JP2000009654A - Device and method for inspecting surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily, rapidly, and accurately detect the contamination state of a sample surface. SOLUTION: A sample 2 is scanned by a laser beam for detecting the intensity of s and p polarization components of reflected light individually, RR that is the intensity ratio of the s and p polarization components is calculated for each application region of the surface of the sample 2, and the occurrence frequency of each value of RR is detected for each specific analysis compartment consisting of a plurality of application regions, and the corresponding relationship between each value of the RR and the occurrence frequency is detected for each analysis compartment of the surface of the sample 2 according to the detection result. The corresponding relationship reflects the contamination state of the surface of the sample 2 and each kind of influence is canceled since the RR is the ratio of two light constituents.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention inspects the quality of a microscopically rough surface of a sample made of a material having a good reflectivity, such as a metal wiring formed on the surface of a semiconductor wafer. The present invention relates to a surface inspection apparatus and method.

[0002]

2. Description of the Related Art Conventionally, in a process of manufacturing an integrated circuit, a metal wiring is formed as a fine pattern on a surface of a semiconductor wafer, and, for example, a bonding wire or a connection terminal of a chip component is connected to the metal wiring.

[0003] However, if the surface of the metal wiring is contaminated during the manufacturing process, the contaminant causes electrical connection failure and insufficient bonding strength. Therefore, in the process of manufacturing an integrated circuit, it is important to improve the yield of the integrated circuit by inspecting and analyzing the state of contamination on the surface of the metal wiring, investigating the cause and taking countermeasures.

As described above, in order to manufacture an integrated circuit with a good yield, it is necessary to inspect and analyze the contamination state of the surface of the metal wiring. However, since the surface of the metal wiring is microscopically rough, it is difficult to analyze fine contamination on the surface. In particular, when the contaminant is a composite material of an organic substance and an inorganic substance, it is extremely difficult to analyze the substance well.

At present, as a basic research on the surface inspection of a fine structure as described above, a scanning tunneling microscop (STM) is used.
Although surface inspection on the nanoscale using e) or AFM (Atomic Force Microscope) has been performed, this is not practical because analysis requires a great deal of time and money.

In addition, FTIR (FIR
Surface inspection by ourier Transform Infrared Spectroscope (Spectroscope) spectroscopy has also been carried out, but this is not practical because trace analysis is difficult and operation is complicated, and again analysis requires a great deal of time and cost.

Therefore, as a surface inspection method which has solved the above-mentioned problem, a polarization analysis method is used in which a surface of a sample is irradiated with light rays and reflected, and a surface inspection is performed from the polarization component.
(Ellipsometry method). This allows for micro-analysis and is easy to operate, and does not require much time and money for analysis.

[0008]

In the above-mentioned ellipsometry, the surface of the sample can be easily inspected, but it is premised that the surface of the sample to be inspected is a mirror surface. However, when the sample is an integrated circuit in the manufacturing process, fine metal wiring is formed on the surface of the mirror-like semiconductor wafer by sputtering or electrolytic plating, and the surface is microscopically rough. is there.

When a conventional ellipsometry is applied to the surface of such a sample, light rays are irregularly reflected due to microscopic irregularities on the surface of the sample, so that it is difficult to perform an accurate inspection. That is, the state of the surface of the integrated circuit in the manufacturing process, which is the sample, cannot be inspected, and it cannot contribute to the improvement of the yield of the integrated circuit.

[0010] Further, as defects occurring on the surface of the integrated circuit during the manufacturing process, there are contamination by an inorganic substance, contamination by an organic substance, contamination by a mixture of an inorganic substance and an organic substance, adhesion of a foreign substance, and the like. Inspection is difficult with conventional ellipsometry.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and can satisfactorily change the state of the surface of a sample such as a semiconductor wafer having metal wiring formed thereon without requiring much time and cost. It is an object of the present invention to provide a surface inspection apparatus and method capable of inspecting and analyzing.

[0012]

A first surface inspection apparatus according to the present invention comprises a sample holding means for holding a sample, and a laser beam condensing and irradiating the surface of the sample held by the sample holding means. Laser irradiation means, relative scanning means for relatively moving the laser irradiation means and the sample holding means and two-dimensionally scanning a laser beam irradiated on a predetermined irradiation area on the sample surface, and two-dimensional scanning Polarization detection means for individually detecting the intensity of each of the s-polarized component and the p-polarized component of the laser beam reflected by the irradiation area of the sample surface;
RR (Reflectance Ratio) which is the ratio of the reflection intensity between the s-polarized light component and the p-polarized light component detected by the polarization detecting means.
Ratio calculation means for calculating for each irradiation area of the sample surface,
Frequency detecting means for detecting the frequency of occurrence of each value of RR calculated by the ratio calculating means for each predetermined analysis section comprising a plurality of irradiation areas; and for each analysis section on the sample surface from the detection result of the frequency detection means. It is also possible to provide a surface inspection apparatus including a relationship detection unit that detects a correspondence relationship between each value of RR and the occurrence frequency.

Therefore, in the surface inspection method of the surface inspection apparatus according to the present invention, the laser beam is condensed and irradiated by the laser irradiation means on the surface of the sample held by the sample holding means. The sample holding means and the sample holding means are relatively moved by the relative scanning means, and the laser beam applied to a predetermined irradiation area on the sample surface is two-dimensionally scanned. The s-polarized light component of the laser beam that is two-dimensionally scanned and reflected by the irradiation area on the sample surface and p
The respective intensities of the polarization components are individually detected by the polarization detection means, and RR, which is the ratio of the reflection intensity of the s-polarization component to the p-polarization component, is calculated for each irradiation area on the sample surface by the ratio calculation means. . The frequency of occurrence of each value of RR calculated in this manner is detected by the frequency detection means for each predetermined analysis section composed of a plurality of irradiation areas, and from the detection result, the RR of each sample is analyzed by the relation detection means for each analysis section on the sample surface. The correspondence between each value and the occurrence frequency is detected. Since this correspondence represents the frequency of occurrence of each value of RR in a predetermined analysis section on the sample surface, this reflects the contamination state of the sample surface. Moreover, the state of the sample surface is s
Since the inspection is performed based on the ratio of the reflection intensity between the polarized light component and the p-polarized light component, even if the surface of the sample is microscopically rough, the influence is canceled and a good result is detected.

Here, the basic principle of the present invention will be verified below. First, in the case of metal wiring of a circuit component in which a sample is mass-produced, the surface thereof is hardly microscopically mirror-like, and the laser beam applied thereto is substantially irregularly reflected.
Therefore, the reflection intensity Ro of the s / p polarized light on such a rough surface.
In the present invention, s and Rop are approximated as follows.

Ros = Rou × Rs (1a) Rop = Rou × Rp (1b) where Rou is the specular reflectivity on the rough surface, and Rs and Rp are s on the smooth surface calculated by Drude's reflection formula. / P is the amplitude reflectance of polarized light.

If the surface of the sample is unevenly contaminated, the amplitude reflectances Rs and Rp of the s / p polarized light will be complicatedly modified. The ratio of the above formulas (1a) and (1b) becomes the ratio RR of the reflection intensity of the s / p polarized light as shown in the following formula (2).

RR = Ros / Rop = (Rou × Rs) / (Rou × Rp) = Rs / Rp (2) The reflection intensity of the s / p polarized light depends on the roughness of the sample surface and the characteristics of the apparatus. Constants are present as well, but these constants will necessarily be offset by the ratio RR. However, since the interaction between the s-polarized light and the p-polarized light is different from the interaction between the photoelectric field and the material surface, the ratio of the change in the reflection intensity due to the contaminant is not the same.

Therefore, the state of the contamination can be detected while eliminating the influence of the roughness of the sample surface by the RR. Therefore, in the present invention, the state of the sample surface is analyzed by using the above equation (2). . Since the formula for calculating RR is simple as described above, the calculation can be performed easily and quickly.

The second surface inspection apparatus of the present invention comprises a sample holding means for holding a sample, a laser irradiation means for condensing and irradiating a laser beam on the surface of the sample held by the sample holding means, A relative scanning unit configured to relatively move the laser irradiation unit and the sample holding unit to two-dimensionally scan a laser beam applied to a predetermined irradiation area on the sample surface; and to irradiate the sample surface scanned two-dimensionally. Polarization detecting means for individually detecting the intensity of each of the s-polarized light component and the p-polarized light component of the laser beam reflected by the region; and the reflection intensity of the s-polarized light component and the p-polarized light component detected by the polarization detecting means. Ratio calculating means for calculating the ratio RR for each irradiation area on the sample surface, and RR calculated by the ratio calculating means
And a relationship detecting means for detecting a correspondence relationship between each value of the above and a plurality of irradiation regions forming a predetermined analysis section.

Therefore, according to the surface inspection method of the surface inspection apparatus of the present invention, the laser beam is condensed and irradiated by the laser irradiation means on the surface of the sample held by the sample holding means. The sample holding means and the sample holding means are relatively moved by the relative scanning means, and the laser beam applied to a predetermined irradiation area on the sample surface is two-dimensionally scanned. The s-polarized light component of the laser beam that is two-dimensionally scanned and reflected by the irradiation area on the sample surface and p
The respective intensities of the polarization components are individually detected by the polarization detection unit, and RR, which is the ratio of the reflection intensity of the s-polarization component to the reflection intensity of the p-polarization component, is calculated for each irradiation area of the sample surface by the ratio calculation unit, The correspondence between each value of RR calculated in this way and the plurality of irradiation areas is detected by the relation detection means for each analysis section. Since this correspondence expresses each value of RR in a predetermined analysis section on the sample surface for each of the plurality of irradiation areas, this reflects the contamination state of the sample surface. Moreover, since the state of the sample surface is inspected from the ratio of the reflection intensity of the s-polarized light component to the reflection intensity of the p-polarized light component, even if the surface of the sample is microscopically rough, the influence is canceled and a good result is detected. You.

In the above-described surface inspection apparatus, the relation detecting means can generate a two-dimensional graph in which one of the RR values and the occurrence frequency is a vertical axis and the other is a horizontal axis. In this case, a two-dimensional graph in which one of the values of RR and the frequency of occurrence is one axis of the ordinate and the other axis of the abscissa is generated by the relation detecting means, so that the contamination state of the sample surface can be confirmed at a glance by the two-dimensional graph. Expressed in state.

In the above-described surface inspection apparatus, the relation detecting means may be arranged such that the analysis section has a lower surface and the RR for each irradiation area is different.
It is also possible to generate a three-dimensional graph with each value of the vertical axis. In this case, since the three-dimensional graph in which the analysis section is the lower surface and each value of RR for each irradiation region is on the vertical axis is generated by the relation detecting means, the contamination state of the sample surface can be confirmed at a glance by the three-dimensional graph. Is expressed.

In the above-described surface inspection apparatus, the relation detecting means may generate a two-dimensional graph in which the analysis section is represented by a plane and each value of RR for each irradiation area is represented by a predetermined color. It is possible. In this case, a two-dimensional graph in which the analysis section is represented by a plane and each value of RR for each irradiation region is represented by a predetermined color is generated by the relation detecting means. Is expressed in a state that can be confirmed at a glance.

In the above-described surface inspection apparatus, it is possible to further include image display means for displaying the detection result of the relation detection means in an image. in this case,
Since a two-dimensional graph or a three-dimensional graph, which is a detection result of the relationship detecting means, is displayed as an image by the image display means, the state of contamination on the sample surface can be confirmed at a glance by the displayed image.

Generally, when the surface of a sample is clean, RR
Only a specific numerical value is generated at a high frequency in a concentrated manner, but the frequency of occurrence of a numerical value deviating from the numerical value is extremely reduced. For example, the shape of a curve in a two-dimensional graph is steep. On the other hand, if the surface of the sample is contaminated, the value of RR that occurs frequently changes, and the frequency of occurrence of values that deviate from the value also increases relatively. Therefore, the shape of the curve in the two-dimensional graph changes. Not steep.

Further, as described above, when the surface of the sample is contaminated, the value of RR frequently generated also generally changes, so that the position of the range where the value of RR occurs at a predetermined frequency also changes. . Furthermore, if the contaminant on the sample surface is an inorganic substance, the value of RR generated frequently increases, and if the contaminant is an organic substance, the value of RR decreases.

For this reason, as described above, the surface inspection apparatus uses the surface inspection apparatus to determine the correspondence between the RR value and the frequency of occurrence for each analysis section on the sample surface, the plurality of irradiation regions forming a predetermined analysis section, and the RR. If the correspondence with the values is detected and such a detection result is displayed as an image as a two-dimensional graph or a three-dimensional graph, the state of contamination on the sample surface can be determined from the displayed image.

According to the surface inspection method of the present invention, it is possible to determine the presence or absence of contamination on the sample surface based on the frequency of occurrence of a specific value of RR. It is also possible to determine the presence or absence of contamination on the sample surface based on the size of the range in which the value of RR occurs at a predetermined frequency. If the value of RR at which the frequency of occurrence peaks is higher than the reference value, it is possible to determine that the contamination of the sample is due to an inorganic substance, and to determine that the contamination is due to an organic substance when it is low. Further, when the position of the range where the value of RR occurs at a predetermined frequency is higher than the reference position, it is possible to determine that the contamination of the sample is due to the inorganic substance, and when it is low, it is possible to determine that the contamination is due to the organic substance. Further, when the position of the range where the value of RR occurs at a predetermined frequency is wider than the reference range, it is possible to determine that the contamination of the sample is caused by the mixture of the inorganic substance and the organic substance.

Therefore, as a surface inspection apparatus of the present invention which has realized the above-described surface inspection method, it is possible to provide a contamination determination means for determining the presence or absence of contamination on the sample surface from the detection result of the relation detection means. , This contamination determination means,
It is also possible to determine whether the contamination of the sample is due to an inorganic substance, an organic substance or a mixture from the detection result of the relation detecting means.

Further, in the above-described surface inspection apparatus, an intensity comparing means for comparing the reflection intensity of the s-polarized light component detected by the polarization detecting means with a predetermined reference intensity, and a reflection result as a comparison result of the intensity comparing means. If the intensity is lower than the reference intensity, it is possible to further comprise a foreign matter determining means for determining that foreign matter is present in the analysis section on the sample surface.

In this case, the reflection intensity of the s-polarized light component detected by the polarization detecting means is compared with a predetermined reference intensity by the intensity comparing means. As a result of this comparison, if the reflection intensity is lower than the reference intensity, the foreign matter judging means determines the surface of the sample. It is determined that a foreign substance is present in the analysis section of the sample, and if a foreign substance is present in the analysis section on the sample surface, this is detected.

When the presence / absence of a foreign substance is determined for each analysis section as described above, for example, if one analysis section has 400 irradiation areas, the reflection of the s-polarized light component may occur in several irradiation areas. Even if the intensity is smaller than the reference intensity, it is preferable that the presence of the foreign object is not determined if the reflection intensity of the s-polarized component is smaller than the reference intensity in several hundred irradiation regions.

In the above-described surface inspection apparatus, it is possible to further include an operation control means for invalidating the detection result of the analysis section in which the presence of the foreign matter is determined by the foreign matter determining means. In this case, since the detection result in the analysis section in which the presence of the foreign matter is determined by the foreign matter determination means is invalidated by the operation control means, unnecessary work for analyzing the contamination is performed in the analysis section to which the foreign matter adheres to the sample surface. Not done.

The various means referred to in the present invention may be formed so as to realize their functions. For example, dedicated hardware, a computer provided with appropriate functions by a program, a computer provided by an appropriate program , The functions realized inside, and the combination thereof are allowed.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic side view showing the surface inspection apparatus of the present embodiment, FIG. 2 is a two-dimensional graph showing the correspondence between each value of RR on the clean surface of the sample and the frequency of occurrence, and FIG. Is a two-dimensional graph showing the correspondence between each value of RR and the frequency of occurrence on the surface of a sample contaminated with organic and inorganic substances, and FIG. 4 is a graph showing R on the surface of a sample contaminated with a composite.
A two-dimensional graph showing the correspondence between each value of R and occurrence frequency,
FIG. 5 shows the RR on the surface of a sample locally contaminated with inorganic substances.
And FIG. 6 is a two-dimensional graph showing the correspondence between each value of RR and the frequency of occurrence on the surface of a sample locally contaminated with organic matter. 7
FIG. 8 is a schematic cross-sectional view showing a state in which foreign matter has adhered to the analysis section on the sample surface, and FIG. 8 is an RR on the surface of the sample to which foreign matter has adhered.
Is a two-dimensional graph showing the correspondence between each value of and the occurrence frequency, and FIG. 9 is a tertiary graph showing the correspondence between each value of RR on the surface of the contaminated sample and a plurality of irradiation regions forming a predetermined analysis section. An original graph and a two-dimensional graph.

First, the sample 2 on which the surface is inspected by the surface inspection apparatus 1 of the present embodiment is, for example, a semiconductor wafer having fine metal wiring formed of platinum, copper, or the like. As shown in FIG. 1, the apparatus 1 includes a sample holding stage 3 as sample holding means for holding the sample 2 as described above.

The sample holding stage 3 is movably supported in the X and Y directions by an X / Y stage 4 as a relative scanning means. The X direction and the Y direction referred to here are directions that are both horizontal but orthogonal to each other. For example, the X direction is the front-back direction and the Y direction is the left-right direction.

At one point on the surface of the sample 2 held on the sample holding stage 3 as described above, a laser irradiation device 5 as laser irradiation means and a polarization detection device 6 as polarization detection means are provided.
The stereo microscope 20 which is an image observation unit is vertically opposed from right above while facing at an inclination angle of about 60 degrees.

The laser irradiation device 5 is a laser light source H
An e-Ne laser tube 7, a beam expander 8, and a condenser lens 9 are provided. The polarization detector 6 includes a polarizing plate 10 serving as a light beam polarizing unit and two pinhole plates 1.
1 and 12 and a photodetector 13 that is a photoelectric conversion unit.

The laser tube 7 emits, for example, a visible light laser beam having a wavelength of 633 (nm) and an output of 5.0 (mW), and the beam expander 8 enlarges the beam diameter of the laser beam emitted from the laser tube 7. I do. The condensing lens 9 condenses the laser beam expanded by the beam expander, so that the laser irradiating device 5 irradiates the irradiation area of about 5.0 (μm ² ) on the surface of the sample 2 held by the sample holding stage 3. The laser beam is focused and irradiated.

The polarizing plate 10 is made of, for example, a Glan-Thompson prism, and is rotatably supported by a rotating mechanism (not shown) composed of a stepping motor and a gear mechanism so that the optical axis is the axis. Then, each of the s-polarized light component and the p-polarized light component is individually extracted from the laser light reflected on the surface of the sample 2.

The pinhole plates 11 and 12 shield the peripheral portion of the s / p polarization component extracted by the polarizing plate 10 and transmit only the central portion, and the photodetector 13 is controlled by the pinhole plates 11 and 12 S / p transmitted through only part
The reflection intensity of the polarization component is detected.

One integrated controller 14 is connected to the X / Y stages 5 and 6, the rotating mechanism of the polarizing plate 10, and the photodetector 13, and this integrated controller 14 is used for the various devices described above. Since the operation is integrally controlled, the polarization detection device 6
The intensity of each of the s-polarized light component and the p-polarized light component of the laser beam scanned two-dimensionally and reflected on the irradiation area on the surface of the sample 2 is individually detected.

An image generating device 15 is connected to the stereomicroscope 20, and an image display device 16 and the above-mentioned integrated control device 14 are connected to the image generating device 15. The stereo microscope 20 observes an irradiation area of about 5.0 (μm ² ) on the surface of the sample 2, and the image generating device 15 generates image data of the surface of the sample 2 observed by the stereo microscope 20, 16 displays and outputs the image data of the surface of the sample 2 generated by the image generating device 15.

The integrated controller 14 to which the image data is input from the image generator 15 controls the operation of the X / Y stage 4 in accordance with the image data of the irradiation area on the surface of the sample 2. The laser beam applied to the sample 2 is two-dimensionally scanned.

A microcomputer 17 is also connected to the integrated control unit 14. The microcomputer 17 has a data input device 18 such as a keyboard as data input means and a data output device such as a display as data output means. The device 19 is connected.

The data input device 18 inputs various data such as instruction codes to the microcomputer 17 by manual operation of an operator, and the data output device 19 outputs various data such as display images generated by the microcomputer 17. Is output to the operator.

The microcomputer 17 has a CPU (Cen
tral Processing Unit) and RAM (Random Access Memor)
y), ROM (Read Only Memory), I / F (Interface), and other hardware.
Various functions are logically realized as various means by the CPU reading a control program, which is software stored in advance in an information storage medium such as M, and executing various operations.

That is, the microcomputer 17 includes:
A ratio calculating function as a ratio calculating means, a frequency detecting function as a frequency detecting means, a relation detecting function as a relation detecting means, an image displaying function as an image displaying means, an intensity comparing function as an intensity comparing means, and a foreign matter determining means. A foreign substance determination function, an operation control function as an operation control unit, and the like are logically realized.

The ratio calculation function is performed by the RAM or R as described above.
When the CPU executes predetermined data processing in accordance with a control program stored in advance in the OM, RR, which is the ratio of the reflection intensity between the s-polarized component and the p-polarized component, detected by the polarization detection device 6 Is calculated for each irradiation area on the surface of the sample 2.

Similarly, when the CPU executes predetermined data processing, the frequency detection function detects the occurrence frequency of each of the calculated RR values for each predetermined analysis section including a plurality of irradiation areas. For example, as described above, the irradiation area of the laser beam on the surface of the sample 2 is 5.0 (μm ² ) and the analysis area is 1
Assuming 00 (μm ² ), one analysis section is composed of four hundred irradiation areas.

The relation detection function detects the correspondence between each value of RR and the occurrence frequency for each analysis section on the sample surface from the detection result of the frequency detection function, and the image display function displays the detection result of the relation detection function as an image. indicate. More specifically, the relationship detection function generates a two-dimensional graph in which the values of RR are assigned to the horizontal axis and the occurrence frequency is assigned to the vertical axis, as shown in FIGS. Is displayed on the display of the data output device 19 as an image.

The intensity comparison function compares the reflection intensity of the s-polarized light component detected by the polarization detecting device 6 with a predetermined reference intensity set in advance. If the intensity is lower than the reference intensity, it is determined that a foreign substance exists in the analysis section on the sample surface.

The operation control function, when performing the operation of analyzing the state of contamination on the surface of the sample 2 by the various functions described above, first activates the above-described intensity comparison function and foreign matter determination function prior to this. The presence or absence of foreign matter is inspected, and only when the presence of foreign matter is not determined, various means such as a ratio calculation function are operated to analyze the contamination in the analysis section.

The operation control function stops the operation of analyzing the state of contamination on the surface of the sample 2 in the analysis section in which the presence of the foreign matter is determined. For example, in this case, a predetermined guidance indicating the presence of the foreign matter is provided. The message is displayed and output on the display of the data output device 19 together with the position data of the analysis section.

The various functions of the microcomputer 17 as described above are realized by using hardware such as the data output device 19 if necessary.
It is realized by the operation of a CPU, which is a computer composed of hardware, corresponding to software stored in an information storage medium such as.

Such software, for example, compares the reflection intensity of the s-polarized light component detected by the polarization detection device 6 with a predetermined reference intensity set in advance. As a result of this comparison, the reflection intensity is higher than the reference intensity. If it is low, it is determined that foreign matter is present in the analysis section on the sample surface. If the presence of foreign matter is confirmed as a result of the determination, a predetermined guidance message is displayed and output on the display of the data output device 19; Is negative, calculating the RR, which is the ratio of the reflection intensity between the s-polarized light component and the p-polarized light component detected by the polarization detection device 6, for each irradiation area on the surface of the sample 2, and calculating each of the calculated RRs The frequency of occurrence of the value is detected for each predetermined analysis section composed of a plurality of irradiation areas, and from this detection result, the correspondence between each value of RR and the frequency of occurrence is determined. As a control program for causing a CPU or the like to execute a processing operation such as generating a two-dimensional graph for each analysis section on the sample surface, displaying the two-dimensional graph on the display of the data output device 19, or the like, a RAM or the like is used as a control program. It is stored in an information storage medium.

A surface inspection method using the surface inspection apparatus 1 of the present embodiment in the above-described configuration will be sequentially described below. First, the laser beam is condensed and irradiated by the laser irradiation device 5 on the surface of the sample 2 held by the sample holding stage 3. In this state, the sample holding stage 3 is moved by the X / Y stage 4 and 2 is scanned two-dimensionally for each irradiation area.

As described above, the respective intensities of the s-polarized light component and the p-polarized light component of the laser beam that is two-dimensionally scanned and reflected on the irradiation area on the surface of the sample 2 are individually detected by the polarization detector 6. However, the microcomputer 17 first compares only the reflection intensity of the s-polarized light component with a predetermined reference intensity.

If the reflection intensity of the s-polarized component is lower than the reference intensity, the microcomputer 17 determines that a foreign substance is present in the analysis section on the surface of the sample 2, and sends a guidance message indicating the presence of the foreign substance to the position data of the analysis section. At the same time, the display of the data output device 19 is displayed and output, and the analysis of the contamination is stopped in the analysis section.

That is, as shown in FIG. 7, when foreign matter is present on the surface of the sample 2, the foreign matter irregularly reflects the irradiated laser beam in a direction different from that of the surface of the sample 2, so that the detected reflection intensity Drops extremely. This occurs similarly for the s-polarized light component and the p-polarized light component, but is particularly remarkable for the s-polarized light component, so that the detection accuracy is good.

As described above, when a two-dimensional graph is generated by performing the operation of analyzing the contamination in the analysis section on the surface of the sample 2 in which the foreign matter is present, as shown in FIG. Since the influence of foreign matter occurs and the state of contamination is not reflected well, the surface inspection apparatus 1 of the present embodiment does not perform the analysis of the contamination in the analysis section where the presence of the foreign matter is determined.

On the other hand, if the reflection intensity of the s-polarized light component is lower than the reference intensity, the microcomputer 17 determines that no foreign substance is present in the analysis section on the surface of the sample 2 and starts the work of analyzing the analysis section for contamination. . In this case, the microcomputer 17 calculates RR, which is the ratio of the reflection intensity between the s-polarized component and the p-polarized component, for each irradiation area on the surface of the sample 2, and calculates the occurrence frequency of each value of the calculated RR for each analysis section. To be detected.

If the irradiation area of the laser beam on the surface of the sample 2 is 5.0 (μm ² ) and the analysis section is 100 (μm ² ), four hundred RRs are detected from one analysis section. R
The number of R is counted for each numerical value. When the occurrence frequency of each value of RR for each analysis section is detected in this manner, RR
Is generated on the horizontal axis and the occurrence frequency on the vertical axis, and is displayed on the display of the data output device 19 as an image.

Since the two-dimensional graph displayed as an image in this manner expresses the frequency of occurrence of each value of RR in the analysis section on the surface of the sample 2, this indicates the contamination state of the analysis section on the surface of the sample 2. That is, the worker can visually recognize the surface state of the sample 2 by visually recognizing the two-dimensional graph.

For example, when the analysis section on the surface of the sample 2 is clean, only a specific value of RR is intensively and frequently generated, and the frequency of occurrence of a value deviating from that value is extremely reduced. As shown in FIG. 2, the shape of the curve of the two-dimensional graph is narrow and steeply convex.

On the other hand, if the surface of the sample 2 is contaminated,
Since the degree of concentration of a specific value of the RR occurring at high frequency decreases and the frequency of occurrence of a numerical value deviating from the numerical value relatively increases, as shown in FIGS. The shape of the curve is not steep, but wide. Also,
As described above, when the surface of the sample 2 is contaminated, the value of the RR that frequently occurs also generally changes. Therefore, the position of the range where the value of the RR occurs at a predetermined frequency also changes.

In particular, as shown in FIG. 3, when the contaminant on the surface of the sample 2 is an inorganic substance, the value of RR frequently generated increases, so that the position of the curve in the two-dimensional graph is shifted to the left in the figure. , And the value of RR decreases when the substance is an organic substance, so that the position of the curve in the two-dimensional graph moves to the right. When the contaminants on the surface of the sample 2 are a mixture of an inorganic substance and an organic substance, as shown in FIG. 4, the curve of the two-dimensional graph has an extremely wide shape as a composite of the curves of the inorganic substance and the organic substance. Become.

Further, when a part of the analysis compartment on the surface of the sample 2 is locally contaminated, the characteristics of the clean part and the contaminated part in the analysis compartment are simultaneously generated in the two-dimensional graph. Therefore, as shown in FIGS. 5 and 6, the shape of the curve of the two-dimensional graph is a shape in which a plurality of curves are overlapped.

As described above, the two-dimensional graph displayed as an analysis result by the surface inspection apparatus 1 allows the
Can be checked at a glance for each analysis section. In this case, the operator can determine the presence or absence of contamination on the surface of the sample 2 based on the frequency of occurrence of a specific value of RR, and determine the degree of contamination on the surface of the sample 2 based on the magnitude of the range in which the value of RR occurs at a predetermined frequency. Can also be determined.

If the value of RR at which the frequency of occurrence peaks is higher than the reference value, it can be determined that the contamination of the sample 2 is due to inorganic substances, and if it is low, it can be determined that it is due to organic substances.
Further, when the position of the range where the RR value occurs at a predetermined frequency is higher than the reference position, it can be determined that the contamination of the sample 2 is due to the inorganic substance, and when it is low, it can be determined that the contamination is due to the organic substance.

Further, if the position of the range where the value of RR occurs at a predetermined frequency is wider than the reference range, it is possible to judge that the contamination of the sample 2 is caused by the mixture of the inorganic substance and the organic substance. Is determined at a glance based on the shape of the curve of the two-dimensional graph, the vertical position of the peak, the horizontal position of the peak, the overall horizontal position, the overall horizontal width, the number of peaks, etc. can do.

In the surface inspection method in the surface inspection apparatus 1 of the present embodiment, the state of the surface of the sample 2 is determined by comparing the state of the surface
Since the inspection can be performed based on RR, which is the ratio of the reflection intensity to the polarization component, even if the surface of the sample 2 is microscopically rough, the influence can be canceled and a good result can be detected.

In this case, since the occurrence frequency of each value of RR for each analysis section is detected, the state of contamination on the surface of the sample 2 can be detected satisfactorily. In particular, since the detection result is displayed as an image as a two-dimensional graph, the operator can check at a glance the contamination state of the surface of the sample 2.

Further, prior to the operation of analyzing such contamination, the presence or absence of foreign matter is detected, and the analysis of contamination is not performed in the analysis section in which the presence of foreign matter is determined. For this reason,
Since unnecessary work is omitted, the overall work efficiency is good, and only effective analysis results are output, so that the contamination state of the surface of the sample 2 can be confirmed with good accuracy. In particular, since the detection of foreign matter is performed using the s-polarized component of the reflected light as described above, it is not necessary to add a special mechanism for detecting foreign matter, and the surface inspection apparatus 1 has a simple structure.

The present invention is not limited to the above-described embodiment, and allows various modifications without departing from the gist of the present invention. For example, in the above embodiment, the X / Y stage 4 moves the holding stage in order to scan the laser beam irradiated on the surface of the sample 22.

However, it is also possible to move the laser irradiating device 5 and the polarization detecting device 6. As a method of moving the laser irradiating device 5 and the polarization detecting device 6 for scanning the laser beam in this way, for example, It is also possible to translate or rotate a deflecting optical system such as a reflecting mirror while keeping the laser light source and the photodetector fixed.

Also, in order to individually detect each of the s / p polarized light by the polarization detecting device 6, the polarizing plate 10 is rotated at a right angle. However, for example, a pair of polarizing plates whose polarization directions are orthogonal to each other is used. It is also possible to arrange them alternately on the optical path, and it is also possible to arrange alternately on the optical path a pair of polarization detectors that individually detect each of the s / p polarized light.

Further, in the above embodiment, the CP is executed according to a control program stored as software in a RAM or the like.
It is illustrated that various means are logically realized as various functions of the microcomputer 17 by operating the U. However, it is also possible to form each of these various means as unique hardware, and it is also possible to store a part as software in a RAM or the like and form a part as hardware.

Although the two-dimensional graph of the analysis result has been shown as an image on the display of the data output device 19 in the above embodiment, the analysis result may be printed out by a printer, or a floppy disk (FDD) may be used. Driv
It is also possible to store data in the FD in e).

Further, in the above embodiment, the surface inspection apparatus 1 displays the occurrence frequency of each value of RR for each analysis section as an image as a two-dimensional graph, and the worker who visually recognizes the displayed image can check whether the sample 2 is contaminated or not. Judgment was described as an example. But,
As described above, since the occurrence frequency of each value of RR for each analysis section has a certain rule depending on the presence or absence and content of contamination, the surface inspection apparatus 1 automatically determines presence / absence and content of contamination by a predetermined algorithm. It is also possible.

In the above embodiment, the surface inspection apparatus 1 detects the frequency of occurrence of each value of RR for each analysis section and generates a two-dimensional graph. Can be detected for each analysis section, and a three-dimensional graph or a two-dimensional graph can be generated from the detection result.

In this case, as shown in FIG. 9, a three-dimensional graph or the like may be generated in which the analysis section is the lower surface and each value of RR for each irradiation region is the vertical axis. Can be checked at a glance. Further, as shown in the figure, it is also possible to generate a two-dimensional graph in which each value of RR for each irradiation region is expressed by a predetermined color by expressing the analysis section by a plane. The contamination status of the surface of No. 2 can be confirmed at a glance.

[0084]

Since the present invention is configured as described above, it has the following effects.

In the surface inspection method according to the first surface inspection apparatus of the present invention, the surface of the sample held by the sample holding means is condensed and irradiated with the laser beam by the laser irradiation means. The means and the sample holding means are relatively moved by the relative scanning means, and the laser beam applied to a predetermined irradiation area on the sample surface is two-dimensionally scanned, and the two-dimensional scanning is performed on the irradiation area on the sample surface. The respective intensities of the s-polarized light component and the p-polarized light component of the reflected laser beam are individually detected by the polarization detecting means, and RR, which is the ratio of the reflected light intensity of the s-polarized light component and the p-polarized light component, is calculated by the ratio calculating means. Is calculated for each irradiation area on the sample surface, and the occurrence frequency of each value of the RR calculated in this way is detected by the frequency detection means for each predetermined analysis section including a plurality of irradiation areas. The relationship between each value of RR and the frequency of occurrence is detected for each analysis section on the sample surface by the relationship detection means from the detection result, so that the contamination state on the sample surface can be detected based on the relationship. Since this correspondence is detected from RR, which is the ratio of the reflection intensity between the s-polarized light component and the p-polarized light component, the influence can be canceled even if the sample surface is microscopically rough, and the sample surface can be canceled. Can be easily and quickly detected with good accuracy.

In the surface inspection method in the second surface inspection apparatus according to the present invention, the correspondence between each value of RR and a plurality of irradiation areas is detected by the relation detecting means for each analysis section, and the correspondence is determined by the correspondence. Since the contamination state of the sample surface can be detected, and this correspondence is detected from RR, which is the ratio of the reflection intensity of the s-polarized light component to the p-polarized light component, the surface of the sample is microscopically rough. However, the influence can be offset, and the contamination state on the sample surface can be detected easily and quickly with good accuracy.

In the above-described surface inspection apparatus, the relation detection means generates a two-dimensional graph in which one of the RR values and the occurrence frequency is a vertical axis and the other is a horizontal axis.
With this two-dimensional graph, the state of contamination on the sample surface can be expressed in a state that can be confirmed at a glance.

Further, the analysis section has a lower surface and the R
Since the relation detecting means generates a three-dimensional graph in which each value of R is the vertical axis, the three-dimensional graph can express the contamination state of the sample surface at a glance.

Further, the relation detecting means generates a two-dimensional graph in which the analysis section is represented by a plane and each value of RR for each irradiation region is represented by a predetermined color, and the two-dimensional graph is used to obtain the surface of the sample. The contamination state can be expressed in a state that can be confirmed at a glance.

Further, the image display means displays the two-dimensional graph or three-dimensional graph which is the detection result of the relation detecting means, so that the operator can contaminate the sample surface with the two-dimensional graph or three-dimensional graph of the displayed image. The status can be checked at a glance.

Further, the contamination judging means judges the presence or absence of contamination on the sample surface from the detection result of the relation detecting means.
The surface inspection device can automatically determine the contamination state of the sample surface.

The type of contamination on the sample surface is automatically determined by the surface inspection apparatus by the contamination determining means determining whether the contamination of the sample is due to an inorganic substance, an organic substance, or a mixture from the detection result of the relation detecting means. can do.

Further, the reflection intensity of the s-polarized light component detected by the polarization detecting means is compared with a predetermined reference intensity by the intensity comparing means. By determining that a foreign substance is present in the analysis section, the foreign substance present in the analysis section on the sample surface can be detected.

Further, the detection result in the analysis section in which the presence of the foreign matter is determined by the foreign matter determination means is invalidated by the operation control means, so that the analysis section to which the foreign matter has adhered on the sample surface is analyzed for contamination. Since the work can be prevented, the absolute work efficiency and the accuracy of the contamination analysis can be improved.

In the surface inspection method of the present invention, the presence / absence of contamination on the sample surface is determined simply and quickly with good accuracy by determining the presence / absence of contamination on the sample surface based on the frequency of occurrence of a specific value of RR. can do.

Further, by determining the presence or absence of contamination on the sample surface according to the magnitude of the range in which the value of RR occurs at a predetermined frequency, it is possible to easily and quickly determine the presence or absence of contamination on the sample surface with good accuracy. it can.

If the value of RR at which the frequency of occurrence peaks is higher than the reference value, it is determined that contamination of the sample is due to inorganic substances, and if it is low, it is determined that the contamination is due to organic substances. Can be determined easily and quickly with good accuracy.

If the position of the range where the RR value occurs at a predetermined frequency is higher than the reference position, it is determined that the contamination of the sample is due to the inorganic substance, and if it is lower, it is determined that the contamination is due to the organic substance. Can be easily and quickly determined with good accuracy as to whether it is inorganic or organic.

If the position of the range where the value of RR occurs at a predetermined frequency is wider than the reference range, it is determined that the contamination of the sample is caused by the mixture of the inorganic and organic substances. Can be easily and quickly determined with good accuracy.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing a surface inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a two-dimensional graph showing a correspondence relationship between each value of RR on a clean surface of a sample and an occurrence frequency.

FIG. 3 is a two-dimensional graph showing the correspondence between each value of RR and the frequency of occurrence on the surface of a sample contaminated with an organic substance and an inorganic substance.

FIG. 4 is a two-dimensional graph showing the correspondence between each value of RR and the frequency of occurrence on the surface of a sample contaminated with a composite.

FIG. 5: R at the surface of a sample locally contaminated with minerals
6 is a two-dimensional graph showing a correspondence relationship between each value of R and an occurrence frequency.

FIG. 6: R at the surface of a sample locally contaminated with organic matter
6 is a two-dimensional graph showing a correspondence relationship between each value of R and an occurrence frequency.

FIG. 7 is a schematic cross-sectional view showing a state in which a foreign substance has adhered to an analysis section on a sample surface.

FIG. 8 is a two-dimensional graph showing the correspondence between each value of RR on the surface of a sample to which a foreign substance has adhered and the frequency of occurrence.

FIG. 9 is a three-dimensional graph and a two-dimensional graph showing a correspondence relationship between each value of RR on the surface of a contaminated sample and a plurality of irradiation regions forming a predetermined analysis section.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Surface inspection apparatus 2 Sample 3 Sample holding stage which is sample holding means 4 X / Y stage which is relative scanning means 5 Laser irradiation apparatus which is laser irradiation means 6 Polarization detecting apparatus which is polarization detecting means 17 Micro which functions as various means Computer 19 Data output device corresponding to image display means

Claims (22)

[Claims] A sample holding means for holding a sample; a laser irradiating means for condensing and irradiating a laser beam onto a surface of the sample held by the sample holding means; a laser irradiating means and the sample holding means; Relative scanning means for two-dimensionally scanning a laser beam irradiated on a predetermined irradiation area of the sample surface by relatively moving the laser beam; and s of the laser beam scanned two-dimensionally and reflected on the irradiation area of the sample surface. Polarization detection means for individually detecting the intensity of each of the polarization component and the p-polarization component; and RR (Reflectance Ratio) which is a ratio of the reflection intensity of the s-polarization component and the p-polarization component detected by the polarization detection means.
A ratio calculating means for calculating for each irradiation area on the sample surface, a frequency detecting means for detecting the occurrence frequency of each value of RR calculated by the ratio calculating means for each predetermined analysis section comprising a plurality of irradiation areas, A surface detecting apparatus comprising: a relationship detecting unit configured to detect a correspondence relationship between each value of RR and an occurrence frequency for each analysis section on the sample surface from a detection result of the frequency detecting unit. 2. A sample holding means for holding a sample, a laser irradiation means for condensing and irradiating a laser beam on a surface of the sample held by the sample holding means, the laser irradiation means and the sample holding means, Relative scanning means for two-dimensionally scanning a laser beam irradiated on a predetermined irradiation area of the sample surface by relatively moving the laser beam; and s of the laser beam scanned two-dimensionally and reflected on the irradiation area of the sample surface. Polarization detecting means for individually detecting the intensity of each of the polarization component and the p-polarization component; and irradiating the sample surface with RR, which is the ratio of the reflection intensity of the s-polarization component and the p-polarization component detected by the polarization detection means. Ratio calculating means for calculating each area, and relation detecting means for detecting a correspondence between each value of RR calculated by the ratio calculating means and a plurality of irradiation areas forming a predetermined analysis section. Surface inspection equipment. 3. The surface inspection apparatus according to claim 1, wherein said relation detecting means generates a two-dimensional graph in which one of each value of RR and occurrence frequency is a vertical axis and the other is a horizontal axis. 4. The surface inspection apparatus according to claim 2, wherein the relation detection unit generates a three-dimensional graph in which the analysis section is on the lower surface and each value of RR for each irradiation area is on the vertical axis. 5. The surface inspection apparatus according to claim 2, wherein the relation detection unit generates a two-dimensional graph in which the analysis section is represented by a plane and each value of RR for each irradiation area is represented by a predetermined color. 6. The surface inspection apparatus according to claim 3, further comprising image display means for displaying a detection result of said relation detection means in an image. 7. The surface inspection apparatus according to claim 1, further comprising a contamination judging means for judging the presence or absence of contamination on the surface of the sample from the detection result of the relation detecting means. 8. The surface inspection apparatus according to claim 7, wherein the contamination determination unit determines whether contamination of the sample is due to an inorganic substance, an organic substance, or a mixture from the detection result of the relation detection unit. 9. An intensity comparison means for comparing the reflection intensity of the s-polarized light component detected by the polarization detection means with a predetermined reference intensity, and as a comparison result of the intensity comparison means, if the reflection intensity is lower than the reference intensity, the sample surface The surface inspection apparatus according to any one of claims 1 to 8, further comprising: a foreign substance determination unit configured to determine whether a foreign substance is present in the analysis section. 10. The surface inspection apparatus according to claim 9, further comprising an operation control unit for invalidating a detection result of the analysis section in which the presence of the foreign matter is determined by the foreign matter determination unit. 11. A laser beam focused on a surface of a sample is irradiated, and the laser beam and the surface of the sample are relatively moved to scan a predetermined analysis section including a plurality of irradiation regions. The intensity of each of the s-polarized light component and the p-polarized light component of the laser beam scanned and reflected by the surface of the sample is individually detected, and the ratio of the detected reflected light intensity of the s-polarized light component to the p-polarized light component is obtained. A certain RR is calculated for each irradiation region on the sample surface, and the occurrence frequency of each value of the calculated RR is detected for each analysis section. From the detection result, each RR value and occurrence frequency for each analysis section on the sample surface are calculated. A surface inspection method that detects the correspondence with the surface. 12. A laser beam focused on the surface of the sample is irradiated, and the laser beam and the surface of the sample are relatively moved to scan a predetermined analysis section composed of a plurality of irradiation areas. The intensity of each of the s-polarized light component and the p-polarized light component of the laser beam scanned and reflected by the surface of the sample is individually detected, and the ratio of the detected reflected light intensity of the s-polarized light component to the p-polarized light component is obtained. A surface inspection method in which a certain RR is calculated for each irradiation region on a sample surface, and the correspondence between each value of the calculated RR and the irradiation region is detected for each analysis section. 13. A method for irradiating a laser beam focused on a surface of a sample, moving the laser beam and the surface of the sample relative to each other, and scanning a predetermined analysis section including a plurality of irradiation areas. The intensity of each of the s-polarized light component and the p-polarized light component of the laser beam scanned and reflected by the surface of the sample is individually detected. If the detected reflection intensity of the s-polarized light component is lower than a predetermined reference intensity, It is determined that a foreign substance is present in the analysis section on the sample surface. In the analysis section where the presence of the foreign substance is not determined, RR, which is the ratio of the reflection intensity of the s-polarized light component to the p-polarized light component, is calculated for each irradiation area on the sample surface. Then, the calculated frequency of occurrence of each value of RR is detected for each analysis section, and from this detection result, the correspondence between each value of RR and the occurrence frequency is detected for each analysis section of the sample surface. Inspection methods. 14. A method for irradiating a laser beam converged on a surface of a sample, moving the laser beam and the surface of the sample relative to each other, and scanning a predetermined analysis section including a plurality of irradiation regions. The intensity of each of the s-polarized light component and the p-polarized light component of the laser beam scanned and reflected by the surface of the sample is individually detected. If the detected reflection intensity of the s-polarized light component is lower than a predetermined reference intensity, It is determined that a foreign substance is present in the analysis section on the sample surface, and in the analysis section in which the presence of the foreign substance is not determined, RR, which is the ratio of the reflection intensity of the s-polarized light component to the p-polarized light component, is calculated for each irradiation area on the sample surface. A surface inspection method for detecting the correspondence between each of the calculated RR values and the irradiation area for each analysis section. 15. As a correspondence relationship between each value of RR and occurrence frequency for each analysis section, a two-dimensional graph in which one of each value of RR and occurrence frequency is a vertical axis and the other is a horizontal axis is generated. A surface inspection method according to claim 11. 16. A correspondence relationship between each value of RR and a plurality of irradiation regions of the analysis section, wherein the analysis section generates a three-dimensional graph in which the RR value for each irradiation area is on the vertical axis on the lower surface. Item 15. The surface inspection method according to item 12 or 14. 17. A two-dimensional graph in which an analysis section is represented by a plane and each value of RR for each irradiation area is represented by a predetermined color as a correspondence relationship between each value of RR and a plurality of irradiation areas of the analysis section. 15. The surface inspection method according to claim 12, wherein 18. The surface inspection method according to claim 11, wherein the presence or absence of contamination on the sample surface is determined based on the frequency of occurrence of a specific value of RR. 19. The surface inspection method according to claim 11, wherein the presence or absence of contamination on the sample surface is determined based on the magnitude of the range in which the value of RR occurs at a predetermined frequency. 20. The method according to claim 1, wherein if the value of RR at which the frequency of occurrence is at a peak is higher than a reference value, it is determined that contamination of the sample is due to an inorganic substance, and if it is low, it is determined to be due to an organic substance.
8. The surface inspection method according to 8. 21. The method according to claim 19, wherein the contamination of the sample is determined to be caused by an inorganic substance when the position of the range in which the value of RR occurs at a predetermined frequency is higher than the reference position is determined, and when the position is lower than the reference position, the contamination is determined to be caused by the organic substance. Surface inspection method. 22. The method according to claim 21, wherein the contamination of the sample is determined to be a mixture of an inorganic substance and an organic substance when the position of the range where the value of RR occurs at a predetermined frequency is wider than a reference range.
Surface inspection method as described.