JP2011009554A - Method and device for inspecting defect - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for inspecting a defect improved in measurement accuracy of a defect of a semiconductor wafer.SOLUTION: This method for inspecting a defect has: a reference substrate installation process of installing a substrate becoming a reference for inspection in this device for inspecting a defect; a light intensity measurement process of emitting light to the installed substrate becoming the reference for the inspection to measure intensity of scattering light of the emitted light; a correction process of decreasing power of the light when the intensity of the scattering light is larger than a set reference level, and increasing the power of the light when the intensity of the scattering light is smaller than the reference level; and an inspection process of installing a substrate becoming an object of inspection in the device for inspecting a defect, emitting light of the corrected power to the substrate becoming the object of the inspection to detect scattering light of the emitted light, and thereby inspecting a defect on the substrate becoming the object of the inspection.

Description

  The present invention relates to a defect inspection method and a defect inspection apparatus.

  When manufacturing a semiconductor integrated circuit or the like, it is necessary to form a large number of fine patterns of micron order or less and at a high density. At this time, it is examined whether or not a semiconductor wafer such as a silicon substrate forming a semiconductor integrated circuit has a defect such as dust or scratch, and if there is a defect such as dust or scratch on the silicon substrate or the like. That is extremely important. For this reason, by irradiating an inspection object such as a silicon substrate with light, etc., detecting scattered light of the light irradiated on the inspection object, and performing image processing, pattern collapse and dust or defects are detected. It is done to detect.

  For example, a silicon substrate or the like, which is an inspection object, is irradiated with a light beam, an optical image reflected from the inspection object is formed by an objective lens, converted into an image signal by an image sensor, and based on the converted image signal Pattern breakage, dust or defects are detected.

JP 2007-298501 A

  Incidentally, miniaturization of semiconductor integrated circuits is progressing day by day, and inspection at a higher magnification is required. In this case, detection of fine defects may be missed due to a slight focus shift of the optical system. Normally, focusing on an object is performed by the autofocus function installed in the defect inspection device, but even with the autofocus function, avoid a slight focus shift due to aging of the device or variations between devices. I can't.

  Further, the power and noise level of the laser light may fluctuate due to slight power fluctuations of the semiconductor laser used as the light source of the light beam, and the fluctuating noise may be erroneously detected as a defect.

  Therefore, there is a demand for a defect inspection method and a defect inspection apparatus that can accurately focus on a semiconductor wafer or the like, and can accurately inspect a minute defect without overlooking a minute defect without erroneously detecting noise or the like. ing.

  According to one aspect of the present embodiment, a reference substrate installation process for installing a reference substrate for inspection in a defect inspection apparatus, and irradiating light to the reference substrate for the installed inspection A light intensity measurement step for measuring the intensity of the scattered light of the light, and if the intensity of the scattered light is stronger than a set reference level, the power of the light is weakened, and the intensity of the scattered light is the reference level If it is weaker, a correction step for correcting the light power to be increased, a substrate to be inspected is installed in the defect inspection apparatus, and the light having the corrected power is set as the inspection target. And an inspection step of inspecting a defect in the substrate to be inspected by detecting scattered light of the irradiated light.

  Further, according to another aspect of the present embodiment, a substrate installation step of installing a substrate to be inspected in a defect inspection apparatus, a temperature measurement step of measuring a temperature in the defect inspection apparatus, and the temperature An offset setting step for setting an autofocus offset of light irradiated to the substrate to be inspected based on the above, and after the offset setting step, focusing by an autofocus function in the defect inspection apparatus, and thereafter An inspection step of inspecting a defect in the substrate to be inspected by irradiating the substrate to be inspected with light and detecting the scattered light of the light.

  Further, according to another aspect of the present embodiment, a light source that emits light to irradiate a reference substrate for inspection and a substrate to be inspected, a reference substrate for the inspection, and a target for inspection The intensity of the scattered light based on the intensity of the scattered light of the light irradiated to the substrate serving as a reference for the inspection, and the detection unit that detects the scattered light of the light among the light irradiated to the substrate And a light source correction unit that performs correction to weaken the power of the light when the level is higher than the set reference level and to increase the power of the light when the intensity of the scattered light is lower than the reference level.

  According to another aspect of the present embodiment, a light source that emits light to irradiate a substrate to be inspected, and an auto for autofocusing the light from the light source onto the substrate to be inspected. A focus unit, a temperature measurement unit that measures the temperature in the defect inspection apparatus, and a storage unit that stores a correlation table between the temperature in the defect inspection apparatus and the offset value of the autofocus, and Based on the correlation table, an autofocus offset value in the autofocus unit is set based on the temperature measured in the temperature measurement unit.

  According to the disclosed defect inspection method and defect inspection apparatus, a semiconductor wafer or the like can be inspected without overlooking a minute defect, and an accurate defect inspection can be performed.

The block diagram of the defect inspection apparatus in 1st Embodiment The principal part perspective view of the defect inspection apparatus in 1st Embodiment Flowchart (1) of the defect inspection method in the first embodiment Illustration of laser power adjustment Flowchart (2) of the defect inspection method in the first embodiment Correlation diagram of focus position and number of defects Correlation diagram of temperature and AF offset value Flowchart of defect inspection method according to second embodiment

  The form for implementing is demonstrated below.

[First Embodiment]
A defect inspection apparatus and a defect inspection method for semiconductor wafers and the like in the first embodiment will be described. The defect inspection apparatus and the defect inspection method for a semiconductor wafer or the like in the present embodiment are for inspecting a pattern collapse and a defect such as dust on the surface of the semiconductor wafer or the like (hereinafter sometimes simply referred to as “defect”). belongs to.

(Defect inspection equipment)
A defect inspection apparatus for semiconductor wafers and the like in this embodiment will be described with reference to FIG. A defect inspection apparatus 10 such as a semiconductor wafer according to the present embodiment includes a light source 11, an optical system 12, a control unit 13, a detection unit 14, an image processing unit 15, an output unit 16, and a stage 17.

  A laser light source is used as the light source 11 and includes a semiconductor laser and a drive circuit for driving the semiconductor laser.

  The optical system 12 includes an optical element such as a lens, and the light from the light source 11 is inclined with respect to the semiconductor wafer 31 which is a substrate to be inspected installed on the stage 17 via the optical system 12. Light is emitted from the direction.

  The control unit 13 is for controlling the entire defect inspection apparatus 10, and includes an AF unit 21, a temperature measurement unit 22, a light source correction unit 23, and a storage unit 24, and adjusts the power of the light source 11, Adjustment in the optical system 12 is performed.

  The AF unit 21 has a function of controlling autofocus (AF). Specifically, the autofocus control is performed by controlling the height of the stage 17.

  The temperature measuring unit 22 has a function of measuring the temperature in the defect inspection apparatus 10 and includes a thermometer and the like.

  The light source correction unit 23 has a function of adjusting the power of light through a drive circuit in the light source 11.

  The storage unit 24 stores a correlation table indicating a correlation between a temperature and an autofocus offset value, which will be described later.

  The detection unit 14 is for detecting the scattered light 41 out of the light irradiated to the semiconductor wafer 31 from the light source 11, and includes an imaging device and the like.

  The image processing unit 15 has a function of performing image processing based on information detected by the detection unit 14 and calculating the number of defects.

  The output unit 16 has a function of outputting the number of defects calculated in the image processing unit 15.

  The stage 17 is for installing the semiconductor wafer 31, and laser light focusing on the semiconductor wafer 31 is performed by adjusting the height of the stage 17.

  Next, the incident light 40 irradiated on the semiconductor wafer 31 and the scattered light 41 detected by the detector 14 will be described with reference to FIG. The semiconductor wafer 31 is irradiated with laser light as incident light 40 from the light source 11 through the optical system 12. Incident light 40 becomes scattered light 41 scattered and reflected light 42 reflected on the semiconductor wafer 31, and the scattered light 41 enters the detection unit 14. The detection unit 14 is provided with an image sensor via an optical system, and image detection is performed by the image sensor.

(Defect inspection method)
Next, the defect inspection method in the present embodiment will be described. The defect inspection method according to the present embodiment can accurately measure defects such as dust and pattern collapse in a semiconductor wafer or the like. For this reason, it is for preventing the noise component of the light detected in the detection part 14 from being misidentified as a defect, and for accurately focusing on the surface of the semiconductor wafer to be inspected. In the detection unit 14, if the noise component of light is mistaken as a defect, the accurate number of defects cannot be measured, and if it is not accurately focused on a semiconductor wafer or the like to be inspected, fine defects, etc. Is not measured, the number of defects cannot be measured accurately. Therefore, the inspection method in the present embodiment is an inspection method capable of more accurately grasping the number of defects.

(Laser light power adjustment)
The defect inspection method in the present embodiment will be described based on FIG. This inspection method prevents the laser light noise from being erroneously recognized as a defect, whereby the exact number of defects in the semiconductor wafer can be measured. That is, in the semiconductor wafer defect inspection apparatus, the laser beam output from the light source 11 is irradiated on the semiconductor wafer 31 via the optical system 12 and then detected by the detection unit 14. For this reason, the detection sensitivity in the detection unit 14 may fluctuate not only due to fluctuations in the output of the semiconductor laser itself that is the light source 11 but also due to changes over time in the optical system 12 and filters provided in the detection unit 14. Accordingly, after adjusting the power of the laser beam using an inspection reference wafer that is a substrate serving as a reference for inspection, a defect inspection of the semiconductor wafer that is the substrate to be inspected is performed.

  First, in step 102 (S102), an inspection reference wafer is set on the stage 17. This inspection reference wafer is a wafer for adjusting the laser power, and specifically, a wafer on which 0.1 μm fine particles are formed.

  Next, in step 104 (S104), the intensity of scattered light is measured. Specifically, the inspection reference wafer installed on the stage 17 is irradiated with laser light from the light source 11 via the optical system 12, and the light scattered from the inspection reference wafer among the irradiated laser light is detected by the detection unit 14. The intensity of the scattered light is measured from the detected value.

  Next, in step 106 (S106), it is determined whether or not the intensity of the scattered light measured in step 104 is within the reference intensity range. Specifically, the intensity value of the peak at a particle diameter of 0.1 μm detected by the inspection unit 14 is set as the intensity of the scattered light, and the determination is made based on whether or not the intensity value is within the reference intensity range. The If it is determined that the intensity of the scattered light is within the range of the reference intensity, the process proceeds to step 110. On the other hand, if it is determined that the intensity of the scattered light does not fall within the range of the reference intensity, the process proceeds to step 108. This reference strength is determined in advance.

  Next, in step 108 (S108), the laser power is corrected. Specifically, in the light source correction unit 23 in the control unit 13, when the intensity of the scattered light detected in step 104 is weaker than the reference intensity, the power of the laser light in the light source 11 is increased and is higher than the reference intensity. If it is strong, correction is made to weaken the power of the laser beam.

  This will be described with reference to FIG. FIG. 4A shows the relationship between the size of the detected particle and the luminance at the reference intensity. As shown in FIG. 4B, when the signal intensity detected by the detection unit 14, that is, the peak value of the 0.1 μm size particle is lower than the reference level, the light source correction unit 23 performs the light source 11. Control to increase the power of the laser beam. As a result, the peak value of the power of the laser beam can be raised to the reference level. Specifically, the current flowing through the semiconductor laser is increased by controlling the drive driver in the light source 11 from the light source correction unit 23. As shown in FIG. 4C, when the signal intensity detected by the detection unit 14, that is, the peak value of a 0.1 μm size particle is higher than the reference level, the light source correction unit 23 Control is performed to weaken the power of the laser beam in the light source 11. As a result, the peak value of the laser beam power can be lowered to the reference level. Specifically, the current flowing through the semiconductor laser is reduced by controlling the drive driver in the light source 11 from the light source correction unit 23.

  The threshold level is for removing a noise component contained in the laser beam or the like, and signals below the threshold level are not measured. Therefore, when the power of the laser beam is adjusted in this way, the noise level may fluctuate. Therefore, as shown in FIG. 4D, the threshold level is adjusted by applying the correction coefficient α. In this way, by adjusting the signal intensity detected by the detection unit 14, the noise level that changes depending on the signal intensity can be stabilized, and the noise level exceeds the threshold level. Can be prevented. That is, there is a correlation between the signal strength and the noise level, and the noise level increases as the signal strength increases. Therefore, if the noise level increases and exceeds the threshold level, noise caused by the light source 11 or the like may be erroneously recognized as a defect and measured, which is prevented. In other words, by adjusting the power of the laser beam in the light source 11, the noise level may also fluctuate, which may cause the noise level to exceed the threshold level. In this case, since noise due to the light source 11 and the like is measured as a defect, the threshold level is adjusted so that the noise level does not exceed the threshold level.

  Next, in step 110 (S110), the semiconductor wafer 31 is inspected for defects. Specifically, a semiconductor wafer 31 to be inspected is placed on the stage 17, and the semiconductor wafer 31 is irradiated with laser light from the light source 11 via the optical system 12, and scattered light 41 generated in the semiconductor wafer 31 is The light enters the detection unit 14. Based on the scattered light 41 incident on the detection unit 14, the number of defects is measured in the image processing unit 15 and output to the output unit 16.

  Incidentally, since the power of the laser beam in the light source 11 is adjusted by carrying out the steps 102 to 108, it is possible to continuously inspect defects of a plurality of semiconductor wafers thereafter.

  The semiconductor laser in the normal light source 11 is equipped with a photo detector for monitoring the amount of light, but control using this photo detector may not be sufficient. In the defect inspection method according to the present embodiment, it is possible to cope with power fluctuations caused by other than the light source 11, for example, power fluctuations caused by the optical system 12, the detection unit 14, or the like.

(Auto focus offset adjustment)
Next, the defect inspection method in the present embodiment will be described with reference to FIG. This inspection method relates to a method of offsetting an autofocus function mounted on an inspection apparatus such as a semiconductor wafer. In other words, in the state where the semiconductor wafer or the like to be inspected is not accurately focused, a fine defect image on the semiconductor wafer is blurred and cannot be accurately detected. For this reason, it is possible to accurately measure the number of defects by a simple method by appropriately offsetting an autofocus function mounted on an inspection apparatus such as a semiconductor wafer.

  First, in step 202 (S202), the semiconductor wafer 31, which is a substrate to be inspected, is placed on the stage 17.

  Next, in step 204 (S204), the temperature in the defect inspection apparatus 10 is measured. Specifically, the temperature measurement unit 22 in the control unit 13 measures the temperature inside the defect inspection apparatus 10 using a thermometer or the like.

  Next, in step 206 (S206), it is determined whether or not the temperature measured in step 204 is within the reference temperature range. If it is determined in step 204 that the measured temperature is within the reference temperature range, the process proceeds to step 210. On the other hand, if it is determined that the temperature measured in step 204 is not within the range of the reference temperature, the process proceeds to step 208.

  Next, in step 208 (S208), autofocus (AF) offset is performed. As mentioned above, there is no problem if it can be completely focused by the autofocus function installed in the defect inspection device. It may not be possible to respond sufficiently. Therefore, it is necessary to correct such an offset.

  FIG. 6 shows the relationship between the focus position and the number of defects measured. There is a relationship as shown in FIG. 6 between the focus position and the number of defects to be measured. In F1, which is the optimum focus position, the number of defects is the largest, and the optimum focus position is F2 or F3. When the position is shifted from the focus position, the number of measured defects decreases. This is considered to be due to the fact that the image detected by the detection unit 14 is blurred due to the defocus, and accurate measurement cannot be performed. Further, since the defect inspection apparatus 10 is an inspection method using light, the temperature in the defect inspection apparatus greatly affects the autofocus operation. Therefore, as shown in FIG. 7, the correlation between the temperature and the AF offset value is examined to create a correlation table, and this correlation table is stored in the storage unit 24 in the control unit 13.

  In the present embodiment, the correlation table of the correlation between the temperature and the AF offset as shown in FIG. 7 is created by determining the offset value for each temperature based on the autofocus position where the number of defects is the largest for each temperature. It is a thing. That is, F1 that is the optimum focus position shown in FIG. 6 is measured for each temperature, and an offset value for each temperature is determined and created based on F1 that is the optimum focus position.

  Specifically, the autofocus offset is obtained based on the correlation table stored in the storage unit 24, and the AF offset value is obtained from the temperature measured in step 204, and the autofocus is based on the offset value. Perform the offset. Thereafter, auto-focusing is performed by controlling the height of the stage 17 by the AF unit 21 in the control unit 13. Thereby, it is possible to accurately focus the light on the surface of the semiconductor wafer or the like.

  Next, in step 210 (S210), the semiconductor wafer 31 is inspected for defects. Specifically, after the autofocus offset in step 208 described above is performed, the semiconductor wafer 31 is autofocused by adjusting the height of the stage 17. Thereafter, the semiconductor wafer 31 is irradiated with laser light from the light source 11 via the optical system 12, and the scattered light 41 generated in the semiconductor wafer 31 enters the detection unit 14, and an image is based on the scattered light 41 incident on the detection unit 14. The number of defects is measured in the processing unit 15 and output to the output unit 16.

  In addition, since the autofocus offset is performed by performing steps 208 to 208, it is possible to continuously perform defect inspection of a plurality of semiconductor wafers thereafter.

  Thereby, the defect in a semiconductor wafer etc. can be measured correctly.

[Second Embodiment]
Next, a second embodiment will be described. This embodiment is a defect inspection method for a semiconductor wafer or the like that performs both laser beam power adjustment and autofocus offset adjustment using the defect inspection apparatus for the semiconductor wafer or the like in the first embodiment.

  The defect inspection method in the present embodiment will be described based on FIG.

  First, in step 302 (S302), an inspection reference wafer, which is a reference substrate for inspection, is placed on the stage 17. This is a wafer for adjusting the laser power, and specifically, a wafer in which fine particles of 0.1 μm are arranged on the surface.

  Next, in step 304 (S304), the intensity of scattered light is measured. Specifically, the inspection reference wafer installed on the stage 17 is irradiated with laser light from the light source 11 via the optical system 12, and the light scattered from the inspection reference wafer among the irradiated laser light is detected by the detection unit 14. The intensity of the scattered light is measured from the detected value.

  Next, in step 306 (S306), it is determined whether or not the intensity of the scattered light measured in step 304 is within the reference intensity range. Specifically, the intensity value of the peak at a particle diameter of 0.1 μm detected by the inspection unit 14 is set as the intensity of the scattered light, and the determination is made based on whether or not the intensity value is within the reference intensity range. The If it is determined that the intensity of the scattered light is within the range of the reference intensity, the process proceeds to step 310. On the other hand, if it is determined that the intensity of the scattered light does not fall within the range of the reference intensity, the process proceeds to step 308.

  Next, in step 308 (S308), laser power correction is performed. Specifically, in the light source correction unit 23 in the control unit 13, when the intensity of the scattered light detected in step 304 is weaker than the reference intensity, the power of the laser light in the light source 11 is increased so that it is higher than the reference intensity. If it is strong, correction is made to weaken the power of the laser beam.

  Next, in step 310 (S310), the semiconductor wafer 31, which is a substrate to be inspected, is placed on the stage 17.

  Next, in step 312 (S312), the temperature in the defect inspection apparatus 10 of the semiconductor wafer 31 is measured. Specifically, the temperature measurement unit 22 in the control unit 13 measures the temperature inside the defect inspection apparatus 10 using a thermometer or the like.

  Next, in step 314 (S314), it is determined whether or not the temperature measured in step 312 is within the reference temperature range. If it is determined that the temperature measured in step 312 is within the reference temperature range, the process proceeds to step 318. On the other hand, if it is determined that the temperature measured in step 312 is not within the reference temperature range, the process proceeds to step 316.

  Next, in step 316 (S316), the AF unit 21 performs autofocus (AF) offset.

  Next, in step 318 (S318), the semiconductor wafer 31 is inspected for defects. Specifically, after the autofocus offset in step 316 is performed, the semiconductor wafer 31 is autofocused by adjusting the height of the stage 17. Thereafter, the semiconductor wafer 31 is irradiated with laser light from the light source 11 via the optical system 12, and the scattered light 41 generated in the semiconductor wafer 31 enters the detection unit 14, and an image is based on the scattered light 41 incident on the detection unit 14. The number of defects is measured in the processing unit 15 and output to the output unit 16.

  Thereby, the defect in the semiconductor wafer 31 can be accurately measured. The contents other than the above are the same as in the first embodiment.

  Although the embodiment has been described in detail above, it is not limited to the specific embodiment, and various modifications and changes can be made within the scope described in the claims.

Regarding the above description, the following additional notes are disclosed.
(Appendix 1)
A standard substrate installation process in which a standard substrate for inspection is installed in the defect inspection apparatus;
A light intensity measurement step of irradiating a reference substrate for the installed inspection with light and measuring the intensity of scattered light of the irradiated light;
A correction step of performing correction to weaken the power of the light when the intensity of the scattered light is higher than a set reference level and to increase the power of the light when the intensity of the scattered light is weaker than the reference level; ,
By installing a substrate to be inspected in the defect inspection apparatus, irradiating the substrate to be inspected with light of the corrected power, and detecting scattered light of the irradiated light An inspection process for inspecting a defect in the substrate to be inspected;
A defect inspection method characterized by comprising:
(Appendix 2)
2. The defect inspection method according to appendix 1, wherein a plurality of fine particles having a predetermined size are provided on a surface of a substrate serving as a reference for the inspection.
(Appendix 3)
A substrate installation process for installing a substrate to be inspected in a defect inspection apparatus;
A temperature measuring step for measuring the temperature in the defect inspection apparatus;
An offset setting step for setting an autofocus offset of light irradiated on the substrate to be inspected based on the temperature;
After the offset setting step, focusing is performed by an autofocus function in the defect inspection apparatus, and then the substrate to be inspected is irradiated with the light to detect the scattered light. An inspection process for inspecting defects in the substrate,
A defect inspection method characterized by comprising:
(Appendix 4)
The offset setting step is set based on a correlation table of temperature and autofocus offset values in the defect inspection apparatus,
The correlation table defines a correlation between temperature and offset value based on a focus position where the number of defects on the substrate is the largest for each temperature in the defect inspection apparatus. The defect inspection method described in 1.
(Appendix 5)
The substrate to be inspected is placed on a stage in a defect inspection apparatus,
The defect inspection method according to appendix 3 or 4, wherein the autofocus is performed by adjusting a height of the stage.
(Appendix 6)
A light source that emits light to irradiate a reference substrate for inspection and a substrate to be inspected;
A detection unit for detecting scattered light of the light among the light irradiated on the substrate serving as a reference for the inspection and the substrate serving as the inspection target;
Based on the intensity of the scattered light of the light irradiated to the reference substrate for the inspection, if the intensity of the scattered light is stronger than a set reference level, the power of the light is reduced, and the intensity of the scattered light is A light source correction unit that performs correction to increase the power of the light when weaker than a reference level;
A defect inspection apparatus comprising:
(Appendix 7)
The defect inspection apparatus according to appendix 6, wherein a plurality of fine particles having a predetermined size are provided on a surface of a substrate serving as a reference for the inspection.
(Appendix 8)
A light source that emits light to irradiate a substrate to be inspected;
An autofocus unit for autofocusing light from the light source onto the substrate to be inspected;
A temperature measuring unit for measuring the temperature in the defect inspection apparatus;
A storage unit storing a correlation table between the temperature in the defect inspection apparatus and the offset value of the autofocus;
A defect inspection apparatus that sets an autofocus offset value in the autofocus unit based on the temperature measured in the temperature measurement unit based on the correlation table.
(Appendix 9)
The defect inspection apparatus has a stage for installing a substrate to be inspected,
The defect inspection apparatus according to appendix 8, wherein the autofocus is performed by adjusting a height of the stage.

DESCRIPTION OF SYMBOLS 10 Defect inspection apparatus 11 Light source 12 Optical system 13 Control part 14 Detection part 15 Image processing part 16 Output part 21 AF part 22 Temperature measurement part 23 Light source correction part 24 Storage part 30 Stage 31 Semiconductor wafer (substrate)
40 incident light 41 scattered light 42 reflected light

Claims (5)

A standard substrate installation process in which a standard substrate for inspection is installed in the defect inspection apparatus;
A light intensity measurement step of irradiating a reference substrate for the installed inspection with light and measuring the intensity of scattered light of the irradiated light;
A correction step of performing correction to weaken the power of the light when the intensity of the scattered light is higher than a set reference level and to increase the power of the light when the intensity of the scattered light is weaker than the reference level; ,
By installing a substrate to be inspected in the defect inspection apparatus, irradiating the substrate to be inspected with light of the corrected power, and detecting scattered light of the irradiated light An inspection process for inspecting a defect in the substrate to be inspected;
A defect inspection method characterized by comprising: A substrate installation process for installing a substrate to be inspected in a defect inspection apparatus;
A temperature measuring step for measuring the temperature in the defect inspection apparatus;
An offset setting step for setting an autofocus offset of light irradiated on the substrate to be inspected based on the temperature;
After the offset setting step, focusing is performed by an autofocus function in the defect inspection apparatus, and then the substrate to be inspected is irradiated with the light to detect the scattered light. An inspection process for inspecting defects in the substrate,
A defect inspection method characterized by comprising: The offset setting step is set based on a correlation table of temperature and autofocus offset values in the defect inspection apparatus,
The correlation table defines a correlation between a temperature and an offset value based on a focus position where the number of defects on the substrate is the largest for each temperature in the defect inspection apparatus. 2. The defect inspection method according to 2. A light source that emits light to irradiate a reference substrate for inspection and a substrate to be inspected;
A detection unit for detecting scattered light of the light among the light irradiated on the substrate serving as a reference for the inspection and the substrate serving as the inspection target;
Based on the intensity of the scattered light of the light irradiated to the reference substrate for the inspection, if the intensity of the scattered light is stronger than a set reference level, the power of the light is reduced, and the intensity of the scattered light is A light source correction unit that performs correction to increase the power of the light when weaker than a reference level;
A defect inspection apparatus comprising: A light source that emits light to irradiate a substrate to be inspected;
An autofocus unit for autofocusing light from the light source onto the substrate to be inspected;
A temperature measuring unit for measuring the temperature in the defect inspection apparatus;
A storage unit storing a correlation table between the temperature in the defect inspection apparatus and the offset value of the autofocus;
A defect inspection apparatus that sets an autofocus offset value in the autofocus unit based on the temperature measured in the temperature measurement unit based on the correlation table.

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