JP2013024734A - Shape measurement device and shape measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shape measurement device and shape measurement method capable of facilitating acquisition of fine rugged shape information on one line of a subject surface with a wide dynamic range in a height direction by one-shot imaging without performing a detection scan.SOLUTION: Illumination light from a planar light source 10 emitting spatially incoherent light with a broadband spectrum is radiated to a reference surface 14 and a subject surface 20 via objective lenses 13A, B. Acquired reference light and measurement light are allowed to interfere each other. The interference light is linearly reshaped by a slit 16A and branched by a spectrometer 16. The shape of the subject surface 20 is analyzed based on spectrum interference information acquired by two-dimensional imaging means 17. The light source 10, the subject surface 20, the slit 16A, and the light source 10, the reference surface 14, the slit 16A are respectively mutually conjugated. An offset is arranged between an optical path length of a pathway via the subject surface 20 and an optical path length of a route via the reference surface 14.

Description

  The present invention relates to a shape measuring device and a shape measuring method used for measuring a fine uneven surface shape.

  Conventionally, a confocal microscope is known as an optical device for measuring a fine surface shape. The confocal microscope has a characteristic that only a focused portion is brightly imaged, and has an advantage that high-resolution measurement can be performed. However, on the other hand, in order to obtain a cross-sectional shape (one-line shape profile) of the test surface, scanning is performed in two directions (two-dimensionally) in the height direction (Z direction) and the horizontal direction (X direction). It is necessary to improve the measurement efficiency. Therefore, a technique is known in which a chromatic aberration is imparted to an objective lens in a confocal microscope so that scanning in the height direction (Z direction) is unnecessary. In this technology, white light is emitted from the pinhole on the light transmission side, the reflected light from the test surface is guided to the pinhole on the light reception side by a confocal system, and the light that has passed through the pinhole on the light reception side is spectrally separated. Spectral signals are obtained by performing spectroscopy in the system. By applying chromatic aberration to the objective lens, light of any wavelength is collected on the surface of the test surface, and the light detection intensity of the collected wavelength is increased, so that the height direction (Z direction) The height information of the test surface can be detected without scanning. The dynamic range in the Z direction depends on the amount of chromatic aberration given.

  In general, in a low coherence interferometer, in order to search for the peak of the envelope (envelope of the light intensity signal), it is necessary to repeatedly acquire the interference signal while scanning the optical path length difference between the measurement light and the reference light. Since the measurement efficiency cannot be improved, for example, a low-coherence interferometer disclosed in Patent Document 1 below can reduce the width of the scanning range so as to improve the measurement efficiency. It has been.

JP 2010-122043 A

  However, even in the confocal microscope using the chromatic aberration of the objective lens described above, at least one-dimensional scanning in the lateral direction (X direction) is required to measure the cross-sectional shape (one-line shape profile) of the test surface. Therefore, there was a limit to the improvement of measurement efficiency.

  Further, even in the low coherence interferometer described in Patent Document 1, although the width of the scan range of the optical path length difference can be reduced, the scan itself cannot be eliminated, and the measurement efficiency is greatly improved. It was difficult.

  The present invention has been made in view of the above circumstances, can increase the dynamic range in the height direction, and can obtain uneven shape information on one line of the test surface by one-shot imaging without scanning for detection. It is an object to provide a shape measuring device and a shape measuring method that can be easily obtained.

One aspect of the shape measuring apparatus illustrating the present invention is as follows:
Illuminating light from a planar light source that emits spatially incoherent light having a broadband spectrum is divided into two paths by a light dividing means, and one is guided to the test surface and the other is guided to the reference surface. An interferometer that obtains spectral interference information generated by the reflected light of the illumination light from the test surface and the reference surface superimposed on each other by a light superimposing means and acquiring the spectral interference information, and the light splitting An objective lens arranged in each system path until the parallel light divided into two system paths by the means is superimposed by the light superimposing means,
The means for acquiring the spectral interference information includes: a spectroscope having a slit for linearly passing the interfered light; and a two-dimensional imaging means for acquiring spectral interference information by a spectral signal dispersed by the spectroscope. And a shape analyzing means for analyzing the shape of the test surface based on the spectral interference information acquired by the two-dimensional imaging means,
The light source, the test surface and the spectroscope slit are arranged at positions that are conjugated with each other, and the light source, the reference surface and the spectroscope slit are arranged at positions that are conjugated with each other,
An offset is provided within a range in which interference is possible between an optical path length from the light source to the slit through the test surface and an optical path length from the light source to the slit through the reference surface. It is characterized by this.

In addition, an aspect of the shape measuring method illustrating the present invention is as follows.
Illumination light emitted from a planar light source that emits spatially incoherent light having a broadband spectrum is divided into two paths by a light dividing means, and one is directed to the test surface and the other is directed to the reference surface. In addition, the reflected light of the illumination light from the test surface and the reference surface is superposed on each other by a light superimposing means to cause interference to obtain spectrum interference information, and the obtained spectrum interference information is analyzed to analyze the test subject. In the shape measuring method for measuring the surface shape of the surface,
The light source, the test surface, and the spectroscope slit are arranged in a conjugate position with each other, and the light source, the reference surface and the spectrometer slit are arranged in a conjugate position with each other,
An offset is provided within a range in which interference is possible between an optical path length from the light source to the slit through the test surface and an optical path length from the light source to the slit through the reference surface,
When acquiring the spectral interference information, the interference light is shaped into a line through the slit, the shaped interference light is spectrally separated by a spectroscope, and a spectral signal is imaged.
Thereafter, the shape of the test surface is analyzed based on the acquired spectral interference information.

  In addition, the above-described “planar light source” includes not only a light source whose light emission area extends two-dimensionally but also a light emission area that is originally formed in a slit shape (including one line) by a mask or the like. Shall also be included. Further, when the “planar light source” is formed in a slit shape (including one line), the longitudinal direction of the slit and the longitudinal direction of the slit of the spectroscope are arranged in directions corresponding to each other. .

  According to the shape measuring apparatus and the shape measuring method of the present invention, the dynamic range in the height direction can be increased, and the uneven shape information on one line of the test surface can be obtained by one-shot imaging without scanning for detection. Can be easily obtained.

It is a schematic block diagram of the shape measuring apparatus which concerns on Example 1 (including a modification) of this invention. It is a schematic block diagram of the shape measuring apparatus which concerns on Example 2 (a modified example is included) of this invention.

  Hereinafter, two embodiments of the shape measuring apparatus according to the present invention and modifications thereof will be described with reference to the drawings.

<Example 1>
As shown in FIG. 1, the shape measuring apparatus 1 according to the first embodiment is configured in an interferometer type having a cross shape with a beam splitter as a center, and analyzes spectral interference fringes having surface information to be detected. It measures the minute surface shape of the surface.

  That is, as shown in FIG. 1, the shape measuring apparatus 1 includes a surface light source 10 that emits white light, a collimator lens 11 that converts divergent light from the surface light source 10 into parallel light, and two parallel light beams. The beam splitter 12 that divides the light into two paths and superimposes the two lights once divided, the objective lens 13A and the objective lens 13B arranged in each of the two paths, and the focal position of the objective lens 13A. The object holding means 22 for holding the object 21 having the reference surface 14 and the object surface 20 arranged at the focal position of the objective lens 13B at a predetermined position, and the interference light superimposed by the beam splitter 12 are condensed. A condensing lens 15, a slit 16 </ b> A is disposed at the focal position of the condensing lens 15, a spectroscope 16 that forms an image of the slit 16 </ b> A, and an image of the slit 16 </ b> A is formed. Analyzing the surface shape of the test surface 20 by analyzing the interference information due to the spectral interference fringes obtained by the two-dimensional imaging device 17 that captures the spectral interference fringes by the interference light Means 18 and display means 23 for displaying the analyzed surface shape of the test surface 20 are provided. Furthermore, an illumination-side stop 19A disposed between the collimating lens 11 and the beam splitter 12 and a detection-side stop 19B disposed between the beam splitter 12 and the condenser lens 15 are provided.

  The surface light source 10 is a planar light source that emits spatially incoherent light having a broadband spectrum. For example, point light source elements are arranged in an array.

  Further, the surface light source 10, the test surface 20, and the slit 16 </ b> A of the spectroscope 16 are arranged at positions that are conjugated with each other, and the surface light source 10, the reference surface 14, and the slit 16 </ b> A of the spectroscope 16 are also conjugated with each other. Arranged.

  Further, as the surface light source 10, the light emission region is formed in a slit shape (the light emission region may be originally formed in a slit shape, or the light emission region is formed in a slit shape by shielding light with a mask or the like. In other words, unnecessary light such as noise can be prevented from being mixed. However, when the surface light source 10 is formed in a slit shape (including one line), the longitudinal direction of the slit and the longitudinal direction of the slit of the spectroscope are arranged so as to correspond to each other.

  Further, the optical path length from the surface light source 10 through the test surface 20 to the slit 16A and the optical path length from the surface light source 10 through the reference surface 14 to the slit 16A are within a range that allows interference (with a coherence length). Within the range).

  The spectroscope 16 includes a slit 16A, a diffraction grating (not shown) which is a spectroscopic means, and an imaging optical system (not shown), and a line of interference light passing through the slit 16A is used as a diffraction grating. And a spectral signal having a spread in the spatial resolution direction (slit longitudinal direction) and a spread in the wavelength resolution direction (slit width direction). To do.

  On the two-dimensional image sensor 17, an image of the slit 16A is formed by the spectroscope 16, and surface shape information (spectral signal obtained by the spectroscope 16) relating to the interference light that has passed through the slit 16A is obtained. Light is received as one-dimensional position information and wavelength information (height information).

  The analysis unit 18 performs an arithmetic process on the spectral signal output from the two-dimensional imaging device 17 to obtain a minute uneven surface shape of the test surface 20, stores this in a storage unit (not shown), and if necessary. The data is output to display means (display screen or printer) 23.

  Next, a shape measuring method according to an embodiment of the present invention will be described with reference to FIG.

  Light emitted from each point light source of the surface light source 10 is converted into parallel light by the collimator lens 11. The angle and azimuth of the collimated parallel light with respect to the optical axis are determined by the coordinates of the emission point on the surface light source 10.

  The collimated parallel light passes through the diaphragm 19A on the illumination side, and is divided into two by the beam splitter 12 into measurement light and reference light. Of the two divided lights, the reference light is collected on the reference surface 14 by the objective lens 13A, and the measurement light is condensed on the test surface 20 by the objective lens 13B.

  The surface light source 10 and the reference surface 14 are arranged at conjugate positions, and an image of the surface light source 10 is formed on the reference surface 14. The light reflected from the reference surface 14 (light from each point of the light source 10) is returned to parallel light by the objective lens 13A, passes through the beam splitter 12, and is collected on the slit 16A of the spectroscope 16 by the condenser lens 15. Is done. That is, the surface light source 10, the reference surface 14, and the slit 16 </ b> A of the spectroscope 16 are conjugated with each other.

  On the other hand, the surface light source 10 and the test surface 20 are arranged at conjugate positions, and an image of the surface light source 10 is formed on the test surface 20. Light reflected from the test surface 20 (light from each point of the surface light source 10) is returned to parallel light by the objective lens 13B, reflected by the beam splitter 12, and reflected by the condenser lens 15 on the slit 16A of the spectroscope 16. It is condensed to. That is, the surface light source 10, the test surface 20, and the slit 16A of the spectroscope 16 are in a conjugate relationship with each other.

  The interference light of the measurement light and the reference light that has entered the spectroscope 16 from the slit 16A is split by the diffraction grating disposed in the spectroscope 16, and is imaged on the two-dimensional image sensor 17 by the imaging optical system. The Thereby, spectral interference fringes corresponding to the surface shape information of the test surface 20 are formed on the two-dimensional image sensor 17.

  Information on the spectral interference fringes obtained by the two-dimensional imaging device 17 is sent to the analyzing means 18 and spectral intensity signals having different modulation frequencies and phases are obtained according to the optical path length difference between the measurement light and the reference light. Here, since a predetermined optical path length difference (offset) is given between the measurement light and the reference light, the spectral intensity signal becomes a sinusoidal intensity signal having a relatively high frequency. In this way, by obtaining the modulation frequency and the spectral intensity signal, the shape of the test surface 20 in the height direction (Z direction) can be obtained with high accuracy. Such a principle is known as a Fourier domain method in which interference light is spectrally resolved, detected by an image sensor, and the detected signal is Fourier transformed to obtain a light intensity profile in the height direction of the test surface. This intensity signal is obtained as a product of the light source spectrum shape.

  Since the optical path length difference differs in accordance with the height in the Z direction (deviation amount from the reference position) at each position of the surface shape of the test surface 20, the spectral intensity signal is also reflected from each position on the test surface 20. A sinusoidal frequency is different for each light. If this spectral intensity signal is Fourier-analyzed with the wave number of light, the phase of the complex amplitude for each wave number of light can be obtained, so that the optical path length difference between the corresponding measurement light and reference light can be obtained. Specifically, the spectral intensity signal obtained by the two-dimensional image sensor 17 is Fourier-transformed by the wave number of light, the signal component is extracted by a band pass filter, and inverse Fourier transform is obtained at that time. Information on the height direction of the test surface 15 can be obtained from the optical path length difference, and the surface shape of the test surface 20 can be obtained.

  By the way, when the uneven surface is present on the test surface 20, the light spot of the reference light is formed with a sufficiently small diameter on the slit 16A of the spectroscope 16, whereas the light of the measurement light The spot diameter spreads according to the size of the unevenness.

  However, since the interference light component of the reference light and the measurement light is extracted using the surface light source 10 that emits spatially incoherent light, the measurement light is adjacent to the measurement light even if there is a spot spread. Crosstalk with reference light from a point light source does not occur, and accurate signal analysis is possible.

  Since spectral interference fringes are detected by spectroscopy with the spectroscope 16, information necessary for cross-sectional measurement (one-line shape profile measurement) can be obtained by one imaging (single shot), and disturbances such as vibrations can be obtained. Measurement is possible.

<Modification>
By the way, when the unevenness of the surface of the test surface 20 is further increased, the light passing through the slit 16A of the spectroscope 16 is weakened, S / N deterioration occurs, and furthermore, detection itself becomes difficult.

  Therefore, in the modified example of the embodiment apparatus of FIG. 1, a predetermined chromatic aberration is given to the objective lens 13 </ b> B disposed between the beam splitter 12 and the test surface 20.

  That is, the reference light is the same as that of the basic apparatus of the first embodiment described above, but the measurement light is measured on the surface 20 to be measured according to the wavelength due to the effect of chromatic aberration applied to the objective lens 13B. The heights of the condensing points are different. Therefore, the wavelength of the light condensed on the slit 16A of the spectroscope 16 differs depending on the height of each position on the test surface 20. A spectral intensity signal (spectral interference fringe) that is spectrally separated by the spectroscope 16 and picked up by the two-dimensional image sensor 17 has an envelope peak corresponding to the height of each position on the test surface 20 and is also referred to as measurement light. It has modulation frequency and phase information corresponding to the optical path length difference of light.

  Therefore, by performing Fourier analysis on the spectral intensity signal based on the wave number of light, the envelope and phase information relating to the interference component can be obtained.

  From this phase information, the optical path length difference can be obtained as described below. However, if the chromatic aberration of the objective lens 13B is known (separately obtained by calibration or the like), it can be obtained by using the interference light. Based on the obtained peak position information of the envelope, the height of the test surface 20 can be obtained efficiently while maintaining high resolution. And each point of the surface light source 10 and the to-be-tested surface 20 will be in a confocal state by the light of one wavelength among the lights inject | emitted from the surface light source 10, and the spectral intensity signal in such a confocal state is utilized. Then, since the surface shape of the test surface 20 is analyzed, measurement with high lateral resolution without blur in the lateral direction is possible.

  When calculating the optical path length difference based on the phase information, if the optical path length difference is expressed by (n + σ / 2π) λ (where n is an integer, λ is a wavelength, and σ is a phase), n is indefinite. This n needs to be determined. Since the phase σ is obtained for a plurality of wavelengths λ, n is determined so as not to contradict the plurality of wavelengths.

  In addition, the optical path length difference is determined to have a consistent value in the vicinity of the optical path length difference obtained from the peak position of the frequency spectrum of the obtained sine wave signal or the wavelength of the envelope peak position described above. .

  In addition, if there is unevenness on the surface 20 to be measured, a lot of measurement light having a wavelength that does not become a confocal state also exists, but these spread on the slit 16A of the spectroscope 16.

  In this modified example, the spot diameter of the reference light is not changed as in the case of the basic form, and a sufficiently small spot is formed. However, the surface light source 10 that emits spatially incoherent light is used as a reference. Since the interference component of the light and the measurement light is extracted, crosstalk with the reference light from the adjacent point light source due to the spot spread of the measurement light does not occur, and highly accurate signal analysis is possible.

  Thereafter, the surface shape of the test surface 20 analyzed by the analyzing unit 18 is displayed on the display unit 23.

  Further, the surface light source 10 is configured by arranging a plurality of incoherent point light sources, and a mask array corresponding to the point light source array on the slit 16A of the spectroscope 16 (corresponding to the point light source of the slit 16A). A mask pattern that shields light other than the portion may be provided. Thereby, since mixing of unnecessary light can be prevented, S / N can be increased.

  In addition, a light source having a broad spectrum width, such as SLD (Super Luminescent Diode), and a spatially coherent light source combined with an element having a coherence eliminating function, such as a rotating diffuser (decoherer) A surface light source unit that emits coherent light may be configured.

  Moreover, it is desirable that the objective lens 13B disposed between the beam splitter 12 and the test surface 20 has telecentricity. This is because the height information with respect to the correct abscissa can be detected regardless of the uneven height on the test surface 20.

When the inclination of the surface shape of the test surface 20 is large, it is desirable to set the NA on the detection side of the objective lenses 13A and 13B to be smaller than the NA on the illumination side of the objective lenses 13A and 13B. Specifically, the diaphragm 19B is set smaller than the diaphragm 19A.
By setting in this way, the gradient of the phase distribution of the measurement light spot on the slit 16A of the spectroscope 16 can be reduced, the spatial frequency of the local interference fringe with the reference light spot can be reduced, and pixel averaging can be performed. The influence can be reduced.

  Here, the apparatus according to Example 1 was compared with the system in which a plurality of pinholes on the light transmission side and the light reception side were arranged in the confocal microscope in which chromatic aberration was imparted to the objective lens, which was shown as the prior art. In this case, in the system according to the prior art, when the light spot of the measurement light is deviated from the confocal state, the light is mixed into the adjacent pinhole on the light receiving side, and the adjacent pinhole An error occurs in the measurement result. On the other hand, in the first embodiment, by using incoherent light, it is possible to separate and extract each piece of interference information from each position on the surface 20 to be detected, so that it is mixed from adjacent positions. High-accuracy measurement is possible without being affected by the measurement light (mixed light does not interfere with the reference light, and only the DC component increases, so it can be removed by subsequent signal analysis). Furthermore, since the phase information (envelope peak position information, etc.) of the interference signal can be used in the invention of the first embodiment, the measurement in the height direction (Z direction) can also maintain high resolution.

<Example 2>
Hereinafter, the shape measuring apparatus 101 according to the second embodiment will be described with reference to FIG.

  Since the shape measuring apparatus 101 according to the second embodiment has the same functions and features as those of the shape measuring apparatus 1 according to the first embodiment described above, description of members having duplicate functions is omitted. The number which added 100 to the number attached | subjected to the corresponding member in Example 1 is given as a code | symbol. The main difference from the apparatus of the first embodiment described above will be described below.

  In the shape measuring apparatus 1 according to the first embodiment, the light splitting unit that splits the light from the surface light source 10 and the light superimposing unit that superimposes the reference light and the measuring light are configured by one beam splitter 12. In the shape measuring apparatus 101 according to the second embodiment, the light splitting unit is configured by the half mirror 112A, and the light superimposing unit is configured by the half mirror 112B independently of each other, and is split by the half mirror 112A. A half mirror 112C for bending the optical path of the reference light in the direction of the reference surface 114, and a half mirror 112D for bending the optical path of the measurement light divided by the half mirror 112A in the direction of the test surface 120 are provided.

  In the shape measuring apparatus 1 of the first embodiment, the illumination-side diaphragm 19A and the detection-side diaphragm 19B are each provided one by one. However, in the shape measuring apparatus 101 of the second embodiment, after the division, In the optical path of the reference light, one illumination-side stop 119Aa and one detection-side stop 119Ba are provided, and in the divided measurement light optical path, the illumination-side stop 119Ab and the detection-side stop 119Bb are respectively provided. It differs in that it is provided one by one. In this way, in the optical path of the divided reference light and measurement light, each of the illumination side diaphragm and the detection side diaphragm is provided, and the NA can be adjusted independently, so that the lateral resolution and the measurable test can be measured. The system can be optimized using the amount of surface inclination and the amount of crosstalk as indices.

  As a modification of the second embodiment, a lens in which a predetermined chromatic aberration is given to the objective lens 113B disposed between the half mirror 112D and the test surface 120 can be cited. The modified example of the second embodiment can obtain the same effects as the modified example of the first embodiment.

  As mentioned above, although the Example of this invention was described, as a shape measuring apparatus and a shape measuring method of this invention, it is not restricted to these, Other various modifications can be employ | adopted. For example, various aspects of the optical arrangement of the apparatus can be changed, and the arrangement of the lenses and the diaphragm can be changed as appropriate. For example, in the shape measuring apparatus 1 according to the first embodiment shown in FIG. Instead, a diaphragm may be provided between the beam splitter 12 and the objective lens 13A, and between the beam splitter 12 and the objective lens 13B.

  When it is desired to perform shape measurement over the entire surface to be measured, it is efficient to perform shape measurement according to the present invention while scanning the surface to be measured in a direction corresponding to the width direction of the slit of the spectrometer. Is.

DESCRIPTION OF SYMBOLS 1,101 Shape measuring apparatus 10,110 Surface light source (light source part)
DESCRIPTION OF SYMBOLS 11, 111 Collimating lens 12 Beam splitter 13A, 13B, 113A, 113B Objective lens 14, 114 Reference surface 15, 115 Condensing lens 16, 116 Spectrometer 16A, 116A Slit 17, 117 Two-dimensional image sensor 18, 118 Analysis means 19A , 19B, 119Aa, 119Ab, 119Ba, 119Bb Aperture 20, 120 Test surface 21, 121 Subject 22, 122 Subject holding means 23, 123 Display means 112A, 112B, 112C, 112D Half mirror

Claims (10)

Illuminating light from a planar light source that emits spatially incoherent light having a broadband spectrum is divided into two paths by a light dividing means, and one is guided to the test surface and the other is guided to the reference surface. An interferometer that obtains spectral interference information generated by the reflected light of the illumination light from the test surface and the reference surface superimposed on each other by a light superimposing means and acquiring the spectral interference information, and the light splitting An objective lens arranged in each system path until the parallel light divided into two system paths by the means is superimposed by the light superimposing means,
The means for acquiring the spectral interference information includes: a spectroscope having a slit for linearly passing the interfered light; and a two-dimensional imaging means for acquiring spectral interference information by a spectral signal dispersed by the spectroscope. And a shape analyzing means for analyzing the shape of the test surface based on the spectral interference information acquired by the two-dimensional imaging means,
The light source, the test surface and the spectroscope slit are arranged at positions that are conjugated with each other, and the light source, the reference surface and the spectroscope slit are arranged at positions that are conjugated with each other,
An offset is provided within a range in which interference is possible between an optical path length from the light source to the slit through the test surface and an optical path length from the light source to the slit through the reference surface. A shape measuring apparatus characterized by that.   2. The shape measuring apparatus according to claim 1, wherein a predetermined chromatic aberration is imparted to an objective lens arranged in a system path through the test surface among the parallel lights divided by the light dividing means. .   3. The shape measuring apparatus according to claim 1, wherein the shape of the test surface is obtained based on phase information obtained by analyzing the spectral interference information by the shape analyzing means.   4. The shape according to claim 1, wherein the shape of the test surface is obtained based on modulation frequency information obtained by analyzing the spectral interference information by the shape analysis means. measuring device.   5. The shape of the test surface is determined based on intensity information of an envelope obtained by analyzing the spectral interference information by the shape analysis unit. 6. Shape measuring device. The light source comprises a point light source array each emitting spatially incoherent light;
The shape measuring apparatus according to claim 1, wherein a mask array having an arrangement corresponding to the array arrangement of the point light source array is provided on the slit of the spectroscope.   The said light source is comprised by the spatially coherent light source and the decoherer which converts the light inject | emitted from this light source into incoherent light, The any one of Claim 1 to 6 characterized by the above-mentioned. Shape measuring device.   8. The objective lens arranged in the system path through the test surface among the parallel lights divided by the light dividing means is configured to have telecentricity. The shape measuring apparatus of any one of them.   Of the parallel light split by the light splitting means, the NA on the detection side of the objective lens arranged in the system path through the test surface is set to be smaller than the NA on the irradiation side of the objective lens The shape measuring device according to claim 1, wherein the shape measuring device is a device. Illumination light emitted from a planar light source that emits spatially incoherent light having a broadband spectrum is divided into two paths by a light dividing means, and one is directed to the test surface and the other is directed to the reference surface. In addition, the reflected light of the illumination light from the test surface and the reference surface is superposed on each other by a light superimposing means to cause interference to obtain spectrum interference information, and the obtained spectrum interference information is analyzed to analyze the test subject. In the shape measuring method for measuring the surface shape of the surface,
The light source, the test surface, and the spectroscope slit are arranged in a conjugate position with each other, and the light source, the reference surface and the spectrometer slit are arranged in a conjugate position with each other,
An offset is provided within a range in which interference is possible between an optical path length from the light source to the slit through the test surface and an optical path length from the light source to the slit through the reference surface,
When acquiring the spectral interference information, the interference light is shaped into a line through the slit, the shaped interference light is spectrally separated by a spectroscope, and a spectral signal is imaged.
Thereafter, the shape measurement method is characterized in that the shape of the test surface is analyzed based on the acquired spectral interference information.

Images