JP2009088026A - Apparatus and method for surface inspection of semiconductor wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for surface inspection of a semiconductor wafer capable of improving the efficiency of an inspection process of the semiconductor wafer. <P>SOLUTION: The apparatus for surface inspection of a semiconductor wafer includes a light-irradiating means 2, a light receiving means, a photoelectric conversion means 6, a signal amplifying means 26, a measuring means 22 and a counting means 23. The apparatus includes a reliable section width storage means 25, in which a reliable section width set, according to a size of foreign matter or a defect on a surface of the semiconductor wafer calculated in advance by specimen measurement, when an amplification factor is fixed by the signal amplifying means 26 and a determination means 24 for fixing the amplification factor by the signal amplifying means 26; calculating the size of the foreign matter or the defect on the surface of the semiconductor wafer measured by the measuring means 22 based on the reliable section width, according to the size of the foreign matter or the defect; and determining whether the surface of the semiconductor wafer is proper from a counted value, according to the size of the foreign matter or the defect on the surface of the semiconductor wafer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a semiconductor wafer surface inspection apparatus and a semiconductor wafer surface inspection method.

Conventionally, as a method for inspecting the surface of a semiconductor wafer for minute defects and foreign matter, a laser beam is irradiated on the surface of the semiconductor wafer, and the weak light scattering when the laser beam is irradiated on the defect or the like is a photomultiplier tube. There is known a method for performing a wafer pass / fail judgment by detecting the magnitude of the detected defect by counting the number of detected defects as an electric signal by amplification using (For example, refer to Patent Document 1).
On the other hand, the required quality of the semiconductor wafer from the semiconductor device manufacturer includes, for example, the number of defects having a size of 0.12 μm to 0.30 μm within 3 mm from the outer periphery of the semiconductor wafer.

JP 2001-264264 A

However, in the method of amplifying with such a photomultiplier tube, it is difficult to detect a small defect to a large defect by fixing the photomultiplier tube to a certain amplification magnification (gain).
This is because the size of the defect that can be detected at a certain amplification magnification differs depending on the amplification magnification of the photomultiplier tube. Is not guaranteed.
In addition, the detection by the photomultiplier tube is highly accurate due to halation occurring near the edge of the semiconductor wafer, high haze on the surface of the semiconductor wafer, and background noise such as system noise in the electrical signal processing of the surface inspection apparatus. It is difficult to detect defects on the surface of the semiconductor wafer.
For this reason, conventionally, in this type of surface inspection, the number of defects having a size guaranteed by each gain is counted, and the quality of the wafer is determined based on whether or not this satisfies the required quality. In this case, since the range of the defect size guaranteed to be detected for the above reason is limited, the gain must be changed for each wafer to be inspected, and the defect must be counted multiple times. There is a problem that the inspection process becomes complicated.

  An object of the present invention is to provide a semiconductor wafer surface inspection apparatus and a semiconductor wafer surface inspection method capable of improving the efficiency of a semiconductor wafer inspection process.

A surface inspection apparatus for a semiconductor wafer according to the present invention comprises:
A semiconductor wafer surface inspection apparatus for measuring a surface of a semiconductor wafer to be inspected by an optical technique and detecting foreign matter or defects on the surface of the semiconductor wafer,
A light irradiation means for irradiating the semiconductor wafer surface with light;
A light receiving means for receiving reflected light or scattered light from the surface of the semiconductor wafer;
Photoelectric conversion means for converting light received by the light receiving means into an electrical signal by a photoelectric effect;
Signal amplifying means for amplifying the electric signal converted by the photoelectric conversion means;
Based on the electrical signal amplified by the signal amplification means, measuring means for measuring the size of the foreign matter or defect on the surface of the semiconductor wafer,
A counting means for counting the number of particles according to the size of the foreign matter or defect measured by the measuring means;
For each amplification factor by the signal amplification means, a confidence interval width storage means in which a confidence interval width set according to the size of the foreign matter or defect on the surface of the semiconductor wafer calculated in advance by sample measurement is stored;
The amplification factor by the signal amplification unit is fixed, and the size of the foreign matter or defect on the surface of the semiconductor wafer measured by the measurement unit is calculated based on the confidence interval width corresponding to the size of the foreign matter or defect. The semiconductor wafer surface is provided with quality determination means for determining quality of the semiconductor wafer surface from a count value corresponding to the size of the foreign matter or defect on the surface of the semiconductor wafer.

Here, the confidence interval width stored in the confidence interval width storage means uses a single semiconductor wafer as a sample, fixes the amplification magnification by the signal amplification means, and irradiates the semiconductor wafer surface with light by the light irradiation means. Obtaining a plurality of measured values of the size of the foreign matter or defect measured by the light receiving means, the signal amplifying means, and the measuring means, and can be calculated by a general statistical method, for example, the average value of the sample, And a population mean confidence interval using the variance and can be calculated.
According to the present invention, the semiconductor wafer surface inspection apparatus includes the confidence interval width storage means, and the pass / fail judgment means corresponds to the size of the foreign matter or defect on the surface of the semiconductor wafer stored in the confidence interval width storage means. Based on the confidence interval width, the size of the foreign matter or defect on the surface of the semiconductor wafer is calculated. Since the quality of the semiconductor wafer surface is judged from the count value of the foreign matter or defect according to the size, even if the size of the foreign matter or defect is measured in a state where the amplification factor by the signal amplification means is fixed. Based on the lower limit value obtained by subtracting the confidence interval width from the measured value, the foreign matter or defect can be counted by the counting means.
Therefore, it is possible to count the foreign matter or defect on the surface of the semiconductor wafer with high accuracy without changing the amplification factor by the signal amplifying means according to the size of the foreign matter or defect, and the accuracy of the quality determination of the semiconductor wafer is improved. In addition, the inspection process can be greatly shortened.

A method for inspecting a surface of a semiconductor wafer according to the present invention includes:
A method for inspecting a surface of a semiconductor wafer by measuring the surface of a semiconductor wafer to be inspected by an optical technique and detecting foreign matter or defects on the surface of the semiconductor wafer,
A procedure for selecting any one of the plurality of semiconductor wafers as a specimen;
A procedure for measuring the surface of the semiconductor wafer selected as a specimen by an optical method and converting it into an electrical signal;
A procedure for amplifying the converted electrical signal with a fixed amplification factor;
A procedure for measuring the size of foreign matter or defects on the surface of the semiconductor wafer based on the amplified electrical signal;
About the semiconductor wafer used as the specimen, the procedure of measuring by an optical method and converting to an electric signal or the procedure of measuring the size of the foreign matter or defect is repeated a plurality of times, and the size of the foreign matter or defect is obtained from the obtained result. Calculating a mean value and a variance of, and setting a confidence interval width for the mean value to the size of the foreign matter or defect by a statistical method;
The surface of another semiconductor wafer is measured by the optical method and converted into an electric signal. The converted electric signal is amplified by the fixed amplification factor, and based on the set confidence interval width. Measure the size of the foreign matter or defect on the surface of the other semiconductor wafer, and count the number of foreign matter or defect according to the size of the foreign matter or defect on the surface of the other semiconductor wafer. And a procedure for determining whether the wafer is good or bad.

  According to the present invention, the size of the defect or foreign matter having a different size on the surface of the semiconductor wafer to be a sample is measured a plurality of times while the amplification factor by the signal amplification means is fixed, and the size of the foreign matter or the defect is determined from the measurement result. When setting the confidence interval width according to the number of foreign particles or defects on the surface of other semiconductor wafers, it is possible to count in consideration of the confidence interval width according to the size of the defect or foreign matter. Alternatively, the number of defects can be counted with high accuracy, and pass / fail judgment can be performed with high accuracy. In addition, even if the size of the foreign matter or the defect is different, it is possible to count at the same amplification magnification without changing the amplification magnification, and the semiconductor wafer surface can be inspected quickly.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a semiconductor wafer surface inspection apparatus 1 according to an embodiment of the present invention. The semiconductor wafer surface inspection apparatus 1 includes a laser oscillator 2, a reflection mirror 3, an elliptical mirror 4, a light guide. The apparatus includes a body 5 and a photomultiplier tube 6 and performs surface inspection of a semiconductor wafer W disposed below the ellipsoidal mirror 4.
The laser oscillator 2 as light irradiation means has a configuration in which argon gas is sealed in a cavity, and irradiates the reflection mirror 3 with laser light of a predetermined wavelength by exciting the argon gas in the cavity.

The reflection mirror 3 is a member that reflects the laser light emitted from the laser oscillator 2 and guides it to the opening 41 formed on the upper surface of the elliptical mirror 4.
The ellipsoidal mirror 4 is a light condensing member whose lower surface is a reflecting surface having an elliptical curved surface, and the laser light entering from the opening 41 is incident on the surface of the lower semiconductor wafer W. When the laser beam is irradiated onto the foreign matter or defect on the surface of the semiconductor wafer W, weak light scattering occurs, and the light enters the light incident end surface of the light guide 5 through the reflecting surface of the ellipsoidal mirror 4.
The light guide 5 is configured as a bundle of optical fibers, the light incident end surface 51 side is configured as a rectangular end surface corresponding to the width of the ellipsoidal mirror 4, and the light exit side end surface side is the photomultiplier tube 6. It is comprised as a circular end surface according to the light incident surface. Then, the scattered light generated at any location of the ellipsoidal mirror 4 is captured by the light incident end face 51 of the light guide 5 and supplied to the photomultiplier tube 6 while repeating internal reflection.

Although not shown in FIG. 1, the photomultiplier tube 6 includes a photoelectric surface that performs photoelectric conversion of incident light and a plurality of amplification electrodes that amplify electrons converted by the photoelectric surface. Scattered light incident from the body 5 is converted into electrons on the photocathode by the photoelectric effect, amplified by a plurality of amplification electrodes to which a voltage is applied, and converted into an electric signal. The amplification magnification by the photomultiplier tube 6 can be changed by adjusting the voltage applied to the amplification electrode. Although not shown, an arithmetic processing unit such as a computer is provided at the subsequent stage of the photomultiplier tube 6, and the electric signal amplified and converted by the photomultiplier tube 6 is processed by this computer. The amplification factor may be changed by providing a signal amplifier between the photomultiplier tube 6 and the computer.
Although not shown in FIG. 1, the semiconductor wafer W is placed on an XY table that is movable in the horizontal direction. Then, while irradiating the laser beam from the laser oscillator 2, the semiconductor wafer W is moved in the horizontal direction by the XY table, thereby scanning the surface of the semiconductor wafer W with the laser beam.

FIG. 2 shows a computer 20 that controls the above-described semiconductor wafer surface inspection apparatus 1. The computer 20 includes an A / D converter 21, a measuring means 22, a counting means 23, a pass / fail judgment means 24, A confidence interval width storage unit 25, an amplification factor switching unit 26, a voltage application control unit 27, a control unit 28, a display control unit 29, and a display 30 are provided.
The A / D converter 21 is a part that converts the analog electrical signal output from the photomultiplier tube 6 into a digital electrical signal that can be processed by the computer 20.
The measuring means 22 is a part that measures the size of the foreign matter or defect from the magnitude of the LPD from the electrical signal detected by the photomultiplier tube 6. The measured size of the foreign matter or defect is passed to the pass / fail judgment means 24. Output.
The counting means 23 is a part that counts foreign matter or defects having a certain range of sizes, and outputs the counted number of foreign matters or defects to the pass / fail judgment means 24.

The pass / fail determination means 24 determines pass / fail of the semiconductor wafer W that is the inspection target based on the size of the foreign matter or defect measured by the measuring means 22 and the number of foreign matters or defects counted by the counting means 23. It is a part to do.
At this time, the pass / fail judgment unit 24 is set according to the size range of the foreign matter or defect stored in the confidence interval width storage unit 25 based on the amplification factor of the electrical signal set by the amplification factor switching unit 26. With reference to the confidence interval width, the counting means 23 counts the foreign matter or defect having a size set inward by the confidence interval width from the size of the foreign matter or defect measured by the measuring means 22.
A method for setting the confidence interval width set in accordance with the size range of the foreign matter or defect stored in the confidence interval width storage means 25 will be described later.

The amplification magnification switching means 26 is a part for changing the amplification magnification of the electric signal at the time of photoelectric conversion by the photomultiplier tube 6. When the amplification magnification is changed by the amplification magnification switching means 26, the voltage application control means 27 The voltage applied to the photomultiplier tube 6 is controlled, and the amplification factor in the photomultiplier tube 6 is changed. In the present embodiment, the amplification magnification that can be changed by the amplification magnification switching means 26 is configured to be changeable to Gain 1 to Gain 7 as shown in Table 1 below, according to each amplification magnification of Gain 1 to Gain 7. A particle size range that guarantees the measurement is determined.
Therefore, when measuring with the semiconductor wafer surface inspection apparatus 1 by a conventional method, the number of LPDs is counted for each defect or foreign material size while changing the amplification magnification from Gain 1 to Gain 7 according to the particle size range to be measured. Must.

The control means 28 is a part that drives and controls the laser oscillator 2 as the light irradiation means and the XY table drive mechanism 7 for scanning the surface of the semiconductor wafer W.
The display control unit 29 causes the display 30 to display an image of the surface of the semiconductor wafer W output from the pass / fail determination unit 24, and based on the measured value and count value of the LPD determined by the pass / fail determination unit 24. This is a portion for displaying an image of the distribution of foreign matter or defects.

  When the surface of the semiconductor wafer W is scanned with laser light by the semiconductor wafer surface inspection apparatus 1 as described above, if there is a foreign matter or a defect on the surface of the semiconductor wafer W, a scattering phenomenon occurs at that portion, as shown in FIG. As shown, a part of the vertically incident laser light is scattered and detected as a light point defect (LPD) in the photomultiplier tube 6. As shown in FIG. 3, when the measurement is performed on the flat portion of the semiconductor wafer W, the laser beam B2 reflected perpendicularly to the incident laser beam B1 and exiting from the opening 41 is approximately 90%. The scattered light B3 and B4 reflected by the reflecting surface 42 of the elliptical mirror 4 and captured by the light guide 5 is about 5%.

  However, as shown in FIG. 4, when the laser light irradiates near the edge of the semiconductor wafer W, the flatness of the surface of the semiconductor wafer W deteriorates. Therefore, the amount of the laser beam B5 reflected from the opening 41 decreases, and the amount of the laser beams B6 and B7 captured by the light guide 5 increases. Specifically, the laser beam B5 near the edge of the semiconductor wafer W is only about 10% of the incident laser beam B1, and the laser beams B6 and B7 captured by the light guide 5 are about 90%. The reverse phenomenon is seen.

For this reason, when the distribution of LPD detected by the photomultiplier tube 6 is processed by a computer and grasped as an image, the LPD 11 is detected in the form of dots in the central region of the semiconductor wafer W as shown in FIG. However, in the edge region of the semiconductor wafer W, the curved LPD 12 along the outer peripheral edge of the semiconductor wafer W is detected.
This is called halation, but when viewed from the signal intensity detected by the photomultiplier tube 6, as shown in FIG. 6, the recovery curve C1 of the photomultiplier tube 6 shows the signal intensity at the region R1. The signal intensity exceeds the threshold value T1. In this case, measurement cannot be performed until the charge saturation state of the photomultiplier tube 6 is recovered.

On the other hand, the cause of the decrease in detection accuracy is not only due to the above-mentioned halation, but also due to the systematic noise of the semiconductor wafer surface inspection apparatus 1 and the interaction of the haze on the surface of the semiconductor wafer W that is the object to be measured. There is the generation of pseudo-LPD due to the ghost that occurs.
That is, as shown in FIG. 7, the electrical signal detected by the photomultiplier tube 6 includes system noise N1 corresponding to the semiconductor wafer surface inspection apparatus 1 and noise N2 due to Haze on the surface of the semiconductor wafer W. Usually, in order to remove these noises N1 and N2 from the peak P1 of LPD, noise components below a certain threshold T2 are removed by HPF (High Pass FIlter).

However, when the system noise N1 and the Haze on the surface of the semiconductor wafer W interact with each other, a ghost, that is, a pseudo-LPD peak P2 may occur beyond the threshold in addition to what is originally detected as the LPD peak P1. . Specifically, there is no problem when the noise N2 due to the haze on the surface of the semiconductor wafer W is low and the system noise N1 is small, but when any noise is large, the peak P2 of the pseudo LPD is the threshold value. It may be detected beyond T2.
In this case, as shown in FIG. 8, pseudo LPDs 13 due to ghosts are distributed on the surface of the semiconductor wafer W adjacent to the LPD 11 based on the original foreign substance defect, which also reduces the detection accuracy. It will contribute.

In order to confirm the influence of such halation, ghost, etc., the present inventors confirmed the occurrence of halation, ghost, etc. at two levels of amplification magnifications Gain6, Gain7. The problem is confirmed to be affected by halation, ghosts, etc. near 0.12 μm, and gain 7 is utilized rather than Gain 6, and the S / N (Signal / Noise) of the semiconductor wafer surface inspection apparatus 1 is used. By increasing the ratio, it was confirmed that LPD in the vicinity of 0.12 μm could be separated from halation and ghost.
That is, with regard to halation, by setting Gain6 → Gain7, as shown in FIG. 9, the threshold value T2 in Gain7 increases, so that no halation generation region is generated.
Similarly, for the ghost, as shown in FIG. 10, the threshold for detecting 0.12 μm rises, so that the pseudo LPD is not detected in the same manner.

Thus, by setting the amplification magnification from Gain 6 to Gain 7 to the high sensitivity side, it was confirmed that there was no influence of halation, ghost, etc., but as shown in Table 1 above, the surface of the semiconductor wafer In the inspection apparatus 1, since the range of the size of the foreign matter or defect that guarantees the measurement at a constant amplification magnification is limited, these are compensated by using a statistical method, and 0.12 μm to 0.16 μm. It was made possible to measure the size range of foreign matter or defect up to 0.30 μm with Gain 7 which guarantees the size range of foreign matter or defect.
Specifically, the population mean μ and population variance σ ² of the population are unknown, and the size of the foreign matter or defect having a different surface size of one semiconductor wafer W as a sample from the same type of semiconductor wafer W. Measure the thickness multiple times. The sample average x _ave of the sample is obtained by the following equation (1), and the variance V of the sample is obtained by the following equation (2).

Once the sample average x _ave and the sample variance V are obtained, if the distribution of this sample follows the t distribution, the confidence interval of the mean μ of the population can be estimated by the following equation (3). Here, N is the number of sample data, φ is the degree of freedom (= N−1), t (φ, α / 2) is the degree of freedom φ, and the inverse function of the Student's t distribution with two-sided probability α. .

Next, the reliability is 95% (1-α: 0.95), one of the plurality of semiconductor wafers W is selected as a sample, and the size of the foreign matter or defect having a different size on the surface of the semiconductor wafer W is selected. Is measured 10 times by the semiconductor wafer surface inspection apparatus 1, and the sample average x _ave and the sample variance V in the size of each foreign matter or defect are calculated. As a result, the results shown in Table 2 are obtained. According to 3), when the confidence interval for each foreign matter or defect was estimated, the results shown in Table 3 were obtained.

When these are arranged, as shown in FIG. 11, when measuring a foreign matter or defect of 0.12 μm to 0.30 μm with an amplification factor of Gain7, in a range D1 of 130 nm (0.13 μm) to 170 nm (0.17 μm), Since the measurement range is guaranteed by Gain 7, the confidence interval width is ± 0.00 μm, that is, it can be seen that the measurement value may be trusted as it is.
Next, in the range D2 from 180 nm (0.18 μm) to 250 nm (0.25 μm), the confidence interval width of 95% reliability is ± 0.01 μm, so the confidence interval width with respect to the value measured with Gain7 The size of the foreign matter or defect is estimated using the inner value obtained by subtracting 0.01 μm. That is, for example, when counting foreign matters or defects having an average value of 200 nm (0.20 μm) with Gain 7, the foreign matters or defects having a size of 190 nm (0.19 μm) obtained by subtracting the confidence interval width 0.01 of the range D2. Since it may be detected as, it is counted.
Similarly, in the range D3 from 250 nm (0.25 μm) to 300 nm (0.30 μm), the confidence interval width is ± 0.02 μm, so that the measured value is obtained by subtracting −0.02 μm from the measured value. Are counted as being included in the range of D3.

When the graph shown in FIG. 11 or the table of the inner set values as described above is obtained, this value is stored in the storage means such as the memory of the surface inspection apparatus 1 of the semiconductor wafer. With reference to the stored value of the inner set value, the LPD is counted according to the size of the foreign matter or defect of the other semiconductor wafer W. At this time, if the LPD size is larger than the inner set value by the confidence interval width, it is determined that all foreign matters or defects having a size included in the range are included in the counting object by the counting means and counted. .
According to this embodiment, the semiconductor wafer W as a sample is measured in a state where the amplification magnification is fixed, the size of the foreign matter or defect outside the originally guaranteed range is measured, and this is determined as the confidence interval width. In the semiconductor wafer surface inspection apparatus, the amplification magnifications Gain1 to Gain7 are determined in accordance with the size of the foreign matter or defect in the semiconductor wafer surface inspection apparatus. There is no need to change. Therefore, compared to the conventional measurement work, the measurement work can be greatly improved in efficiency and the measurement accuracy is not impaired.
In addition, this embodiment is an example in which the distribution of the actual measurement of the foreign matter or the defect is inferred as a t distribution, and another distribution generally used in statistical methods may be used from the inference. .

The outline perspective view showing the surface inspection device of the semiconductor wafer concerning the embodiment of the present invention. The block diagram showing the structure of the computer in the said embodiment. The schematic diagram explaining the measurement principle in the state which the halation does not arise in the said embodiment. The schematic diagram explaining the principle which the halation produces in the said embodiment. The schematic diagram which shows distribution of LPD when the halation generate | occur | produces in the said embodiment. The graph showing the area | region where the recovery curve of a photomultiplier tube and the halation generate | occur | produce in the said embodiment. The graph for demonstrating the principle which pseudo | simulation LPD by the ghost in the said embodiment produces. The schematic diagram which shows distribution of LPD when pseudo | simulation LPD in the said embodiment generate | occur | produces. The graph showing the relationship between the recovery curve of a photomultiplier tube at the time of setting the amplification magnification in the said embodiment to the high magnification side, and a threshold value. The graph showing the relationship between the peak height of the pseudo-LPD of the photomultiplier tube and the threshold when the amplification magnification in the embodiment is set on the high magnification side. The graph showing the relationship between the range of the size of LPD and the confidence interval in the embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Semiconductor wafer surface inspection apparatus, 2 ... Laser oscillator, 3 ... Reflection mirror, 4 ... Ellipsoidal mirror, 5 ... Light guide, 6 ... Photomultiplier tube, 7 ... Table drive mechanism, 11, 12, 13 ... LPD, 20 ... computer, 21 ... A / D converter, 22 ... measuring means, 23 ... counting means, 24 ... pass / fail judgment means, 25 ... confidence interval storage means, 26 ... amplification magnification switching means, 27 ... voltage application control Means 28 ... Control means 29 ... Display control means 30 ... Display 41 ... Opening 42 ... Reflecting surface 51 ... Light incident end face B1 ... Laser light B2 ... Laser light B3, B4 ... Scattered light, B5 ... laser light, B6 ... laser light, C1 ... recovery curve, D1, D2, D3 ... range, N1 ... system noise, N2 ... noise due to high haze, P1, P2 ... peak, R1 ... region, T1, T2 ... threshold, W ... Semiconductor Ha

Claims (2)

A semiconductor wafer surface inspection apparatus for measuring a surface of a semiconductor wafer to be inspected by an optical technique and detecting foreign matter or defects on the surface of the semiconductor wafer,
A light irradiation means for irradiating the semiconductor wafer surface with light;
A light receiving means for receiving reflected light or scattered light from the surface of the semiconductor wafer;
Photoelectric conversion means for converting light received by the light receiving means into an electrical signal by a photoelectric effect;
Signal amplifying means for amplifying the electric signal converted by the photoelectric conversion means;
Based on the electrical signal amplified by the signal amplification means, measuring means for measuring the size of the foreign matter or defect on the surface of the semiconductor wafer,
A counting means for counting the number of particles according to the size of the foreign matter or defect measured by the measuring means;
For each amplification factor by the signal amplification means, a confidence interval width storage means in which a confidence interval width set according to the size of the foreign matter or defect on the surface of the semiconductor wafer calculated in advance by sample measurement is stored;
The amplification factor by the signal amplification unit is fixed, and the size of the foreign matter or defect on the surface of the semiconductor wafer measured by the measurement unit is calculated based on the confidence interval width corresponding to the size of the foreign matter or defect. An apparatus for inspecting a surface of a semiconductor wafer, comprising: a quality judgment means for judging quality of the surface of the semiconductor wafer from a count value corresponding to the size of foreign matter or defect on the surface of the semiconductor wafer. A method for inspecting a surface of a semiconductor wafer by measuring the surface of a semiconductor wafer to be inspected by an optical technique and detecting foreign matter or defects on the surface of the semiconductor wafer,
A procedure for selecting any one of the plurality of semiconductor wafers as a specimen;
A procedure for measuring the surface of the semiconductor wafer selected as a specimen by an optical method and converting it into an electrical signal;
A procedure for amplifying the converted electrical signal with a fixed amplification factor;
A procedure for measuring the size of foreign matter or defects on the surface of the semiconductor wafer based on the amplified electrical signal;
About the semiconductor wafer used as the specimen, the procedure of measuring by an optical method and converting to an electric signal or the procedure of measuring the size of the foreign matter or defect is repeated a plurality of times, and the size of the foreign matter or defect is obtained from the obtained result. Calculating a mean value and a variance of, and setting a confidence interval width for the mean value of the size of the foreign matter or defect by a statistical method;
The surface of another semiconductor wafer is measured by the optical method and converted into an electric signal. The converted electric signal is amplified by the fixed amplification factor, and based on the set confidence interval width. Measure the size of the foreign matter or defect on the surface of the other semiconductor wafer, and count the number of foreign matter or defect according to the size of the foreign matter or defect on the surface of the other semiconductor wafer. A method for inspecting a surface of a semiconductor wafer, comprising: performing a wafer quality determination procedure.

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