Acoustic monitoring of regulators during polishing

Abstract

A chemical mechanical polishing device comprises: a table for supporting a polishing pad; the regulator head is used for keeping the regulator disc in contact with the polishing pad; the motor is used for generating relative movement between the polishing pad and the adjuster disc so as to adjust the polishing pad; an in-situ acoustic monitoring system having an acoustic sensor to receive an acoustic signal from the regulator disk; and a controller configured to analyze the signal from the acoustic sensor and determine a characteristic of the regulator disc or the regulator head based on the signal.

Description

Technical Field

[0001] The present disclosure relates to chemical mechanical polishing, and more particularly, to acoustic monitoring during chemical mechanical polishing. Background Art

[0002] Integrated circuits are typically formed on a substrate by sequentially depositing a conductive layer, a semiconductive layer, or an insulating layer on a silicon wafer. One manufacturing step involves depositing a fill layer on a non-planar surface and planarizing the fill layer. For some applications, the fill layer is planarized until the top surface of the patterned layer is exposed. For example, a conductive fill layer may be deposited on a patterned insulating layer to fill trenches or holes in the insulating layer. After planarization, portions of the conductive layer remaining between the raised patterns of the insulating layer form vias, plugs, and lines that provide conductive paths between thin film circuits on the substrate. For other applications such as oxide polishing, the fill layer is planarized until a predetermined thickness is left on the non-planar surface. In addition, photolithography typically requires planarization of the substrate surface.

[0003] Chemical mechanical polishing (CMP) is an acceptable planarization method. This planarization method generally requires the substrate to be fixed on a carrier head or polishing head. The exposed surface of the substrate is generally placed against a rotating polishing pad. The carrier head provides a controllable load on the substrate to push the substrate against the polishing pad. An abrasive polishing slurry is generally supplied to the surface of the polishing pad.

[0004] When the polisher is in operation, the pad is subjected to compression, shear and friction, which generates heat and wear. Slurry and abraded material from the wafer and pad are squeezed into the pores of the pad material, and the material itself becomes matte and even partially fused. These effects (sometimes referred to as "glazing") reduce the roughness of the pad and the ability to apply fresh slurry to the substrate. Therefore, it is desirable to condition the pad by removing trapped slurry and de-matting, re-expanding or re-roughening the pad material.

[0005] Polishing systems typically include a conditioner system to condition the polishing pad. Conditioning of the polishing pad maintains the polishing surface at a consistent roughness to ensure uniform polishing conditions from wafer to wafer. Conventional conditioner systems have a conditioner head that holds a conditioner disk having an abrasive lower surface (e.g., with diamond particles) placed in contact with the polishing pad. The contact and movement of the abrasive surface against the polishing pad roughens the polishing surface. However, the conditioner disk itself is subject to wear and periodically needs to be replaced. Summary of the invention

[0006] In one aspect, a chemical mechanical polishing apparatus includes a table for supporting a polishing pad; a conditioner head for maintaining a conditioner disk in contact with the polishing pad; a motor for generating relative motion between the polishing pad and the conditioner disk so as to condition the polishing pad; an in-situ acoustic monitoring system having an acoustic sensor for receiving an acoustic signal from the conditioner disk; and a controller configured to analyze the signal from the acoustic sensor and determine a characteristic of the conditioner disk or the conditioner head based on the signal.

[0007] One or more of the following possible advantages may be achieved.

[0008] Wear of the adjuster disk may be monitored in situ, and the end of life of the adjuster disk may be detected in situ and more reliably. If the end of life of the adjuster is detected, a warning may be generated to trigger replacement of the adjuster disk. The risk of defects or scratches of the base plate may be reduced. The useful life of the adjuster disk may be improved, and downtime for replacing the adjuster disk may be reduced, thus improving the cost of ownership. Other anomalies associated with the adjuster may be detected, and a warning may be generated to trigger corrective action. For example, incorrect installation of the adjuster disk or incorrect adjustment down force may be detected.

[0009] The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, and from the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a schematic side view of a polishing system including a conditioner and an in-situ acoustic monitoring system.

[0011] Figure 2A A schematic top view of the polishing system.

[0012] Figure 2B Graph showing the division of the signal from the acoustic sensor by position relative to the actuator.

[0013] Figure 3 is a graphical representation of example acoustic signals and segments corresponding to different portions of the ring assembly or base plate.

[0014] Figure 4 is a schematic side view of another embodiment of a polishing system including a conditioner and an in-situ acoustic monitoring system.

[0015] In the drawings, like reference numerals indicate like elements. DETAILED DESCRIPTION

[0016] The chemical mechanical polishing process may include a pad conditioning step in which a conditioner disk (e.g., a disk coated with abrasive diamond particles) is pressed against a rotating polishing pad to condition and texture the polishing pad surface. However, the friction of the pad against the abrasive particles of the conditioner disk and / or the chemicals of the polishing liquid may gradually wear the conditioner disk. For example, the abrasive particles may become dull, reducing the wear rate, or the abrasive particles may become loose from the conditioner disk, resulting in scratches and defects on the substrate. Therefore, the conditioning disk periodically needs to be replaced. However, due to simple manufacturing variations, conditioning disks may not all have the same lifespan.

[0017] One approach is to simply replace the conditioning disk after set intervals, such as replacing the conditioning disk after polishing a preset number of substrates or after a preset time of use. However, this carries the risk of under-use (i.e., replacing a disk that still has useful life left) or over-use of the conditioning disk, with the risk of damaging the substrate. Another approach is to monitor the wear of the polishing pad; a change in the wear rate may indicate that the conditioner disk has a problem. However, this is an indirect indication; the conditioner disk may be subject to wear and the risk of abrasive particles breaking away without a change in the wear rate.

[0018] Monitoring the acoustic signal from the conditioner disk can resolve these problems and can be a more reliable technique for detecting that the conditioner disk needs to be replaced.Even if the life of the conditioner disk is not monitored, acoustic monitoring can provide indications of other anomalies, thereby permitting corrective action to be taken by the operator of the polishing system.

[0019] like Figure 1 and Figure 2A The chemical mechanical polishing system 20 includes a rotatable table 24 on which a polishing pad 30 is mounted. The table 24 is operable to rotate about an axis 25 (see Figure 2A 2. For example, the motor 22 may rotate the drive shaft 28 to rotate the table 24. The polishing pad 30 may be a dual layer polishing pad having an outer polishing layer 34 with a polishing surface 36 and a softer backing layer 32.

[0020] The polishing system 20 includes a supply port 64 (e.g., at the end of a slurry supply arm 62) to dispense a polishing liquid 60 (such as an abrasive slurry) onto the polishing pad 30. In some embodiments, the polishing system 20 includes a wiper blade or body to evenly distribute the polishing liquid 60 across the polishing pad 30.

[0021] The carrier head 70 is suspended from a support structure 72 (eg, a turntable or track) and is connected to a carrier head rotation motor 76 via a drive shaft 74 so that the carrier head can rotate about an axis 71 (see Figure 2A Alternatively, the carrier head 70 may oscillate laterally (see arrow B in FIG. Figure 2AThe polishing pad 30 is a polishing pad that is formed on the worktable 25 and the carrier head 70 is a polishing pad that is formed on the worktable 25. .... The polishing pad 30 is a polishing pad that is formed on the worktable 25. The polishing pad 30 is a polishing pad that is formed on the worktable 25. The polishing pad 30 is a polishing pad that is formed on the worktable 25. The polishing pad 30 is a polishing pad that is formed on the worktable 25. The polishing pad 30 is a polishing pad that is formed on the worktable 25. The polishing pad 30 is a polishing pad that is formed on the worktable 25. Figure 1 Three chambers are shown in FIG. 8 , but there may be one or two chambers, or four or more chambers, such as five chambers. Carrier head 70 may also include a retaining ring 84 to hold the substrate below membrane 80 .

[0022] A controller 90, such as a programmable computer, is coupled to the motors 121, 154 to control the rotational rates of the table 120 and the carrier head 140. For example, each motor may include an encoder to measure the rotational rate of the associated drive shaft.

[0023] The polishing station 20 also includes a pad conditioner 40 having a conditioner disk 50 to maintain the surface roughness of the polishing pad 30. The bottom surface of the conditioner disk 50 includes one or more abrasive regions 52 that contact the polishing surface 36 during the conditioning process. The abrasive regions may be provided by abrasive diamond particles secured to the lower surface of a backing plate 54. The backing plate 54 is typically metal, such as stainless steel, although other materials, such as ceramics, are possible. In some embodiments, abrasive particles of other compositions (e.g., silicon carbide) are used instead of or in addition to diamond particles.

[0024] During conditioning, the abrasive region moves relative to the surface of the polishing pad 30, thereby abrading and retexturing the polishing surface 36. For example, both the polishing pad 30 and the conditioning disk 50 may rotate (see Figure 2A Arrows A and D in the figure).

[0025] Conditioner disk 50 may be held at the end of arm 42 by conditioner head 46. Arm 42 and conditioner head 46 are supported by base 48. Arm 42 may swing to sweep conditioner head 46 and conditioner disk 50 laterally across polishing pad 30 (see FIG. Figure 2A 4. For example, the base 48 may be driven by a motor 49 to pivot about a vertical axis and thereby sweep the arm 42 and conditioner head 46 laterally over the table 24 and polishing pad 30.

[0026] Conditioner head 46 includes a mechanism to attach conditioner disk 50 to conditioner head 46 (such as a mechanical attachment system, e.g., bolts or screws, or a magnetic attachment system), and a mechanism to rotate conditioner disk 50 about axis 41 (such as a drive belt passing through an arm or a rotor inside conditioner head). In addition, pad conditioner 40 may also include a mechanism to modulate the pressure between conditioner disk 50 and polishing pad 30 (such as a pneumatic or mechanical actuator inside the conditioner head or base) and / or a mechanism to change the vertical position of conditioner disk 50 relative to polishing pad 30. For example, conditioner head 46 may include an upper portion 46a, a lower portion 46b that holds conditioner disk 50, and an actuator that adjusts the vertical position of lower portion 46b relative to upper portion 46a or adjusts the pressure of conditioner disk 50 on polishing pad 30. However, these mechanisms may have many possible implementations (and are not limited to Figure 1 As other examples, a vertical actuator may be positioned in base 48 to raise and lower arm 42, or the arm may be pivotally attached to base 48 in a manner that permits the arm to swing vertically to lower and raise conditioner head 46 from polishing pad 30.

[0027] The polishing system 20 includes at least one in-situ acoustic monitoring system 100. The in-situ acoustic monitoring system 100 includes an acoustic sensor 102. Figure 1 In the embodiment shown in , the acoustic sensor 102 is positioned on a side of the substrate 10 that is farther from the polishing pad 30, and will receive the acoustic signal from the substrate conditioner disk 50 through the polishing pad 30. In particular, the acoustic sensor 102 can be supported on the table 24. For example, the acoustic sensor 102 can be positioned in a recess 28 in the table 24. In some embodiments, the top surface of the acoustic sensor 102 is coplanar with the top surface of the table 24.

[0028] The acoustic sensor 102 is positioned on the table 24 at a radial position (from the axis 25) so that the sensor 102 will sweep under the adjuster disk 50 for at least some lateral positions of the adjuster head 46. For example, the acoustic sensor 102 may be positioned at a midpoint between the edge of the table 24 and the axis of rotation 25.

[0029] In some embodiments, the portion of the polishing pad directly above the acoustic sensor 102 may include an acoustic window 120, e.g., an area having a lower acoustic impedance than the surrounding polishing material. The acoustic window 120 may extend through the polishing layer 32 or the backing layer 34, or both. However, if the acoustic transmission of the polishing pad is sufficiently high, the acoustic window 120 may not be necessary.

[0030] The acoustic sensor 102 may be a contact acoustic sensor having a surface connected to a portion of the polishing pad (e.g., directly contacting the portion, or having only an adhesive layer for attaching to the portion, or having only an acoustic glue for transmitting an acoustic signal from the portion), such as the polishing layer 32 or the backing layer 34 or the acoustic window 120. For example, the acoustic sensor 102 may be an electromagnetic acoustic transducer or a piezoelectric acoustic transducer. The piezoelectric sensor may include a rigid contact plate, such as made of stainless steel, etc., which is placed in contact with the subject to be monitored, and a piezoelectric component on the back side of the contact plate, such as a piezoelectric layer sandwiched between two electrodes.

[0031] In some embodiments, the spring 106 is positioned to urge the acoustic sensor 102 into contact with a portion of the polishing pad 30. In some embodiments, the spring 106 is a long-travel spring.

[0032] The acoustic sensor 102 may be connected to a power source and / or other signal processing electronics 110 via a rotary coupling 112 (e.g., a mercury slip ring) through the circuit system 108. The signal processing electronics 110 may in turn be connected to the controller 90. In some embodiments, some or all of the functions of the signal processing electronics 110 are performed by the controller 90.

[0033] In some embodiments, the in-situ acoustic monitoring system 100 is a passive acoustic monitoring system. In this case, the signal is monitored by the acoustic sensor 102 without generating a signal from the acoustic signal generator (or the acoustic signal generator may be omitted from the system entirely). The passive acoustic signal monitored by the acoustic sensor 162 may be in the range of 50kHz to 1MHz, for example, 200kHz to 400kHz, or 200Khz to 1MHz.

[0034] The signal from the sensor 102 can be amplified by a built-in internal amplifier. In some embodiments, the amplification gain is between 40 dB and 60 dB (e.g., 50 dB). If necessary, the signal from the acoustic sensor 106 can then be further amplified and filtered, and digitized to a high-speed data acquisition board, for example, in the electronic component 108 or 110, through an A / D port. The data from the acoustic sensor 102 can be recorded at a range from 1 MHz to 10 MHz (e.g., 1-3 MHz or 6-8 MHz). In an embodiment in which the acoustic sensor 162 is a passive acoustic sensor, a frequency range from 100 kHz to 2 MHz can be monitored, such as 500 kHz to 1 MHz (e.g., 750 kHz).

[0035] A position sensor (e.g., an optical interrupter connected to the rim of the table or a rotary encoder) may be used to sense the angular position of the table 24. This permits only the portion of the signal measured when the sensor 102 is close to the adjuster disk 50 (e.g., when the sensor 102 is below the adjuster disk 50) to be used as an indication of the adjuster disk condition in subsequent signal processing.

[0036] Reference Figure 2A , due to the motion of the table 24 (shown by arrow A), the acoustic sensor 102 sweeps in a path 200 that travels under the adjuster disk 50. The acoustic monitoring system 100 (e.g., the controller 90) may be configured to sample signals from the sensor 102 as the sensor passes under the adjuster disk 50. For example, the controller 90 may determine the angular position of the sensor 102 based on input from a motor encoder or a table position sensor, and compare the angular position to the position of the adjuster head (e.g., based on the adjuster sweep information). Determining the position of the sensor relative to the substrate is discussed in U.S. Pat. No. 6,159,073 and U.S. Pat. No. 6,296,548; equivalent techniques may be applied to move the adjuster disk. This permits identification and selection of portions of the received signal when the sensor 102 is under the adjuster disk 50.

[0037] Reference Figure 2A and Figure 2B , the signal 220 from the sensor 102 may include a portion 222 corresponding to the sensor 102 outside the adjuster disk 50 but approaching the adjuster disk 50 (indicated by the area 202 of the path 200 and referred to as the "leading adjuster-out data"), a portion 224 corresponding to the sensor 102 below the adjuster disk 50 (referred to as the "upper adjuster data"), and a portion 222 corresponding to the sensor 102 outside the adjuster disk 50 and behind the adjuster disk 50 (indicated by the area 204 of the path 200 and referred to as the "trailing adjuster-out data"). The leading and trailing adjuster-out data may each correspond to an arc of 5-30° traveled by the sensor 102 along the path 200.

[0038] Figure 3 An example of an acoustic signal 300 is illustrated. As shown, the signal strength may increase when the sensor 102 is positioned below the regulator disk 50 (i.e., for "on regulator data"). The acoustic monitoring system 100 may process the acoustic signal 300 and subdivide the acoustic signal 300 into segments, which may aid in subsequent signal processing.

[0039] Generally, at least the on-conditioner data 226 is used for monitoring the conditioner disk 50 discussed below. In some embodiments, the leading off-conditioner data 222 and / or the trailing off-conditioner data 230 are also used for monitoring the conditioner disk 50. However, in some embodiments, only the on-conditioner data is used. Portions of the signal not used in the conditioner disk monitoring may still be used for other monitoring purposes, such as detection of polishing endpoint or detection of defects on the substrate 10.

[0040] Back to Figure 1 , the acoustic signal generated by the interface between the conditioner disk 50 and the polishing layer 112 of the polishing pad 110 travels through the polishing pad 110 and is received by the acoustic sensor 102. The acoustic sensor 102 transmits the received acoustic signal to the signal processing electronic component 110, and the signal processing electronic component 110 performs a function on the received acoustic signal. The electronic component 110 may include, for example, a filter, an amplifier, a spectrum analyzer, a data acquisition system (DAQ), or other components for processing the received acoustic signal. In general, the electronic component 110 may include a general-purpose programmable computer, a dedicated circuit system, or a combination of the above. In some embodiments, the electronic component 110 is within the controller 90, for example, implemented by the controller 90.

[0041] The signal from the acoustic sensor 102 (e.g., after amplification, preliminary filtering, and digitization) may be subjected to data processing (e.g., in the controller 90) for use in detecting a wear state of the regulator disk 50 and / or detecting other anomalies of the regulator head 46. The controller 90 may generate an alert indicating the type of event, for example, the alert may indicate that the regulator disk needs to be replaced, or that the regulator disk is improperly attached to the regulator head, or that the pressure of the regulator disk does not match what is expected.

[0042] In some embodiments, the controller 90 is configured to monitor changes in acoustic signal strength. For example, for an active acoustic monitoring system (where the sensor 102 transmits acoustic energy), the received signal strength is compared to the transmitted signal strength to produce a normalized signal, and the normalized signal can be monitored over time to detect changes. As another example, for a passive acoustic monitoring system, the received signal strength is compared to a measured initial signal strength (e.g., obtained when the regulator disc is newly installed on the carrier head) to produce a normalized signal, and the normalized signal can be monitored over time to detect changes. Such changes can indicate changes in the regulator disc, for example, the regulator disc has worn and needs to be replaced.

[0043] As another example, the amount of noise in the monitoring signal, for example, the deviation of the signal, such as the root mean square difference. For example, the deviation value calculated for the signal can be compared to a threshold. If the deviation value exceeds the threshold, this can indicate a change in the regulator disk, for example, the regulator disk is worn and needs to be replaced.

[0044] In some embodiments, a frequency analysis of the signal is performed. For example, frequency domain analysis can be used to determine changes in the relative power of spectral frequencies. In particular, a Fourier transform (e.g., a fast Fourier transform (FFT)) can be performed on the signal to produce a spectrum (e.g., a power, wavelength, or frequency spectrum). A specific band of power, wavelength, or frequency can be monitored, and if the intensity in the band exceeds a threshold, this can indicate that the regulator disk is worn and needs to be replaced. Alternatively, if the location (e.g., wavelength) or bandwidth of a local maximum or minimum in a selected frequency range exceeds a threshold, this can indicate a change in the regulator disk, for example, the regulator disk is worn and needs to be replaced.

[0045] In some embodiments, the spectrum of the signal can be compared to a reference spectrum. If the difference (e.g., the sum of the squares of the differences in power, wavelength, or frequency range) exceeds or falls below a threshold, this can indicate a change in the regulator disk, such as the regulator disk is worn and needs to be replaced.

[0046] The determination of the appropriate characteristics of the signal to be monitored and the appropriate criteria for triggering the indication of a change in the regulator disk can be determined empirically. For example, polishing can be performed with a worn regulator disk (e.g., a disk known to have a low polishing pad wear rate) and the spectrum of the signal from this regulator disk can be used as a reference spectrum. As another example, polishing can be performed with both a fresh regulator disk and a worn regulator disk. The spectra of the signals can be compared to empirically determine the power, wavelength, or frequency band for monitoring, and whether the worn regulator disk has a higher or lower signal strength in the band. Criteria for generating a signal indicating a warning that the regulator disk is worn and needs to be replaced can be derived, and the controller 90 can be configured to test whether the signal meets the criteria.

[0047] As another example, polishing can be performed with a regulator disc that is known to be incorrectly installed on the regulator head, and the spectrum of the signal from this incorrectly installed regulator disc can be used as a reference spectrum. As another example, polishing can be performed with both correctly installed and incorrectly installed regulator discs. The spectrum of the signal can be compared to empirically determine the power, wavelength, or frequency band for monitoring, and whether the incorrectly installed regulator disc has a higher or lower signal strength in the band. A standard for generating a signal indicating a warning that the regulator disc is not correctly installed can be derived, and the controller 90 can be configured to test whether the signal meets the standard.

[0048] As another example, polishing can be performed with a fresh adjuster disk, and the spectrum of the signal from the fresh disk can be used as a reference spectrum. This can provide a "gold" signal spectrum. If the measured spectrum of another disk deviates from the reference spectrum, this can indicate a problem. The controller 90 can then analyze which of the other known problems (e.g., a worn or improperly installed adjuster disk) provides the closest fit. If the spectrum corresponding to the known problem fails to match the measured spectrum within a threshold, the system can generate a general fault signal indicating an unknown problem.

[0049] As another example, polishing may be performed with the regulator disk at a first load corresponding to a desired pressure set by the polishing recipe, and polishing may be performed with the regulator disk at a different second load (e.g., a lower load). At the lower load on the regulator disk, there should be lower friction, and therefore a lower signal from the acoustic monitoring system. The spectra of the signals may be compared to empirically determine the power, wavelength, or frequency band for monitoring whether the friction on the regulator disk (and therefore the applied load) matches the expected value. A standard for generating a signal indicating a warning that the load on the regulator disk does not match the expected load may be derived, and the controller 90 may be configured to test whether the signal meets the standard.

[0050] In operation, acoustic signals are collected from the in-situ acoustic monitoring system 160. The signals are monitored to detect changes in the conditioner disk, or other problems with the conditioner head. Detected changes or problems may trigger a warning to the operator, or the polishing operation may be automatically stopped. Depending on the magnitude of the problem, the conditioner disk may be removed and replaced, or removed and reinstalled.

[0051] Figure 4 Another embodiment of an in-situ acoustic monitoring system is shown in which the sensor 102 is attached to the regulator head 46 rather than supported by the table. This simplifies signal processing because the controller 90 does not have to select the portion of the signal corresponding to the sensor 102 passing under the regulator disk 50. On the other hand, position information is lost; the sensor 102 is likely picking up acoustic signals from the entire regulator disk 50 and has no external regulator signal for calibration.

[0052] The controller 90, as well as other controls for other functional operations described in this specification, may be implemented in a digital electronic circuit system, or in computer software, firmware, or hardware, or in a combination of the above. The controller 90 and other functions may be implemented using one or more non-transitory computer program products, i.e., one or more computer programs tangibly embodied in a machine-readable storage device for execution by or to control the operation of a data processing apparatus, such as a programmable processor, a computer, or multiple processors or computers. The controller 90 and other functions may be implemented using one or more programmable processors (e.g., in a general-purpose computer) executing one or more computer programs, or using dedicated logic circuits, such as an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit).

[0053] Several embodiments of the present invention have been described. However, it will be appreciated that various modifications may be made. For example: • Instead of sweeping along an arcuate path, the adjuster head may move linearly (eg, be carried along a linear track). The polishing pad can be a belt driven by rollers rather than a round pad on a table. The polishing pad can be a fixed abrasive pad or other materials.

[0054] Although this specification contains many details, these details should not be interpreted as limitations on the scope of protection, but rather as descriptions of features specific to a particular example. Certain features described in this specification in the context of separate embodiments may also be combined. Conversely, various features described in the context of a single embodiment may also be implemented separately in multiple embodiments or in any suitable subcombination.

Claims

1. A chemical mechanical polishing device, comprising: a work table for supporting the polishing pad; a conditioner head for maintaining a conditioner disk in contact with the polishing pad; a motor for producing relative motion between the polishing pad and the conditioner disk to condition the polishing pad; an in-situ acoustic monitoring system having an acoustic sensor to receive an acoustic signal from the regulator disk; as well as A controller is configured to analyze an output signal from the acoustic sensor and determine a characteristic of the regulator disk or the regulator head based on the output signal.

2. The apparatus of claim 1, wherein the acoustic sensor is housed within the workbench.

3. The apparatus of claim 2, wherein the acoustic sensor contacts a bottom surface of the polishing pad.

4. The apparatus of claim 2, wherein the controller is configured to identify a portion of the signal corresponding to the acoustic sensor being positioned below the adjuster disk.

5. The apparatus of claim 4, wherein the controller is configured to determine the characteristic of the regulator disk or the regulator head using only the portion of the signal corresponding to the acoustic sensor being positioned below the regulator disk.

6. The device of claim 1, wherein the acoustic sensor is attached to the regulator head.

7. The apparatus of claim 1, wherein the controller is configured to detect an acoustic event caused by rubbing of the conditioner disk against the polishing surface.

8. The apparatus of claim 1, wherein the controller is configured to at least one of generate a warning, stop polishing, or change a conditioning parameter based on the determined characteristic of the conditioner disk or the conditioner head.

9. The apparatus of claim 8, wherein the controller is configured to detect that the adjuster disk is sufficiently worn to require replacement.

10. The apparatus of claim 8, wherein the controller is configured to detect that the adjuster disk is improperly installed in the adjuster head.

11. The apparatus of claim 8, wherein the controller is configured to detect that a pressure of the conditioner disk on the polishing pad does not match a desired pressure.

12. The apparatus of claim 1, wherein the controller is configured to generate a measured frequency spectrum of the output signal.

13. The apparatus of claim 12, wherein the controller is configured to compare the measured spectrum with a reference spectrum.

14. The apparatus of claim 12, wherein the controller is configured to detect signal strength in a band in the measured spectrum and compare the signal strength to a threshold.

15. A method for monitoring a regulator disk, comprising the steps of: receiving an acoustic signal from the conditioning disk at an acoustic sensor while the conditioning disk is conditioning the polishing pad, and generating an output signal from the acoustic sensor; and The output signal is analyzed and a property of the regulator disk or the regulator head is determined based on the output signal.

16. The method of claim 15, comprising the steps of sweeping the acoustic sensor beneath the adjustment disk and determining the portion of the output signal corresponding to the acoustic sensor beneath the adjustment disk.

17. A method as claimed in claim 16, comprising the step of determining the characteristic of the regulator disc or the regulator head using only the portion of the output signal corresponding to the acoustic sensor.

18. The method of claim 15, comprising the step of detecting that the adjuster disk is sufficiently worn to require replacement.

19. The method of claim 15, comprising the step of detecting that the regulator disk is improperly installed in the regulator head.

20. The method of claim 15, comprising the step of detecting that a pressure of the conditioner disk on the polishing pad does not match a desired pressure.

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