JP3466374B2 - Polishing apparatus and polishing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing apparatus and a polishing method, and more particularly to a polishing apparatus and a polishing method used for flattening the surface of an insulating film or a conductive film forming a semiconductor element.

[0002]

2. Description of the Related Art The degree of integration of semiconductor devices such as semiconductor memory devices has been increasing year by year, and the number of wiring layers of their internal circuits has been further increased. In order to make the wiring multi-layered, chemical mechanical polishing (hereinafter, CMP (chemical mechanical polishi
ng) technology is used to planarize the interlayer insulating film on the wiring. In the CMP technology, the end point of polishing and the automation are emphasized from the viewpoint of time and cost.

However, regarding the end time of the polishing,
Since the polishing rate cannot be kept constant due to deterioration of the polishing cloth and the like, it has not been possible to make a precise determination even with time control. Therefore, until now, the work of polishing for a short time, stopping the polishing and observing the polishing state of the object to be polished was repeated until a flat surface was obtained. Such a method is not practical because it takes time and labor.

The detection of the end point of CMP has hitherto been carried out by detecting a change in the torque of a motor for rotating a surface plate (also referred to as a head) and monitoring the frictional resistance of the polishing surface based on the change. However, since this method has no high-frequency component, it only obtains the positional and temporal average of the rubbing frictional force of the polishing surface, and therefore has poor sensitivity and may not be usable depending on the structure of the head. For example, in an air bag system having a structure in which a head and a housing are joined by an elastic body, the influence of friction on the polishing surface is less likely to be transmitted to the rotating shaft, and the sensitivity is significantly reduced, which is not practical.

There is also a method of measuring the polishing object with an optical film thickness meter to detect the end point, but it cannot be detected in real time. Further, when the silicon nitride film and the SiO ₂ film are simultaneously polished, the polishing film thickness cannot be accurately measured with an optical film thickness meter. Therefore, it has been proposed in Japanese Patent Laid-Open Nos. 6-320416 and 6-45299 to detect the end point of polishing based on changes in the rotation torque of the motor and the vibration of the surface plate. However, in these publications, it is not whether the polishing surface is simply flattened, but polishing progresses and foreign materials are exposed to the polishing surface, which changes the frictional resistance of the polishing surface and changes the vibration. The end point is the time point.

Further, there is a method of measuring the strain of the surface plate due to the friction between the polishing surface and the polishing cloth with a strain sensor.
It is described in Japanese Patent Publication No.

[0007]

However, in a polishing apparatus using a strain sensor, since vibration generated by polishing is small, mechanical vibration (sound) such as motor vibration of the polishing apparatus is mixed as background noise. Sufficient sensitivity cannot be obtained. As a result, it is difficult to accurately detect the polishing state of the entire area of the polishing surface or to detect the end point, and additional polishing is required after basic polishing is completed.

When the strain sensor measures the strain of the head caused by the friction between the polishing surface and the polishing cloth, the strain is not so large as to appear in the strain sensor. Moreover,
Even if the vibration of the polishing apparatus itself is reduced by the filter, the distortion sensor cannot detect the change of the unevenness of the wafer surface. This is because the strain sensor is not sensitive to high vibration frequencies.

In the conventional polishing apparatus, since there is no objective index regarding the timing of dressing or replacement of the polishing cloth, it is apt to perform unnecessary work. Further, even if the polishing surface is scratched by dust (foreign matter) during polishing, the existence of scratches can be recognized only by taking out the object to be polished after the polishing and observing the polishing surface with a microscope. C
No measures have been taken against the generation and mixing of dust during polishing by MP, and it was indirectly evaluated by observing scratches on the polished surface.

On the other hand, conventionally, since the polishing evaluation is carried out after the polishing is completed, even if dust is mixed in the initial stage of one lot (usually about 25 sheets) and the surface of the object to be polished is scratched, I didn't notice the mixing of dust until one lot was completed. For this reason, the object to be polished, which is to be polished later after dust that damages the polishing surface is inevitably scratched, wastes the object to be polished such as a semiconductor wafer. In addition, a part of the scratched polishing surface may be lost to become dust, and the dust may further increase.

Further, even if dust is present during polishing, its location cannot be specified. Therefore, the entire polishing cloth may be replaced in order to remove the dust. In such a case, it takes time and effort. . Further, in the above-mentioned patent publication,
It is described that the signal for detecting the platen vibration is transmitted from the top of the platen to the amplifier.However, if the signal is transmitted wirelessly, the shaft of the motor for rotating the platen is used. The wireless signal is temporarily interrupted.

Incidentally, the polishing amount depends on the shape of the pattern, and also greatly changes depending on the polishing conditions such as the pressing force, the number of revolutions, the flow rate of the polishing liquid, and the surface condition of the polishing cloth. Therefore, when the polishing amount is controlled by time, trial polishing is performed once for each lot to check the polishing rate, but this takes time. Moreover, when polishing is performed on a plurality of types of lots having different patterns, the time taken for trial polishing increases and throughput decreases.

An object of the present invention is to detect vibration during polishing with high sensitivity to accurately detect variations in polishing, and to detect in real time to shorten polishing time, and to easily confirm the presence of dust. It is also an object of the present invention to provide a polishing apparatus and a polishing method capable of wirelessly transmitting the vibration of a surface plate normally and improving the ability of detecting the vibration peculiar to polishing used to detect the polishing state. And

[0014]

[Means for Solving the Problems]
As illustrated in FIG. 22 and the like, the first for supporting an object to be polished
Surface plate 3, a first drive mechanism 21 for rotating the first surface plate 3, a second surface plate 2 arranged to face the first surface plate 3, and the second surface plate 2. A polishing cloth 1 attached to a surface plate 2 and a vibration detector 10 (1 attached to the first surface plate 3 or the second surface plate 2 to detect vibration during polishing.
0A, 10B), and a controller 17 for controlling the polishing operation of at least one of the first surface plate 3 and the second surface plate 2.
When the vibration intensity detected by the vibration detector 10 is subjected to frequency analysis, the vibration intensity is further integrated every hour, and when the temporal change of the integrated value is below a reference value, or the integrated value is a reference value. And a signal analysis unit 15 that sends a polishing stop signal to the control unit to stop at least one of the first surface plate and the second surface plate at any point when To solve the problem.

In the above polishing apparatus, an elastic body 7 is formed around the first surface plate.
In the above polishing apparatus, a groove 4 or a hole is formed on the surface of the polishing cloth 1, and a cavity 6 that resonates with the vibration of the surface is formed inside the polishing cloth 1.

In the above polishing apparatus, the vibration detector 1
A plurality of band pass filters 34b having different center frequencies are combined and connected to the output end side of 0A. In the above polishing apparatus, as illustrated in FIG. 16, a signal analysis unit 33 that determines whether polishing has started, stopped polishing, or has satisfied polishing conditions, and the vibration detector 1
The transmitter 13 for wirelessly transmitting the vibration information of polishing detected by 0, the wireless signal output from the transmitter 13 is received, and the variation of the tuning frequency of the wireless signal is automatically adjusted within the range of the reference frequency. And a receiver 32 for receiving the oscillation frequency of the transmitter 13 by the automatic frequency control mechanism each time the signal analysis unit 34 requests reception data. To solve the problem.

In the above polishing apparatus, the vibration detector 1
0 is an element for detecting vibration in the longitudinal direction or the circumferential direction. In the polishing apparatus, as illustrated in FIG. 22, a plurality of the vibration detectors 10A and 10B are attached to a target with respect to the rotation center of the first surface plate 3, and a plurality of the vibration detectors 10A and 10A are provided. It is characterized in that arithmetic units 37 and 38 for obtaining the sum or difference of the output signals of 10B are connected to the output terminals of the plurality of vibration detectors 10A and 10B.

In the above polishing apparatus, as illustrated in FIG. 34, the vibration detector 59 is provided with a vibration converting means 59 for converting the vibration frequency detected by the vibration detector 10 into the resonance frequency of the vibration detector 10. It is characterized by being connected to. In the polishing apparatus, as shown in FIG.
Of the through-holes 54 formed in the first surface plate 3 and the inner sheet 51 and supported by the surface plate 3 of
It is characterized by having a vibration transmitter 55 which is in contact with both the object to be polished W and the vibration detector 10 through the inside.

In the above polishing apparatus, the second platen 3
Includes a second drive mechanism M for rotating the second surface plate 3.
Are connected, the first surface plate 2 has a first natural vibration frequency that is the same as the vibration frequency to be detected by the vibration detector 10, and the first drive mechanism 21 and the second At least one of the driving mechanisms M has a second natural vibration frequency different from the first natural vibration frequency.

[0020]

[0021]

[0022]

[0023]

The problems noted above, as illustrated in FIGS. 1-10, a first platen for supporting a polishing object, a second constant which is disposed opposite to the first surface plate In a polishing method for polishing an object to be polished with the polishing cloth by using a disk and a polishing cloth attached to the second surface plate, a vibration detector is used for the first surface plate or the second surface plate. The vibration during polishing of the surface plate was detected, the vibration intensity output from the vibration detector was frequency-analyzed, and the vibration intensity was integrated every hour, and the temporal change of the integrated value was below the reference value. The polishing method is characterized in that polishing is stopped at any time, or when the integrated value falls below a reference value.

In the above polishing method, the integrated value is an average value of a plurality of vibration intensities. In the above polishing method, a film formed on the object to be polished and having irregularities on its surface is planarized by the polishing cloth. In the above polishing method, deterioration of the polishing cloth is recognized by either the time from the start of polishing to the stop of polishing being shorter than a set time or the time change of the integral value being decreased beyond a specified value. It is characterized by doing.

In the above polishing method, during the polishing time,
The polishing condition is changed by detecting that the reduction rate of the vibration intensity of a specific vibration frequency is higher than the reduction rate of the vibration intensity of another vibration frequency. In the above polishing method, based on a change in a vibration intensity signal or a vibration spectrum output from the vibration detector, a polishing state is analyzed in real time to detect a polishing end point, or polishing conditions are changed. .

[0027]

[0028]

[0029]

(Operation) According to the present invention, the vibration information obtained from the vibration detector is frequency-analyzed, and the vibration intensity at that frequency is integrated every time, and when the integrated value falls below the reference value, or Since the polishing is stopped by the signal analysis means that sends a signal to stop polishing at any time when the temporal change of the integrated value falls below the reference value, it becomes easy to detect the end point of polishing.

In the signal analysis means, either the time from the start of polishing to the stop of polishing is shorter than the set time, or the time change of the integrated value is decreased beyond the specified value, the polishing cloth is reduced. Since the signal indicating the deterioration signal is output, it is easy to determine whether the polishing is finished or the polishing cloth is deteriorated, and the optimum polishing operation is performed. During polishing, if the reduction rate of vibration intensity at a specific vibration frequency is higher than the vibration intensity at other vibration frequencies, it has been experimentally confirmed that polishing is not performed uniformly. Optimum polishing is performed by detecting such attenuation of the vibration intensity and changing the polishing conditions to change the polishing conditions so that the polishing becomes uniform.

Further, in a polishing apparatus having a structure in which a first surface plate supporting an object to be polished and a rotational force transmitting mechanism are connected via an elastic body, a vibration detector is attached to the first surface plate. Therefore, the vibration peculiar to the rotational force transmission mechanism is absorbed by the elastic body, and the noise when detecting the vibration of the polishing object is reduced. This makes it possible to detect the polishing end point more quickly and accurately.

Further, since the mechanism for inducing vibration during polishing is formed on the polishing cloth, the vibration intensity of the vibration generated during polishing increases and the vibration frequency band that can be detected by the vibration detector becomes wider. Facilitates precise control of polishing conditions and detection of polishing end point. As such a mechanism, there is one in which a plurality of grooves are formed in a polishing cloth and vibration is induced in a region surrounded by the grooves.

In this case, when a cavity is formed inside the polishing cloth or the surface plate, the induced vibration during polishing is amplified, and it becomes easy to grasp the change in the vibration intensity for vibration detection. Furthermore, the amount of vibration attenuation by the vibration detector during polishing is grasped as an effective value, and the change of this effective value is measured every hour, and the integrated value of the change or the amount of change for a certain time becomes zero or more. The time point at which the polishing is completed may be used as the end point of polishing.

[0035]

[0036]

Further, according to the present invention, since the automatic frequency control mechanism is used when a plurality of polishing operations are simultaneously performed and the polishing information is wirelessly transmitted and received, stable reception is achieved even if the transmission frequency fluctuates due to temperature change. The state is obtained .

According to another aspect of the present invention to [0038] of al, in the structure interior having an upper surface plate of the air bag type, which is vibration damping from the housing to be kept confidential in the cavity, so as to detect the vibration in the circumferential direction Such a vibration detector is attached to the upper surface plate, and polishing is completed by changing the vibration intensity or vibration spectrum signal output from the vibration detector. According to this, it becomes easy to judge the change of the polishing state by knowing the vibration intensity of the air bag type upper surface plate in the rotation direction and the change of its spectrum.

When the signal from the vibration detector is output to the control unit through the bandpass filter, the vibration component depending on the vibration of the frequency unique to the polishing apparatus is removed according to the polishing apparatus and polishing conditions. Then, only the vibration generated by the actual polishing can be selected .

When the output signal from the vibration detector is small, the output signal can be increased by connecting a plurality of vibration detectors. Moreover, the number of vibration components that you do not want to detect with these multiple vibration detectors increases,
By selecting the orientation and arrangement of the vibration detector so that the unnecessary vibration components cancel each other and the necessary vibration components are added, noise due to unnecessary vibration components is reduced and the S / N ratio is improved. it can.

Further, according to another aspect of the present invention, when the vibration detector detects the vibration of the object support plate which changes with the progress of polishing, a soundproof material is arranged around the vibration detector. Therefore, the S / N ratio can be improved by suppressing the input of the background noise of the motor or the like to the vibration detector.
Further, when the vibration detector detects the vibration of the object support plate that changes with the progress of polishing, the frequency of the vibration to be detected is converted to the maximum sensitivity frequency of the vibration detector. The N ratio can be improved.

Further, when the vibration detector detects the vibration of the polishing object supporting plate which changes with the progress of polishing, the vibration plate having the natural vibration frequency which is the same as the vibration frequency to be detected is supported on the polishing object. Since it is interposed between the board and the vibration detector, the detected vibration inputted to the vibration detector can be resonated and amplified, and the S / N ratio is improved. Also,
When detecting the vibration of the object support plate that changes with the progress of polishing with the vibration detector, since the vibration transmitter that penetrates the object support plate and comes into contact with the object to be detected is provided, The efficiency of vibration transmission from the object to be polished to the vibration detector is improved, and the S / N can be improved.

Further, when the vibration detector detects the vibration of the object support plate which changes with the progress of polishing, the supply of energy for driving the object support plate is temporarily stopped at the time of detection. Therefore, the background noise can be significantly reduced and the S / N ratio can be improved. In addition, when detecting the vibration of the object supporting board that changes with the progress of polishing with the vibration detector, the vibration frequency to be detected and the vibration frequency of the background noise are made different, and Since the natural vibration frequency and the vibration frequency to be detected are the same, the S / N ratio can be improved.

Further, when the vibration detector detects the vibration of the object supporting plate which changes with the progress of polishing, the vibration plate vibrating in a phase opposite to the background noise is used for the object supporting plate and the vibration detector. Since it is interposed between them, the input of background noise to the vibration detector can be eliminated and the S / N ratio can be improved. Also, when the vibration detector detects vibration of the workpiece support plate that changes as the polishing progresses, multiple vibration detectors can be attached on the specific polishing object support plate to enable selection. You can reduce the trouble of replacement by.

[0045]

Since the present invention employs techniques such as increasing the vibration peculiar to polishing and improving the S / N ratio, the polishing end point detection of a wafer having no foreign matter for detecting the polishing end point is performed. It becomes easy to judge such as.

[0047]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a configuration diagram showing a main part of a polishing apparatus according to a first embodiment of the present invention. The polishing device is a motor M
It has a disk-shaped lower surface plate 2 which is rotated by and a disk-shaped upper surface plate 3 which supports an object W to be polished through a suction pad (not shown). The lower surface plate 2 and the upper surface plate 3 each have one or more cavity parts 2a and 3a each having a cavity.
Are formed. Further, on the lower surface plate 2, the polishing cloth 1 that is in contact with the object W to be polished is attached.

The polishing cloth 1 is made of urethane foam, for example, and has a two-layer structure. On the upper layer portion of the polishing cloth 1, first grooves 4 having a depth of about 2 mm are formed at a plurality of places as shown in FIGS. 2 (a) and 2 (b). The rectangular region surrounded by the first groove 4 has a width of, for example, 20 mm square, and serves as an exciting unit 5 that comes into contact with the workpiece W during polishing and induces vibration. In addition, a second groove (cavity) 6 overlapping the excitation part 5 is formed in the lower layer portion of the polishing cloth 1, and the second groove 6 resonates with the vibration of the excitation part 5.

The region where the first groove 4 is formed is not particularly limited, but there are, for example, those shown in FIGS. 2 (a) and 2 (b). The first groove 4 shown in FIG. 2A has a rectangular plane, and a plurality of first grooves 4 are formed in the cross direction. Also, FIG.
A plurality of first grooves 4 shown in (b) are linearly formed in the vertical and horizontal directions. As shown in FIG. 3, the upper surface plate 3 is supported by a housing 8 having an internal cavity via an elastic portion 7 such as rubber or a spring, and moves differently from the housing 8. . The upper part of the housing 8 is fixed to the lower end of the shaft 9 which is rotated and moved up and down by the shaft drive unit 21. The housing 8, the upper surface plate 3, and the elastic portion 7 are also collectively called a head, and the space inside the head has an internal pressure capable of pressing the upper surface plate 3 against the polishing cloth 1.

A vibration detection element (hereinafter also referred to as an acceleration element) 10 is attached to the upper or side portion of the upper surface plate 3.
The output end of the vibration detecting element 10 is connected to the transmitter 13 attached to the housing 8. As the vibration detection element 10, for example, a piezoelectric element acceleration sensor is used. A head having a structure in which the space surrounded by the housing 8, the upper surface plate 3, and the elastic portion 7 is maintained at a predetermined pressure is called an airbag head. In the air bag type head, when the upper surface plate 3 is displaced upward, downward pressure for returning the position is applied to the upper surface plate 3, while when the upper surface plate 3 is displaced downward, the upper surface plate 3 is moved downward.
Is or is held at such a pressure that upward pressure is applied to restore the position. The pressure is applied externally through a cavity in the shaft 9.

Further, the transmitter 13 wirelessly transmits a signal of information on the vibration frequency and the vibration intensity from the vibration detecting element 10 to the receiver 14, and the vibration information received by the receiver 14 is analyzed by the signal analysis unit 15. Then, a natural vibration component (for example, a vibration component peculiar to the polishing apparatus) due to a cause other than polishing is subtracted from the obtained power spectrum of the vibration frequency and the vibration intensity, and the result is displayed on the display unit 16 or the drive control unit The shaft 9 and the dresser 12 are moved, driven, and stopped via 17, or the amount of polishing liquid supplied from the nozzle 11 is controlled via the drive controller 17.

The surface of the polishing cloth 1 is sharpened by the dresser 12. Vertical movement and rotation of the dresser 12
It is controlled by the drive controller 17. The rotation number of the motor M that rotates the lower surface plate 2 is controlled by the drive control unit 17. The object W to be polished by the above-described polishing apparatus includes, for example, a wafer of silicon, germanium, a compound semiconductor, or the like, a conductive film, an insulating film, or a metal film formed on such a wafer.

A plurality of small holes may be formed in the polishing cloth 1 instead of the above-mentioned first and second grooves.
Therefore, next, the operation of the above-described polishing apparatus will be described taking the polishing of a semiconductor wafer as an example. First, after sticking the semiconductor wafer W as the object W to be polished on the lower surface of the upper surface plate 3, the lower surface plate 2 is rotated by a signal from the drive control unit 17. Further, the shaft 9 is rotated and lowered by a signal from the drive control unit 17 to press the semiconductor wafer W against the polishing cloth 1. During the polishing, the polishing liquid is supplied to the polishing cloth 1 through the nozzle 11.

When the polishing is started, the semiconductor wafer W vibrates due to the friction between the semiconductor wafer W and the polishing cloth 1. Therefore, the vibrating portion 5 formed on the polishing cloth 1 vibrates, and the vibration is generated in the second groove 6 and the lower part. Resonance parts 2a, 3a of the side surface plate 2 and the upper surface plate 3
Is amplified by the resonance of and is transmitted to the vibration detection element 10. As the vibration input to the vibration detection element 10, there is a vibration component from the shaft drive unit 21 that drives the shaft 9 in addition to the vibration component due to friction. Shaft drive unit 21
The natural vibration of becomes the noise of the vibration detecting element 10 that detects the frictional vibration. However, since the vibration detection element 10 is attached to the upper surface plate 3, the natural vibration of the shaft drive unit 21 transmitted to the shaft 9 and the housing 8 is attenuated by the vibration absorption of the elastic body 7. As a result, the natural vibration of the shaft drive unit 21 transmitted to the upper surface plate 3 becomes weaker,
Noise input to the vibration detection element 10 is reduced.

Vibration information such as the vibration frequency and the vibration intensity detected by the vibration detecting element 10 is displayed on the display unit 16 via the transmitter 13, the receiver 14 and the signal analysis unit 15. On the display unit 16, for example, a power spectrum of vibration as shown in FIG. 4 is displayed. This power spectrum is obtained by subtracting the natural vibration component due to causes other than polishing by the signal analysis unit 15.

In the initial stage of polishing, where there are irregularities on the entire polishing surface, it can be seen that the vibration intensity increases over a wide vibration frequency band from low frequency to high frequency as shown in FIG. . When the polishing progresses and a part of the polished surface becomes locally flat, not only the vibration intensity decreases over the entire vibration frequency, but also the vibration intensity at a low vibration frequency of about 500 Hz is significantly attenuated. The low frequency attenuation is a unique phenomenon that occurs when a part of the polishing surface is polished flatly, and is 10 when the entire surface is polished uniformly.
The vibration intensity of the high frequency around 00 Hz is attenuated. When a part of the polishing surface is flattened, the drive control unit 17 adjusts the number of revolutions of the upper surface plate 3 and the lower surface plate 2 and the pressure by the upper surface plate 3 to adjust the variation in polishing. Reduce.

Since vibration does not occur when the entire polished surface is uniformly flattened, the vibration intensity becomes almost zero in the entire vibration frequency band as seen in FIG. In this way, the polishing cloth 1
In addition to widening the vibration frequency band and increasing the vibration intensity to improve the sensitivity due to the vibration induction of the excitation unit 5 provided on the upper surface plate 3 and the lower surface plate 2 of the polishing cloth 1. The vibration is amplified by the resonance of the resonance parts 2a and 3a.

As a result, it becomes possible to amplify and detect the presence of fine irregularities on the polished surface. The change in the vibration can detect even minute unevenness of the polishing surface of 0.05 μm or less on the polishing surface, and it is possible to accurately grasp the status of the polishing variation on the polishing surface, and change the polishing pressure in the direction in which the variation decreases. The polishing variation can be corrected automatically by changing the number of rotations of the upper or lower platens 2 and 3. As a result, the polishing state can be grasped with high accuracy to facilitate the determination of the end of polishing, and no additional polishing is required, thus improving the throughput.

When the spectrum of the vibration intensity with respect to the vibration frequency is integrated by the signal analysis unit 15, the integrated value gradually decreases as the polishing progresses. Therefore, when there is no temporal change in the integrated value, it is judged that the polishing is completed. The signal analysis unit 15 to send a polishing end signal to the drive control unit 17,
The drive control unit 17 stops the rotation of the shaft 9 or raises the shaft 9 so that the semiconductor wafer W and the polishing cloth 1
The contact is cut off to finish the polishing.

When the integrated value does not become zero even after the polishing is completed, the integrated value becomes a preset reference value, or the temporal change of the integrated value is a preset reference value. It may be judged that the polishing has been completed when it becomes smaller than the above. By the way, when the polishing pad 1 is worn in a state where the polishing is not finished, the friction between the object to be polished W and the excitation part 5 is reduced and the vibration is not generated, and the vibration intensity is rapidly attenuated to be almost the same as the state where the polishing is finished. Change in characteristics. Such steep vibration intensity attenuation is detected by the signal analysis unit 15 via the vibration detection element 10, the transmitter 13, and the receiver 14, and the signal analysis unit 15 determines that the polishing pad 1 has deteriorated. In this case, the polishing is stopped via the drive control unit 17, and the dresser 12 is driven to make the polishing cloth 1 stand out. Then, after finishing the dressing, polishing is restarted.

When the surface of the polishing cloth 1 becomes smooth, the vibration intensity in the frequency band of 0 to several hundred Hz is several d.
Since it exists in the size of B, it may be detected that the polishing cloth is worn based on the information of the existence of the vibration intensity and the change of the vibration intensity in the vibration frequency band. The deterioration criterion of the polishing cloth may be the deterioration criterion when the time from the start to the end of polishing is shorter than a preset time, or when the temporal change of the integrated value decreases beyond a specified value.

Next, a semiconductor device is prepared by using the above polishing apparatus.
The process of polishing the insulating film covering the wiring of the storage device will be described.
It When forming the wiring of the semiconductor device, first, as shown in FIG.
As shown in (a), the semiconductor substrate W₁On top of the first insulating film W
₂After forming the first insulating film W₂Form a metal film on top
Then, as shown in FIG. 5 (b), the metal film is patterned.
Wiring pattern W₃To form. Then the figure
As shown in 6 (a), the wiring pattern W₃To protect
Second insulating film W_FourTo form. Wiring pattern W₃And the
One insulating film W ₂The step formed by the second insulation
Membrane W_FourAppears as irregularities on the surface of. Second insulating film W_Four
The end point of the surface of the
And the polished surface is flat as shown in Fig. 6 (b).
Became.

Since the polishing rate is high when the second insulating film W ₄ is a SiO ₂ film using TEOS, for example,
As shown in FIG. 7A, CVD is performed on the second insulating film W _4.
As a result, a silicon nitride film W ₅ may be formed. Unevenness appears on the surface of the silicon nitride film W ₅ . The surfaces of the second insulating film W ₄ and the silicon nitride film W ₅ are polished by the polishing apparatus of the present invention until the end point is detected, and the polished surfaces become flat as shown in FIG. 7 (b). Silicon nitride
Since harder than SiO _2, the polishing amount when there is a silicon nitride film W ₅ is less than the polishing amount in the absence of the silicon nitride film W _5.

When only the second insulating film W ₄ is polished, the polishing surface changes as shown in FIGS. 8 (a) to 8 (c), and in these cases, the vibration input to the vibration detecting element 10 is changed. The waveform becomes smaller as the polishing progresses as shown in FIG.
On the other hand, when the second insulating film W ₄ and the silicon nitride film W ₅ are polished, as shown in FIGS. 9A and 9B, the silicon nitride film W ₅ which covers the entire surface in the initial state. Part of the second insulating film W ₄ disappears as the polishing progresses.
Will be exposed. Further, when the silicon nitride film W ₅ and the first insulating film W ₄ are polished, the polishing end point is detected when the polished surface is flattened, and the polishing is stopped. As shown in FIG. 9C, only the first insulating film W ₄ may be exposed on the polished surface, or the silicon nitride film W ₅ may be partially left on the polished surface.

The waveform of the vibration input to the vibration detecting element 10 during the polishing is almost as shown in FIG. Therefore, the above-described polishing apparatus does not capture the situation where the amplitude becomes large due to the change of the film quality as described in JP-A-6-320416, and the vibration intensity increases as the flatness of the polishing surface improves. When the vibration reduction reaches a predetermined standard, the polishing end point is judged and the polishing is stopped.

A plurality of the vibration detecting elements 10 described above may be attached to the upper surface plate 3. For example, the polishing state may be detected in more detail by separately detecting the vertical vibration and the horizontal vibration. Further, the vibration of the vibration detecting element 10 may not be the vibration in the vertical direction but may be the vibration in the lateral direction or the circumferential direction. The vibration in the circumferential direction will be described in detail in the eighth and ninth embodiments. Further, the vibration detecting element 10 may be attached to the lower surface plate 3 instead of the upper surface plate 3. The mounting location is similarly applied to the following embodiments. (Second Embodiment) FIG. 11 is a side view showing a second embodiment of the present invention.

In the present embodiment, as shown in FIG. 11, a vibration detecting element (acceleration element) 18 made of a piezoelectric material such as ceramic or crystal is interposed in the intermediate layer of the upper surface plate 3. As a result, not only the vibration of the object W to be polished perpendicular to the polishing surface but also the friction in the twisting direction along the surface of the polishing surface,
That is, the "shear friction force" can be detected. The shear friction force sharply decreases when a part of the polished surface is locally flattened, so
When it is desired to polish the entire surface uniformly, the polishing conditions (for example, the polishing pressure and the polishing rate) are adjusted so as not to decrease sharply, and the variations in the polishing are eliminated.

The vibration detecting element 18 of this embodiment is the first
It is connected to the transmitter 13 as in the embodiment. Further, the vibration detecting element 18 may be applied to a polishing apparatus in which the polishing cloth 1 does not have the excitation unit 5. (Third Embodiment) FIG. 12 is a side view showing a third embodiment of the present invention.

In this embodiment, as shown in FIG. 12, a film-shaped pressure sensor 19 such as a strain gauge is interposed between the workpiece W and the upper surface plate 3. This allows
By detecting a change in pressure applied to the object W to be polished in a direction perpendicular to the polishing surface as a change in electrical resistance, it is possible to detect a vibration frequency or vibration intensity in the vertical direction. This pressure sensor 19
A type that can detect the pressure distribution may be used.

The vibration detecting element 18 of this embodiment is the first
Although it is connected to the transmitter 13 as in the embodiment, it can also be applied to a polishing apparatus in which the polishing cloth does not have the above-mentioned excitation unit. (Fourth Embodiment) In the above-described embodiment, the object to be polished is attached to the upper surface plate and the polishing cloth is attached to the lower surface plate. However, as shown in FIG. Surface plate 2
Alternatively, the polishing cloth 1 may be attached to the upper surface plate 3.

In this embodiment as well, the exciter 5 is attached to the polishing cloth 1.
And the vibration detecting element 10 and the transmitter 13 are attached to the upper surface plate 3. In this embodiment as well, the second groove 6 is formed in the polishing cloth 1 as in the first embodiment, and the upper surface plate 3 and the lower surface plate 2 are provided with the cavity portions 2a and 3a each having a cavity. May be. (Fifth Embodiment) In the above-described embodiments, the shaft rotates the upper surface plate, but as shown in FIG. 14, a so-called dead weight type using the upper surface plate 20 without a rotation mechanism is used. Even when the polishing apparatus is used, the vibration detecting element 10 and the transmitter 13 may be mounted on the upper surface plate 20. In this case, the exciter 5 may be provided on the polishing cloth 1 on the lower surface plate 2, or the cavity surface may be provided on the upper surface plate 20 or the lower surface plate 2.

In FIG. 14, the same symbols as those in FIG. 1 indicate the same elements. (Sixth Embodiment) FIG. 15 is a side view of a sixth embodiment of the present invention. The present embodiment shows a polishing apparatus having a structure for supplying power to a transmitter without using a battery and a structure for wirelessly connecting a transmitter and a receiver. In FIG. 15, FIG.
The same reference numerals denote the same elements.

In FIG. 15, a shaft drive section 21 having a motor is attached on the shaft 9, and the shaft drive section 21 is provided with an elastic body 22 to oscillate the device 2.
It is attached to 3. The rocking device 23 includes a belt 24.
And is arranged so as to be vertically and horizontally movable along the upper surface of the polishing pad 1a. A vibration detection element (for example, an acceleration sensor) 10 is attached to the upper surface plate 3 at a position separated from the center of the upper surface plate 3 by 1/4 to 3/4 of the radius of the surface plate. Further, at least one round of a transmitting antenna 25 connected to the transmitter 13 is formed on the outer peripheral surface of the housing 8 to which the transmitter 13 is attached. Further, at least one receiving antenna 26 is formed on the outer peripheral surface of the oscillating device, and the receiving antenna 26 receives the signal shown in FIG. 1 through the signal line 27 arranged along the elastic body 22 and the belt 24. Machine 14
Connected to. The receiving antenna 26 is surrounded by a shielded wire 27a that is grounded.

On the other hand, a ring-shaped conductor 28 insulated from the surface is formed around the shaft 9.
A conductive brush 29 is in contact with 8, and the conductive brush 29 is connected to a power supply wiring drawn to the outside. Further, an electric wire 30 is drawn from the annular conductor 28 along the inside or the outside of the shaft 9, and the electric wire 30 is connected to the power supply terminal of the transmitter 13. The electric wire 30 is covered with an insulating material.

When the elastic portion 7 for supporting the upper surface plate 3 on the housing 8 is an insulator, the upper surface plate 3 and the transmitter 13 are connected to each other so as to secure a ground potential. Plate 3
Must be formed of a conductor, or metal must be vapor-deposited on the surface of the upper surface plate 3 to connect them to the ground wire.
As a result, only one electric wire 30 is required to be pulled in the length direction of the shaft 9 which is at the ground potential.

According to such a polishing apparatus, even when the upper surface plate 3 is rotated by the shaft 9, the signal output from the transmitter 13 is wirelessly transmitted through the substantially annular transmitting antenna 25 around the upper surface plate 3. Sent by. Since the radio signal is input to the receiver 14 shown in FIG. 1 via the substantially annular receiving antenna 26 around the shaft driving unit 21, the radio signal is not disturbed by the shaft 9. In this case, even if the oscillating device 23 oscillates, the transmitting antenna 25 and the receiving antenna 26 simultaneously oscillate, and the transmitting antenna 25 among them rotates. In addition,
The receiving antenna 26 does not rotate.

Transmitting antenna 25 and receiving antenna 26
If one of them is arranged in a substantially annular shape around the shaft 9, transmission and reception becomes possible. However, in order to avoid the instability of the transmission / reception state due to the swing of the shaft 9, as described above, the transmitting antenna 25 and the receiving antenna 26 are provided.
It is preferable to make both of them annular and then arrange them coaxially.

On the other hand, since the electric power consumed by the transmitter 13 is supplied through the electric wire 30 arranged along the shaft 9, it is unnecessary to replace the battery for supplying the electric power to the transmitter 13, Moreover, it is possible to avoid interruption of polishing due to insufficient power and improve throughput. The polishing cloth 1a may have the excitation part formed as in the first embodiment. Further, the structure shown in the first embodiment may be adopted except for the power supply system and the signal transmission system. (Seventh Embodiment) Since it is necessary to construct a management system in the case of polishing a plurality of objects to be polished in parallel by using a plurality of polishing apparatuses shown in the first embodiment or the sixth embodiment, The embodiment will be described based on FIG.

In FIG. 16, a plurality of polishing devices m _{1 to} m _n having the above-mentioned structure are provided with signals f _{1 having} different frequencies.
The above-mentioned transmitters 13 for transmitting .about.fn are attached, and the above-mentioned vibration detecting elements 10 are connected to the transmitters 13, respectively. Further, those transmitters 13 are configured to transmit only a specific vibration frequency band by a filter.

The signal output from each transmitter 13 is wirelessly propagated via the transmitting antenna 25 and the receiving antenna 26. The signals f _{1 to} fn having different frequencies inputted to the receiving antenna 26 above the transmitting antenna 25 are inputted to the receiver 32 via the combiner 31.
The receiver 32 sequentially tunes the signals f _{1 to} fn of the plurality of transmitters 13 in a time division manner every time the signal analysis unit 33 requests a certain amount of received data, and transmits the tuned signals to the signal analysis unit 33. In addition, it has an automatic tuning (automatic frequency control) mechanism. Auto-tuning mechanism, since mechanisms that automatically hold the variation in the frequency of the to be tuned signal in the range of the reference frequency, the frequency of the signals f ₁ to fn are even slightly shifted by a temperature change, say the unreceivable Inconvenience is avoided. Therefore, even if the transmission frequency of the transmitter 13 fluctuates due to a temperature change or the like, it is always received in the best reception state.

Further, the receiver 32 uses the signal analysis unit 3 as the signals f _{1 to} fn having the same or closest frequency as the tuned signal.
3 is transmitted, the signal processing in the signal analysis unit 33 is normally performed. In the signal analysis unit 33, the time-divided signal f
Based on the information of _{1 to} fn, the drive control unit 17 of each polishing apparatus m _{1 to mn} is controlled to drive, stop or adjust the pressure of the platen, or adjust the number of rotations of the platen, or a dresser. Drive and stop.

The tuning is performed in the order of frequency, and this is repeated many times. As described above, the plurality of polishing devices can be efficiently and optimally managed. (Eighth Embodiment) In the present embodiment, a polishing apparatus that controls polishing by vibration in the circumferential direction (or rotation direction) of the polishing surface will be described. FIG. 17 is a side view of the polishing apparatus showing the eighth embodiment, and FIG. 18 is a bottom view of the head. In FIG. 17, the same reference numerals as those in FIGS. 1 and 15 indicate the same elements, and the parts not shown have the same mechanism as in either of FIGS.

In this embodiment, the elastic body 7 for connecting the air bag type housing 8 and the upper surface plate 3 is not particularly limited in material, but a rubber sheet having a multilayer structure in which cloth is sandwiched is used. By using a plurality of the rubber sheets stacked together, the one having high mechanical strength can be obtained. A vibration detecting element 10A is attached on the upper surface plate 3,
As shown in FIG. 18, the orientation is such that minute vibrations in the circumferential direction of the upper surface plate 3 are detected. The vibration detection element 10A
Has a structure in which the direction of vibration to be detected can be selected by changing its direction. The above-mentioned first to seventh
The vibration detection element 10 in the above embodiment is arranged so as to detect vertical vibrations.

The vibration detecting element 10 is connected to the transmitter 13A on the housing 8 via a signal line. The signal output end of the transmitter 13A is an annular transmitting antenna 25 on the outer peripheral surface of the housing 8.
Further, the power supply end of the transmitter 13A is connected to the annular conductor 28 shown in FIG. The mechanism on the side that receives the radio signal output from the transmitting antenna 25 is shown in FIG.
The configuration includes an annular receiving antenna 26 shown by 5.

Incidentally, reference numeral 34 in FIG.
Amplifier 34a, filter 34b, and second amplifier 34c
2 shows an integrated circuit. The circuits of the transmission system and the reception system are as shown in FIG. The vibration detection element 10A has a first
Amplifier 34a, filter 34b, and second amplifier 34c
Is connected to the transmitter 13A via a cable. When the vibration detecting element 10A has a sensitivity of 50 mV / G (about 50 μV / gal) or more and a noise level of 1 mG (about 1 gal) or less, an acceleration sensor is used as the vibration detecting element 10A. Has a resonance frequency of 20 kHz or higher, or has a resonance at a frequency at which the vibration intensity changes with the progress of polishing.

The first amplifier 34a has a gain of 500, the filter has a bandpass of 10 Hz to 30 KHz, and the second amplifier 34c has a characteristic of a gain of 1/50. For example, an FM transmitter is used as the transmitter 13A. Used. Commercially available operational amplifiers can be applied to the amplifiers 34a and 34c. Further, the filter 34b is formed by combining a plurality of bandpass filters having different center frequencies, such as a graphic equalizer, so as to be able to immediately respond to changes in polishing conditions, an object to be polished, and changes in a vibration mode due to modification of the polishing apparatus. Alternatively, a programmable bandpass filter may be used to change the transmittance of each vibration frequency band. FIG. 20 shows an example of the characteristics of the filter using the graphic equalizer. Each bandpass filter has an attenuation rate of 34 dB / o.
ct or more and bandwidth equal to or less than the center frequency or 1 kHz
It is preferable to use one having a z level.

On the other hand, in the receiving system, the receiver 14 connected to the receiving antenna 26 includes the signal analyzing unit 15 shown in FIG.
The processing unit 35 having the drive control unit 17 is provided.
Is composed of an FFT analyzer, a CPU board, or a so-called personal computer. The processing unit 35 obtains a spectrum of vibration frequencies of, for example, about 10 Hz to about 30 kHz.

Although the structure for measuring the vibration peculiar to the polishing has been described above, the vibration of the motor for rotating the lower surface plate 2 and the upper surface plate 3 is actually the vibration detecting element 10A. To enter. Therefore, the vibration of the upper surface plate 3 caused by the vibration of the polishing apparatus itself is 50 mG (about 50 gal).
The following structure is preferable. 50 mG
As a method of determining whether or not the following, the polishing vibration exerted on the upper surface plate 3 when a flat wafer is used as the workpiece W may be measured.

Next, detection of the polishing end point using the polishing apparatus having the above structure will be described. First, while rotating the lower surface plate 2 and the upper surface plate 3, the lower surface plate 2
To be polished W attached underneath the polishing cloth 1 on the lower surface plate 2
Then, the polishing of the object W to be polished is started. The polishing cloth 1 includes the grid-like grooves 4 and the vibrating portion 5 as described in the first embodiment.
have.

When the relationship between the frequency of vibration of 0 to 25 kHz in the circumferential direction of the upper surface plate 3 and the intensity of the vibration was examined, the results shown in FIG. 21 were obtained. It can be seen that the vibration strength decreases over the entire vibration frequency band as the polishing progresses. From this,
The vibration signal detected by the vibration detection element 10A is input to the processing unit 35 via the transmitter 13A, the receiver 14, and the like. The processing unit 35 compares the reference spectrum, which is the reference value, with the vibration signal being measured, and, for example, the ratio between the integrated value of the vibration intensity and the integrated value of the reference spectrum in a specific frequency range is equal to or less than a predetermined threshold value. When
Alternatively, when the amount of change over time of the integrated value of the vibration intensity in a specific frequency range becomes equal to or less than a predetermined threshold value, it is determined that the polishing has ended.

The detection accuracy of the vibration signal depends on the wireless transmitter 13A.
Greatly affects the performance of. First and second amplifier 34
The characteristics required for a and 34c and the filter 34b and the vibration signal to be transmitted are determined by the following procedure. First, the vibration strength of the upper surface plate 3 is measured by wire. Next, the first amplifier 34 is adjusted so that the voltage obtained by amplifying the vibration intensity signal does not exceed the allowable input voltage of the filter 34b.
Determine the amplification factor of a. Further, the voltage obtained by amplifying the vibration intensity signal that has passed through the filter 34b is the transmitter 13
The second value so that it does not exceed the allowable input voltage of A
The amplification factor of the amplifier 34c is determined.

When determining the transmission frequency band of the vibration intensity frequency of the filter 34b, first, the radio frequency is transmitted while the polishing is actually performed, and the vibration frequency at which the vibration intensity does not change even if the polishing progresses is investigated, and A transmission frequency band is determined so that the vibration frequency is not transmitted. A vibration component whose vibration intensity does not change even when polishing progresses is vibration noise caused by the polishing apparatus itself.

The deterioration of the polishing pad 1 and the change in the concentration of the polishing liquid can be known by comparing the shapes of the spectrum measured in advance and the measured spectrum. If this information is unnecessary and only the polishing end point is desired to be known, a vibration intensity signal in a specific frequency range is converted into a DC signal corresponding to its effective value before the transmitter 13A, and this is transmitted to the transmitter 13.
You may make it send from A to the receiver 14.

In order to expand the amplitude range when wirelessly transmitting the vibration signal, the vibration signal is amplified by the logarithmic amplifier 34c and then wirelessly transmitted by the transmitter 13A, and the wireless signal is received by the receiver 14. After that, the received signal is processed by the processing unit 35.
The original signal may be reproduced by the inverse logarithmic amplifier inside. Note that, in the present embodiment, as in the structure shown in FIG. 15, the annular conductor 28 is used to supply power to the oscillator 13A, but a battery may be used. Moreover, the transmitter 13A may transmit to the receiver 14 by wire using a signal circular conductor having the same structure as the circular conductor 28 used for power supply, instead of wirelessly. Further, although the transmitter 13A is attached to the outside of the casing 8, it may be attached to the inside of the cavity inside the casing 8 like the vibration detecting element 10.

In FIG. 17, one upper surface plate 3 is arranged on one lower surface plate 2, but a plurality of upper surface plates are arranged on one lower surface plate 2. Or, when using a polishing apparatus having a plurality of sets of the lower surface plate 2 and the upper surface plate 3,
The above-described configuration is provided for each head for the progress or termination of polishing, and the polishing is controlled independently. The amplifier and the filter described in this embodiment may be applied to the polishing apparatus of the first to seventh embodiments. (Ninth Embodiment) In the above eighth embodiment, the case where one vibration detection element 10A is mounted has been described.
If a weight having the same weight as the vibration detecting element 10A or a second vibration detecting element is mounted on the upper surface plate 3 so as to be center-symmetrical to the vibration detecting element 10A, the rotating upper surface plate 3 will be well balanced. Vibration of time is stable.

An apparatus to which the second vibration detecting element is attached is shown in FIG. 22. In this configuration, the two vibration detecting elements 10 are provided by adopting the circuit configuration as shown below.
Vibration noise of A and 10B can be reduced. The vibration noise is due to the vibration component in the direction perpendicular to the measurement direction. The vibration detection elements 10A and 10B generally have a sensitivity of several% for a vibration component that is in a direction perpendicular to the measurement direction. In this embodiment, the vibration component in the perpendicular direction is vibration in the vertical direction.

In FIG. 22, two vibration detecting elements 10 are provided.
Two vertical vibration noises respectively input to A and 10B are in the opposite direction as shown in FIGS. 23 (a) and 23 (b) and in the same direction as shown in FIGS. 24 (a) and 24 (b). In some cases. FIG. 23
When vertical vibration noise occurs in the opposite direction as shown in Fig. 25, as shown in Fig. 25 (a), the vibration detecting elements 10A, 10B
The adder 36 is connected to the output ends of the first amplifiers 34d and 34e connected to the output end of the adder 36, and the output end of the adder 36 is connected to the filter 34b. In this case,
As indicated by the solid arrow 2 (a), the two vibration detecting elements 10A and 10B are arranged so as to detect the rotational vibration of the upper surface plate 3 in the same circumferential direction.

By arranging the vibration detecting elements 10A and 10B as described above and inserting the adding circuit 36 on the output side of the first amplifiers 34d and 34e, it is possible to cancel and reduce the vibration noise in the vertical direction. Moreover, filter 3
Since the vibration intensity in the circumferential direction input to 4b is doubled, S
The / N ratio is improved. On the other hand, when vertical vibration noises in the same direction as shown in FIGS. 24 (a) and 24 (b) occur, as shown in FIG. 25 (b), the output terminals of the vibration detection elements 10A and 10B are connected. The subtractor 38 is connected to the output terminals of the connected first amplifiers 34d and 34e, and the output terminal of the subtractor 38 is connected to the filter 34b. In this case, the two vibration detection elements 10A and 10A,
B is arranged so as to detect the rotational vibration of the upper surface plate 3 in the opposite direction.

By arranging the vibration detecting elements 10A and 10B as described above and inserting the subtractor 38 on the output side of the first amplifiers 24d and 34e, vibration noise in the opposite direction can be added to reduce the vibration noise. Moreover, since the absolute value of the vibration intensity in the circumferential direction detected in the reverse direction is doubled by the subtractor 38, the vibration intensity in the circumferential direction input to the filter 34b is doubled, and the S / N ratio is increased. Is improved.

Whether the upper surface plate 3 has a longitudinal vibration as shown in FIGS. 23 (a), (b) or a longitudinal vibration as shown in FIGS. 24 (a), 24 (b) depends on the polishing apparatus or because it depends on polishing conditions, it is necessary to investigate whether to take either of the longitudinal vibration in advance. Such vertical vibration is caused by the two vibration detecting elements 10
The configuration with the least noise may be selected by changing the mounting direction of A and 10B or by exchanging the adder and the subtractor of the signal.

In this embodiment, the vibration component in the circumferential direction is detected and the vibration component in the vertical direction is excluded. However, when the vibration component in the longitudinal direction is detected, the vibration component in the circumferential direction is detected. However, in this case, it is necessary to adjust the directions of the two vibration detecting elements. (10th Embodiment) FIG. 26 is a side view showing a 10th embodiment of the present invention.

The present embodiment is intended to prevent the polishing surface from being damaged by dust during polishing and facilitate removal of dust. The dust that damages the polishing surface includes, for example, silicon oxide contained in the polishing liquid that is dried and solidified, and pieces of an object to be polished. In FIG. 26, a dead weight type upper surface plate 41 is used, and an acceleration detecting element (vibration detecting element) 42 is attached to the surface thereof. Also, for example, a semiconductor wafer is attached as an object to be polished W under the upper surface plate 41, and this is attached to the lower surface plate 4
3 is placed on the polishing cloth 44 attached to No. 3.

Further, a marker 45 having a high light reflectance is attached to a side portion of the lower surface plate 43, and whether or not the marker is at a predetermined position is determined by a marker position detector 46 on the side of the lower surface plate 43. Detected by. The marker detector 46 has a light emitting element and a light receiving element, and the amount of light received increases due to the reflected light from the marker 45, so that the presence or absence of the marker 45 is detected.

The signal of the acceleration sensor 42 of the upper surface plate 41 is input to the signal analysis unit 15 via the transmitter 13 and the receiver 14 shown in the first embodiment. In the polishing apparatus described above, the lower surface plate 43 is rotated to polish the workpiece W with the polishing cloth 44. In this case, the workpiece W is moved in a certain direction by an arm (not shown). Then, the vibration information of the upper surface plate 41 detected by the acceleration sensor 42 during one rotation of the marker 45 is sent to the signal processing analysis unit 15 at least once via the transmitter 13 and the receiver 14 shown in FIG. Enter continuously.

FIG. 27 (a) shows the case where polishing is normally performed.
Although the spectrum of the vibration frequency and the vibration intensity as shown in Fig. 27 is obtained, if the polishing surface of the workpiece W is damaged by the dust on the polishing cloth 44, the vibration intensity increases at some frequencies as shown in Fig. 27 (b). To do. The spectrum that serves as a criterion for the increase may be checked in advance, or the spectrum before being damaged may be used.

When the presence of dust becomes apparent due to such abnormal vibration intensity, the drive controller 17 drives the dresser 12 while supplying water to the polishing cloth 44 through the nozzle 11, and drives the dressing cloth 44. After the dust is discharged from the surface of the lower surface plate 43 to the outside, the polishing is restarted again. By the way, when it is desired to specify the position of dust, the following processing is performed.

During the polishing, if the vibration information of the upper surface plate 41 is continuously input to the signal analysis unit 15, the marker detector 46 can know when the marker 43 is detected. By recording and recording the abnormal signal together, for example, the characteristic as shown in FIG. 28 is obtained. Since the marker position appears at regular intervals, when scratches due to dust occur on the polished surface, the time of occurrence of the abnormal signal is recorded on the time axis. Thus, from the ratio of the time interval of passing the marker and the time from when the marker passes to when the abnormal signal occurs, the angle θ from which dust is generated is easy with respect to the line connecting the center of the polishing cloth 44 to the marker 45. Sought.

Therefore, the signal analysis unit 15 has the drive control unit 17
To drive the dresser 122 to drive the dresser 12 on the surface of the polishing cloth 44 at least along the normal line of the angle θ, dust is removed in a short time. Further, if an abnormal signal is generated at the same position even after the dresser, or if the abnormal signal is generated at the same position even if the workpiece W is replaced, the polishing is immediately stopped and the abnormal signal is generated. Notify the worker, and the worker will eliminate the cause of the abnormal signal. As a result, the next polishing of the object W to be polished can be started in a normal state, so that the number of wasteful objects W to be polished, for example, semiconductor wafers is reduced, and the polishing efficiency is improved.

By the way, as shown in FIG. 28, if the abnormal signal stops within one cycle of the marker, it is understood that the abnormal signal is due to dust. However, if one cycle or more continues, there is a high possibility that an abnormal signal will be generated due to a cause other than dust. In this case, therefore, the signal analysis unit is configured to completely stop polishing, and an abnormal signal sound is generated at the same time as the stop command. It is necessary to notify the worker by calling. (Eleventh Embodiment) In this embodiment, an apparatus for improving the S / N ratio of the output of the vibration detection element and the S / N ratio of the vibration input to the vibration detection element will be described with reference to FIGS. 29 to 35. To do. The vibration noise input to the vibration detection element is vibration other than the vibration generated by the friction between the object W to be polished and the polishing cloth 1, and is mainly generated from the motor. Such noise is hereinafter referred to as background noise.

29 to 35, the vibration detecting element 10 is placed at the center of the upper surface of the upper surface plate (bottom plate of the head) 3 so that the relative speed between the object to be detected W and the polishing cloth 1 is stable. This reduces the detection error. The basic structure of this embodiment is the same as that of the first or seventh embodiment, and the same reference numerals as those of these embodiments indicate the same elements.

FIG. 29 shows a structure in which the vibration detecting element 10 is surrounded by a soundproof / sound absorbing material 50 with a gap in the cavity in the housing 8 of the head. Soundproofing / absorbing material 5
Reference numeral 0 is composed of a bellows-type spring that allows the upper surface plate 3 to freely vibrate, an elastic material such as rubber, or a porous resin. By adopting such a configuration, it is possible to prevent background noise transmitted in the space inside the housing 8,
It is possible to absorb sound and improve the S / N ratio input to the vibration detection element 10. Moreover, since a gap is formed between the soundproof / sound absorbing material 50 and the vibration detecting element 10, new noise due to friction between the soundproof / sound absorbing material 50 and the vibration detecting element 10 does not occur.

When the natural vibration frequency of the upper surface plate 3 and the vibration frequency of the background noise are not matched, the S / N ratio is further improved. In addition, reference numeral 51 in FIG. 29 indicates an inner sheet interposed between the upper surface plate 3 and the object to be polished W in order to absorb the variation in the thickness of the object to be polished W. FIG. 30 shows an apparatus in which a resonance plate 52 is interposed between the vibration detecting element 10 and the upper surface plate 3 shown in FIG. The resonance plate 52 resonates at a specific vibration frequency to be measured, and is formed of, for example, a spring coil.

According to this, the background noise having a frequency different from the resonance frequency of the resonance plate 52 is generated by the resonance plate 5.
Since it is blocked by 2 and the input to the vibration detection element 10 is blocked, the S / N ratio of the input to the vibration detection element 10 is improved. 31 shows a device in which an amplifier 53 is attached to the side of the resonator 10 shown in FIG.

When the impedance of the vibration detecting element 10 itself is high, if the connection wiring with the amplifier 53 is long, noise easily enters the output signal of the vibration detecting element 10, but the resonator 10 and the amplifier 53 are connected to the upper platen 3. By mounting it on the top, the connection wiring can be shortened and the noise added to the vibration signal can be greatly reduced, thereby improving the S / N ratio. In the head of the polishing apparatus shown in FIG. 32, holes 54 are formed through both the upper surface plate 3 and the inner sheet 51, and the vibration detecting element 10 is placed in the holes 54.
And a vibration transmitting needle 55 that comes into contact with the detected object W is inserted. The vibration generated in the object to be detected W by the friction with the polishing cloth 1 is transmitted to the vibration detecting element 10 via the vibration transmitting needle 55 without being absorbed by the inner sheet 51, and therefore is input to the vibration detecting element 10. The vibration strength increases and the S / N ratio improves.

FIG. 33 shows the vibration detecting element 1 shown in FIG.
0 is a device in which a diaphragm 56 is interposed between the upper surface plate 3 and the upper surface plate 3, and a second vibration detecting element 57 for background measurement is mounted on the housing 8. The background noise signal output from the second vibration detection element 57 is converted into an antiphase by the vibration control unit 58, and then the vibration control unit 58 causes the vibration plate 56 to have the same waveform as the antiphase signal. It is a device that is made to vibrate. Diaphragm 56
Are those formed of a piezoelectric material such as a piezo element.

According to this apparatus, the vibration generated by the vibrating plate 56 cancels the background noise input to the vibration detecting element 10. Therefore, the vibration generated by the polishing cloth 1 and the workpiece W is selectively detected. It becomes possible to input to the element 10, and the S / N ratio is significantly improved. By the way, the resonance frequency f ₀ of the vibration detecting element 10 is 5 to 10 times more sensitive than the other frequencies. However, the frequency f _{1 of} the vibration to be detected may not match the resonance frequency f ₀ . In this case, as shown in FIG. 34, the vibration of the detected frequency f ₁ is input to the frequency conversion circuit 59 and vibrated with the same or proportional strength as the vibration frequency f ₁ detected by the frequency conversion circuit 59. By vibrating the plate 56 at the frequency f ₀ and feeding back the vibration at the frequency f ₀ to the vibration detection element 10, it is possible to detect vibration with high sensitivity. In this case, the processing as described in the first or sixth embodiment is performed on the vibration having the frequency f ₀ .

FIG. 35 shows a vibration detecting element 1 shown in FIG.
A plurality of 0s are arranged on the upper surface plate 3, and the vibration plates 5 are individually provided between the vibration detecting elements 10 and the upper surface plate 3.
It is a device with 2 interposed. By applying a constant signal to each diaphragm 52, the sensitivity of the vibration detecting element 10 is inspected and the vibration detecting element 10 having the highest sensitivity to the frequency of the vibration to be detected is selected by a selection circuit (not shown). I am trying to do it.

As a result, variations in the characteristics of the vibration detecting element 10 can be avoided, and another one can be selected by an electric circuit instead of the deteriorated vibration detecting element 10, and the labor of replacing the vibration detecting element 10 can be reduced. Can be reduced. As a method other than the above for improving the S / N ratio,
The power supply to some or all of the motors of the polishing apparatus may be stopped when the vibration is detected, which significantly reduces the background noise. The stop time is set to several seconds or less, and if the time is about this time, the head and the lower surface plate 2 rotate due to inertia, and the polishing process is continued. Also,
It takes only a few seconds or less for vibration detection, and there is no problem in vibration detection. Stopping the power supply to the motor is shown in FIG.
The control signal from the drive control unit 17 as shown in FIG.

The output of the vibration detecting element 10 is generated in the signal transmission system by taking it out through the amplifier and the filter as shown in the eighth embodiment, or by taking it out after A / D conversion. Noise can be reduced. When wirelessly transmitting the A / D converted signal, an A / D converter (not shown) is interposed between the oscillator 13A and the vibration detection element 10A shown in FIG.

Further, when the head is oscillating, the background noise due to the oscillating becomes large in a place where the direction of the head changes, so that the vibration detection is avoided. As an example of each vibration detection element, the model name CE507M101 of the piezoelectric element acceleration sensor manufactured by US Vibrometer
, CE507M301, and when these sensors are used, it is preferable to detect the vibration intensity at the resonance frequency f ₀ at which high sensitivity is obtained as shown in FIG. This can be applied to each of the above-described embodiments.

Next, the measurement results are shown in FIGS. 37 and 38. FIG. 37 is an example showing how the frequency spectrum of vibration changes with the passage of polishing time. According to this, it is found that the vibration strength decreases with the passage of polishing time. FIG. 38 shows the spectrum as shown in FIG. 37 by integrating the spectrum in a specific frequency range and calculating the difference between the integrated values at every elapse of a certain time. According to this, it can be seen that as the polishing time elapses, the amount of change in the integrated value decreases and the planarization by polishing progresses. The end point of polishing is when the change in the integrated value disappears. This determination of the end point can be applied to each of the above-described embodiments. (Twelfth Embodiment) FIG. 39 (a) is a sectional view showing a mechanical portion of a polishing apparatus according to a twelfth embodiment of the present invention.
(b) is a plan view showing a lower surface plate. FIG. 40 is a circuit diagram showing a signal processing portion of the polishing apparatus according to the twelfth embodiment of the present invention. In these figures, the same reference numerals as those in FIGS. 1 and 15 indicate the same elements.

In FIG. 39 (a), the shaft drive unit 21
A position detector 61 for detecting the position of the upper surface plate 3 is provided on the side of the
Are arranged. The position detector 61 has a light emitting element 61a that irradiates a detection plate 62 attached to the shaft drive unit 21 with light, and a light receiving element 61b that receives reflected light from the detection plate 62. The position detector 61 includes the light receiving element 6
The distance L from the shaft drive unit 21 is measured according to the amount of incident light of 1b, and the measured data is stored in a computer 7 described later.
7 is input. For example, a semiconductor laser is used as the light emitting element 61a, and a photodiode is used as the light receiving element 61b.

A polishing cloth 1d having a plurality of grooves 4a cut vertically and horizontally is attached to the lower surface plate 2, and the polishing cloth 1d is rotated by the motor M together with the lower surface plate 2 during polishing. It On the polishing cloth 1d, the upper surface plate 3 reciprocates between points a and b during polishing, and the upper surface plate 3 is further moved.
Is designed to rotate at a constant speed. The reciprocating motion and rotation of the upper surface plate 3 are transmitted from the shaft drive unit 21 via the elastic body 7, the housing 8 and the shaft 9. The operation of the shaft drive unit 21 is similar to that of the first embodiment, and the drive control unit 1
Controlled by 7.

As shown in FIG. 40, a voltage is applied to the output end of the vibration detecting element 10 attached to the upper surface plate 3 through the rectifier 63, and further the capacitor 64 and the amplifier 6 are connected.
5, low-pass filter 66 and high-pass filter 67
Is connected to the FM transmitter 34B via. The vibration signal output from the vibration detection element 10 is mechanically and electrically noise-removed by the capacitor 64, amplified by the amplifier 65, and then narrowed down to a specific frequency band by the low-pass filter 66 and the high-pass filter 67. Input to the transmitter 34B. The specific frequency band is, for example, 8 kHz to 18 kHz when the low-pass filter 66 removes a vibration signal of 18 kHz or more and the high-pass filter 67 removes a vibration signal of 8 kHz or less.
Becomes

The FM transmitter 34B wirelessly transmits the vibration signal from the transmitting antenna 25 around the housing 8 to the FM receiver 69. The vibration signal input to the receiving antenna 26 attached around the shaft driving unit 21 is received by the FM receiver 69 as shown in FIG. A recording device 70 is connected to the output terminal of the FM receiver 69, and the recording device 7
The vibration signal data stored in 0 is used for creating a data library, frequency analysis, adjustment of processing circuits, and the like.
The output terminal of the FM receiver 69 has a 1 kHz high-pass filter 71, a first amplifier 72, a rectifying circuit 73, 0.
5Hz low pass filter 74, second amplifier 75, A
It is connected to the computer 77 via the / D converter 76. The high pass filter 71 cuts off the DC component of the vibration signal, and the rectifier circuit 73 and the low pass filter 74 integrate the specific frequency band of the vibration signal to obtain the effective value of the frequency.

In the computer 77 described above, the vibration signal is calculated and displayed in accordance with the flowchart of FIG. First, a case where the polishing target W is polished only by the rotation of the upper surface plate 3 without the center of rotation of the upper surface plate 3 moving on the polishing cloth surface will be described. On computer 77,
The effective value of the vibration signal continuously input is sequentially sampled at a rate of 10 (10 Hz) per second, then the average value of the 10 sampled data D ₁ is calculated, and the average value is defined as one point. Let it be data D ₂ .

Next, when the point data D ₂ is displayed as an image with time as it is, a line with many irregularities is obtained. Therefore, in order to display the line smoothly, the average value of the five point data D ₂ is obtained and displayed as a point. The data D ₃ is obtained. In this case, the point data D ₂ is incremented one by one in the order of calculation, and the five point data D
_When the average of ₂ is calculated, the point display data D ₃ is 1
You will get one per second. Such an average is called a moving average.

The point display data obtained by this moving average are sequentially drawn on the image display section 77D of the computer,
A vibration intensity curve is obtained by drawing a plurality of dot display data. By the way, the sampled data D
_As is presumed from the above-described embodiment, the value ₁ gradually attenuates as the polishing progresses when the upper surface plate 3 simply rotates.

However, when the upper surface plate 3 is accompanied by an operation other than rotation, for example, a reciprocating operation on the polishing cloth 1d, the dot display data D ₃ shows an AC component as shown by the one-dot chain line in FIG. 42 (a). Since it is included, it becomes difficult to detect the end point of polishing. For example, differentiating the alternate long and short dash line in FIG. 42 (a) results in a curved line like the alternate long and short dash line in FIG. 42 (b), so it is not possible to determine the time when the differential value becomes zero as the polishing end point. .

Therefore, the upper surface plate 3 is located on the polishing cloth 1d at a point a.
When reciprocating between points b, correction is performed by dividing the effective value data D ₁ sampled at 10 Hz by the correction coefficient η, and then the point data D ₂ and point display data D ₃ are obtained. Next, the dot display data D ₃ is displayed on the image display unit 7
When displayed in 7D, the curve shown by the solid line in FIG. 42 (a) is obtained. As the curve showing the differentiation of the curve, the curve shown by the solid line in FIG. 42 (b) is obtained. Normally, the cycle of the reciprocating operation is about several tens of seconds or more, so the point data D ₂ may be divided by the correction function.

As shown in FIG. 39 (b), the rotating upper surface plate 3 reciprocates between two points a and b in the diameter direction from the rotation center O ₀ of the lower surface plate 2. 43 (a), the correction coefficient η
Becomes r ² / r ₁ ² as shown in FIG. 43 (b). For example, point a
The distance between the point b and the point b is 32 mm, and the moving speed v of the upper surface plate 3 is 2
In the case of mm / sec, the period T of the waveform in FIG. 43 (b) is 3
2 seconds. In this case, r ₁ is 134 mm.

Such a correction coefficient η is determined as follows. Considering that a minute portion P of the polishing surface of the polishing object W at a distance r from the rotation center of the polishing cloth 1d is rubbed by the polishing cloth 1d rotating at an angular velocity ω, the minute portion P
And the relative speed of the polishing cloth 1d is a function of rω. This distance r is obtained based on the position data from the position detector 61. The minute portion P was the center of rotation of the upper surface plate 3.

Also, on the surface of the polishing cloth 1d, as shown in FIG.
As shown in (b), there are some in which the grooves 4e or the small holes 4f are dug at a constant density. In this case, the polishing cloth 1d is 1
The number of contacts p in which the minute portion P contacts the groove 4e or the small hole 4f during rotation is a function of rω. Also, FIG. 44 (c),
As shown in (d), the groove 4g or the small hole 4h has the polishing cloth 1d.
In the case where the polishing cloth 1d extends radially from the center of rotation, the minute portion P has the groove 4G or the small hole 4H while the polishing cloth 1d makes one rotation.
The number of contacts p that comes into contact with is a function of ω. When using a polishing cloth having no grooves or small holes, it is not necessary to consider the influence of the grooves and small holes of the minute portion P.

Therefore, the product of the relative velocity rω and the number of contacts p is set as the correction function η. Table 1 shows the basics of the correction function η.
become that way. It should be noted that factors such as the type of polishing liquid and the material of the polishing cloth are considered to hardly change during polishing, so
It was decided not to include it in the correction coefficient η. Also, the upper surface plate 3
When r is not accompanied by any operation other than rotation, r is constant and therefore r is set to 1. Also, the rotation number of the upper surface plate 3 is generally not changed during polishing, and ω is set to 1 to make a correction function. You may decide η. Further, the correction function η may include a coefficient. For example, FIG. 39 (b) and FIG.
As shown in (b), the distance r may be divided by the distance r ₁ (constant).

[0135]

[Table 1]

As described above, the corrected sampling data Ds is converted into point data D ₂ after being averaged at 10 Hz as shown in FIG. 41, and then converted into point display data D _3. . And the dot display data D ₃ is
In the image display unit 77d, the relationship between the polishing time and the vibration intensity is displayed as shown by the solid line in FIG. 42 (a). Further, in the computer 77, the differential value (dV / dt) of the drawn curve or the time change amount ΔV is calculated based on the point display data D ₃ . The calculation result is, for example, FIG. 42 (b).
Is displayed on the image display unit 77d as a curved line like the solid line.

The time change amount ΔV of the dot display data is calculated by
For example, as indicated by the value obtained by subtracting the display data D ₃ from the display the current point data D ₃ 10-th previous point. In this example,
The time variation ΔV is displayed as one data item per second. Derivative value (dV / dt) or time variation ΔV
When the value becomes zero or more, the polishing end point is set, and the end point detection result is displayed on the image display unit 77D.

The computer 77 performing the above calculation and display functions as the drive control unit 17 shown in the first embodiment, and therefore commands the shaft drive unit 21 to stop the polishing when the polishing end point is detected. By the way, the upper surface plate 3
The locus reciprocating between the two points a and b on the polishing cloth 1d is not always in the diametrical direction from the rotation center 0 ₀ of the polishing cloth 1d. For example, as shown in FIG. 45 (a), it exists as a linear trajectory orthogonal to the diametrical direction, or FIG. 46 (a)
As shown in, the upper surface plate 3 may be swung by the arm of the robot, and the locus of the upper surface plate 3 may have an arc shape.

In these cases, the distance r between the center of rotation of the upper surface plate 3 and the center of rotation O ₀ of the polishing cloth 1d is as shown in FIG. 45 (b) in the case of the locus shown in FIG. 45 (a). 46 (b) in the case of the locus shown in FIG. 46 (a).
It changes with time. In the computer 77, the distance r at the time of measuring the effective value is calculated based on the data detected by the position detector 61 and used as the correction function η.

By the way, when only the rotating operation is applied to the upper surface plate 3, it is not necessary to consider the correction function η, and the curve based on the point display data is as shown in FIG. 47 (a).
The curve showing the differential value is as shown in FIG. 47 (b). In addition, a curve A in FIGS. 47 (a) and (b) shows a state in which a SiO ₂ film formed by using TEOS is polished, and a curve B shows a silicon nitride film on the SiO ₂ film. The state where the films are polished after the films are formed is shown.

In the above description, the detection of the polishing end point based on the vibration intensity of the upper surface plate 3 has been described. However, the progress of polishing depends on the shaft drive unit 21.
It can also be captured as a change in the torque of the motor built into the. Therefore, the effective value of the torque is calculated as described above,
The polishing status can be grasped and the end point can be detected by means of sampling or correcting the effective value. (Thirteenth Embodiment) In this embodiment, instead of measuring the vibration (sound) due to the friction between the head and the polishing cloth, the polishing state and the polishing end point are measured based on the change in the frictional force between the head and the polishing cloth. An example of the device is shown.

FIG. 48 is a sectional view and a bottom view showing the main part of the twelfth embodiment. 48, FIG. 1 and FIG.
5 and the same code | symbol as FIG. 17 have shown the same element. FIG. 48
In (a) and (b), the lower surface plate 2 having the polishing cloth 1 attached to the upper surface is rotated by the shaft drive unit 21 at a predetermined rotation speed. The object W to be polished, which is pressed against the upper surface of the polishing cloth 1 and is polished, is attached to the lower surface of the upper metal platen 3 made of metal at the bottom of the airbag head via the inner pad 51. . A side wall 3b is fixed around the upper surface plate 3, and the side wall 3b and the housing (support) 8 of the head are connected via an elastic portion 7. A cylindrical shaft 9 for rotating the casing 8 is attached to the center of the casing 8. Also, the shaft 9 and the housing 8
A cylindrical head cover 80 is non-rotatably attached to the periphery of the head to prevent the head from being contaminated by the polishing liquid.

An inclined surface (not shown) is formed on the upper surface of the upper surface plate 3 for converting the amount of lateral displacement (deviation) of the upper surface plate into the amount of vertical displacement. On the bottom of the case 8,
A first displacement detector 81 for detecting the displacement of the side wall 3b of the upper surface plate 3 is attached, and the head cover 80 is also attached.
A second displacement detector 82 for detecting the displacement of the side wall 3b of the upper surface plate 3 is attached to the bottom surface of the upper surface plate 3, and a ceiling surface inside the housing 8 above the inclined surface of the upper surface plate 3 is attached to the second displacement detector 82. Is equipped with a third displacement detector 83 for detecting the displacement of the distance from the inclined surface.

First, second and third displacement detectors 81-8
Reference numeral 3 is a stylus type displacement meter that detects a displacement amount by expanding and contracting a needle, a capacitance type displacement meter that detects a displacement amount based on a change amount of a capacitor due to a change in a distance from the upper surface plate side wall 3b, and an upper surface plate side wall 3b. There are eddy current displacement gauges that detect the amount of displacement based on the amount of change in the magnetic flux density due to changes in the distance between them, and optical displacement meters that detect the distance based on light reflection.

Such first to third displacement detectors 81 to
A plurality of 83 may be arranged as shown in the bottom view of the head of FIG. 48 (b), or one by one may be arranged. Also,
The first to third displacement detectors 81 to 83 are shown in FIGS. 48 (a) and 48 (b).
It is not necessary to provide all of them as described above, and at least one may be attached. The outputs of the first to third displacement detectors 81 to 83 are connected to the transmitter 13b via the amplifiers 34a and 34c and the filter 34b as shown in FIG.
The detection signal oscillated from b is input to the processing unit 35 via the receiver 14, and the processing unit 35 determines the polishing end point or changes the polishing conditions based on the change in the displacement signal.

Although not particularly shown, a polishing liquid supply nozzle and a dresser are arranged above the polishing cloth 1 as in the above embodiment. Further, the first and second displacement detectors 81 and 82 may be protected by a transparent cover so that the polishing liquid or water is not splashed. Since the third displacement detector 83 is arranged inside the housing 8, a cover is unnecessary.

Next, the polishing end point detection using such a polishing apparatus will be described. First, when a flat standard wafer is attached to the lower surface of the inner pad 51 and a polishing operation is performed, the position of the upper surface plate 3 is changed from FIG. 49 (a) to FIG. 49 (c).
It changes like. First to third displacement detectors 8 at this time
The displacement signals from 1 to 83 are recorded as the reference signal. The standard wafer is removed after the reference signal measurement.

Next, when a wafer on which an interlayer film is formed as the object to be polished W is attached to the lower surface of the inner pad 51 and polishing work is performed, the upper surface plate 3 existing at the position shown in FIG. As the body 8 moves, it is displaced as shown in FIG. 49 (b). Such displacement of the upper surface plate 3 occurs because the friction between the object W to be polished and the polishing cloth 1 is large, and thus the stress applied to the elastic body 7 around the upper surface plate 3 is largely broken. Therefore, the upper surface plate 3 is biased so as to be pulled in the moving direction of the housing 8. This is an initial state, and the displacement amount detected by the first to third displacement detectors 81 to 83 at this time is set to the maximum value.

When the polishing is continued, the friction between the object to be polished W and the polishing cloth 1 gradually decreases with the lapse of time, and the upper surface plate 3 is positioned near the center of the housing 8 as shown in FIG. 49 (c). Come to do. Further, the change of the upper surface plate 3 becomes small, and as shown in FIG. 50, the first to third displacement detectors 8
The amount of change in displacement detected by 1 to 83 also gradually decreases, and finally the amount of change becomes zero or close to zero, and polishing is stopped in this state. The polishing is stopped by lifting the casing 3 to reduce the polishing pressure or separating the workpiece W from the polishing cloth 1.

When it is difficult to detect the end point due to the amount of change in the displacement of the upper surface plate 3, as shown in FIG. 51, the time when the amount of displacement and the reference signal are compared or when there is almost no difference is detected. It may be the end point of polishing. As an example in which it is difficult to detect the end point, for example, when a foreign substance for detecting the end point is formed in the object W to be polished, the displacement may be further increased when the foreign substance is flattened and exposed. .

When investigating the displacement of such a surface plate,
The changes in the output signals of the displacement detectors 81 to 83 are gradual and may be measured as a DC component. Further, the displacement detectors 81 to 8 are accompanied by the rotation of the casing 8, the upper surface plate 3, and the polishing cloth 1.
When the detection signal of 3 has a low frequency of several tens Hz, only the low frequency component may be extracted as the detection signal. Since high-frequency signals such as background noise are removed by the filter, the sensitivity of the displacement detectors 81 to 83 is higher than that of the vibration detecting element 10. When the detection signal is direct current, or when the frequency band is narrow, such as around 0 to 100 Hz, the transmission accuracy to the detector is better than in the case of high frequency, so the sensitivity is higher than in the vibration measurement described above. Measurement becomes possible.

By the way, since the first displacement detector 81 rotates in synchronization with the head, the range measured by the upper surface plate 3 does not change, so that it is not affected by variations in the shape of the upper surface plate 3. . However, since the distance between the first displacement detector 81 and the upper surface plate 3 changes while the upper surface plate 3 makes one rotation, the intensity of the displacement signal and the displacement direction periodically change corresponding to the rotation frequency. Change. The rotation frequency is 10 at maximum.
Since it is around 0 Hz and is synchronized with the rotation of the head, the S / N ratio is not deteriorated.

The second displacement detector 82 can linearly detect the amount of change of the upper surface plate 3 without the displacement signal changing cyclically, but the influence of variations in the shapes of the housing 8 and the upper surface plate 3 is affected. It is easy to receive. The third displacement detector 83 targets the vertical movement of the slope formed on the upper surface plate 3 as the detection target, but eliminates such a slope and detects the vertical movement of the upper surface of the upper surface plate 3 as the detection target. May be

By attaching a plurality of such displacement detectors 81 to 82 to measure the front-rear, left-right and up-down displacements of the casing 8 and the upper surface plate 3, the total amount of information becomes rich. It is possible to obtain more information about wafer dropout, wafer damage, and polishing conditions (supply of polishing liquid, abnormal polishing cloth, pressure change, rotation speed change, etc.) it can.

Further, if hemispherical projections 91, 92 or recesses (not shown) as shown in FIGS. 52 (a) and (b) are formed at the detection location on the side wall 3b of the upper surface plate 3, the same location can be obtained. It is possible to detect displacements in multiple directions. When a plurality of polishing objects W are polished simultaneously, a plurality of heads shown in FIG. 39 are activated at the same time. When the variation in polishing under each head is 10% or less, it is not necessary to detect the polishing end point in all the heads, and it is not necessary to detect the polishing end points in some of the heads (there may be one). All that is required is to attach the vibration detecting element 10 in the form. In this case, the displacement detectors 81 to 83 or the vibration detecting element 10
Good results can also be obtained by stopping the polishing of all the heads when the heads attached with reach the end point. Note that polishing may be excessively performed for a predetermined time after reaching the end point.

Further, in order to attach the vibration detecting elements and the displacement detectors to all the heads, the heads (upper surface plate 3) are lifted in the order in which the end point detection of the polishing is finished to stop the polishing and all the polishing is finished. You may wait until. The command to stop polishing a plurality of heads is issued by the control unit 1 shown in FIG. 1 and FIG.
7,35.

[0157]

As described above, according to the present invention, since the mechanism for inducing vibration during polishing is formed on the polishing cloth, the vibration intensity of the vibration generated during polishing is increased and the vibration detection is performed. The vibration frequency band that can be detected by the element is widened, the polishing conditions can be precisely controlled, and the end point of polishing can be easily detected. As such a mechanism,
There is a polishing cloth in which a plurality of grooves are formed and vibration is induced in a region surrounded by the grooves.

In this case, when a cavity is formed inside the polishing cloth or the surface plate, the induced vibration at the time of polishing is amplified, and the change in the vibration intensity for vibration detection can be easily grasped. Further, the vibration information obtained from the vibration detection element is subjected to frequency analysis, and the vibration intensity obtained by subtracting the natural vibration component due to causes other than polishing is integrated every time, and when the integrated value falls below the reference value, or the integrated value Since the polishing is stopped by the signal analysis means that sends a polishing stop signal at any time when the temporal change is below the reference value, the polishing end point can be easily detected.

In the signal analysis means, the polishing cloth is either used when the time from the start of polishing to the stop of polishing is shorter than the set time or when the temporal change of the integrated value is decreased beyond the specified value. Since the signal indicating the deterioration signal is output, it becomes easy to judge whether the polishing is finished or the polishing cloth is deteriorated, and the polishing operation can be optimized. During polishing, if the reduction rate of vibration intensity at a specific vibration frequency is larger than that at other vibration frequencies, it is experimentally confirmed that polishing is not performed uniformly. It is possible to optimize the polishing by detecting such vibration intensity attenuation and changing the polishing conditions so that the polishing is uniform.

Furthermore, the amount of vibration attenuation by the vibration detector during polishing is grasped as an effective value, and the change of this effective value is measured every time, and the integrated value of the change or the amount of change for a certain time is zero or When the end point of polishing is detected when the above time is reached, and when the operation of moving the first polishing plate on the polishing cloth is performed in addition to rotation, a function including the position of the first polishing plate is used. When the detection signal is corrected by dividing the effective value by
The end point of polishing can be detected quickly and accurately.

Further, according to the present invention, when the output of the vibration detecting element for detecting the vibration during polishing is wirelessly transmitted to the outside, the transmitting antenna and the receiving antenna are arranged coaxially. It is possible to stabilize the transmission and reception even when is rotating or swinging. Further, when power is supplied to the vibration detecting element and the transmitting unit attached to the surface plate, an annular conductor is attached around the shaft that rotates the surface plate, and power is supplied through the brush that contacts the annular conductor. As a result, it is possible to avoid the trouble of battery replacement and work stop due to insufficient power.

Further, according to the present invention, since the automatic frequency control mechanism is used when a plurality of polishing operations are performed simultaneously and the polishing information is wirelessly transmitted / received, a stable reception state can be obtained even if a frequency change due to a temperature change occurs. can do. Further, according to the present invention, during polishing, when the abnormality of the vibration intensity detected by the vibration detecting element attached to the surface plate is detected and the abnormality detection time of the vibration intensity is shorter than the rotation cycle of the surface plate. Since a signal analysis unit that outputs a signal indicating the presence of dust is provided in the above, it is possible to prevent the subsequent occurrence of scratches due to dust on the polishing surface of the object to be polished.

According to still another aspect of the present invention, in a structure having an air bag type upper surface plate which is vibration-proofed from a casing whose inside is kept airtight, a vibration for detecting a vibration in a circumferential direction. Since the detection element is attached to the upper surface plate and the polishing is completed by changing the signal of the vibration intensity or the vibration spectrum output from the vibration detection element,
By knowing the vibration intensity of the air bag type upper surface plate in the rotating direction and the change of its spectrum, it becomes easy to judge the change of the polishing state.

Further, when the signal from the vibration detecting element is output to the control section via the bandpass filter, the vibration component depending on the vibration of the frequency unique to the polishing apparatus is removed according to the polishing apparatus and polishing conditions. Then, only the vibration generated by the actual polishing can be selected. Further, when the vibration signal detected by the vibration detection element is sent to the control unit wirelessly, the amplitude range of the vibration signal is expanded via the logarithmic amplifier and sent wirelessly, and when the vibration signal is restored by the antilogarithmic amplifier after reception, The S / N ratio is improved.

Further, when the output signal from the vibration detecting element is small, the output signal can be increased by connecting a plurality of vibration detecting elements. Moreover, since the unnecessary vibration components are increased by the plurality of vibration detection elements, the orientation and arrangement of the vibration detection elements should be selected so that the unnecessary vibration components cancel each other out and the necessary vibration components are added. Therefore, noise due to unnecessary vibration components can be reduced and the S / N ratio can be improved.

Further, according to another polishing apparatus of the present invention, when the vibration detecting element detects the vibration of the object supporting board which changes with the progress of polishing, the soundproof material is arranged around the vibration detecting element. Therefore, the background noise of the motor or the like is suppressed from being input to the vibration detection element, and the S / N ratio is reduced.
The ratio can be improved. Also, when detecting the vibration of the object support plate that changes with the progress of polishing with the vibration detection element,
Since the frequency of the vibration to be detected is converted into the maximum sensitivity frequency of the vibration detecting element, the S / N ratio can be improved.

When the vibration detecting element detects the vibration of the object supporting plate which changes with the progress of polishing, the object supporting the object is a diaphragm having a natural vibration frequency which is the same as the vibration frequency to be detected. Since it is interposed between the board and the vibration detection element, the detected vibration input to the vibration detection element can be resonated and amplified, and the S / N ratio is improved.

Further, when the vibration detecting element detects the vibration of the object supporting plate which changes with the progress of polishing, the vibration transmitting body which penetrates the object supporting plate and contacts the vibration detecting element and the object to be polished. Since the above is provided, the vibration transmission efficiency from the object to be polished to the vibration detection element is improved, and the S / N can be improved. Further, when detecting the vibration of the object support plate that changes with the progress of polishing by the vibration detection element, the supply of energy for driving the object support plate is temporarily stopped at the time of detection. The background noise can be greatly reduced and the S / N ratio can be improved.

Further, when the vibration detecting element detects the vibration of the object supporting board which changes with the progress of polishing, the vibration frequency to be detected and the vibration frequency of the background noise are made different, and the object to be polished is made different. Since the natural vibration frequency of the support board and the vibration frequency to be detected are the same, the S / N ratio can be improved. Further, when the vibration detecting element detects the vibration of the object supporting plate that changes with the progress of polishing, a diaphragm vibrating in a phase opposite to the background noise is interposed between the object supporting plate and the vibration detecting element. Therefore, the input of background noise to the vibration detecting element can be eliminated to improve the S / N ratio.

Further, when the vibration detecting element detects the vibration of the polishing object supporting plate which changes with the progress of polishing, a plurality of vibration detecting elements are mounted on the polishing object supporting plate so that the vibration can be detected. The time and effort required for replacement due to element failure can be reduced. Further, according to the polishing apparatus of the present invention, since it has a displacement detector for detecting the position of the object support plate during polishing, the friction force of the polishing cloth and the object to be polished increases as the polishing progresses. The position of the object support plate changes due to the change, and the end point of polishing or the like can be detected by the amount of change in the displacement. In this case, the amount of change in the position of the object support plate has a vibration frequency band different from that of the background noise, so that a good S / N ratio can be detected without being affected by vibration of the motor or the like.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a polishing apparatus according to a first embodiment of the present invention.

2 (a) and 2 (b) are plan views showing the grooves of the polishing cloth applied to the polishing apparatus of the first embodiment of the present invention.

FIG. 3 is a perspective view in which a head used in the polishing apparatus according to the first embodiment of the present invention is partially cut.

FIG. 4 is a spectrum showing a relationship between a vibration frequency and a vibration intensity detected by a vibration detecting element during polishing using the polishing apparatus according to the first embodiment of the present invention.

5 (a) and 5 (b) are cross-sectional views showing a part of the process of manufacturing a semiconductor device.

6A and 6B are cross-sectional views showing a first example of polishing an insulating film of a semiconductor device by using the polishing apparatus of the first embodiment of the present invention.

FIGS. 7A and 7B are cross-sectional views showing a second example of polishing an insulating film of a semiconductor device by using the polishing apparatus of the first embodiment of the present invention.

FIGS. 8A to 8C are cross-sectional views showing a first example of a transition of polishing an insulating film of a semiconductor device using the polishing apparatus of the first embodiment of the present invention.

9A to 9C are cross-sectional views showing a second example of the transition of polishing an insulating film of a semiconductor device using the polishing apparatus of the first embodiment of the present invention.

FIG. 10 is a waveform diagram showing a change in vibration output from the vibration detection element of the polishing apparatus according to the first embodiment of the present invention.

FIG. 11 is a side view showing a head portion of a polishing apparatus according to a second embodiment of the present invention.

FIG. 12 is a side view showing a head portion of a polishing apparatus according to a second embodiment of the present invention.

FIG. 13 is a side view showing a head portion of a polishing apparatus according to a third embodiment of the present invention.

FIG. 14 is a side view showing a head portion of a polishing apparatus according to a fifth embodiment of the present invention.

FIG. 15 (a) is a side view showing a polishing apparatus according to a sixth embodiment of the present invention, and FIG. 15 (b) is a perspective view showing the positional relationship between the transmitting antenna and the receiving antenna.

FIG. 16 is a block diagram showing a circuit configuration of a polishing apparatus according to a seventh embodiment of the present invention.

FIG. 17 is a side view showing a polishing apparatus according to an eighth embodiment of the present invention.

FIG. 18 is a bottom view of an upper surface plate of a polishing apparatus according to an eighth embodiment of the present invention.

FIG. 19 is a block diagram showing a signal system of a polishing apparatus according to an eighth embodiment of the present invention.

FIG. 20 is a diagram showing an example of the relationship between the pass frequencies and the signal transmittances of a plurality of bandpass filters applied to the polishing apparatus of the eighth embodiment of the present invention.

FIG. 21 is a spectrum showing the relationship between the vibration frequency and the vibration intensity detected by the vibration detecting element of the polishing apparatus according to the eighth embodiment of the present invention.

22 (a) and 22 (b) are a side view of a polishing apparatus according to a ninth embodiment of the present invention and a bottom view of an upper surface plate of the polishing apparatus.

FIGS. 23 (a) and 23 (b) are side views showing a first example of vertical vibration of an upper surface plate of a polishing apparatus according to a ninth embodiment of the present invention.

FIGS. 23 (a) and 23 (b) are side views showing a second example of the vertical vibration of the upper surface plate of the polishing apparatus of the ninth embodiment of the present invention.

25 (a) and 25 (b) are block diagrams showing two examples of the signal system applied to the ninth embodiment of the present invention.

26 (a) and 26 (b) are a side view and a plan view of a polishing apparatus according to a tenth embodiment of the present invention.

27 (a) and 27 (b) are spectra showing the relationship between the vibration frequency and the vibration intensity according to the tenth embodiment of the present invention.

FIG. 28 is a spectrum diagram showing an abnormal signal due to dust and an abnormal signal other than the abnormal signal by the polishing apparatus according to the tenth embodiment of the present invention.

FIG. 29 is a partial cross-sectional view showing an example in which a sound absorbing material is provided in the head in the polishing apparatus of the eleventh embodiment of the present invention.

FIG. 30 is a partial cross-sectional view showing an example in which a vibrating body is attached to the bottom of a vibration detecting element in the polishing apparatus of the eleventh embodiment of the present invention.

FIG. 31 is a partial cross-sectional view showing an example in which a vibrating body is attached to the bottom of a vibration detecting element in a polishing apparatus according to an eleventh embodiment of the present invention.

FIG. 32 is a partial cross-sectional view showing an example in which a vibration transmitting needle is interposed between a vibration detecting element and an object to be detected in the polishing apparatus according to the eleventh embodiment of the present invention.

FIG. 33 is a partial cross-sectional view showing an example in which a polishing device according to an eleventh embodiment of the present invention is provided with a circuit for eliminating noise vibration input to a vibration detection element.

FIG. 34 is a partial cross-sectional view showing an example in which a circuit for changing the vibration frequency input to the vibration detection element is provided in the polishing apparatus of the eleventh embodiment of the present invention.

[FIG. 35] FIG. 35 is a partial cross-sectional view showing an example in which a plurality of vibration detection elements and a plurality of vibration plates attached to the bottom surface are provided in the polishing apparatus of the eleventh embodiment of the present invention.

FIG. 36 is a characteristic diagram showing the relationship between the vibration frequency and the sensitivity of the vibration detecting element applied to the polishing apparatus of the present invention.

FIG. 37 is a spectrum showing the relationship between the frequency and the intensity of the natural polishing vibration detected by the polishing apparatus of the eleventh embodiment of the present invention.

FIG. 38 is a characteristic diagram showing the amount of change over time in the integrated value of the spectrum of the polishing natural vibration detected in the polishing apparatus of the eleventh embodiment of the present invention.

39 (a) and 39 (b) are a side view of a polishing apparatus of a twelfth embodiment of the present invention and a plan view showing a lower surface plate and a polishing cloth.

FIG. 40 is a block diagram showing a signal system of a polishing apparatus according to a twelfth embodiment of the present invention.

FIG. 41 is a block diagram showing signal processing of a computer in the polishing apparatus according to the twelfth embodiment of the present invention.

FIG. 42 (a) is a diagram showing a vibration intensity curve before correction, in which sampling data is averaged and displayed in the polishing apparatus of the twelfth embodiment of the present invention, and a corrected vibration intensity curve, FIG. 42 (b) is a diagram showing a curve obtained by differentiating the vibration intensity curve before and after the correction.

FIG. 43 (a) shows the center of rotation of the upper surface plate and the center of rotation of the polishing cloth when the upper surface plate moves in the diametrical direction of the polishing cloth in the polishing apparatus of the twelfth embodiment of the present invention. 43 (b) is a waveform diagram showing a change in the distance r, and FIG. 43 (b) is a waveform diagram of the correction function using the distance r.

44 (a) to 44 (d) are plan views showing variations of the polishing cloth used in the polishing apparatus of the twelfth embodiment of the present invention.

FIG. 45 (a) is a plan view showing a second example of the movement trajectory of the upper surface plate in the polishing apparatus of the twelfth embodiment of the present invention, and FIG. 45 (b) is the movement trajectory thereof. It is a wave form diagram which shows the change of the distance r of the rotation center of the upper surface plate and the rotation center of the polishing cloth.

FIG. 46 (a) is a plan view showing a third example of the movement trajectory of the upper surface plate in the polishing apparatus of the twelfth embodiment of the present invention, and FIG. 46 (b) shows the movement trajectory. It is a wave form diagram which shows the change of the distance r of the rotation center of the upper surface plate and the rotation center of the polishing cloth.

47 is a vibration intensity curve showing a temporal change when the upper surface plate does not move on the polishing cloth in the polishing apparatus of the twelfth embodiment of the present invention, and FIG. 47 (b) shows the vibration intensity. It is a differential curve of a curve.

48 (a) and 48 (b) are a sectional view and a bottom view showing a main part of a polishing apparatus according to a thirteenth embodiment of the present invention.

49 (a) to 49 (c) are bottom views showing changes due to polishing of the bottom surface of the head of the polishing apparatus of the thirteenth embodiment of the present invention.

FIG. 50 is a diagram showing the amount of change in displacement of the upper surface plate due to progress of polishing in the polishing apparatus of the thirteenth embodiment of the present invention.

FIG. 51 is a diagram showing a comparison between a change amount of displacement of the upper surface plate due to progress of polishing and a reference signal in the polishing apparatus according to the thirteenth embodiment of the present invention.

52 (a) and 52 (b) are partial cross-sectional views of the head showing a state in which a protrusion is formed in the vibration detection region in the polishing apparatus of the thirteenth embodiment of the present invention.

[Explanation of symbols]

1,1d polishing cloth 2 Lower surface plate 2a cavity 3 Upper surface plate 3a cavity 3b Side wall 4 first groove 5 second groove 6 Second groove (cavity) 7 Elastic part 8 indicators 9 shaft 10, 10A, 10B Vibration detection element 11 nozzles 12 Dresser 13, 13A transmitter 14 receiver 15 Drive controller 16 Display 21 Shaft drive 22 Elastic part 23 Swing device 24 belts 25 transmitting antenna 26 Receiving antenna 27 signal line 28 ring conductor 29 brushes 30 electric wires 31 synthesizer 32 receiver 33 Signal analysis unit 34a, 34d, 34e First amplifier 34b filter 34c Second amplifier 34B FM transmitter 35 processing unit 41 Upper surface plate 42 Accelerometer 43 Lower surface plate 44 polishing cloth 45 markers 46 Marker detector 50 Soundproof / Sound absorbing material 51 inner sheet 52 Resonance plate 53 amplifier 54 holes 55 Vibration transmission needle 56 diaphragm 57 Vibration detection element 58 Vibration controller 59 Frequency conversion circuit 61 Position detector 62 detection plate 63 Rectifier 64 capacitors 65 amp 66 low-pass filter 67 High Pass Filter 69 FM receiver 70 Recording device 71 Filter 72 First Amplifier 73 Rectifier circuit 74 Low Pass Filter 75 Second amplifier 76 A / D converter 77 Computer 81, 82, 83 Displacement detector 91, 92 protrusion

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-6-320416 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B24B 37/04 B24B 49/10 H01L 21 / 304

Claims (16)

(57) [Claims] 1. A first platen for supporting an object to be polished, a first drive mechanism for rotating the first platen, and a second platen arranged so as to face the first platen. A surface plate, a polishing cloth attached to the second surface plate, a vibration detector attached to the first surface plate or the second surface plate for detecting vibration during polishing, and at least the first surface plate A control unit for controlling the polishing operation of one of the surface plate No. 1 and the second surface plate; frequency analysis is performed on the vibration intensity detected by the vibration detector; At least one of the first surface plate and the second surface plate is stopped when the time change of the value is below the reference value or when the integrated value is below the reference value. And a signal analysis unit that sends a polishing stop signal to the control unit. 2. The polishing apparatus according to claim 1, wherein an elastic body is formed around the first surface plate. 3. A groove or a hole is formed on the surface of the polishing cloth, and a cavity that resonates with the vibration of the surface is formed inside the polishing cloth. Polishing equipment. 4. The polishing apparatus according to claim 1, wherein a plurality of bandpass filters having different center frequencies are combined and connected to the output end side of the vibration detector. 5. A signal analysis unit that determines whether polishing is started, stopped, or whether polishing conditions are satisfied, a transmission unit that wirelessly transmits vibration information of polishing detected by the vibration detector, and the transmission. Has a frequency control mechanism for receiving a radio signal output from the unit and automatically holding the variation of the tuning frequency of the radio signal within the range of the reference frequency, and the signal analysis unit requests reception data. The polishing apparatus according to any one of claims 1 to 4, further comprising: a receiver that receives the oscillation frequency of the transmitter by the automatic frequency control mechanism. 6. The polishing apparatus according to claim 1, wherein the vibration detector is an element that detects vibration in a longitudinal direction or a circumferential direction. 7. A plurality of the vibration detectors are mounted symmetrically with respect to the center of rotation of the first surface plate, and a plurality of computing units for calculating the sum or difference of the output signals of the plurality of vibration detectors are provided. The polishing apparatus according to any one of claims 1 to 6, which is connected to an output end of the vibration detector. 8. A vibration converting means for converting a vibration frequency detected by the vibration detector into a resonance frequency of the vibration detector is connected to the vibration detector. The polishing device described. 9. An object to be polished is supported by the first surface plate via an inner sheet, and the object to be polished is passed through the through holes formed in the first surface plate and the inner sheet and the through hole. 9. The polishing apparatus according to claim 1, further comprising a vibration transmitter that contacts both the object and the vibration detector. 10. A second drive mechanism for rotating the second platen is connected to the second platen, and the first drive mechanism is connected to the first platen.
The platen has a first natural vibration frequency that is the same as the vibration frequency to be detected by the vibration detector,
At least one of the said 1st drive mechanism and the said 2nd drive mechanism has a 2nd natural vibration frequency different from the said 1st natural vibration frequency, The claim 1 characterized by the above-mentioned. Polishing equipment. 11. A first platen for supporting an object to be polished, and
A second surface plate arranged to face the first surface plate, and the second surface plate
Using a polishing cloth attached to the surface plate of the
In the polishing method of polishing an elephant with the above-mentioned polishing cloth,
A motion detector, the first surface plate or the second surface plate
Vibration during polishing is detected, and the vibration intensity output from the vibration detector is frequency analyzed.
Then, the vibration intensity is integrated every time, and the integrated value
Change is below the standard value, or the integrated value is below the standard value.
Characteristic that polishing is stopped at any point when it falls below
And polishing method. 12. The integrated value is an average value of a plurality of vibration intensities.
The polishing method according to claim 11, wherein 13. A concave surface formed on the object to be polished.
It is possible to flatten a film having a protrusion with the polishing cloth.
The polishing method according to claim 11 or 12, which is characterized in that. 14. The time from polishing start to polishing stop is set by
Shorter than the fixed time, or the time change of the integrated value
If either of the values decreases below the specified value,
The deterioration according to claim 11 to 13, characterized in that the deterioration is recognized.
Any one of the polishing methods. 15. A vibration of a specific vibration frequency during the polishing time.
The rate of decrease of the dynamic strength becomes the rate of decrease of the vibration strength of other vibration frequencies.
Compared with changing the polishing conditions
The polishing method according to any one of claims 11 to 14, characterized in that
Law. 16. The vibration intensity output from the vibration detector
Based on the change in signal or vibration spectrum
Analyze in real time to detect the polishing end point or
The case according to claim 11 to 13, characterized in that the number of cases is changed.
Abrasive method described.