JP6820515B2 - Surface shape measuring device and surface shape measuring method - Google Patents

Description

The present invention relates to a surface shape measuring device and a surface shape measuring method, and in particular, the surface of a surface to be measured by an optical unit having at least a light source, a plurality of objective lenses having different magnifications, and an imaging unit for acquiring a measurement image. The present invention relates to a surface shape measuring device for measuring a shape and a surface shape measuring method.

The surface shape measuring device is a device that measures the three-dimensional shape of the surface to be measured of an object to be measured, and is a light source that outputs light for measuring the surface shape of the surface to be measured, and the light output from the light source is used as the surface to be measured. For example, a white interference microscope (Patent Document 1) or a laser cofocal microscope is known as a surface shape measuring device composed of at least an objective lens to be irradiated and a photographing unit for acquiring a measurement image of a surface to be measured.

Then, the surface shape measuring device of the optical unit having the above configuration needs to at least select an objective lens having an appropriate magnification from a plurality of objective lenses having different magnifications and adjust an appropriate amount of light of the light source as measurement preparation alignment. .. The measurement accuracy of the surface shape of the surface to be measured differs depending on whether or not this measurement preparation alignment is performed properly.

By the way, in a surface shape measuring device provided with an objective lens such as the above optical unit, the measurement range of the surface to be measured that can be measured in one measurement may be limited due to the limitation of the measurement field of view of the objective lens. There are many. For this reason, stitching measurement is performed by placing the object to be measured on a horizontally movable stage, measuring the surface to be measured multiple times, and then calculating using software processing or the like to connect a plurality of measurement data. Is known to do.

Therefore, in order to perform the stitching measurement with high accuracy, it is necessary to properly perform the measurement preparation alignment of the magnification selection of the objective lens and the light intensity adjustment for each of a plurality of measurements.

Japanese Unexamined Patent Publication No. 2016-136091

However, conventionally, since the selection of the objective lens and the adjustment of the light amount of the light source are performed based on the experience of the operator, there is a problem that the measurement accuracy of the surface shape varies depending on the proficiency of the operator. In particular, in stitching measurement, if there is a variation in the measurement accuracy for each of a plurality of measurements, the accuracy of the surface shape obtained by connecting a plurality of measurement data becomes poor, which is a serious problem.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a surface shape measuring device and a surface shape measuring method capable of improving the accuracy of surface shape measurement.

In order to achieve the object, the surface shape measuring device according to one aspect of the present invention uses a support portion that supports the object to be measured, a light source that outputs light for measuring the surface shape of the surface to be measured of the object to be measured, and a light source. A plurality of objective lenses having different magnifications for irradiating the surface to be measured with the output light, an optical unit having at least an imaging unit for acquiring a measurement image of the surface to be measured, and a support portion moved in the in-plane direction of the surface to be measured. A plurality of measuring surfaces composed of an in-plane moving means for making the measured surface, a rough shape acquiring means for acquiring the rough shape information of the surface to be measured, and an inclined region and a flat region for the measured surface based on the rough shape information. The object surface dividing means to be divided into two, and the objective lens having a magnification to be used among a plurality of objective lenses according to the measurement contribution irradiation amount that contributes to the measurement when the divided inclined region and flat region are irradiated with light. The objective lens selection means for selecting the above, the light amount adjusting means for adjusting the light amount of the light source according to the measurement contribution irradiation amount that contributes to the measurement when the divided inclined region and the flat region are irradiated with light, and the support portion. Measurement surface shape measurement to acquire a plurality of measurement data by individually measuring the surface shape based on the selected objective lens and the adjusted light amount by moving each of the divided measurement surfaces in the in-plane direction of the surface to be measured. A means and a data connecting means for connecting a plurality of acquired measurement data are provided. A white interferometer or a laser confocal microscope can be applied as the optical unit.

According to the surface shape measuring apparatus of the present invention, it is possible to properly perform measurement preparation alignment for selection of an objective lens and adjustment of the amount of light of a light source when measuring the surface shape of a surface to be measured, so that surface shape measurement can be made highly accurate. It can be done and is especially effective in stitching measurement.

In the surface shape measuring apparatus of the present invention, the measurement field of view of the objective lens is narrower than the measured surface of the object to be measured, and it is preferable to measure the surface shape of the measured surface by stitching measurement. This is because the present invention is particularly effective in stitching measurement.

As the surface shape measuring device of the present invention, a white interferometer can be preferably used for the optical unit.

In the surface shape measuring apparatus of the present invention, it is possible to provide a measurement contributing irradiation light amount detecting means for detecting the measurement contributing irradiation amount G of the irradiation light that returns to the objective lens and contributes to the measurement among the light irradiated to the surface to be measured through the objective lens. preferable.

Then, the objective lens selection means selects an objective lens having a magnification to be used based on the ratio G / F of the measurement contribution irradiation amount G to the total irradiation light amount F of the irradiated light for the divided inclined region and flat region. .. As a result, it is possible to select an objective lens having an appropriate magnification for performing measurement with high accuracy in the inclined region and the flat region.

Further, the light amount adjusting means uses the measurement contribution irradiation amount G when measuring the flat region as the reference light amount for the divided inclined region and the flat region, and the measurement contribution irradiation amount G when measuring the inclined region is the reference. Adjust the amount of light from the light source so that the amount of light is the same. As a result, it is possible to adjust an appropriate amount of light source light for performing measurement with high accuracy depending on the inclined region and the flat region.

In the surface shape measuring apparatus of the present invention, the surface shape of the surface to be measured of the object to be measured is preferably a wavy shape. This is because the present invention is particularly effective when the surface shape of the surface to be measured is the object to be measured.

In the surface shape measuring device of the present invention, the approximate shape acquiring means is preferably any of a triangulation type laser displacement meter, a stereo camera, and a pattern projection device.

In the surface shape measuring apparatus of the present invention, the approximate shape acquiring means is preferably a holding means for holding CAD data of the object to be measured.

In the surface shape measuring apparatus of the present invention, the approximate shape acquiring means is preferably a white interferometer using a low magnification lens having a smaller magnification than the objective lens of the optical unit.

In the surface shape measuring apparatus of the present invention, it is preferable to have a display unit that displays an objective lens map selected by the objective lens selection means for a plurality of measurement surfaces divided by the surface shape measuring means to be measured.

In order to achieve the object, the surface shape measuring method according to one aspect of the present invention uses a support portion that supports the object to be measured, a light source that outputs light for measuring the surface shape of the surface to be measured of the object to be measured, and a light source. Using a surface shape measuring device having at least a plurality of objective lenses having different magnifications for irradiating the surface to be measured with the output light of the above, and an optical unit having at least an imaging unit for acquiring a measurement image of the surface to be measured. A surface shape measuring method for measuring the surface shape of a measurement surface, which includes a schematic shape acquisition process for acquiring the approximate shape information of the surface to be measured, and an inclined region and a flat region for the surface to be measured based on the schematic shape information. Multiple objective lenses according to the measurement contribution irradiation amount that contributes to the measurement when the divided inclined region and flat region are irradiated with light and the surface division step to be divided into a plurality of measurement surfaces composed of The amount of light from the light source is adjusted according to the objective lens selection step of selecting the objective lens of the magnification to be used and the measurement contribution irradiation amount that contributes to the measurement when the divided inclined region and flat region are irradiated with light. By moving the support portion in the in-plane direction of the surface to be measured, the surface shape of each divided measurement surface is individually measured based on the selected objective lens and the set amount of light, and a plurality of measurements are performed. It includes a measurement surface shape measurement step for acquiring data and a data connection step for connecting a plurality of acquired measurement data.

According to the surface shape measuring method of the present invention, the objective lens can be selected when measuring the surface shape of the surface to be measured and the measurement preparation alignment for adjusting the light intensity of the light source can be appropriately performed, so that the surface shape measurement can be made highly accurate. It can be done and is especially effective in stitching measurement.

According to the surface shape measuring device and the surface shape measuring method of the present invention, it is possible to appropriately select an objective lens and perform measurement preparation alignment for adjusting the amount of light of a light source when measuring the surface shape of the surface to be measured. The measurement can be made highly accurate.

Overall configuration diagram of the surface shape measuring device according to the embodiment of the present invention Conceptual diagram showing an example of a plurality of types of objective lenses having different magnifications provided in the interference portion of the optical portion. The figure which showed the pixel array of the interference fringes on the xy coordinate of the image pickup surface of an image sensor The figure which illustrated the relationship between the z position of an interference part and a luminance value, and an interference fringe curve. A diagram illustrating the relationship between different z-coordinate values at different points on the surface to be measured and the interference fringe curve. Explanatory drawing of surface shape measurement by stitching measurement Perspective view showing an example of a measurement object having a swell-shaped surface to be measured. Explanatory drawing explaining one aspect of laser displacement meter of schematic shape acquisition means Explanatory drawing explaining one aspect of stereo camera of schematic shape acquisition means Explanatory drawing explaining one aspect of white interference meter of schematic shape acquisition means Explanatory drawing of a surface dividing means to be measured, an objective lens selecting means, a light amount adjusting means, a measuring surface shape measuring means, and a data connecting means mounted on a processing unit of a surface shape measuring device. Explanatory drawing of step threshold Explanatory drawing explaining an example in which a swell-shaped measurement surface is divided into a plurality of measurement surfaces of an inclination angle adjustment and a flat region. Explanatory drawing explaining an example of selecting an objective lens having a different magnification in an inclined region and a flat region by an objective lens selection means. Explanatory drawing explaining the behavior of light when light is irradiated to the surface under measurement of tilt angle θ2 with the objective lens of prospect angle θ1. A graph showing the relationship between the tilt angle of the surface to be measured and the ratio of the measurement contribution irradiation light amount that contributes to the measurement to the total irradiation light amount. Flow chart of the surface shape measuring method according to the embodiment of the present invention Explanatory drawing of the objective lens map

Hereinafter, preferred embodiments of the surface shape measuring apparatus and the surface shape measuring method of the present invention will be described with reference to the accompanying drawings.

The present invention will be described in the following preferred embodiments. Changes can be made by many methods without departing from the scope of the present invention, and other embodiments other than the present embodiment can be used. Therefore, all modifications within the scope of the present invention are included in the claims.

Here, in the figure, the parts indicated by the same symbols are similar elements having the same functions. Further, in the present specification, when the numerical range is expressed by using "~", the numerical values of the upper limit and the lower limit indicated by "~" are also included in the numerical range.

[Surface shape measuring device]
In the surface shape measuring device of the present embodiment, a light source that outputs light for measuring the surface shape of the surface to be measured of the object to be measured, an objective lens that irradiates the surface to be measured with light output from the light source, and a surface to be measured. As an optical unit having at least an imaging unit for acquiring the measured image of the above, an example of a vertical scanning type white interferometer will be described below.

Further, a case where the measurement field of view of the objective lens is smaller than the surface to be measured of the object to be measured and stitching measurement is performed will be described.

FIG. 1 is a configuration diagram showing the overall configuration of the surface shape measuring device according to the embodiment of the present invention.

The surface shape measuring device 1 in FIG. 1 uses a Michaelson type interferometer to measure the surface shape of the surface S to be measured of the object P to be measured three-dimensionally by non-contact, so-called Michaelson type scanning white interference. An optical unit 2 that is a meter (microscope) and acquires interference fringes (interference images) of the object P to be measured, a stage 10 as a support portion on which the object P to be measured is placed, and various types of surface shape measuring devices 1. The processing unit 18 and the like including an arithmetic processing device such as a personal computer that performs various arithmetic processes based on the interference fringe image acquired by the control and the optical unit 2 are provided.

In the present embodiment, the example of the Michelson type scanning white interferometer will be described, but a well-known Millow type scanning white interferometer may be used. Further, in the measurement space where the measurement object P is arranged, the two horizontal coordinate axes orthogonal to each other are set as the x-axis (axis parallel to the paper surface) and the y-axis (axis orthogonal to the paper surface), and the x-axis and y-axis The coordinate axis in the vertical direction orthogonal to is defined as the z-axis. The z-axis is parallel to the measurement optical axis Z-0 described later. Then, the processing unit 18 has xyz coordinates indicating a point on the measured surface S by the x coordinate of the x axis, the y coordinate of the y axis, and the z coordinate of the z axis, and obtains the three-dimensional position of the measured surface S. Can be done.

The stage 10 is a flat surface substantially parallel to the x-axis and the y-axis, and has a stage surface 10S on which the measurement object P is placed. Further, the stage 10 includes an in-plane moving means 35 for horizontally moving the stage 10 in the in-plane direction of the surface S to be measured relative to the optical unit 2.

The in-plane direction moving means 35 is composed of an x actuator 34 and a y actuator 36. Then, the stage 10 horizontally moves in the x-axis direction by driving the x-actuator 34, and horizontally moves in the y-axis direction by driving the y-actuator 36. By moving the stage 10 in the x-axis direction and the y-axis direction, the surface S to be measured of the measurement object P placed on the stage 10 is moved with respect to the optical unit 2.

The term actuator in the present specification, such as the x-actuator 34 and the y-actuator 36, refers to an arbitrary driving device such as a piezo actuator or a motor.

Further, an optical unit 2 integrally held by the housing 2A (see FIG. 2) is arranged at a position facing the stage surface 10S, that is, on the upper side of the stage 10.

The optical unit 2 includes a light source unit 12 having an optical axis Z-1 parallel to the x-axis, an interference unit 14 having an optical axis parallel to the z-axis (measurement optical axis Z-0), and a photographing unit 16. .. The optical axis Z-1 of the light source unit 12 is orthogonal to the measurement optical axis Z-0 of the interference unit 14 and the photographing unit 16, and intersects the measurement optical axis Z-0 between the interference unit 14 and the photographing unit 16. To do. The optical axis Z-1 does not necessarily have to be parallel to the x-axis.

The light source unit 12 emits a light source 40 that emits white light having a wide wavelength width (low coherence light with little coherence) as illumination light that illuminates the object P to be measured, and an illumination light that is diffused and emitted from the light source 40. It has a collector lens 42 that converts light into a substantially parallel light source. The central axes of the light source 40 and the collector lens 42 are coaxially arranged as the optical axis Z-1 of the light source unit 12.

Further, as the light source 40, any kind of light emitting body such as a light emitting diode, a semiconductor laser, a halogen lamp, and a high-intensity discharge lamp can be used.

The illumination light emitted from the light source unit 12 is arranged between the interference unit 14 and the photographing unit 16, and is a half mirror or the like arranged at a position where the optical axis Z-1 and the measurement optical axis Z-0 intersect. It is incident on the beam splitter 44 of the above. Then, the illumination light reflected by the beam splitter 44 (the flat light dividing surface (reflecting surface) of the beam splitter 44) travels along the optical axis Z-0 and is incident on the interference portion 14.

The interference unit 14 is composed of a Michelson type interferometer, and divides the illumination light incident from the light source unit 12 into measurement light and reference light. Then, the measurement object P is irradiated with the measurement light and the reference light is irradiated to the reference mirror 52 to generate interference light in which the measurement light returning from the measurement object P and the reference light returning from the reference mirror 52 interfere with each other.

The interference unit 14 has a light-collecting action, a plurality of objective lenses 50 having different magnifications, a reference mirror 52 which is a reference surface for reflecting light and has a flat reflecting surface, and a flat light splitting which divides light. It has a beam splitter 54 having a surface. The axes at the centers of the objective lens 50, the reference mirror 52, and the beam splitter 54 are coaxially arranged as the measurement optical axis Z-0 of the interference unit 14. The reflecting surface of the reference mirror 52 is arranged at a lateral position of the beam splitter 54 in parallel with the measurement optical axis Z-0.

FIG. 2 is a conceptual diagram showing an objective lens 50 provided in the interference unit 14 of the optical unit 2.

As shown in FIG. 2, a revolver 2B is provided on the surface of the housing 2A that holds the optical unit 2 on the side to be measured, and the revolver 2B has a low magnification lens 50A, a medium magnification lens 50B, and a high magnification lens 50C. Is fixed. Then, the objective lens 50 used for the measurement scanning of the interference unit 14 can be selected by rotating the revolver 2B according to the instruction of the processing unit 18.

The objective lens 50 is not limited to the above three types, and two of the low magnification lens 50A, the medium magnification lens 50B, and the high magnification lens 50C may be combined, or four or more objective lenses 50. May be provided to subdivide the magnification.

Returning to FIG. 1, the illumination light incident on the interference unit 14 from the light source unit 12 is focused by the objective lens 50 and then incident on the beam splitter 54.

The beam splitter 54 is, for example, a half mirror, and the illumination light incident on the beam splitter 54 is split into a measurement light that passes through the beam splitter 54 and a reference light that is reflected by the light splitting surface of the beam splitter 54.

The measurement light transmitted through the beam splitter 54 is applied to the surface S to be measured of the object P to be measured, then returns from the surface S to be measured to the interference portion 14, and is incident on the beam splitter 54 again. Then, the measurement light transmitted through the beam splitter 54 is incident on the objective lens 50.

On the other hand, the reference light reflected by the beam splitter 54 is reflected by the light reflecting surface of the reference mirror 52 and then incidents on the beam splitter 54 again. Then, the reference light reflected by the beam splitter 54 is incident on the objective lens 50.

As a result, interference light is generated in which the measurement light irradiated from the interference unit 14 to the measured surface S of the measurement object P and returned to the interference unit 14 and the reference light reflected by the reference mirror 52 are superimposed, and the interference is generated. After the light is focused by the objective lens 50, it is emitted from the interference unit 14 toward the photographing unit 16.

Further, after the illumination light is divided into the measurement light and the reference light, the optical path of the optical path through which each of the measurement light and the reference light passes until the measurement light and the reference light are superimposed is determined by the optical path of the measurement light. The length and the optical path length of the reference light are called, and the difference between them is called the optical path length difference between the measurement light and the reference light.

The interference unit actuator 56 is provided as a scanning means for changing the optical path length of the measurement light by measuring and scanning the interference unit 14 in the vertical direction along the measurement optical axis Z-0 (z axis) of the measurement light. Then, the interference unit 14 moves in the z-axis direction (measurement scanning direction) by driving the interference unit actuator 56. As a result, the position (height) of the focal plane of the objective lens 50 moves in the z-axis direction, and the distance between the surface S to be measured and the beam splitter 54 changes, so that the optical path length of the measurement light changes, and the measurement is performed. The optical path length difference between the light and the reference light changes.

The photographing unit 16 is an interference fringe acquisition unit that acquires interference fringes from the brightness information of the interference light due to the measurement light irradiated to each point of the measurement surface S of the measurement object P and the reference light, for example, a CCD ( It corresponds to a Charge Coupled Device) camera and has a CCD type image pickup element 60 and an imaging lens 62. The central axes of the image sensor 60 and the image lens 62 are coaxially arranged as the measurement optical axis Z-0 of the photographing unit 16. As the image pickup device 60, any imaging means such as a CMOS (Complementary Metal Oxide Semiconductor) type solid-state image pickup device can be used.

The interference light emitted from the interference unit 14 is incident on the beam splitter 44 described above, and the interference light transmitted through the beam splitter 44 is incident on the imaging unit 16.

The interference light incident on the photographing unit 16 forms an interference fringe image on the image pickup surface 60S of the image pickup element 60 by the image pickup lens 62. Here, the imaging lens 62 magnifies the interference fringe image with respect to the region around the measurement optical axis Z-0 of the measurement surface S of the measurement object P at a high magnification and forms an image on the image pickup surface 60S of the image pickup element 60. ..

Further, the imaging lens 62 forms an image of a point on the focal plane of the objective lens 50 of the interference unit 14 as an image point on the imaging surface of the image sensor 60. That is, the photographing unit 16 is designed so that the position of the focal plane of the objective lens 50 is in focus (focused).

The interference fringe image formed on the image pickup surface 60S of the image pickup element 60 is converted into an electric signal by the image pickup element 60 and acquired as interference fringes. Then, the interference fringes are given to the processing unit 18.

As described above, the optical unit 2 including the light source unit 12, the interference unit 14, the photographing unit 16, and the like is provided as an integral body so as to be movable in the z-axis direction. For example, the optical unit 2 is supported by a z-axis guide unit (not shown) erected along the z-axis direction so as to be movable in a straight line. Then, the entire optical unit 2 moves linearly in the Z-axis direction by driving the z-actuator 70. As a result, the focus position of the imaging unit 16 can be moved more in the z-axis direction than when the interference unit 14 is moved in the z-axis direction. For example, the imaging unit can be moved according to the thickness of the measurement object P or the like. The focus position of 16 can be adjusted to an appropriate position.

When measuring the surface shape of the surface S to be measured of the object P to be measured, the processing unit 18 controls the interference unit actuator 56 to move the interference unit 14 of the optical unit 2 in the z-axis direction, while the processing unit 18 of the imaging unit 16 Interference fringes are sequentially acquired from the image sensor 60. Then, based on the acquired interference fringes, the three-dimensional shape data of the surface S to be measured is acquired as data indicating the surface shape of the surface S to be measured.

Here, a process in which the processing unit 18 acquires the three-dimensional shape data of the surface S to be measured based on the interference fringes will be described.

The image sensor 60 of the photographing unit 16 is composed of a large number of light receiving elements (pixels) two-dimensionally arranged along an xy plane (horizontal plane) composed of an x-axis and a y-axis. Then, the brightness value of the interference fringes received by each pixel, that is, the brightness value of each pixel of the interference fringes acquired by the image pickup element 60 is the measurement light reflected at each point of the surface S to be measured corresponding to each pixel. The intensity (luminance information) of the interference light according to the difference in the optical path length between the light and the reference light is shown.

Here, as shown in FIG. 3, the pixels in the m-th column and the n-th row in the interference fringes on the xy coordinates of the image pickup surface 60S of the image pickup element 60 are assumed to represent (m, n). Then, the x-coordinate value indicating the position of the pixel (m, n) in the x-axis direction (hereinafter, the position in the x-axis direction is referred to as “x position”) is expressed as x (m, n). Then, the y coordinate value indicating the position related to the y-axis direction (hereinafter, referred to as the position “y position” related to the y-axis direction) is represented by y (m, n).

Further, the x-coordinate value indicating the x-position of the point on the measured surface S of the measurement object P corresponding to the pixel (m, n) is represented by X (m, n), and the y-coordinate value indicating the y-position is Y. It shall be expressed as (m, n), and the point shall be expressed as (X (m, n), Y (m, n)) by the xy coordinate value.
The point on the measured surface S corresponding to the pixel (m, n) is the point on the measured surface S on which the image point is formed at the position of the pixel (m, n) in the focused state. Means a point.

At this time, the brightness values of the pixels (m, n) of the interference fringes acquired by the image sensor 60 are the points (X (m, n), Y (X (m, n), Y () on the surface to be measured S corresponding to the pixels (m, n). The magnitude corresponding to the optical path length difference between the measurement light and the reference light irradiated to m, n)) is shown.

That is, the interference unit 14 is measured and scanned in the z-axis direction by the interference unit actuator 56 in FIG. 1, and the position of the interference unit 14 relative to the optical unit 2 (photographing unit 16) in the z-axis direction (hereinafter, “z position””. When the) is displaced, the focus position of the photographing unit 16 (the focal plane of the objective lens 50) also moves in the z-axis direction, and the focus position is also displaced by the same amount of displacement as the interference unit 14. Further, when the focus position is displaced, the optical path length of the measurement light applied to each point of the surface S to be measured also changes.

Then, while moving the interference unit 14 in the z-axis direction to displace the focus position, that is, while changing the optical path length of the measurement light, the interference fringes are sequentially acquired from the image sensor 60 and any pixel of the interference fringes ( The brightness value of m, n) is detected.

Here, the processing unit 18 can detect the displacement amount of the interference unit 14 from a predetermined reference position (z position of the interference unit 14) by a detection signal from a position detection means (not shown) such as a potentiometer or an encoder. it can. Alternatively, when controlling the z position of the interference unit 14 without using the position detecting means, for example, when moving the interference unit 14 by a constant displacement amount by a drive signal given to the interference unit actuator 56, the total displacement amount. Can be detected by.

Then, the z position of the focus position when the interference unit 14 is the reference position is set as the reference position (origin position) of the z coordinate in the measurement space, and the displacement amount of the interference unit 14 from the reference position is the z coordinate value of the focus position. Can be obtained as. The z coordinate value has a positive side at a position higher than the origin position (a position closer to the photographing unit 16) and a negative side at a lower position (a position closer to the stage surface 10S). Further, the reference position of the interference unit 14, that is, the origin position of the z coordinate can be set or changed to an arbitrary z position.

(A) to (C) of FIG. 4 show when an image is acquired from the image sensor 60 of the photographing unit 16 while raising the interference unit 14 from a position close to the measured surface S of the measurement object P in the z-axis direction. It is a figure which showed the relationship between the z position of the interference part 14 and a luminance value.

As shown in FIG. 4A, when the optical path length L1 of the measurement light is smaller than the optical path length L2 of the reference light, the interference is small and the brightness value is substantially constant. Then, as shown in FIG. 4B, when the optical path length L1 of the measurement light and the optical path length L2 of the reference light are the same, that is, when the optical path length difference becomes 0, the interference becomes large and the maximum luminance value is shown. .. Further, as shown in FIG. 4C, when the optical path length L1 of the measurement light is larger than the optical path length L2 of the reference light, the interference becomes small again and the luminance value becomes substantially constant. As a result, the luminance value along the interference fringe curve Q shown in FIG. 4D can be obtained.

That is, the interference fringe curve Q at an arbitrary pixel (m, n) is located at a point (X (m, n), Y (m, n)) on the surface to be measured S corresponding to the pixel (m, n). When the optical path length difference between the irradiated measurement light and the reference light is larger than the predetermined value, a substantially constant brightness value is shown, and when the optical path length difference is smaller than the predetermined value, the brightness value increases as the optical path length difference decreases. As it vibrates, its amplitude increases.

Therefore, as shown in FIG. 4D, the interference fringe curve Q shows the maximum value when the optical path lengths of the measurement light and the reference light match (when the optical path length difference is 0), and the maximum value thereof is shown. The maximum value in the envelope of the interference fringe curve Q is shown.

Further, the optical path length between the measurement light and the reference light applied to the points (X (m, n), Y (m, n)) on the measurement surface S is such that the focus position of the photographing unit 16 is the measurement surface S. It matches when it matches the z position of the upper point (X (m, n), Y (m, n)).

Therefore, when the interference fringe curve Q shows the maximum value (or when the envelope of the interference fringe curve Q shows the maximum value), the focus position is the point (X (m, n), Y ( It matches the z-position of m, n)), and the z-coordinate value of the focus position at that time is the z-coordinate of the point (X (m, n), Y (m, n)) on the surface S to be measured. Indicates a value.

From the above, the processing unit 18 moves the interference unit 14 in the z-axis direction by the interference unit actuator 56 to move the focus position in the z-axis direction (while changing the optical path length of the measurement light), while the image sensor Interference fringes are sequentially acquired from 60, and the luminance value of each pixel (m, n) is acquired in association with the z-coordinate value of the focus position. That is, the brightness values of each pixel (m, n) of the interference fringes are acquired while scanning the focus position in the z-axis direction. Then, for each pixel (m, n), the z coordinate value (interference fringe position) of the focus position when the brightness value of the interference fringe curve Q as shown in FIG. 3D shows the maximum value is set to each pixel (m). , N) is detected as the z-coordinate value Z (m, n) of the point (X (m, n), Y (m, n)) on the surface S to be measured.

Note that Z (m, n) indicates the z coordinate value of the point (X (m, n), Y (m, n)) on the measured surface S corresponding to the pixel (m, n).

Further, a method of detecting the z-coordinate value of the focus position when the luminance value of the interference fringe curve Q indicates the maximum value is well known, and any method may be adopted. For example, by acquiring the interference fringes at the z-coordinate values for each minute interval of the focus position, it is possible to actually draw the interference fringe curve Q as shown in FIG. 3D for each pixel (m, n). The brightness value can be obtained to the extent. Then, by detecting the z-coordinate value of the focus position when the acquired luminance value indicates the maximum value, the z-coordinate value of the focus position when the luminance value of the interference fringe curve Q indicates the maximum value can be detected. it can.

Alternatively, the interference fringe curve Q is estimated by the least squares method or the like based on the luminance value acquired at each z coordinate value of the focus position, or the envelope of the interference fringe curve Q is estimated. Then, by detecting the z-coordinate value of the focus position when the luminance value shows the maximum value based on the estimated interference fringe curve Q or the envelope, when the luminance value of the interference fringe curve Q shows the maximum value. The z-coordinate value of the focus position can be detected.

As described above, the processing unit 18 has each point (X (m, n), Y) on the measured surface S corresponding to each pixel (m, n) of the interference fringe (imaging surface 60S of the image sensor 60). By detecting the z-coordinate value Z (m, n) of (m, n)), the relative height of each point (X (m, n), Y (m, n)) on the surface to be measured S is Can be detected.

Then, the x-coordinate values X (m, n), y-coordinate values Y (m, n), and z-coordinate values Z (m, n) of each point on the measured surface S are the three-dimensional shapes of the measured surface S. It can be acquired as data (data indicating the surface shape).

For example, as shown in FIG. 5, when the z-coordinate values Z1, Z2, and Z3 at three points on the measured surface S corresponding to the three pixels arranged in the x-axis direction are different, the focus position is scanned in the z-axis direction. While acquiring the brightness values of those pixels of the interference fringes. As a result, interference fringe curves Q1, Q2, and Q3 indicating the maximum luminance value when the focus position is the z coordinate values Z1, Z2, and Z3 for each of those pixels are acquired. Therefore, by detecting the z-coordinate value of the focus position when the luminance values of the interference fringe curves Q1, Q2, and Q3 show the maximum values, z at three points on the measured surface S corresponding to those pixels The coordinate values Z1, Z2, and Z3 can be detected. In this way, the surface shape of the object P to be measured is measured by acquiring the three-dimensional shape data of the surface S to be measured.

When a vertical scanning white interferometer is used as the optical unit 2 as described above, it is possible to measure with one measurement due to the limitation of the measurement field of view W which is the maximum imaging area of the objective lens 50 used for the interferometer 14. In many cases, the measurement field of view of the surface S to be measured is limited.

Therefore, as shown in FIG. 6, the measurement object P is placed on the stage 10 that can move horizontally in the x-axis direction and the y-axis direction, and the measured surface S of the measurement object P is measured at a constant ratio. Measure multiple times while moving so that the ranges overlap. Then, after that, stitching measurement is performed to measure the surface shape of the surface S to be measured by connecting a plurality of measurement data by calculation using software processing or the like.

In this embodiment, the surface S to be measured is measured at a constant ratio so that the measurement ranges overlap, but the measurement may not overlap. W in FIG. 6 shows the measurement field of view of the objective lens 50, but is actually the area of a square having a width of W.

By the way, as described in the prior art, in the surface shape measuring device 1 having the light source 40, the plurality of objective lenses 50 having different magnifications, and the optical unit 2 including the photographing unit 16, the interfering unit 14 is used as the measurement preparation alignment. It is necessary to at least select the plurality of objective lenses 50 having different magnifications provided in the above and adjust the amount of light of the light source 40.

The measurement accuracy of the surface shape differs depending on whether or not this measurement preparation alignment is performed properly. In particular, as shown in FIG. 7, stitching measurement is performed in which a swell-shaped surface to be measured S having a surface shape having an inclined region D and a flat region K is measured a plurality of times, and then a plurality of measurement data are connected. When this is performed, the measurement accuracy between the inclined region D and the flat region K tends to vary. Therefore, if the measurement preparation alignment regarding the selection of the objective lens 50 and the light amount adjustment of the light source 40 is not properly performed for each of a plurality of measurements, the accuracy of the surface shape measurement deteriorates.

Therefore, the surface shape measuring device 1 according to the embodiment of the present invention is provided with the following configuration for performing surface shape measurement with high accuracy in addition to the above basic configuration.

That is, as shown in FIG. 1, mainly, the approximate shape acquisition means 72, the surface to be measured dividing means 74, the objective lens selecting means 75, the light amount adjusting means 76, the measuring surface shape measuring means 77, and the data connecting means. It was equipped with 78.

(Rough shape acquisition means)
The approximate shape acquisition means 72 acquires the approximate shape information of the surface S to be measured, and can distinguish between the inclined region D (see FIG. 7) and the flat region K (see FIG. 7) on the surface S to be measured. It may be of a relatively low accuracy, and priority is given to being able to measure at high speed and in a wide range. As the approximate shape acquisition means 72, it is preferable to adopt the following three types.

The first rough shape acquisition means 72 is a case where a triangulation type laser displacement meter, a stereo camera, a pattern projection device, and the like are separately provided. FIG. 8 shows a concept in which the approximate shape of the inclined region D and the flat region K of the measured surface S is acquired by moving the triangulation type laser displacement meter 72A along the in-plane direction of the measured surface S. It is a figure.

In the triangulation type laser displacement meter 72A, a part of the diffuse reflection of the laser irradiated on the surface S to be measured of the object P to be measured passes through the light receiving lens to form a spot on the light receiving element, and the object P to be measured is measured. When the distance to is displaced, the spot also moves. This is a method of measuring the approximate shape of the surface S to be measured by detecting the spot position. By receiving the diffuse reflected light in the reflected light, the measurement range can be widened.

The stereo camera 72B can record information in the depth direction by simultaneously photographing the surface S to be measured of the object P to be measured from a plurality of different directions, reproduce the binocular parallax with one unit, and grasp the three-dimensional space. It is possible to take a stereoscopic photograph that can be done.

FIG. 9 is a diagram in which the measured surface S of the measurement object P is imaged by two cameras 73, whereby the approximate shape of the measured surface S can be acquired.

Although not shown, the pattern projection method is a method of projecting pattern light onto a surface S to be measured of a measurement object P and obtaining three-dimensional coordinates of points on the pattern reflected in the image. Then, the approximate shape of the surface S to be measured can be obtained by acquiring the three-dimensional shape data from each point on the pattern with the three-dimensional coordinates corresponding to those points by the principle of triangulation.

As the approximate shape acquisition means 72 such as the triangulation type laser displacement meter 72A, the stereo camera 72B, and the pattern projection device, known ones can be used.

As shown in FIG. 1, the approximate shape acquisition means 72 that needs to be newly installed, such as the laser displacement meter 72A, the stereo camera 72B, and the pattern projection device, is arranged at a lateral position of, for example, the optical unit 2. Further, a stage moving means 80 for reciprocating the stage 10 between the lower position of the optical unit 2 and the lower position of the approximate shape acquisition means 72 is provided. As a result, when the approximate shape of the surface S to be measured of the measurement object P placed on the stage 10 is acquired by the approximate shape acquisition means 72, the stage 10 is moved to the lower side of the optical unit 2 by the stage moving means 80. To do. In the present embodiment, one stage 10 is moved between the lower position of the optical unit 2 and the lower position of the approximate shape acquisition means 72, but a stage for the approximate shape acquisition means 72 is separately provided. When the approximate shape acquisition by the approximate shape acquisition means 72 is completed, the user may mount the measurement object P on the stage 10.

The second approximate shape acquisition means 72 is a holding means (not shown) for holding CAD (computer-aided-design) data of the measurement object P, and the storage means of the processing unit 18 can be used. .. As described above, if the holding means for holding the CAD data of the measurement object P is used as the rough shape acquisition means 72, it is necessary to separately provide the rough shape acquisition means 72 like the first rough shape acquisition means 72. Absent. Further, the CAD data held by the holding means already has the three-dimensional shape data of the measurement object P. As a result, it is not necessary to measure the approximate shape of the surface S to be measured of the object P to be measured, which contributes to shortening the measurement time.

The third approximate shape acquisition means 72 is a case where the approximate shape is pre-measured by a white interferometer using a low-magnification lens capable of measuring a wide range at high speed as the objective lens 50 of the interference unit 14. In this case, it can be configured by using the low magnification lens 50A of the existing objective lens 50 in the interference portion 14 of the surface shape measuring device 1 of the present embodiment. Therefore, even in the case of the third rough shape acquisition means 72, it is not necessary to separately provide the rough shape acquisition means 72.

Then, as shown in FIG. 10, the approximate shape of the surface S to be measured can be obtained by sampling and measuring the vicinity of a plurality of feature points of the surface S to be measured by the interference unit 14 switched to the low magnification lens 50A. it can. The feature point is, for example, a stepped edge portion of the surface S to be measured.

The approximate shape information of the measured surface S acquired by these approximate shape acquiring means 72 is sent to the measured surface dividing means 74.

(Measurement surface dividing means)
The surface to be measured dividing means 74 comprises an inclined region D and a flat region K on the surface to be measured S based on the approximate shape information acquired by the approximate shape acquiring means 72, and one area is the measurement field of view of the objective lens 50. It is divided into a plurality of measurement surfaces N of W or less.

Here, the inclined region D and the flat region K are flat regions and regions that appear to be inclined as an overview of the entire surface S to be measured when the approximate shape information is displayed on the display unit 20 (see FIG. 1). It refers to a visible area and does not include inclination or flatness when the fine irregularities of the surface S to be measured are enlarged.

Further, the inclined region D refers to an inclined surface and a region in the vicinity thereof, and is not limited to one inclined surface, and includes a case where inclined surfaces having different inclination angles are connected. The flat region K refers to a flat surface and a region in the vicinity thereof, and the flat region may be substantially flat.

FIG. 11 shows a processing unit in which the surface to be measured dividing means 74, the objective lens selecting means 75, the light amount adjusting means 76, the measuring surface shape measuring means 77, and the data connecting means 78, which will be described in detail later, are composed of an arithmetic processing unit such as a personal computer. This is the case when it is mounted on 18.

The surface dividing means 74 to be measured, the objective lens selecting means 75, the light amount adjusting means 76, the measuring surface shape measuring means 77, and the data connecting means 78 shall be configured as dedicated hardware without being mounted on the processing unit 18. However, in the present embodiment, it is constructed by using the program executed in the processing unit 18. That is, the CPU (Central-Processing-Unit) of the processing unit 18 constitutes the arithmetic processing unit, and the surface to be measured dividing means 74, the objective lens selecting means 75, the light amount adjusting means 76, the measuring surface shape measuring means 77, and the data connecting means. Functions as 78.

As shown in FIG. 11, the processing unit 18 is equipped with the surface dividing means 74 to be measured, the objective lens selecting means 75, the light amount adjusting means 76, the measuring surface shape measuring means 77, and the data connecting means 78, and the approximate shape acquiring means 72. The approximate shape information from is input to the surface dividing means 74 to be measured. Further, the three-dimensional coordinates (xyz coordinates) of the approximate shape information in the approximate shape acquisition means 72 are also input to the processing unit 18.

Then, the surface dividing means 74 to be measured matches the three-dimensional coordinates of the rough shape information acquired by the rough shape acquisition means 72 with the three-dimensional coordinates of the measurement object P placed on the stage 10. As a result, the measurement target P and the approximate shape information are aligned. Then, based on the approximate shape information, the surface to be measured S is divided into a plurality of measurement surfaces N composed of an inclined region D and a flat region K and having one area equal to or less than the measurement field of view W. In this case, the surface to be measured S is divided at a constant ratio so that the measurement surfaces N overlap.

The surface dividing means 74 to be measured is preferably identified by a threshold value of a step formed by a height difference between the inclined region D and the flat region K (hereinafter, referred to as a step threshold).

As shown in FIG. 12, for example, when the maximum swell height h of the swell shape (maximum thickness h1-minimum thickness h2 of the object to be measured P) is 100 μm, the step threshold value R is set to, for example, 10 μm. As a result, the surface dividing means 74 to be measured determines the region having a height difference of 10 μm or more as the inclined region D on the surface S to be measured, and determines the region having a height difference of less than 10 μm as the flat region K. How much the step threshold value R is set can be determined based on the maximum swell height h of the swell shape of the surface S to be measured, the size of the swell width, the swell cycle, and the like.

The number of the step threshold value R to be set may be set in advance in the measured surface dividing means 74, but the user can arbitrarily set it in the measured surface dividing means 74 by using the input unit 22 or the like. Is preferable. As a result, the number of divisions of the surface S to be measured can be appropriately selected according to the surface shape of the surface S to be measured.

In FIG. 13, the wavy surface S to be measured shown in FIG. 7 is divided into 16 measurement surfaces N _{1 to} N ₁₆ having a quadrangular shape in the x-axis direction and the y-axis direction by the measurement surface dividing means 74. It is explanatory drawing which set the minimum scanning range Z _{1 to} Z ₈ of the interference part 14 which is the minimum necessary for measuring and scanning the maximum height existing in the measurement surface for each divided measurement surface N.

FIG. 13A shows the minimum scanning ranges Z _{1 to} Z ₈ of the 16 divided measurement surfaces N, and FIG. 13B shows the ₁₆ measurement surfaces N _{1 to} N ₁₆ divided. In FIG. 13B, the mesh-like portion indicates an overlapping portion between the measurement surfaces N. Further, FIG. 13C shows the measurement field of view W of the objective lens 50 of the interference unit 14.

As shown in FIG. 13B, assuming that the 16 measurement surfaces N are named N ₁ to N ₁₆ , for example, the minimum scanning range of the measurement surface N ₁ and the measurement surface N ₉ is Z ₁ . Further, the minimum scanning range of the measurement surface N ₈ and the measurement surface N ₁₆ is Z ₈ . Similarly, the minimum measurement scanning settings Z _{2 to} Z ₇ can be set for the measurement surfaces N _{2 to} N ₇ and the measurement surfaces N _{10 to} N ₁₅ .

As another method in which the measured surface dividing means 74 divides the measured surface S into the inclined region D and the flat region K, the user divides the measured surface using the display unit 20 and the input unit 22. A division area can also be specified for the means 74. That is, the user visually identifies the approximate shape information displayed on the display unit 20 into the inclined region D and the flat region K, and inputs the position coordinates (xy coordinates) of the identified divided regions. Then, the surface to be measured dividing means 74 divides the surface to be measured S into an inclined region D and a flat region K based on a designation from the user. Further, if the surface S to be measured can be divided into an inclined region D and a flat region K, the method is not limited to the above division method.

(Objective lens selection means)
As will be described below, the objective lens selecting means 75 responds to the measurement contribution irradiation amount that contributes to the measurement when the inclined region D and the flat region K are irradiated with light from the light source 40 for each of the divided measurement surfaces N. The objective lens 50 having the magnification to be used is selected from the plurality of objective lenses 50.

FIG. 14 is an explanatory diagram showing an example in which an objective lens 50 having a different magnification is selected by the objective lens selection means 75 in the inclined region D and the flat region K divided by the surface dividing means 74 to be measured.

When the surface shape of the surface S to be measured of the object P to be measured has a wavy shape as shown in FIG. 14, the light irradiated to the surface S to be measured through the objective lens 50 is likely to be scattered. As a result, the light returning to the objective lens 50 becomes weak, and the image becomes noisy at the photographing unit 16, so that the measurement accuracy deteriorates.

On the other hand, as a characteristic of the objective lens 50, the high-magnification lens 50C having a high numerical aperture (NA) can capture brighter and higher-resolution even in weak light than the low-magnification lens 50A having a low numerical aperture, and the low-magnification lens 50A. Has a wider measurement field than the high-magnification lens 50C.

Therefore, as shown in FIG. 14, the objective lens selection means 75 selects the low-magnification lens 50A having a wide measurement field of view W but poor measurement accuracy on the inclined surface for the measurement of the flat region K, and the measurement accuracy on the inclined surface is high. A high-magnification lens 50C, which is good but has a narrow measurement field of view W, is selected for the measurement of the inclined region D. As a result, both the inclined region D and the flat region K can be measured with high accuracy, and by using the low-magnification lens 50A having a wide measurement field of view in the flat region K, a wide range can be measured in a short time, and measurement preparation is possible. The alignment time can be shortened.

The reference numeral Wx in FIG. 14 indicates the width of the measurement surface N in the in-plane direction (x-axis) of the surface to be measured S, and Wz indicates the scanning range of the interference unit 14 in the z-axis direction.

Next, an objective lens selection method of how to select an objective lens 50 having an appropriate magnification from a plurality of objective lenses 50 by the inclined region D and the flat region K will be described.

FIG. 15 is an explanatory diagram illustrating the behavior of light when the objective lens 50 having a viewing angle θ1 irradiates the surface S to be measured with an inclination angle θ2 with light. In FIG. 15, the inclination angle θ2 is the inclination angle of the surface S to be measured with respect to the horizontal plane 17.

That is, when light is irradiated from the objective lens 50 having a prospect angle θ1 to the surface S to be measured of the measurement object P having an inclination angle θ2 in the air, the light A returns to the objective lens 50, that is, the irradiation light A and the objective that contribute to the measurement. There is an irradiation light B that does not return to the lens 50, that is, does not contribute to the so-called measurement. Reference numeral C indicates a reflection region of the irradiation light B that does not return to the objective lens 50, and reference numeral 15 is a normal line perpendicular to the surface to be measured S.

In FIG. 15, since the numerical aperture (NA) = sin θ1 is established in the air, the theoretical measurement limit inclination angle θ2 _max of the inclination angle θ2 of the surface S to be measured can be expressed by asin (NA). .. For example, in the case of the objective lens 50 having an NA of 0.3, the measurement limit tilt angle θ2 _max is about 17 °. That is, it can be said that measurement is possible if the equation of inclination angle θ2 <asin (NA) of the surface to be measured S is satisfied. In other words, in the case of the objective lens 50 having an NA of 0.3, it can be determined that measurement is not possible if the inclination angle of the surface S to be measured exceeds 17 °, and measurement is possible if it is 17 ° or less.

However, in reality, the equation of θ2 <asin (NA) is the theoretical measurement limit tilt angle θ2 _max , and it is not realistic to apply it as it is as a criterion for selecting the objective lens 50. A realistic criterion is the ratio (G / G) of the measurement contribution irradiation light amount (G) that contributes to the measurement returning to the objective lens 50 with respect to the total irradiation light amount (F) of the light emitted to the surface S to be measured through the objective lens 50. It is preferable to determine by F).

FIG. 16 shows, for example, assuming a uniform irradiation light in the objective lens 50 having an NA of 0.3, the inclination angle θ2 of the surface S to be measured and the measurement contribution irradiation light amount (G) with respect to the total irradiation light amount (F). It is a graph which showed the relationship with the ratio (G / F).

The horizontal axis of FIG. 16 indicates the inclination angle θ2 (°) of the surface S to be measured, and the vertical axis indicates G / F. When the G / F is less than 0.2 (less than 20%), it becomes impossible to measure with the objective lens 50 having an NA of 0.3, and it is necessary to select the objective lens 50 having an NA (large magnification) larger than 0.3. There is. From the graph of FIG. 15, when the G / F is 0.2, the inclination angle θ2 is about 12 °, and in reality, the inclination angle 12 ° is the measurement limit inclination angle θ2 _max .

From this, the G / F at the measurement limit tilt angle θ2 _max is obtained in advance by a preliminary test or the like for each of the plurality of objective lenses 50 provided in the interference unit 14. Then, by knowing the measurement contribution irradiation light amount (G) of the inclined region D and the flat region K, an objective lens 50 having an appropriate magnification for measuring the inclined region D and the flat region K with high accuracy is selected. can do. The total irradiation light amount (F) can be known from the output of the light source 40 without measuring.

Therefore, it is preferable that the surface shape measuring device 1 according to the embodiment of the present invention is further provided with the measurement contribution irradiation light amount detecting means 82 (see FIGS. 2 and 11) for detecting the measurement contribution irradiation light amount (G). Then, the objective lens selection means 75 selects the objective lens 50 having a magnification to be used based on the G / F by the divided inclined region D and the flat region K. As a result, the objective lens 50 having an appropriate magnification can be selected from the plurality of objective lenses 50 by the inclined region D and the flat region K.

The method of selecting the objective lens 50 having an appropriate magnification is not limited to the measurement contribution irradiation light amount detecting means 82. If the measurement limit tilt angle θ2 _max can be obtained by measuring the tilt angle of the tilted region D or the flat region K, the objective lens 50 having an appropriate magnification is based on the measurement limit tilt angle θ2 _max , which is a direct index. May be selected. Alternatively, the approximate shape information of the measurement object P acquired by the approximate shape acquisition means 72 is displayed on the display unit 20, and the operator visually determines the degree of the inclination angle of the inclined region D and the flat region K to determine the degree of the inclination angle of the objective lens. 50 may be selected.

(Light intensity adjusting means)
As will be described below, the light amount adjusting means 76 responds to the measurement contribution irradiation amount that contributes to the measurement when the inclined region D and the flat region K are irradiated with light from the light source 40 for each of the divided measurement surfaces N. The amount of light of the light source 40 is adjusted.

The idea described with reference to FIG. 15 can also be used for adjusting the amount of light of the light source 40. For example, assuming a uniform irradiation light in the objective lens 50 having an NA of 0.3, the inclination angle θ2 of the surface S to be measured and the measurement contribution irradiation light amount (G) that contributes to the measurement with respect to the total irradiation light amount (F). The relationship with the ratio (G / F) is shown in the graph of FIG.

Here, the G / F (about 0.56) when the inclination angle θ2 of the surface S to be measured is, for example, 6 ° is about half of the G / F (1.0) when the inclination angle θ2 is 0 °. , The measurement accuracy is lowered due to insufficient light intensity.

Therefore, when the inclination angle θ2 of the surface S to be measured is, for example, 6 °, the light amount adjusting means 76 adjusts the amount of light to about twice the amount of light when the inclination angle θ2 is 0 °. As described above, it is possible to avoid a decrease in measurement accuracy due to insufficient light amount caused by an increase in the inclination angle of the surface S to be measured, using the amount of light when the inclination angle θ2 is 0 ° as a reference light amount. As a result, even when a plurality of measurement surfaces N exist from a small inclination angle to a large inclination angle such as a swell shape of the surface S to be measured, the surface shape of each measurement surface N can be measured with high accuracy. it can.

Therefore, the light amount adjusting means 76 can use the measurement contribution irradiation light amount (G) detected by the measurement contribution irradiation light amount detecting means 82 in the light amount adjusting method of the light source 40. That is, the light amount adjusting means uses the measurement contribution irradiation amount G when measuring the flat region K as the reference light amount, and the light amount of the light source 40 so that the measurement contribution irradiation amount G when measuring the inclined region D becomes the reference light amount. To adjust.

As a result, the amount of light in the inclined region D and the flat region K becomes the same, so that both regions D and K can be measured with high accuracy and the measurement accuracy can be made uniform.

(Measuring surface shape measuring means)
The measuring surface shape measuring means 77 moves the stage 10 in the in-plane direction of the surface S to be measured by the in-plane moving means 35, so that each of the divided measuring surfaces N is selected as the objective lens 50 and the adjusted light source 40. A plurality of measurement data are acquired by individually measuring the surface shape based on the amount of light.

That is, the measuring surface shape measuring means 77 moves the measured surface S in the in-plane direction by the in-plane moving means 35, so that the divided measurement surfaces N are selected as the objective lens 50 and the adjusted light source 40. The surface shape is individually measured based on the above, and a plurality of measurement data are acquired.

That is, the interference portion 14 is measured and scanned in the vertical direction within the range of the minimum scanning range Z _{1 to} Z ₈ set for each of the ₁₆ measurement surfaces N _{1 to} N ₁₆ shown in FIG. 13, and each measurement surface N _{1 to} N is measured. The surface shape of ₁₆ is measured. Processing unit 18, for example, first to obtain a minimum scanning range Z ₁ only measure the scanned surface shape of the measurement surface N ₁ and the measurement surface N _1. Next, to obtain the surface shape of the measurement surface N ₂ scans measured measurement surface N ₂ by a minimum scan range Z _2. This is repeated until the measuring surface _{N 16.}

(Data connection means)
The data connecting means 78 connects the measurement data of each measuring surface N acquired by the measuring surface shape measuring means 77. As a result, the surface shape of the entire surface S to be measured can be measured. As a method of connecting each measurement surface N by the data connection means 78, a known method such as software processing can be adopted.

[Surface shape measurement method]
Next, a surface shape measuring method for measuring the surface shape of the object to be measured P having the wavy surface S to be measured will be described using the surface shape measuring device 1 of the present invention configured as described above.

FIG. 17 is a step flow for measuring the surface shape of the surface S to be measured of the object P to be measured by the stitching measurement method. For easy explanation, as shown in FIG. 7, the surface shape measuring method of the present embodiment has a wavy shape only in the x-axis direction, and the length in the x-axis direction is the measurement field of view W of the objective lens 50 of the interference portion 14. An example of the measurement object P, which is longer than the measurement object P and has a length in the y-axis direction slightly shorter than the measurement visual field W, will be described.

First, the rough shape acquisition means 72 performs a rough shape acquisition step of acquiring the rough shape information of the surface S to be measured of the measurement object P (step 10). The approximate shape acquisition means 72 is a low field of view as an objective lens of the above-mentioned triangular survey type laser displacement meter, stereo camera, pattern projection device, holding means for holding CAD (computer-aided-design) data, and interference unit 14. Any white interferometer using a magnification lens may be used.

Next, the surface dividing means 74 to be measured matches the three-dimensional coordinates of the rough shape information by the rough shape acquisition means 72 with the three-dimensional coordinates of the measurement object P placed on the stage 10, and is based on the rough shape information. A surface to be measured division step is performed in which the surface to be measured S is composed of an inclined region D and a flat region K, and one area is divided into a plurality of measurement surfaces having a measurement field of view W or less (step 20).

Next, the objective lens selecting means 75 has a plurality of objectives depending on the measurement contribution irradiation amount that contributes to the measurement when the inclined region D and the flat region K are irradiated with light from the light source 40 for each of the divided measurement surfaces N. The objective lens selection step of selecting the objective lens 50 having the magnification to be used among the lenses 50 is performed (step 30).

In this objective lens selection step, as shown in FIG. 18, the objective lens map of the objective lens 50 selected by the objective lens selection method described above for each measurement surface N of the divided plurality of inclined regions D and the flat region K. It is preferable to display F on the display unit 20.

FIG. 18A shows the swell shape of the surface S to be measured in the x-axis direction and the z-axis direction. Actually, there is a swell in the y-axis direction, but it is omitted in the figure. In FIG. 18B, an example of the objective lens map F of the objective lens 50 selected for the plurality of inclined regions D and the flat region K in which the swell shape of FIG. 18A is divided is displayed on the display unit 20. It is the one displayed. Reference numeral 10 (C) indicates the sizes of the measurement fields W ₁ , W ₂ , and W ₃ of the low-magnification lens 50A, the medium-magnification lens 50B, and the high-magnification lens 50C.

As shown in FIG. 18B, it is preferable that the measurement range of each measurement surface N is displayed in a quadrangle and the objective lenses 50 having different magnifications are displayed in different colors on the objective lens map F. For example, the objective lens map F, show the measurement surface N _R to be measured at low magnification lens 50A in red shows the measurement surface N _G measuring at medium magnification lens 50B in green, the measurement surface N of measuring at a high magnification lens 50C _B can be shown in blue. The shaded area is the area where the measurement surfaces overlap.

As a result, the operator can visually confirm the magnification of the objective lens 50 used for each measurement surface N, and clearly indicate that the objective lens 50 has a measurement range having a different area depending on the magnification. Can be done.

Further, by displaying the objective lens map F on the display unit 20, the user can actually feel the state of the more optimal selection plan of the objective lens 50 as compared with the case where the objective lens map F is not displayed.

Next, the light amount adjusting means 76 uses the light source 40 according to the measurement contribution irradiation amount that contributes to the measurement when the inclined region D and the flat region K are irradiated with light from the light source 40 for each of the divided measurement surfaces N. A light amount adjusting step for adjusting the light amount is performed (step 40).

Next, the measuring surface shape measuring means 77 of the processing unit 18 moves the stage 10 in the in-plane direction of the surface S to be measured, so that each divided measurement surface N is based on the selected objective lens 50 and the adjusted light source light amount. The surface shape is individually measured and a measurement surface shape measurement step of acquiring a plurality of measurement data is performed (step 50).

Next, the data connection means 78 of the processing unit 18 performs a data connection step of connecting the acquired plurality of measurement data (step 60).

As a result, in the stitching measurement, it is possible to select the objective lens 50 having an appropriate magnification when measuring the surface shape of the surface S to be measured and to perform the measurement preparatory alignment for adjusting the appropriate amount of light of the light source 40. The surface shape measurement of the surface S can be made highly accurate.

In the present embodiment described above, the measurement field W of the objective lens 50 is smaller than the surface S to be measured, and the stitching measurement has been described, but the present invention is not limited to the stitching measurement. Even when the measurement field of view W of the objective lens 50 is equal to or greater than the surface S to be measured, by performing the approximate shape acquisition step (step 10) to the data connection step (step 60) as in the present invention, in particular. The surface shape of the wavy surface S to be measured can be measured with high accuracy.

Although the description has been made by moving the stage 10 horizontally with respect to the optical unit 2, the optical unit 2 may be moved horizontally with respect to the stage 10. Further, in the present embodiment, the case where the surface S to be measured has a wavy shape has been described, but the shape is not limited to this shape, and any shape may be used as long as the surface has a height difference of unevenness.

In the surface shape measuring device 1 of the present embodiment described above, the light source 40 that outputs the light for measuring the surface shape of the surface S to be measured of the object P to be measured, and the light output from the light source 40 are the surface S to be measured. As an optical unit 2 having at least an imaging unit 16 for acquiring a measurement image of the surface S to be measured and an objective lens 50 to irradiate the light source 50, the present invention has been described with an example of a vertical scanning white interferometer, but the present invention is a laser confocal microscope. It can also be applied to.

P ... Measurement target, Q, Q1, Q2, Q3 ... Interference fringe curve, S ... Measured surface, Z-0, Z-1 ... Optical axis, N ... Measurement surface, D ... Inclined region, K ... Flat shape Region, A ... irradiation light that can be used for measurement, B ... irradiation light that cannot be used for measurement, C ... reflected light that does not return to the objective lens 50, F ... objective lens division map, Z ... scanning range, 1 ... surface shape measurement Device, 2 ... Optical unit, 2A ... Housing, 2B ... Revolver, 10 ... Stage, 10S ... Stage surface, 12 ... Light source unit, 14 ... Interference unit, 16 ... Imaging unit, 18 ... Processing unit, 20 ... Display unit, 22 ... Input unit, 34 ... x actuator, 35 ... In-plane moving means, 36 ... y actuator, 40 ... Light source, 42 ... Collector lens, 44, 54 ... Beam splitter, 50 ... Objective lens, 50A ... Low magnification lens, 50B ... Medium magnification lens, 50C ... High magnification lens, 52 ... Reference mirror, 56 ... Interference part actuator, 60 ... Imaging element, 60S ... Imaging surface, 62 ... Imaging lens, 70 ... z actuator, 72 ... Approximate shape acquisition means , 74 ... Measured surface dividing means, 75 ... Objective lens selecting means, 76 ... Light amount adjusting means, 77 ... Measuring surface shape measuring means, 78 ... Data connecting means, 80 ... Stage moving means, 82 ... Measurement contribution irradiation light amount measuring means

Claims (12)

A support part that supports the object to be measured and
A light source that outputs light for measuring the surface shape of the surface to be measured of the object to be measured, a plurality of objective lenses having different magnifications that irradiate the surface to be measured with light output from the light source, and measurement of the surface to be measured. An optical unit that has at least an imaging unit that acquires an image,
An in-plane moving means for moving the support portion in the in-plane direction of the surface to be measured, and
A rough shape acquisition means for acquiring the rough shape information of the surface to be measured, and
A surface dividing means for measuring, which divides the surface to be measured into a plurality of measurement surfaces composed of an inclined region and a flat region based on the schematic shape information.
An objective lens that selects an objective lens having a magnification to be used from the plurality of objective lenses according to a measurement contribution irradiation amount that contributes to measurement when the divided region and the flat region are irradiated with the light. Selection method and
A light amount adjusting means for adjusting the light amount of the light source according to the measurement contribution irradiation amount that contributes to the measurement when the divided inclined region and the flat region are irradiated with the light.
By moving the support portion in the in-plane direction of the surface to be measured, the surface shape of each of the divided measurement surfaces is individually measured based on the selected objective lens and the adjusted amount of light, and a plurality of measurement data are obtained. With the measuring surface shape measuring means to acquire
A surface shape measuring device including a data connecting means for connecting a plurality of acquired measurement data. The surface shape measuring apparatus according to claim 1, wherein the measurement field of view of the objective lens is narrower than the surface to be measured of the object to be measured, and the surface shape of the surface to be measured is measured by stitching measurement. The invention according to claim 1 or 2, wherein the measurement contribution irradiation light amount detecting means for detecting the measurement contribution irradiation amount G of the irradiation light that returns to the objective lens and contributes to the measurement among the light irradiated to the surface to be measured through the objective lens is provided. Surface shape measuring device. The objective lens selecting means obtains an objective lens having a magnification to be used based on the ratio G / F of the measurement contribution irradiation amount G to the total irradiation light amount F of the irradiated light for the divided inclined region and the flat region. The surface shape measuring device according to any one of claims 1 to 3 to be selected. The light amount adjusting means uses the measurement contribution irradiation amount G when measuring the flat region as a reference light amount for the divided inclined region and the flat region, and the measurement when measuring the inclined region. The surface shape measuring device according to any one of claims 1 to 4, wherein the light amount of the light source is adjusted so that the contribution irradiation amount G becomes the reference light amount. The surface shape measuring apparatus according to any one of claims 1 to 5, wherein the surface shape of the surface to be measured of the measurement object is a wavy shape. The surface shape measuring device according to any one of claims 1 to 6, wherein the approximate shape acquiring means is any one of a triangulation type laser displacement meter, a stereo camera, and a pattern projection device. The surface shape measuring device according to any one of claims 1 to 6, wherein the approximate shape acquiring means is a holding means for holding CAD data of the measurement object. The surface shape measuring device according to any one of claims 1 to 6, wherein the rough shape acquiring means is a white interference meter using a low magnification lens having a magnification smaller than that of the objective lens of the optical unit. The surface shape measuring apparatus according to any one of claims 1 to 9, further comprising a display unit for displaying an objective lens map selected by the objective lens selecting means for a plurality of measurement surfaces divided by the surface dividing means to be measured. .. The surface shape measuring apparatus according to any one of claims 1 to 10, wherein the optical unit is a white interferometer or a laser confocal microscope. A support part that supports the object to be measured and
A light source that outputs light for measuring the surface shape of the surface to be measured of the object to be measured, a plurality of objective lenses having different magnifications for irradiating the surface to be measured with the light output from the light source, and the surface to be measured. A surface shape measuring method for measuring the surface shape of the surface to be measured by using an optical unit having at least an imaging unit for acquiring a measurement image and a surface shape measuring device having at least a photographing unit.
The outline shape acquisition step for acquiring the outline shape information of the surface to be measured, and
A surface division step of dividing the surface to be measured into a plurality of measurement surfaces composed of an inclined region and a flat region based on the schematic shape information.
An objective lens that selects an objective lens having a magnification to be used among the plurality of objective lenses according to a measurement contribution irradiation amount that contributes to measurement when the divided region and the flat region are irradiated with the light. Selection process and
A light amount adjusting step of adjusting the light amount of the light source according to the measurement contribution irradiation amount that contributes to the measurement when the divided inclined region and the flat region are irradiated with the light.
By moving the support portion in the in-plane direction of the surface to be measured, the surface shape of each of the divided measurement surfaces is individually measured based on the selected objective lens and the adjusted amount of light, and a plurality of measurement data are obtained. To acquire the measurement surface shape measurement process and
A surface shape measuring method comprising a data connecting step of connecting a plurality of acquired measurement data.

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