JP2005057100A - Polishing method and device of semiconductor substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a yield and work efficiency, by accurately judging that the time requiring the washing of an EPD window of the polishing cloth of a CMP device has come and abnormality is generated at the EPD window and automatically cleaning the EPD window. <P>SOLUTION: By rotating a turntable 2 and pressing a wafer 1 to the polishing cloth 3 while rotating it, the surface of the wafer 1 is polished and a polishing end point is judged by an optical type EPD detection unit 5. A change of the state of the stains of the EPD window 6 is detected on the basis of the value of reflected light intensity from the wafer 1 detected in the optical type EPD detection unit 5, it is judged that the time requiring the washing of the EPD window 6 has come or the abnormality is generated at the EPD window part 6, a device is stopped, and the EPD window 6 is automatically washed by an EPD window washing mechanism 9. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a polishing method and a polishing apparatus used in a planarization process such as chemical mechanical polishing (CMP) performed when a silicon semiconductor substrate is manufactured, for example.

  A CMP apparatus (Chemical Mechanical Polishing Machine) is used when processing a flat surface of a flat workpiece such as a silicon semiconductor substrate.

  FIG. 8 shows a schematic configuration of a general CMP apparatus. The CMP apparatus includes a turntable 2, a polishing head 4, an optical EPD (End Point Detector) unit 5, and the like. The polishing head 4 that holds the wafer 1 as a workpiece on the lower surface is disposed opposite to the turntable 2 and above it. A polishing cloth 3 is affixed to the upper surface of the turntable 2. The polishing cloth 3 is provided with an EPD window 6 for transmitting light for EPD detection. The turntable 2 is provided with a through hole 8 for allowing light to pass through the EPD window portion 6 of the polishing pad 3.

  In the CMP apparatus as described above, while the turntable 2 is rotated, an abrasive (slurry) is supplied from the abrasive supply nozzle 7 onto the polishing cloth 3 and the polishing head 4 is used to remove the wafer 1. By pressing against the polishing pad 3 while rotating, the surface of the wafer 1 is polished. The polishing end point is determined by the optical EPD unit 5.

  FIG. 9 is a detailed diagram showing how the end point of polishing by the optical EPD unit 5 is determined. A change in reflectance of light from the surface of the wafer 1 is used for determining the end point of polishing. For example, when the wafer 1 of the same film type is polished, the reflectivity changes depending on the film thickness, so that the end point is determined when the reflectivity at a predetermined film thickness is obtained by polishing. Further, when switching between layers in the case of polishing two or more kinds of laminated films is detected, the end point of polishing is determined from the change in reflectance of each film type.

  However, with repeated polishing of the wafer, slurry abrasive grains and polishing products gradually adhere to the surface of the EPD window portion 6 of the polishing cloth. For this reason, when the wafer incident light and the wafer reflected light pass through the EPD window 6, they are absorbed by the deposits on the surface of the EPD window 6. For this reason, the amount of reflected wafer light incident on the optical detector of the optical EPD unit 5 decreases and a predetermined amount of reflected light cannot be obtained, so that polishing progresses without reaching the set end point detection trigger, resulting in over-polishing and defective products. There is a problem that the yield of the wafer is reduced.

  Conventionally, generally, the operator determines whether or not it is time to perform cleaning for removing slurry abrasive grains and polishing products attached to the surface of the EPD window 6 of the polishing cloth 3 based on experience. Therefore, it was performed based on the usage time and the cumulative number of processed wafers. For this reason, the judgment that the cleaning of the EPD window section 6 has reached the necessity tends to be performed relatively early. As a result, the frequency of cleaning the EPD window section 6 of the polishing cloth increases, and the cost of maintenance work increases. There was a problem that it took more than necessary.

  Further, in the empirical management method as described above, sudden dirt on the polishing cloth EPD window section 6, peeling or scratching of the polyethylene terephthalate sheet (PET sheet), which is the material of the polishing cloth EPD window section 6, and the like. An EPD detection abnormality caused by an abnormality in the EPD window 6 itself could not be detected. As a result, EPD cannot be detected at the time of wafer polishing, resulting in overpolishing, resulting in continuous generation of defective products and a decrease in wafer yield.

In order to solve such a problem, the following polishing apparatus is described in Patent Document 1, and the influence of the slurry when optically monitoring the polishing state is considered. When the measurement light and the signal light pass through the slurry between the wafer and the detection window, the measurement light and the signal light are reflected by the boundary surface between the detection window and the slurry, or the abrasive grains are scattered or absorbed. As a result, the amount of signal incident on the photodetector decreases, the S / N ratio of the measurement decreases, and the measurement accuracy of the end point detection deteriorates. For this reason, this polishing apparatus is provided with a polishing liquid removal unit in the vicinity of the detection window for removing slurry that deteriorates the measurement accuracy of end point detection. By providing this polishing liquid removal unit, it is said that the measurement accuracy of the polishing end point detection can be improved and the yield of the wafer can be increased.
JP 2000-254860 A JP-A-6-81175

  However, in the above method, since it is necessary to flow water to the polishing liquid removal part in order to exclude the slurry in the vicinity of the detection window, the slurry is diluted with water during polishing, and the polishing rate of the wafer is changed. There was a problem and there was a limit to the use during actual wafer polishing.

  The present invention has been made in view of the problems associated with the conventional EPD detection as described above. The object of the present invention is that the time when the polishing cloth EPD window portion needs to be cleaned has been reached, and the polishing cloth EPD window. It is an object of the present invention to provide a semiconductor substrate polishing method and polishing apparatus capable of accurately determining that an abnormality has occurred in a portion.

  The method for polishing a semiconductor substrate of the present invention is a method for polishing a semiconductor substrate using an optical polishing end point detecting means, and polishing the semiconductor substrate by pressing the semiconductor substrate against a polishing cloth having an end point detection window of the polishing end point detecting means. A polishing step to be performed, and a detection step of detecting an abnormal state due to dirt adhering to the end point detection window.

  In the present invention, it is preferable that the detecting step detects an abnormal state due to contamination based on the intensity of reflected light from the semiconductor substrate detected by the polishing end point detecting means. In this case, the polishing end point detection means emits light toward the semiconductor substrate through the end point detection window, receives the reflected light reflected by the semiconductor substrate and returned through the end point detection window, and the reflected light intensity Can be measured.

  In the present invention, the detection step transmits an ultrasonic wave toward the semiconductor substrate through the end point detection window, receives the reflected wave reflected by the semiconductor substrate and returned through the end point detection window, It is preferable to detect an abnormal state due to dirt based on the reflected wave intensity.

  Moreover, in this invention, it is preferable to stop a grinding | polishing process in response to detection of the abnormal state by a detection process during the sequence of a grinding | polishing process.

  In the present invention, the polishing process is stopped during the polishing process sequence in response to detection of an abnormal state by the detection process, and thereafter, the cleaning means removes the dirt adhering to the end point detection window by the cleaning means. May be.

  Further, in the present invention, there may be provided a cleaning step in which the dirt adhering to the end point detection window is removed by the cleaning means in response to detection of an abnormal state by the detection step during the polishing step sequence.

  The first semiconductor substrate polishing apparatus of the present invention has an optical polishing end point detecting means and polishes the semiconductor substrate by pressing the semiconductor substrate against a polishing cloth having an end point detecting window of the polishing end point detecting means. In the apparatus, the polishing end point detection means also detects an abnormal state due to dirt adhering to the end point detection window based on the reflected light intensity from the semiconductor substrate detected by the polishing end point detection means. In this case, for example, the polishing cloth is affixed to the surface plate, a through hole is provided in the surface plate corresponding to the end point detection window of the polishing cloth, and the polishing end point detecting means is connected to the semiconductor substrate via the end point detection window. The reflected light that is emitted toward, reflected by the semiconductor substrate and returned through the end point detection window can be received, and the intensity of the reflected light can be measured.

  The second semiconductor substrate polishing apparatus of the present invention has an optical polishing end point detection means and polishes the semiconductor substrate by pressing the semiconductor substrate against a polishing cloth having an end point detection window of the polishing end point detection means. The apparatus transmits ultrasonic waves toward the semiconductor substrate through the end point detection window, receives the reflected waves reflected by the semiconductor substrate and returned through the end point detection window, and the reflected wave intensity. And an ultrasonic detection means for detecting an abnormal state due to dirt adhering to the end point detection window. In this case, for example, the polishing cloth is attached to the surface plate, and a through hole is provided in the surface plate corresponding to the end point detection window of the polishing cloth.

  In the first and second semiconductor substrate polishing apparatuses of the present invention, it is preferable to provide a cleaning means for cleaning the end point detection window. This cleaning means includes a spray nozzle type megasonic cleaning mechanism having a cleaning nozzle and an ultrasonic oscillation means for applying ultrasonic waves to the cleaning nozzle, and a high-pressure pump for applying high-pressure spray to the cleaning nozzle and the cleaning nozzle. Or a spin brush cleaning mechanism having a cleaning nozzle and a spin brush means at the tip of the cleaning nozzle.

  According to the semiconductor substrate polishing method and polishing apparatus of the present invention, based on the reflected light intensity or reflected wave intensity of the workpiece from the semiconductor substrate, the dirt state of the end point detection window is monitored and the abnormal state is detected. Thus, it is possible to accurately determine that the time required to clean the end point detection window has been reached or that an abnormality has occurred. As a result, the number of times of excessive cleaning can be reduced and the maintenance cost can be reduced. In addition to this, when any abnormality as described above occurs in the end point detection window, it can be detected and the operation of the polishing apparatus can be stopped. For this reason, since the polishing in the abnormal state of the end point detection window is not continued, the yield of the wafer (semiconductor substrate) can be increased.

  In addition, since the abrasive grains and polishing products adhering to the end point detection window can be removed and kept in a constant state by the cleaning means, the EPD trigger detection error is eliminated by obtaining a stable EPD signal, and the wafer is poorly polished. Can be prevented and yield can be increased. In addition, since the end point detection window is automatically cleaned in-line, CoO (cost of ownership) can be reduced by omitting maintenance work. Further, by removing the aggregated particles of the slurry abrasive grains generated in the end point detection window, generation of surface defects (scratches) of the workpiece can be prevented, and the yield of non-defective products is improved.

(First embodiment)
FIG. 1 shows a schematic configuration of a CMP apparatus that automatically detects the cleaning timing of the polishing cloth EPD window by an optical method according to the present invention.

  In the figure, 1 is a wafer (workpiece), 2 is a turntable, 3 is a polishing cloth, 4 is a polishing head, 5 is an optical EPD detection unit, 6 is an EPD window, 7 is an abrasive supply nozzle, and 8 is an abrasive supply nozzle. A through hole, 9 is an EPD window cleaning mechanism, 10 is a data processing unit, 11 is a control unit, and 12 is an operation terminal.

  The polishing head 4 and the EPD window cleaning mechanism 9 are disposed above and facing the turntable 2. A polishing cloth 3 is attached to the upper surface of the turntable 2, and a wafer 1 as a workpiece is held on the lower surface of the polishing head 4. An optical detection system is installed below the turntable 2. This optical detection system includes an optical EPD detection unit 5, a data processing unit 10, a control unit 11, and the like.

  In the above CMP apparatus, the turntable 2 is rotated, the slurry is supplied onto the polishing cloth 3 from the abrasive (slurry) supply nozzle 7, and then the polishing cloth 3 is rotated while rotating the wafer 1 using the polishing head 4. , The surface of the wafer 1 is polished, and the polishing end point is determined by the optical EPD detection unit 5 as in the conventional case of FIG.

  The principle of the present invention will be described. The dirt state of the EPD window portion 6 changes due to the influence of the polishing time of the wafer 1 and the increase in the number of polished wafers. Further, the intensity of the reflected light from the wafer 1 that has been emitted from the optical EPD detection unit 5 and reflected by the wafer 1 through the through hole 8 and the EPD window 6 varies according to the state of contamination of the EPD window 6. To do. Accordingly, it is possible to detect a change in the dirt state of the EPD window portion 6 based on the value of the reflected light intensity from the wafer 1. As described above, the cleaning timing (or abnormality) of the EPD window section 6 can be accurately detected by monitoring the dirt state of the EPD window section 6 based on the intensity of reflected light from the wafer 1. .

  Therefore, in the present embodiment, the value of the reflected light intensity from the wafer 1 (detectable as a voltage value) is measured, and the measured reflected light intensity is reduced compared to a preset reference value, and the difference is When it exceeds the preset allowable value, it is determined that the time required to clean the polishing pad EPD window 6 has been reached or an abnormality has occurred in the polishing pad EPD window 6, and the apparatus is stopped. Then, the EPD window section cleaning mechanism 9 also causes the EPD window section 6 to be automatically cleaned. Here, the value of the reflected light intensity from the wafer 1 is measured for each wavelength by a spectrometer (included in the optical EPD detection unit 5) that performs spectrum detection for optical EPD detection of the workpiece. Can do. Here, a specific wavelength is selected from each wavelength, the reflected light intensity at the specific wavelength is obtained, and sent to the data processing unit 10.

  In the above CMP apparatus, the value of the reflected light intensity from the wafer 1 is measured by the optical EPD detection unit 5 and sent to the data processing unit 10. The data processing unit 10 compares the transmitted reflected light intensity with a reference value set in advance, and determines whether the EPD window unit 6 is abnormal. When it is determined that some abnormality has occurred, an abnormality detection signal is sent to the control unit 11. Upon receiving the abnormality detection signal, the control unit 11 stops the operation of the polishing apparatus according to a predetermined sequence. At the same time, a signal is sent to the operation terminal 12 to display a predetermined warning screen on the display device. Further, a signal for cleaning the EPD window section 6 can be sent to the EPD window section cleaning mechanism 9 to be executed.

  Next, the configuration of the monitoring system in the flat polishing apparatus that automatically detects the cleaning timing of the polishing cloth EPD window by the optical method according to the present invention will be described. FIG. 2 shows a control block diagram of the monitoring system.

  (A) First, the operator inputs processing conditions (processing pressure, number of rotations, number of processing, etc.) to the operation terminal 12 and is used for determination to perform EPD window cleaning in the data processing unit 10. An instruction about data (reference value, allowable value, etc. described later) is input.

  (B) The control unit 11 issues a command to the polishing apparatus to start automatic continuous processing of the wafer.

  (C) The optical EPD detection unit 5 measures the reflected light from the wafer during the processing of each wafer, converts the reflected light into the reflected light intensity by a spectrometer, and sends it to the data processing unit 10. Note that the sampling period of the reflected light is, for example, about 0.5 sec.

  (D) The data processing unit 10 compares the calculated reflected light intensity with the reference value previously set in (a), the reflected light intensity is lower than the reference value, and the difference is preset. When the allowable value exceeds the allowable value, it is determined that an abnormality has occurred in the EPD window 6 (including that the EPD window 6 needs to be cleaned). In other cases, it is determined that there is no abnormality. As a result, when it is determined that an abnormality has occurred in the EPD window section 6, an abnormality detection signal is sent to the control section 11.

  (E) When the control unit 11 receives the abnormality detection signal, the control unit 11 sends a command to stop the operation of the polishing apparatus according to a predetermined sequence to each of the related driving devices. At the same time, a signal is sent to the operation terminal 12 to display a warning “cleaning cloth EPD window cleaning required or abnormal EPD window” on the display device. In addition, a signal for cleaning the polishing cloth EPD window 6 can be sent to the EPD window cleaning mechanism 9 of the polishing apparatus to be operated.

  As a method for setting the reference value of the reflected light intensity in the above monitoring system, for example, the following method can be employed. The reflected light intensity collected in advance for each type of slurry, wafer type, and film thickness is stored in the data processing unit 10 as a database, and when polishing an actual wafer, The reflected light intensity is read from the combination of type and film thickness, and the value is set as a reference value.

(Second Embodiment)
FIG. 3 shows a schematic configuration of a CMP apparatus that performs automatic detection of the cleaning timing of the polishing cloth EPD window by the ultrasonic method according to the present invention.

  In the figure, 1 is a wafer (workpiece), 2 is a turntable, 3 is a polishing cloth, 4 is a polishing head, 5 is an optical EPD detection unit, 6 is an EPD window, 7 is an abrasive supply nozzle, and 8 is an abrasive supply nozzle. A through hole, 9 is an EPD window cleaning mechanism, 10 is a data processing unit, 11 is a control unit, 12 is an operation terminal, and 20 is an ultrasonic measuring instrument.

  The polishing head 4 and the EPD window cleaning mechanism 9 are disposed above and facing the turntable 2. A polishing cloth 3 is attached to the upper surface of the turntable 2, and a wafer 1 as a workpiece is held on the lower surface of the polishing head 4. An optical EPD detection unit 5 and an ultrasonic unit are installed below the turntable 2. The ultrasonic unit includes an ultrasonic measuring device 20 having an ultrasonic wave transmission function and a wave reception function, a data processing unit 10, a control unit 11, and the like.

  In the above CMP apparatus, the turntable 2 is rotated, the slurry is supplied onto the polishing cloth 3 from the abrasive (slurry) supply nozzle 7, and then the polishing cloth 3 is rotated while rotating the wafer 1 using the polishing head 4. , The surface of the wafer 1 is polished, and the polishing end point is determined by the optical EPD detection unit 5 as in the conventional case of FIG.

  The principle of the present invention will be described. The dirt state of the EPD window portion 6 changes due to the influence of the polishing time of the wafer 1 and the increase in the number of polished wafers. Further, the reflected wave intensity from the wafer 1 where the ultrasonic wave emitted from the ultrasonic measuring instrument 20 is reflected by the wafer 1 through the through hole 8 and the EPD window 6 is the state of contamination of the EPD window 6. Fluctuates according to. Accordingly, it is possible to detect a change in the state of contamination of the EPD window 6 based on the value of the reflected wave intensity from the wafer 1. As described above, the cleaning timing (or abnormality) of the EPD window 6 can be accurately detected by monitoring the state of contamination of the EPD window 6 based on the reflected wave intensity from the wafer 1. .

  Therefore, in this embodiment, the value of the reflected wave intensity from the wafer 1 (which can be detected as a voltage value) is measured, and the measured reflected wave intensity is lower than a preset reference value, and the difference is When it exceeds the preset allowable value, it is determined that the time required to clean the polishing pad EPD window 6 has been reached or an abnormality has occurred in the polishing pad EPD window 6, and the apparatus is stopped. Then, the EPD window section cleaning mechanism 9 also causes the EPD window section 6 to be automatically cleaned.

  In the above CMP apparatus, the value of the reflected wave intensity of the wafer 1 is measured by the ultrasonic measuring device 20 and sent to the data processing unit 10. The data processing unit 10 compares the transmitted reflected wave intensity with a preset reference value to determine whether the EPD window unit 6 is abnormal. When it is determined that some abnormality has occurred, an abnormality detection signal is sent to the control unit 11. Upon receiving the abnormality detection signal, the control unit 11 stops the operation of the polishing apparatus according to a predetermined sequence. At the same time, a signal is sent to the operation terminal 12 to display a predetermined warning screen on the display device. Further, a signal for cleaning the EPD window section 6 can be sent to the EPD window section cleaning mechanism 9 to be executed.

  Next, the configuration of the monitoring system in the planar polishing apparatus that automatically detects the cleaning timing of the polishing cloth EPD window by the ultrasonic method according to the present invention will be described. FIG. 4 shows a control block diagram of the monitoring system.

  (A) First, the operator inputs processing conditions (processing pressure, number of rotations, number of processing, etc.) to the operation terminal 12 and is used for determination to perform EPD window cleaning in the data processing unit 10. An instruction about data (reference value, allowable value, etc. described later) is input.

  (B) The control unit 11 issues a command to the polishing apparatus to start automatic continuous processing of the wafer.

  (C) The ultrasonic measuring device 20 measures the reflected wave intensity from the wafer during processing of each wafer, and sends it to the data processing unit 10. Note that the sampling period of the reflected wave is, for example, about 0.5 sec.

  (D) The data processing unit 10 compares the calculated reflected wave intensity with the reference value previously set in (a), the reflected wave intensity is lower than the reference value, and the difference is preset. When the allowable value exceeds the allowable value, it is determined that an abnormality has occurred in the EPD window 6 (including that the EPD window 6 needs to be cleaned). In other cases, it is determined that there is no abnormality. As a result, when it is determined that an abnormality has occurred in the EPD window section 6, an abnormality detection signal is sent to the control section 11.

  (E) When the control unit 11 receives the abnormality detection signal, the control unit 11 sends a command to stop the operation of the polishing apparatus according to a predetermined sequence to each of the related driving devices. At the same time, a signal is sent to the operation terminal 12 to display a warning “cleaning cloth EPD window cleaning required or abnormal EPD window” on the display device. In addition, a signal for cleaning the polishing cloth EPD window 6 can be sent to the EPD window cleaning mechanism 9 of the polishing apparatus to be operated.

  As a method for setting the reference value of the reflected wave intensity in the above monitoring system, for example, the following method can be adopted. The reflected wave intensity collected for each type of slurry, wafer type, and film thickness is stored in the data processing apparatus 10 as a database, and when polishing an actual wafer, The reflected wave intensity is read from the combination of type and film thickness, and the value is set as a reference value.

  As described above, according to the first embodiment, based on the reflected light intensity from the wafer by the optical EPD detection unit 5, and according to the second embodiment, from the wafer by the ultrasonic measuring device 20. By determining the state of contamination of the polishing pad EPD window 6 based on the reflected wave intensity, it becomes possible to accurately determine the cleaning timing of the polishing pad EPD window 6 or the occurrence of an abnormality. As a result, the number of times of excessive cleaning can be reduced and the maintenance cost can be reduced. In addition, if any abnormality occurs in the polishing pad EPD window section 6, it can be detected and the operation of the polishing apparatus can be stopped. For this reason, the polishing cloth EPD window portion 6 is not continuously polished in an abnormal state, so that the yield of the wafer can be increased.

  Further, by providing the EPD window cleaning mechanism 9, the slurry abrasive particles and polishing products attached to the polishing cloth EPD window 6 can be removed, and the polishing cloth EPD window 6 can always be kept in a constant state. By obtaining a stable EPD signal, it is possible to eliminate an EPD trigger detection error, prevent the occurrence of a poorly polished wafer, and increase the yield. In addition, since the polishing cloth EPD window 6 is automatically cleaned inline, CoO (cost of ownership) can be reduced by omitting maintenance work. Further, by removing the aggregated particles of the slurry abrasive grains generated in the EPD window portion 6, it is possible to prevent the occurrence of surface defects (scratches) on the workpiece and to improve the yield of good products.

  In the first and second embodiments, when the control unit 11 receives an abnormality detection signal from the data processing unit 10, the EPD window cleaning mechanism 9 is activated without stopping the polishing operation by the polishing apparatus. By operating, the EPD window portion 6 may be cleaned while polishing.

  Hereinafter, an example of the EPD window cleaning mechanism 9 used in the first and second embodiments will be described.

  FIG. 5 shows Example 1 of the polishing pad EPD window cleaning mechanism 9. In the figure, 13 is an ultrasonic transducer, 14 is an oscillator, and 15 is a DIW (cleaning liquid) line. As a timing for cleaning the polishing cloth EPD window portion 6, the method based on the automatic detection of the cleaning timing of the polishing cloth EPD window portion described in the first and second embodiments may be used. Or it can also carry out for every lot of workpieces, for example. Or it can also carry out for every work material, for example. The turntable 2 is rotated using a standby state in which the surface polishing apparatus is not processing the wafer. The rotation of the turntable 2 is stopped at the position where the polishing cloth EPD window portion 6 comes to the washable region of the EPD window portion cleaning mechanism 9. This turntable stop position is the EPD window cleaning position. By performing EPD window cleaning at the EPD window cleaning position, slurry abrasive grains and polishing products adhering to the EPD window are removed.

  In the example of FIG. 5, the polishing pad EPD window 6 is cleaned using a spray nozzle type megasonic cleaning method. However, as shown in the example of FIG. The polishing cloth EPD window portion 6 may be cleaned using a high-pressure spray cleaning method of spraying high-pressure water. In addition, as in the example of FIG. 7, the polishing pad EPD window 6 may be cleaned using a spin brush cleaning method including a brush 18 and a motor 19 that rotates the brush 18.

  In the spray nozzle type megasonic cleaning mechanism of FIG. 5, the high pressure spray cleaning mechanism of FIG. 6, and the spin brush cleaning mechanism of FIG. 7, the cost increases in the order of spin brush cleaning mechanism <high pressure spray cleaning mechanism <spray nozzle type megasonic cleaning mechanism. However, the cleaning ability is excellent in the order of cost. In addition, there is a higher possibility that the PET, which is the material of the polishing pad EPD window portion 6, will be damaged by cleaning in order of increasing cost.

  The method and apparatus for polishing a semiconductor substrate according to the present invention can accurately determine that the time required to clean the polishing cloth EPD window has been reached and that an abnormality has occurred in the polishing cloth EPD window, For example, it is useful in a planarization process such as chemical mechanical polishing (CMP) performed when manufacturing a silicon semiconductor substrate.

1 is a schematic configuration diagram of a CMP apparatus that performs automatic detection of cleaning timing of an optical polishing cloth EPD window portion according to the first embodiment of the present invention. Control block diagram of a monitoring system for automatically detecting the cleaning timing of the polishing cloth EPD window portion by the optical method in the first embodiment of the present invention 1 is a schematic configuration diagram of a CMP apparatus that performs automatic detection of cleaning timing of a polishing cloth EPD window portion by an ultrasonic method in the first embodiment of the present invention. Control block diagram of a monitoring system for automatically detecting the cleaning timing of the polishing cloth EPD window portion by the ultrasonic method in the first embodiment of the present invention The figure which shows the 1st example of polishing cloth EPD window part cleaning apparatus The figure which shows the 2nd example of polishing cloth EPD window part cleaning apparatus. The figure which shows the 3rd example of polishing cloth EPD window part cleaning apparatus. Schematic configuration diagram of a conventional CMP apparatus The figure which shows the grinding | polishing end point detection mechanism of CMP apparatus

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wafer 2 Turntable 3 Polishing cloth 4 Polishing head 5 Optical EPD detection unit 6 EPD window part 7 Abrasive supply nozzle 8 Through-hole 9 EPD window part cleaning mechanism 10 Data processing part 11 Control part 12 Operation terminal 13 Ultrasonic vibration Child 14 Oscillator 15 DIW (cleaning liquid) line 16 Nozzle 17 High-pressure pump 18 Brush 19 Motor 20 Ultrasonic measuring instrument

Claims (12)

A method for polishing a semiconductor substrate using an optical polishing end point detection means,
A polishing step of polishing by pressing a semiconductor substrate against a polishing cloth having an end point detection window of the polishing end point detection means;
And a detection step of detecting an abnormal state due to dirt adhering to the end point detection window.   2. The method of polishing a semiconductor substrate according to claim 1, wherein the detecting step detects an abnormal state due to the contamination based on a reflected light intensity from the semiconductor substrate detected by the polishing end point detecting means.   The detecting step transmits an ultrasonic wave toward the semiconductor substrate through the end point detection window, receives a reflected wave reflected by the semiconductor substrate and returned through the end point detection window, 2. The method of polishing a semiconductor substrate according to claim 1, wherein an abnormal state due to the dirt is detected based on the reflected wave intensity.   4. The method for polishing a semiconductor substrate according to claim 1, wherein the polishing step is stopped in response to detection of an abnormal state by the detection step during the sequence of the polishing step.   In the polishing process sequence, the polishing process is stopped in response to detection of an abnormal state by the detection process, and then a cleaning process is performed to remove dirt adhered to the end point detection window with a cleaning means. The method for polishing a semiconductor substrate according to claim 1, 2 or 3.   4. The method according to claim 1, further comprising a cleaning step of removing dirt attached to the end-point detection window by a cleaning unit in response to detection of an abnormal state by the detection step during the polishing step sequence. A method for polishing a semiconductor substrate as described. A polishing apparatus for a semiconductor substrate, comprising an optical polishing end point detection means, and polishing the semiconductor substrate by pressing the semiconductor substrate against a polishing cloth having an end point detection window of the polishing end point detection means,
The polishing end point detection means detects an abnormal state due to dirt adhering to the end point detection window based on the reflected light intensity from the semiconductor substrate detected by the polishing end point detection means. Semiconductor substrate polishing equipment. A polishing apparatus for a semiconductor substrate, comprising an optical polishing end point detection means, and polishing the semiconductor substrate by pressing the semiconductor substrate against a polishing cloth having an end point detection window of the polishing end point detection means,
An ultrasonic wave is transmitted toward the semiconductor substrate through the end point detection window, and a reflected wave reflected by the semiconductor substrate and returned through the end point detection window is received, and the reflected wave intensity is increased. An apparatus for polishing a semiconductor substrate, comprising: ultrasonic detection means for detecting an abnormal state due to dirt adhering to the end point detection window.   9. The semiconductor substrate polishing apparatus according to claim 7, further comprising cleaning means for cleaning the end point detection window.   The semiconductor substrate polishing apparatus according to claim 9, wherein the cleaning unit includes a cleaning nozzle and an ultrasonic oscillation unit for applying ultrasonic waves to the cleaning nozzle.   The semiconductor substrate polishing apparatus according to claim 9, wherein the cleaning unit includes a cleaning nozzle and a high-pressure pump unit that applies high-pressure spray to the cleaning nozzle.   The semiconductor substrate polishing apparatus according to claim 9, wherein the cleaning unit includes a cleaning nozzle and a spin brush unit at a tip of the cleaning nozzle.

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