Grinding device and grinding method

Abstract

To provide a grinding device excellent in productivity which does not require re-grinding of the whole grinding surface even when a wafer held on a holding surface of a chuck table is ground in a horizontal direction from a side part.SOLUTION: Control means includes: a temporary positioning step S1 of temporarily positioning grinding means; a temporary polishing step S2 of temporarily grinding a part of a wafer held on a holding surface of a chuck table from a side part by means of a grindstone; a thickness measuring step S3 of measuring a thicknesses of a temporarily ground area of the wafer; a calculating step S4 of calculating a difference between a desired thickness and the thickness of the wafer measured in the thickness measuring step S3; a main positioning step S5 of positioning the grinding means at a Z-axis position at which the desired thickness is obtained by grinding the wafer, based on a value of the difference; a finish-grinding step S6 of actuating Y-axis feed means to grind the wafer held on the holding surface of the chuck table, by means of the grindstone to finish the wafer to the desired thickness.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a grinding apparatus for grinding the surface of a wafer and a grinding method for grinding the surface of a wafer. [Background technology]

[0002] Wafers with multiple devices such as ICs and LSIs formed on their surface along planned dividing lines are ground to the desired thickness using a grinding machine, and then separated into individual device chips using a dicing machine and laser processing machine. These are then used in electrical devices such as mobile phones and personal computers.

[0003] The grinding device is an in-feed grinding device (see, for example, Patent Document 1) that includes a rotatable chuck table having a holding surface that holds a wafer, grinding means that is rotatably provided with a grinding wheel having annularly arranged grinding stones that pass through the center of rotation of the wafer held on the holding surface of the chuck table and rotates to grind the wafer, Z-axis feed means that feeds the grinding means in the Z-axis direction perpendicular to the holding surface of the chuck table and grinds the wafer by contacting it from the top surface, thickness measurement means that measures the thickness of the wafer held on the holding surface of the chuck table, and control means, and a holding device that holds the wafer. There is known a creep feed grinding device (see, for example, Patent Document 2) that includes a chuck table having a holding surface, grinding means having a rotatable grinding wheel with a ring-shaped arrangement of grinding stones that grinds the wafer held on the holding surface of the chuck table from the side, Y-axis feed means that feeds the grinding means in the Y-axis direction parallel to the holding surface of the chuck table, Z-axis feed means that positions the grinding means at a predetermined Z-axis position in the Z-axis direction perpendicular to the holding surface of the chuck table, thickness measurement means that measures the thickness of the wafer held on the holding surface of the chuck table, and control means. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-021264 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-103192 Summary of the Invention [Problem to be solved by the invention]

[0005] In the in-feed grinding apparatus, a grinding wheel with a ring-shaped grinding stone is placed above the wafer, which is held on the holding surface of the chuck table and rotates, so as to pass through the center of rotation, and the entire back surface of the wafer is gradually ground. Therefore, the thickness of the wafer can be measured during the grinding process, and the grinding process can be continued until the wafer reaches the finished thickness. In contrast, in conventional creep feed grinding apparatuses, the wafer held on the holding surface of the chuck table is ground from the side in a horizontal direction parallel to the holding surface, making it difficult to measure the thickness of the wafer during the grinding process. Furthermore, since the grinding feed amount in the Z-axis direction is not changed during the grinding process, the grinding means is moved in the Y-axis direction to grind the entire back surface of the wafer, and then the thickness of the wafer after grinding is measured to determine whether the wafer has reached the desired thickness. If it is determined that the amount of grinding is insufficient, regrinding is performed to achieve the desired thickness. In a creep feed grinding device, it is possible to measure the thickness of the wafer before grinding, and based on the measurement results, position the grinding means at the desired position in the Z axis direction to perform grinding. However, because there are variations in the wear state of the grinding wheel and in the operation of the Z axis feed means that feeds the grinding means in the Z axis direction for processing, even if the thickness of the wafer can be measured before processing, it is difficult to precisely process it to the desired thickness in one grinding without regrinding. Instead, after grinding the entire back surface of the wafer once, the thickness must be measured and regrinding must be performed, which poses the problem of low productivity for creep feed grinding devices.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and its main technical object is to provide a grinding device and a grinding method that are highly productive, without having to re-grind the entire grinding surface, even when grinding a wafer held on the holding surface of a chuck table from the side in a horizontal direction. [Means for solving the problem]

[0007] In order to solve the above-mentioned main technical problem, according to the present invention, a grinding apparatus for grinding a surface of a wafer includes a chuck table having a holding surface for holding a wafer, grinding means rotatably provided with a grinding wheel having annularly arranged grinding stones for grinding the wafer held on the holding surface of the chuck table from the side, Y-axis feed means for feeding the grinding means in a Y-axis direction parallel to the holding surface of the chuck table, Z-axis feed means for feeding the grinding means in a Z-axis direction perpendicular to the holding surface of the chuck table, thickness measurement means for measuring the thickness of the wafer held on the holding surface of the chuck table, and control means, wherein the control means operates the Z-axis feed means to temporarily position the grinding means at a Z-axis position that does not reach the desired thickness obtained by grinding the wafer. a positioning step, a temporary grinding step in which the Y-axis feed means is operated to temporarily grind a portion of the wafer held on the holding surface of the chuck table from the side by the grinding stone, a thickness measurement step in which the thickness measurement means is operated to measure the thickness of the area of ​​the wafer that has been temporarily ground, a calculation step in which the difference between the desired thickness and the thickness of the wafer measured in the thickness measurement step is calculated, a final positioning step in which the Z-axis feed means is operated based on the value of the difference to position the grinding means at a Z-axis position where the desired thickness will be obtained by grinding the wafer, and a finish grinding step in which the Y-axis feed means is operated to grind the wafer held on the holding surface of the chuck table by the grinding stone to finish the wafer to the desired thickness.

[0008] Further, according to the present invention, there is provided a grinding method for grinding a surface of a wafer, the method comprising: a preparation step of preparing a grinding apparatus including a chuck table having a holding surface for holding a wafer; grinding means rotatably provided with a grinding wheel having annularly arranged grinding stones for grinding the wafer held on the holding surface of the chuck table from the side; Y-axis feed means for feeding the grinding means in a Y-axis direction parallel to the holding surface of the chuck table; Z-axis feed means for feeding the grinding means in a Z-axis direction perpendicular to the holding surface of the chuck table; thickness measurement means for measuring the thickness of the wafer held on the holding surface of the chuck table; and control means; a wafer holding step of holding the wafer on the holding surface of the chuck table; and a step of operating the Z-axis feed means to grind the wafer to a thickness that does not reach the desired thickness obtained by grinding the wafer. a temporary grinding step of operating the Y-axis feed means to temporarily grind a portion of the wafer held on the holding surface of the chuck table from the side with the grinding stone; a thickness measurement step of operating the thickness measurement means to measure the thickness of the region of the wafer that has been temporarily ground; a calculation step of calculating the difference between the desired thickness and the thickness of the wafer measured in the thickness measurement step; a final positioning step of operating the Z-axis feed means to position the grinding means at a Z-axis position where the desired thickness will be obtained by grinding the wafer based on the value of the difference; and a finish grinding step of operating the Y-axis feed means to grind the wafer held on the holding surface of the chuck table with the grinding stone to finish the wafer to the desired thickness. [Effects of the Invention]

[0009] The grinding apparatus of the present invention includes a chuck table having a holding surface for holding a wafer, grinding means rotatably provided with a grinding wheel having annularly arranged grinding stones for grinding the wafer held on the holding surface of the chuck table from the side, Y-axis feed means for feeding the grinding means in a Y-axis direction parallel to the holding surface of the chuck table, Z-axis feed means for feeding the grinding means in a Z-axis direction perpendicular to the holding surface of the chuck table, thickness measurement means for measuring the thickness of the wafer held on the holding surface of the chuck table, and control means, wherein the control means performs a temporary positioning step of operating the Z-axis feed means to temporarily position the grinding means at a Z-axis position that does not reach the desired thickness obtained by grinding the wafer, and operating the Y-axis feed means to grind a portion of the wafer held on the holding surface of the chuck table from the side by the grinding stone. a thickness measurement step of operating the thickness measurement means to measure the thickness of the region of the wafer that has been temporarily ground; a calculation step of calculating the difference between the desired thickness and the thickness of the wafer measured in the thickness measurement step; a final positioning step of operating the Z-axis feed means to position the grinding means at a Z-axis position where the desired thickness will be obtained by grinding the wafer based on the value of the difference; and a finish grinding step of operating the Y-axis feed means to grind the wafer held on the holding surface of the chuck table with the grinding wheel to finish the wafer to the desired thickness.This eliminates the need to measure the thickness of the wafer after the entire back surface of the wafer has been ground, and if the amount of grinding is insufficient, it is not necessary to grind the wafer again to the desired thickness, thereby solving the problem of poor productivity.

[0010] The grinding method of the present invention also includes a preparation step of preparing a grinding apparatus including a chuck table having a holding surface for holding a wafer, grinding means rotatably provided with a grinding wheel having annularly arranged grinding stones for grinding the wafer held on the holding surface of the chuck table from the side, Y-axis feed means for feeding the grinding means in a Y-axis direction parallel to the holding surface of the chuck table, Z-axis feed means for feeding the grinding means in a Z-axis direction perpendicular to the holding surface of the chuck table, thickness measurement means for measuring the thickness of the wafer held on the holding surface of the chuck table, and control means; a wafer holding step of holding the wafer on the holding surface of the chuck table; a temporary positioning step of operating the Z-axis feed means to temporarily position the grinding means at a Z-axis position that does not reach the desired thickness obtained by grinding the wafer; and a step of operating the Y-axis feed means to grind the wafer by the grinding stones. The method includes a temporary grinding step in which a portion of the wafer held on the holding surface of the table is temporarily ground from the side, a thickness measurement step in which the thickness measurement means is operated to measure the thickness of the area of ​​the wafer that has been temporarily ground, a calculation step in which the difference between the desired thickness and the thickness of the wafer measured in the thickness measurement step is calculated, a final positioning step in which the Z-axis feed means is operated based on the value of the difference to position the grinding means at a Z-axis position where the desired thickness will be obtained by grinding the wafer, and a finish grinding step in which the Y-axis feed means is operated to grind the wafer held on the holding surface of the chuck table with the grinding wheel to finish the wafer to the desired thickness.This eliminates the need to measure the thickness of the wafer after the entire back surface of the wafer has been ground, and if the amount of grinding is insufficient, there is no need to grind the wafer again to the desired thickness, thereby solving the problem of poor productivity. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is an overall perspective view of a grinding device according to an embodiment of the present invention; [Figure 2] 2 is a flowchart of control executed by a control unit of the grinding device shown in FIG. [Figure 3] 2 is a perspective view showing a manner in which a protective tape is adhered to a wafer to be ground by the grinding apparatus of FIG. 1. FIG. [Figure 4]FIG. 10A is a perspective view showing an embodiment of the temporary positioning step, and FIG. 10B is a side view showing the state when (a) is performed. [Figure 5] FIG. 1A is a perspective view showing an embodiment of a preliminary grinding step, and FIG. 1B is a perspective view showing a state after the preliminary grinding step is completed. [Figure 6] FIG. 10 is a perspective view showing an embodiment of a thickness measurement step. [Figure 7] (a) is a perspective view showing an embodiment of this positioning step, and (b) is a side view when (a) is performed. [Figure 8] (a) An oblique view showing an embodiment of the finish grinding step, (b) An oblique view showing the state after the finish grinding process shown in (a) is completed, and (c) An oblique view of the wafer after the finish grinding step is completed. DETAILED DESCRIPTION OF THE INVENTION

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a grinding apparatus and a grinding method configured based on the present invention will be described in detail with reference to the accompanying drawings.

[0013] 1 shows an overall perspective view of a grinding apparatus 1 prepared for carrying out the grinding method of the present invention for grinding the surface of a wafer. The grinding apparatus 1 includes a chuck table 3 having a holding surface 31 for holding a wafer 10 (e.g., a silicon (Si) wafer) as a workpiece, a grinding means 4 for grinding the wafer 10 held on the holding surface 31 of the chuck table 3, a Y-axis feed means (disposed inside the apparatus housing 2 and not shown) for processing and feeding the wafer 10 in a Y-axis direction parallel to the holding surface 31 of the chuck table 3, a Z-axis feed means 5 for processing and feeding the grinding means 4 in a Z-axis direction perpendicular to the holding surface 31 of the chuck table 3, a thickness measurement means 7 for measuring the thickness of the wafer 10 held on the holding surface 31 of the chuck table 3, and a control means 100. As described below, the grinding apparatus 1 is a so-called creep feed grinding apparatus that grinds the wafer 10 horizontally from the side.

[0014] The chuck table 3 includes a holding surface 31 that holds the wafer 10 by suction, and a frame 32 that supports the holding surface 31 and is connected to a suction source (not shown) to transmit negative pressure to the holding surface 31. The chuck table 3 is moved by the Y-axis feed means to any position in the Y-axis direction in the drawing, for example, a carry-in / out position on the front side in the drawing where the wafer 10 is carried in and out, and a grinding position directly below the grinding means 4 where grinding is performed.

[0015] The grinding means 4 includes at least a rotating shaft 41, a grinding wheel 42 disposed at the lower end of the rotating shaft 41, a plurality of grinding stones 43 disposed in an annular shape on the underside of the grinding wheel 42, an electric motor 44 for rotating the rotating shaft 41, a support part 45 for supporting the grinding means 4, and a Z-axis movable base 46 supported on the vertical wall part 2a of the device housing 2 so as to be movable up and down in the Z-axis direction together with the support part 45. Grinding water W is supplied to the upper end 41a of the rotating shaft 41, and is supplied to the grinding processing area of ​​the grinding stones 43 and the wafer 10 through a through-hole formed inside the rotating shaft 41.

[0016] The Z-axis feed means 5 converts the rotational motion of the pulse motor 51 into linear motion via a ball screw 52 rotated by the pulse motor 51 and transmits the linear motion to the Z-axis movable base 46. A position detection means 6 for detecting the Z-axis position of the grinding means 4 in the Z-axis direction is disposed between the grinding means 4 and the vertical wall 2a. The position detection means 6 includes, for example, a scale 61 disposed on the Z-axis movable base 46 and a sensor 62 disposed on the vertical wall 2a for reading the graduations of the scale 61. By reading the graduations of the scale 61 with the sensor 62, it is possible to detect the amount of movement of the grinding means 4 relative to a predetermined reference position in the Z-axis direction (for example, the position when the grinding means 4 is positioned at the uppermost position) Z0, i.e., the Z-axis position of the grinding means 4.

[0017] The thickness measurement means 7 includes a sensor base 70, an extension arm 71 extending from the sensor base 70, and a measurement beam irradiation unit 72 disposed at the tip of the extension arm 71. The sensor base 70 is disposed to the side of the area in the device housing 2 where the chuck table 3 moves, and the measurement beam irradiation unit 72 is positioned directly above the center position in the X-axis direction (width direction) perpendicular to the Y-axis direction in the area where the chuck table 3 moves.

[0018] The control means 100 is configured by a computer and includes a central processing unit (CPU) that performs calculations according to a control program, a read-only memory (ROM) that stores the control program, etc., a readable / writable random access memory (RAM) that temporarily stores detected values, calculation results, etc., an input interface, and an output interface (details not shown). The control means 100 of this embodiment is connected to and controls each operating unit of the grinding apparatus 1 (the electric motor 44 of the grinding means 4, the pulse motor 51 of the Z-axis feed means 5, the Y-axis feed means, etc.), and is also connected to the position detection means 6 and thickness measurement means 7. The position detection means 6 can detect the Z-axis position of the grinding means 4, and in cooperation with the Z-axis feed means 5, the grinding wheel 43 of the grinding means 4 can be positioned at a desired Z-axis position. In this embodiment, the Z-axis position of the grinding means 4 is the distance down from the reference position Z0, which is the position Z0 when the grinding wheel 43 is raised to the highest point, and is detected by the position detection means 6 described above.

[0019] The thickness measurement means 7 irradiates the wafer 10 held on the chuck table 3 with a measurement beam emitted from a broadband light source through a measurement beam irradiation unit 72, and receives the spectral interference waveform of the return light reflected by the wafer 10 with a light-receiving sensor (not shown) housed in the sensor base 70. The control means 100 performs a Fourier transform on the spectral interference waveform of the return light to calculate the thickness of the wafer 10 at the position irradiated with the measurement beam. Furthermore, the control means 100 is equipped with a control program 110 shown in the flowchart of FIG. 2, which is configured to execute the grinding method of this embodiment in which the grinding apparatus 1 grinds the wafer 10 to a desired thickness. Note that, for convenience of explanation, the control means 100 is shown outside the apparatus housing 2 in FIG. 1, but in reality it is housed inside the apparatus housing 2.

[0020] The measuring device 1 of this embodiment has roughly the configuration as described above, and performs the grinding method described below for grinding the wafer 10. The following description is of the procedure for grinding the wafer 10 to a desired thickness W0 (e.g., 100 μm) by performing the grinding method of this embodiment.

[0021] When carrying out the grinding method of this embodiment, first, the grinding apparatus 1 described above is prepared (preparation step). While the preparation step is being carried out, a wafer 10 before grinding, as shown in FIG. 3, is prepared. The wafer 10 before grinding is, for example, a wafer having a thickness of 300 μm, and a plurality of devices 12 formed on the surface 10a by dividing the wafer 10 along division lines 14. A protective tape T is attached to the surface 10a to form an integrated unit. The wafer 10 thus prepared is placed on the holding surface 31 of the chuck table 3 positioned at the transfer position shown in FIG. 1, and a suction source (not shown) is activated to hold the wafer 10 by suction (wafer holding step).

[0022] After the wafer holding step is performed, the control program 110 stored in the control means 100 shown in Fig. 2 is started, and first, a temporary positioning step S1 is executed. As shown in Fig. 4(a), the temporary positioning step S1 is a step in which the Z-axis feed means 5 is operated to lower the grinding means 4 in the direction indicated by arrow R1, and the lower end of the grinding wheel 43 of the grinding means 4 is temporarily positioned at a Z-axis position Z1 that does not reach the desired thickness (W0) obtained by grinding the wafer 10, as shown in Fig. 4(b). Although the Z-axis position of the grinding means 4 in this embodiment can be precisely controlled based on the position detection means 6, slight deviations (e.g., 5 to 10 µm) may occur in the grinding position by the grinding wheel 43 due to the wear state of the grinding wheel 43, etc. Therefore, the Z-axis position Z1 in this embodiment is set to a thickness that does not reach the desired thickness (W0) without excessively grinding the wafer 10 even when the side portion 10c of the wafer 10 is ground by the grinding wheel 43 of the grinding means 4. In this embodiment, the thickness W1 of the wafer 10 after grinding is W1 = W0 + 50 to 100 [μm] Set the Z-axis position Z1 so that the thickness is about this.

[0023] After the temporary positioning step is performed, the temporary grinding step S2 of the control program 110 shown in FIG. 2 is executed. More specifically, after the grinding wheel 43 of the grinding means 4 is positioned at Z-axis position Z1 in the Z-axis direction by the temporary positioning step, the electric motor 44 is operated to rotate the rotation shaft 41 of the grinding means 4 in the direction indicated by arrow R2, as shown in FIG. 5(a). At the same time, the Y-axis feed means is operated to feed the chuck table 3 in the Y-axis direction parallel to the holding surface 31, in the direction indicated by arrow R3, to temporarily grind only a predetermined portion of the wafer 10 from the side 10c (temporary grinding step). After the temporary grinding step is completed, the Z-axis feed means 5 is operated to lift the grinding means 4 in the direction indicated by arrow R4 and move the chuck table 3 in the direction indicated by arrow R5, exposing the temporary ground area 10d. The temporary ground region 10d is a partial region that does not cover the entire back surface 10b of the wafer 10, and is formed at least large enough to allow thickness measurement by the thickness measurement means 7, which will be described later. Note that, although striped grinding marks (shown by dashed lines) are shown in Fig. 5(b) on the ground temporary ground region 10d, these grinding marks are added for convenience of explanation, and in reality, the ground surface of the temporary ground region 10d is ground to be approximately flat.

[0024] After the preliminary grinding step described above is performed, a thickness measurement step S3 of the control program 110 is executed. To execute the thickness measurement step S3, the Y-axis feed means is operated to position the preliminary grinding area 10d of the wafer 10 held on the chuck table 3 directly below the measurement beam irradiation unit 72 of the thickness measurement means 7, as shown in FIG. 6. Next, a measurement beam L emitted from a broadband light source (not shown) is irradiated toward the preliminary grinding area 10d. The measurement beam L irradiated onto the preliminary grinding area 10d is reflected by the upper and lower surfaces of the wafer 10 in the preliminary grinding area 10d to become return light. The return light is dispersed into individual wavelengths by a diffraction grating (not shown) disposed in the thickness measurement means 7, and the light intensity for each wavelength is detected by a light-receiving sensor (not shown). Arithmetic processing such as Fourier transform is then performed to measure the thickness W1 of the wafer 10 in the preliminary grinding area 10d after the preliminary grinding step (thickness measurement step). In this embodiment, the measured thickness W1 is 158 μm.

[0025] After the thickness measurement step is performed, a calculation step S4 is performed to calculate the difference ΔZ between the desired thickness W0 and the thickness of the wafer 10 measured in the thickness measurement step S3, more specifically, the thickness W1 of the temporary grinding region 10d. In this embodiment, as described above, W0=100 μm and W1=158 μm, so ΔZ=W1−W0=58 μm.

[0026] When ΔZ=58 μm is calculated by performing the above calculation step, a final positioning step S5 is performed in which the grinding means 4 is positioned on the Z axis at a position that will result in the desired thickness W0 obtained by grinding the wafer 10, based on the value of the difference ΔZ. In this final positioning step S5, as shown in Fig. 7(a), the Z axis feed means 5 is operated to lower the grinding means 4 in the direction indicated by arrow R6, and the lower end position of the grinding wheel 43 of the grinding means 4 is positioned at a Z axis position = Z1 + ΔZ, with position Z0 when the grinding wheel 43 is raised to the highest position as the reference position, as shown in Fig. 7(b) (final positioning step).

[0027] After the main positioning step is performed, the electric motor 44 of the grinding means 4 is operated to rotate the rotary shaft 41 in the direction indicated by R2 as shown in Fig. 8(a), and the Y-axis feed means is operated to feed the chuck table 3 in the direction indicated by arrow R7 parallel to the holding surface 31 of the chuck table 3. As shown in Fig. 8(b), a finish grinding step S6 is performed in which the entire area from the side 10c of the wafer 10 to the back surface 10b of the wafer 10 is ground using the grinding wheel 43 (finish grinding step). As a result, the provisional grinding area 10d is precisely ground by ΔZ (= 58 μm) to the desired thickness W0 (100 μm), and other areas of the back surface 10b of the wafer 10 are also ground to form a main ground surface 10e having a thickness of 100 μm across the entire area of ​​the wafer 10 as shown in Fig. 8(c) (finish grinding step). In addition, Figure 8(c) also shows striped grinding marks (shown by dashed lines) on the ground surface 10e, but like the temporary ground area 10d shown in Figure 5(b), this is added for the sake of convenience of explanation, and the actual ground surface 10e is approximately flat.

[0028] According to the grinding apparatus 1 and grinding method of this embodiment, after the entire back surface 10b of the wafer 10 is ground, the thickness of the wafer 10 is measured, and if the amount of grinding is insufficient, there is no need to grind the wafer 10 again to the desired thickness W0, thereby eliminating the problem of poor productivity. [Explanation of symbols]

[0029] 1: Grinding device 2: Device housing 3: Chuck table 31: Holding surface 32:Frame body 4: Grinding means 41: Rotation axis 42: Grinding wheel 43: Grinding wheel 44: Electric motor 45: Support part 46:Z-axis moving base 5: Z-axis feed means 51: Pulse motor 52: Ball screw 6: Position detection means 61: Scale 62: Sensor 7: Thickness measurement means 71: Extension arm 72: Measurement beam irradiation unit 10: Wafer 10a: surface 10b: Back side 10c: Side 10d: Temporary grinding area 10e: Mainly ground surface 12: Device 14: Planned division line 100: Control means 110: Control program W: Grinding water T: Protective tape

Claims

1. A grinding apparatus for grinding a surface of a wafer, a chuck table having a holding surface for holding a wafer; grinding means rotatably provided with a grinding wheel having annularly arranged grinding stones for grinding the wafer held on the holding surface of the chuck table from the side; Y-axis feed means for feeding the grinding means in a Y-axis direction parallel to the holding surface of the chuck table; Z-axis feed means for feeding the grinding means in a Z-axis direction perpendicular to the holding surface of the chuck table; thickness measurement means for measuring the thickness of the wafer held on the holding surface of the chuck table; and control means, The control means a temporary positioning step of operating the Z-axis feed means to temporarily position the grinding means at a Z-axis position that does not reach the desired thickness obtained by grinding the wafer; a preliminary grinding step of operating the Y-axis feed means to temporarily grind a part of the wafer held on the holding surface of the chuck table from the side by the grinding wheel; a thickness measuring step of operating the thickness measuring means to measure the thickness of the pre-ground region of the wafer; a calculation step of calculating a difference between the desired thickness and the thickness of the wafer measured in the thickness measurement step; a main positioning step of operating the Z-axis feed means based on the difference value to position the grinding means at a Z-axis position where the wafer is ground to a desired thickness; a finish grinding step in which the Y-axis feed means is operated to grind the wafer held on the holding surface of the chuck table with the grinding wheel, thereby finishing the wafer to a desired thickness; A grinding device comprising:

2. A grinding method for grinding a surface of a wafer, comprising: a preparation step of preparing a grinding device including: a chuck table having a holding surface for holding a wafer; grinding means rotatably provided with a grinding wheel having annularly arranged grinding stones for grinding the wafer held on the holding surface of the chuck table from the side; Y-axis feed means for feeding the grinding means in a Y-axis direction parallel to the holding surface of the chuck table; Z-axis feed means for feeding the grinding means in a Z-axis direction perpendicular to the holding surface of the chuck table; thickness measurement means for measuring the thickness of the wafer held on the holding surface of the chuck table; and control means; a wafer holding step of holding the wafer on a holding surface of a chuck table; a temporary positioning step of operating the Z-axis feed means to temporarily position the grinding means at a Z-axis position that does not reach the desired thickness obtained by grinding the wafer; a temporary grinding step of temporarily grinding a part of the wafer held on the holding surface of the chuck table from a side by the grinding wheel by operating the Y-axis feed means; a thickness measuring step of operating the thickness measuring means to measure the thickness of the pre-ground region of the wafer; a calculation step of calculating a difference between the desired thickness and the thickness of the wafer measured in the thickness measurement step; a main positioning step of operating the Z-axis feed means based on the difference value to position the grinding means at a Z-axis position where the wafer will be ground to a desired thickness; a finish grinding step in which the Y-axis feed means is operated to grind the wafer held on the holding surface of the chuck table with the grinding wheel, thereby finishing the wafer to a desired thickness; A grinding method comprising:

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