TW201808514A - Leveling mount adjustment method for working machine and grinding processing method using the same - Google Patents

Abstract

The purpose of the invention is to provide a leveling-mount-adjustment method to improve processing accuracy of a working machine. According to the invention, the leveling-mount-adjustment method for a working machine supported horizontally by a plurality of leveling mounts, includes: a first step where an acceleration sensor is installed to the plurality of leveling mounts, an impulse hammer is used for hammering to vibrate each of the plurality of leveling mounts, and a response signal is received from the acceleration sensor; a second step where reference values of the plurality of leveling mounts are obtained from the response signals obtained in the first step; and a third step where at least one adjustment bolt of the plurality of leveling mounts is tightened or loosened according to ratios of the reference values respectively obtained in the second step, so as to adjust the plurality of leveling mounts.

Description

Method for adjusting leveling fixed seat of working machine and grinding processing using the same method

The present invention relates to a method of adjusting a leveling mount for a working machine and a method of grinding using the method.

A working machine for cutting or grinding is a device that cuts a workpiece by using the motion of either or both of the workpiece (the member to be processed) and the tool, and the workpiece is machined into a target shape. The lathe, the milling machine, and the like are representative. example. This kind of working machine is widely used in the processing of workpieces composed of various materials such as metal, wood, stone, and the like. Moreover, semiconductor wafers that require precision processing, etc., also perform work machine polishing in the manufacturing process.

An example of such a working machine is the so-called double-head grinding type working machine disclosed in Patent Document 1. The working machine disclosed in Patent Document 1 cuts a pair of grinding stones rotating at a high speed into the direction of the grinding stone axis while rotating the supporting workpiece, and simultaneously grinds the front and back sides of the workpiece by using the grinding surfaces of the end faces of the two grinding stones. .

In the double-head polishing type machine tool, as shown in Fig. 1 of the bed portion 40 as viewed from above, a leveling fixing seat is provided at six positions of the four corners and the center portion of the long side facing each other. Then, the adjustment screws of the leveling mounts are adjusted by the locking method or the like to perform leveling of the working machine. Also known as level adjustment, equalization). Hereinafter, an example of a method of adjusting the leveling mount performed in the past will be specifically described. For the convenience of explanation, regarding the position of the leveling mount in this example, as shown in Fig. 1, the lower left side of the figure is called P01, the upper left side of the figure is called P02, and the lower part of the figure is called P03. The upper part of the formula is called P04, the bottom right of the figure is called P05, and the upper right of the figure is called P06.

First, lock the adjustment screws of the leveling mounts at the three positions P02, P06, and P03, and adjust the horizontal direction in the left and right direction and the front and rear direction while using the leveler. After adjusting the horizontal direction of the left and right direction and the front and rear direction with these three points, the adjustment screws located at P01 and P05 are gently pressed but not horizontally displaced, and the adjustment screw of P03 is slowly released from P03. The position releases the load. At this point, a slight horizontal offset is produced. After that, the level shift is finely adjusted while viewing the level of the level. The levels are adjusted at four points P02, P06, P05, and P01, and it is confirmed that none of the four screws are released. Next, the adjustment screw of the position of the previously released P03 is slightly activated. Then, lock the adjustment screw at the P04 position to correct the tilt. In this way, after confirming that the horizontal direction and the front-rear direction are all horizontal, the nuts are locked to all the adjustment screws. As described above, the adjustment of the leveling mount is performed.

Advanced technical literature

Patent Document 1: International Publication No. 2004/033148

According to the above-described conventional technique, the semiconductor wafer is subjected to double-head grinding processing using a work machine that has been subjected to the adjustment of the leveling mount. As the double-head grinding process is repeated, the inventors have found that there are sometimes semiconductors. The case where the flatness of the wafer gradually deteriorates. In order to mass-produce a workpiece such as a semiconductor wafer that requires extremely high flatness, this deterioration will result in different product quality. The reason, not to let go.

The present inventors examined in detail the deterioration of the flatness, and confirmed that the center portion of the semiconductor wafer tends to have a convex shape as the double-head polishing process is repeated, and the height of the protrusion shape gradually increases the flatness. The deterioration has intensified. Here, in the case of the above-described double-head polishing type machine tool, for example, as shown in FIG. 2, the semiconductor wafer W is rotated in the circumferential direction in the processing chamber 50 at the center portion in the horizontal direction of the machine tool 1. The grinding of the semiconductor wafer is performed by rotating the grindstone 20 attached to the processing shaft 10 at a high speed from the both surface sides of the semiconductor wafer W and abutting against the semiconductor wafer W. Further, the bed portion 40 of the work machine 1 is horizontally supported by the leveling mount 30 placed on the floor of the floor F (hereinafter simply referred to as "ground").

The reason why the above-described flatness deterioration phenomenon occurs is as shown in the exaggerated diagram of FIG. 3, and it can be imagined that the rotation axis of the processing rotating shaft 10 is inclined with respect to the main surface of the semiconductor wafer W. The inventors further reviewed the cause of this tilting phenomenon, and the considerations are as follows. In the work machine 1 in the double-head grinding process, stress in the tensile direction is generated on the upper surface of the bed portion 40 due to the bending moment caused by the thermal expansion and the machining load, and the stress in the compression direction is generated in the lower surface of the bed portion 40. Further, by leveling the fixing base 30, the bed portion 40 is kept horizontal, and the load applied to the work machine 1 of each leveling fixing base 30 is somewhat uneven. For this reason, the inventors have observed that when the balance of the vertical resistance from the ground on which the work machine 1 is placed is broken, there is a possibility that the center portion of the bed portion 40 has a plurality of ridges (or the end portion of the bed portion 40). Sink), causing the processing shaft 10 to be tilted. From the above observations, the inventors thought that the above-described deterioration of the flatness may be caused by the load balance of the plurality of leveling mounts 30.

Here, as already explained, the conventional leveling mount adjustment only takes care of the level of adjustment, and does not take into account the balance of load due to the degree of lock of each leveling mount (ie, the balance of vertical resistance from the ground). ). In order to improve the unevenness of the machining accuracy of the work machine for cutting or polishing, it is necessary to establish a method of adjusting the leveling seat based on such a quantitative index considering the balance of the load, and the inventors have reconfirmed the problem. . Then, when the adjustment of the leveling mount of the machine tool is performed by the method of adjusting the level of the leveling seat, even if the workpiece is processed repeatedly, the deterioration of the flatness of the workpiece can be suppressed, and the result can be improved. The processing accuracy is not uniform. In addition, the adjustment method of the leveling mount can be established, and the present invention is not limited to the double-head type grinder, and can be applied to a cutting or grinding process including a machining shaft that is a horizontal axis. Working machine used.

Accordingly, it is an object of the present invention to provide a method of adjusting a leveling mount that can improve the machining accuracy of a work machine for cutting or grinding.

In order to solve the above problems, the inventors seriously conducted a review. The present inventors focused on a vibration model in a case where the floor F is assumed to be a spring in a system including a leveling mount 30, a bed portion 40 of a device body on which a predetermined load is placed, and a floor F (see FIG. 4). . The load applied to the leveling mount 30 is assumed to be M, and the spring constant of the floor F is assumed to be k. The natural vibration frequency of the spring is expressed by the following formula (1). Therefore, as the elastic constant k is larger, the natural vibration frequency n is larger.

Formula 1)

On the other hand, if the load to which the spring is applied is represented by P, the shape variable of the spring is represented by δ, and the elastic constant k is expressed by the following formula (2).

Here, in the case where the leveling mount 30 between the bed portion 40 and the floor F is adjusted, a change in the load M applied to the leveling mount 30, or even a change in the load P applied to the spring, is assumed The deformation of the floor corresponding to the spring variable δ is small. Therefore, as can be seen from the above formulas (1) and (2), if the load M applied to the leveling mount 30 is increased by adjusting the adjustment of the screw, the spring constant k of the floor F becomes large, resulting in a system. The natural vibration frequency n becomes higher.

Therefore, when the leveling mount 30 is tapped using the acceleration sensor and the stress wave hammer, and the response acceleration signal at the time of tapping is measured, and the reference value of the specific frequency domain on the side of the high-frequency wave is obtained, the reference value can be used as the reference value. The index indicating the degree of lock of the leveling mount 30 (the degree of lock is related to the load M applied to the leveling mount) is shown. As such a reference value, the acceleration value of the response acceleration signal or the value of the coherence function in the specific frequency domain can be used. Then, when the reference value is obtained for each of the plurality of leveling mounts, the load balance can be quantitatively evaluated from the ratio of these reference values. Then, the inventors found out that by adjusting this reference value, the leveling mount of the working machine can be appropriately adjusted. The inventors have learned that by such adjustment of the leveling mount, the cutting can be improved. The present invention has been completed by the inconsistency in the processing accuracy of the work machine for work or polishing. That is, the gist of the present invention is as follows.

(1) A leveling fixing seat adjusting method for a working machine for cutting or grinding, the working machine having: a plurality of leveling fixing seats, placed on the ground, adjusted by adjusting the locking of the screws The bed portion is horizontally supported by the plurality of leveling mounts; and the processing shaft is located above the bed portion and is oriented in a horizontal direction as a rotation axis. The method for adjusting the leveling fixture includes: in the first step, installing an acceleration sensor to the plurality of leveling fixing seats, and using the impact hammer to respectively perform a striking of the plurality of leveling fixing seats, from the acceleration The sensor measures the response acceleration signal; the second step determines the reference value of the plurality of leveling mounts from the response acceleration signal obtained in the first step; and the third step, based on the second The ratio of the reference values obtained in the step is respectively locked or loosened by at least one of the adjusting screws of the plurality of leveling mounts, thereby adjusting the plurality of leveling mounts.

(2) The leveling fixture adjusting method according to (1), wherein in the second step, frequency response analysis is performed on the response acceleration signal obtained from each of the plurality of leveling mounts The acceleration value in the peak acceleration frequency domain inherent to the leveling mount is used as the reference value.

(3) The method of adjusting the leveling mount according to (1), wherein in the first step, the vibration force signal of the hammer is further measured. In the second step, a coherence function is obtained from the vibration force signal obtained by each of the plurality of leveling mounts and the response acceleration signal, and the reference to the leveling fixture is referenced. The value of the coherence function in the frequency domain is taken as the reference value.

(4) The method of adjusting the leveling mount according to (3), The reference value is the average of the coherence function in the reference frequency domain.

(5) The method of adjusting a leveling mount according to any one of (2) to (4), wherein the machine tool is a double-head type work machine, and has two machining shafts arranged in opposite directions, The workpiece is held between the processing shafts at a central portion in the horizontal direction of the machine tool, and the workpiece is ground from both sides. The bed portion of the working machine is rectangular, and the leveling fixing seat is disposed at four corners of the rectangle of the bed portion and a central portion of the opposite long sides. In the third step, the reference value of the leveling mount of at least one of the center portions of the opposite long sides is adjusted to be higher than any of the leveling mounts of the four corners. The reference value is small.

(6) The method of adjusting the leveling mount according to (5), wherein the reference value of the leveling mount of both the center portions of the opposite long sides is adjusted to be equal to the level of the four corners This reference value of the mount is small.

(7) The method of adjusting the leveling mount according to (5) or (6), wherein the workpiece is a tantalum wafer.

(8) A polishing method for polishing the workpiece by using the double-head polishing type working machine adjusted by the leveling fixing method according to any one of (5) to (7).

According to the present invention, it is possible to provide a leveling mount adjusting method capable of improving the machining accuracy of a work machine.

1‧‧‧Working machinery

10‧‧‧ shaft

20‧‧‧磨石

30‧‧‧ Leveling mount

31‧‧‧ fixed seat

32‧‧‧Adjustment screws

33‧‧‧ nuts

40‧‧‧ Beds

50‧‧‧Processing room

F‧‧‧Floor

W‧‧‧Workpiece

Fig. 1 is a schematic view for explaining the position of a leveling mount of the prior art.

Fig. 2 is a schematic view for explaining a double-head type working machine of the prior art.

Fig. 3 is a schematic view showing the inclination of a rotating shaft for machining in the prior art.

Fig. 4 is a schematic view for explaining a vibration model of the present invention.

Figure 5 is a flow chart for explaining an embodiment of the present invention.

Fig. 6 is a schematic view showing a leveling mount of the double-head type working machine of the embodiment.

Fig. 7 is a graph showing the response acceleration signal measured in the preliminary experimental example 1.

Fig. 8 is a graph showing the coherence function measured in the preliminary experimental example 1.

Fig. 9 is a graph showing the average value of the acceleration in the preliminary embodiment 1 and the average value of the coherence function with respect to the locking angle of the adjusting screw, (A) showing the average value of the acceleration, and (B) showing the average value of the coherence function. .

Fig. 10 is a graph showing the ratio of the coherence function function values before and after the adjustment of the leveling mount of Experimental Example 1, (A) showing the graph before adjustment, and (B) showing the adjusted graph.

Fig. 11 is a graph showing the flatness of a tantalum wafer after polishing in the conventional example and the inventive example.

(Adjust the fixing method)

Hereinafter, the embodiment of the present invention will be described in more detail with reference to the flowchart of Fig. 5. The present embodiment is a method for adjusting a leveling mount of a working machine for cutting or grinding, the working machine comprising: leveling by adjusting the locking of the screw, and leveling the plurality of levels placed on the ground A fixed seat, a bed portion horizontally supported by the plurality of leveling mounts, and a processing shaft located above the bed portion and having a horizontal direction as a rotating shaft.

As a method of adjusting the leveling mount according to this embodiment An example of a working machine to be applied is the working machine 1 of the double-head polishing type described in the second drawing. The double-head grinding type working machine 1 includes: a plurality of leveling fixing seats 30 placed on the ground adjusted by locking of screws; a bed portion 40 horizontally supported by a plurality of leveling fixing seats 30; The processing shaft 10 above the bed portion 40 and having a horizontal direction as a rotation axis. With reference to this double-head grinding type working machine 1, the leveling fixing method according to the present embodiment will be specifically described below. However, in addition to the above-described machine tool 1, the applicant can understand that the so-called "horizontal axis type" cutting in which the machining direction of cutting or grinding is horizontal is included in the application of the leveling mount adjustment method of the present embodiment. Machines and grinders, lathes and milling machines (especially horizontal milling machines) are also suitable for this embodiment. In addition, as a working machine of the "longitudinal axis type", a double-head grinding disc in which the machining direction is a vertical direction disclosed in Japanese Laid-Open Patent Publication No. 2004-345049 can be exemplified.

According to the adjustment method of the leveling mount of the present embodiment, the first step (S10) is to install the acceleration sensor to the plurality of leveling mounts 30, and use a stress wave hammer to strike the plurality of leveling fixes. The seat 30 is oscillated to measure the response acceleration signal from the acceleration sensor; in the second step (S20), the plurality of leveling mounts 30 are respectively determined from the response acceleration signals obtained in the first step (S10). Reference value; in the third step (S30), at least one of the adjustment screws of the plurality of leveling mounts 30 is locked or loosened according to the ratio of the reference values obtained in the second step (S20). Adjust the plurality of leveling mounts 30. The details of each step are described in order below.

In the first step (S10), the acceleration sensor is attached to the plurality of leveling mounts 30, and the plurality of leveling mounts 30 are oscillated by tapping with a stress wave hammer. Then, the measurement is due to the vibration generated by this tapping. The response sensor's response to the acceleration signal. Here, at the time of tapping, it is not necessary to simultaneously mount the acceleration sensor to each of the plurality of leveling mounts 30, and the acceleration sensors can be sequentially mounted to the respective leveling mounts, and then sequentially knocked. Just hit it. Of course, it is also possible to mount the acceleration sensor simultaneously for all of the plurality of leveling mounts 30. There is no limitation on the order in which the plurality of leveling mounts 30 are struck.

Here, the tapping in this step is an action of performing a plurality of taps on each leveling mount. However, the number of strokes per leveling mount does not have to be the same. In this case, in order to suppress the influence of the noise, it is preferable to put a sufficient time after each tapping. When tapping again, the vibration force, the vibration speed, and the like can be set as general conditions.

In the second step (S20), the reference value of the plurality of leveling mounts 30 is obtained from the response acceleration signals obtained in the first step (S10). As a preferred aspect of the reference value obtained in this step, the first reference value and the second reference value will be described in order below.

The first reference value is an acceleration value in the frequency domain of the peak acceleration inherent to the leveling mount 30. In addition, the peak acceleration frequency domain refers to a specific frequency domain that generates a peak in the frequency domain on the high frequency side in the response acceleration signal. The specific frequency domain on the relatively high frequency side of the response acceleration signal can be used as an indicator for indicating the degree of lock of the leveling mount 30 because the vibration model has been considered. That is to say, in this peak acceleration frequency domain, the large acceleration value of a certain leveling mount 30 indicates the load applied to that leveling mount 30.

In order to obtain the first reference value, first, the frequency response of the response acceleration signal obtained by the tapping of each of the plurality of leveling mounts 30 is analyzed. Then, the peak acceleration frequency domain inherent in the fixed seat 30 will be leveled. The speed value is used as the first reference value. As such an acceleration value, the peak value of the acceleration in the peak acceleration frequency domain may be used, or the acceleration average value in the peak acceleration frequency domain may be used. When the average value of the acceleration is used, it may be obtained from the arithmetic mean of the peak acceleration frequency range, or a secondary average, a multiplied average, a harmonic average, or the like may be used.

Further, in order to define the peak acceleration frequency domain inherent to the leveling mount 30, it is preferable to perform the following preliminary steps in advance. In other words, an acceleration sensor is attached to any of the plurality of leveling mounts 30 (hereinafter also referred to as "selecting the leveling mount"), and the selection leveling mount is tapped with a stress wave hammer. The response sensor of the acceleration sensor performs frequency response analysis to obtain the first measurement result. Then, after the adjustment screw for selecting the leveling mount is locked or released, the frequency response in the different lock state is analyzed by tapping to obtain the second measurement result. By comparing the first and second measurement results, it is possible to determine the peak acceleration frequency domain inherent to the leveling mount that should be used as the first reference value. It is also possible to perform a tap in a state in which the lock state is changed again, and a peak acceleration frequency range is determined from three or more measurement results. In addition, the working machine 1 generally has the same type of leveling mount, and even if the same type of leveling mount other than the leveling mount is selected, the peak acceleration frequency range is the same as that of the selected leveling mount. Further, in the case of a work machine having different types of leveling mounts, it is preferable to perform the above-described preliminary steps for each type of leveling mount.

Next, the second reference value is a coherence function value of the reference frequency domain unique to the leveling mount 30. In addition, the reference frequency domain refers to a range suitable for the input and output of the evaluation system among the coherence functions obtained in the tap. The reason why the value based on the coherence function is used as the second reference value is as follows. In other words, in consideration of the vibration model described above, the value of the coherence function in the reference frequency domain on the high-frequency side can be used as an index indicating the degree of lock of the leveling mount 30, similarly to the first reference value. To use. Here, in general, γ ² is a graph showing the coherence function of causation input and output of the system can be the following formula (3) represents the coherence function γ ^2. The coherence function γ ² takes a value in the range of 0 or more and 1 or less. When the coherence function γ ² (f) is 1, it means that all the outputs of the system at the frequency f are caused by the measurement input, in the coherence function. When γ ² (f) is 0, it means that the output of the system at the frequency f is independent of the measurement input. Therefore, in the reference frequency domain, the large coherence function of a leveling mount 30 indicates the magnitude of the load applied to that leveling mount 30.

Where Wxy is the cross spectrum and Wxx and Wyy are the power spectra of x and y, respectively.

The above second reference value can be obtained as follows. First, in the first step (S10), in addition to the response to the acceleration signal, the vibration force signal of the stress wave hammer is further measured. Next, in the second step (S20), the coherence function according to the above formula (3) is obtained from the vibration force signal and the response acceleration signal obtained from the tapping of each of the plurality of leveling mounts 30. Then, the value of the coherence function in the reference frequency domain inherent in the leveling mount 30 is used as the second reference value. As the value in the reference frequency domain of the coherence function of the second reference value, the average value of the coherence function at the reference frequency can be used. It is also possible to use the arithmetic mean in the reference frequency domain as well as the average value of the acceleration. Square averaging, multiplying averaging, and harmonic averaging can be used.

Here, in order to define the reference frequency domain, it is preferable to perform the following preliminary steps in advance. That is to say, that is, the acceleration sensor is mounted on the selection leveling mount, and the selection leveling mount is tapped by the stress wave hammer, and the response acceleration signal from the acceleration sensor and the stress wave hammer are excited. The first coherence function is obtained in the signal. Then, after locking or loosening the adjusting screw for selecting the leveling mount, the second coherence function in different locking states is obtained by tapping. Comparing the first and second coherence functions, the reference frequency domain of the coherence function to be used as the second reference value can be determined. It is also possible to perform a tap in a state where the lock state is changed again, and the reference frequency domain is determined from three or more coherence functions. Whether or not the reference frequency domain determined in this way can be applied to other leveling mounts is related to the type of the leveling mount of the machine tool 1, which is also the same as in the case of the first reference value.

Further, the first and second reference values described above are examples, and reference values different from the first and second reference values may be obtained from the response acceleration signal and other signals.

Finally, in the third step (S30), at least one of the adjustment screws of the plurality of leveling mounts 30 is locked or loosened according to the ratio of the reference values obtained in the second step (S20). This adjusts the plurality of leveling mounts 30. Depending on the characteristics of the working machine, the reference value of the leveling mount from a specific position is adjusted to be larger or smaller than the leveling mount from other positions, or to satisfy the predetermined ratio condition. By adjusting the leveling mount 30 in this manner, the machining accuracy of the machine can be improved.

The double-head grinding type working machine 1 which has been described is taken as an example, and a specific aspect of the adjusting method according to the present embodiment is explained. As already stated As shown in Fig. 2, in the double-head grinding type working machine 1, two processing shafts 10 arranged in the opposing direction are arranged, and the workpiece W is held between the machining shafts 10 in the horizontal direction of the center of the machine tool 1, Grind the workpiece on both sides. Then, the bed portion 40 of the work machine 1 is rectangular, and the leveling mount 30 is disposed at the four corners of the rectangular shape of the bed portion 40 and the central portion of the long side facing each other (refer to the first drawing described above).

According to the adjustment method of the present embodiment, in the case of the work machine 1, in the third step (S30), the reference value of the leveling mount 30 of at least one of the central portions of the opposite long sides is It is preferable to adjust it to be smaller than the reference value of any of the four levels of the leveling mounts 30. When the position of the leveling mount P01 to P06 shown in Fig. 1 is used, one of the reference values of the leveling mounts of the positions of P03 and P04 is adjusted to be larger than that of P01, P02, P05, and P06. The reference value of the leveling mount of the position is preferably small. Even in the case of any of the first and second reference values, the load is mainly applied to the four corners of the bed portion 40, and the load is not applied to the center in the horizontal direction. The state of the department. Thereby, it is thought that the inclination of the processing rotating shaft 10 demonstrated in FIG. 3 can be prevented.

Further, in order to surely obtain this tilt preventing effect, it is preferable to adjust the reference value of the leveling fixing base 30 of both the center portions of the opposite long sides to be smaller than the reference value of the leveling fixing base 30 of the four corners.

Specific aspects according to this embodiment will be described below.

The workpiece to be subjected to cutting or polishing is arbitrary, but it is preferable to use a semiconductor wafer that requires precision machining, in particular, a silicon wafer as a workpiece.

Acceleration sensors and stress-wave hammers (sometimes referred to as "impact hammers") can use commercially available products to detect responses from acceleration sensors. The speed signal and the vibration force signal of the hammer can also be measured using a commercially available FET analyzer or a frequency characteristic analyzer.

In order to suppress the influence of any one or both of the vibration force signal or the response acceleration signal measured in the first step (S10), it is preferable to perform a plurality of taps in the first step (S10). It is preferable to perform knocking 5 times or more, and it is more preferable to perform tapping 10 times or more. There is no limit to the upper limit of the number of strokes.

The surface material of the leveling mount 30 in contact with the ground is arbitrary and is not limited at all. A member made of metal such as stainless steel can be used, and a member made of rubber can also be used. However, in consideration of the fact that the value of the coherence function varies depending on the degree of locking of the adjusting screw, the present embodiment is preferably used for a horizontally supported working machine that is horizontally supported by a metal leveling mount.

Further, in the above-described embodiment, the double-head grinding type working machine 1 will be specifically described. However, the object to be applied to the leveling fixing method according to the present embodiment is of course not limited to the above. Only applicable to the above work machine 1.

(grinding method)

According to the polishing method of the present embodiment, the workpiece W is polished by using the double-head polishing type working machine 1 adjusted by the above-described leveling fixing method.

Hereinafter, the present invention will be described in more detail by way of examples, but the invention is not limited to the following examples.

(Preparatory Experimental Example 1)

In order to confirm the acceleration of the index of the degree of the lock of the leveling mount of the double-head grinding device (DXSG320; Koyo Machinery Industry Co., Ltd.) The following preliminary experiments were carried out in the frequency domain and the reference frequency domain of the coherence function. When the double-head polishing apparatus is schematically displayed, the reference numerals of the respective components of the machine tool 1 will be referred to below in the same manner as the second drawing. Moreover, the installation position of the leveling mount 30 is also referred to in the first figure already described. A schematic view of the leveling mount 30 of this double-headed grinding apparatus is shown in FIG. The leveling mount 30 is composed of a fixing base 31 on the surface of the floor F, an adjusting screw 32, and a nut 33 between the fixing base 31 and the adjusting screw 32. Further, the fixing base 31, the adjusting screw 32, and the nut 33 are all made of stainless steel. Although not shown, the bed portion 40 of the double-head polishing apparatus is threaded to adjust the shaft of the screw 32 to the groove of the bed portion 40 to be locked. Further, the bed portion 40 is completely fixed by the nut 33. This work machine 1 adjusts the leveling mount using the conventional technique described, and confirms that the level is obtained in the left and right direction and the front and rear direction.

First, the acceleration sensor is mounted to the leveling mount 30 at the position of P02, and the adjusting screw 32 is completely loosened to bring the bed portion 40 into contact with the fixed seat 31. Assume that this state is referred to as "screw lock angle" of 0°. In this state, an impact hammer (model: 086D05; manufactured by PCB Piezotronics) and an acceleration sensor (model; 356A16; manufactured by PCB Piezotronics) were used to strike 20 times of this adjustment screw, and then the FFT analyzer was used. : NR-600; KEYENCE company, analysis software: WAVE LOGGER PRO; KEYENCE company) to analyze the frequency response of the acceleration signal, and find the coherence function. The results are shown in Fig. 7(A) and Fig. 8(A), respectively. The acceleration signal after the frequency response analysis in Fig. 7(A) is an average of 20 times, and the coherence function in Fig. 8(A) is a value obtained from 20 taps.

Then, the screw locking angles are sequentially 25°, 50°, 75°, The order of 100° is locked. At each locking angle, 20 times of tapping is performed in the same manner as when the screw locking angle is 0°, and the frequency response of the acceleration signal is analyzed, and the coherence function is obtained at the same time. The frequency response analysis and the coherence function when the screw lock angle is 25° are shown in Fig. 7(B) and Fig. 8(B), respectively. Similarly, the frequency response analysis and the coherence function when the screw lock angle is 50° are shown in the 7th (C) and 8th (C) diagrams, respectively, and the frequency response analysis and coherence function when the screw lock angle is 75°. The frequency response analysis and the coherence function when the screw locking angle is 100° are shown in the 7th (D) and 8th (E) diagrams, respectively.

From the seventh (A) to (E) diagrams, it can be confirmed that the peak of the response acceleration is generated in the vicinity of 10000 Hz (9000 to 11,000 Hz). Further, from the eighth (A) to (E), it can be seen that the coherence function rises between 8000 and 14000 Hz. Therefore, 9000~11000Hz is used as the peak acceleration frequency domain, and 8000~14000Hz is used as the reference frequency domain of the coherence function. The average value of the acceleration in the peak acceleration frequency range of 9000 to 11000 Hz (arithmetic average, the same below) is shown in Fig. 9(A) with respect to the screw locking angle. Further, a graph of the average value of the coherence function in the reference frequency domain of 8000 to 14000 Hz (hereinafter also referred to as "coherence function value") with respect to the screw locking angle is shown in Fig. 9(B).

As can be seen from Fig. 9(A), as the angle of the screw locking increases, that is, the locking of the adjusting screw is tightened, the average value of the acceleration in the peak acceleration frequency range rises. Similarly, as can be seen from the figure 9(B), the value of the coherence function in the reference frequency domain becomes larger as the locking of the adjustment screw is tightened. Therefore, it is possible to quantitatively grasp the lock state of the leveling mount by using the average value of these accelerations and the value of the coherence function.

(Example 1)

First, the lock state of the leveling mount of the double-head polishing apparatus (DXSG320; Koyo Machinery Industry Co., Ltd.) used in the preliminary test example 1 was returned to the state before the preliminary experiment example 1. Each of the leveling mounts 30 at the positions of P01 to P06 was subjected to the same 20 taps as in the preliminary test example 1. Find the coherence function in the reference frequency domain of 8000~14000Hz. Then, the maximum coherence function value P02 among P01 to P06 is used as a reference, and the ratio of each of P01 and P03 to P06 to the coherence function value of P02 is obtained. The results are shown in Figure 10(A).

In this state, 30 wafers (300 mm in diameter and an average thickness of 880 μm) were subjected to double-head grinding until the thickness was 830 μm. Further, after the double-head polishing process of the fifteenth wafer, the processing was temporarily stopped, and a predetermined time interval was placed. GBIR (abbreviation of Global Backside Ideal Focal Plane, which is defined in the SEMI specification) for each polished tantalum wafer is measured using a flatness measuring device (WaferSight; manufactured by KLA-Tencor Co., Ltd.). The GBIR of each of the polished wafers is shown in Fig. 11. In addition, the double-head polishing processing of the first to the 30th sheets is referred to as a "conventional example" for convenience. As shown in Fig. 11, in the conventional example, as the double-head grinding process progresses, the deterioration of GBIR is seen. Further, when the shape of each of the wafers was confirmed, it was found that the central portion of the wafer was formed in a convex shape.

Here, the coherence function values of P03 and P04 are larger than the other four corners (P01, P02, P05, P06). In this state, the four corners of the bed portion 40 are relatively easily recessed, and the inventors believe that the processing shaft 10 is suitable. It may be tilted as a result. Therefore, the leveling mounts of the four corners (P01, P02, P05, P06) The adjustment screws of 30 are locked and adjusted to 10°. After the adjustment, the leveling mounts 30 at the positions of P01 to P06 are tapped 20 times again to obtain a coherence function in the reference frequency range of 8000 to 14000 Hz. Then, the maximum coherence function value P06 among P01 to P06 is used as a reference, and the ratio of each of P01 to P05 to the coherence function value of P06 is obtained. The results are shown in Figure 10(B).

Thereafter, in the same manner as before the adjustment, the double-head polishing processing of the 15 wafers was performed. That is, the adjusted first sheet processing is the processing of the 31st sheet in the total number of sheets in the first embodiment, and the total of 30 sheets before the adjustment are performed, and a total of 45 sheets of tantalum wafer are subjected to double-head polishing. It is assumed that the double-head polishing processing from the 31st to the 45th sheets of the total number of sheets is referred to as an "invention example". The ground germanium wafer GBIR was measured in the same manner as before the adjustment. The GBIR of each of the polished wafers is shown in Fig. 11. As shown in Fig. 11, after the adjustment of the leveling mount, the GBIR was significantly lowered, and the deterioration tendency seen before the adjustment was not observed, and it was confirmed that the value of GBIR was stable.

As a result of the above, it is presumed that before the adjustment of the leveling mount (conventional example), the load during machining is applied to the direction in which the central portion of the bed portion 40 is bent upward by the processing shaft 10 . Resisting this force is the rigidity of the bed 40 itself and the support it receives from the ground. In the example of the present invention, the support force (vertical resistance) received from the ground is changed by the adjustment of the leveling mount, and thus the flatness (GBIR) of the wafer is stabilized. Further, according to the results of this experiment, even if other working machines (having the leveling mounts disposed at the same position as the double-head grinding apparatus used in the first embodiment), the support force of the center of the working machine is adjusted to be more Small is better.

Further, in the first embodiment, the average value of the coherence function in the reference frequency domain is used, but even the peak acceleration obtained in the preliminary embodiment 1 is used. The average of the acceleration in the frequency domain can of course also be adjusted for the leveling mount. It is preferable to use the coherence function as in Experimental Example 1 in consideration of the vibration of the apparatus environment.

According to the present invention, it is an object of the invention to provide a leveling fixing seat adjusting method capable of improving the machining accuracy of a working machine.

Claims (9)

A leveling fixing seat adjusting method for a working machine for cutting or grinding, the working machine is provided with: a plurality of leveling fixing seats, which are placed on the ground and adjusted by adjusting the locking of the screws; the bed part And horizontally supported by the plurality of leveling mounts; and the processing shaft located above the bed and in a horizontal direction as a rotation axis, the leveling mount adjustment method includes: the first step, the acceleration sensing The device is mounted to the plurality of leveling mounts, and the plurality of leveling mounts are separately vibrated by the impact hammer, and the response acceleration signal is measured from the acceleration sensor; the second step, from the first The response acceleration signal obtained in the step respectively obtains a reference value of the plurality of leveling mounts; and the third step, locking or loosening according to the ratio of the reference values respectively obtained from the second step At least one of the plurality of adjustment screws of the leveling mount, thereby adjusting the plurality of leveling mounts. The method for adjusting a leveling fixture according to claim 1, wherein in the second step, frequency response analysis is performed on the response acceleration signal obtained from respective taps of the plurality of leveling mounts. The acceleration value in the peak acceleration frequency domain inherent to the leveling mount is used as the reference value. The method for adjusting a leveling seat according to the first aspect of the invention, wherein in the first step, the vibration force signal of the hammer is further measured, and in the second step, the leveling is fixed from the plurality The respective taps of the seat The obtained coercive force signal and the response acceleration signal are obtained as a coherence function, and the value of the coherence function in the reference frequency domain unique to the leveling mount is used as the reference value. The method of adjusting a leveling fixture according to claim 3, wherein the reference value is an average value of the coherence function in the reference frequency domain. The method for adjusting a leveling fixture according to any one of claims 2 to 4, wherein the working machine is a double-head grinding type working machine, and the two rotating shafts for processing are arranged in opposite directions, and the processing shaft is used Holding the workpiece in a horizontal direction central portion of the working machine, grinding the workpiece from both sides, wherein the bed portion of the working machine is a rectangle, and the leveling fixing seat is disposed at four corners of the rectangle of the bed portion and In the third step of the opposite long side, in the third step, the reference value of the leveling fixing seat of at least one of the center portions of the opposite long sides is adjusted to be higher than the leveling of the four corners. The reference value of any of the seats is small. The method for adjusting a leveling mount according to claim 5, wherein the reference value of the leveling mount of both the center portions of the opposite long sides is adjusted to be equal to the level of the four corners. This reference value of the mount is small. The method of adjusting a leveling fixture according to claim 5, wherein the workpiece is a silicon wafer. The method of adjusting a leveling fixture according to claim 6, wherein the workpiece is a silicon wafer. A grinding processing method for grinding a workpiece by using the double-head grinding type working machine adjusted by the leveling fixing seat adjusting method according to any one of claims 5 to 8.