Double-sided polishing condition determination method for wafer, double-sided polishing method for wafer, and wafer manufacturing method

Abstract

To provide a double-sided polishing condition determination method for a wafer, which can provide a wafer of a desired shape.SOLUTION: The double-sided polishing condition determination method for a wafer is for determining a condition for wafer double-sided polishing carried out by rotating upper and lower surface plates to which annular polishing pads are stuck and causing a carrier holding the wafer to self-rotate and roll between the upper and lower surface plates. The method comprises: a correlation acquisition step of acquiring a correlation between a radial polishing pressure distribution between the polishing pads, the presence probability of the wafer at each radial position between the polishing pads, and a shape of the wafer after the double-sided polishing; a target shape acquisition step of acquiring a target shape of the wafer; and a condition determination step of determining a condition for the double-sided polishing so as to achieve the polishing pressure distribution and the presence probability corresponding to the target shape on the basis of the correlation.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present invention relates to a method for determining conditions for double-sided polishing of a wafer, a method for double-sided polishing of a wafer, and a method for manufacturing a wafer. [Background technology]

[0002] Conventionally, a double-side polishing method for increasing the flatness of a wafer is known (see, for example, Patent Document 1). In the method described in Patent Document 1, relationship data is obtained in advance that indicates the relationship between the distance between the plates at two or more positions that are different distances from the center of the rotating platen and the flatness of the workpiece. Next, an optimal value of the distance between the plates at the two or more positions for obtaining a desired flatness of the workpiece is calculated based on the relationship data. Then, the distance between the plates is controlled to the optimal value, for example, by flowing cooling water through the cooling water channel of the upper platen, and the workpiece is polished. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-189524 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, as described in Patent Document 1, simply adjusting the flatness of the workpiece by adjusting the polishing pressure based on the platen distance may not result in a workpiece with the desired shape.

[0005] An object of the present invention is to provide a method for determining conditions for double-sided polishing of a wafer, a method for double-sided polishing of a wafer, and a method for manufacturing a wafer, which are capable of obtaining a wafer of a desired shape. [Means for solving the problem]

[0006] The method for determining conditions for double-sided polishing of a wafer of the present invention is a method for determining conditions for double-sided polishing of a wafer, which determines conditions for double-sided polishing of the wafer, which is performed by rotating upper and lower base plates to which circular polishing pads are attached, while rotating and revolving a carrier holding a wafer between the upper and lower base plates, and includes a correlation acquisition step for acquiring the correlation between the radial polishing pressure distribution between the polishing pads, the presence probability of the wafer at each radial position between the polishing pads, and the shape of the wafer after double-sided polishing, a target shape acquisition step for acquiring a target shape of the wafer, and a condition determination step for determining conditions for double-sided polishing based on the correlation so that the polishing pressure distribution and the presence probability correspond to the target shape.

[0007] In the method for determining conditions for double-sided polishing of a wafer of the present invention, it is preferable that the condition determination step determines the conditions for double-sided polishing on the premise that the polishing pressure distribution is set so that the polishing pressure in the radially intermediate region between the polishing pads is higher than the polishing pressure in the inner and outer edge regions.

[0008] In the method for determining conditions for double-sided polishing of a wafer of the present invention, it is preferable that the condition determination process determines at least one of the shapes of the upper and lower plates and the polishing surface shape of the polishing pad by dressing so that the polishing pressure distribution corresponds to the target shape.

[0009] In the method for determining conditions for double-sided polishing of a wafer of the present invention, it is preferable that the condition determination process determines at least one of the rotation speed of the carrier and the distance from the center of the carrier to the center of the wafer so that the existence probability corresponds to the target shape.

[0010] In the method for determining conditions for double-sided polishing of a wafer of the present invention, it is preferable that the correlation is a correlation between an expected value of pressure received at a specified position of the wafer, obtained based on the polishing pressure distribution and the existence probability, and a shape of the wafer after double-sided polishing, and the condition determination process determines the conditions for double-sided polishing so that the expected value of pressure corresponds to the target shape.

[0011] In the method for determining conditions for double-sided polishing of a wafer of the present invention, it is preferable that the correlation is an expected value difference obtained by dividing the expected value of the pressure received by the outer edge portion from the expected value of the pressure received by the center of the wafer, and a correlation between the shape of the wafer after double-sided polishing, and that the condition determination process determines the conditions for double-sided polishing so that the expected value difference corresponds to the target shape.

[0012] The method for double-sided polishing of wafers of the present invention comprises a step of determining conditions for double-sided polishing based on the above-mentioned method for determining conditions for double-sided polishing of wafers, a condition adjustment step of adjusting the conditions for double-sided polishing based on the determined conditions, and a polishing processing step of polishing both sides of the wafer based on the adjusted conditions.

[0013] The method for producing a wafer of the present invention includes a step of polishing both sides of the wafer by the above-mentioned method for double-sided polishing of a wafer. [Brief description of the drawings]

[0014] [Figure 1] 1 is a perspective view showing a configuration of a double-sided polishing machine according to a prerequisite technique of the present invention; [Diagram 2] 1 is a graph showing the radial polishing pressure distribution between polishing pads based on measured values. [Diagram 3] 13 is a graph showing the calculation results of the presence probability of a wafer at each radial position between polishing pads. [Figure 4] FIG. 2 is a schematic diagram showing the definition of each parameter used to derive an equation expressing the presence probability of a wafer. [Diagram 5] 1 is a graph showing the correlation between the experimental GBIR value and the expected value difference Qdiff. [Figure 6] 1 is a graph showing the radial polishing pressure distribution between polishing pads based on a simulation in Experimental Examples 1 to 3. [Figure 7] 13 is a graph showing GBIR and expected value difference Qdiff based on a simulation in Experimental Examples 4 to 12. [Figure 8] 8 is a graph showing an enlarged range of GBIR from −200 nm to 0 nm in FIG. 7. [Figure 9] 2 is a flowchart showing a method for manufacturing a wafer according to an embodiment of the present invention. [Figure 10] 4 is a flowchart showing a double-sided polishing process according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] [Prerequisite technology] Before describing an embodiment of the present invention, the configuration of a double-sided polishing machine used in the embodiment will be described. Fig. 1 is a perspective view showing the configuration of a double-sided polishing machine according to the prerequisite technology of the present invention.

[0016] The double-sided polishing apparatus 1 includes an upper platen 11, a lower platen 12, a sun gear 13, an internal gear 14, and a plurality of carriers 15. An annular polishing pad 111 is provided on the lower surface of the upper surface plate 11. The upper surface plate 11 has a structure in which metals with different expansion coefficients are bonded together, and is configured so that its shape can be adjusted by adjusting the temperature of cooling water flowing inside. The upper surface plate 11 is raised and lowered by the drive of a lifting mechanism 16. An annular polishing pad 121 is provided on the upper surface of the lower surface plate 12. Sun gear 13 is provided approximately at the center of lower platen 12 so as to rotate independently of lower platen 12. Teeth that mesh with carrier 15 are formed on the outer circumferential surface of sun gear 13. The internal gear 14 is formed in a ring shape surrounding the lower platen 12. Teeth that mesh with a carrier 15 are formed on the inner peripheral surface of the internal gear 14. The upper surface plate 11, the lower surface plate 12, the sun gear 13, and the internal gear 14 have respective rotation centers connected to the rotation shafts of drive motors, so that each of them is rotated independently by each drive motor.

[0017] The carrier 15 is formed in a disk shape. Teeth that mesh with the sun gear 13 and the internal gear 14 are formed on the outer circumferential surface of the carrier 15. Three carrier holes 151 that each accommodate a wafer W are formed in the carrier 15. The carrier holes 151 are formed so that their inner diameters are approximately 0.5 mm larger than the outer diameter of the wafer W.

[0018] In the double-sided polishing apparatus 1 having such a configuration, slurry is supplied between each of the base plates 11, 12, and while each of the base plates 11, 12 is rotated, the carrier 15 is rotated and revolved between each of the base plates 11, 12, thereby polishing both sides of the wafer W contained in the carrier 15.

[0019] [How the present invention was arrived at] Next, the circumstances that led to the invention will be described. The inventor hypothesized that there is a correlation between the radial polishing pressure distribution between the polishing pads, the probability of the presence of any position of the wafer W at each radial position between the polishing pads (hereinafter sometimes simply referred to as the "probability of the presence of the wafer W"), and the shape of the wafer W after double-sided polishing, and verified this hypothesis.

[0020] <Investigation of polishing pressure distribution> The polishing pressure distribution in the radial direction was measured by adjusting the pressing conditions so that the polishing pressure on the inner edge side between the polishing pads 111 and 121 (between the polishing pads) was at a first level higher than other areas. The pressing conditions were adjusted by at least one of adjusting the polishing surface shape of each of the polishing pads 111 and 121 by dressing and adjusting the temperature of the cooling water flowing on the upper platen 11. Similarly, the polishing pressure distribution in the radial direction was measured by adjusting the pressing conditions so that the polishing pressure in the radially intermediate region between the polishing pads was at a second level higher than the other regions (regions on the inner edge side and outer edge side) and at a third level higher than the other regions on the outer edge side. A surface pressure distribution measuring device (e.g., BIG-MAT, a large area pressure distribution measuring system (manufactured by Nitta Corporation)) that measures the surface pressure distribution by the change in electrical resistance value due to pressure was used to measure the polishing pressure distribution. With each polishing pad 111, 121 attached to each of the platens 11, 12, multiple sensor sheets were arranged at equal intervals in the circumferential direction between the polishing pads, and the surface pressure distribution was measured when the upper platen 11 was lowered to a predetermined load. The polishing pressure distribution in the radial direction between the polishing pads based on the measured values ​​is shown in FIG. 2. The polishing pressure shown in FIG. 2 is the average value of the circumferential polishing pressure at each position in the radial direction and is a normalized value.

[0021] <Calculation of the probability of a wafer being present at each radial position between polishing pads> The probability that the center (wafer center) or any position on the periphery (wafer periphery) of the wafer W is present at each radial position between the polishing pads until a given wafer W revolving during double-sided polishing returns from a given radial position between the polishing pads to that given position (until the carrier 15 makes one revolution by rotating on its axis instead of revolving) was calculated as the presence probability of the wafer center or wafer periphery. The calculation results of the presence probability of the wafer at each radial position between the polishing pads are shown in Figure 3. As shown in Fig. 3, it was confirmed that the presence probability differs between the center and the outer periphery of the wafer W. It was confirmed that the center of the wafer W does not exist on the inner edge side or the outer edge side between the polishing pads. It was confirmed that the outer periphery of the wafer W exists over almost the entire radial direction between the polishing pads.

[0022] <Derivation of an equation expressing the probability of a wafer being present at each radial position between polishing pads> The definitions of the parameters used to derive the equation expressing the wafer presence probability are shown in Figure 4. As shown in FIG. 4, the distance from the center (platen center) 11c of each platen 11, 12 to the center (carrier center) 15c of the carrier 15 is r1, the distance from the carrier center 15c to the center (wafer center) Wc of the wafer W is r2, and the distance from the wafer center Wc to an arbitrary position Wp of the wafer W is r w The rotational angular velocity of the carrier 15 is ω2, the time is t, and the angle between the line L1 including the carrier center 15c and the wafer center Wc and the line L2 including the wafer center Wc and an arbitrary position Wp of the wafer W is θ w In this case, the distance R from the platen center 11c to an arbitrary position between the polishing pads can be expressed by the following formula (1).

[0023]

number

[0024] 4, θ1 is the angle between the X-axis in the XY plane perpendicular to the vertical direction and a straight line L3 including the base center 11c and the carrier center 15c. θ2 is the angle between the extension of the straight line L3 and the straight line L1. ω1 is the revolution angular velocity of the carrier 15. ω w is the rotational angular velocity of the wafer W in the carrier hole 151.

[0025] By transforming equation (1), we can obtain the following equation (2).

[0026]

number

[0027] In equation (2), θ w Since is integrated in the circumferential direction of the wafer W as described later, θ w are treated as constants, and q and φ are defined as follows:

[0028]

number

[0029]

number

[0030]

number

[0031] For example, the time required for an arbitrary wafer W to move from a position where the distance R is R1 to a position where the distance R is R2 during double-sided polishing can be expressed by the following equation (6) based on equation (2): In equation (6), t1 is the time when the wafer W is located at the position where the distance R is R1, and t2 is the time when the wafer W is located at the position where the distance R is R2.

[0032]

number

[0033] It can be considered that the larger the value obtained by equation (6), the higher the probability that the wafer W exists in the annular region from the position of distance R1 to the position of distance R2. In equation (6), if the difference between distance R1 and distance R2 is made as small as possible and the difference between time t1 and time t2 is made small, the following equation (7) is obtained.

[0034]

number

[0035] By integrating equation (7) in the circumferential direction of the wafer W, the distance from the wafer center Wc to the position at the distance R from the platen center 11c is r w The following equation (8) can be obtained to express the probability of existence of any position Wp.

[0036]

number

[0037] In equation (8), A is a normalization constant and is expressed by the following equation (9).

[0038]

number

[0039] In formula (8), the distance r1 from the platen center 11c to the carrier center 15c and the distance r2 from the carrier center 15c to the wafer center Wc are values ​​determined by the specifications (apparatus specifications) of the double-sided polishing apparatus 1. The rotation angular velocity ω2 is a value determined by the setting of the rotation angular velocity (carrier rotation angular velocity setting). The rotation angular velocity ω2 is also a value determined by the apparatus specifications. Therefore, it is believed that by changing at least one of the distances r1, r2 and the rotation angular velocity ω2 according to the equipment specifications and the carrier rotation angular velocity setting, it is possible to adjust the probability of the presence of any position of the wafer W at each radial position between the polishing pads.

[0040] <Confirmation of correlation between the radial polishing pressure distribution between the polishing pads, the probability of a wafer being present at each radial position between the polishing pads, and the shape of the wafer after double-sided polishing> In general, in double-sided polishing, the removal amount of the wafer W increases as the polishing pressure increases. If the equation expressing the polishing pressure distribution, which depends on the distance R from the platen center 11c, is p(R), then the distance from the wafer center Wc to the wafer Wc is r w The expected value of pressure Q(r w ) can be expressed by the following formula (10). Formula (10) is obtained by integrating the formula (8) that expresses the existence probability by the formula (8) that expresses the polishing pressure distribution over the entire surface of the platen (range from the inner edge to the outer edge).

[0041]

number

[0042] The expected value of the pressure acting on the wafer center Wc is Q(r w_0), and the expected value of the pressure on the outer edge of the wafer W is Q(r w_max ), Q(r w_0 ) to Q(r w_max ) is subtracted from the expected value (Q diff Then, the following equation (11) is obtained.

[0043]

number

[0044] The smaller the expected value difference obtained from equation (11) is from 0, the greater the expected value of the pressure received by the outer periphery of the wafer. In other words, the wafer W after double-sided polishing is expected to have a convex shape that is thicker at the center (a specified range including the center) than at the outer periphery.

[0045] Next, the above prediction was verified. First, in Experimental Example 1, multiple wafers W having a diameter of 300 mm were double-sided polished by adjusting the pressing conditions so that the polishing pressure distribution in the radial direction was at the first level shown in Fig. 2. In addition, in Experimental Example 2, the same number of wafers W as in Experimental Example 1 were double-sided polished under the same conditions as in Experimental Example 1, except that the pressing conditions were adjusted so that the polishing pressure distribution in the radial direction was at the second level shown in Fig. 2. In addition, in Experimental Example 3, the same number of wafers W as in Experimental Example 1 were double-sided polished under the same conditions as in Experimental Example 1, except that the pressing conditions were adjusted so that the polishing pressure distribution in the radial direction was at the third level shown in Fig. 2. Then, the GBIR (Global flatness back reference ideal range) of each wafer W polished on both sides in Experimental Examples 1, 2, and 3 was measured. Here, the definition of GBIR in the present invention will be described. In a general definition, GBIR represents the difference (absolute value) between the maximum thickness and the minimum thickness in the wafer surface, so it is not a negative value. In the present invention, when the wafer is convex, the value of GBIR is given a positive sign and treated as a positive value. Also, when the wafer is concave, with the center being thinner than the outer periphery, the value of GBIR is given a negative sign and treated as a negative value. In addition, as a method for determining whether a wafer is convex or concave, a method can be exemplified in which the change in the radial thickness of the wafer is averaged in the circumferential direction, and then approximated by a quadratic function, and if the sign of the quadratic term is positive, it is determined to be concave, and if it is negative, it is determined to be convex. In addition, using equation (11), the expected value difference Q diff The difference between the experimental and expected values ​​of GBIR, Q diff The correlation between these is shown in Figure 5. As shown in Figure 5, the difference between the experimental and expected values ​​of GBIR, Q diff In other words, it was confirmed that there is a correlation between the polishing pressure distribution in the radial direction between the polishing pads, the probability of a wafer being present at each position in the radial direction between the polishing pads, and the shape of the wafer after double-side polishing.

[0046] In addition, using the correlation shown in Figure 5, the expected difference Q diff For example, if the target value of GBIR is between -100 nm and +100 nm, the expected difference Q diff The expected value difference Q should be between +0.13 and +0.17. diffTo bring the value within the above allowable range, at least one of the polishing pressure distribution and the probability of the presence of the wafer W may be adjusted. When adjusting the polishing pressure distribution, the above-mentioned method of adjusting the pressing conditions (adjusting the polishing surface shape of each polishing pad 111, 121, and adjusting the temperature of the cooling water flowing through the upper platen 11) may be used. When adjusting the probability of the presence of the wafer W, at least one of adjusting the carrier rotation angular velocity and replacing with a carrier 15 having a different distance r2 from the carrier center 15c to the wafer center Wc may be performed.

[0047] Next, when the correlation shown in FIG. 5 is obtained, the GBIR and the expected value difference Q when the polishing pressure distribution and the distance r2 from the carrier center 15c to the wafer center Wc are set to a predetermined state are diff was calculated by simulation. The polishing pressure distribution in the radial direction between the polishing pads based on the simulation is shown in Fig. 6. The polishing pressure shown in Fig. 6 is the average value of the polishing pressure in the circumferential direction at each position in the radial direction, and is also a normalized value. As shown in Figure 6, first, second and third polishing pressure distributions were set. The first polishing pressure distribution is a distribution in which the polishing pressure in the radial middle region is higher than in other regions (the inner and outer edge regions). The second polishing pressure distribution is a distribution in which the polishing pressure is constant throughout the entire radial direction. The third polishing pressure distribution is a distribution in which the polishing pressure on the inner and outer edge sides is higher than in the radial middle region.

[0048] In Experimental Example 4, the carrier 15 is used in which the distance r2 from the carrier center 15c to the wafer center Wc is the first distance, and the polishing pressure is set to the first polishing pressure distribution, and the GBIR and the expected value difference Q diff In addition, in Experimental Example 5, the GBIR and the expected value difference Q were calculated when double-sided polishing was performed under the same conditions as in Experimental Example 4, except that a carrier 15 having a second distance r2 (=first distance-first distance×5%), which is 5% shorter than the first distance, was used. diffIn addition, in Experimental Example 6, the GBIR and the expected value difference Q were calculated when double-sided polishing was performed under the same conditions as in Experimental Example 4, except that a carrier 15 having a third distance (=first distance+first distance×5%) in which the distance r2 was 5% longer than the first distance was used. diff was calculated. In Experimental Examples 7, 8, and 9, the GBIR and expected value difference Q were measured when double-sided polishing was performed under the same conditions as in Experimental Examples 4, 5, and 6, respectively, except that the polishing pressure distribution was set to the second polishing pressure distribution. diff was calculated. In Experimental Examples 10, 11, and 12, the GBIR and expected value difference Q were measured when double-sided polishing was performed under the same conditions as in Experimental Examples 4, 5, and 6, respectively, except that the polishing pressure distribution was set to the third polishing pressure distribution. diff was calculated.

[0049] GBIR and expected value difference Q based on simulations in Experimental Examples 4-12 diff is shown in Figure 7. As shown in Fig. 7, by setting the polishing pressure distribution to the first polishing pressure distribution in which the polishing pressure in the radial middle region is higher than in other regions, the GBIR can be set to a negative value closer to 0, compared to when the polishing pressure distributions are set to the second and third polishing pressure distributions. In other words, it was confirmed that by setting the polishing pressure distribution to the first polishing pressure distribution, the absolute value of GBIR can be reduced and the flatness of the wafer W can be increased. This coincides with the experimental result in Fig. 5, in which the absolute value of GBIR when the pressing conditions are adjusted to the second level in which the polishing pressure in the radial middle region is higher than in other regions is smaller than when the pressing conditions are adjusted to the first and third levels.

[0050] FIG. 8 shows an enlarged graph of the GBIR range of FIG. 7 from −200 nm to 0 nm. As shown in Figure 8, when the polishing pressure distribution is set to the first polishing pressure distribution, it was confirmed that the longer the distance r2 from the carrier center 15c to the wafer center Wc, the closer the negative value of GBIR becomes to 0, and the higher the flatness of the wafer W can be achieved.

[0051] <Summary> As described above, the inventor has discovered that there is a correlation between the radial polishing pressure distribution between the polishing pads, the probability of the presence of the wafer W at each radial position between the polishing pads, and the shape of the wafer W after double-sided polishing. The inventor then discovered that a wafer having a desired shape can be obtained by obtaining the above correlation, obtaining the target shape of the wafer W, and determining the conditions for double-sided polishing so as to obtain the polishing pressure distribution and existence probability corresponding to the target shape based on the correlation, and thus completed the present invention.

[0052] [Embodiment] <Wafer manufacturing method> Next, a method for manufacturing a wafer according to an embodiment of the present invention will be described. Fig. 9 is a flow chart showing the method for manufacturing a wafer. Fig. 10 is a flow chart showing a double-side polishing process. In this embodiment, a wafer W made of silicon and having a diameter of 300 mm is exemplified; however, the wafer may be made of materials such as germanium, gallium arsenide, gallium phosphide, or indium phosphide, and may have a diameter of a predetermined value not less than 150 mm and not more than 450 mm.

[0053] As shown in FIG. 9, the wafer manufacturing method includes a pulling step S1, a block processing step S2, a slicing step S3, a pre-processing step S4, a double-side polishing step S5, a single-side finishing step S6, and a cleaning step S7.

[0054] In the pulling step S1, a cylindrical silicon single crystal is pulled up from a silicon melt by the Czochralski method. In the block processing step S2, the outer periphery of the single crystal ingot is ground, notched according to the crystal orientation, and cut into a plurality of blocks using, for example, a band saw. In the slicing step S3, the block is sliced ​​into a plurality of wafers W, each having a thickness of, for example, about 1 mm, using an inner diameter blade cutter or a wire saw. In the pre-processing step S4, chamfering is performed and rough polishing (lapping) is performed with, for example, an alumina abrasive so that both surfaces of the wafer W are parallel. Then, after etching or the like is performed as necessary, a planarization process is performed to remove unevenness on the surface of the wafer W.

[0055] The double-sided polishing step S5 corresponds to the double-sided polishing method of the present invention for the wafer W, and includes the double-sided polishing condition determining method of the present invention for the wafer W. In the double-sided polishing step S5, a double-sided polishing apparatus 1 is used to perform a mirror finish on the pre-treated wafer W to enhance the flatness. In the single-side finishing step S6, the polished surface of the wafer W obtained in the double-side polishing step S5 is polished. By carrying out the polishing process in the single-side finishing step S6, scratches and damage on the polished surface of the wafer W can be removed, and at the same time, the surface roughness of the polished surface can be adjusted. In the cleaning step S7, the wafer W obtained in the single-side finishing step is cleaned with, for example, an alkaline solution.

[0056] Next, the double-side polishing step S5 will be described in detail. 10, the double-sided polishing process S5 includes a correlation obtaining step S51, a target shape obtaining step S52, a target expected value difference calculating step S53, a condition determining step S54, a condition adjusting step S55, and a polishing process step S56. The correlation obtaining step S51, the target shape obtaining step S52, the target expected value difference calculating step S53, and the condition determining step S54 constitute a method for determining conditions for double-sided polishing of a wafer W according to the present invention.

[0057] In a correlation acquisition step S51, the computer acquires the correlation between the GBIR and the expected value difference as shown in Fig. 5 from, for example, a storage unit (not shown). The correlation may be obtained by an experiment or a simulation.

[0058] In the target shape acquisition step S52, the computer acquires a target GBIR as a target shape of the wafer W after double-side polishing, based on, for example, an operator's operation of an input unit (not shown).

[0059] In a target expected value difference calculation step S53, the computer calculates a target expected value difference that allows the GBIR of the wafer W after double-side polishing to become the target GBIR, based on the correlation acquired in the correlation acquisition step S51. For example, when the target GBIR is -100 nm or more and +100 nm or less, the target expected value difference calculated based on the correlation shown in FIG. 5 is +0.13 or more and +0.17 or less.

[0060] In the condition determination step S54, the computer calculates the expected value difference Q diff The conditions for double-sided polishing are determined so that the difference between the expected values ​​calculated in the target expected value difference calculation step S53 becomes the target expected value difference. In other words, in the condition determination step S54, the conditions for double-sided polishing are determined so that the polishing pressure distribution and the existence probability used to calculate the expected values ​​of the formulas (10) and (11) become values ​​corresponding to the target GBIR. For example, in the condition determination step S54, when the target GBIR is −100 nm or more and +100 nm or less, the expected value difference Q diff The conditions of double-sided polishing are determined so that the probability of existence is +0.13 or more and +0.17 or less. The polishing conditions for making the polishing pressure distribution a predetermined distribution are, for example, at least one of the polishing surface shape of each polishing pad 111, 121 by dressing and the temperature of the cooling water flowing through the upper platen 11. The polishing conditions for making the probability of existence a predetermined probability are, for example, at least one of the rotation angular velocity of the carrier 15 and the distance r2 from the carrier center 15c to the wafer center Wc.

[0061] In the condition determination step S54, the polishing pressure distribution is set to a distribution in which the polishing pressure in the radially intermediate region between the polishing pads is higher than the polishing pressure in the regions on the inner and outer edges. diff It is preferable to determine the conditions of double-sided polishing so that the probability of existence becomes the target expected value difference, that is, the probability of existence corresponds to the target GBIR. By performing double-side polishing under such a polishing pressure distribution condition, it is possible to make the GBIR a negative value close to 0, and to increase the flatness of the wafer W. In this case, it is preferable to determine the conditions of double-sided polishing so as to obtain the presence probability corresponding to the target GBIR, on the premise that a carrier 15 having a longer distance r2 from the carrier center 15c to the wafer center Wc is used. By using such a carrier 15 to perform double-side polishing, the GBIR can be brought closer to 0, and the flatness of the wafer W can be increased.

[0062] In the condition adjustment step S55, the worker adjusts the conditions for double-side polishing based on the polishing conditions determined in the condition determination step S54. For example, the worker adjusts at least one of the dressing conditions of the polishing pads 111, 121, the temperature of the cooling water flowing through the upper platen 11, the rotational angular velocity of the carrier 15, and the distance r2 from the carrier center 15c to the wafer center Wc. When adjusting the distance r2 from the carrier center 15c to the wafer center Wc, the worker replaces the carrier 15 with a carrier 15 having a different distance r2 (a different radial position of the carrier hole 151) (hereinafter, sometimes referred to as a "carrier 15 of different specifications").

[0063] In the polishing process S56, the double-sided polisher 1 polishes both sides of the wafer W based on the conditions adjusted in the condition adjusting process S55. By the polishing process S56, a wafer W having a GBIR equal to the target GBIR can be obtained.

[0064] <Effects of the embodiment> The method for determining double-sided polishing conditions for a wafer W includes a correlation acquisition process S51 for acquiring the correlation shown in FIG. 5, a target shape acquisition process S52 for acquiring a target GBIR for the wafer W, and a condition determination process S54 for determining the conditions for double-sided polishing based on the correlation so as to obtain a polishing pressure distribution and existence probability corresponding to the target GBIR. In this way, by polishing the wafer W using conditions determined based on the polishing pressure distribution as well as the probability of the wafer W being present at each radial position between the polishing pads, a wafer W of the desired shape can be obtained. Furthermore, in the method described in Patent Document 1, if the rotational angular velocity of the carrier 15 is changed or the carrier 15 is replaced with a carrier 15 of different specifications, the relationship between the platen distance (polishing pressure distribution) and the flatness of the wafer W changes, and therefore it is necessary to perform an experiment again to obtain relational data showing the relationship. In this embodiment, even if the rotational angular velocity or specifications of the carrier 15 are changed as described above, that is, even if the existence probability of the wafer W is changed, it is possible to determine the double-sided polishing conditions so that the polishing pressure distribution and existence probability corresponding to the target shape are obtained based on the already existing correlation without performing experiments or simulations to obtain the correlation. Furthermore, since the wafers W can be obtained in a desired shape, the yield of the wafers W is improved, and it is possible to realize improved energy efficiency, improved production efficiency, and reduced waste.

[0065] In the correlation acquisition step S51, the GBIR and the expected value difference Q diff In the condition determination step S54, the expected value difference Q corresponding to the target GBIR is obtained. diff The double-side polishing conditions are determined so that In this way, the expected difference Q diff By using correlations including the above, it is possible to control the GBIR with higher precision. In particular, the expected value difference Q diff is the difference between the expected value of the pressure applied to the wafer center Wc and the expected value of the pressure applied to the outer edge of the wafer W. diff By using the correlation between the thickness difference in the wafer W and the GBIR, it is possible to control the GBIR with even higher precision.

[0066] [Variations] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and various improvements and design changes that do not deviate from the gist of the present invention are also included in the present invention.

[0067] For example, the correlation acquisition step S51, the target shape acquisition step S52, the target expected value difference calculation step S53, and the condition determination step S54 may be performed by an operator. Specifically, the operator may check the correlation displayed on the display unit of a computer or on a sheet-like medium such as paper (correlation acquisition step S51), check the target shape of the wafer W based on the product specifications or the like (target shape acquisition step S52), calculate the target expected value difference (target expected value difference calculation step S53), and determine the conditions for double-sided polishing (condition determination step S54).

[0068] The correlation acquired in the correlation acquisition step S51 may be a correlation between the expected value of the pressure that a predetermined position of the wafer W receives, calculated based on the formula (10), and the shape of the wafer W after double-sided polishing. In this case, the target expected value difference calculation step S53 is not performed, and the conditions for double-sided polishing may be determined in the condition determination step S54 so that the expected value difference corresponds to the target shape. The correlation acquired in the correlation acquisition step S51 may be a correlation between the polishing pressure distribution in the radial direction between the polishing pads, the existence probability of the wafer W at each position in the radial direction between the polishing pads, and the shape of the wafer W after double-sided polishing. In this case, the target expected value difference calculation step S53 is not performed, and the conditions for double-sided polishing can be determined in the condition determination step S54 so that the polishing pressure distribution and existence probability correspond to the target shape. [Industrial Applicability]

[0069] According to the method for determining conditions for double-sided polishing of a wafer, the method for double-sided polishing of a wafer, and the method for manufacturing a wafer of the present invention, a wafer W having a desired shape can be obtained, and therefore the yield of the wafer W can be improved, and energy efficiency, production efficiency, and waste can be reduced. Furthermore, the improvement in production efficiency of the wafer manufacturing process improves the productivity and quality of the wafer, making it possible to meet greater demand. This improves the productivity of the entire semiconductor industry and promotes economic growth. [Explanation of symbols]

[0070] 11...upper platen, 12...lower platen, 15...carrier, 111, 121...polishing pad, W...wafer.

Claims

1. A method for determining conditions for double-sided polishing of a wafer, the method comprising: rotating upper and lower polishing plates to which annular polishing pads are attached, and rotating and revolving a carrier holding a wafer between the upper and lower polishing plates; a correlation acquisition step of acquiring a correlation between a polishing pressure distribution in a radial direction between the polishing pads, a presence probability of the wafer at each position in the radial direction between the polishing pads, and a shape of the wafer after double-side polishing; a target shape acquisition step of acquiring a target shape of the wafer; and a condition determination process for determining conditions for the double-sided polishing of a wafer, based on the correlation, so as to obtain the polishing pressure distribution and the presence probability corresponding to the target shape.

2. 2. The method for determining conditions for double-sided polishing of a wafer according to claim 1, A method for determining conditions for double-sided polishing of a wafer, in which the condition determination process determines the conditions for the double-sided polishing under the premise that the polishing pressure distribution is set so that the polishing pressure in the radial middle region between the polishing pads is higher than the polishing pressure in the inner and outer edge regions.

3. 2. The method for determining conditions for double-sided polishing of a wafer according to claim 1, A method for determining conditions for double-sided polishing of a wafer, wherein the condition determination process determines at least one of the shapes of the upper and lower plates and the polishing surface shape of the polishing pad by dressing so that the polishing pressure distribution corresponds to the target shape.

4. 2. The method for determining conditions for double-sided polishing of a wafer according to claim 1, A method for determining conditions for double-sided polishing of a wafer, in which the condition determination process determines at least one of the rotation speed of the carrier and the distance from the center of the carrier to the center of the wafer so that the existence probability corresponds to the target shape.

5. 2. The method for determining conditions for double-sided polishing of a wafer according to claim 1, the correlation is a correlation between an expected value of a pressure received at a predetermined position of the wafer, which is obtained based on the polishing pressure distribution and the existence probability, and a shape of the wafer after double-side polishing, The method for determining conditions for double-sided polishing of a wafer, wherein the condition determination step determines conditions for the double-sided polishing so that the expected value of the pressure corresponds to the target shape.

6. 6. The method for determining conditions for double-sided polishing of a wafer according to claim 5, the correlation is a correlation between an expected value difference obtained by subtracting the expected value of the pressure applied to the outer edge portion of the wafer from the expected value of the pressure applied to the center of the wafer, and a shape of the wafer after double-side polishing; The method for determining conditions for double-sided polishing of a wafer, wherein the condition determination step determines conditions for the double-sided polishing so as to obtain the expected value difference corresponding to the target shape.

7. A step of determining conditions for double-sided polishing based on the method for determining conditions for double-sided polishing of a wafer according to any one of claims 1 to 6; a condition adjusting step of adjusting conditions for the double-side polishing based on the determined conditions; a polishing process step of polishing both sides of the wafer based on the adjusted conditions.

8. A method for manufacturing a wafer, comprising a step of polishing both sides of the wafer by the method for polishing both sides of the wafer according to claim 7.

Images