JP7070502B2 - How to select measuring device and polishing head and how to polish wafer - Google Patents

Description

The present invention relates to a measuring device for measuring the shape of a back pad in a polishing head of a single-sided polishing device, a method for selecting a polishing head, and a method for polishing a wafer.

In polishing using a single-sided polishing device, a polishing head composed mainly of a head body (metal, etc.), a base plate or base ring (metal, ceramic, etc.), and a template for holding a wafer is used. This template consists of a back pad and a retainer ring (mainly made of glass epoxy) on its outer circumference. The wafer is held in the holding hole surrounded by the back pad and retainer ring. The wafer holding surface is a back pad (made of a base material such as PET), and by pressurizing this surface during polishing, the wafer is brought into sliding contact with the polishing pad (polishing cloth) attached to the surface plate for polishing. Is going.

Depending on the accuracy of the members themselves that make up the polishing head and the accuracy when they are assembled, the flatness of the polished wafer will vary even when the same rotating shaft of the same device is used. Several methods for measuring, selecting and managing members have been invented.

For example, the polishing head is selected based on the height from the back pad, that is, the pocket depth and the flatness of the retainer ring surface, based on the retainer ring surface in which the wafer holding template is simply attached to the base ring. (Patent Document 1). In this method, one of a plurality of templates is selected so that the difference between the pocket depth and the retainering flatness is within 5 μm.
Further, as an example of measuring the shape of the back pad, there is a method of measuring the thickness variation of the back pad in a state where the pressure and rotation at the time of actual polishing are applied (Patent Document 2).
By these methods, it is possible to control the variation in wafer quality due to the variation in the amount of wafer protrusion from the retainer ring.

JP-A-2017-202556 Japanese Unexamined Patent Publication No. 2004-239718

In recent years, the demand for flatness of polishing wafers has become tighter, and there is a further demand for a measuring device suitable for investigating factors for quality improvement and a method for selecting an appropriate polishing head.
The present invention has been made in view of the above problems, and is a measuring device capable of measuring data having a higher relationship with polishing characteristics (quality of polishing wafer) and a wafer between polishing heads used for polishing. It is an object of the present invention to provide a method for selecting a polishing head capable of adjusting the variation in flatness.

In order to achieve the above object, the present invention holds the back surface of the wafer when polishing the wafer in the polishing head of the single-sided polishing device, and pressurizes the wafer from the opposite side of the holding side using air. It is a measuring device that measures the shape of the back pad to be used.
A template having the back pad and a retainer ring surrounding the outer periphery of the wafer held by the back pad.
With a base ring or base plate located on top of the template,
The shape of the back pad is measured in a state where the polishing head having a head body in which the base ring or the base plate is held is assembled.
With respect to the loading platform on which the assembled polishing head is placed, the support column supporting the loading platform, the clamp that presses the polishing head against the loading platform, and the back pad of the polishing head mounted on the loading platform. It has a pressurizing means with air that can be pressurized and a displacement measuring machine that measures the shape of the back pad.
The displacement measuring machine can measure the shape of the back pad at the time of pressurization by the pressurizing means at the same pressure as when polishing the waha and at the time of non-pressurization. Provided is a measuring device characterized by the above.

The present inventors consider that the polishing characteristics such as the variation in the flatness of the wafer between the polishing heads are related to the assembly accuracy of the polishing head and the deflection of the back pad (shape of the back pad) due to the pressurization with air. rice field. Therefore, the measuring device of the present invention is a device capable of measuring the shape of the back pad not only during non-pressurization but also during pressurization in the polishing head assembled as described above in consideration of them. With such a thing, it is possible to obtain the shape data of the back pad which is more closely related to the polishing characteristics. Therefore, the polishing head can be selected based on the obtained data, and the wafer can be more appropriately polished using the selected polishing head, and the polishing characteristics (flatness variation of the polishing wafer between the polishing heads) can be performed more appropriately. Etc.) can be adjusted (especially suppressed) as appropriate.

Further, the back surface of the polishing head may be placed on the loading platform so that the side of the back pad holding the wafer faces upward.

As described above, if the polishing head can be measured in an upside-down state, easy and accurate measurement can be performed in a short time.

Further, it is possible that three or more of the columns and the clamps are arranged so as to be point-symmetrical with respect to the center of the polishing head mounted on the loading platform in a plan view.

With such a case, the polishing head can be supported more stably and more appropriately, and more appropriate measurement can be performed.

Further, the displacement measuring machine may be a contact type or a non-contact laser type.

With such a thing, the shape of the back pad can be easily measured.

Further, the present invention includes a back pad that holds the back surface of the wafer when polishing the wafer and is pressurized with air from the opposite side of the side that holds the wafer, and the back pad held by the back pad. A template with a retainer ring that surrounds the outer circumference of the wafer,
With a base ring or base plate located on top of the template,
A method of selecting a polishing head having a head body in which the base ring or base plate is held.
The template, the base ring or the base plate, and the head body are assembled to prepare the polishing head.
The shape of the back pad was determined by using a displacement measuring machine for each of the case where the back pad of the prepared polishing head was pressurized with the same pressure as when polishing the wafer and the time when the wafer was not pressurized. Measure and measure
The difference between the measured back pad shapes during pressurization and non-pressurization was calculated.
Provided is a method for selecting a polishing head, which comprises selecting the polishing head based on the calculated difference in the shape of the back pad.

As described above, in the present invention, the polishing head is selected based on the parameter of the difference in the shape of the back pad during pressurization and non-pressurization in the assembled polishing head. Then, if wafer polishing is performed using a desired polishing head selected by such a selection method, the variation in flatness of the polishing wafer between the polishing heads can be appropriately adjusted (particularly suppressed).

Also, when measuring the shape of the back pad,
It is preferable to perform the measurement with the back surface of the polishing head supported so that the side of the back pad holding the wafer faces upward.

In this way, it is easier to measure with the polishing head turned upside down, and accurate selection can be performed in a short time.

Further, the displacement measuring machine used when measuring the shape of the back pad can be a contact type or a non-contact laser type.

As described above, the shape of the back pad can be easily measured by using the contact type or non-contact laser type measuring machine.

Also, when selecting the polishing head,
In advance, the correlation between the difference in the shape of the back pad in the polishing head and the shape data of the polishing wafer obtained by polishing using the polishing head is obtained.
A control value for selecting the polishing head from the correlation is set.
Selection can be made based on the set control value.

By conducting such a preliminary test, obtaining the above correlation, and setting the above control value, it is possible to more easily and surely select the desired polishing head, and the wafer between the polishing heads can be selected. The variation in flatness can be adjusted.

Further, the present invention is a method for polishing a wafer by sliding the surface of the wafer against a polishing cloth attached on a surface plate to polish the wafer.
Provided is a method for polishing a wafer, which comprises holding and polishing the back surface of the wafer by the back pad in the polishing head selected by the method for selecting a polishing head of the present invention.

With such a wafer polishing method, it is possible to adjust the polishing head so that the variation between the polishing heads is suppressed, for example, by selecting the polishing head. Therefore, the flatness variation of the polishing wafer between the polishing heads can be appropriately adjusted. can do.

As described above, according to the present invention, it is possible to obtain shape data of the back pad which is highly related to the polishing characteristics. Further, since the polishing head to be used for polishing can be appropriately selected, it is possible to appropriately adjust the variation in the flatness of the wafer between the polishing heads, and it is possible to suppress the occurrence of the variation in particular.

It is a flow chart which shows an example of the process of the selection method of the polishing head and the polishing method of a wafer of this invention. It is a schematic diagram which shows an example of the single-sided polishing apparatus which can be used in the wafer polishing method of this invention. It is a side view which shows an example of the measuring apparatus of this invention for measuring the shape of the back pad which can be used in the method of selecting a polishing head of this invention. It is a top view which shows an example of a measuring jig. It is a schematic diagram which shows the state of a polishing head at the time of measurement. It is explanatory drawing which shows an example of the measurement point. It is a graph which shows the shape measurement result of the back pad on the same scanning line. It is a graph which shows the relationship between the back pad shape change amount and ESFQD change amount in an Example. It is a graph which shows an example of the flatness (after tilt correction) of the retainer ring in the circumferential direction in the comparative example. It is a graph which shows the relationship between the flatness of retainer ring (maximum value-minimum value from the least squares plane) and the amount of change of ESFQD in the comparative example.

As described above, the present inventors have been diligently researching the measuring device and the selection method because further methods for selecting the measuring device and the polishing head are required due to the tightening of the flatness requirement of the polishing wafer in recent years. Was done.
In order to cope with the above-mentioned tightness, in addition to the accuracy of assembling the polishing head, the measurement of the deflection shape of the back pad surface directly related to the sliding contact of the wafer during pressurization, and such a shape were taken into consideration. The present inventors considered that the above selection is necessary.

In order to particularly suppress the variation in the flatness of the wafer among multiple polishing heads, it is necessary that the pressure applied to the back pad is transmitted uniformly and without loss to the wafer, and the method of transmission must be small among the polishing heads. Therefore, I thought that the amount of deflection as an index of what kind of shape the back pad would have when pressed was an important factor. In addition, since the accuracy when assembling the head body (for example, metal), base plate or base ring, and template may vary, it is necessary to pressurize and measure the back pad with the polishing head assembled. And completed the present invention.

Hereinafter, the present invention will be described in more detail with reference to the drawings, but the present invention is not limited thereto.
FIG. 2 shows an example of a single-sided polishing apparatus that can be used in the wafer polishing method of the present invention. The single-sided polishing apparatus 1 includes a rotatable platen 3 to which the polishing pad 2 is attached, a polishing head 4 that holds the wafer W to be polished, and an abrasive supply for supplying the polishing agent onto the polishing pad 2. It has a mechanism 5. The number of the polishing heads 4 may be one or more, and may be a plurality.

The polishing head 4 has a template 8 including a back pad 6 for holding the back surface of the wafer W and a retainer ring 7 for surrounding the outer periphery of the wafer W. Further, the polishing head 4 has a base ring 9 located on the template 8 and a head body 10 in which the base ring 9 is held. Air can be sent into the space inside the base ring 9, and the back pad 6 can be pressurized by using air from the side opposite to the side holding the wafer W.
Instead of the base ring 9, for example, a base plate having a recess can be used. In any case, it is possible to form a space for sending air for pressurizing the back pad 6.

At the time of polishing, while the polishing agent is supplied by the polishing agent supply mechanism 5, the polishing head 4 and the platen 3 are rotated, and the wafer W held by the polishing head 4 is slidably contacted with the polishing cloth 2 for polishing. be able to.

FIG. 3 shows an example of the measuring device 20 (including a measuring jig, a displacement measuring machine, and a pressurizing means) of the present invention for measuring the shape of a back pad that can be used in the method of selecting a polishing head of the present invention. Is shown. FIG. 3 is a side view.
Further, FIG. 4 shows an example of a top view of the measuring jig.
The measuring jig 11 is located on a base 12, a support column 13 from the base 12, a loading platform 14 on which the polishing head 4 to be measured is placed, and a clamp 15 for pressing the polishing head 4 against the loading platform 14. It has become. Here, an example is shown in which the polishing head 4 is turned upside down at the time of measurement and the back surface of the polishing head 4 is supported with the back pad 6 facing upward. The polishing head 4 is shown by a broken line. If the measurement is performed in such an upside-down state, accurate measurement can be performed more easily and in a short time.
However, the present invention is not limited to this, and it is also possible to support the polishing head 4 with the back pad 6 facing downward and use a measuring jig, a displacement measuring machine, or the like for measuring.

The clamp 15 can be pressed against the retainer ring 7 of the polishing head 4 with a force equivalent to that during polishing. The number of columns 13 and clamps 15 is not particularly limited, but for example, as shown in FIG. 4, the number is three or more, and in a plan view, the center of the measuring jig 11 (the polishing head 4 when the polishing head 4 to be measured is arranged). It can be arranged at equal intervals so as to be point-symmetrical with respect to the center of the back pad 6, that is, the center of the back pad 6. The position of the support column 13 overlaps with the position of the clamp 15. With such an arrangement, the polishing head 4 can be stably supported and the measurement can be performed. Further, when pressing with the clamp 15, a metal ring or the like can be inserted in between.

FIG. 5 shows the state of the polishing head at the time of measurement.
The polishing head 4 supported by the measuring jig 11 as described above is provided with a pressurizing means 16 (pressurizing hose connecting jig 16a, pressurizing air pump 16b). At the time of measurement, the pressurizing hose connecting jig 16a is attached to the head body 10. Through this pressurizing hose connecting jig 16a, air for pressurizing the back pad 6 from the opposite side (back side) of the wafer W holding side (wafer holding side) can be sent from the pressurizing air pump 16b. It has become. It can be pressurized with the same pressure as during polishing. This makes it possible to reproduce the state at the time of polishing at the time of measurement. In addition, of course, it can be in a non-pressurized state.
By attaching the same jig during polishing, the back pad 6 can be pressurized from the back side.

Further, the displacement measuring machine 17 is not particularly limited as long as it can measure the shape of the back pad 6 when it is pressurized with the same pressure as during polishing and when it is not pressurized. For example, a contact-type measuring machine having a spherical short hand at the tip can be used. Alternatively, it may be a non-contact laser type. With such a thing, the shape of the back pad can be easily measured.
As in the example of the measurement point in FIG. 6, it is preferable that the back pad 6 can be linearly scanned in the radial direction. Although FIG. 6 shows an example of scanning at 3 points (3 lines), it is better if 8 points (8 lines) or more can be scanned. The back pad 6 may be linearly scanned as described above with reference to the height position of the retainer ring surface, and the shape of the back pad 6 along the measurement line may be obtained.

With such a measuring device 20, it is possible to obtain data on the shape of the back pad, which includes the accuracy of assembling the polishing head and is more closely related to the polishing characteristics. Then, by using the shape data, it becomes possible to select a more appropriate polishing head and polish the wafer, and it is possible to adjust (particularly suppress) the polishing characteristics such as the variation in the flatness of the polishing wafer between the polishing heads. ..

Next, a method for selecting a polishing head and a method for polishing a wafer according to the present invention will be described. Although an example using the measuring device of the present invention will be described here, the device used for measuring the shape of the back pad for selecting the polishing head is not limited to this.
FIG. 1 shows an example of the process flow in these methods of the present invention.
First, as shown in FIG. 5, the template 8 (back pad 6 and retainer ring 7), the base ring 9, and the polishing head main body 10 are assembled to prepare the polishing head 4 (step 1).
If the polishing head itself is purposely assembled in this way when measuring the shape of the back pad, which will be performed later, the accuracy of this assembly will also vary, and the variation will occur between the polishing heads. This is because it affects the variation in flatness of the polishing wafer. By measuring in a pre-assembled state, it becomes possible to accurately grasp the state of the shape of the back pad peculiar to the polishing head.

Further, as shown in FIG. 5, a pressurizing hose connecting jig 16a is attached to the head body 10 of the assembled polishing head 4, and is connected to the pressurizing air pump 16b with a hose (step 2).
By attaching such a jig, it is possible to send air and pressurize from the back side of the back pad when measuring the shape of the back pad, and the back pad is pressurized not only when it is not pressurized but also when it is pressurized. The shape of is also measurable.

Next, as shown in FIG. 3, the head body 10 is placed on the measuring jig 11 in a form in which the head body 10 is supported by the loading platform 14 (that is, in a form of supporting the back surface of the polishing head 4) with the back pad 6 facing upward (that is, in a form of supporting the back surface of the polishing head 4). Step 3). After mounting, a metal ring of the same size is placed on the retainer ring 7, and the retainer ring 7 is pressed by clamps 15 at three locations with a force equivalent to that during polishing (step 4).

Then, the displacement measuring machine 17 is scanned in the radial direction of the back pad 6 when the wafer is pressurized with air at the same pressure as when polishing the wafer and when the wafer is not pressurized, and the shape of the back pad 6 is formed. (Step 5).
More specifically, for shape measurement, it is preferable to lower the probe of the displacement measuring machine perpendicular to the back pad and scan in the radial direction as shown in FIG. 6, particularly 8 points (8 lines) or more. .. The scanning range may be the entire diameter of the back pad, or may be a limited fixed range near the center. This constant range can be, for example, 50 mm or more. By performing the measurement in such a certain length range, the correlation with the shape of the polishing wafer can be improved.
Using the retainer ring surface as a reference for a height of 0 mm, the shapes in the pressurized state and the non-pressurized state are obtained as described above.

FIG. 7 shows the shape measurement result of the back pad on the same scanning line. It can be seen that it swells upward as a whole when it is pressurized compared to when it is not pressurized. In this example, the amount of change (difference) at a position at a distance of 0 mm from the center was 1.12 mm. The measurement was performed in increments of approximately 1 mm.

Then, the difference between the pressurized state and the non-pressurized state at each position is calculated, the average is taken over the entire area, and the change amount of the scanning line is calculated (step 6). This is repeated at least 3 times, and the average of them is used as the final amount of change in the shape of the back pad. That is, the average value at all scanning angles is obtained (step 7).

It should be noted that this measurement procedure is not limited to this, and it is sufficient that the shapes of each of the pressurized and non-pressurized shapes can be measured and the difference between them can be calculated. Then, the difference itself can be used for selection in the selection process described later, or the back pad shape change amount obtained as the average value as described above can be used for selection. At least, the parameters that can be used for selection are calculated based on the difference in the above shapes.

The same measurement is performed on a plurality of (for example, three or more) polishing heads 4, and the amount of change in the shape of the back pad based on the shape difference as described above is obtained (step 8).

Further, using the polishing head 4 for which the measurement was performed, the wafer W is polished while pressurizing the back pad 6 from the back side by the single-sided polishing device 1 as shown in FIG.
The waha W measures the shape data in advance before polishing, measures the shape data again for the polishing waha obtained by polishing, and calculates the amount of change in the shape data. The type of shape data is not particularly limited, but here, ESFQD (Edge Site Front least sQuares Deviation) can be used.
The amount of change in ESFQD before and after polishing (also referred to as difference ESFQD) thus obtained is associated with the amount of change in the shape of each back pad obtained in step 8, and the correlation between them is obtained.
Then, for example, a threshold value for the amount of change in the shape of the back pad is obtained so that the amount of change in ESFQD changes relatively significantly. Further, in consideration of the threshold value, a control value used for selecting the polishing head is set (step 9).

This control value is not particularly limited, but for example, a critical value of the back pad shape change amount such that the fluctuation of flatness before and after polishing is small, that is, the ESFQD change amount is relatively suppressed can be set as the control value. .. In this case, by selecting a polishing head having a control value or less in the subsequent selection step, it is possible to obtain a polishing wafer having a small amount of change in ESFQD when performing wafer polishing using the polishing head.
By conducting such a preliminary test and obtaining a control value, it is possible to more easily and reliably select a desired polishing head.

Then, the polishing head is selected based on the set control value, and the selected polishing head 4 is used to polish the wafer W while holding the back surface of the wafer W by the back pad 6 pressurized from the back side (). Step 10).
It is possible to select only from the polishing heads obtained in the preliminary test, or to measure the shape of the back pad, calculate the difference, and change the shape of the back pad for other new polishing heads in the same manner as above. It is also possible to calculate the amount, add those new polishing heads, and compare the amount of change in the shape of each back pad with the control value set in the preliminary test for selection from all the polishing heads.

As a result, it is possible to adjust the variation in the flatness (ESFQD, etc.) of the polishing wafer between the polishing heads, which has occurred conventionally, as desired. Depending on the method of selecting the polishing head of the present invention and the method of polishing the wafer in consideration of the assembly accuracy of the polishing head, the deflection of the back pad during pressurization and non-pressurization, etc., between the polishing heads (between the polishing wafers), For example, it is possible to significantly suppress variations in flatness. As a result, the quality of the polishing wafer can be made uniform, and it is possible to meet the recent tight flatness demands.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.
(Example)
For the seven polishing heads (cases 1-7), the method for selecting the polishing head of the present invention and the method for polishing the wafer shown in FIG. 1 were carried out using the measuring device of the present invention as shown in FIG.
Templates (back pad and retainer ring) for wafers with an outer diameter of 365 mm and a holding hole diameter of 302 mm and a diameter of 300 mm were concentrically attached to the base ring, and seven polishing heads attached to the head body were prepared. After placing the back pad on a measuring jig with the back pad facing up and fixing it with a clamp, etc., the shape of the back pad when pressurized (10 kPa) equivalent to that during polishing and when not pressurized using a contact displacement measuring machine. Was measured.
As the contact type displacement measuring machine, a spherical ruby probe having a diameter of 1.0 mm was used, and the shape was measured by vertically contacting the machine. After that, the difference between pressurized and non-pressurized was taken, and the amount of change in the shape of the back pad was obtained for each polishing head.

Then, the wafer was polished using each polishing head.
For polishing, a polishing pad is attached to a ceramic surface plate, and the polishing head and surface plate are rotated to slide the wafer while supplying the polishing slurry of a KOH-based alkaline aqueous solution containing silica-based abrasive grains to the surface plate. I went there. At the time of polishing, the back pad was pressurized from the back side at 10 kPa as in the measurement.

In this way, the amount of change in the shape of the back pad of the seven polishing heads was determined, and the correlation with the amount of change in ESFQD from before polishing of the wafer polished using those polishing heads is shown in Table 1 and FIG.

As can be seen from these correlations, the amount of change in the shape of the back pad was in the range of 0.50 to 1.01 mm for each polishing head even at the same pressure. Then, from the measurement results of the examples, it can be seen that the ESFQD change amount deteriorates when the backpad shape change amount exceeds 0.85 mm. In this way, it was possible to clarify the tendency between the amount of change in ESFQD and the amount of change in the shape of the back pad. In this way, it is considered effective to assemble the polishing head and measure the shape change of the back pad, which is a part for transmitting pressure to the wafer, due to pressure, for evaluation of the polishing head and suppression of quality variation. An example of selecting a polishing head using this correlation will be described in detail below.

Looking at the amount of change in the shape of the wafer (amount of change in ESFQD), when comparing Case 3 and Case 5, Case 3 was as small as 22% of Case 5. In addition, when the amount of change in the shape of the back pad is 0.91 mm or more (Case 5-7) and when it is 0.85 mm or less (Case 1-4), the amount of change in the shape of the wafer (ESFQD change) is average. There was a difference of about 2.7 times. That is, the boundary value at which a large difference occurs in the amount of change in ESFQD, that is, the threshold value of the amount of change in the shape of the back pad can be regarded as around 0.85 mm. Therefore, the control value was set to 0.85 mm.
Then, in order to obtain a polishing head having a small change in ESFQD, a polishing head having a control value or less was selected.

When polishing is performed by selecting and using a polishing head (case 1-4) having a back pad shape change amount of 0.85 mm or less by this selection method, the ESFQD change amount due to polishing is small as desired. In addition, the variation in flatness of the polishing wafer between the polishing heads became stable.

On the other hand, if polishing is performed using the polishing heads of Cases 1-3 and Case 5 at random without performing the selection / polishing method of the present invention, for example, the polishing head of Case 5 is particularly used. Compared to the polishing wafer when the polishing wafer of Case 1-3 is used, the polishing wafer at the time of being used has a large difference in flatness, resulting in variation.

(Comparative example)
For seven polishing heads (cases 1-7) similar to the examples, the flatness of the retainer ring with only the template (back pad and retainer ring) + base ring can be measured without using the measuring device in the present invention. This was done with a contact shape measuring machine.
An example of a template with a position 1 mm from the inner peripheral edge of the retainer ring probing every 5 ° in the circumferential direction and tilt correction from the least squares line (height (mm) from the reference plane (least squares line)). (Case 3) is shown in the graph of FIG. The (maximum value-minimum value) at this time was obtained as the flatness of the retainer ring (7.81 μm in the example of FIG. 9).
Further, in the same manner as in the examples, the wafer was polished using each polishing head, and the amount of change in ESFQD was determined. Table 1 and FIG. 10 show the correlation between the flatness of the retainer ring (maximum value-minimum value from the least squares surface) and the amount of change in ESFQD.

The flatness of the retainer ring for each polishing head ranged from 7.81 to 28.86 μm, and the correlation between them and the amount of change in ESFQD was investigated, but no tendency was observed.

The present invention is not limited to the above embodiment. The above embodiment is an example, and any one having substantially the same structure as the technical idea described in the claims of the present invention and having the same effect and effect is the present invention. It is included in the technical scope of the invention.

1 ... Single-sided polishing device, 2 ... Polishing cloth, 3 ... Surface plate, 4 ... Polishing head,
5 ... Abrasive supply mechanism, 6 ... Back pad, 7 ... Retaining,
8 ... template, 9 ... base ring, 10 ... head body,
11 ... Measuring jig, 12 ... Base, 13 ... Support, 14 ... Loading platform,
15 ... Clamp, 16 ... Pressurizing means, 16a ... Pressurizing hose connection jig,
16b ... Pressurizing air pump, 17 ... Displacement measuring machine,
20 ... The measuring device of the present invention,
W ... Wafer.

Claims (9)

In the polishing head of a single-sided polishing device, a measuring device that holds the back surface of the wafer when polishing the wafer and measures the shape of the back pad that is pressurized with air from the opposite side of the side that holds the wafer. There,
A template having the back pad and a retainer ring surrounding the outer periphery of the wafer held by the back pad.
With a base ring or base plate located on top of the template,
The shape of the back pad is measured in a state where the polishing head having a head body in which the base ring or the base plate is held is assembled.
With respect to the loading platform on which the assembled polishing head is placed, the support column supporting the loading platform, the clamp that presses the polishing head against the loading platform, and the back pad of the polishing head mounted on the loading platform. It has a pressurizing means with air that can be pressurized and a displacement measuring machine that measures the shape of the back pad.
The displacement measuring machine can measure the shape of the back pad at the time of pressurization by the pressurizing means at the same pressure as when polishing the waha and at the time of non-pressurization. A measuring device characterized by that. The measuring device according to claim 1, wherein the loading platform is on which the back surface of the polishing head is placed so that the side of the back pad holding the wafer faces upward. Claim 1 is characterized in that three or more of the columns and the clamps are arranged so as to be point-symmetrical with respect to the center of the polishing head mounted on the loading platform in a plan view. Alternatively, the measuring device according to claim 2. The measuring device according to any one of claims 1 to 3, wherein the displacement measuring device is a contact type or a non-contact laser type. A back pad that holds the back surface of the wafer when polishing the wafer and is pressurized with air from the opposite side of the side that holds the wafer, and a retainer that surrounds the outer periphery of the wafer held by the back pad. With a template with a ring and
With a base ring or base plate located on top of the template,
A method of selecting a polishing head having a head body in which the base ring or base plate is held.
The template, the base ring or the base plate, and the head body are assembled to prepare the polishing head.
The shape of the back pad was determined by using a displacement measuring machine for each of the case where the back pad of the prepared polishing head was pressurized with the same pressure as when polishing the wafer and the time when the wafer was not pressurized. Measure and measure
The difference between the measured back pad shapes during pressurization and non-pressurization was calculated.
A method for selecting a polishing head, which comprises selecting the polishing head based on the calculated difference in the shape of the back pad. When measuring the shape of the back pad,
The method for selecting a polishing head according to claim 5, wherein the measurement is performed with the back surface of the polishing head supported so that the side holding the wafer of the back pad faces upward. The method for selecting a polishing head according to claim 5 or 6, wherein the displacement measuring machine used when measuring the shape of the back pad is a contact type or a non-contact laser type. When selecting the polishing head
In advance, the correlation between the difference in the shape of the back pad in the polishing head and the shape data of the polishing wafer obtained by polishing using the polishing head is obtained.
A control value for selecting the polishing head from the correlation is set.
The method for selecting a polishing head according to any one of claims 5 to 7, wherein selection is performed based on the set control value. It is a method of polishing a wafer by sliding the surface of the wafer against a polishing cloth attached on a surface plate.
A method for polishing a wafer, wherein the back pad of the polishing head selected by the method for selecting a polishing head according to any one of claims 5 to 8 holds and polishes the back surface of the wafer. ..

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