JPH0616985B2 - Cutting method in wire saw - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for cutting a so-called brittle material such as a semiconductor material, a magnetic material, or a ceramic into a wafer shape by a wire.

Prior art and its problems Fig. 5 shows the cutting situation by the wire saw. A plurality of multi-groove rollers 50 (hereinafter simply referred to as “groove rollers”) circulates one wire 51, and the wires having a predetermined pitch of the groove rollers 50 accommodate the wires 51 in guide grooves (hereinafter simply referred to as “grooves”). The work 5 is formed while forming the pitch wire rows 52, running the wire rows, and supplying the working liquid 54 containing abrasive grains to the sliding portions of the wires 53.
3 is pushed up and the product 5 of a predetermined thickness is produced by the grinding action of the abrasive grains.
5 (hereinafter referred to as a wafer) is cut.

The thickness variation and the flatness of the cut surface are important as the dimensional accuracy required for the cut wafer, and in particular, the micron order accuracy is a problem in the electronics field. In the conventional wire saw cutting, the dimensional accuracy with the wafer is not always sufficient, and it is customary to obtain the necessary dimensions by lapping after cutting. If the dimensional accuracy of the cut wafer is improved, the polishing allowance in the lapping process can be reduced, which brings advantages such as a reduction in the lapping time and an improvement in the material yield. It has been conventionally said that the cause of poor accuracy in wire saw cutting is the change in groove pitch caused by the wire heated by the sliding of the abrasive grains and the work around the groove roller, and the resulting movement of the groove position. .

FIG. 4 shows an example of the structure of a conventionally used groove roller 50, in which a metal sleeve 40 in which a resin sleeve 25 is fitted to a bearing shaft 27 supported on the machine body side is concentrically fixed by a bolt 26. ing. The bearing shaft 27 is rotatably supported by a bearing 64, and one end of the metal sleeve 40 is rotatably supported by a bearing 41, so that the entire groove roller rotates. Since the groove roller is used in the environment where the abrasive liquid is scattered,
It is necessary to prevent the polishing liquid from entering the bearing portion, and air is blown from the air supply ports 42 and 63 to make the metal sleeve 40
The air is blown from between the cover 43 and the cover 43. Grooves are engraved on the outer peripheral surface of the resin sleeve 25 at a predetermined pitch, and both ends of the sleeve 25 are attached to the nut 6 mounted via the flange 40a of the metal sleeve and the holding plate 61.
It is tightened with 0. The reason why the groove is processed into the resin sleeve 25 is to suppress abrasion and cutting due to winding of the wire to which the abrasive grains adhere, and the resin having excellent abrasion resistance is selected. Although there is an example of using ceramics having good wear resistance instead of resin, resin is often used because the cost of grooving is high. When the heat of the wire is transmitted to the resin sleeve 25, the grooved surface and its vicinity expand in the axial direction. Since the linear expansion coefficient of resin is extremely large (10 to 20 times that of steel), the movement of the groove position in the vicinity of the end of the resin sleeve where the change in groove pitch is accumulated poses a problem. Therefore, a method for suppressing thermal expansion by cooling a resin sleeve has been proposed as described in Japanese Utility Model Application Laid-Open No. 58-59558 (Japanese Utility Model Application Laid-Open No. 56-152840).

By the way, the heat generation of the wire changes depending on the material of the work, and the length of the wire also changes depending on the sliding length of the work and the wire such as the sectional size. For example, in the case of a work having a circular cross section, the sliding length also changes due to the cutting process. Further, the factors that change the heat generation amount of the wire are complicated, such as the temperature change of the work as the cutting progresses, the miniaturization of the abrasive liquid used in circulation, and the change of the amount of the abrasive liquid supplied to the narrow cutting site. Therefore, as a practical matter, it is extremely difficult to control the cooling of the resin sleeve according to the amount of heat generated by the wire.

OBJECT OF THE INVENTION The present invention has been made under such a background, and an object thereof is to propose a method of stabilizing the groove position of the groove roller by a simple method to improve the cutting accuracy.

Configuration of the Invention The present inventor has conducted a detailed investigation focusing on the temperature change of the entire groove roller in the wire saw cutting, and as a result, in the wire saw in which the wire travels at a high speed in order to improve the cutting efficiency, the bearings 64 and 41 are used. It was found that the deterioration of the cutting accuracy due to the heat generated is transmitted to the resin sleeve 25 is a problem. As a result, the resin sleeve 2
5 is not directly cooled, but the temperature of the bearing portion, which is a heat generation source, is controlled to be constant, and thus the metal sleeve 4
The inventors have invented a method of keeping the distance between the flange 40a of the metal sleeve and the pressing plate 61 constant by keeping the temperature of 0 constant and thereby greatly improving the cutting accuracy.

That is, the gist of the present invention is to dispose a plurality of multi-groove rollers having a structure in which a resin sleeve is fitted around the outer circumference of a metal sleeve at a predetermined interval, and to wind a wire many times around the groove of the roller while running the material to be cut. Is a method of cutting by pressing a wire against a wire by a wire saw, wherein cooling oil is passed through the metal sleeve of the multi-groove roller, and the metal sleeve fixing bolt serving as the central axis of at least the multi-groove roller is fitted to the fixing bolt. While cooling the mounted metal sleeve and the bearings at both ends of the roller, measure the oil temperature after cooling at the exit side of the multi-groove roller, find the difference between the measured value and the set temperature, and determine the temperature difference in the oil supply system. According to this method, the oil temperature is controlled accordingly, and the oil having a predetermined temperature is cut while being supplied to the multi-groove roller.

The oil temperature is measured at the groove roller outlet side, the difference between it and the set temperature is calculated to control the oil temperature, and the temperature-controlled oil is supplied to the groove roller. Since a temperature difference inevitably occurs between the side and the side, it is necessary to control the temperature difference of the oil supplied to the groove roller in order to supply the oil to the groove roller at a predetermined temperature. This is to control the oil temperature in the tank to a predetermined temperature as quickly as possible.

Next, when cooling oil is passed through the groove roller to cool the roller, at least the metal sleeve fixing bolt 26, the metal sleeve 1, and the roller shown in FIG. 1 (an example of the structure of the groove roller for carrying out the method of the present invention) are shown. Bearings 6 at both ends
It is necessary to cool -1, 6-2. To cool the metal sleeve fixing bolt 26, the axial expansion of the metal sleeve 1 decreases due to thermal expansion of the metal sleeve fixing bolt 26, and in a remarkable case, play occurs to make the axial position of the metal sleeve 1 unstable. This is to prevent the cutting accuracy from being impaired.

Note that the resin sleeve is indirectly cooled because the metal sleeve is cooled, and therefore it is not necessary to directly cool the resin sleeve.

Hereinafter, the method of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing a structural example of a groove roller for carrying out the method of the present invention, and FIG. 2 is a schematic view showing an example of a temperature control system of the groove roller.

The groove roller shown in FIG. 1 is similar to the air blow type groove roller shown in FIG. 4, but the bearing portion is different due to the use of oil as the cooling medium.

That is, on the oil supply side of the groove roller, a lubricating oil passage 3-1 communicating with the main oil passage 2 is provided at the end of the metal sleeve 1 supported by the bearing 6-1 and the metal sleeve 1 and the bearing cover 4- are provided. A packing 5-1 is attached between the first and second parts to form a hermetically sealed structure. 26 is a metal sleeve fixing bolt. Further, on the oil outlet side, a bearing shaft 27 supported by a bearing 6-2 and a metal sleeve fixing bolt 26 are connected, and a lubricating oil passage 3-2 communicating with the bearing 6-2 is provided at the end of the metal sleeve 1. In addition to being provided, a packing 5-2 is attached between the metal sleeve and the bearing cover 4-2 to form a hermetically sealed structure.

In the case of the above structure, the oil supplied from the oil supply port 7 passes through the bearing 6-1 and the lubricating oil passage 3-1 and the main oil passage 2
To the bearing 6-2 through the lubricating oil passage 3-2 on the outlet side, and is discharged from the oil discharge port 8.

Next, the temperature control system shown in FIG. 2 will be described.

First, the oil is sucked / pressurized by the pump 11 from the oil tank 10 and supplied to the groove rollers A and B, and the oil that has left the groove roller is returned to the oil tank 10 again and is circulated and used. The oil tank 10 includes a stirrer 12 for equalizing the oil temperature in the tank, an electric heater 13 for adjusting the initial temperature, a water cooling tube 14 for oil cooling, and an oil thermometer 15. It has a control function. 16,
Reference numeral 17 is an oil thermometer provided near the oil discharge ports of the groove rollers A and B, 18 is an oil temperature control device in the oil tank 10, and 19 is a groove roller temperature control device. Reference numeral 20 is a pressure gauge, 21 is a pressure control valve, 22 and 23 are oil flow rate adjusting valves, and 24 is a cooling water flow rate adjusting valve.

That is, the oil whose temperature has been controlled to a predetermined temperature in the oil tank 10 is suctioned / pressurized by the pump 11 and controlled to a constant pressure by the pressure control valve 21, and each groove roller A,
It is supplied via the flow rate adjusting valves 22 and 23 distributed to B. . The oil supplied to the groove roller is the bearing 6 on the inlet side.
-1 → metal sleeve 1 → metal sleeve fixing bolt 26 →
While flowing through the bearing 6-2 on the outlet side, the bearing 6-1 on the inlet side,
The metal sleeve 1 and the bearing 6-2 on the outlet side are cooled and discharged from the oil outlet 8. At this time, the oil temperature is measured by the oil thermometers 16 and 17 provided in the vicinity of the oil discharge port, the difference between the set temperature and the groove roller temperature control device 19 is detected, and the temperature of the oil tank 10 becomes the set temperature. The oil temperature in the tank 10 is controlled by the oil temperature control device 18. At the same time, the oil temperature flow rate adjusting valves 22 and 23 are controlled to supply a predetermined flow rate of oil to the groove rollers A and B.

Example When the method of the present invention is applied to a unidirectional high-speed wire saw, the cutting conditions and cutting accuracy when 200 sheets of 8 inch diameter silicon ingots are simultaneously cut are shown in Table 1, and the transition of the bearing temperature near the oil discharge port is shown in Table 3. Each is shown in the figure.

As is clear from FIG. 3, in the conventional method without temperature control, it takes a long time for the temperature of the bearing to reach the saturation temperature, so that as shown in Table 1, the variation in the thickness of the wafer and the warp are large due to the elongation of the shaft.

On the other hand, according to the method of the present invention, since the heat generated in the bearing is directly absorbed by the oil, the temperature change of the entire bearing and groove roller is small, the wafer accuracy is improved, and the time for the bearing to reach the saturation temperature is short. The time from start of operation to start of cutting was shortened.

EFFECTS OF THE INVENTION As described above, according to the method of the present invention, the following effects are achieved.

(1) Rather than directly cooling only the resin sleeve, the temperature of the bearing, which is the heat generation source, is controlled to be constant, and by keeping the temperature of the metal sleeve constant, expansion of the metal sleeve in the axial direction is prevented. Since it is suppressed, the resin sleeve can be prevented from moving in the axial direction during the cutting process, and high cutting accuracy can be obtained.

(2) Since the resin sleeve is cooled by indirect cooling from the metal sleeve, the resin sleeve does not necessarily have to have a cooling structure. As a result, the cutting margin of the groove of the resin sleeve is not restricted, the frequency of replacement of the resin sleeve is extremely low, and it is economical.

(3) Since the cooling oil is supplied to the groove rollers after being controlled to a predetermined temperature, the time required for the groove rollers to reach the saturation temperature can be shortened, and the difference between the initial temperature and the saturation temperature becomes very small. Therefore, the wafer accuracy can be improved and the operating rate can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of the structure of a groove roller used for carrying out the method of the present invention, FIG. 2 is a schematic view showing an example of a temperature control system for the groove roller, and FIG. 3 is a bearing in an embodiment of the present invention. FIG. 4 is a cross-sectional view showing a conventional groove roller, and FIG. 5 is a schematic perspective view showing a cutting state by a wire saw as a target of the present invention. 1 ... Metal sleeve 2 ... Main oil passage 3-1, 3-2 ... Lubricating oil passage 4-1, 4-2 ... Bearing cover 5-1, 5-2 ... Packing 6-1, 6- 2 ... Bearing 7 ... Oil supply port 8 ... Oil discharge port 10 ... Oil tank 11 ... Pump 12 ... Stirring device 13 ... Electric heater 14 ... Water cooling tube 15, 16, 17 ... Thermometer 18 ...... Oil temperature control device 19 ...... Groove roller temperature control device 20 ...... Pressure gauge 21 ...... Pressure control valve 22, 23 ...... Oil flow rate adjustment valve 24 ...... Cooling water flow rate adjustment valve 25 ...... Resin sleeve 26 ...... Metal sleeve fixing bolt 27 …… Bearing shaft A, B …… Groove roller

 ─────────────────────────────────────────────────── ───Continued from the front page (56) References JP-A-60-80544 (JP, A) Actually opened 58-59558 (JP, U) Actually opened 52-17984 (JP, U) JP-B 52- 12954 (JP, B2) Actual public Sho 51-45038 (JP, Y2)

Claims (1)

[Claims] 1. A multi-groove roller having a structure in which a resin sleeve is fitted around an outer circumference of a metal sleeve is arranged at a predetermined interval, and a wire is wound around a groove of the roller a number of times to run the material to be cut. A method of cutting by pressing with a wire saw, wherein cooling oil is passed through the metal sleeve of the multi-groove roller, and at least a metal sleeve fixing bolt serving as a central axis of the multi-groove roller is fitted on the fixing bolt. Cool the metal sleeve and the bearings at both ends of the roller, and measure the oil temperature after cooling at the exit side of the multi-groove roller.
By the difference between the measured value and the set temperature, the oil temperature is controlled in accordance with the temperature difference in the oil supply system, and the oil having a predetermined temperature is cut while being supplied to the multi-groove roller. Cutting method.