JP5036757B2 - Substrate surface inspection apparatus and surface inspection method - Google Patents

Description

  The present invention relates to a surface inspection apparatus and a surface inspection method for optically detecting defects existing on the surface of a substrate and discriminating the type of defect, and in particular, for example, foreign matters and crystal defects existing on the surface of a semiconductor wafer. Alternatively, the present invention relates to a surface inspection apparatus and a surface inspection method that improve the discrimination accuracy of foreign matter and scratches.

  For semiconductor wafers, high-purity polycrystalline silicon is used as the material. If there is a defect on the surface of this material, it will affect the quality of the product, so inspection is performed with a surface inspection device. Examples of defects generated on the wafer surface include fine foreign matters such as dust and abrasives attached to the surface, crystal defects (COP (Crystal Originated Particles)) formed on the surface, and scratches (polishing scratches) caused by polishing. )and so on. The crystal defects are caused by oxidation of silicon atoms to form minute oxides on the wafer surface, which are lost from the wafer surface by cleaning the wafer, and are formed in a concave shape on the wafer surface. The scratch is generated by polishing the wafer surface, and is formed linearly on the wafer surface. As an effective method for detecting these various defects, the conventional surface inspection apparatus irradiates a laser beam on the wafer surface, and detects the optical properties that are detected differently with respect to the shape and size of each defect. That is, a method of detecting a defect by receiving reflected light or scattered light of the laser light is used.

  Conventionally, as a surface inspection apparatus for detecting foreign matters and crystal defects existing on the wafer surface, for example, there is an apparatus disclosed in JP-A-9-304289. In the above surface inspection apparatus, when the scattered light of the laser beam irradiated on the wafer surface is received by both the low angle receiver and the medium angle receiver, the foreign object is detected, and the scattered light of the laser beam is detected at the medium angle. A crystal defect detection process is performed when light is received only by the light receiver. Further, there are the following apparatuses as surface inspection apparatuses for detecting foreign matter and scratches existing on the wafer surface. When the scattered light of the laser beam irradiated on the wafer surface is received by the medium angle receiver and the high angle receiver, foreign matter detection processing is performed, and when the scattered light of the laser beam is received only by the low angle receiver Scratch detection processing is performed.

  By the way, since the crystal defects have different depths and diameters depending on the degree of defects of the silicon oxide, crystal defects of various shapes are generated on the wafer surface. For this reason, depending on the shape of the crystal defect, scattered light that should be scattered with directivity in the direction of the medium angle light receiver may be scattered with directivity in directions other than the direction. In such a case, in the above surface inspection apparatus, not only the medium angle light receiver but also the low angle light receiver receives the scattered light due to the crystal defect, so that the crystal defect is detected as a foreign substance. there were. Also, scratches having various shapes with different lengths, widths or depths are generated on the wafer surface. Therefore, depending on the shape of the scratch, scattered light that should be scattered with directivity in the direction of the low-angle light receiver may be scattered with directivity in directions other than the direction. In such a case, in the above surface inspection apparatus, not only the low-angle light-receiving system but also the medium-angle light-receiving system and the high-angle light-receiving system receive scattered light due to scratches, so that the scratch is detected as a foreign object. There was a problem.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a surface inspection apparatus and a surface inspection method capable of discriminating foreign matters and crystal defects with high accuracy in the surface inspection of a substrate. It is another object of the present invention to provide a surface inspection apparatus and a surface inspection method capable of discriminating foreign substances and scratches with high accuracy in the surface inspection of a substrate.

  A substrate surface inspection apparatus according to the present invention irradiates a surface of a substrate (eg, a semiconductor substrate) with a light beam (eg, laser light), receives scattered light of the laser light at different angles, and performs first and second operations. An optical system that outputs the received light signal and a reference function that defines a correlation between the levels of the first and second received light signals are set, and the first and second received light signals are compared using the reference function as a comparison reference. And determining means for comparing levels and determining whether a defect present on the surface of the semiconductor substrate corresponds to one of a plurality of different types of defects based on the comparison result. According to this, by comparing the levels of the first and second received light signals using the reference function that defines the correlation between the levels of the first and second received light signals output from the optical system, the semiconductor substrate For example, foreign substances and crystal defects existing on the surface of the semiconductor substrate can be determined with high accuracy. There is an excellent effect. The substrate surface inspection method irradiates a surface of a substrate (for example, a semiconductor substrate) with a light beam (for example, laser light), receives scattered light of the light beam at different angles, and performs first and second light reception. A signal output step and a reference function that defines the correlation between the levels of the first and second light reception signals are set, and the levels of the first and second light reception signals are compared using the reference function as a comparison reference. And determining whether a defect existing on the surface of the substrate corresponds to any of a plurality of different types of defects based on the comparison result. Also by this, an effect similar to the above effect can be obtained.

  The substrate surface inspection apparatus according to the present invention irradiates a surface of a substrate (for example, a semiconductor substrate) with a light beam (for example, a laser beam), receives scattered light of the laser beam at different angles, and receives a plurality of light receptions. An optical system for outputting a signal, and a predetermined value is weighted to a predetermined light reception signal level among the plurality of light reception signals, and the levels of the light reception signal weighted with the predetermined value and the levels of the remaining light reception signals And determining means for determining a plurality of different types of defects present on the surface of the semiconductor substrate by determining the relationship. According to this, among the plurality of light receiving signals output from the optical system, by weighting a predetermined value to the level of the predetermined light receiving signal, the level of the light receiving signal weighted with the predetermined value and the remaining light receiving signals Since the level can be differentiated, the level of the level of the received light signal weighted with the predetermined value and the level of the remaining received light signal are determined, so that, for example, foreign matter and scratches existing on the surface of the semiconductor substrate can be accurately detected. It has an excellent effect that it can be discriminated. In the substrate surface inspection method, a light beam (for example, laser light) is irradiated on the surface of the substrate (for example, a semiconductor substrate), scattered light of the light beam is received at different angles, and a plurality of light reception signals are output. And a step of weighting a predetermined value among predetermined light reception signals among the plurality of light reception signals, and determining a magnitude relationship between the levels of the light reception signals weighted with the predetermined values and the levels of the remaining light reception signals. And a step of discriminating a plurality of different types of defects present on the surface of the substrate. Also by this, an effect similar to the above effect can be obtained.

1 is a schematic configuration diagram showing an embodiment of a substrate surface inspection apparatus according to the present invention. FIG. 2 is a configuration block diagram of a data processing unit according to the surface inspection apparatus shown in FIG. 1. The flowchart of the foreign material and crystal defect determination processing by the surface inspection apparatus shown in FIG. Explanatory drawing which shows the distribution state of the brightness level data of the foreign material and crystal defect by a vertical irradiation / medium angle optical system and an oblique irradiation / low angle optical system. The schematic diagram which shows the determination process and discrimination | determination process of a foreign material and a crystal defect. The schematic block diagram which shows the other Example of the surface inspection apparatus which concerns on this invention. FIG. 7 is a configuration block diagram of a data processing unit according to the surface inspection apparatus shown in FIG. 6. The flowchart of the foreign material and scratch determination processing by the surface inspection apparatus shown in FIG.

  Hereinafter, an embodiment of a substrate surface inspection apparatus according to the present invention will be described with reference to the accompanying drawings. In FIG. 1, the surface inspection apparatus A includes an inspection optical system 1, a rotation / movement table 2, a drive control unit 3, and a data processing unit 4, and the rotation / movement table 2 has a high purity. A semiconductor wafer (hereinafter simply referred to as “wafer”) W to be inspected which is made of polycrystalline silicon is mounted. The inspection optical system 1 includes an oblique irradiation / low angle optical system 5 and a vertical irradiation / medium angle optical system 6 each including a light projecting system and a light receiving system. The oblique illumination / low-angle optical system 5 includes an oblique illumination light source 5a and a low-angle light receiver 5b, and the wafer W is detected so that these detect defects generated on the wafer W surface, that is, crystal defects. Each is arranged at a predetermined position with a predetermined elevation angle with respect to the surface. The vertical irradiation / medium angle optical system 6 includes a vertical irradiation light source 6a and a medium angle light receiver 6b, so that these detect defects generated on the surface of the wafer W, that is, foreign matter and crystal defects. The oblique irradiation / low angle optical system 5 is arranged at a predetermined position with respect to the W surface at an elevation angle higher than that of the oblique irradiation / low angle optical system 5. Further, the oblique irradiation / low angle optical system 5 irradiates the laser beam L1 obliquely so as to form a laser spot on the surface of the wafer W by the oblique irradiation light source 5a, and scans the surface of the wafer W spirally. (This is called spiral scanning). The vertical irradiation / medium angle optical system 6 performs spiral scanning by vertically irradiating the laser beam L2 with a vertical irradiation light source 6a so as to form a laser spot on the surface of the wafer W, and scanning the surface of the wafer W in a spiral manner. . In this embodiment, spiral scanning is performed by rotating the wafer W itself by the rotary table 2a and simultaneously moving the wafer W in the radial direction by the linear movement mechanism 2b. Of course, spiral scanning may be performed by rotating the wafer W itself by the turntable 2a and simultaneously moving the entire optical systems 5 and 6 in the radial direction of the wafer W. The rotation / movement table 2 is controlled by the data processing unit 4 via the drive control unit 3.

  During the spiral scanning, if there is a defect (foreign matter or crystal defect) on the smooth surface of the wafer W surface, the laser spot is irregularly reflected and scattered by the irregularities of the defect. Since the foreign matter is a convex defect formed by dust or polishing agent adhering to the surface of the wafer W, when the foreign matter is present on the surface of the wafer W, the laser spot is scattered in a random direction. On the other hand, since the crystal defect is a dent-like defect formed by missing silicon oxide, when a crystal defect exists on the surface of the wafer W, the laser spot is emphasized and scattered in a specific direction. In other words, the foreign matter generates scattered light in a random direction (that is, omnidirectional scattered light that is not emphasized in a specific direction), but crystal defects generate directional sharp scattered light according to the concave surface. generate. Therefore, if there is a foreign substance on the surface of the wafer W at the same scanning position of the laser spot, the low-angle light receiver 5b and the medium-angle light receiver 6b receive scattered light from the foreign substance, but the crystal on the surface of the wafer W is received. When there is a defect, only the medium angle light receiver 6b receives the scattered light due to the crystal defect. The low-angle light receiver 5b and the medium-angle light receiver 6b that have received the scattered light output light reception signals D1 and D2 to the data processing unit 4 via the A / D converters 7 and 8, respectively, as shown in FIG. To do.

  By the way, since the depth and diameter of crystal defects differ depending on the degree of silicon oxide defects, a relatively large crystal defect, for example, a crystal defect having a shallow depth and a large diameter, has a concave surface that is nearly flat. Accordingly, the directivity range of scattered light is widened, and the scattered light may be received not only by the medium angle light receiver 6b but also by the low angle light receiver 5b. In this way, when scattered light due to crystal defects is received by the oblique irradiation / low angle optical system 5 and the vertical irradiation / medium angle optical system 6, it is impossible to distinguish from foreign matters as they are, so that data processing is performed. The unit 4 performs a discrimination process for discriminating foreign matters and crystal defects using a defect judgment table in which a reference function that defines a correlation between detection levels (luminance levels) of the received light signals D1 and D2 is set. That is, the detection levels of the light reception signals D1 and D2 are compared using the reference function of the defect determination table as a comparison reference, and it is determined based on the comparison result whether the defect existing on the surface of the wafer W corresponds to a foreign matter or a crystal defect. To do.

  With reference to FIG. 3, the determination processing and determination processing of foreign matter and crystal defects in the data processing unit 4 will be described. The MPU 4a of the data processing unit 4 executes a program stored in the memory 4b, and receives the light reception signal D1 obtained from the low angle light receiver 5b and the light reception signal D2 obtained from the medium angle light receiver 6b from the interface 4c through the data bus. Capture through 4d (step S1). In step S2, it is determined whether the light reception signal D1 is captured or the light reception signals D1 and D2 are captured. When the received light signal D1 is taken, it is determined that the crystal defect is present (step 3), and the process proceeds to step 7. When the received light signals D1 and D2 are captured, the process proceeds to step S4 to perform a discrimination process for discriminating foreign matters and crystal defects. In the case of the scattered light measurement method, when the detection level of foreign matter and crystal defect by vertical irradiation / medium angle light reception is the same, the detection level of foreign matter by oblique irradiation / low angle light reception is higher than the detection level of crystal defect. The magnitude relationship between the detection levels of foreign matter and crystal defects by such oblique irradiation / low-angle light reception is such that if the detection levels of foreign matter and crystal defects are the same in vertical irradiation / medium-angle light reception, The same tendency is shown regardless of small. Therefore, the detection level data of the foreign matter and the detection level data of the crystal defect can be separated to some extent from the magnitude relationship between the detection level of the foreign matter and the crystal defect by oblique irradiation / low angle light reception as described above. The MPU 4a uses the defect determination table T (see FIG. 4) in which a reference function is set based on the correlation between the detection levels of the foreign matter and crystal defects due to the oblique irradiation / low-angle light reception as described above, so that the foreign matter and the crystal defects are detected. Determine. As shown in FIG. 4, in the defect determination table T, the horizontal axis (X axis) indicates the detection level of the light reception signal D2 for vertical irradiation / medium angle light reception, and the vertical axis (Y axis) indicates oblique irradiation / low angle light reception. For example, a discrimination line S of a linear function is set as the reference function corresponding to the detection level of the light reception signal D1. The discrimination line S is expressed by, for example, the general formula y = ax + b. Here, “a” is an inclination obtained from detection ratios of detection levels detected by vertical irradiation / medium angle light reception and oblique irradiation / low angle light reception for a plurality of types of standard particles whose particle diameters are known in advance. , “B” is an offset of the detection level of oblique irradiation / low-angle light reception. In the MPU 4a, for example, when the detection level data of the light reception signals D1 and D2 is in a distribution state indicated by black dots in FIG. 4, the group G1 of detection level data in the lower region of the discrimination line S is determined as a crystal defect (step 5) The group G2 of the detection level data in the upper area of the discrimination line S is determined as a foreign substance (step 6). Then, the group G1 determined as a crystal defect in step S5 is added to the crystal defect determined in step S3. In this way, when the discrimination processing between the foreign matter and the crystal defect in the light reception signals D1 and D2 is performed, the size judgment processing of the crystal defect and the foreign matter is then performed (step S7), and then the crystal defect and the foreign matter are detected. A detection value counting process for counting the number individually and calculating the total is performed (step S8), and then a map output process for displaying crystal defects and foreign matters on the CRT 9 is performed (step S9).

  FIG. 5 shows a schematic diagram of these processes so that the MPU 4a can easily understand the determination process and the determination process of foreign matters and crystal defects. As shown in FIG. 5, a crystal defect is determined when the light reception signal D1 is obtained only by vertical irradiation / medium angle light reception. On the other hand, when the light reception signals D1 and D2 are obtained from both the vertical irradiation / medium angle light reception and the oblique irradiation / low angle light reception, the foreign matter and the crystal defect are discriminated by the discrimination line S using the defect determination table T. Note that the received light signal obtained only by oblique irradiation / low-angle light reception is canceled as undefined. In the defect determination table T, for example, when the detection level data of the light reception signals D1 and D2 is in a distribution state indicated by black dots, the group G1 of detection level data in the region below the discrimination line S is determined as a crystal defect (COP). Then, the detection level data group G2 in the upper region of the discrimination line S is determined as a foreign object. Thus, by determining whether the correlation between the received light signals D1 and D2 obtained by both the oblique irradiation / low angle optical system 5 and the vertical irradiation / medium angle optical system 6 is the lower region or the upper region of the discrimination line S. Thus, foreign substances and crystal defects can be distinguished with high accuracy. Then, the crystal defect (COP) is added to the determined crystal defect (COP) determination result.

  In the surface inspection apparatus according to this embodiment, a discrimination line S of a linear function is set in the defect determination table T, but the discrimination line S is not limited to this, and is inclined according to the type of defect to be discriminated. “A” and offset “b” can be set to appropriate values. Further, as the discrimination line S, a function including a curve other than the linear function may be appropriately set as the discrimination line.

  Next, a surface inspection apparatus according to another embodiment will be described with reference to FIG. In this embodiment, a surface inspection apparatus for detecting foreign matter and scratches will be described. In addition, the same code | symbol is attached | subjected to the structural member which is common in the surface inspection apparatus mentioned above. In FIG. 6, the surface inspection apparatus B includes, as the inspection optical system 1, an oblique irradiation / low angle optical system 5 including a light projecting system and a light receiving system, and a vertical irradiation / medium / high angle optical system 11. . The oblique illumination / low-angle optical system 5 includes an oblique illumination light source 5a and a low-angle light receiver 5b. The wafer W surface is detected so that they detect defects or scratches generated on the wafer W surface. Are respectively arranged at predetermined positions with a predetermined elevation angle. The vertical irradiation / medium / high-angle optical system 11 includes a vertical irradiation light source 11a, a medium-angle light receiver 11b, and a high-angle light receiver 11c, which detect defects, that is, foreign matters generated on the surface of the wafer W. Thus, the wafer W is disposed at a predetermined position with an elevation angle higher than that of the oblique irradiation / low-angle optical system 5 described above. As in the above-described embodiment, the oblique irradiation / low-angle optical system 5 obliquely irradiates the laser beam L1 with the oblique irradiation light source 5a so as to form a laser spot on the surface of the wafer W. Spiral scanning is performed to spirally scan the surface. The vertical irradiation / medium / high angle optical system 11 spirally scans the surface of the wafer W spirally by vertically irradiating the laser beam L2 so as to form a laser spot on the surface of the wafer W by the vertical irradiation light source 6a. I do. Also in this embodiment, spiral scanning is performed by rotating the wafer W itself by the rotary table 2a and simultaneously moving the wafer W in the radial direction by the linear moving mechanism 2b. Of course, spiral scanning may be performed by rotating the wafer W itself by the turntable 2a and simultaneously moving the entire optical systems 5 and 11 in the radial direction of the wafer W.

  During the spiral scanning, if there is a defect (foreign matter or scratch) on the smooth surface of the wafer W, the laser spot is irregularly reflected and scattered by the irregularities of the defect. As described above, since the foreign matter is a convex defect formed by dust or abrasive on the surface of the wafer W, the laser spot is scattered in a random direction when the foreign matter is present on the surface of the wafer W. On the other hand, since the scratch is a linear dent defect formed by polishing the surface of the wafer W, when the scratch exists on the surface of the wafer W, the laser spot is emphasized and scattered in a specific direction. In other words, the foreign matter generates scattered light in a random direction (that is, omnidirectional scattered light that is not emphasized in a specific direction), but in the scratch, the directional sharp scattered light according to the depth and width is generated. generate. Therefore, when there is a foreign substance on the surface of the wafer W at the same scanning position of the laser spot, the medium-angle light receiver 11b and the high-angle light receiver 11c receive scattered light from the foreign substance. When there is a scratch, scattered light due to the scratch is received only by the low-angle light receiver 5b. As shown in FIG. 7, the low-angle light receiver 5b, the medium-angle light receiver 11b, and the high-angle light receiver 11c that have received the scattered light respectively receive the light reception signals D3 and D3 via the A / D converters 12, 13, and 14, respectively. D4 and D5 are output to the data processing unit 4.

  By the way, since the depth and the width of the scratch differ depending on the degree of the linear recess formed by polishing the surface of the wafer W, in a relatively large scratch, for example, a scratch having a shallow depth and a large width, the recess surface is almost flat. Due to the surface shape, the directivity range of scattered light is widened, and the scattered light may be received not only by the low-angle light receiver 5b but also by the medium-angle light receiver 11b and the high-angle light receiver 11c. In particular, in the high-angle light receiver 11c, scattered light due to a relatively large scratch is detected. The medium angle light receiver 11b receives scattered light that is not received by the high angle light receiver 11c, and is used as a complementary role to the high angle light receiver 11c. When the vertical irradiation / medium / high angle optical system 11 receives scattered light from scratches, the data processing unit 4 cannot detect the received light signals D3, D4, and D5. Among the level data (luminance level data), a predetermined value is weighted to the detection level data of the reception signals D4 and D5, and the magnitude relationship with the detection level data of the remaining light reception signal D3 is determined, whereby foreign matter and scratches are determined. A discrimination process for discriminating between is performed.

  The foreign object / scratch determination process and determination process in the data processing unit 4 will be described with reference to FIG. The MPU 4a of the data processing unit 4 executes a program stored in the memory 4b, and receives a light reception signal D3 obtained from the low angle light receiver 5b and a light reception signal D4 obtained from the medium angle light receiver 11b and the high angle light receiver 11c. , D5 are fetched from the interface 4c via the data bus 4d (step S11). In step S12, it is determined whether the light reception signal D3 is captured or the light reception signals D3, D4, and D5 are captured. If the received light signal D3 is captured, it is determined as a scratch (step 13), and the process proceeds to step 17. When the received light signals D3, D4, and D5 are captured, the process proceeds to step S14 to perform a discrimination process for discriminating foreign objects and scratches. That is, in step S14, a value obtained by adding a predetermined coefficient K to the addition value of the detection level data of the light reception signals D4 and D5, that is, a value obtained from K (D4 + D5), and the detection of the remaining light reception signal D3. Compare magnitude relationship with level data. In this way, by weighting the detection coefficient data of the light reception signals D4 and D5 obtained from the vertical irradiation / medium / high angle optical system 11 with the predetermined coefficient K, the light reception signals D4 and D5 weighted with the predetermined coefficient K. And the received light signal D3 obtained from the oblique irradiation / low angle optical system 5 can be differentiated. In step S14, if K (D4 + D5) ≧ D3d (“Y” in step S14), a scratch is determined (step S15), and if K (D4d + D5d) <D3d (“N” in step S14) Determination is made (step S16). Then, the scratch determined in step S16 is added to the scratch determined in step S13. After the foreign matter and scratch determination process is performed in the reception signals D3, D4, and D5 in this way, the scratch and foreign matter size determination process is performed (step S17), and then the number of scratches and foreign objects is determined. A detection value counting process is performed to calculate the total by individually counting (step S18), and then a map output process for displaying the scratch and the foreign substance on the CRT 9 is performed (step S19).

  As described above, in this embodiment, the oblique illumination / low angle optical system 5 is weighted with a predetermined value on the detection level data of the light reception signals D4 and D5 obtained from the vertical illumination / medium / high angle optical system 11. Since the comparison is made with the detection level data of the light reception signal D3 obtained from the above, foreign substances and scratches can be discriminated with high accuracy. Of course, instead of the vertical irradiation / medium / high angle optical system 11 of the inspection optical system 1, a vertical irradiation / high angle optical system including a vertical irradiation light source 11a and a high angle light receiver 11c may be used.

  In each of the above-described embodiments, the case where laser light is used as the light beam has been described as an example. However, white light or ultraviolet irradiation light may be used instead of the laser light. In each of the embodiments, the laser beam is described as spiral scanning in which the surface of the wafer is spirally scanned. However, the scanning may be XY two-dimensional scanning. Further, in each embodiment, the surface inspection of the semiconductor wafer substrate has been described, but it can also be applied to the surface inspection of a glass substrate or the like.

  As described above, according to the substrate surface inspection apparatus and the surface inspection method of the present invention, the reference function that defines the correlation between the levels of the first and second received light signals output from the optical system is used. By comparing the levels of the first and second received light signals, it is possible to determine whether a defect existing on the surface of the substrate corresponds to one of a plurality of different types of defects. For example, foreign substances and crystal defects can be distinguished with high accuracy. In addition, by weighting a predetermined value to the level of a predetermined light receiving signal among a plurality of light receiving signals output from the optical system, the level of the light receiving signal weighted with the predetermined value and the level of the remaining light receiving signal are obtained. Because it can be differentiated, it is possible to discriminate between, for example, foreign matters and scratches existing on the surface of the substrate with high accuracy by determining the magnitude relationship between the level of the received light signal weighted with the predetermined value and the remaining received light signal level. Can do.

DESCRIPTION OF SYMBOLS 1 Inspection optical system 4 Data processing part 5 Oblique irradiation / low angle optical system 5a Oblique irradiation light source 5b Low angle light receiver 6 Vertical irradiation / medium angle optical system 6a Vertical irradiation light source 6b Medium angle light receiver 11 Vertical irradiation / medium High angle optical system 11a Vertical irradiation light source 11b Medium angle light receiver 11c High angle light receiver W Wafer

Claims (4)

An illumination optical system that illuminates the surface of the substrate with a first light beam at a first elevation angle and a second elevation angle higher than the first elevation angle;
Light from the substrate is detected at a first angle, light from the substrate is detected at a second angle higher than the first angle, and the light is detected at a third angle higher than the second angle. A detection optical system that detects the angle;
A predetermined coefficient is added to the sum of the first received light signal illuminated at the second elevation angle and detected at the third angle and the second received light signal illuminated at the second elevation angle and detected at the second angle. And a processing unit that discriminates foreign matters from scratches by comparing the multiplied result with a third light receiving signal illuminated at the first elevation angle and received at the first angle. A substrate surface inspection apparatus. In the surface inspection apparatus according to claim 1,
When the processing unit determines that the third light receiving signal is obtained without obtaining the first light receiving signal and the second light receiving signal, the processing unit determines that the scratch is received, and the first light receiving signal is obtained. When it is determined that the second received light signal and the third received light signal have been obtained, the sum of the first received light signal and the second received light signal is multiplied by the coefficient, and the multiplication result is obtained. And the third light receiving signal to discriminate the foreign material from the scratch. Illuminating the surface of the substrate with a first light beam at a first elevation angle and a second elevation angle higher than the first elevation angle;
Light from the substrate is detected at a first angle, light from the substrate is detected at a second angle higher than the first angle, and the light is detected at a third angle higher than the second angle. Detecting by angle;
A predetermined coefficient is added to the sum of the first received light signal illuminated at the second elevation angle and detected at the third angle and the second received light signal illuminated at the second elevation angle and detected at the second angle. And a step of discriminating foreign matter from scratch by comparing the multiplied result with a third light receiving signal illuminated at the first elevation angle and received at the first angle. A method for inspecting a surface of a substrate. The surface inspection method according to claim 3,
When the processing step determines that the third light reception signal is obtained without obtaining the first light reception signal and the second light reception signal, it is determined as the scratch, and the first light reception signal is obtained. When it is determined that the second received light signal and the third received light signal have been obtained, the sum of the first received light signal and the second received light signal is multiplied by the coefficient, and the multiplication result is obtained. And the third light reception signal to discriminate between the foreign matter and the scratch.

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