JP2013193156A - Grinding device, and grinding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grinding device and a grinding method which can reduce a workload of the inclination adjustment of a holding table without measuring the thickness of a workpiece at each other time of measurement.SOLUTION: A grinding device has a control means. The control means includes: a reference data storing part for storing measurement data measured by a height position measuring means as reference data; a comparing part for comparing measurement data measured at the height position of a holding surface by the height position measuring means in predetermined timing, with the reference data stored in the reference data storing part; and an inclination changing means controller which, when a difference is found between the reference data and the measurement data compared by the comparing means, changes the inclination of the holding table by making an inclination changing means act, and makes the height position of the holding surface follow the height position in the reference data.

Description

  The present invention relates to a grinding apparatus and a grinding method for grinding a workpiece such as a semiconductor wafer.

  Conventionally, as disclosed in Patent Document 1, for example, a holding surface (chuck surface) of a holding table (chuck table) is configured in a conical shape including an inclined surface with a very small gradient with the rotation axis (center of the holding surface) as a vertex. Grinding devices are known.

  In such a grinding apparatus, a grinding unit including a spindle and a grinding wheel including a grinding wheel mounted on the spindle is provided, and the grinding unit is disposed to face the holding table. Since the holding surface of the holding table is configured in a conical shape, a radius region from the center of the holding surface to the outer periphery is a processing point (a region where the grinding wheel processes the workpiece).

  At this processing point, the axis of the rotary shaft of the holding table and the spindle of the grinding unit are aligned so that the holding surface of the holding table and the grinding surface of the grinding wheel (the surface contacting the workpiece of the grinding wheel) are parallel to each other. An angle is formed in the relationship between the shaft centers. The example of Patent Document 1 discloses a configuration in which an angle θ is formed between the axis of the rotation axis of the substantially vertical holding table by tilting the axis of the spindle.

JP 2000-288888 A JP 2002-367933 A

  In a grinding apparatus, it is assumed that each part of the grinding apparatus is thermally expanded due to heat generated by processing, a temperature change of an atmosphere in which the grinding apparatus is disposed, and the like. Due to this thermal expansion, in the case of a configuration in which the holding table is inclined, it is assumed that the inclination of the holding table changes from a specified inclination.

  And if it hold | maintains with the holding table from which inclination changed, and it grinds, the thickness dispersion | variation of the workpiece after grinding will become large, and there exists a possibility that it may become a processing defect.

  In the past, when the thickness of the workpiece after grinding was measured and the thickness variation was large, the tilt of the holding table was adjusted every time. There was a problem of taking time.

  The present invention has been made in view of the above problems, and the object of the present invention is to reduce the work burden of adjusting the tilt of the holding table without having to measure the thickness of the workpiece each time. An apparatus and a grinding method are provided.

  According to the first aspect of the present invention, there is provided a grinding apparatus for grinding a workpiece. The grinding device has a holding surface for holding the workpiece and a rotating shaft passing through the holding surface at the center of the holding surface. A holding table formed conically with the center of the holding surface as a vertex, a grinding wheel having a plurality of grinding wheels arranged opposite to the holding table, and a spindle on which the grinding wheel is rotatably mounted A grinding means for grinding a work piece held by the holding table in a radial region extending from the center of the holding surface to the outer periphery; an inclination changing means for changing the inclination of the holding table; and a plurality of height positions of the holding surface. A height position measuring means for measuring at a point, and a control means for controlling at least the holding table, the grinding means, and the inclination changing means, and the control means stores the measurement data measured by the height position measuring means as reference data. You Comparison between the reference data storage unit, the comparison unit that compares the measurement data obtained by measuring the height position of the holding surface with the height position measuring means at a predetermined timing and the reference data stored in the reference data storage unit, and the comparison unit An inclination changing means control section for causing the inclination changing means to act to change the inclination of the holding table so that the height position of the holding surface follows the height position in the reference data when there is a difference between the measured data and the reference data. Are provided.

  According to the invention described in claim 2, a grinding method for grinding a workpiece with a grinding apparatus, the holding surface holding the workpiece, and a rotation axis passing through the holding surface at the center of the holding surface, A holding step in which the holding surface holds the workpiece by a holding table formed conically with the center of the holding surface as a vertex, and a plurality of grinding wheels disposed so as to face the holding table after performing the holding step A grinding step having a grinding wheel having a grinding wheel and a spindle on which the grinding wheel is rotatably mounted, wherein the workpiece held by the holding table is ground in a radial region extending from the center of the holding surface to the outer periphery. After the grinding step, the workpiece thickness variation measuring step for measuring the workpiece thickness variation, and the holding surface height before the holding step or after the grinding step is performed. A first holding surface measuring step for measuring the position at a plurality of points and a workpiece holding thickness measured in the first holding surface measuring step when the workpiece thickness variation measured in the workpiece thickness variation measuring step is less than a predetermined value. A reference data storage step for storing the height position as reference data, and a second holding surface for obtaining measurement data by measuring the height position of the holding surface at a plurality of points at a predetermined timing after performing the reference data storage step. A holding table tilting step for tilting the holding table so that the height position in the measurement data follows the height position in the reference data when the measurement data measured in the measurement step and the second holding surface measurement step differ from the reference data; Are provided.

  According to the present invention, once the reference data is acquired, the height and position of the holding surface are measured at a predetermined timing, and the inclination and height of the holding surface are corrected. Therefore, it is possible to reduce the work load of adjusting the inclination and height of the holding surface. Thereby, the thickness variation of the workpiece after grinding can be reduced, and processing accuracy can be improved.

1 is an external perspective view of a grinding apparatus according to an embodiment of the present invention. It is sectional drawing shown about the structure of a chuck table. It is sectional drawing shown about the structure of a chuck table unit. It is sectional drawing explaining a grinding step. It is a figure explaining the measurement of the height position of a holding surface by a height position measuring device. It is a graph explaining the measurement result of a height position. It is a block diagram shown about the outline | summary of a control apparatus. It is a figure explaining a workpiece thickness variation measurement step.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an external perspective view of a grinding apparatus 2 according to an embodiment of the present invention. The housing 4 of the grinding device 2 is composed of a horizontal housing part 6 and a vertical housing part 8.

  A pair of guide rails 12 and 14 extending in the vertical direction are fixed to the vertical housing portion 8. A grinding unit (grinding means) 16 is mounted along the pair of guide rails 12 and 14 so as to be movable in the vertical direction. The grinding unit 16 is attached to a moving base 18 that moves up and down along a pair of guide rails 12 and 14 via a support portion 20.

  The grinding unit 16 includes a spindle housing 22 attached to the support portion 20, a spindle 24 rotatably accommodated in the spindle housing 22, and a servo motor 26 that rotationally drives the spindle 24.

  As best shown in FIG. 2, a mounter 28 is fixed to the tip of the spindle 24, and a grinding wheel 30 is screwed to the mounter 28. The grinding wheel 30 is configured by adhering a plurality of grinding wheels 34 in which diamond abrasive grains or the like are hardened with an appropriate bonding agent such as resin bond or vitrified bond to a free end portion of a wheel base 32.

  Referring again to FIG. 1, the grinding apparatus 2 includes a grinding unit feed mechanism 44 that moves the grinding unit 16 in the vertical direction along the pair of guide rails 12 and 14. The grinding unit feed mechanism 44 includes a ball screw 46 and a pulse motor 48 fixed to one end of the ball screw 46. When the pulse motor 48 is pulse-driven, the ball screw 46 rotates and the moving base 18 is moved in the vertical direction via the nut of the ball screw 46 fixed inside the moving base 18.

  A chuck table unit 50 is disposed in the recess 10 of the horizontal housing portion 6. As shown in FIG. 3, the chuck table unit 50 includes a support base 52 and a chuck table 54 that is rotatably disposed on the support base 52.

  The chuck table unit 50 is moved in the front-rear direction of the grinding apparatus 2 by the chuck table moving mechanism 58. The chuck table moving mechanism 58 includes a ball screw 60 and a pulse motor 64 connected to one end of a screw shaft 62 of the ball screw 60.

  When the pulse motor 64 is pulse-driven, the screw shaft 62 of the ball screw 60 rotates, and the support base 52 having a nut screwed to the screw shaft 62 moves in the front-rear direction of the grinding device 2. Therefore, the chuck table 54 also moves in the front-rear direction according to the rotation direction of the pulse motor 64.

  As shown in FIG. 1, the pair of guide rails 66 and 68 and the chuck table moving mechanism 58 shown in FIG. 3 are covered with bellows 70 and 72. That is, as shown in FIG. 1, the front end portion of the bellows 70 is fixed to the front wall that defines the recess 10, and the rear end portion is fixed to the front end surface of the cover 56 having a hole through which the chuck table 54 is inserted. Yes. The rear end of the bellows 72 is fixed to the vertical housing portion 8, and the front end thereof is fixed to the rear end surface of the cover 56.

  In the horizontal housing portion 6 of the housing 4, a first wafer cassette 74, a second wafer cassette 76, a wafer transfer means 78, a temporary wafer placement means 80, a wafer carry-in means 82, and a wafer carry-out means 84 are provided. A cleaning means 86 is provided. Further, an operation means 88 is provided in front of the housing 4 for an operator to input grinding conditions and the like.

  Further, a cleaning water spray nozzle 90 for cleaning the chuck table 54 is provided at the approximate center of the horizontal housing portion 6. The cleaning water jet nozzle 90 sprays cleaning water toward the ground wafer held by the chuck table 54 in a state where the chuck table unit 50 is positioned in the wafer carry-in / carry-out region.

  The grinding operation of the grinding device 2 configured as described above will be described below. In the first wafer cassette 74, a semiconductor wafer having a protective tape mounted on the front surface side (surface on which a circuit is formed) is accommodated as a workpiece, and the back surface is positioned on the upper side. ing. Thus, the first wafer cassette 74 containing a plurality of semiconductor wafers is placed in a predetermined cassette loading area of the housing 4.

  And when all the semiconductor wafers before grinding which were accommodated in the 1st wafer cassette 74 mounted in the cassette carrying-in area are carried out, it changed into the empty wafer cassette 74 and accommodated the several semiconductor wafer. A new first wafer cassette 74 is manually placed in the cassette loading area.

  On the other hand, when a predetermined number of ground semiconductor wafers are loaded into the second wafer cassette 76 placed in the predetermined cassette unloading area of the housing 4, the second wafer cassette 76 is manually unloaded. A new empty second wafer cassette 76 is placed in the cassette unloading area.

  The semiconductor wafers accommodated in the first wafer cassette 74 are transported by the vertical movement and forward / backward movement of the wafer transport means 78 and placed on the temporary wafer placement means 80. The wafer mounted on the temporary wafer mounting means 80 is centered here, and then the chuck table of the chuck table unit 50 positioned in the wafer loading / unloading area by the turning operation of the wafer loading means 82. 54 and is sucked and held by the chuck table 54.

  If the chuck table 54 sucks and holds the wafer in this way, the chuck table moving mechanism 58 (FIG. 3) is operated to move the chuck table unit 50 and position it in the grinding area behind the apparatus.

  When the chuck table unit 50 is positioned in the grinding area, the center of the wafer held by the chuck table 54 is positioned slightly beyond the outer circumference circle of the grinding wheel 30.

  Next, the chuck table 54 is rotated at, for example, about 100 to 300 rpm, the servo motor 26 is driven to rotate the grinding wheel 30 at 4000 to 7000 rpm, and the pulse motor 48 of the grinding unit feed mechanism 44 is driven to rotate forward. The grinding unit 16 is lowered.

  Then, as shown in FIG. 4, the back surface of the wafer W is ground by pressing the grinding wheel 34 of the grinding wheel 30 against the back surface Wb (surface to be ground) of the wafer W on the chuck table 54 with a predetermined load. . By grinding in this way for a predetermined time, the wafer W is ground to a predetermined thickness.

  When grinding is completed, as shown in FIG. 1, the chuck table moving mechanism 58 (FIG. 3) is driven to position the chuck table 54 in the wafer carry-in / carry-out region. When the chuck table 54 is positioned in the wafer carry-in / carry-out region, the back surface Wb (the surface to be ground) of the ground wafer W that is ground and held by the chuck table 54 by spraying the cleaning water from the cleaning water spray nozzle 90. In addition, the chuck table 54 after the wafer W is unloaded is cleaned.

  After the suction and holding of the wafer held on the chuck table 54 is released, the wafer W is transferred to the cleaning means 86 by the wafer carry-out means 84. The wafer transferred to the cleaning means 86 is cleaned here and spin-dried. Next, the wafer is stored in a predetermined position of the second wafer cassette 76 by the wafer transfer means 78.

Next, in addition to the overall configuration described above, a characteristic configuration of the grinding apparatus 2 according to the embodiment of the present invention will be described.
First, as shown in FIGS. 2 and 4, a holding surface 55 that holds a wafer W as a workpiece and a rotation shaft 54 g that passes through the center 55 </ b> C of the holding surface 55 are provided. The chuck table 54 is configured as a holding table formed conically with the center 55C as a vertex.

  A concave accommodating portion 54b is formed on the upper surface of the main body 54a of the chuck table 54. In the accommodating portion 54b, an adsorption chuck 55K, which is a porous member made of porous ceramic or the like having numerous suction holes. Is housed. The accommodating portion 54b is connected to a suction path 54c connected to a suction source (not shown), and a negative pressure is generated on the holding surface 55 which is the upper surface of the suction chuck 55K, so that the wafer W is applied to the holding surface 55. Adsorbed and held.

  The suction chuck 55K is configured to have a conical shape with the center 55C of the upper surface as an apex, whereby the holding surface 55 is configured to have a conical shape. The wafer W is adsorbed along the shape of the conical holding surface 55.

  Further, as shown in FIGS. 2 and 4, the grinding wheel 30 having a plurality of grinding wheels 34 disposed to face the chuck table 54 and the spindle 24 on which the grinding wheel 30 is rotatably mounted are provided. The grinding unit 16 is configured as a grinding means for grinding the wafer W held by the chuck table 54 in a radius region extending from the center 55C of the holding surface 55 to the outer periphery.

  Further, as shown in FIG. 3, an inclination changing device 51 is configured as an inclination changing means for changing the inclination of the chuck table 54. In this embodiment, on the upper surface of the support base 52, lifting devices 52a, 52b, and 52c are provided at three positions on a concentric circle at intervals of 120 degrees, and the lifting table 52a, 52b, and 52c lowers the chuck table 54 on the lower side. The base table 57 supported from above is supported.

  Each of the lifting devices 52a, 52b, and 52c is configured to extend and contract the rods 53a, 53b, and 53c by a driving force such as pneumatic pressure, hydraulic pressure, and motor driving, for example, and controls the expansion and contraction of the rods 53a, 53b, and 53c. The angle of the upper surface of the base table 57 is adjusted, and accordingly, the angle θ (see FIG. 2) of the holding surface 55 of the chuck table 54 is adjusted. When the base table 57 is supported at three points as in the present embodiment, the angle of the upper surface of the base table 57 is adjusted by fixing one point and adjusting the remaining two points. It is good also as adjusting.

  Then, in order to measure the height position of the holding surface 55 of the chuck table 54 whose inclination is changed as described above at a plurality of points, as shown in FIG. Is provided.

  As shown in FIG. 5, the height position measuring device 36 of the present embodiment has a configuration in which a height measuring device 38 is provided at the tip of the rotating arm 37, and the rotating arm 37 is rotated by a predetermined angle. The height positions L1 to L4 (see FIG. 6) of the chuck table 54 are measured each time at predetermined measurement points P1 to P4.

  FIG. 6 shows a graph in which the vertical axis is the height and the horizontal axis is the measurement position for each of the measured height positions L1 to L4. Such measurement results are not shown in the memory of the control means. Is remembered. In this example, the center 55C of the holding surface 55 of the chuck table 54 is coincident with the measurement point P4.

  FIG. 7 shows a configuration example of the control device 40 as the control means of the grinding device 2. In this embodiment, the chuck table (holding table) 54, the grinding unit (grinding means) 16, and the tilt changing device (tilt). Change means) 51 and the like.

  Further, the control device 40 includes a reference data storage unit 41 that stores measurement data 41S measured by the height position measurement device 36 as reference data 41D.

  As shown in FIG. 6, the measurement data 41S is data including height positions L1 to L4 at the measurement points P1 to P4. For example, the timing when initial setting is performed when the grinding device 2 is introduced, and the like. It is assumed that it is acquired each time at a timing after processing a specific number of wafers W or after a specific continuous processing time has elapsed.

  In the measurement data 41S measured in this way, as will be described in detail later, the measurement data 41S when the thickness variation B1 is less than or equal to a predetermined value N is achieved by realizing a desired processing accuracy. Is stored as reference data 41D for realizing high machining accuracy.

  Further, as shown in FIG. 7, the control device 40 includes the measurement data 41 </ b> S obtained by measuring the height positions L <b> 1 to L <b> 4 of the holding surface 55 of the chuck table 54 with the height position measurement device 36 at a predetermined timing and the reference data storage unit. Comparing unit 42 for comparing with reference data 41D stored in 41 is provided.

  Here, the predetermined timing may be, for example, a timing after processing a specific number of wafers W or a timing after a specific continuous processing time has elapsed. Thus, the comparison unit 42 compares the difference between the measurement data 41S acquired each time at a predetermined timing and the reference data 41D described above.

  In addition, as shown in FIG. 7, when there is a difference between the measurement data 41 </ b> S compared by the comparison unit 42 and the reference data 41 </ b> D, the control device 40 operates the tilt changing device 51 to change the tilt of the chuck table 54. There is an inclination changing means control unit 43 that causes the height positions L1 to L4 of the holding surface 55 of the chuck table 54 to follow the reference data 41D.

  For example, as shown in FIG. 6, when the measurement data 41S measured at a predetermined timing is the height positions L1a to L4a, the height positions L1a to L4a are changed to the height positions L1 to L4 (reference The inclination of the chuck table 54 is changed so as to coincide with the data 41D), whereby the inclination and height of the chuck table 54 are corrected.

Next, an embodiment of a grinding method using the above apparatus configuration will be described.
First, as shown in FIG. 4, a holding surface 55 that holds a wafer W as a workpiece and a rotation shaft 54 g that passes through the holding surface 55 at the center 55 </ b> C of the holding surface 55. A holding step of holding the wafer W with the chuck table 54 as a holding table formed in a conical shape with the center 55C as a vertex is performed.

  By this holding step, the wafer W is attracted to the holding surface 55 so as to follow the shape of the conical holding surface 55.

  After carrying out the holding step, grinding as a grinding means having a grinding wheel 30 having a plurality of grinding wheels 34 disposed facing the chuck table 54 and a spindle 24 on which the grinding wheel 30 is rotatably mounted. In the unit 16, a grinding step is performed in which the wafer W held by the chuck table 54 is ground in a radial region from the center 55 </ b> C of the holding surface 55 to the outer periphery.

  In the present embodiment shown in FIG. 4, the radius region from the center 55 </ b> C of the holding surface 55 to the outer periphery becomes the processing point K, and the back surface Wb of the wafer W is ground, so that the wafer W is thinned.

  After performing the grinding step, a workpiece thickness variation measuring step for measuring the thickness variation of the wafer W is performed as shown in FIG.

  In this embodiment, the wafer W is placed on the thickness measuring stage 94 so that the thinned back surface Wb of the wafer W is on the upper side, and the non-contact type thickness measuring device 92 is placed above the wafer W at the center of the wafer W. The thickness variation of the wafer W is measured by moving the wafer W from one end side w1 to the other end side w2.

  Here, the “thickness variation” means, for example, the flatness of the thickness (TTV (Total Thickness Variation: the maximum value of the thickness) measured at a plurality of locations in the range from one end side w1 to the other end side w2 of the wafer W. (Value defined by the difference between the minimum values) as a unit, or the standard deviation with each thickness at multiple locations as a population. Thinning is performed with good accuracy, and the inclination (angle θ (see FIG. 2)) of the chuck table 54 is in an optimal state.

  Note that the “thickness variation” may be measured by using a contact-type thickness measuring device as well as a non-contact-type thickness measuring device 92 as shown in FIG. In addition, the thickness measuring stage 94 is provided in the grinding apparatus 2 so that “thickness variation” is measured in the grinding apparatus 2, or provided in a location different from the grinding apparatus 2. A configuration may be adopted in which “thickness variation” is measured for the wafer W unloaded from 2.

  In addition, a first holding surface measurement step is performed in which the height position of the holding surface 55 is measured at a plurality of points before the holding step is performed or after the grinding step is performed and the wafer W is not held.

  Specifically, as shown in FIG. 5, using a height position measuring device 36, as shown in FIG. 6, a plurality of (four points in this embodiment) measurement points P1 from the outer periphery to the center of the chuck table 54. Measure height positions L1a to L4a at P4 to obtain measurement data 41S.

  Then, the height position (measurement data 41S) of the holding surface 55 measured in the first holding surface measurement step when the thickness variation of the wafer W measured in the workpiece thickness variation measurement step is equal to or less than a predetermined value is measured with good processing. A reference data storing step for storing as reference data 41D for realizing accuracy is performed.

  Specifically, as shown in FIG. 6, for example, when the thickness variation B1 of the wafer W is measured in the workpiece thickness variation measurement step, the thickness variation B1 is less than or equal to a predetermined value N. The height positions L1 to L4 (measurement data 41S) of the holding surface 55 measured in the holding surface measurement step are stored as reference data 41D.

  Here, the predetermined value N means a thickness variation when the wafer W is processed at a desired processing accuracy (thinning processing accuracy), and the thickness variation below the predetermined value N is realized. As long as it is done, it means that a desired processing accuracy is achieved.

  For example, when initial setting is performed when the grinding apparatus 2 is introduced, the reference data storage step is completed, that is, until the thickness variation B1 becomes equal to or less than a predetermined value N, the holding step, the grinding step, It is assumed that a series of steps of the workpiece thickness variation measuring step and the first holding surface measuring step are performed a plurality of times. The predetermined value N may be set to 1 μm, for example, when the above flatness is used as a unit.

  Further, as shown in FIGS. 5 and 6, the reference data 41D is defined based on the height positions L1 to L4 acquired in the range of the measurement points P1 to P4, and the reference data 41D is measured data 41S (height In addition to being used for comparison with the positions L1a to L4a), the height position of the region of the processing point K shown in FIGS. 4 and 6 is measured, and the upper surface shape of the holding surface 55 (the shape of the region of the processing point K) And the height) may be defined as the reference data 41D.

  After performing the reference data storage step, as shown in FIG. 6, a second holding surface measurement step is performed in which the height position of the holding surface 55 is measured at a plurality of points at a predetermined timing to obtain measurement data 41S. The Here, the predetermined timing may be, for example, a timing after processing a specific number of wafers W or a timing after a specific continuous processing time has elapsed.

  When the measurement data 41S measured in the second holding surface measurement step is different from the reference data 41D, the height positions L1a to L4a in the measurement data 41S are copied to the height positions L1 to L4 in the reference data 41D. A holding table tilting step for tilting the chuck table 54 is performed (see arrow G in FIG. 1).

  For example, in the example of FIG. 6, the height positions L1 to L4 of the holding surface 55 are defined and stored as the reference data 41D, and the height positions L1a to L4a of the holding surface 55 measured in the second holding surface measurement step. Is defined as the measurement data 41S, the measurement data S is different from the reference data D1. In such a case, a holding table tilting step is performed.

  Specifically, the comparison unit 42 shown in FIG. 7 compares the difference between the measurement data 41S (height positions L1a to L4a (FIG. 6)) and the reference data 41D (height positions L1 to L4 (FIG. 6)). The Then, when there is a difference between the measurement data 41 </ b> S and the reference data 41 </ b> D, the inclination changing unit control unit 43 operates the inclination changing device 51 to change the inclination of the chuck table 54 and the height position of the holding surface 55 of the chuck table 54. The inclination and height of the chuck table 54 are corrected by causing L1a to L4a to follow the height positions L1 to L4 in the reference data 41D.

  By correcting the tilt and height of the chuck table 54 in this way, the same situation as when the desired machining accuracy is realized can be reproduced with respect to the tilt and height of the holding surface 55 of the chuck table 54. This makes it possible to achieve a desired machining accuracy.

  According to the embodiment described above, the reference data is acquired once, and thereafter, the height position of the holding surface 55 is measured at a predetermined timing to correct the tilt and height of the chuck table 54. Therefore, it is not necessary to measure the thickness of the wafer W, which is a workpiece, each time, and the work load for adjusting the tilt of the chuck table 54 can be reduced. Thereby, the thickness variation of the wafer W after grinding can be reduced, and the processing accuracy can be improved.

  In the present embodiment, an example of a grinding apparatus including one chuck table 54 as a holding table has been described. However, for a grinding apparatus including a plurality of holding tables, a height position measuring device ( (Height position measuring means) 36 may be provided, and tilt correction may be performed for each holding table.

2 Grinding device 36 Height position measuring device 37 Rotating arm 38 Measuring device 41D Reference data 41S Measurement data 50 Chuck table unit 51 Tilt changing device 52 Support base 54 Chuck table 55 Holding surface 55C Center 55K Adsorption chuck 92 Measuring device 94 Measurement Stage W Wafer Wb Back

Claims (2)

A grinding device for grinding a workpiece,
A holding table that holds a workpiece and a rotation table that passes through the holding surface at the center of the holding surface, the holding surface being formed in a conical shape with the center of the holding surface as a vertex;
A holding wheel on the workpiece held by the holding table, the grinding wheel having a plurality of grinding wheels disposed opposite to the holding table and a spindle on which the grinding wheel is rotatably mounted; Grinding means for grinding in a radial region from the center to the outer periphery,
Inclination changing means for changing the inclination of the holding table;
Height position measuring means for measuring the height position of the holding surface at a plurality of points;
Control means for controlling at least the holding table, the grinding means, and the inclination changing means,
The control means includes
A reference data storage unit for storing measurement data measured by the height position measuring means as reference data;
A comparison unit that compares the measurement data obtained by measuring the height position of the holding surface with the height position measurement unit at a predetermined timing and the reference data stored in the reference data storage unit;
When there is a difference between the measurement data compared with the reference data and the reference data, the inclination changing means is operated to change the inclination of the holding table, and the height position of the holding surface is changed to the height in the reference data. And a tilt changing means control section for copying the position. A grinding method for grinding a workpiece with a grinding device,
A holding table that holds a workpiece and a rotation shaft that passes through the holding surface at the center of the holding surface, and the holding surface is formed in a conical shape with the center of the holding surface as a vertex. A holding step for holding the workpiece;
After carrying out the holding step, the holding table includes a grinding wheel having a grinding wheel having a plurality of grinding wheels disposed opposite to the holding table and a spindle on which the grinding wheel is rotatably mounted. A grinding step for subjecting the work piece held in step 1 to a radius region extending from the center to the outer periphery of the holding surface;
After performing the grinding step, the workpiece thickness variation measuring step for measuring the workpiece thickness variation,
A first holding surface measuring step for measuring the height position of the holding surface at a plurality of points before or after performing the holding step;
Reference data storage for storing the height position of the holding surface measured in the first holding surface measuring step as reference data when the thickness variation of the workpiece measured in the workpiece thickness variation measuring step is equal to or less than a predetermined value. Steps,
A second holding surface measuring step for obtaining measurement data by measuring the height position of the holding surface at a plurality of points at a predetermined timing after performing the reference data storing step;
When the measurement data measured in the second holding surface measuring step is different from the reference data, the holding table tilting step is performed to tilt the holding table so that the height position in the measurement data follows the height position in the reference data. When,
A grinding method comprising:

Images