WO2002077567A1

WO2002077567A1 - Height measuring instrument, and method of measuring height using the same

Info

Publication number: WO2002077567A1
Application number: PCT/JP2002/002659
Authority: WO
Inventors: Nobuhiro Kita; Shigeru Kanegae; Hideo Watanabe; Akihiro Kitahara
Original assignee: Olympus Optical Co., Ltd.
Priority date: 2001-03-22
Filing date: 2002-03-20
Publication date: 2002-10-03

Abstract

A height measuring instrument comprises an object lens (8) for focusing light from a light source (3) on a sample (9), a moving mechanism (14) for relatively moving the focusing position of the object lens (9) and the position of the sample (9) along the direction of the optical axis of the focused light, a small-aperture member (11) positioned conjugate to the focusing position of the object lens (9), and an optical detector (12) for detecting the intensity of the light passing through the small-aperture member (11). A method of measuring the height of the sample (9) using this height measuring instrument comprises the steps of making two cofocal images by changing the relative position between the focusing position of the object lens (8) and the sample (9), calculating the difference/sum of the outputs from the optical detector (12) for the corresponding individual pixels, and multiplying this calculated value by a predetermined coefficient, thereby obtaining information about the height of each sample point.

Description

Description Height measuring device and height measuring method using the same

The present invention records a sample height measurement method for measuring surface information of a sample by scanning the sample with light through an optical system of an optical microscope, a confocal microscope, and a height measurement program for a confocal microscope. The present invention relates to a recording medium and a program therefor.

Background art

A confocal scanning optical microscope illuminates a sample in a point-like manner, collects light (transmitted light, reflected light, and fluorescent light) from the sample onto a pinhole, and then detects the intensity of light passing through the pinhole. 3D information of the sample can be obtained by detecting with the instrument. FIG. 1 shows a schematic configuration of a conventional confocal scanning optical microscope. In the figure, light emitted from a light source 3 passes through a beam splitter 4, is reflected by a mirror 5 and enters a two-dimensional scanning mechanism 6. The two-dimensional scanning mechanism 6 includes a first optical scanner 6a and a second optical scanner 6b. The two-dimensional scanning mechanism 6 scans the light beam from the light source 3 two-dimensionally and passes through the relay lens system 7 to the objective lens 8. Be guided. The light beam incident on the objective lens 8 becomes a converged light beam and scans the surface of the sample 9 two-dimensionally. The light reflected on the surface of the sample 9 enters the beam splitter 4 via the reproduction objective lens 8, the relay lens system 7, and the two-dimensional scanning mechanism 6, and is reflected by the beam splitter 4 to form the imaging lens 1. By 0, light is condensed on a pinhole 11 which is a minute aperture member. At this time, the reflected light from the point other than the focal point of the sample 9 is focused by the pinhole 11 and only the reflected light from the focal point passes through the pinhole 11 and is detected by the photodetector 12. You. The sample 9 is placed on a sample stage 13, and can be moved in the optical axis direction by a Z stage 14. The two-dimensional scanning mechanism 6, the Z stage 14 and the photodetector 12 are controlled by a computer 15. As shown in FIG. 2A, the computer 15 issues a drive command to the scanner drive unit 19 from the CPU 25 via the CPU path 17 and the IZF (interface) 18 to drive the scanner 6.

In addition, a drive command is issued to the Z drive unit 21 via the IZF (interface) 20, Drives Z stage 14 Further, a computer program for converting the analog output of the photodetector 12 into digital data by an AZD (analog Z-digital) converter 22 and controlling the confocal scanning optical microscope used for the control process is as follows. Are recorded on the recording medium 23, copied to the main memory 24, and executed by the CPU 25. The computer program can be downloaded from a server computer located at a remote place via a communication circuit such as a network (not shown) connected to the computer 15 and executed.

Here, the condensing position of the objective lens 8 is at a position optically conjugate with the pinhole 11, and when the sample 9 is at the condensing position of the objective lens 8, the reflected light from the sample 9 is When the light is focused on the pinhole 11 and passes through the pinhole 11, but the sample 9 is located at a position shifted from the focus position by the objective lens 8, the reflected light from the sample 9 is reflected on the pinhole 11. Does not converge, and does not pass through pinhole 11. FIG. 3 shows the relative position Z of the objective lens 8 and the sample 9 at this time on the horizontal axis, and the output I of the photodetector 12 on the vertical axis. Hereinafter, this relation is referred to as an I_Z curve. As shown in Fig. 3, when the sample 9 is located at the focusing position Z o of the objective lens 8, the output I of the photodetector 12 becomes maximum, and the relative position between the objective lens 8 and the sample 9 is separated from this position. , The output of the photodetector 12 decreases rapidly. Due to this characteristic, the two-dimensional scanning mechanism 6 scans the condensing point of the objective lens 8 two-dimensionally, and the output of the photodetector 12 is imaged in synchronization with the two-dimensional scanning mechanism 6, so that a specific sample 9 can be identified. Only the height of the sample 9 is imaged, and an image (confocal image) obtained by optically slicing the sample 9 is obtained. Furthermore, the sample 9 is moved discretely in the optical axis direction by the Z stage 14, and the confocal image is acquired by scanning the two-dimensional scanning mechanism 6 at each position (each height), and light is detected at each point of the sample. By detecting the position of the Z stage 14 at which the output of the vessel 12 becomes maximum, the height information of the sample 9 can be obtained.

When measuring the height of the sample with such a configuration, if the accuracy of the measurement is to be increased, it is necessary to reduce the amount of movement of the Z stage per operation, which takes time.

Japanese Patent Application Laid-Open No. Hei 9-198643 discloses a height measuring method for improving the accuracy of the height measurement of a sample without reducing the amount of movement of the Z stage per operation. In this method, the I_Z curve is quadratic based on the photodetector output at a total of three points: the position (height) of the Z stage where the output of the photodetector is maximized, and the positions before and after it. By approximating with a line, the position (height) of the Z stage at which the output of the photodetector is maximized is obtained with an accuracy equal to or less than the movement amount of the Z stage to obtain height information.

In Japanese Patent Application Laid-Open No. H10-281843, n model data indicating a peak portion of the I-Z force is previously stored, and the model data and the n light beams are stored. It describes that the peak frequency is calculated using the output data of the detector to obtain height information. Furthermore, according to the description in Japanese Patent Application Laid-Open No. H11-246493, the I-Z curve is stored in advance, and if the reflectance of the sample is 100%, the Z-step is set. The height information is obtained by judging which Z stage position the captured photodetector output corresponds to in the I-Z curve without moving the sensor. If the reflectance of the sample is unknown, the Z stage is moved to acquire a confocal image at two Z-stage positions, and the output of the photodetector at each position is represented by the Z curve using the I_Z curve. Height information is obtained by deciding which position on the stage it corresponds to and averaging the heights of the obtained samples.

The above prior art has the following problems.

As described in Japanese Unexamined Patent Publication No. 9-68413, the I-Z curve is approximated by a quadratic curve or other curves to find the position of the Z stage at which the output of the photodetector is maximized. To do this, it is necessary to position the Z stage in at least three places. Also, if the area where the I-Z curve can be approximated by a quadratic curve or other curves is assumed to be 50% or more of the maximum output of the photodetector in the I-Z curve, the amount of one movement of the Z stage Must be less than one-third of the full width at half maximum of the I-Z curve. Furthermore, since the position of the peak (the output of the photodetector 12 is the highest output in the I-Z curve) must be estimated, the load on the computer 12 is concentrated on the arithmetic processing and the operability is impaired.

Further, according to the description of Japanese Patent Application Laid-Open No. 10-281743, n photodetectors are required, which increases the cost.

Further, according to the description in Japanese Patent Application Laid-Open No. 11-246493, when the reflectance of the sample is 100%, the photodetector taken in without moving the Z stage is used. It is determined which output (Z-curve) corresponds to which position (height) of the Z stage. As is clear from Fig. 3, the position (height) of the Z stage with respect to the output of the photodetector is determined. ) Is two As described above, the height of the sample cannot be uniquely determined.

If the reflectance of the sample is unknown, a confocal image is acquired at two Z-stage positions, and the output of the photodetector at each position corresponds to the position of the Z-stage with the I-Z carp. Even when judging this, since the output of the photodetector is proportional to the reflectance of the sample, the error in making the above judgment depends on the output of the photodetector. Therefore, since the error amount at the positions of the two Z stages generally does not match, averaging the heights of the respective Z stages cannot eliminate the influence of the reflectance of the sample. In any case, since the computer 15 needs to judge various conditions and correct the processing during operation, the effect of reducing the movement of the Z stage 14 in order to reduce the measurement time is unlikely to appear. '

Also, when the movement amount of the Z stage 14 is increased by the above-described method, it is not possible to obtain an image in which all the surfaces are in focus only by the confocal images acquired at each position. In the methods described in JP-A-09-0 684 13 and JP-A-10-281743, a specific method for obtaining a peak value at each point is described. Absent. In addition, when determining the height, there is a disadvantage that the Z stage must be positioned at at least three places in order to determine the maximum value of the output of the photodetector. Further, in Japanese Patent Application Laid-Open No. H11-2464933, when the height is obtained, only the I-Z characteristic (I-Z curve) only when the reflectance is 100 is obtained. However, since there is no description of a method for obtaining the maximum value when the reflectance is not 100%, the peak value of each point cannot be obtained.

Also, as shown in FIGS. 4A and 4B, there is a difference in the characteristics of the I-Z curve depending on the individual even if the objective lens has the same magnification. For this reason, the I-Z curve is stored in advance in the method disclosed in Japanese Patent Application Laid-Open No. H10-281843, as in the method disclosed in Japanese Patent Application Laid-Open No. H11-264733. If this is done, individual differences will also occur in confocal microscopes.

Further, in the above-described prior art, the measurement operator could not select the measurement accuracy and the measurement speed according to the measurement conditions.

Therefore, a main object of the present invention is to reduce the number of movements of the Z stage without reducing the amount of movement per movement of the Z stage, and to reduce the number of movements of the Z stage, and The present invention provides a height measuring method, a confocal microscope, a recording medium recording a height measuring program for a confocal microscope, and a program therefor.

Another object of the present invention is to increase the accuracy of sample height measurement, and at the same time, reduce the number of movements of the Z stage, thereby speeding up the measurement, and without being affected by the reflectance of the sample. Another object of the present invention is to provide a height measuring device capable of reducing the load on a control device, improving responsiveness, and expanding a measuring range.

Still another object of the present invention is to improve the accuracy of sample height measurement and reduce the number of movements of the Z stage, without being affected by the reflectance of the sample, and focusing on all surfaces. An object of the present invention is to provide a height measuring device capable of acquiring an image.

Another object of the present invention is to increase the accuracy of sample height measurement without reducing the amount of movement of the Z stage per stroke, and at the same time, to increase the Z stage required for sample height measurement. An object of the present invention is to provide a parameter setting method capable of selecting a measurement accuracy and a measurement speed according to a measurement condition when performing a measurement in which the number of times of movement is reduced.

Disclosure of the invention

The height measuring method according to the present invention includes an objective lens that focuses light from a light source on a sample, a scanning mechanism that relatively scans the focused light along the sample surface, and an optical axis direction of the focused light. A moving mechanism for relatively moving the focus position of the objective lens and the position of the sample in the optical axis direction; a minute aperture member arranged at a position conjugate with the focus position of the objective lens;

A confocal scanning microscope equipped with a photodetector for detecting the intensity of light passing through the minute aperture member is used. In this case, two confocal images are taken by changing the focusing position of the objective lens and the relative position of the sample, and the sum Z of the output of the photodetector is calculated for each corresponding pixel, and the calculated value is calculated. The height information of each point of the sample is obtained by substituting into a predetermined polynomial for.

According to the present invention, the polynomial for obtaining the height information is a linear expression.

According to the present invention, in order to obtain a calculation formula to be substituted into the linear expression, the difference between the condensing position of the objective lens and the relative position of the sample in the two confocal images is calculated by the above-described relative position-one-light detection It is 0.3 to 2 times the full width at half maximum of the output signal strength curve.

The height measuring method according to the present invention comprises an objective lens for focusing light from a light source onto a sample. Lens, a scanning mechanism that relatively scans the focused light along the sample surface, and moves the focus position of the objective lens and the position of the sample relatively along the optical axis along the optical axis of the focused light. A confocal scanning 顕微鏡 microscope equipped with a moving mechanism, a micro-aperture member arranged at a position conjugate to the focusing position of the objective lens, and a photodetector for detecting the intensity of light passing through the micro-aperture member Used. In this case, the converging position of the objective lens and the relative position of the sample are sequentially changed by a fixed amount of movement to capture multiple confocal images, and the difference between the converging position of the two objective lenses and the relative position of the sample is calculated. The difference / sum of the output of the photodetector is calculated for each corresponding pixel between the two confocal images where the shift amount is an integral multiple of the above shift amount, and this calculated value is substituted into a predetermined polynomial. Then, the height information of each point of the sample is obtained by adding the average value of the focusing position of the objective lens and the relative position of the sample in the two confocal images to the result.

According to the present invention, the shift amount obtained from the two confocal images is the movement amount. According to the present invention, the amount of movement is 0.3 to 0.8 times the full width at half maximum of the relative position-one photodetector output signal intensity curve.

A confocal scanning microscope according to the present invention includes: an objective lens for focusing light from a light source on a sample; a scanning mechanism for relatively scanning the focused light along a sample surface; and an optical axis direction of the focused light. Along, a moving mechanism for relatively moving the focus position of the objective lens and the position of the sample in the optical axis direction; a micro aperture member arranged at a position conjugate with the focus position of the objective lens; A light detector for detecting the intensity of light passing through the minute aperture member. In this case, two confocal images are captured by changing the focusing position of the objective lens and the relative position of the sample, and the output difference of the photodetector is determined for each corresponding pixel by the photodetector. A height measurement function is provided to obtain the height information of each point of the sample by dividing by the sum of the outputs and substituting it into an appropriate polynomial.

According to the present invention, there is provided a recording medium storing a control program for controlling height measurement of a confocal microscope by a computer, wherein a focusing position of an objective lens and a relative position of a sample are changed. The height information of each point of the sample is obtained by dividing the difference of each corresponding pixel by the sum of each pixel from the two confocal images taken and substituting it into an appropriate polynomial.

According to the present invention, the height of the confocal microscope can be A measurement control program that divides the difference of each corresponding pixel by the sum of each pixel from two confocal images taken while changing the focusing position of the objective lens and the relative position of the sample. By substituting it into an appropriate polynomial, the computer obtains the height information for each point on the sample.

The height measuring device according to the present invention includes: an objective lens for condensing light from a light source at a predetermined position; a scanning mechanism for relatively scanning the condensed light along a surface at the predetermined position; A moving mechanism that relatively moves the light-collecting position and the predetermined position along the optical axis direction; a small aperture disposed at a position conjugate to the light-collecting position; A photodetector for detecting the intensity, a storage device for storing a signal from the photodetector as image data, a plurality of input terminals and at least one output terminal, and a plurality of inputs from these input terminals. And a calculation device having a look-up table for outputting a predetermined value to the data. A step of acquiring a plurality of image data by changing the focusing position of the objective lens and the relative position of the predetermined position; and The image data of the two image data at one focus position is input to the look-up table via the storage device, and the image data at the other focus position is directly input to the look-up table. Process.

The height measuring device according to the invention, the minimum value A _{mi n} of the image data in the first collection point, the maximum value A _{ma x,} the minimum value of the image data in the second collection point B _min, and the maximum value and B _{ma x,} the maximum value a _{ma x} to m data between the minimum value a _min, when between the minimum value B _min to the maximum value B _{ma x} there are _n data In this case, the lookup table has at least the following data C (i, j).

C (i, j) = (B j -A i) / (B j + A i)

Where i = l, 2, 3, ..., m, j = 1, 2, 3, ..., n, where m and n are integers. Further, it is _{_{A min A i ≤ A ma x}} , B mi n B j ≤B ma x.

The height measuring apparatus of the present invention acquires a confocal image at different light condensing positions and calculates height information from the image data. This will be described. Note that the light condensing position means that the light from the light source is condensed through the objective lens 8 as shown in Fig. 5A. It is the position that was done. In addition, the shape of the I_Z carp centered on the condensing position is exactly as shown in FIG. 3, but in FIGS. 5B and 5C, the fine shape is omitted for convenience of explanation. It is.

First, the focusing position is moved to an arbitrary position on the sample 9. For example, FIG. 5B shows the state and the I-Z curve when the focusing position is set to the position of Zb. Here, the value of I-Z carp becomes maximum at the position of Z b. At a position higher or lower than Z b, the value of the I-Z curve becomes smaller as the distance from the light condensing position Z b increases. In Fig. 5B, point P on the inclined surface is located at a position lower than the focusing position Zb, so its value is lower than the maximum value Pb on the I-Z curve at the focusing position Zb. Become. Next, Fig. 5C shows the situation when the light condensing position is set to a position Za lower than Zb and the I-Z curve. In this case, since the point P is located at a position higher than the light condensing position Za, its value is lower than the maximum value P on the I-Z curve at the light condensing position Za as shown in FIG. 5C. becomes a.

FIG. 6A is a diagram in which the I-Z curves shown on the right side of FIGS. 5B and 5C are superimposed. 6A and 6B, la (Z) and Ib (Z) indicate the I-Z curves at the light condensing positions Za and Zb, respectively. Here, the I-Z curves I a (Z) and lb (Z) have the same maximum value and shape. The data (hereinafter referred to as “brightness value”) on which the I-Z curve I a (Z) or lb (Z) is obtained by previously moving the objective lens and the sample (usually a mirror surface) relatively. It is recorded on a computer.

As shown in Fig. 6A, the brightness value for point P in Figs. 5B and 5C is lb (Zp) = Pb when the focus position is at Zb, and the focus position is at Za. In the case, I a (Z p) = Pa. Therefore, for any one point on the sample (in the direction of the optical axis), there is a combination of IZ curves I a (Z) and lb (Z) at different light condensing positions corresponding one-to-one. Is shown. Conversely, if the combination of l a (Z) and l b (Z) is known, the relative position (height) in the optical axis direction at any one point on the sample can be determined.

Next, based on the I—Z carp I a (Z) and I b (Z) shown in FIG. 6A, at each Z position, C (Z) = {I b (Z) −I a (Z )} / {I b (Z) + 1 a (Z)} Fig. 6B shows the result of the calculation. Focusing on the section indicated by “measurement range” in FIG. 6B, the graph of C (Z) is almost linear in this section. Therefore, in this section, the relative position (height) in the actual optical axis direction can be obtained simply by multiplying the value of C (Z) by a predetermined coefficient. By the way, this “measurement range” is determined by the linearity and the slope of the graph. The linearity and the slope of the graph are determined by the shape of the I-Z curve shown in Fig. 3 and the interval from Za to Zb. Among these, the shape of the I-Z curve differs depending on the objective lens used. Therefore, it is necessary to measure the I-Z curve of the objective lens to be used before the measurement. Then, the I one Z curve based on, in the required linearity and _c confocal microscope from Z a so that the inclination can be obtained so that the previously determined intervals up to Z b in the graph, the sample surface 2 A sample image is formed by performing dimensional scanning. Therefore, when two-dimensional scanning is performed with the light condensing position at the position Zb, data of each pixel is obtained as a luminance value on the I-Z curve lb (Z) at the position Zb. Next, when scanning is performed by moving the light converging position to Za, data of each pixel is obtained as a luminance value on the I-Z curve Ia (Z) at this Za position. Here, in order to obtain the height of each pixel, for each pixel obtained by scanning at two light condensing positions Za and Zb, for each pixel, {lb (Z)-Ia (Z)} / {lb (Z) + I a (Z)} must be calculated. However, when trying to calculate {Ib (Z)-Ia (Z)} / {lb (Z) + Ia (Z)} while controlling various conditions, etc., the load on the computer is increased. This makes it difficult to obtain height information in a short time.

Therefore, in the present invention, U b (Z) −I a (ZZ U b (Z) + I a (Z)} is calculated in advance, and the result is stored (stored) in a lookup table. The lookup table stores data so that it has the function of outputting one value for a combination of multiple (typically two) values that are input, so that la (Z) and lb If the possible values of (Z) are, for example, la (Z) = 1, 2, 3, lb (Z) = 1, 2,

I a (Z) = 1 and l b (Z) = 1,

I a (Z) = 1 and I b (Z) = 2, I a (Z) = 3 and I b (Z) = 2

Calculate {lb (Z)-I a (Z)} / {lb (Z) + I a (Z)} for each combination of, and save the result in a lookup table. . In this way, for example, when I a (Z) = m and I b (Z) = n are input to the lookup table, (n−m) / (n + m) is output immediately. Height information can be obtained in a short time.

As described above, when two brightness values (the brightness data of the confocal image at the first focus position and the brightness data of the confocal image at the second focus position) are input to the lookup table, Data is stored so that one value corresponding to the combination of the two input values is output.

Therefore, the height measurement device of the present invention, the minimum value of Luminance data of the confocal image in the first condensing position A _{mi [pi,} the maximum value and A _{ma x,} confocal in the second collection point The minimum value of the luminance data of the point image is B _min , and the maximum value is B _raax . Then, there are n of luminance values between the m luminance value between the minimum value A _∞In maximum value A _{ma x,} the minimum value B _{mi n} to the maximum value B _ma _x. In this case, the look-up table will have at least the following data C (i, j).

C (i, j) = (B j -A i) / (B j + A i)

Here, i = 1, 2, 3, ···, m, j = 1, 2, 3, ···, n, where m and n are integers. _{Also, A mi n ≤ A i≤ A} ma x, a _{_{B mi n ≤B j ≤B ma x}} .

Further, in the height measuring device according to the present invention, the arithmetic unit inputs the image data at the other light-collecting position to the look-up table via the storage device and is adjacent to the other light-collecting position. And directly inputting image data at a different light condensing position different from the one light condensing position to the look-up table; and outputting from the look-up table for the input in the process. Adding the distance from the light position to the other light condensing position. As shown in Fig. 試料, if the surface unevenness of sample 9 is out of the height measurement range by the I-Z curve, Z stage 14 shown in Fig. Are sequentially positioned as Zl, Z2, ……, Zn and the confocal image Get. At this time, the relationship between the height of the sample 9 and the output of the photodetector 12 is the same as in the above case, with the center of the condensing position (for example, Z k, Z k +1). Obtained by Z Carp. According to the present invention, the difference Z sum signal from the look-up table which gives relative height information in each area is converted to the other light-collecting position (for example, Z k) and another light-collecting position (for example, Z k). Z k + 1) is scaled by an appropriate value determined by the interval, and the amount of movement from one focus position (Z 1) to the other focus position (Z k) is added. Height can be obtained.

Further, in the height measuring device according to the present invention, it is preferable that the look-up table has a threshold value indicating a predetermined range, and outputs C (i, j) only when the value falls within the predetermined range.

According to the present invention, the Z stage 14 determines whether or not the difference / sum value (the output data of the lookup table) is within a range that can be uniquely determined as the height information of the sample 9. This can be performed immediately by combining the luminance values Ia and lb, which are the outputs from the photodetectors 12 when positioned at the light condensing positions Za and Zb.

In the height measuring apparatus according to the present invention, the data C (i, j) is subjected to a predetermined correction.

According to the present invention, the linearity of the difference / sum value (output data of the lookup table) can be corrected in an arbitrary range.

In addition, the height measuring device according to the present invention preferably includes a step in which the arithmetic device changes the predetermined range.

According to the present invention, it is possible to arbitrarily set a determination condition such as whether the sample 9 is in a range uniquely determined as height information.

The height measuring device according to the present invention includes: an objective lens that focuses light from a light source on a sample; a scanning mechanism that relatively scans the focused light along the sample surface; and a light of the focused light. A moving mechanism for relatively moving the focus position of the objective lens and the position of the sample along the axial direction; a fine aperture disposed at a position conjugate to the focus position of the objective lens; A confocal microscope equipped with a photodetector that detects the intensity of light passing through the aperture is constructed, and two confocal images are taken by changing the focusing position of the objective lens and the relative position of the sample. , Each pixel corresponding to each confocal image Calculating the difference / sum of the outputs from the photodetectors, or the divided value, and performing appropriate scaling to obtain height information at each point of the sample; and Brightness information obtained by the height information obtained by the height information calculation means, the output of the photodetector, and the “brightness-one focus position” characteristic of the confocal microscope; have.

Further, in the height measuring device according to the present invention, the luminance calculation means uses a “luminance-focus position” characteristic based on a theoretical value (design value) of the confocal microscope.

Further, in the height measuring device according to the present invention, the luminance calculation means uses a “luminance-focus position” characteristic (I-Z curve) based on an actual measurement value of the confocal microscope.

According to the present invention, as shown in FIG. 8, when the Z stage 14 is positioned at the focal positions Za and Zb so as to sandwich the surface 9 s of the sample 9 to obtain two confocal images, As shown in FIG. 9A, the relationship between the height of the sample 9 and the output of the photodetector 12 is an I-Z curve centered on the focal positions Za and Zb, respectively.

Here, the outputs of the photodetector 12 when the Z stage 14 is positioned at the focal positions Za and Zb are defined as Ia and Ib, and the sum of the differences (la—Ib) Z (Ia + I When b) is calculated, the relationship shown in FIG. 9B is obtained at each height of the sample 9. As shown in FIG. 9B, the difference Z sum of the outputs of the photodetectors 12 is 0 at the midpoint between the focal position Za and the focal position Zb. It is almost proportional and has a one-to-one relationship. Therefore, from the relationship in FIG. 9B, if the relationship between the height of the sample 9 and the sum of the differences of the outputs of the photodetectors 12 in this use range is approximated by a linear equation having a predetermined proportionality constant, the difference Z The height of the sample 9 can be obtained from the sum signal.

Further, the height thus obtained, the actual measured values (Za, Ia) (Zb, Ib) of the output from the detector 12 at the focal positions Za and Zb, and their I- By obtaining the peak value of the luminance I at each point of the sample 9 from the Z curve, an image in which all surfaces are in focus can be obtained. As described above, the I-Z curve is a theoretical value (design value) determined from design factors such as the wavelength of the light source, the size of the minute aperture, the numerical aperture of the objective lens, and is measured for each actual device. By using these measured values, the peak value of the luminance I at each point of the sample 9 can be obtained more accurately.

Further, in the height measuring device according to the present invention, the luminance calculation means may include the height information. Dividing means for calculating the defocus amount of each point from the height information at each point obtained by the information calculating means and the height information at one of the two acquired confocal images; and It is preferable to obtain the luminance at the in-focus position of each point of the sample using the amount and a look-up table from which the corresponding luminance data can be selected.

Further, in the height measuring apparatus according to the present invention, it is preferable that the defocus amount at each point is obtained from height information of a position having a larger luminance at each point of the two confocal images.

According to the present invention, the defocus amount ΔZ is determined from the obtained height Z of the sample 9 and the position Za or Zb of the Z stage 14. From the defocus amount ΔZ and the output Ia of the detector 12 at the Za position of the Z stage 14 or the output Ib of the detector 12 at the Zb position of the Z stage 14, The peak value of the luminance I at each point of the sample 9 can be immediately obtained from the lookup table into which the value of the first Z curve is input. Further, by selecting the larger one as the output la or the output lb, the influence of SZN is reduced, and the peak value of the luminance I at each point of the sample 9 can be accurately obtained.

The parameter setting method according to the present invention is a method of setting a first axis, which is represented by a coordinate axis of a first axis indicating a relative position and a second axis orthogonal to the first axis and indicating a light intensity signal. Moving the curve I (Z) by a predetermined amount A along the first axis; the first curve I (Z) before the movement by the predetermined amount A and the first curve I (Z + A) after the movement. The operation {I (Z)-I (Z + A)} / {I (Z) + I (Z + A)} to obtain the second curve, and define the second curve group And a desired moving amount is obtained.

The present invention provides an objective lens for focusing light from a light source on a sample, a scanning mechanism for relatively scanning the focused light along the surface of the sample, and an objective lens along an optical axis direction of the focused light. A moving mechanism for relatively moving the focus position of the lens and the position of the sample, a small aperture disposed at a position conjugate with the focus position of the objective lens, and an intensity of light transmitted through the small aperture It is used for height measurement of a confocal microscope equipped with a photodetector for detecting the height. Then, two confocal point images are taken by changing the converging position of the objective lens and the relative position of the sample, and the sum Z of the output of the photodetector is calculated for each corresponding pixel. The height information of each point of the sample is obtained by multiplying by an appropriate coefficient. At this time, it is important to appropriately set the relative positions of the two confocal images.In the present invention, the I-Z curve acquired in advance and the I-Z curve are moved in the relative position direction by a predetermined amount. The sum of the differences between the curves is calculated as height information, the height information curve obtained from the difference / sum calculation is evaluated under specified conditions, and the two confocal images most suitable for measurement are evaluated. To obtain the relative distance of

In the parameter setting method according to the present invention, the objective lens for condensing the light from the first curve I (Z) light source at a predetermined position, and the objective lens may be disposed at a position conjugate to the predetermined condensing position. A configuration in which a micro-aperture and a photodetector for detecting the intensity of light passing through the micro-aperture, wherein a relative movement amount when the reflecting surface is moved along the optical axis direction in the vicinity of the converging position; And the output from the photodetector at the relative position.

The parameter setting method of the present invention is for obtaining confocal images at different light condensing positions and calculating height information from the image data.

Here, the height curve is calculated by calculating the difference Z sum between the I-Z curve la (Z) and the I-Z curve lb (Z), which is shifted by a predetermined amount in the relative position direction. . The height curve is zero at the midpoint between the top of the I-Z curve Ia (Z) and the top of the I-Z curve Ib (Z), and is almost proportional to the sample height in the vicinity. Also, as can be seen by comparing FIGS. 9A and 9B with FIGS. 10A and 10B, the height curve is determined by the shift amount between the I—Z curve la (Z) and the I_Z curve lb (Z). The slope and linearity of change. Here, as shown in FIG. 9B, the wider the linear portion of the height curve, the wider the effective range for measuring the sample height. Also, as shown in Fig. 9B, the greater the slope of the linear portion of the height curve, the greater the change in the difference / sum signal with respect to the sample height, the higher the sensitivity of sample height detection, and the higher the accuracy. A measurement can be made. As described above, since the relative shift between the I—Z curve la (Z) and the I—Z curve lb (Z) is greatly related to the measurement accuracy, it is important to set this shift appropriately. . Therefore, in the present invention, a plurality of different height curves are acquired by sequentially changing the shift amount, and A process is performed to determine whether or not each height curve satisfies a predetermined condition. As a result, a height curve satisfying the predetermined condition can be found, and an appropriate shift amount can be obtained. Here, the shift amount of the I-Z curve is a relative distance between the converging position Za and the converging position Zb. When measuring the height, the distance between the focal position Z a and the focal position Z b must be determined according to the required measurement range, measurement speed (stage or objective lens movement step), and measurement accuracy. I just need. In addition, since the I-Z force Ia (Z) differs for each objective lens, it is desirable to obtain the I-Z curve la (Z) in advance for at least the objective lens to be used.

In the parameter setting method according to the present invention, the predetermined condition can be selected according to a measurement condition.

In the parameter setting method according to the present invention, it is preferable that the measurement conditions are a type of an objective lens, a required measurement speed and a required measurement accuracy, and a measurement sample. Further, in the parameter setting method according to the present invention, it is preferable that the predetermined condition is a linearity of the second curve, and a step of determining the linearity is provided. That is, the selection of the relative distance is determined from the linearity of the height curve.

According to the present invention, the height curve is linearly shifted in an arbitrary relative distance range before and after the midpoint of the I-Z curve Ia (Z) and the I-Z curve lb (Z) shifted by a certain shift amount. If the sum of the straight line error and the square error of the height curve approximating the equation is large enough to affect the accuracy of height measurement, it can be determined that the linearity is poor, and the shift amount at this time is inappropriate. It can be determined that there is.

Further, in the parameter setting method according to the present invention, the predetermined condition is a gradient of an approximate expression when the second curve is approximated by a linear expression, and a step of determining a gradient of the approximate expression is provided. Is preferred.

According to the present invention, approximation of a height curve (second curve) obtained by using an I—Z curve la (Z) and an I—Z curve lb (Z) obtained by shifting the I—Z curve by a certain shift amount. By calculating the degree of inclination of the equation for each objective lens, the accuracy of each height curve can be determined. If the calculated result is stored, the optimum height curve can be selected in accordance with the required measurement accuracy, so that the measurement accuracy can be adjusted (selected). Further, in the parameter setting method according to the present invention, the predetermined condition may be such that:

It is preferable that the method further comprises a step of determining a range in which the curve 2 substantially matches the approximate expression, and determining the matching range. That is, the selection of the optimized relative distance is determined from the width of the straight line portion where the height curve (the second curve) and its approximate expression almost match. According to the present invention, the approximate expression of the height curve and the linear portion of the height curve obtained by using the I—Z carp I a (Z) and the I—Z curve lb (Z) shifted by a certain shift amount By determining the width of the portion where the values almost match, it is possible to determine the ratio of the measurement range to the shift amount.

Further, in the present invention, the selection of the optimized relative distance may be determined based on both the slope of the approximate expression and the width of the straight line portion where the approximate expression matches the height curve.

In this way, by controlling the balance of the operation of the present invention, it is possible to balance measurement accuracy and measurement speed.

The parameter setting method according to the present invention preferably includes a step of sequentially changing the movement amount (shift amount) to obtain a plurality of second curves.

Further, in the above, it is desirable that the acquisition of the I-Z curve and the determination of the relative distance between the light condensing positions Za and Zb are automatically performed using a computer or the like. Therefore, the present invention is a system for executing a program provided with the above parameter setting method.

Further, the present invention is a recording medium having a program provided with the above parameter setting method.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram schematically showing a configuration of a conventional confocal scanning optical microscope. FIG. 2A is a block diagram of a computer of the confocal scanning optical microscope shown in FIG.

FIG. 2B is an explanatory diagram of the recording medium of FIG. 2A.

FIG. 3 is a graph showing the relationship between the relative position of an objective lens and a sample and the output of a photodetector in a conventional confocal scanning optical microscope.

Figure 4A shows the relationship between the relative position of one objective lens and the sample with the same magnification and the output of the photodetector. It is a graph which shows a relationship.

FIG. 4B is a graph showing the relationship between the relative position of another objective lens having the same magnification and the sample and the output of the photodetector.

5A, 58 and 5 8 are explanatory diagrams showing the sample with respect to the focal position.

FIG. 6A is a graph showing the relationship between the relative position of the objective lens and the sample and the output of the photodetector, with the I-Z curves in FIGS. 5B and 5C superimposed.

FIG. 6B is a graph showing the relationship between the relative position of the objective lens and the sample and the Z-sum difference signal of the photodetector output.

FIG. 7 is an explanatory diagram showing a sample having irregularities at each focal position.

FIG. 8 is an explanatory diagram showing the position of the Z stage with respect to the sample when obtaining two confocal images.

FIG. 9A is a graph showing the relationship between the relative positions of the objective lens and the sample and the photodetector output when obtaining two confocal images in FIG.

FIG. 9B is a graph showing the relationship between the relative position of the objective lens and the sample in FIG. 8A and the difference Z sum signal of the photodetector output.

FIG. 10A is a graph showing the relationship between the relative position of the objective lens and the sample and the output of the photodetector when the slope of the linear portion of the difference / sum signal is large.

FIG. 10B is a graph showing the relationship between the relative position of the objective lens and the sample and the difference Z sum signal of the photodetector output when the slope of the linear portion of the difference Z sum signal is large.

FIG. 11A is a graph showing the relationship between the relative position between the objective lens and the sample and the output of the photodetector in the second embodiment of the present invention.

FIG. 11B is a graph showing the relationship between the relative position between the objective lens and the sample and the sum signal of the photodetector output in the second embodiment.

FIG. 12 is a flowchart for obtaining the height of the sample in the second embodiment.

FIG. 13 is an explanatory diagram of the second embodiment in which the value of the constant is set so that the height of the sample is uniquely determined with respect to the difference / sum signal corresponding to the calculation range. FIG. 11B is a graph showing the relationship between the relative position of the objective lens and the sample and the difference / sum signal of the photodetector output in the second embodiment. FIG. 14 is a block diagram showing a circuit configuration of the height measuring device according to the fourth embodiment of the present invention.

FIG. 15 is a diagram illustrating an example of an output data format of LUT of the height measuring device according to the fourth embodiment.

FIG. 16 is a block diagram showing a circuit configuration of the height measuring device according to the fifth embodiment of the present invention.

FIG. 17A is a graph showing the relationship between the relative position of the objective lens and the sample and the output of the photodetector in the fifth embodiment.

FIG. 17B is a graph showing the relationship between the relative position of the objective lens and the sample and the Z-sum difference signal of the photodetector output in the fifth embodiment.

FIG. 18 is an explanatory diagram of the operation of the frame unit in the fifth embodiment.

FIG. 19 is a schematic diagram of a confocal scanning microscope constituting a height measuring device in the sixth and seventh embodiments of the present invention.

FIG. 2OA is a graph showing the relationship between the relative position of the objective lens and the sample and the output of the photodetector in the sixth embodiment.

FIG. 20B is a graph showing the range of the difference sum signal used in the sixth embodiment.

FIG. 20C is a graph showing that the height of the sample can be obtained from the difference Z sum signal of FIG. 20B.

FIG. 21 is a graph showing the relationship between the relative position of the objective lens and the sample and the output of the photodetector with normalized luminance.

FIG. 22 is a flowchart showing a calculation procedure in the parameter setting method according to the eighth embodiment of the present invention.

FIG. 23 is a flowchart showing a calculation procedure in the parameter setting method according to the ninth embodiment of the present invention.

FIG. 24 is a flowchart showing a calculation procedure in the parameter setting method according to the tenth embodiment of the present invention.

FIG. 25 is a graph showing the relationship between measurement accuracy and measurement speed in the parameter setting method according to the tenth embodiment of the present invention. FIG. 26A is an explanatory diagram showing the sample shape and the position of the Z stage in the parameter setting methods of the eighth to tenth embodiments.

FIG. 26B is an explanatory diagram of the measurement range in the measurement of FIG. 26A.

FIG. 27A is a graph showing the relationship between the relative positions of the objective lens and the sample and the photodetector output when measuring the height of the sample in FIG. 26A.

FIG. 27B is a graph showing the relationship between the relative position between the objective lens and the sample and the difference / sum signal of the photodetector output.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First embodiment

The confocal scanning microscope used in the present embodiment has the same configuration as that shown in FIG. 1 described as the related art, and thus the same reference numerals are given and the description is omitted. It is assumed that the calculation procedure shown in the following embodiment is recorded as a computer program as a height measurement program 23a of the recording medium 23 shown in FIG. 2B.

As shown in Fig. 8, the movement interval (Zb-Za) of the Z-stage 14 set so as to sandwich the surface 9 s of the sample 9 becomes approximately 0.3 times the full width at half maximum of the I-Z curve. To obtain two confocal images. As shown in FIG. 9A, the height of the sample 9 and the output relation of the photodetector 12 at this time are I-Z curves centered at Za and Zb, respectively.

Here, the output of the photodetector 12 when the Z stage 14 is positioned at Za and Zb is defined as Ia and Ib, and the difference / sum signal, that is, (la—Ib) Z (I When a + I b) is calculated, the relationship shown in Fig. 9B is obtained at each height of the sample. As shown in FIG. 9B, the difference Z sum signal of the outputs of the photodetectors 12 is 0 at the midpoint of Za and Zb, and is almost proportional to the sample height near that. Therefore, the height of the sample 9 can be obtained by multiplying the difference / sum signal by a predetermined value determined by the interval between Za and Zb. Therefore, the wider the linear portion of the difference / sum signal, the wider the measurement range of the sample height. Therefore, the interval between Za and Zb is set to approximately 0.3 times the full width at half maximum of the I-Z curve so that the height measurement range is the widest. The height measurement range at this time is approximately 1.4 times the full width at half maximum of the I-Z curve. A modification of the first embodiment will be described.

Set the interval between Za and Zb of Z stage 14 to almost twice the full width at half maximum of the I-Z curve. The relationship between the height of the sample 9 and the output of the photodetector 12 at this time is shown in FIG. 10A, and the difference / sum signal of the output of the photodetector 12 is shown in FIG. 10B. The greater the slope of the linear portion of the difference signal of the outputs of the photodetectors 1 and 2, the greater the change in the difference / sum signal with respect to the sample height.This increases the sample height detection sensitivity and increases the accuracy of the measurement. It can be performed.

In other words, when the interval between Za and Zb of the Z stage 14 is set to almost twice the full width at half maximum of the I-Z curve, the height detection sensitivity of the sample becomes the highest and high-precision measurement is performed. be able to.

Note that the interval between Za and Zb of the Z stage 14 is not limited to the above value, but may vary depending on the height range and measurement accuracy required for height measurement. Can be set between 0.3 and 2 times the full width at half maximum of.

According to the present embodiment, by changing the position of the Z stage and acquiring and calculating two confocal point images having different heights, the surface unevenness of the sample is maximum, and the half value of the I-Z carp is obtained. It can measure with high accuracy up to about 1.4 times the full width.

In the present embodiment, the height information is obtained by the linear expression of the difference / sum, but if it is a polynomial, the height can be obtained in a wider range.

Second embodiment

As shown in Fig. 7, the Z stage 14 is set so that the surface 9 s of the sample 9 having relatively large irregularities is sandwiched, and the distance between Z k and Z k + 1 is almost the full width at half maximum of the I-Z curve. The setting is made to be 0.8 times, and the Z stage 14 is sequentially positioned from Z1 to Zn to obtain a confocal image. At this time, the relationship between the height of the sample 2 and the output of the photodetector 12 is an I-Z carp centered on Z k and Z k + 1 as shown in FIG. 11A.

Here, the output of the photodetector 12 when the Z stage 14 is positioned at Z k and Z k + 1 is defined as I k and I k + 1, and the difference / sum signal (I k + 1− I k) / When (I k + 1 + I k) is calculated, the relationship shown in FIG. 11B is obtained at each height of the sample 9. As shown in FIG. 11B, the difference / sum signal of the output of the photodetector 12 becomes 0 at the midpoint between Z k and Z k + 1, and is almost proportional to the height of the sample 9 in the vicinity thereof. Therefore, the difference / sum signal is added at the interval of Z k and Z k + 1 The height of the sample can be obtained by multiplying by the determined predetermined value and adding the average value of Zk and Zk + 1.

According to the second embodiment, the interval between Zk and Zk + 1 is set to be approximately 0.8 times the full width at half maximum of the I-Z curve. The measurement range of the sample height coincides with the interval between Zk and Zk + 1. For this reason, when obtaining the confocal image by sequentially positioning the Z stage 14 at Zl, Z2, ···, and Zn, the confocal point at the position of the immediately preceding Zk-1 can be obtained for any Zk position. If only the images are temporarily stored in the computer 15, the height of the sample can be measured by the above-described method, so that the image memory of the computer 15 can be reduced.

In this way, when height measurement is performed, only the confocal image at the position of Zk-1 immediately before is temporarily stored, and in order to enable height measurement, the interval between Zk and Zk + 1 must be The width is not limited to 0.8 times the full width at half maximum of the I-Z curve, but may be 0.3 times the full width at half maximum of the I-Z curve (see the first embodiment) or 0.8 times.

Since the sum signal of the height of sample 2 and the output of photodetector 12 is proportional only when the height of sample 2 is between Zk and Zk + 1, the position of Z stage 12 is When moving from Z1 force to Zn, if the height of sample 2 is not between Zk and Zk + 1, the height of sample 2 cannot be obtained correctly even if the above difference Z sum signal is calculated. .

Therefore, a method of obtaining the height of the sample 9 when the height of the sample 9 is not between Zk and Zk + 1 will be described with reference to the flowchart of FIG.

First, the k value of the Z counter (not shown; the same applies hereinafter) built into the computer 15 is set to the initial value 1, the Z stage 14 is moved to the position Z1, and the confocal of the sample 9 is placed at this position. The image I (X, y) is fetched and stored in the image memory M (X, y) (not shown; the same applies hereinafter) built in the computer 15 (step S1). Next, the k value of the Z counter is increased by 1, the Z stage 14 is moved to the position of Z2, and the confocal image I (x, y) of the sample 9 is captured (step S2). Here, the value I (x, y) of the confocal image of each point of the sample 9 obtained in step S2 and the value of the confocal image of the sample 9 obtained in step S1, The sum of the values M (x, y) is calculated, and the constant C1 is compared with the magnitude (step S3). As shown in Fig. 13, the value of the constant C1 is such that the height of sample 9 is higher than the difference Z sum signal corresponding to the calculation range. It is set to be determined uniquely.

If the sum of the value I (x, y) of the confocal image and the value M (x, y) of the memory M in step S3 is equal to or greater than the constant C1, the above I (X, y) and M (x , Y) and Z (x, y) are calculated (step S4). As shown in Fig. 13, the difference / sum signal between the height of sample 9 and the output of photodetector 10 is proportional to the difference / sum signal between C2 and C2. Then, the absolute value of the difference / sum signal calculated in step S4 is compared with the magnitude of the constant C2 (step S5). If the absolute value of the difference sum signal is smaller than C2, the difference Z sum signal is multiplied by C3 determined by the interval between Zk and Zk + 1, and the average value of Zk and Zk + 1 is added. Then, it is stored in a height memory Z (x, y) (not shown; the same applies hereinafter) built in the computer 15 (step S6).

Next, the value I (X, y) of the confocal image is stored in the image memory M, y) (step S7). The above steps S2 to S6 are performed until the k value of the Z counter becomes n (step S8).

With the above procedure, for the difference / sum signal corresponding to the calculation range, the difference Z sum signal is calculated only for the range where the height of the sample 9 is uniquely determined, and then the sample is calculated for the difference Z sum signal. Only in the range where the height of 9 is proportional, the height calculation result is stored in the height memory Z \.

In step S3, the sum of the value I (X, y) of the confocal image and the value M (x, y) of the image memory M, and the difference / sum signal corresponding to the calculation range, Judgment is made to determine whether the height is uniquely determined. However, the present invention is not limited to this. The height of the sample 9 is calculated based on the difference Z sum signal corresponding to the calculation range based on the confocal image value I (X, y) and the value M (x, y) Any condition can be used as long as it can be determined whether or not is within a range uniquely determined.

Third embodiment

According to the third embodiment, by changing the position of the Z stage and sequentially acquiring and calculating a plurality of confocal images having different heights, the surface of the sample has the largest convexity, and the I-Z curve Outline 1. Since the measurement can be performed even at about 4 times or more, high-speed and high-accuracy height measurement can be performed.

In the present embodiment, the shift amount is made to coincide with the movement amount. The height can be determined with higher precision by setting it to an integral multiple of the quantity (2, 3, 4,...).

Fourth embodiment

FIG. 14 shows a circuit configuration of a height measuring apparatus according to a fourth embodiment of the present invention. This configuration is provided in a computer 15 which is a control device of the confocal scanning optical microscope shown in FIG.

The AZD converter 101 outputs the output signal of the photodetector 12 corresponding to the amount of reflected light from the sample 9 passing through the pinhole 11 shown in FIG. 1 as a digital value. It is designed to sequentially convert digital values according to the sampling clock (SCLK) synchronized with scanning. Digital image data from the A / D converter 101 is sent to the frame buffer 102 and one input port B of the lookup table 103 (hereinafter, LUT). The frame buffer 102 is a memory having a capacity of one screen and temporarily storing digital image data from the AZD converter 101 in synchronization with scanning by the two-dimensional scanning mechanism 6. The output from the frame buffer 102 is sent to the other input port A of the LUT 103. The LUT 103 outputs one value corresponding to a combination of two input values sent from the two input ports A and B, and stores table data as shown in Table 1. Table 1 shows, for simplicity, for example, assuming that the maximum value of the two inputs is “20”, and for each combination of the two inputs, the operation of (B—A) / (A + B) The example of the table which expanded the value is shown. Here, since the area in which the height information is uniquely determined in the calculation of (B−A) / (A + B) is limited, the LUT 103 can use the input means (not shown) to validate the calculated value. Data processing is performed so that an invalid condition can be given. For example, as shown in Table 2, “UPJ“ DOWN ”,“ OVER ”, and“ UNDERJ ”play a role of giving a valid Z invalid condition of the operation value. UP, DOWN, OVER, and UNDER can be freely determined. As a result, if the value of (B−A) / (B + A) is out of the predetermined range, “UP”, “DOWN”, “OVER”, “UN DER” will be output as range information. The condition that determines “OVER” is when the input is saturated. As is evident from Fig. 4A, when one of the values is the maximum value, the other always shows a smaller value, so that both do not take the vicinity of the maximum value. Therefore, if a predetermined value (in this case, “15”) is exceeded at the midpoint between Z a and Z b, the calculation value is limited so as not to indicate the calculated value. It can be changed as the “upper threshold” because it changes at the curve interval.

The condition that determines "UNDER" is when the two inputs are too small. Limit the input values that deviate from the two I-Z curves, that is, do not indicate the calculated values near the left and right ends that are less than the specified value (in this case, “3”). The predetermined value in this case can be changed as the “lower threshold value” because it is determined by how much the calculation range is desired.

The condition for determining “UP” is determined by the input value to input port A of LUT103. Determine the upper end of the effective measurement range. If the input value to input port A is less than the “lower threshold” (in this case, “3”), limit the computed value to not be displayed.

The condition for determining “DOWN” is determined by the input value to input port B of LUT103. Determine the lower end of the effective measurement range, and limit the computation if the input value to input port B is less than the “lower threshold” (in this case, “3”).

ξΖ

S9Z0 / Z0df / X3d .9S..0 / Z0 OAV

Table 3

A

1 2 3 4 8 9 10

1 Awake 1DER DOI DOI DOI DOI DOI DOI DOI DOI DOI Customer_ DOI DOI DOI D Day DOI DOI D Sonokuni 2 UNDER Secret R 麵 DOI DOI DOI DOI DOI Country DOI DOI DOI DOI DOI DOI DOI DOI Customer DOI Country 3 UP UP 128 103 84 70 59 49 41 35 29 24 20 16 13 9 7 4 2 0 4 UP UP 152 128 108 93 80 70 61 54 47 41 36 32 28 24 21 18 15 13 5 UP UP 171 147 128 112 99 88 78 70 63 56 51 46 41 37 33 30 27 24 6 DP DP 185 162 143 128 114 103 93 84 77 70 64 59 54 49 45 41 38 35 7 OP UP 197 175 156 156 141 128 116 106 97 89 82 n 70 65 60 56 52 48 44 8 UP OP 206 185 167 152 139 128 117 108 100 93 86 80 75 70 65 61 57 54 9 UP DP 214 194 177 162 149 138 128 128 118 110 103 96 90 84 79 74 70 66 62

10 UP 'UP 220 201 185 171 158 147 137 137 128 119 112' 105 99 93 88 83 78 70 11 UP UP 226 208 192 178 166 155 145 136 128 120 113 107 101 96 91 86 82 77 12 UP UP 231 214 199 185 185 173 162 152 143 135 135 128 121 114 108 103 98 93 89 84 13 UP UP 235 219 204 191 179 169 159 150 150 142 134 128 121 115 110 105 100 95 91 14 UP UP 239 223 209 197 185 175 175 165 156 148 141 134 128 122 116 111 106 101 97 15 UP UP 243 227 227 201 201 190 180 171 162 154 147 147 140 133 128 122 117 112 107 103 16 UP OP 246 231 218 206 195 185 176 167 167 159 152 145 139 133 Awakening Oki OVER OVER 17 DP UP 248 234 222 210 210 199 190 181 1 top and bottom 72 164 157 151 144 138 OVER Oki OVER OVER OVER 18 UP UP 251 237 225 225 214 203 194 185 177 177

Great calculation

19 IIP UP 253 240 228 217 207 198 189 189 181 174 166 166 160 154 148 瞧 OVER Oki Hikasa OVER 20 ϋΡ UP 255 243 231 220 211 201 193 185 178 171 164 158

Taking

7 »

on Then, as shown in FIG. 15, when the output format of the LUT 103 is set to 12 bits, the above four results can be output to the upper 4 bits via a comparison circuit (not shown). I have.

Separately, the calculation result of (B-A) / (A + B) in the valid range as the height information of sample 9 has positive and negative values. Is scaled. For example, when the number of output bits is set to, for example, 8 bits, scaling is performed as in the following equation.

(Β-Α) / (Α + Β) / Maximum value X 255/2 + 1 28

Combining these results, the data in LUT 103 is as shown in Table 3. Here, the “maximum value” is a value normalized such that the upper and lower ends of the effective measurement range correspond to the upper and lower limits in the output bit number. Specifically, it corresponds to the maximum value in Table 2. Further, the data in the area outside the effective measurement range may be replaced with, for example, “0” so as not to be output as the height information of the sample 9, and can be represented by an arbitrary value. Such a table may be created in advance corresponding to the gradation of the digital value output from the photodetector 12 whose input is predicted.

A process of determining the height of the sample 9 according to the present embodiment configured as described above will be described. As shown in FIGS. 5A to 5C, the Z stage 14 is set at an interval of Za and Zb so as to sandwich the surface 9 s of the sample 9 so as to obtain a confocal image. As shown in FIG. 6A, the relationship between the height of the sample 9 and the output of the photodetector 12 at this time is, as shown in FIG. 6A, an I-Z curve Ia (Z), lb ( Z).

When such a confocal scanning optical microscope equipped with the height measuring device of the present embodiment is operated, a confocal image at the Za position is first obtained in synchronization with scanning. The AZD converter 101 in Fig. 14 converts the output of the photodetector 12 into digital data for each pixel by SCLK. The converted image data is temporarily stored in the frame buffer 102. When the image of one frame is captured by the frame buffer 102, the Z stage 14 is moved to the Zb position to start capturing the image of the next frame. Simultaneously with the start of the image capture of this frame, the image data of the immediately preceding frame (Za position) stored in the frame buffer 102 is taken out, and the LUT 103 receives the Za and Zb directions. Data of the same pixel at the position You.

Here, the output of the photodetector 12 when the Z stage 14 is positioned at Za and Zb is Ia and Ib, and the difference Z sum signal (Ib—la) / (Ia + Ib) When. Is calculated, the relationship shown in FIG. 6B is obtained at each height of the sample 9. As shown in Fig. 6B, the difference Z sum of the outputs of the photodetectors 12 is 0 at the midpoint between the Za position and the Zb position, and a value that is almost proportional to the sample height is obtained in the vicinity. . Therefore, the height information of the sample 9 can be obtained by scaling this difference Z sum signal with an appropriate value determined by the interval between the Za position and the Zb position.

Since the LUT 103 is created in advance according to this processing, one piece of height data after calculation corresponding to the data of the same pixel at the sequentially input Za and Zb positions is immediately determined. . For example, the reflected light from the point P on the surface of the sample 9 shown in FIGS. 5B and 5C is transmitted through the photodetector 12 when the Z stage 14 is positioned at the focusing positions Za and Zb. It is obtained as the values of P a and P b of A and converted by the A / D converter 101. One value passes through the frame buffer 102 and the other value is directly Input to two input ports A and B. Since LUT 103 outputs the value P _LUT in FIG. 6B, it uniquely indicates the position of Z p. Note that the wider the linear portion of the difference Z sum signal, the wider the effective range of the sample height measurement. Therefore, in this embodiment, the interval between Za and Zb is set to approximately 0.3 times the full width at half maximum of the I-Z curve so that the effective measurement range of the sample height is maximized. At this time, the effective measurement range of the sample height is approximately 1.4 times the full width at half maximum of the I-Z curve.

By the way, at both ends of the effective measurement range, the “change in Z coordinate, the change in Z operation value” changes compared to the center, and the linearity of the difference / “sum signal operation data becomes worse toward the end. The area that can actually be used for measurement is reduced.Therefore, the linearity can be improved by applying appropriate corrections to the data stored in the LUT 103. Also, the actual I-Z curve is This may cause the linearity of the calculated data to deteriorate, but it is also possible to correct it, and set the “lower threshold” to the LUT 103 appropriately. The effective range of measurement can be set freely by adjusting, so the range where the value of difference / sum is uniquely determined It can be extended to In addition, since these correction processes are performed when preparing table data from the I-Z curve in advance in the LUT 103, they do not impose a load on the computer 15 during measurement, and lower the scanning speed, drawing speed, etc. In addition, it is possible to absorb fluctuations and obtain accurate height information immediately. Further, by repeatedly scanning the Z stage 14 in synchronization with the two-dimensional scanning, it is possible to directly display three-dimensional data in accordance with the scanning.

As described above, according to the height measuring apparatus of the present embodiment, the accuracy of the height measurement of the sample 9 can be increased, and at the same time, the number of movements of the Z stage 14 can be reduced to speed up the measurement. be able to. In addition, the influence of the reflectance of the sample 9 can be eliminated, and the load on the control device can be reduced, the responsiveness can be improved, and the effective measurement range can be expanded.

Fifth embodiment

FIG. 16 shows a circuit configuration of a height measuring apparatus according to a fifth embodiment of the present invention. The configuration of the present embodiment, except for the monitor 806, is provided in a computer 15 which is a control device of the confocal scanning optical microscope shown in FIG.

The A / D converter 801 is a two-dimensional scanning mechanism that outputs the output signal of the photodetector 12 as a digital value corresponding to the amount of reflected light from the sample 9 that has passed through the pinhole 11 shown in Fig. 1. The conversion is performed sequentially according to the SCLK synchronized with the scanning of 6. The digital image data from the AZD converter 801 is sent to the frame buffer 802 and one input port B of the LUT 803. The frame buffer 802 is a memory having a capacity of two screens 802 (a) and 802 (b) and storing digital image data from the AZD converter 801 in synchronization with the scanning of the two-dimensional scanning mechanism 6. . In addition, the frame buffers 802 (a) and 802 (b) are configured so that writing and reading are exclusively switched alternately by a vertical synchronization signal (hereinafter, VD) from the two-dimensional scanning mechanism 6. I have.

The output from the frame buffer 802 on the read side is sent to the other input port A of the LUT 803. The LUT 803 outputs one value corresponding to a combination of the two input values sent from the two input ports A and B, and stores the same table data as in the first embodiment of the present invention. Input means (not shown). Data processing is performed so that the valid / invalid condition of the difference / sum operation value can be given. Then, the LUT 803 separately outputs a flag for the measurement effective range together with the height information of the sample 9. The addition control circuit 804 receives the VD from the two-dimensional scanning mechanism 6 and the flag for the measurement effective range from the LUT 803, and adds the height information of the sample 9 output from the LUT 803 to the Z stage 14 described later. It is configured to add the information for each divided moving area and control writing to the drawing memory 805. The drawing memory 805 is a memory in the computer 12 for displaying a control interface of the confocal scanning optical microscope and various information. The monitor 806 displays the contents of the drawing memory 805 to the operator as each information of the confocal scanning optical microscope, so that the operator can visually recognize the height information of the sample 9.

A process of obtaining the height of the sample 9 according to the present embodiment configured as described above will be described. In the case of measuring the height of sample 9 having relatively large irregularities as shown in Fig. 7, since the surface depression of sample 9 protrudes from the effective height measurement range by the I-I curve, the fourth embodiment It is not possible to measure all of the two Ζstages 14 only from the position as close as. Thus, as shown in Fig. 7, the moving range of the stage 14 is set so as to sandwich the surface 9 s of the sample 9, and the stage 14 is sequentially positioned at equal intervals from Z 1 to Ζη to share Try to get a focused image. At this time, the relationship between the height of the sample 9 and the output of the photodetector 12 is, as shown in Fig. 17Α, the I-Z curve I k ( Z), I k + 1 (Z).

Here, in order to simplify the explanation, the interval between Z k and Z k + 1 or the “lower threshold” to LUT 803 is appropriately adjusted in advance, and the Z k position of Z stage 14 is adjusted. It is assumed that the distance from the Z k + 1 position is equal to the effective measurement range.

When a confocal scanning optical microscope equipped with such a height measuring device of this embodiment is operated, a confocal image (1) at the Z1 position is first synchronized with scanning as shown in Fig. 18. can get. The AZD converter 801 in FIG. 16 converts the output of the photodetector 12 into digital data for each pixel by SCLK. The converted image data is temporarily stored in the frame buffer 802 (a). When an image of one frame is captured by the frame buffer 802 (a), the Z stage 14 is moved to the Z2 position and the capture of the image ② of the next frame is started. As soon as the image of this frame starts to be captured, the frame buffer 802 (a) and the frame buffer 802 (b) are switched, and the frame buffer 802 (a) starts reading and stores the previous frame (Z 1 The image data ① ′ at the position) is taken out, and data of the same pixel at both positions Z 1 and Z 2 are sequentially input to the LUT 803. The switched frame buffer 802 (b) stores the image data at the Z2 position at the same time.

In this manner, in synchronization with the movement of the Z stage 14, the subsequent frames alternately switch the frame buffers 802 (a) and 802 (b) and store the current frame image data while storing the current frame image data. The image data of the frame and the image data of the previous frame are input to the LUT 803 as “② and ③”, “③ and ④”…. For example, the process of outputting height data from LUT 803 at point Q in FIG. 7 is the same as the process of outputting height data from LUT 103 at point P in FIG. 5B or 5C in the fourth embodiment. Is the same. In this way, the height information of the sample 9 can be obtained for each section while the Z stage 14 is sequentially positioned at equal intervals from Z1 to Zn.

By the way, when the Z stage 14 is positioned at Zk, Zk + 1, the output of the photodetector 12 is Ik, Ik + 1, and the difference / sum signal (Ik + 1-Ik) / ( When I k + 1 + I k) is calculated, the relationship shown in Fig. 17A is obtained at each height of the sample 9, but it is only height information for each section. Therefore, if the sum of the difference Z sum signal and the appropriate value determined by the number of bits for expressing between the Z k position and the Z k + 1 position multiplied by the number of movements to the Z k position is added, The height information of sample 9 can be obtained continuously over a period of time. In other words, since the number of movements of the Z stage 14 since the start of scanning has a corresponding relationship with the number of frames, the addition control circuit 804 controls the VD, and if the section is represented by 8 bits, the Z LUT of `` 256 X 0J '' between 1 and Z 2, `` 256 X 1 '' between Z 2 and Z 3, `` 256 X (k-1) '' between Z k and Z k + 1 It is added to the height data of 803 output. Also, writing to the drawing memory 805 is prohibited for pixels for which a height cannot be obtained in the current section. As a result, the drawing memory 805 has a height only for the pixel whose height is obtained. The data will be stored.

In order to actually make the height information continuous, pay attention to “UP” and “DOWN” among the 4 bit determination flags output from the LUT 803 in FIG. When “UP” is attached to the height information of a certain pixel, for example, the information of the point R when measuring the area of Z k and Z k + 1 in FIG. 7 corresponds. Point R is in the “UP” area, as is clear from FIGS. 17A and 17B, and the height information is replaced by “0” in such an area, so that “256 X (k-1) ) + 0 ”is calculated, but writing to the drawing memory 805 is prohibited because“ UP ”is added. : The point height is obtained at the positions corresponding to R a ′ and R b ′ in FIG. 17A in the region of Z k + 1 and Z k + 2. "256 xk" is added. Here, since the flag disappears, the point R is written into the drawing memory 805 with a value of “256 X k + R”. In other words, the Q point in Fig. 7 has a height of "256 X (k-1) + Q" and the R point has a height of "256 X k + R". It will be. However, in the case of the “UP” flag, there is no problem even if the writing to the drawing memory 805 is not prohibited, since the height data is correctly overwritten when the subsequent height data is obtained.

Conversely, when “DOWN” is attached to the flag, the addition control circuit 804 must prohibit writing to the drawing memory 805. This can be considered by exchanging the viewpoints of the Q point and the R point, and from the region of Z k + l and Z k + 2, the Q point is

"DOWN". The height of the Q point has already been found in the Z k and Z k + 1 regions, but the addition control circuit 804 uses the height data of the Q point in the Z k + 1 and Z k + 2 regions.

Γ 256 X k j is added to Γ 0 J. In this case, Γ256 X (k−1) + Q ”」 Γ256 X k + 0 J, so this value must not be written to the drawing memory 805.

In this manner, in the present embodiment, height data is written into the drawing memory 805 from the pixel whose height has been newly determined while the Z stage 14 moves from Z1 to Zn, and the height once increases. The determined pixel is not overwritten. Also, in the height measurement of the sample 9 having relatively large irregularities as shown in Fig. 7, the correction processing, range determination, section connection processing, etc. do not become a load on the computer 15 during measurement, and Accurate height information can be obtained immediately without reducing the inspection speed, drawing speed, etc., absorbing variations. Further, by repeatedly scanning the Z stage 14 in synchronization with the two-dimensional scanning, it is possible to directly display three-dimensional data on a monitor in synchronization with the scanning.

As described above, according to the height measuring apparatus of the present embodiment, the accuracy of the height measurement of the sample 9 can be increased, and at the same time, the number of movements of the Z stage 14 can be reduced to speed up the measurement. be able to. In addition, the influence of the reflectivity of the sample 9 is not required, and the load on the control device can be reduced, the responsiveness can be improved, and the effective measurement range can be extended.

FIG. 19 shows the basic configuration of a confocal scanning microscope used in each of the sixth and seventh embodiments of the present invention. The basic configuration of the confocal scanning microscope used in each of these examples is

This is the same as the configuration of the conventional confocal scanning microscope shown in FIG. Therefore, description of the basic configuration and operation is omitted. The height measuring device of each embodiment is characterized by the configuration of the height calculating means 15a and the luminance calculating means 15b provided in the computer 15 of the confocal scanning microscope.

Sixth embodiment

In the sixth embodiment, the previously calculated I-Z curve is shifted by an interval d as shown in FIG. 2OA, and the difference / Information obtained by calculating the sum (I−I ′) / (I + I ′) is stored. Next, as shown in FIG. 8, two confocal images are obtained by positioning the Z stage 14 at the focal positions Za and Zb spaced apart so as to sandwich the surface 9 s of the sample 9. . At this time, the height calculator 15a calculates the difference / point for each point of the sample from the output Ia, lb of the photodetector 12 when the Z stage 14 is positioned at the focal position Za, Zb. Calculate the sum signal (Ia-Ib) / (Ia + Ib). Then, as shown in FIG. 20C, Z for each point, that is, the height of the sample 9 is obtained.

Next, the brightness calculating means 15b calculates the relative height ΔZa between the obtained height of the sample 9 and one of the focal positions Za and Zb, for example, the focal position Za. . Furthermore, as shown in FIG. 21, an I_Z curve with normalized luminance is stored in advance, and the relative height ΔZa is substituted into this I−Z curve to perform scaling. i a is required. Therefore, the peak value of the actual luminance of the sample 9 can be obtained by I _PEAK == 1 XIa / ia.

Here, the I-Z curve is expressed by the following equation (1) according to, for example, “TR. Corle, GS Kino,“ Confocal Scanning Optical Microscopy and Related Imaging Systems ”ACADEMICPRESS 1996”. This can be used as a theoretical value.

However,

- ² ¾

": Refractive index

-"sinfl: number of ports Also, if a flat mirror is used as the sample 9 and the Z stage 14 is moved by a very small amount to acquire a confocal image, the objective lens etc. which constitute the height measuring device can be obtained. Since the actual measured value of the I-Z curve can be obtained for each combination of, it is possible to eliminate the influence such as aberration.

Seventh embodiment

In the seventh embodiment, the luminance calculation means 15b in the sixth embodiment is provided with a look-up table. The lookup table is created from theoretical values or measured values, and stores table data so that one luminance value is selected for one combination of (ΔΖ, I). According to this, the luminance calculating means 15b can instantaneously obtain the actual luminance peak value via the look-up table by obtaining (ΔΖ, I).

Modified example

In the above description, the basic configuration of the confocal scanning microscope constituting the height measuring device of the present invention is shown in FIG. 1. However, the height measuring device of the present invention is not limited to this, and various types of confocal scanning can be used. It can be applied to a type microscope.

For example, the focused light from the objective lens 8 is relatively scanned along the surface of the sample 9. An XY stage that moves the sample 9 in a plane perpendicular to the optical axis may be used as the scanning mechanism. Further, a configuration may be adopted in which a Nipkow disk having a plurality of minute openings spirally formed on a disk is rotated at a low speed. At this time, the Nipkow disk also serves as a minute aperture arranged at a position conjugate to the condensing position of the objective lens, and a two-dimensional image sensor such as a CCD is used as a photodetector. Further, instead of the two-dimensional optical scanning mechanism, a configuration may be employed in which the focused light of the objective lens is scanned on one line of the sample by a one-dimensional optical scanner to measure the cross-sectional shape of the sample.

Further, a mechanism for moving the objective lens 8 in place of the Z stage 14 for moving the position of the sample 9 may be used as a moving mechanism for relatively moving the focus position of the objective lens 8 and the position of the sample 9. . In addition, the present invention is not limited to the above configuration, and can be applied to various confocal microscopes.

In the above-described embodiment, the pinhole is disposed as a member having a minute opening at a position conjugate with the condensing position of the objective lens, and light passing through the pinhole is detected by the detector. However, the micro-apertures arranged at conjugate positions can be micro-apertures made of a material having a reflection characteristic such as a mirror at a portion corresponding to the hole, in addition to the hole through which light passes.

Eighth embodiment

FIG. 22 is a flowchart showing a calculation procedure in the parameter setting method according to the eighth embodiment of the present invention. In the parameter setting method according to the present embodiment, measurement accuracy is obtained according to a procedure as shown in FIG. 22, and an interval between the focal position Za and the focal position Zb is set based on the measurement accuracy.

Specifically, first, on the surface of a highly reflective sample such as a mirror, obtain the I-Z curve Ia (Z) as the first curve of the objective lens used for measurement (step S1) _c The calculated I—Z curve I a (Z) is shifted in the height direction Z by a certain amount A in the computer calculation (step S 4), and the I—Z curve lb (Z) = I a (Z + A) is calculated (step S5). Next, perform the operation {la (Z)-I a (Z + A)} / {la (Z) + I a (Z + A)} to find the difference Z sum of those I-Z curves. A height curve is calculated as the second curve (step S6). Next, an approximation expression (primary expression) of the height curve is derived using a least square method or the like (step S7). After deriving the approximate expression of the height curve, the linearity of the height curve is determined (step S8). As an example of this judgment, the square sum of the error between the height curve and the approximation formula of the height curve becomes a significantly large value (a value that affects the measurement accuracy) near the midpoint between Za and Zb. Is determined based on whether the Here, if the sum of the squares of the error between the height curve and the approximation formula of the height curve is large, the linearity is deteriorated. Therefore, the shift amount at this time is inappropriate, and the steps S9 and S10 described later The processing of step S11 described below is performed without performing the processing of.

Here, the wider the linear portion of the difference Z sum signal, the wider the measurement range of the sample height. At this time, the relationship between the height of the sample 9 and the output of the photodetector 12 is as shown in FIG. 9A, and the difference / sum signal is as shown in FIG. 9B.

Also, as the slope of the linear portion of the difference Z sum signal increases, the change of the difference / sum signal with respect to the sample height increases, the sensitivity of sample height detection increases, and highly accurate measurement can be performed. At this time, the relationship between the height of the sample 9 and the output of the photodetector 12 is as shown in FIG. 10A, and the difference / sum signal is as shown in FIG. 10B.

Next, it is determined whether or not the slope of the approximate expression is larger than the slope a that satisfies the minimum required accuracy (step S9). Prior to this determination, a tilt value _a that can derive the minimum required accuracy is set in advance for each type of objective lens. If the gradient of the approximate expression is larger than the gradient a that satisfies the minimum required accuracy, the shift amount A at that time and the gradient of the approximate expression are stored in the memory (step S10). Next, it is determined whether the slope of the approximation formula is not too small for the measurement accuracy, that is, larger than the maximum slope value b that can be measured with higher accuracy and higher speed than the height measurement in the prior art. I do. Prior to this determination, the tilt value b is set in advance for each type of objective lens. If the slope of the approximation formula is smaller than the slope b, the I-Z curve I b ₁ (Z) is obtained by shifting the I-Z force Ia (Z) in the height direction Z by a certain amount A _{+ 1.} A height curve is calculated from the difference sum of Ia (Z + A _{+ 1} ) (steps S3 to S6), and similarly, the linearity of the height curve and the slope of the approximate expression of the height curve are determined. This is repeated, and if the slope of the approximate expression is larger than the slope b, the calculation is terminated.

Finally, select the measurement accuracy required for the measurement (step S1 2), and calculate the Judging from the slope of the approximate expression of the height curve (step S13), the optimum interval between Za and Zb can be set (step S14).

At this time, it is desirable that the relationship between the slope of the approximate expression and the measurement accuracy is defined in advance for each type of objective lens, and the measurement accuracy is determined by a computer.

It is also desirable that the shift amount A of the I-Z curve be defined for each type of objective lens. '

In a microscope equipped with the parameter setting method of the present embodiment having such a calculation procedure, the surface 9 s of the sample 9 is sandwiched as shown in FIGS. In the stage 14, the interval between Za and Zb is set to a value optimized for the measurement conditions as described above, and a confocal image is obtained. As shown in FIG. 9A, the relationship between the height of the sample 9 and the output of the photodetector 12 at this time is an I-Z curve la (Z), lb with the focal positions Za and Zb as the center positions, respectively. (Z).

Here, the difference / sum signal (la-Ib) / (Ia + Ib) is calculated with the outputs of the photodetectors 12 when the Z stage 14 is positioned at Za and Zb as Ia and Ib. Then, a relationship as shown in FIG. 9B is obtained at each height of the sample 9. As shown in Fig. 9B, the difference Z sum of the outputs of the photodetectors 12 is 0 at the middle point between the Za position and the Zb position, and a value that is almost proportional to the sample height is obtained in the vicinity. . Therefore, the height can be obtained by multiplying the difference Z sum signal by the slope of the approximate expression of the height curve.

According to the parameter setting method of the present embodiment, the interval between Za and Zb can be set according to the measurement accuracy required for height measurement.

Ninth embodiment

FIG. 23 is a flowchart showing a calculation procedure in the parameter setting method according to the ninth embodiment of the present invention. In the parameter setting method of the present embodiment, the interval between the focal position Za and the focal position Zb is set from the measurement range (measurement speed) according to the procedure shown in FIG.

Specifically, first, an I-Z curve Ia (Z) is obtained as the first curve of the objective lens used for measurement on the surface of a sample having a high reflectance such as a mirror (step S15). Next, the obtained I-Z force Ia (Z) is shifted in the height direction Z by a certain amount A in the computer calculation (step S18), and the I-Z curve lb (Z ) = Calculate I a (Z + A) (step S 19). Next, the operation {la (Z) ~ I a (Z + A)} / {la (Z) + 1 a (Z + A)} to calculate the difference / sum of those I-Z curves A height curve is calculated as a curve (step S20). Next, an approximate expression (linear expression) of the height curve is derived using a least squares method or the like (step S21). After deriving the approximate expression of the height curve, first, the linearity of the height curve is determined (step S22). As an example of this determination, the square sum of the error between the height curve and the approximation formula of the height curve is a remarkably large value (a value that affects the measurement accuracy) near the midpoint between Za and Zb. It is determined by whether or not there is. Here, if the sum of the squares of the error between the height curve and the approximation formula of the height curve is large, the linearity is deteriorated, so that the shift amount at this time is inappropriate, and the following steps S23 to S25 The processing in step S26 described below is performed without performing the processing.

Here, the wider the linear portion of the difference Z sum signal, the wider the measurement range of the sample height. The relationship between the height of the sample 9 and the output of the photodetector 12 at this time is as shown in FIG. 9A, and the difference / sum signal is as shown in FIG. 9B.

Also, as the slope of the linear portion of the difference Z sum signal increases, the change of the difference Z sum signal with respect to the sample height increases, the sensitivity of sample height detection increases, and highly accurate measurement can be performed. The relationship between the height of the sample 9 and the output of the photodetector 12 at this time is as shown in FIG. 1OA, and the difference Z sum signal is as shown in FIG. 10B.

Next, the measurement range will be considered. Here, the measurement range is a straight line portion of the height curve, that is, a range in which the height curve and the approximate expression of the height curve substantially match. Therefore, the height range of the height curve where the square of the error between the height curve and the approximate expression of the height curve does not affect the accuracy is calculated (step S23). This is set as a measurement range in calculation. Then, it is determined whether or not the calculated measurement range is smaller than the measurement range c that satisfies the minimum required accuracy (step S24). Prior to this determination, a measurement range c that satisfies the minimum required accuracy is set in advance for each type of objective lens. If the calculated measurement range is smaller than the measurement range, the shift amount, the inclination of the approximate expression and the measurement range are stored in the memory (step S25).

Next, the calculated measurement range is not too small for the accuracy, that is, higher than the height measurement in the prior art. It is determined whether or not is also wide (step S26). Prior to this determination, the measurement range d is set in advance for each type of objective lens.

If the calculated measurement range is wider than the measurement range d, the I—Z curve la (Z) is shifted by a certain amount A _{+1 in the} height direction Z in the height direction Z. A length curve is calculated from the difference / sum of Z) = Ia (Z + A _{+ 1} ) (steps S17 to S20), and the linearity of the height curve and the measurement range are similarly determined. This operation is repeated, and if the calculated measurement range is smaller than the measurement range d, the calculation ends.

Finally, select the measurement speed required for measurement (step S27), judge from the measurement range obtained from the height curve previously calculated (step S28), and determine the optimal Za and Zb. The interval can be set (step S29).

At this time, it is desirable that the relationship between the measurement range and the measurement speed is defined in advance for each type of objective lens, and the measurement speed is determined by a computer. It is also desirable to define the shift amount A of the I-Z carp for each type of objective lens. In a microscope equipped with the parameter setting method of the present embodiment having such a calculation procedure, the surface 9 s of the sample 9 is sandwiched as shown in FIGS. In the stage 14, the confocal image is obtained by setting the interval between Za and Zb to a value optimized for the measurement conditions as described above. As shown in FIG. 9A, the relationship between the height of the sample 9 and the output of the photodetector 12 at this time is an I-Z curve la (Z), where the focal positions Za and Zb are the center positions, respectively. lb (Z).

Here, assuming that the outputs of the photodetectors 12 when the Z stage 14 is positioned at Za and Zb are Ia and Ib, the difference sum signal (la—Ib) / (Ia + Ib) is calculated. Then, a relationship as shown in FIG. 9B is obtained at each height of the sample 9. Therefore, the height can be obtained by multiplying the difference / sum signal by the slope of the approximate expression of the height curve. According to the parameter setting method of the present embodiment, the interval between Za and Zb can be set according to the measurement speed (measurement range) required for height measurement.

10th embodiment

FIG. 24 is a flowchart showing a calculation procedure in the parameter setting method according to the tenth embodiment of the present invention. In the parameter setting method of this embodiment, the focal position Za and the focus position are determined from the measurement accuracy and the measurement range (measurement speed) according to the procedure shown in FIG. Set the distance from the point position Zb.

Specifically, first, on the surface of a sample having a high reflectivity such as a mirror, an I_Z force ¹ "group Ia (Z) is acquired as a first curve of an objective lens used for measurement (step S30). Next, the obtained I-Z curve I a (Z) is shifted in the height direction Z by a certain amount A by calculation in the computer (step S33), and the I-Z curve I b ( Z) = I a (Z + A) is calculated (step S34) Next, the operation for calculating the sum of the differences of the I—Z curves {la (Z) −I a (Z + A)} / Perform {la (Z) + I a (Z + A)} to calculate the height curve as the second curve (step S 35) Next, the approximate expression (primary expression) of this height curve is (Step S36) After deriving the approximate expression of the height curve, first determine the linearity of the height curve (Step S37). High near the midpoint between Za and Zb Judgment is made based on whether or not the sum of the squares of the difference between the height curve and the approximation formula of the height curve is a remarkably large value (a value that affects measurement accuracy). If the sum of the squares of the error from the approximation formula is large, the linearity will be poor, so the shift amount at this time is inappropriate, and the processing in steps S38 to S40 described below is skipped and the processing in step S Perform the process of 41.

Here, the wider the linear portion of the difference sum signal, the wider the measurement range of the sample height. The relationship between the height of the sample 9 and the output of the photodetector 12 at this time is as shown in FIG. 9A, and the difference sum signal is as shown in FIG. 9B.

Also, as the slope of the linear portion of the difference / sum signal is greater, the change of the difference Z sum signal with respect to the sample height is greater, the sensitivity of sample height detection is higher, and highly accurate measurement can be performed. The relationship between the height of the sample 9 and the output of the photodetector 12 at this time is as shown in FIG. 1OA, and the difference / sum signal is as shown in FIG. 10B.

Next, it is determined whether or not the slope of the approximate expression satisfies the slope a that satisfies the minimum required accuracy (step S38). Prior to this determination, the slope value a that can derive the minimum required accuracy is set in advance for each type of objective lens, and the slope of the approximate expression is calculated from the slope a that satisfies the minimum required accuracy. If is also large, then consider the measurement range, and the square of the error between the height curve and the approximation does not affect the accuracy. The height range of the height curve having the maximum value is calculated (step S39). This is the measurement range for calculation. Then, the shift amount satisfying the condition, the slope of the approximate expression, and the calculated measurement range are stored in the memory (Step S40).

Next, it is determined whether or not the calculated measurement range is not too small for the accuracy, that is, whether the calculated measurement range is wider than the minimum measurement range d that can be measured with higher accuracy and higher speed than the height measurement in the prior art ( Step S 41). Prior to this determination, the measurement range d is set in advance for each type of objective lens.

If the calculated measurement range is wider than the measurement range d, I-Z curve I b (Z) I—Z curve la (Z) shifted by a certain amount A _{+1 in the} height direction Z A height curve is calculated from the difference Z sum of a (Z + A _{+ 1} ) (steps S31 to S35), and similarly, the linearity of the height curve and the slope of the approximate expression are determined. This operation is repeated, and if the calculated measurement range is smaller than the measurement range d, the calculation is terminated.

Finally, select the measurement accuracy and measurement speed required for measurement (step S42), and judge from the slope of the approximation formula of the height curve calculated previously and the measurement range obtained from the height curve (step S42). 43), the optimum distance between Za and Zb can be set (step S44).

At that time, the relationship between the measurement accuracy and the measurement speed is inversely proportional as shown in FIG. The relationship is different for each objective lens, and such a graph is plotted on a computer by shifting the I-Z curve to obtain a balance between measurement accuracy and measurement speed required by the operator. Can be selected.

→ In addition, it is desirable that the shift amount A of the I-Z curve is defined for each type of objective lens.

In a microscope equipped with the parameter setting method of the present embodiment having such a calculation procedure, the surface 9 s of the sample 9 is sandwiched as shown in FIGS. In the stage 14, the interval between Za and Zb is set to a value optimized for the measurement conditions as described above, and a confocal image is obtained. As shown in FIG. 9A, the relationship between the height of the sample 9 and the output of the photodetector 12 at this time is, as shown in FIG. 9A, the I-Z curves la (Z), lb (Z).

Here, the output of the photodetector 12 when the Z stage 14 is positioned at Za and Zb When the difference / sum signal (la-lb) (Ia + Ib) is calculated with the values of Ia and Ib, the relationship shown in FIG. 9B at each height of the sample 9 is obtained. Therefore, the height can be obtained by multiplying the difference sum signal by the slope of the approximate expression of the height curve.

According to the parameter setting method of the present embodiment, the interval between Za and Zb can be set according to the measurement speed (measurement range) and measurement accuracy required for height measurement. In the eighth to tenth embodiments, it is desirable that the calculation is automatically performed using a computer. In the eighth to tenth embodiments, it is desirable that the approximate expression of the height curve approximates only the straight line portion of the height curve.

Modified example

In the eighth to tenth embodiments, the confocal scanning microscope to which the parameter setting method of the present invention is applied has a configuration as shown in FIG. 1, but is not limited thereto and various confocal scanning microscopes are used. Can be applied to

For example, an XY stage that moves the sample 9 in a plane perpendicular to the optical axis may be used as a scanning mechanism that relatively scans the focused light by the objective lens 8 along the surface of the sample 9. Further, a configuration may be employed in which a Nip kow disk having a plurality of minute openings spirally formed on a disk is rotated at a high speed. At this time, the Nipkow disk also serves as a minute aperture arranged at a position conjugate to the condensing position of the objective lens, and a two-dimensional image sensor such as a CCD is used as a light detector. Further, instead of the two-dimensional optical scanning mechanism, a configuration may be employed in which the focused light of the objective lens is scanned on one line of the sample by a one-dimensional optical scanner to measure the cross-sectional shape of the sample.

In addition, a moving mechanism that relatively moves the focusing position of the objective lens 8 and the position of the sample 9 also includes a mechanism that moves the objective lens 8 instead of the Z stage 14 that moves the position of the sample 9. May be used. In addition, the present invention is not limited to the above configuration, and can be applied to various confocal microscopes.

In the measurement parameter setting method of the embodiment shown in FIGS. 22 to 24, the selection of the balance between the measurement accuracy and the measurement speed is performed after the calculation of the height curve. ) May be performed prior to the calculation, or the result may be output immediately after the approximate expression of the height curve satisfying the input condition is calculated.

In each of the above embodiments, the acquisition of the I_Z curve la (Z) is performed by using a mirror or the like. Although the measurement was performed with a high reflectivity, the measurement may be performed with the sample 9. Further, it is desirable that the values of a, b, c, and d used in the above embodiment have a margin more than the values at the boundaries. In each of the above embodiments, the shift amount of the I-Z curve la (Z) and the I-Z curve lb (Z) was changed from a small value to a large value, but the shift amount was changed from a large value to a small value. May be.

Further, in each of the above embodiments, as shown in FIGS. 5A to 5C, the interval between Za and Zb was optimized so as to sandwich the surface 9 s of the sample 9. this height may be applied to the measurement according to the measurement _c in sample 9 with O UNA relatively large irregularities indicating time, the optimal Z _k and Z _{k + i} in the same manner as in the measurement conditions and the above-described embodiments the distance set so as to satisfy, to obtain a focused image by sequentially positioned from the Z stage 1 4 to Z _n. Here, the output of the photodetector 12 when the Z stage 14 is positioned at Z _k , Z _{k +} ; is _defined as I _k , I _{k + i} , and the difference Z sum signal (I _{k + i} _ I _k ) / (I _{k + When i} + I _k ) is calculated, a relationship as shown in FIG. 27A is obtained at each height of the sample 9. The difference Z sum of the outputs of the optical detectors 1 2 as shown in FIG. 2 7 B becomes zero at the midpoint of the Z _k and Z _{k +} i, substantially proportional to the sample height in the vicinity. Therefore, the height of the sample 9 can be obtained by multiplying the difference Z sum signal by the slope of the approximate expression of the height curve and adding the average value of Z _k and Z _{k + i} . Here the interval between the Z _k and Z _{k + i,} as shown in FIG. 26 B, intersect the measurement range of the Z _k, the measurement range of the Z _k _{+ i} and _{_{Z k + 1, Z k +}} 1 + i Must be set as follows.

In addition, the approximation formula of the height curve has been linear expression so far, but the approximation formula is not limited to the linear expression, but may be approximated by an n-order expression. In this case, the measurement range is not limited to the linear portion of the height curve. However Shi because accuracy is lowered in the curved portion, that apply a ToTadashi when multiplied to the result of the difference between the sum of Z _a and Z _b as coefficients desirable.

Claims

The scope of the claims

1. An objective lens that focuses light from the light source on the sample,

A moving mechanism that relatively moves a condensing position of the objective lens and a position of the sample along the optical axis direction of the focused light in the optical axis direction;

A height measuring device comprising: a small aperture member disposed at a position conjugate to a condensing position of the objective lens; and a photodetector for detecting an intensity of light passing through the small aperture member.

A height measuring function for obtaining outputs of two photodetectors by changing a focusing position of the objective lens and a relative position of the sample, and obtaining height information of each point of the sample. Height measuring device.

2. The height measuring device according to claim 1, wherein the height measuring device is a confocal scanning microscope having a scanning mechanism for relatively scanning the focused light along a sample surface. .

3. For each corresponding pixel, the height difference at each point of the sample is obtained by dividing the output difference of the photodetector by the sum of the outputs of the photodetectors and substituting it into an appropriate polynomial. The height device according to claim 1, wherein

4. Two images captured by changing the focusing position of the objective lens and the relative position of the sample, including a recording medium on which a computer has recorded a control program for controlling the height measurement of the confocal microscope The height information of each point of the sample is obtained by dividing the corresponding difference of each pixel by the sum of each pixel from the confocal image of the above and substituting it into an appropriate polynomial. The height measuring device according to item 1.

5. An objective lens that focuses light from the light source on the sample,

A scanning mechanism for relatively scanning the focused light along the sample surface,

A moving mechanism for relatively moving the focus position of the objective lens and the position of the sample along the optical axis of the focused light in the optical axis direction;

A micro-aperture member arranged at a position conjugate with the focusing position of the objective lens,

A method for measuring the height of a sample, comprising: a photodetector for detecting the intensity of light passing through the minute aperture member; A method for measuring the height of a sample, which acquires the output of two photodetectors by changing the focusing position of the objective lens and the relative position of the sample, and obtains height information for each point of the sample.

6. The method according to claim 5, wherein the polynomial for obtaining the height information is a linear expression.

7. To get the equation to be substituted into the linear equation,

The difference between the converging position of the objective lens and the relative position of the sample in the two confocal images is 0.3 to 2 times the full width at half maximum of the relative position-one photodetector output signal intensity curve. 7. The method for measuring the height of a sample according to claim 6, wherein:

8. A plurality of confocal images are taken by sequentially changing the focus position of the objective lens and the relative position of the sample by a fixed amount of movement, and the difference between the focus position of the two objective lenses and the relative position of the sample is calculated. A request for obtaining height information of each point of a sample according to an output of a photodetector for each corresponding pixel between two confocal images in which a shift amount is an integral multiple of the movement amount. Item 6. The method for measuring the height of a sample according to Item 5.

9. Calculate the difference Z sum of the outputs of the photodetectors, substitute the calculated value into a predetermined polynomial, obtain the outputs of the two photodetectors, and obtain the outputs of the photodetectors for each corresponding pixel. 9. The method for measuring the height of a sample according to claim 8, wherein the difference / sum of the outputs is calculated, and the height information of each point of the sample is obtained by substituting the calculated value into a predetermined polynomial.

10. The method according to claim 8, wherein the movement amount is a shift amount for obtaining the two confocal images.

11. The method according to claim 10, wherein the amount of movement is 0.3 to 0.8 times the full width at half maximum of the relative position-one photodetector output signal intensity curve. Law.

12. A storage device for storing a signal from the photodetector as image data, a plurality of input terminals, and at least one output terminal, and a predetermined value is input to a plurality of inputs from these input terminals. An arithmetic unit having a lookup table for outputting,

A step in which the arithmetic unit acquires a plurality of image data by changing a focusing position of the objective lens and a relative position of the predetermined position;

Of the plurality of image data obtained above, two Inputting the image data at one of the light-collecting positions to the look-up table via the storage device, and directly inputting the image data at the other light-collecting position to the look-up table. The height measuring device according to claim 1, wherein:

1 3. The minimum value of the image data and A _{mi n,} the maximum value A _max, the minimum value B _{mi n} of the image data in the second collection point, the maximum value B _{ma x} at the first collection point M data from the minimum value A _m to the maximum value A _max , the minimum value B _m ! If the there are n data between the _n to the maximum value B _{ma x,} the look-up table, at least the following data C (i, j) according to claim 1 2, characterized in that it has a Height measuring device.

C (i, j) = (B j -A i) / (B j + A i)

Here, i = 1, 2, 3, 3, m, and j = 1, 2, 3,…, n, where m and n are integers. _{_{Also, A mi n A i ≤A ma}} x, a _{_{B mi n ≤B j ≤B ma x}} . '

14. The arithmetic unit inputs the image data at the other light-collecting position to the look-up table via the storage device, and outputs the image data at a position adjacent to the other light-collecting position and the one light-collecting position. Directly inputting image data at different light condensing positions into the look-up table,

A step of adding a distance from the one light-collecting position to the other light-collecting position to an output from the lookup table in the process. The height measuring device as described.

15. The height measuring apparatus according to claim 13, wherein the lookup table has a threshold value indicating a predetermined range, and outputs C (i, j) only when the value falls within the predetermined range. .

16. The height measuring apparatus according to claim 13, wherein a predetermined correction is applied to the data C (i, j).

17. The height measuring device according to claim 15, wherein the arithmetic device includes a step of changing the predetermined range.

18. The height measuring apparatus according to claim 13, wherein the look-up table outputs range information when C (i, j) is outside the predetermined range.

1 9. Two confocal images are captured by changing the focusing position of the objective lens and the relative position of the sample, and the output of the photodetector is output for each pixel corresponding to each confocal image. Height information calculating means for calculating a sum of differences or a division value and obtaining height information at each point of the sample by performing an appropriate scaling; and

A luminance calculating means for obtaining a luminance value at the in-focus position of each point of the sample based on the height information obtained by the height information calculating means, the output of the photodetector, and the "luminance-one focus position" characteristic; The height measuring device according to claim 1, wherein

20. The height measuring apparatus according to claim 19, wherein the luminance calculating means uses a theoretical value of a “luminance-focus position” characteristic.

21. The height measuring apparatus according to claim 19, wherein the luminance calculating means uses an actual measurement value of a “luminance-focus position” characteristic.

22. The brightness calculating means calculates the data of each point from the height information at each point obtained by the height information calculating means and the height information at one of the two acquired confocal images. 2. The luminance at each in-focus position of each sample point is obtained by using a dividing means for obtaining a focus amount and a lookup table capable of selecting the defocus amount and luminance data corresponding to the defocus amount. 22. The height measuring device according to any one of 9 to 21.

23. The height measuring device according to claim 22, wherein the defocus amount of each point is obtained from height information of a position having a larger luminance at each point of the two confocal images.

24. A curve represented by coordinate axes of a first axis indicating a relative position and a second axis orthogonal to the first axis and indicating a light intensity signal, the first curve being obtained in advance. Moving I (Z) by a predetermined amount A along the first axis;

Using the first curve I (Z) before the movement by the predetermined amount A and the first curve I (Z + A) after the movement, an operation {I (Z) -I (Z + A)} / {I ( Z) + I (Z + A)} to obtain a second curve,

Evaluating the second curve under predetermined conditions,

A parameter setting method, wherein the above-described steps are performed by changing the value of the predetermined amount A to obtain the desired movement amount A.

25. The first curve I (Z) includes an objective lens for condensing light from a light source at a predetermined position, a minute aperture disposed at a position conjugate to the predetermined light condensing position, A light detector that detects the intensity of light passing through the small aperture, wherein a relative movement amount when a distance between the objective lens and the sample is moved along the optical axis direction near the light collection position. 26. The parameter setting method according to claim 24, wherein the parameter setting method is obtained based on an output from the photodetector at each relative position.

26. The parameter setting method according to claim 24, wherein the predetermined condition is selectable according to a measurement condition.

27. The parameter setting method according to claim 26, wherein the measurement conditions are a type of an objective lens, a required measurement speed and a measurement accuracy, and a measurement sample.

28. The parameter setting method according to claim 24, wherein the predetermined condition is a linearity of the second curve, and a step of determining the linearity is provided. .

29. The method according to claim 29, wherein the predetermined condition is a gradient of an approximate expression when the second curve is approximated by a linear expression, and the method includes a step of determining a gradient of the approximate expression. Parameter setting method according to claim 24 or 25.

30. The method according to claim 29, wherein the predetermined condition is a range in which the second curve and the approximation formula are substantially coincident with each other, and further comprising a step of determining the coincident range. Parameter setting method described.

31. The parameter setting method according to claim 24 or 25, further comprising a step of obtaining a plurality of second curves by sequentially changing the movement amount. '