JP6822518B2 - Polishing pad management method and polishing pad management system - Google Patents

Description

The present invention relates to a polishing pad management method and a polishing pad management system.

Generally, wafers are manufactured through a polishing process to improve flatness. In the polishing step, the surface of the wafer is polished by sliding the polishing pad attached to the rotary surface plate and the surface of the wafer by rotating the rotary surface plate while supplying the polishing slurry or the like.

However, when the polishing pad is clogged with foreign matter such as Si and the life is approaching the end of its life, a defect called LPD (Light Point Defects) may occur in the wafer polished by the polishing pad. In some cases, the cleanliness of the wafer was reduced.

On the other hand, as a method of evaluating the life of the polishing pad and managing the polishing pad before the occurrence of LPD or other quality abnormality on the wafer, for example, in Patent Document 1, the fluorescence obtained by the fluorescent X-ray analysis method is used. It has been proposed to evaluate the life of the polishing pad based on the signal of the X-ray spectrum.

Patent No. 5967044

However, the method described in Patent Document 1 uses a fluorescent X-ray analysis method, and since sufficient consideration must be given to safety in its use, a simpler method has been sought.

Therefore, an object of the present invention is to provide a polishing pad management method and a polishing pad management system capable of evaluating the life of the polishing pad and managing the polishing pad by a simple method.

The gist structure of the present invention is as follows.
(1) The method for managing the polishing pad of the present invention is as follows.
A measuring step in which the measuring unit measures at least one variable in the color space of the polishing pad.
It is characterized by including an evaluation step of evaluating the life of the polishing pad based on at least one variable in the color space measured by the determination unit.

(2) In the polishing pad management method of the present invention,
The color space is an L ^* a ^* b ^* color space.
In the measuring step, at least one of L ^* , a ^* , and b ^* of the polishing pad is measured.
In the evaluation step, it is preferable to evaluate the life of the polishing pad based on at least one of the measured L ^* , a ^* , and b ^* .

(3) In (2) above
In the measurement step, two or more of L ^* , a ^* , and b ^* of the polishing pad are measured.
In the evaluation step, it is preferable to evaluate the life of the polishing pad based on two or more of the measured L ^* , a ^* , and b ^* .

(4) In (3) above
In the measurement step, all of L ^* , a ^* , and b ^* of the polishing pad are measured.
In the evaluation step, it is preferable to evaluate the life of the polishing pad based on all of the measured L ^* , a ^* , and b ^* .

(5) In the polishing pad management method of the present invention,
In the evaluation step, it is preferable to evaluate the life of the polishing pad based on the data showing the relationship between any one or more of L ^* , a ^* , and b ^* and the life of the polishing pad.

(6) In the polishing pad management method of the present invention,
In the evaluation step, it is also preferable to evaluate the life of the polishing pad by using a prediction formula which is a relational expression between any one or more of L ^* , a ^* , and b ^* and the life of the polishing pad.

(7) In the polishing pad management method of the present invention,
The measuring step is preferably performed in a state where the polishing pad is dry.

(8) In the polishing pad management method of the present invention,
The measuring unit is preferably a spectrocolorimeter.

(9) The polishing pad management system of the present invention is
A measuring unit that measures at least one variable in the color space of the polishing pad,
It is characterized by including a determination unit that evaluates the life of the polishing pad based on at least one variable in the measured color space.

According to the present invention, it is possible to provide a polishing pad management method and a polishing pad management system capable of evaluating the life of the polishing pad and managing the polishing pad by a simple method.

It is a block diagram which shows the management system of the polishing pad which concerns on one Embodiment of this invention. It is a flow figure which shows the management method of the polishing pad which concerns on one Embodiment of this invention. It is a schematic diagram which shows the L ^* a ^* b ^* color space. It is a schematic diagram which shows the finish polishing apparatus. It is a figure which shows the relationship between the polishing pad life of a polishing pad, and the number of LPDs. It is a figure which shows the relationship between the polishing pad life of a polishing pad, and the clogging amount (weight%) of Si. It is a figure which shows the relationship between the polishing pad life of a polishing pad, and L ^* . It is a figure which shows the relationship between the polishing pad life of a polishing pad, and a ^* . It is a figure which shows the relationship between the polishing pad life of a polishing pad, and b ^* . It is a figure which shows the relationship between the clogging amount (weight%) of Si, and L ^* . It is a figure which shows the relationship between the clogging amount (weight%) of Si, and a ^* . It is a figure which shows the relationship between the clogging amount (weight%) of Si, and b ^* .

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<Abrasion pad management system>
FIG. 1 is a block diagram showing a polishing pad management system according to an embodiment of the present invention. As shown in FIG. 1, the management system 100 includes a measurement unit 1, a determination unit 2, and a communication unit 3.

The measuring unit 1 is configured to measure at least one variable in the color space of the polishing pad. In the present embodiment, the color space is an L ^* a ^* b ^* color space, and the measuring unit 1 has at least one (or two or more) of L ^* , a ^* , and b ^* of the polishing pad. Or all). As the measuring unit 1, for example, a spectrophotometer can be used. For example, the above measurement can be performed by pressing the spectrophotometer against the polishing pad with a predetermined load. For example, when measuring only L ^* in the L ^* a ^* b ^* color space, a measuring instrument capable of measuring only the brightness may be used.
Further, it is preferable that the measuring unit 1 is configured so that the measurement can be performed in a state where the polishing pad is dry. This is because the accuracy of measurement can be improved by preventing reflections and the like that may occur in a wet state. For this reason, the system 100 may include a dryer that dries the polishing pad.

The determination unit 2 is configured to evaluate the life of the polishing pad based on at least one variable in the measured color space. In the present embodiment, the color space is an L ^* a ^* b ^* color space, and at least one (or two or more, or all three) of L ^* , a ^* , and b ^* measured by the measuring unit 1 is used. ), It is configured to evaluate the life of the polishing pad. The determination unit 2 can be any known processor.

In this example, the determination unit 2 includes a storage unit, and the storage unit is polished with any one or more (or two or more, or all three) of L ^* , a ^* , and b ^*. Data showing the relationship with the life of the pad is stored. For the data, when any one or more (or two or more, or all three) of L ^* , a ^* , and b ^* are obtained, the corresponding polishing pad life value is obtained (linked). It can be mapping data like this. Further, as another example, the storage unit can store a prediction formula which is a relational expression between any one or more of L ^* , a ^* , and b ^* and the life of the polishing pad. In the prediction formula, when any one or more (or two or more, or all three) of L ^* , a ^* , and b ^* are obtained, the polishing pad is substituted by substituting it into the prediction formula. It can be a prediction formula that gives a life value. Examples of the prediction formula include, but are not limited to, the following (Equation 1), and may include, for example, quadratic or higher terms of L ^* , a ^* , and b ^* .
(Equation 1) Polishing pad life value = k1 x L ^* + k2 x a ^* + k3 x b ^*
(However, k1, k2, and k3 are coefficients given in advance)
When evaluating the life of the polishing pad, the determination unit 2 can make a determination using the above data and / or the prediction formula.

The communication unit 3 is configured to be able to transmit the evaluation result of the life of the polishing pad and / or the determination result for the management of the polishing pad based on the evaluation result determined by the determination unit 2 to the outside. .. Further, in this example, the communication unit 3 can receive information from the outside and transmit it to the storage unit of the determination unit 2 so that the above data and / or the prediction formula can be updated. Alternatively, the management system 100 may further include a display unit, and the evaluation result of the life of the polishing pad determined by the determination unit 2 and / or the determination result for the management of the polishing pad based on the evaluation result can be obtained. It can also be displayed on the display unit.
The polishing pad management system of the present invention can also be implemented as a part of the polishing apparatus.

<Evaluation method of polishing pad>
FIG. 2 is a flow chart showing a method of managing a polishing pad according to an embodiment of the present invention.
As shown in FIG. 2, in the present embodiment, first, at least one variable in the color space of the polishing pad is measured by the measuring unit 1 (in this example, the spectrocolorimeter) (step S101: measuring step). .. Further, in the measurement step, it is preferable to perform the measurement in a state where the polishing pad is dry. Therefore, it is preferable to perform a drying step of drying the polishing pad prior to the measuring step.

Here, FIG. 3 is a schematic diagram showing an L ^* a ^* b ^* color space (CIE 1976 L ^* a ^* b ^* color space). As described above, in the present embodiment, the color space is an L ^* a ^* b ^* color space. As shown in FIG. 3, the L ^* a ^* b ^* color space consists of three variables, L ^* , a ^* , and b ^* . In the L ^* a ^* b ^* color space, L ^* represents lightness, and a ^* and b ^* represent hue and saturation (as also shown in FIG. 3, the positive value of L ^* is large. becomes enough, closer to white, as the negative value of L ^* increases, approaches black, and, as the positive value of a ^* increases, approaching the red (magenta), the negative value of a ^* enough to increase, approaching the green, also, as the positive value of b ^* is larger, close to yellow, as the negative value of b ^* is large, approaching blue). In the present embodiment, in the measurement step (step S101), any one or more of the above three variables L ^* a ^* b ^{* in} the L ^* a ^* b ^* color space of the polishing pad is measured. In the present invention, in the measuring step, any two or more of the above three variables L ^* a ^* b ^{* in} the L ^* a ^* b ^* color space of the polishing pad can be measured, and all three can be measured. It can also be measured.

Then, as shown in FIG. 2, in this embodiment, the determination unit 2 (processor in this example) is based on at least one (or two or more, or all three) variables in the measured color space. The life of the polishing pad is evaluated (step S102: evaluation step).

In the present embodiment, in the evaluation step (step S102), data showing the relationship between any one or more (or two or more, or all three) of L ^* , a ^* , and b ^* and the life of the polishing pad. It is preferable to evaluate the life of the polishing pad based on. The data can be the data described in the embodiment of the polishing pad management system 100.

Further, in the evaluation step (step S102), the life of the polishing pad is evaluated by using a prediction formula which is a relational expression between any one or more of L ^* , a ^* , and b ^* and the life of the polishing pad. Is also preferable. The prediction formula can be the prediction formula described in the embodiment of the polishing pad management system 100.

As described above, the polishing pad management system 100 of the present embodiment is based on the measuring unit 1 that measures at least one variable in the color space of the polishing pad and at least one variable in the measured color space. It is provided with a determination unit 2 for evaluating the life of the polishing pad.
Further, the method of managing the polishing pad of the present embodiment includes a measurement step (step S101) in which the measuring unit 1 measures at least one variable in the color space of the polishing pad, and the color space measured by the determination unit 2. The evaluation step (step S102), which evaluates the life of the polishing pad based on at least one variable in the above, is included.

According to the polishing pad measuring system 100 of the present embodiment, it is possible to measure at least one variable (in this example, any one or more of L ^* , a ^* , and b ^* ) of the polishing pad in the color space. it can. Then, as shown in Examples described later, the variable correlates with the clogging amount (% by weight) of Si, and therefore, polishing with any one or more of L ^* , a ^* , and b ^*. It is possible to obtain in advance data showing the relationship with the life of the pad and a prediction formula which is a relational expression between any one or more of L ^* , a ^* , and b ^* and the life of the polishing pad. Then, using the data and / or the prediction formula, the life of the polishing pad can be evaluated based on at least one variable in the measured color space. Then, depending on the evaluation result, predetermined management such as replacement of the polishing pad can be performed.
It also has an advantage in terms of safety in that X-rays and the like are not used for measurement.
As described above, according to the polishing pad measurement system 100 of the present embodiment, the life of the polishing pad can be evaluated and the polishing pad can be managed by a simple method.
In particular, in the present embodiment, since the L ^* a ^* b ^* color space close to human perception is used as the color space, it is a sensation to quantify the clogging of the polishing pad due to foreign matter such as Si residue. Is also easy to understand.
In particular, in the present embodiment, the measuring unit 1 can be performed in a state where the polishing pad is dry, and the accuracy of the measurement by the measuring unit 1 can be further improved.
Further, when quantifying the amount of clogging of a foreign substance such as Si residue, the measurement unit 1 can measure the absolute values of L ^* , a ^* , and b ^* as in the present embodiment. It is preferable to use a colorimeter (for example, when using another measuring instrument such as a color difference meter). In addition, the spectrophotometer has less variation in the results depending on the light source than, for example, a color difference meter.

Similarly, according to the polishing pad measuring method of the present embodiment, at least one variable in the color space of the polishing pad (in this example, any one or more of L ^* , a ^* , and b ^* ) is measured. .. Then, as shown in Examples described later, the variable correlates with the clogging amount (% by weight) of Si, and therefore, polishing with any one or more of L ^* , a ^* , and b ^*. It is possible to obtain in advance data showing the relationship with the life of the pad and a prediction formula which is a relational expression between any one or more of L ^* , a ^* , and b ^* and the life of the polishing pad. Then, using the data and / or the prediction formula, the life of the polishing pad is evaluated based on at least one variable in the measured color space. Then, depending on the evaluation result, predetermined management such as replacement of the polishing pad can be performed.
It also has an advantage in terms of safety in that X-rays and the like are not used for measurement.
As described above, according to the polishing pad measuring method of the present embodiment, the life of the polishing pad can be evaluated and the polishing pad can be managed by a simple method.
In particular, in the present embodiment, since the L ^* a ^* b ^* color space close to human perception is used as the color space, it is a sensation to quantify the clogging of the polishing pad due to foreign matter such as Si residue. Is also easy to understand.
In particular, in the present embodiment, the measurement step (step S101) can be performed in a state where the polishing pad is dry, and the accuracy of measurement by the measurement unit 1 can be further improved.
Further, when quantifying the amount of clogging of foreign matter such as Si residue, in the measurement step (step S101), the absolute values of L ^* , a ^* , and b ^* are measured as in the present embodiment. It is preferable to use a spectrocolorimeter capable of (for example, when using another measuring instrument such as a color difference meter). In addition, the spectrophotometer has less variation in the results depending on the light source than, for example, a color difference meter.

Although the present embodiment has been described above, the present invention is not limited to the above embodiment. For example, in the above example, the example of the L ^* a ^* b ^* color space (L ^* a ^* b ^* color system) is shown as the color space, but the CIE color system, the Mansell color system, and the Ostwald color system are shown. A system, a DIN color system, or the like can also be used. In the case of the CIE color system, in addition to the above L ^* a ^* b ^* color system, an RBG color system, an XYZ color system, an L ^* u ^* v ^* color system, and the like can be used.

Hereinafter, examples of the present invention will be described, but the present invention is not limited to the following examples.

FIG. 4 is a schematic view showing a finish polishing apparatus. A silicon wafer having a diameter of 300 mm was polished using the No. 1 and No. 2 finish polishing devices 200 as shown in FIG. Specifically, as schematically shown in FIG. 4, the polishing head 220 holds one side of the silicon wafer W, and while rotating the silicon wafer W, the polishing pad 250 (material: polyurethane) is attached to the rotation. The surface to be polished of the silicon wafer W was pressed against the platen 240, and the polishing slurry 270 was supplied onto the surface of the polishing pad 250 by the polishing slurry supply mechanism 260 to polish the surface to be polished of the silicon wafer W. After advancing the polishing pad life and polishing to a predetermined polishing time, the polishing pad was collected. By the same work, even when a plurality of polishing times shorter than the predetermined polishing time were set and the polishing pad life was advanced to the polishing time (each of them), the polishing pad life was advanced and the polishing pad was collected. ..

All the collected polishing pads were completely dried, and a photograph of the polished surface of the polishing pads was taken. Further, when the maximum diameter of the polishing surface of the polishing pad is r by elemental analysis using a handheld XRF analyzer (X-ray irradiation area: 15 mm ² ), the distance from the center of the polishing pad is in the range of r / 2. The amount of clogging (% by weight) of Si contained in the X-ray irradiation range near the inside was measured (the lower limit of detection was set to 10 ppm). Further, using a surface defect inspection device (KLA-Tencor, manufactured by Surfscan SP-2), the wafer after polishing is subjected to DWO mode (Dark Field Wide Oblique mode: dark field, wide, oblique incident mode). The number of LPDs having a diameter of 50 nm or more was examined.
FIG. 5 is a diagram showing the relationship between the polishing pad life of the polishing pad and the number of LPDs measured as described above. Further, FIG. 6 is a diagram showing the relationship between the polishing pad life of the polishing pad and the clogging amount (% by weight) of Si as measured above. In FIGS. 5 and 6, the above "predetermined polishing time" is shown as an index "1" of the polishing pad life on the horizontal axis.

On the other hand, the lightness (L ^* ), hue and saturation (a ^* , b ^* ) were measured by the SCI method using a spectrocolorimeter (manufactured by Konica Minolta). FIG. 7A is a diagram showing the relationship between the polishing pad life of the polishing pad and L ^* as measured above. FIG. 7B is a diagram showing the relationship between the polishing pad life of the polishing pad and a ^* as measured above. FIG. 7C is a diagram showing the relationship between the polishing pad life of the polishing pad and b ^* as measured above. In FIGS. 7A to 7C, the above-mentioned "predetermined polishing time" is shown as an index "1" of the polishing pad life on the horizontal axis (the scale notation is "1.0").

First, it can be seen that the amount of clogging of the polishing pad increased as the polishing pad life of the polishing pad progressed.

Next, from FIG. 5, it is understood that even if the polishing pad life of the polishing pad progressed, no change in LPD abnormality was observed in the wafer.

From FIG. 6, it is understood that as the polishing pad life of the polishing pad progressed, the amount of Si clogging of the polishing pad increased linearly.

Then, from FIGS. 7A to 7C, it is understood that L ^* , a ^* , and b ^* change linearly as the polishing pad life of the polishing pad progresses. Specifically, as shown in FIG. 7A, L ^* increased linearly as the polishing pad life of the polishing pad progressed. Further, as shown in FIG. 7B, a ^* decreased linearly as the polishing pad life of the polishing pad progressed. Further, as shown in FIG. 7C, b ^* decreased linearly as the polishing pad life of the polishing pad progressed.

FIG. 8A is a diagram showing the relationship between the clogging amount (% by weight) of Si and L ^* . FIG. 8B is a diagram showing the relationship between the clogging amount (% by weight) of Si and a ^* . FIG. 8C is a diagram showing the relationship between the clogging amount (% by weight) of Si and b ^* . As shown in FIGS. 8A to 8C, it is understood that the clogging amount (% by weight) of Si and L ^* , a ^* , and b ^* each have a high linear correlation. Specifically, as shown in FIG. 8A, as the clogging amount (% by weight) of Si increased, L ^* increased linearly. Further, as shown in FIG. 8B, as the clogging amount (% by weight) of Si increased, a ^* decreased linearly. Further, as shown in FIG. 8C, as the clogging amount (% by weight) of Si increased, b ^* decreased linearly.

From the above, it can be seen that L ^* , a ^* , and b ^* each showed a high linear correlation with the amount of Si clogging (% by weight). In addition, based on the results shown in FIG. 5, L ^* , a ^* , and b ^* are linearly functional with the amount of Si clogging (% by weight), respectively, before the LPD abnormality occurs on the wafer. It can be seen that a high correlation was observed.
^{Therefore, L *, a *, b} * and any one or more of, and data showing the relationship between the life of the polishing ^{pad, L *, a *, b} * and any one or more of the polishing pad life It is understood that a prediction formula, which is a relational formula with, can be obtained in advance.
Therefore, one or more of L ^* , a ^* , and b ^* of the polishing pad are measured, and based on the measured one or more of L ^* , a ^* , and b ^* , the above data and / or It is also understood that the life of the polishing pad can be evaluated by using the prediction formula.

100: Polishing pad management system,
1: Measuring unit,
2: Judgment unit,
3: Communication department,
200: Finish polishing equipment,
220: Polishing head,
240: Rotating surface plate,
250: Polishing pad,
260: Polishing slurry supply mechanism,
270: Polishing slurry

Claims (9)

A measuring step in which the measuring unit measures at least one variable in the color space of the polishing pad.
The polishing pad is measured by the determination unit based on at least one variable in the color space and data showing the relationship between the at least one variable and the amount of foreign matter clogging in the polishing pad and / or a prediction formula. A method for managing a polishing pad, which comprises an evaluation step of evaluating the life of the polishing pad by evaluating the amount of clogging of foreign matter . The color space is an L ^* a ^* b ^* color space.
In the measurement step, at least one of L ^* , a ^* , and b ^* of the polishing pad is measured.
The method for managing a polishing pad according to claim 1, wherein in the evaluation step, the life of the polishing pad is evaluated based on at least one of the measured L ^* , a ^* , and b ^* . In the measurement step, two or more of L ^* , a ^* , and b ^* of the polishing pad are measured.
The method for managing a polishing pad according to claim 2, wherein in the evaluation step, the life of the polishing pad is evaluated based on two or more of the measured L ^* , a ^* , and b ^* . In the measurement step, all of L ^* , a ^* , and b ^* of the polishing pad are measured.
The method for managing a polishing pad according to claim 3, wherein in the evaluation step, the life of the polishing pad is evaluated based on all of the measured L ^* , a ^* , and b ^* . In the evaluation step, the life of the polishing pad is evaluated based on the data showing the relationship between any one or more of L ^* , a ^* , and b ^* and the life of the polishing pad, according to claims 1 to 4. The method for managing a polishing pad according to any one item. In the evaluation step, the life of the polishing pad is evaluated by using a prediction formula which is a relational expression between any one or more of L ^* , a ^* , and b ^* and the life of the polishing pad. The method for managing a polishing pad according to any one of 4. The method for managing a polishing pad according to any one of claims 1 to 6, wherein the measuring step is performed in a state where the polishing pad is dry. The method for managing a polishing pad according to any one of claims 1 to 7, wherein the measuring unit is a spectrocolorimeter. A measuring unit that measures at least one variable in the color space of the polishing pad,
A storage unit that stores data and / or a prediction formula indicating the relationship between the at least one variable and the amount of foreign matter clogging in the polishing pad.
A determination unit that evaluates the life of the polishing pad by evaluating the amount of clogging of foreign matter on the polishing pad based on at least one variable in the measured color space and the data and / or the prediction formula. A polishing pad management system characterized by being equipped with.

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