Polishing device and polishing method for workpiece

Abstract

A double-side polishing device for a workpiece according to the present invention is provided with: a temperature measurement unit that measures temperature on the double-side polishing device; and a control unit that controls the polishing amount of the workpiece on the basis of oscillation of the measured temperature. The temperature measurement unit measures the temperature of polishing slurry on an outer peripheral part of the double-side polishing device. A double-side polishing method for a workpiece according to the present invention includes a temperature measurement step for measuring temperature on the double-side polishing device by the temperature measurement unit, wherein, in the temperature measurement step, the temperature of polishing slurry on an outer peripheral part of the double-side polishing device is measured. The double-side polishing method further includes a control step for controlling, by the control unit, the polishing amount of the workpiece on the basis of oscillation of the temperature of the polishing slurry measured in the temperature measurement step.

Description

Workpiece polishing device and polishing method

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

[0002] In the manufacture of semiconductor wafers, such as silicon wafers, which are typical examples of workpieces used for polishing, a double-side polishing process is commonly employed, in which both the front and back surfaces are polished simultaneously to achieve higher wafer flatness and surface roughness. The required shape of semiconductor wafers (primarily the flatness of the entire surface and the periphery) varies depending on their applications, and it is necessary to determine the target amount of wafer polishing and accurately control that amount according to each requirement. In particular, in recent years, with the miniaturization of semiconductor elements and the increasing diameter of semiconductor wafers, the requirements for semiconductor wafer flatness during exposure have become stricter, and there is a strong demand for methods to appropriately control the amount of wafer polishing.

[0003] In response to this, for example, in Patent Document 1, the present applicant has proposed a method in which, in a double-sided polishing machine in which the carrier plate does not revolve on a rotating table, the temperature of the carrier plate is measured from the side of the polishing machine, and the amount of polishing of the workpiece is controlled based on changes in the phase and / or amplitude of the measured temperature.

[0004] Japanese Patent Application Laid-Open No. 2014-166677

[0005] However, the above method was only applicable to rotating machines in which the carrier plate does not move on a surface plate. In other words, in a revolving machine in which the carrier plate revolves on a rotating surface plate, the revolving carrier plate makes it difficult to continuously measure the temperature of the carrier plate as it moves on the surface plate, making it difficult to analyze changes in temperature amplitude.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a double-sided polishing apparatus and method for polishing a workpiece, which can accurately control the amount of polishing and can be applied to not only rotary machines but also revolution machines.

[0007] As a result of intensive research, the inventors have found that by measuring the temperature of the polishing slurry on the outer periphery of the double-sided polishing machine in a rotating machine and a revolving machine, it is possible to measure the temperature amplitude with high precision and accurately control the polishing amount, and have thus completed the present invention. The gist of the present invention is as follows:

[0008] (1) A double-sided polishing apparatus for a workpiece, comprising: a rotatable carrier plate having one or more holding holes formed therein for holding the workpiece to be polished, at least one of the holding holes being eccentrically positioned; a lower surface plate on which the carrier plate is placed; an upper surface plate paired with the lower surface plate; and polishing pads attached to each of the lower surface plate and the upper surface plate; and further comprising: a temperature measuring unit that measures the temperature on the double-sided polishing apparatus; and a control unit that controls the amount of polishing of the workpiece based on the vibration of the measured temperature, wherein the temperature measuring unit measures the temperature of the polishing slurry on the outer periphery of the double-sided polishing apparatus.

[0009] (2) The double-side polishing apparatus for a workpiece according to (1), wherein the outer periphery is the side surface of the polishing pad and / or the side surface of the lower surface plate.

[0010] (3) A double-sided polishing apparatus for a workpiece described in (1), wherein the outer peripheral portion is between the lower surface plate and the upper surface plate and is the portion radially outward of the center of the retaining hole when the retaining hole is at its outermost position.

[0011] (4) The double-side polishing apparatus for workpieces according to (2), wherein the temperature measuring unit measures the temperature from diagonally above the polishing pad.

[0012] (5) The double-side polishing apparatus for workpieces according to (1) or (2), wherein the temperature measuring unit is an infrared radiometer.

[0013] (6) A method for simultaneously polishing the front and back surfaces of a workpiece by holding the workpiece on a carrier plate having one or more holding holes for holding the workpiece, at least one of the holding holes being eccentrically positioned, and rotating at least the carrier plate between a lower platen and an upper platen to which a polishing pad is attached while supplying a polishing slurry, the method comprising: a temperature measurement step of measuring the temperature on the double-sided polishing apparatus by a temperature measurement unit; in the temperature measurement step, measuring the temperature of the polishing slurry on the outer periphery of the double-sided polishing apparatus; and further comprising a control step of controlling the amount of polishing of the workpiece by a control unit based on the temperature fluctuations of the polishing slurry measured in the temperature measurement step.

[0014] According to the present invention, it is possible to provide a double-side polishing apparatus and a double-side polishing method for a workpiece, which can accurately control the amount of polishing and can be applied to not only rotating machines but also revolving machines.

[0015] Furthermore, by accurately controlling the amount of polishing, it is possible to improve the yield when manufacturing workpieces and when manufacturing devices from workpieces (e.g., wafers). Improving yield improves the manufacturing efficiency of semiconductor products, enabling the production of more high-quality products, promoting technological innovation and contributing to the sustainable development of the industry. Improving yield also contributes to the efficient use of resources by reducing waste of materials consumed in the semiconductor product manufacturing process. Furthermore, improving yield reduces waste of energy consumed in the semiconductor product manufacturing process, thereby contributing to the reduction of greenhouse gas emissions. In other words, the present invention can contribute to, for example, "Goal 9: Industry, Innovation, and Infrastructure," "Goal 12: Ensure Sustainable Consumption and Production," and "Goal 13: Climate Change Action" of the Sustainable Development Goals (SDGs).

[0016] 1 is a top view of a double-side polishing apparatus for workpieces according to one embodiment of the present invention. FIG. 1 is a cross-sectional view taken along line A-A in FIG. 1. FIG. 1 is a cross-sectional view taken along line B-B in FIG. 1. FIG. 2 is a diagram showing the relationship between polishing time and the temperature of the polishing slurry on the side of the polishing pad on the upper surface platen side. FIG. 3 is a diagram showing the relationship between polishing time and the thickness of a silicon wafer. FIG. 4 is a diagram showing the relationship between polishing time and the P-P value A of the temperature of the polishing slurry on the side of the polishing pad on the upper surface platen side. FIG. 5 is a diagram for explaining measurement locations. FIG. 6 is a diagram showing the relationship between polishing time and temperature amplitude for each measurement location. FIG. 7 is a diagram showing the difference in temperature oscillation that can be obtained when the temperature measurement range is adjusted. FIG. 8 is a diagram for explaining the P-P value A, amplitude B, and actual measurement value C.

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0018] <Apparatus for polishing double-sided workpieces> Fig. 1 is a top view of an apparatus for polishing double-sided workpieces according to one embodiment of the present invention. Fig. 1 shows the apparatus for polishing double-sided workpieces as viewed from above with an upper surface plate and a polishing pad attached to the upper surface plate removed. Fig. 2 is a cross-sectional view taken along line A-A in Fig. 1, and Fig. 3 is a cross-sectional view taken along line B-B in Fig. 1.

[0019] As shown in Figures 1 to 3, the double-sided polishing apparatus 1 for workpieces of this embodiment includes a rotatable carrier plate 3 having one or more (only one in the illustrated example) holding holes 4 for holding a workpiece 2 (a silicon wafer in this embodiment) to be polished, at least one of the holding holes 4 being eccentrically positioned, a lower surface plate 5b on which the carrier plate 3 is placed, an upper surface plate 5a that forms a pair with the lower surface plate 5b, and polishing pads 6b, 6a attached to the lower surface plate 5b and the upper surface plate 5a, respectively.

[0020] The double-side polishing machine 1 is equipped with a plurality of motors (not shown), and the upper and lower surface plates 5a and 5b are rotated in opposite directions by the motors. In the illustrated example, the centers of the holding holes 4 are positioned away from the center of the carrier plate 3. The upper and lower surface plates 5a and 5b can clamp the workpiece 2 held in the holding holes 4 with a constant pressure.

[0021] The carrier plate 3 is also provided with an outer peripheral gear (not shown) that meshes with a sun gear 7 and an internal gear 8 provided between the upper and lower surface plates 5a and 5b. The sun gear 7 and / or the internal gear 8 are a drive mechanism that rotates the carrier plate 3 and is driven by a motor different from the motor that rotates the upper and lower surface plates. The outer peripheral gear of the carrier plate 3 meshes with the sun gear 7 and the internal gear 8, causing the carrier plate 3 to rotate. The meshing of the sun gear 7, the internal gear 8, and the outer peripheral gear is not shown in the figure to simplify the double-sided polishing apparatus 1. The internal gear 8 is also composed of individual axle pins, each of which has a large number of rotational drive axle pins arranged in the circumferential direction. The individual axle pins mesh with the outer peripheral gear of the caliper plate 3, causing the carrier plate 3 to rotate. However, the individual axle pins are not shown in the figure to simplify the double-sided polishing apparatus 1.

[0022] Due to this gear meshing, the carrier plate 3 rotates around the center of the carrier plate 3 as a central axis (hereinafter simply referred to as "rotation") in conjunction with the rotation of the lower surface plate 5b and the rotation of the sun gear 7 and / or internal gear 8, while rotating around the center of the carrier plate 3 as a central axis (hereinafter simply referred to as "revolution"), and also rotates around the sun gear 7 around the centers of the upper surface plate 5a and lower surface plate 5b as a central axis (hereinafter simply referred to as "revolution"). In this embodiment, the center of the holding hole 4 is located away from the center of the carrier plate 3, i.e., the workpiece 2 is eccentric with respect to the center of the carrier plate 3, so that with each rotation, the distance between the centers of the upper surface plate 5a and lower surface plate 5b and the center of the workpiece 2 changes periodically. In the workpiece polishing apparatus 1 of this embodiment, the front and back surfaces of the workpiece 2 are simultaneously chemically mechanically polished by the polishing pads 6a and 6b and the polishing slurry 9 while the sandwiched carrier plate 3 rotates and revolves around its axis.

[0023] The workpiece double-sided polishing apparatus 1 of this embodiment further includes a temperature measuring unit 10 for measuring the temperature on the double-sided polishing apparatus 1. The temperature measuring unit 10 is configured to measure the temperature of the polishing slurry 9 on the outer periphery of the double-sided polishing apparatus 1 (e.g., flowing on the outer periphery). The outer periphery is preferably the side surface of the polishing pads 6a, 6b and / or the side surface of the lower surface plate 5b. When measuring the temperature of the polishing slurry 9 on the side surface of the polishing pads 6a, 6b and / or the side surface of the lower surface plate 5b, the temperature measuring unit 10 preferably measures the temperature from diagonally above the polishing pads 6a, 6b. In this case, the temperature measuring unit 10 is preferably an infrared radiometer, for example, an infrared camera (especially one using infrared thermography). Alternatively, the outer periphery is preferably the portion between the lower surface plate 5b and the upper surface plate 5a, radially outward of the center of the holding hole 4 when the holding hole 4 of the rotating carrier plate is at its outermost position. In this case, the temperature measuring unit 10 is preferably a thermocouple.

[0024] The double-sided polishing machine 1 for workpieces of this embodiment further includes a control unit 11 that controls the amount of polishing of the workpieces 2 based on the temperature vibration measured by the temperature measurement unit 10. The control unit 11 can be any known processor. The control unit 11 is connected to a motor provided in the double-sided polishing machine 1 so as to perform wired or wireless communication (not shown). The control unit 11 is also connected to a temperature control unit 10 so as to perform wired or wireless communication (not shown). For example, the temperature measurement unit 10 transmits the temperature measured by the temperature measurement unit 10 to the control unit 11 via wired communication. The control unit 11 transmits a signal to control the motor of the double-sided polishing machine 1 based on the received temperature via wired communication.

[0025] <Method for polishing both sides of a workpiece> Although the method for polishing both sides of a workpiece according to one embodiment of the present invention is not particularly limited, as an example, it can be performed using the apparatus for polishing both sides of a workpiece 1 according to the above-described embodiment. Repetitive explanations of matters that have already been explained regarding the embodiment of the apparatus for polishing both sides of a workpiece 1 will be omitted.

[0026] The method for polishing both sides of a workpiece in this embodiment involves holding the workpiece 2 on a carrier plate 3 having one or more holding holes 4 for holding the workpiece 2, with at least one of the holding holes 4 being eccentrically positioned, and simultaneously polishing the front and back surfaces of the workpiece 2 by rotating at least the carrier plate 3 between a lower surface plate 5b and an upper surface plate 5a to which polishing pads 6a, 6b are attached while supplying a polishing slurry 9.

[0027] The method for polishing both sides of a workpiece according to this embodiment includes a temperature measurement step in which the temperature on the double-sided polishing machine 1 is measured by the temperature measurement unit 10. In the temperature measurement step, the temperature of the polishing slurry on the outer periphery of the double-sided polishing machine 1 is measured. The method for polishing both sides of a workpiece according to this embodiment further includes a control step in which the control unit 11 controls the amount of polishing of the workpiece based on the temperature fluctuation of the polishing slurry 9 measured in the temperature measurement step. The effects of this embodiment will be described below.

[0028] The double-sided polishing apparatus 1 for workpieces of this embodiment includes a temperature measuring unit 10 that measures the temperature on the double-sided polishing apparatus 1, and a control unit 11 that controls the amount of polishing of the workpieces 2 based on the vibrations of the measured temperature. The temperature measuring unit 10 measures the temperature of the polishing slurry 9 on the outer periphery of the double-sided polishing apparatus 1. This allows the temperature on the double-sided polishing apparatus 1 to be constantly measured, regardless of the timing of the rotation and revolution of the carrier plate 3. Furthermore, since it is easy to grasp the vibrations of the temperature of the polishing slurry 9 on the outer periphery of the double-sided polishing apparatus 1, the amount of polishing can be accurately controlled based on the vibrations. As described above, the double-sided polishing apparatus 1 for workpieces of this embodiment allows the amount of polishing to be accurately controlled, and is applicable not only to rotary machines but also to revolution machines.

[0029] The outer periphery is preferably the side surface of the polishing pads 6a, 6b and / or the side surface of the lower platen 5b. As will be shown in the examples described later, the temperature fluctuations of the polishing slurry 9 on the side surfaces of the polishing pads 6a, 6b and / or the side surface of the lower platen 5b are particularly easy to grasp, allowing for more accurate control of the amount of polishing. In this case, the temperature measurement unit 10 is preferably configured to measure the temperature from diagonally above the polishing pads 6a, 6b. This is because it is easy to measure the temperature of the polishing slurry 9 on the side surfaces of the polishing pads 6a, 6b and / or the side surface of the lower platen 5b. Furthermore, from the viewpoint of preventing the adhesion of scattered polishing slurry 9 and cleaning fluid used to clean the platen to the temperature measurement unit 10, it is preferable that the temperature measurement unit 10 be located diagonally above the polishing pads 6a, 6b. In this case, an infrared radiometer is suitable for the temperature measurement unit 10.

[0030] On the other hand, the outer peripheral portion can also be the portion between the lower surface plate 5b and the upper surface plate 5a, radially outward from the center of the retaining hole 4 when the retaining hole 4 of the rotating carrier plate is at its outermost position.

[0031] The method for polishing double-sided workpieces according to this embodiment also includes a temperature measurement step in which the temperature on the double-sided polishing machine 1 is measured by the temperature measurement unit 10. The temperature measurement step also includes a control step in which the temperature of the polishing slurry on the outer periphery of the double-sided polishing machine 1 is measured, and the control unit 11 controls the amount of polishing of the workpiece based on the temperature fluctuations of the polishing slurry 9 measured in the temperature measurement step. This allows the temperature on the double-sided polishing machine 1 to be constantly measured, regardless of the timing of the rotation and revolution of the carrier plate 3. Furthermore, since it is easy to grasp the temperature fluctuations of the polishing slurry 9 on the outer periphery of the double-sided polishing machine 1, the amount of polishing can be accurately controlled based on the fluctuations. As described above, the method for polishing double-sided workpieces according to this embodiment allows the amount of polishing to be accurately controlled, and is applicable to not only rotary machines but also revolution machines.

[0032] Even in the invention of the double-side polishing method for a workpiece, the outer periphery is preferably the side surface of the polishing pads 6a, 6b and / or the side surface of the lower surface plate 5b. As will be shown in the examples described later, the temperature amplitude of the polishing slurry 9 on the side surface of the polishing pads 6a, 6b and / or the side surface of the lower surface plate 5b is particularly easy to grasp, allowing for more accurate control of the amount of polishing. In this case, the temperature measurement unit 10 is preferably configured to measure the temperature from diagonally above the polishing pads 6a, 6b. This is because it is easy to measure the temperature of the polishing slurry 9 on the side surface of the polishing pads 6a, 6b and / or the side surface of the lower surface plate 5b. In this case, an infrared radiometer is also suitable for the temperature measurement unit 10. On the other hand, the outer periphery can also be the portion between the lower surface plate 5b and the upper surface plate 5a, radially outward from the center of the holding hole 4 when the holding hole 4 of the rotating carrier plate is at its outermost position.

[0033] Examples of the present invention will be described below, but the present invention is not limited to these examples in any way.

[0034] Figure 4 shows the relationship between polishing time and the temperature of the polishing slurry on the side of the polishing pad on the upper surface plate when a 300 mm diameter p-type silicon wafer is double-sided polished using the double-sided polishing machine for workpieces shown in Figures 1 to 3. As shown in Figure 4, it can be seen that the temperature fluctuations over time can be easily grasped at any of the five different measurement points, regardless of the polishing time (i.e., the timing of the rotation and revolution of the carrier plate).

[0035] When the temperature measurement unit 10 is configured as an infrared radiometer, the temperature measurement unit 10 measures the temperature of a region of a measurement target having a certain area. From the perspective of clearly grasping temperature fluctuations, a narrower temperature measurement range is preferable. FIG. 9 illustrates the difference in temperature fluctuations obtainable when the temperature measurement range is adjusted. The dotted line graph shows the temperature change over time when the temperature measurement range is a square with sides of 15 cm. The solid line graph shows the temperature change over time when the temperature measurement range is a square with sides of 10 cm. FIG. 9 shows that temperature fluctuations can be obtained more clearly when the temperature measurement range is a square with sides of 10 cm. The temperature measurement range of the temperature measurement unit 10 is preferably an area that fits within a square with sides of 10 cm or less. For example, it can be a square area with sides of 10 cm or less, or a circular area with a diameter of 10 cm or less.

[0036] FIG. 5 shows the relationship between polishing time and silicon wafer thickness. FIG. 6 shows the relationship between polishing time and the P-P value A of the temperature of the polishing slurry on the side of the polishing pad on the upper platen side. Here, the P-P value A is defined as the difference between the maximum and minimum values ​​within one vibration cycle, as shown in FIG. 10. FIGS. 5 and 6 show the results of polishing performed under three conditions of low, normal, and high pressure. As shown in FIG. 5, there is a relationship between polishing time and silicon wafer thickness, in which the silicon wafer thickness decreases (approximately linearly) as the polishing time increases. Furthermore, as shown in FIG. 6, there is a relationship between polishing time and the P-P value A of temperature, in which the P-P value A of temperature decreases (to the extent that it can be linearly approximated) as the polishing time increases. Therefore, if the temperature oscillations shown in FIG. 4 can be grasped, the thickness of the silicon wafer can be calculated (estimated) by analyzing the change in the P-P value A in the temperature oscillations. This allows the polishing end time to be appropriately determined and the amount of polishing to be accurately controlled. For example, the P-P value A of the temperature corresponding to the thickness of the silicon wafer can be obtained by, for example, determining in advance the relational expression between the P-P value A of the temperature and the thickness of the silicon wafer, creating a mapping, or performing machine learning using a sufficient amount of data, and the time at which the temperature amplitude reaches a value corresponding to the desired thickness can be determined as the end time of polishing.

[0037] In addition, as an index used to control the polishing apparatus, in addition to the P-P value A described above, a parameter obtained from the temperature oscillation may be used. As shown in FIG. 10, the amplitude B defined as the width from the center of oscillation to the maximum or minimum value within one oscillation cycle, or the actual temperature measurement value C for each oscillation cycle may also be used.

[0038] Next, to determine the most suitable measurement object, the temperature of the polishing slurry on each of the measurement points, namely, the side of the upper platen, the side of the polishing pad on the upper platen, the side of the polishing pad on the lower platen, and the side of the lower platen, was measured, and the relationship between polishing time and temperature amplitude was tested. FIG. 7 is a diagram for explaining the measurement points, and FIG. 8 is a diagram showing the relationship between polishing time and temperature amplitude for each measurement point. In FIGS. 7 and 8, "upper pad" refers to the polishing pad attached to the upper platen, and "lower pad" refers to the polishing pad attached to the lower platen. As shown in FIG. 8, it can be seen that the polishing slurry flowing on the side of the polishing pad and / or the side of the lower platen is suitable as the measurement object from the perspective of more clearly obtaining temperature fluctuations, and the side of the polishing pad is more suitable. On the other hand, as shown in FIGS. 7 and 8, since there was no slurry flow at the measurement point on the upper platen, it was difficult to obtain temperature fluctuations. Note that temperature measurement is performed by placing the measurement object within the measurement range of the temperature measuring device 10, but is not limited to a configuration in which only the measurement object is present within the temperature measurement range. For example, the temperature at the measurement point of the upper pad is measured by placing the side of the polishing pad attached to the upper platen within the measurement range of the temperature measuring device 10. However, since the polishing pad itself is thin, part of the side of the upper platen is also included in the measurement range of the temperature measuring device 10, but it is possible to obtain temperature fluctuations as shown in Figure 8.

[0039] 1: Workpiece double-side polishing device, 2: Workpiece (wafer), 3: Carrier plate, 4: Holding hole, 5a: Upper surface plate, 5b: Lower surface plate, 6a, 6b: Polishing pad, 7: Sun gear, 8: Internal gear, 9: Polishing slurry, 10: Temperature measuring unit, 11: Control unit

Claims

1. An apparatus for polishing a double-sided workpiece, comprising a rotatable carrier plate having one or more holding holes formed therein for holding the workpiece to be polished, at least one of the holding holes being eccentrically positioned, a lower base plate on which the carrier plate is placed, an upper base plate that forms a pair with the lower base plate, and polishing pads affixed to each of the lower base plate and the upper base plate, further comprising: a temperature measuring unit that measures the temperature on the double-sided polishing apparatus; and a control unit that controls the amount of polishing of the workpiece based on the vibration of the measured temperature, wherein the temperature measuring unit measures the temperature of the polishing slurry on the outer periphery of the double-sided polishing apparatus.

2. An apparatus for polishing both sides of a workpiece as described in claim 1, wherein the outer peripheral portion is a side surface of the polishing pad and / or a side surface of the lower platen.

3. An apparatus for polishing both sides of a workpiece as described in claim 1, wherein the outer peripheral portion is between the lower platen and the upper platen and is a portion radially outward from the center of the retaining hole when the retaining hole is at its outermost position.

4. The double-sided polishing apparatus for workpieces as described in claim 2, wherein the temperature measuring unit measures the temperature from diagonally above the polishing pad.

5. A double-sided polishing apparatus for workpieces as described in claim 1 or 2, wherein the temperature measuring unit is an infrared radiometer.

6. A method for simultaneously polishing the front and back surfaces of a workpiece by holding the workpiece on a carrier plate having one or more holding holes for holding the workpiece, with at least one of the holding holes being eccentrically positioned, and rotating at least the carrier plate between a lower platen and an upper platen to which a polishing pad is affixed while supplying a polishing slurry, the method comprising: a temperature measurement step of measuring the temperature on the double-sided polishing apparatus by a temperature measurement unit; in the temperature measurement step, the temperature of the polishing slurry on the outer periphery of the double-sided polishing apparatus is measured; and further comprising a control step of controlling the amount of polishing of the workpiece by a control unit based on the vibration of the temperature of the polishing slurry measured in the temperature measurement step.

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