Grinding apparatus and grinding method

Abstract

To prevent the scattering of water spray containing grinding debris generated during grinding. [Solution] The grinding apparatus comprises a holding table 10 for holding a wafer (workpiece) W, a grinding unit 20 for grinding the wafer W held on the holding table 10 with a grinding wheel 25b, and a grinding feed unit 3 for moving the grinding unit 20 away from or closer to the holding table 10. The apparatus includes a container-shaped bucket section 41 that surrounds the holding table 10 and the grinding wheel 25b at the grinding position where the grinding wheel 25b is in contact with the wafer W held on the holding table 10, and is capable of storing water inside, a water supply section 40 for supplying water into the bucket section 41, a first drain port 41a for discharging the water stored in the bucket section 41, and a control unit 50 that controls the grinding unit 20, the grinding wheel 25b and the water supply section 40 so that the grinding unit 20 grinds the wafer W held on the holding table 10 while maintaining its water seal state.

Description

[Technical Field]

[0001] The present invention relates to a grinding apparatus that grinds a workpiece, such as a wafer, held on a holding table using a rotating grinding wheel, and to a method for grinding a workpiece using the grinding apparatus. [Background technology]

[0002] For example, in the manufacturing process of semiconductor devices such as ICs and LSIs used in electronic devices, the back surface of the wafer is ground down by a grinding machine to reduce its thickness to a predetermined level in order to miniaturize and lighten the semiconductor device. In particular, in recent years, there has been a demand to form semiconductor devices thinly in order to meet the demands for thinner and smaller electronic devices.

[0003] Here, the wafer grinding apparatus includes a holding table that holds wafers on a holding surface, a grinding unit that grinds wafers held on the holding surface of the holding table with a grinding wheel which is a processing tool, a processing chamber that houses the holding table and the grinding wheel, and a grinding water supply means that supplies grinding water which is a processing fluid to the grinding wheel (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-137909 [Overview of the project] [Problems that the invention aims to solve]

[0005] Incidentally, in wafer grinding equipment, the holding table and grinding wheel are housed in the processing chamber. During grinding, the processing chamber is filled with grinding water, and the rotating grinding wheel grinds the wafer, causing a spray of grinding water containing grinding debris to be scattered. As a result, the spray of grinding water containing grinding debris adheres to the inner walls of the processing chamber (especially the inner walls of the side plates and top plates).

[0006] Furthermore, the rotation of the grinding wheel creates an airflow within the processing chamber, which dries any moisture from the spray adhering to the inner walls of the chamber, causing grinding debris to adhere to the inner walls. As the wafer is continuously ground, the accumulated grinding debris gradually grows larger, and when the processing chamber vibrates during the grinding process, the larger pieces of debris may fall onto the top surface of the wafer.

[0007] As described above, when grinding debris that has adhered to the inner wall of the processing chamber falls onto the top surface of the wafer, this debris can get trapped between the wafer and the grinding wheel, forming deep scratches on the wafer's surface. These deep scratches create a pattern on the wafer's surface that differs from the grinding pattern formed by the grinding wheel, and these scratches can negatively affect the device.

[0008] The present invention has been made in view of the above problems, and its object is to provide a grinding apparatus and a grinding method that can prevent the scattering of water spray containing grinding debris generated by grinding. [Means for solving the problem]

[0009] The invention described in claim 1 is a grinding apparatus comprising: a rotatable holding table for holding a workpiece; a grinding unit for grinding the workpiece held on the holding table with a rotating annular grinding wheel; and a grinding feed unit for moving the grinding unit away from or closer to the holding table, the apparatus comprising: a container-shaped tub section that surrounds the holding table and the grinding wheel at a grinding position where the grinding wheel is in contact with the workpiece held on the holding table and is capable of storing water inside; a water supply section for supplying water into the tub section; a first drain port for discharging the water stored in the tub section; and a control unit that controls the grinding unit, the grinding feed unit and the water supply section so that the grinding unit grinds the workpiece held on the holding table while maintaining its water seal.

[0010] The invention described in claim 2 is characterized in that, in the invention described in claim 1, the first drain port is provided with an opening / closing section whose opening and closing are controlled by the control unit according to the water seal state of the workpiece held on the holding table.

[0011] The invention described in claim 3 is characterized in that, in the invention described in claim 1, the water supply unit comprises a water supply source, a nozzle provided in the bucket, and a flow rate adjustment unit provided in the water supply path that supplies water from the water supply source to the nozzle.

[0012] The invention described in claim 4 is characterized in that, in the invention described in claim 1, the control unit includes a setting unit that sets the required time from when the water supply unit supplies water to the bucket unit until the workpiece held on the holding table is sealed with water.

[0013] The invention described in claim 5 is characterized in that, in the invention described in claim 1, the grinding unit is provided with a lid that selectively covers the upper opening of the bucket portion.

[0014] The invention described in claim 6 is characterized in that, in the invention described in claim 1, it comprises a drainage channel having a water receiving port for receiving water discharged from the first drain port and a second discharge port for discharging the water received from the water receiving port to the outside.

[0015] The invention described in claim 7 is a grinding method for grinding a workpiece using a grinding apparatus described in any one of claims 1 to 6, comprising: a water supply step of supplying water into the bucket section by the water supply section; a grinding step of grinding the workpiece with the grinding wheel while maintaining a water-sealed state of the workpiece held on the holding table; and a cleaning step of rotating at least one of the grinding wheel and the workpiece in a water-sealed state with the grinding wheel separated from the workpiece by the grinding feed unit.

[0016] The invention according to claim 8 is the invention according to claim 7, wherein in the water supply step, the control unit closes the first drain port by the opening and closing unit until a predetermined amount of water is stored in the bucket portion, and opens the first drain port by the opening and closing unit when a predetermined amount of water is stored in the bucket portion.

[0017] The invention according to claim 9 is the invention according to claim 7, wherein the control unit controls the flow rate adjustment unit so that water is supplied to the bucket portion at a first flow rate greater than the drainage volume from the first drain port until the workpiece held on the holding table is in a water-sealed state, and after the workpiece held on the holding table is in a water-sealed state, water is supplied to the bucket portion at a second flow rate equal to the drainage volume from the first drain port.

Advantages of the Invention

[0018] According to the grinding method according to claim 7 implemented using the grinding apparatus according to any one of claims 1 to 6, since the holding table, the workpiece, and the grinding wheel are all immersed in the water constantly flowing in the bucket portion and are in a water-sealed state, grinding debris generated by grinding the workpiece does not scatter around, the generated grinding debris is contained in the water flowing in the bucket portion, and the water containing this grinding debris is discharged from the first drain port to the outside of the bucket portion, so that scattering of the spray of water containing grinding debris is prevented.

[0019] According to the inventions according to claims 2 and 8, when storing a predetermined amount of water in the bucket portion prior to grinding the workpiece, the opening and closing unit is closed to prevent the discharge of water from the bucket portion, so that the time until a predetermined amount of water is stored in the bucket portion can be shortened.

[0020] According to the inventions according to claims 3 and 9, when storing a predetermined amount of water in the bucket portion prior to grinding the workpiece, by increasing the amount (flow rate) of water supplied to the bucket portion by the flow rate adjustment unit, the time until a predetermined amount of water is stored in the bucket portion can be shortened.

[0021] According to the invention described in claim 4, it is possible to determine whether or not a predetermined amount of water has been stored in the bucket by determining whether or not a time set in the control unit's setting unit has elapsed. Incidentally, if this determination is made by detecting the water level in the bucket using a water level sensor, foreign matter such as grinding debris may adhere to the water level sensor, potentially reducing its accuracy and sensitivity.

[0022] According to the invention described in claim 5, in the grinding and washing processes, the upper opening of the bucket is covered by the lid, thereby more reliably preventing the scattering of water containing grinding debris during grinding and washing.

[0023] According to the invention described in claim 6, a predetermined amount of water can be supplied to the bucket section while a predetermined amount of water can be discharged from the bucket section to the outside of the bucket section through the drainage channel. Therefore, the workpiece can be ground and cleaned while clean water flows continuously through the bucket section. [Brief explanation of the drawing]

[0024] [Figure 1] This is a perspective view of the grinding apparatus according to the present invention. [Figure 2] This is a plan view of the main part of the grinding apparatus according to the present invention. [Figure 3] This is a cross-sectional view along line AA in Figure 2. [Figure 4] (a) to (c) are side cross-sectional views of the main part of a grinding apparatus showing the grinding method according to the present invention in the order of its steps. [Figure 5] This flowchart shows the procedure for the grinding method according to the present invention. [Figure 6] This is a time chart showing the changes over time in the opening and closing of the valve, the amount of water supplied to the bucket, and the amount of water drained from the bucket. [Figure 7] This is a time chart showing another example of the time changes in the opening and closing of a valve, the amount of water supplied to the bucket, and the amount of water drained from the bucket. [Figure 8] This is a side cross-sectional view of a main part of a grinding device according to another embodiment of the present invention. [Figure 9](a) to (c) are side cross-sectional views of the main parts of the grinding apparatus, showing the grinding method using the grinding apparatus shown in Figure 8 in order of the process steps. [Modes for carrying out the invention]

[0025] Embodiments of the present invention will be described below with reference to the accompanying drawings.

[0026] First, the overall configuration of the grinding apparatus according to the present invention will be described with reference to Figure 1. In the following description, the arrow directions shown in Figure 1 will be the X-axis direction (left-right direction), the Y-axis direction (front-back direction), and the Z-axis direction (up-down direction), respectively.

[0027] [Configuration of the grinding machine] The grinding apparatus 1 shown in Figure 1 is a device for grinding a disc-shaped wafer W, which is a workpiece, and its main components include three holding tables 10 arranged on a rotatable disc-shaped turntable 2, a rough grinding unit 20 and a finish grinding unit 30 which are processing means for grinding the wafer W held on the holding tables 10, a pair of grinding feed units 3 which raise and lower the rough grinding unit 20 and the finish grinding unit 30 in the vertical direction, a bucket section 41 (see Figures 2 and 3) installed on the turntable 2 and surrounding the holding tables 10, a water supply unit 40 which supplies water to the bucket section 41, and a control unit 50 which controls the rough grinding unit 20, the finish grinding unit 30, the grinding feed unit 3, the water supply unit 40, etc.

[0028] The grinding apparatus 1 also includes other components such as a pair of cassettes 201 and 202, an in / out robot 70, an alignment table 102, a first transport means 71, a second transport means 72, a pair of thickness measuring instruments 81 and 82, and a cleaning unit 60, the functions of which will be described later. In this embodiment, the workpiece wafer W is a thin, disc-shaped member made of a single-crystal silicon matrix, and multiple devices (not shown) are formed on the downward-facing surface as shown in Figure 1.

[0029] Next, the configurations of the main components of the grinding apparatus 1 according to the present invention—the holding table 10, the rough grinding unit 20 and the finish grinding unit 30, the grinding feed unit 3, the bucket section 41, the water supply section 40, and the control unit 50—will be described.

[0030] (Retention table) The three holding tables 10 are disc-shaped members and are arranged at equal angular pitches (120° pitches) in the circumferential direction on a disc-shaped turntable 2 that rotates intermittently around a central axis perpendicular to the Z-axis direction. That is, the upper surface of the turntable 2 is divided into three regions by partition plates 11 extending radially from the center: a wafer loading / unloading region R1, a rough grinding region R2, and a finish grinding region R3, with a holding table 10 arranged in each of the three regions R1, R2, and R3. These holding tables 10 rotate (revolve) at an angle of 120° each around an axis perpendicular to the Z-axis direction along with the turntable 2 as it rotates intermittently, moving sequentially between the wafer loading / unloading region R1, the rough grinding region R2, and the finish grinding region R3, and also rotate (spin) at a predetermined speed around its own vertical central axis by a rotation mechanism (not shown).

[0031] Each holding table 10 has a disc-shaped porous member 10A made of porous ceramic or the like incorporated in its center, and the upper surface of each porous member 10A forms a holding surface 10a that sucks and holds a disc-shaped wafer W. The holding surface 10a of each holding table 10 is selectively connected to a suction source (not shown), such as a vacuum pump or ejector.

[0032] (Rough grinding unit and finish grinding unit) The rough grinding unit 20 and the finish grinding unit 30 are positioned perpendicularly along the X-axis direction (left-right direction) at the +Y-axis end (rear end) of a rectangular box-shaped base 100 that is long in the Y-axis direction (front-to-back direction). Here, the rough grinding unit 20 is a unit that rough grinds the upper surface (workpiece surface) of the wafer W held on the holding surface 10a of the holding table 10 located in the rough grinding region R2, and the finish grinding unit 30 is a unit that finish grinds the upper surface (workpiece surface) of the wafer W held on the holding surface 10a of the holding table 10 located in the finish grinding region R3, and the basic configuration of both is the same.

[0033] In other words, the rough grinding unit 20 comprises a spindle motor 22 fixed to a holder 21, a vertical spindle 23 rotationally driven by the spindle motor 22, a disc-shaped mount 24 attached to the lower end of the spindle 23, and a grinding wheel 25 detachably mounted on the lower surface of the mount 24. Here, the grinding wheel 25 is composed of a disc-shaped base 25a and a plurality of grinding wheels 25b, which are workpieces attached in an annular shape to the lower surface of the base 25a, and is rotationally driven around the axis of the spindle 23, which is the grinding wheel rotation axis.

[0034] Furthermore, the finish grinding unit 30, like the rough grinding unit 20, includes a spindle motor 32 fixed to a holder 31, a vertical spindle 33 rotationally driven by the spindle motor 32, a disc-shaped mount 34 attached to the lower end of the spindle 33, and a grinding wheel 35 detachably mounted on the lower surface of the mount 34. Here, the grinding wheel 35 is composed of a disc-shaped base 35a and a plurality of grinding wheels 35b, which are processing tools attached in an annular shape to the lower surface of the base 35a, but the grinding wheels 35b are composed of finer abrasive grains than the grinding wheel 25b of the rough grinding unit 20.

[0035] (Grinding feed unit) In this embodiment, a pair of grinding feed units 3 are provided on the -Y axis end faces (front surfaces) of a pair of block-shaped columns 101 that are erected vertically along the X axis (left-right direction) at the +Y axis end (rear end) of the base 100. These grinding feed units 3 raise and lower the rough grinding unit 20 and the finish grinding unit 30 in the vertical direction (Z axis direction) to move them apart from or closer to the holding table 10, and their configurations are the same; therefore, corresponding components will be denoted by the same reference numerals below.

[0036] Each grinding feed unit 3 is equipped with a rectangular plate-shaped lifting plate 4 and a pair of left and right guide rails 5 to guide the lifting movement of the lifting plate 4. A rough grinding unit 20 and a finish grinding unit 30 are attached to each lifting plate 4. The pair of left and right guide rails 5 are arranged perpendicularly and parallel to each other on the front surface of the column 101.

[0037] A rotatable ball screw 6 is erected vertically between a pair of left and right guide rails 5 along the Z-axis direction (up and down direction), and the upper end of the ball screw 6 is connected to a reversible servo motor 7, which is the drive source. The lower end of the ball screw 6 is rotatably supported by a bearing (not shown) on a column 101, and a nut member (not shown) that protrudes horizontally toward the rear (+Y-axis direction) from the back of the lifting plate 4 is screwed onto the ball screw 6.

[0038] Therefore, when the servo motors 7 of each grinding feed unit 3 configured as described above are activated to rotate each ball screw 6 in the forward and reverse directions, each lifting plate 4, which has a nut member (not shown) protruding from it that screws onto each ball screw 6, moves up and down along a pair of left and right guide rails 5. As a result, the rough grinding unit 20 and the finish grinding unit 30 attached to the lifting plates 4 also move up and down independently of each other along the Z-axis direction (vertical direction).

[0039] (Okebe) As shown in Figures 2 and 3, the wafer loading / unloading area R1, the rough grinding area R2, and the finish grinding area R3, which are divided into three sections by a partition plate 11 on the upper surface of the turntable 2, have three container-shaped bucket sections 41 surrounding each holding table 10, which are arranged radially at equal angular pitches (120° pitches) in the circumferential direction. In addition, an annular channel member 45 with an open top surface is installed around the turntable 2 on the base 100, and an annular drainage channel 45A is formed in this channel member 45.

[0040] As shown in Figures 2 and 3, a circular first drain port 41a is provided at the radially inner end of the bottom plate 40A of each bucket section 41. As shown in Figure 3, each first drain port 41a opens to the annular water receiving port 45b of the drain channel 45A of the channel member 45 via a drain pipe 46 extending vertically downward from the bottom plate 41A. Here, an electromagnetic (solenoid) on-off valve V1, which constitutes the opening and closing mechanism, is provided in the first drain port 41a. This on-off valve V1 is electrically connected to a control unit 50, and its opening and closing operation is controlled by the control unit 50.

[0041] Furthermore, as shown in Figure 2, a circular second drain port 45a is provided at one location on the bottom of the annular channel member 45 arranged around the turntable 2. This second drain port 45a is connected to a wastewater treatment facility via a drain pipe (not shown).

[0042] (Water supply section) The water supply unit 40 is composed of a nozzle 42 located inside each bucket section 41 and a water supply source 44, such as a water pump, connected to the nozzle 42 via piping 43. The piping 43 is equipped with a flow control valve V2, which acts as a flow control unit to adjust the flow rate (amount of water supplied) of water supplied from the water supply source 44 to the bucket section 41. The flow control valve V2 is electrically connected to a control unit 50, and the amount of water supplied to the bucket section 41 is adjusted by controlling its opening degree by the control unit 50. The nozzles 42 that supply water to each bucket section 41 are erected vertically on the radial inner circumference (right end in Figure 3) of the bottom plate 41A of each bucket section 41, as shown in Figures 2 and 3.

[0043] In this embodiment, as shown in Figures 1 and 3, the portion of the turntable 2 facing the rough grinding area R2 and the finish grinding area R3, the two holding tables 10 located in this portion, the wafers W held on these holding tables 10, and parts of the grinding wheels 25 and 35 of the rough grinding unit 20 and the finish grinding unit 30 are housed in a processing chamber S formed by a processing chamber cover 90. Although not shown, a rectangular opening is formed in the portion of the processing chamber cover 90 through which the holding tables 10 pass, allowing the holding tables 10 to pass. Furthermore, pure water is preferably used as the water.

[0044] (Control unit) The control unit 50 shown in Figure 1 includes a CPU (Central Processing Unit) that performs calculations according to a control program, a storage unit such as ROM (Read Only Memory) and RAM (Random Access Memory), and a setting unit 51 that sets the time required from the time water is supplied to the bucket section 41 by the water supply unit 40 until the wafer W held on the holding table 10 is water-sealed. In particular, in this embodiment, the control unit 50 performs the function of controlling the rough grinding unit 20, the finish grinding unit 30, the grinding feed unit 3, the on / off valve V1, the flow rate adjustment valve V2 of the water supply unit 40, etc., so that the wafer W held on the holding table 10 located in the rough grinding area R2 and the finish grinding area R3 can be ground while maintaining its water-sealed state, but the details will be described later.

[0045] [Grinding Method] Next, a method for grinding a wafer W using the grinding apparatus 1 configured as described above will be explained.

[0046] The wafer grinding method according to the present invention is: 1) Wafer holding process: 2) Water supply process: 3) Grinding process: 4) Washing process: This method grinds the wafer W to a predetermined thickness by sequentially performing the following steps in this order. Each step will be explained below with reference to Figures 4 to 7.

[0047] 1) Wafer holding process: When grinding a wafer W, the loading / unloading robot 70 shown in Figure 1 removes one wafer W from one cassette 201 before processing, and the removed wafer W is transferred to the alignment table 102. On the alignment table 102, the wafer W is aligned (centered), and the aligned wafer W is transferred by the first transport means 71 to the holding table 10 located in the wafer loading / unloading area R1, where it is held by suction on the holding table 10 (step S1 in Figure 5). That is, when the porous member 10A of the holding table 10 on which the wafer W is placed is connected to a suction source (not shown), the porous member 10A is evacuated by the suction source (not shown), generating negative pressure on the holding surface 10a, and the wafer W is held by suction on the holding surface 10a of the holding table 10 due to this negative pressure.

[0048] As described above, when the wafer W is held by suction on the holding surface 10a of the holding table 10 in the wafer loading / unloading area R1, the turntable 2 rotates 120° around its vertical axis in the direction of the arrow in Figure 1, and as a result the holding table 10 and the wafer W held therein move from the wafer loading / unloading area R1 to the rough grinding area R2 (step S2 in Figure 5).

[0049] 2) Water supply process: As described above, when the wafer W held on the holding surface 10a of the holding table 10 in the preceding wafer holding process moves together with the holding table 10 from the wafer loading / unloading area R1 to the rough grinding area R2, the control unit 50 closes the on / off valve V1 that opens and closes the first drain port 41a of the bucket section 41 (step S3 in Figure 5), as shown in Figure 6(a), and supplies water from the water supply source 44 shown in Figure 3 to the bucket section 41 via the piping 43 and nozzle 42 (step S4 in Figure 5). At this time, the opening degree of the flow rate adjustment valve V2 is controlled by the control unit 50, and the amount of water supplied to the bucket section 41 (first flow rate) Q i2 The amount of water supplied (second flow rate) Q after time t1 following the opening of the on / off valve V1. i1 It is set to be a value greater than (Q i2 Q>Q i1)。Note that, as shown in Fig. 6(a), when the on-off valve V1 is closed, water is not discharged from the bucket portion 41. Therefore, as shown in Fig. 6(c), the amount of water discharged from the bucket portion 41 is 0.

[0050] As described above, when water is supplied from the water supply source 44 to the bucket portion 41 with the on-off valve V1 closed, as shown in Fig. 4(a), water is gradually stored in the bucket portion 41. However, whether a predetermined amount of water is stored in the bucket portion 41 is determined by the control unit 50 (step S5 in Fig. 5). Here, the predetermined amount of water stored in the bucket portion 41 is an amount sufficient for the holding table 10, the wafer W, and the grinding wheel 25b to be immersed in the water in the bucket portion 41 and be in a water-sealed state as shown in Fig. 4(b) in the subsequent grinding process. The time t1 (see Fig. 6) required for this predetermined amount of water to be stored in the bucket portion 41 is set by the setting unit 51 of the control unit 50.

[0051] Therefore, the determination of whether a predetermined amount of water is stored in the bucket portion 41 is made based on whether the time t1 has elapsed since the start of the water supply to the bucket portion 41. As a result of this determination, since the time t1 has elapsed since the start of the water supply to the bucket portion 41, as shown in Fig. 4(a), when a predetermined amount of water is supplied and stored in the bucket portion 41 (step S5: Yes in Fig. 5), as shown in Fig. 6(a), the on-off valve V1 is opened by the control unit 50 at time t1 (step S6 in Fig. 5). Then, water is supplied from the water supply source 44 to the bucket portion 41 at a water supply rate Q i1 (see Fig. 6(b)), and as shown in Fig. 6(c), water of approximately the same amount as the water supply rate Q i1 is discharged from the bucket portion 41 at a drainage rate Q d (≒Q i1 ). [[ID=I8]]

[0052] That is, a predetermined amount (drainage rate Q d ) of water flows from the bucket portion 41 through the drain pipe 46 from the first drain port 41a to the drain passage 45A of the channel member 45, and the water that has flowed into the drain passage 45A is discharged outside the drain passage 45A from the second drain port 45a (see Fig. 2) that opens into the drain passage 45A. Therefore, a certain amount of water constantly flows in the bucket portion 41.

[0053] As described above, in this embodiment, the on / off valve V1 provided at the first drain port 41a is closed until a predetermined time t1 has elapsed, and after time t1 has elapsed, the amount of water supplied to the bucket section 41 (second flow rate) Q i1 A larger water supply volume (first flow rate) Q i2 (>Q i1 As the water is supplied to the bucket section 41 by the ), the time t1 required for a predetermined amount of water to be stored in the bucket section 41 is shortened, as shown in Figure 4(a).

[0054] In this embodiment, the determination of whether a predetermined amount of water has been stored in the bucket section 41 is made by determining whether a time t1 set in the setting section 51 of the control unit 50 has elapsed. However, the determination of whether a predetermined amount of water has been stored in the bucket section 41 may also be made by detecting the water level in the bucket section 41 using a water level sensor. However, in this case, foreign matter (contamination) such as grinding debris may adhere to the water level sensor, potentially reducing the accuracy and sensitivity of the water level sensor.

[0055] Furthermore, in this embodiment, the on-off valve V1 is kept closed until a predetermined amount of water is stored in the bucket section 41 (until time t1 has elapsed). However, as shown in Figure 7(a), the on-off valve V1 may be kept open at all times. In this case, however, as shown in Figure 7(b), the amount of water supplied to the bucket section 41 Q is kept open from the time t1 when the supply of water to the bucket section 41 is started until a predetermined amount of water is stored in the bucket section 41. i2 The amount of water supplied Q after time t1 has elapsed. d1 (Alternatively, drainage volume Q) d It needs to be set to a value greater than (see Figure 7(c)).

[0056] As described above, when a predetermined amount of water is stored in the bucket section 41 and water is flowing steadily through the bucket section 41, the holding table 10 and the wafer W held therein are immersed in the water stored in the bucket section 41 and are in a water-sealed state, as shown in Figure 4(a).

[0057] 3) Grinding process: As described above, in the wafer loading / unloading area R1, water is supplied from the water supply source 44 to the bucket section 41, and the holding table 10 and wafer W are immersed in the water that flows steadily in the bucket section 41, maintaining a water seal state. In the next grinding step, the wafer W is ground. In this embodiment, rough grinding is performed on the wafer W by the rough grinding unit 20 and finish grinding is performed by the finish grinding unit 30.

[0058] In other words, during rough grinding of the wafer W by the rough grinding unit 20, as shown in Figure 4(b), the holding table 10 is driven to rotate around its central axis at a predetermined speed in the direction of the arrow by a rotation mechanism (not shown), and the grinding wheel 25 is driven to rotate around its central axis at a predetermined speed in the direction of the arrow by a spindle motor 22, while the grinding feed unit 3 lowers the grinding wheel 25. As a result, the grinding wheel 25b of the grinding wheel 25 is immersed in the water in the bucket 41 and enters a water-sealed state, and the grinding wheel 25b comes into contact with the back surface (top surface) of the wafer W, which is also in a water-sealed state, and rough grinds the back surface (top surface) of the wafer W (step S7 in Figure 5).

[0059] During rough grinding of the wafer W, the holding table 10, the wafer W, and the grinding wheel 25b are all immersed in water that flows steadily within the bucket section 41, creating a water seal. As a result, grinding debris generated during the rough grinding of the wafer W does not scatter into the surrounding area within the processing chamber S. The generated grinding debris is contained in the water flowing within the bucket section 41, and this water containing grinding debris flows from the first drain port 41a through the drain pipe 46 (see Figure 3) into the drain channel 45A of the channel member 45, and is discharged outside the drain channel 45A from the second drain port 45a (see Figure 2) that opens into the drain channel 45A. Therefore, spray of water containing grinding debris does not scatter within the processing chamber S, and this scattered spray does not adhere to the inner wall of the processing chamber cover 90, nor does the spray adhering to the inner wall of the processing chamber cover 90 dry and cause grinding debris to fall onto the upper surface of the wafer W being ground, damaging the wafer W. Furthermore, since clean water is constantly circulating within the bucket section 41, grinding debris contained in the water does not accumulate within the bucket section 41, and the grinding debris is effectively discharged from the bucket section 41 along with the water.

[0060] During the rough grinding of the wafer W, the thickness of the wafer W is measured by the thickness measuring instrument 81 shown in Figure 1, and when the measurement signal is transmitted to the control unit 50, the control unit 50 determines whether or not the rough grinding of the wafer W is complete by determining the thickness of the wafer W (step S8 in Figure 5). If the wafer W has been roughly ground to a predetermined thickness, it is determined that the rough grinding is complete (step S8 in Figure 5: Yes), and the process proceeds to the next step, finish grinding. If the rough grinding of the wafer W is not complete (step S8: No), the rough grinding of the wafer W by the rough grinding unit 20 continues until the thickness of the wafer W reaches a predetermined thickness (steps S7 to S8).

[0061] During the finish grinding of the wafer W, the turntable 2 shown in Figure 1 intermittently rotates 120° in the direction of the arrow around a vertical axis by a rotation mechanism (not shown). As a result, the holding table 10 located in the rough grinding area R2 and the wafer W held by it rotate (revolve) 120° along with the turntable 2 in the direction of the arrow, and the holding table 10 and wafer W move from the rough grinding area R2 to the finish grinding area R3 (step S9 in Figure 5). During this time, a predetermined amount of water flows steadily inside the bucket section 41.

[0062] As described above, when the holding table 10 and wafer W move to the finish grinding area R3, the wafer W is finish-ground by the grinding wheel 35b of the finish grinding unit 30 in this finish grinding area R3 (step S10 in Figure 5). The finish grinding of the wafer W in the finish grinding area R3 is performed in the same way as the rough grinding in the rough grinding area R2, so the illustration and explanation of this are omitted, but in this finish grinding as well, the finish grinding of the wafer W is performed in a water-sealed state in which the holding table 10, wafer W and the grinding wheel 35b of the finish grinding unit 30 are immersed in water that flows steadily inside the bucket section 41.

[0063] Even during the finish grinding of the wafer W, the thickness of the wafer W is measured by the thickness measuring instrument 82 shown in Figure 1, and the control unit 50 determines whether the finish grinding of the wafer W is complete based on the measured thickness of the wafer W (step S11 in Figure 5). If the wafer W has been finished grinding to a predetermined thickness, it is determined that the finish grinding is complete (step S11 in Figure 5: Yes), and the process proceeds to the next cleaning step (step S12). If the finish grinding of the wafer W is not complete (step S11: No), the finish grinding of the wafer W by the finish grinding unit 30 continues until the thickness of the wafer W reaches a predetermined thickness (steps S10 → S11).

[0064] Furthermore, in this finish grinding process, just as in the rough grinding process, the spray of water containing grinding debris does not scatter within the processing chamber S, and the same effects as those obtained in the rough grinding process are achieved. As a result, the spray does not scatter within the processing chamber S, and problems such as the spray adhering to the inner wall of the processing chamber cover 90, or the spray adhering to the inner wall of the processing chamber cover 90 drying and causing processing debris to fall onto the upper surface of the wafer W being ground and damage the wafer W, do not occur.

[0065] 4) Washing process: In the cleaning process, in the finish grinding region R3, as shown in Figure 4(c), the grinding feed unit 3 raises the finish grinding unit 30 by a predetermined amount, and the grinding wheel 35b of the finish grinding unit 30 is immersed in water, maintaining a water seal state together with the wafer W, while the grinding wheel 35b is slightly separated from the wafer W, forming a predetermined gap between them. In this state, the grinding wheel 35b and the wafer W are each driven to rotate at a predetermined speed in the direction of the arrows shown in the figure.

[0066] As a result, the wafer W and grinding wheel 35b, which are in a water-sealed state, rotate together in the water, and the wafer W and grinding wheel 35b are washed by the water, and any grinding debris adhering to them is washed away and removed.

[0067] As described above, when the wafer W is cleaned in the cleaning process, the rotation of the wafer W and the grinding wheel 35b stops, the supply of water to the bucket 41 stops, and the water is drained from the bucket 41 (Figure 5, step S13). That is, as shown in Figure 6(b) or Figure 7(b), at time t2 when the cleaning process is completed, the supply of water from the water supply source 44 (see Figure 3) to the bucket 41 stops (water supply amount = 0). At this time, since the on-off valve V1 is open, the water in the bucket 41 is drained from the first drain port 41a through the drainage channel 45A of the channel member 45 and out of the second drain port 45a with a drainage amount Q d It is then discharged to the outside.

[0068] As described above, once the water is drained from the bucket section 41 and the bucket section 41 becomes empty, the turntable 2 rotates 120° around its central axis in the direction of the arrow in Figure 1, and the holding table 10 and the wafer W held therein move from the finishing grinding area R3 to the wafer loading / unloading area R1 (step S14 in Figure 5). Then, the wafer W is sucked and held by the second transport means 72 shown in Figure 1 and transported from the holding table 10 to the cleaning unit 60, where the wafer W is cleaned by the cleaning unit 60 (step S15 in Figure 5).

[0069] In other words, in the cleaning unit 60, the wafer W, which is held by suction by the second transport means 72, is placed on the spinner table 61 and held by suction. From this state, the spinner table 61 is driven to rotate at high speed around a vertical axis by a rotation mechanism (not shown) together with the wafer W, and cleaning water (pure water) is sprayed from the spray nozzle 62 toward the center of the wafer W. As a result, the cleaning water sprayed toward the center of the wafer W flows from the center toward the outer edge of the upper surface of the wafer W due to centrifugal force, so the upper surface of the wafer (the surface to be ground) is cleaned by this cleaning water, and grinding debris adhering to the wafer W is washed away and removed by the cleaning water.

[0070] As described above, once the wafer W is cleaned in the cleaning unit 60, the loading / unloading robot 70 transports the wafer W from the cleaning unit 60 to the cassette 202 and stores it in the cassette 202 (step S16 in Figure 15), thus completing a series of grinding processes for one wafer W.

[0071] Subsequently, it is determined whether grinding of all wafers W in the cassette 201 has been completed (step S17 in Figure 15). If grinding of all wafers W has been completed (step S17: Yes), the series of processes ends (step S18 in Figure 15). If it has not been completed (step S17: No), the process returns to step S1, and the series of processes described above is repeated for the next wafer W.

[0072] As is clear from the above explanation, this embodiment provides the effect of preventing the scattering of water spray containing grinding debris generated by grinding the wafer W.

[0073] Next, another embodiment of the present invention will be described with reference to Figures 8 and 9. In Figures 8 and 9, the same reference numerals are used for elements that are the same as those shown in Figures 3 and 4, and further explanation of these elements will be omitted.

[0074] <Another embodiment of the present invention> In this embodiment, as shown in Figure 8, a lid portion 26 is attached to the lower surface of the holder 21 of the rough grinding unit 20 of the barrel portion 41, selectively covering the upper opening of the barrel portion 41. The other configurations are the same as those in the above embodiment. Although Figure 8 shows the rough grinding unit 20 with the lid portion 26 attached, as shown in Figure 9(c), a similar lid portion 26 is also attached to the finish grinding unit 30.

[0075] In this embodiment as well, the wafer W is ground by sequentially going through 1) a holding step, 2) a water supply step, 3) a grinding step, and 4) a cleaning step.

[0076] In other words, during the holding process, as shown in Figures 8 and 9(a), the lid portion 26 is positioned above the bucket portion 41 without covering the upper opening of the bucket portion 41, and the wafer W is held by suction on the holding surface 10a of the holding table 10.

[0077] Then, in the water supply and grinding processes, as shown in Figure 9(b), the rough grinding unit 20 descends and the lid portion 26 covers the upper opening of the bucket portion 41. Water is supplied to the bucket portion 41, and water flows steadily in the space formed by the bucket portion 41 and the lid portion 26. The holding table 10, the wafer W, and the grinding wheel 25b maintain a water seal, and the upper surface of the wafer W is roughly ground by the grinding wheel 25b. Although not shown, the wafer W is also finished by the finish grinding unit 30 while maintaining a water seal.

[0078] Furthermore, in the cleaning process, the wafer W that has been finished-ground by the finishing grinding unit 30 is cleaned by rotating together with the holding table 10 in the direction of the arrow shown in the figure, while being immersed in water that flows steadily through the space formed by the bucket portion 41 and the lid portion 26, as shown in Figure 9(c), and maintaining a water seal state.

[0079] Therefore, in this embodiment as well, the grinding and cleaning processes are carried out while the wafer W is kept in a water-sealed state, and the same effects as those obtained in the previous embodiment are obtained. However, in this embodiment, the wafer W is ground (rough grinding and finish grinding) and cleaned with the upper opening of the bucket portion 41 covered by the lid portion 26, so the scattering of water containing grinding debris during grinding and cleaning is prevented even more reliably.

[0080] Although the above explanation describes the case where the workpiece is a wafer, the present invention can be applied similarly to any workpiece other than a wafer to obtain the same effects.

[0081] Furthermore, although the embodiments described above have described a form in which a wafer is roughly ground and finish ground as an example, the present invention can also be applied to a form in which a workpiece is simply ground.

[0082] Furthermore, the present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the technical idea described in the claims, specification, and drawings. [Explanation of symbols]

[0083] 1: Grinding device, 2: Turntable, 3: Grinding feed unit, 4: Lifting plate, 5: Guide rail, 6: Ball screw shaft, 7: Servo motor, 10: Holding table, 20: Rough grinding unit, 21: Holder, 22: Spindle motor, 23: Spindle, 24: Mount, 25: Grinding wheel, 25a: Base, 25b: Grinding wheel, 26: Cover 30: Finishing grinding unit, 31: Holder, 32: Spindle motor, 33: Spindle, 34: Mount, 35: Grinding wheel, 35a: Base, 35b: Grinding, 40: Water supply unit, 41: Bucket section, 41A: Bottom plate of bucket section, 41a: First discharge port, 42: Nozzle, 43: Piping (water supply route), 44: Water supply source, 45: Channel component, 45A: Drainage channel, 45a: Second drain outlet, 45b: Water receiving outlet, 46: Drain pipe, 50: Control unit, 51: Setting unit, 60: Cleaning unit, 61: Spinner table, 62: Spray nozzle, 70: Loading / unloading robot, 71: First transport means, 72: Second transport means, 81, 82: Thickness measuring instrument, 90: Processing chamber cover, 100: Base, 101: Column, 102: Alignment table, 202, 202: Cassette, Q d :Drainage volume, Q i1 : Water supply amount (second flow rate), Q i2 : Water supply amount (first flow rate), R1: Wafer loading / unloading area, R2: Rough grinding area, R3: Finish grinding area, S: Processing room t1, t2: time, V1: on / off valve (on / off part), V2: flow control valve (flow control part) W: Wafer (workpiece)

Claims

1. A rotatable holding table for holding the workpiece, A grinding unit that grinds a workpiece held on the holding table with a rotating annular grinding wheel, A grinding feed unit that moves the grinding unit away from or closer to the holding table, A grinding apparatus comprising, A container-shaped tub capable of storing water is provided, surrounding the holding table and the grinding wheel at the grinding position where the grinding wheel is in contact with the workpiece held on the holding table, A water supply unit that supplies water into the bucket section, A first drain port for discharging the water stored in the barrel section, A control unit controls the grinding unit, the grinding feed unit, and the water supply unit so that the grinding unit grinds the workpiece held on the holding table while maintaining its water seal state. A grinding apparatus characterized by being equipped with the following features.

2. The grinding apparatus according to claim 1, characterized in that the first drain port is provided with an opening / closing section whose opening and closing are controlled by the control unit according to the water seal state of the workpiece held on the holding table.

3. The water supply unit is Water supply sources, A nozzle provided inside the barrel section, A flow rate adjustment unit is provided in the water supply path that supplies water from the water supply source to the nozzle, The grinding apparatus according to claim 1, characterized by comprising:

4. The control unit is The grinding apparatus according to claim 1, further comprising a setting unit for setting the required time from when water is supplied to the bucket by the water supply unit until the workpiece held on the holding table is sealed with water.

5. The grinding device according to claim 1, characterized in that the grinding unit is provided with a lid that selectively covers the upper opening of the bucket portion.

6. The grinding apparatus according to claim 1, characterized in that it comprises a drainage channel having a water receiving port for receiving water discharged from the first drain port and a second discharge port for discharging the water received from the water receiving port to the outside.

7. A grinding method for grinding a workpiece using a grinding apparatus according to any one of claims 1 to 6, A water supply step in which water is supplied into the bucket section by the water supply unit, A grinding step in which the workpiece held in the holding table is ground with the grinding wheel while maintaining the water seal on the workpiece, A cleaning step in which the grinding wheel is separated from the workpiece by the grinding feed unit and at least one of the grinding wheel and the workpiece is rotated in a water-sealed state, A grinding method characterized by comprising the following features.

8. The control unit is The grinding method according to claim 7, characterized in that, in the water supply step, the first drain port is closed by the opening / closing unit until a predetermined amount of water is stored in the bucket, and the first drain port is opened by the opening / closing unit when a predetermined amount of water is stored in the bucket.

9. The control unit is The grinding method according to claim 7, characterized in that water is supplied to the bucket at a first flow rate greater than the amount of water drained from the first drain port until the workpiece held on the holding table is in a water-sealed state, and after the workpiece held on the holding table is in a water-sealed state, the flow rate adjustment unit is controlled so that water is supplied to the bucket at a second flow rate equal to the amount of water drained from the first drain port.

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