JPH1068616A - Shape measuring equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an equipment for measuring the shape of an object by irradiating the object with light and receiving the reflected light thereby requiring a significant measuring time in which measurement accuracy of an inclining face is prevented from lowering by providing an interference light generating means. SOLUTION: The light emitted from a light source 3 and reflected on an object 1 is received at an image pickup section 6 through an enlarging microscopic optical system 5 having shallow depth of focus. When the object 1 has an inclining face, a shade 11 is opened to pass the light to a reference mirror 8 and interference fringes are generated based on a reference light reflected on the reference mirror 8 and the reflected light from the object 1. The image pickup section 6 can produce the image of the inclining face at high contrast by picking up the 0-order interference fringe.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shape measuring apparatus, and more particularly, to a high-speed and high-precision measurement of a surface shape of a fine three-dimensional part used for an ink jet printer, an optical communication device, or the like. The present invention relates to a shape measuring device.

[0002]

2. Description of the Related Art In recent years, electrical equipment and optical communication equipment have become more sophisticated.
The performance and performance have been improved, and the dimensions and shapes of the functional components used in these have become fine three-dimensional shapes in units of μm. For example, a marking head nozzle used in an ink jet printer has a diameter and a pitch interval of 10 μm to 1 μm.
It has a complicated and various shape including a straight line and a free-form surface according to the ink ejection principle.

In the inspection of such functional components, generally,
Processing accuracy is visually measured using an optical microscope. However, the visual measurement has a problem in that high measurement accuracy cannot be obtained because the measurement varies depending on the proficiency of the observer and the like.

As a solution to this problem, there has been proposed a shape measuring apparatus for measuring a fine three-dimensional shape with high accuracy by combining optical devices. For example, Japanese Patent Application Laid-Open No. Hei 7-113617 using the confocal principle has been proposed. Is disclosed in Japanese Unexamined Patent Application Publication No. 2000-205,878.

FIG. 18 shows a conventional shape measuring apparatus disclosed in Japanese Patent Application Laid-Open No. 7-113617, in which a laser diode 25 for emitting a laser beam based on a driving current supplied from a laser power control circuit 24, A collimator lens 27 that converts the laser beam into parallel light, an objective lens 28 that projects the parallel light onto the measurement target 29, a beam splitter 26 that separates reflected light from the measurement target 29,
An optical aperture unit 30 having a pinhole 30a, a photodiode 31 that receives the reflected light of the beam splitter 26 via the pinhole 30a and outputs an electric signal corresponding to the received light intensity, and an electric signal output from the photodiode 31 An amplifier 32 for amplifying; a tuning fork 34 arranged with one vibrating end in contact with a peripheral portion of the objective lens 28;
4, an amplitude detector 35 provided at the other vibrating end, and an amplifier 3 for amplifying an electric signal output from the amplitude detector 35.
6, a solenoid 37 for vibrating the tuning fork 34 based on the control current supplied from the tuning fork amplitude control circuit 38, and a distance conversion unit 39 for measuring the displacement of the surface of the measurement object 29 based on the output of the calculation unit 33. Have.

According to this shape measuring device, the distance from the position of the objective lens 28 to the object 29 to be measured when the objective lens 28 is vibrated by the light beam in the direction of the optical axis based on the vibration of the tuning fork 34 and a focal point is generated. Seeking. Therefore, the three-dimensional shape of the measurement target 29 can be obtained by scanning the laser beam two-dimensionally in a plane.

FIG. 19 shows another configuration for measuring the three-dimensional shape of the object to be measured based on the astigmatism method.
As shown in (a), a condenser lens 41 for condensing a laser beam 40 emitted from a laser light source (not shown) and reflected on a measurement object (not shown), and a condensed laser beam It is composed of a cylindrical lens 42 that projects onto the four-divided light receiving element 43.

If there is a change in height on the surface of the object to be measured,
Since the optical path length from the laser light source to the four-division light receiving element 43 changes, the imaging position fluctuates. When focusing is performed in front of the four-segment light receiving element 43, as shown in FIG.
Is projected onto the four-divided light receiving element 43. When focusing is performed on the four-segment light receiving element 43, a circular beam spot 44b is formed as shown in FIG.
Projected to When focusing is performed behind the four-segment light receiving element 43, the beam spot 44c having a horizontally long oval is formed as shown in FIG.
Projected to

When the beam spot has an elliptical shape as described above, a difference occurs between the electric signals output from the four elements of the four-divided light receiving element 43. The distance between the four-divided light receiving element 43 and the measurement object (not shown) is obtained based on the difference between the electric signals. Therefore, a three-dimensional shape of the measurement object (not shown) can be obtained by scanning the laser beam two-dimensionally in a plane.

[0010] However, the above two shape measuring devices are:
Since a three-dimensional shape is obtained by two-dimensionally scanning a measurement object with a laser beam, there is a problem that an enormous amount of time is required for measurement when the measurement area is wide.

In order to solve such a problem, an interference fringe is formed based on the reflected light reflected by the measurement object and the reference light reflected by the reference surface, and the measurement object is changed in the height direction. For example, Japanese Patent Application Laid-Open No. Hei 1-288702 discloses an interference-type shape measuring apparatus that collectively measures the three-dimensional shape of an object to be measured from the luminance information of the object.

FIG. 20 shows a conventional shape measuring apparatus disclosed in Japanese Patent Application Laid-Open No. 1-288702, in which a light source 45 for irradiating light with poor coherence and a light emitted from the light source 45 are reflected and transmitted. A half mirror 47 that divides the light into light and irradiates the measurement object 46 with reflected light, a reference mirror 48 that reflects light transmitted through the half mirror 47 to generate reference light, and an objective provided on the transmission side of the half mirror 47 A lens 49, a television camera 50 for imaging the surface of the measurement object 46 via the objective lens 49, a television monitor 51 for displaying the imaged surface of the measurement object 46, and an image signal input from the television camera 50. An image synthesis circuit 52 that performs calculation and image synthesis.

According to this interference type shape measuring device, the reflected light from the measuring object 46 and the reference light reflected by the reference mirror 48 are combined by the half mirror 47 and imaged by the television camera 50. At this time, while moving the reference mirror 48 from P ₀ to P ₁ and P ₂ , an interference fringe having the highest reflection intensity (hereinafter referred to as a zero-order fringe) is displayed at a position where the optical path lengths of the reflected light and the reference light match. Therefore, the position where the zero-order fringe occurs is input as height position information for each pixel. In the figure, reference mirror 48 when in the position of P _1, the interference fringes at the position indicated by B is observed as being formed. Therefore, a three-dimensional shape can be obtained from the height position information input by moving the reference mirror 48 in the optical axis direction.

Further, the image passed through the magnifying microscope optical system is divided into minute processing units, and the degree of focusing (hereinafter referred to as the degree of focusing) is measured from the degree of blurring of the image. A focus measurement type shape measuring device for obtaining a three-dimensional shape is disclosed in Journal of Precision Mechanical Engineering Vol. 60 No. 8, 1994
It is disclosed in "Synthesis of long depth of focus optical microscope image by image processing".

According to this focusing degree measuring type shape measuring apparatus, the object to be measured is moved up and down in the height direction, and the position where the degree of focusing is highest is regarded as the focal point, and height position information is obtained. I have.

[0016]

However, according to the conventional interference type shape measuring device, the reference mirror is moved in the direction of the optical axis so that the reflected light from the object to be measured and the optical path length are matched. It is necessary to adjust the moving amount and the tilt of the reference mirror with high accuracy, and there is a problem that the operation becomes complicated and the adjustment requires time.

Further, according to the shape measuring apparatus of the focusing degree measuring type, if there is an inclined surface in the range of the processing unit, the reflected light observed by the magnifying optical system becomes weak, so that a clear focusing point is specified. There is a problem that it becomes difficult. Therefore,
An object of the present invention is to provide a shape measuring apparatus capable of measuring a three-dimensional shape of a measurement object including an inclined surface at high speed and with high accuracy.

It is another object of the present invention to provide a shape measuring apparatus in which a reference mirror is provided as interference light generating means, but the frequency of use of the reference mirror is reduced.

Another object of the present invention is to provide a shape measuring apparatus which eliminates a decrease in the accuracy of determination of an inclined surface by a focus degree determining means.

[0020]

In order to achieve the above object, the present invention irradiates a measuring object with light and measures a three-dimensional shape of the measuring object based on reflected light of the measuring object. In the shape measuring device, a light source that emits the light that irradiates the measurement target has a depth of focus equal to or less than the measurement accuracy of the three-dimensional shape, and guides the light to the measurement target and the reflected light. Optical means for guiding the object in a predetermined direction and the object to be measured are placed, and the object to be measured is moved in the optical axis direction of the optical means by a unit movement amount equal to or less than the measurement accuracy over a predetermined movement amount. An optical axis direction scanning stage, interference light generating means for generating interference light that interferes with the reflected light, and located in the predetermined direction, the interference light being generated by interference between the reflected light or the reflected light and the interference light Receiving interference fringes Providing a shape measuring device for measuring the dimension shape.

In the above-described shape measuring apparatus, the optical means is preferably an enlarged microscope optical system using a lens with a high numerical aperture. The shape measuring means may be configured to measure a three-dimensional shape by receiving interference fringes generated by interference between reflected light and interference light when the measurement target includes an inclined surface,
Alternatively, when the measurement object does not include an inclined surface, a configuration may be adopted in which reflected light is received to measure a three-dimensional shape. Also,
The shape measuring means divides the light receiving element array for outputting a two-dimensional image signal in response to the reflected light or interference fringe and a predetermined number of light receiving element arrays each time the optical axis direction scanning stage moves by a unit movement amount. A calculation unit that calculates the degree of focus for each block, a determination unit that determines the presence or absence of a focus by comparing the degree of focus with a threshold, and 2 that is determined as a focus by the determination unit.
A configuration including a shape configuration unit that reproduces the three-dimensional shape of the measurement object by distributing the dimensional position in the optical axis direction based on the unit movement amount may be employed. It is preferable that the optical axis scanning stage and the interference light generating means have a configuration in which an initial position at the start of measurement is determined based on a position information table stored in the storage means in advance.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a shape measuring apparatus according to the present invention will be described with reference to the drawings.

FIG. 1 shows a shape measuring apparatus according to an embodiment of the present invention.
A light source 3 such as a halogen lamp for generating white light;
The half mirror 4 for reflecting the light generated in the above and irradiating the object to be measured 1, the enlarged microscope optical system 5 having a shallow depth of focus and an objective lens having a high numerical aperture, and the reflected light from the object 1 to be measured An imaging unit 6 such as a CCD camera that receives reflected light, a measurement target scanning stage 7 that displaces the measurement target 1 and the sample stage 2 in the Z direction, and a white light that enters through the half mirror 4 during interference measurement. A reference mirror 8 that reflects to generate reference light, a reference mirror scanning stage 9 that displaces the reference mirror 8 in the optical axis direction, and a condenser lens 1 that condenses white light on the reference mirror 8
0 and a light-shielding plate 11 that blocks an interference light path on which the reference mirror 8 is provided. By opening the light-shielding plate 11, interference measurement becomes possible.

The measuring object 1 has a height scale (not shown) in the Z direction, and this height scale is recognized as a height position described later at the time of imaging.

The feeding accuracy of the object scanning stage 7 is as follows.
It is determined by the measurement accuracy in the Z direction, and it is preferable that the feed amount is equal to the measurement accuracy or 1/10 of the measurement accuracy. For example, it is preferable to set the feed pitch to 0.1 μm in the measurement accuracy in the Z direction in units of 1 μm,
It can be realized by a motor with a high reduction gear.

The feeding accuracy of the reference mirror scanning stage 9 is determined by the measuring accuracy in the Z direction, and is preferably equal to the measuring accuracy or is set to be one tenth of the measuring accuracy. For example, a feed pitch of 0.1 μm is preferable for measurement accuracy in the Z direction in units of 1 μm, and can be realized by a linear actuator or the like using a piezoelectric element or the like.

FIG. 2 shows a control block of the shape measuring apparatus according to the embodiment of the present invention, and a measurement control unit 1 for executing shape measurement based on image data input from an image pickup unit 6.
2, the position information table of the measurement object scanning stage 7 and the reference mirror scanning stage 9 set according to the shape and size of the measurement object 1, and the measured measurement object 1
, A frame memory 14 for storing image data input from the image pickup unit 6 by dividing the image data into 512 × 512 pixels, and dividing the image data of the measurement target 1 into blocks of several pixels both vertically and horizontally. A focus calculating unit 15 for calculating the degree of focus of the image block obtained, and a focus for determining the focus and outputting the in-plane position (x, y) and the height scale in the Z direction of the image block as the height position. The determination unit 16, a shape configuration unit 17 that accumulates the height positions determined to be in focus in the Z direction to reproduce the three-dimensional shape of the measurement target 1, and a control signal output from the measurement control unit 12. Scanning stage drive circuit 1 that supplies a drive voltage to reference mirror scanning stage 9
8, and a scanning stage drive circuit 19 that supplies a drive voltage to the measurement object scanning stage 7 based on a control signal output from the measurement control unit 12.

FIG. 3 is a flowchart showing a shape measuring process when interference measurement is not performed. Hereinafter, the operation of the shape measuring apparatus according to the embodiment of the present invention will be described with reference to the flowchart.

First, the measurement object 1 is mounted on the sample table 2, a schematic shape and dimensions are input, and when a measurement start is instructed, the measurement control unit 12 performs the operation based on the position information table stored in the RAM 13. Then, a control signal is output to the scanning stage drive circuit 19, and a drive voltage according to the control signal is supplied from the scan stage drive circuit 19 to the measurement target scanning stage 7, and the measurement target 1 is positioned at a predetermined position.
After the positioning, the measurement object scanning stage 7 is moved in the Z direction to perform fine adjustment, and measurement is started after the height adjustment is made to coincide with the height scale 0. (Step S1).

Next, the light source 3 is turned on in a state where the interference light path on which the reference mirror 8 is provided is closed by the light shielding plate 11, and the object 1 is irradiated with white light via the half mirror 4 to enlarge the microscope. The reflected light from the measurement object 1 is imaged by the imaging unit 6 via the optical system 5 (step S2).

FIG. 4 shows an image pickup operation by the magnifying microscope optical system 5. For example, as shown in FIG. 4A, a case where a measurement object 20 having a conical protrusion is measured in the Z direction will be described. . Contour lines 20a are projected on the projection of the measurement object 20.
When the objective lens having a large depth of focus d is observed from the Z direction, a contour line arrangement as shown in FIG. 4B is obtained.

The magnifying optical system 5 is composed of a high numerical aperture objective lens having a shallow depth of focus d. When the object 1 to be measured is imaged by the imaging section 6, a clear image can be obtained in the range of the depth of focus d. Can be FIG. 4C shows an image captured in a state where the contour line 20a is located in the range of the depth of focus d of the enlarged microscope optical system 5. Only the contour lines in the range of the depth of focus d are clearly captured, and other parts are shown. Becomes ambiguous. Therefore, when the measurement object 1 is displaced in the Z direction, FIG.
As shown in (d) and (e), a clear image in the range of the depth of focus d can be obtained, and the height position in the Z direction can be quantified.

The numerical aperture of the objective lens constituting the magnifying microscope optical system 5 is determined based on the quantification accuracy required in the Z direction. For example, when measurement accuracy in the Z direction in units of 1 μm is required, it is preferable to use an objective lens having a numerical aperture of 0.7 or more that has a depth of focus of 1 μm or less. It is about 100 times, and the measurement area is 50 × 50 μm to 100 × 10
The range is 0 μm.

FIG. 5 shows an image based on the reflected light of the measurement object 1 imaged by the image pickup unit 6. As shown in FIG. 5A, the frame memory 14 stores the luminance of each pixel of the image pickup unit 6. Information (X _i , Y _i ) is stored, and the luminance information (X _i , Y _i ) is stored.
_i ) is further divided into image blocks 14A each composed of five pixels in the x and y directions corresponding to the X and Y directions as shown in FIG. 5B. The focus calculation unit 15 calculates the degree of focus based on the image block 14A.

The image of the measurement object 1 captured by the image capturing section 6 has a high spatial frequency in a focused portion in the range of the depth of focus d, while an unfocused portion has a high spatial frequency. Spatial frequency is low. From this,
In the present embodiment, the degree of focus is calculated using a Laplacian filter which is a second derivative as a filter for extracting a high spatial frequency component.

FIG. 6 shows a calculation process of the degree of focus using a Laplacian filter composed of a square matrix of 3 rows and 3 columns. The Laplacian filter L ₈ (i, j), the luminance value data matrix 14B of the image block 14A, and Is subjected to a matrix operation to obtain a second derivative image 21 and its luminance value data 21
A is obtained. The total sum 21B of the pixels in the row direction and the column direction of the secondary differential image 21 is the degree of focus. Sum value 2
The larger the value of 1B, the closer to the focal point (step S).
3).

Next, the degree of focus of each image block calculated by the focus calculation unit 15 is output to the focus determination unit 18 to determine focus. Since the reflected light from the measurement object 1 often includes image noise due to scattered light or the like, the focus determination unit 18 sets a threshold value in advance so as not to pick up a pseudo-focus point due to the image noise, and sets the threshold value. Extract only the height position that exceeds. This threshold is appropriately set based on the result of experimentally analyzing the reflected light characteristics and the like of the measurement object 1 in advance (step S4).

[0038] Figure 7 shows the change in height position in the cross-sectional shape and each image block of the measurement object 1, the height of the cross section of the measurement object 1 is changed from the image block x ₁ toward x _4. The arrow d provided on the scale at the height position indicates the range of the depth of focus.

[0039] Figure 8 shows the degree of focus from the image block x ₁ toward the height position 0 of the x ₄ 6, (a) an image block x _1, the (b) is an image block x _2, (c) Indicates the image block x ₃ , and (d) indicates the degree of focus of the image block x ₄ .

At the height position 3, FIGS. 8A and 8B
Image block x as shown in₁And x _TwoExceeds the threshold S
So, image block x₁And x_TwoHeight position is 3
Is determined. Determined image block x₁And x_TwoFocus degree
Are stored in the RAM 13.

Next, the object scanning stage 7 is displaced in the direction opposite to the direction of the imaging section 6 in accordance with the measurement accuracy, and the steps S2, S3 and S4 are executed, and the focus determination at the height position 4 is determined. Do.

At the height position 4, FIGS. 8B and 8C
Image block x as shown in_TwoAnd x _ThreeExceeds the threshold S
I have. Image block x_TwoExceeds the threshold even at height position 3
However, since the degree of focus at height position 4 is large,
Cook x_TwoIs determined to be 4. Also,
Cook x_ThreeExceeds the threshold value S, the image block x _Three
Is determined to be 4. The determined image block
x_TwoAnd x_ThreeIs stored in the RAM 13.

As described above, the measuring object scanning stage 7 is displaced in the Z direction, and steps S2, S3 and S4 are repeatedly executed, and the height position of each image block is stored in the RAM1.
3 is stored. Here, the x direction of the image block has been described for the sake of simplicity, but the same determination is made in the y direction.

The focus determination section 16 determines the focus of the image block whose focus degree exceeds the threshold value. If the focus is recognized at a different height as described above, the focus is determined. Select a height position with a greater degree. Therefore,
After determining the degree of focus of the image block at each height, the height position of the measurement object 1 is displaced to determine RA.
The data of the height position stored in M13 is updated. Therefore, the RAM 13 having a small storage capacity can be used, and the cost can be reduced.

When the scanning in the Z direction is completed, the height position data of the measurement object 1 stored in the RAM 13 is output to the shape forming unit 17 to form a three-dimensional shape.

Next, a case where interference measurement is performed using interference fringes generated by interference between the reference light reflected by the reference mirror 8 and the reflected light of the measurement object 1 will be described.

[0047] Figure 9 shows the change in height position in the cross-sectional shape and each image block of the measurement object 1, the inclined surface A is present in the cross section of the measurement object 1 in the image block x _2. The arrow d provided on the scale at the height position indicates the range of the depth of focus.

As described above, if the surface of the measurement object 1 has an inclined surface, a clear in-focus may not be obtained in the range of the depth of focus d of the enlarged microscope optical system 5 by the above-described method.

[0049] Figure 10 shows the focus degree of the image block x ₂ having an inclined surface A, the determination of focus is difficult to focus level does not exceed the threshold S. In this case, the light shielding plate 11 is opened, light is incident on the interference light path, and the light reflected by the reference mirror 8 is combined with the light reflected from the measurement object 1 by the half mirror 4 (step S2). The zero-order fringe of the interference fringes generated by this is imaged by the imaging unit 6 (step S4).
Steps S2 and S4 shown here indicate the contents of a flowchart described later.

FIG. 11 shows a configuration of calibration performed when performing shape measurement using a zero-order fringe. A triangular prism-shaped block gauge 22 having a gentle and smooth inclined surface and an X-direction stage 23 for scanning the block gauge 22 in the X direction are mounted on the sample stage 2. At this time,
The light shielding plate 11 provided in the interference light path is opened and the light source 3
Is incident on the reference mirror 8.

Next, a zero-order fringe appears. Since the range of the zero-order fringe in the Z direction is limited to 0.2 μm, and the depth of focus d of the enlarged microscope optical system 5 is about 1 μm, it is necessary to adjust the interference optical system.

FIG. 12 shows the block gauge 22 in an enlarged manner. The object scanning stage 7 and the X-direction stage are arranged so that the inclined surface of the block gauge 22 is imaged within the range of the depth of focus d at the center of the image. 23 is driven to perform positioning.

Next, the reference mirror scanning stage 9 is driven in the optical axis direction of the reference light to search for the position where the zero-order fringe appears, and the position where the zero-order fringe appears appears as the initial value of the reference mirror scanning stage 9. I do. The initial values of the measuring object scanning stage 7 and the reference mirror scanning stage 9 at this time are stored in the RAM 13 as a position information table.

Next, in order to confirm the adjustment of the interference optical system, the measuring object scanning stage 7 is moved by h at intervals of the measuring accuracy in the Z direction, and at the same time, the reference mirror scanning stage 9 is also moved by h.
Just move. The position of the inclined surface of the block gauge 22 focused within the depth of focus d is recorded, and it is confirmed that a zero-order fringe is generated at this position, and the adjustment is terminated. By the adjustment using the above-described block gauge, the image of the inclined surface A having a strong contrast based on the zero-order fringe is captured by the imaging unit 6 without adjusting the appearance of interference fringes for each measurement object.

FIG. 13 is a flow chart of the shape measurement using the zero-order fringe, in which an interference optical system for generating the zero-order fringe is formed (step S2), the reference mirror 8 is adjusted (step S3), and the zero-order fringe is adjusted. The processes other than the imaging of the next fringe (step S4) are the same as those of the shape measurement operation described above, and thus the duplicate description will be omitted. Steps S2 and S4 have been described above. In step S3, the reference mirror scanning stage 9 is sent by a distance equal to the amount of displacement for moving the measuring object 1 in the height direction. Thereby, the distance from the half mirror 4 to the measurement target 1 and the distance from the half mirror 4 to the reference mirror 8 are always equal,
Zero-order fringes occur.

FIG. 14 shows image blocks x ₁ to x when the shape of the measurement object 1 is measured using the zero-order fringe.
Indicate the degree of focus from height positions 0 to 6 of ₄ and use a zero-order fringe to obtain a clear image of the inclined surface, so that the height position can be determined based on the degree of focus.
Therefore, as shown in FIG. 14 (b), it is determined from the image block x ₂ having an inclined surface exceeds the threshold value S in the height position 4, the height position 4 and.

As described above, since the object to be measured 1 is imaged through the microscopic optical system having a small depth of focus, a high resolution can be obtained in the height direction with a simple configuration, and the captured image is divided into a plurality of image blocks. By calculating the degree of focus, highly accurate shape measurement can be performed. In addition, since the height position of the measurement target is determined based on the calculated focus degree based on the threshold value, the focus degree at each height position can be determined in a short time, and the storage capacity of the frame memory or RAM can be reduced. A small device can be used, and the cost of the entire apparatus can be reduced. Furthermore, for a measurement object having an inclined surface, by performing interference measurement based on the zero-order fringe,
High-precision measurement is possible even on inclined surfaces.

In this embodiment, the configuration in which the measurement target 1 is moved in the Z direction has been described. However, the configuration in which the measurement target 1 is fixed and the imaging unit 6 is moved in the Z direction may be employed. The above-described interference optical system can also perform interference measurement on a flat measurement target, and is also effective in measurement of a measurement target whose inclination is difficult to grasp.
In the above-described shape measuring apparatus, by using the magnifying microscope optical system 5 having a small depth of focus and a high magnification, 100 × 10
Although image measurement can be performed in a range of about 0 μm, a two-dimensional scanning mechanism or the like can be used in combination when performing image measurement over a wider range.

Further, the light source 3 is not limited to a halogen lamp or the like, and it is preferable to select and use a light source that generates light having a wavelength characteristic according to the peak sensitivity of the imaging unit 6.

In this embodiment, the Laplacian filter is used as an operator for calculating the degree of focusing. For example, the relationship between the image block position and the total luminance value shown in FIG. It is also possible to evaluate based on the variance value of the luminance of the image or the level and amplitude of the high frequency component based on the two-dimensional Fourier transform shown in FIG.

[0061]

As described above, according to the shape measuring apparatus of the present invention, the interference fringes generated by the interference between the reflected light reflected by the object to be measured and the interference light generated by the reference mirror are received. Since the shape is measured, the three-dimensional shape of the measurement object including the inclined surface can be measured at high speed and with high accuracy.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a shape measuring device according to an embodiment of the present invention.

FIG. 2 is a control block of the shape measuring device according to the embodiment of the present invention.

FIG. 3 is a flowchart of the shape measuring device according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram illustrating an imaging principle of the shape measuring device according to the embodiment of the present invention.

FIG. 5A is a captured image of a measurement target 1 stored in a frame memory 14, and FIG.
FIG. 3 is an explanatory diagram showing an image block configured by being divided into × 5 pixels.

FIG. 6 is an explanatory diagram illustrating a calculation process of a focus degree according to the embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a relationship between an image block x of the measurement object 1 imaged by the imaging unit 6 and a height position Z.

8 is an explanatory diagram showing a relationship between the focus of the height position Z for x ₄ from the image block x _1.

FIG. 9 is an explanatory diagram showing a relationship between an image block x and a height position Z of a measurement object 1 having an inclined surface A.

10 is an explanatory view showing the relationship between the focus of the image block x ₂ the inclined surface A is present and the height position Z.

FIG. 11 is an explanatory diagram showing a configuration when an interference measurement function of the shape measurement device according to the embodiment of the present invention is used.

FIG. 12 is an explanatory diagram showing positioning of a block gauge 22;

FIG. 13 is a flowchart in the case where the interference measurement function of the shape measuring apparatus according to the embodiment of the present invention is used.

FIG. 14 shows image blocks x ₁ to x ₄ when the interference measurement function of the shape measuring device according to the embodiment of the present invention is used.
FIG. 4 is an explanatory diagram showing a relationship between a focus degree and a height position Z for (1).

FIG. 15 is an explanatory diagram showing another evaluation method for calculating the degree of focus in the embodiment of the present invention.

FIG. 16 is an explanatory diagram showing another evaluation method for calculating the degree of focus in the embodiment of the present invention.

FIG. 17 is an explanatory diagram showing another evaluation method for calculating the degree of focus in the embodiment of the present invention.

FIG. 18 is an explanatory view showing a conventional shape measuring device.

FIG. 19 is an explanatory view showing a conventional shape measuring device.

FIG. 20 is an explanatory diagram showing a conventional shape measuring device.

[Explanation of symbols]

 Reference Signs List 1, measurement object 2, sample table 3, light source 4, half mirror 5, magnifying microscope optical system 6, imaging unit 7, measurement object scanning stage 8, reference mirror 9, reference mirror scanning stage 10, condensing lens 11, Light shielding plate 12, measurement control unit 13, RAM 14, frame memory 15, focus calculation unit 16, focus determination unit 17, shape configuration unit 18, scan stage drive circuit 19, scan stage drive circuit 20, measurement object 21, Second derivative image 21B, luminance value data 22, block gauge 23, X-direction stage 24, laser power control circuit 25, laser diode 26, beam splitter 27, collimator lens 28, objective lens 29, measurement object 30, optical aperture unit 31, photodiode 32, amplifier 33, operation unit 34, tuning fork 35, amplitude detector 36, amplifier 37, solenoid 8, tuning fork amplitude control circuit 39, distance conversion unit 40, laser beam 41, objective lens 42, cylindrical lens 43, quadrant light receiving element 44a, 44b, 44c, beam spot 45, light source 46, measuring object 47, half mirror 48 , Reference mirror 49, objective lens 50, television camera 51, television monitor 52, image composition circuit

Claims (6)

[Claims] 1. A shape measuring apparatus that irradiates light to a measurement target and measures a three-dimensional shape of the measurement target based on reflected light of the measurement target, wherein the light that irradiates the measurement target is A light source that emits light, an optical unit that has a depth of focus equal to or less than the measurement accuracy of the three-dimensional shape, guides the light to the measurement target, and guides the reflected light in a predetermined direction; An optical axis direction scanning stage for mounting an object and moving the object to be measured over a predetermined amount of movement in a unit movement amount equal to or less than the measurement accuracy in the optical axis direction of the optical means; and interference light interfering with the reflected light. An interference light generating means for generating the interference light; and a shape measuring means for measuring the three-dimensional shape by receiving the reflected light or an interference fringe generated by interference between the reflected light and the interference light. It is special to have A shape measuring apparatus. 2. The shape measuring apparatus according to claim 1, wherein said optical means is an enlarged microscope optical system using a lens with a high numerical aperture. 3. The configuration in which the shape measuring means measures the three-dimensional shape by receiving the interference fringes generated by interference between the reflected light and the interference light when the measurement target includes an inclined surface. The shape measuring device according to claim 1. 4. The shape measuring apparatus according to claim 1, wherein said shape measuring means measures said three-dimensional shape by receiving said reflected light when said object to be measured does not include an inclined surface. 5. The shape measuring means includes: a light receiving element array for outputting a two-dimensional image signal in response to the reflected light or the interference fringe; and each time the optical axis scanning stage moves by the unit movement amount. A calculating unit that calculates a degree of focus for each block obtained by dividing the light receiving element array into a predetermined number, a determining unit that determines the presence or absence of a focal point by comparing the degree of focus with a threshold value, and 2 determined as focused
The shape measuring apparatus according to claim 1, further comprising a shape forming unit that reproduces a three-dimensional shape of the measurement target by distributing a three-dimensional position in the optical axis direction based on the unit movement amount. 6. An apparatus according to claim 1, wherein said optical axis direction scanning stage and said interference light generating means determine an initial position at the start of measurement based on a position information table stored in advance in a storage means. Shape measuring device.