JPH1172311A - Sectional form measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sectional form by a method wherein a correction value is obtained by a calibration means from a relationship between a first distance from the surface of an object to be inspected to a sensor and a difference signal of the sensor and then, is added to a second distance between a stage in which the actual surface of the object to be inspected is scanned to hold the difference signal of the sensor zero and the sensor to allow calibration according to the condition of the surface. SOLUTION: Firstly, while stages 24 and 26b are driven to scan the top of the surface of an object to be inspected, a sensor device 20 is continuously driven in the direction of the Z axis so that a difference signal S from a 2-split sensor in the sensor device 20 is held in zero under a servo control in which the driving or controlling is performed by a control section 30. When the difference signal S from the sensor is 'zero', a distance between the object to be inspected and the device 20 is at a focusing distance. In the measurement of the sectional form, secondly, a moving distance in the direction of the Z axis of the sensor device 20 is detected by an encoder 21 as a degree displaced from a Z value. That is to say, the device 20 is always driven vertically to reach the focusing position along the direction of scanning and the Z value at the moment is sampled thereby measuring the sectional form of the surface of the object to be inspected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a non-contact type cross-sectional shape measuring apparatus for measuring a cross-sectional shape of a surface of an object to be inspected by detecting a change amount of a focus position of a sensor device.

[0002]

2. Description of the Related Art A non-contact type cross-sectional shape measuring apparatus drives and controls a vertical position of a microscope barrel provided with a sensor so that the vertical position is always in focus with respect to the surface of an inspection object. The height of the surface of the inspection object is detected from the displacement amount in the vertical direction. Then, the cross-sectional shape of the surface of the inspection object is detected by sampling the amount of displacement in the vertical direction while scanning the surface of the inspection object.

[0003] The automatic focusing function of such a measuring device is configured according to, for example, the principles of the triangulation method and the knife edge method. FIG. 8 is a diagram showing the knife edge method.
According to this method, a light spot 13 projected from the light source 10 to the surface of the inspection object 12 through one side of the optical system 14 is again transmitted to the opposite side of the optical system 14 and the reflection surface of the knife edge 16.
The image is projected on the split sensor 18. In the drawing, as shown by solid lines and broken lines, the heights h1, h2, h of the surface of the inspection object 12 are shown.
The positions of the light spots to be imaged on the two-division sensor 18 are different depending on the three. In this example, the height h of the surface of the inspection object is
Position 2 is the in-focus position at which the light spot image then forms a sharp image exactly in the middle of the two-segment sensor.
At the upper and lower positions h1 and h3, the light spot images are formed as defocused images at the positions of the sensors B and A, respectively. The basic principle of the triangulation method is the same as that of the knife edge method, and utilizes the fact that the position of the light spot on the two-division sensor changes according to the height of the surface of the inspection object.

FIG. 9 is a diagram showing signals detected by the two-divided sensor. In the figure, the horizontal direction corresponds to the vertical distance between the surface of the inspection object and the sensor. As the distance changes, light spot images are generated on the sensors A and B of the two-divided sensor 18. Accordingly, the signal b from the sensor B, the signal a from the sensor A, and their difference signal S
= Ab is generated. Accordingly, the position of the distance between the sensor and the surface of the inspection object where the difference signal S = 0 corresponds to the focus position.

Utilizing such a principle, a cross-sectional shape measuring apparatus scans the surface of an object to be inspected, and constantly scans the surface of the object to be inspected. Is driven and the cross-sectional shape or height distribution of the surface of the inspection object is measured according to the distance between the sensor and the stage on which the inspection object is detected at that time.

[0006]

However, in the servo control for driving and controlling the distance between the stage on which the object is placed and the sensor so that the difference signal S = 0 while scanning the surface of the object to be inspected. It is difficult to always maintain the difference signal S = 0 due to the tracking characteristics of the servo control.
For example, when the height of the surface of the inspection object changes stepwise, the difference signal S does not temporarily become zero and the state becomes out of focus. Even if the drive is controlled by changing the gain according to the difference signal S by the servo control, it takes some time to return to the focus state of the difference signal S = 0 again due to the delay caused by the feedback.

Therefore, the distance between the stage of the inspection object and the sensor is detected, a correction value based on the difference signal S from the two-divided sensor is calculated, and the correction value is added to the detected distance to obtain a true value. Determining the height has conventionally been performed.

However, such correction values are based on a uniform table or linear interpolation irrespective of the material of the object to be inspected, and a conventional cross-sectional shape measuring apparatus cannot determine an accurate correction value. In particular, for example, a metal or mirror-finished surface has a large reflection coefficient, while a plastic or rough-finished surface has a low reflection coefficient and tends to scatter reflected light. In this case, the light spot image on the two-divided sensor at the out-of-focus position differs depending on the material of the reflecting surface and the finishing condition of the surface. Therefore, the relationship between the detected difference signal S and the amount of displacement from the in-focus position differs depending on the inspection object. Therefore, in the method of performing the correction uniformly as in the related art, it is impossible to accurately measure the cross-sectional shape depending on the surface condition of the inspection object.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a cross-sectional shape measuring device capable of accurately measuring a cross-sectional shape regardless of the surface condition of an object to be inspected.

Another object of the present invention is to provide a cross-sectional shape measuring apparatus having a calibration means capable of acquiring a relationship between a sensor output signal and a distance in accordance with the surface condition of an object to be inspected more accurately. Is to do.

It is still another object of the present invention to appropriately perform calibration in accordance with the surface condition of an object to be inspected and to measure a cross-sectional shape in accordance with a relationship between a sensor output signal and a distance optimal for a surface of the object to be inspected. It is an object of the present invention to provide a method for measuring a cross-sectional shape.

[0012]

According to the present invention, in a calibration means, a relationship between a first distance from a surface of a test object to a sensor and a difference signal of the sensor is determined in accordance with a type of a surface of the test object. Measure multiple types. Then, a correction function or a correction table indicating the above-described relationship is obtained for each type of surface of each inspection object. Then, the second distance between the stage of the inspection object and the sensor is servo-controlled so as to keep the sensor difference signal at zero while scanning the actual surface of the inspection object, and the second distance detected at that time is controlled. Then, a correction value obtained from a sensor difference signal and a correction function or a correction table indicating the above relationship is added to obtain a final measured value. Since the correction function and the correction table are acquired for each type of the surface of the inspection object, the optimum correction function and the correction table are selected and used for the calculation for obtaining the correction value.

In order to achieve the above object, the present invention relates to a method for projecting a light spot projected on a surface of an object to be inspected according to a first distance between the object and the photoelectric conversion element. The object was projected onto the photoelectric conversion element via a light receiving optical system that changes the position of the point image, and the object to be inspected was placed such that the position of the light point image projected on the photoelectric conversion element was a predetermined position. A measuring unit that scans the light spot along the surface of the inspection object while driving and controlling a second distance between the stage and the photoelectric conversion element, a distance detecting unit that detects the second distance, A cross-sectional shape measuring apparatus having a calculating means for calculating a cross-sectional shape of the inspection object according to the second distance, at a predetermined position of the inspection object, from the photoelectric conversion element when the first distance is changed. From the detected light spot image position signal, the first distance and the light spot Calibration means for acquiring the relationship with the position signal for a plurality of types of test objects, the arithmetic means, while scanning the surface of the test object, the second distance is detected, A correction value up to the predetermined position obtained from the light spot image position signal and the relationship between the first distance and the light spot image position signal corresponding to the type of the object to be inspected. It is characterized in that the cross-sectional shape of the inspection object is obtained.

According to this invention, the second distance detected during scanning is corrected using the relationship between the first distance and the light spot image position signal that is optimal for the surface state of the inspection object. Therefore, more accurate correction can be performed.

Further, according to the present invention, in the above-mentioned invention, the calibrating means obtains a plurality of points of each type of the inspection object when acquiring the relationship between the distance and the light spot image position signal. A representative relation is obtained as a correction function from a plurality of the obtained relations by a predetermined approximation operation.

By obtaining a correction function by an approximation operation based on a plurality of relationships obtained by sampling a number of points, the influence of the unique state of the sampling points can be eliminated, and a more general-purpose correction function can be obtained. Can be obtained.
Moreover, in the case of a correction function, only the constant needs to be stored, so that the capacity of a memory for storing a plurality of types of correction functions can be reduced.

Further, a more accurate correction function can be obtained by using at least a third-order polynomial as a correction function by the least square method in the approximation operation.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, such embodiments do not limit the technical scope of the present invention.

FIG. 1 is a schematic view of a cross-sectional shape measuring apparatus according to this embodiment. The light source 10 and the optical system 1 described in FIG.
The sensor device 20 including the four- and two-divided sensors 18
It is provided on a stage composed of a stage 24 and a Y stage 26 via a column 23. An inspection object (not shown) is mounted on the stage. In the upper part of the sensor device 20,
An image pickup device 22 is provided, which picks up an object to be inspected and outputs an image signal to an image observation unit 28. The sensor device 20 is driven up and down in a vertical direction (Z-axis direction) by a driving device (not shown), and an encoder 21 provided in the sensor device 20 outputs a Z value of the position of the sensor device 20 in the Z-axis direction. Further, a difference signal S from the two-divided sensor in the sensor device 20 is also output.

The control unit 30 receives the difference signal S from the two-divided sensor, the Z value from the encoder of the sensor device, and the position signal X value and Y value from the stage encoder for detecting the positions of the stages 24 and 26. , And controls the horizontal drive of the stage and the vertical drive of the sensor device 20. The stage is driven to scan the surface of the inspection object with the projected light spots.
This is performed to maintain the difference signal S from the divided sensors at zero and keep the distance between the sensor device 20 and the inspection object at the value of the focus position (focus distance). Further, the image signal P generated by the image observation unit 28 is given to the control device 30 and the control device 30
Controls the image display on the display device 32. Furthermore,
An operation input IN is provided from the operation input device 34 to the control device 30.

The cross-sectional shape of the surface of the inspection object is measured by the cross-sectional shape measuring device shown in FIG. In the measurement, first, while scanning the surface of the inspection object with the projected light spot by driving the stages 24 and 26, the difference signal S from the two-divided sensor provided in the sensor device 20 is set to 0. The sensor device 20 is continuously driven in the Z-axis direction so as to be maintained at. That is,
This is a servo control of the sensor device 20. As shown in FIGS. 8 and 9, when the difference signal S from the sensor is zero, the distance between the inspection object and the sensor device 20 is the focusing distance. And
When the difference signal S is negative, the position is shorter than the focus position, and when the difference signal S is positive, the position is longer than the focus position. Accordingly, when the difference signal S is negative, the sensor device 20 is driven to a higher position, and when the difference signal S is positive, the sensor device 20 is driven to a lower position.
The control unit 30 controls the drive. In this case, for example, the higher the absolute value of the difference signal S is, the higher the gain is, and the higher the driving is, the more the servo control can be followed.

In the measurement of the cross-sectional shape, secondly, the moving distance of the sensor device in the Z-axis direction is detected as the displacement of the Z value by the encoder 21 attached to the sensor device 20.
That is, as described above, the sensor device 2 is always arranged in the scanning direction.
By driving the sensor up and down so that 0 becomes the in-focus position and sampling the Z value of the sensor device 20 at that time, the cross-sectional shape of the surface of the inspection object can be measured.

FIG. 2 is a graph showing Z detected when scanning is performed.
FIG. 7 is a diagram illustrating a relationship between a value and an actual cross-sectional shape of an inspection object and a difference signal S from a sensor. The horizontal axis in FIG. 2A is the scanning direction, the vertical axis is the Z value, and the horizontal axis in FIG.
The vertical axis is the difference signal S. 2 (1) indicates the Z value based on the actual surface of the inspection object, and the solid line indicates the Z value detected as the actual position of the sensor device 20.

As described above, the vertical drive of the sensor device 20 is servo-controlled by the CNC control device in the control unit 30. Where the surface shape of the inspection object changes abruptly, a shift amount temporarily occurs between the Z value of the sensor device 20 and the Z value of the surface of the inspection object due to the delay characteristics of the servo control. That is, it is as indicated by ΔZ in the figure. Therefore, in order to measure an accurate cross-sectional shape, the sensor device 20 must be used.
Must be added to the Z value detected from the position.

On the other hand, when the Z value detected by the encoder from the position of the sensor device 20 deviates from the in-focus position with respect to the inspection object by ΔZ, the difference signal S of the sensor shown in FIG. It shifts in the plus or minus direction. This is because when the above-mentioned ΔZ shift occurs, the sensor device 2
This is because 0 is shifted from the focus position of the difference signal S = 0. Therefore, if the shift amount from the in-focus position can be obtained based on the difference signal S, the shift amount ΔZ of the Z value can be obtained.

However, the relationship between the difference signal S and the amount of deviation ΔZ from the in-focus position varies depending on the surface condition of the inspection object. I can't ask.

FIG. 3 shows a difference amount Z which is a shift amount from the in-focus position of the sensor device with respect to the surface of a plurality of types of inspected objects.
FIG. 9 is a diagram illustrating an example of a relationship between s and a difference signal S. Here, three types of S-shaped curves 40, 42, and 44 are shown. For example, the S-shaped curve 40 is a case where the surface of the inspection object has a high reflectance like a mirror surface and is regularly reflected. When the surface of the object to be inspected is a mirror surface, the light spot image formed on the surface of the two-divided sensor 18 shown in FIG. 9 is relatively sharp, and the difference signal S has a sharp curve near the in-focus position. Become. On the other hand, the S-shaped curve 44 is a case where the surface of the inspection object is a surface that irregularly reflects like a rough surface. In the case of such a surface, the light spot image formed on the surface of the two-piece sensor 18 is a relatively out-of-focus image,
The difference signal S has a slow curve centered on the in-focus position.

Therefore, assuming that the difference signal S from the sensor is the S1 value, the corresponding sensor device 20
The deviation amount Zs of the position from the in-focus position is ΔZ in FIG.
1, ΔZ2 and ΔZ3. That is, the deviation amount Zs obtained from the curve of the difference signal S differs depending on the surface state of the inspection object. Therefore, in order to more accurately obtain the shift amount Zs from the difference signal S, it is necessary to use a function representing a curve of the optimum difference signal S for each type of the surface of the inspection object as a correction function.

FIG. 4 is a diagram showing an example of sampling the surface of the object to be inspected by the calibration means in this embodiment. In this example, six sampling points 46 are respectively taken for the mirror surface area 12A where the reflectance of the inspection object 12 is high and the regular reflection area 12A and the rough reflection area 12B where the irregular reflection is performed. In the present embodiment, for example, the stage is moved so that the optical system of the sensor device 20 is located at one sampling point in the mirror surface area 12A. And
The stage is stopped at the sampling point, and the difference signal S and the Z value from the detected two-divided sensor are sampled while the sensor device 20 scans in the Z-axis direction. This sampling process of the difference signal S is repeated at the other five sampling points. As for the sampling point, the position of a general mirror surface is selected as much as possible, and the selection of a position having a special shape and surface state is avoided.

FIG. 5 is a diagram showing the distribution of the sampling values of the difference signal S corresponding to the difference Zs from the focal position of the sensor device 20 at a plurality of sampling points 46.
In the figure, the sampling values are indicated by + signs. In the present embodiment, the relationship between the position (Zs value) of the sensor device and the difference signal S from the two-divided sensor is acquired at a plurality of sampling points, and the distribution of values within the appropriate effective range 52 is obtained. , An approximate curve 50 is obtained by a predetermined approximate calculation method. This approximation curve 50 is acquired, for example, as a correction function or as a correction table, and is used as a base for obtaining a correction value in actual cross-sectional shape measurement.

The approximate curve 50 showing the relationship between the difference Zs value of the position of the sensor device obtained from the plurality of sampling points from the focal position and the difference signal S from the two-divided sensor is
By the matrix solution method of the least squares method, for example, it can be represented by the following third-order polynomial.

Zs = ax ³ + bx ² + cx + d Since x is the difference signal S, this polynomial can be expressed as a correction function Zs = F (s).

The matrix solution of the least squares method is as follows.

[0034]

(Equation 1)

The above-mentioned x ₁ , x _2... X _n are the values of the sampled difference signal S (the S value of the point + in the figure), and y ₁ , x ₂
y _{2 ...} y _n is a differential amount Zs from the focal position of the position sensor device corresponding thereto. By obtaining the parameters a, b, c, and d of the correction function, a relational expression required for calibration can be obtained.

By using the correction function, it is only necessary to store a plurality of sets of parameter values a to d, and a memory area can be saved as compared with the case where a correction table is stored. Further, by using a polynomial of at least third order, the correction function can be a function closer to the curve of the difference signal S. Accordingly, more accurate correction of the cross-sectional shape can be performed.

FIG. 6 is a detailed configuration diagram of the cross-sectional shape measuring apparatus of the present embodiment. FIG. 6 specifically shows the configuration inside the control unit 30 in detail. In the sensor device 20, a two-divided sensor 18 is provided in addition to a light source and an optical system (not shown).
The signals from the respective sensors A and B are output to a difference signal generator 54.
And a difference signal S = ab is generated. The sensor device 20 is provided with an encoder 56 for detecting its vertical position. From a counter 58 that counts pulse signals from the encoder 56, the Z value of the sensor device 20 is determined.
The axial position Z is output. Furthermore, stages 24 and 2
The encoder 60 is also provided with an encoder 60, and outputs the position X value and the Y value of the stage.

The control unit 30 shown in FIG. 1 includes a CNC drive control unit 64, a calibration control unit 66, a sectional shape measurement and correction calculation unit 68, and a correction function memory 70. The CNC drive control unit 64 includes a sensor device drive unit 72
And a drive signal to the stage drive unit 74 is generated. Specifically, first, the stage drive control when measuring the cross-sectional shape by scanning the inspection object 12 with the sensor device 20 and the sensor device so that the difference signal S from the sensor becomes zero during scanning. And servo control for driving the motor 20. Secondly, in the calibration process, drive control of the sensor device 20 in the vertical direction at the sampling point is performed. Therefore, C
The difference signal S, the position Z of the sensor device, and the positions X and Y of the stage are given to the NC drive control unit 64.

The calibration control section performs a calibration step corresponding to the calibration means. That is, as shown in FIGS. 4 and 5, the calibration is performed based on the difference signal S with respect to the difference Zs from the in-focus position of the position of the sensor device at a plurality of sampling points for each material and surface type of the inspection object. A correction function for the application is obtained. The correction function is preferably a polynomial function of degree 3 or higher, and is obtained by, for example, a matrix solution method of the least square method as described above. The parameter values of the correction function thus obtained are stored in the correction function memory 70. This correction function is acquired and stored for the material and surface type of the inspection object.

The section shape measuring and correcting operation section 68 corresponds to the measuring means and measures the section shape of the inspection object 12. At this time, the difference Zs (= ΔZ) from the focus position of the sensor device 20 is calculated from the difference signal S from the sensor 54 and the correction function corresponding to the surface under measurement, and the position Z of the sensor device 20 is calculated as a correction value. Is added to And the scanning position X, Y
And the corrected position of the sensor device 20 (Z + ΔZ), the cross-sectional shape of the inspection object is obtained.

FIG. 7 is a flowchart for measuring the cross-sectional shape in the present embodiment. The measurement of the cross-sectional shape
It comprises a measurement procedure program creation process from steps S10 to S16, and an automatic measurement process from steps S18 to S28. The measurement procedure program creation step includes the above-described calibration step and teaching data creation step.

Here, the teaching data is defined as conditions such as the position to be measured of the object, the scanning direction, the condition of the illumination system, the magnification of the optical system, and the like in measuring the cross-sectional shape of the object. This is the data to be given, and in the subsequent automatic measurement process, for many specimens of the same type,
Automatic measurement according to the teaching data is performed. Therefore, the measurement procedure program includes the teaching data and the parameter data of the calibration correction function.

The flowchart of FIG. 7 shows an example of measuring the cross-sectional shape of the inspection object 12 having the mirror surface area shown in FIG. 4, for example, the metal surface 12A and the rough surface area, for example, the plastic surface 12B. In the first measurement procedure program creation step, a calibration step is performed on the metal surface 12A, and a parameter value of the correction function Zs = Fm (s) suitable for the surface is obtained (S1).
0). Further, teaching data Tm for the metal surface is created by the measurement operator (S12). Next, a calibration process is performed on the plastic surface 12B, and a correction function Zs = Fp adapted to the surface is performed.
The parameter value of (s) is obtained (S14). Furthermore,
Teaching data Tp for the plastic surface is created by the measurement operator (S16). Thus, the creation of the measurement procedure program is completed.

In the automatic measurement process, basically, while scanning the measurement location in accordance with the teaching data described above, the correction value Zs is applied to the position Z of the sensor device 20 using the parameter value of the correction function suitable for the surface. Add. That is, the parameter value of the correction function once obtained is not changed in the automatic measurement process.

However, if there is a significant difference between the surface condition of the test object corresponding to the correction function obtained in the calibration process and the surface condition of the test object to be actually automatically measured, the automatic measurement process is also performed. A new correction function parameter may be obtained by executing the calibration process again. That is, in steps S18 to S28,
The cross-sectional shape of the test object is measured, and it is determined whether the metal surface of the test object to be measured is significantly different from the surface of the sample in the calibration step (S1).
8) If there is a large difference, the calibration process is performed again on the metal surface of the inspection object to obtain a new correction function parameter value (S20). If not different, the parameter value of the correction function obtained in step S10 is used. Then, using the correction function and the teaching data Tm, the metal surface is scanned, the position Z of the sensor device 20 is detected while performing the servo control described above, and a correction operation is performed based on a difference signal S from the sensor. To obtain a correction value Zs (S22).

Next, when measuring the cross-sectional shape of the plastic surface 12B, it is similarly determined whether or not the surface condition is significantly different (S24). If the surface condition is significantly different, the calibration process is executed again, and a new correction function is performed. Is obtained (S26). If not different, the parameter value of the correction function obtained in step S14 is used.
Then, using the correction function and the teaching data Tp, the plastic surface is scanned, the position Z of the sensor device 20 is detected while performing the above-described servo control, and a correction operation is performed based on a difference signal S from the sensor. (S2
8).

The steps S18 and S24 are performed as follows.
For example, in a normal measurement process, the correction function automatically acquired first is used assuming that the surface state of the inspection object does not change. Change the processing flow. Alternatively, as another method, the measuring device is configured to perform step S18,
It is also possible to wait at 24 for an instruction from the operator.

In the above-described embodiment, a two-divided sensor is used. However, the present invention is not limited to this and can be similarly applied to a case where a line sensor or a light spot position detecting element PSD is used.

Further, in the above embodiment, the light spot is scanned on the inspection object while the sensor position is maintained at the in-focus position, the sensor position is measured, and the measured value is obtained in the calibration step. The shape of the surface of the device under test was measured by adding a correction value based on the correction function, but the sensor position was first set near the focus position, the position of the sensor position was fixed, and the light spot was placed on the device under test. The present invention is also applicable to the case where scanning is performed and the cross-sectional shape of the inspection object is measured from the shift amount ΔZ from the in-focus position obtained according to the difference signal S from the sensor. That is, such measurement can be applied when the cross-sectional shape of the object to be inspected is about the level difference within the dynamic range of the sensor.

Further, in the above embodiment, a correction function of a third-order polynomial is obtained for each of a large number of surface states. However, the present invention is not limited to a large number of surface states, and a correction function of a third-order polynomial is simply used. Even in this case, more accurate measurement of the cross-sectional shape can be performed.

[0051]

As described above, according to the present invention, since a plurality of correction functions corresponding to the surface of the object to be measured are obtained, accurate measurement of the cross-sectional shape can be performed regardless of the surface condition of the object to be inspected. It can be performed.

Further, according to the present invention, the relationship between the sensor output signal and the distance in accordance with the surface condition of the object to be inspected can be obtained more accurately by utilizing the matrix solution by the least squares method. It is possible to measure a complicated cross-sectional shape.

Further, according to the present invention, even after a function for correction is first obtained in the calibration step, calibration is appropriately performed according to the surface condition of the inspection object, and an optimum sensor output for the surface of the inspection object is obtained. Since the cross-sectional shape is measured according to the relationship between the signal and the distance, accurate cross-sectional shape measurement can be performed flexibly in accordance with the state of the inspection object.

Further, according to the present invention, by using at least a third-order polynomial function as a correction function, it is possible to more accurately measure the cross-sectional shape of the inspection object.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a cross-sectional shape measuring apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a Z value detected at the time of scanning and an actual cross-sectional shape of an inspection object and a difference signal S from a sensor.

FIG. 3 is a diagram illustrating an example of a relationship between a position (Z value) of a sensor device and a difference signal S with respect to surfaces of a plurality of types of inspection objects.

FIG. 4 is a diagram showing an example in which the surface of the inspection object is sampled by a calibration unit in the embodiment.

FIG. 5 is a diagram showing a distribution of sampling values of a difference signal S corresponding to a position (Z value) of a sensor device at a plurality of sampling points.

FIG. 6 is a detailed configuration diagram of a cross-sectional shape measuring apparatus according to the present embodiment.

FIG. 7 is a flowchart of measurement of a cross-sectional shape in the present embodiment.

FIG. 8 illustrates a knife edge method.

FIG. 9 is a diagram showing a signal detected by a two-division sensor.

[Explanation of symbols]

 Reference Signs List 20 sensor device 24, 26 stage 64 drive control unit 66 calibration control unit 68 section shape measurement unit

Claims (6)

[Claims] A light receiving optical system for changing a position of a light spot image projected according to a first distance between the test object and a photoelectric conversion element by using a light spot projected on the surface of the test object. A second distance between the stage on which the inspection object is mounted and the photoelectric conversion element so that the position of the light spot image projected on the photoelectric conversion element is at a predetermined position. Measuring means for scanning the light spot along the surface of the inspection object while controlling driving, distance detection means for detecting the second distance, and a sectional shape of the inspection object according to the second distance. In a cross-sectional shape measuring apparatus having a calculation means for obtaining, at a predetermined position of the inspection object, from the light spot image position signal detected from the photoelectric conversion element when the first distance is changed, The relationship between the first distance and the light spot image position signal,
Calibration means for acquiring a plurality of types of inspected objects, the arithmetic means, while scanning the surface of the inspected object, at the second distance detected, the light spot image position signal detected And a correction value up to the predetermined position obtained from the relationship between the first distance and the light spot image position signal corresponding to the type of the object to be inspected to obtain a sectional shape of the object to be inspected. A cross-sectional shape measuring device, characterized in that: 2. The method according to claim 1, wherein the calibration unit is obtained by sampling a number of points of each type of the inspection object when acquiring the relationship between the first distance and the light spot image position signal. A cross-sectional shape measuring apparatus, wherein a correction function is obtained from a plurality of the relations by a predetermined approximation calculation. 3. The method according to claim 2, wherein the correction function is at least a third-order polynomial function,
The cross-sectional shape measuring device is characterized in that the approximation operation is a matrix solution of a least squares method. 4. A light receiving optical system for changing the position of a light spot image projected on the surface of an object to be inspected according to a first distance between the object and a photoelectric conversion element. A second distance between the stage on which the inspection object is mounted and the photoelectric conversion element so that the position of the light spot image projected on the photoelectric conversion element is at a predetermined position. Scanning the light spots along the surface of the inspection object while controlling the drive, detecting the second distance, and calculating the cross-sectional shape of the inspection object according to the second distance. At a predetermined position of the inspection object, from the light spot image position signal detected from the photoelectric conversion element when the first distance is changed, the first distance and the light spot image position signal Relationship
Calibration step to obtain a plurality of types of inspected objects, and after the calibration step, while scanning the surface of the inspected object, at the second distance detected, the light spot image position signal detected And a correction value up to the predetermined position obtained from the relationship between the first distance and the light spot position signal corresponding to the type of the object to be inspected, and the cross-sectional shape of the object to be inspected is measured. A cross-sectional shape measuring method, comprising: an automatic measuring step; and performing the calibration step on a surface of an arbitrary inspection object as needed during the automatic measuring step. 5. The method according to claim 1, wherein the light spot projected on the surface of the object is changed via a light receiving optical system for changing a position of a light spot image projected according to a distance between the object and the photoelectric conversion element. Measuring means for projecting the light spot along the surface of the object to be projected onto the photoelectric conversion element and calculating a cross-sectional shape of the object according to a light spot image position signal detected from the photoelectric conversion element In a cross-sectional shape measuring apparatus having means, at a predetermined position of the inspection object, from the light spot image position signal detected from the photoelectric conversion element when the distance is changed, the distance and the light spot image position A calibration unit configured to acquire a relationship with a signal for a plurality of types of inspected objects, wherein the calculating unit scans the surface of the inspected object, and detects the light spot image position signal detected while scanning the surface of the inspected object; The distance corresponding to the type of inspection object From the relationship between the light spot image position signals, the cross-sectional shape measuring apparatus and obtaining the cross-sectional shape of the object to be inspected. 6. A light-receiving optical system for changing a position of a light spot image projected according to a first distance between the test object and a photoelectric conversion element by using a light spot projected on the surface of the test object. A second distance between the stage on which the inspection object is mounted and the photoelectric conversion element so that the position of the light spot image projected on the photoelectric conversion element is at a predetermined position. Measuring means for scanning the light spot along the surface of the inspection object while controlling driving, distance detection means for detecting the second distance, and a sectional shape of the inspection object according to the second distance. In a cross-sectional shape measuring apparatus having a calculation means for obtaining, at a predetermined position of the inspection object, from the light spot image position signal detected from the photoelectric conversion element when the first distance is changed, The relationship between the first distance and the light spot image position signal,
Calibration means for obtaining a correction function of at least a third-order polynomial by a predetermined approximation calculation, wherein the calculation means detects the second distance detected while scanning the surface of the inspection object. A cross-sectional shape of the inspection object is obtained by adding a correction value up to the predetermined position obtained from the light spot image position signal and the correction function.