Method for evaluating semiconductor wafer and method for manufacturing semiconductor wafer

Abstract

To provide a new evaluation method capable of accurately evaluating the surface roughness of a semiconductor wafer.SOLUTION: A semiconductor wafer evaluation method includes obtaining the maximum height Sz and roughness parameters other than Sz by measuring with a roughness measuring device in one or more measurement areas on the surface of a semiconductor wafer to be evaluated, and determining whether the values of roughness parameters other than Sz obtained in the measurement area are values that can be adopted for evaluation of the semiconductor wafer to be evaluated for each measurement area using the value of the maximum height Sz as an index.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for evaluating a semiconductor wafer and a method for manufacturing a semiconductor wafer.

Background Art

[0002] In the manufacturing process of a semiconductor wafer (hereinafter, also simply referred to as "wafer"), usually, for quality control of products, inspections for process control and sampling inspections before shipment from a lot are performed. Examples of inspection items for such inspections include surface roughness (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A semiconductor wafer is generally manufactured by subjecting a wafer cut from an ingot to various processes such as surface polishing. By measuring the surface roughness of the semiconductor wafer thus manufactured, it is possible to evaluate, based on the measurement results, for example, whether the surface polishing process has been properly performed. And by performing process control of the surface polishing process based on the evaluation results and / or by discriminating between good lots and defective lots, it becomes possible to supply high-quality product wafers to the market. However, the measurement results of surface roughness may include various noises (see paragraph 0006 of Patent Document 1). In order to improve the accuracy of the evaluation based on the measurement results of surface roughness, it is desirable to obtain measurement results of surface roughness with reduced noise effects. In this regard, Patent Document 1 proposes a method in which the surface shape of a semiconductor wafer is measured under at least two different measurement conditions, the data of each surface shape is converted into a power spectrum, and among the peaks appearing in the power spectrum, those with inconsistent peak spatial frequencies are discriminated as noise components, and the discriminated noise components are removed from at least one of the power spectra before evaluation. However, the present inventor believes that with such a method, the noise that can be removed is limited to frequency-dependent noise (specifically, noise due to equipment factors), and noise due to disturbance factors, which is noise without frequency dependence, cannot be removed. However, from the viewpoint of more accurately evaluating the surface roughness of a semiconductor wafer, it is desirable to be able to reduce the influence of various noises.

[0005] In view of the above, one aspect of the present invention aims to provide a new evaluation method capable of accurately evaluating the surface roughness of a semiconductor wafer.

Means for Solving the Problems

[0006] One aspect of the present invention is as follows. [1] Obtaining the maximum height Sz and roughness parameters other than Sz by performing measurement with a roughness measuring device in one or more measurement regions on the surface of the semiconductor wafer to be evaluated, and For each measurement area, using the value of the maximum height Sz as an index, determine whether the values of roughness parameters other than Sz obtained in the measurement area are values that can be adopted for the evaluation of the semiconductor wafer to be evaluated. A method for evaluating a semiconductor wafer including (hereinafter, also simply referred to as "evaluation method"). [2] The semiconductor wafer evaluation method according to [1], including adopting, as values for evaluating the semiconductor wafer to be evaluated, the values of roughness parameters other than Sz obtained for one or more measurement areas where the maximum height Sz of the value was obtained, when the value of the maximum height Sz is less than or equal to a preset threshold value. [3] The semiconductor wafer evaluation method according to [1] or [2], wherein when the value of the maximum height Sz is greater than or equal to a preset threshold value or exceeds the threshold value, the values of roughness parameters other than Sz obtained for the measurement area where the maximum height Sz of the value was obtained are not adopted as values for evaluating the semiconductor wafer to be evaluated. [4] The semiconductor wafer evaluation method according to [3], further including, when the value of the maximum height Sz is greater than or equal to a preset threshold value or exceeds the threshold value, performing measurement again on the measurement area where the maximum height Sz of the value was obtained using a roughness measuring device. [5] The semiconductor wafer evaluation method according to [3] or [4], further including, when the value of the maximum height Sz is greater than or equal to a preset threshold value or exceeds the threshold value, performing measurement using a roughness measuring device on an area other than the measurement area where the maximum height Sz of the value was obtained. [6] The semiconductor wafer evaluation method according to any one of [3] to [5], further including, when the value of the maximum height Sz is greater than or equal to a preset threshold value or exceeds the threshold value, recalculating the values of one or more roughness parameters obtained for the measurement area where the maximum height Sz of the value was obtained. [7] The semiconductor wafer evaluation method according to [6], wherein the recalculation is performed by excluding from the calculation target of the roughness parameter the part estimated to be the cause of the abnormal value of the maximum height Sz. [8] The semiconductor wafer evaluation method according to any one of [1] to [7], wherein the roughness parameters other than Sz are one or more roughness parameters selected from the group consisting of the arithmetic mean height Sa and the root mean square height Sq. [9] The semiconductor wafer evaluation method according to any one of [1] to [8], wherein the roughness measuring device is an optical interference microscope.

[10] The semiconductor wafer evaluation method according to [9], wherein the optical interference microscope is a white light interference microscope.

[11] Manufacturing an evaluation semiconductor wafer under test manufacturing conditions, Evaluating the manufactured evaluation semiconductor wafer by the evaluation method according to any one of [1] to

[10] , Based on the result of the above evaluation, determining the manufacturing conditions obtained by changing the above test manufacturing conditions as the actual manufacturing conditions, or determining the above test manufacturing conditions as the actual manufacturing conditions, and, Manufacturing a semiconductor wafer under the determined actual manufacturing conditions, A semiconductor wafer manufacturing method including the above (hereinafter referred to as "manufacturing method 1").

[12] The semiconductor wafer manufacturing method according to

[11] , wherein the manufacturing conditions to which the above changes are applied include the surface polishing treatment conditions of the semiconductor wafer.

[13] Manufacturing a semiconductor wafer lot including a plurality of semiconductor wafers, Extracting one or more semiconductor wafers from the semiconductor wafer lot, Evaluating the extracted semiconductor wafer by the evaluation method according to any one of [1] to

[10] , and, Preparing for shipping as products the semiconductor wafers of the same semiconductor wafer lot as the semiconductor wafers determined to be non-defective as a result of the above evaluation, A semiconductor wafer manufacturing method including the above (hereinafter referred to as "manufacturing method 2").

Effect of the Invention

[0007] According to one aspect of the present invention, it is possible to provide a new evaluation method capable of accurately evaluating the surface roughness of a semiconductor wafer.

Brief Description of the Drawings

[0008]

Figure 1

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Figure 7

Mode for Carrying Out the Invention

[0009] [Method for Evaluating Semiconductor Wafer] One aspect of the present invention relates to a method for evaluating a semiconductor wafer, which includes obtaining the maximum height Sz and roughness parameters other than Sz by performing measurement with a roughness measuring device in one or more measurement regions on the surface of the semiconductor wafer to be evaluated, and for each measurement region, using the value of the maximum height Sz as an index to determine whether the value of the roughness parameter other than Sz obtained in this measurement region is a value that can be adopted for evaluating the semiconductor wafer to be evaluated (hereinafter, also simply referred to as "determination of adoptability").

[0010] One of the two surfaces of the semiconductor wafer is the surface (front surface) on the device formation surface side, and the other is the surface (back surface) on the side opposite to the front surface. In the present invention and this specification, the semiconductor wafer surface refers to either one or both of the front surface and the back surface.

[0011] In the present invention and this specification, for various roughness parameters, reference can be made to ISO 25178-2:2012 and the Japanese Industrial Standard JIS B0681-2:2018 corresponding to the above ISO. The maximum height Sz, which is one of the roughness parameters, is expressed as "Sz = Sp + Sv". Sp is the maximum peak height (the maximum value of the height from the average surface), and Sv is the maximum valley depth (the absolute value of the minimum value of the height from the average surface). Sz calculated as the sum of these can be said to be the distance from the highest point to the lowest point of the surface to be measured.

[0012] In the above evaluation method, in one or more measurement regions of the semiconductor wafer surface to be evaluated, by performing measurement with a roughness measuring device, for each measurement region, two or more roughness parameters including the maximum height Sz are obtained. Then, using the value of the maximum height Sz as an index, it is determined whether the values of the roughness parameters other than Sz obtained in each measurement region are values that can be adopted for the evaluation of the semiconductor wafer to be evaluated. In this regard, the present inventor speculates as follows. However, the present invention is not limited to the speculation of the present inventor. Since the maximum height Sz is the sum of the maximum peak height and the maximum valley depth as described above, the inventors consider that it is easily affected by noise due to device factors, and further, it is also easily affected by noise due to disturbance factors such as foreign matter adhesion. As an example, according to the inventors' study, when foreign matter with a size of 100 nm or more adheres within the measurement field of view, the values of other roughness parameters (for example, Sa and Sq described later) change only by about several to a dozen or so nm compared to normal times, while the value of Sz changes by 100 nm or more. Also, when sudden vibrations of the device occur, steps of 200 nm or more that usually do not exist on the wafer surface may occur. In such a case, the value of Sz becomes about 200 nm or 200 nm or more. For example, in the above cases, a threshold value can be set to, for example, 100 nm for the value of Sz, and based on the threshold value, it is possible to determine the presence or absence of the influence of noise. Specifically, it is possible to determine whether the measurement results of the roughness parameters acquired together with Sz include abnormal values due to noise, or whether the above measurement results are normal values that do not include or have little influence of noise. For example, in this way, for each measurement area where measurement is performed by the roughness measuring device, using the value of the maximum height Sz as an index, it is possible to determine whether the values of the roughness parameters other than Sz acquired in each measurement area are values that can be adopted for the evaluation of the semiconductor wafer to be evaluated. As a result, it becomes possible to use the values of the roughness parameters with reduced influence of noise for the evaluation of the semiconductor wafer. Hereinafter, the above evaluation method will be described in more detail.

[0013] <Semiconductor wafer to be evaluated> Examples of the semiconductor wafer to be evaluated in the above evaluation method include various semiconductor wafers such as silicon wafers (e.g., single crystal silicon wafers). In the present invention and this specification, unless otherwise specified, the silicon wafer refers to a single crystal silicon wafer. Further, as an example of the semiconductor wafer to be evaluated, a polished wafer can be mentioned. A polished wafer is a wafer in which one or both surfaces are polished surfaces, that is, surfaces subjected to surface polishing treatment. A polished wafer is usually manufactured through processes such as rough polishing, etching, and mirror polishing (i.e., finish polishing) in sequence and has a polished surface on the surface. The polished surface is usually a mirror surface. The surface polishing treatment can be DSP (double side polishing) or SSP (single side polishing). Also, the conductivity type of the semiconductor wafer to be evaluated is not limited and can be either n-type or p-type. Its dopant concentration (i.e., resistivity), oxygen concentration, etc. are also not limited. The diameter of the semiconductor wafer to be evaluated can be, for example, 200 mm, 300 mm, or 450 mm, but is not particularly limited.

[0014] <Measurement by a roughness measuring device> In the above evaluation method, measurements for obtaining roughness parameters are performed by a roughness measuring device in one or more measurement regions on the surface of the semiconductor wafer to be evaluated. The surface of the semiconductor wafer on which the measurement is performed can be, in one form, only one of the front surface or the back surface, or in another form, both the front surface and the back surface. In the measurement by the roughness measuring device in the above evaluation method, the total number of measurement regions per one surface of the front surface or the back surface is 1 or more, and can be 1 in one form or 2 or more in another form. Also, the above total number can be, for example, 50 or less, 40 or less, 30 or less, or 20 or less, or can exceed the values exemplified herein.

[0015] As the roughness measurement device, various roughness measurement devices capable of acquiring roughness parameters can be used. Specific examples of the roughness measurement device include an optical interference microscope, an atomic force microscope, a laser microscope, a Fizeau interferometer, etc. As an example, the optical interference microscope will be further described below. However, the roughness measurement device used in the above evaluation method is not limited to the optical interference microscope.

[0016] The optical interference microscope is a roughness measurement device that measures the unevenness of the surface of the measurement object by utilizing the interference of light. As the measurement method of the optical interference microscope, there are a vertical scanning type white light interference method and a phase shift interference method. The optical interference microscope of the vertical scanning type white light interference method is a white light interference microscope. More specifically, the white light interference microscope is a device that can perform three-dimensional measurement over a wide area and with high vertical resolution on the surface of the measurement object using white light as the light source.

[0017] Fig. 1 is an explanatory diagram showing the measurement principle of the white light interference microscope. As shown in Fig. 1(a), when the light from the white light source is split into two by a beam splitter, one is irradiated onto the reference mirror attached to the objective lens, and the other is irradiated onto the surface of the measurement object, these two lights are reflected and recombined again. It has a mechanism with a vertical scanning scanner attached to the objective lens. As shown in Fig. 1(b), by scanning the objective lens in the vertical direction and measuring the height at which the intensity of the generated interference fringes becomes maximum, height information can be obtained. In the example shown in Fig. 1(b), the difference in the peak positions of the interference intensities at point A and point B indicates the height difference. The interference of white light is the superposition of the interferences of lights of multiple wavelengths, and the peak position of the interference signal is the position where all the phases are aligned. Therefore, according to the white light interference microscope, high-precision height measurement is possible regardless of the observation magnification.

[0018] Figure 2 shows an example of the change in interference light during fringe scanning in measurement by a white light interference microscope. A vertical scanning scanner is attached to the objective lens of the white light interference microscope, for example, as shown in Fig. 1(a). As in the example shown in Fig. 1, height information is obtained by fringe scanning that measures the height at which the intensity of interference fringes (fringes) generated by scanning the objective lens in the vertical direction becomes maximum. The number of interference fringes is determined by the inclination angle of the surface to be measured, and the height difference between adjacent bright and dark parts of the fringes is about 140 nm, which is 1 / 4 of the central wavelength of the white light source. Among the interference signals of fringe scanning, the point where the intensity of the interference light is highest is called the zero-order interference, and the second-highest point is called the first-order interference. If there is no influence of noise, an interference waveform as shown in Fig. 2, for example, can be obtained. In Fig. 2, A corresponds to point A shown in Fig. 1(b), and B corresponds to point B shown in Fig. 1(b). On the other hand, for example, if sudden vibration of the apparatus occurs during fringe scanning, the interference waveform is disturbed, and the zero-order interference may not be detected at the location where the zero-order interference should originally be obtained. In such a case, the first-order interference or the second-order interference may become the highest interference intensity within that pixel and misrecognize the height information. Also, if sudden vibration of the apparatus occurs during measurement and the interference waveform is disturbed and the first-order interference is misrecognized as the zero-order interference, a step of about 280 nm, which is λ (560 nm) / 1 / 2 of the central wavelength of the white light, may be formed at that location. Fig. 3 is an example of the measurement result by a white light interference microscope image of the surface of a silicon wafer. Fig. 3(a) shows the white light interference microscope image, and Fig. 3(b) shows the height profile. In Fig. 3, it can be confirmed that there is a step of about 260 nm within the measurement field of view due to sudden vibration of the apparatus occurring during measurement. By using the maximum Height Sz as an index, for example, it can be determined that the influence of noise of the apparatus factor as described above is included in the measurement result obtained by the roughness measuring apparatus. This is because, as described above, the maximum Height Sz is the sum of the maximum peak height and the maximum valley depth, and it is considered that it is easily affected by noise of the apparatus factor. Furthermore, the maximum Height 1 / 2 which is about 280 nm of λ (560 nm) can be formed. Fig. 3 is an example of the measurement result by a white light interference microscope image of the surface of a silicon wafer. Fig. 3(a) shows the white light interference microscope image, and Fig. 3(b) shows the height profile. In Fig. 3, it can be confirmed that there is a step of about 260 nm within the measurement field of view due to sudden vibration of the apparatus occurring during measurement. Maximum Height By using Sz as an index, for example, it can be determined that the influence of noise of the apparatus factor as described above is included in the measurement result obtained by the roughness measuring apparatus. This is because, as described above, Height Sz is the sum of the maximum peak height and the maximum valley depth, and it is considered that it is easily affected by noise of the apparatus factor. Furthermore, the maximum HeightSz is considered to be easily affected by noise from disturbance factors such as foreign matter adhesion. Below, taking Figure 4 as an example, this point will be further explained.

[0019] Figure 4 is a white light interference microscope image of the surface of a silicon wafer where foreign matter with a height of about 200 nm exists within the field of view. Figure 4(a) is the overall image of the white light interference microscope, Figure 4(b) is the enlarged image of the foreign matter adhesion location, Figure 4(c) is the height profile of the foreign matter, and in the table shown in Figure 4(d), the roughness parameters calculated from the overall image shown in Figure 4(a) are described. When foreign matter, scratches, defects, etc. exist within the measurement field of view of the white light interference microscope, the values of the roughness parameters of the semiconductor wafer surface may shift due to such foreign matter, scratches, defects, etc. The values of Sa and Sq shown in the table of Figure 4(d) are slightly higher compared to the values of Sa and Sq of a general silicon wafer. Note that details of Sa and Sq will be described later. In contrast, the value of Sz shown in Figure 4(d) is affected by the foreign matter within the field of view and shows a value of 200 nm or more. Therefore, Sz to By using it as an index, it is possible to determine that the noise from disturbance factors such as foreign matter adhesion is included in the measurement results obtained by the roughness measurement device.

[0020] In the above, a white light interference microscope was used as an example of the roughness measurement device, and a silicon wafer was used as an example of the semiconductor wafer. However, as described above, the roughness measurement device used in the above evaluation method can also be a roughness measurement device other than a white light interference microscope, and the semiconductor wafer to be evaluated can also be a semiconductor wafer other than a silicon wafer.

[0021] <Judgment on the Adoptability of Roughness Parameters> In the above evaluation method, as described above, in one or more measurement regions, the maximum height Sz and roughness parameters other than Sz are obtained by measuring with a roughness measuring device. Then, for each measurement region, using the value of the maximum height Sz obtained for this measurement region as an index, it is determined whether the value of the roughness parameter other than Sz obtained in the same measurement region is a value that can be adopted for evaluating the semiconductor wafer to be evaluated. In the above evaluation method, the reason for adopting the maximum Height The details of the reason for adopting Sz are as described above. As specific forms of the determination of adoptability, for example, the following forms can be cited. The following various forms can also be arbitrarily combined.

[0022] (1) In one form, when the value of the maximum height Sz is less than or less than a preset threshold value, the value of the roughness parameter other than Sz obtained for one or more measurement regions where this value of the maximum height Sz was obtained is adopted as the value for evaluating the semiconductor wafer to be evaluated. That the value of the maximum height Sz is less than or less than a preset threshold value is also described as "no abnormality in Sz". The threshold value may be determined in consideration of, for example, the height of foreign matter that can adhere to the semiconductor wafer, the depth of defects or scratches that can occur on the semiconductor wafer, the magnitude of noise due to device factors that can occur during measurement, the quality required for the semiconductor wafer to be evaluated, etc. Whether to use less than the threshold value or less than the threshold value as the standard can be determined as appropriate. Also, as roughness parameters other than Sz, for example, one or more roughness parameters selected from the group consisting of the arithmetic mean height Sa and the root mean square height Sq can be cited. Only the arithmetic mean height Sa, only the root mean square height Sq, or both of these can be adopted as the value for evaluation. For the arithmetic mean height Sa and the root mean square height Sq, ISO 25178-2:2012 can be referred to as described above. The above points are the same for the various forms described later.

[0023] In this embodiment, when the total number of measurement regions is 1, the values of the roughness parameters other than Sz obtained for this one measurement region are adopted as the values for evaluating the semiconductor wafer to be evaluated. On the other hand, in this embodiment, when the total number of measurement regions is 2 or more, and the total number of measurement regions where the value of the maximum height Sz is less than or equal to a preset threshold value is 2 or more, the values of the roughness parameters other than Sz obtained for all of these 2 or more measurement regions can be adopted as the values for evaluating the semiconductor wafer to be evaluated, or the values of the roughness parameters other than Sz obtained for some regions can also be adopted as the values for evaluating the semiconductor wafer to be evaluated. When adopting the values of the roughness parameters other than Sz obtained for 2 or more measurement regions as the evaluation values, for example, it can be determined whether the semiconductor wafer to be evaluated is a semiconductor wafer having a desired quality (i.e., a good product) or a semiconductor wafer that does not meet the desired quality (i.e., a defective product) based on the arithmetic mean, maximum value, minimum value, etc. of the values obtained for a plurality of measurement regions. The threshold value for good product determination or defective product determination may be determined in consideration of the quality required for the semiconductor wafer to be evaluated and the like. The above points are the same for the various embodiments described below.

[0024] (2) In one embodiment, when the value of the maximum height Sz is greater than or equal to a preset threshold value or exceeds the threshold value, the value of the roughness parameter other than Sz obtained for the measurement region where this maximum height Sz value was obtained is not adopted as the value for evaluating the semiconductor wafer to be evaluated. The fact that the value of the maximum height Sz is greater than or equal to a preset threshold value or exceeds the threshold value is also described as "abnormal Sz". According to this embodiment, specifically, for the measurement region where the maximum height Sz is greater than or equal to a preset threshold value or exceeds the threshold value, it can be determined that the measurement result obtained in this measurement region includes abnormal values affected by noise and is not adopted as the value for evaluating the semiconductor wafer to be evaluated.

[0025] In this embodiment, in one aspect, for a measurement region in which a value of the maximum height Sz equal to or greater than a preset threshold value or exceeding the threshold value is obtained, measurement by the roughness measuring device can be performed again (hereinafter, also referred to as "re-measurement"). When there are two or more measurement regions in which a value of the maximum height Sz equal to or greater than a preset threshold value or exceeding the threshold value is obtained, re-measurement can be performed on some or all of them. For example, if the factor for which the value of the maximum height Sz in a certain measurement region is equal to or greater than a preset threshold value or exceeds the threshold value is a device factor such as vibration of the device during measurement, the measurement result obtained by re-measurement for this measurement region may not include abnormal values. Whether or not the measurement result of the re-measurement includes abnormal values can also be determined using the maximum Height Sz as an index. If the value of the maximum height Sz obtained by the re-measurement is less than or less than the preset threshold value, the values of the roughness parameters other than Sz obtained by the re-measurement can be adopted as the values for evaluating the semiconductor wafer to be evaluated. On the other hand, if, even by re-measurement, a value of the maximum height Sz equal to or greater than a preset threshold value or exceeding the threshold value is obtained, it can be finally determined that the values of the roughness parameters other than Sz obtained for that measurement region are not adopted as the values for evaluating the semiconductor wafer to be evaluated.

[0026] In addition, in one embodiment, when a value of the maximum height Sz equal to or greater than a preset threshold value or exceeding the threshold value is obtained, measurement by the roughness measuring device can be further performed in a region outside the measurement region where this value of the maximum height Sz was obtained. For example, if the measurement region in the first measurement contains a measurement region in which a value of the maximum height Sz equal to or greater than a preset threshold value or exceeding the threshold value was obtained, then as the second measurement, measurement by the roughness measuring device can be performed on one or more regions that were not measured in the first measurement. If the factor for which the maximum height Sz obtained in the first measurement for a certain measurement region is equal to or greater than the threshold value or exceeds the threshold value is a foreign object, scratch, defect, etc. present in this measurement region, then by changing the measurement region, there is a possibility of obtaining a measurement result that does not include the influence of these. In such a case, if the value of the maximum height Sz obtained by the measurement performed by changing the measurement region is equal to or less than the preset threshold value or less than the threshold value, then the value of the roughness parameter other than Sz obtained by this measurement can be adopted as the value for evaluating the semiconductor wafer to be evaluated. On the other hand, if a value of the maximum height Sz equal to or greater than a preset threshold value or exceeding the threshold value is obtained as the measurement result obtained by changing the measurement region, then it can be determined that the value of the roughness parameter other than Sz obtained for that measurement region is not adopted as the value for evaluating the semiconductor wafer to be evaluated, or re-measurement can also be performed for that measurement region. For the determination of the measurement result obtained by re-measurement, reference can be made to the previous description.

[0027] In addition, in one embodiment, when a value of the maximum height Sz equal to or greater than a preset threshold value or exceeding the threshold value is obtained, recalculation of the value of one or more roughness parameters obtained for the measurement region where this value of the maximum height Sz was obtained can be performed. The recalculation is based on the cause of the abnormal value of the maximum height Sz, that is, the maximum HeightThe part estimated to be the cause where Sz is equal to or exceeds the threshold can be excluded from the calculation target of the roughness parameter. For example, when the reason that the maximum height Sz obtained for a certain measurement area is equal to or exceeds the threshold is a foreign object, the part where the foreign object exists can be removed by image processing (for example, masking processing), or the measurement result of the part where the foreign object exists can be removed by data processing, and then the measurement result is recalculated to obtain a measurement result that does not include the influence of the foreign object or the influence of the foreign object is reduced. The object of recalculation is one or more roughness parameters, and the maximum Height It can be one or more surface parameters other than Sz. For example, the recalculation result thus obtained can be adopted as a value for evaluating the semiconductor wafer to be evaluated. Or, further, the maximum Height Sz may also be recalculated, and the recalculated maximum Height If Sz is less than or below the threshold, it can be determined that the value of the surface parameter other than the maximum Height Sz obtained by this recalculation is a value that can be adopted for evaluating the semiconductor wafer to be evaluated.

[0028] In the above evaluation method, as described above, as a result of determining whether it can be adopted, based on the value of the roughness parameter other than Sz determined to be adoptable, the semiconductor wafer to be evaluated can be evaluated. Such evaluation can be performed based on one or more of the values of the surface parameters other than Sz obtained for one measurement area, or can also be performed based on the arithmetic mean, maximum value, minimum value, etc. of the values obtained for a plurality of measurement areas. In any case, when the value of the surface parameter is less than or below the preset threshold, it can be determined that the semiconductor wafer to be evaluated is a semiconductor wafer having the desired quality (that is, a good product), and when it is equal to or exceeds the preset threshold, it can be determined that the semiconductor wafer to be evaluated is a semiconductor wafer that does not meet the desired quality (that is, a defective product). As described above, the threshold for determining a good product or a defective product may be determined in consideration of the quality required for the semiconductor wafer to be evaluated. Also, in one form, the maximum HeightThe value of Sz can also be used for determining the quality of the semiconductor wafer to be evaluated. Maximum Height According to Sz, it is possible to determine the presence or absence of local defects on the surface (front or back surface) of the semiconductor wafer, evaluate unevenness, etc.

[0029] [Manufacturing Method 1] Manufacturing Method 1 is manufacturing an evaluation semiconductor wafer under test manufacturing conditions, evaluating the manufactured evaluation semiconductor wafer by the above evaluation method, based on the result of the above evaluation, determining the manufacturing conditions obtained by changing the above test manufacturing conditions as the actual manufacturing conditions, or determining the above test manufacturing conditions as the actual manufacturing conditions, and manufacturing a semiconductor wafer under the determined actual manufacturing conditions, a manufacturing method of a semiconductor wafer including is.

[0030] In Manufacturing Method 1, as a preliminary step for determining actual manufacturing conditions, test manufacturing conditions are set, and an evaluation semiconductor wafer is manufactured under these test manufacturing conditions. The "actual manufacturing conditions" shall mean the manufacturing conditions for the product semiconductor wafer. The evaluation semiconductor wafer manufactured under the test manufacturing conditions is subjected to evaluation by the evaluation method described in detail above. There is at least one evaluation semiconductor wafer, and there may be two or more, and the number thereof is not particularly limited. If the evaluation result of the surface parameters (for example, the arithmetic mean height Sa and / or the root mean square height Sq described above) obtained for the evaluation semiconductor wafer is a value desired for the product semiconductor wafer, the product semiconductor wafer is manufactured and shipped using these test manufacturing conditions as the actual manufacturing conditions, thereby enabling stable supply to the market of product semiconductor wafers having the desired surface properties. On the other hand, if the evaluation result of the surface parameters obtained for the evaluation semiconductor wafer is different from the value desired for the product semiconductor wafer as a result of the evaluation, the manufacturing conditions obtained by changing the test manufacturing conditions are determined as the actual manufacturing conditions. As an example of the manufacturing process of a semiconductor wafer, for example, a polished wafer, which is a form of a silicon wafer, is manufactured by a manufacturing process including cutting (slicing) of a silicon wafer from a silicon single crystal ingot grown by the Czochralski method (CZ method) or the like, chamfering, rough polishing (for example, lapping), etching, mirror polishing (finish polishing), and cleaning performed between or after the above processing steps. For a silicon wafer or a semiconductor wafer other than a silicon wafer, the manufacturing conditions for making the above changes are preferably manufacturing conditions considered to affect the surface parameters. As an example of such manufacturing conditions, the polishing treatment conditions for the surface (front surface and / or back surface) of the semiconductor wafer can be mentioned. Specific examples of such surface polishing treatment conditions can include rough polishing conditions and mirror polishing conditions, and more specifically, the type of polishing liquid, the abrasive grain concentration of the polishing liquid, the type of polishing pad (for example, hardness, etc.) can be mentioned. In this way, the manufacturing conditions obtained by changing the test manufacturing conditions are determined as the actual manufacturing conditions, and by manufacturing and shipping the product semiconductor wafer under these actual manufacturing conditions, it is possible to stably supply to the market product semiconductor wafers having the desired surface properties.Note that the evaluation semiconductor wafer may be manufactured again under the manufacturing conditions with changes made to the test manufacturing conditions, and the evaluation semiconductor wafer may be evaluated by the above evaluation method, and it may be repeated one or more times to determine whether to use these manufacturing conditions as the actual manufacturing conditions or to make further changes. The threshold value for determining whether the evaluation result of the surface parameters obtained for the evaluation semiconductor wafer is a value desired for the product semiconductor wafer can be appropriately set according to market required quality and the like.

[0031] [Manufacturing Method 2] Manufacturing Method 2 is manufacturing a semiconductor wafer lot including a plurality of semiconductor wafers, extracting one or more semiconductor wafers from the semiconductor wafer lot, evaluating the extracted semiconductor wafers by the above evaluation method, and subjecting the semiconductor wafers of the same semiconductor wafer lot as the semiconductor wafers determined to be non-defective as a result of the above evaluation to preparations for shipping as products. A method for manufacturing a semiconductor wafer including is

[0032] In Manufacturing Method 2, so-called sampling inspection is performed, and as a result, the semiconductor wafers of the same lot as the semiconductor wafers determined to be non-defective are subjected to preparations for shipping as product semiconductor wafers. The manufacturing of the semiconductor wafer lot in Manufacturing Method 2 can be performed by adopting a general semiconductor wafer manufacturing process. As an example, reference can be made to the previous description regarding the manufacturing process of polished wafers.

[0033] The number of semiconductor wafers extracted from the manufactured semiconductor wafer lot and subjected to so-called sampling inspection is at least one, may be two or more, and the number is not particularly limited. The semiconductor wafers extracted from the semiconductor wafer lot are subjected to evaluation by the evaluation method described in detail above. As a result of the evaluation, the semiconductor wafers of the same semiconductor wafer lot as the semiconductor wafers determined to be non-defective are prepared for shipment as product semiconductor wafers. The criteria for determining non-defective products, specifically the threshold values of surface parameters (for example, the arithmetic mean height Sa and / or the root mean square height Sq described above), may be determined according to the quality required for the product semiconductor wafers. Examples of the preparation for shipment as product semiconductor wafers include packaging. Thus, according to Manufacturing Method 2, product semiconductor wafers having a desired surface property can be stably supplied to the market.

Example

[0034] The present invention will be further described below based on examples. However, the present invention is not limited to the embodiments shown in the examples.

[0035] [Semiconductor Wafer to be Evaluated] As the semiconductor wafers to be evaluated, 25 silicon wafers with a diameter of 300 mm were prepared. The above silicon wafers are polished wafers polished on both sides (DSP).

[0036] [Measurement by Roughness Measuring Device] For the back surface of each of the above silicon wafers, measurement was performed under the following measurement conditions.

[0037] [Measurement Conditions] Roughness measuring device: White interference microscope Measurement magnification: 10 times (field of view: 1.6 mm × 1.6 mm) Filter: Hi-pass Filter 80 μm (removing undulations with a spatial wavelength of 80 μm or more) Measurement area: For each silicon wafer, 9 regions within the wafer surface shown in Table 1

[0038]

Table 1

[0039] <Measurement flow> Figure 5 shows the measurement flow in this embodiment. The details of the measurement flow will be described below. The surface of the silicon wafer to be measured was subjected to image processing such as flattening processing on the microscope image obtained by measuring with a white light interference microscope. In the analysis unit of the white microscope, the microscope image after image processing was analyzed, and the roughness parameters Sa, Sq, and Sz were output for each of the nine points in the plane of each silicon wafer. Regarding the threshold value of Sz, in this embodiment, assuming that the height of foreign matter, the depth of defects or scratches causing noise is 50 nm or more, the threshold value of Sz was set to 50 nm. However, the threshold value may be any value that does not remove the surface shape of the wafer. For example, if the wafer surface is a smooth surface, it can be said that values such as 10 nm or 20 nm are appropriate as the threshold value. In this embodiment, if the value of Sz is 50 nm or more, it is determined that "there is an Sz abnormality", and if it is less than 50 nm, it is determined that "there is no Sz abnormality". For each of the nine measurement regions of each silicon wafer, if there is no Sz abnormality, it is determined that Sa and Sq in that measurement region can be adopted for wafer evaluation. On the other hand, in the case of an Sz abnormality, it is determined that further processing is required, and one or more processes of remeasurement, measurement in other measurement regions, and recalculation can be performed. The details of these processes are as described above.

[0040] Figure 6 shows an example of the evaluation results obtained in this embodiment. In Figure 6, image A is an image determined to be "no Sz abnormality" where the value of Sz is less than the threshold value. In image A, steps, foreign matters, defects, etc. that may become noise in roughness parameter measurement are not confirmed. On the other hand, Image B, Image C, and Image D are images determined to have "abnormal Sz" where the value of Sz is equal to or greater than the threshold value. In Image B, a step suspected to be a vibration factor of the device is observed. In Image C, foreign matter adhesion is observed. In Image D, pit-type defects are observed. From the above results, it can be confirmed that by using the value of Sz as an index, it is possible to determine whether the result of the roughness parameter measurement is affected by noise.

[0041] In this embodiment, since the number of measurement regions for each of the 25 silicon wafers was 9, a total of 225 images were obtained by measurement with a white light interference microscope. As a result of determining the presence or absence of abnormal Sz among the 225 images, 216 images were determined to have "no abnormal Sz" and 9 images were determined to have "abnormal Sz". Table 2 shows the arithmetic mean and standard deviation of the Sq values of the 225 images, as well as the arithmetic mean and standard deviation of the Sq values of the 216 images determined to have no abnormal Sz.

[0042]

Table 2

[0043] In Fig. 7, the arithmetic mean of the Sq values (described as "Sq arithmetic mean") obtained for each of the 25 silicon wafers is plotted. Regarding the double-sided polishing applied to the silicon wafers evaluated in this embodiment, the normal value of Sq of the polished surface after double-sided polishing is about 0.2 nm. In Fig. 7, on the left side, the Sq arithmetic means obtained for 9 in-plane measurement regions for each of the 25 silicon wafers are plotted. The plot on the left side in Fig. 7 also includes plots where the arithmetic mean of the Sq values is 1 nm or more. In Fig. 7, on the right side, the Sq arithmetic means obtained by excluding the images determined to have abnormal Sz are plotted. All of the plots on the right side in Fig. 7 have an Sq arithmetic mean of around 0.2 nm.

[0044] From the results shown in Table 2 and FIG. 7, it can be confirmed that by using the value of Sz as an index, it is possible to accurately evaluate the surface roughness of the semiconductor wafer.

Industrial Applicability

[0045] One aspect of the present invention is useful in the field of manufacturing various semiconductor wafers such as silicon wafers.

Claims

1. In one or more measurement regions on the surface of a semiconductor wafer to be evaluated, obtaining a maximum height Sz and roughness parameters other than Sz by performing measurement with a roughness measuring device; and For each measurement region, determining, using the value of the maximum height Sz as an index, whether the value of the roughness parameter other than Sz obtained in the measurement region is a value that can be adopted for the evaluation of the semiconductor wafer to be evaluated. A method for evaluating a semiconductor wafer, comprising the above steps.

2. The method for evaluating a semiconductor wafer according to claim 1, including adopting, as a value for evaluating the semiconductor wafer to be evaluated, the value of the roughness parameter other than Sz obtained for one or more measurement regions where the value of the maximum height Sz was obtained, when the value of the maximum height Sz is less than or equal to a preset threshold value.

3. The method for evaluating a semiconductor wafer according to claim 1, wherein when the value of the maximum height Sz is greater than or equal to a preset threshold value or exceeds the threshold value, the value of the roughness parameter other than Sz obtained for the measurement region where the value of the maximum height Sz was obtained is not adopted as a value for evaluating the semiconductor wafer to be evaluated.

4. The method for evaluating a semiconductor wafer according to claim 3, further including performing measurement again with a roughness measuring device on the measurement region where the value of the maximum height Sz was obtained, when the value of the maximum height Sz is greater than or equal to a preset threshold value or exceeds the threshold value.

5. The method for evaluating a semiconductor wafer according to claim 3, further including performing measurement with a roughness measuring device on a region other than the measurement region where the value of the maximum height Sz was obtained, when the value of the maximum height Sz is greater than or equal to a preset threshold value or exceeds the threshold value.

6. The method for evaluating a semiconductor wafer according to claim 3, further including recalculating the value of one or more roughness parameters obtained for the measurement region where the value of the maximum height Sz was obtained, when the value of the maximum height Sz is greater than or equal to a preset threshold value or exceeds the threshold value.

7. The method for evaluating a semiconductor wafer according to claim 6, wherein the recalculation is performed by excluding from the calculation target of the roughness parameter the portion presumed to be the cause of the abnormal value of the maximum height Sz.

8. The method for evaluating a semiconductor wafer according to claim 1, wherein the roughness parameter other than Sz is one or more roughness parameters selected from the group consisting of an arithmetic mean height Sa and a root mean square height Sq.

9. The roughness measuring device is an optical interference microscope, and the method for evaluating a semiconductor wafer according to claim 1.

10. The optical interference microscope is a white light interference microscope, and the method for evaluating a semiconductor wafer according to claim 9.

11. Manufacturing an evaluation semiconductor wafer under test manufacturing conditions, Evaluating the manufactured evaluation semiconductor wafer by the evaluation method according to any one of claims 1 to 10, Based on the result of the evaluation, determining the manufacturing conditions obtained by changing the test manufacturing conditions as the actual manufacturing conditions, or determining the test manufacturing conditions as the actual manufacturing conditions, and Manufacturing a semiconductor wafer under the determined actual manufacturing conditions, A method for manufacturing a semiconductor wafer including the above.

12. The manufacturing conditions to which the change is applied include the surface polishing treatment conditions of the semiconductor wafer, and the method for manufacturing a semiconductor wafer according to claim 11.

13. Manufacturing a semiconductor wafer lot including a plurality of semiconductor wafers, Extracting one or more semiconductor wafers from the semiconductor wafer lot, Evaluating the extracted semiconductor wafer by the evaluation method according to any one of claims 1 to 10, and Preparing for shipping as a product the semiconductor wafers of the same semiconductor wafer lot as the semiconductor wafers determined to be non-defective based on the result of the evaluation, A method for manufacturing a semiconductor wafer including the above.

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