JP5194516B2 - Management method for chemical mechanical polishing equipment - Google Patents

Description

  The present invention relates to a management method for a chemical mechanical polishing apparatus, and more particularly to a management method for a chemical mechanical polishing apparatus characterized by a configuration for accurately determining a hardware failure of a conditioner constituting the chemical mechanical polishing apparatus. Is.

  In recent years, with the progress of higher integration of semiconductor integrated circuit devices, the pattern size has been miniaturized. In order to pattern a fine pattern with high accuracy, a semiconductor wafer (semiconductor substrate) or The flatness of the surface of the insulating layer and conductor layer formed on the semiconductor wafer becomes a problem.

  That is, if the surface is non-flat, a film thickness distribution is generated on the resist applied thereon, which causes a problem of local excess or deficiency in exposure amount during exposure, and local unevenness of the pattern during development. The problem arises.

  In order to cope with such a problem, the surface of the semiconductor wafer or the insulating layer and the conductor layer formed on the semiconductor wafer is flattened for each process by using a CMP (Chemical Mechanical Polishing) method.

  For example, in the wiring formation process, copper (Cu) having higher electromigration resistance than aluminum (Al) has been used in place of conventional aluminum (Al) wiring. Since there is no etching gas that can be selectively etched without adversely affecting the dry etching process, the Cu wiring is formed as a buried wiring layer using a CMP method.

Thus, the CMP method is used for various processes or purposes.
Here, the configuration of the CMP apparatus will be described with reference to FIG.
FIG. 5 is a schematic configuration diagram of an essential part of an example of a conventional CMP apparatus. A polishing table 21, a platen 22 attached to the polishing table, a polishing pad 23 placed on the platen 22, a conditioner head 26, and The conditioner 24 includes a rotating arm 25 and the polishing head 10.
In the CMP apparatus, a plurality of platens 22 are often arranged on one polishing table.

  The polishing head 10 includes a head casing 11, a retainer ring 12 that is circumscribed by the head casing 11 and holds the semiconductor wafer 30 on the inner periphery thereof. Thus, a membrane for sucking the semiconductor wafer 30 to the polishing head 10 or pressing it toward the polishing pad 23 is incorporated.

  In such a CMP process, the polishing pad is clogged with polishing residues and the like, leading to a decrease in polishing speed or a decrease in polishing accuracy. Therefore, it is necessary to perform conditioning periodically using a conditioner.

The conditioning is also referred to as a dress, and the polishing pad 23 is sharpened by a conditioner head 26 having a diamond disk. However, if the conditioner is in a poor condition, the polishing pad 23 is not sufficiently sharpened.
As a result, it appears as a decrease in the polishing rate in the object to be ground such as the semiconductor wafer 30 or a conductive layer disposed on the surface thereof.

  Therefore, if the grinding result is poor according to the measurement result of the semiconductor wafer 30 after polishing, the pad profile of the polishing pad 23 is measured using a micrometer or the like, and the conditioning by the conditioner 24 is performed based on the result. The process is corrected (for example, see Patent Document 1).

The conditioning process is corrected in accordance with the recipe. For example, the conditioning process is corrected over various items listed in the recipe such as dress pressure and dress rotation speed.
JP 2001-129754 A

  However, in such a conventional technique, since the conditioning process of the pad profile is corrected based on the measurement result of the semiconductor wafer after polishing, there is a problem that even if the conditioner itself is defective, it cannot be detected.

  That is, when the conditioner has a defect, the pad profile becomes unstable even if the conditioning process is corrected many times, and the conditioning process must be corrected repeatedly.

  It is an object of the present invention to accurately determine a hardware malfunction of a conditioner and efficiently remove the hardware malfunction of the conditioner.

Now, with reference to FIG. 1, means for solving the problems in the present invention will be described.
Refer to FIG. 1. In order to solve the above-mentioned problem, the present invention measures the pad profile of a plurality of polishing pads after polishing treatment used in the same platen in the management method of a chemical mechanical polishing apparatus, and measures the measured pads. If the standard deviation obtained by statistical processing of the measured values of the profile is less than or equal to a predetermined value, the mechanical condition of the conditioner is determined to be good and the polishing process is continued. When the standard deviation obtained by the statistical processing of the measured value is larger than a predetermined numerical value, it is determined as defective and the mechanical failure of the conditioner is repaired.

  In this way, by examining the pad profile of multiple polishing pads after polishing treatment used on the same platen, the hardware failure of the conditioner attached to each platen that cannot be compensated by the conditioning process correction from the quality of the pad profile Can be grasped.

  In this case, if the mechanical state of the conditioner is determined to be defective, the chemical mechanical polishing apparatus is temporarily used for polishing before repairing the mechanical failure of the conditioner. Measure the pad profile of multiple polishing pads used on the same platen after the polishing process, and if the pad profile meets a predetermined standard, determine that the conditioner's mechanical state is good When the polishing process is continued and it is determined as defective, it is desirable to repair the mechanical failure of the conditioner, thereby reducing the number of repairs of the mechanical failure of the conditioner.

In this case, the condition of the conditioner mechanical state is determined to be defective when the standard deviation obtained by statistical processing of the measured values of the measured pad profile is larger than a predetermined numerical value.

In this case, the number of polishing pads used for statistical processing is preferably 5-15, and if it is less than 5, the number of data for statistical processing is too small, making it difficult to determine whether the accuracy is high or low. If the number of sheets exceeds 15, the time required for the polishing operation becomes too long until the data is acquired, and it becomes impossible to quickly cope with the hardware failure of the conditioner.
In the case of a 300 mm polishing pad, since the pad area is large and the pad conditioning becomes unstable, the more effective the device is for a large-diameter semiconductor wafer.

  According to the present invention, it becomes possible to determine the hardware malfunction of the conditioner of each platen that cannot be compensated by the modification of the conditioning process, and by repairing the hardware malfunction of the conditioner based on the determination result, in the CMP polishing process Generation of defective products can be suppressed.

Here, referring to FIG. 1 again, an embodiment of the present invention will be described.
See Figure 1
FIG. 1 is a flowchart showing an embodiment of the present invention.
That is,
a. Predetermined polishing is performed using a CMP apparatus. Then
b. The pad profiles of a plurality of polishing pads after the polishing treatment used on the same platen are measured using, for example, a micrometer. Then
c. The quality of the pad profile is determined based on the measurement result. At this time, whether the pad profile is good or bad is
c ₁ . This is done by comparing the measured values of the measured pad profile.
In this case, the comparison of the measured values may be based on empirical judgment, or the numerical values may be determined mechanically by weighting the measured values at a plurality of predetermined specific locations on the polishing pad. May be. Or
c ₂ . Measure 5 to 15 pad profiles of the same platen and use a statistical method to determine whether the conditioner is good or bad.
As a statistical method, the standard deviation (STD) is obtained by the overall values of the thicknesses of 5 to 15 pad profiles, and the standard deviation is determined to be defective when the standard deviation exceeds a predetermined reference value.
d. If the determination result is good (OK), the polishing apparatus is continuously used, and the quality of the pad profile is determined again after a predetermined number of times of polishing. on the other hand,
e. If the determination result is bad (NG), the polishing apparatus is continuously used tentatively, and after the predetermined number of times of polishing is completed, again,
f. Measure the pad profile of 5-15 polishing pads,
g. The quality of the pad profile is determined based on the measurement result.
h. If the determination result is good (OK), the conditioner of the polishing apparatus is used without any problem, and after completion of a predetermined number of times of polishing, it is determined again whether or not the pad profile is acceptable. on the other hand,
i. If the determination result is bad (NG), it is determined that the conditioner of the polishing apparatus has a hardware failure, and the hardware failure such as the pressure state of the diaphragm is repaired.
j. After repairing the hardware failure of the conditioner, the polishing process is resumed as a normal polishing machine.

Next, with reference to FIG. 2, a management method for the CMP apparatus according to the first embodiment of the present invention will be described.
Here, a polishing apparatus having one head on the platen is used as the polishing apparatus A, a polyurethane independent foam type single layer pad is used as the polishing pad, and the slurry is an ILD in which a fumed silica-based slurry is diluted 1: 1. The result in the case of -CMP, that is, the oxide-based polishing of the interlayer insulating film is shown.

As polishing conditions,
Platen rotation speed: 80 to 100 rpm (rotation / min)
Polishing head rotation speed: 70-100 rpm
Condition pressure: 3.0 to 7.0 bf (pound weight)
Condition rotation speed: 80-100rpm
Went as.
FIG. 2 shows the measurement results of the pad profile in Example 1 of the present invention.
FIG. 2 shows a pad profile obtained by measuring the thickness of the polishing pad in the pad diameter direction.

Here, the pad profiles of the six polishing pads used in the _first platen P ₁ are shown.
In the first embodiment of the present invention, the shape of all the pad profiles is almost constant, which shows a good case.

  In addition, although the pass / fail determination of these pad profiles is empirical, a plurality of determination points in the polishing pad are determined in advance, and the measured values in the plurality of locations are within a predetermined reference value range. In the case of failure, the above-described conditioner hardware failure is repaired.

Next, a management method for the CMP apparatus according to the second embodiment of the present invention will be described with reference to FIG.
FIG. 3 is an explanatory diagram of the measurement result of the pad profile in the second embodiment of the present invention.
Here, a polishing apparatus having one head on the platen is used as the polishing apparatus B, a polyurethane independent foam type laminated pad is used as the polishing pad, and the slurry is ILD- in which a fumed silica-based slurry is diluted 1: 1. The case of CMP is shown.

As polishing conditions,
Platen rotation speed: 80-100rpm
Polishing head rotation speed: 70-100 rpm
Condition pressure: 3.0-7.0bf
Condition rotation speed: 80-100rpm
Went as.
FIG. 3 shows the measurement results of the pad profile in Example 2 of the present invention.
FIG. 3 shows a pad profile obtained by measuring the thickness of the polishing pad in the pad diameter direction.

Here, a pad profile of seven polishing pads used in the _third platen P3 is shown.
In this case, there are variations in the shape of the pad profile, and the shape of the pad profile of the two polishing pads is “saddle-shaped”.

On the other hand, since the shape of the pad profile of the other five polishing pads is “mountain shape”, it is determined that it is empirically bad.
In such a case, repair of the hardware failure of the conditioner is performed.

  Even in Example 2, the quality determination of the pad profile is empirical, but a plurality of determination points on the polishing pad are determined in advance, and the measurement values at the plurality of points are within a predetermined reference value range. It may be determined whether or not.

Next, a management method for the CMP apparatus according to the third embodiment of the present invention will be described with reference to FIG.
In the third embodiment, the quality of the measurement results in the first and second embodiments described above is statistically processed to determine pass / fail.
FIG. 4 is an explanatory diagram of statistical processing results of measured values in the first and second embodiments.
Here, standard deviation (STD) is used as a criterion.
The lower line shows the results for the three platens of the polishing apparatus A in Example 1, and the upper line shows the results for the three platens of the polishing apparatus B in Example 2.

  The standard deviation (STD) of the pad profile is calculated as follows: the thickness distribution of seven polishing pads used on the same platen, that is, the values of the pad profile are overall, that is, the standard deviation is measured at all measured points. The value obtained by multiplying 100 by 100 is shown.

In this case, since 15% is adopted as the determination reference value, it is indicated that the film thickness distribution of the polishing pad used in the platen P ₃ of the polishing apparatus B in Example 2 has a large variation.
That is, since the conditioner has a hardware defect, it means that conditioning is unstable and polishing cannot be performed in a stable state.
Therefore, if the STD exceeds 15% even if the polishing apparatus is temporarily used and the standard deviation (STD) of the pad profile is checked again, the conditioner is repaired.

  As described above, in the third embodiment of the present invention, the hardware failure of the conditioner is determined by a statistical method without relying on experience, so the hardware failure of the conditioner is objectively and accurately determined. Is possible.

  In particular, when the polishing pad has a large diameter of 300 mm or the like, since the pad area is large, the pad conditioning is likely to be unstable, and becomes more effective as the apparatus is adapted to a large diameter semiconductor wafer.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the configurations and conditions described in the embodiments, and various modifications are possible. In Example 2, the result of a CMP apparatus of a specific manufacturer is shown. However, the result is not limited to the above-described CMP apparatus of a specific manufacturer, and can be applied as a management method of CMP apparatuses of each company. .

  In the third embodiment, the criterion is 15% of the STD. However, such a numerical value is not absolute, and the degree of integration of the semiconductor integrated circuit device increases, that is, the pattern becomes finer. Since the flatness of the surface becomes more important as the process progresses, it is necessary to lower the reference value and make a stricter judgment of acceptability.

  As a practical example of the present invention, a management method for a CMP apparatus used for polishing a semiconductor wafer is typical, but the present invention is not limited to a CMP apparatus used for polishing a semiconductor wafer, and any CMP apparatus may be used. It is applied regardless of the polishing object.

It is a flowchart of an embodiment of the invention. It is explanatory drawing of the measurement result of the pad profile in Example 1 of this invention. It is explanatory drawing of the measurement result of the pad profile in Example 2 of this invention. It is explanatory drawing of the statistical processing result of the measured value in Example 1 and Example 2. FIG. It is a schematic principal part block diagram of an example of the conventional CMP apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Polishing head 11 Head housing | casing 12 Retainer ring 21 Polishing stand 22 Platen 23 Polishing pad 24 Conditioner 25 Rotating arm 26 Conditioner head 30 Semiconductor wafer

Claims (3)

When the pad profile of a plurality of polishing pads after polishing treatment used on the same platen is measured, and the standard deviation obtained by statistical processing of the measured values of the pad profile is less than or equal to a predetermined value The condition of the conditioner is determined to be good and the polishing process is continued. If the standard deviation obtained by statistical processing of the measured values of the pad profile is greater than a predetermined value, it is determined to be defective. Administration methods of chemical mechanical polishing apparatus characterized by repairing mechanical failure of the conditioner Te. When the pad profile of a plurality of polishing pads after polishing treatment used on the same platen is measured, and the standard deviation obtained by statistical processing of the measured values of the pad profile is less than or equal to a predetermined value The condition of the conditioner is determined to be good and the polishing process is continued. If the standard deviation obtained by statistical processing of the measured values of the pad profile is greater than a predetermined value, it is determined to be defective. Te, before repairing mechanical failure of the conditioner, the chemical mechanical polishing apparatus to continue the polished interim use of a plurality of polishing pad used in the same platen after該暫constant used polishing pad the profile is measured, wherein when the standard deviation obtained by statistical processing of the measurement values of the pad profile predetermined numerical smaller or equal the Determine the mechanical condition of the conditioner and good polishing process to continue, the standard deviation obtained by statistical processing of the measurement values of the pad profile is determined to be defective if greater than the value predetermined conditionality A management method for a chemical mechanical polishing apparatus, characterized by repairing a mechanical defect of na. The management method for a chemical mechanical polishing apparatus according to claim 1 or 2, wherein the number of polishing pads used for the one-time statistical processing is 5 to 15.

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