TW202346024A - Grinding device and wafer grinding method capable of uniformizing the grinding time and amount of each chuck table - Google Patents

Abstract

The present invention provides a grinding device and a wafer grinding method. In the grinding device that performs grinding with a first grinding tool and a second grinding tool, grinding time periods and amounts at each chuck table performed by the second grinding tool can be uniformized to achieve an effective wafer grinding. The grinding device has a turntable (30) equipped with a plurality of chuck tables (31), which uses a control unit (80) to position the chuck tables (31) at a first grinding position where the first grinding tool (51) grinds the wafer (90) and at a second grinding position where the second grinding tool (61) grinds the wafer, and uses a first tilt control unit (81) to control a tilt adjustment mechanism (33) to make a chuck disc spindle (312) of the chuck tables (31) positioned at the first grinding position reach a preset angle with respect to a first spindle (52), and a second tilt control unit (82) to control the tilt adjustment mechanism (33) to make the chuck disc spindle (312) of the chuck tables (31) positioned at the second grinding position reach a preset angle with respect to a second spindle (62).

Description

Grinding device and wafer grinding method

The invention relates to a grinding device and a wafer grinding method.

In the grinding device, the chuck table holding the wafer rotates, and the grindstone arranged annularly on the grinding wheel contacts the wafer while rotating, thereby grinding the wafer. Conventionally, as this type of grinding device, it is known to confirm the thickness tendency of the wafer in the radial direction and correct the inclination of the rotation axis of the chuck table with respect to the rotation axis of the grindstone (for example, Patent Documents 1 and 2). For example, the thickness tendency of the wafer can be confirmed by measuring the thickness of the wafer at three locations in the radial direction of the wafer: near the center, near the outer periphery, and at an intermediate position.

Furthermore, the grinding device is provided with: a rough grinding unit that grinds the wafer with a rough grinding stone; and a fine grinding unit that grinds the wafer with a fine grinding stone and rotates a rotary table equipped with two or more chuck tables. Each chuck table is positioned at a grinding position using a rough grinding stone and a grinding position using a fine grinding stone (for example, Patent Document 2). [Known technical documents] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2016-016462 [Patent Document 2] Japanese Patent Application Publication No. 2013-119123

[Problem to be solved by the invention] Conventionally, in a grinding device equipped with a rough grinding unit and a fine grinding unit, from the viewpoint that the wafer has a uniform thickness tendency during the fine grinding stage, the chuck table is used to correct the thickness tendency of the wafer. The tilt adjustment of the rotation axis is performed at the grinding position performed by the fine grinding stone. Therefore, in the stage of grinding with a rough grinding stone, the thickness of the wafers on each chuck table may not tend to be uniform. In this case, in order to eliminate the deviation in thickness tendency, the grinding amount when grinding with a fine grinding stone will vary for each chuck table, and there will be a problem of deviation in the grinding time. If the time required for fine grinding varies depending on each chuck table, the wafer production efficiency will deteriorate.

The present invention was made in view of this point, and its object is to provide a grinding device and a wafer grinding method for grinding with a first grindstone and a second grindstone, so that each grinding wheel when grinding with the second grindstone can be used. The grinding time and grinding amount of the chuck table are uniformized, thereby achieving efficient wafer grinding.

[Technical means to solve the problem] One aspect of the present invention is a grinding device including: a chuck table that holds a wafer with a conical holding surface; and a chuck rotation unit that rotates the chuck with a chuck spindle passing through the center of the holding surface. The table rotates; the tilt adjustment mechanism changes the tilt of the chuck spindle; the first grinding mechanism rotates the first spindle equipped with an annular first grindstone, and grinds with the first grindstone to be held on the a wafer held on the holding surface; a second grinding mechanism that rotates a second spindle equipped with an annular second grinding stone, and grinds the wafer held on the holding surface with the second grinding stone; a rotating table, A plurality of the chuck tables are configured; and a control part that rotates the rotary table to position the chuck table at a first grinding position where the first grinding stone grinds and a second grinding position where the second grinding stone grinds. A grinding position, wherein the grinding device is provided with: a first tilt control part, which rotates the turntable through the control part to position the chuck spindle of the chuck table at the first grinding position relative to The first spindle controls the tilt adjustment mechanism so that the first spindle reaches a preset angle; and the second tilt control part rotates the rotary table through the control part to position the chuck in the second grinding position. The tilt adjustment mechanism is controlled so that the main axis of the chuck of the table reaches a preset angle relative to the second main axis.

The grinding device includes: a thickness measuring device that measures the thickness of the wafer ground by the first grinding stone; and a thickness tendency calculation unit that calculates the thickness in a radius portion of the wafer ground by the first grinding stone. The measuring instrument measures the thickness at at least three places and calculates the thickness tendency of the wafer, and the first tilt control unit has the function of finding the difference between the thickness tendency calculated by the thickness tendency calculation unit and a predetermined thickness tendency set in advance. The calculation unit then controls the tilt adjustment mechanism based on the difference so that the wafer ground by the first grinding stone has a predetermined thickness tendency.

One aspect of the present invention is a wafer grinding method that rotates a rotary table equipped with a plurality of chuck tables holding wafers, and grinds the wafers held on the chuck table with a first grinding stone, The second grinding stone is used to grind the wafer to a predetermined thickness. The wafer grinding method consists of the following steps: a holding step, which holds the wafer on the chuck table; and an initial grinding step, which after the holding step, Grinding the wafer with the first grinding stone; a thickness measurement step, which measures the thickness at at least three places in the radial direction of the wafer ground by the initial grinding step; a thickness tendency calculation step, which measures from the thickness measurement step Calculate the thickness tendency of the wafer using at least three thickness values; and a tilt adjustment step, which adjusts the chuck spindle of each chuck table in such a way that the thickness tendency calculated by the thickness tendency calculation step is consistent with the preset thickness tendency. the tilt relative to the first spindle; the first grinding step, which uses the first grindstone to grind the wafer held by the chuck table adjusted by the tilt adjustment step; and the second grinding step, which rotates the rotary table, The second grinding stone is used to grind the wafer ground in the first grinding step.

The wafer ground in the initial grinding step can be ground in the first grinding step.

[Invention effect] According to the grinding device and the wafer grinding method of the present invention, after the inclination of the chuck table is adjusted at the position where grinding is performed with the first grinding stone (the first grinding position), grinding is performed with the first grinding stone. This can make the grinding amount of the second grinding stone uniform, thereby achieving efficient wafer grinding.

Hereinafter, the grinding device and the wafer grinding method will be described with reference to the accompanying drawings. Fig. 1 is a perspective view of the grinding device according to this embodiment. In addition, the grinding device to which the present invention is applied only needs to perform grinding by the first grinding stone and grinding by the second grinding stone on the wafer, and is not limited to the structure shown in FIG. 1 .

The grinding device 1 shown in FIG. 1 is a fully automatic type processing device, and is configured to fully automatically carry out loading processing, rough grinding processing, and fine grinding processing of the wafer 90 that is a workpiece. A series of operations consisting of cleaning and removal.

The wafer 90 is formed into a substantially disc shape and is loaded into the grinding device 1 with a protective film (not shown) attached to the lower surface. In addition, the wafer 90 can be a semiconductor substrate such as silicon or gallium arsenide, an inorganic material substrate such as ceramics, glass, sapphire, etc., or a packaging substrate for semiconductor products. In addition, the wafer 90 can also be moved into the grinding device 1 without a protective film attached to the lower surface.

The X-axis direction, the Y-axis direction, and the Z-axis direction in the grinding device 1 have a mutually perpendicular relationship. The X-axis direction and the Y-axis direction are approximately horizontal directions, and the Z-axis direction is the up-down direction (vertical direction). Among the two arrows indicating the direction of the X-axis, let the side of the text marked with an Among the two arrows indicating the Y-axis direction, set the side of the text marked Y to the left, and set the side of the text not marked Y to the right. Among the two arrows indicating the direction of the Z axis, set the side with text marked Z as upper, and set the side with text not marked with Z as lower.

A pair of cassettes 11 accommodating a plurality of wafers 90 is mounted on the front side of the base 10 of the grinding device 1 . Behind the pair of cassettes 11, a robot 12 for moving the wafer 90 in and out of the cassettes 11 is provided. The robot hand 12 is composed of a hand 14 provided at the front end of a robot arm 13 composed of a multi-section link.

A positioning mechanism 15 for positioning the wafer 90 before grinding is provided on the right oblique rear of the robot arm 12 . The positioning mechanism 15 is composed of a plurality of positioning pins 17 arranged around the temporary stand 16 and capable of moving forward and backward in the radial direction of the temporary stand 16 . In the positioning mechanism 15 , the plurality of positioning pins 17 contact the outer peripheral edge of the wafer 90 placed on the temporary stage 16 to position the center of the wafer 90 to be consistent with the center of the temporary stage 16 .

A cleaning mechanism 18 for cleaning the grinded wafer 90 is provided obliquely to the left behind the robot arm 12 . The cleaning mechanism 18 is composed of various nozzles (not shown) that spray cleaning water and dry air toward the rotating table (not shown). In the cleaning mechanism 18 , the rotating table holding the wafer 90 is lowered into the base 10 , and cleaning water is sprayed into the base 10 . After the wafer 90 is rotated and cleaned, dry air is sprayed to dry the wafer 90 .

The robot 12 transports the wafer 90 before grinding from the cassette 11 to the positioning mechanism 15 , and transports the wafer 90 after grinding from the cleaning mechanism 18 to the cassette 11 .

Between the positioning mechanism 15 and the cleaning mechanism 18, there is provided: a loading mechanism 20, which carries the wafer 90 before grinding and processing into the chuck table 31; and a carrying out mechanism 23, which removes the ground wafer 90 from the chuck table. 31 Move out.

The loading mechanism 20 is configured by providing a holding pad 22 on the base 10 at the front end of a support arm 21 that is rotatable about an axis in the Z-axis direction. In the loading mechanism 20 , the wafer 90 is attracted and held by the holding pad 22 , the wafer 90 is lifted from the temporary stage 16 , and the holding pad 22 is rotated by the support arm 21 , thereby loading the wafer 90 into the chuck. Taiwan 31.

The unloading mechanism 23 is configured by providing a holding pad 25 on the base 10 at the front end of a support arm 24 that is rotatable about an axis in the Z-axis direction. In the unloading mechanism 23 , the wafer 90 is sucked and held by the holding pad 25 , the wafer 90 is lifted from the chuck table 31 , and the holding pad 25 is rotated by the support arm 24 to remove the wafer 90 from the chuck. The disk table 31 is moved out to the cleaning mechanism 18 .

A rotary table 30 is provided behind the loading mechanism 20 and the unloading mechanism 23, and three chuck tables 31 are arranged at equal intervals in the circumferential direction. The turntable 30 is rotatable about the rotation axis in the Z-axis direction, and is rotationally driven by a table drive mechanism (not shown).

As shown in FIG. 2 , each chuck table 31 is provided with a porous porous member 32 at the upper part, and the porous member 32 is connected to a suction source (not shown). The upper surface of the porous member 32 serves as a holding surface 321 that attracts and holds the wafer 90 . Each chuck table 31 is supported rotatably about a central axis 311 passing through the center of the holding surface 321 . The structure supporting the chuck table 31 will be described later.

As shown in FIG. 2 , the holding surface 321 of each chuck table 31 is formed into a conical surface whose apex is located on the central axis 311 and gradually becomes lower toward the outer peripheral side of the chuck table 31 . The wafer 90 placed on the chuck table 31 is held while following the conical shape of the holding surface 321 . When the wafer 90 held by suction and holding is adhered with a protective adhesive film, the holding surface 321 attracts and holds the protective adhesive film, and attracts and holds the wafer 90 through the protective adhesive film. In addition, in FIG. 2 , the inclination of the holding surface 321 with respect to the horizontal direction and the inclination of the central axis 311 with respect to the vertical direction are exaggeratedly depicted, but they are actually slight inclinations that cannot be visually recognized.

The turntable 30 rotates intermittently at intervals of 120 degrees, and each of the three chuck tables 31 is sequentially positioned at a loading and unloading position for loading and unloading the wafer 90 by the loading mechanism 20 and the loading mechanism 23. The first grinding stone 51 of a grinding mechanism 50 grinds the first grinding position of the wafer 90 , and the second grinding stone 61 of the second grinding mechanism 60 grinds the second grinding position of the wafer 90 . In the first grinding position, the wafer 90 on the chuck table 31 is roughly ground to a predetermined thickness by the first grindstone 51 . In the second grinding position, the wafer 90 on the chuck table 31 is finely ground to a finished thickness by the second grindstone 61 .

In the first grinding mechanism 50 , the lower end of the first spindle 52 extending in the Z-axis direction is provided with a disc-shaped mounting part 53 , and a grinding wheel 54 is mounted on the lower part of the mounting part 53 . The first grindstone 51 is annularly arranged on the lower surface of the grinding wheel 54 .

In the second grinding mechanism 60 , the lower end of the second spindle 62 extending in the Z-axis direction is provided with a disc-shaped mounting piece 63 , and a grinding wheel 64 is mounted on the lower part of the mounting piece 63 . The second grindstone 61 is annularly arranged on the lower surface of the grinding wheel 64 .

The first spindle 52 and the second spindle 62 are, for example, air spindles, and are supported by high-pressure air to rotate about the axis in the Z-axis direction.

The first grindstone 51 and the second grindstone 61 are made of, for example, a diamond grindstone, which is formed by fixing diamond abrasive grains with a bonding agent such as a metal bonding material or a resin bonding material. The second grindstone 61 is formed of abrasive grains having a finer particle diameter than the first grindstone 51 .

A cylinder 101 supporting the first grinding mechanism 50 and a cylinder 102 supporting the second grinding mechanism 60 are erected behind the first grinding position and the second grinding position in the rotary table 30 .

A first lifting mechanism for moving the first grinding mechanism 50 up and down is provided on the front surface of the column 101 . The first lifting mechanism is provided with a pair of parallel guide rails 55 (only one is shown in the figure) extending in the Z-axis direction on the front surface of the column 101, and is provided with a ball screw 56 extending in the Z-axis direction between the pair of guide rails 55. The lift table 57 is supported slidably in the Z-axis direction relative to a pair of guide rails 55 . The first grinding mechanism 50 is supported through the housing 58 on the front surface of the lifting platform 57 . A ball screw 56 is screwed to the back side of the lift table 57 , and a motor 59 is connected to one end of the ball screw 56 . The ball screw 56 is rotationally driven by the motor 59 , thereby moving the first grinding mechanism 50 in the Z-axis direction along the guide rail 55 .

A second lifting mechanism for moving the second grinding mechanism 60 up and down is provided on the front surface of the column 102 . The second lifting mechanism is provided with a pair of parallel guide rails 65 (only one is shown in the figure) extending in the Z-axis direction on the front surface of the column 102, and is provided with a ball screw 66 extending in the Z-axis direction between the pair of guide rails 65. The lift table 67 is supported slidably in the Z-axis direction relative to the pair of guide rails 65 . The second grinding mechanism 60 is supported through the housing 68 on the front surface of the lifting platform 67 . A ball screw 66 is screwed to the back side of the lift table 67 , and a motor 69 is connected to one end of the ball screw 66 . The ball screw 66 is rotationally driven by the motor 69 , thereby moving the second grinding mechanism 60 in the Z-axis direction along the guide rail 65 .

Thickness measuring gauges 70 and 71 are provided near the turntable 30 . The thickness measuring gauge 70 measures the thickness of the wafer 90 held by the chuck table 31 at the first grinding position positioned below the first grinding mechanism 50 . The thickness measuring gauge 71 measures the thickness of the wafer 90 held by the chuck table 31 at the second grinding position positioned below the second grinding mechanism 60 .

Thickness measuring gauges 70 and 71 respectively include: reference height gauges 701 and 711, which measure the height position of the holding surface 321 of the chuck table 31; and wafer height gauges 702 and 712, which measure the upper surface of the wafer 90. The height of the surface. The reference height gauges 701 and 711 are contact type height gauges that bring the contact element into contact with the holding surface 321 and detect the height position of the holding surface 321 from the height of the contact position. Similarly, the wafer height gauges 702 and 712 are contact type height gauges that bring the contactor into contact with the upper surface of the wafer 90 and detect the height position of the upper surface of the wafer 90 from the height of the contact position. Then, the thickness of the wafer 90 is measured based on the difference between the measured values of the reference height gauges 701 and 711 and the measured values of the wafer height gauges 702 and 712 .

Furthermore, a non-contact thickness measuring device 72 is provided near the thickness measuring gauge 71 . The thickness measuring device 72 measures the thickness of the wafer 90 held by the chuck table 31 at the second grinding position positioned below the second grinding mechanism 60 .

As shown in FIG. 2 , the thickness measuring instrument 72 includes a bracket 721 erected on the outer peripheral side of the turntable 30 and a support arm 722 extending from the bracket 721 toward the upper side of the chuck table 31 . Three sensors 723, 724, 725 are installed. The three sensors 723 , 724 , and 725 are arranged at different positions in the radial direction of the wafer 90 held on the chuck table 31 .

Each of the sensors 723 , 724 , and 725 of the thickness measuring device 72 irradiates laser light from above the wafer 90 to measure the thickness of the wafer 90 .

For example, the thickness measuring device 72 uses each of the sensors 723, 724, and 725 to receive the upper surface reflected light when the laser light is reflected by the upper surface of the wafer 90 and the lower surface reflected light when the laser light is reflected by the lower surface of the wafer 90. The thickness of the wafer 90 is measured using a spectroscopic interference method that uses the principle of interference between the upper surface reflected light and the lower surface reflected light.

As another example of the thickness measuring device 72, each sensor 723, 724, 725 receives the laser light reflected by the upper surface of the wafer 90 and measures the height position of the upper surface of the wafer 90, and uses Each sensor 723, 724, 725 receives the holding surface reflected light reflected by the holding surface 321 of the Beka table 31 to measure the height position of the holding surface 321, and calculates the height of the upper surface of the wafer 90 and the height of the holding surface 321. The difference in height measures the thickness of wafer 90.

In the thickness gauge 72 , three sensors 723 , 724 , and 725 may be used to measure the thickness at three locations in the radial portion of the wafer 90 . More specifically, the thickness of the wafer 90 near the center is measured by the sensor 723 provided on the front end side of the support arm 722 , and the sensor 725 provided on the base end side of the support arm 722 The thickness of the wafer 90 near the outer periphery is measured, and the thickness of the wafer 90 in the middle of the radial direction is measured by the sensor 724 disposed in the middle of the support arm 722 .

As shown in FIGS. 3 to 6 , each chuck table 31 is provided with a cylindrical chuck spindle 312 centered on a central axis 311 below the porous member 32 . The tilt of the chuck spindle 312 can be adjusted by the tilt adjustment mechanism 33 . Specifically, the portion of the wafer 90 that is shaped along the conical holding surface 321 and is in contact with the first grindstone 51 and the second grindstone 61 is in contact with the first grindstone 51 when viewed from the side. The inclination of the chuck spindle 312 is adjusted using the inclination adjustment mechanism 33 so that the lower surface and the lower surface of the second grindstone 61 become parallel.

The tilt adjustment mechanism 33 includes a support base 34 and a position adjustment unit 35 and a fixed support part 36, which are connected to the support base 34 (see FIG. 6 ). The support base 34 includes a cylindrical support tube portion 341 and a disc-shaped flange 342 formed by enlarging the diameter of the lower portion of the support tube portion 341 . The tilt adjustment mechanism 33 operates the position adjustment unit 35 and tilts the flange 342 with the fixed support portion 36 as a fulcrum, thereby adjusting the tilt of the chuck spindle 312 .

As shown in FIG. 4 , the chuck spindle 312 is inserted into the support tube 341 of the support table 34 . The bearing 343 disposed inside the support tube 341 is in contact with the outer peripheral surface of the chuck spindle 312, and supports the chuck spindle 312 rotatably through the bearing 343.

The position adjustment units 35 are provided at two or more places with different positions in the circumferential direction of the support base 34 , and each position adjustment unit 35 is connected to the flange 342 . FIG. 5 shows an example of the arrangement of the position adjustment unit 35 and the fixed support part 36. In the structure of FIG. 5 , two position adjustment units 35 and one fixed support part 36 are arranged at intervals of 120 degrees (equal intervals) in the circumferential direction. The fixed support portion 36 supports the flange 342 at a fixed height position. The two position adjustment units 35 operate individually and can change the height position of the flange 342 .

As shown in FIG. 6 , each position adjustment unit 35 includes a cylindrical portion 351 fixed to the rotating table 30 , a movable shaft 352 penetrating the cylindrical portion 351 , a motor 353 connected to the lower end of the movable shaft 352 , and a clamping screw. Cap 354, which clamps flange 342 from above and below. The cylindrical portion 351 penetrates a hole formed in the Z-axis direction of the turntable 30 . A screw portion (not shown) formed on the upper end side of the movable shaft 352 penetrates the flange 342 and is screwed into the clamping nut 354 . The movable shaft 352 is rotationally driven by the motor 353, thereby causing the clamping nut 354 to change its position along the movable shaft 352, and causing the flange 342 clamped by the clamping nut 354 to change the height position in the Z-axis direction.

In addition, the tilt adjustment mechanism 33 is not limited to the above-mentioned structure. For example, instead of two, three or more position adjustment units 35 may be provided. Moreover, the movable shaft 352 may slide in the Z-axis direction without rotating, and the height of the flange 342 may be changed.

The chuck spindle 312 is rotated by the chuck rotating part 37 . The chuck rotating part 37 includes a motor 371 , a pulley 372 provided on the output shaft of the motor 371 , and a transmission belt 373 wound around the pulley 372 and the chuck spindle 312 . When the pulley 372 is rotationally driven by the motor 371 , the rotational force is transmitted to the chuck spindle 312 through the transmission belt 373 . Then, the chuck spindle 312 passing through the center (central axis 311 ) of the holding surface 321 rotates, so that the chuck table 31 rotates.

The grinding device 1 is provided with a control unit 80 that centrally controls various parts of the device (see FIGS. 1 and 9 ). The control unit 80 is composed of a processor, a memory, etc. that execute various processes. The control unit 80 follows the control program stored in the memory and controls the transportation of the wafer 90 between the various parts of the grinding device 1 , the rough grinding by the first grinding stone 51 , and the fine grinding by the second grinding stone 61 . Various operations include grinding, thickness measurement of the wafer 90 , and cleaning of the wafer 90 . The target finished thickness of the wafer 90 , the rough grinding amount of the wafer 90 , the fine grinding amount of the wafer 90 , and the preset thickness tendency of the wafer 90 are temporarily stored in the memory of the control unit 80 . Related information.

In addition, regarding the operation of each part of the grinding device 1 described below, the operation is controlled by the control signal sent from the control unit 80 when the subject of control is not specified.

In the grinding device 1 configured as above, during the grinding process of the wafer 90 , the inclination adjustment of the chuck table 31 is performed at the first grinding position and the second grinding position respectively. That is, the control unit 80 rotates the turntable 30 to position the chuck spindle 312 of the chuck table 31 at the first grinding position at a preset angle relative to the first spindle 52. The first tilt control unit 81 (see FIG. 9 ) of 80 controls the tilt adjustment mechanism 33 . In addition, the control unit 80 rotates the turntable 30 to position the chuck spindle 312 of the chuck table 31 at the second grinding position at a preset angle relative to the second spindle 62 . The second tilt control unit 82 (see FIG. 9 ) controls the tilt adjustment mechanism 33 . Each operation step in the grinding device 1 including such tilt adjustment of the chuck table 31 will be described.

[Keep step] The wafer 90 before grinding is taken out from the cassette 11 by the robot 12 and transported to the positioning mechanism 15 , and the positioning mechanism 15 is used to perform center alignment of the wafer 90 . Next, the wafer 90 is loaded into the chuck table 31 at the loading/unloading position by the loading mechanism 20 , and the wafer 90 is held on the holding surface 321 .

[Initial grinding steps] When the chuck table 31 holds the wafer 90 in the loading/unloading position, the control unit 80 rotates the turntable 30 to position the chuck table 31 at the first grinding position. Then, the control unit 80 executes an initial grinding step of grinding the upper surface of the wafer 90 using the first grindstone 51 of the first grinding mechanism 50 .

In the initial grinding step, the first grinding mechanism 50 is lowered by the first lifting mechanism, the first grindstone 51 is brought into contact with the upper surface of the wafer 90 , and the grinding wheel 54 is rotated by the first spindle 52 . Furthermore, in the chuck table 31 positioned at the first grinding position, the chuck spindle 312 is rotated by the chuck rotating part 37 . In this manner, while the first grindstone 51 and the wafer 90 on the chuck table 31 are rotated respectively, the upper surface of the wafer 90 is ground by the first grindstone 51 . If the predetermined grinding amount preset for initial grinding has been reached, that is, if the wafer 90 has been ground to the preset predetermined thickness, the rotation of the grinding wheel 54 and the chuck spindle 312 are stopped, and the grinding wheel 54 is stopped. The first grinding mechanism 50 is raised by the first lifting mechanism, so that the first grindstone 51 is separated from the wafer 90 on the chuck table 31, and the initial grinding step is completed.

[Thickness measurement procedure] After the initial grinding step is completed, the control unit 80 rotates the turntable 30 to position the chuck table 31 holding the wafer 90 that has completed the initial grinding at the second grinding position. Then, the control unit 80 performs a thickness measurement step of using the thickness measuring device 72 to measure the thickness of at least three places in the radial direction of the wafer 90 that has been ground in the initial grinding step.

[Thickness tendency calculation procedure] Next, the control unit 80 executes a thickness tendency calculation step for calculating the thickness tendency of the wafer 90 from at least three thickness values measured by the thickness measurement step (performing a shape calculation of the wafer 90 ).

For example, the thickness of the upper surface of the wafer 90 can be measured near the outer periphery, in the middle in the radial direction, and near the center of the wafer 90 where the thickness value has been measured by the three sensors 723, 724, and 725 of the thickness measuring device 72. The height position is coordinateized in the Z-axis direction, and a curved shape that smoothly connects these three points is expressed as the thickness tendency.

In addition, the thickness measuring device 72 may also be provided with four or more sensors, and in the thickness measurement step, the thickness may be measured at more than four locations in the radial direction of the wafer 90 . In this case, the thickness tendency can be expressed by an approximate curve based on the thickness values measured at four or more places through the thickness measurement step.

[Tilt adjustment procedure] Next, the control unit 80 compares the thickness tendency of the wafer 90 calculated through the thickness tendency calculation step with the thickness tendency preset and stored in the memory and obtains the difference. In the case where there is a difference in thickness tendency, the tilt adjustment amount is calculated in such a way that the thickness tendency of the wafer 90 calculated through the thickness tendency calculation step is consistent with the preset thickness tendency (by eliminating the difference), and in the first step The grinding position causes the tilt adjustment step to adjust the tilt of the chuck spindle 312 of each chuck table 31 relative to the first spindle 52 .

FIG. 7 shows an example of the thickness trend of the wafer 90 . (A) of FIG. 7 shows a predetermined thickness tendency of the wafer 90 , that is, a set thickness tendency Ta. The data related to the set thickness tendency Ta is included in the grinding process and stored in the memory of the control unit 80 . In FIG. 7(B) and FIG. 7(C) , solid lines indicate the thickness tendency of the wafer 90 calculated in the thickness tendency calculation step after the initial grinding, that is, the grinding thickness tendency Tb and Tc. S in FIG. 7 is a thickness measurement point where the thickness of the wafer 90 is measured by the thickness measurement gauge 70 and the thickness measurement gauge 71 during grinding.

In the initial grinding step, grinding is performed so that the thickness of the wafer 90 at the thickness measurement point S coincides with a preset thickness of the wafer 90 (set thickness). That is, grinding is performed so that the difference between the thickness after grinding and the set thickness becomes zero at the thickness measurement position S. Then, if data processing is performed to overlap the shapes of the set thickness tendency Ta and the grinding thickness tendencies Tb and Tc so that the height position of the upper surface of the wafer 90 coincides with the thickness measurement point S, then the set thickness tendency Ta and the shapes of the grinding thickness tendencies Tb and Tc can be distinguished. The grinding thickness tends to be the difference between Tb and Tc. In the grinding thickness tendencies Tb and Tc shown in FIGS. 7(B) and 7(C) , the thickness of the center portion in the radial direction of the wafer 90 is larger and the thickness of the outer peripheral portion of the wafer 90 is larger than the set thickness tendency Ta. The thickness tendency of the small mountain shape is found to be inconsistent with the set thickness tendency Ta.

More specifically, in the grinding thickness trend Tb in FIG. 7(B) , as the thickness goes toward the outer circumference from the thickness measurement point S, the post-grinding thickness becomes smaller than the set thickness, and at the outer peripheral portion of the wafer 90 , the grinding thickness becomes smaller than the set thickness. The difference between the rear thickness and the set thickness is Ma (the difference is negative). Furthermore, as it proceeds from the thickness measurement point S toward the inner circumferential side (center), the post-grinding thickness becomes larger than the set thickness, and at the center of the wafer 90 , the difference between the post-grinding thickness and the set thickness is Na (the difference is just).

The control unit 80 calculates the tilt adjustment amount for making the grinding thickness tendency Tb and the set thickness tendency Ta coincide with each other from the difference between the set thickness tendency Ta and the grinding thickness tendency Tb. Then, based on the calculated tilt adjustment amount, the motors 353 of each position adjustment unit 35 of the chuck table 31 supporting the first grinding position are operated, and the tilt adjustment mechanism 33 adjusts the angle of the chuck spindle 312 to the relative position. The first spindle 52 becomes a preset appropriate angle. Thereby, the thickness tendency of the wafer 90 ground by the first grindstone 51 of the first grinding mechanism 50 becomes consistent with the set thickness tendency Ta.

In the grinding thickness trend Tc in FIG. 7(C) , as the thickness is measured toward the outer circumference from the thickness measurement point S, the thickness after grinding becomes smaller than the set thickness, and at the outer peripheral portion of the wafer 90 , the thickness after grinding becomes smaller than the set thickness. The difference in thickness is Mb (the difference is negative). Furthermore, as it proceeds from the thickness measurement point S toward the inner circumferential side (center), the post-grinding thickness becomes larger than the set thickness. And at the center of the wafer 90 , the difference between the thickness after grinding and the set thickness is Nb (the difference is positive). In this way, although the overall thickness trend of the grinding thickness tendency Tc is similar to the grinding thickness tendency Tb in FIG. 7(B) , in the grinding thickness tendency Tc, the difference between the set thickness and the thickness after grinding becomes smaller on the outer peripheral side, and the set thickness trend Tc The difference between the thickness and the thickness after grinding becomes larger on the inner peripheral side (center side). That is, Ma>Mb, Na<Nb, and in the grinding thickness tendency Tc, the deviation from the set thickness is large especially on the center side of the wafer 90 .

Therefore, the tilt adjustment amount for making the grinding thickness tendency Tc coincide with the set thickness tendency Ta is different from the tilt adjustment amount for making the grinding thickness tendency Tb match the set thickness tendency Ta. The calculation of the inclination adjustment amount related to the grinding thickness tendency Tc and the inclination adjustment operation based on the calculated inclination adjustment amount are performed in the same manner as in the case of the above-mentioned grinding thickness tendency Tb, and therefore the description is omitted.

FIG. 8 shows different examples of thickness trends of the wafer 90 . (A) of FIG. 8 shows a predetermined thickness tendency Td of the wafer 90 that is set in advance. The data related to the set thickness tendency Td is included in the grinding process and stored in the memory of the control unit 80 .

In the initial thickness trend after grinding shown in FIG. 8(B) , that is, the grinding thickness tendency Te, as it proceeds from the thickness measurement point S (the position where the difference between the thickness after grinding and the set thickness is 0) toward the outer circumferential side, The thickness after grinding will become greater than the set thickness, and at the outer periphery of the wafer 90 , the difference between the thickness after grinding and the set thickness is Mc (the difference is positive). Furthermore, as one proceeds from the thickness measurement point S toward the inner circumferential side (center), the post-grinding thickness relative to the set thickness becomes smaller, and at the center of the wafer 90, the difference in the post-grinding thickness relative to the set thickness is Nc ( The difference is negative).

In the initial thickness trend after grinding shown in FIG. 8(C) , that is, the grinding thickness tendency Tf, as it proceeds from the thickness measurement point S (the position where the difference between the thickness after grinding and the set thickness is 0) toward the outer circumferential side, The thickness after grinding will become greater than the set thickness, and at the outer periphery of the wafer 90 , the difference between the thickness after grinding and the set thickness is Md (the difference is positive). Furthermore, as the thickness is measured from the thickness measurement point S toward the inner circumferential side (center), the post-grinding thickness becomes larger than the set thickness, and at the center of the wafer 90 , the difference Nd between the post-grinding thickness and the set thickness is (the difference is just). That is, in the grinding thickness tendency Tf, the entire post-grinding thickness becomes larger than the set thickness except for the thickness measurement point S.

The control unit 80 calculates the tilt adjustment amount for making the grinding thickness tendencies Te, Tf consistent with the set thickness tendency Td from the difference between the set thickness tendency Td and the grinding thickness tendencies Te, Tf. Then, based on the calculated tilt adjustment amount, the motors 353 of each position adjustment unit 35 of the chuck table 31 supporting the first grinding position are operated, and the tilt adjustment mechanism 33 adjusts the angle of the chuck spindle 312 to the relative position. The first spindle 52 becomes a preset appropriate angle. Thereby, the thickness tendency of the wafer 90 ground by the first grindstone 51 of the first grinding mechanism 50 becomes consistent with the set thickness tendency Td.

As described above, the tilt adjustment step is performed based on the thickness tendency of the wafer 90 (the grinding thickness tendencies Tb, Tc, Te, Tf) obtained in the thickness measurement step and the thickness tendency calculation step after the initial grinding step, whereby the tilt adjustment step is performed. The chuck spindle 312 of the chuck table 31 at the first grinding position is adjusted to a preset appropriate angle relative to the first spindle 52, and the thickness of the wafer 90 ground by the first grinding stone 51 of the first grinding mechanism 50 The tendency is consistent with the set thickness tendencies Ta and Td.

Therefore, each of the plurality of chuck tables 31 arranged on the turntable 30 adjusts the chuck spindle 312 to a preset appropriate angle with respect to the first spindle 52 in the first grinding position, and is therefore maintained at the first grinding position. The wafers 90 ground by the first grindstone 51 on each chuck table 31 have the same thickness tendency.

In addition, when there is no difference between the thickness tendency of the wafer 90 calculated in the thickness tendency calculation step and the thickness tendency preset and stored in the memory, the tilt adjustment amount in the tilt adjustment step becomes 0, and no tilt adjustment is performed. The tilt adjustment action performed by the mechanism 33.

[First grinding step] Next, the control unit 80 performs a first grinding step in which the wafer 90 held by the chuck table 31 adjusted in the tilt adjustment step is ground with the first grinding stone 51 of the first grinding mechanism 50 . In a first grinding step, wafer 90 is roughly ground. Like the above-described initial grinding step, in the first grinding step, the first grinding mechanism 50 is lowered by the first lifting mechanism, and the grinding wheel 54 is rotated by the first spindle 52 . Furthermore, the chuck spindle 312 is rotated by the chuck rotating part 37 . Then, the upper surface of the wafer 90 is ground with the first grindstone 51 . If it is confirmed that the wafer 90 has reached the thickness set for rough grinding through the measurement of the thickness measuring gauge 70, the rotation of the grinding wheel 54 and the chuck spindle 312 are stopped, and the first lifting mechanism is used to lift the first wafer 90. The grinding mechanism 50 rises, ending the first grinding step.

In addition, in the first grinding step, not only the unground wafer 90 transported from the cassette 11 is ground, but the wafer 90 ground in the initial grinding step can also be positioned at the first grinding position again, and repositioned in the first grinding position. A grinding step is performed by using the first grindstone 51 . Thereby, the wafer 90 ground in the initial grinding step can be used without waste. Furthermore, in this case, the finished thickness of the wafer 90 ground in the first grinding step is set to be smaller than the thickness of the wafer ground in the initial grinding step.

[Second Tilt Adjustment Step] Next, the control part 80 controls the tilt adjustment mechanism 33 in such a manner that the chuck spindle 312 of the chuck table 31 positioned at the second grinding position becomes a preset angle relative to the second spindle 62 by rotating the turntable 30, and Let the second tilt adjustment step be performed.

In the second tilt adjustment step, the tilt angle of the chuck spindle 312 of each chuck table 31 relative to the second spindle 62 is stored in the memory. For example, similarly to the case of the first grinding mechanism 50 , the wafer 90 positioned on the chuck table 31 at the second grinding position is initially ground by the second grinding stone 61 of the second grinding mechanism 60 . Next, the control unit 80 uses the thickness measuring device 72 to measure the thickness of the wafer 90 that has been initially ground by the second grinding mechanism 60 at at least three places in the radial direction, and calculates the thickness tendency of the wafer 90 . Then, the control unit 80 calculates the inclination angle of the chuck spindle 312 of each chuck table 31 relative to the second spindle 62 based on the difference between the calculated thickness tendency of the wafer 90 and the thickness tendency preset and stored in the memory. , and stored in the memory. The second tilt adjustment step is executed. The second tilt adjustment step is to adjust the tilt of the chuck spindle 312 to the tilt angle of each chuck spindle 312 stored in the memory.

By performing the second tilt adjustment step, any one of the plurality of chuck tables 31 arranged on the rotary table 30 is adjusted in the second grinding position so that the chuck spindle 312 becomes preset relative to the second spindle 62 At an appropriate angle, the wafers 90 held on each chuck table 31 and ground by the second grindstone 61 have the same thickness tendency.

[Second grinding step] Next, the control unit 80 causes the second grinding step to be performed. The second grinding step is to use the second grinding stone 61 of the second grinding mechanism 60 to grind the wafer 90 positioned on the chuck table 31 at the second grinding position. . In a second grinding step, wafer 90 is finely ground.

In the second grinding step, the second grinding mechanism 60 is lowered by the second lifting mechanism, and the grinding wheel 64 is rotated by the second spindle 62 . Furthermore, in the chuck table 31 positioned at the second grinding position, the chuck spindle 312 is rotated by the chuck rotating part 37 . In this manner, while the second grindstone 61 and the wafer 90 on the chuck table 31 are rotated respectively, the upper surface of the wafer 90 is ground by the second grindstone 61 . If it is confirmed that the wafer 90 has reached the finished thickness through the measurement of the thickness gauge 71, the rotation of the grinding wheel 64 and the chuck spindle 312 are stopped, and the second grinding mechanism 60 is raised by the second lifting mechanism. End the second grinding step.

[Cleaning steps, removal steps] Next, the control unit 80 rotates the turntable 30 to position the chuck table 31 holding the wafer 90 ground in the second grinding step at the loading and unloading position. Then, the wafer 90 is carried out from the chuck table 31 to the cleaning mechanism 18 by the carry-out mechanism 23 , and the polished wafer 90 is cleaned by the cleaning mechanism 18 . The cleaned wafer 90 is transported by the robot 12 and stored in the cassette 11 .

After each of the above steps, a series of operations on the wafer 90 in the grinding device 1 is completed.

FIG. 9 is a block diagram conceptually showing a part of the control system of the grinding device 1 including the control unit 80. The tilt adjustment of the chuck spindle 312 of each chuck table 31 at the first grinding position is controlled by the first tilt control unit 81 , which is a functional block of the control unit 80 . The tilt adjustment of the chuck spindle 312 of each chuck table 31 at the second grinding position is controlled by the second tilt control unit 82 , which is a functional block of the control unit 80 .

The process of measuring the thickness of the wafer 90 ground by the initial grinding step with the thickness measuring device 72 and calculating the thickness tendency of the wafer 90 is executed by the thickness tendency calculation unit 83 which is a functional block of the control unit 80 .

Furthermore, the process of obtaining the difference between the thickness tendency of the wafer 90 calculated by the thickness tendency calculation unit 83 and a predetermined thickness tendency (calculating the tilt adjustment amount) is a function included in the first tilt control unit 81 The block is executed by the calculation unit 84.

In addition, the first tilt control unit 81, the second tilt control unit 82, the thickness tendency calculation unit 83, and the calculation unit 84 in the control unit 80 are conceptual functional blocks, and it does not mean that these units exist individually. The functions of each unit in the control unit 80 are realized by the operations of the processor, memory, etc. constituting the control unit 80 .

As described above, in the grinding device 1 of the present embodiment, the chuck spindle 312 of the chuck table 31 positioned at the first grinding position is tilt-adjusted so as to be preset relative to the first spindle 52 of the first grinding mechanism 50 angle. Thereby, the wafer 90 of each chuck table 31 ground by the first grindstone 51 of the first grinding mechanism 50 has a uniform thickness tendency, and will be ground by the second grindstone 61 of the second grinding mechanism 60 . The amount of grinding of the wafers 90 on each chuck table 31 is made uniform, and there is no difference in the grinding time.

Furthermore, during tilt adjustment of the chuck spindle 312 , the thickness tendency of the wafer 90 is calculated from three or more thickness values in the radial direction (shape calculation is performed), and the difference with the preset thickness tendency is compared. By using data obtained by performing shape calculation on the thickness tendency of the entire wafer 90 , compared to the case where only data of thickness values obtained by point measurement at specific positions in the radial direction of the wafer 90 are used, it is possible to perform More precise tilt adjustment.

A thickness gauge other than thickness gauge 72 shown in Figure 2 may also be used. The thickness measuring instrument 73 according to the modified example shown in FIG. 10 is configured such that a bracket 731 erected on the outer peripheral side of the turntable 30 can rotate about an axis in the Z-axis direction. A sensor 733 is installed on the support arm 732 extending upward from the bracket 731 toward the chuck table 31 . The sensor 733 is a non-contact sensor that irradiates laser light from above the wafer 90 and measures the thickness of the wafer 90 .

The support arm 732 is rotated by the measuring instrument rotating unit 74 . The measuring instrument rotating part 74 is equipped with a motor 741, a pulley 742 provided on the output shaft of the motor 741, and a transmission belt 743 wound around the pulley 742 and the bracket 731. When the pulley 742 is rotationally driven by the motor 741 , the rotational force is transmitted to the bracket 731 through the transmission belt 743 . In this way, the support arm 732 rotates around the bracket 731 .

When the support arm 732 rotates, the position of the sensor 733 in the radial direction of the chuck table 31 changes. Thereby, the thickness can be measured at multiple places in the radial direction of the wafer 90 . In particular, since the thickness measuring device 73 can freely select the thickness measurement position in the radial direction of the wafer 90 in accordance with the rotation position of the support arm 732 without relying on the number of sensors, it can be used at multiple places in the radial direction. The thickness value used to calculate the thickness tendency can improve the calculation accuracy of the thickness tendency.

In the thickness gauge 73, the support arm 732 is rotated. As a further modification, a thickness gauge of a type in which the support arm 732 slides in the radial direction of the chuck table 31 can be used.

The thickness measuring device used to calculate the thickness tendency of the wafer 90 may be disposed in a position different from the thickness measuring device 72 of the grinding device 1 in FIG. 1 . For example, the thickness measuring device may be installed on the chuck table 31 at a position capable of measuring the loading and unloading position on the turntable 30 (a position where transport by the loading mechanism 20 and the carrying out mechanism 23 is possible). The position of the thickness of the wafer 90. Alternatively, the thickness measuring device may be disposed at a position capable of measuring the thickness of the wafer 90 on the chuck table 31 at the first grinding position (a position capable of grinding by the first grinding mechanism 50 ).

In addition, the thickness tendency of the wafer 90 may also be calculated using a thickness measuring instrument that is not arranged in the grinding device 1 . That is, an external thickness measuring instrument is used to measure the thickness of the initially ground wafer, and the measured thickness value is input into the thickness value input part of the grinding device 1, whereby the thickness tendency calculation part can calculate the thickness of the wafer. tendency. Furthermore, the thickness tendency of the wafer may be calculated outside the grinding device 1 , and the grinding device 1 may be provided with a thickness tendency input unit for inputting the thickness tendency.

In addition, the embodiments of the present invention are not limited to the above-described embodiments and modifications, and various changes, substitutions, and modifications can be made without departing from the gist of the technical idea of the present invention. Furthermore, as long as other methods can be used to realize the technical idea of the present invention through technological advancement or other derived technologies, the methods can also be used and implemented. Therefore, the scope of the patent application covers all implementation aspects that can be included within the scope of the technical idea of the present invention.

[Industrial Applicability] As described above, the grinding device and the wafer grinding method of the present invention make the shape of the wafers ground by the first grinding stone in a plurality of chuck tables uniform (make the wafers have the same thickness tendency), thereby having the following advantages: The second grinding stone has the effect of uniformizing the grinding time and grinding amount, and is useful for grinding devices and grinding methods that perform grinding in various stages such as grinding of wafers before forming components and grinding of wafers with components on them. .

1:Grinding device 15: Positioning mechanism 18: Cleaning mechanism 20:Moving into the institution 23: Move out of the institution 30: Rotary table 31:Chuck table 33:Tilt adjustment mechanism 35: Position adjustment unit 36: Fixed support part 37:Chuck rotation part 50:The first grinding mechanism 51:The first millstone 52:First spindle 60:Second grinding mechanism 61:Second grindstone 62: Second spindle 70: Thickness measuring gauge 71: Thickness measuring gauge 72:Thickness measuring instrument 73:Thickness measuring instrument 74: Measuring instrument rotating part 80:Control Department 81:First tilt control part 82: Second tilt control part 83: Thickness tendency calculation department 84:Computing Department 90:wafer 312:Chuck spindle 321:Keep the surface 723: Sensor 724: Sensor 725: Sensor 733: Sensor 741: Motor S: Thickness measurement place Ta: Set thickness tendency Tb: grinding thickness tendency Tc: grinding thickness tendency Td: Set thickness tendency Te: grinding thickness tendency Tf: grinding thickness tendency

Figure 1 is a perspective view of the grinding device. Figure 2 is a cross-sectional view showing the chuck table, thickness measuring device, and second grinding mechanism. Figure 3 is a side view showing the chuck table and tilt adjustment mechanism. FIG. 4 is a cross-sectional view showing a part of the chuck table and the tilt adjustment mechanism. FIG. 5 is a plan view showing an arrangement example of the tilt adjustment mechanism. FIG. 6 is a perspective view showing the chuck table, tilt adjustment mechanism, and chuck rotating part. FIG. 7 is a diagram illustrating an example of a preset thickness trend of a wafer and a thickness trend of a ground wafer. FIG. 8 is a diagram illustrating an example of difference between a preset thickness tendency of a wafer and a thickness tendency of a ground wafer. Fig. 9 is a block diagram showing the control system of the grinding device. Fig. 10 is a cross-sectional view showing a modified example of the thickness measuring device.

1:Grinding device

10:Abutment

11: Cassette

12:Manipulator

13: Robotic arm

14:Hands

15: Positioning mechanism

16: Temporary stand

17: Positioning pin

18: Cleaning mechanism

20:Moving into the institution

21:Support arm

22:Retention pad

23: Move out of the institution

24:Support arm

25:Maintenance pad

30: Rotary table

31:Chuck table

50:The first grinding mechanism

51:The first millstone

52:First spindle

53:Installation parts

54:Grinding wheel

55: Guide rail

56: Ball screw

57: Lifting platform

58: Shell

59: Motor

60:Second grinding mechanism

61:Second grindstone

62: Second spindle

63: Installation parts

64:Grinding wheel

65: Guide rail

66: Ball screw

67: Lifting platform

68: Shell

69: Motor

70: Thickness measuring gauge

71: Thickness measuring gauge

72:Thickness measuring instrument

80:Control Department

90:wafer

101:Cylinder

102:Cylinder

701: Reference height gauge

702: Wafer height gauge

711: Reference height gauge

712: Wafer height gauge

721: Bracket

722:Support arm

Claims (4)

A grinding device having: A chuck table, which holds the wafer with a conical holding surface; A chuck rotating part that rotates the chuck table with the chuck spindle passing through the center of the holding surface; a tilt adjustment mechanism that changes the tilt of the chuck spindle; a first grinding mechanism that rotates a first spindle equipped with an annular first grindstone and uses the first grindstone to grind the wafer held on the holding surface; a second grinding mechanism that rotates a second spindle equipped with an annular second grindstone and uses the second grindstone to grind the wafer held on the holding surface; a rotary table configured with a plurality of the chuck tables; and a control part that rotates the rotary table and positions the chuck table at a first grinding position where the first grinding stone grinds and a second grinding position where the second grinding stone grinds, Among them, the grinding device has: The first tilt control unit rotates the turntable through the control unit so that the chuck spindle of the chuck table positioned at the first grinding position becomes a preset angle relative to the first spindle. , control the tilt adjustment mechanism; and The second tilt control unit rotates the turntable through the control unit so that the chuck spindle of the chuck table positioned at the second grinding position becomes a preset angle relative to the second spindle. , to control the tilt adjustment mechanism. Such as the grinding device of claim 1, which has: a thickness measuring device that measures the thickness of the wafer ground by the first grinding stone; and a thickness tendency calculation unit that measures the thickness at at least three places with the thickness measuring device in the radius portion of the wafer ground by the first grinding stone, and calculates the thickness tendency of the wafer, The first tilt control unit has a calculation unit that calculates a difference between the thickness tendency calculated by the thickness tendency calculation unit and a predetermined thickness tendency set in advance, and then uses the difference to grind the wafer with the first grindstone. The tilt adjustment mechanism is controlled to achieve a predetermined thickness tendency. A wafer grinding method that rotates a rotating table equipped with a plurality of chuck tables holding wafers, and after grinding the wafer held on the chuck table with a first grinding stone, grinding it with a second grinding stone To a predetermined thickness, the wafer grinding method consists of the following steps: a holding step that causes the chuck table to hold the wafer; An initial grinding step, which after the holding step, uses the first grinding stone to grind the wafer; A thickness measurement step, which measures the thickness at at least three places in the radial direction of the wafer ground by the initial grinding step; a thickness tendency calculation step that calculates the thickness tendency of the wafer from at least three thickness values measured by the thickness measurement step; A tilt adjustment step, which adjusts the tilt of the chuck spindle of each chuck table relative to the first spindle in such a way that the thickness trend calculated by the thickness trend calculation step is consistent with the preset thickness trend; A first grinding step, which uses the first grinding stone to grind the wafer held by the chuck table adjusted by the tilt adjustment step; and The second grinding step is to rotate the rotary table and use the second grinding stone to grind the wafer ground in the first grinding step. For example, the grinding method of claim item 3, wherein: The wafer ground in the initial grinding step is ground in the first grinding step.