JP2023161339A - Wafer grinding apparatus and grinding method - Google Patents

Abstract

To grind a wafer into a uniform thickness over the entire surface while suppressing heat deformation of the wafer due to grinding water.SOLUTION: A wafer grinding method for grinding a wafer W with a rotating annular grindstone 26b by rotating the wafer W held on a holding surface 11a of a chuck table 10 makes grinding water that is linearly ejected toward the center part of the wafer W from a nozzle 50 reach an outer peripheral portion of the rotating wafer W, makes the grinding water head toward the outer periphery of the wafer W along the upper surface of the wafer W by applying the centrifugal force to the grinding water with rotation of the chuck table 10 while moving the grinding water along the upper surface of the wafer W toward the center from the outer peripheral portion of the wafer W, moves the grinding water to a processing point (processing region R) where a grindstone 26b comes into contact with the wafer W to grind the wafer W while supplying the grinding water to the entire region of the processing point (processing region R).SELECTED DRAWING: Figure 3

Description

The present invention relates to a wafer grinding device and a wafer grinding method using the grinding device.

A wafer grinding device grinds the top surface of a wafer held on a holding surface of a chuck table by rotating and abutting a plurality of block-shaped grindstones arranged in a ring on the top surface of the wafer. However, various proposals have been made regarding this grinding device.

For example, Patent Document 1 proposes a grinding apparatus that grinds a wafer to a uniform thickness by adjusting the inclination of a chuck table with respect to a grindstone.

Further, Patent Documents 2 and 3 propose a grinding device that supplies grinding fluid (cleaning fluid) toward a base that holds a plurality of grindstones arranged in an annular manner or toward the inner and outer peripheral surfaces of the grindstones. has been done.

Further, Patent Document 4 proposes a grinding device in which a nozzle for supplying a grinding liquid to a contact portion between the rotating grindstone and the wafer is disposed inside the rotating grindstone.

Japanese Patent Application Publication No. 2013-119123 Japanese Patent Application Publication No. 2010-149222 Japanese Patent Application Publication No. 2013-212555 Japanese Patent Application Publication No. 7-223152

In the grinding devices proposed in Patent Documents 2 and 3, the grinding wheel is cooled by the grinding liquid (cleaning liquid) supplied from the nozzle, but since the wafer is not directly cooled by the grinding liquid (cleaning liquid), the grinding wheel is cooled by the grinding liquid (cleaning liquid) supplied from the nozzle. There is a problem that the wafer is overheated at the processing point where it is in contact with the wafer, and the thickness of the wafer is not uniform over the entire surface. In other words, when a wafer is overheated at the processing point where the grinding wheel contacts the wafer, the overheated part thermally expands, so the amount of grinding at the processing point of the wafer becomes larger than other parts, and the grinding of the wafer The thickness of the part with a large amount becomes thinner than other parts at room temperature after grinding.

Further, in the grinding apparatus proposed in Patent Document 4, only the portion of the wafer where the grinding fluid lands is cooled. In other words, since the chuck table and the wafer held thereon are rotating during the grinding process, the point where the grinding liquid lands on the wafer is cooled in a ring shape. For this reason, the cooled ring-shaped part of the wafer shrinks due to heat, and the amount of grinding of this ring-shaped part becomes smaller than other parts, so the thickness of this part after grinding at room temperature becomes thicker than other parts. I end up.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a wafer grinding device and grinder capable of suppressing thermal deformation of the wafer due to grinding water and grinding the wafer to a uniform thickness over the entire surface. The purpose is to provide a method.

To achieve the above object, the present invention includes: a chuck table that rotates while holding a wafer on a holding surface; a grinding unit that grinds the wafer with an annular grindstone passing through the center of the wafer held on the holding surface; A wafer grinding device comprising: a grinding feeding means for raising and lowering a grinding unit; and a nozzle for spouting grinding water straight from the inside of the grindstone covering the wafer in a radial direction from the outer periphery toward the center of the wafer. The nozzle has an injection port that directs the grinding water toward the center of the wafer and lands on the outer periphery of the wafer, and the nozzle is at the height of the lower surface of the grindstone or the upper surface of the wafer held on the holding surface. A nozzle elevating means for elevating and lowering the nozzle according to the height is provided, and the grinding water spouted from the nozzle positioned by the nozzle elevating means lands on the outer peripheral portion of the wafer held on the holding surface. By applying centrifugal force to the grinding water by rotating the chuck table and directing the grinding water toward the center of the wafer, the grinding wheel is brought into contact with the wafer at the processing point. The grinding water is supplied.

The present invention also provides a wafer grinding method in which a wafer held on a holding surface of a chuck table is rotated and the wafer is ground with a rotating annular grindstone, the wafer being ground in a straight line from a nozzle toward the center of the wafer. The spouted grinding water lands on the outer periphery of the rotating wafer, and while the grinding water is moved from the outer periphery of the wafer toward the center along the top surface of the wafer, the grinding water is By applying centrifugal force to direct the grinding water along the top surface of the wafer toward the outer periphery of the wafer and moving the grinding water to the processing point where the grinding wheel contacts the wafer, the grinding water is transferred to the processing point. It is characterized by grinding the wafer while supplying it to the entire area.

According to the wafer grinding method of the present invention carried out using the grinding apparatus of the present invention, the grinding water spouted linearly in the radial direction from the nozzle toward the center of the wafer during wafer grinding is applied to the wafer. The water lands on the outer periphery of the wafer, and as it moves from the outer periphery of the wafer toward the center of the wafer, it receives centrifugal force due to the rotation of the chuck table (wafer), which causes the flow direction to change between the wafer and the grinding wheel. The processing area is the contact area of the For this reason, most of the grinding water ejected from the nozzle is supplied to the processing area of the wafer and is used to cool the processing area, and the wafer is cooled uniformly over the entire surface, and its temperature becomes uniform over the entire surface. This results in the effect that local thermal expansion due to local overheating of the wafer is prevented and the wafer is ground to a uniform thickness over the entire surface.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially cutaway perspective view of a grinding device according to a first embodiment of the present invention. FIG. 1 is a cutaway side view of main parts of the grinding device according to the first embodiment of the present invention. FIG. 3 is a plan view showing the behavior of grinding water sprayed from a nozzle toward a wafer in the grinding apparatus according to the first embodiment of the present invention. (a) is a diagram showing the radial distribution of the thickness of a wafer ground by the grinding device according to the first embodiment of the present invention, and (b) is a diagram showing the radial distribution of the thickness of the wafer ground by the conventional grinding device. FIG. FIG. 6 is a cutaway side view showing a main part of a grinding device according to a second embodiment of the present invention during a grinding process. FIG. 7 is a cutaway side view showing the main part of the grinding device according to the second embodiment of the present invention after grinding. It is a main part broken side view which shows the modification of the grinding apparatus based on 2nd Embodiment of this invention. FIG. 7 is a cutaway side view showing a main part of a grinding device according to a third embodiment of the present invention during a grinding process. It is a main part broken side view which shows the modification of the grinding apparatus based on 3rd Embodiment of this invention.

Embodiments of the present invention will be described below based on the accompanying drawings.

<First embodiment>
First, the configuration of a wafer grinding apparatus according to a first embodiment of the present invention will be described below based on FIGS. 1 and 2. In the following description, the arrow directions shown in FIG. 1 are respectively referred to as the X-axis direction (left-right direction), the Y-axis direction (front-back direction), and the Z-axis direction (vertical direction).

[Grinding device]
The grinding apparatus 1 shown in FIG. 1 grinds a disk-shaped wafer W (see FIG. 2), which is a workpiece, and includes the following components.

That is, the wafer grinding apparatus 1 includes a chuck table 10 that holds a wafer W and rotates around the center of the wafer W, a grinding unit 20 that grinds the wafer W sucked and held by the chuck table 10, and a top surface height measuring device 30 that measures the top surface height of the wafer W being processed; a grinding feeder 40 that moves the grinding unit 20 up and down in the vertical direction (Z-axis direction) with respect to the holding surface 11a of the chuck table 10; A nozzle 50 supplies grinding water to the contact area (processing area) between the grinding wheel 26b of the grinding unit 20 and the wafer W, and a nozzle 50 that follows the height of the top surface of the wafer W being grinded held on the chuck table 10. A nozzle elevating means 60 for elevating and lowering the chuck table 10, an inclination adjustment mechanism 70 for adjusting the inclination of the chuck table 10, and a horizontal movement mechanism 80 for moving the chuck table 10 in the horizontal direction (Y-axis direction) with respect to the holding surface 11a. It is provided as a component.

Here, the wafer W is made of a single-crystal silicon base material, and a plurality of devices (not shown) are formed on the surface facing downward in the state shown in FIG. , is protected by a protective tape T attached to the surface of the wafer W. The front surface (lower surface in FIG. 2) of the wafer W is suction-held on the holding surface 11a of the chuck table 10 via the protective tape T, and the back surface (upper surface in FIG. 2) is supplied with grinding water from the nozzle 50. Grinding is carried out by the grindstone 26b of the grinding unit 20 while receiving the vibration.

Next, the main components of the grinding device 1 are the chuck table 10, the grinding unit 20, the top surface height measuring device 30, the grinding feed means 40, the nozzle 50, the nozzle lifting means 60, the inclination adjustment mechanism 70, and the horizontal movement mechanism 80. The configuration of each will be explained.

(Chuck table)
The chuck table 10 is a disc-shaped member, and a disc-shaped porous member 11 made of porous ceramic or the like is incorporated in a circular recess 10a formed in the center thereof. The upper surface of the porous member 11 constitutes a holding surface 11a that sucks and holds the disk-shaped wafer W.

Here, the chuck table 10 is rotationally driven by the rotation drive mechanism 2 shown in FIG. 2 around a vertical central axis in the direction of the arrow shown (clockwise). That is, the chuck table 10 is equipped with a rotating shaft 12 that integrally extends vertically downward from its center, and this rotating shaft 12 has a pair of upper and lower bearings mounted on a ring plate-shaped flange 14 supported by a frame 13. It is rotatably supported via (ball bearing) 15. The lower end of the rotating shaft 12 is connected to a rotary joint 16, and the driven pulley 3 is connected to the rotating shaft 12.

Further, an electric motor 4 as a drive source is arranged beside the driven pulley 3, and a drive pulley 5 is connected to an output shaft 4a of the electric motor 4 that extends vertically upward. An endless timing belt 6 is wound around the driven pulley 5 and the driven pulley 3. Note that the outer diameter of the driven pulley 3 is set larger than the outer diameter of the driving pulley 5.

Further, as shown in FIG. 2, a communication path 17 is formed vertically at the axes of the chuck table 10, the rotating shaft 12, and the rotary joint 16, and the upper end of this communication path 17 is connected to the lower surface of the porous member 11. It is open to Further, the lower end of the communication passage 17 is connected to a communication passage 18 formed in the rotary joint 16 in the radial direction (lateral direction), and a pipe 19 is connected to the communication passage 18 . Three branch pipes 19a, 19b, and 19c branch from the pipe 19, and a suction source 7 such as a vacuum pump is connected to the branch pipe 19a via an on-off valve V1, and a branch pipe 19b is connected to an air supply source 8 such as an air compressor via an on-off valve V2. Further, a water supply source 9 such as a water pump is connected to the branch pipe 19c via an on-off valve V3.

Here, as shown in FIG. 1, the grinding device 1 according to the present embodiment includes a rectangular box-shaped base 100 that is long in the Y-axis direction (front-back direction), and has an opening in the Y-axis direction. The chuck table 10 faces the long rectangular opening 100a. The area around the chuck table 10 in the opening 100a is covered with a rectangular plate-shaped cover 101, and the front and rear (-Y direction and +Y direction) portions of the cover 101 in the opening 100a move together with the cover 101. They are respectively covered by bellows-shaped telescopic covers 102 and 103 that expand and contract with each other. Therefore, no matter where the chuck table 10 is located on the Y-axis, the opening 100a is always closed by the cover 101 and the telescopic covers 102, 103, preventing foreign matter from entering the base 100 from the opening 100a. Prevented.

(Grinding unit)
The grinding unit 20 includes a spindle housing 22 fixed to a holder 21, a spindle motor 23 housed in the spindle housing 22, a vertical spindle 24 rotationally driven by the spindle motor 23, and a vertical spindle 24 at the lower end of the spindle 24. It includes a disk-shaped mount 25 attached thereto, and a grinding wheel 26 detachably attached to the lower surface of the mount 25. Here, the grinding wheel 26 includes a disc-shaped base 26a and a plurality of grindstones 26b, which are processing tools attached to the lower surface of the base 26a in an annular shape. Note that the grindstone 26b is a rectangular block-shaped processing tool for grinding the wafer W, and its lower surface constitutes a grinding surface that contacts the upper surface (surface to be ground) of the wafer W.

(Top height measuring device)
The top surface height measuring device 30 measures the top surface height of the wafer W held on the chuck table 10 and is being ground. It is equipped with a contactor 32 that makes contact. Here, the top surface height of the wafer W during the grinding process is measured by one contact 31, and the top surface height of the wafer W measured by this one contact 31 and the other contact 32 are measured. The thickness of the wafer W is determined by the difference in height from the top surface of the chuck table 10.

(Grinding feed means)
The grinding feed means 40 moves the grinding unit 20 up and down along the direction (Z-axis direction) perpendicular to the holding surface 11a of the chuck table 10, and as shown in FIG. It is arranged on the end face (front face) in the -Y axis direction of a rectangular box-shaped column 41 vertically erected on the end part (rear end part) in the +Y axis direction. This grinding feed means 40 moves a rectangular plate-shaped lifting plate 42 attached to the back surface of the holder 21 along a pair of left and right guide rails 43 together with the holder 21 and the spindle 24 and grinding wheel 26 held by the holder 21. It moves up and down in the Z-axis direction. Here, the pair of left and right guide rails 43 are arranged perpendicularly to the front surface of the column 41 and parallel to each other.

Further, between the pair of left and right guide rails 43, a rotatable ball screw shaft 44 is vertically provided along the Z-axis direction (vertical direction), and the upper end of the ball screw shaft 44 is a driving source. It is connected to an electric motor 45 that can rotate in forward and reverse directions. Here, the electric motor 45 is mounted vertically via a rectangular plate-shaped bracket 46 mounted on the upper surface of the column 41. The lower end of the ball screw shaft 44 is rotatably supported by the column 41, and the ball screw shaft 44 has a nut member provided horizontally protruding backward (in the +Y-axis direction) on the back surface of the elevating plate 42. 47 (see FIG. 2) are screwed together.

Therefore, when the electric motor 45 is driven to rotate the ball screw shaft 44 in the forward and reverse directions, the elevating plate 42 to which a nut member (not shown) that is threadedly engaged with the ball screw shaft 44 is attached, moves along the pair of guide rails 43 to the grinding unit. Since the grinding unit 20 moves up and down together with the grinding wheel 20, the grinding amount of the grinding wheel 26b relative to the wafer W is set.

(nozzle)
The nozzle 50 supplies grinding water such as pure water toward the processing point (the arc-shaped processing region R shown in FIG. 3), which is the contact point between the grindstone 26b and the wafer W during the grinding process, and Grinding water is spouted from inside the grinding wheel 26b that rotates while covering the wafer W during the grinding process. More specifically, as shown in FIG. 3, the nozzle 50 is a member bent in an inverted L shape that spouts the grinding water linearly in a radial direction from the outer periphery of the wafer W toward the center. An injection port 50a (see FIG. 3) for causing water to land on the outer peripheral portion of the wafer W is open at the tip.

(Nozzle elevating means)
As shown in FIG. 2, the nozzle elevating means 60 moves the nozzle 50 up and down in the Z-axis direction (vertical direction) following the height of the upper surface of the wafer W, and as shown in FIG. It is erected in Here, the nozzle elevating means 60 includes an elevating drive section 61 that moves the nozzle 50 up and down, and controls the elevating drive section 61 in accordance with the top surface height of the wafer W measured by the top surface height measuring device 30 to raise and lower the nozzle. 50 is provided.

(Tilt adjustment mechanism)
The tilt adjustment mechanism 70 is a mechanism for adjusting the tilt of the chuck table 10, and is provided between the chuck table 10 and the flange 14 below it, as shown in FIG. Specifically, this tilt adjustment mechanism 70 is composed of two actuators 71 and one pivot (not shown), and these actuators 71 and the pivot (not shown) are arranged at equal angular pitches (120° pitches) in the circumferential direction. ).

Here, each actuator 71 moves a rod (not shown) up and down to tilt the chuck table 10 about a pivot (not shown) to adjust the inclination of the holding surface 11a with respect to the horizontal plane. Note that each actuator 71 may be provided with a vertical load measuring device such as a load cell for measuring the vertical load acting vertically on the wafer W from the grindstone 26b.

(Horizontal movement mechanism)
The horizontal movement mechanism 80 is a mechanism for moving the chuck table 10 in the horizontal direction (Y-axis direction) with respect to the holding surface 11a, and as shown in FIG. It is arranged on the internal base 81. This horizontal movement mechanism 80 includes a block-shaped slider 82, and this slider 82 moves along the Y-axis along a pair of left and right guide rails 83 that are arranged parallel to each other along the Y-axis direction (front-back direction). It is possible to slide in the direction. Therefore, the chuck table 10 supported by the slider 82 and the rotary drive mechanism 2 including the electric motor 4 shown in FIG. 2 and the like can slide together with the slider 82 along the Y-axis direction.

A rotatable ball screw shaft 84 extending in the Y-axis direction (front-back direction) is disposed between the pair of left and right guide rails 83 on the internal base 81, and one end of the ball screw shaft 84 in the Y-axis direction ( The left end in FIG. 1) is connected to an electric motor 85 that is a driving source and is capable of forward and reverse rotation. The other end of the ball screw shaft 84 in the Y-axis direction (the right end in FIG. 1) is rotatably supported by a bearing 86 erected on the internal base 81. A nut member (not shown) that protrudes downward from the slider 82 is screwed onto the ball screw shaft 84 .

Therefore, when the electric motor 85 is rotated forward and backward to rotate the ball screw shaft 84 forward and backward, a nut member (not shown) screwed onto the ball screw shaft 84 moves along the ball screw shaft 84 in the Y-axis direction (back and forth direction) together with the slider 82. Due to the sliding movement, the chuck table 10 also moves together with the slider 82 along the Y-axis direction. As a result, the wafer W held by suction on the holding surface 11a of the chuck table 10 also moves along the Y-axis direction.

[Wafer grinding method]
Next, a method of grinding a wafer W performed using the grinding apparatus 1 according to the first embodiment configured as above will be described.

When grinding the wafer W, the wafer W is placed on the holding surface 11a of the chuck table 10 with the protective tape T facing down, as shown in FIG. Then, the suction source 7 connected to the porous member 11 of the chuck table 10 is driven to vacuum the porous member 11. Specifically, when the on-off valve V1 is opened, the air in the porous member 11 is sucked by the suction source 7 through the communication paths 17 and 18, the piping 19, the branch pipe 19a, and the on-off valve V1, so that the air in the porous member 11 is sucked by the suction source 7. A negative pressure is generated, and the wafer 100 placed on the upper surface (holding surface 11a) of the porous member 11 via the protective tape T is suction-held onto the holding surface 11a by the negative pressure. Note that at this time, the other two on-off valves V2 and V3 are closed.

Here, the holding surface 11a (the upper surface of the porous member 11) of the chuck table 10 is formed into a conical surface with the rotation center axis as its apex, that is, an inclined surface that slopes downward from the rotation center axis toward the outside in the radial direction. ing. Therefore, the wafer W held by suction on the holding surface 11a of the chuck table 10 also forms a conical surface having the rotation center axis as its apex, similarly to the holding surface 11a. Note that, in reality, the inclination of this conical surface is so minute that it cannot be visually recognized with the naked eye.

In this embodiment, the horizontal lower surface (grinding surface) of the grinding wheel 26b, which rotates horizontally around a vertical central axis, is parallel to the holding surface 11a of the chuck table 10 and the upper surface (ground surface) of the wafer W. The tilt adjustment mechanism 70 adjusts the inclination so that the holding surface 11a of the chuck table 10 is inclined by a predetermined minute angle with respect to the horizontal plane (the rotation center axis of the chuck table 10 is a minute angle with respect to the vertical). be adjusted.

From the above state, the horizontal movement mechanism 80 is driven to move the chuck table 10 in the +Y-axis direction (backwards), and the wafer W, which is suctioned and held by the chuck table 10, is positioned below the grinding wheel 26 of the grinding unit 20. . That is, when the electric motor 85 is started and the ball screw shaft 84 rotates, the slider 82, to which a nut member (not shown) that is screwed onto the ball screw shaft 84 is attached, moves along the pair of left and right guide rails 83 together with the chuck table 10, etc. Since the wafer W is slid in the +Y-axis direction, the wafer W held on the holding surface 11a of the chuck table 10 is positioned below the grinding wheel 26 of the grinding unit 20. At this time, the horizontal positional relationship between the two is adjusted so that the lower surface (processing surface) of the grindstone 26b passes through the center of the wafer W.

Further, the rotation drive mechanism 2 shown in FIG. 2 is driven to rotate the chuck table 10, and the wafer W held on the holding surface 11a of the chuck table 10 is rotated at a predetermined rotation speed (for example, 1,000 rpm). 2 and 3 (clockwise in plan view), and the spindle motor 23 is driven to rotate the grinding wheel 26. That is, when the electric motor 4 is started, its rotation is decelerated from the drive pulley 5 through the timing belt 6 and the driven pulley 3, and is transmitted to the rotating shaft 12. The wafer W held therein is rotated at a predetermined speed.

As described above, while the wafer W and the grinding wheel 26 are rotating, the grinding feed means 40 is driven to lower the grinding wheel 26 in the −Z-axis direction. That is, when the electric motor 45 is driven and the ball screw shaft 44 rotates, the elevating plate 42, which is provided with a nut member (not shown) that is screwed onto the ball screw shaft 44, moves down in the −Z-axis direction together with the grinding wheel 26 and the like. Then, the lower surface (processed surface) of the grindstone 26b of the grinding wheel 26 comes into contact with the upper surface (back surface) of the wafer W. In this way, when the grinding wheel 26 is further lowered by a predetermined amount in the −Z-axis direction from the state where the lower surface of the grinding wheel 26b is in contact with the upper surface of the wafer W, the upper surface of the wafer W is ground by the grinding wheel 26b by a predetermined amount. be done.

While the wafer W is being ground as described above, as shown in FIGS. 2 and 3, grinding water is injected from the injection port 50a of the nozzle 50 in a straight line in the radial direction from the outer periphery of the wafer W toward the center. However, this grinding water lands on the outer peripheral portion of the wafer W. Then, the grinding water flows from the outer periphery of the upper surface of the wafer W toward the center of the wafer W, and is subjected to centrifugal force by the rotation of the chuck table 10 (wafer W), causing its flow to flow as shown by the arrow in FIG. The direction is changed to the direction of the processing region R, which is the contact area between the wafer W and the grindstone 26b, and most of the grinding water jetted from the nozzle 50 is supplied to the processing region R and is used for cooling the processing region R. .

Here, to specifically explain the principle of the above action, for example, at point P in FIG. 3, the grinding water is subjected to the downward inertial force _F1 in _FIG. act. Therefore, the resultant force _F0 in the right direction (direction toward the machining area R) in Fig. 3, which is a vector combination of the inertial force _F1 and the centrifugal force _F2 , acts on the grinding water. , will head towards the processing area R.

As described above, when most of the grinding water is efficiently supplied to the processing region R, the processing heat generated by grinding the wafer W by the grindstone 26b in the processing region R is effectively removed by the grinding water, and the wafer W is uniformly cooled over the entire surface. Therefore, local overheating of the wafer W is prevented, and the temperature of the wafer W becomes uniform over the entire surface. As a result, local thermal expansion due to local overheating of the wafer W is prevented, and the wafer W is ground to a uniform thickness over the entire surface.

Here, the radial thickness distribution obtained by actually measuring the thickness of the wafer W is shown in FIG. FIG. 4(a) shows the radial distribution of the thickness of a wafer W ground by the method of the present invention using the wafer grinding apparatus 1 according to the present invention. It can be seen that the thickness is almost uniform with no large variations.

On the other hand, Fig. 4(b) shows the radial thickness distribution of a wafer ground by a conventional grinding method using a conventional grinding device; It can be seen that relatively large variations occur. Note that the conventional wafer grinding method employs a method in which grinding water lands on the center of the wafer to cool the processing area of the wafer.

By the way, as described above, when grinding the wafer W while supplying grinding water from the nozzle 50 to the processing area R of the wafer W, the grinding wheel 26b is lowered by the grinding feeding means 40, so that the wafer W has a predetermined thickness. At this time, the height position of the nozzle 50 follows the change in the thickness of the wafer W (that is, the change in the top surface height position of the wafer W). It is adjusted by a lifting means 60.

That is, the control unit 62 shown in FIG. Make it follow the position. As a result, the position at which the grinding water ejected from the injection port 50a of the nozzle 50 lands on the wafer W remains constant regardless of changes in the thickness of the wafer W, and the above effect can be stably obtained.

As described above, according to the method of cleaning a wafer W performed using the grinding apparatus 1 according to the present embodiment, during the grinding of the wafer W, a straight line from the nozzle 50 toward the center of the wafer W is applied. The injected grinding water lands on the outer periphery of the wafer W, and in the process of the landed grinding water moving from the outer periphery of the wafer W toward the center of the wafer W, centrifugal force is generated by the rotation of the chuck table 10 (wafer W). As a result, as shown in FIG. 3, the flow direction is changed to the processing region R, which is the contact area between the wafer W and the grindstone 26b. Therefore, most of the grinding water ejected from the nozzle 50 is supplied to the processing area R of the wafer W and is used to cool the processing area R, so that the entire surface of the wafer W is uniformly cooled and its temperature is maintained evenly over the entire surface. This results in the effect that the wafer W is ground to a uniform thickness over the entire surface, thereby preventing local thermal expansion due to local overheating of the wafer W.

<Second embodiment>
Next, a grinding device according to a second embodiment of the present invention will be described below based on FIGS. 5 and 6.

The basic configuration of the wafer grinding apparatus 1A according to this embodiment is the same as the basic configuration of the grinding apparatus 1 according to the first embodiment, so in FIGS. 5 and 6, the same as that shown in FIG. The same reference numerals are given to the elements, and their explanation will be omitted below.

In the wafer grinding apparatus 1A according to the present embodiment, the configuration of the nozzle elevating means 60A is different from that of the nozzle elevating means 60 according to the first embodiment. Therefore, only the configuration and operation of the nozzle elevating means 60A will be described below.

The nozzle elevating means 60A is fixed to the frame 13, and includes an air cylinder 63 and a piston 64 mounted in the air cylinder 63 so as to be movable up and down, as urging means for urging the nozzle 50 in the upward direction. a piston rod 65 that extends vertically upward from the piston 64 through the air cylinder 63; an air supply source 66 such as an air compressor that supplies compressed air into the air cylinder 63; and the air supply source 66 and the air cylinder. A regulator 68 is provided on an air pipe 67 that connects the air pipe 63 to the air pipe 63.

Here, the inside of the air cylinder 63 is divided into an upper chamber S1 and a lower chamber S2 by a piston 64, and an air pipe 67 is connected to the lower chamber S2. A nozzle 50 that injects grinding water toward the wafer W is attached to the upper end of the piston rod 65.

Further, the nozzle elevating means 60A includes a pressing part 69 vertically attached to the lower surface of the holder 21 of the grinding unit 20, and as shown in FIG. 5, when the wafer W is being ground by the grindstone 26b, Compressed air is supplied to the lower chamber S2 of the air cylinder 63 from an air supply source 66 via an air pipe 67. Therefore, the piston 64, the piston rod 65, and the nozzle 50 are urged upward by the air pressure acting on the lower surface of the piston 64. The nozzle 50 attached thereto is pressed downward (in the opposite direction).

Therefore, as shown in FIG. 5, when the wafer W is being ground by the grindstone 26b, the nozzle 50 is positioned at a height where the grinding water ejected from the injection port 50a lands on the outer periphery of the wafer W. However, as the grinding of the wafer W progresses and the grindstone 26b descends, the nozzle 50 moves downward following the descending movement of the grindstone 26b, and its height position changes depending on the change in the thickness of the wafer W (i.e., The height position of the nozzle 50 is adjusted by the nozzle elevating means 60A so as to follow the lower surface height position of the grindstone 26b. As a result, the position at which the grinding water ejected from the injection port 50a of the nozzle 50 lands on the wafer W remains constant regardless of changes in the thickness of the wafer W (changes in the height of the lower surface of the grinding wheel 26b), and the processing area R This enables a stable supply of grinding water to.

When the grinding of the wafer W is finished and the grinding unit 20 is raised as shown in FIG. Since it is separated from the rod 65, the piston 64, the piston rod 65, and the nozzle 50 rise to the upper limit position, and in this state, for example, the grindstone 26b can be replaced with a new one.

In addition, in the wafer grinding apparatus 1A equipped with the nozzle elevating means 60A as described above, the wafer W is ground by the same method as in the first embodiment, and the same effects as described above are obtained. A further explanation of the method of grinding the wafer W using the grinding method will be omitted.

By the way, the nozzle elevating means 60A described above includes an air supply source 66, an air pipe 67, and a regulator 68 in addition to the air cylinder 63, piston 64, and piston rod 65 as urging means for urging the nozzle 50 in the upward direction. However, as shown in FIG. 7, if a coil spring 90 as one of the biasing means is compressed into the lower chamber S2 of the air cylinder 63, the air supply source 66, air piping 67, and regulator 68 can be connected. This becomes unnecessary, and it is possible to simplify the structure and reduce the cost of the nozzle elevating means 60A.

<Third embodiment>
Next, a grinding device according to a third embodiment of the present invention will be described below based on FIG. 8.

The basic configuration of the wafer grinding apparatus 1B according to this embodiment is also the same as the basic configuration of the grinding apparatus 1 according to the first embodiment, so in FIG. 8, the same elements as shown in FIG. They are designated by the same reference numerals and will not be described again hereinafter.

In the grinding device 1B according to the present embodiment, the configuration of the nozzle elevating means 60B is different from that of the nozzle elevating means 60, 60A according to the first and second embodiments. Therefore, only the configuration and operation of the nozzle elevating means 60B will be described below.

The nozzle elevating means 60B is fixed to the flange 14, and serves as a biasing means for urging the nozzle 50 in the upward direction.Like the nozzle elevating means 1A according to the second embodiment, the nozzle elevating means 60B includes an air cylinder 63 and an air cylinder 63. A piston 64 is installed in the air cylinder 63 so as to be able to move up and down, a nozzle 50 that also serves as a piston rod extends vertically upward from the piston 64 through the air cylinder 63, and supplies compressed air into the air cylinder 63. It includes an air supply source 66 such as an air compressor, and a regulator 68 provided in an air pipe 67 that connects the air supply source 66 and the air cylinder 63. Here, the inside of the air cylinder 63 is divided into an upper chamber S1 and a lower chamber S2 by a piston 64, and an air pipe 67 is connected to the lower chamber S2.

Further, the nozzle elevating means 60B includes a cylindrical pressing part 91 provided at the center of the lower surface of the grinding wheel 26, and a hemispherical pivot 91a protruding from the center of the lower surface of this pressing part 91 moves the nozzle. 50 (point contact).
In the nozzle elevating means 60B configured as described above, as shown in FIG. Compressed air is supplied via piping 67. Therefore, the piston 64 and the nozzle 50 are urged upward by air pressure acting on the lower surface of the piston 64, and the pivot 91a of the pressing part 91 comes into contact with the tip of the nozzle 50, pushing the nozzle 50. It is pressed downward (in the opposite direction).

Therefore, as shown in FIG. 8, when the wafer W is being ground by the grindstone 26b, the nozzle 50 is positioned at a height where the grinding water ejected from the injection port 50a lands on the outer periphery of the wafer W. However, as the grinding of the wafer W progresses and the grindstone 26b descends, the nozzle 50 moves downward following the descending movement of the grindstone 26b, and its height position changes depending on the change in the thickness of the wafer W (i.e., The height position of the nozzle 50 is adjusted by the nozzle elevating means 60B so as to follow the change in the height position of the lower surface of the grindstone 26b. As a result, the position at which the grinding water ejected from the injection port 50a of the nozzle 50 lands on the wafer W remains constant regardless of changes in the thickness of the wafer W (changes in the height of the lower surface of the grinding wheel), and the wafer W due to the grinding water Stable supply to the processing area R (see FIG. 3) becomes possible.

Although not shown, when the grinding of the wafer W is finished and the grinding unit 20 is raised by the grinding feed means 40, the pressing part 91 attached to the base 26a of the grinding wheel 26 also rises integrally with the nozzle 50. Since they are separated, the piston 64 and the nozzle 50 rise to the upper limit position, and in this state, for example, the grindstone 26b can be replaced with a new one.

In addition, in the wafer grinding apparatus 1B equipped with the nozzle elevating means 60B as described above, the wafer W is ground by the same method as in the first embodiment, and the same effects as described above are obtained. A further explanation of the method of grinding the wafer W using 1B will be omitted.

By the way, the nozzle elevating mechanism 60B described above includes, in addition to the air cylinder 63 and the piston 64, an air supply source 66, an air pipe 67, and a regulator 68 as urging means for urging the nozzle 50 in the upward direction. However, as shown in FIG. 9, if a coil spring 90 as one of the biasing means is compressed into the lower chamber S2 of the air cylinder 63, the air supply source 66, air piping 67, and regulator 68 are unnecessary, and the nozzle The structure of the lifting means 60B can be simplified and costs can be reduced.

Note that the grinding apparatuses 1, 1A, and 1B described above employ an infeed grinding method, but the present invention relates to a grinding apparatus that employs a creep feed grinding method and a wafer grinding method using the same. In addition, the present invention is not limited in application to the embodiments described above, but is within the scope of the technical idea described in the claims, specification, and drawings. Of course, various modifications are possible.

1A, 1B: Grinding device, 2: Rotation drive mechanism, 3: Driven pulley, 4: Electric motor,
4a: Output shaft of electric motor, 5: Drive pulley, 6: Timing belt, 7: Suction source,
8: air supply source, 9: water supply source, 10 chuck table, 10a: recess,
11: Porous member, 11a: Holding surface, 12: Rotating shaft, 13: Frame,
14: flange, 15: bearing, 16: rotary joint, 17, 18: communication path,
19: Piping, 19a, 19b, 19c: Branch pipe, 20: Grinding unit, 21: Holder,
22: spindle housing, 23: spindle motor, 24: spindle,
25: Mount, 26: Grinding wheel, 26a: Base, 26b: Grinding wheel,
30: Top surface height measuring device, 31, 32: Contactor, 40: Grinding feed means, 41: Column,
42: Elevating plate, 43: Guide rail, 44: Ball screw shaft, 45: Electric motor,
46: bracket, 47: nut member, 50: nozzle, 50a: injection port,
60, 60A, 60B: nozzle elevating means, 61: elevating drive section, 62: control section,
63: Air cylinder, 64: Piston, 65: Piston rod, 66: Air supply source,
67: Air piping, 68: Regulator, 69: Pressing part, 70: Tilt adjustment mechanism,
71: Actuator, 80: Horizontal movement mechanism, 81: Internal base, 82: Slider,
83: Guide rail, 84: Ball screw shaft, 85: Electric motor, 86: Bearing,
90: coil spring, 91: pressing part, 91a: pivot, 100: base,
100a: opening, 101: cover, 102, 103: telescopic cover, R: processing area,
S1: Upper chamber, S2: Lower chamber, T: Protective tape, V1 to V3: Open/close valve, W: Wafer

Claims (4)

A chuck table that holds and rotates a wafer on a holding surface, a grinding unit that grinds the wafer with an annular grindstone passing through the center of the wafer held on the holding surface, a grinding feeder that moves the grinding unit up and down; A wafer grinding device comprising: a nozzle that ejects grinding water linearly from the inside of the grindstone covering the wafer in a radial direction from the outer periphery toward the center of the wafer,
The nozzle has an injection port that causes the grinding water to land on the outer peripheral portion of the wafer so as to direct the water toward the center of the wafer,
comprising a nozzle raising and lowering means for raising and lowering the nozzle in accordance with the height of the lower surface of the grindstone or the height of the upper surface of the wafer held on the holding surface;
The grinding water spouted from the nozzle positioned by the nozzle elevating means is directed to the center of the wafer by landing on the outer peripheral portion of the wafer held on the holding surface, while rotating the chuck table. A wafer grinding device that supplies the grinding water to a processing point where the grindstone contacts the wafer by applying centrifugal force to the grinding water and directing the grinding water toward the outer periphery of the wafer. The nozzle raising/lowering means includes a biasing means for biasing the nozzle in an upward direction, and a pressing part provided on the grinding unit to press the nozzle in a counter-biasing direction, and the grinding unit is controlled by the grinding feeding means. 2. The wafer grinding apparatus according to claim 1, wherein the nozzle is positioned corresponding to the lower surface of the grindstone by causing the nozzle to follow the downward movement of the grindstone. comprising a top surface height measuring device for measuring the top surface height of the wafer held on the holding surface;
The nozzle elevating means includes an elevating drive section that moves the nozzle up and down, and a control section that controls the elevating drive section and positions the nozzle in accordance with the top surface height of the wafer measured by the top surface height measuring device. A wafer grinding apparatus according to claim 1. A wafer grinding method that rotates a wafer held on a holding surface of a chuck table and grinds the wafer with a rotating annular grindstone, the method comprising:
Grinding water that is ejected linearly from a nozzle toward the center of the wafer lands on the outer periphery of the rotating wafer, and the grinding water is moved from the outer periphery of the wafer toward the center along the top surface of the wafer. At the same time, by rotating the chuck table, a centrifugal force is applied to the grinding water to direct the grinding water toward the outer circumference of the wafer along the upper surface of the wafer, and move the grinding water to the processing point where the grinding wheel contacts the wafer. A wafer grinding method, wherein the wafer is ground while supplying the grinding water to the entire area of the processing point.

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