JP2024011097A - Method of manufacturing wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a wafer by grinding both surfaces of the wafer, in which a grinding quantity of one side surface is set to be equal to a grinding quantity of the other side surface.

SOLUTION: A method of manufacturing a wafer comprises: a thickness measuring step of measuring a thickness of a wafer (W) before grinding with a measuring device (30); a calculation step of subtracting a preset finish-thickness (Ta) from a wafer-thickness (Tb) before grinding; a holding step of causing a holding surface (131) of a chuck table (10) to hold one side surface (Wa) of the wafer; a first grinding step of grinding another side surface (Wb) of the wafer held by the holding surface by a quantity (Tc) of a half of a difference calculated at the calculation step; a reversing step of separating the wafer from the holding surface and causing the holding surface to hold the other side surface of the wafer after reversion; and a second grinding step of grinding one side surface of the wafer held by the holding surface by a half quantity (Td) of the difference calculated at the calculation step.

SELECTED DRAWING: Figure 2

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a method for manufacturing a wafer.

In manufacturing wafers used for semiconductor devices and the like, a columnar ingot is sliced into plate shapes using a cutting device such as a wire saw to form as-sliced wafers. As disclosed in Patent Document 1, one surface and the other surface of an as-sliced wafer are ground to produce a wafer of a predetermined thickness. After grinding both sides of the as-sliced wafer, the outer peripheral edge is chamfered into a predetermined shape.

Japanese Patent Application Publication No. 2009-272557

On both surfaces of an as-sliced wafer, a plurality of linear cutting marks are formed during slicing, and undulations and warpage occur. In the process of grinding an as-sliced wafer, the wafer is finished to a predetermined thickness while removing such cutting marks, undulations, warpage, etc.

Conventionally, when grinding both sides of an as-sliced wafer, one side was ground to remove any undulations, and then the other side was ground to a predetermined thickness. It was not even considered that it would be possible to do so. However, if the amount of grinding on both sides is different, there is a risk that the outer circumferential portion of the wafer after grinding will have a warped shape. If the outer peripheral portion of the wafer is warped, there is a problem in that it is difficult to transport and hold the wafer.

The present invention has been made in view of the above, and is a wafer manufacturing method in which a wafer is manufactured by grinding both sides of the wafer, and the amount of grinding on one side is made equal to the amount of grinding on the other side. The purpose is to

One aspect of the present invention is a wafer manufacturing method of manufacturing a wafer of a predetermined thickness by grinding both sides of the wafer, the method comprising: a thickness measuring step of measuring the thickness of the wafer before grinding with a thickness measuring device; A calculation step of subtracting a preset finishing thickness from the pre-grind wafer thickness measured in the measurement step, a holding step of holding one side of the wafer on the holding surface of the chuck table, and the other side of the wafer held on the holding surface. a first grinding step in which the surface of the wafer is ground by half of the difference calculated in the calculation step; and a reversal in which the wafer is separated from the holding surface and, after inversion, the other surface of the wafer is held on the holding surface. and a second grinding step of grinding one side of the wafer held on the holding surface by half the difference calculated in the calculation step.

Before the first grinding step, a summation step of calculating a total value of a half value of the wafer thickness measured in the thickness measuring step and a preset half value of the finished thickness, In the first grinding step, the top surface height of the wafer is measured with a top surface height measuring device and the wafer is ground until the distance from the holding surface to the other surface of the wafer matches the total value calculated in the summing step. good.

When a protective member including a resin layer that covers the entire surface of one side of the wafer is provided, a protective member thickness measuring step of measuring the thickness of the protective member before the first grinding step; a first grinding end height position calculation step of adding up the total value; and a peeling step of peeling off the protective member after the first grinding step and before the second grinding step. In the holding step, the wafer is held via the protective member, and in the first grinding step, the top surface height of the wafer held in the holding step is measured with a top surface height measuring device, and the wafer is removed from the holding surface. It is preferable to grind until the distance to the other surface of the wafer matches the value calculated in the first grinding end height position calculation step.

According to the wafer manufacturing method of the present invention, when grinding both sides of a wafer, it is possible to manufacture a wafer with high shape accuracy by making the amount of grinding on one side the same as the amount of grinding on the other side. can.

It is a figure showing a carrying-in process to a holding process of a manufacturing method of the wafer of a first form. It is a figure showing the first grinding process of the manufacturing method of the wafer of the first form. It is a figure which shows the reversal process of the manufacturing method of the wafer of a 1st form. It is a figure showing the second grinding process of the manufacturing method of the wafer of the first form. FIG. 3 is a diagram illustrating an unloading process of the wafer manufacturing method of the first embodiment. It is a figure which shows the carrying-in process to the holding process of the manufacturing method of the wafer of a second form. It is a figure which shows the first grinding process of the manufacturing method of the wafer of a second form. It is a figure which shows the reversal process and the peeling process of the manufacturing method of the wafer of a second form. It is a figure which shows the second grinding process of the manufacturing method of the wafer of a second form.

The wafer manufacturing method of this embodiment will be described below with reference to the accompanying drawings. 1 to 5 show a wafer manufacturing method according to the first embodiment, and FIGS. 6 to 9 show a wafer manufacturing method according to the second embodiment. First, a wafer manufacturing method according to the first embodiment will be described.

The wafer W is an as-sliced wafer before device formation, and is formed by slicing a cylindrical ingot with a wire saw. In the following description, both surfaces of the wafer W are referred to as one surface Wa and the other surface Wb.

Note that the upper surface of the wafer W means the surface facing upward when the wafer W is held on a chuck table 10, which will be described later. The lower surface of the wafer W means the surface facing downward when the wafer W is held on the chuck table 10. Depending on the vertical orientation of the wafer W, there are two states: one surface Wa is the bottom surface and the other surface Wb is the top surface (FIGS. 1 and 2), and the other surface Wb is the bottom surface and one surface Wa is the top surface (FIGS. 1 and 2). Figure 4).

The material of the wafer W is not limited, and may be a semiconductor substrate such as silicon or gallium arsenide, or an inorganic material substrate such as ceramic, glass, or sapphire.

The wafer manufacturing method of this embodiment is carried out using a grinding apparatus 1 that grinds one surface Wa and the other surface Wb of a wafer W. The grinding device 1 grinds the wafer W held by the chuck table 10 using the grindstone 24 of the grinding mechanism 20 (see FIGS. 2 and 4).

The chuck table 10 includes a frame 11 and a porous member 13 attached inside a recess 12 provided at the top of the frame 11. The upper surface of the porous member 13 is a holding surface 131 that holds the wafer W. The upper surface 111 of the frame 11 around the recess 12 is continuous with the holding surface 131. The porous member 13 communicates with a suction source 15 via a suction path 14, and when the suction source 15 is activated, a suction force acts on the holding surface 131.

The chuck table 10 is rotatably supported around a central axis passing through the center of the holding surface 131. The chuck table 10 is rotationally driven by a rotational drive mechanism 16.

The grinding device 1 includes a transport mechanism 17 (FIGS. 1 and 5). The transport mechanism 17 transports the wafer W, and transports the wafer W before being ground to the chuck table 10 and holds it there, and transports the wafer W after the grinding from the chuck table 10 . Further, it is provided with an inversion mechanism 18 (FIG. 3) that inverts the wafer W placed on the chuck table 10 upside down.

The unground wafer W carried into the grinding apparatus 1 by the transport mechanism 17 is placed on the holding surface 131. When the suction source 15 is activated to apply suction force to the holding surface 131, the wafer W is suctioned and held on the chuck table 10.

The grinding mechanism 20 (FIGS. 2 and 4) includes a disk-shaped mount 22 at the lower end of a spindle 21 extending in the vertical direction, and a grinding wheel 23 is attached to the lower part of the mount 22. A grindstone 24 is arranged in an annular manner on the lower surface of the grinding wheel 23 . The spindle 21 is rotatably supported by a spindle housing (not shown) about an axis extending in the vertical direction. The spindle 21 is rotationally driven by a spindle motor (not shown), and when the spindle 21 rotates, the mount 22 and the grinding wheel 23 rotate together with the spindle 21.

The grinding mechanism 20 is moved in the vertical direction by a grinding feed mechanism 25. The grinding feed mechanism 25 includes a guide rail (not shown) that extends in the vertical direction, a ball screw (not shown), and a motor (not shown) that rotationally drives the ball screw. A holder (not shown) holding the grinding mechanism 20 is supported so as to be movable along the guide rail of the grinding feed mechanism 25, and is screwed into a ball screw of the grinding feed mechanism 25. When the motor of the grinding feed mechanism 25 is activated and the ball screw rotates, the grinding mechanism 20 moves in the vertical direction.

The grinding device 1 includes a thickness measuring device 30. The thickness measuring device 30 measures the thickness of the wafer W held on the chuck table 10. The thickness measuring device 30 includes a holding surface height measuring device 31 and a top surface height measuring device 32.

The holding surface height measuring device 31 is a contact type height gauge, and a probe (contactor) is brought into contact with the upper surface 111 of the frame 11, and the height position of the upper surface 111 is detected from the height of the contact position. Since the upper surface 111 is a continuous surface with the holding surface 131, the height position of the holding surface 131 can be detected by the holding surface height measuring device 31.

The top surface height measuring device 32 is a contact type height gauge, which brings a probe (contactor) into contact with the top surface of the wafer W, and detects the height position of the top surface of the wafer W from the height of the contact position. Then, the thickness of the wafer W is measured based on the difference between the measured value of the holding surface height measuring device 31 and the measured value of the upper surface height measuring device 32.

Each part of the grinding device 1 is controlled by a control section 40. The control unit 40 includes a processor that executes various processes, a memory that records programs and temporary data, and the like. The control unit 40 controls the transport of the wafer W by the transport mechanism 17, the grinding by the grinding mechanism 20, the reversal of the wafer W by the reversing mechanism 18, etc., according to the control program stored in the memory. The memory of the control unit 40 temporarily stores processing-related data such as the target finishing thickness Ta of the wafer W (see FIG. 5).

A method of manufacturing a wafer using the above grinding apparatus 1 will be explained. The operations of the following sections are controlled by the control section 40, and unless the main body of control is specified, it is assumed that the operations are controlled by the control section 40.

The wafer W to be ground in the wafer manufacturing method according to the first embodiment shown in FIGS. 1 to 5 is an as-sliced wafer from which undulations have been removed by lapping. No protective member is provided to cover the surface Wb. Furthermore, a chamfered portion Wc is formed on the outer periphery of the wafer W.

[Delivery process]
First, a loading process (Figure 1) is performed. In the carrying-in process, the wafer W before being ground is carried to the chuck table 10 by the carrying mechanism 17, and is placed on the holding surface 131 with one surface Wa facing downward. The value of the finished thickness Ta (FIG. 5) of the wafer W to be carried in is set in advance and stored in the memory of the control unit 40.

[Thickness measurement process]
Next, a thickness measurement step (FIG. 1) is performed. In the thickness measuring step, the thickness of the wafer W before grinding is measured by the thickness measuring device 30. Specifically, the probe of the holding surface height measuring device 31 is brought into contact with the top surface 111 of the frame 11 to detect the height positions of the top surface 111 and the holding surface 131, and the probe of the top surface height measuring device 32 is brought into contact with the top surface 111 of the frame 11. to detect the height position of the other surface Wb. The control unit 40 measures the pre-grind wafer thickness Tb, which is the thickness of the wafer W before grinding, based on the difference between the measured value of the holding surface height measuring device 31 and the measured value of the top surface height measuring device 32. The measured wafer thickness Tb before grinding is stored in the memory of the control unit 40.

[Calculation process]
Next, a calculation step (FIG. 1) is performed. In the calculation step, the thickness calculation section 41 of the control section 40 subtracts a preset finishing thickness Ta from the pre-grinding wafer thickness Tb measured in the thickness measurement step. The difference obtained by subtracting the finished thickness Ta from the wafer thickness Tb before grinding is defined as the thickness difference.

[Holding process]
Next, a holding step (FIG. 1) is performed. In the holding process, the suction source 15 is operated to apply suction force to the holding surface 131 of the chuck table 10, thereby causing the holding surface 131 to suction and hold the wafer W.

[First grinding process]
Next, a first grinding step (FIG. 2) is performed. In the first grinding step, the other surface Wb of the wafer W is ground by a first grinding amount Tc, which is half the thickness difference calculated in the calculation step. Specifically, the grinding mechanism 20 is lowered by the grinding feed mechanism 25 to bring the grindstone 24 into contact with the other surface Wb of the wafer W, and the grinding wheel 23 is rotated by the spindle 21 . Further, the chuck table 10 is rotated by the rotation drive mechanism 16. In this way, the other surface Wb of the wafer W is ground by rotating the wafer W on the chuck table 10 and the grinding wheel 23 while feeding the grindstone 24 for grinding.

Grinding of the first grinding amount Tc (half the thickness difference) in the first grinding step can be performed as follows. Before the first grinding step, a summation step is performed to calculate the sum Ka of half the pre-grind wafer thickness Tb of the wafer W measured in the thickness measurement step and half the preset finishing thickness Ta. conduct. The calculation in the summing process is performed by the summing unit 42 of the control unit 40.

While measuring the top surface height of the wafer W (in the case of the first grinding process, the height of the other surface Wb) using the top surface height measuring device 32, the wafer is removed from the holding surface 131 measured by the thickness measuring device 30. The other surface Wb is ground by the grindstone 24 until the distance to the other surface Wb of W matches the total value Ka calculated in the above-mentioned summing process.

At the stage when the distance from the holding surface 131 to the other surface Wb of the wafer W matches the total value Ka, the determination unit 43 of the control unit 40 determines that the first grinding amount Tc, which is the grinding amount in the first grinding process, has been reached. I judge that. As a result, the other surface Wb is ground by the first grinding amount Tc, that is, the grinding amount is half of the thickness difference calculated in the calculation step.

When the determination section 43 of the control section 40 determines that the amount of grinding in the first grinding step (first amount of grinding Tc) has been reached, the first grinding step is ended. In the end processing of the first grinding process, the rotation of the chuck table 10 and the grinding wheel 23 is stopped, and the downward grinding feed of the grinding mechanism 20 by the grinding feed mechanism 25 is stopped. Then, the grinding mechanism 20 is raised by the grinding feed mechanism 25 to separate the grindstone 24 from the other surface Wb of the wafer W. Further, the operation of the suction source 15 is stopped, and the suction holding of the wafer W by the chuck table 10 is released.

[Reversal process]
After the first grinding process is completed, an inversion process (FIG. 3) is performed. In the reversing process, as shown in FIG. 3A, the wafer W is separated from the holding surface 131 by the reversing mechanism 18. Subsequently, as shown in FIG. 3B, after the orientation of the wafer W is reversed vertically by the reversing mechanism 18, the other surface Wb after grinding is placed on the holding surface 131. Then, the suction source 15 is activated to apply suction force to the holding surface 131, thereby causing the holding surface 131 to suction and hold the wafer W. Thereby, the wafer W is held with one unground surface Wa facing upward.

[Second grinding process]
Next, a second grinding step (FIG. 4) is performed. In the second grinding step, one surface Wa of the wafer W is ground by a second grinding amount Td, which is half the thickness difference calculated in the calculation step. Specifically, the grinding mechanism 20 is lowered by the grinding feed mechanism 25, the grinding wheel 24 is brought into contact with one surface Wa of the wafer W, and the grinding wheel 23 is rotated by the spindle 21. Further, the chuck table 10 is rotated by the rotation drive mechanism 16. In this way, one surface Wa of the wafer W is ground by rotating the wafer W on the chuck table 10 and the grinding wheel 23, respectively, and feeding the grindstone 24 for grinding.

While measuring the top surface height of the wafer W (in the case of the second grinding process, the height of one surface Wa) using the top surface height measuring device 32, the height of the wafer W is measured from the holding surface 131 measured by the thickness measuring device 30. One surface Wa is ground by the grindstone 24 until the distance to the one surface Wa (the thickness of the wafer W) becomes the finished thickness Ta. Then, when the thickness of the wafer W measured by the thickness measuring device 30 reaches the finished thickness Ta, the determination unit 43 of the control unit 40 determines that the amount of grinding in the second grinding process has been reached, and the second grinding process is performed. Finish the process. As a result, one surface Wa is ground by the second grinding amount Td, that is, grinding is performed by half the thickness difference calculated in the calculation step.

In the end processing of the second grinding process, the rotation of the chuck table 10 and the grinding wheel 23 is stopped, and the downward grinding feed of the grinding mechanism 20 by the grinding feed mechanism 25 is stopped. Then, the grinding mechanism 20 is raised by the grinding feed mechanism 25 to separate the grindstone 24 from one surface Wa of the wafer W. Further, the operation of the suction source 15 is stopped, and the suction holding of the wafer W by the chuck table 10 is released.

[Export process]
After the second grinding process is completed, the unloading process (FIG. 5) is performed. In the carrying-out process, the wafer W, which has been ground on both surfaces Wa and Wb, is lifted from the chuck table 10 by the transport mechanism 17 and carried out. As shown in FIG. 5, the wafer W after both surfaces have been ground has a preset target finishing thickness Ta.

As described above, the first embodiment of the wafer manufacturing method is carried out. According to this manufacturing method, the first grinding amount Tc of the other surface Wb in the first grinding step and the second grinding amount Td of the one surface Wa in the second grinding step can be made the same amount. can.

As an example, the preset finishing thickness Ta is 800 μm, and the pre-grinding wafer thickness Tb of the wafer W measured in the thickness measurement step is 1.0 mm. The total value Ka calculated in the summing process is 900 μm, which is the sum of 500 μm, which is half of 1.0 mm (wafer thickness Tb before grinding), and 400 μm, which is half of 800 μm (finished thickness Ta). Become. In the first grinding step, when grinding is performed until the distance from the holding surface 131 to the other surface Wb of the wafer W becomes 900 μm (total value Ka), the amount of grinding with respect to the other surface Wb (first grinding amount Tc) becomes 100 μm. In the second grinding step, when grinding is performed until the distance from the holding surface 131 to one surface Wa of the wafer W becomes 800 μm, which is the finished thickness Ta, the amount of grinding for one surface Wa (second grinding amount Td) becomes 100 μm. Therefore, the amount of grinding on one surface Wa of the wafer W and the amount of grinding on the other surface Wb are the same.

In this manufacturing method, the numerical values referenced in each step are based on the finished thickness Ta included in processing-related data (grinding recipe) input in advance and the wafer thickness Tb before grinding measured by the thickness measuring device 30, It is possible to obtain the necessary numerical information without requiring any other special equipment or complicated control. Therefore, the amount of grinding on one surface Wa of the wafer W and the amount of grinding on the other surface Wb of the wafer W can be made the same amount easily and efficiently without requiring high costs.

When the amount of grinding on one surface Wa of the wafer W is the same as the amount of grinding on the other surface Wb, the shape accuracy of the wafer W can be increased when grinding is performed. For example, if there is a variation in the amount of grinding on one surface Wa and the amount of grinding on the other surface Wb, warping is likely to occur in the outer peripheral portion of the wafer W. On the other hand, if the amount of grinding on one side Wa and the amount of grinding on the other side Wb are the same, the stress applied during grinding on both sides is equalized, so the outer circumference of the wafer W after grinding is Warpage is less likely to occur. Since a wafer W without warpage is easy to transport, hold, and undergo various processing after grinding, it is very useful to equalize the amount of grinding on both sides of the wafer W.

Further, if the amount of grinding on one surface Wa of the wafer W is the same as the amount of grinding on the other surface Wb, the shape of the chamfered portion Wc on the outer periphery of the wafer W can also be made vertically uniform without deviation.

Next, a wafer manufacturing method according to the second embodiment will be described with reference to FIGS. 6 to 9. Note that the unloading process after grinding both sides of the wafer W is the same as that of the first embodiment shown in FIG. 5, and is therefore not shown. Further, the same components as those of the grinding device 1 described in the first embodiment are indicated by the same reference numerals, and the description thereof will be omitted.

The wafer W that is the object of grinding in the second embodiment is an as-sliced wafer that includes a protection member 50 that covers the entire surface of one surface Wa. The protective member 50 includes a resin layer 51 and a sheet 52. The resin layer 51 is formed, for example, by curing an ultraviolet curing liquid resin.

The protection member 50 is formed using a protection member forming device (not shown) before being carried into the grinding device 1 . In the protective member forming apparatus, a sheet 52 is placed on a protective member forming stage, and liquid resin is supplied onto the sheet 52. Subsequently, one surface Wa of the wafer W is pressed against the liquid resin from above the protective member forming stage, and the liquid resin is spread between the wafer W and the sheet 52. In this state, the liquid resin is irradiated with ultraviolet light from below to be cured. Then, the protective member 50 is formed by the cured resin layer 51 and the sheet 52. Note that the method for forming the protective member 50 is not limited to this.

As shown in FIG. 6, the grinding device 1 includes a non-contact thickness measuring device 35 in addition to the thickness measuring device 30. As shown in FIG. The non-contact thickness measuring device 35 is of a type that uses measurement light, and uses the upper surface reflected light obtained by reflecting the measurement light L (laser light, infrared SLD) on the upper surface of the wafer W (the other surface Wb), and the lower surface of the wafer W. The thickness of the wafer W ( The thickness of the wafer W excluding the protective member 50 is measured.

Further, the non-contact thickness measuring device 35 may be of an ultrasonic type. Ultrasonic waves are emitted from above the wafer W, and the ultrasonic vibrations reflected from the top surface of the wafer W (the other surface Wb) and the ultrasonic vibrations reflected from the bottom surface of the wafer W (one surface Wa) are received. , the thickness of the wafer W is measured based on the propagation time of the ultrasonic wave through the wafer W. Alternatively, as disclosed in Japanese Unexamined Patent Publication No. 2022-000615, the thickness of the wafer W is measured from the propagation time and number of times by receiving reflected waves reflected multiple times on the lower surface (one surface Wa) of the wafer W. You may also do so.

[Delivery process]
First, a loading process (FIG. 6) is performed. In the carrying-in process, the wafer W before being ground is carried to the chuck table 10 by the carrying mechanism 17, and is placed on the holding surface 131 with the protection member 50 facing downward. This embodiment differs from the first embodiment in that the sheet 52 of the protection member 50 is placed on the holding surface 131.

[Thickness measurement process]
Next, a thickness measurement step (FIG. 6) is performed. In the thickness measuring step, the thickness of the wafer W before grinding is measured by the thickness measuring device 30. What is measured in this thickness measurement step is the thickness of the entire wafer W including the protection member 50. The measured wafer thickness Tb before grinding is stored in the memory of the control unit 40.

[Total process]
Next, a summing process is performed. In the summing step, a sum Ka of half the pre-grind wafer thickness Tb of the wafer W measured in the thickness measuring step and half the preset finished thickness Ta (see FIG. 5) is calculated. The summing process is performed by the summing unit 42 of the control unit 40.

[Protective member thickness measurement process]
Next, a protective member thickness measuring step (FIG. 6) is performed. In the protective member thickness measuring step, the thickness of the protective member 50 is measured. Specifically, the non-contact thickness measuring device 35 detects the actual wafer thickness Te, which is the thickness of the wafer W from the other surface Wb to the one surface Wa. Then, the thickness calculation unit 41 of the control unit 40 calculates the protection member thickness Tf, which is the thickness of the protection member 50, by subtracting the actual wafer thickness Te from the pre-grinding wafer thickness Tb measured in the previous thickness measurement step. .

[First grinding end height position calculation process]
Next, a first grinding end height position calculation step (FIG. 6) is performed. In the first grinding end height position calculation step, the protection member thickness Tf and the total value Ka are added together to calculate the second total value Kb. The second summation unit 44 of the control unit 40 calculates the second summation value Kb in the first grinding end height position calculation step.

[Holding process]
Next, a holding step (FIG. 6) is performed. In the holding step, the suction source 15 is activated to apply suction force to the holding surface 131 to suction and hold the wafer W on the holding surface 131 via the protection member 50 .

[First grinding process]
Next, a first grinding step (FIG. 7) is performed. In the first grinding process, the top surface height of the wafer W held in the holding process (in the case of the first grinding process, the height of the other surface Wb) is measured using the top surface height measuring device 32 of the thickness measuring device 30. , until the distance from the holding surface 131 to the other surface Wb of the wafer W matches the second total value Kb calculated in the first grinding end height position calculation step, the other surface Wb is polished by the grinding wheel 24 of the grinding mechanism 20. to grind.

At the stage when the distance from the holding surface 131 to the other surface Wb of the wafer W matches the second total value Kb, the determination unit 43 of the control unit 40 determines that the amount of grinding in the first grinding process has been reached, and One grinding process is completed. In the end processing of the first grinding process, the rotation of the chuck table 10 and the grinding wheel 23 is stopped, and the downward grinding feed of the grinding mechanism 20 by the grinding feed mechanism 25 is stopped. Then, the grinding mechanism 20 is raised by the grinding feed mechanism 25 to separate the grindstone 24 from the other surface Wb of the wafer W. Further, the operation of the suction source 15 is stopped, and the suction holding of the wafer W and the protection member 50 by the chuck table 10 is released.

[Reversal process/Peeling process]
After the first grinding process is completed, an inversion process and a peeling process (FIG. 8) are performed. In the reversing process and the peeling process, the wafer W is separated from the holding surface 131 by the transport mechanism 17, and the wafer W is carried out from the chuck table 10 ((A) in FIG. 8). The wafer W carried out from the chuck table 10 is transported to a peeling device (not shown). After the protective member 50 is peeled off from the wafer W by the peeling device, the wafer W is returned to the chuck table 10 by the transport mechanism 17. After the first grinding process, the wafer W is taken out from the chuck table 10 and the wafer W is returned to the chuck table 10 after the peeling process. The surface Wb of is placed on the holding surface 131 ((B) of FIG. 8). Then, the suction source 15 is operated to apply a suction force to the holding surface 131, thereby causing the holding surface 131 to suction and hold the other surface Wb. Thereby, the wafer W is held with one unground surface Wa facing upward. In this way, the peeling process of peeling off the protective member 50 from the wafer W is performed after the first grinding process and before the second grinding process.

[Second grinding process]
Next, a second grinding step (FIG. 9) is performed. In the second grinding step, one surface Wa of the wafer W is ground by the grindstone 24. More specifically, in the second grinding step, while measuring the top surface height of the wafer W (the height of one surface Wa) with the top surface height measuring device 32, the wafer is removed from the holding surface 131 measured by the thickness measuring device 30. One surface Wa is ground by the grindstone 24 until the distance (thickness of the wafer W) to the upper surface (one surface Wa) of W becomes the finished thickness Ta. Then, when the thickness of the wafer W measured by the thickness measuring device 30 reaches the finished thickness Ta, the determination unit 43 of the control unit 40 determines that the amount of grinding in the second grinding process has been reached, and the second Finish the grinding process.

In the end processing of the second grinding process, the rotation of the chuck table 10 and the grinding wheel 23 is stopped, and the downward grinding feed of the grinding mechanism 20 by the grinding feed mechanism 25 is stopped. Then, the grinding mechanism 20 is raised by the grinding feed mechanism 25 to separate the grindstone 24 from one surface Wa of the wafer W. Further, the operation of the suction source 15 is stopped, and the suction holding of the wafer W by the chuck table 10 is released.

[Export process]
When the second grinding process is completed, the wafer W, which has been ground on both surfaces Wa and Wb, is carried out from the chuck table 10 by the transport mechanism 17. After both surfaces of the wafer W have been ground, the protective member 50 has been removed, and the unloading process is the same as that of the first embodiment shown in FIG. 5.

The second embodiment of the wafer manufacturing method is performed as described above. According to this manufacturing method, in the first grinding end height position calculating step, the first grinding end height position is calculated in consideration of the thickness of the protective member 50, so that the protective member 50 covering the entire surface of one surface Wa is Regarding the formed wafer W, the amount of grinding of the other surface Wb in the first grinding step and the amount of grinding of one surface Wa in the second grinding step can be made the same amount.

As an example, the preset finishing thickness Ta is 800 μm, and the pre-grinding wafer thickness Tb of the wafer W (including the protective member 50) measured in the thickness measurement step is 1.5 mm. Further, the protective member thickness Tf measured in the protective member thickness measuring step is 500 μm. In other words, the actual wafer thickness Te before grinding excluding the thickness of the protective member 50 is 1.0 mm. In this case, the total value Ka calculated in the summing step is 900 μm.

In the first grinding end height position calculation step, the protection member thickness Tf (500 μm) and the total value Ka (900 μm) are added together to calculate the second total value Kb (1.4 mm). In the first grinding step, when grinding is performed until the distance from the holding surface 131 to the other surface Wb of the wafer W becomes 1.4 mm (second total value Kb), the amount of grinding for the other surface Wb becomes 100 μm. Become. In the second grinding step, when grinding is performed until the distance from the holding surface 131 to one surface Wa of the wafer W becomes 800 μm, which is the finished thickness Ta, the amount of grinding for the one surface Wa becomes 100 μm. Therefore, the amount of grinding on one surface Wa of the wafer W and the amount of grinding on the other surface Wb are the same.

In this manufacturing method, the numerical values referenced in each step are the finished thickness Ta included in processing-related data (grinding recipe) input in advance, the wafer thickness before grinding Tb measured by the thickness measuring device 30, and the non-contact thickness. It is based on the actual wafer thickness Te measured by the measuring device 35, and it is possible to obtain necessary numerical information without requiring any other special equipment or complicated control. Therefore, even for the wafer W covered with the protection member 50, the amount of grinding on one surface Wa and the amount of grinding on the other surface Wb can be easily made the same amount at low cost.

By making the amount of grinding on one surface Wa and the amount of grinding on the other surface Wb the same, the outer circumferential portion of the wafer W after grinding is less likely to be warped, and the subsequent transportation, holding, and grinding of the wafer W This makes it easier to perform various types of processing later on.

Note that in the first embodiment in which no protective member is provided on the wafer W, the thickness of the wafer W is measured with a non-contact thickness measuring device such as the non-contact thickness measuring device 35 instead of the contact-type thickness measuring device 30. You may. For example, the height position of the top surface of the wafer W is measured by receiving the top surface reflected light from the top surface of the wafer W with a sensor, and the holding surface 131 of the chuck table 10 from which the laser beam is reflected is measured by a sensor. The height position of the holding surface 131 is measured by receiving the reflected light with a sensor, and the thickness of the wafer W can be measured from the difference between the height of the upper surface of the wafer W and the height of the holding surface 131.

Note that the embodiments of the present invention are not limited to the above-described embodiments and modified examples, and may be variously changed, replaced, and modified without departing from the spirit of the technical idea of the present invention. Furthermore, if the technical idea of the present invention can be realized in a different manner due to advances in technology or other derived technologies, it may be implemented using that method. Accordingly, the claims cover all embodiments that may be included within the spirit of the invention.

As explained above, the present invention is a wafer manufacturing method in which a wafer is manufactured by grinding both sides of the wafer, and the amount of grinding on one side can be made the same amount as the amount of grinding on the other side. By grinding the same amount on both sides, the processing accuracy of the wafer can be improved and warping can be prevented. Therefore, high-quality wafers can be efficiently manufactured, and the method is extremely useful in the production of precision instruments using wafers.

1: Grinding device 10: Chuck table 13: Porous member 15: Suction source 16: Rotation drive mechanism 17: Conveyance mechanism 18: Reversing mechanism 20: Grinding mechanism 21: Spindle 22: Mount 23: Grinding wheel 24: Grinding wheel 25: Grinding feed Mechanism 30: Thickness measuring device 31: Holding surface height measuring device 32: Top surface height measuring device 35: Non-contact thickness measuring device 40: Control section 41: Thickness calculation section 42: Addition section 43: Judgment section 44: Second summation Part 50: Protective member 51: Resin layer 52: Sheet 131: Holding surface L: Measuring light Ta: Finished thickness Tb: Wafer thickness before grinding Tc: First grinding amount Td: Second grinding amount Te: Actual wafer thickness Tf: Protection Member thickness W: Wafer Wa: One side of the wafer Wb: Other side of the wafer

Claims (3)

A wafer manufacturing method that manufactures a wafer of a predetermined thickness by grinding both sides of the wafer, the method comprising:
a thickness measurement step of measuring the thickness of the wafer before grinding with a thickness measuring device;
a calculation step of subtracting a preset finishing thickness from the pre-grinding wafer thickness measured in the thickness measurement step;
a holding step of holding one side of the wafer on the holding surface of the chuck table;
a first grinding step of grinding the other surface of the wafer held on the holding surface by half the difference calculated in the calculation step;
a reversing step of separating the wafer from the holding surface and, after reversing, holding the other side of the wafer on the holding surface;
A second grinding step of grinding one side of the wafer held on the holding surface by half the difference calculated in the calculation step. Before the first grinding step, a summing step of calculating a total value of a half value of the wafer thickness measured in the thickness measuring step and a preset half value of the finished thickness,
In the first grinding step, the top surface height of the wafer is measured with a top surface height measuring device until the distance from the holding surface to the other surface of the wafer matches the total value calculated in the summing step. The method for manufacturing a wafer according to claim 1, wherein the wafer is ground. The wafer is provided with a protection member including a resin layer covering the entire surface of one side of the wafer,
Before the first grinding step, a protective member thickness measuring step of measuring the thickness of the protective member, and a first grinding end height position calculating step of adding up the thickness of the protective member and the total value. , a peeling step of peeling off the protective member after the first grinding step and before the second grinding step,
The holding step includes holding the wafer via the protection member,
In the first grinding step, the height of the top surface of the wafer held in the holding step is measured using a top surface height measuring device, and the distance from the holding surface to the other surface of the wafer is determined to be the height at which the first grinding is completed. 3. The wafer manufacturing method according to claim 2, wherein the wafer is ground until it matches the value calculated in the position calculation step.

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