JP4051119B2 - Cutting equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for preventing a displacement of a working element due to expansion and contraction of a support member due to a heat change, and a cutting apparatus that enables precise cutting by applying the method.
[0002]
[Prior art]
For example, in the cutting apparatus 50 shown in FIG. 4, when a workpiece, for example, a semiconductor wafer W is to be cut, the semiconductor wafer W is held by the frame F via the holding tape T and held by the chuck table 34. The
[0003]
Then, the chuck table 34 moves in the X-axis direction and is positioned immediately below the alignment means 51. After the cutting area is detected by the processing such as pattern matching and the alignment is performed, the chuck table 34 is further moved in the X-axis direction. Cutting is performed by moving and receiving the action of the cutting means 52.
[0004]
As shown in FIG. 5, the cutting means 52 has a circular blade 53 as an action element for cutting the workpiece held on the chuck table 34, and a rotation provided with the circular blade 53 at the tip and a thrust plate 53a. A spindle 54, a motor unit 55 serving as a driving source for the rotation of the rotary spindle 54, and a spindle housing 58 that supports the rotary spindle 54 by thrust bearings 56a and 56b and a radial bearing 57 are generally configured. Then, the rotation spindle 54 is rotated by the rotation of the rotor 59 constituting the motor unit 55, and the circular blade 53 attached to the rotation spindle 54 is rotated accordingly.
[0005]
The rotary spindle 54 has a certain distance in a non-contact state with the spindle housing 58 by air blown from the thrust bearings 56a and 56b toward the thrust plate 53a and air blown from the radial bearing 57 toward the axis of the rotary spindle 54. It is supported rotatably while keeping.
[0006]
At the time of cutting, the rotary spindle 54 is driven and rotated by the motor unit 55, the entire cutting means 52 moves in the Y-axis direction and the Z-axis direction, and the chuck table 34 moves in the X-axis direction. The semiconductor wafer W held on the chuck table 34 is cut by the circular blade 53 that rotates at high speed.
[0007]
With the recent miniaturization of chips, the demand for cutting accuracy has become stricter and the movement accuracy of the cutting apparatus has been improved. However, the rotary spindle 54 expands and contracts due to the heat generated by the rotation of the rotary spindle 54, and the circular blade There may be a shift in the position 53. Such misalignment causes a cutting error, and cannot be ignored particularly in recent years when the demand for cutting accuracy is severe. For example, when cutting is performed by applying a circular blade having a thickness of about 15 μm to the center of a street having a width of about 50 μm formed on the surface of a semiconductor wafer, the rotary spindle expands and contracts by about 20 μm due to heat, and the position of the circular blade is Similarly, if it is displaced by about 20 μm, a portion other than the street is cut and the chip is damaged.
[0008]
Therefore, by using a material having a small linear expansion coefficient for the spindle housing 58 including the thrust bearings 56a and 56b and the radial bearing 57, or by keeping the temperature around the rotating spindle 54 constant, the thermal fluctuation of the rotating spindle 54 is caused. Various measures have been taken to reduce the expansion and contraction.
[0009]
[Problems to be solved by the invention]
However, a material having a small coefficient of linear expansion is generally expensive, and a dedicated device is required to keep the temperature around the rotary spindle 54 constant, which is expensive. There is a problem in terms of sex.
[0010]
Therefore, the position of the working element is prevented from being displaced even if there is a thermal fluctuation to prevent the displacement of the working element, and in particular, the position of the circular blade is kept constant without being affected by the expansion and contraction of the rotary spindle in the cutting device. There is a problem in realizing this by an economical method.
[0011]
[Means for Solving the Problems]
As specific means for solving the above-mentioned problems, the present invention includes at least a chuck table for holding a workpiece and a cutting means for cutting the workpiece held on the chuck table, At least a circular blade for cutting a workpiece, a rotary spindle having a thrust plate for supporting the circular blade, a thrust bearing for supporting the thrust plate at a constant distance between the thrust plate and A spindle housing that supports the rotary spindle by a radial bearing, and a spindle mounting portion that fixes the spindle housing to the cutting device, and is thermally expanded in a direction opposite to the thermal expansion direction of the rotary spindle. Expansion / contraction canceling member with linear expansion coefficient M for moving the rotating spindle in the opposite direction When the linear expansion coefficient of the rotating spindle is K and the distance from the circular blade to the mounting position of the expansion / contraction canceling member and the spindle housing is L, the thickness of the expansion / contraction canceling member is ( and K × L / M), when the rotating spindle is thermally expanded is moving the circular blade by the elastic offset member moves the thrust plate the reflected pairs direction as much by thermal expansion in the reflected pairs direction A cutting device is provided.
[ 0012 ]
Then, among the thrust bearings of the spindle housing, an expansion / contraction canceling member is interposed between the thrust bearing near the circular blade and the thrust plate of the rotating spindle, and the spindle housing is fixed to the spindle mounting portion. An additional requirement is that an expansion / contraction canceling member is interposed between the spindle mounting portion and the spindle housing.
[ 0013 ]
According to such a cutting apparatus, the thermal expansion of the rotary spindle is canceled by the movement of the rotary spindle in the opposite direction accompanying the thermal expansion of the expansion and contraction canceling member, and the position of the circular blade is kept constant.
[ 0014 ]
DETAILED DESCRIPTION OF THE INVENTION
As an embodiment of the present invention, a case where the working element position shift prevention method according to the present invention is applied to a cutting apparatus 10 will be described as an example. In addition, in order to make an understanding easy, suppose that the same code | symbol is attached | subjected and demonstrated about the site | part common to the conventional cutting device.
[ 0015 ]
FIG. 1 shows a structure of a region where cutting is actually performed in a cutting apparatus 10 to which the present invention is applied. In a support portion 11 that can move within a required range in the Y-axis direction, the cutting means 12 is a Z-axis. The structure is supported so as to be movable in the direction.
[ 0016 ]
The support portion 11 has a configuration in which a wall body 14 is provided upright from an end portion of a base 13 that is horizontally disposed, and a first ball screw 15 that is disposed in the Y-axis direction is a first one. By being driven by the pulse motor 16 and rotating, the required range can be moved in the Y-axis direction. The movement of the support portion 11 in the Y-axis direction is precisely controlled based on the reading value of the first linear scale 17.
[ 0017 ]
Further, the cutting means 12 has a required range in the Z-axis direction when the second ball screw 18 disposed in the Z-axis direction on the inner surface of the wall body 14 is driven and rotated by the second pulse motor 19. It is movable. The movement of the cutting means 12 in the Z-axis direction is precisely controlled based on the reading value of the second linear scale 20.
[ 0018 ]
As shown in FIG. 2, the cutting means 12 is a circular blade 21 that is an action element that performs actual cutting, a rotary spindle 22 that attaches and supports the circular blade 21 at the tip, and a drive source of the rotary spindle 22. The motor unit 23 includes a spindle housing 27 that rotatably supports a rotating spindle by thrust bearings 24 and 25 and a radial bearing 26, and a spindle mounting portion 28 that is a fixing portion for fixing the spindle housing 27. The rotating spindle 22 and the spindle housing 27 constitute a spindle portion that is a support portion.
[ 0019 ]
The rotary spindle 22 is formed of a material having a relatively small linear expansion coefficient, and is fitted to the rotor 29 of the motor unit 23 made of, for example, a synchronous motor, and the rotary spindle 22 rotates as the rotor 29 rotates. Accordingly, the circular blade 21 attached to the rotary spindle 22 is configured to rotate. A disc-shaped thrust plate 30 is formed at the end of the rotary spindle 22 on the motor unit 23 side.
[ 0020 ]
The spindle housing 27 accommodates the motor unit 23 inside, and has thrust bearings 24 and 25 projecting inward from the inner wall, and the air is blown out from the thrust bearings 24 and 25 toward the thrust plate 30. The thrust plate 30 is supported with a constant distance between them, and the position of the rotary spindle 22 in the Y-axis direction is kept constant.
[ 0021 ]
The material forming the thrust bearing 25 is the same as that of the prior art, and the thrust bearing 24 is formed of a material having a large linear expansion coefficient unlike the conventional one.
[ 0022 ]
Further, the spindle housing 27 rotates in the X-axis direction and the Z-axis direction while maintaining a certain distance from the rotary spindle 22 by the air blown from the radial bearing 26 provided on the inner periphery toward the axis of the rotary spindle 22. The spindle 22 is rotatably supported.
[ 0023 ]
A protruding portion 31 protrudes at a substantially intermediate position on the outer periphery of the spindle housing 27, and the mounting surface 32 of the protruding portion 31 and the end of the spindle mounting portion 28 are fixed to each other. The spindle housing 27 and the spindle mounting portion 28 are fixed by engaging the outer periphery located closer to the motor unit 23 than the inner periphery of the spindle mounting portion 28 having a U-shaped cross section. . One side of the thrust bearing 24 is fixed to the mounting surface 32.
[ 0024 ]
A workpiece 33 to be cut is held by a chuck table 34, driven by a third pulse motor 35, guided by a pair of rails 36a and 36b, and moved in the X-axis direction to thereby move the circular blade 21. Is affected.
[ 0025 ]
In the cutting apparatus 10 configured as described above, the workpiece 33 is placed on the chuck table 34, alignment is performed in the same manner as in the prior art to detect the cutting position, and then the Y of the circular blade 21 is placed at the cutting position. While aligning the position in the axial direction, the cutting means 12 is lowered, and the chuck table 34 is further moved in the X-axis direction, whereby the workpiece 33 is cut by the action of the rotating circular blade 21.
[ 0026 ]
Positioning of the circular blade 21 in the Y-axis direction is performed by being driven by the first pulse motor 16 to rotate the first ball screw 15 and moving the support portion 11 in the Y-axis direction accordingly. On the other hand, alignment in the Z-axis direction is performed by driving the second pulse motor 19 to rotate the second ball screw 18 and moving the cutting means 12 in the Z-axis direction.
[ 0027 ]
The circular blade 21 is rotated by the rotation of the rotary spindle 22 driven by the motor unit 23. Here, the position of the rotary spindle 22 in the Y-axis direction is kept constant in the spindle housing 27 by the thrust bearings 24 and 25, and the positions in the X-axis direction and the Z-axis direction are also kept constant by the radial bearing 26. However, the rotary spindle 22 may expand in the Y-axis direction due to thermal fluctuation caused by rotation.
[ 0028 ]
When the rotary spindle 22 expands, the circular blade 21 attached to the tip of the rotary spindle 22 is also displaced. Therefore, if cutting is performed as it is, an error occurs in the cutting position. Therefore, in the present invention, the thrust bearing 24, which is one of the thrust bearings supporting the Y-axis direction, is made of a material having a linear expansion coefficient larger than that of the rotating spindle 22, thereby preventing the circular blade 21 from being displaced. Like to do. Specifically, misalignment is prevented as follows.
[ 0029 ]
For example, when the rotary spindle 22 formed of a material having a relatively small linear expansion coefficient expands in the + Y direction, the thrust bearing 24 having a large linear expansion coefficient also expands in the −Y direction. Here, even when the thrust bearing 24 expands, the distance from the thrust plate 30 is kept constant by the air blown out, so that the thrust plate 30 also expands in the direction in which the thrust bearing 24 expands by the amount that the thrust bearing 24 expands. It moves in the same direction, that is, the direction opposite to the expansion direction of the rotary spindle 22, and the circular blade 21 mounted on the rotary spindle 22 including the thrust plate 30 also moves in the same direction. That is, the thrust bearing 24 is moved in the opposite direction to the rotary spindle 22 by the amount of expansion of the rotary spindle 22, and functions as an expansion / contraction canceling member. However, in order to make the expansion amount in the + Y direction of the rotary spindle 22 equal to the expansion amount in the -Y direction of the thrust bearing 24 to completely cancel the deviation, the thickness T of the thrust bearing 24 is set as follows. There is a need to.
[ 0030 ]
As shown in FIG. 2, the length from the attachment surface 32 of the thrust bearing 24 to the circular blade 21 is L, the linear expansion coefficient of the rotary spindle 22 is K, the linear expansion coefficient of the members constituting the thrust bearing 24 is M, and the thrust When the thickness of the bearing 24 is T, the expansion amount of the rotary spindle 22 can be expressed as (K × L), and the expansion amount of the thrust bearing 24 can be expressed as (T × M). Here, if the relationship of (K × L = T × M) is established, the expansion of the rotary spindle 22 is completely offset by the expansion of the thrust bearing 24. Therefore, the thickness T of the thrust bearing 24 may be set so that the relationship (T = K × L / M) is established.
[ 0031 ]
In addition, the movement of the thrust plate 30 due to the thermal expansion of the thrust bearing 24 can be allowed by setting the gap between the thrust bearing 25 and the thrust plate 30 to be slightly larger, for example, about 25 μm. The rotor 29 is configured to absorb some expansion and contraction.
[ 0032 ]
Next, as a second embodiment, a case where an expansion / contraction canceling member is provided separately from the thrust bearing as shown in FIG. 3 will be described. In addition, about the site | part which is common in 1st embodiment, the same code | symbol is attached | subjected and demonstrated.
[ 0033 ]
The spindle attachment portion 41 in FIG. 3 is different in shape from the spindle attachment portion 28 described in the first embodiment, and the inside thereof is more than the spindle attachment portion 28 shown in the first embodiment. A large hollow portion 43 is formed, and a fixing portion 44 for fixing the expansion and contraction canceling member 40 is provided at the tip of the U-shape. The protruding portion 31 of the spindle housing 27 is attached via the expansion / contraction canceling member 40 fixed to the fixing portion 44, and the spindle mounting portion 41 and the spindle housing 27 are formed only by the expansion / contraction canceling member 40. They are connected and are in a non-contact state in other parts.
[ 0034 ]
The thrust bearings 25a and 25b of the spindle housing 27 are both made of a material having a relatively small linear expansion coefficient.
[ 0035 ]
For example, when the rotary spindle 22 expands in the + Y direction due to thermal fluctuation and the circular blade 21 is displaced in the + Y direction, the expansion / contraction canceling member 40 expands in the −Y direction and moves the spindle housing 27 in the −Y direction. . Since the distance between the thrust bearings 25a, 25b and the thrust plate 30 is always kept constant, if the spindle housing 27 moves in the -Y direction, the rotary spindle 22 also moves by the same amount in the -Y direction. Become.
[ 0036 ]
In this case, in order to completely cancel the expansion / contraction of the rotary spindle 22 by the expansion / contraction canceling member 40, the relational expression (T = K × L / M) may be satisfied as in the first embodiment. . Here, T is the thickness of the expansion / contraction cancellation member 40, M is the linear expansion coefficient of the expansion / contraction cancellation member 40, and K is the linear expansion coefficient of the rotary spindle 22. In this case, L is the spindle mounting portion 41 and the expansion / contraction cancellation member. 40 is a distance from the fixed surface 42 to which the circular blade 21 is fixed.
[ 0037 ]
In the present embodiment, the case where the present invention is applied to a cutting apparatus has been described as an example. However, the present invention is not limited to this and can be applied to various apparatuses in which positional deviation occurs due to thermal fluctuations. is there.
[ 0038 ]
【The invention's effect】
As described above, according to the method for preventing the displacement of the working element according to the present invention, the thermal expansion of the support part is canceled by the movement of the support part in the opposite direction accompanying the thermal expansion of the expansion / contraction canceling member, Since the position of the device is kept constant and is not affected by heat, there is no error in the operation of the working element in the apparatus to which this method is applied, and operations such as production and processing can be performed precisely.
[ 0039 ]
Further, according to the cutting device of the present invention, the thermal expansion of the rotary spindle is canceled by the movement of the rotary spindle in the opposite direction accompanying the thermal expansion of the expansion / contraction canceling member, so that the position of the circular blade is kept constant. Precise cutting can be performed, and the quality of semiconductor chips and the like can be improved. Furthermore, since it is not necessary to use a material having a small linear expansion coefficient for the rotary spindle and the spindle housing, a general steel material such as stainless steel can be used, which is excellent in terms of economy.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing the structure of a cutting apparatus which is an example of an apparatus to which a misregistration prevention method according to the present invention is applied.
FIG. 2 is an explanatory view showing a first embodiment of a configuration of cutting means of the cutting apparatus.
FIG. 3 is an explanatory view showing a second embodiment of the configuration of the cutting means of the cutting apparatus.
FIG. 4 is a perspective view showing a conventional cutting apparatus.
FIG. 5 is an explanatory view showing a configuration of cutting means of the cutting apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Cutting device 11 ... Supporting part 12 ... Cutting means 13 ... Base 14 ... Wall 15 ... First ball screw 16 ... First pulse motor 17 ... First linear scale 18 ... ... Second ball screw 19 ... Second pulse motor 20 ... Second linear scale 21 ... Circular blade 22 ... Rotary spindle 23 ... Motor unit 24 ... Thrust bearing (extension / contraction canceling member) 25 ... Thrust Bearing 26... Radial bearing 27... Spindle housing 28... Spindle mounting portion 29... Rotor 30... Thrust plate 31 .. Projection portion 32 .. Mounting surface 33. Third pulse motors 36a, 36b ... rail 40 ... expansion and contraction canceling member 41 ... spindle mounting portion 42 ... fixing surface 43 ... empty Part 44 ...... Adhering part 50 ...... Cutting device 51 ...... Alignment means 52 ...... Cutting means 53 ...... Circular blade 53 a …… Thrust plate 54 …… Rotary spindle 55 …… Motor parts 56 a, 56 b …… Thrust bearing 57 …… ... Radial bearings 58 …… Spindle housing 59 …… Rotor

Claims (3)

At least a chuck table for holding the workpiece and a cutting means for cutting the workpiece held on the chuck table, the cutting means including at least a circular blade for cutting the workpiece and a thrust plate a rotating spindle which supports the circular blade has a spindle housing supporting the rotary spindle by a thrust bearing and a radial bearing for supporting the thrust plate while keeping a constant distance between the thrust plate, the spindle A spindle mounting portion for fixing the housing to the cutting device, and the coefficient of linear expansion for moving the rotating spindle in the opposite direction by thermal expansion in the direction opposite to the direction of thermal expansion of the rotating spindle is M. An expansion / contraction canceling member is attached to the spindle housing, and the rotating spindle is Where the linear expansion coefficient is K, and the distance from the circular blade to the attachment position of the expansion / contraction canceling member and the spindle housing is L, the thickness of the expansion / contraction canceling member is (K × L / M), When the rotary spindle is thermally expanded, the expansion and contraction canceling member is thermally expanded in the opposite direction by the same amount, and the circular blade is moved by moving the thrust plate in the opposite direction. 2. The cutting apparatus according to claim 1 , wherein an expansion / contraction canceling member is interposed between a thrust bearing of the spindle housing close to the circular blade and a thrust plate of the rotary spindle. 2. The cutting apparatus according to claim 1 , wherein the spindle housing is fixed to the spindle mounting portion, and an expansion / contraction canceling member is interposed between the spindle mounting portion and the spindle housing.

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