JP2003240723A - Method and apparatus for examining defect - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a method and an apparatus for examining defect capable of detecting a defect in high sensitivity even when a surface to be examined is in a non-mirror state. <P>SOLUTION: A laser beam Lb1 is radiated from a laser beam source 5 and a laser beam La1 is radiated from a laser beam source 3. The intensity of a regular reflecting light La2 detected by a detector 4 is processed as prescribed by a signal processing part 7, and then input to a haze value calculating part 8. The haze value calculated by the calculating part 8 is input to a controller 9 and a defect detecting part 11. The controller 9 sets a sampling frequency so as to perform at least three times of samplings for each haze undulation in response to the haze value. The intensity of the scattered light Lb2 is detected by a detector 6 in the set sampling frequency, processed as prescribed by a signal processing part 10, and then input to the defect detecting part 11. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defect inspection method and a defect inspection apparatus, and more particularly to a defect inspection method and a defect inspection apparatus for inspecting a semiconductor wafer having a non-mirror-like wafer surface.

[0002]

2. Description of the Related Art As a method for inspecting defects such as foreign substances adhered on the wafer surface of a bare wafer, the wafer surface is scanned with a laser beam that is narrowed into a beam shape, and scattered light caused by the defects is detected by a photodetector (photoelectron). A method of detecting with a multiplier tube or the like) is conventionally known. In this defect inspection method,
It is assumed that the bare wafer has a mirror-like wafer surface and that the intensity of scattered light generated in a defect-free portion is negligibly smaller than the intensity of scattered light caused by defects.

By the way, foreign substances are also generated by semiconductor manufacturing processes such as film formation and etching, and if these foreign substances adhere to the circuit pattern of the product, they may deteriorate the performance of the product or cause malfunction of the circuit. . Therefore, controlling the level of foreign matter generated during the process is essential for judging the quality of the process and maintaining the quality of the product. Therefore, as one of means for monitoring dust generation during the process and knowing the generation state thereof, a dust emission inspection of a device has been conventionally performed. This is because the process that is the target of dust emission monitoring is performed on a dummy bare wafer, and the defect inspection using the above laser light is performed on the wafer immediately after the process as the inspection target, so that the generation of foreign particles in the process. It monitors the situation.

[0004]

However, in the above-mentioned device dusting inspection, a defect inspection is performed on the wafer after the process is executed, but the surface of the wafer after the process is not roughened due to the process. It is usually formed to have a non-mirrored surface. For example, in the dust inspection of the film forming process, the surface of the film formed on the wafer surface of the bare wafer is roughened due to the execution of the film forming process. By the influence of the plasma used in
The surface of the bare wafer after the etching process is roughened.

In the defect inspection using the surface having the surface roughness as the inspection surface, even from a normal portion where no defect occurs,
Scattered light is generated due to surface roughness. Therefore, only scattered light that is considerably stronger than the intensity of scattered light due to surface roughness can be detected as scattered light due to defects. As a result, the size of a defect that can be detected becomes larger than that in the inspection for a mirror-shaped bare wafer, which may affect the circuit pattern.
There is a problem in that m-level foreign substances cannot be detected as defects.

When a film is formed on the surface,
There is a problem that the intensity of scattered light to be detected changes in the plane of the wafer or from wafer to wafer due to the influence of the type of film and interference, and the inspection conditions vary. Conventionally, to solve this,
An operator measures the reflectance of each of a plurality of sample wafers on which different types of films are formed, and creates a conversion table that describes the reflectance for each type of film based on the measurement results. A conversion table was created in anticipation of changes in reflectance within the plane.
However, the conversion table creation work by such an operator is complicated, and since the conversion table is not actually created using the wafer itself to be inspected, there is variation in each wafer. There was a problem that it was not reflected and accuracy was low.

The present invention has been made to solve the above problems, and even when the inspection surface is a non-mirror surface,
An object of the present invention is to obtain a defect inspection method and a defect inspection device capable of detecting defects with high sensitivity.

[0008]

[Means for Solving the Problems] Claim 1 of the present invention
The defect inspection method described in (a) irradiates a plurality of positions on the inspection surface with a first laser beam having a first wavelength, and the intensity of scattered light of the first laser beam at each of the positions. Respectively, and (b) creating a distribution of the number of the positions for each of the intensities of the scattered light based on the detection result in the step (a); And (d) determining that scattered light having a higher intensity than the predetermined intensity value in the distribution is caused by a defect, based on the step of setting a predetermined intensity value related to the intensity of the scattered light. And a process.

The defect inspection method according to a second aspect of the present invention is the defect inspection method according to the first aspect, wherein the step (c) includes (c-1) the distribution. Calculating a median value of the normal distribution when the area corresponding to the surface roughness of the inspection surface is regarded as the normal distribution;
2) setting the predetermined intensity value as a value obtained by adding a predetermined multiple of the standard deviation of the normal distribution to the median value.

The defect inspection method according to claim 3 of the present invention is the defect inspection method according to claim 1 or 2, wherein (e) the defect inspection method is performed on the plurality of positions in the inspection surface. A step of irradiating a second laser beam of a second wavelength and detecting the intensity of specularly reflected light of the second laser beam at each of the positions; and (f) the result of the detection in the step (e). Based on the surface roughness at each of the positions, in the step (a), the scattering is performed at a cycle of at least 1/4 of the cycle of the surface roughness calculated in the step (f). The intensity of the light is sampled.

The defect inspection method according to a fourth aspect of the present invention is the defect inspection method according to the third aspect, wherein the step (a) and the step (e) are performed in parallel. The first wavelength and the second wavelength are different from each other.

The defect inspection method according to claim 5 of the present invention is the defect inspection method according to claim 3 or 4, wherein the intensity of the scattered light is detected in the step (a). The sampling frequency in this case is changed according to the surface roughness determined in the step (f).

The defect inspection method according to claim 6 of the present invention is the defect inspection method according to claim 3 or 4, wherein the inspection body having the inspection surface is mounted on a predetermined stage. The irradiation of the first and second laser beams to the plurality of positions is realized by moving the stage, and the moving speed of the stage is determined in the step (f). It is characterized in that it is changed according to the surface roughness.

The defect inspection method according to claim 7 of the present invention is the defect inspection method according to claim 3 or 4, wherein the irradiation positions of the first and second laser lights are moved. As a result, the irradiation of the first and second laser beams to the plurality of positions is realized, and the first and second laser beams are emitted.
The moving speed of the irradiation portion of the laser light is changed according to the surface roughness determined in the step (f).

Further, in the defect inspection method according to claim 8 of the present invention, (a) a position within the inspection plane is irradiated with the first laser beam, and the first laser beam at the position is irradiated with the first laser beam. A step of detecting the intensity of scattered light; (b) a step of judging a defect at the position based on a result of the detection in the step (a); and (c) a second step for the position.
Of the regular reflection light of the second laser light at the position, and (d) the surface roughness at the position based on the detection result in the step (c). And the step (a)
Then, the intensity of the scattered light is sampled at a cycle of at least 1/4 of the cycle of the surface roughness calculated in the step (d).

The defect inspection method according to claim 9 of the present invention is the defect inspection method according to any one of claims 1 to 8, wherein (x) the reflectance of the inspection surface is When it is lower than a predetermined value, further comprising a step of increasing at least one of the intensity of the first laser light and the sensitivity of a detector that detects the intensity of the scattered light. is there.

According to a tenth aspect of the present invention, in the defect inspection method, (a) the inspection surface is irradiated with a first laser beam, and the intensity of scattered light of the first laser beam is set to a first level. Detecting with the detector of (1), and (b) the step (a)
And (c) irradiating the inspection surface with a second laser beam to determine the intensity of the specularly reflected light of the second laser light, based on the result of the detection in (1). A step of detecting with a second detector, and (d) the first detector detects that the intensity of the scattered light is lower than a predetermined value, and the intensity of the regular reflection light is lower than the predetermined value. And a step of increasing at least one of the intensity of the first laser beam and the sensitivity of the first detector when the second detector detects that it is low.

In the defect inspection apparatus according to claim 11 of the present invention, a first laser light source for irradiating a plurality of positions on the inspection surface with the first laser light of the first wavelength,
A first detector that detects the intensity of the scattered light of the first laser light at each of the positions, and based on the result of detection by the first detector, for each of the intensities of the scattered light, Creating a distribution of the number of positions, based on the distribution, set a predetermined intensity value related to the intensity of the scattered light, in the distribution, scattered light having a higher intensity than the predetermined intensity value, And a defect determination unit that determines that the defect is caused by

A defect inspection apparatus according to a twelfth aspect of the present invention is the defect inspection apparatus according to the eleventh aspect, wherein the defect determination section is configured to detect surface roughness of the inspection surface in the distribution. The median value of the normal distribution when the corresponding region is regarded as a normal distribution is determined, and the predetermined intensity value is set as a value obtained by adding a predetermined multiple of the standard deviation of the normal distribution to the median value. It is what

A defect inspection apparatus according to a thirteenth aspect of the present invention is the defect inspection apparatus according to the eleventh aspect or the twelfth aspect, wherein the defect inspection apparatus has a second position with respect to the plurality of positions in the inspection surface. A second laser light source for irradiating a second laser light having a wavelength; a second detector for detecting the intensity of specularly reflected light of the second laser light at each of the positions;
Based on the result of the detection in the detector, the indexing section for indexing the surface roughness at each of the positions, and the sampling cycle of the intensity of the scattered light, the surface roughness indexed by the indexing section. It further comprises a first control unit for controlling the cycle to be at least ¼ of the cycle.

A defect inspection apparatus according to a fourteenth aspect of the present invention is the defect inspection apparatus according to the thirteenth aspect, wherein the irradiation of the first laser beam and the irradiation of the second laser beam are performed. The irradiation is performed in parallel, and the first wavelength and the second wavelength are different from each other.

The defect inspection apparatus according to a fifteenth aspect of the present invention is the defect inspection apparatus according to the thirteenth or fourteenth aspects, wherein the first control section is configured to operate by the first detector. The sampling frequency for detecting the intensity of the scattered light is changed according to the surface roughness indexed by the indexing unit.

The defect inspection apparatus according to claim 16 of the present invention is the defect inspection apparatus according to claim 13 or 14, further comprising a stage on which an inspection object having the inspection surface is mounted. And irradiating the plurality of positions with the first and second laser beams by moving the stage, and the first controller controls the moving speed of the stage by the indexer. It is characterized in that it is changed according to the indexed surface roughness.

A defect inspection apparatus according to a seventeenth aspect of the present invention is the defect inspection apparatus according to the thirteenth or fourteenth aspects, wherein the irradiation points of the first and second laser beams are moved. Thereby, the irradiation of the first and second laser lights to the plurality of positions is realized, and the first control unit sets the moving speed of the irradiation position of the first and second laser lights to the split speed. It is characterized in that it is changed according to the surface roughness indexed at the projecting portion.

Further, in the defect inspection apparatus according to claim 18 of the present invention, a first laser light source for irradiating a position within an inspection plane with a first laser beam and the first laser light source at the position. A first detector that detects the intensity of scattered light of the laser light, a defect determination unit that determines a defect at the position based on the detection result of the first detector, and a second detector for the position. Second laser light source for irradiating the second laser light, a second detector for detecting the intensity of specularly reflected light of the second laser light at the position, and based on the detection result by the second detector. Then, the indexing section for indexing the surface roughness at the position and the sampling cycle of the intensity of the scattered light are set to be at least 1/4 of the cycle of the surface roughness indexed by the indexing section. With a control unit .

A defect inspection apparatus according to a nineteenth aspect of the present invention is the defect inspection apparatus according to any one of the eleventh to eighteenth aspects, wherein the reflectance of the inspection surface is greater than a predetermined value. When it is also low, a second control unit for increasing at least one of the intensity of the first laser light and the sensitivity of the first detector is further provided.

In the defect inspection apparatus according to claim 20 of the present invention, a first laser light source for irradiating the inspection surface with the first laser light and a scattered light of the first laser light are used. A first detector that detects the intensity, a defect determination unit that determines a defect on the inspection surface based on the result of detection by the first detector, and a second laser beam on the inspection surface. A second laser light source for irradiating, a second detector for detecting the intensity of specularly reflected light of the second laser light on the inspection surface, and the intensity of the scattered light being lower than a predetermined value. If the first detector detects and the second detector detects that the intensity of the specular reflection light is lower than a predetermined value, the intensity of the first laser beam and the first intensity of the first laser beam.
And a control unit for increasing at least one of the sensitivities of the detectors.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. FIG. 1 is a block diagram showing the configuration of the defect inspection apparatus according to the first embodiment of the present invention. A wafer 1 to be inspected having a wafer surface 1 a as an inspection surface is placed on a wafer stage 2. The wafer 1 to be inspected is a semiconductor wafer after a semiconductor manufacturing process such as film formation and etching has been executed, and the wafer surface 1a is
The surface is roughened so that it is non-mirror-like.

Near the wafer stage 2, laser light sources 3 and 5 and detectors 4 and 6 are arranged. From the laser light source 5, the laser light Lb1 having the first wavelength is emitted on the wafer surface 1a.
And the scattered light Lb2 is detected by the detector 6. The light receiving surface of the detector 6 is provided with a filter 6f that passes only the first wavelength (and wavelengths in the vicinity thereof). The regular reflection light Lb of the laser light Lb1
3 is not used for inspection. Further, although only one detector 6 for detecting scattered light is shown in FIG. 1, a plurality of detectors 6 may be provided in order to detect a large amount of minute scattered light.

Laser light La1 having a second wavelength different from the first wavelength is emitted from the laser light source 3 toward the wafer surface 1a, and the specularly reflected light La2 is detected by the detector 4. The light receiving surface of the detector 4 is provided with a filter 4f that passes only the second wavelength (and wavelengths in the vicinity thereof).

FIG. 2 shows that the laser beam La1 is emitted on the wafer surface 1a.
It is a schematic diagram which shows the situation where Lb1 is irradiated. The laser beam Lb1 has a beam diameter narrowed down to about several μm,
Irradiation is applied to an arbitrary point P on the wafer surface 1a.
The beam diameter of the laser light La1 is 1000 times or more larger than the beam diameter of the laser light Lb1, and the laser light La1 is applied to the region R including the irradiation point P. For example,
The laser light Lb1 is applied to a circular area having a predetermined radius centered on the irradiation point P.

Returning to the explanation of FIG. 1, the output of the detector 4 is connected to the input of the signal processing unit 7, and the output of the signal processing unit 7 is connected to the input of the haze value indexing unit 8. The output of the haze value indexing unit 8 is connected to each input of the control unit 9 and the defect determining unit 11. The output of the control unit 9 is connected to the input of the detector 6, and the output of the detector 6 is connected to the input of the signal processing unit 10. The output of the signal processing unit 10 is connected to the input of the defect determination unit 11, and the output of the defect determination unit 11 is connected to the input of the display unit 12.

FIG. 3 is a flow chart for explaining the defect inspection method according to the first embodiment of the present invention using the defect inspection apparatus shown in FIG. Hereinafter, the defect inspection method according to the first embodiment will be described with reference to FIGS. When the wafer 1 to be inspected is placed on the wafer stage 2 and the inspection is started, first, in step SP1, the region R in the wafer surface 1a is irradiated with the laser light La1 from the laser light source 3.

Next, in step SP2, the intensity of the regular reflection light La2 is detected by the detector 4. Detector 4
A signal S relating to the intensity of specular reflection light La2 output from
1 is a haze value indexing unit 8 as data D1 after signal processing such as amplification and A / D conversion is performed by the signal processing unit 7.
Entered in.

Next, in step SP3, the haze value corresponding to the surface roughness is calculated. Specifically, the haze value indexing unit 8 determines the intensity of the laser light La1 and the data D
Based on the intensity of the specular reflection light La2 represented as 1, the reflectance in the region R where the data D1 is obtained is calculated. Then, the haze value in the region R is calculated based on the calculated reflectance. Here, the intensity of the laser beam La1 is taught in advance in the haze value indexing unit 8, and the reflectance is obtained from the value and the intensity of the regular reflection light La2.

FIG. 4 is a top view showing a commercially available haze calibration wafer 13. The haze calibration wafer 13
Areas AR1 to AR6 having different haze values (known values)
Are formed. FIG. 5 is a graph showing the relationship between haze value and reflectance. Here, the haze value is represented as a polishing rotation speed (Revolutions Per Minute). The characteristic K representing the relationship between the haze value and the reflectance is obtained in advance by irradiating the areas AR1 to AR6 shown in FIG. 4 with the laser light La1 and detecting the intensity of the reflected light in each area. . The haze value indexing unit 8 corresponds to the reflectance of the region R by referring to the characteristic K or by referring to the conversion table in which the relationship between the haze value and the reflectance is described based on the characteristic K. You can calculate the haze value you want. Information regarding the calculated haze value is input to the control unit 9 and the defect determination unit 11 as data D2.

Next, in step SP4, the control unit 9
Thus, the sampling frequency is set according to the haze value of the region R represented as the data D2. Specifically, since the repetition period and the repetition frequency of the surface undulations (which are defined as “haze undulations” in the present specification) that give rise to haze are known from the data D2, at least three samplings are performed for each haze undulation. The sampling frequency is set to be four times or more the repetition frequency so that the above can be performed. This sampling frequency is reset every time the region R is updated by scanning the laser beam La1.

Next, in step SP5, the inspection point P included in the region R is irradiated with the laser light Lb1 from the laser light source 5. The laser light Lb1 updates the inspection point P and scans a plurality of positions within the wafer surface 1a. At this time, the laser beam La1 is scanned as necessary so that the region R includes the inspection point P.

Next, in step SP6, the intensity of the scattered light Lb2 is detected by the detector 6 at the sampling frequency set as described above. Since the laser beam Lb1 scans the wafer surface 1a, the signal S2 regarding the intensity of the scattered light Lb2 output from the detector 6 indicates the scattered light intensity at a plurality of positions on the wafer surface 1a. Detector 6
The signal S2 output from the wafer surface 1 after being subjected to signal processing such as amplification and A / D conversion by the signal processing unit 10.
The data D3 is input to the defect determination unit 11 in association with the position coordinates in a.

FIGS. 6 and 7 are diagrams showing how the scattered light intensity is detected by the detector 6. FIG. 6 shows the haze value H of the region R.
7 shows the detection situation when 1 is relatively large, and FIG.
Shows the detection situation when the haze value H2 of the region R is relatively small. In FIG. 6, a relatively high sampling frequency F1 is applied, whereas in FIG. 7, a relatively low sampling frequency F2 is applied. Figures 6 and 7
In, the envelope of the sampled values is shown by a broken line.
Since the sampling frequency is set based on the haze value, it is considered that the unevenness of the envelope corresponds to the surface profile of the wafer surface 1a at the position scanned by the laser beam Lb1.

Next, in step SP7, the defect determination section 11 creates a predetermined histogram.
Specifically, it is as follows. The defect determination unit 11 extracts the peak value of the scattered light intensity from a plurality of scattered light intensities corresponding to one cycle of repeated haze relief.
Then, by classifying for each peak value and counting the number of detections, a histogram in which the horizontal axis represents the scattered light intensity and the vertical axis represents the count number is created. This histogram is created for each haze value. FIG. 8 is a diagram showing a histogram relating to the haze value H1 corresponding to FIG. 6, and FIG. 9 is a diagram showing a histogram relating to the haze value H2 corresponding to FIG.

Next, in step SP8, the defect determination is performed by the statistical processing by the defect determination section 11. FIG. 10 is a flowchart for explaining the processing in step SP8 in detail. First, in step SP81, the data of the portion related to the surface roughened region R2 is extracted from the histograms shown in FIGS. The spatial frequency of surface roughness caused by the semiconductor manufacturing process is considered to be higher than the spatial frequency of surface undulations (defined herein as “defect-induced undulations”) due to defects and the spatial frequency of noise. Therefore, by performing frequency analysis, the surface roughness region R can be obtained from the histograms shown in FIGS.
Only the data for 2 can be extracted. For an example of frequency analysis, see, for example, Japanese Patent Laid-Open No. 11-18339.
No. 3 publication. The distribution of data regarding the surface roughened region R2 is regarded as a Gaussian distribution (normal distribution). Further, in FIGS. 8 and 9, the region R1 is a noise region.

Next, in step SP82, the median values M1 and M2 of the Gaussian distribution regarding the rough surface area R2 are determined. Next, in step SP83, the median value M
A predetermined distance L from 1, M2 in the direction of increasing scattered light intensity
Thresholds V1 and V2 of the scattered light intensity are set at locations separated by 1 and L2 (for example, 2σ or 3σ: σ is standard deviation). Next, in step SP84, a region in which the scattered light intensity is higher than the threshold values V1 and V2 is set as a defect region R3, and a position on the wafer surface 1a corresponding to the position coordinate of the data included in the defect region R3 is set. Detect the defects that are occurring. For example, the portion Q shown in FIG. 6 is highly likely to be detected as a defect.

Referring to FIG. 3, next, in step SP9, the defect determination section 11 creates data D4 concerning the positions and sizes of all the defects occurring in the wafer surface 1a, and the display section Enter in 12. On the display unit 12, the defect inspection result is displayed on the screen based on the data D4, whereby the inspection is completed.

In the above description, the control unit 9 changes the sampling frequency based on the data D2 regarding the haze value, but the following control may be performed while keeping the sampling frequency constant.

The first control is the laser beams La1 and L1.
When the scanning of the wafer surface 1a by b1 is realized by moving the wafer stage 2, the control unit 9
Depending on the haze value represented as data D2,
The moving speed of the wafer stage 2 may be changed. Specifically, the moving speed of the wafer stage 2 is relatively reduced in a region with a large haze value, and the movement speed of the wafer stage 2 is reduced in a region with a small haze value so that sampling can be performed at least three times for each of the haze undulations. Increase the moving speed relatively.

The second control is laser light La1, L
The scanning of the wafer surface 1a by b1 is performed by the laser beams La1 and L1.
When realized by moving the irradiation position of b1 (changing the trajectory), the control unit 9 determines the laser light La1, according to the haze value represented as the data D2.
You may change the moving speed of the irradiation location of Lb1. Specifically, in order to perform sampling at least three times for each of the haze undulations, the moving speed of the irradiation location is relatively reduced in the area with a large haze value, and the moving speed of the irradiation location in the area with a small haze value. Relatively raise.

With the first and second controls as described above, more detection values of scattered light intensity can be obtained for a region having a large haze value, and the same effect as when the sampling frequency is changed is obtained. be able to. However, in the case of using the first and second controls, the time required for the inspection tends to be longer than in the case of changing the sampling frequency. Conversely, when the sampling frequency is changed, the time required for the inspection does not become long, so that the throughput can be maintained.

As described above, according to the defect inspection apparatus and the defect inspection method according to the first embodiment, the threshold value of the scattered light intensity is appropriately set according to the haze value of each position on the wafer surface 1a. . Therefore, the wafer surface 1a has a non-mirror surface shape,
Even when the scattered light from the surface roughness is detected as noise by the detector 6, the defect can be detected with high sensitivity.

Further, since the threshold value is set by using the actually inspected wafer 1 itself, it is not affected by the variation of each semiconductor wafer, and is appropriate for each inspected wafer 1. You can set different thresholds.

Further, laser light La having different wavelengths from each other is used.
By using 1, Lb1, the step of irradiating the laser beam La1 and the step of irradiating the laser beam Lb1 can be performed in parallel. As a result, the time required for the inspection can be shortened as compared with the case where these steps are executed in different steps.

Embodiment 2. When the wafer 1 to be inspected is a wafer in which a film is formed on the surface of a bare wafer, the reflectance differs depending on the type of the film, and therefore the scattered light detected by the detector 6 depends on the type of the film formed. May decrease in intensity and may interfere with inspection. Second Embodiment
Now, a defect inspection device and a defect inspection method capable of avoiding such a situation will be described.

FIG. 11 is a block diagram showing the structure of the defect inspection apparatus according to the second embodiment of the present invention. The defect inspection apparatus according to the second embodiment is obtained by adding a control unit 20 to the defect inspection apparatus according to the first embodiment shown in FIG. The input of the control unit 20 is connected to the outputs of the detectors 4 and 6, and the output is connected to at least one of the inputs of the laser light source 5 and the detector 6.

The operation of the controller 20 will be described below. The control unit 20 determines whether or not the intensity of the regular reflection light La2 is lower than a predetermined value set in advance, based on the signal S1 input from the detector 4. If it is lower than the predetermined value, it is confirmed based on the signal S2 input from the detector 6 whether the intensity of the scattered light Lb2 is lower than a predetermined value set in advance. When both the intensity of the regular reflection light La2 and the intensity of the scattered light Lb2 are low, it means that the reflectance of the film formed on the surface is low. Therefore, the control unit 20 uses the control signal S4 to adjust the gain or dynamics of the laser light source 5. The range is adjusted to increase the intensity of the laser light Lb1. Alternatively, the gain and dynamic range of the detector 6 are adjusted by the control signal S5 to increase the sensitivity of the detector 6.
Alternatively, when the reflectance of the formed film is extremely low, both of them are controlled.

As described above, according to the defect inspection apparatus and the defect inspection method according to the second embodiment, it is possible to compensate the variation in the reflectance for each type of film by the automatic control by the control unit 20. In addition, even if the films of the same type have slightly different reflectances, the defect inspection apparatus and the defect inspection method according to the second preferred embodiment can detect the actually inspected wafer 1 itself. Since compensation variation control of reflectance is performed by using this, it is possible to appropriately deal with such a situation.

[0056]

According to the first aspect of the present invention, since the predetermined intensity value can be appropriately set based on the distribution of the intensity of scattered light, the scattered light caused by the defect can be appropriately determined. be able to.

According to the second aspect of the present invention, the predetermined intensity value can be set to an appropriate value by the statistical processing.

According to the third aspect of the present invention, since the intensity of scattered light can be appropriately sampled according to the surface roughness of the inspection surface, an appropriate distribution can be obtained in step (b). it can.

According to the fourth aspect of the present invention, the steps (a) and (e) are performed in parallel by using the first and second laser beams having different wavelengths. Can be executed. As a result, the time required for the inspection can be shortened as compared with the case where the step (a) and the step (e) are performed in separate steps.

According to the fifth aspect of the present invention, the simple control of changing the sampling frequency according to the surface roughness allows the surface roughness to be adjusted without increasing the time required for the inspection. Appropriate sampling can be achieved.

Further, according to the sixth aspect of the present invention, proper sampling according to the surface roughness can be realized by the simple control of changing the moving speed of the stage according to the surface roughness.

According to the seventh aspect of the present invention, the surface roughness can be reduced by the simple control of changing the moving speeds of the irradiation portions of the first and second laser beams according to the surface roughness. Appropriate sampling can be realized depending on the situation.

According to the eighth aspect of the present invention, since the intensity of scattered light can be appropriately sampled according to the surface roughness of the inspection surface, an appropriate defect determination can be made in step (b). You can

According to the ninth aspect of the present invention, it is possible to compensate for the variation in the reflectance of the inspection surface between the inspection objects.

According to the tenth aspect of the present invention, it is possible to compensate the variation in the reflectance of the inspection surface between the inspection objects.

According to the eleventh aspect of the present invention, since the predetermined intensity value can be appropriately set based on the distribution of the scattered light intensity, the scattered light caused by the defect can be appropriately determined. be able to.

According to the twelfth aspect of the present invention, the predetermined intensity value can be set to an appropriate value by the statistical processing.

According to the thirteenth aspect of the present invention, since the intensity of scattered light can be appropriately sampled according to the surface roughness of the inspection surface, an appropriate distribution can be obtained in the defect determining section. .

According to the fourteenth aspect of the present invention, by using the first and second laser beams having different wavelengths, the first laser beam irradiation and the second laser beam irradiation are performed.
The irradiation with the laser light can be executed in parallel.
As a result, the time required for the inspection can be shortened as compared with the case where the irradiation of the first and second laser lights is performed in separate steps.

Further, according to the fifteenth aspect of the present invention, the simple control of changing the sampling frequency according to the surface roughness can be performed according to the surface roughness without increasing the time required for the inspection. Appropriate sampling can be achieved.

Further, according to the sixteenth aspect of the present invention, the appropriate sampling according to the surface roughness can be realized by the simple control of changing the moving speed of the stage according to the surface roughness.

According to the seventeenth aspect of the present invention, the surface roughness can be reduced by the simple control of changing the moving speeds of the irradiation portions of the first and second laser beams according to the surface roughness. Appropriate sampling can be realized depending on the situation.

According to the eighteenth aspect of the present invention, since the intensity of scattered light can be appropriately sampled in accordance with the surface roughness of the inspection surface, the defect determining section can appropriately perform the defect determination. it can.

According to the nineteenth aspect of the present invention, it is possible to compensate the variation in the reflectance of the inspection surface between the inspection objects.

According to the twentieth aspect of the present invention, it is possible to compensate for the variation in the reflectance of the inspection surface between the inspection objects.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a defect inspection apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a situation in which a laser beam is applied to a wafer surface.

FIG. 3 is a flowchart for explaining the defect inspection method according to the first embodiment of the present invention.

FIG. 4 is a top view showing a haze calibration wafer.

FIG. 5 is a graph showing the relationship between haze value and reflectance.

FIG. 6 is a diagram showing how scattered light intensity is detected.

FIG. 7 is a diagram showing how scattered light intensity is detected.

FIG. 8 is a diagram showing a histogram relating to a haze value H1 corresponding to FIG.

9 is a diagram showing a histogram relating to a haze value H2 corresponding to FIG. 7. FIG.

FIG. 10 is a flowchart for explaining in detail the processing in step SP7.

FIG. 11 is a block diagram showing a configuration of a defect inspection device according to a second embodiment of the present invention.

[Explanation of symbols]

1 wafer to be inspected, 1a wafer surface, 2 wafer stage, 3, 5 laser light source, 4, 6 detector, 9, 20
Control unit, 11 Defect determination unit.

Claims (20)

[Claims] 1. A method comprising: (a) irradiating a plurality of positions on an inspection surface with a first laser beam having a first wavelength, and detecting the intensity of scattered light of the first laser beam at each of the positions. And (b) based on the result of the detection in the step (a),
Creating a distribution of the number of the positions for each intensity of the scattered light; (c) setting a predetermined intensity value related to the intensity of the scattered light based on the distribution; (d) A defect inspection method comprising: determining scattered light having an intensity higher than the predetermined intensity value in the distribution as being caused by a defect. 2. The step (c) includes: (c-1) determining a median value of the normal distribution when a region of the distribution corresponding to the surface roughness of the inspection surface is regarded as a normal distribution. 2. The defect inspection method according to claim 1, further comprising the step of: (c-2) setting the predetermined intensity value as a value obtained by adding a predetermined multiple of the standard deviation of the normal distribution to the median value. 3. The intensity of specularly reflected light of the second laser light at each of the positions, which is obtained by irradiating the plurality of positions on the inspection surface with a second laser light having a second wavelength. And (f) based on the result of the detection in the step (e),
The method further comprises the step of respectively calculating the surface roughness at each of the positions, and in the step (a), the scattered light is scattered at a cycle of at least 1/4 of the cycle of the surface roughness calculated in the step (f). The defect inspection method according to claim 1, wherein the intensity is sampled. 4. The defect inspection method according to claim 3, wherein the step (a) and the step (e) are performed in parallel, and the first wavelength and the second wavelength are different from each other. 5. The sampling frequency for detecting the intensity of the scattered light in the step (a) is changed according to the surface roughness determined in the step (f). 4. The defect inspection method described in 4. 6. The inspection body having the inspection surface is placed on a predetermined stage, and by moving the stage, irradiation of the first and second laser beams onto the plurality of positions is performed. It is realized and the moving speed of the stage is changed according to the surface roughness determined in the step (f).
The defect inspection method described in. 7. The irradiation of the first and second laser lights to the plurality of positions is realized by moving the irradiation positions of the first and second laser lights, and the irradiation of the first and second laser lights is realized. The moving speed of the laser light irradiation location is
The defect inspection method according to claim 3 or 4, which is changed according to the surface roughness determined in the step (f). 8. (a) A step of irradiating a position on the inspection surface with a first laser beam and detecting the intensity of scattered light of the first laser beam at the position, and (b) the step. Based on the result of detection in (a),
Determining a defect at the position, (c) irradiating the position with a second laser beam, and detecting the intensity of specularly reflected light of the second laser beam at the position, (d) ) Based on the result of the detection in the step (c),
Determining the surface roughness at the position, wherein in the step (a), the intensity of the scattered light is sampled at a cycle of at least 1/4 of the cycle of the surface roughness calculated in the step (d). Defect inspection method. 9. (x) Of the intensity of the first laser light and the sensitivity of a detector that detects the intensity of the scattered light when the reflectance of the inspection surface is lower than a predetermined value. 9. The method according to claim 1, further comprising the step of raising at least one side.
The defect inspection method described in any one of 1. 10. (a) A step of irradiating an inspection surface with a first laser beam and detecting the intensity of scattered light of the first laser beam by a first detector, and (b) the step. Based on the result of detection in (a),
Determining a defect on the inspection surface, and (c) irradiating the inspection surface with a second laser beam, and detecting the intensity of specularly reflected light of the second laser beam with a second detector. And (d) the first detector detects that the intensity of the scattered light is lower than a predetermined value, and the second detection that the intensity of the specular reflection light is lower than a predetermined value. Defect detection apparatus, which increases at least one of the intensity of the first laser light and the sensitivity of the first detector when detected by a detector. 11. A first laser light source for irradiating a plurality of positions on the inspection surface with a first laser light having a first wavelength, and the intensity of scattered light of the first laser light at each position. First detector to detect each, based on the result of the detection in the first detector, for each of the intensity of the scattered light, to create a distribution of the number of the positions, based on the distribution, A predetermined intensity value related to the intensity of the scattered light is set, and a scattered light having a higher intensity than the predetermined intensity value in the distribution is provided with a defect determination unit that determines that the defect is caused by a defect. Inspection device. 12. The defect determination unit calculates a median value of the normal distribution when a region of the distribution corresponding to the surface roughness of the inspection surface is regarded as a normal distribution, and determines a standard deviation of the normal distribution. The defect inspection apparatus according to claim 11, wherein the predetermined intensity value is set as a value obtained by adding several times to the median value. 13. A second laser light source for irradiating the plurality of positions on the inspection surface with a second laser light having a second wavelength, and specular reflection of the second laser light at each of the positions. A second detector for detecting the intensity of light, an indexing unit for determining the surface roughness at each of the positions based on the detection result of the second detector, and sampling of the intensity of the scattered light. At least one of the cycles of the surface roughness indexed by the indexing part
Further comprising a first control unit for controlling a cycle of / 4,
The defect inspection apparatus according to claim 11. 14. The irradiation with the first laser light and the irradiation with the second laser light are performed in parallel, and the first wavelength and the second wavelength are different from each other. The defect inspection device described in 1. 15. The first control unit sets a sampling frequency for detecting the intensity of the scattered light by the first detector according to the surface roughness indexed by the indexing unit. The defect inspection apparatus according to claim 13 or 14, which is changed. 16. The apparatus further comprises a stage on which an inspection object having the inspection surface is placed, and by moving the stage, irradiation of the first and second laser beams to the plurality of positions is realized, The first control unit changes the moving speed of the stage according to the surface roughness indexed by the indexing unit,
The defect inspection apparatus according to claim 13 or 14. 17. The irradiation of the first and second laser lights to the plurality of positions is realized by moving the irradiation positions of the first and second laser lights, and the first controller is The defect inspection apparatus according to claim 13 or 14, wherein the moving speed of the irradiation location of the first and second laser light is changed according to the surface roughness indexed by the indexing section. 18. A first laser light source for irradiating a position on the inspection surface with a first laser light having a first wavelength, and detecting the intensity of scattered light of the first laser light at the position. A first detector, a defect determination unit that determines a defect at the position based on a result of detection by the first detector, and irradiates the position with a second laser beam having a second wavelength. A second laser light source, a second detector that detects the intensity of specularly reflected light of the second laser light at the position, and a second detector at the position based on the detection result of the second detector. An indexing section for indexing the surface roughness, and a sampling cycle of the intensity of the scattered light, at least one of the cycle of the surface roughness indexed by the indexing section.
A defect inspection apparatus comprising: a control unit for setting a cycle of / 4. 19. A second control for increasing at least one of the intensity of the first laser beam and the sensitivity of the first detector when the reflectance of the inspection surface is lower than a predetermined value. The defect inspection apparatus according to claim 11, further comprising a section. 20. A first laser light source that irradiates an inspection surface with a first laser light having a first wavelength, and a first detector that detects the intensity of scattered light of the first laser light. A defect determination unit that determines a defect on the inspection surface based on a result of detection by the first detector, and a second irradiation unit that irradiates the inspection surface with a second laser beam having a second wavelength. A laser light source, a second detector that detects the intensity of specularly reflected light of the second laser light on the inspection surface, and the first detector that the intensity of the scattered light is lower than a predetermined value. If the second detector detects that the intensity of the specular reflection light is lower than a predetermined value, the intensity of the first laser light and the sensitivity of the first detector, A defect inspection apparatus comprising: a control unit that raises at least one of the above.