feed speed changing position where the distance between the grinding surface of the grinding wheel and the workpiece reaches a predetermined distance. The second feed rate for moving the grinding wheel until contact is detected is a rate at which the workpiece is not damaged even if the grinding surface of the grinding wheel contacts the workpiece (for example, 1.0 to 3.0 μm / second). ), But the grinding surface of the grinding wheel and the workpiece come into contact with the workpiece at a moving speed that is about 10 times faster than the grinding feed rate (for example, 0.2 to 0.4 μm / sec). May cause damage.

  The present invention has been made in view of the above-mentioned fact, and the main technical problem thereof is that the grinding surface of the grinding wheel comes into contact with the workpiece without actually damaging the workpiece, and grinding is actually started. An object of the present invention is to provide a grinding apparatus capable of improving productivity by reducing time.

In order to solve the main technical problem, according to the present invention, a chuck table having a holding surface for holding a workpiece and grinding for grinding the workpiece held on the holding surface of the chuck table. A grinding unit comprising a wheel and a rotational drive means for rotationally driving the grinding wheel, a grinding unit feed mechanism for moving the grinding unit in a direction perpendicular to the holding surface of the chuck table, the grinding wheel, and the grinding wheel In a grinding apparatus comprising a grinding water supply means for supplying grinding water to a workpiece held on a holding surface of a chuck table,
A grinding unit position detecting means for detecting a moving position of the grinding unit relative to the holding surface of the chuck table;
Grinding wheel rotation speed detecting means for detecting the rotation speed of the grinding wheel;
Control means for controlling the grinding unit feed mechanism based on detection signals from the grinding unit position detection means and the grinding wheel rotation speed detection means,
The control means includes storage means for storing the thickness of the workpiece before processing held on the holding surface of the chuck table, and operates the grinding water supply means to operate the grinding wheel and the chuck. When the grinding unit feed mechanism is operated while supplying the grinding water to the work piece held on the holding surface of the table and the grinding unit is moved in the grinding feed direction, the grinding surface of the grinding wheel and the pre-machining The grinding unit feed mechanism is operated at the first feed speed until the feed speed change position at which the distance between the workpiece and the workpiece reaches a predetermined distance, and is detected by the grinding wheel rotation speed detecting means from the feed speed change position. The grinding unit feed mechanism is operated at a second feed rate that is slower than the first feed rate but faster than the grinding feed rate until the grinding wheel rotation speed decreases to a predetermined value, and thereafter grinding to the grinding end position Allowed to operate the the grinding unit feeding mechanism Ri speed,
A grinding device is provided.

  Input means for inputting the thickness of the workpiece, the thickness of the workpiece before machining is input to the control means by the input means, and the control means sets the thickness of the workpiece before machining as described above. Store in storage means. Further, a height position detecting means for detecting the height of the holding surface of the chuck table and the height position of the workpiece before being held held on the holding surface of the chuck table is provided, and the control means detects the height position. The thickness of the workpiece is obtained based on the height position of the holding surface of the chuck table detected by the means and the height position of the workpiece before being held held on the holding surface of the chuck table. The thickness of the workpiece is stored in the storage means.

  The grinding apparatus according to the present invention is configured as described above, and the grinding unit feed mechanism is operated at the first feed speed until the feed speed change position at which the distance between the grinding surface of the grinding wheel and the workpiece before processing reaches a predetermined distance. The second speed which is slower than the first feed speed but faster than the grinding feed speed until the grinding wheel revolution speed detected by the grinding wheel revolution speed detecting means from the feed speed change position is lowered to a predetermined value by the resistance of the grinding water. Since the grinding unit feed mechanism is operated at the feed speed of the grinding wheel and thereafter the grinding unit feed mechanism is operated at the grinding feed speed up to the grinding end position, the grinding surface of the grinding wheel that is not involved in the grinding from the feed speed change position is subjected to the workpiece before processing. The time required to move the workpiece to the point just before contact with the workpiece can be greatly shortened. Moreover, since the operation at the second feed rate is up to the point where the grinding surface of the grinding wheel comes into contact with the workpiece before processing, the workpiece is not damaged.

  DESCRIPTION OF EMBODIMENTS Hereinafter, a preferred embodiment of a grinding apparatus configured according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a perspective view of a main part of a grinding apparatus constructed according to the present invention.
The grinding device includes a device housing 2 having a substantially rectangular parallelepiped shape. An upright wall 21 is erected on the upper right end of the device housing 2 in FIG. On the front side surface of the upright wall 21, a pair of guide rails 211, 211 extending in the vertical direction are provided. The grinding unit 3 is mounted on the guide rails 211 and 211 so as to be movable in the vertical direction (a direction perpendicular to a holding surface of a chuck table described later).

  The grinding unit 3 includes a moving base 31 and a spindle unit 32 attached to the moving base 31. Guided grooves 311 and 311 that are slidably fitted to the pair of guide rails 211 and 211 are formed on the rear side surface of the movable base 31. Thus, a support member 33 is attached to the front side surface of the movable base 31 slidably mounted on the pair of guide rails 211, 211 provided on the upright wall 21 by a plurality of fastening bolts 331. A spindle unit 32 is attached to the front side surface of the support member 33.

  The spindle unit 32 includes a spindle housing 321 mounted on the support member 33, a rotary spindle 322 rotatably disposed on the spindle housing 321, and servo serving as a rotation driving unit for driving the rotation spindle 322 to rotate. And a motor 320 (M1). The lower end of the rotary spindle 322 protrudes downward beyond the lower end of the spindle housing 321, and a wheel mount 323 is provided at the lower end of the rotary spindle 322. A grinding wheel 324 is attached to the lower surface of the wheel mount 323. The grinding wheel 324 includes an annular grindstone base 325 and a plurality of segments composed of a grinding grindstone 326 mounted on the lower surface of the grindstone base 325, and the grindstone base 325 is wheeled by a fastening screw 327. Mounted on the mount 323. The spindle unit 32 thus configured rotates the grinding wheel 324 in the direction indicated by the arrow when the servo motor 320 (M1) is driven.

  The grinding apparatus in the illustrated embodiment includes a grinding wheel rotational speed detecting means 34 (RD) for detecting the rotational speed of the grinding wheel 324 as shown in FIG. The grinding wheel rotational speed detection means 34 (RD) in the illustrated embodiment is configured to detect the rotational speed of the grinding wheel 324 by detecting the rotational speed of the servo motor 320 (M1). The grinding wheel rotation speed detection means 34 (RD) sends a detection signal to the control means 10 described later. Further, as shown in FIG. 2, the grinding apparatus in the illustrated embodiment includes grinding water supply means 4 for supplying grinding water to the workpiece held on the holding surface of the grinding wheel 324 and a chuck table described later. is doing. The grinding water supply means 4 includes a grinding water supply source 41, a pipe 42 connecting the grinding water supply source 41 and the spindle unit 32, and an electromagnetic opening / closing valve 43 (MV) disposed in the pipe 42. It has become. This electromagnetic on-off valve 43 (MV) is closed when it is de-energized (OFF), and is opened when energized (ON) so that the grinding water supply source 41 and the spindle unit 32 communicate with each other. It is configured. The electromagnetic on-off valve 43 (MV) is controlled by the control means 10 described later.

  Referring back to FIG. 1, the grinding apparatus in the illustrated embodiment moves the moving base 31, that is, the grinding unit 3 along the guide rails 211 and 211 to move the grinding wheel 324 to a chuck table holding surface to be described later. A grinding unit feeding mechanism 5 for grinding and feeding in a vertical direction is provided. The grinding unit feed mechanism 5 will be described with reference to FIG. The grinding unit feed mechanism 5 shown in FIG. 2 is provided with a male screw rod 51 disposed in the vertical direction parallel to the rear side surface of the upright wall 21 and a male screw rod 51 mounted on the rear side upper portion of the upright wall 21 to rotate. Pulse motor 52 (M2), a bearing block 53 that is attached to the lower part of the rear side of the upright wall 21 and rotatably supports the lower end of the male screw rod 51, and that is attached to the moving base 31 and screwed to the male screw rod 51. And the grinding unit 3 is moved downward by driving the pulse motor 52 (M2) in the forward direction, and the grinding unit 3 is moved upward by driving the pulse motor 52 (M2) in the reverse direction. Move it. The upright wall 21 has a long hole that allows the female screw block 54 to move.

  As shown in FIG. 2, the grinding apparatus in the illustrated embodiment includes a grinding unit position detecting means 6 for detecting a moving position of the grinding unit 3, that is, the grinding wheel 324 with respect to a holding surface of a chuck table described later. The grinding unit position detecting means 6 includes a linear scale 61 arranged in parallel with the male threaded rod 51 and fixed to the upright wall 21, and a detector 62 attached to the female thread block 54 and detecting a detected line of the linear scale 61. (LS). The detector 62 (LS) may be a well-known photoelectric detector, and generates a pulse signal in response to detection of the detected lines of the linear scale 61 (for example, formed at intervals of 1 μm). This pulse signal is sent to the control means described later.

  Referring back to FIG. 1, the description of the grinding apparatus in the illustrated embodiment includes a turntable 7 disposed so as to be substantially flush with the upper surface of the apparatus housing 2 on the front side of the upright wall 21. Yes. The turntable 7 is formed in a relatively large-diameter disk shape as shown in FIG. 1, and is appropriately rotated in a direction indicated by an arrow by a rotation driving mechanism (not shown). In the illustrated embodiment, two chuck tables 8 are arranged on the turntable 7 so as to be rotatable in a horizontal plane with a phase angle of 180 degrees. The chuck table 8 has a holding surface 81 for holding a workpiece on the upper surface, and can be rotated in a direction indicated by an arrow by a rotation driving means (not shown). The chuck table 8 is made of an appropriate porous material such as porous ceramics, and is connected to suction means (not shown). Accordingly, the workpiece placed on the holding surface 81 is sucked and held by selectively communicating the chuck table 8 with a suction means (not shown). The turntable 7 is configured so that the two chuck tables 8 are alternately positioned in a workpiece loading / unloading zone 8a and a grinding zone 8b which is a position below the grinding unit 3. A semiconductor wafer W as a workpiece before processing is placed on a holding surface 81 of the chuck table 8 positioned in the workpiece loading / unloading area 8a by a workpiece loading means (not shown). A protective tape T is attached to the surface of the semiconductor wafer W as a workpiece, and the protective tape T side is placed on the holding surface 81 of the chuck table 8.

  As shown in FIGS. 1 and 2, the grinding apparatus in the illustrated embodiment serves as a workpiece before processing that is held on the holding surface 81 of the chuck table 8 and on the holding surface 81 of the chuck table 8. A height gauge 9 (HG) as a height position detecting means for detecting the height position of the semiconductor wafer W is provided. The height gauge 9 (HG) sends the detection signal to the control means 10 described later.

  The grinding apparatus in the illustrated embodiment includes a control means 10 as shown in FIG. The control means 10 is constituted by a microcomputer, and 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, etc., and a read / write that stores arithmetic results and the like. A random access memory (RAM) 103, an input interface 104, and an output interface 105. Note that. The random access memory (RAM) 103 includes a height position ZC of the holding surface 81 of the chuck table 8, a height position ZW of the workpiece before processing held on the holding surface 81 of the chuck table 8, and a workpiece before processing. Functions as storage means for storing the thickness t1, the finished thickness t2 of the workpiece, and the like. The input interface 104 of the control means 10 configured as described above includes the grinding wheel rotation speed detection means 34 (RD), the detector 62 (LS) of the grinding unit position detection means 6, the height gauge 9 (HG), the workpiece. A signal is input from an input unit 110 (ID) or the like for inputting the thickness of the object. Further, the output interface 105 outputs a control signal to the servo motor 320 (M1), the pulse motor 52 (M2), the electromagnetic on-off valve 43 (MV) of the grinding water supply means 4, and the like.

The grinding apparatus in the illustrated embodiment is configured as described above, and the grinding operation will be described below.
Prior to grinding, the height position (ZC) of the holding surface 81 of the chuck table 8 is stored in advance in a random access memory (RAM) 103 of the control means 10. That is, the chuck table 8 is positioned in the grinding area 8 b, the grinding unit feeding mechanism 5 is operated to gradually lower the grinding unit 3, and the grinding surface (lower surface) of the grinding wheel 324 is the holding surface 81 of the chuck table 8. The control means 10 uses the position signal output from the detector 62 (LS) of the grinding unit position detecting means 6 in contact with the height position (ZC) of the holding surface 81 of the chuck table 8, that is, the origin of the grinding unit 3. The position is stored in a random access memory (RAM) 103. For the semiconductor wafer W as a workpiece, a design thickness t1 and a design finish thickness t2 before processing are input from the input means 110 (ID) to the control means 10, and this input data is controlled. It is stored in a random access memory (RAM) 103 of the means 10.

  The unprocessed semiconductor wafer W is placed on the holding surface 81 of the chuck table 8 positioned in the workpiece loading / unloading area 8a by a workpiece loading means (not shown). The unprocessed semiconductor wafer W placed on the holding surface 81 of the chuck table 8 is sucked and held on the chuck table 8 by suction means (not shown). Then, the turntable 7 is rotated 180 degrees in the direction indicated by the arrow A by a rotation drive mechanism (not shown), and the chuck table 8 on which the semiconductor wafer W before processing is placed is positioned in the grinding region 8b. If the chuck table 8 is positioned in the grinding area 8b, the height (H1) of the holding surface 81 of the chuck table 8 and the pre-processed semiconductor held on the holding surface 81 of the chuck table 8 by the height gauge 9 (HG). The height (H2) of the wafer W is detected, and the detection signal is input to the control means 10 and temporarily stored in the random access memory (RAM) 103. Then, the control means 10 determines the semiconductor wafer based on the height (H1) of the holding surface 81 of the chuck table 8 and the height (H2) of the unprocessed semiconductor wafer W held on the holding surface 81 of the chuck table 8. A pre-processing thickness t1 of W is obtained (t1 = H2−H1), and the pre-processing thickness t1 of the semiconductor wafer W thus obtained is stored in a random access memory (RAM) 103. The thickness t1 of the unprocessed semiconductor wafer W may be input by the input means 110 (ID) as described above. However, in consideration of variations in the thickness of the unprocessed semiconductor wafer W, the chuck table is required each time. Preferably, the height (H1) of the holding surface 81 of 8 and the height (H2) of the unprocessed semiconductor wafer W held on the holding surface 81 of the chuck table 8 are detected and obtained from the difference.

  As described above, when the chuck table 8 holding the unprocessed semiconductor wafer W is positioned in the grinding area 8b, the control means 10 operates a rotary drive mechanism (not shown) for driving the chuck table 8 to move the chuck table 8 to the arrow. For example, the servomotor 320 (M1) of the grinding unit 3 is driven to rotate the grinding wheel 324 in the direction indicated by arrow C at a rotational speed of 6000 rpm, for example, in the direction indicated by B. Further, the control means 10 energizes (ON) the electromagnetic on-off valve 43 (MV) of the grinding water supply means 4 to open the circuit, and makes the grinding water supply source 41 and the spindle unit 32 communicate with each other. As a result, the grinding water is supplied to the semiconductor wafer W held on the holding wheel 81 of the grinding wheel 324 and the chuck table 8 constituting the spindle unit 32. Next, the control means 10 drives the pulse motor 52 (M2) of the grinding unit feed mechanism 5 in the normal direction to operate the grinding unit 3 downward in the grinding feed direction, and the grinding surface of the grinding wheel 324 is on the chuck table 8. Grinding is performed in contact with the unprocessed semiconductor wafer W held on the substrate.

Here, the feed control of the grinding unit feed mechanism 5 will be described with reference to the flowchart shown in FIG.
When the operation of the grinding unit feed mechanism 5 in the grinding feed direction (downward) is started, the grinding unit 3 is positioned at a position above the chuck table 8 by a predetermined amount (home position: Z0). The control means 10 first supplies the grinding water to the grinding wheel 324 by energizing (ON) the electromagnetic on-off valve 43 (MV) of the grinding water supply means 4 to open the circuit, and in step S1, the grinding unit feed mechanism 5 is provided. The pulse motor 52 (M2) is normally driven to lower the feed speed (ZV) of the grinding unit 3, that is, the grinding wheel 324, at a high speed of the first feed speed V1 (for example, 10 to 50 mm / sec).

  If the grinding unit 3, that is, the grinding wheel 324 is lowered at the first feed speed V1 (for example, 10 to 50 mm / second) in step S1, the control means 10 proceeds to step S2 and the detector of the grinding unit position detection means 6 is detected. It is checked whether or not the movement position (Z) detected by 62 (LS) has reached the feed speed change position Z1. This feed speed change position Z1 is determined from the upper surface of the unprocessed semiconductor wafer W held on the holding surface 81 of the chuck table 8, that is, the height position ZW (ZC + t1) of the unprocessed semiconductor wafer W. ) Is set at a position corresponding to the predetermined distance L. The predetermined distance L is determined when the grinding unit 3 is lowered at the first feed speed V1 (for example, 10 to 50 mm / sec) and the feed speed (ZV) is rapidly decelerated. The distance at which the grinding surface (lower surface) of the grinding wheel 324 does not come into contact with the unprocessed semiconductor wafer W due to bending is set to, for example, 10 to 20 μm. Accordingly, the feed speed change position Z1 is a value (Z1 = ZC + t1 + L) obtained by adding the height position ZC of the holding surface 81 of the chuck table 8, the thickness t1 of the unprocessed semiconductor wafer W, and the predetermined distance L.

  If the movement position (Z) does not reach the feed speed change position Z1 in step S2, the control means 10 returns to the above step S1 and at the first feed speed V1 (for example, 10 to 50 mm / sec) of the grinding unit 3. Continue to descend. On the other hand, if the movement position (Z) reaches the feed speed change position Z1 in step S2, the control means 10 proceeds to step S3 and the rotational speed of the forward drive of the pulse motor 52 (M2) of the grinding unit feed mechanism 5 is reached. The feed rate (ZV) of the grinding unit 3, that is, the grinding wheel 324 is slower than the first feed rate V1 (for example, 10 to 50 mm / second), but the grinding feed rate V3 (for example, 0.1 to 0.2 μm / second). ) Faster second feed speed V2 (for example, 1.0 to 2.0 μm / second).

  If the grinding unit 3, that is, the grinding wheel 324 is lowered at the second feed speed V2 (for example, 1.0 to 3.0 μm / second) in step S3, the control means 10 proceeds to step S4 and rotates the grinding wheel 324. It is checked whether the speed (RV) has decreased to a predetermined value (RV1). That is, the control means 10 determines whether or not the rotational speed (RV) of the grinding wheel 324 has decreased to a predetermined value (RV1) based on the detection signal from the grinding wheel rotational speed detection means 34 (RD). . Since the rotational speed (RV) of the grinding wheel 324 decreases temporarily because the resistance of the grinding water increases as the distance between the grinding surface (lower surface) of the grinding wheel 324 and the semiconductor wafer W decreases. By detecting that the rotational speed (RV) of the wheel 324 has decreased to a predetermined value (RV1), it is possible to confirm that the grinding surface (lower surface) of the grinding wheel 324 has just reached the point where it contacts the semiconductor wafer W. it can. The predetermined value (RV1) is set to 5950 rpm, for example, when the rotational speed of the grinding wheel 324 is set to 6000 rpm as described above.

  If the rotational speed (RV) of the grinding wheel 324 has not decreased to the predetermined value (RV1) in step S4, the control means 10 returns to step S3 and the second feed speed V2 (for example, 1.0) of the grinding unit 3. Continue to descend at ˜3.0 μm / sec). On the other hand, if the rotational speed (RV) of the grinding wheel 324 decreases to the predetermined value (RV1) in step S4, the control means 10 has reached the point where the grinding surface (lower surface) of the grinding wheel 324 is in contact with the semiconductor wafer W. In step S5, the rotational speed of the forward drive of the pulse motor 52 (M2) of the grinding unit feed mechanism 5 is further reduced, and the feed speed (ZV) of the grinding unit 3, that is, the grinding wheel 324, is set as the grinding condition. The grinding feed is changed to the same grinding feed speed V3 (for example, 0.1 to 0.2 μm / second).

  If the grinding unit 3, that is, the grinding wheel 324 starts grinding feed at a grinding feed speed V 3 (for example, 0.1 to 0.2 μm / second) in step S 5, the control means 10 proceeds to step S 6 and the semiconductor wafer W is set to a predetermined value. It is checked whether it has been ground to the finished thickness t2. Whether or not the semiconductor wafer W has been ground to the finished thickness t2 is determined by whether the moving position (Z) detected by the detector 62 (LS) of the grinding unit position detecting means 6 has reached the grinding end position Z2. Depending on whether or not. That is, the grinding end position Z2 is set to a value (Z2 = ZC + t2) obtained by adding the height position ZC of the holding surface 81 of the chuck table 8 and the finished thickness t2 of the semiconductor wafer W.

  If the moving position (Z) of the grinding unit 3, that is, the grinding wheel 324 does not reach the grinding end position Z2 in step S6, the control means 10 determines that the semiconductor wafer W has not been ground to the finished thickness t2, and the above step Returning to S5, the grinding feed at the grinding feed speed V3 (for example, 0.1 to 0.2 μm / second) of the grinding unit 3 is continuously executed. On the other hand, if the moving position (Z) of the grinding unit 3, that is, the grinding wheel 324 reaches the grinding end position Z2 in step S6, the control means 10 determines that the semiconductor wafer W has been ground to the finished thickness t2, and step S7. Then, the pulse motor 52 (M2) of the grinding unit feed mechanism 5 is driven in reverse. As a result, the grinding unit feed mechanism 5 raises the grinding unit 3, that is, the grinding wheel 324. The moving speed for raising the grinding unit 3 may be equal to or faster than the first feed speed V1 (for example, 10 to 50 mm / second).

  If the pulse motor 52 (M2) is reversely driven in step S7, the control means 10 proceeds to step S8, and the movement position (Z) detected by the detector 62 (LS) of the grinding unit position detection means 6 is the home position. Check whether the position (Z0) has been reached. If the home position (Z0) has not been reached in step S8, the control means 10 returns to step S7 and continues the reverse drive of the pulse motor 52 (M2). If the movement position (Z) reaches the home position (Z0) in step S8, the control means 10 determines that the grinding unit 3 has reached the predetermined home position (Z0), and proceeds to step S9 to feed the grinding unit. The pulse motor 52 (M2) of the mechanism 5 is stopped (OFF).

  In step S7, when the pulse motor 52 (M2) of the grinding unit feed mechanism 5 is reversely driven to raise the grinding unit 3, the control means 10 stops driving the servo motor 320 (M1) of the grinding unit 3. Then, the electromagnetic on-off valve 43 (MV) of the grinding water supply means 4 is de-energized (OFF) and closed to stop the supply of the grinding water to the grinding wheel 324 and stop the rotation of the chuck table 8. Then, the turntable 7 is rotated 180 degrees in the direction indicated by the arrow A, and the chuck table 8 on which the processed semiconductor wafer W is placed is positioned in the workpiece loading / unloading area 8a.

  As described above, in the illustrated embodiment, the grinding unit 3 is operated from the home position (Z0) at the first feed speed V1 (for example, 10 to 50 mm / second) during grinding, and the grinding surface (lower surface) of the grinding wheel 324 is operated. ) Reaches the feed speed change position Z1 above a predetermined distance L (for example, 10 to 20 μm) from the upper surface of the unprocessed semiconductor wafer W placed on the holding surface 81 of the chuck table 8, the rotational speed (RV) of the grinding wheel 324 is reached. ) Is lower than the first feed speed V1 (for example, 10 to 50 mm / second) but is faster than the grinding feed speed V3 (for example, 0.1 to 0.2 μm / second) until it decreases to a predetermined value (RV1). Since it operates at a speed V2 (for example, 1.0 to 2.0 μm / second), the grinding surface (lower surface) of the grinding wheel 324 not involved in grinding from the feed speed change position Z1 is the semiconductor wafer W before processing. The time required to move until immediately before the contact can be significantly reduced. In addition, since the operation at the second feed rate V2 (for example, 1.0 to 2.0 μm / second) is just before the ground surface (lower surface) of the grinding wheel 324 contacts the unprocessed semiconductor wafer W, the semiconductor wafer W It will not damage you. Thus, in the above embodiment, the time not involved in grinding can be shortened without damaging the semiconductor wafer W.

The principal part perspective view which shows one Embodiment of the grinding device comprised by this invention. The schematic block diagram of the grinding device comprised by this invention. The flowchart which shows the operation | movement procedure of the control means with which the grinding | polishing apparatus shown in FIG. 2 is equipped.

Explanation of symbols

2: Device housing 3: Grinding unit 31: Moving base 32: Spindle unit 33: Support member 320: Servo motor (M1)
321: Spindle housing 322: Rotating spindle 323: Wheel mount 324: Grinding wheel 34: Grinding wheel rotational speed detection means (RD)
4: Grinding water supply means 41: Grinding water supply source 43: Electromagnetic on-off valve (MV)
5: Grinding unit feed mechanism 51: Male thread rod 52: Pulse motor (M2)
53: Bearing block 54: Female thread block 6: Grinding unit position detection means 61: Linear scale 62: Detector (LS)
7: Turntable 8: Chuck table 9: Height gauge (HG)
10: Control means 110: Input means (ID)
W: Semiconductor wafer
T: Protective tape

Claims (3)

A chuck table having a holding surface for holding a workpiece, a grinding wheel for grinding the workpiece held on the holding surface of the chuck table, and a rotation driving means for rotating the grinding wheel are provided. A grinding unit, a grinding unit feed mechanism that moves the grinding unit in a direction perpendicular to the holding surface of the chuck table, and a workpiece held on the holding surface of the grinding wheel and the chuck table. In a grinding apparatus comprising a grinding water supply means for supplying water,
A grinding unit position detecting means for detecting a moving position of the grinding unit relative to the holding surface of the chuck table;
Grinding wheel rotation speed detecting means for detecting the rotation speed of the grinding wheel;
Control means for controlling the grinding unit feed mechanism based on detection signals from the grinding unit position detecting means and the grinding wheel rotation speed detecting means,
The control means includes storage means for storing the thickness of the workpiece before processing held on the holding surface of the chuck table, and operates the grinding water supply means to operate the grinding wheel and the chuck. When the grinding unit feed mechanism is operated while supplying the grinding water to the work piece held on the holding surface of the table and the grinding unit is moved in the grinding feed direction, the grinding surface of the grinding wheel and the pre-machining The grinding unit feed mechanism is operated at the first feed speed until the feed speed change position at which the distance between the workpiece and the workpiece reaches a predetermined distance, and is detected by the grinding wheel rotation speed detecting means from the feed speed change position. The grinding unit feed mechanism is operated at a second feed rate that is slower than the first feed rate but faster than the grinding feed rate until the grinding wheel rotation speed decreases to a predetermined value, and thereafter grinding to the grinding end position Allowed to operate the the grinding unit feeding mechanism Ri speed,
A grinding apparatus characterized by that.   Input means for inputting the thickness of the workpiece; the thickness of the workpiece before processing is input to the control means by the input means; and the control means determines the thickness of the workpiece before processing. The grinding apparatus according to claim 1, which is stored in a storage unit.   Height position detecting means for detecting the height position of the holding surface of the chuck table and the height position of the workpiece before being held held on the holding surface of the chuck table is provided, and the control means includes the height position. Determining the thickness of the workpiece based on the height position of the holding surface of the chuck table detected by the detecting means and the height position of the workpiece before processing held on the holding surface of the chuck table; The grinding apparatus according to claim 1, wherein the obtained thickness of the workpiece is stored in the storage means.

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