JP2018140458A - Grinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grinder which can simply mount dress means.SOLUTION: A grinder 1 includes: a wafer chuck 3 holding a wafer W; grinding means 2 having a ground grindstone 21 grinding the wafer W; and a dress unit 8 dressing the ground grindstone 21. The dress unit 8 includes a base member 82c having a vacuum suction groove 82e which vacuum-sucks a rear face 81c of a dress board 81.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a grinding apparatus, and more particularly to a grinding apparatus provided with dressing means for dressing a grinding wheel.

  In the field of semiconductor manufacturing, in order to form a semiconductor wafer such as a silicon wafer (hereinafter referred to as “wafer”) into a thin film, back surface grinding for grinding the back surface of the wafer is performed.

  As a grinding apparatus that performs backside grinding of a wafer, Patent Document 1 discloses a device that includes a holding unit that holds a wafer, a grinding wheel that grinds the wafer, and a dress member that dresses the grinding wheel. . The dress member is configured to rotate about the dress axis.

  In such a grinding apparatus, when the dress member is pressed against the grinding wheel, the abrasive grains are detached from the grinding wheel to generate a self-generated blade. Since the dressing member is pressed parallel to the grinding wheel, the grinding surface of the grinding wheel is dressed so as to be leveled horizontally. The wafer can be ground into a flat shape by pressing a grinding wheel having a flat grinding surface against the wafer. Thereby, even if it is a difficult-to-cut material such as sapphire, the wafer can be continuously ground without causing the surface burn of the wafer due to wear of the abrasive grains of the grinding wheel.

Japanese Patent No. 5815150

  However, in the grinding apparatus described in Patent Document 1 as described above, it is necessary to replace the dress member after dressing the dress member for a predetermined time, but when attaching the dress member to the dress shaft, There is a possibility that grinding scraps may be caught between the two, and it is necessary to visually check whether there is a mounting failure in which the dress member is mounted in an incorrect posture.

  Then, the technical subject which should be solved arises that attachment of a dressing means is simply performed, and this invention aims at solving this subject.

  The present invention has been proposed in order to achieve the above-mentioned object, and the invention according to claim 1 is a grinding system comprising holding means for holding a wafer and grinding means having a grinding wheel for grinding the wafer. There is provided a grinding apparatus comprising a dressing means for dressing the grinding wheel and a dressing means holding mechanism for detachably vacuum-sucking the dressing means.

  According to this configuration, the dressing means can be indirectly confirmed that there is no grinding waste between the dressing means and the dressing means holding mechanism by being vacuum-adsorbed to the dressing means holding mechanism without leaking the vacuum, The dressing means can be attached to the dressing means holding mechanism in a correct posture. Compared to the case where the dressing means is mechanically fixed to the dressing means holding mechanism with a bolt or the like, the dressing means can be simply attached to the dressing means holding mechanism simply by placing the dressing means on the dressing means holding mechanism and vacuum-adsorbing the dressing means. Can do.

  According to a second aspect of the present invention, in addition to the configuration of the first aspect of the invention, the dressing means holding mechanism provides a grinding apparatus that sucks the back surface of the dressing means.

  According to this configuration, since the back surface of the dressing unit is vacuum-sucked by the dressing unit holding mechanism, the dressing unit is restrained by sliding in the radial direction, so that the pressing force acting on the dressing unit is dispersed in the radial direction. Distortion in the thickness direction is reduced, and the grinding wheel can be dressed with high accuracy. Further, since the back surface of the dressing means is vacuum-adsorbed, even when the dressing means is deformed while maintaining its volume by the pressing force acting on the dressing means in the vertical direction, the dressing means moves in the radial direction. Is prevented and distortion in the thickness direction of the dressing means is reduced, so that the grinding wheel can be dressed with high precision.

  According to a third aspect of the present invention, in addition to the configuration of the second aspect of the present invention, there is provided a grinding apparatus provided with positioning means for positioning the dressing means at a predetermined position with respect to the dress holding mechanism.

  According to this configuration, by using the positioning means, the dressing means can be accurately and simply attached to the dressing means holding mechanism.

  According to a fourth aspect of the present invention, in addition to the configuration of the third aspect of the invention, the positioning means includes a positioning pin that projects from one of opposing surfaces of the dressing means and the dressing means holding mechanism, There is provided a grinding apparatus comprising: a recess provided on the other of the facing surfaces of the dressing unit and the dressing unit holding mechanism that are opposed to each other and engageable with the positioning pin.

  According to this configuration, the positioning means can be attached to the dressing means holding mechanism accurately and simply by engaging the positioning pin with the recess.

  According to a fifth aspect of the invention, in addition to the configuration of the first aspect of the invention, a vacuum suction groove connected to a vacuum source is formed on the facing surface of the dressing means holding mechanism facing the dressing means. A grinding device is provided.

  According to this configuration, even if the grinding waste is present between the dressing means and the dressing means holding mechanism, the dressing means is not leaked by vacuum because the grinding waste is sucked into the vacuum suction groove. Vacuum suction can be performed on the means holding mechanism.

  The present invention can indirectly confirm that there is no grinding dust between the dressing means and the dressing means holding mechanism by the vacuum suction of the dressing means without leaking the dressing means. Can be attached to the dress means holding mechanism in a correct posture. Further, compared to the case where the dressing means is fixed to the dressing means holding mechanism using a bolt or the like, the dressing means can be simply attached to the dressing means holding mechanism simply by placing the dressing means on the dressing means holding mechanism and vacuum-adsorbing the dressing means. it can.

The side view which shows the grinding device which concerns on one Example of this invention. The top view of the grinding apparatus shown in FIG. FIG. 3 is a partially cutaway side view taken along the line II of FIG. 2 showing the internal structure of the wafer chuck. The top view which shows a dress unit. The IIII partial cutaway side view of FIG. 4 which shows the internal structure of a dress unit and a dress unit inclination mechanism. The longitudinal cross-sectional view which shows the internal structure of a part of dress unit. The schematic diagram which shows a mode that a grinding wheel is dressed with a dress unit. The schematic diagram which shows distribution of the pressing force which acts on a dress unit. The schematic diagram which shows a mode that a deformation | transformation of the dressboard by pressing force is suppressed.

  A grinding apparatus according to the present invention is a grinding apparatus comprising a holding means for holding a wafer and a grinding means having a grinding wheel for grinding the wafer in order to achieve the purpose of simply attaching the dressing means. This is realized by including a dressing means for dressing the grinding wheel and a dressing means holding mechanism for detachably vacuum-sucking the dressing means.

  Hereinafter, a grinding apparatus 1 according to an embodiment of the present invention will be described with reference to the drawings. In the following examples, when referring to the number, numerical value, quantity, range, etc. of the constituent elements, the specific number is used unless otherwise specified and clearly limited to a specific number in principle. It is not limited, and it may be a specific number or more.

  In addition, when referring to the shapes and positional relationships of components, etc., those that are substantially similar to or similar to the shapes, etc., unless otherwise specified or otherwise considered in principle to be apparent. Including.

  In addition, the drawings may be exaggerated by enlarging characteristic portions in order to make the features easy to understand, and the dimensional ratios and the like of the constituent elements are not always the same. In the cross-sectional view, hatching of some components may be omitted in order to facilitate understanding of the cross-sectional structure of the components. In this embodiment, the terms “upper” and “lower” correspond to the upper and lower parts in the vertical direction.

  FIG. 1 is a side view showing a basic configuration of a grinding apparatus 1 in which the dress unit 8 is omitted. FIG. 2 is a plan view of the grinding apparatus 1. 3 is a partially cutaway side view taken along the line II of FIG. FIG. 4 is a plan view showing the dress unit 8. FIG. 5 is a partially cutaway side view taken along the line II-II in FIG. 4 showing the internal structure of the dress unit 8 and the dress unit tilting mechanism 9. FIG. 6 is a longitudinal sectional view showing a part of the internal structure of the dress unit 8.

  The grinding apparatus 1 forms the thin film by grinding the back surface of the wafer W with the grinding means 2. The grinding means 2 includes a grinding wheel 21, a spindle 22 attached to the tip of the grinding wheel 21, and a spindle feed mechanism 23 that sends the spindle 22 in the vertical direction V.

  The grinding wheel 21 is horizontally attached to the tip of the spindle 22. When the grinding wheel 21 is pressed against the wafer W, the wafer W is ground.

  The spindle 22 rotates the grinding wheel 21 around the rotation axis a1 along the rotation direction C1 by a motor (not shown).

  The spindle feed mechanism 23 includes two linear guides 23 a that connect the column 4 and the spindle 22, and a known ball screw slider mechanism (not shown) that raises and lowers the spindle 22 in the vertical direction V.

  Below the grinding means 2, a wafer chuck 3 as a holding means is arranged. In order to continuously grind a plurality of wafers W, the grinding apparatus 1 includes a plurality of wafer chucks 3. The plurality of wafer chucks 3 are arranged at predetermined intervals on the circumference around the rotation axis of the index table 5.

  The wafer chuck 3 includes a chuck 31 and an air bearing 32.

  The chuck 31 has an adsorbent (not shown) made of a porous material such as alumina embedded in the upper surface. The wafer chuck 3 includes a conduit (not shown) that extends through the chuck 31 and the air bearing 32 to the surface of the chuck 31. The pipe line is connected to a vacuum source, a compressed air source, and a water supply source (not shown) via a rotary joint (not shown) connected to the rotor 32a of the air bearing 32. When the vacuum source is activated, the wafer W placed on the chuck 31 is sucked and held on the chuck 31. Further, when the compressed air source or the water supply source is activated, the adsorption between the wafer W and the chuck 31 is released.

  The air bearing 32 includes a rotor 32a that can rotate about the rotation axis a2, and a stator 32b that is disposed on the outer periphery of the rotor 32a. The rotor 32a and the chuck 31 are fixed with bolts (not shown). The rotor 32a is connected to the rotary joint, and rotates the chuck 31 along the rotation direction C2 around the rotation axis a2. A predetermined gap (air gap) is provided between the rotor 32a and the stator 32b, and the rotor 32a rotates without contact with the stator 32b by supplying compressed air to the gap from the outside. be able to.

  The wafer chuck 3 includes a chuck tilt mechanism 6 that tilts the rotation axis a2 with respect to the rotation axis a1 of the grinding wheel 21. The chuck tilt mechanism 6 includes a tilt table 61, a fixed support portion 62, an upstream side movable support portion 63, and a downstream side movable support portion 64.

  The tilt table 61 is formed in a substantially triangular shape in plan view. In the tilt table 61, a fixed support portion 62, an upstream side movable support portion 63, and a downstream side movable support portion 64 are arranged 120 degrees apart on a concentric circle around the rotation axis a2.

  The fixed support portion 62 is fastened to the tilt table 61 with bolts 62a.

  The upstream movable support portion 63 is disposed on the upstream side in the rotation direction C <b> 2 of the wafer chuck 3 with respect to the fixed support portion 62. The structure of the upstream side movable support part 63 is the same as that of the downstream side movable support part 64. Therefore, the structure of the downstream side movable support part 64 will be described as an example, and the description of the upstream side movable support part 63 will be omitted. .

  The downstream side movable support portion 64 is disposed on the downstream side in the rotation direction C <b> 2 of the wafer chuck 3 with respect to the fixed support portion 62. The downstream movable support portion 64 includes a nut 64a embedded in the tilt table 61, a tilt ball screw 64b that is fixed to the index table 5 and screwed into the nut 64a at an upper portion, and a tilt motor that rotates the tilt ball screw 64b. 64c. The downstream movable support portion 64 is formed longer in the vertical direction V than the fixed support portion 62.

  The grinding apparatus 1 includes a scale 7 that measures the amount of sedimentation that the tilt table 61 has fallen due to the load applied when the grinding means 2 presses the wafer W.

  The grinding apparatus 1 includes a dress unit 8 for dressing the grinding wheel 21. The dress unit 8 includes a dress board 81, a dress base mechanism 82, and a dress unit feeding mechanism 83.

  The dress board 81 includes a dress material 81a that is disposed to face the grinding wheel 21 and dresses the grinding wheel 21, and a dress base 81b that supports the dress material 81a. The dress material 81a is a material that is smaller than the grinding wheel 21 and is made of, for example, white alumina and a binder.

  The dress base mechanism 82 supports the dress board 81 in a rotatable manner. Specifically, the dress base mechanism 82 includes a rotor 82a that can rotate around the rotation axis a3, a stator 82b that is disposed on the outer periphery of the rotor 82a, and a base member 82c that is connected to the rotor 82a and supports the dress board 81. And.

  The rotor 82a is connected to a rotary joint (not shown) and rotates the dressboard 81 and the base member 82c along the rotation direction C3 about the rotation axis a3. A predetermined gap (air gap) is provided between the rotor 82a and the stator 82b. By supplying compressed air to the gap from the outside, the rotor 82a rotates without contact with the stator 82b. be able to.

  In addition, the dress base mechanism 82 is provided with a pipe line that is connected to a vacuum suction groove 82e, which will be described later, extending through the rotor 82a to the surface of the base member 82c. The pipe line is connected to a vacuum source and a compressed air source (not shown) via a rotary joint connected to the rotor 82a.

  Four rows of vacuum suction grooves 82e are formed concentrically around the rotation axis a3 on the surface 82d of the base member 82c facing the dressing base metal 81b. When the vacuum source is activated, the dressing base 81b is evacuated to the base member 82c through the vacuum suction groove 82e, and the dressboard 81 is sucked and held on the base member 82c. When the compressed air source is activated, compressed air is introduced between the dressing base metal 81b and the base member 82c through the vacuum suction groove 82e, and the suction between the dressboard 81 and the base member 82c is released.

  On the surface 82d of the base member 82, a positioning pin 82g fitted into the recess 82f is projected. The positioning pin 82g is engaged with a recess 81d that is recessed in the back surface 81c of the dressing base 81b.

  The dress unit feeding mechanism 83 includes two linear guides 83 a connected to the base table 95 and a known ball screw slider mechanism 83 b that raises and lowers the base table 95 in the vertical direction V. That is, the linear guide 83 a and the ball screw slider mechanism 83 b are arranged in parallel with the spindle feed mechanism 23.

  The dress unit 8 includes a touch sensor 84 that measures the thickness of the dress material 81a. The touch sensor 84 is provided so as to be swingable around the turning center 84a.

  The dress unit 8 includes a nozzle 85 that supplies coolant water to the surface of the dress material 81a. The nozzle 85 may be configured to employ a flare type capable of spraying coolant water over a wide range and hit the grinding wheel 21 and the touch sensor 84.

  The dress unit 8 includes a dress unit tilting mechanism 9 that tilts the rotation axis a3 with respect to the rotation axis a1 of the grinding wheel 21. The dress unit tilting mechanism 9 includes a tilt table 91, a fixed support portion 92, an upstream side movable support portion 93, and a downstream side movable support portion 94.

  In the tilt table 91, a fixed support portion 92, an upstream side movable support portion 93, and a downstream side movable support portion 94 are arranged 120 degrees apart on a concentric circle about the rotation axis a3.

  The fixed support portion 92 is a bolt that connects the tilt table 91 and the base table 95 in the vertical direction V. Note that reference numeral 92 a in FIG. 5 is a spherical washer interposed between the tilt table 91 and the base table 95.

  The upstream side movable support portion 93 is disposed on the upstream side in the rotational direction C3 of the dressboard 81 with respect to the fixed support portion 92. In addition, the structure of the upstream movable support part 93 is the same as that of the downstream movable support part 94, and description regarding the upstream movable support part 93 is abbreviate | omitted.

  The downstream side movable support portion 94 is disposed on the downstream side in the rotational direction C3 of the dressboard 81 with respect to the fixed support portion 92. The downstream movable support portion 94 includes an adjustment knob 94a and a tilt ball screw 94b.

  The adjustment knob 94 a is formed in a cylindrical shape, and the tip is fitted to the tilt table 91. An insertion hole 94c is formed in the adjustment knob 94a.

  The tilting ball screw 94 b is inserted into the insertion hole 94 c and the tip is fitted to the base table 95. A spring 94d is interposed between the tilting ball screw 94a and the adjustment knob 94b. When the tilt ball screw 94b is rotated, the tilt table 91 is raised by the amount of the tilt ball screw 94b being screwed.

  The operation of the grinding device 1 is controlled by the control device 10. The control device 10 controls each component constituting the grinding device 1. The control device 10 is configured by, for example, a CPU, a memory, and the like. Note that the function of the control device 10 may be realized by controlling using software or may be realized by operating using hardware.

  Based on the thickness of the wafer W measured by a thickness sensor (not shown), the control device 10 tilts the rotation axis a2 with respect to the rotation axis a1 so that a desired wafer thickness can be obtained. Adjust the processing range for grinding. The thickness sensor is not limited to the one included in the configuration of the grinding apparatus 1, and may be one that feeds back data measured by an external device of the grinding apparatus 1 to the control apparatus 10, for example. The upstream movable support portion 63 and the downstream movable support portion 64 independently expand and contract along the vertical direction V, and the tilt table 61 tilts with respect to the fixed support portion 62, thereby tilting the rotation axis a2. Can do.

  The controller 10 stores data of the grinding amount of the wafer W according to the angle (tilt angle) of the rotation axis a2 with respect to the rotation axis a1, that is, the contact angle of the wafer W with respect to the grinding wheel 21. Thus, the thickness of the wafer W before grinding or the thickness of the wafer W during grinding is measured, and the amount of grinding and the tilt angle of the rotation axis a2 with respect to the rotation axis a1 are adjusted from the difference between this thickness and the desired wafer thickness. Further, data relating to the shape of the grinding surface 21a of the grinding wheel 21 corresponding to the angle (tilt angle) of the rotation axis a3 with respect to the rotation axis a1 is stored.

  Next, the operation of the dress unit 8 will be described based on the drawings. FIG. 7 is a schematic diagram showing how the dressing unit 8 dresses the grinding wheel 21. FIG. 8 is a schematic diagram showing the distribution of the pressing force acting on the dressing unit 8. FIG. 9 is a schematic diagram illustrating a state in which the deformation of the dressboard 81 due to the pressing force is suppressed.

  The dressing unit 8 dresses the grinding surface 21 a of the grinding wheel 21 after grinding the wafer W. Specifically, when the grinding of the wafer W is completed, the grinding wheel 21 is retracted upward in the vertical direction V. Thereafter, the ball screw slider mechanism 83b is driven, and the dressing material 81a approaches the grinding surface 21a of the grinding wheel 21.

  The grinding surface 21a of the grinding wheel 21 is dressed by the dressing material 81a by pressing the dress board 81 against the grinding wheel 21 while rotating the grinding wheel 21 and the dress board 81, respectively.

  Since the ball screw slider mechanism 83b is arranged in parallel with the spindle feed mechanism 23, the ball screw slider mechanism 83b receives a pressing force along the vertical direction V when the dressboard 81 is pressed against the grinding wheel 21, The grinding wheel 21 can be dressed stably.

  Since the ball screw slider mechanism 83b is disposed between the center O of the grinding wheel 21 and the spindle feed mechanism 23, the dressing board is mounted on the base table 95 that is cantilevered by the linear guide 83a and the ball screw slider mechanism 83b. The pressing force along the vertical direction V when 81 is pressed against the grinding wheel 21 is suppressed from acting locally, and the base table 95 cantilevered by the linear guide 83 a is used when the grinding wheel 21 is dressed. Since jumping up by the reaction force is suppressed, the grinding wheel 21 can be dressed more stably.

  When dressing the grinding wheel 21, coolant water is supplied to the surface of the dress material 81a. By rotating the dress board 81 in a state where the coolant water is supplied, surplus coolant water is scattered by centrifugal force, and an extremely thin water film WF is formed on the surface of the dress material 81a. As an example of forming the water film WF, it is conceivable to set the coolant water supply amount to 0.1 to 0.5 l / min and the rotational speed of the dressboard 81 to 400 rpm or less. Thus, since the touch sensor 84 contacts the dress material 81a through the water film WF, wear of the touch sensor 84 is suppressed. The coolant water is preferably supplied so as to hit the grinding wheel 21 and the touch sensor 84.

  The rotational axis a3 of the dressing unit 8 can be dressed in a curved surface by grinding the grinding surface 21a of the grinding wheel 21 by tilting by the dressing unit tilting mechanism 9. For example, when the upstream movable support portion 93 and the downstream movable support portion 94 are extended and the tilt table 91 is tilted, the grinding surface 21a of the grinding wheel 21 has a central convex shape thicker than the outer peripheral portion of the grinding wheel 21. Can be formed. Further, when the upstream movable support portion 93 and the downstream movable support portion 94 contract and the tilt table 91 tilts, the grinding surface 21a of the grinding wheel 21 is formed in a concave shape that is thinner than the outer peripheral portion at the center of the grinding wheel 21. Can be formed.

  Further, when the wafer chuck 3 is tilted, the upstream side movable support portion 93 and the downstream side movable support portion 94 of the tilt table 91 extend and contract so that the tilt angle of the tilt table 61 and the tilt angle of the tilt table 91 coincide with each other. Let By previously dressing the grinding surface 21 a of the grinding wheel 21 according to the inclination of the wafer chuck 3, the shape of the wafer W can be indirectly determined according to the inclination of the dress board 81.

  Since the back surface 81c of the dressing base 81b is vacuum-sucked by the base member 82c, the dressboard 81 is slid and restrained in the radial direction R. Therefore, as shown in FIG. 8A, the pressing force acting on the dressboard 81 is dispersed in the radial direction R, and the distortion in the thickness direction T is reduced.

  On the other hand, when the dressing base 81b is fastened to the base member 82c with the bolt B as in the comparative example shown in FIG. 8B, the dressboard 81 is fixed in the radial direction R. In such a case, since the bolt B receives the pressing force acting on the dress board 81 in a concentrated manner, distortion in the thickness direction T occurs.

  Further, as shown in FIG. 9, when the dressing base metal 81b is to be deformed with a constant volume by the pressing force acting on the dressboard 81, that is, to be deformed so as to be thin in the thickness direction T and spread in the radial direction R. Even when the back surface 81c of the dressing base metal 81b is vacuum-sucked to the base member 82c, the spreading of the dressing base metal 81b in the radial direction R is suppressed, and the thickness direction T of the dressing base metal 81b is reduced. The distortion to the is reduced.

  In this way, the above-described grinding apparatus 1 ensures that the grinding waste does not intervene between the dressboard 81 and the base member 82c by the vacuum suction of the dressboard 81 to the base member 82c without causing a vacuum leak. This can be confirmed indirectly, and the dressboard 81 can be attached to the base member 82c in the correct posture.

  Further, as compared with the case where the dressboard 81 is fixed to the base member 82c using a bolt or the like, the dressboard 81 can be easily attached to the base member 82c simply by placing the dressboard 81 on the base member 82c and vacuum-sucking the dressboard 81. it can.

  Furthermore, the dressing board 81 can be accurately and simply attached to the base member 82c by the positioning pin 82g engaging with the recess 81d.

  The present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.

DESCRIPTION OF SYMBOLS 1 ... Grinding device 2 ... Grinding means 21 ... Grinding wheel 22 ... Spindle 23 ... Spindle feed mechanism 23a ... Linear guide 3 ... Wafer chuck (holding means)
31 ... Chuck 32 ... Air bearing 32a ... Rotor 32b ... Stator 4 ... Column 5 ... Index table 6 ... Chuck tilt mechanism 61 ... Tilt table 62 ... Fixed Support part 62a ... Bolt 63 ... Upstream movable support part 64 ... Downstream movable support part 7 ... Scale 8 ... Dress unit (dressing means)
81 ... Dress board 81a ... Dress material 81b ... Dress base 81c ... Back side (of dress base) 81d ... Recess (of dress base) 82 ... Dress base mechanism 82a .. Rotor 82b ... Stator 82c ... Base member 82d ... (base member) surface 82e ... Vacuum suction groove 82f ... (base member) recess 82g ... Positioning pin 83 ... Dress unit feed mechanism 83a ... Linear guide 83b ... Ball screw slider mechanism 84 ... Touch sensor 84a ... Turning center 85 ... Nozzle 9 ... Dress unit tilt mechanism 91 ... Tilt table 92・ ・ ・ Fixed support part 93 ・ ・ ・ Upstream movable support part 94 ・ ・ ・ Downstream movable support part 10 ・ ・ ・ Control device W ・ ・ ・ Wafer

Claims (5)

A grinding device comprising a holding means for holding a wafer and a grinding means having a grinding wheel for grinding the wafer,
Dressing means for dressing the grinding wheel;
A dressing means holding mechanism for vacuum adsorbing the dressing means,
A grinding apparatus comprising:   The grinding apparatus according to claim 1, wherein the dressing means holding mechanism sucks a back surface of the dressing means.   The grinding apparatus according to claim 2, further comprising positioning means for positioning the dressing means at a predetermined position with respect to the dress holding mechanism. The positioning means includes
A positioning pin projecting on one of opposing surfaces of the dressing means and the dressing means holding mechanism;
A recess formed in the other of the facing surfaces of the dressing unit and the dressing unit holding mechanism facing each other and engageable with the positioning pin;
The grinding apparatus according to claim 3, comprising: 2. The grinding apparatus according to claim 1, wherein a vacuum suction groove connected to a vacuum source is formed on a facing surface of the dressing means holding mechanism facing the dressing means.