JP2008046361A - Optical system and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical system achieving rapid observation by a confocal optical system. <P>SOLUTION: The optical system 1 includes: the confocal optical system 3 to radiate illuminating light emitted from an illuminating light source 21 to a specimen 8 through a confocal minute aperture 34a so as to obtain passing light reflected by the specimen and passing through the confocal minute aperture 34a; a photodetector part 41 to detect the passing light; a displacement part 5 to displace the focal position of the confocal optical system to the specimen in an optical axis direction; and a processing part 60 to read and process detection data from the photodetector part 41 at a plurality of positions obtained by displacing the focal position. The optical system 1 is constituted so that the processing part may adjust the intensity of the light radiated to the specimen 8 based on the detection data read at the plurality of positions. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical system including an illumination light source, a confocal optical system, and an imaging device that captures a confocal image obtained in the confocal optical system, and a method for controlling the optical system.

  As an optical system including a confocal optical system and an imaging device, for example, inspection of a confocal microscope or an area height measuring device for inspecting a fine pattern of a semiconductor wafer substrate, an integrated element (IC), a liquid crystal display panel, etc. There is a device. The confocal optical system used in these inspection apparatuses irradiates the object with illumination light through the confocal microscopic aperture, and reflects the reflected light (point image) from the test object again through the confocal microscopic aperture. Pass through and observe. When the focal position of the confocal optical system is set near the surface of the specimen and the focal position is relatively displaced in the direction of the optical axis, the reflected light that passes through the confocal micro-aperture out of the reflected light from the specimen The intensity of the passing light becomes maximum when the intensity of the passing light (hereinafter referred to as passing light) increases and decreases and the focal position coincides with the surface of the test object. Therefore, it is possible to measure the height and shape of each part of the test object by detecting the height position when the intensity of the transmitted light detected by the light detection part is maximized.

  With respect to such an inspection apparatus, in order to perform efficient measurement, two-dimensional imaging elements (light detection units) are used for passing light while displacing the height position of the focal plane with respect to the test object at predetermined intervals in the optical axis direction. An apparatus using a method of reading the image data by reading the image data and calculating the height position where the intensity of the reflected light is maximum from the data of discrete luminance signals detected at each pixel of the image sensor by interpolation processing. It is known (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 9-126739

  However, the apparatus using the measurement method as described above has the light receiving intensity of the image sensor (the luminance output from the image sensor) in a state where the focal position of the confocal optical system coincides with the surface (object surface) of the test object. Signal) is a necessary and sufficient value that can be processed, and is not saturated. However, on the characteristic of the confocal optical system that the reflected light is detected when the focal position is close to the surface of the test object, and the received light intensity becomes maximum when the focal position matches the test object surface, The received light intensity was unknown until the focus position was adjusted to the surface of the test object, and it was necessary to manually move the focus position to the test object before optimizing the height scan to optimize the illumination intensity. .

  In particular, when there are two or more parts with different height positions and different surface reflectivities in the field of view, the part with low reflectivity is adjusted when the brightness is adjusted so that the saturation intensity is high in the part with high reflectivity. However, if the illumination illuminance is adjusted according to the part with low reflectivity, the output of the light receiving element will be saturated at the part with high reflectivity. In addition, there is a problem that it is difficult to adjust the illuminance of the illumination light source. As a countermeasure to such a conventional technique, a method of manually sampling a plurality of parts to be measured and setting an illumination condition while viewing image data of each part is generally performed. However, there is a problem that it takes time to acquire a confocal image.

  The present invention has been made in view of the circumstances as described above, and an object thereof is to provide an optical system capable of promptly performing observation with a confocal optical system.

  In order to achieve the above object, the invention according to claim 1 is an optical system that irradiates an object to be examined with an illumination light source that emits illumination light and illumination light emitted from the illumination light source through a confocal microscopic aperture. A confocal optical system that obtains passing light reflected by the test object and passed through the confocal micro-aperture, a light detection unit that detects the passing light obtained in the confocal optical system, and confocal optics for the test object A displacement unit that displaces the focal position of the system in the optical axis direction, and a processing unit that reads and processes the detection data from the light detection unit at a plurality of positions in which the focal position is displaced by the displacement unit. Based on the detection data read at the position, the intensity of the light applied to the test object is adjusted.

  According to a second aspect of the present invention, in the optical system of the first aspect, the processing unit detects the light intensity of the passing light detected by the light detection unit and the saturated light intensity of the light detection unit from the detection data read at a plurality of positions. And the intensity of light applied to the test object is adjusted based on the comparison result.

  According to a third aspect of the present invention, in the optical system of the first aspect, the processing unit emits light when the surface of the test object and the focal position of the confocal optical system coincide from the detection data read at a plurality of positions. The maximum intensity of the passing light to be detected by the detection unit is calculated by interpolation processing, and the intensity of the light irradiated to the test object is adjusted according to the calculated maximum intensity.

  According to a fourth aspect of the present invention, in the optical system according to any one of the first to third aspects, the processing unit adjusts the intensity of light applied to the test object, and then displaces the focal position by the displacement unit. Thus, the detection data is read from the light detection unit at a plurality of positions, and the height information of each part of the test object is acquired.

  The invention according to claim 5 is a method for controlling an optical system, wherein an illumination light source that emits illumination light and illumination light emitted from the illumination light source is irradiated to the test object through a confocal microscopic aperture. The confocal optical system that obtains the passing light reflected by the confocal micro aperture, the light detection unit that detects the passing light obtained by the confocal optical system, and the focal position of the confocal optical system with respect to the test object A control method for an optical system, comprising: a displacement unit that displaces the optical axis in a direction of the optical axis; and a processing unit that displaces a focal position by the displacement unit and reads detection data from the light detection unit and processes the data. Illumination light is emitted with the light intensity of, and the processing unit reads the detection data from the light detection unit at a plurality of positions where the focal position of the confocal optical system is displaced in the optical axis direction by the displacement unit, and reads at the plurality of positions. Based on detected data There are, configured to adjust the intensity of light applied to the specimen.

  According to a sixth aspect of the present invention, in the optical system control method of the fifth aspect, the processing unit is configured to detect the light intensity of the passing light photographed by the light detection unit and the light detection unit from the detection data read at a plurality of positions. The saturation light intensity is compared, and the intensity of light irradiated to the test object is adjusted based on the comparison result. The processing unit interpolates the light intensity of the reflected light that should be detected by the light detection unit when the surface of the test object and the focal position of the confocal optical system coincide from the detection data read at a plurality of positions. The intensity of the light irradiated to the test object is adjusted according to the calculated light intensity.

The invention according to claim 7 is the method of controlling an optical system according to claim 5, wherein the processing unit is
From the detection data read at multiple positions, the light intensity of the reflected light to be detected by the light detection unit when the surface of the test object matches the focal position of the confocal optical system is calculated by interpolation. According to the calculated light intensity, the intensity of the light irradiated to the test object is adjusted.

  According to an eighth aspect of the present invention, in the method for controlling an optical system according to any one of the fifth to seventh aspects, the processing unit adjusts the intensity of light applied to the test object, and then shifts. The detection information of the passing light detected by the light detection unit at a plurality of positions whose focal positions are displaced by the unit is read to obtain the height information of the test object.

  ADVANTAGE OF THE INVENTION According to this invention, the control method of the optical system which can perform observation by a confocal optical system rapidly, and an optical system can be provided.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. As an example of an optical system to which the present invention is applied, FIG. 1 shows a schematic configuration of an inspection apparatus 1 that observes the fine shape of the surface of an object. First, the configuration of the inspection apparatus 1 will be described.

  The inspection apparatus 1 includes an illumination optical system 2, a confocal optical system 3 that obtains a confocal image of the object 8, an imaging apparatus 4 that captures an image (confocal image) obtained by the confocal optical system 3, A displacement mechanism (displacement unit) 5 that includes a stage drive unit 52 that drives the stage 7 on which the test object 8 is mounted to move up and down, and that relatively displaces the focal position of the confocal optical system 3 in the optical axis direction; And a control device 6 that controls the operation of each unit.

  The illumination optical system 2 is located on the side of the confocal optical system 3 and includes a condenser lens 22 and an illumination light source 21 on an optical axis extending laterally from the polarization beam splitter 23. For example, a halogen lamp or a xenon lamp is used as the illumination light source 21, and the luminance (light emission intensity) can be adjusted. The confocal optical system 3 includes a ¼λ plate 31, an objective lens system 32, a pinhole disk 34, a polarization beam splitter 23, and a relay lens system 35, which are aligned on the optical axis extending upward from the test object 8. Configured. The imaging device 4 includes an imaging element (light detection unit) 41 provided at the image plane position of the relay lens system 35, and is configured using, for example, a two-dimensional photoelectric element such as a CCD or a CMOS. The test object 8 is placed on the stage 7 and is disposed near the focal point of the confocal optical system 3.

  The light beam emitted from the illumination light source 21 is converted into parallel light by the condenser lens 22 and enters the polarization beam splitter 23. The polarization beam splitter 23 has a function of transmitting the P-polarized component of the incident light and reflecting the S-polarized component, and the reflected S-polarized illumination light is applied to the upper surface of the pinhole disk 34.

  The pinhole disk 34 has a thin disk shape, and a plurality of confocal pinholes (confocal micro openings) 34a that transmit light are arranged in a spiral shape on a light-shielding thin film that has been subjected to an antireflection treatment. (A pinhole disk having such a configuration is also referred to as a Nippon disk). The pinhole disk 34 is disposed orthogonal to the optical axis of the confocal optical system 3 so as to block the illumination light reflected by the polarization beam splitter 23. The pinhole disk 34 is rotated at a predetermined rotational speed by a motor 34m, and the illumination light that has passed through the confocal pinhole 24a is confocal to the object 8 placed on the stage 7 via the objective lens system 32. Condensed and irradiated as an image (point image) of the pinhole 34a. In FIG. 1, a light beam passing through two confocal pinholes 34a and 34a is illustrated.

  The image of the confocal pinhole 34a focused and irradiated on the test object 8 is reflected by the surface of the test object 8 (hereinafter referred to as “object plane O”) and is incident on the objective lens system 32 again. The light is condensed by the objective lens system 32 to form an image of the surface of the test object 8 on the lower surface of the pinhole disk 34 and passes through the confocal pinhole 34a. Here, the reflected light that has passed through the confocal pinhole 34a (referred to as “passed light” in the same manner as described above) passes through the quarter-λ plate 21 twice by the illumination light that has been changed to S-polarized light by the polarization beam splitter 23. The light is converted to P-polarized light, passes through the polarization beam splitter 23, is collected by the relay lens system 35, and forms an image of the confocal pinhole 34 a on the imaging surface of the imaging device 41.

  In addition, by providing the ¼λ plate 21 and the polarization beam splitter 23 so that the imaging device 4 captures the polarization component of the reflected light (P-polarized light), the entire amount of passing light with weak light intensity is obtained. While transmitting, it is possible to block the flare light caused by the surface reflection of the optical member located closer to the test object than the polarizing beam splitter 23, thereby obtaining a clear confocal image.

  Then, the pinhole disc 34 on which a large number of confocal pinholes 34a are formed is rotated at a high speed by a motor 34m at a predetermined speed, so that the illumination light passing through each confocal pinhole 34a becomes spot light as the test object 8 The object surface O is scanned, and a reflected image (confocal image) of the test object 8 that has passed through the confocal pinhole 34a is photographed by the imaging device 4 and processed by the processing device 60 in the control device 6. Thus, a confocal image including the height information of each part of the test object 8 can be obtained.

  That is, in the confocal optical system 3, when the object plane O (the surface of the test object) is at the height position of the focal plane of the objective lens system 32, the reflected light is coupled to the pinhole forming surface of the pinhole disk 34. Although almost all of the reflected light passes through the confocal pinhole 34a as the passing light, if the object plane O slightly deviates from the height of the focal plane of the objective lens system 32, the reflected light is pinholed. An image is not formed on the formation surface, and only a part can pass through the confocal pinhole 34a.

  For this reason, at least one of the test object 8 and the confocal optical system 3 is displaced in the optical axis direction (Z-axis direction in which a coordinate axis is added to FIG. 1), and the height of the focal plane relative to the object O is relatively displaced. The reflected light from the test object 8 is photographed by the imaging device 4 via the pinhole disk 34, and the height position at which the light intensity of the passing light detected by the imaging element 41 is maximized is determined for each of the imaging elements 41. By obtaining for each pixel, the height position of each part of the test object corresponding to each pixel can be detected.

FIG. 2 shows the stage 7 (object plane) when the stage 7 is displaced in the optical axis direction (Z-axis direction) so that the object plane O of the object 8 is positioned near the focal plane of the objective lens system 32. 10 schematically shows changes in the Z coordinate position of O) and the light intensity I of the passing light received by the image sensor 41. As apparent from the detection principle, when the stage 7 is continuously displaced in the Z-axis direction (optical axis direction), the light intensity I of the passing light changes smoothly as shown by the dotted line in the figure, and the objective lens At the height position Z ₀ where the focal plane of the system 32 and the object plane O coincide with each other, the light intensity I of the passing light becomes the maximum value I ₀ .

  Under proper illumination conditions, there is a certain proportional relationship between the light intensity I of the passing light and the luminance signal output from the imaging device 4, and the height position where the luminance signal is maximized is obtained for each pixel. Thus, the height position of each part of the corresponding test object can be detected.

Therefore, the control device 6 controls the operation of the stage drive unit 52 to displace the test object 8 in the optical axis direction, and changes the intensity of the passing light detected by the image pickup device 41 at this time from the image pickup device 4 to the control device. The height position of the surface of the test object 8 is specified by obtaining the position Z ₀ in the Z direction of the stage 7 when the magnitude of the luminance signal reaches a peak. be able to. Then, by detecting the height position of the surface of the test object for each pixel of the image sensor 41, the relative height position relationship of each part of the test object 8 can be specified for the entire imaging region. Thereby, the height measurement of a fine part and the three-dimensional solid shape measurement can be performed.

  The inspection apparatus 1 shown in the figure has a form in which the height position of the object plane O with respect to the focal plane of the confocal optical system 3 is displaced in the optical axis direction by moving the stage 7 on which the object 8 is placed up and down. The control device 6 is configured to control the operation of the stage drive unit 52 to displace the test object 8 on the stage 7 in the optical axis direction. However, the stage 7 on which the test object 8 is placed is fixed and the entire confocal optical system 3 is changed in the optical axis direction, or the objective lens on the test object side in the objective lens system 32 is displaced in the optical axis direction. Thus, even when the height position of the focal plane of the confocal optical system 3 with respect to the object plane O is displaced in the optical axis direction, the height position of the test object 8 can be measured similarly.

Here, if the passing light from the test object 8 is detected continuously or at a fine pitch for each pixel, the storage capacity of the memory for storing the change of the luminance signal for each pixel becomes enormous, and the passing light It takes a long time to calculate the peak position. On the other hand, the characteristics of the intensity change of the passing light in the vicinity of the in-focus position Z ₀ shown in FIG. 2 are already known, and can be approximated to a two-dimensional function such as a Gaussian function or a point spread function. Therefore, if the light intensity I of the passing light is known at least at two coordinate positions in the Z direction, the focus position Z ₀ and the peak intensity I ₀ are calculated by interpolating this data (curve fit calculation). be able to.

In the inspection apparatus 1, the sampling interval (height interval) ΔZ is set in advance so that the light intensity I of the passing light can be sampled at at least three locations on the Z coordinate, and the processing device 60 in the control device 6 Then, the operation of the stage drive unit 52 is controlled to displace the stage 7 in the optical axis direction at a height interval ΔZ, and read from the imaging device 4 at each height position (Z ₁ , Z ₂ , Z _{3 in} FIG. 2). An interpolation process is performed based on the luminance signal, and the in-focus position Z ₀ and the peak intensity I ₀ are calculated.

However, as a premise for calculating the in-focus position Z ₀ by the interpolation process as described above, the luminance signal input from the imaging device 4 has a sufficient magnitude and is not saturated, that is, for the test object 8. It is necessary that the lighting conditions are within an appropriate range. However, due to the characteristics of the confocal optical system as described above, the light intensity I of the passing light is not known until the focal plane of the confocal optical system 3 and the object plane O of the test object 8 coincide.

As a result, in relation to the light receiving sensitivity of the image sensor 41, as shown in FIG. 3A, the luminance signal values of the sampling data of about 3 to 4 places input from the imaging device 4 to the processing device 60 are too low. When it is difficult to specify an accurate in-focus position, or as shown in FIG. 3B, the light intensity I of the passing light exceeds the saturation light reception intensity I _S of the image sensor 41 at least at one of the sampling points. In some cases, the luminance signal is saturated. Accordingly, in order to measure the three-dimensional shape of the test object 8 or to obtain a confocal image (referred to as an all-focus image) in which the entire imaging range is in focus, each part of the test object at each height position is obtained. On the other hand, it is necessary to obtain an illumination condition that provides an appropriate illumination illuminance.

  In the inspection apparatus 1, the processing apparatus 60 is configured to adjust the intensity of light applied to the test object 8 based on the image data read from the imaging apparatus 4. FIG. 4 is a block diagram of the processing device 60 that performs such adjustment control. Hereinafter, the configuration of the processing device 60 and the control operation of the inspection device 1 by the processing device 60 will be described.

  The processing device 60 includes a CPU 61, a drive control unit 62 that controls the operation of the stage drive unit 52, an image data storage unit 63 that stores image data input from the imaging device 4, and the intensity of light irradiated on the test object 8. An illuminance control unit 64 that changes the image, an image data extraction unit 65 that extracts data of the in-focus portion from the image data stored in the image data storage unit 63, and an image that generates a confocal image by combining the extracted image data It is composed of a synthesis unit 66 and the like.

  Image data is input from the imaging device 4 to the processing device 60, and a height position in the optical axis direction of the stage 7, that is, a coordinate position on the Z axis is input from the stage driving unit 52. Further, the processing device 60 is provided with an output unit 67 for outputting the processing result, and the three-dimensional shape and the omnifocal image of the test object 8 are transferred to the image display device 71 such as a liquid crystal display panel or CRT, the printer 72 and the like. Output is enabled.

  When the process for setting the illumination illuminance (pre-scan process) is started, the processing device 60 outputs a command signal from the illuminance control unit 64 to the illumination light source 21 to emit illumination light with a predetermined light intensity set in advance. Let it emit. The predetermined light intensity is set in the memory in the processing device 60 as illumination illuminance for measuring the reflectance of the test object. For example, the type of the test object 8 (printed wiring board, IC chip, semiconductor) The illumination illuminance according to the wafer or the like is set and stored, and can be selected and set according to the object to be inspected.

  Next, a command signal is output from the drive control unit 62 to the stage drive unit 52 to start the movement of the stage 7 in the Z direction, and the imaging device 4 captures images at every height interval ΔZ from the initial setting start position of image data. The read image data is read and stored in the image data storage unit 63 together with the Z coordinate position. When this reading and storing process is completed for a preset image data acquisition range (height range or number of shots), the CPU 61 in the processing device 60 stores the image data stored in the image data storage unit 63. The luminance signal is rearranged in time series for each pixel, and a group of luminance signal strings composed of 3 to 4 discrete data having high luminance signal values is extracted for each pixel. This is a detection signal of passing light in the vicinity of the focal plane of each part.

  The illuminance control unit 64 calculates the adjustment amount of the illumination illuminance with reference to a group of luminance signal sequences including the highest luminance signal among the extracted luminance signal sequences.

(First embodiment)
In the adjustment process of the first embodiment, the light intensity I of the passing light is compared with the saturated light intensity I _S of the image sensor 41, and the intensity of the light irradiated on the test object 8 is changed based on the comparison result. Then, the illumination illuminance of the test object 8 is adjusted.

For example, as illustrated in FIG. 3A, the light intensity I (luminance signal value) of the passing light detected by the image sensor 41 is a group of luminance signal sequences with respect to the saturated light intensity I _S of the image sensor 41. Is low for all, the illuminance control unit 64 calculates an intensity difference ΔI = | I _S −I | between the saturated light intensity I _S and the detected maximum light intensity I, and according to the intensity difference ΔI. The output signal is output to the illumination light source 21 to increase the luminance (light emission intensity) of the illumination light source 21 and increase the intensity of light applied to the test object 8. Note the sum of a group of luminance signal data may be compared with the saturation intensity I _S be configured to perform the illuminance adjustment.

On the other hand, as shown in FIG. 3B, the light intensity I (luminance signal value) of the passing light is higher than the saturation light intensity I _S of the image sensor 41, and saturation occurs in any of a group of luminance signal strings. When this occurs, the illuminance control unit 64 calculates the luminance signal at the saturated position from the luminance signals before and after sandwiching the saturated luminance signal (up and down at the height position) to obtain the maximum light intensity I. Then, an intensity difference ΔI = | I _S −I | between the maximum light intensity I and the saturated light intensity I _S is calculated. And the signal according to this intensity difference (DELTA) I is output to the illumination light source 21, the brightness | luminance of the illumination light source 21 is reduced, and the intensity | strength of the light irradiated to the test object 8 is reduced.

  Here, in this pre-scan, since the illumination illuminance of the initially set illumination light is known, the light intensity I (luminance signal value) of the passing light received by the image sensor 41 is detected. The reflectance of the part of the object 8 can be obtained. For this reason, the illumination illuminance to be raised or lowered can be calculated based on the reflectance and the intensity difference ΔI of the test object 8 thus obtained, and the illuminance control unit 64 responds to the illuminance thus calculated. A signal is output to the illumination light source 21 to increase or decrease the illumination illuminance of the test object 8.

Therefore, the adjustment processing according to the present embodiment makes it possible to obtain an appropriate illumination illuminance by one pre-scan, so that the three-dimensional shape of the test object 8 can be immediately measured in the next measurement scan without performing adjustments over and over again. Shapes and omnifocal images can be acquired. In the present embodiment, as a specific example of comparing the light intensity I of the passing light with the saturated light intensity I _S of the image sensor 41, the case of calculating the intensity difference ΔI has been described. However, the intensity ratio (for example, I / I) is described. _S ) may be calculated to adjust the illumination illuminance.

(Second Embodiment)
In the adjustment process of the second embodiment, the maximum light of the passing light to be detected by the image sensor 41 when the surface of the test object 8 and the focal position of the confocal optical system 3 coincide with each other from a group of luminance signal sequences. The intensity I _MAX is calculated by interpolation processing, and the intensity of light irradiated on the test object 8 is adjusted according to the calculated maximum light intensity I _MAX . That is, as described with reference to FIG. 2, if the light intensity I (luminance signal value) of the passing light is known at at least two coordinate positions, the two coordinate positions and the luminance signal value are interpolated. Thus, the in-focus position and the maximum light intensity can be calculated, and the illumination illuminance is adjusted according to the maximum light intensity I _MAX thus determined.

For example, as shown in FIG. 3A, when the light intensity I of the passing light is low, the illuminance control unit 64 interpolates the detected luminance signal data at the four locations and performs the maximum light intensity I of the passing light. _MAX is calculated, the calculated maximum light intensity I _MAX is compared with the saturated light intensity I _S of the image sensor 41, and a signal corresponding to the intensity difference ΔI = | I _S −I _MAX | The luminance (light emission intensity) of the illumination light source 21 is increased by output, and the intensity of light irradiated on the test object 8 is increased.

On the other hand, as shown in FIG. 3B, when the light intensity I of the passing light is higher than the saturation light intensity I _S of the image sensor 41 and saturation occurs in any of a group of luminance signal sequences, The illuminance control unit 64 interpolates the luminance signal data at three locations that are not saturated to calculate the maximum light intensity I _MAX of the passing light, and calculates the calculated maximum light intensity I _MAX and the saturated light intensity of the image sensor 41. Compared with I _S , a signal corresponding to the intensity difference ΔI = | I _S −I _MAX | is output to the illumination light source 21 to reduce the luminance of the illumination light source 21, and light irradiated on the test object 8. Reduce the strength.

In the pre-scan, the reflectance of each part of the test object 8 can be obtained in the same manner as in the above-described embodiment, and should be increased or decreased based on the reflectivity of the test object 8 and the intensity difference ΔI. The illumination illuminance can be calculated, and the illuminance control unit 64 outputs a signal corresponding to the illuminance thus calculated to the illumination light source 21 to increase or decrease the illumination illuminance of the test object 8. As in the above-described embodiment, the illumination illuminance may be adjusted based on the intensity ratio (for example, I _MAX / I _S ).

  Therefore, also in the adjustment process of the present embodiment, as in the above-described embodiment, it is possible to obtain an appropriate illumination illuminance by one pre-scan, and thereby the next measurement without repeated adjustments. The three-dimensional shape and omnifocal image of the test object 8 can be acquired immediately by scanning. Furthermore, since the maximum light intensity of the passing light and its height position (focus position) can be obtained by pre-scanning, the illumination illuminance can be adjusted more finely and only the focus position can be selectively selected in the measurement scan. In addition, it is possible to scan accurately according to the in-focus position, and the measurement time can be further shortened.

  In addition, although the structure which changes the brightness | luminance (light emission intensity) of the illumination light source 21 was illustrated as a means to adjust the intensity | strength of the light irradiated to the to-be-tested object 8, other means, for example, in the optical path of the illumination optical system 2, is illustrated. A filter having a plurality of transmittances or continuously changing transmittances may be inserted and removed to change the intensity of light irradiated on the test object 8 while keeping the luminance of the illumination light source 21 constant.

  When the pre-scan process for adjusting the illumination illuminance of the test object 8 is completed in this way, the processing device 60 shifts to a process for measuring the height (measurement scan process). When the measurement scan process is started, the processing device 60 outputs a command signal from the illuminance control unit 64 to the illumination light source 21 to emit illumination light with the light intensity obtained by the pre-scan process.

  Next, a command signal is output from the drive control unit 62 to the stage drive unit 52 to start the movement of the stage 7 in the Z direction, and from the initial setting position of acquisition of image data, for every same height interval ΔZ as the pre-scan, Alternatively, the image data captured by the imaging device 4 is read at the height position where the object plane O is detected in the pre-scan, and is stored in the image data storage unit 63 together with the Z coordinate position. The image data stored in this way is height information acquired under appropriate illumination conditions.

  When the image data reading and storing process ends for the preset image data acquisition range, the CPU 61 in the processing device 60 converts the image data stored in the image data storage unit 63 into a luminance signal for each pixel. Rearranged into time-series data arranged in time series, the image data extraction unit 65 extracts data having the maximum luminance signal for each pixel. The data for each pixel is confocal image data in a focused state of a minute portion of the test object corresponding to each pixel. The processing device 60 performs the interpolation processing described above to calculate the Z coordinate of the in-focus position for each corresponding region of each pixel.

  Then, the image data for each pixel extracted by the image data extraction unit 65 is synthesized by the image synthesis unit 66, and an omnifocal image in which the entire imaging range is in focus is generated. The generated omnifocal image is output from the output unit 67, displayed on an image display device 71 such as a CRT or a liquid crystal display panel, and printed out from the printer 72. The generated omnifocal image is a high-definition confocal image captured under appropriate illumination conditions. Therefore, according to the inspection apparatus 1, since the appropriate illuminance is set without repeatedly performing complicated illuminance adjustment, observation by the confocal optical system 3 can be quickly performed.

1 is a schematic configuration diagram of an inspection apparatus exemplified as an embodiment of the present invention. It is explanatory drawing which shows the change of the Z coordinate position of the object surface O, and the light intensity of passing light. It is explanatory drawing which shows the effect | action of a test | inspection apparatus. It is a block diagram of the processing apparatus in the said inspection apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inspection apparatus (optical system) 3 Confocal optical system 5 Displacement mechanism (displacement part) 8 Test object 21 Illumination light source 41 Image sensor (light detection part)
34m Confocal Pinhole (Confocal Micro Aperture) 60 Processing Device (Processing Unit)

Claims (8)

An illumination light source that emits illumination light;
A confocal optical system that irradiates the object to be examined with the illumination light emitted from the illumination light source through the confocal microscopic aperture, and obtains the passing light reflected by the test object and passing through the confocal microscopic aperture. When,
A light detection unit for detecting the passing light obtained in the confocal optical system;
A displacement part for displacing a focal position of the confocal optical system with respect to the test object in an optical axis direction;
A processing unit that reads and processes detection data from the light detection unit at a plurality of positions in which the focal position is displaced by the displacement unit;
The optical system, wherein the processing unit is configured to adjust the intensity of light applied to the test object based on the detection data read at the plurality of positions.   The processing unit compares the light intensity of the passing light detected by the light detection unit with the saturation light intensity of the light detection unit from the detection data read at the plurality of positions, and based on the comparison result The optical system according to claim 1, wherein the optical system is configured to adjust the intensity of light irradiated to the test object.   The processing unit is configured to detect the passing light to be detected by the light detection unit when the surface of the test object and the focal position of the confocal optical system coincide from the detection data read at the plurality of positions. The maximum intensity of the light is calculated by interpolation processing, and the intensity of light irradiated on the test object is adjusted according to the calculated maximum intensity. Optical system.   The processing unit adjusts the intensity of light applied to the test object, and then displaces the focal position by the displacement unit to read detection data from the light detection unit at a plurality of positions. The optical system according to any one of claims 1 to 3, wherein the height information is acquired. An illumination light source that emits illumination light, and the illumination light emitted from the illumination light source irradiates the test object through a confocal microscopic aperture, is reflected by the test object, and passes through the confocal microscopic aperture A confocal optical system that obtains passing light; a light detection unit that detects the passing light obtained by the confocal optical system; and a focal position of the confocal optical system with respect to the test object is displaced in the optical axis direction. A control method for an optical system comprising: a displacement unit; and a processing unit that displaces the focal position by the displacement unit and reads and processes detection data from the light detection unit,
Causing the illumination light source to emit the illumination light at a predetermined light intensity;
The processing unit reads detection data from the light detection unit at a plurality of positions where the focal position of the confocal optical system is displaced in the optical axis direction by the displacement unit,
A control method for an optical system, characterized in that the intensity of light applied to the test object is adjusted based on the detection data read at the plurality of positions. The processor is
From the detection data read at the plurality of positions, comparing the light intensity of the passing light imaged on the light detection unit and the saturation light intensity of the light detection unit,
6. The method of controlling an optical system according to claim 5, wherein an intensity of light irradiated on the test object is adjusted based on a comparison result. The processor is
Based on the detection data read at the plurality of positions, the light intensity of the reflected light to be detected by the light detection unit when the surface of the test object coincides with the focal position of the confocal optical system is determined. Calculated by inserting,
The optical system control method according to claim 5, wherein the optical system is configured to adjust the intensity of light applied to the test object in accordance with the calculated light intensity. The processor is
After adjusting the intensity of light irradiated to the test object,
Reading detection data of the passing light detected by the light detection unit at a plurality of positions where the focal position is displaced by the displacement unit,
The optical system control method according to any one of claims 5 to 7, wherein height information of the test object is acquired.

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