JPH10264005A - Wire diameter detection device for wire saw and wire saw using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of a wire breakage before happening and also process accurately by always detecting and controlling the diameter of a wire in a running by a non-contact in a wire saw. SOLUTION: In a wire diameter detection device for detecting the diameter of the wire of a wire saw for processing the work by pressing a running wire 14 to the work and supplying a processing liquid including abrasive grains to the pressed part, the wire 14 is made of a magnetic material and provided with an inductance element 61 through whose inside the wire is passed, a capacity element 62 connected so as to form the inductance element and a tank circuit, oscillation signal producing circuits 64, 65, 66 for impressing the oscillation signal with a prescribed amplitude by a prescribed frequency to the tank circuit and a voltage detection circuit 68 for detecting the voltage of the tank circuit, and the wire diameter is detected from the voltage of the tank circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire diameter which is attached to a wire saw used for simultaneously cutting a plurality of thin disk-shaped wafers from an ingot of a semiconductor material, and which detects a wire diameter in a non-contact manner. The present invention relates to a detection device and a wire saw having such a wire diameter detection device.

[0002]

2. Description of the Related Art An apparatus called a dicing saw or a slicing saw is used for cutting a thin disk-shaped wafer from a semiconductor ingot or processing a thin groove in a brittle material such as ceramic or glass. This device rotates the grindstone blade with diamond abrasive grains fixed with nickel or the like at a high speed to perform groove processing. Calling. The processing of the groove is performed by moving the work (work) relatively to the grindstone blade. In such an apparatus, there is usually one grindstone blade, and one groove can be processed by one relative movement.

Some workpieces machine a large number of parallel grooves at predetermined intervals. For example, when cutting a thin disk-shaped wafer from an ingot of a semiconductor material, if one wafer is cut out, the ingot is moved in the axial direction by an amount corresponding to the thickness, and then a cutting operation is performed. Many wafers are repeatedly cut out from one ingot. However, in this case, it is necessary to repeat the above operation for the number of wafers to be cut, and it takes a long time to process one ingot, and there is a problem that a sufficiently high production efficiency cannot be obtained. To solve the above problems,
In a dicing saw, two grindstone blades are provided in parallel, and two grooves are simultaneously processed. However, only two grooves can be processed at the same time, and it is not possible to improve productivity sufficiently. Can not.

On the other hand, as a device for processing a thin groove, a wire saw is used in which a wire having a diameter slightly smaller than the width of the groove is pressed against a work while running, and a processing liquid containing abrasive grains is supplied to the portion to perform processing. There is a device. In a wire saw, a plurality of parallel grooves are simultaneously formed by winding a wire around a roller having a plurality of grooves, forming a wire row running in parallel at a predetermined interval, and pressing a portion of the wire row against a workpiece. can do. In this wire saw, one end of the wire is wound around one wire reel, and the other end is wound around the other wire reel, and the wire usually travels 500 m / m between one wire reel and the other wire reel.
It reciprocates at a high speed of 1 to 1000 m / min. During this reciprocation, the work is pressed against the wire row,
A work fluid containing abrasive grains is supplied to the wire row, and the work is cut into a number of thin wafers by the lapping action of the abrasive grains.

[0005] It is desirable that the wire used in the wire saw has a uniform perfect circular shape with a predetermined diameter. However, since the wire is manufactured by pulling out the steel material, the wire has a certain degree of variation in diameter, the entire length is not uniform, and there are various distortions and local changes in diameter. In addition, while the wire is being processed, the wire itself wears due to the abrasive grains, and the diameter gradually decreases. During processing, the wire is pulled with a predetermined force so that the wire row is pressed against the work with a predetermined pressure. Therefore, if the diameter of the wire becomes small or the above-described distortion occurs, the wire is broken. When the wire breaks, there is a problem in that the work or parts constituting the wire saw are damaged, or the wire is entangled with the device, and it is necessary to stop the device while removing the wire, thereby lowering production efficiency. In order to solve such a problem, it has been performed to detect a worn state of the wire and replace the wire before disconnection.

The detection of the state of wear of the wire is performed by measuring the diameter of the wire. The diameter of the wire is about 200 μm.
It must be possible to detect with a resolution of m. The wire travels at a high speed, and when a contact-type measuring instrument such as a micrometer is used to measure the diameter of the wire, it cannot be measured while the wire is traveling. Therefore, the wire saw is temporarily stopped at regular intervals, and during this time, the operator measures the wire diameter with a micrometer or the like, and replaces the wire when the wire diameter falls below a predetermined value. However, if the wire saw is temporarily stopped to measure the wire diameter, there is a problem that the production efficiency is reduced accordingly. Therefore, it has been desired to measure the state of the running wire in a non-contact manner.

Accordingly, the present applicant has filed a Japanese Patent Application No. 8-33330.
In No. 75, a differential transformer is formed by applying an oscillating signal to the excitation coil through a wire running between the excitation coil and the two detection coils, and a difference between electromotive forces generated in the two detection coils. There is disclosed a wire shape detection device that detects distortion of a wire in a non-contact manner by detecting the wire shape.

[0008]

SUMMARY OF THE INVENTION The aforementioned Japanese Patent Application No. 8-33 is disclosed.
By using the wire shape detecting device disclosed in No. 3075, the state of the wire can be constantly detected without stopping the wire saw, and the occurrence of disconnection of the wire can be reduced without lowering the production efficiency. Become like

However, the wire shape detecting device disclosed in Japanese Patent Application No. 8-333075 uses the principle of a differential transformer, and can detect only the wires located in the two detecting coils. Is the difference. That is, it is possible to detect only partial distortion of the wire, and it is not possible to detect a change in the wire diameter of a uniform portion without distortion. For this reason, there has been a problem in that the wire diameter becomes smaller as a result of the processing, and it is not possible to detect a disconnection that occurs without withstanding the tensile force applied to the wire.

The present invention is intended to solve such a problem. A wire diameter detecting device capable of detecting a change in the wire diameter of a wire saw in a non-contact manner, and a wire diameter detecting device using the same without reducing production efficiency. The aim is to realize a wire saw that can manage

[0011]

The wire diameter detecting device for a wire saw of the present invention is provided with an inductance element so that a wire made of a magnetic material passes through the inside. The wire functions as an iron core of the inductance element, and the inductance changes according to the wire diameter. If a capacitance element is provided so as to form a resonance circuit with this inductance element, the inductance of the inductance element changes according to the diameter of the wire, so that the resonance frequency of the resonance circuit changes according to the diameter of the wire. . This resonance circuit is used as a tank circuit. When an oscillation signal having a predetermined frequency and a predetermined amplitude is applied to the tank circuit, if the frequency of the applied oscillation signal matches the resonance frequency of the tank circuit, the voltage of the oscillation signal of the tank circuit is large, but the voltage is applied. As the difference between the frequency of the oscillation signal and the resonance frequency of the tank circuit increases, the voltage of the oscillation signal of the tank circuit decreases. Therefore, if the relationship between the wire diameter and the voltage of the tank circuit is checked in advance, the wire diameter can be detected by detecting the voltage of the tank circuit.

That is, in the wire diameter detecting apparatus for a wire saw of the present invention, a traveling wire is pressed against a workpiece (work), and a processing liquid containing abrasive grains is supplied to the pressed portion to process the workpiece. A wire diameter detecting device for detecting a diameter of a wire of a wire saw, wherein the wire is made of a magnetic material and connected to form an inductance element through which the wire passes, and a tank circuit with the inductance element. A capacitor element, an oscillation signal generation circuit for applying an oscillation signal of a predetermined frequency and a predetermined amplitude to the tank circuit, and a voltage detection circuit for detecting a voltage of the tank circuit; a voltage of the tank circuit detected by the voltage detection circuit The diameter of the wire is detected from the distance.

[0013] In the wire diameter detecting device for a wire saw of the present invention, the wire only passes through the inductance element.
The wire diameter can be detected without contact. Further, the wire saw of the present invention includes the above-described wire diameter detecting device, and stops the running of the wire when the wire diameter detected by the wire diameter detecting device becomes equal to or smaller than a predetermined value, and instructs the replacement of the wire. To do it. Thereby, disconnection can be prevented.

[0014]

FIG. 1 is a diagram showing the overall configuration of a wire saw according to an embodiment of the present invention. First, the overall configuration of the wire saw will be briefly described. As shown in FIG. 1, a wire 14 wound around one of the reels 12 is
6a, a plurality of fixed guide rollers 18, a movable roller 20, and sequentially wound around three grooved rollers 22a, 22b, 22c to form a wire row 24, and then a plurality of fixed guide rollers 18, a movable roller 20, forming a wire running path that is wound on the other reel 26 via the wire guiding device 16b. A weight 44 having a predetermined weight is suspended from the moving roller 20, and a predetermined tension is constantly applied to the wire 14 by the load of the weight 44. In the middle of the wire traveling route, the wire cleaning devices 46a and 46a
b, and the machining fluid 40 attached to the wire 14
Is removed. The wire 14 is made of steel.

Each of the reels 12 and 26 is connected to drive motors 28 and 30 that can rotate forward and reverse, and one of the three grooved rollers 22 is a drive motor that can rotate forward and reverse. 32. One reel 12
Is wound on the other reel 26 while traveling at a high speed of 500 m / min to 1000 m / min in the direction of the arrow 34 shown by the solid line in the drawing. Further, the wire 14 wound on the other reel 26 at one end travels in the direction opposite to the arrow 34 and is wound on the reel 12. That is, the wire 14 reciprocates between the one reel 12 and the other reel 26.

A portion of the wire row 24 formed between the two grooved rollers 22b and 22c has an abrasive storage tank 3
8 (usually GC # 600 to GC # 10
About 00 abrasive grains are used. ) Is supplied from the abrasive supply nozzle 42. A work feed table 48 is provided below the wire row 24 for mounting and moving a workpiece. The work feed table 48 is moved by a feed screw 52 rotated by a motor 50 in a direction perpendicular to the plane of the wire row 24 (Y-Y direction in the figure).
A semiconductor ingot 54, which is a work, is supported on the work feed table 48 side of the wire row 24 via a block 56 and a slice base 58. When the work feed table 48 is moved to the wire row 24 side,
The semiconductor ingot 54 is pressed against the wire row 24 running at high speed, and the semiconductor ingot 5
4 is cut into many thin wafers. The above is the same configuration as the conventional wire saw.

The wire saw of the present embodiment has a wire diameter detecting device 60 in addition to the above configuration. The wire diameter detecting device 60 may be provided at any position.
Is preferably provided at a position where the vehicle travels in the vertical direction. This is because the change in the position of the wire 14 is smaller in the part traveling in the vertical direction than in the part traveling in the horizontal direction.
Further, the wire diameter detecting device may be provided at a plurality of locations.

FIG. 2 is a diagram showing the configuration of the wire diameter detecting device 60 used in this embodiment. As shown in FIG. 2, the wire diameter detection device 60 is provided with a coil 61 so that the wire 14 passes through the inside, and capacitors 62 are connected to both ends of the coil 61. These coils 61
And a capacitor 62, a resonance circuit is formed. If the inductance of the coil 61 is L and the capacitance of the capacitor 62 is C, the resonance frequency f is f = 1 / (2π (L
C) ^1/2 ). When the diameter of the wire 14 decreases due to wear, the inductance L of the coil 61 also decreases, and the resonance frequency f changes. In the present invention, this resonance circuit is used as a tank circuit.

An oscillation signal such as a sine wave, a triangular wave, or a square wave generated by the variable gain oscillation circuit 64 is amplified by an amplifier 66 and applied to the tank circuit. automatic·
The gain control (AGC) circuit 65 is connected to the amplifier 6
6 is fed back negatively to the variable gain oscillation circuit 64. The output intensity of the variable gain oscillation circuit 64 is changed according to the output intensity of the amplifier 66, and the output intensity of the amplifier 66 is kept constant. As a result, an oscillation signal having a constant frequency and a constant amplitude is applied to the tank circuit. The capacitor 63 is provided to prevent the tank circuit from affecting the amplifier 66.

When an oscillation signal having a predetermined frequency and a constant amplitude is applied to the tank circuit constituted by the coil 61 and the capacitor 62, if the frequency of the applied oscillation signal matches the resonance frequency of the tank circuit, Although the voltage of the oscillation signal of the tank circuit is large, the voltage of the tank circuit decreases as the difference between the frequency of the applied oscillation signal and the resonance frequency of the tank circuit increases. As described above, since the resonance frequency of the tank circuit changes according to the inductance of the coil 61, and the inductance of the coil 61 changes according to the diameter of the wire 14, the voltage of the tank circuit changes according to the diameter of the wire 14. Will do. FIG. 3 shows this state. Here, in order to detect the diameter of the wire 14 from the voltage of the tank circuit, it is necessary that the voltage of the tank circuit and the diameter of the wire 14 have a one-to-one correspondence.
It is necessary to set the range of change in the diameter of the above to the illustrated range.
In other words, it is necessary to set the range so as not to include the wire diameter that maximizes the voltage of the tank circuit. Actually, since the change range of the inductance is determined by the change range of the wire diameter and the coil, the range of the resonance frequency is determined from the change range of the inductance and the capacitance of the capacitor. Set the oscillation frequency.

The voltage of the tank circuit is detected by a voltage detecting circuit 68 via a coil 67 provided corresponding to the coil 61, and is displayed on a meter 69. If the relationship between the voltage of the tank circuit and the diameter of the wire 14 is checked in advance, the diameter of the wire 14 can be known from the display of the meter 69. The voltage detection circuit 68 is, for example, a circuit that rectifies an AC signal generated in the coil 67 and then detects the voltage. Since such a circuit that detects the voltage of the AC signal is widely known,
Here, the description is omitted.

By providing the wire diameter detecting device 60 as described above, the diameter of the traveling wire 14 can be detected in a non-contact manner. The wire saw according to the present embodiment always detects the diameter of the wire 14 without stopping the apparatus, and stops the operation of the apparatus when the diameter of the wire 14 becomes a predetermined value or less to replace the wire 14. Instruct workers. FIG. 4 is a block diagram showing only a part related to the present invention of the control unit of the wire saw. As shown,
A wire diameter detection device 60 is connected to the entire control unit 90. When the wire diameter detected by the wire diameter detection device 60 becomes equal to or smaller than a predetermined threshold, the motors 28, 30, 3
2, 50 are stopped, and a display for instructing the display device 91 to replace the wire 14 is performed.

Here, the necessity of managing the wire diameter will be described. FIG. 5 shows that the wire row 24 is
FIG. 4 is a diagram showing a cross section of a portion pressed against the surface. As shown in the drawing, the wire 14 traveling in parallel is pressed against the work 54, and the processing liquid 40 is supplied from an abrasive supply nozzle 42 provided on the upper part. Here, the pitch of the wires 14 in the wire row 24 is Pw, the wire diameter is φw, and the abrasive grain size is φ.
g, the thickness T of the cut wafer is Pw-φ
It is known that w-3φg. Since Pw and φg can be kept constant, the error of T is determined by the wire diameter φw. Therefore, by controlling the wire diameter φw, the pressure difference of the wafer to be cut can be kept within a predetermined range.

Further, the material of the wire 14, the applied tensile pressure,
If the conditions such as and the material of the work are the same, wire 1
The diameter of No. 4 and the rate of occurrence of disconnection vary as shown in FIG. As is apparent from FIG. 6, when the wire diameter exceeds a certain wire diameter, the disconnection occurrence rate sharply increases. Therefore, if the wire diameter is constantly monitored and the wire 14 is replaced when the wire diameter to be replaced as shown in the figure is reached, the wire 14 can be used efficiently and the occurrence of disconnection can be prevented. .

It is troublesome to replace the wire 14 when the groove is formed halfway in the work 54, and the wire diameter is different in the middle, which is not preferable. Therefore, the relationship between the processing time and the decrease in the wire diameter is examined in advance, and if there is a possibility that the wire diameter may become the above-described wire diameter to be replaced during the processing of the next groove, the processing of the groove is performed. It is desirable to instruct the user to change the wire before starting.

[0026]

As described above, according to the present invention,
Since the diameter of the running wire in the wire saw can always be detected in a non-contact manner, the wire diameter can be managed. Thus, the wire can be used efficiently while preventing the occurrence of disconnection, and accurate processing can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of a wire saw according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of a wire diameter detection device according to an embodiment.

FIG. 3 is a diagram illustrating a relationship between a wire diameter and a voltage of a tank circuit.

FIG. 4 is a block diagram illustrating a configuration of an entire control unit of the wire saw according to the embodiment.

FIG. 5 is a diagram showing a state of a processed portion in a wire saw.

FIG. 6 is a diagram showing a relationship between a wire diameter and a disconnection occurrence rate in a wire saw.

[Explanation of symbols]

14: Wire 61: Inductance element (coil) 62: Capacitance element (capacitor) 63: Capacitor 64: Variable gain oscillation circuit 65: Automatic gain control (AG
C) Circuit 66 ... Amplifier 67 ... Coil 68 ... Voltage detection circuit

Claims (2)

[Claims] A traveling wire (14) is connected to a workpiece (5).
4) a wire diameter detecting device for detecting a diameter of the wire (14) of a wire saw for processing the workpiece by supplying a working fluid (40) containing abrasive grains to the pressed portion. The wire (14) is made of a magnetic material, an inductance element (61) through which the wire (14) passes, and a capacitor connected to the inductance element (61) to form a tank circuit. An element (62), an oscillation signal generation circuit (64, 65, 66) for applying an oscillation signal of a predetermined frequency and a predetermined amplitude to the tank circuit, and a voltage detection circuit (68) for detecting a voltage of the tank circuit
And detecting the diameter of the wire (14) in a non-contact manner from the voltage of the tank circuit detected by the voltage detection circuit (68). 2. A wire saw comprising the wire diameter detecting device according to claim 1.