One-sided polishing method for SOI wafer, one-sided polishing device, and method of manufacturing polished SOI wafer

Abstract

To provide a one-sided polishing method for an SOI wafer capable of more accurately controlling a polishing amount, a one-sided polishing device and a method of manufacturing a polished SOI wafer capable of manufacturing a polished SOI wafer which is accurately polished.SOLUTION: A one-sided polishing method for an SOI wafer includes a polishing amount control step of performing control of a polishing amount based on a moving average value of measured polishing amounts of the SOI wafer. A one-sided polishing device for an SOI wafer comprises a polishing amount control section which performs control of a polishing amount based on a moving average value of measured polishing amounts of the SOI wafer. The number of sections of the moving average value is determined based on a cycle of oscillation of a polishing head. A method of manufacturing a polished SOI wafer uses the one-sided polishing method.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for polishing a single side of an SOI wafer, a single side polishing apparatus, and a method for manufacturing a polished SOI wafer. [Background technology]

[0002] Conventionally, in an SOI (Silicon On Insulator) wafer having a support substrate wafer, an insulating layer provided on one surface of the support substrate wafer, and an active layer wafer provided on the surface of the insulating layer, the active layer wafer has been subjected to single-sided polishing. Such single-sided polishing is performed by horizontally moving a polishing head over the polishing surface of the wafer, causing a polishing cloth to slide against the polishing surface.

[0003] In such single-side polishing, the polishing is sometimes observed by optical techniques in order to control the amount of polishing. For example, Patent Document 1 proposes observing the change in the integrated value of the spectrum in real time.

[0004] In addition, the film thickness of an SOI wafer for use as an active layer is also measured in real time. One example is a method in which light is irradiated onto the active layer wafer and the reflected light is received as it passes through a polishing cloth window. However, the polishing head and the SOI wafer held by the polishing head oscillate horizontally during polishing. Therefore, the SOI wafer moves radially relative to the polishing cloth window and the light irradiating window (measurement window). Therefore, the measurement position (position of the measurement window) of the SOI wafer thickness varies radially on the SOI wafer due to the oscillation. Therefore, when the wafer thickness is measured continuously, different radial positions on the SOI wafer are measured, which means that the radial thickness variation within the SOI wafer is measured. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-156503 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the above-described method for measuring the film thickness value of an active layer wafer, measurements are taken at different radial positions of the SOI wafer, and therefore, the lower the flatness of the SOI wafer before single-side polishing, the more variation there is in the film thickness value, which may result in a decrease in the accuracy of the final polishing amount.

[0007] Therefore, an object of the present invention is to provide a method and apparatus for polishing a single side of an SOI wafer, which can control the amount of polishing with higher precision, and a method for manufacturing a polished SOI wafer, which can manufacture a polished SOI wafer that is polished with higher precision. [Means for solving the problem]

[0008] The gist and configuration of the present invention are as follows. (1) A method for polishing a single-side surface of an SOI wafer, the method comprising: polishing an active layer wafer of an SOI wafer having a support substrate wafer, an insulating layer provided on one surface of the support substrate wafer, and an active layer wafer provided on the surface of the insulating layer, the method comprising: a polishing step of polishing one side of the SOI wafer by using a single-side polishing apparatus including a polishing platen, a polishing cloth attached to the polishing platen, a polishing head capable of holding the SOI wafer and pressing it against the polishing cloth, and a polishing liquid supply unit that supplies a polishing liquid to the polishing cloth, while supplying the polishing liquid from the polishing liquid supply unit to the polishing cloth and rotating the polishing platen and the polishing cloth, a polishing cloth window is provided in the polishing cloth; In the polishing step, the SOI wafer is polished while measuring a polishing amount of the SOI wafer by receiving light reflected by the active layer wafer when light irradiated onto the active layer wafer passes through the polishing cloth window; The method further includes a polishing amount control step of controlling the polishing amount based on a moving average value of the polishing amount of the SOI wafer measured, A single-side polishing method, characterized in that the number of sections of the moving average value is determined based on the oscillation period of the polishing head.

[0009] (2) A single-sided polishing method according to (1), wherein the number of sections of the moving average value is determined based on the oscillation width of the polishing head, the oscillation speed of the polishing head, and the rotation speed of the polishing table.

[0010] (3) The number of intervals N of the moving average value is expressed by the first relational expression, where L (mm) is the oscillation width of the polishing head, v (mm / s) is the oscillation speed of the polishing head, and n (rps) is the rotation speed of the polishing platen. N=2L×n / v The single-side polishing method according to (2) above, wherein the polishing ratio is determined based on the following:

[0011] (4) The single-side polishing method according to any one of (1) to (3), wherein the polishing amount control step uses a polishing amount corrected by a correction value.

[0012] (5) The single-side polishing method according to (4), wherein the correction value is determined based on the polishing rate.

[0013] (6) The correction value C (μm) is expressed by a second relational expression, where R (μm / s) is the polishing rate, L (mm) is the swing width of the polishing head, and v (mm / s) is the swing speed of the polishing head: C=L×R / v The single-side polishing method according to (5) above, wherein the surface roughness is determined by the following formula.

[0014] (7) A single-side polishing apparatus for an SOI wafer, which polishes an active layer wafer of an SOI wafer having a support substrate wafer, an insulating layer provided on one surface of the support substrate wafer, and an active layer wafer provided on the surface of the insulating layer, A polishing platen; a polishing cloth attached to the polishing platen; a polishing head capable of holding the SOI wafer and pressing it against the polishing cloth; a polishing liquid supply unit that supplies a polishing liquid to the polishing cloth; a polishing cloth window is provided in the polishing cloth; a measuring unit that measures the amount of polishing of the SOI wafer by receiving light reflected by the active layer wafer when light irradiated onto the active layer wafer passes through the polishing cloth window; a polishing amount control unit that controls the polishing amount based on a moving average value of the polishing amount of the measured SOI wafer, 10. A single-sided polishing apparatus, wherein the number of sections of the moving average value is determined based on the oscillation period of the polishing head.

[0015] (8) A method for producing a polished SOI wafer using the single-side polishing method according to any one of (1) to (6) above. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide a method and apparatus for polishing a single side of an SOI wafer, which are capable of controlling the amount of polishing with greater precision, and a method for manufacturing a polished SOI wafer, which is capable of manufacturing a polished SOI wafer that is polished with greater precision. [Brief explanation of the drawings]

[0017] [Figure 1] 1A and 1B are a schematic side view and an enlarged view of a main part of an SOI wafer single-side polishing apparatus according to one embodiment of the present invention. [Figure 2] 1 is a schematic top view showing a single-side polishing apparatus for an SOI wafer according to one embodiment of the present invention. [Figure 3]It is a diagram showing the relationship between the polishing time and the indicated film thickness value by one-sided polishing of a conventional SOI wafer. [Figure 4] It is a diagram showing the relationship between the polishing time and the indicated film thickness value by one-sided polishing of an SOI wafer according to the present disclosure. [Figure 5] It is a diagram showing the relationship between the number of moving average intervals and the change amount of the film thickness value of an SOI wafer. [Figure 6] It is a diagram showing the difference between the presence or absence of correction and the final polishing amount.

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. For convenience, first, an embodiment of a one-sided polishing apparatus for an SOI wafer will be described.

[0019] <One-sided Polishing Apparatus for SOI Wafer> FIG. 1 is a schematic side view and an enlarged view of a main part showing a one-sided polishing apparatus for an SOI wafer according to an embodiment of the present invention. FIG. 2 is a schematic top view showing a one-sided polishing apparatus for an SOI wafer according to an embodiment of the present invention.

[0020] This one-sided polishing apparatus 1 polishes the active layer wafer 12 of an SOI wafer W having a support substrate wafer 10, an insulating layer 11 provided on one surface of the support substrate wafer 10, and an active layer wafer 12 provided on the surface of the insulating layer 11 (see the enlarged view of FIG. 1). It is a one-sided polishing apparatus for an SOI wafer.

[0021] 1 and 2, this single-sided polishing apparatus 1 includes a polishing platen 2, a polishing cloth 3 attached to the upper surface of the polishing platen 2, a polishing head 4 capable of holding an SOI wafer W and pressing it against the polishing cloth 3, and a polishing liquid supply unit 5 (a nozzle in this example) that supplies a polishing liquid (polishing slurry) to the polishing cloth 3. By using such single-sided polishing apparatus 1, the polishing liquid is supplied from the polishing liquid supply unit 5 to the polishing cloth 3, and while the polishing platen 2 and the polishing cloth 3 are rotated, the polishing head 4 presses the SOI wafer W against the polishing cloth 3, and the polishing head 4 oscillates (reciprocates) the polishing surface of the SOI wafer W (schematically indicated by two arrows pointing opposite to each other in FIGS. 1 and 2), thereby polishing one side of the SOI wafer W.

[0022] 1 and 2, the polishing platen 2 has a hole 2a penetrating through the thickness of the polishing platen 2, and a polishing platen window 2b is provided above the hole 2a. A portion of the polishing cloth 3 is hollowed out, and a polishing cloth window 3a is provided in that position. The polishing platen window 2b and the polishing cloth window 3a are preferably optically transparent so that light can pass through.

[0023] The single-side polishing apparatus 1 further includes a measuring unit 6. The measuring unit 6 measures the amount of polishing of the SOI wafer W by receiving the light reflected by the active layer wafer 12 when the light irradiated onto the active layer wafer 12 passes through the polishing cloth window 3a. That is, the light irradiated onto the active layer wafer 12 from the measuring unit 6 fixed below strikes the active layer wafer 12 when the polishing cloth window 3a passes through the area irradiated with the light. Therefore, reflected light is obtained at that timing, and the thickness of the active layer wafer 12 can be measured. The thickness of the active layer wafer 12 is measured by calculating the optical path difference. Specifically, the irradiated light is reflected at two points: the surface of the active layer wafer 12 and the interface with the insulating layer 11. The two reflected lights of the irradiated light have an optical path difference equal to the thickness of the active layer wafer 12, and the light-receiving unit of the measuring unit 6 measures this optical path difference. As the thickness of the active layer wafer 12 increases, the optical path difference also increases. Therefore, if the light reflected from the surface of the active layer wafer 12 arrives in a certain time, the distance that the light reflected from the interface of the insulating layer 11 travels becomes longer. This relationship can be utilized to measure the amount of polishing. The measurement unit 6 can further include an optical system that irradiates the active layer wafer 12 with irradiation light. Such a measurement unit 6 can constantly measure the amount of polishing of the SOI wafer W (strictly speaking, every time the polishing cloth window 3a is positioned directly above the polishing platen window 2b). The measurement unit 6 is not particularly limited, but an infrared measuring device can be used. In this example, as shown in the figure, a transparent polishing platen window 2b (which can be made of acrylic, quartz, or the like) is attached to a polishing platen 2 with a hole 2a. A polishing cloth 3 with a hole of the same shape in a plan view is attached on top of the polishing platen 2 so that the hole 2a overlaps the hole in the polishing cloth 3, and a polishing cloth window 3a made of, for example, urethane is attached to the hole in the polishing cloth 3 (above the polishing platen window 2b).

[0024] This single-side polishing apparatus 1 further includes a polishing amount control unit 7. The polishing amount control unit 7 is configured to control the polishing amount based on a moving average value of the polishing amount of the SOI wafer W measured by the measurement unit 6. The polishing amount control unit 7 can be configured by a processor. In this embodiment, the number of sections of the moving average value is determined based on the oscillation period of the polishing head 4. The processor constituting the polishing amount control unit 7 may be set with the determined number of sections of the moving average value, or the polishing amount control unit 7 may have a communication unit and receive the determined number of sections of the moving average value via the communication unit.

[0025] The number of sections of the moving average value is determined based on the oscillation width of the polishing head 4, the oscillation speed of the polishing head 4, and the rotation speed of the polishing table 2, and it is preferable that the polishing amount control unit 7 is configured to control the polishing amount based on the moving average value using the number of sections of the moving average value determined in this manner.

[0026] More specifically, the number of intervals N of the moving average value is determined by the first relational expression, where L (mm) is the oscillation width of the polishing head 4, v (mm / s) is the oscillation speed of the polishing head 4, and n (rps) is the rotation speed of the polishing platen 2. N=2L×n / v The determination can be made based on the following: The number of sections N is calculated by multiplying the time 2L / v that the polishing head 4 takes to oscillate once by the rotation speed n of the lower platen (= number of measurements per second), and therefore means the number of film thickness measurements per oscillating motion. In such cases, if N is not an integer, it can be rounded off. However, it is also possible to round up or down the decimal point, or to use other methods to approximate it to an integer.

[0027] On the other hand, the number of intervals of the moving average value can also be determined by a machine learning technique. For example, an artificial intelligence model is created using a sufficient amount of learning data, which includes the oscillation period of the polishing head 4 as an input and outputs the optimal number of intervals of the moving average value, and the optimal number of intervals of the moving average value can be determined by inputting an input including the oscillation period of the polishing head 4 to the artificial intelligence model. The following describes the effects of the single-side polishing apparatus for SOI wafers of this embodiment.

[0028] FIG. 3 shows the relationship between polishing time and the nominal film thickness (measured film thickness) during conventional single-sided polishing of an SOI wafer. During single-sided polishing, the film thickness of the active layer wafer 12 is measured in real time by receiving and analyzing the reflected light as it passes through the polishing cloth window 3a. The polishing head and the SOI wafer held by the polishing head oscillate horizontally during polishing. Therefore, the SOI wafer moves radially relative to the polishing cloth window and the irradiated light window (measurement window). Therefore, the measurement position (position of the measurement window) of the SOI wafer thickness varies radially across the SOI wafer due to the oscillation. Therefore, when the wafer thickness is measured continuously, different radial positions on the SOI wafer are measured, and the radial thickness variation within the SOI wafer is measured. Therefore, the lower the flatness of the wafer, the more variation there is in the displayed film thickness value, and there is a possibility that multiple displayed film thickness values ​​corresponding to the target final polishing amount will be detected, which may make it difficult to control the polishing amount accurately.

[0029] FIG. 4 shows the relationship between the polishing time and the nominal film thickness value during single-sided polishing of an SOI wafer according to this embodiment. In contrast, in the single-sided polishing apparatus 1 according to this embodiment, the polishing amount control unit 7 controls the polishing amount based on a moving average of the measured polishing amount of the SOI wafer W, and the number of intervals of the moving average is determined based on the oscillation period of the polishing head 4. This allows the polishing amount to be averaged even when the wafer has low flatness. Therefore, as shown in FIG. 4, the timing at which the nominal film thickness value equals the final film thickness value is determined to be unique. Furthermore, since the number of intervals of the moving average is determined based on the oscillation period of the polishing head 4, a moving average that averages out the variation over, for example, m periods (m is an integer greater than or equal to 1) can be calculated. This is suitable for reducing the variation in the measured film thickness value, as will be shown in the examples described below. As described above, according to the SOI wafer single-sided polishing apparatus 1 of this embodiment, the variation in the measured film thickness values ​​is averaged, and the polishing amount can be controlled using the polishing amount that suppresses the influence of the variation as an index, thereby enabling more accurate control of the polishing amount.

[0030] As described above, it is preferable that the number of intervals of the moving average value is determined based on the oscillation width of the polishing head 4, the oscillation speed of the polishing head 4, and the rotation speed of the polishing platen 2, and that the polishing amount control unit 7 is configured to control the polishing amount based on the moving average value using the number of intervals of the moving average value determined in this manner. This configuration is suitable for calculating the oscillation period of the polishing head 4, and by determining the number of intervals of the moving average value based on these parameters, the polishing amount can be controlled with even greater precision.

[0031] The number of intervals N (number of intervals) of the moving average value is expressed by the first relational expression, where L (mm) is the oscillation width of the polishing head 4, v (mm / s) is the oscillation speed of the polishing head 4, and n (rps) is the rotation speed of the polishing platen 2. N=2L×n / v It is preferable that the value is determined based on the following. This is because the variation over m periods (m is an integer of 1 or more) of oscillation of the polishing head 4 can be averaged, and the amount of polishing can be controlled with even greater precision.

[0032] However, since the film thickness of an SOI wafer continues to decrease with single-sided polishing, it was discovered that when using a moving average value, the larger the number of intervals, the more past data is included, resulting in a problem that the measured nominal film thickness value is calculated to be larger. In other words, the film thickness is calculated as being thicker than the actual film thickness relative to the target polishing amount, which may result in over-polishing.

[0033] Therefore, in the single-side polishing apparatus 1 of this embodiment, it is preferable that the polishing amount control unit 7 uses the polishing amount corrected by the correction value. This makes it possible to correct the above-mentioned measured displayed film thickness value, which is calculated to be larger than the actual value when the moving average value is used, by using the correction value, and therefore makes it possible to control the polishing amount with even greater precision.

[0034] In this case, it is preferable that the correction value be determined based on the number of intervals of the moving average value, because as mentioned above, the larger the number of intervals of the moving average value, the more past data is included, and the larger the measured displayed film thickness value is calculated to be, so by determining the correction value based on the number of intervals of the moving average value, the correction value can be made more appropriate.

[0035] It is also preferable that the correction value be determined based on the polishing rate, because the larger the polishing rate, the larger the polishing amount to be corrected for the same number of intervals of the moving average value, and therefore, by using such an index, the correction value can be made more appropriate.

[0036] The correction value C (μm) is determined by the second relational expression, where R (μm / s) is the polishing rate, L (mm) is the swing width of the polishing head 4, and v (mm / s) is the swing speed of the polishing head 4: C=L×R / v It is preferably determined by The above C is the polishing rate R multiplied by the time L / v during which the polishing head 4 oscillates one way, and means the amount of polishing performed while the polishing head 4 oscillates one way. This is because by setting the amount polished while the polishing head 4 swings in one direction as a correction value, the correction value can be made more appropriate.

[0037] On the other hand, the correction value can also be determined based on experimental data or the like. Alternatively, the correction value can also be obtained by a machine learning method. For example, an artificial intelligence model is created using a sufficient amount of training data that includes the polishing rate R (μm / s), the swing width L (mm) of the polishing head 4, and the swing speed v (mm / s) of the polishing head 4 as inputs and outputs an optimal correction value. By inputting an input including the polishing rate R (μm / s), the swing width L (mm) of the polishing head 4, and the swing speed v (mm / s) of the polishing head 4 into the artificial intelligence model, an optimal correction value can also be output and obtained.

[0038] <Single-sided polishing method for SOI wafer> The single-sided polishing method for an SOI wafer according to an embodiment of the present invention is a single-sided polishing method for the active layer wafer 12 of the SOI wafer W having a support substrate wafer 10, an insulating layer 11 provided on one surface of the support substrate wafer 10, and an active layer wafer 12 provided on the surface of the insulating layer 11. The single-sided polishing method for an SOI wafer according to an embodiment of the present invention can be performed, for example, using the above-described single-sided polishing apparatus 1 for an SOI wafer.

[0039] The single-sided polishing method for an SOI wafer in this embodiment includes a polishing step of using a single-sided polishing apparatus 1 including a polishing platen 2, a polishing cloth 3 attached to the polishing platen 2, a polishing head 4 that holds the SOI wafer W and can press it against the polishing cloth 3, and a polishing liquid supply unit 5 that supplies a polishing liquid (polishing slurry) to the polishing cloth 3. While supplying the polishing liquid from the polishing liquid supply unit 5 to the polishing cloth 3, while rotating the polishing platen 2 and the polishing cloth 3, while pressing the SOI wafer W against the polishing cloth 3 with the polishing head 4, and while the polishing head 4 swings (reciprocates) on the polishing surface of the SOI wafer W (schematically shown by two arrows in opposite directions in FIGS. 1 and 2), one side of the SOI wafer W is polished.

[0040] As already explained in the embodiment of the SOI wafer single-side polishing apparatus 1, the polishing platen 2 is provided with a polishing platen window 2b, and the polishing cloth 3 is provided with a polishing cloth window 3a.

[0041] In the polishing process, the SOI wafer W is polished while measuring the amount of polishing of the SOI wafer W by receiving the light reflected by the active layer wafer 12 when the light irradiated onto the active layer wafer 12 passes through the polishing cloth window 3 a.

[0042] The method for polishing a single side of an SOI wafer according to this embodiment further includes a polishing amount control step of controlling the polishing amount based on a moving average value of the measured polishing amount of the SOI wafer W. The number of intervals of the moving average value is determined based on the oscillation period of the polishing head 4. The effects of the method for polishing a single side of an SOI wafer according to this embodiment will be described below.

[0043] The method for polishing a single side of an SOI wafer according to this embodiment further includes a polishing amount control step of controlling the polishing amount based on a moving average value of the measured polishing amount of the SOI wafer W. The number of intervals of the moving average value is determined based on the oscillation period of the polishing head 4. As a result, even if the flatness of the wafer is low, the polishing amount is averaged. Since the number of intervals of the moving average value is determined based on the oscillation period of the polishing head 4, it is possible to obtain a moving average that averages out variations over, for example, m periods (m is an integer equal to or greater than 1). As described above, according to the method for polishing a single side of an SOI wafer of this embodiment, the variation in the measured film thickness values ​​is averaged, and the polishing amount can be controlled using the polishing amount that suppresses the influence of the variation as an index, so that the polishing amount can be controlled with higher precision.

[0044] In the method for polishing a single side of an SOI wafer according to this embodiment, it is preferable that the number of sections of the moving average value is determined based on the oscillation width of the polishing head 4, the oscillation speed of the polishing head 4, and the rotation speed of the polishing platen 2. This is because the amount of polishing can be controlled with even greater precision.

[0045] In the method for polishing a single side of an SOI wafer according to the present embodiment, the number of sections N of the moving average value is determined by the first relational expression, where L (mm) is the oscillation width of the polishing head 4, v (mm / s) is the oscillation speed of the polishing head 4, and n (rps) is the rotation speed of the polishing platen 2. N=2L×n / v It is preferable that the value is determined based on the following. This is because the variation over m periods (m is an integer of 1 or more) of oscillation of the polishing head 4 can be averaged, and the amount of polishing can be controlled with even greater precision. The technique using the first relational expression can be applied when the time required for one rotation of the polishing platen 2 is shorter than the time required for one reciprocating swing of the polishing head 4.

[0046] In the single-side polishing method of this embodiment, it is preferable to use the polishing amount corrected by the correction value in the polishing amount control step, because this makes it possible to control the polishing amount with even greater precision.

[0047] In the single-side polishing method of this embodiment, it is also preferable that the correction value be determined based on the number of sections of the moving average value, because this makes it possible to make the correction value more appropriate.

[0048] In the single-side polishing method of this embodiment, it is also preferable that the correction value be determined based on the polishing rate, since this makes it possible to make the correction value more appropriate.

[0049] In the single-side polishing method of this embodiment, the correction value C (μm) is also determined by the second relational expression, where R (μm / s) is the polishing rate, L (mm) is the oscillation width of the polishing head 4, and v (mm / s) is the oscillation speed of the polishing head 4. C=L×R / v It is preferably determined by This is because by using the amount of polishing performed while the polishing head 4 swings one way as the correction value, the correction value can be made more appropriate.

[0050] On the other hand, in the single-side polishing method of this embodiment, the correction value can also be determined based on experimental data or the like. Alternatively, in the single-side polishing method of this embodiment, the correction value can also be determined by a machine learning technique. For example, an artificial intelligence model including the polishing rate R (μm / s), the oscillation width L (mm) of the polishing head 4, and the oscillation speed v (mm / s) of the polishing head 4 as inputs and outputting an optimal correction value can be created using a sufficient amount of learning data, and the inputs including the polishing rate R (μm / s), the oscillation width L (mm) of the polishing head 4, and the oscillation speed v (mm / s) of the polishing head 4 can be input to the artificial intelligence model, thereby determining and outputting the optimal correction value.

[0051] <Method for manufacturing polished SOI wafers> A method for manufacturing a polished SOI wafer according to one embodiment of the present invention uses the embodiment of the single-side polishing method for an SOI wafer described above. According to the method for manufacturing a polished SOI wafer of this embodiment, the polished SOI wafer can be one in which the variation in measured film thickness is equalized, and the polishing amount is controlled using the polishing amount that suppresses the influence of the variation as an index, thereby enabling the polishing amount to be more precisely controlled. In this way, a polished SOI wafer that is polished with high precision can be manufactured. The active layer wafer 12 of the polished SOI wafer manufactured in this way can have reduced variation from the desired thickness. [Example]

[0052] Example 1 The amount of change in the measured SOI wafer film thickness was compared when the moving average setting value for single-sided polishing was varied. Here, "the amount of change in the SOI wafer film thickness" refers to the difference in the film thickness measured between the tth and t+1th times. The single-sided polishing machine used was as shown in Figures 1 and 2, and the polishing parameters were set to the following ranges: polishing head oscillation width L = 36 to 72 (mm), polishing head oscillation speed v = 6 to 12 (mm / s), and polishing table rotation speed n = 1 to 2 (rps). Under certain conditions within this range, the optimal number of intervals for the moving average was calculated using the first relational expression, and N = 12 was found.

[0053] [Table 1]

[0054] As shown in FIG. 5 and Table 1, when the number of sections of the moving average was set to 3, 6, 9, 12, 15, and 18, the variation in the film thickness value was smallest when the number of sections of the moving average was 12. This suggests that the method of calculating the optimal number of intervals for the moving average value according to the present disclosure can suppress the variation in the amount of change in the film thickness value of the SOI wafer, and therefore can control the amount of polishing with greater precision.

[0055] Example 2 To confirm the polishing accuracy for the final polishing amount with and without the correction value, the difference in the final polishing amount was compared between when the correction value calculated using the second relational expression was used and when the correction value was not used. The closer the difference is to 0, the higher the precision for the final polishing amount.

[0056] [Table 2]

[0057] 6 and Table 2, without correction, polishing proceeded excessively relative to the final polishing amount, whereas with correction by the method of the present disclosure, polishing approached the final polishing amount, suggesting that correction by the method of the present disclosure can improve the accuracy of the final polishing amount.

[0058] [SDGs] According to the present disclosure, it is possible to improve the yield when manufacturing polished SOI wafers and when manufacturing devices from polished SOI wafers. Improving yields increases the manufacturing efficiency of semiconductor products, enabling the production of higher-quality products, promoting technological innovation and contributing to the sustainable development of the industry. Improving yields also contributes to the efficient use of resources by reducing the waste of materials consumed in the semiconductor product manufacturing process. Furthermore, improving yields reduces the waste of energy consumed in the semiconductor product manufacturing process, thereby contributing to the reduction of greenhouse gas emissions. In other words, the present disclosure can contribute to, for example, "Goal 9: Industry, Innovation, and Infrastructure," "Goal 12: Ensure Sustainable Consumption and Production," and "Goal 13: Climate Action" of the Sustainable Development Goals (SDGs). [Explanation of symbols]

[0059] 1: Single side polishing equipment, 2: Polishing table, 2a:hole, 2b: Polishing table window, 3: Polishing cloth, 3a: Polishing cloth window, 4: Polishing head, 5: Polishing liquid supply section, 6: Measuring part, 7: Polishing amount control unit, 10: Support substrate wafer, 11: insulating layer, 12: active layer wafer, W: SOI wafer

Claims

1. 1. A method for polishing a single-side surface of an SOI wafer, the method comprising: polishing an active layer wafer of an SOI wafer having a support substrate wafer, an insulating layer provided on one surface of the support substrate wafer, and an active layer wafer provided on the surface of the insulating layer, the method comprising: a polishing step of polishing one side of the SOI wafer by using a single-side polishing apparatus including a polishing platen, a polishing cloth attached to the polishing platen, a polishing head capable of holding the SOI wafer and pressing it against the polishing cloth, and a polishing liquid supply unit that supplies a polishing liquid to the polishing cloth, while supplying the polishing liquid from the polishing liquid supply unit to the polishing cloth and rotating the polishing platen and the polishing cloth, a polishing cloth window is provided in the polishing cloth; In the polishing step, the SOI wafer is polished while measuring a polishing amount of the SOI wafer by receiving reflected light that is reflected by the active layer wafer when irradiation light that is irradiated onto the active layer wafer passes through the polishing cloth window; The method further includes a polishing amount control step of controlling the polishing amount based on a moving average value of the polishing amount of the SOI wafer measured, A single-side polishing method, characterized in that the number of sections of the moving average value is determined based on the oscillation period of the polishing head.

2. 2. The single-side polishing method according to claim 1, wherein the number of sections of the moving average value is determined based on the oscillation width of the polishing head, the oscillation speed of the polishing head, and the rotation speed of the polishing platen.

3. The number of intervals N of the moving average value is expressed by the first relational expression, where L (mm) is the oscillation width of the polishing head, v (mm / s) is the oscillation speed of the polishing head, and n (rps) is the rotation speed of the polishing platen. N = 2L x n / v The single-side polishing method according to claim 2 , wherein the value is determined based on the following formula:

4. 3. The single-side polishing method according to claim 1, wherein the polishing amount control step uses a polishing amount corrected by a correction value.

5. The single-side polishing method according to claim 4 , wherein the correction value is determined based on a polishing rate.

6. The correction value C (μm) is expressed by a second relational expression, where R (μm / s) is the polishing rate, L (mm) is the oscillation width of the polishing head, and v (mm / s) is the oscillation speed of the polishing head: C = L × R / v The single-side polishing method according to claim 5, wherein the polishing ratio is determined by the following formula:

7. 1. A single-side polishing apparatus for an SOI wafer, which polishes an active layer wafer of an SOI wafer having a support substrate wafer, an insulating layer provided on one surface of the support substrate wafer, and an active layer wafer provided on the surface of the insulating layer, A polishing platen; a polishing cloth attached to the polishing platen; a polishing head capable of holding the SOI wafer and pressing it against the polishing cloth; a polishing liquid supply unit that supplies a polishing liquid to the polishing cloth; a polishing cloth window is provided in the polishing cloth; a measuring unit that measures the amount of polishing of the SOI wafer by receiving light reflected by the active layer wafer when light irradiated onto the active layer wafer passes through the polishing cloth window; a polishing amount control unit that controls the polishing amount based on a moving average value of the polishing amount of the measured SOI wafer, 10. A single-sided polishing apparatus, wherein the number of sections of the moving average value is determined based on the oscillation period of the polishing head.

8. A method for producing a polished SOI wafer using the single-side polishing method according to claim 1.

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