JP2005195419A - Height measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a height measuring device capable of detecting the height of a measuring object accurately at high speed in the noncontact state. <P>SOLUTION: This height measuring device is equipped with a two-dimensional photodetection part 30 for receiving light from the measuring object 5 by changing a relative position in the optical axis L1 direction in a confocal optical system 10 to the measuring object 5, and an operation control part 40 for outputting the height of the measuring object 5 based on a detection result detected by the two-dimensional photodetection part 30. In the device, position information in the optical axis direction of a pixel from which the maximum light quantity is detected, which is acquired based on output results from a maximum light quantity detection part 33 for detecting the maximum light quantity of each pixel and a coordinate counter 51 for outputting information of the relative position in the optical axis direction in the confocal optical system 10, is retained in a peak coordinate latch part 35, and outputted to the operation control part 40. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a height measuring device.

As a conventional height measurement device, a two-dimensional photoelectric sensor that receives light from a measurement object by changing the relative position of the confocal optical system with respect to the measurement object in the optical axis direction, and the two-dimensional photoelectric sensor detected by the two-dimensional photoelectric sensor What is provided with the arithmetic processing part which outputs the height of a measuring object based on an image is known. In this confocal optical system, the amount of light of the point spread function increases or decreases around the focal position.
Japanese Patent Laid-Open No. 9-12639

  In recent years, while moving the measurement object in the direction of the optical axis at high speed, taking the several points on the point spread function and calculating the coordinate that gives the maximum light intensity from these points, the height of the measurement object can be calculated. Measurements are being made at high speed.

By the way, in order to perform highly accurate height measurement, it is advantageous that the NA (aperture) of the optical system is large. However, the width of the point spread function of the confocal optical system (point image of the position in the optical axis direction and the amount of light). When the distribution function-like behavior width (referred to as Z-I profile) is D, a relationship of D = K / (NA ² ) is established between D and NA. K is a constant determined by the wavelength. Therefore, the width D decreases as NA increases.

  When capturing an image discretely, it is necessary to perform image sampling including discrete data at several points of the width D. When NA is increased, fine image sampling corresponding to the decrease in the width D is required. Therefore, much time is required for the measurement.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a height measuring device capable of detecting the height of a measurement object at high speed and accurately without contact.

  In order to solve the above-mentioned problem, a first aspect of the present invention provides a two-dimensional light detection means for receiving light from the measurement object by changing a relative position in the optical axis direction of the confocal optical system with respect to the measurement object. A height measuring apparatus comprising: a calculating means for outputting the height of the measurement object based on a detection result detected by the two-dimensional light detecting means; wherein the two-dimensional light detecting means is a maximum light quantity of each pixel. A maximum light amount detection means for detecting the position, a position information output means for outputting information on the relative position of the confocal optical system in the optical axis direction with respect to the measurement object, the maximum light amount detection means, and the position information output means. And a peak coordinate latch means for holding position information in the optical axis direction of the pixel in which the maximum light quantity is detected, obtained based on the output result.

  According to a second aspect of the present invention, in the height measuring device according to the first aspect, a peak light amount latching unit that holds the maximum light amount information of each pixel detected by the maximum light amount detection unit and outputs the information to the calculation unit. It is characterized by having.

  According to the height measuring apparatus of the present invention, the height of the measuring object can be detected at high speed and accurately without contact.

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

  FIG. 1 is a block diagram showing a height measuring apparatus according to the first embodiment of the present invention.

  The height measuring apparatus 1 includes a confocal optical system 10, a two-dimensional light detection unit (two-dimensional light detection unit) 30, and an arithmetic control unit (calculation unit) 40.

  The confocal optical system 10 includes a light source 11, a half prism 12, an imaging lens 13, a Nipou disk 20, an objective lens 14, and a λ / 4 plate 15.

  The light source 11 is disposed on the optical axis L2. A halogen lamp or the like is used as the light source 11.

  The imaging lens 13 is disposed between the half prism 12 and the Niipou disk 20, and condenses the illumination light emitted from the light source 11 and reflected by the half prism 12 in the pinhole 21.

  A plurality of pinholes 21 having the same diameter are formed in the Nipkow disk 20 in a spiral shape at predetermined intervals. The diameter of the pinhole 21 corresponds to the Airy disk diameter of the objective lens 14. The objective lens 14 condenses the light from the light source 11 on the measurement object 5. The measurement object 5 is placed on a stage 50 that can move in the optical axis direction.

  The central portion of the Nipkow disc 20 is fixed to the rotating shaft of the disc rotating motor 25.

  The λ / 4 plate 15 is disposed between the objective lens 14 and the measurement object 5, and gives a phase difference (λ / 4) to the light wave.

  The illumination light emitted from the light source 11 is reflected by the half prism 12, enters the imaging lens 13, and is condensed on the pinhole 21.

  The illumination light that has passed through the pinhole 21 enters the objective lens 14. The illumination light that has passed through the objective lens 14 passes through the λ / 4 plate 15 and is condensed on the surface of the measurement object 5.

  When the measurement object 5 is in the in-focus position corresponding to the position of the pinhole 21, the reflected light from the surface of the measurement object 5 passes through the λ / 4 plate 15 and is collected again in the pinhole 21 by the objective lens 14. Lighted.

  The reflected light that has passed through the pinhole 21 reaches the imaging lens 13 and is imaged by the imaging lens 13 on the light receiving surface of the C-MOS sensor 31 (see FIG. 2) of the two-dimensional light detection unit 30.

  When the measurement object 5 is not in the in-focus position corresponding to the position of the pinhole 21, the reflected light from the surface of the measurement object 5 is not condensed on the pinhole 21. Therefore, the amount of light passing through the pinhole 21 is reduced, and the reflected light reaching the C-MOS sensor 31 is reduced.

  FIG. 2 is a block diagram of the two-dimensional light detection unit.

  The two-dimensional light detection unit 30 includes a C-MOS sensor 31, a LOG conversion unit 32, a light amount peak detection unit (maximum light amount detection unit) 33, a peak coordinate latch unit (peak coordinate latch unit) 34, and a coordinate counter (position information output unit). 51.

  The number of pixels of the C-MOS sensor 31 is 1000 × 1000.

  The LOG converter 32 LOG-converts the output of the C-MOS sensor 31 in units of pixels to widen the dynamic range.

  The light quantity peak detection unit 33 detects the maximum light quantity in units of pixels.

  The coordinate counter 51 outputs information on the relative position of the confocal optical system 10 in the optical axis direction with respect to the measurement object 5. The position information is a pulse signal output from an encoder (not shown), for example, corresponding to the movement of the stage 50 in the optical axis direction.

  The peak coordinate latch unit 34 holds, in units of pixels, position information in the optical axis direction of the pixel from which the maximum light amount is detected, obtained based on outputs from the light amount peak detection unit 33 and the coordinate counter 51.

  For example, when the stage 50 is raised, the value of the coordinate counter increases as the stage 50 moves. The light quantity peak detection unit 33 detects the maximum light quantity for each pixel. The peak coordinate latch unit 34 holds the coordinates (peak coordinates) having the maximum light amount for each counter value of the coordinate counter 51 in units of pixels. The stage 50 is moved until no peak coordinates are detected.

  As a result, the peak coordinate latch unit 34 holds the peak coordinate data of each pixel in units of pixels. The peak coordinates are output to the arithmetic processing unit 40. Since the peak coordinate data is coordinate data indicating the height of each pixel, the arithmetic processing unit 40 can output the height of the measurement object 5.

  According to this embodiment, since the calculation for calculating the maximum light amount point is not required as in the conventional example, the height of the measurement object can be detected at high speed and accurately without contact. Moreover, since it is not necessary to acquire many slice images as data for height measurement as in the conventional example, the measurement time can be shortened. Furthermore, it is not necessary to acquire a fine image even with an optical system having a large NA.

  In addition, since the image is not acquired in units of time as in the conventional example, there is no possibility that an erroneous measurement result is caused due to the speed unevenness, and the moving mechanism in the optical axis direction can be simplified. Therefore, the two-dimensional light detection unit 30 may be attached to the microscope and the stage 50 may be manually moved in the optical axis direction.

  FIG. 3 is a block diagram of a two-dimensional light detection unit according to a modification of the present invention. The same reference numerals are given to the same parts as those in the above embodiment, and the description thereof is omitted.

  The two-dimensional light detection unit 130 includes a C-MOS sensor 31, a LOG conversion unit 32, a light amount peak detection unit (maximum light amount detection unit) 33, a peak coordinate latch unit (peak coordinate latch unit) 34, and a peak light amount latch unit (peak light amount latch). Means) 35 and a coordinate counter (position information output means) 51.

  The peak light amount latch unit 35 holds the maximum light amount information of each pixel.

  This peak light quantity information is output to the arithmetic processing unit 40 together with the peak coordinate information.

  According to this modification, the same effect as in the above embodiment is obtained, and data in a state where all the pixels are in focus is output to the arithmetic processing unit 40, so that the entire surface is focused based on this data. Images can be obtained.

FIG. 1 is a block diagram of a height measuring apparatus according to the first embodiment of the present invention. FIG. 2 is a block diagram of the two-dimensional light detection unit. FIG. 3 is a block diagram of a two-dimensional light detection unit according to a modification of the present invention.

Explanation of symbols

5 Measurement object 10 Confocal optical system 30, 130 Two-dimensional light detection unit (two-dimensional light detection means)
33 Light intensity peak detector (maximum light intensity detection means)
34 Peak coordinate latch (peak coordinate latch means)
35 Peak light quantity latch (peak light quantity latch means)
40 Calculation control unit (calculation means)
51 Coordinate counter (position information output means)
L1 optical axis

Claims (2)

Based on the two-dimensional light detection means for receiving light from the measurement object by changing the relative position of the confocal optical system with respect to the measurement object and the detection result detected by the two-dimensional light detection means. In a height measuring device comprising a calculating means for outputting the height of the measurement object,
The two-dimensional light detection means includes a maximum light quantity detection means for detecting a maximum light quantity of each pixel, a position information output means for outputting information on a relative position in the optical axis direction of the confocal optical system with respect to the measurement object, Peak coordinate latch means for holding position information in the optical axis direction of the pixel from which the maximum light quantity is detected, obtained based on output results of the maximum light quantity detection means and the position information output means. A height measuring device characterized by.   2. The height measuring apparatus according to claim 1, further comprising peak light amount latch means for holding maximum light amount information of each pixel detected by the maximum light amount detecting means and outputting the information to the calculating means.

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