JPH06278127A - Slicing machine - Google Patents

Abstract

(57) [Summary] [Purpose] To adjust the flatness of the work cut surface with high accuracy. [Structure] A central electromagnet 24 facing the inner peripheral portion of the blade 8 with a wafer Wf cut out from a work W interposed therebetween.
And left and right electromagnets 34 and 36 facing the inner circumference of the blade on both sides thereof. Each electromagnet 24, 34, 3
The blade inner peripheral side of 6 faces the inner peripheral edge of the blade, and the center, left and right blade position detection sensors 30, 3
8, 40 are arranged. Furthermore, each sensor 30, 3
The signals from 8 and 40 are arithmetically processed using the stiffness matrix obtained in advance, and the electromagnets 24 and 3 are calculated based on the arithmetic results.
Control means is provided for adjusting the amount of current supplied to 4, 36.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slicing machine used for cutting a wafer from a work such as a semiconductor single crystal rod.

[0002]

2. Description of the Related Art In a slicing machine used for cutting a wafer from a single crystal rod of silicon or the like, a change in flatness of an inner peripheral blade during cutting has a great influence on the flatness of the wafer. It has been attempted to constantly monitor the displacement of the inner peripheral blade in the thickness direction and proceed with the cutting while correcting the position of the blade in the thickness direction according to the displacement.

An example of a slicing machine equipped with such an inner peripheral blade correcting means is, for example, Japanese Patent Laid-Open No. 3-1.
As described in Japanese Patent No. 21769, a displacement detection sensor for measuring displacement of an inner peripheral blade in a thickness direction, at least a pair of electromagnets arranged so as to sandwich the inner peripheral blade, and the displacement detection sensor. And a magnetic force adjusting means for adjusting the magnetic force generated by the electromagnet based on the output signal of the electromagnet, and increases the magnetic force of the electromagnet on the side away from the blade surface according to the amount of displacement of the blade in the thickness direction detected by the displacement detection sensor. Thus, there is provided a blade which pulls the blade to cancel the displacement in the thickness direction.

[0004]

By the way, in the conventional slicing machine described above, one of the position before the inner peripheral blade is cut into the silicon single crystal rod and the position where the blade comes out of the silicon single crystal rod, or Displacement detection sensors and electromagnets are arranged on both sides to detect and correct blade displacement, and not to detect and correct inner blade blade displacement at the actual cutting position.

For this reason, it is not possible to cope with the runout and deformation of the inner peripheral blade being cut into the material to be cut, and there is a possibility that the cutting accuracy cannot be maintained with high accuracy. The present invention is
Under such a background, it is possible to provide a slicing machine capable of adjusting the flatness of a work cut surface with high accuracy by controlling the displacement in the thickness direction of the blade at the portion cut into the work. Is an issue.

[0006]

A slicing machine according to the present invention is an annular inner peripheral blade made of a ferromagnetic material having a cutting blade formed on an inner peripheral edge thereof, and supports the inner peripheral blade, Blade rotating means for rotating the inner peripheral blade around its axis, work supporting means for supporting the work to be cut in a state of being inserted into the opening of the inner peripheral blade, and cutting the inner peripheral blade. A cutting means for moving the work supporting means or the inner peripheral blade so that the blade cuts into the work, and a wafer cut out from the work, and an inner peripheral portion of the inner peripheral blade blade cut into the work. And a central blade position detection sensor that is arranged at a position that can face with, over the wafer, that detects the position of the inner peripheral blade in the blade thickness direction. A central magnetic force generating means for generating a magnetic force that attracts the blade over the wafer is disposed at a position that can face the inner peripheral portion of the inner peripheral blade blade that is cut into the work, with the wafer cut out from the work being sandwiched therebetween. And 1 or 2 or more lateral magnetic force generating means that are provided so as to be separated from the central magnetic force generating means in the blade circumferential direction and face the inner peripheral portion of the inner peripheral blade.
One or more side blade position detection sensors, which are spaced apart from the central blade position detection sensor in the blade circumferential direction and are arranged so as to face the inner peripheral portion of the inner peripheral blade,
A control means for calculating the signals from the central and side blade position detection sensors, and controlling the magnetic force exerted on the inner peripheral blade by the central and side magnetic force generating means based on the calculation result. It is characterized by doing.

The control means causes the central and lateral magnetic force generating means to attract the inner peripheral portion of the inner peripheral blade with a predetermined initial magnetic force at the start of work cutting, thereby cutting the cutting blade. While maintaining the initial position closer to the central and lateral magnetic force generating means side than the position in the natural state, during the cutting of the workpiece, each of the initial depending on the signal from the central and lateral blade position detection sensor. The magnetic force may be increased / decreased to control the position of the blade inner peripheral portion bidirectionally in the thickness direction of the inner peripheral blade with reference to each of the initial positions.

The central and lateral magnetic force generating means may each have one or more electromagnets capable of attracting the inner peripheral portion of the inner peripheral blade.

In order to make the displacement amount of the inner peripheral blade at each measurement point of the center and side blade position detection sensors coincide with a preset target value of the blade displacement amount, Initial magnetic force calculating means for calculating an initial magnetic force to be generated from each of the central and lateral magnetic force generating means, a blade displacement amount detected by each of the central and lateral blade position detection sensors, and a target value of the blade displacement amount. Is calculated by the deviation detecting means for calculating the deviations by comparing the deviations, the compensating magnetic force calculating means for calculating the compensation amount of each of the initial magnetic forces based on the deviations calculated by the deviation detecting means, and the initial magnetic force calculating means. Magnetic force summing means for summing the respective initial magnetic forces and the magnetic force compensation amounts calculated by the compensation magnetic force calculating means, and the magnetic force. Current calculating means for calculating the amount of current to be supplied to each of the electromagnets of the central and lateral magnetic force generating means from each total value calculated by the measuring means, and the calculated current amount for the central and lateral magnetic force generating means. It may have a current supply means for supplying to each of the electromagnets.

The central and lateral magnetic force generating means are both arranged equidistant from the blade center, and the central and lateral blade position detecting sensors are located closer to the inner circumference of the blade than the central and lateral magnetic force generating means. It may be arranged.

Each of the central and lateral magnetic force generating means is an electromagnet in which a soft magnetic material core wound with a coil is housed inside a soft magnetic material housing, and the blade position detection sensor is a vortex. It may be a current type distance sensor.

The central and lateral magnetic force generating means are provided with a permanent magnet arranged at a position that can face the blade with the wafer sandwiched therebetween, and a driving means for moving the permanent magnet closer to and away from the blade. It may be one.

[0013]

According to the slicing machine of the present invention, the position of the cutting blade of the portion cut into the work is directly detected by the central blade position detection sensor arranged to face the wafer to be cut, and the central magnetic force generating means is used. In addition to controlling its position, the lateral magnetic force generating means arranged on the side of the central magnetic force generating means can control even the flatness of the blades in the workpiece with high precision, so cutting of the workpiece The flatness of the surface can be set freely.

Further, by cutting the blade while attracting the blade to the initial displacement position by each of the magnetic force generating means, it is possible to increase or decrease each magnetic force even though the magnetic force generating means is arranged only on one side of the blade. For example, the blade position can be adjusted in both the direction approaching the magnetic force generating means and the direction moving away from the magnetic force generating means.

[0015]

1, 2 and 3 are a front view, a plan view and a side view showing an embodiment of a slicing machine according to the present invention. In these drawings, reference numeral 1 is a base, on which a rail 2 is horizontally fixed in the left-right direction in FIG. 1, and a column 4 is installed on the rail 2 so as to be movable in the left-right direction. ing.

Inside the column 4, an annular blade fixing jig 6 is arranged so that its axis is horizontal and is rotatable about its axis. Inside the fixing jig 6, an inner peripheral blade 8 is coaxially housed, and the fixing jig 6 uniformly pulls the entire outer peripheral portion of the blade 8 radially outward so that appropriate tension is applied. There is. The blade 8 has a cutting blade 8a formed by electrodepositing abrasive grains such as diamond on the inner peripheral edge of a base metal formed of a ferromagnetic material in a ring shape. A drive mechanism 10 for rotating the fixing jig 6 around the axis is provided on the upper portion of the column 4.

In front of the column 4, a bed 12 for mounting and supporting a columnar single crystal ingot (not shown) or the like, which serves as a work, is provided facing the inner peripheral blade 8. The bed 12 is mounted on an elevating device 14 such as a hydraulic cylinder provided on the front side of the base 1 and can move up and down, whereby the work can be moved relative to the blade 8 and cutting can be performed. It is like this. Note that instead of moving the work up and down, it is also possible to move the blade 8 up and down to cut the blade 8 into the work. The bed 12 is provided with a feeding mechanism 16 for advancing and retracting the work supported on the bed 12 toward the inner peripheral blade 8 side.

In the apparatus of this embodiment, the inner peripheral blade 8
A blade position control mechanism 20, which is a characteristic part of the present embodiment, is provided so as to face the inner peripheral portion on the front surface side, and is fixed to the column 4 via a support member (not shown). In addition, a control panel 18 for operating each of the operating parts is provided.

4 to 6 show a work W such as a single crystal rod.
The blade position control mechanism 20 in the state of cutting the blade
It is a figure which shows the principal part of. The work W is adhesively fixed to a table 22 made of graphite or the like, and placed on the bed 12 (not shown). Wafer W cut from work W
At a position that can face the upper inner peripheral portion of the inner peripheral blade 8 that is cut into the work 8 with f sandwiched, a central electromagnet (center The central electromagnet 24 is fixed to a supporting portion 28 via a rod 26.

Below the central electromagnet 24, a central blade position detecting sensor 30 (hereinafter referred to as central sensor) is arranged at a position facing the vicinity of the cutting blade 7 of the blade 8 with the wafer Wf being cut therebetween. The central sensor 30 is also fixed to the support portion 28. The support portion 28 is a rod 32.
It is connected to a drive mechanism (not shown) via the and is movable in the axial direction of the blade 8. This allows
When the central electromagnet 24 and the central sensor 30 may interfere with the work W, they can be retracted from the work W.

On both sides of the central electromagnet 24 in the circumferential direction of the blade, the left electromagnet 34 and the right electromagnet 36 are located at positions not facing the wafer Wf but facing the inner circumference of the blade 8.
The (lateral magnetic force generators) are arranged symmetrically. Left and right blade position detection sensors 38, 40 (hereinafter referred to as left and right sensors) are arranged symmetrically on the inner circumference side of each of the left electromagnet 34 and the right electromagnet 36. The electromagnets 24, 34, 36 are the same and have an arcuate shape concentric with the blade 8, and are all arranged at positions equidistant from the inner peripheral edge of the blade.
The sensors 30, 38, 40 are also identical to each other and are arranged at positions equidistant from the inner peripheral edge of the blade 8. The sensors 30, 38, 40 and the electromagnets 24, 34, 36 are arranged such that their tip surfaces are parallel to the blade surface, and the distance from the blade surface is the wafer Wf to be cut out from the work W.
It is set larger than the thickness of.

The electromagnets 24, 34, 36 and the sensor 30,
38 and 40, so that the sensor is not magnetically affected,
It is desirable to dispose the blades at a certain distance or more in the blade radial direction. Since some residual magnetization is unavoidable at the portion of the blade 8 attracted by the electromagnet, an error due to magnetic influence may occur when the attracted portion passes in front of the sensor. , The areas where the electromagnets 24, 34, 36 face each other, and the sensors 30, 3
By sufficiently separating the regions where 8 and 40 face each other in the radial direction of the blade, it is possible to prevent the magnetic influence due to the residual magnetization. It should be noted that the sensors 30, 38, 40 can be arranged outside the electromagnets 24, 34, 36 in the blade radial direction instead of inside.

The electromagnets 24, 34 and 36 are all shown in FIG.
Further, as shown in FIG. 8, a housing 42 made of a soft magnetic material such as pure iron is provided, and the blade 8 of the housing 42 is provided.
Two circular arc-shaped grooves 44 are formed parallel to each other in the longitudinal direction on the end surface facing the coil 4.
A plurality of (in this example, six) cores 48 made of a soft magnetic material such as pure iron around which 6 is wound are accommodated. The coils 46 are connected in series or in parallel so that the magnetic poles of all the cores 48 have the same phase.

The electromagnets 24, 34, 36 having such a structure
According to this, as shown in FIG. 9, when the coil 46 is energized, a magnetic circuit is formed from the tip of the core 48 to the housing 42 through only the facing portion of the blade 8. Therefore, remanent magnetization is unlikely to occur outside the area where the electromagnets 24, 34, 36 of the blade 8 face each other, and the sensors 30, 38, 40
Even when the sensor is a sensor of a type such as an eddy current sensor that is susceptible to magnetic influence, it is possible to prevent the above-described residual magnetization from affecting the measured value.

Sensors 30, 38, 40 and electromagnet 2
4, 34 and 36 are respectively connected to the control panel 18 to form a control system as shown in FIG. Prior to describing this control system, the essential points of the blade position control method according to the present invention will be described with reference to FIG.

(Explanation of Blade Position Control Method) FIG. 11 is an enlarged sectional view showing a state in which the work W is being cut by the blade 8. In order to cut the work W with the slicing machine of this embodiment, the electric current is individually supplied to the electromagnets 24, 34 and 36 to generate the magnetic force f with the blade 1 started to rotate before the cutting is started. Electromagnets 24, 34, 36
The inner peripheral portion of the blade 8 facing to is attracted and elastically moved to an initial position P2 close to the electromagnets 24, 34, 36 by a certain distance x from the natural position P1 (the displacement amount at this time is referred to as an initial displacement amount). Displacement. The magnetic force f, the displacement amount x, and the position P2 may be different for each suction location.

The initial displacement amount of the blade 8 is a value to be determined according to the type of the blade 8 and is not limited in the present invention, but in the case of a general wafer manufacturing blade, it is about 2 to 50 μm. Is preferred. If it is less than 2 μm, a sufficient amount of displacement in the D2 direction cannot be secured, and conversely 50 μ
If it is larger than m, a sufficient displaceable amount in the D1 direction cannot be secured.

Next, while maintaining the initial displacement state, the cutting blade 8a of the blade 8 is cut along the planned cutting surface of the work W to start cutting the work W. If the actual cutting surface deviates from the planned cutting surface during cutting, the sensor 30,
The magnetic force f depending on the amount of deviation detected by 38 and 40.
Increase or decrease. That is, if the blade 8 is displaced in the direction D2 away from the electromagnet, the current supplied to the electromagnet is increased to increase the magnetic force f, and the blade 8 is displaced in the direction D1 toward the electromagnet to compensate the displacement. On the contrary, if the blade 8 shifts in the direction D1 approaching the electromagnet, the magnetic force f is weakened to restore the blade 8 in the D2 direction by the elastic force to compensate the shift.

(Magnetic Force Calculation Method) Next, based on the target displacement amount at each point of the blade 8, each electromagnet 24, 34, 36 is calculated.
A method of calculating the magnetic force to be generated in the will be described. The magnetic force exerted on the blade 8 by the left electromagnet 34 is f ₁ , the magnetic force of the central electromagnet 24 is f ₂ , and the magnetic force of the right electromagnet 36 is f ₃ .
Let F be the vector of these magnetic forces, as shown in the following equation.
Further, the blade displacement amount detected by the left sensor 38 is x ₁ , the blade displacement amount detected by the central sensor 30 is x ₂ ,
The blade displacement detected by the right sensor 40 is x ₃ ,
Let X be a vector of these blade displacement amounts.

[0030]

[Equation 1]

The relationship between the vector F of magnetic force and the vector X of blade displacement is shown by the following equation. C is a 3 × 3 compliance matrix, and c _ij indicates the amount of displacement of the blade observed by the sensor i when only the electromagnet j _{attracts the} blade with a magnetic force of 1.

[0032]

[Equation 2]

Inverse matrix C ^{-1 of the} compliance matrix C
Is the stiffness matrix (Stiffness Matrix) K, the following equation is obtained. F = KX

Since the compliance matrix C can be measured as will be described later, if the stiffness matrix K is obtained from the value, the magnetic force of each electromagnet required to obtain the predetermined blade displacement amount can be calculated by the above equation, The blade position can be controlled.

(Structure and operation of control system) Next, FIG.
The configuration and operation of the control system shown in will be described. X in FIG.
_r is a vector of the target value of the blade displacement amount input to this control system, and x _r1 , x _r2 , and x _r3 shown in the following equations are left, center, and right side sensors 38, 30, 4 respectively.
The target value of the blade displacement amount at each measurement point of 0 is shown.

[0036]

[Equation 3]

In the control system of this embodiment, the stiffness matrix K, which has been previously obtained from the vector X _r of the target value of the blade displacement amount inputted by the initial magnetic force calculating means 50, is first described.
Is used to calculate the vector F _{f of the} initial magnetic force that each electromagnet 34, 24, 36 should exert on the blade 8. The vector F _f of this initial magnetic force is expressed by the following equation, and f _f1 , f _f2 and f _f3 are the left, center and right electromagnets 34, 24, 36.
Represents the initial magnetic force to be exerted on the blade 8 in advance.

[0038]

[Equation 4]

The initial magnetic force vector F _f is then transmitted to the magnetic force summing means 56. However, the compensating magnetic force F _b, which will be described later, finally becomes 0 when there is no disturbance on the blade 8, so the vector of the initial magnetic force is obtained. F _f is directly transmitted to the current calculation means 58. The current calculation means 58 calculates the vector I of the current to be supplied to each electromagnet in advance at the start of cutting based on the vector F _f of the initial magnetic force. I ₁ , i ₂ and i in the following equation
Reference numeral ₃ indicates the amount of current to be supplied to the left, center and right electromagnets 34, 24 and 36.

[0040]

[Equation 5]

From the initial magnetic forces f _f1 , f _f2 and f _f3 to the current i ₁ ,
In order to calculate i ₂ and i ₃ , the relational expression between the magnetic force applied to the blade and the current for each electromagnet may be obtained in advance by an experiment, and the current to be supplied to each electromagnet may be calculated from the relational expression. By supplying these currents i ₁ , i ₂ , and i ₃ to the respective electromagnets, the displacement amount of the blade 8 at each measurement point can be made to match the target value before the start of cutting.

After the blade 8 is initially displaced as described above, the work W is inserted into the blade 8 and the lifting device 14 is moved.
Then, the work W is started to be cut. Simultaneously with the start of cutting, the sensor 38,
The amount of blade displacement is measured at 30 and 40. The output of each sensor 38, 30, 40 obtained by one sampling is
It is transmitted to the blade position calculation means 60, and the vector X _c of the measured value of the blade displacement amount at each measurement point is calculated. x _c1 , x _c2 and x _c3 are measurements of blade displacement at the left, center and right sensor 38, 30, 40 positions. The calculated measured value vector X _c is transmitted to the deviation detecting means 52, and the deviation detecting means 52 compares the measured value vector X _c with the target value vector X _r to calculate the deviation vector X _e . .

[0043]

[Equation 6]

The deviation vector X _e is calculated by the compensation magnetic force calculating means 5
4 and the vector F _b of the compensating magnetic force is calculated by the following equation. f _b1 , f _b2 and f _b3 indicate the magnetic force compensation amounts in the left, center and right electromagnets 34, 24 and 36.

[0045]

[Equation 7]

The above equation shows a calculation equation when proportional control is used as a control law for reducing X _e .
Other than the comparison control, any control law can be used as long as it makes the deviation x _e close to zero. For example, a calculation formula such as the following formula may be used. In the following equation, k _p , k ₁
Is a positive real number and t is time.

[0047]

[Equation 8]

The calculated compensating magnetic force vector F _b and the initial magnetic force vector F _f transmitted from the initial magnetic force calculating means 50 are summed in the magnetic force summing means 56, so that the electromagnets 34, 24 and 36 can perform the following. The vector F of the magnetic force to be generated is calculated. The obtained magnetic force vector F is transmitted to the current calculation means 58, and the current amounts i ₁ , i ₂ and i ₃ to be supplied to each electromagnet are calculated again as described above.
Supply to each electromagnet 34, 24, 36.

Thereafter, as in the above, each sensor 3 is set at regular intervals.
By measuring the blade displacement amount at 8, 30, 40 and repeating the initial magnetic force calculation, the compensation magnetic force calculation, the current calculation, and the current supply, the blade displacement amount x _c1 at each measurement point,
It is possible to match x _c2 and x _c3 with the target values x _r1 , x _r2 and x _r3 , respectively.

Strictly speaking, the magnetic force generated by the electromagnets 34, 24, 36 also changes depending on the amount of gap between the blade and the electromagnet. However, in this embodiment, the electromagnets 34, 24, 36 are
Since the gap amount between the blade 8 and the blade 8 is about 1 mm, the displacement width of the blade is about several μm, so that the change in magnetic force due to the change in the gap amount can be ignored.

According to the above control method, when the vector X _{r of the} target value is input before the start of cutting, the blade displacement amount at the position facing each sensor during cutting is the component of the vector X _r of the target value. Since it is automatically controlled so as to match with, it is possible to cut a wafer with high flatness. Further, according to the present invention, not only a wafer having a high flatness but also a wafer to which a predetermined warp is applied in advance in order to cancel the warp of the wafer generated in a subsequent process can be manufactured. In that case, the wafers Wf may be warped arbitrarily by making the target values x _{r1 to} x _r3 at the respective measurement points different from each other or cutting the target values x _{r1 to} x _r3 while changing them with time. Give.

In this embodiment, the initial magnetic force calculating means 5
Although the initial magnetic force F _f is calculated by 0 and the initial magnetic force F _f is fed forward, the blade displacement amount is automatically calculated by the action of the compensating magnetic force calculating means 54 without performing such feed forward. It matches the target value X _r .
However, performing the feedforward by the initial magnetic force calculating means 50 has an advantage that the position of the blade 8 is stabilized more quickly after the start of cutting, as compared with the case where the feedforward is not performed.

Further, although three electromagnets and three sensors are provided in the above embodiment, the number of electromagnets and sensors may be two or four or more in the present invention. As the number of sensors and electromagnets increases, the shape of the cut surface can be controlled with higher accuracy, and the flatness of the wafer can be increased. Even if the numbers of electromagnets and sensors are changed, control can be easily performed by using the matrix as described above.

The number of sensors and electromagnets may not be the same. If the rank of the compliance matrix is equal to or larger than the number of sensors, it is controllable without considering the restriction of the magnetic force of the electromagnet. When the number of electromagnets is larger than that of the sensor, the aforementioned compliance matrix C does not become a square matrix, and the stiffness matrix K which is the inverse matrix thereof cannot always be calculated. However, instead of the stiffness matrix K, the pseudo inverse matrix (psudo) of the matrix C is used. -Inverse matrix) can be used for the same control as above. However, when the number of electromagnets is smaller than the number of sensors, it is impossible to make all the deviations at the measurement points of each sensor zero.

According to the slicing machine having the above structure, the position of the blade cutting blade 7 of the portion cut into the work W is directly detected by the central blade position detection sensor 30 arranged to face the wafer Wf to be cut. The central electromagnet 24 not only controls its position, but also the left and right electromagnets 34 disposed on both sides of the central electromagnet 24,
Since the flatness of even the portion cut into the work W is controlled with high precision by 36, the flatness of the cut surface of the work W can be freely set.

Further, in this embodiment, the electromagnets 34, 2 are
Since cutting is performed in a state where the blade 8 is sucked by each of the blades 4 and 36, the blade position can be adjusted by increasing or decreasing each magnetic force either in the direction approaching the electromagnet or in the direction away from the electromagnet.

Further, three blade position detection sensors 3
The signals from 0, 38 and 40 are calculated using the stiffness matrix K to determine the supply currents to the three electromagnets 24, 34 and 36. It is possible to improve the operation stability as compared with the configuration in which the feedback is individually performed on the. It is also possible to control the signal of each sensor to be fed back to the current of each electromagnet individually, but if the blade position at one measurement point is corrected, the blade position at another measurement point changes and must be corrected again. Therefore, the stability of blade position control is reduced, and the blade position is likely to be unstable.

Further, in this embodiment, the central electromagnet 24 is
Since the central sensor 30 is movable in the blade axis direction, for example, when cutting the end of the work W, the central electromagnet 24 and the central sensor 30 are retracted from the work W to move the work. It is possible to eliminate the possibility that the end portion interferes with the central electromagnet 24 and the central sensor 30. In this case, although the control accuracy is slightly lowered, the left and right sensors 38, 40 and the electromagnets 34, 3 are
Only 6 can be used to control the blade position.

Next, a specific example of control in the apparatus of the second embodiment will be described. The apparatus shown in FIGS. 1 to 10 was actually manufactured, and the left sensor 38 and the right sensor 40 were arranged at positions which were separated by 50 ° from the central sensor 30 to the left and right and 10 mm outward from the inner peripheral edge of the blade 8. Further, the left electromagnet 34 and the right electromagnet 36 are arranged at positions of 60 ° to the left and right from the center of the central electromagnet 24.

Eddy current type sensors are used as the sensors 30, 38, 40, and the sensors 30, 38, 40 and the electromagnets 24, 34, 36 are arranged in the blade radial direction so as not to be affected by the residual magnetization of the blade 8 by the electromagnet. 12 mm apart. In addition, regarding the presence or absence of the influence of magnetism, a laser displacement meter (not shown) is arranged at a position facing each sensor 30, 38, 40 with the blade 8 sandwiched between them, and a magnetic force is generated so that the measured values of the both agree with each other. It was decided whether or not to do it.

Electromagnets 24, 34, 36, sensors 30, 3
The distance between the blades 8 and 40 and the blade 8 and the like were set as shown in FIG. The blade 8 used has an inner diameter of 235 m.
m, the base metal thickness is 0.15 mm, the thickness of the cutting blade 8a on which diamond abrasive grains are electrodeposited is 0.3 mm, and the base metal is made of ferromagnetic stainless steel. This blade 8 has an inner diameter of 1.2
It was pulled up by the fixing jig 6 until it was enlarged by mm. In this state, the inner peripheral portion of the blade 8 is 350 g in the blade axial direction.
When pressed with f, it was displaced by 50 μm. Electromagnet 24,3
The distance from the blade end faces of 4, 36 and the sensors 30, 38, 40 was set to 1.0 mm.

As the electromagnets 24, 34, and 36, as shown in FIGS. 7 to 9, those having a structure in which 12 cores 48 made of pure iron are fitted in a housing 42 made of pure iron are used. The coil 48 of 300 turns was attached to the core 48. Using the above apparatus, the relationship between the magnetic force and the amount of displacement of the blade 8 was investigated. As shown in FIG. 6, a laser displacement meter 62 is arranged at a position of 10 mm outside the inner peripheral edge of the blade 8, and the blade 8 is rotated at 1460 rpm while changing the angle θ from the center of the central electromagnet 24 at every 10 °. The blades were continuously rotated, the current supplied to the central electromagnet 24 was disconnected and connected, and the blade displacement amount at each point was measured. The current to the central electromagnet 24 was 1.5A.

The results are shown in Table 1 and FIG. The amount of displacement became maximum at the point of θ = 0 °, and the amount of displacement gradually decreased with increasing distance from this point, and the graph became substantially bilaterally symmetric about θ = 0. From this, it was found that the displacement amount of the blade 8 was hardly affected by the rotation.
This is because the blade 8 is extremely thin and lightweight.

[0064]

[Table 1]

The left and right electromagnets 34, 36 are the central electromagnet 2
Since it is exactly the same as No. 4, each electromagnet 24, 34, 3
The amount of blade displacement when a current of 1.5 A is applied to 6 is
It becomes like each line shown in FIG. When the magnetic force of the electromagnet when a current of 1.5 A is passed is 1, the following compliance matrix C and rigidity matrix K are obtained from the experimental data of FIG. 13 and the positional relationship between the electromagnet and the sensor.

[0066]

[Equation 9]

By using the stiffness matrix K, Table 2
Target values x ₁ , x ₂ , x of blade displacement shown in Examples 1 to 3 of
Corresponding to ₃ , the magnetic forces f ₁ , f ₂ and f ₃ that each electromagnet should exert on the blade could be calculated as shown in the table. Figure 10
With the compensation magnetic force calculating means 54 of FIG.
_The amount of current is calculated from ₁ , f ₂ and f ₃ to obtain the electromagnets 34 and 2
When it was supplied to Nos. 4 and 36 and the blade displacement amount at each sensor measurement point was measured with a laser displacement meter, it was confirmed that the target value was met. 15, FIG. 16 and FIG. 17 are shown in Table 2.
6 is a graph showing the result of calculation using the compliance matrix C of the shape of the cut surface when the target value is set as in Examples 1 to 3.

[0068]

[Table 2]

The slicing machine according to the present invention is not limited to the above embodiment, and the configuration may be changed as necessary. For example, instead of using an electromagnet as the magnetic force generating means, a magnetic force generating means having a permanent magnet and a driving means such as a direct-acting stepping motor for moving the permanent magnet toward and away from the blade 8 may be used.

[0070]

As described above, according to the slicing machine of the present invention, the position of the cutting blade of the portion cut into the work can be directly measured by the central blade position detecting sensor arranged to face the wafer to be cut. Not only does it detect and control its position by the central magnetic force generating means, but also by the lateral magnetic force generating means arranged on the side of the central magnetic force generating means,
Since even the flatness of the portion cut into the work can be controlled, the flatness of the cut surface of the work can be freely set, and not only a wafer having a high flatness but also a wafer having a predetermined warp can be manufactured.

Further, since the blade is cut by the central and lateral magnetic force generating means while being sucked to the initial displacement position, the magnetic force generating means is arranged only on one side of the blade, By increasing or decreasing each magnetic force, the blade position can be adjusted both in the direction approaching the electromagnet and in the direction moving away from the electromagnet.

Further, in the case where the signals from the two or more blade position detecting sensors are calculated by using a stiffness matrix or the like to control the magnetic force generated by the magnetic force generating means, the signals of the respective sensors are generated. It is possible to improve operational stability as compared with a configuration in which feedback is individually provided to the means.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of a slicing machine according to the present invention.

FIG. 2 is a plan view of the slicing machine.

FIG. 3 is a side view of the slicing machine.

FIG. 4 is a perspective view showing a main part of a blade position control mechanism of the slicing machine.

FIG. 5 is a side view showing a main part of the blade position control mechanism.

FIG. 6 is a front view showing a main part of the blade position control mechanism.

FIG. 7 is a front view of an electromagnet used in the blade position control mechanism.

FIG. 8 is a sectional view of the electromagnet.

FIG. 9 is a sectional view showing the operation of the electromagnet.

FIG. 10 is a block diagram of a control system of the slicing machine.

FIG. 11 is a cross-sectional view showing the operation of the blade position control mechanism.

FIG. 12 is a side view showing a main part of an apparatus used in an experimental example of the present invention.

FIG. 13 is a graph showing the results of the experimental example.

FIG. 14 is a graph for explaining a blade control method in the experimental example.

FIG. 15 is a graph showing an example of a cut surface shape in the experimental example.

FIG. 16 is a graph showing an example of a cut surface shape in the experimental example.

FIG. 17 is a graph showing an example of a cut surface shape in the experimental example.

[Explanation of symbols]

W work Wf Wafer 8 Inner peripheral blade 8a Cutting blade 24 Central electromagnet (central magnetic force generating means) 30 Central blade position detection sensor 34, 36 Left and right electromagnets (side magnetic force generating means) 38, 40 Left and right blade position detection Sensor (side blade position detection sensor) 42 Housing 46 Coil 48 Core 50 Initial magnetic force calculating means 52 Deviation detecting means 54 Compensating magnetic force calculating means 56 Magnetic force summing means 58 Current calculating means 60 Blade position calculating means

Claims (7)

[Claims] 1. An inner peripheral blade made of an annular ferromagnetic material having a cutting blade formed on an inner peripheral edge thereof, and a blade for supporting the inner peripheral blade and rotating the inner peripheral blade around its axis. Rotating means, work supporting means for supporting the work to be cut in a state of being inserted into the opening of the inner peripheral blade, and the work supporting means so that the cutting blade of the inner peripheral blade cuts into the work. Or cutting means for moving the inner peripheral blade, sandwiching the wafer cut out from the work, is arranged at a position that can be opposed to the inner peripheral portion of the inner peripheral blade cut into the work, the wafer over In the central blade position detection sensor for detecting the position of the inner peripheral blade in the blade thickness direction, the blade circumference from the central blade position detection sensor. 1 or 2 or more lateral blade position detection sensors that are spaced apart in the opposite direction and are arranged to face the inner peripheral portion of the inner peripheral blade, and a wafer cut out from the work is sandwiched between the inner peripheral blade blade and the inner peripheral blade, and the wafer is cut into the work. A central magnetic force generation unit that is arranged at a position that can face the inner peripheral portion of the inner peripheral blade and that generates a magnetic force that attracts the inner peripheral blade over the wafer, and is separated from the central magnetic force generation unit in the blade circumferential direction. And provided to face the inner peripheral portion of the inner peripheral blade 1
Alternatively, the signals from the two or more lateral magnetic force generating means and the central and lateral blade position detecting sensors are arithmetically processed, and based on the arithmetic result, the central and lateral magnetic force generating means act on the inner peripheral blades. A slicing machine comprising: a control unit that controls each magnetic force exerted. 2. The control means causes the central blade and the lateral magnetic force generator to attract the inner peripheral portion of the inner peripheral blade with a predetermined initial magnetic force at the start of cutting of the work, thereby controlling the cutting blade. While maintaining the initial position closer to the center and the side magnetic force generating means side than the position in the natural state, while the workpiece is being cut, each of the initial positions according to the signals from the center and side blade position detection sensors. Increase or decrease the magnetic force,
The slicing machine according to claim 1, wherein the position of the inner peripheral portion of the blade is controlled bidirectionally in the thickness direction of the blade based on each of the initial positions. 3. The central and lateral magnetic force generating means each have one or more electromagnets capable of attracting the inner peripheral portion of the inner peripheral blade.
Slicing machine described. 4. The control means matches the displacement amount of the inner peripheral blade at each measurement point of the center and side blade position detection sensors with a preset target value of the blade displacement amount. In the initial magnetic force calculating means for calculating the initial magnetic force to be generated from each of the central and lateral magnetic force generating means, the blade displacement amount detected by the central and lateral blade position detection sensor, respectively, of the blade displacement amount. A deviation detecting unit that compares a target value with each other to calculate a deviation, a compensating magnetic force calculating unit that calculates a compensation amount of each initial magnetic force based on the deviation calculated by the deviation detecting unit, and an initial magnetic force calculating unit. Magnetic force summing means for respectively summing each of the calculated initial magnetic forces and each of the magnetic force compensation amounts calculated by the compensation magnetic force calculating means, Current calculating means for calculating the amount of current to be supplied to each of the electromagnets of the central and lateral magnetic force generating means from each total value calculated by the force summing means, and the calculated current amount for generating the central and lateral magnetic force 4. The slicing machine according to claim 3, further comprising a current supply unit that supplies the electromagnets of the unit. 5. The central and lateral magnetic force generating means are both arranged equidistantly from the blade center, and the central and lateral blade position detecting sensors are arranged such that the central and lateral magnetic force generating means have an inner circumference of the blade. The slicing machine according to claim 1, 2, 3, or 4, wherein the slicing machine is arranged on the side. 6. The blade position detecting sensor, wherein each of the central and lateral magnetic force generating means is an electromagnet having a soft magnetic material core having a coil wound inside a soft magnetic material housing. Is an eddy current type distance sensor, The slicing machine according to claim 1, 2, 3, 4 or 5. 7. The central and lateral magnetic force generating means separates the permanent magnet from the inner circumferential blade blade by arranging the permanent magnet at a position that can face the inner circumferential blade blade with the wafer interposed therebetween. The slicing machine according to claim 1, further comprising: a driving unit for driving the slicing machine.