Work-piece processing device

Abstract

To provide a work-piece processing device that can process a surface of a work-piece into a flat surface to form the work-piece into a target shape.SOLUTION: A work-piece processing device 1 comprises a second measurement mechanism 32 that measures thicknesses of a wafer W in a concentric manner at a plurality of measurement positions, in a state finish grinding for the wafer W is stopped in the middle of the grinding, and a control mechanism 5 that controls a tilt mechanism 13 on the basis of measured values by the second measurement mechanism 32. The control mechanism 5 determines average values of the thicknesses at the plurality of measurement positions measured by the second measurement mechanism 32 in a concentric manner, determines a polynomial curve in a surface shape of the wafer W from the average values, controls the tilt mechanism 13 on the basis of the polynomial curve so that an inclination angle θ of a chuck table 12 is adjusted, and starts to finish-grind a surface Ws of the wafer W again.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a workpiece machining device. [Background technology]

[0002] In the field of semiconductor manufacturing, semiconductor wafers such as silicon wafers (hereinafter sometimes referred to as "workpieces") are ground to form them into thin films. Known workpiece processing devices for performing such grinding include those that roughly grind the workpiece to a thickness greater than a target shape (target thickness) and then finish-grind the workpiece after rough grinding to the target shape.

[0003] For example, a workpiece processing device is known that temporarily stops grinding the workpiece during finish grinding and optically measures the thickness of the workpiece at three radial points at the grinding position. According to this workpiece processing device, when grinding is temporarily stopped during finish grinding of the workpiece to measure the thickness of the workpiece, the rotation of the workpiece is stopped and the thickness of the workpiece is measured at three radial points between the center and the outermost periphery of the workpiece. After measuring the thickness of the workpiece, the tilt of the workpiece is adjusted based on the measured thickness of the workpiece, and finish grinding of the workpiece is restarted after the tilt adjustment (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-119123 A Summary of the Invention [Problem to be solved by the invention]

[0005] Here, in grinding a workpiece, it may not be ground into a desired shape, and some parts of the workpiece may be too thick or too thin. For this reason, when the workpiece is stopped from rotating and the thickness of the workpiece is measured at three points in the radial direction, as in the workpiece processing device of Patent Document 1, there is a possibility that, for example, one of the three points may measure a singular point.

[0006] In this case, the shape of the workpiece obtained from the measurements at the three locations will be significantly different from the actual shape of the workpiece. Therefore, even if the tilt of the workpiece is adjusted based on the thickness of the workpiece measured at the three locations, it is difficult to keep the total thickness variation (TTV) of the workpiece small, for example, to 0.1 μm or less. For this reason, it is difficult for the workpiece processing device of Patent Document 1 to process the surface of the workpiece flat, and there is a risk that the workpiece cannot be processed into the target shape.

[0007] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide a workpiece machining apparatus that can machine the surface of a workpiece flat and machine the workpiece into a target shape. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention proposes the following means. <1> A workpiece processing apparatus according to one embodiment of the present invention is a workpiece processing apparatus for processing a surface of a workpiece to be flat, the apparatus comprising: a chuck table for rotating and holding the workpiece; a workpiece grinding mechanism for grinding the surface of the workpiece; an optical non-contact measurement mechanism for concentrically measuring the thickness of the workpiece at multiple radial measurement positions when grinding by the workpiece grinding mechanism is stopped midway; a tilt mechanism for adjusting the tilt angle of the chuck table; and a control mechanism for adjusting the tilt angle of the chuck table by controlling the tilt mechanism based on the measurement values ​​by the measurement mechanism, wherein the control mechanism calculates each of the concentric average values ​​at the multiple measurement positions measured by the measurement mechanism, calculates a polynomial line in the surface shape of the workpiece from each of the average values, controls the tilt mechanism based on the polynomial line to adjust the tilt angle of the chuck table, and restarts grinding of the surface of the workpiece.

[0009] According to the workpiece machining device, the average values ​​of the concentric circles at a plurality of measurement positions measured by the measuring mechanism are calculated, and a polynomial line for the surface shape of the workpiece is calculated from the average values. Thus, the polynomial line can be approximated to the surface shape of the workpiece. Based on this approximated polynomial line, the tilt mechanism is controlled to adjust the tilt angle of the chuck table. This allows the tilt angle of the workpiece to be adjusted based on the polynomial line. In this state, grinding of the workpiece surface is restarted, whereby the TTV of the workpiece can be kept small and the surface of the workpiece can be machined flat. Thus, the workpiece can be machined to the target shape.

[0010] <2> the above <1> In the workpiece processing apparatus according to the present invention, the workpiece grinding mechanism may include at least a rough grinding unit that roughly grinds the workpiece, and a fine grinding unit that finish grinds the workpiece that has been roughly ground, and the tilt angle of the chuck table may be adjusted by controlling the tilt mechanism during the finish grinding.

[0011] According to the workpiece machining device, the tilt angle of the chuck table is adjusted during finish grinding, which makes it possible to effectively keep the TTV of the workpiece small and to effectively machine the surface of the workpiece to be flat.

[0012] <3> the above <1> or <2> In the workpiece machining apparatus according to the present invention, a singular point may be removed from the measurement values ​​at the plurality of measurement positions measured by the measuring mechanism.

[0013] According to the workpiece machining device, the tilt angle of the chuck table is adjusted by excluding the measurement value of the singular point from the multiple measurement values ​​measured by the measuring mechanism. Therefore, the polynomial line can be more closely approximated to the surface shape of the workpiece. As a result, by adjusting the tilt angle of the chuck table, the TTV of the workpiece can be more effectively kept small, and the surface of the workpiece can be more effectively machined to be flat.

[0014] <4> the above <3> In the workpiece machining device according to the present invention, the singular point may be a central portion of the workpiece.

[0015] Here, when grinding a workpiece, a singular point may exist in the center of the workpiece. Therefore, in the multiple measured values ​​obtained by the measuring mechanism, the center of the workpiece is treated as a singular point and the measured values ​​of the center are excluded. This allows the polynomial line to be more closely approximated to the surface shape of the workpiece. As a result, by adjusting the tilt angle of the chuck table, the TTV of the workpiece can be more effectively kept small, and the surface of the workpiece can be more effectively machined to be flat. Effect of the Invention

[0016] According to the present invention, the surface of the workpiece can be machined flat to machine the workpiece into a target shape. [Brief description of the drawings]

[0017] [Figure 1] 1 is a plan view showing a basic configuration of a workpiece machining device according to an embodiment of the present invention. [Diagram 2]4 is a conceptual diagram illustrating a process of grinding a wafer by the workpiece processing apparatus according to the embodiment. FIG. [Diagram 3] 13 is a graph illustrating a plurality of measurement positions in the radial direction of a wafer W according to the embodiment. [Figure 4] 11 is a cross-sectional view showing a surface shape of a wafer in which finish grinding is temporarily stopped midway according to the embodiment; FIG. [Diagram 5] 4 is a graph showing a first measurement value of the surface shape of the wafer shown in FIG. 3 measured by a second measurement mechanism. [Figure 6] 4 is a graph showing a second measurement value obtained by measuring the surface shape of the wafer shown in FIG. 3 after it has been finish-ground again using a second measuring mechanism. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, a workpiece machining device according to an embodiment of the present invention will be described with reference to the drawings. In the following embodiments, when the number, value, amount, range, etc. of components are mentioned, the number is not limited to the specific number, and may be more or less than the specific number, unless otherwise specified or when it is clearly limited to a specific number in principle.

[0019] In addition, when referring to the shape or positional relationship of components, etc., this includes things that are substantially similar or approximate to those shapes, etc., unless otherwise specified or considered to be clearly different in principle.

[0020] In addition, the drawings may exaggerate characteristic parts to make the features easier to understand, and the dimensional ratios of the components may not be the same as the actual ones. In addition, in cross-sectional views, hatching of some components may be omitted to make the cross-sectional structure of the components easier to understand.

[0021] Fig. 1 is a plan view showing the basic configuration of a workpiece processing device, and Fig. 2 is a conceptual diagram explaining a process of grinding a wafer by the workpiece processing device. 1 and 2, the workpiece processing device 1 is a device that holds the workpiece W at a predetermined grinding position and precisely grinds the workpiece W into a target shape (target thickness) by flattening the surface Ws of the held workpiece W. Hereinafter, the workpiece W will be described as a "wafer W." The wafer W is a silicon wafer, a silicon carbide wafer, or the like, but is not limited to these.

[0022] The workpiece machining device 1 includes a holding means 2, a workpiece grinding mechanism 3, a measuring mechanism 4, and a control mechanism 5. The holding means 2 includes an index table 11, a chuck table 12, and a tilt mechanism 13. A partition plate 15 is provided above the index table 11. The partition plate 15 is formed in a cross shape.

[0023] The index table 11 is divided by partition plates 15 into four stages at equal intervals: an alignment stage ST1, a rough grinding stage ST2, a medium grinding stage ST3, and a fine grinding stage ST4. The four stages, the alignment stage ST1, the rough grinding stage ST2, the medium grinding stage ST3, and the fine grinding stage ST4, are arranged in this order in a counterclockwise direction on the paper surface of FIG. 1. Hereinafter, the counterclockwise direction on the paper surface of FIG. 1 may be simply referred to as the "counterclockwise direction." The partition plates 15 prevent the machining fluid used in each stage from splashing onto an adjacent stage.

[0024] The index table 11 is supported so as to be rotatable counterclockwise around a rotation shaft 18. The index table 11 is provided with four chuck tables 12. The four chuck tables 12 are provided on the index table 11 so as to be positionable on an alignment stage ST1, a rough grinding stage ST2, a medium grinding stage ST3, and a fine grinding stage ST4. The index table 11 rotates counterclockwise in steps of 90° each time, whereby the chuck table 12 is transported (transferred) counterclockwise to the alignment stage ST1, the rough grinding stage ST2, the medium grinding stage ST3, and the fine grinding stage ST4 in that order.

[0025] The chuck table 12 is disposed so as to be rotatable about a rotation axis O via a tilt mechanism 13 described later. The chuck table 12 is provided with an adsorption body 12a made of porous ceramic embedded on the upper surface. The chuck table 12 adsorbs the wafer W placed on the adsorption body 12a with negative pressure. As a result, the center of the wafer W is aligned with the rotation axis O of the chuck table 12, and the wafer W is vacuum-adsorbed to the adsorption body 12a, thereby rotating and holding the wafer W integrally. That is, the wafer W rotates about the rotation axis O.

[0026] A wafer W transferred by a transfer device (not shown) or the like is attracted and held in a predetermined aligned position on the chuck table 12 of the alignment stage ST1. The wafer W attracted and held on the chuck table 12 is transferred to the rough grinding stage ST2 by the index table 11 rotating 90° counterclockwise.

[0027] The wafer W transported to the rough grinding stage ST2 has its surface Ws roughly ground (processed) by a later-described rough grinding unit 21. The roughly ground wafer W is transported to the intermediate grinding stage ST3 by the index table 11 rotating counterclockwise.

[0028] The wafer W transported to the medium grinding stage ST3 has its surface Ws medium-ground (processed) by the medium grinding unit 22, which will be described later. The wafer W that has been medium-ground is transported to the fine grinding stage ST4 by the index table 11 rotating 90° counterclockwise. The wafer W transferred to the precision grinding stage ST4 has its front surface Ws subjected to finish grinding (precision grinding) by a precision grinding unit 23, which will be described later.

[0029] The chuck table 12 is provided with a tilt mechanism 13. The tilt mechanism 13 adjusts the tilt angle (tilt angle) θ of the chuck table 12 by tilting the rotation axis O of the chuck table 12 in the XY direction (see FIG. 1). Thus, the tilt mechanism 13 can adjust the tilt angle θ of the wafer W held on the chuck table 12.

[0030] The workpiece grinding mechanism 3 grinds the surface Ws of the wafer W held on the chuck table 12 in the order of rough grinding stage ST2, medium grinding stage ST3, and fine grinding stage ST4. The workpiece grinding mechanism 3 grinds the surface Ws of the wafer W to thin the wafer W. The workpiece grinding mechanism 3 includes a rough grinding unit 21, a medium grinding unit 22, and a fine grinding unit 23.

[0031] The rough grinding unit 21 includes a rough grinding wheel 21a disposed above the rough grinding stage ST2. The rough grinding wheel 21a is supported by a feed device (not shown) so as to be movable up and down. The rough grinding wheel 21a roughly grinds the front surface Ws of the wafer W held on the rough grinding stage ST2.

[0032] The medium grinding unit 22 includes a medium grinding wheel 22a disposed above the medium grinding stage ST3. The medium grinding wheel 22a is supported by a feed device (not shown) so that it can be raised and lowered in the vertical direction. The medium grinding wheel 22a medium grinds the surface Ws of the wafer W disposed on the medium grinding stage ST3.

[0033] The precision grinding unit 23 includes a precision grinding wheel 23a disposed above the precision grinding stage ST4. The precision grinding wheel 23a is supported by a feed device (not shown) so as to be movable up and down. The precision grinding wheel 23a finish-grinds the surface Ws of the wafer W disposed on the precision grinding stage ST4.

[0034] The measurement mechanism 4 includes a first measurement mechanism 31 and a second measurement mechanism 32. The first measurement mechanism 31 is disposed, for example, on the precision grinding stage ST4. The first measurement mechanism 31 measures the thickness of the wafer W in an optical non-contact manner, and for example, a spectroscopic interference type thickness gauge (NCIG: Non-contact In-process Gauge) is used, but is not limited to this. The first measurement mechanism 31 measures the thickness of the wafer W transferred to the precision grinding stage ST4.

[0035] The second measuring mechanism 32 is disposed, for example, on the precision grinding stage ST4. The second measuring mechanism 32 measures the thickness of the wafer W in a state in which grinding by the precision grinding unit 23 of the workpiece grinding mechanism 3 is stopped midway. Specifically, the second measuring mechanism 32 is configured to be movable in the radial direction along the surface Ws of the wafer W from the outermost periphery We of the wafer W to the center Wc of the wafer W, for example.

[0036] The second measuring mechanism 32 measures the thickness of the wafer W in an optical non-contact manner, and for example, a spectroscopic interference type thickness measuring instrument (NCIG) is used, but is not limited to this. The second measuring mechanism 32 moves in the radial direction along the surface Ws of the wafer W in a state where the finish grinding of the wafer W is stopped midway and the wafer W is rotated. This allows the second measuring mechanism 32 to measure the thickness of the wafer W concentrically at multiple measurement positions in the radial direction. The multiple measurement positions in the radial direction of the wafer W are preferably, for example, four or more. Furthermore, it is preferable that singular points are excluded from the multiple measurement positions in the radial direction of the wafer W. Here, the singular point refers to a point where the thickness measurement value is significantly different from the thickness measurement value at other measurement positions. In addition, a measurement position where the thickness measurement value is significantly different from the other measurement positions among the multiple measurement positions in the radial direction is also called a singular point. In the embodiment, the singular point is mainly described as the center Wc of the wafer W, but the singular point may be the center Wc and the outermost periphery We of the wafer W.

[0037] Furthermore, in the embodiment, for example, eight or nine measurement positions in the radial direction of the wafer W will be described as an example. An example in which the measurement positions are eight positions will be described in detail in FIG. 3. An example in which the measurement positions are nine positions will be described in detail in FIG. 5 and FIG. 6.

[0038] The control mechanism 5 controls the operation of each of the components constituting the workpiece machining device 1. The control mechanism 5 is composed of, for example, a CPU (Central Processing Unit), a memory, etc. The functions of the control mechanism 5 may be realized by control using software, or may be realized by operation using hardware.

[0039] The control mechanism 5 adjusts the tilt angle θ of the chuck table 12 by controlling the tilt mechanism 13 based on the measurement value by the second measurement mechanism 32. That is, the control mechanism 5 obtains the average values ​​of the concentric circles at a plurality of measurement positions in the radial direction measured by the second measurement mechanism 32. The control mechanism 5 also obtains a polynomial with the obtained average values ​​as monomials, and obtains a polynomial line in the shape of the surface Ws of the wafer W from the polynomial. Furthermore, the control mechanism 5 calculates a correction value for correcting the surface shape of the wafer W based on the obtained polynomial line.

[0040] In addition, the control mechanism 5 controls the tilt mechanism 13 based on the calculated correction value to adjust the tilt angle θ of the chuck table 12. Furthermore, after adjusting the tilt angle θ of the chuck table 12, the control mechanism 5 restarts grinding of the surface Ws of the wafer W. Hereinafter, the shape of the surface Ws of the wafer W may be referred to as the "surface shape of the wafer W."

[0041] Next, an example in which the number of measurement positions in the radial direction of the wafer W is eight will be described with reference to FIG. Fig. 3 is a graph for explaining a plurality of measurement positions in the radial direction of the wafer W. In Fig. 3, the vertical axis indicates the thickness [THK (Thickness)] of the wafer W, and the horizontal axis indicates the measurement positions of the wafer W. The surface shape of the wafer W is indicated by G1. The measurement positions in the embodiment are indicated by black circles. The measurement positions in the comparative example are indicated by white circles.

[0042] As shown in FIG. 3, the comparative example has three measurement points: a measurement point P10 on the outermost circumference We of the wafer W, a measurement point P11 on the central portion Wc, and a measurement point P12 at the center between the outermost circumference We and the central portion Wc. Furthermore, in this comparative example, these three measurement points are used without being measured concentrically. In this case, any one of the three measurement points P10, P11, and P12 may be a singular point. Therefore, the polynomial line obtained from the measured values ​​of the three measurement points, the measurement point P10 on the outermost circumference We, the measurement point P11 on the central portion Wc, and the measurement point P12 at the center, cannot be approximated to the surface shape G1 of the workpiece W. As a result, the inclination angle θ of the wafer W held on the chuck table 12 cannot be properly adjusted based on the polynomial line obtained from the measured values ​​at three locations. Therefore, it is difficult to process the surface Ws of the workpiece W flat, and the workpiece W cannot be processed into a target shape.

[0043] In contrast, in the embodiment, eight measurement positions P1 to P8 are set between the outermost circumference We and the central portion Wc of the wafer W, and measurements are performed concentrically. By excluding the outermost circumference We and the central portion Wc, which are likely to become singular points, it is possible to approximate the polynomial line obtained from the eight measurement positions P1 to P8 to the surface shape G1 of the workpiece W. Furthermore, since the measurements are performed concentrically, even if a singular point occurs in a part of the circumferential direction at any of the measurement positions P1 to P8, the influence of the singular point can be reduced. Alternatively, the polynomial line can be created without considering the singular point. Therefore, a correction value for correcting the surface shape of the wafer W is calculated based on the polynomial line obtained from the eight measurement positions P1 to P8, and the tilt mechanism 13 is controlled based on the calculated correction value to properly adjust the tilt angle θ of the chuck table 12. This makes it possible to properly adjust the tilt angle θ of the wafer W held on the chuck table 12. Therefore, the surface Ws of the workpiece W can be processed flat to machine the workpiece W into a target shape.

[0044] Thus, according to the embodiment, a polynomial line can be approximated for the surface shape of the wafer W by using eight measurement positions (P1 to P8) between the outermost periphery We and the central portion Wc of the wafer W. This makes it possible to calculate a shape correction value from the approximated polynomial line, correct the inclination angle θ (i.e., the grinding angle), and perform finish grinding on the wafer W again to flatten the surface Ws of the workpiece W and to machine the workpiece W into a target shape.

[0045] In the embodiment of Fig. 3, eight measurement positions P1 to P8 are used as an example, but the number of measurement positions is not limited to eight positions P1 to P8. Also, in the embodiment of Fig. 3, two measurement positions, the outermost periphery We and the central portion Wc, are not included in the measurement positions, but only one position, the central portion Wc, may not be included in the measurement positions.

[0046] Next, a procedure for grinding the wafer W by the workpiece processing device 1 will be described with reference to FIGS. Fig. 4 is a cross-sectional view showing the surface profile of a wafer in which grinding is temporarily stopped midway during finish grinding. Fig. 5 is a graph showing first measured values ​​obtained by measuring the surface profile of the wafer shown in Fig. 3 using the second measurement mechanism. Fig. 6 is a graph showing second measured values ​​obtained by measuring the surface profile of the wafer shown in Fig. 3 after it has been finish-ground again using the second measurement mechanism.

[0047] Hereinafter, an example will be described in which the singular point on the surface Ws of the wafer W is the central portion Wc and the tilt angle θ of the chuck table 12 is adjusted excluding measurement position 29 on the central portion Wc, but the present invention is not limited to this. For example, the singular point on the surface Ws of the wafer W may be the outermost periphery We and the tilt angle θ of the chuck table 12 may be adjusted excluding the measurement position and measurement position 20 on the outermost periphery We. Also, the tilt angle θ of the chuck table 12 may be adjusted including the central portion Wc and the outermost periphery We.

[0048] 1, the surface Ws of the wafer W is roughly ground by a rough grinding wheel 21a at the rough grinding stage ST2. After the wafer W is roughly ground, the index table 11 is rotated 90° counterclockwise in the direction of the arrow A. Thus, the wafer W is transported from the rough grinding stage ST2 to the medium grinding stage ST3.

[0049] After the wafer W is transferred to the medium grinding stage ST3, the surface Ws of the wafer W is medium-ground by the medium grinding wheel 22a at the medium grinding stage ST3. After the wafer W is medium-ground, the index table 11 is rotated 90° counterclockwise in the direction of the arrow A. Thus, the wafer W is transferred from the medium grinding stage ST3 to the fine grinding stage ST4.

[0050] 1 and 2, the thickness of the wafer W transported to the precision grinding stage ST4 is measured by a first measurement mechanism 31. Based on the thickness of the wafer W measured by the first measurement mechanism 31, finish grinding of the surface Ws of the wafer W is started by the precision grinding wheel 23a. After the surface Ws of the wafer W is finish ground by the precision grinding wheel 23a for a predetermined time (or a predetermined amount), the finish grinding of the wafer W is stopped midway while the wafer W is rotated.

[0051] 2 to 5, after the finish grinding of the wafer W is stopped midway, the wafer W is rotated on its axis, and the second measurement mechanism 32 is moved in the radial direction along the surface Ws of the wafer W, as indicated by the arrow A. As a result, the second measurement mechanism 32 performs a first measurement of the thickness of the wafer W concentrically at a plurality of measurement positions P20 to P29 in the radial direction.

[0052] In the embodiment, the central portion Wc of the wafer W will be described as a singular point on the surface Ws of the wafer W. Therefore, except for the measurement value at measurement position P29 measured by the second measurement mechanism 32, the control mechanism 5 obtains each concentric average value of the measurement values ​​at measurement positions P20 to P28. In the embodiment, an example is described in which a plurality of measurement positions P20 to P29 are measured, and then the measurement value at measurement position P29 is excluded from the calculation of each concentric average value. However, measurement positions P20 to P28 may also be measured excluding measurement position P29.

[0053] A polynomial line G2 for the surface shape of the surface Ws of the wafer W is obtained from the average values ​​obtained by the control mechanism 5. Furthermore, the control mechanism 5 obtains a thickness THK1 of the wafer W and a difference TTV1 between the maximum and minimum values ​​of the thickness of the wafer W from the polynomial line G2. The control mechanism 5 also calculates a correction value for correcting the surface shape of the wafer W based on the obtained polynomial line G2. In addition, the control mechanism 5 controls the tilt mechanism 13 based on the calculated correction value to adjust the tilt angle θ of the chuck table 12. This makes it possible to adjust the inclination angle θ of the wafer W held on the chuck table 12. After adjusting the inclination angle θ of the wafer W, finish grinding of the surface Ws of the wafer W is started again by the fine grinding wheel 23a.

[0054] 2 and 6, after the surface Ws of the wafer W is finish-ground again with the fine grinding wheel 23a, the thickness of the wafer W is measured a second time concentrically at a plurality of measurement positions (P20 to P29) in the radial direction by the second measurement mechanism 32. Here, the control mechanism 5 calculates the average values ​​of the concentric measured values ​​at the measurement positions P20 to P28, excluding the measured value at the measurement position P29 at the center Wc of the wafer W, which is a singular point. Alternatively, during measurement, measurement positions P20 to P28 are measured excluding measurement position P29, and the control mechanism 5 determines the average values ​​of the measured values ​​at measurement positions P20 to P28 on concentric circles.

[0055] A polynomial line G3 for the surface shape of the surface Ws of the wafer W is obtained from the average values ​​obtained by the control mechanism 5. Furthermore, the thickness THK2 of the wafer W and the difference TTV2 between the maximum and minimum values ​​of the thickness of the wafer W are obtained from the polynomial line G3 by the control mechanism 5.

[0056] 5 and 6, the TTV2 in the second measurement can be made smaller than the TTV1 in the first measurement. This makes it possible to machine the surface Ws of the workpiece W flat and machine the workpiece W into the target shape.

[0057] 2, according to the workpiece machining apparatus 1 described above, the average values ​​of the concentric circles at a plurality of measurement positions measured by the second measuring mechanism 32 of the measuring mechanism 4 are calculated, and a polynomial line for the surface shape of the wafer W is calculated from the average values. Thus, the polynomial line can be approximated to the surface shape of the wafer W. The tilt mechanism 13 is controlled based on this approximated polynomial line to adjust the tilt angle θ of the chuck table 12. This allows the tilt angle θ of the wafer W to be adjusted based on the polynomial line. In this state, by restarting the finish grinding of the surface Ws of the wafer W, the TTV of the wafer W can be kept small and the surface Ws of the wafer W can be processed to be flat. Therefore, the wafer W can be processed to the target shape.

[0058] In addition, the inclination angle θ of the chuck table 12 is adjusted in finish grinding for precisely grinding the surface Ws of the wafer W. This makes it possible to effectively keep the TTV of the wafer W small and to effectively process the surface Ws of the wafer W into a flat surface.

[0059] Furthermore, in the multiple measurement values ​​measured by the second measuring mechanism 32 of the measuring mechanism 4, the tilt angle θ of the chuck table 12 is adjusted excluding the measurement value of the singular point. This allows the polynomial line to be more closely approximated to the surface shape of the wafer W. As a result, by adjusting the tilt angle θ of the chuck table 12, the TTV of the wafer W can be more effectively kept small and the surface Ws of the wafer W can be more effectively processed to be flat.

[0060] 2 and 4, when the surface Ws of the wafer W is finish ground, a singular point may exist at the center Wc of the wafer W. Therefore, in the multiple measurement values ​​measured by the second measurement mechanism 32 of the measurement mechanism 4, the central portion Wc of the wafer W is treated as a singular point and the measurement value of the central portion Wc is excluded. This makes it possible to more closely approximate the polynomial line to the surface shape of the wafer W. As a result, by adjusting the tilt angle θ of the chuck table 12, the TTV of the wafer W can be more effectively kept small and the surface Ws of the wafer W can be more effectively processed to be flat.

[0061] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the above embodiment, the workpiece grinding mechanism 3 is provided with three grinding units, i.e., the rough grinding unit 21, the medium grinding unit 22, and the fine grinding unit 23, and the wafer W is ground in stages at the three grinding stages ST2, ST3, and ST4. However, the present invention is not limited to this. As another example, the workpiece grinding mechanism 3 may be provided with two grinding units, i.e., the rough grinding unit 21 and the fine grinding unit 23, and the wafer W may be ground in stages at the two grinding stages. Furthermore, the finishing process may be polishing with an abrasive cloth, and the wafer W may be processed in stages in the order of rough grinding, fine grinding, and polishing.

[0062] In addition, the components in this embodiment can be replaced with well-known components as appropriate without departing from the spirit of the present invention. [Explanation of symbols]

[0063] 1 Workpiece processing equipment 2 Holding means 3 Workpiece grinding mechanism 4 Measuring mechanism 5 Control Mechanism 11 Index Table 12 Chuck table 13 Tilt mechanism 21 Rough grinding section 22 Medium grinding section 23 Precision grinding department 32 Second measurement mechanism W Wafer (work) Wc Center of wafer We Wafer outermost circumference Ws Wafer surface θ Tilt angle

Claims

1. In a workpiece processing device for processing a surface of a workpiece to be flat, A chuck table that rotates and holds the workpiece; a workpiece grinding mechanism for grinding the surface of the workpiece; an optical non-contact measuring mechanism for concentrically measuring the thickness of the workpiece at a plurality of measurement positions in a radial direction while grinding by the workpiece grinding mechanism is stopped midway; a tilt mechanism for adjusting the tilt angle of the chuck table; a control mechanism for adjusting a tilt angle of the chuck table by controlling the tilt mechanism based on a measurement value by the measurement mechanism, The control mechanism is calculating concentric average values ​​at the plurality of measurement positions measured by the measurement mechanism, calculating a polynomial line in the surface shape of the workpiece from the average values, controlling the tilt mechanism based on the polynomial line to adjust the tilt angle of the chuck table, and restarting grinding of the surface of the workpiece. A workpiece machining device characterized by the above.

2. The workpiece grinding mechanism includes: The grinding apparatus includes a rough grinding unit that roughly grinds the workpiece, and a fine grinding unit that finishes the workpiece that has been roughly ground, adjusting the tilt angle of the chuck table by controlling the tilt mechanism during the finish grinding; 2. The workpiece machining apparatus according to claim 1 .

3. The measurement values ​​at the plurality of measurement positions measured by the measurement mechanism are subjected to elimination of singular points.

3. The workpiece machining apparatus according to claim 1 or 2.

4. The singular point is the center of the workpiece; 4. The workpiece machining apparatus according to claim 3.

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