JP5359565B2 - Waveform analysis apparatus, computer-executable waveform analysis program, interferometer apparatus, pattern projection shape measurement apparatus, and waveform analysis method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce ripple-like analysis errors due to finitenes, etc. of the range of data. <P>SOLUTION: The method of analyzing a waveform includes a regular analysis step (S11) for calculating a specific component, included in an input waveform by analyzing the input waveform by utilizing a Fourier transform method; a model preparation step (S14) for preparing a model waveform which is the model of the input waveform by smoothing basic data including the calculated specific component; a test analysis step (S16) for calculating a specific component included in the model waveform by analyzing the model waveform prepared in the preparation step, in a way same similar to the analysis step; an error calculation step (S17) for calculating a difference between the specific component calculated in the test analysis step and the specific component actually included in the model waveform as an analysis error related to the specific component in the test analysis step; and a correction step (S21) for correcting the specific component calculated in the regular calculation step, based on the analysis error calculated in the calculation step. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a waveform analysis device applied to an interferometer device, a pattern projection shape measurement device, and the like, a computer-executable waveform analysis program, an interferometer device, a pattern projection shape measurement device, and a waveform analysis method.

  The fringe analysis processing by the Fourier transform method invented by Takeda et al. Is well known (see Non-Patent Documents 1 and 2). In order to calculate a fringe phase component from one fringe image measured by an interferometer or the like, an interference fringe on which carriers are superimposed is used for the fringe analysis processing. In the fringe analysis processing, the intensity distribution of the fringe image is Fourier-transformed, a + 1st-order or −1st-order spectrum is extracted from the obtained Fourier spectrum, the spectrum is inversely Fourier-transformed, and the obtained complex amplitude distribution is converted to a predetermined value. It is applied to the arithmetic expression. By subtracting a known carrier component from the calculated phase component, the signal component included in the phase component can be made known.

Mitsuo Takeda et al. "Fourier-transform method of fringe-pattern analysis for computer-based topography and interferometry", Journal of the Optical Society of America.Vol. 72, No. 1, January 1982 Claude Roddier and Francois Roddier APPLIED OPTICS Vol. 26 1668 (1987)

  However, since the data range of the fringe image, which is actually measured data, is limited, and the data is discontinuous at the fringe edge, the ripple component analysis error is included in the phase component calculated by the fringe analysis process using the Fourier transform method. Are superimposed.

  Accordingly, the present invention provides a waveform analysis apparatus using a Fourier transform method, a computer-executable waveform analysis program, and a waveform analysis method that can reliably suppress ripple-like analysis errors caused by the finiteness of the data range. With the goal. It is another object of the present invention to provide an interferometer device and a pattern projection shape measuring device with high measurement accuracy.

  One aspect of the waveform analysis apparatus exemplifying the present invention is that the analysis means for calculating a specific component included in the input waveform by performing analysis processing using the Fourier transform method on the input waveform, and the analysis means A model creation unit that creates a model waveform that is a model of the input waveform by performing a smoothing process on the basic data including the calculated specific component; and the analysis unit that converts the model waveform created by the model creation unit to the model waveform By performing the same analysis processing, the test analysis means for calculating the specific component included in the model waveform, the difference between the specific component calculated by the test analysis means and the specific component actually included in the model waveform, An error calculating means for calculating as an analysis error related to a specific component of the test analyzing means, and the analyzing means based on the analysis error calculated by the error calculating means And a correcting means for correcting the specific component that issued.

  One aspect of a computer-executable waveform analysis program that exemplifies the present invention is to perform analysis processing using a Fourier transform method on an input waveform, thereby calculating a specific component included in the input waveform; A model creation procedure for creating a model waveform that is a model of the input waveform by performing smoothing processing on the basic data including the specific component calculated in this analysis procedure, and a model waveform created by the model creation procedure The test analysis procedure for calculating the specific component included in the model waveform by performing the same analysis processing as the main analysis procedure, the specific component calculated in the test analysis procedure, and the specification actually included in the model waveform An error calculation procedure for calculating a difference from the component as an analysis error related to the specific component in the test analysis procedure, and the error calculation procedure. And based on said analysis error correcting the specific component calculated in the analysis procedure, characterized in that it comprises a correction procedure.

  In addition, one aspect of the interferometer apparatus illustrating the present invention includes one aspect of the waveform analysis apparatus described above.

  In addition, one aspect of the pattern projection shape measuring apparatus exemplifying the present invention is provided with one aspect of the waveform analysis apparatus described above.

  In addition, according to one aspect of the waveform analysis method illustrating the present invention, the analysis procedure for calculating a specific component included in the input waveform by performing analysis processing using the Fourier transform method on the input waveform, and the analysis A model creation procedure for creating a model waveform that is a model of the input waveform by applying a smoothing process to the basic data including the specific component calculated in the procedure, and the model waveform created in the model creation procedure to the model waveform By performing the same analysis processing as this analysis procedure, a test analysis procedure for calculating a specific component included in the model waveform, a specific component calculated in the test analysis procedure, a specific component actually included in the model waveform, and Based on the error calculation procedure for calculating the difference between the error and the analysis error calculated in the error calculation procedure. And a correction procedure for correcting the specific component calculated in the analysis procedure.

  According to the present invention, a waveform analysis device using a Fourier transform method, a computer-executable waveform analysis program, and a waveform analysis method that can reliably suppress ripple-like analysis errors caused by the finiteness of a data range and the like are realized. . Further, according to the present invention, an interferometer device and a pattern projection shape measuring device with high measurement accuracy are realized.

It is a schematic block diagram of the interferometer apparatus of 1st Embodiment. It is a flowchart of an analysis process. It is a conceptual diagram which supplements the flowchart of an analysis process. The distribution of the calculated first factor a _A (x, y) in the x direction (example), and the distribution of the calculated second factor b _A (x, y) in the x direction (example). It is a figure explaining this analysis processing by a Fourier-transform method. It is a conceptual diagram explaining the effect of 1st Embodiment. It is a schematic block diagram of the pattern projection shape measuring apparatus of 2nd Embodiment.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described. This embodiment is an embodiment of an interferometer apparatus.

  First, the configuration of the interferometer apparatus will be described. FIG. 1 is a schematic configuration diagram of the interferometer apparatus of the present embodiment.

  As shown in FIG. 1, the interferometer apparatus includes a laser light source 1, a beam expander 2, a polarizing beam splitter 3, a quarter wavelength plate 4, a Fizeau plate 5, a wavefront conversion lens 6, a beam diameter conversion optical system 8, A dimensional image detector 9 is provided. Although not shown, the interferometer apparatus is also provided with a computer. The measurement object 7 set in the interferometer device is an optical element such as an aspherical mirror or an aspherical lens, and is supported by a stage (not shown). The shape of the measurement target surface 7a of the measurement target 7 is basically smooth.

  Among these, the laser light source 1 emits a linearly polarized light beam L. The beam L expands its diameter by passing through the beam expander 2. The light beam L having an enlarged diameter enters the polarization beam splitter 3 and is reflected by the polarization separation surface 3 a of the polarization beam splitter 3. The polarization plane of the light beam L is selected in advance so as to be reflected by the polarization separation plane 3a. When the light beam L reflected by the polarization separation surface 3a enters the Fizeau surface 5a of the Fizeau plate 5 through the quarter-wave plate 4, the light beam LM passes through the Fizeau surface 5a and the light beam LR reflects the Fizeau surface 5a. To be separated. Hereinafter, the light beam LM is referred to as “measurement light beam LM”, and the light beam LR is referred to as “reference light beam LR”.

  Here, although the light beam L that has passed through the beam expander 2 has some intensity unevenness, the intensity distribution of the cross section thereof is basically smooth, and the intensity distribution of the cross section of the measurement light beam LM, the reference light beam LR The cross-sectional intensity distribution is also smooth.

  The measurement light beam LM becomes a null wavefront by passing through the wavefront conversion lens 6. The measurement light beam LM enters the measurement target surface 7a of the measurement target 7 substantially perpendicularly. The position of the measuring object 7 in the optical axis direction is set to a position where the difference between the wavefront of the incident spherical wave and the measuring object surface 7a is small.

  The measurement light beam LM is reflected on the measurement target surface 7 a to return the optical path, and enters the polarization beam splitter 3 through the wavefront conversion lens 6, the Fizeau plate 5, and the quarter wavelength plate 4. The measurement light beam LM rotates the polarization plane by 90 ° by reciprocating the quarter-wave plate 4, so that it passes through the polarization separation surface 3 a of the polarization beam splitter 3 and enters the beam diameter conversion optical system 8. To do. The measurement light beam LM is reduced in diameter by passing through the beam diameter conversion optical system 8 and is incident on the two-dimensional image detector 9 in this state.

  On the other hand, the reference light beam LR is incident on the polarization beam splitter 3 through the quarter-wave plate 4. The reference light beam LR is rotated 90 ° by reciprocating the quarter-wave plate 4, so that it passes through the polarization separation surface 3 a of the polarization beam splitter 3 and enters the beam diameter conversion optical system 8. To do. The reference light beam LM is reduced in diameter by passing through the beam diameter converting optical system 8 and is incident on the two-dimensional image detector 9 in that state.

Accordingly, interference fringes are generated on the two-dimensional image detector 9 due to the measurement light beam LM and the reference light beam LR. This interference fringe pattern reflects the shape of the measurement target surface 7a.
The two-dimensional image detector 9 captures interference fringes and acquires a fringe image. The fringe image is input to a computer (not shown). A computer (not shown) performs analysis processing on the input fringe image. Note that the analysis processing program is preinstalled in the computer.
Here, the arrangement angle of the Fizeau plate 5 is set so that the incident angle of the light beam L with respect to the Fizeau surface 5a is a predetermined angle other than zero. In this case, there is a difference between the angle at which the measurement light beam LM is incident on the two-dimensional image detector 9 and the angle at which the reference light beam LR is incident on the two-dimensional image detector 9. For this reason, stripe-shaped carrier stripes (spatial carriers) are superimposed on the interference fringes. By superimposing the carrier fringes, the spatial frequency of necessary information becomes higher than the spatial frequency of unnecessary information, so that it is possible to apply analysis processing by the Fourier transform method.
The inclination direction of the Fizeau plate 5 is selected so as to form an angle of 45 ° with respect to both the x axis and the y axis of the two-dimensional image detector 9. In this case, the carrier fringe has a common spatial frequency in both the x direction and the y direction.

Next, analysis processing by a computer will be described.
FIG. 2 is a flowchart of the analysis processing of the present embodiment, and FIG. 3 is a conceptual diagram supplementing FIG. Steps corresponding to each other between FIG. 3 and FIG. Hereinafter, each step will be described in order.

  Step S10: The computer inputs a fringe image. The fringe image I (x, y) is expressed by Expression (1).

  In Expression (1), a (x, y) is a first factor (unknown) due to the intensity unevenness of the light beam L, the measurement light beam LM, and the reference light beam LR, and b (x, y) is the intensity unevenness thereof. Is a second factor (unknown) due to, and φ (x, y) is a fringe phase component (unknown).

Incidentally, when the object of analysis processing is an interference fringe, the phase component φ (x, y) is expressed by the carrier component φ _c (x, y) (known) and the signal component φ _s (x, y) as shown in the equation (2). ) (Unknown).

  Step S11: The computer subjects the fringe image I (x, y) to the main analysis process by the Fourier transform method, and the phase component φ (x, y), the first factor a (x, y), and the second factor b ( x, y) are calculated respectively.

However, since these calculation results include analysis errors, the true phase component φ (x, y), the true first factor a (x, y), and the true second factor b (x, y) In the following, the phase component φ (x, y) calculated in this step is referred to as “calculated phase component φ _A (x, y)”, and the first factor a ( x, y) is referred to as “calculated first factor a _A (x, y)”, and the second factor b (x, y) calculated in this step is referred to as “calculated second factor b _A (x, y)”. Called.

4A is an enlarged view of an example of the distribution of the calculated first factor a _A (x, y) in the x direction, and FIG. 4B shows the calculated second factor b _A (x , Y) is an enlarged distribution (example) of the x direction. 4A and 4B, the horizontal axis represents the distance from the optical axis in terms of the number of pixels of the two-dimensional image detector 9, and the vertical axes in FIGS. 3 and 4 represent the intensity. . As shown in FIG. 4A and FIG. 4B, ripples are generated in both the calculated first factor a _A (x, y) and the calculated second factor b _A (x, y). . As described above, since the intensity distribution of the cross section of the light beam is smooth, each of the true first factor a (x, y) and the true second factor b (x, y) should show a smooth distribution. Therefore, the ripple generated in both the calculated first factor a _A (x, y) and the calculated second factor b _A (x, y) is due to the analysis error of this analysis process. Note that, similarly to the calculated first factor a _A (x, y) and the calculated second factor b _A (x, y), a ripple-shaped analysis error occurs in the calculated phase component φ _A (x, y). ing.

  Here, if the flow of the main analysis processing (analysis processing by Fourier transform method) of this step is illustrated in FIG. 5, it is as shown in FIG. 5, and the main analysis processing of this step is expressed by equations (3), (4), (5) and (6).

In these equations, F [X] represents the Fourier transform of X, F ⁻¹ [X] represents the inverse Fourier transform of X, Re [X] represents the real part of X, and Im [X] is An imaginary part of X is indicated, f ₀ indicates a filter process for cutting out a zeroth-order spectrum, and f ₊ 1 indicates a filter process for cutting out a first-order spectrum.

  In addition, the method described in Claude Roddier and Francois Roddier APPLIED OPTICS Vol. 26 1668 (1987) etc. can also be applied to this analysis process in this step.

  Step S12: The computer sets the number of repetitions i to an initial value “1”. Note that the number of repetitions i is the number of repetitions of subsequent steps S14 to S17.

  Step S13: The computer sets the basic data φ ′ (x, y), a ′ (x, y), and b ′ (x, y) of the model fringe image as initial values.

The initial value of the basic data φ ′ (x, y) is the calculated phase component φ _A (x, y) as shown in the equation (7).

Further, the initial value of the basic data a ′ (x, y) is the calculated first factor a _A (x, y) as shown in the equation (8).

Further, the initial value of the basic data b ′ (x, y) is the calculated second factor b _A (x, y) as shown in the equation (9).

Step S14: The computer smoothes the basic data φ ′ (x, y) to eliminate the ripple portion, and the model φ _m (x, y) similar to the true phase component φ (x, y). ). Further, the computer smoothes the basic data a ′ (x, y) to eliminate the ripple portion, and the model a _m (x, y) similar to the true first factor a (x, y). ). Further, the computer eliminates the ripple portion by performing a smoothing process on the basic data b ′ (x, y), and the model b _m (x, y) similar to the true second factor b (x, y) is obtained. y) is created.

  The smoothing process in this step is, for example, a spatial filter process (so-called low-pass filter process) having a smoothing function (averaging function). However, for example, as indicated by arrows in FIGS. 4A and 4B, the step in the boundary portion of the effective area of the data (the arrow portion in FIG. 4) needs to be left after the smoothing process. The smoothing process in this step is preferably performed separately for the smoothing process for the data outside the boundary part and the smoothing process for the data inside the boundary part.

Step S15: The computer applies the models φ _m (x, y), a _m (x, y), b _m (x, y) acquired in the previous step S14 to the following equation (10), A model fringe image I _m (x, y) in which each component is known is created.

Here, as described above, the models φ _m (x, y), a _m (x, y), and b _m (x, y) have the true phase component φ (x, y) and the true first factor a ( x, y) and true second factor b (x, y), respectively. Therefore, if the analysis processing for the model fringe image I _m (x, y) and the analysis processing for the fringe image I (x, y) are the same algorithm, the analysis errors of both should be similar to each other.

Step S16: The computer applies the test analysis process of the same algorithm as the main analysis process (Step S11) to the model fringe image I _m (x, y), thereby calculating the calculated phase component φ ″ (x, y), 1 factor a ″ (x, y) and calculated second factor b ″ (x, y) are acquired. When the test analysis process of this step is expressed as an equation, the equations (11), (12), (13), (14 ).

In these equations, F [X] represents the Fourier transform of X, F ⁻¹ [X] represents the inverse Fourier transform of X, Re [X] represents the real part of X, and Im [X] is An imaginary part of X is indicated, f ₀ indicates a filter process for cutting out a zeroth-order spectrum, and f ₊ 1 indicates a filter process for cutting out a first-order spectrum.

  Step S17: The computer calculates an analysis error of the test analysis process (step S16). The analysis errors include an analysis error Δφ related to the phase component, an analysis error Δa related to the first factor, and an analysis error Δb related to the second factor.

Of these, the analysis error Δφ is calculated by subtracting the model φ _m (x, y) from the calculated phase component φ ″ (x, y) as shown in the equation (15).

Further, the analysis error Δa is calculated by subtracting the model a _m (x, y) from the calculated first factor a ″ (x, y) as shown in the equation (16).

Further, the analysis error Δb is calculated by subtracting the model b _m (x, y) from the calculated second factor b ″ (x, y) as shown in the equation (17).

Step S18: The computer current iteration number i, it is determined whether or not reached the maximum value _{i max,} the process proceeds to step S19 if not reached the maximum value _{i max,} step S21 if reached the maximum value _{i max} Migrate to

The maximum value i _max is a value set in advance by the manufacturer or user of this apparatus, and is set to a large value when high measurement accuracy is required, and when the analysis time is required to be shortened. Set to a small value. There is also a method for determining whether or not to end the repetition using an error change rate or the like as an index.

  Step S19: The computer increments the number of repetitions i by one.

  Step S20: The computer uses the current basic data φ ′ (x, y), a ′ (x, y), b ′ (x, y) as the analysis error Δφ (x, y) calculated in the previous step S17. ), Δa (x, y), Δb (x, y).

Here, the updated basic data φ ′ (x, y) is obtained from the initial value (here, calculated phase component φ _A (x, y)) of the basic data φ ′ (x, y) as shown in Expression (18). , The analysis error Δφ (x, y) is subtracted.

Further, the updated basic data a ′ (x, y) is obtained from the initial value of the basic data a ′ (x, y) (here, the calculated first factor a _A (x, y)) as shown in the equation (19). , The analysis error Δa (x, y) is subtracted.

Further, the updated basic data b ′ (x, y) is obtained from the initial value of the basic data b ′ (x, y) (here, the calculated first factor b _A (x, y)) as shown in the equation (20). , The analysis error Δb (x, y) is subtracted.

  According to these updates, the basic data φ ′ (x, y) approaches the true phase component φ (x, y), and the basic data a ′ (x, y) becomes the true first factor a (x, y). ), The basic data b ′ (x, y) approaches the true second factor b (x, y).

Thereafter, the computer returns to step S14 to re-execute model fringe image creation and test analysis processing using the updated basic data φ ′ (x, y), a ′ (x, y), b ′ (x, y). To do. That is, the computer updates the basic data φ ′ (x, y), a ′ (x, y), b ′ (x, y), and updates the model fringe image until the number of repetitions i reaches the maximum value i _max. Repeat the creation and test analysis process.

As the number of repetitions increases, the model φ _m (x, y) approaches the true phase component φ (x, y), and the model a _m (x, y) is the true first factor a (x, y). Since the model b _m (x, y) approaches the true second factor b (x, y), the analysis errors Δφ (x, y), Δa (x, y), Δb (x , Y) approaches an analysis error related to the phase component of the analysis process, an analysis error related to the first factor of the analysis process, and an analysis error related to the second factor of the analysis process.

Step S21: The computer subtracts the analysis error Δφ of the test analysis process calculated in the previous step S17 from the calculated phase component φ _A (x, y) calculated in the present analysis process, thereby calculating the calculated phase component φ _A. (X, y) is corrected (formula (21)).

As a result, the analysis error (analysis error resulting from this analysis process) superimposed on the calculated phase component φ _A (x, y) is removed with high accuracy.

Thereafter, the computer subtracts the carrier component φ _c (x, y) (known) from the corrected calculated phase component φ _A ′ (x, y) to thereby obtain a signal component included in the phase component φ (x, y). φ _s (x, y) is known, and the shape of the measurement target surface 7a is known based on the signal component φ _s (x, y) and the light source wavelength.

As described above, in the analysis processing of the present embodiment, smoothing processing is performed using the analysis results (φ _A , a _A , b _A ) of the main analysis processing (step S11) as basic data, and each component has a known model fringe image ( I _m ) is created (steps S13, S14, S15). Then, the test analysis using model fringe image _{I m} (step S16, S17) by analysis error ([Delta] [phi, .DELTA.a, [Delta] b) calculating the analysis result of the analysis at the analysis error (step S11) (phi _A ) Is corrected (step S21).

Therefore, in the analysis processing of the present embodiment, the analysis result (φ _A ′) can be obtained with higher accuracy than the conventional analysis processing (when the test analysis processing is not performed).

  Moreover, in the analysis processing of this embodiment, the test analysis processing errors (Δφ, Δa) are repeated by repeating the test analysis processing (steps S16, S17) while updating the basic data (φ ′, a ′, b ′). , Δb) is brought close to the analysis error of this analysis process.

Therefore, in the analysis processing of this embodiment, the analysis result (φ _A ) of this analysis processing can be corrected with high accuracy by the analysis error (Δφ) calculated in the last iteration.

FIG. 6 is a conceptual diagram illustrating the effect of this embodiment. FIG. 6A is a diagram showing an analysis error of the conventional analysis process, and FIG. 6B is a total analysis error (when i _max = 10) of the analysis process (FIG. 2) of the present embodiment. FIG. 6 (A) and 6 (B), the horizontal axis represents the distance from the optical axis in terms of the number of pixels of the two-dimensional image detector 9, and in FIGS. 6 (A) and 6 (B). The vertical axis represents the phase with the light source wavelength λ. As shown in FIGS. 6A and 6B, ripple-like analysis errors are removed in the analysis processing of this embodiment.

  As a result of the above, the interferometer device of this embodiment can measure the shape of the measurement target surface 7a with high accuracy.

In step S13 of the present embodiment, the calculated phase component φ _A (x, y) is used as the initial value of the basic data φ ′ (x, y), but the design shape of the measurement target surface 7a is not spherical but non-spherical. In the case of a spherical surface, instead of the calculated phase component φ _A (x, y), a phase component derived from the design shape of the measurement target surface 7a (hereinafter, “design phase component φ _D (x, y)”). May be used).

This is because when the design shape of the measurement target surface 7a is an aspherical surface, the ± first-order spectrum after Fourier transform (left and right in the second stage of FIG. 5) is compared with the case where the design shape is a spherical surface. ) Spectrum) tends to be expanded, the accuracy of cutting out each spectrum in the next stage is reduced, and the calculated phase component φ _A (x, y) is separated from the true phase component φ (x, y). This is because the design phase component φ _D (x, y) is more likely to be closer to the true phase component φ (x, y).

Here, the design phase component φ _D (x, y) includes the design aspherical amount Z (x, y) of the measurement target surface 7a, the wavelength λ of the laser light source 1, and the carrier component φ _c (x, y) described above. ) And is expressed by the following formula.

φ _D (x, y) = 4πZ (x, y) / λ + φ _c (x, c)
Therefore, in steps S13 to S20 described above, the design phase component φ _D (x, y) obtained by this equation is used instead of the calculated phase component φ _A (x, y).

Incidentally, the design phase component φ _D (x, y) is smooth unlike the calculated phase component φ _A (x, y). Therefore, when the design phase component φ _D (x, y) is used as the initial value of the basic data φ ′ (x, y), the first iteration of steps S14 to S20 is performed on the basic data φ ′ (x, y). The smoothing process may be omitted and the basic data φ ′ may be used as the model φ _m (x, y) as it is.

In step S13 of the present embodiment, the calculated first factor a _A (x, y) is used as the initial value of the basic data a ′ (x, y), but the calculated first factor a _A (x, y) is used. Instead of this, an actual measurement first factor measured separately from the present device or a design first factor derived from design data of the present device may be used. When the first design factor is used, the smoothing process for the basic data a ′ (x, y) is omitted in the first iteration of steps S14 to S20, and the basic data a ′ (x, y) is used. The model a _m (x, y) may be used as it is. The first factor peculiar to the optical system is that Iα (x, y) + Iβ (x, y) based on the intensity distribution Iα (x, y) of the reference beam and the intensity distribution Iβ (x, y) of the measurement beam. y), the intensity distribution Iα (x, y) of the reference light beam and the intensity distribution Iβ (x, y) of the measurement light are first obtained, and a ′ ( x, y) = Iα (x, y) + Iβ (x, y) may be used.

In step S13 of the present embodiment, the calculated second factor b _A (x, y) is used as the initial value of the basic data b ′ (x, y), but the calculated second factor b _A (x, y) is used. Instead of this, an actual measurement second factor separately measured from the present apparatus or a design second factor derived from the design data of the present apparatus may be used. When the design second factor is used, the smoothing process for the basic data b ′ (x, y) is omitted in the first iteration of steps S14 to S20, and the basic data b ′ (x, y) is used. The model b _m (x, y) may be used as it is. Note that the second factor peculiar to the optical system is 2√ {Iα (x, y) · 2 based on the intensity distribution Iα (x, y) of the reference beam and the intensity distribution Iβ (x, y) of the measuring beam. Iβ (x, y)}, the intensity distribution Iα (x, y) of the reference light beam and the intensity distribution Iβ (x, y) of the measurement light beam are first acquired and used for subsequent measurements. In this case, b ′ (x, y) = 2√ {Iα (x, y) · Iβ (x, y)} may be used.

In addition, the update target in step S20 of the present embodiment is all the basic data φ ′, a ′, and b ′, but may be limited to only the basic data φ ′. However, the total analysis error of the analysis processing of this embodiment is smaller when all of φ ′, a ′, and b ′ are set.
Further, the interferometer apparatus of the present embodiment measures the shape of the measurement target surface 7a (that is, the spatial distribution of the height), but measures the time change of the height of an arbitrary point on the measurement target surface 7a. May be.
In that case, instead of generating carrier fringes (that is, spatial carriers), a time change waveform of a pixel value corresponding to that point may be measured while generating a time carrier, and the time change waveform may be set as an analysis target.
If this measurement is performed for each pixel, the shape change of the measurement target surface 7a (including the shape change due to the movement of the measurement target surface 7a) can be measured. Such measurement is suitable for measuring an element having a variable surface shape, such as a micromirror array.
In order to generate a time carrier by the interferometer device, the Fizeau plate 5 or the measurement object 7 may be displaced in the optical axis direction by a piezo element or the like. Incidentally, when no spatial carrier is generated, it is not necessary to incline the Fizeau surface 5a.
Further, although the Fizeau interferometer is applied to the interferometer apparatus of the present embodiment, other types of interferometers such as a Twiman Green type may be applied. Incidentally, in order to generate a spatial carrier in a Twiman Green interferometer, the reference plane may be inclined, and in order to generate a time carrier, the reference plane may be moved in the optical axis direction.

[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described. The present embodiment is an embodiment of a pattern projection shape measuring apparatus.
FIG. 7 is a schematic configuration diagram of the pattern projection shape measuring apparatus of the present embodiment. As shown in FIG. 7, the pattern projection shape measurement apparatus includes a stage 12 that supports the measurement object 11, a projection unit 13, and an imaging unit 14. The pattern projection shape measuring apparatus also includes a computer (not shown). The surface 11a of the measurement object 11 is a measurement object surface.
The projection unit 13 includes a light source 21, an illumination optical system 22, a pattern formation unit 23, and a projection optical system 24, and illuminates the measurement target surface 11a on the stage 12 from an oblique direction.
Among these, the pattern forming unit 23 modulates the intensity of the light beam directed toward the measurement target surface 11a in a sine wave shape at a predetermined spatial frequency in the spatial direction. As a result, a stripe-shaped carrier stripe is projected onto the measurement target surface 11a. The carrier stripe is distorted according to the shape of the measurement target surface 11a.
The imaging unit 14 includes an imaging optical system 25 and an imaging element 26, and images a stripe appearing on the measurement target surface 11a from the front. The fringe image (the fringe image) acquired by the imaging unit 14 through imaging is input to a computer (not shown).
The computer calculates the fringe phase component by performing an analysis process on the inputted fringe image. This analysis process is the same as the analysis process of the above-described embodiment. Then, the computer makes the signal component included in the phase component known based on the calculated phase component and carrier component (known), and makes the shape of the measurement target surface 11a known based on the signal component and the light source wavelength. Note that the analysis processing program is preinstalled in the computer.
Therefore, the pattern projection shape measuring apparatus of the present embodiment can measure the shape of the measurement target surface 11a with high accuracy.
Note that the pattern projection shape measurement apparatus of the present embodiment analyzes the waveform modulated in the spatial direction and measures the shape (space distribution of the height) of the measurement target surface 11a. The shape of the measurement target surface 11a may be measured after the direction is also modulated.

  Incidentally, in order to generate both a spatial carrier and a time carrier in the pattern projection shape measuring apparatus, the projection position of the carrier fringes by the projection unit 13 may be scanned in the pitch direction of the fringes.

  DESCRIPTION OF SYMBOLS 1 ... Laser light source, 2 ... Beam expander, 3 ... Polarizing beam splitter, 4 ... 1/4 wavelength plate, 5 ... Fizeau plate, 6 ... Wavefront conversion lens, 8 * ..Beam diameter conversion optical system, 9 ... 2D image detector

Claims (13)

This analysis means for calculating a specific component included in the input waveform by performing analysis processing using the Fourier transform method on the input waveform;
Model creation means for creating a model waveform that is a model of the input waveform by performing a smoothing process on the basic data including the specific component calculated by the analysis means;
Test analysis means for calculating a specific component included in the model waveform by performing the same analysis processing as the analysis means on the model waveform created by the model creation means;
An error calculation means for calculating a difference between the specific component calculated by the test analysis means and the specific component actually included in the model waveform as an analysis error related to the specific component of the test analysis means;
A waveform analysis apparatus comprising: a correction unit that corrects the specific component calculated by the analysis unit based on the analysis error calculated by the error calculation unit. The waveform analysis apparatus according to claim 1,
Recurring means for repeatedly operating the model creating means, the test analyzing means, and the error calculating means while updating specific components included in the basic data based on the analysis error calculated by the error calculating means,
The waveform analyzer according to claim 1, wherein the correction unit performs the correction based on the analysis error calculated by the error calculation unit in the last round of the repetition. The waveform analysis apparatus according to claim 2,
The test analysis means calculates each component included in the model waveform,
The error calculation means calculates a difference between each component calculated by the test analysis means and each component actually included in the model waveform as an analysis error regarding each component of the test analysis means,
The waveform analysis apparatus characterized in that the repeating means updates each component of the basic data based on an analysis error of each component calculated by the error calculating means. In the waveform analysis apparatus according to any one of claims 1 to 3,
The input waveform is
A waveform analyzer characterized by being a waveform modulated in a spatial direction. In the waveform analysis apparatus according to any one of claims 1 to 4,
The input waveform is
A waveform analyzer characterized by a waveform modulated in the time direction. This analysis procedure for calculating a specific component included in the input waveform by performing analysis processing using the Fourier transform method on the input waveform;
A model creation procedure for creating a model waveform that is a model of the input waveform by performing a smoothing process on the basic data including the specific component calculated in the analysis procedure;
A test analysis procedure for calculating a specific component included in the model waveform by performing the same analysis process as the main analysis procedure on the model waveform created in the model creation procedure;
An error calculation procedure for calculating a difference between the specific component calculated in the test analysis procedure and the specific component actually included in the model waveform as an analysis error related to the specific component in the test analysis procedure;
A computer-executable waveform analysis program comprising: a correction procedure for correcting the specific component calculated in the analysis procedure based on the analysis error calculated in the error calculation procedure. The computer-executable waveform analysis program according to claim 6,
While updating the specific component included in the basic data based on the analysis error calculated in the error calculation procedure, further including a repetition procedure for repeatedly executing the model creation procedure, the test analysis procedure, the error calculation procedure,
The computer-executable waveform analysis program characterized in that the correction procedure performs the correction based on the analysis error calculated in the error calculation procedure in the last round of the repetition. The computer-executable waveform analysis program according to claim 6,
In the test analysis procedure, each component included in the model waveform is calculated,
In the error calculation procedure, a difference between each component calculated in the test analysis procedure and each component actually included in the model waveform is calculated as an analysis error regarding each component in the test analysis procedure,
In the repetition procedure, each component of the basic data is updated based on an analysis error of each component calculated in the error calculation procedure. A computer-executable waveform analysis program. In the computer-executable waveform analysis program according to any one of claims 6 to 8,
The input waveform is
A computer-executable waveform analysis program characterized by being a waveform modulated in a spatial direction. In the computer-executable waveform analysis program according to any one of claims 6 to 9,
The input waveform is
A computer-executable waveform analysis program characterized in that the waveform is modulated in the time direction. An interferometer apparatus comprising the waveform analysis apparatus according to any one of claims 1 to 5.   A pattern projection shape measuring apparatus comprising the waveform analysis apparatus according to claim 1. This analysis procedure for calculating a specific component included in the input waveform by performing analysis processing using the Fourier transform method on the input waveform;
A model creation procedure for creating a model waveform that is a model of the input waveform by performing a smoothing process on the basic data including the specific component calculated in the analysis procedure;
A test analysis procedure for calculating a specific component included in the model waveform by performing the same analysis process as the main analysis procedure on the model waveform created in the model creation procedure;
An error calculation procedure for calculating a difference between the specific component calculated in the test analysis procedure and the specific component actually included in the model waveform as an analysis error related to the specific component in the test analysis procedure;
And a correction procedure for correcting the specific component calculated in the analysis procedure based on the analysis error calculated in the error calculation procedure.

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