Apparatus for polishing both sides of a workpiece and method for polishing both sides of a workpiece

Abstract

The present invention aims to provide a double-sided polishing apparatus and a double-sided polishing method for a workpiece that can improve the roll-off of the outer peripheral shape of the workpiece. [Solution] The temperature of the polishing slurry is adjusted individually for each of the multiple slurry supply systems.

Description

Technical Field

[0001] The present invention relates to a double-sided polishing apparatus for a workpiece and a double-sided polishing method for a workpiece.

Background Art

[0002] Conventionally, in double-sided polishing of a workpiece such as a semiconductor wafer, it has been proposed to control the slurry temperature so that the temperature of the polishing surface of the workpiece during polishing reaches the target temperature (see Patent Document 1).

[0003] In the technique described in Patent Document 1, while measuring the temperature inside the polishing chamber using a temperature sensor, slurry that has been collectively temperature-adjusted by a single slurry temperature adjustment device is supplied to a plurality of slurry discharge holes provided on the upper platen.

Prior Art Documents

Patent Documents

[0007] The gist of the present invention is as follows: (1) Equipped with an upper surface plate and a lower surface plate, A workpiece double-sided polishing apparatus, wherein one or both of the upper and lower polishing plates are provided with a plurality of slurry discharge holes, The plurality of slurry supply systems are formed by the plurality of slurry discharge holes, A workpiece double-sided polishing apparatus, characterized in that each of the plurality of slurry supply systems is equipped with an individual slurry temperature control device.

[0008] (2) The workpiece double-sided polishing apparatus according to (1), wherein the plurality of slurry discharge holes forming the plurality of slurry supply systems are arranged at different radial positions or regions on the surface platen.

[0009] (3) One or both of the upper and lower platens are provided with a plurality of temperature measuring devices for measuring the temperature of the polished surface of the workpiece. The workpiece double-sided polishing apparatus according to (1) or (2), wherein the plurality of temperature measuring devices are arranged at different radial positions or regions on the surface plate.

[0010] (4) A method for polishing both sides of a workpiece, characterized by including an individual temperature adjustment step of individually adjusting the temperature of the polishing slurry for each of the plurality of slurry supply systems formed by a plurality of slurry discharge holes provided in one or both of the upper and lower polishing plates.

[0011] (5) The plurality of slurry discharge holes forming the plurality of slurry supply systems are arranged in different positions or regions on the surface plate for each slurry supply system. In the individual temperature adjustment step, the temperature of the polishing slurry is adjusted such that the temperature of the polishing slurry discharged from the slurry discharge holes arranged at positions or regions closer to the center of the surface plate is lower. The double-sided polishing method for a workpiece according to (4) above.

[0012] (6) Further includes a temperature measurement step of measuring the temperature of the polishing surface of the workpiece at different surface plate radius positions or regions. In the individual temperature adjustment step, the temperature of the polishing slurry is adjusted such that the temperature difference between the different surface plate radius positions or regions measured in the temperature measurement step approaches the target temperature difference. The double-sided polishing method for a workpiece according to (5) above.

[0013] (7) In the individual temperature adjustment step, using the index ΔT / ΔD obtained by dividing the temperature difference ΔT between the different surface plate radius positions measured in the temperature measurement step by the difference ΔD due to the different surface plate radius positions of the distance between the upper surface plate and the lower surface plate, the temperature of the polishing slurry is adjusted. The double-sided polishing method for a workpiece according to (6) above. [Effect of the Invention]

[0014] According to the present invention, it is possible to provide a double-sided polishing apparatus for a workpiece and a double-sided polishing method for a workpiece that can improve the roll-off of the outer peripheral shape of the workpiece. [Brief Description of the Drawings]

[0015] [Figure 1] It is a diagram showing an example of a double-sided polishing apparatus for a workpiece according to an embodiment of the present invention. [Figure 2A] It is a diagram for explaining the generation of heat when the upper and lower surface plates are parallel. [Figure 2B] It is a diagram for explaining the generation of heat when the upper and lower surface plates become non-parallel during polishing. [Figure 3] It is a diagram showing the relationship between the temperature difference within the plane of the upper surface plate and the outer peripheral shape of the wafer after processing in the example. [Figure 4] It is a diagram showing the results of the example. [Figure 5]It is a diagram showing the relationship between ΔT / ΔD and ESFQD in the embodiment.

Embodiment for Carrying out the Invention

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, a double-sided polishing apparatus for a work according to an embodiment of the present invention will be described.

[0017] <Double-sided Polishing Apparatus for Work>[[ID=​​​​​​​​​​

[0020] This double-sided polishing apparatus 1 is provided with a plurality of slurry discharge holes 8 (8a, 8b) (four in the illustrated example) on one or both of the upper platen 2 and the lower platen 3 (only on the upper platen 2 in the illustrated example). In the illustrated example, two slurry discharge holes 8a are located on the inner circumference side of the upper platen 2. In this example, the two slurry discharge holes 8a are positioned symmetrically with respect to the rotation center. The other two slurry discharge holes 8b are located on the outer circumference side of the upper platen 2. In this example, the two slurry discharge holes 8b are positioned symmetrically with respect to the rotation center.

[0021] A slurry supply pipe 9 is connected to each slurry discharge hole 8. Specifically, a slurry supply pipe 9a is connected to each slurry discharge hole 8a on the inner circumference, and a slurry supply pipe 9b is connected to each slurry discharge hole 8b on the outer circumference. The polishing slurry can be supplied from the slurry supply pipe 9 by gravity dripping or by pressure feeding.

[0022] This double-sided polishing apparatus 1 has multiple slurry supply systems formed by multiple slurry discharge holes 8. In this example, the two slurry discharge holes 8a on the inner circumference form an inner-circumferential slurry supply system (in this example, polishing slurry is supplied from two slurry supply pipes 9a, respectively), and the two slurry discharge holes 8b on the outer circumference form an outer-circumferential slurry supply system (in this example, polishing slurry is supplied from two slurry supply pipes 9b, respectively).

[0023] Multiple slurry discharge holes 8 (in this example, inner-circumferential slurry discharge holes 8a and outer-circumferential slurry discharge holes 8b) that form multiple slurry supply systems (in this example, inner-circumferential slurry supply system and outer-circumferential slurry supply system) are arranged at different radial positions or regions of the surface platen. That is, in this example, the inner-circumferential slurry discharge hole 8a is located in a position or region on the inner side of the upper surface platen 2 than the outer-circumferential slurry discharge hole 8b.

[0024] In this double-sided polishing apparatus 1, each of the multiple slurry supply systems is equipped with an individual slurry temperature control device 10. In this example, the inner circumference slurry supply system is equipped with a slurry temperature control device 10a, which individually adjusts the temperature of the polishing slurry supplied from two slurry supply pipes 9a to the inner circumference slurry discharge holes 8a connected to each slurry supply pipe 9a (independently from the polishing slurry from the outer circumference slurry supply pipe 9b). The outer circumference slurry supply system is equipped with a slurry temperature control device 10b (different from the slurry temperature control device 10a), which individually adjusts the temperature of the polishing slurry supplied from two slurry supply pipes 9b to the outer circumference slurry discharge holes 8b connected to each slurry supply pipe 9b (independently from the polishing slurry from the inner circumference slurry supply pipe 9a). The slurry temperature control device 10 may use a heating device and / or a cooling device.

[0025] Furthermore, in this embodiment, one or both of the upper platen 2 and the lower platen 3 (only on the upper platen 2 in the illustrated example) are provided with multiple (two in the illustrated example) temperature measuring devices 11 (11a, 11b) for measuring the temperature of the polishing surface of the workpiece. The multiple temperature measuring devices 11 (11a, 11b) are arranged at different positions or regions on the platen radius. In the illustrated example, the temperature measuring device 11a is located on the inner circumference side of the upper platen 2 (at the bottom of the upper platen 2), and the temperature measuring device 11b is located on the outer circumference side of the upper platen 2 (at the bottom of the upper platen 2). As shown in the illustration, it is preferable to arrange the temperature measuring devices 11 near the slurry discharge holes 8. In the illustrated example, the inner circumference temperature measuring device 11a is located near the inner circumference slurry discharge hole 8a, and the outer circumference temperature measuring device 11b is located near the outer circumference slurry discharge hole 8b. Any known temperature sensor can be used as the temperature measuring device 11.

[0026] <Method for polishing both sides of a workpiece> Next, a method for polishing both sides of a workpiece according to one embodiment of the present invention will be described. Although not particularly limited, for example, this method can be carried out using the workpiece polishing apparatus according to the embodiment described above.

[0027] The method of this embodiment includes an individual temperature adjustment step in which the temperature of the polishing slurry is individually adjusted for each of the multiple slurry supply systems formed by multiple slurry discharge holes 8 provided in one or both of the upper and lower surface plates 2 and 3. In the method of this embodiment, the multiple slurry discharge holes 8 forming the multiple slurry supply systems are arranged at different positions or regions on the surface plate radius for each slurry supply system. In this example, the inner-circumferential slurry discharge holes 8a forming the inner-circumferential slurry supply system are located on the inner side of the surface plate at a position or region closer to the outer-circumferential slurry discharge holes 8b forming the outer-circumferential slurry supply system. In the individual temperature adjustment step, it is preferable to adjust the temperature of the polishing slurry so that the temperature of the polishing slurry discharged from the slurry discharge holes 8 (in this example, the inner-circumferential slurry discharge holes 8a) located closer to the center of the surface plate is lower.

[0028] The effects and advantages of this embodiment will be described below. In double-sided polishing, as a mechanical effect, the relative speed between the workpiece and the rotating platen 4 is relatively faster on the outer circumference side than on the inner circumference side. When the relative speed is faster, the deformation of the polishing pad is suppressed, preventing the workpiece from wrapping around to the outer circumference, which in turn suppresses polishing of the outer circumference of the workpiece and prevents roll-off of the wafer's outer shape.

[0029] <Effects and Effects (Workpiece Double-Sided Polishing Device)> The workpiece double-sided polishing apparatus 1 of this embodiment has a plurality of slurry discharge holes 8 provided in one or both of the upper platen 2 and the lower platen 3, and has a plurality of slurry supply systems formed by the plurality of slurry discharge holes 8, each of the plurality of slurry supply systems is equipped with an individual slurry temperature control device 10. With this configuration, the temperature of the polishing slurry can be individually adjusted for each of the multiple slurry supply systems by the individual slurry temperature control device 10. In particular, the temperature of the polishing slurry can be adjusted so that the temperature of the polishing slurry discharged from the slurry discharge hole 8 (in this example, the slurry discharge hole 8a on the inner circumference side) located closer to the center of the surface plate is lower. As a result, based on the mechanical action described above, the temperature on the outer circumference of the rotating platen 4 can be kept relatively high, which in turn promotes the chemical action on the outer circumference and relatively accelerates polishing on the outer circumference. This promotes polishing while suppressing the roll-off of the workpiece's outer circumference shape, thereby improving the roll-off of the workpiece's outer circumference shape at the end of polishing.

[0030] To ensure that such effects are obtained, it is preferable that the multiple slurry discharge holes 8 forming the multiple slurry supply systems are arranged at different radial positions or regions on the surface plate.

[0031] Furthermore, it is preferable that one or both of the upper and lower platen 2 and the lower platen 3 are provided with multiple temperature measuring devices 11 (11a, 11b) for measuring the temperature of the polished surface of the workpiece, and that the multiple temperature measuring devices 11 (11a, 11b) are arranged at different platen radial positions or regions. This is because the above effect can be more reliably obtained by measuring the temperature at different platen radial positions or regions (for example, the inner circumference and the outer circumference) and adjusting the slurry temperature adjustment device 10 so that the temperature difference between the different platen radial positions or regions obtained from the measurement results approaches a predetermined target value.

[0032] <Effects (Method for polishing both sides of a workpiece)> The double-sided polishing method for workpieces according to this embodiment includes an individual temperature adjustment step in which the temperature of the polishing slurry is individually adjusted for each of the multiple slurry supply systems formed by multiple slurry discharge holes 8 provided in one or both of the upper and lower polishing plates 2 and 3. This allows the temperature of the polishing slurry to be adjusted so that the temperature of the polishing slurry is lower, especially for slurry discharge holes 8 located closer to the center of the polishing plate, thereby promoting polishing while suppressing the roll-off of the outer periphery of the workpiece, as described above, and improving the roll-off of the outer periphery of the workpiece at the end of polishing.

[0033] The method disclosed herein further includes a temperature measurement step of measuring the temperature of the polishing surface of the workpiece at different platen radius positions or regions (e.g., inner and outer circumference), and in the individual temperature adjustment step, it is preferable to adjust the temperature of the polishing slurry so that the temperature difference between the different platen radius positions or regions measured in the temperature measurement step approaches a target temperature difference. This is because the above effects can be obtained more reliably.

[0034] Figure 2A illustrates the heat generation when the upper and lower polishing plates are parallel, while Figure 2B illustrates the heat generation when the upper and lower polishing plates become non-parallel during polishing. Basically, of the temperatures in the polishing environment, the most dominant factor in determining the shape of the workpiece after polishing is the temperature of the polishing slurry. However, for example, the temperature measuring device 11 placed on the upper platen 2 measures not only the temperature of the polishing slurry, but also the temperature of the polishing pad and a small amount of the workpiece temperature as the temperature of the polished surface. Here, as schematically shown in Figure 2A, when the upper platen 2 and the lower platen 3 are parallel, the temperature of the polishing pad 12, which fluctuates due to friction, can be considered to be uniform within the platen surface. If the temperature of the workpiece (wafer) W, which has a relatively small influence, is ignored, the measured temperature can be considered to be essentially the temperature of the polishing slurry, and ΔT=T A -T B (T A The temperature on the inner circumference, T BThe temperature on the outer periphery can be considered as the difference in temperature of the polishing slurry between different radius positions on the surface plate (the temperature of the polishing slurry as a relative value). On the other hand, as schematically shown in Figure 2B, if the parallelism of the rotary platen 4 is disrupted for any reason during double-sided polishing, the friction of the polishing pad 12 on either the inner or outer circumference side of the platen will increase, causing a temperature imbalance in the polishing pad 12. The temperature measured by the temperature measuring device 11 will have a higher temperature added to the polishing pad 12 on either the outer or inner circumference side, making it difficult to obtain the temperature difference of the polishing slurry alone. Note that Figure 2B illustrates the case where the frictional force is stronger on the outer circumference side, and although the thickness of the carrier plate 7 is shown as thinner on the outer circumference side, in reality the thickness of the carrier plate 7 does not actually decrease on the outer circumference side. Rather, the frictional force on the outer circumference side increases because the elastic polishing pad 12 sinks more on the outer circumference side.

[0035] In the method disclosed herein, in the individual temperature adjustment step, it is preferable to adjust the temperature of the polishing slurry using an index ΔT / ΔD obtained by dividing the temperature difference ΔT between different surface plate radius positions measured in the temperature measurement step by the difference ΔD due to the different surface plate radius positions in the distance between the upper surface plate 2 and the lower surface plate 3. For example, if there are two points with different surface plate radii, one on the inner circumference and one on the outer circumference, ΔD is the distance D between the surface plates on the inner circumference. A and the distance D between the surface plates on the outer perimeter B Difference D A -D B That is the case. When the parallelism of the rotating platen 4 is disrupted, the temperature of the polishing pad 12 depends on the radius distance of the platen. In particular, the temperature difference between different platen radius positions is roughly proportional to the difference in distance between those different platen radius positions. Therefore, by normalizing ΔT by ΔD, the effect of heat on the polishing pad due to the disruption of the parallelism of the rotating platen 4 can be removed, and only the temperature difference of the slurry (which is most dominant over the shape of the workpiece after polishing) can be obtained as a measured value. This allows for precise temperature control even when the parallelism of the rotary platen 4 is disrupted, thereby further improving the roll-off of the outer periphery of the workpiece at the end of polishing.

[0036] Although embodiments of the present invention have been described above, the present invention is not limited in any way to the above embodiments. For example, in the above embodiments, an example is shown in which slurry discharge holes 8a and 8b, which form different slurry supply systems, are arranged on the same straight line, but they may be located on different straight lines (or at different circumferential positions). Also, the two or more slurry supply systems may be, for example, three slurry supply systems, or four or more. In the case of having three slurry supply systems, for example, an inner circumferential slurry supply system, an outer circumferential slurry supply system, and an intermediate slurry supply system located at the surface plate radius position between them, and the temperature of the polishing slurry supplied can be adjusted so that it decreases in the order of inner circumferential slurry supply system, intermediate slurry supply system, and outer circumferential slurry supply system. Furthermore, even if the wafers are located at different radius positions on the surface platen, they can be controlled to have the same temperature if they are within the same radius region. For example, if the radius of the wafer is divided into an inner circumference region and an outer circumference region, and two slurry discharge holes 8 are placed in each region, it is clear that adjusting the temperature of the two slurry discharge holes 8a belonging to the inner circumference region and located at different positions to a lower, same temperature, and adjusting the temperature of the two slurry discharge holes 8b belonging to the outer circumference region and located at different positions to a higher, same temperature does not deviate from the spirit of this disclosure. Moreover, such region settings can be appropriately configured in terms of both the number of regions and the range of regions, and are not limited to the above example. Furthermore, various other modifications and alterations are possible. The following describes embodiments of the present invention, but the present invention is not limited to the following embodiments. [Examples]

[0037] To verify the effectiveness of the present invention, double-sided polishing was performed using a workpiece polishing apparatus equipped with two temperature measuring devices on the upper platen side and two slurry supply systems capable of individually controlling the temperature of the supplied polishing slurry. First, the relationship between the temperature difference within the surface of the upper platen and the outer edge shape of the wafer after processing was confirmed from the temperature measurement results at two points. This relationship is shown in Figure 3.

[0038] As shown in Figure 3, it was confirmed that the higher the temperature on the inner circumference of the surface plate (the larger the value on the horizontal axis in Figure 3 (moving to the right in the illustration)), the more the roll-off of the wafer's outer circumference shape is promoted. Furthermore, based on these results, the temperature difference between the inner and outer sides of the surface plate when the temperatures of the two slurry supply systems were individually controlled was set to "inner side - outer side" = -0.5°C (corresponding to the target ESFQD (Edge Site flatness Front reference least sQuare Deviation) value). Note that "ESFQD Mean EE1" in Figure 3 refers to the average value of the ESFQD in the region excluding the outer 1 mm of a 300 mm semiconductor wafer. "ESFQD Mean EE1" was measured using a WaferSight2 manufactured by KLA-Tencor. The temperature was measured using a temperature sensor installed on the upper surface plate of the double-sided polishing machine.

[0039] Figure 4 shows a comparison of the wafer outer edge shape results when the slurry temperature of the two slurry supply systems is individually controlled (inventive example) and when it is not (comparative example). In the inventive example, it can be seen that the roll-off of the wafer outer edge shape is improved compared to the comparative example.

[0040] Figure 5 shows the relationship between ΔT / ΔD and "ESFQD Mean EE1". Furthermore, the difference ΔD between the upper and lower surface plates at two points on the inner and outer circumference was measured. By dividing the measured temperature difference ΔT within the surface plate by the above ΔD, the index ΔT / ΔD was calculated, and its relationship with the outer circumference shape of the wafer (ESFQD Mean EE1) was confirmed. As a result, it was confirmed that the correlation with the outer circumference shape of the wafer improved compared to when the temperature difference ΔT within the surface plate was used as the index alone. [Explanation of Symbols]

[0041] 1: Workpiece double-sided polishing device, 2: Upper surface plate, 3: Lower surface plate, 4: Rotary surface plate, 5: Sangia, 6: Internal gear, 7: Carrier plate, 8: Slurry discharge port, 9: Slurry supply pipe, 10: Temperature control device, 11: Temperature measuring device, 12: Polishing pad, W: Work (wafer)

Claims

1. Equipped with an upper and lower surface plate, A workpiece double-sided polishing apparatus, wherein one or both of the upper and lower polishing plates are provided with a plurality of slurry discharge holes, The plurality of slurry supply systems are formed by the plurality of slurry discharge holes, A workpiece double-sided polishing apparatus characterized in that each of the plurality of slurry supply systems is equipped with an individual slurry temperature control device.

2. The workpiece double-sided polishing apparatus according to claim 1, wherein the plurality of slurry discharge holes forming the plurality of slurry supply systems are arranged at different radial positions or regions on the surface platen.

3. One or both of the upper and lower platens are provided with a plurality of temperature measuring devices for measuring the temperature of the polished surface of the workpiece. The workpiece double-sided polishing apparatus according to claim 1 or 2, wherein the plurality of temperature measuring devices are arranged at different radial positions or regions on the surface plate.

4. A method for polishing both sides of a workpiece, characterized by including an individual temperature adjustment step of individually adjusting the temperature of the polishing slurry for each of the multiple slurry supply systems formed by multiple slurry discharge holes provided in one or both of the upper and lower polishing plates.

5. The plurality of slurry discharge holes forming the plurality of slurry supply systems are arranged in different positions or regions on the surface plate for each slurry supply system. The method for polishing both sides of a workpiece according to claim 4, wherein in the individual temperature adjustment step, the temperature of the polishing slurry is adjusted so that the temperature of the polishing slurry discharged from the slurry discharge hole located closer to the center of the surface plate becomes lower.

6. The process further includes a temperature measurement step of measuring the temperature of the polished surface of the workpiece at different platen radius positions or regions, The method for polishing both sides of a workpiece according to claim 5, wherein in the individual temperature adjustment step, the temperature of the polishing slurry is adjusted so that the temperature difference between the different surface plate radius positions or regions measured in the temperature measurement step approaches a target temperature difference.

7. The method for polishing both sides of a workpiece according to claim 6, wherein in the individual temperature adjustment step, the temperature of the polishing slurry is adjusted using an index ΔT / ΔD obtained by dividing the temperature difference ΔT between the different surface plate radius positions measured in the temperature measurement step by the difference ΔD in the distance between the upper surface plate and the lower surface plate due to the different surface plate radius positions.

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