Method for evaluating semiconductor wafer and method for manufacturing semiconductor wafer

Abstract

To provide a new evaluation method capable of evaluating a defect due to minute treatment generated on a semiconductor wafer surface due to treatment executed in a manufacturing process.SOLUTION: An evaluation method of a semiconductor wafer includes performing plural times of surface treatment to a surface of a semiconductor wafer. The surface treatment includes the step of supplying a hydrofluoric acid to the surface of the semiconductor wafer and supplying ozone water to the surface of the semiconductor wafer after supply of the hydrofluoric acid, or the step of supplying the ozone water to the surface of the semiconductor wafer and supplying the hydrofluoric acid to the surface of the semiconductor wafer after supply of the ozone water. The method further includes the step of performing surface inspection of inspecting the surface of the semiconductor wafer by a surface defect inspection device before performing the surface treatment, after each surface treatment and after the plural times of surface treatment are finished. An LPD detected for the first time in the surface inspection after n-th surface treatment at a coordinate point at which the LPD is not detected in the surface treatment before performing the surface treatment is classified as a defect due to treatment. The above-mentioned n is an integer number equal to or greater than 1 and equal to or less than (N-1) when the total number of times of the surface treatment is N. The method calculates an assumed size of the defect due to treatment existing on the surface of the semiconductor wafer before the surface treatment is performed at the coordinate point at which the defect due to treatment is detected by means of regression analysis with a detection size of the LPD detected in the surface inspection after the plural times of the surface treatment are finished as a target variable and the total number of times (N-n) of the surface treatment performed after the first detection as an explanatory variable.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] As a method for evaluating defects in a semiconductor wafer, a method based on light points (LPD: Light Point Defect) detected by a surface defect inspection apparatus is widely used (see, for example, Patent Documents 1 to 3). According to this method, by irradiating light onto the surface of the semiconductor wafer to be evaluated and detecting the emitted light (scattered light or reflected light) from this surface, the presence or absence and size of defects on the surface of the semiconductor wafer can be evaluated.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] On the surface of a semiconductor wafer, there may be process-induced defects generated due to the processing operations performed in the manufacturing process. Among these process-induced defects, there may be minute process-induced defects that are smaller than the detection limit size of the surface defect inspection apparatus. For example, with conventional evaluation methods such as those described in Patent Documents 1 to 3, it is difficult to detect such minute process-induced defects. However, if it becomes possible to obtain information regarding such minute process-induced defects, for example, based on such information, by changing the manufacturing conditions of the semiconductor wafer so that the generation of minute process-induced defects is suppressed, it becomes possible to manufacture a high-quality semiconductor wafer with fewer minute process-induced defects.

[0005] One aspect of the present invention aims to provide a new evaluation method capable of evaluating minute process-induced defects generated on the surface of a semiconductor wafer due to the processing operations performed in the manufacturing process.

Means for Solving the Problems

[0006] One aspect of the present invention is as follows. [1] An evaluation method for a semiconductor wafer (hereinafter, also referred to as a "wafer"), comprising: performing a plurality of surface treatments on the surface of the semiconductor wafer, wherein the surface treatment includes supplying hydrofluoric acid to the surface of the semiconductor wafer and then supplying ozone water to the surface of the semiconductor wafer after the supply of the hydrofluoric acid, or includes supplying ozone water to the surface of the semiconductor wafer and then supplying hydrofluoric acid to the surface of the semiconductor wafer after the supply of the ozone water, further comprising performing a surface inspection of inspecting the surface of the semiconductor wafer with a surface defect inspection apparatus before performing the surface treatment, after each surface treatment, and after the plurality of surface treatments are completed, classifying, as a process-induced defect, an LPD first detected in the surface inspection after the nth surface treatment at a coordinate point where no LPD was detected in the surface inspection before performing the surface treatment. The above-mentioned n is an integer of 1 or more and (N - 1) or less, where N is the total number of times of the above-mentioned surface treatment. At the coordinate point where the above-mentioned processing-induced defect is detected, taking the assumed size of the above-mentioned processing-induced defect existing on the surface of the semiconductor wafer before the above-mentioned surface treatment as the target variable and the total number of times of surface treatment (N - n) performed after the first detection as the explanatory variable, calculate by regression analysis. Method for evaluating a semiconductor wafer. [2] The above-mentioned surface treatment includes supplying ozone water to the surface of the above-mentioned semiconductor wafer, supplying hydrofluoric acid to the surface of the above-mentioned semiconductor wafer after the supply of this ozone water, and supplying ozone water to the surface of the above-mentioned semiconductor wafer after the supply of this hydrofluoric acid. The method for evaluating a semiconductor wafer according to [1]. [3] For the above-mentioned regression analysis, with the above-mentioned target variable as y and the above-mentioned explanatory variable as x, the following regression equation: y = ax + b Perform according to In the above-mentioned regression equation, a is the slope obtained by the above-mentioned regression analysis, and b is the intercept obtained by the above-mentioned regression analysis. At the coordinate point where the above-mentioned processing-induced defect is detected, obtain the assumed size of the above-mentioned processing-induced defect existing on the surface of the semiconductor wafer before the above-mentioned surface treatment as the above-mentioned b. The method for evaluating a semiconductor wafer according to [1] or [2]. [4] The above-mentioned ozone water is ozone water with an ozone concentration of 20 ppm or more and 30 ppm or less based on mass. The method for evaluating a semiconductor wafer according to any one of [1] to [3]. [5] The above-mentioned hydrofluoric acid is hydrofluoric acid with a hydrogen fluoride concentration of 0.1 mass% or more and 1.0 mass% or less. The method for evaluating a semiconductor wafer according to any one of [1] to [4]. [6] The supply time of the above-mentioned hydrofluoric acid is 20 seconds or less. The method for evaluating a semiconductor wafer according to any one of [1] to [5]. [7] Manufacturing a semiconductor wafer under the manufacturing conditions of the evaluation target. Evaluating the manufactured semiconductor wafer by the method for evaluating a semiconductor wafer according to any one of [1] to [6]. Based on the results of the above evaluation, determine the manufacturing conditions obtained by changing the manufacturing conditions of the object to be evaluated as the subsequent manufacturing conditions, or determine the manufacturing conditions that continue to employ the manufacturing conditions of the object to be evaluated, and manufacture a semiconductor wafer under the determined manufacturing conditions, A method for manufacturing a semiconductor wafer including the above. [8] The manufacturing method of the semiconductor wafer according to [7], wherein the manufacturing conditions to which the above changes are applied are polishing treatment conditions on the surface of the semiconductor wafer.

Effect of the Invention

[0007] According to one aspect of the present invention, it becomes possible to evaluate minute process-induced defects generated on the surface of a semiconductor wafer due to a processing treatment performed in a manufacturing process.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

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Figure 6

[0009] [Method for Evaluating Semiconductor Wafer] One aspect of the present invention is a method for evaluating a semiconductor wafer, including performing surface treatment on the surface of the semiconductor wafer a plurality of times. The surface treatment includes supplying hydrofluoric acid to the surface of the semiconductor wafer and supplying ozone water to the surface of the semiconductor wafer after the supply of the hydrofluoric acid, or supplying ozone water to the surface of the semiconductor wafer and supplying hydrofluoric acid to the surface of the semiconductor wafer after the supply of the ozone water. Before performing the surface treatment, after each surface treatment, and after the plurality of surface treatments are completed, surface inspection is further performed to inspect the surface of the semiconductor wafer with a surface defect inspection device. In the surface inspection before performing the surface treatment, the LPD first detected in the surface inspection after the nth surface treatment at the coordinate point where no LPD was detected is classified as a process-induced defect. Here, n is an integer of 1 or more and (N - 1) or less, where N is the total number of times of the surface treatment. At the coordinate point where the process-induced defect is detected, the assumed size of the process-induced defect existing on the surface of the semiconductor wafer before the surface treatment is performed is calculated by regression analysis using the detection size of the LPD detected in the surface inspection after the plurality of surface treatments are completed as the target variable and the total number of surface treatments (N - n) performed after the first detection as the explanatory variable. A method for evaluating a semiconductor wafer. Regarding. Hereinafter, the above evaluation method will be described in more detail.

[0010] [Semiconductor Wafer to be Evaluated] The semiconductor wafer evaluated by the above evaluation method can generally be various semiconductor wafers used as semiconductor substrates. For example, specific examples of semiconductor wafers can include various silicon wafers. The silicon wafer can be, for example, a single-crystal silicon wafer that has undergone various processing steps after being cut from a silicon single-crystal ingot, such as a polished wafer having a polished surface after being polished. The diameter of the semiconductor wafer to be evaluated is, for example, 200 mm or less, 200 mm or more (for example, 200 mm, 300 mm, or 450 mm), but is not particularly limited.

[0011] <Surface inspection by a surface defect inspection device> As the surface defect inspection device, a known surface defect inspection device capable of irradiating light onto the surface of a semiconductor wafer and detecting the emitted light (scattered light or reflected light) from this surface can be used. Such a surface defect inspection device is generally also called a light scattering type surface defect inspection device, a surface inspection machine, etc. As a specific example of the surface defect inspection device, a laser surface defect inspection device can be cited. The laser surface defect inspection device usually scans the surface to be evaluated of the semiconductor wafer with laser light, and detects processing-induced defects and adhered particles on the surface to be evaluated of the wafer as bright spots (LPD) by the emitted light (scattered light or reflected light). Further, by measuring the emitted light from the LPD, the position (specifically, coordinate points) of the processing-induced defects and adhered particles on the surface to be evaluated of the semiconductor wafer and the size detected as the LPD can be obtained. Such an LPD detection size is usually output by the analysis unit of the surface defect inspection device by comparing the intensity of the emitted light from the LPD with the intensity of the emitted light of standard particles such as silica particles. As the laser light, ultraviolet light, visible light, etc. can be used, and its wavelength is not particularly limited. Ultraviolet light refers to light in the wavelength range of less than 400 nm, and visible light refers to light in the wavelength range of 400 to 600 nm. The analysis unit of the laser surface defect inspection device usually acquires information on the two-dimensional position coordinates (X coordinate and Y coordinate) on the surface to be evaluated for each of the plurality of detected LPDs, and can create an LPD map showing the in-plane distribution state of the LPDs on the surface to be evaluated from the acquired information on the two-dimensional position coordinates. Specific examples of commercially available laser surface defect inspection devices include Surfscan series SP1, SP2, SP3, SP5, SP7, etc. manufactured by KLA TENCOR Corporation. However, these devices are examples, and various other surface defect inspection devices can also be used.

[0012] As described above, it is difficult to evaluate micro-processing-induced defects that are smaller than the detection limit size of the surface defect inspection device by normal surface inspection using the surface defect inspection device. In contrast, according to the above evaluation method, it becomes possible to evaluate such micro-processing-induced defects by going through the following steps.

[0013] <Process Flow> Figure 1 shows the process flow in the above evaluation method. Hereinafter, various processes in the above evaluation method will be described along the process flow shown in Figure 1.

[0014] (Surface inspection before surface treatment, repetition of surface treatment and surface inspection) In the above evaluation method, the surface of the semiconductor wafer to be evaluated is subjected to surface treatment multiple times (repetition of S2 in Figure 1). Before the multiple surface treatments are performed, a surface inspection of the surface of the semiconductor wafer to be evaluated (evaluation target surface) is carried out (S1 in Figure 1).

[0015] Thereafter, the first surface treatment is performed on the evaluation target surface (S2 in Figure 1), and a surface inspection of the evaluation target surface is carried out after this surface treatment (S3 in Figure 1). Thereafter, the surface treatment and the surface inspection after the surface treatment are performed multiple times.

[0016] In one embodiment, in the first surface treatment and each subsequent surface treatment, hydrofluoric acid is supplied to the evaluation target surface (hereinafter, also referred to as the "hydrofluoric acid supply step"), and ozone water is supplied to the evaluation target surface after the supply of this hydrofluoric acid (hereinafter, also referred to as the "ozone water supply step for passivation"). This embodiment is described as "Method 1". In Method 1, further, before the hydrofluoric acid supply step, ozone water can be supplied to the evaluation target surface (hereinafter, also referred to as the "ozone water supply step for oxide film formation"). The implementation of the ozone water supply step for oxide film formation is optional, but it is preferably implemented. The reason for preference will be described later. Also, in another embodiment, in the first surface treatment and each subsequent surface treatment, ozone water is supplied to the evaluation target surface (hereinafter, also referred to as the "ozone water supply step for oxide film formation"), and hydrofluoric acid is supplied to the evaluation target surface after the supply of this ozone water (hereinafter, also referred to as the "hydrofluoric acid supply step"). This embodiment is described as "Method 2". Details of the surface treatment of Method 1 and Method 2 will be described later. Also, usually, after each surface treatment, a drying treatment can be performed on the evaluation target surface by a known method, and then a surface inspection can be carried out.

[0017] On the surface of a semiconductor wafer, as defects, there may exist simply adhering particles attached to the surface and defects generated due to the processing performed in the manufacturing process as described above. By the first surface treatment, usually, the adhering particles on the surface to be evaluated are removed. Therefore, if the LPD detected in the surface inspection before the surface treatment is not detected in the surface inspection after the first surface treatment at the coordinate point where the LPD was detected, the LPD can be presumed to be the LPD due to adhering particles. The defects that were not detected as LPD after the first surface treatment are hereinafter referred to as "vanishing defects". On the other hand, the LPD detected in the surface inspection before the surface treatment may be detected also in the surface inspection after the first surface treatment and further in the surface inspections after the subsequent repeated surface treatments at the coordinate point where the LPD was detected. Such an LPD can be presumed to be the LPD due to processing-induced defects larger than the detection limit size of the surface defect inspection apparatus. Such processing-induced defects are hereinafter referred to as "fixed defects". On the other hand, the processing-induced defects can be made apparent by the above surface treatment. Therefore, minute processing-induced defects that were not detected as LPD in the surface inspection before the surface treatment because they are smaller than the detection limit size of the surface defect inspection apparatus can be detected as LPD in the surface inspection after the first or second and subsequent surface treatments. Such minute processing-induced defects are hereinafter referred to as "increasing defects". Details of the above manifestation will be described later.

[0018] Fig. 2 shows a schematic diagram of a specific example of the in-plane distribution of LPD on the wafer surface before and after repeated surface treatments. In Fig. 2, both the upper figure and the lower figure include vanishing defects, fixed defects, and increasing defects. From the position information (coordinate information) of the LPD before and after the surface treatment as shown in Fig. 2, the vanishing defects existing only before the surface treatment are adhering particles, the fixed defects existing at the same position before and after the surface treatment are large-size processing-induced defects with a size equal to or larger than the detection limit size of the surface defect inspection apparatus, Increases in defects that did not exist before the surface treatment and only exist after the n-th surface treatment and later are defects caused by microfabrication that became apparent due to the n surface treatments. It can be presumed that. In the case where the increased defect becomes a disappearing defect due to the next surface treatment, it is preferably excluded as an attached particle. Here, "n" is an integer of 1 or more and (N - 1) or less, where N is the total number of surface treatments.

[0019] Next, the above-mentioned manifestation will be described in more detail. Figure 3 is an explanatory diagram of the manifestation of defects caused by microfabrication due to the surface treatment of Method 1 described above. Defects caused by microfabrication can be, for example, convex defects as schematically shown in Figure 3(a). Specific examples of such convex defects include PID (Polished Induced Defect). PID is a convex defect introduced on the surface of a semiconductor wafer during the polishing process. When ozone water is supplied to the surface of a wafer having defects caused by microfabrication (ozone water supply step for oxide film formation), the surface layer of the wafer is oxidized by the ozone water, and an oxide film is formed (Figure 3(b)). Note that a natural oxide film is usually formed on the surface to be evaluated before the hydrofluoric acid supply step is performed in the first surface treatment and subsequent surface treatments. Therefore, the implementation of the ozone water supply step for oxide film formation is optional, but it is preferably implemented. The reason for preferably implementing the ozone water supply step for oxide film formation will be described later. Preferably, after performing the ozone water supply step for oxide film formation, when hydrofluoric acid is supplied to the surface of the wafer (hydrofluoric acid supply step), at least a part of the oxide film on the surface of the wafer is removed (so-called etching) (Figure 3(c)). As a result, the size of the defects caused by microfabrication can be increased (i.e., manifested). In order to manifest the defects caused by microfabrication, it is preferable to perform the hydrofluoric acid supply step so that the oxide film on the surface of the wafer is not completely peeled off and a part of it remains. The hydrofluoric acid supply step will be described later. The subsequent supply of ozone water (ozone water supply process for passivation) is a treatment (so-called passivation treatment) for suppressing contamination of the wafer surface by organic substances or the like by inactivating the wafer surface after the hydrofluoric acid supply process. By the ozone water supply process for passivation, the surface layer portion of the wafer after the hydrofluoric acid supply process can be oxidized to form an oxide film (Fig. 3(d)), whereby the wafer surface can be inactivated. However, it is not essential to inactivate the wafer surface after the hydrofluoric acid supply process. Therefore, when performing the surface treatment of Method 2 described above, after performing the ozone water supply process for forming an oxide film and then the hydrofluoric acid supply process, surface inspection can be performed without performing the ozone water supply process for passivation.

[0020] (Calculation of the assumed size of defects caused by microfabrication by regression analysis) Since the size of the defects caused by the above microfabrication is below the detection limit size of the surface defect inspection apparatus used for surface inspection, as a result of the surface inspection before surface treatment, the LPD detection size of the above defects caused by microfabrication cannot be obtained.

[0021] On the other hand, the inventor has found through repeated studies that the amount of change in the size of defects caused by processing in each surface treatment of multiple surface treatments can be regarded as constant. Fig. 4 is a graph showing the relationship between the LPD detection size of each defect and the number of surface treatments in an example where, after performing a surface inspection before surface treatment on the surface of a silicon wafer (polished wafer), the surface treatment and surface inspection are repeated a total of 6 times, and 5 defects (Defect 1 to Defect 5) detected as LPDs in the surface inspection before surface treatment are randomly selected. The 6 surface treatments were each performed under the same surface treatment conditions. From Fig. 4, it can be confirmed that the amount of change in the size of defects caused by processing in each surface treatment of multiple surface treatments can be regarded as constant.

[0022] As a result of further intensive studies by the present inventors, on the premise that the amount of change in the size of defects caused by microfabrication in each surface treatment of multiple surface treatments is constant, it has been newly found that for defects caused by microfabrication, the size that would be detected by a surface defect inspection apparatus with a smaller detection limit size can be calculated by regression analysis as follows. First, at the coordinate points where LPD was not detected in the surface inspection before the above-mentioned surface treatment, the LPD first detected in the surface inspection after the n-th (n is an integer of 1 or more and (N - 1) or less as described above) surface treatment is classified as a defect caused by processing (specifically, the above-mentioned defect caused by microfabrication). At the coordinate points where this defect caused by microfabrication is detected, the assumed size of the defect caused by microfabrication existing on the surface of the semiconductor wafer before the above-mentioned surface treatment is calculated by regression analysis using the detection size of LPD in the surface inspection after multiple surface treatments as the objective variable and the total number of surface treatments (N - n) performed after the first detection as the explanatory variable.

[0023] A specific example is shown below to explain the above-mentioned calculation process in more detail.

[0024] As a sample semiconductor wafer, a polished wafer (single crystal silicon wafer) with a diameter of 300 mm was used for evaluation. FIG. 5 is a graph showing the relationship between the total number of surface treatments performed after the first detection and the LPD detection size in the surface inspection after the final surface treatment for the LPD first detected in the surface inspection after the n-th surface treatment after performing surface treatment and surface inspection repeatedly on the surface of the above-mentioned sample wafer. As the surface defect inspection apparatus, SP7 of the Surfscan series (laser surface defect inspection apparatus) manufactured by KLA TENCOR was used, and as the measurement mode, High Sensitivity Oblique Mode (HSO Mode) was used. Each channel of the HSO Mode has the following sensitivity. DW1O (Dark-Field Wide1 Oblique) channel: 15 nm DW2O (Dark-Field Wide2 Oblique) channel: 25 nm DNO (Dark-Field Narrow Oblique) channel: 31 nm Among the above channels, the most sensitive channel is DW1O. DW1O is highly sensitive to Particles. On the other hand, DW2O and DNO are highly sensitive to processing-induced defects. In the example shown in FIG. 5, the total number of surface treatments is six (N = 6). Therefore, for example, the plot on the horizontal axis of "1 time" in FIG. 5 is the plot regarding the LPD that was first detected in the surface inspection after the fifth surface treatment, and then one more time (6 times - 5 times) of surface treatment was performed on it. The plot with the horizontal axis of "2 times" is the plot regarding the LPD that was first detected in the surface inspection after the fourth surface treatment, and then two more times (6 times - 4 times) of surface treatment were performed on it. The same applies to the plots with the horizontal axes of "3 times", "4 times", and "5 times". FIG. 5 shows a straight line obtained by linearly approximating the average values for each of the horizontal axes from 1 time to 5 times. From the results shown in FIG. 5, it can be confirmed that the smaller the number of surface treatments when the LPD is first detected, the larger the LPD detection size in the surface inspection after the final surface treatment tends to be. From this result, it can be said that the defects caused by microfabrication tend to become apparent earlier with a smaller number of surface treatments and the final LPD detection size also becomes larger as the size on the wafer surface before the surface treatment is larger. Furthermore, by statistically calculating the amount of change, it becomes possible to estimate the amount of size change due to one surface treatment. For example, taking the LPD detection size in the surface inspection after the final (the sixth time in the example shown in FIG. 5) surface treatment, that is, after the completion of multiple surface treatments, as the objective variable, and the total number of surface treatments (N - n) performed after the first detection as the explanatory variable, if the linear equation of the approximate straight line shown in FIG. 5 is set as the regression equation "y = ax + b", the slope a and the intercept b can be obtained by simple regression analysis. The assumed size of the defect caused by microfabrication that existed on the surface of the semiconductor wafer before the above-mentioned surface treatment at the coordinate point where the defect caused by microfabrication was detected can be calculated as the above-mentioned b, for example. For example, by creating a regression equation in advance for each surface treatment condition, then, when performing surface treatment under that surface treatment condition, using the pre-created regression equation, taking the LPD detection size in the surface inspection after the completion of multiple surface treatments as the objective variable, and the total number of surface treatments (N - n) performed after the first detection as the explanatory variable, it can be calculated by regression analysis.

[0025] Fig. 6 shows the LPD detection size before surface treatment of the LPD detected as a fixed defect in the example shown in Fig. 5 (right figure), and the assumed size calculated at the coordinate point where an increasing defect was detected (left figure). From Fig. 6, it can be confirmed that by the above evaluation method, it is possible to detect, with a surface defect inspection apparatus, minute processing-induced defects with an LPD detection size of 25 nm or less that cannot normally be detected by the surface defect inspection apparatus used in the example shown in Fig. 5, and that the assumed size could be calculated by the method described above.

[0026] <Surface treatment> As described above, in the surface treatment performed multiple times in the above evaluation method, the surface treatment of the above method 1 or the above method 2 is performed. The multiple surface treatments are preferably performed under the same surface treatment conditions. Here, regarding the "same surface treatment conditions", fluctuations in conditions that may inevitably occur during the preparation of the chemical solution for surface treatment and during surface treatment are allowed.

[0027] The total number N of surface treatments performed multiple times is 2 or more, and can be 3 or more, 4 or more, or 5 or more. Also, N can be, for example, 10 or less, 9 or less, 8 or less, 7 or less, or 6 or less. However, since more minute processing-induced defects can be made apparent as the number of surface treatments increases, the number of surface treatments is not limited to the numbers exemplified here, and more surface treatments can also be performed.

[0028] As the ozone water, for example, ozone water with an ozone concentration of 20 ppm or more and 30 ppm or less based on mass can be used. As the hydrofluoric acid, for example, hydrofluoric acid with a hydrogen fluoride concentration of 0.1 mass% or more and 1.0 mass% or less can be used. The supply of ozone water and the supply of hydrofluoric acid to the surface to be evaluated can be performed in the same manner as the cleaning treatment usually performed on a semiconductor wafer. In the examples shown in Figs. 4 and 5, ozone water with an ozone concentration of 25 ppm based on mass and hydrofluoric acid with a hydrogen fluoride concentration of 1.0 mass% were used, and an ozone water supply step for oxide film formation, a hydrofluoric acid supply step, and an ozone water supply step for passivation were performed in the same manner as the cleaning treatment usually performed on a semiconductor wafer.

[0029] Regarding the supply of ozone water, from the perspective of the passivation treatment after the hydrofluoric acid supply step, it is preferable that the ozone water supply step for passivation be performed for a longer time than the ozone water supply step for forming the oxide film. The supply time of ozone water can be, for example, about 10 seconds to 60 seconds in the ozone water supply step for forming the oxide film, and about 20 seconds to 60 seconds in the ozone water supply step for passivation. In the examples shown in FIGS. 4 and 5, the supply time of ozone water was 15 seconds in the ozone water supply step for forming the oxide film and 30 seconds in the ozone water supply step for passivation.

[0030] In the hydrofluoric acid supply step, the supply time of hydrofluoric acid can be, for example, 1 second or more, 2 seconds or more, or 3 seconds or more. As described above, in order to make the defects caused by microfabrication manifest, it is preferable to perform the hydrofluoric acid supply step so that the oxide film formed before the hydrofluoric acid supply step is not completely peeled off and a part of it remains. From this point, the supply time of hydrofluoric acid is preferably 20 seconds or less. In the examples shown in FIGS. 4 and 5, the supply time of hydrofluoric acid in the hydrofluoric acid supply step was 4 seconds. Also, as described above, after the hydrofluoric acid supply step, it is preferable that the oxide film formed before the hydrofluoric acid supply step is not completely peeled off and a part of it remains. Therefore, in the surface treatment of Method 1 described above, it is preferable to perform the ozone water supply step for forming the oxide film before the hydrofluoric acid supply step.

[0031] [Method for manufacturing a semiconductor wafer] One aspect of the present invention relates to a method for manufacturing a semiconductor wafer, including manufacturing a semiconductor wafer under manufacturing conditions to be evaluated, evaluating the manufactured semiconductor wafer by the evaluation method of the semiconductor wafer, determining, based on the result of the evaluation, whether to use the manufacturing conditions obtained by changing the manufacturing conditions to be evaluated as the subsequent manufacturing conditions, or to continue to adopt the manufacturing conditions to be evaluated as the manufacturing conditions, and manufacturing a semiconductor wafer under the determined manufacturing conditions.

[0032] Specific forms of the above manufacturing method can be exemplified as follows. Manufacture a semiconductor wafer under manufacturing condition A. Separately, manufacture a semiconductor wafer under manufacturing condition B, which is different from manufacturing condition A. Set the manufacturing condition to be evaluated as "manufacturing condition B". Extract evaluation wafers from the group of wafers manufactured under manufacturing condition A and the group of wafers manufactured under manufacturing condition B, respectively, and evaluate them by the evaluation method described above. For example, as a result of the evaluation, if the total number of minute process-induced defects classified as process-induced defects in the above-described evaluation method is less in the evaluation wafer extracted from the group of wafers manufactured under manufacturing condition A than in the evaluation wafer extracted from the group of wafers manufactured under manufacturing condition B, it can be determined that manufacturing condition A is a manufacturing condition in which minute process-induced defects are less likely to occur than manufacturing condition B. In this case, manufacturing condition B can be changed so as to approach manufacturing condition A, and the manufacturing condition with such a change can be set as improved manufacturing condition B, and thereafter, a semiconductor wafer can be manufactured. Also, for example, as a result of the evaluation, if the representative value (average value, maximum value, etc.) of the assumed size of the minute process-induced defects classified as process-induced defects calculated by the above-described evaluation method is larger in the evaluation wafer extracted from the group of wafers manufactured under manufacturing condition B than in the evaluation wafer extracted from the group of wafers manufactured under manufacturing condition A, it can be determined that manufacturing condition B is a manufacturing condition in which larger minute process-induced defects are more likely to occur than manufacturing condition A. In this case, manufacturing condition B can be changed so as to approach manufacturing condition A, and the manufacturing condition with such a change can be set as improved manufacturing condition B, and thereafter, a semiconductor wafer can be manufactured.

[0033] Also, as a specific form of the above manufacturing method, the following can also be exemplified. In order to determine the manufacturing condition (hereinafter referred to as "actual manufacturing condition") for manufacturing a semiconductor wafer that is actually shipped as a product, first, determine the test manufacturing condition. Manufacture a semiconductor wafer under this test manufacturing condition. Evaluate the semiconductor wafer manufactured under the test manufacturing conditions by the evaluation method described above. Based on the evaluation results, it is possible to determine the manufacturing conditions with changes made to the test manufacturing conditions as the actual manufacturing conditions, or to determine the test manufacturing conditions themselves as the actual manufacturing conditions. Then, a semiconductor wafer can be manufactured under the determined actual manufacturing conditions. For example, as a result of the evaluation, if the total number of minute process-induced defects classified as process-induced defects in the semiconductor wafer manufactured under the test manufacturing conditions exceeds a preset target value in the evaluation method described above, it is possible to determine the manufacturing conditions with changes made to the test manufacturing conditions so as to suppress the occurrence of minute process-induced defects as the actual manufacturing conditions. Also, for example, as a result of the evaluation, if the representative value (average value, maximum value, etc.) of the assumed size of the minute process-induced defects classified as process-induced defects calculated in the evaluation method described above in the semiconductor wafer manufactured under the test manufacturing conditions exceeds a preset target value, it is also possible to determine the manufacturing conditions with changes made to the test manufacturing conditions so as to suppress the occurrence of minute process-induced defects as the actual manufacturing conditions.

[0034] Regarding the manufacturing process of the semiconductor wafer, for example, the manufacturing process of the polished wafer can be carried out by a manufacturing process including wafer cutting (slicing) from a semiconductor ingot such as a silicon single crystal ingot, chamfering, rough polishing (e.g., lapping), etching, mirror polishing (finish polishing), and a cleaning process performed between or after the above processing steps. Since PID, which is a form of minute process-induced defect, is a defect that occurs in the polishing process, the manufacturing conditions to which the above changes are made can be the polishing process conditions on the surface of the semiconductor wafer. Specifically, various polishing condition changes can be mentioned, such as replacement of the polishing slurry, change in the composition of the polishing slurry, replacement of the polishing pad, change in the type of the polishing pad, and change in the operating conditions of the polishing apparatus.

Industrial Applicability

[0035] One aspect of the present invention is useful in the field of manufacturing various semiconductor wafers of polished wafers.

Claims

1. A method for evaluating a semiconductor wafer, comprising: performing a plurality of surface treatments on the surface of the semiconductor wafer; the surface treatment includes: supplying hydrofluoric acid to the surface of the semiconductor wafer and then supplying ozone water to the surface of the semiconductor wafer after the supply of the hydrofluoric acid, or supplying ozone water to the surface of the semiconductor wafer and then supplying hydrofluoric acid to the surface of the semiconductor wafer after the supply of the ozone water; further including performing a surface inspection on the surface of the semiconductor wafer by a surface defect inspection device before performing the surface treatment, after each surface treatment, and after the plurality of surface treatments are completed; classifying an LPD first detected in a surface inspection after the n-th surface treatment as a processing-induced defect at a coordinate point where no LPD was detected in the surface inspection before the surface treatment; wherein n is an integer of 1 or more and (N - 1) or less, with the total number of surface treatments being N times; at the coordinate point where the processing-induced defect is detected, calculating the assumed size of the processing-induced defect present on the surface of the semiconductor wafer before the surface treatment is performed, using the detection size of the LPD detected in the surface inspection after the plurality of surface treatments are completed as the target variable and the total number of surface treatments (N - n) performed after the first detection as the explanatory variable, by regression analysis; A method for evaluating a semiconductor wafer.

2. The surface treatment includes supplying ozone water to the surface of the semiconductor wafer, then supplying hydrofluoric acid to the surface of the semiconductor wafer after the supply of the ozone water, and then supplying ozone water to the surface of the semiconductor wafer after the supply of the hydrofluoric acid. The method for evaluating a semiconductor wafer according to Claim 1.

3. Performing the regression analysis using the following regression equation with the target variable as y and the explanatory variable as x: y = ax + b wherein, in the regression equation, a is the slope obtained by the regression analysis and b is the intercept obtained by the regression analysis, and at the coordinate point where the processing-induced defect is detected, obtaining the assumed size of the processing-induced defect present on the surface of the semiconductor wafer before the surface treatment is performed, as b. The method for evaluating a semiconductor wafer according to Claim 1.

4. The ozone water is ozone water having an ozone concentration on a mass basis of 20 ppm or more and 30 ppm or less. The method for evaluating a semiconductor wafer according to Claim 1.

5. ​ The hydrofluoric acid is hydrofluoric acid having a hydrogen fluoride concentration of 0.1% by mass or more and 1.0% by mass or less, and the method for evaluating a semiconductor wafer according to claim 1.

6. The supply time of the hydrofluoric acid is 20 seconds or less, and the method for evaluating a semiconductor wafer according to claim 1.

7. The surface treatment includes supplying ozone water to the surface of the semiconductor wafer, supplying hydrofluoric acid to the surface of the semiconductor wafer after the supply of the ozone water, and supplying ozone water to the surface of the semiconductor wafer after the supply of the hydrofluoric acid. The regression analysis is performed using the following regression equation with the objective variable as y and the explanatory variable as x: y = ax + b where in the regression equation, a is the slope obtained by the regression analysis, and b is the intercept obtained by the regression analysis. At the coordinate point where the processing-induced defect is detected, the assumed size of the processing-induced defect existing on the surface of the semiconductor wafer before the surface treatment is obtained as the b. The ozone water is ozone water having an ozone concentration of 20 ppm or more and 30 ppm or less based on mass. The hydrofluoric acid is hydrofluoric acid having a hydrogen fluoride concentration of 0.1% by mass or more and 1.0% by mass or less, and the supply time of the hydrofluoric acid is 20 seconds or less, and the method for evaluating a semiconductor wafer according to claim 1.

8. Manufacturing a semiconductor wafer under the manufacturing conditions of the evaluation target, Evaluating the manufactured semiconductor wafer by the method for evaluating a semiconductor wafer according to any one of claims 1 to 7, Based on the result of the evaluation, determining the manufacturing conditions obtained by changing the manufacturing conditions of the evaluation target as the subsequent manufacturing conditions, or determining the manufacturing conditions of the evaluation target as the manufacturing conditions to be continuously adopted, and Manufacturing a semiconductor wafer under the determined manufacturing conditions. A method for manufacturing a semiconductor wafer including the above steps.

9. The manufacturing conditions to which the change is applied are the polishing treatment conditions on the surface of the semiconductor wafer, and the method for manufacturing a semiconductor wafer according to claim 8.

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