JP2013068489A - Surface profiling method using multiple wavelengths and apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To overcome the wavelength constraint on height differences between adjacent pixels in a phase shift method using an optical interference method, which irradiates a target object surface with monochromatic light of a single wavelength, acquires at least three images at different distances to the target object surface, performs phase computation from a brightness value of each pixel, and profiles a three-dimensional shape using the phase values of adjacent pixels.SOLUTION: A surface profiling method comprises steps of; extracting a plurality of monochromatic light of different wavelengths from irradiation light having broadband wavelength characteristics; mixing the monochromatic light together; simultaneously irradiating a target object surface and a reference surface with the mixed monochromatic light via splitting means; acquiring a plurality of images of interference fringes, generated by the reflection from the target object surface and the reference surface returning on a same optical path, while varying the difference between the reflection path length from the target object surface and from the reference surface; decomposing the acquired plurality of images per monochromatic light; determining a plurality of surface height candidate groups from phase of each pixel obtained for each monochromatic light; and determining a height common to each group as a real height.

Description

The present invention relates to a surface shape measuring method and apparatus for simultaneously irradiating a plurality of wavelengths and picking up an image with one color camera in a phase shift method using an optical interference method.

  Conventionally, using a light interferometry, monochromatic light of one wavelength is irradiated onto a measurement target surface, the distance to the measurement target surface is changed, and at least three images are captured, and the luminance value of each pixel is calculated. A phase shift method has been used in which phase calculation is performed and a three-dimensional shape is measured using the phase value of adjacent pixels. However, in this measurement method, the step between adjacent pixels is limited by the wavelength.

  In addition, a method of sequentially switching the wavelength of the monochromatic light with respect to the monochromatic light of the one wavelength to acquire a luminance signal of each wavelength and using the equivalent wavelength when calculating the height has been used.

  Furthermore, monochromatic light of three wavelengths of laser light is simultaneously irradiated, imaged with a color camera, decomposed into images of each wavelength of R wavelength, B wavelength and G wavelength, and phase calculation is performed from the luminance value of each wavelength, A surface shape measuring method using a coincidence method for height calculation or an apparatus using the surface shape measuring method have been developed. See [Non-Patent Document 1] and the like.

JP 2004-053307 A JP 2008-209404 A

A. Pfortner and J.M. Schwider: Red-green-blue interferometer for the metrology of discontinuos structures, Appl. Opt. 42,667-673 (2003)

  In the phase shift method using the optical interference method with monochromatic light of one wavelength described in the background art, because of the phase connection with the adjacent pixel, the height difference with the adjacent pixel is ¼ of the wavelength of the irradiation light. There was a problem that it was limited to the following.

  In addition, in other conventional surface shape measurement methods or apparatuses using the same, for example, measurement methods that sequentially switch a plurality of monochromatic light sources, the measurement time becomes redundant and the measurement time becomes redundant. In addition, there is a possibility that the measurement accuracy is deteriorated due to the environmental change of the measurement object while the measurement time of a plurality of measurements is passed.

  Furthermore, in the method of simultaneously irradiating laser beams with a plurality of wavelengths, there is a problem that speckle noise occurs due to the characteristics of the laser beams and a clear image cannot be obtained.

The first invention of the present application irradiates the measurement target surface and the reference surface with a plurality of monochromatic lights having different wavelengths through the branching means, and reflects the reflected light from both the measurement target surface and the reference surface and returns on the same optical path. In the surface shape measurement method by the multiple wavelength phase shift method for detecting the intensity value of the generated interference fringes by changing the difference in the reflected optical path length from the measurement target surface and the reference surface,
A first step of extracting a plurality of monochromatic lights having different wavelengths from irradiation light having broadband wavelength characteristics, mixing them together, and simultaneously irradiating the measurement target surface and the reference surface via a branching unit;
The interference fringe image generated by the reflected light reflected from the measurement target surface and the reference surface and returning from the same optical path can be changed with a single color camera by changing the difference in the reflected light path length between the measurement target surface and the reference surface. A second process of acquiring multiple sheets,
A third step of decomposing the acquired plurality of images for each monochromatic light;
A fourth step of removing a mixed signal from other monochromatic light contained in each monochromatic light from a plurality of images of each monochromatic light separated by the spectral characteristics of the optical system device;
For each monochromatic light, a fifth process for obtaining the phase of each pixel using an expression for obtaining an interference fringe waveform from the interference fringe intensity values of the pixels at the same position in the plurality of images,
A sixth step of obtaining a plurality of surface height candidate groups from the phase of each pixel obtained for each monochromatic light, and obtaining a common height as an actual height from each candidate group;
It is provided with.

  As described above, in the present invention, when measuring using a known phase shift method as a surface shape measurement method using optical interferometry, a plurality of white light sources not found in other reports are used. A method capable of simultaneously irradiating monochromatic light, taking an image with a color camera, decomposing it into a plurality of images for each monochromatic light, and further processing the correction of the crosstalk phenomenon with the own software, and the method An apparatus capable of measuring a surface shape using a slab is provided.

  By using a white light source, it is possible to avoid the influence of speckle noise that occurs as a specific defect when laser light in other known documents is used. In addition, when irradiating a plurality of monochromatic lights at the same time, an optimum wavelength can be freely set by using a white light source and a multi-band pass filter or an acousto-optic filter. Irradiation light can be irradiated.

  As described above, in order to capture an image with one color camera, when the image is decomposed into each wavelength, for example, each wavelength such as R wavelength, G wavelength, or B wavelength, a crosstalk phenomenon occurs between the images. Therefore, crosstalk correction is performed to ensure the accuracy of the captured image.

  By the way, in the generally known one-wavelength phase shift method, the Z-direction scanning pitch at the time of image capturing generally uses ¼ of the irradiation wavelength in order to facilitate phase calculation. In the present invention, irradiation light having a plurality of wavelengths is used, so that the wavelength is not necessarily ¼. For this purpose, the phase calculation for each of a plurality of monochromatic lights is performed by obtaining an approximate sine wave by the least square method from the luminance value sequence obtained for each pitch in the Z-direction scan, and calculating a plurality of wavelengths obtained by the phase of the approximate sine wave. The least square fitting technique described in [Patent Document 2] can be applied.

  Further, in the phase shift method, the height calculation using a plurality of wavelengths can be performed by expanding the height range of the measurement range by performing the height calculation using an equivalent wavelength generally obtained by the least common multiple of each wavelength. In the present invention, the height calculation of an arbitrary pixel is obtained from the height candidate group of each wavelength using a matching method. See [Patent Document 2].

According to a second aspect of the present invention, in the surface shape measurement method using a plurality of wavelengths according to the first aspect, the phase of each monochromatic light corresponding to a predetermined pixel on the measurement target surface is expressed by an expression for an interference fringe waveform. An expression,

g = a + bcos {2πfx + φ}

It is characterized in that it is obtained by fitting to the least squares.
Here, g is an intensity value of the same pixel of a plurality of pixels in the previous period, a is a DC component included in the interference fringe waveform, b is an amplitude of an AC component included in the interference fringe waveform, f is a frequency of monochromatic light to be irradiated, x represents the coordinate in the x direction, and φ represents the phase of each monochromatic light corresponding to a predetermined pixel on the measurement target surface to be obtained.

  Further, according to a third invention of the present application, the irradiating means used in any one of the first invention to the second invention uses a multiband pass filter or an acoustooptic filter from irradiating light having a broadband wavelength characteristic. A plurality of monochromatic lights having different wavelengths are used to irradiate and irradiate them at the same time.

  As a first effect of the present invention, when measuring using a known phase shift method as a surface shape measurement method using an optical interferometry, a plurality of white light sources that have not been reported in other reports are used. A method capable of simultaneously irradiating monochromatic light, taking an image with a color camera, decomposing it into a plurality of images for each monochromatic light, and processing correction of crosstalk phenomenon with owned software, Surface shape measurement can be performed using the method. Moreover, the height measurement range can be expanded by imaging with a plurality of wavelengths.

  The height calculation of each pixel is different from the phase connection with adjacent pixels performed by the one-wavelength phase shift method, and the height is calculated by the matching method from the height candidates based on the phase for each wavelength (RGB, etc.). Due to the calculation, there is no restriction due to the wavelength of the step between adjacent pixels.

  The second effect is that the measurement time can be increased. That is, by irradiating a plurality of wavelengths at the same time and simultaneously capturing images, a result can be obtained by a single measurement. Further, it is not necessary to switch the band pass filter.

  As a third effect, an optimum wavelength can be freely set by using a multiband pass filter or an acoustooptic filter, unlike the case of using laser light.

The figure which shows schematic structure of the surface shape measuring apparatus which concerns on a present Example. The flowchart which shows the process in a surface shape measuring apparatus. The figure which shows the luminance value of B, G, and R of the same pixel of seven acquisition images. The figure which shows the phase calculation result of B, G, and R of each pixel of a X direction. The figure which shows the height calculation result of each pixel of a X direction. The figure which shows the height calculation result (surface shape of a 1 micron level | step difference) of each pixel of XY direction. The figure which shows the measurement result which drawn the measurement result of FIG. 6 in three dimensions.

  Embodiments of the present invention will be described below with reference to the drawings.

  In addition, as a present Example, the surface as described in the prior art document [patent document 2] cited in this-application specification including the example which measured the surface height and surface shape of the measuring object using the interference fringe. The shape measuring device will be described as an example.

FIG. 1 is a diagram showing a schematic configuration of a surface shape measuring apparatus according to an embodiment of the present invention. This surface shape measuring apparatus irradiates a plurality of monochromatic lights in a specific wavelength band onto a measuring object 30 having a fine uneven step on the surface of a semiconductor wafer, liquid crystal panel, plasma display panel, magnetic film, glass substrate or metal film. An optical system unit 1, a control system unit 2 for controlling the optical system unit 1, and a holding table 40 for mounting and holding the measurement object 30.

The optical system unit 1 measures the illumination device 10 that outputs a plurality of monochromatic lights having different wavelengths toward the measurement target surface 30A and the reference surface 15, the collimator lens 11 that converts the monochromatic lights into parallel light, and the monochromatic lights. The half mirror 13 that reflects light from the direction of the measurement object 30 while reflecting in the direction of the object 30, the interference objective lens 14 that collects each monochromatic light reflected by the half mirror 13, and the interference objective lens The monochromatic light that has passed through 14 is divided into reference light that reflects to the reference surface 15 and measurement light that passes to the measurement target surface 30A, and the reference light reflected by the reference surface 15 and the measurement light reflected by the measurement target surface 30A. The beam splitter 17 that combines the light again to generate interference fringes, the imaging lens 18 that forms each monochromatic light in which the reference light and the measurement light are combined, and the interference fringes are measured. And an imaging device 19 that captures an image plane 30A.

The illuminating device 10 includes a light source 10A that irradiates irradiation light having a broadband wavelength and a multiband pass filter or an acoustooptic filter 10B. As the light source 10A of the present embodiment, for example, a white light source composed of a halogen lamp is used. By passing through the multi-band pass filter or acousto-optic filter 10B, a plurality of monochromatic lights having different wavelengths are selectively extracted in a state where a plurality of monochromatic lights having different wavelengths are mixed at the same time. As for the wavelengths of a plurality of monochromatic lights having different arbitrary wavelengths, for example, the first wavelength is the wavelength λ ₁ = 470 nm, the second wavelength is the wavelength λ ₂ = 560 nm, and the third wavelength is the wavelength λ ₃ = 600 nm. The illumination device 10 corresponds to the irradiation means of the present invention.

The half mirror 13 reflects parallel light composed of a plurality of monochromatic lights having different wavelengths from the collimating lens 11 toward the measurement object 30, while allowing reflected light returned from the measurement object 30 to pass therethrough.

  The interference objective lens 14 is a lens that focuses on the measurement target surface 30A that focuses a plurality of monochromatic light beams having different wavelengths.

The beam splitter 17 separates a plurality of monochromatic lights with different wavelengths collected by the interference objective lens 14 into reference light that is reflected by the reference surface 15 and measurement light that is reflected by the measurement target surface 30A. Further, the reference light and the measurement light that are reflected on each surface and return on the same optical path are combined again, thereby generating interference for each wavelength of the plurality of monochromatic lights having different wavelengths. The beam splitter 17 is
This corresponds to the branching means of the present invention.

The reference surface 15 has a mirror-finished surface, and the reference light composed of a plurality of monochromatic lights having different wavelengths reflected by the reference surface 15 reaches the beam splitter 17 and is reflected by the beam splitter 17. It has become.

Further, the measurement light composed of a plurality of monochromatic lights having different wavelengths that have passed through the beam splitter 17 is:
The light is condensed toward the focal point and reflected by the measurement target surface 30A. The reflected measurement light reaches the beam splitter 17 and passes through the beam splitter 17.

The reference beam and the measurement beam are combined again by the beam splitter 17. In this case, the distance L ₁ between the reference surface 15 and the beam splitter 17, the optical path difference by the difference in distance between the distance L ₂ between the object surface 30A and the beam splitter 17 is caused. Depending on the optical path difference, the reference light and the measurement light interfere with each other for a plurality of monochromatic lights having different wavelengths.

The imaging device 19 captures an image of the measurement target surface 30A that is projected by measurement light including a plurality of monochromatic lights having different wavelengths. The captured image data is collected by the memory 21 of the control system unit 2. Further, the imaging device 19 captures images of the measurement target surface 30 </ b> A and the convex portion (concave portion) 30 </ b> B of the measurement target surface at a predetermined sampling timing, and the image data is collected by the control system unit 2. The imaging device 19 corresponds to the imaging means of the present invention, and the control system unit 2 functions as the sampling means of the present invention.

  The imaging device 19 in the present embodiment may be configured to detect a plurality of monochromatic lights having different wavelengths. For example, a CCD solid-state imaging device, a CMOS image sensor, or the like is used.

The control system unit 2 performs overall control of the entire surface shape measuring apparatus and CPU 20 for performing predetermined arithmetic processing, and various data and programs such as image data and arithmetic results sequentially collected by the CPU 20. A memory 21 to be stored, an input unit 22 such as a mouse or a keyboard for inputting other setting information such as a sampling timing and an imaging area, and a monitor 23 for displaying an image of the measurement target surface 30A and the like. Further, the optical system unit 1 is driven to move in the Z direction in accordance with an instruction from the CPU 20. For example, the computer system includes a drive unit 24 including a drive mechanism such as a piezo actuator (not shown). Yes. The CPU 20 corresponds to the calculation means in the present invention, and the memory 21 functions as the storage means in the present invention.

The CPU 20 is a so-called central processing unit, and controls the imaging device 19, the memory 21, and the driving unit 24, and includes a measurement target surface 30 </ b> A including interference fringes for a plurality of monochromatic lights having different wavelengths captured by the imaging device 19. In addition, the CPU 20 is connected to a monitor 23 and an input unit 22 such as a keyboard or a mouse, so that the operator can monitor the surface shape of the measurement object 30 based on the image data. Various setting information is input from the input unit 22 while referring to the operation screen displayed on the screen 23. Further, the monitor 23 displays a surface image of the measurement target surface 30A, a concavo-convex shape, and the like as numerical values and images.

The drive unit 24 changes the distance difference between the fixed distance L ₁ between the reference surface 15 and the beam splitter 17 and the variable distance L ₂ between the beam splitter 17 and the measurement target surface 30A. 1 is a device that changes the optical unit 1 in the Z-axis direction, and includes a drive mechanism including, for example, a piezo actuator that drives the optical system unit 1 in the z-axis direction illustrated in FIG. In this embodiment, the optical system unit 1 is operated. Alternatively, the holding table 40 on which the measurement object 30 is placed may be driven in the Z direction.

  Hereinafter, processing performed by the entire surface shape measuring apparatus, which is a characteristic part of the present embodiment, will be described with reference to the flowchart shown in FIG.

<Step S <b>1> Acquisition of Measurement Data The optical system unit 1 simultaneously outputs monochromatic light having different wavelengths from the illumination device 10 and irradiates the measurement object 30 and the reference surface 15. This process corresponds to the first process of the present invention.

  The CPU 20 measures the measurement target including interference fringes imaged by the color camera of the imaging device 19 every time the optical unit 1 moves in the Z direction by a sampling interval of 1/8 of the wavelength λ of arbitrary monochromatic light to be irradiated, for example. The image data of the plane object 30 is collected and stored in the memory 21 sequentially. This process corresponds to the second process of the present invention.

<Step S2> Image Decomposition for Each Monochromatic Light In step S1, the CPU 20 operates at least three or more pieces of image data picked up by operating the image pickup device 19, and images of R wavelength, G wavelength, and B wavelength, respectively. Divide into This is all handled inside the computer. For example, FIG. 3 shows data of luminance values of a certain pixel when seven pieces of image data are divided into R wavelength G wavelength and B wavelength images. This process corresponds to the third process of the present invention.

<Step S3> Crosstalk Correction Between Monochromatic Colors of Decomposed Image Since the luminance signal of the image obtained above has additivity by irradiation with each light source, in this step, crosstalk by monochromatic light illumination of three wavelengths is performed. Correct talk. As a method, the true luminances R, G, B are obtained and corrected from the observed luminances B ′, G ′, R ′ of each pixel. At this time, the coefficient necessary for correction is obtained in advance by experiments.

In other words, as long as the observed luminance value is proportional to the input light quantity, the observed luminance value under the influence of the crosstalk phenomenon can be represented by a linear model of the following equation (1) as a crosstalk model.

B ′ = B + αG + βR
G ′ = γB + G + δR (1)
R ′ = εB + ξG + R

Here, B ′, G ′, and R ′ are observed luminance values, B, G, and R are true luminance values, and α, β, γ, δ, ε, and ζ are coefficients representing the strength of the crosstalk phenomenon, that is, Crosstalk correction coefficient. Here, although the method for calculating the crosstalk correction coefficient is omitted, if the crosstalk correction coefficient is calculated, the true value can be obtained from the observed luminance value by using Equation (1). In this case, simultaneous linear equations are obtained. However, since most of the crosstalk correction coefficients are usually as small as several%, the product term of the crosstalk correction coefficients is ignored and the following simple expression (2) Thus, the true luminance value can be calculated.

B = B′−αG′−βR ′
G = −γB ′ + G′−δR ′ (2)
R = −εB′−ξG ′ + R ′

The process of obtaining the true luminance value corresponds to the fourth process of the present invention.

ここで、aは干渉縞波形に含まれる直流成分、bは干渉縞波形に含まれる交流成分の振幅（以下、交流振幅という）、Δは光学ユニット１のＺ方向の移動間隔、λは各単色光の波長である。 <Step S4> Phase calculation of each pixel Next, an approximate sine wave is obtained by the least square method from the luminance values of a plurality of image data for each wavelength of B, G, and R, and each pixel is obtained from the sine wave. Find the phase of. The phase at the pixel selected by the CPU 20 is obtained using a calculation algorithm determined in advance using the light intensity values of the interference fringes of the plurality of pixels at the same position that have been imaged. Specifically, in a plurality of picked-up images for each wavelength, an expression obtained by modifying the following expression (3), which is an expression for obtaining an interference fringe waveform from the light intensity values of a plurality of interference fringes of a selected pixel ( 4) Apply (fitting) to obtain the phase.

g = a + bcos {2πfx + φ} (3)

First, the phase φ in a pixel for which a certain wavelength is to be calculated is expressed by the following equation (4) in the light intensity value g _i (i is 1,..., N) of interference fringes at n points (n is at least 3 or more). ) To fit the least squares model function.

Here, a is the DC component included in the interference fringe waveform, b is the amplitude of the AC component included in the interference fringe waveform (hereinafter referred to as AC amplitude), Δ is the movement interval in the Z direction of the optical unit 1, and λ is each single color. It is the wavelength of light.

By assuming the following equation (5), equation (4) can be rewritten as the following equation (6).

When the unknown parameters a, b, and φ are estimated by the least square method, they can be expressed by the following equation (7). However, φ is non-linear.

Therefore, assuming the following formulas (8) to (9), the formula (6) can be transformed into the following formula (10) and represented by the following formula (11). Thereby, the equation (7) can be expressed by the following equation (12), and can be a linear least square problem with respect to a, ξ _c, and ξ _s .

ζc = bcosφ. . . (8)

ζs = −bsinφ (9)

Therefore, the ternary simultaneous equations of a and ξc and xi] _s, represented by a matrix of the following equation (13).

例えば、Ｒ波長Ｇ波長およびＢ波長のそれぞれについて、Ｘ方向に１３７６画素の位相値を演算した結果を図４に示す。
なお、この過程が本発明における第５の過程に相当する。 By solving the ternary simultaneous equations of the equation (13) and obtaining ξ _c and ξ _s , the phase φ can be obtained as in the following equation (14).

For example, FIG. 4 shows the result of calculating the phase value of 1376 pixels in the X direction for each of the R wavelength, G wavelength, and B wavelength.
This process corresponds to the fifth process in the present invention.

<Step S5> Calculation of actual height of each pixel From the obtained phase, a height candidate value is calculated for each wavelength, and a height candidate that best matches each wavelength is determined as an expected height range. Select within. Specifically, the height candidate value h _j (n) is obtained by the following equation (15), and the combination of the height candidates closest to each wavelength is selected. That is, a combination of heights that minimizes the range of combinations of height candidates between wavelengths (the difference between the maximum value and the minimum value) is obtained. Among the obtained height combinations, a height candidate value for a certain wavelength is obtained as an actual height. Alternatively, an average value of the obtained combinations of heights may be obtained as the actual height.

h _j (n) = (φ _j / 2π) * (λ _j / 2) + n (λ _j / 2) (15)

Here, j is the wavelength number (j = 1,...), N is the height candidate order, φ is the phase, and λ is the wavelength of each monochromatic light.
For example, the actual height result obtained from the phase calculation result of FIG. 4 is shown in FIG.
This process corresponds to the sixth process of the present invention.

<Step S6> Completion of calculation processing for all selected pixels?
CPU20 repeats the process of step S5-S6 until calculation of a phase and height is complete | finished about all the pixels.

<Step S8> Display of Surface Shape as Result of Calculation CPU 20 creates a display image of measurement target surface 30A from the calculated surface height information, and uses it to monitor 23 the two-dimensional surface height of measurement target surface 30A. Alternatively, information such as a three-dimensional image is displayed as shown in FIGS. The operator can grasp the concavo-convex shape on the surface of the measurement target surface 30A by observing these displays. Thus, a series of processing ends.

In the method of measuring the surface shape of a semiconductor wafer, liquid crystal panel, plasma display panel, magnetic film, glass substrate, metal film, etc.
In the generally known phase shift method using monochromatic light of one wavelength, the height difference with the adjacent pixel is limited to 1/4 or less of the wavelength of the irradiation light because of phase connection with the adjacent pixel. There was a problem.

  In the present invention, the height calculation of each pixel is obtained by the matching method from the height candidates based on the phase for each wavelength (R, G, B, etc.), unlike the phase connection with the adjacent pixels performed by the one-wavelength phase shift method. Because of independent calculation for each pixel, there is no restriction due to the wavelength of the step between adjacent pixels, and a wide height range can be measured.

DESCRIPTION OF SYMBOLS 1 ... Optical system unit 2 ... Control system unit 10 ... Illuminating device 10A / Light source 10B / Multi-band pass filter or acousto-optic filter 11 / Collimating lens 13 / Half mirror 14 / Interference objective lens 15 · · Reference surface 17 · · Beam splitter 18 · Imaging lens 19 · Imaging device 20 · · CPU
21..Memory 22..Input unit 23..Monitor 24..Driver 30..Measurement object 30 A.Measurement target surface 30B.
40 ・ ・ Holding table

Claims (6)

By irradiating the measurement target surface and the reference surface with a plurality of monochromatic lights having different wavelengths through the branching means, the intensity value of the interference fringes generated by the reflected light reflected from both the measurement target surface and the reference surface and returning on the same optical path, In the surface shape measurement method by the multiple wavelength phase shift method to detect by changing the difference of the reflected optical path length from the measurement target surface and the reference surface,
A first step of extracting a plurality of monochromatic lights having different wavelengths from irradiation light having broadband wavelength characteristics, mixing them together, and simultaneously irradiating the measurement target surface and the reference surface via a branching unit;
Interference fringe images generated by reflected light reflected from the measurement target surface and the reference surface and returning from the same optical path are changed by a single color camera by changing the difference in the reflected light path length from the measurement target surface and the reference surface. A second process of acquiring the sheets,
A third step of decomposing the acquired plurality of images for each monochromatic light;
A fourth step of removing a mixed signal from other monochromatic light contained in each monochromatic light from a plurality of images of each monochromatic light separated by the spectral characteristics of the optical system;
For each monochromatic light, a fifth process for obtaining the phase of each pixel using an expression for obtaining an interference fringe waveform from the interference fringe intensity values of the pixels at the same position in the plurality of images,
A sixth step of obtaining a plurality of surface height candidate groups from the phase of each pixel obtained for each monochromatic light, and obtaining a common height as an actual height from each candidate group;
A surface shape measuring method using a plurality of wavelengths. In the surface shape measuring method by multiple wavelengths according to claim 1,
g is an intensity value of the same pixel of a plurality of pixels in the previous period, a is a direct current component included in the interference fringe waveform nig, b is an amplitude of an alternating current component included in the interference fringe waveform, f is a frequency of monochromatic light to be irradiated, and x is x When the coordinates of the direction and φ are the phase for each monochromatic light corresponding to the predetermined pixel of the measurement target surface to be obtained,

g = a + bcos {2πfx + φ}

A surface shape measuring method using a plurality of wavelengths, which is obtained by least square fitting. The irradiation means used in any one of claims 1 to 2 extracts a plurality of monochromatic lights having different wavelengths from the irradiation light having a broadband wavelength characteristic by using a multi-band pass filter or an acoustooptic filter, and simultaneously A surface shape measuring method using a plurality of wavelengths, comprising irradiation means for irradiating in a mixed manner. By irradiating the measurement target surface and the reference surface with a plurality of monochromatic lights having different wavelengths through the branching means, the intensity value of the interference fringes generated by the reflected light reflected from both the measurement target surface and the reference surface and returning on the same optical path, In the surface shape measuring device by the multiple wavelength phase shift method that detects by changing the difference in the reflected optical path length from the measurement target surface and the reference surface,
A plurality of monochromatic lights having different wavelengths are extracted from the irradiation light having a broadband wavelength characteristic, and they are mixed to illuminate the measurement target surface and the reference surface simultaneously via the branching unit;
The interference fringe image generated by the reflected light reflected from the measurement target surface and the reference surface and returning from the same optical path can be changed with a single color camera by changing the difference in the reflected light path length between the measurement target surface and the reference surface. Imaging means for imaging a plurality of images;
Sampling means for capturing a plurality of captured images as an interference fringe intensity value for each pixel;
Storage means for storing interference fringe intensity value groups which are a plurality of the intensity values captured by the sampling means;
Performing an operation for decomposing a plurality of intensity value groups stored in the storage means for each monochromatic light;
From the multiple intensity value groups for each decomposed monochromatic light, perform an operation to remove the mixed signal from other monochromatic light contained in each monochromatic light by the spectral characteristics of the optical system,
For each monochromatic light, using the expression for obtaining the interference fringe waveform from the interference fringe intensity value of the pixel at the same position of the multiple images, obtain the phase of each pixel,
An arithmetic means for obtaining a plurality of surface height candidate groups from the phase of each pixel obtained for each monochromatic light and obtaining a common height as an actual height from each candidate group;
A surface shape measuring apparatus using a plurality of wavelengths. In the surface shape measuring apparatus with multiple wavelengths according to claim 4,
g is the plurality of pixels, a is the DC component included in the interference fringe waveform, b is the amplitude of the AC component included in the interference fringe waveform, f is the spatial frequency component of the interference fringe g, x is the coordinate in the x direction, and φ As a phase corresponding to a predetermined pixel of the measurement target surface,
The phase of each monochromatic light corresponding to the measurement pixel on the measurement target surface is an expression that is an expression of the interference fringe waveform,

g = a + bcos {2πfx + φ}

A surface shape measuring device using a plurality of wavelengths, which is obtained by least square fitting. The irradiation means used in any one of claims 4 to 5 extracts a plurality of monochromatic lights having different wavelengths from the irradiation light having a broadband wavelength characteristic by using a multi-band pass filter or an acousto-optic filter. A surface shape measuring apparatus using a plurality of wavelengths, characterized by comprising irradiation means for irradiating mixedly.

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