JPH09101116A - Automatic focusing method and its device, and pattern detection method and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To do focusing with high precision through a low-cost optical unit, and detect a clear image signal by projecting a bright and dark pattern onto an object, causing the same to be reflected, and converting a bright and dark image pattern obtained from an image forming optical unit into a contrast signal. SOLUTION: An illuminating optical unit 12 projects a bright and dark pattern, which has bright and dark linear edges extending practically radially from an illuminating light source 9 via a mask 10, onto an object 4 via a condenser lens 11 and an objective lens 3. A pattern detecting image sensor 8 detects an optical image formed on the object 4 from a pattern to be detected by a lens 3. A focusing position at which a contrast signal of the bright and dark pattern composed of a difference signal between signals 31A, 31B obtained from sensors 14A, 14B after penetrating shade masks 13A, 13B and a bright and dark contrast signal composed of a difference signal between signals 32A, 32B obtained from sensors 16A, 16B after penetrating shade masks 15A, 15B approximately coincide with each other is judged by a focusing position judgement circuit 17 so as to adjust the (z) direction of the object.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dimension measuring method for measuring a dimension deviation between a plurality of patterns having height differences such as a superposition pattern formed on an LSI wafer, an apparatus therefor, an LSI wafer, and a print. An inspection method for inspecting a pattern defect of a wiring board, a thin film multi-layered substrate, a TFT thin film, etc., a pattern detection method for detecting a pattern such as the apparatus and its apparatus, a pattern detection method and an automatic focusing method suitable for the apparatus, and the like Regarding the device.

[0002]

2. Description of the Related Art As a conventional technique relating to automatic focusing in the form of projecting a pattern, Japanese Patent Laid-Open No. 59-155919 is known.
There are known ones described in Japanese Patent Application Laid-Open No. 61-235808 (Prior Art 1), Japanese Patent Laid-Open No. 61-235808 (Prior Art 2), Japanese Patent Laid-Open No. 62-115114 (Prior Art 3), and the like.
Among these, a typical example described in the prior arts 1 and 2 is shown in FIG. A projection pattern mask 162 having a grid-shaped striped pattern 171 (shown in FIG. 16) that is repeated in the uniaxial direction by the illumination optical system 161 is subjected to the grid-shaped striped pattern 171 that is repeated in the uniaxial direction through the objective lens 163. A one-dimensional linear image sensor for focus detection, which is projected on the object 164 and has its grid pattern 171 installed before and after the in-focus position via the objective lens 163 (one-dimensionally detects the light receiving pixels 172 as shown in FIG. 16). One-dimensional linear image sensor arrayed in 165), 165, 166
And the pattern contrast is calculated from the detected pattern to determine the shift of the focus position, and the position of the sample stage 167 in the Z direction is moved to enable adjustment to the focus position of the object 164, and a pattern detection image is obtained. The sensor 168 enables accurate pattern detection.

The automatic focusing is performed as follows. A projection pattern mask 162 having a grid-shaped stripe pattern 171 (shown in FIG. 16) that is repeated in the uniaxial direction is provided so as to be projected at the in-focus position, and is separated by one distance above the in-focus position. However, a one-dimensional linear image sensor for focus detection (one-dimensional linear image sensor in which light-receiving pixels 172 are arranged in a one-dimensional array as shown in FIG. 16) 165 is arranged so that the image forming position is formed, and the same distance below is the image forming position. So that the one-dimensional linear image sensor for focus detection (one-dimensional linear image sensor in which the light receiving pixels 172 are arranged in one dimension as shown in FIG. 16) 166
Is provided. As a result, when the surface of the object 164 is at the in-focus position as shown in FIGS. 17A and 17B, for example, every three pixels detected by each of the focus detecting one-dimensional linear image sensors 165 and 166. The contrast signals (the difference between the maximum output and the minimum output in FIG. 17) obtained by the difference between the output signals are equal. As shown in FIGS. 17C and 17D, when the surface of the object 164 is located above the in-focus position, the contrast signal detected by the focus detecting one-dimensional linear image sensor 165 (the maximum output and the minimum output in FIG. 17). The output difference) becomes large as shown in FIG. on the other hand,
When the surface of the object 164 is located below the in-focus position, the contrast signal (the difference between the maximum output and the minimum output in FIG. 17) detected by the focus detection image sensor 166 becomes large as shown in FIG. 17 (f). . Differences in contrast signals output from each of the focus detecting one-dimensional linear image sensors 165 and 166 (difference between (a) and (b) in FIG. 17, difference between (c) and (d), (c)). And (d)
The difference) is an S-shaped curve as shown in FIG. When this curve is approximately 0, the focus position Z is within the allowable range with respect to the in-focus position, so that the sample table 167 does not move. When the value is a negative value, the surface of the object 164 is below, so the sample table 167 is slightly moved to the above.
The surface of 64 is controlled to the in-focus position of the objective lens 163.

[0004]

The focus position control is
Although it is possible to solve the problem with the conventional technique, there is a problem that the scales of the focus detecting one-dimensional linear image sensors 165 and 166 and their control circuits are large and the cost is high. Further, when controlling the in-focus position with high accuracy, the pitch P of the grid-like striped pattern 171 repeated in the uniaxial direction is made equal to the several pixel pitch of the one-dimensional linear image sensors 165 and 166 for focus detection. There is a need to. For this reason, generally, the detection magnifications are made equal at the conjugate positions before and after the focusing position where the magnification adjusting mechanism and the focus detecting one-dimensional linear image sensors 165 and 166 are installed in the detection optical system including the objective lens 163. Therefore, it is necessary to use a telecentric optical system on the exit side. However, when the detection optical system including the objective lens 163 is not telecentric on the exit side, the direction of the principal ray differs depending on the image height, and the one-dimensional linear image sensors 165, 1 for focus detection are used.
If each of 66 is installed at a position other than the focus position, the detection magnification changes. That is, the magnification is small before the focused position and is large after the focused position. Therefore, the pitch P of the grid-shaped stripe pattern 171 is set to 2 before and after the focused position.
One-dimensional linear image sensor for focus detection 1
It becomes difficult to keep both the pixel pitches of 65 and 166 at an integral multiple, and the control accuracy of focusing is lowered. That is, all of the exit side telecentric optical system capable of adjusting the magnification, the one-dimensional linear image sensor, and the control circuit are expensive, and the above-mentioned conventional techniques have not sufficiently considered this point.

An object of the present invention is to solve the problems in the above-mentioned prior art by using an inexpensive optical system as an automatic focusing optical system so that the surface of an object or a sample can be focused and controlled with high precision. It is to provide a focusing method and an apparatus therefor. Another object of the present invention is to use an inexpensive optical system as an automatic focusing optical system so that the surface of an object or a sample can be focus-controlled with high accuracy and the object to be detected formed on the surface of the object or the sample. It is an object of the present invention to provide a pattern detection method and apparatus capable of detecting a clear image signal of a pattern to be detected by forming an optical image of the pattern in a focused state by an imaging optical system. It is also an object of the present invention to use an inexpensive optical system as an automatic focusing optical system so that the surface of an object or a sample can be focus-controlled with high accuracy, so that a plurality of objects having different heights can be provided on the surface of the object or the sample. The optical image of the pattern to be detected formed by the pattern is focused and imaged by the imaging optical system to detect a clear image signal of the pattern to be detected to determine the dimension between the plurality of patterns. An object of the present invention is to provide a pattern detection method and a device therefor capable of highly accurate measurement.

[0006]

In order to achieve the above object, the present invention provides an object (a substrate such as a semiconductor wafer) through an imaging optical system, and substantially from the optical axis of the imaging optical system. A bright / dark pattern having radially extending bright and dark linear edges is projected, and an image of the bright / dark pattern that is reflected from the object and obtained through the imaging optical system is received by a photoelectric conversion unit to form a contrast signal of the bright / dark pattern. The automatic focusing method is characterized in that the object is converted, and the object is relatively controlled at a focus position of the imaging optical system based on the converted contrast signal of the light-dark pattern. The present invention also projects a light-dark pattern having straight light and dark edges extending substantially radially from the optical axis of the imaging optical system through an imaging optical system, and reflecting the pattern from the object. The image of the dark pattern among the images of the bright pattern obtained through the image forming optical system is received by the first photoelectric conversion element and converted into the first signal corresponding to the dark pattern, and at the same time, the image of the bright pattern is formed. The object is relatively moved to the focus position of the imaging optical system based on the contrast signal of the light-dark pattern obtained by receiving the light by the second photoelectric conversion element and converting it into the second signal corresponding to the light pattern. It is an automatic focusing method characterized by controlling.

Further, according to the present invention, a light-dark pattern having straight edges of light and dark extending substantially radially from an optical axis of the imaging optical system is projected onto the object, and the object is projected. The image of the bright and dark pattern reflected from the image forming optical system and received by each of the first and second photoelectric conversion means arranged at a conjugate position before and after the in-focus position is received by the first and second photoelectric conversion means. And converting the contrast signals of the two bright and dark patterns, and relatively controlling the object at the focus position of the imaging optical system based on the converted contrast signals of the first and second bright and dark patterns. It is a featured automatic focusing method. The present invention also projects a light-dark pattern having a straight edge of light and dark extending substantially radially from the optical axis of the imaging optical system through the imaging optical system onto the object and reflecting from the object. The image of the bright and dark pattern obtained through the image forming optical system is received by the first photoelectric conversion elements constituting each of the first and second photoelectric conversion means arranged at conjugate positions before and after the focus position. And convert it to the first signal corresponding to the dark pattern,
A second constituting each of the first and second photoelectric conversion means
The photoelectric conversion element receives the light, converts it into a second signal corresponding to the bright pattern, and converts the first and second signals from the first and second photoelectric conversion means into the first and second signals. Automatic focusing, characterized in that the object is relatively controlled to a focus position of the imaging optical system based on the contrast signals of the first and second bright and dark patterns obtained corresponding to the photoelectric conversion means. Is the way.

Further, according to the present invention, a bright and dark linear edge which extends substantially radially from the optical axis of the imaging optical system through the imaging optical system with respect to the periphery of the pattern area to be detected on the object is provided. A pattern is projected, a light-dark pattern image reflected from the periphery and obtained through the imaging optical system is received by a photoelectric conversion unit and converted into a light-dark pattern contrast signal, and the converted light-dark pattern contrast signal is obtained. Based on the focusing step of relatively controlling the object to the in-focus position of the imaging optical system on the basis of the detected pattern area on the object controlled by the focusing step, the image is obtained through the imaging optical system. And a detected pattern detecting step of detecting the image signal of the detected pattern by receiving the received light by the photoelectric conversion means for the detected pattern detection method. Further, according to the present invention, a light-dark pattern having linear edges of light and dark extending substantially radially from the optical axis of the imaging optical system is projected to the periphery of the detected pattern area on the object through the imaging optical system. Then, of the bright and dark pattern images reflected from the periphery and obtained through the imaging optical system, the dark pattern image is received by the first photoelectric conversion element and converted into a first signal corresponding to the dark pattern. With
The image of the bright pattern is received by the second photoelectric conversion element and converted into a second signal corresponding to the bright pattern, and the target is located at the focus position of the imaging optical system based on the contrast signal of the bright / dark pattern obtained. A focusing step for relatively controlling the object, and light obtained through the imaging optical system from the pattern area to be detected on the object controlled in the focusing step is received by the photoelectric conversion means for detection and is received. And a detected pattern detecting step of detecting an image signal of a detection pattern.

Further, according to the present invention, a bright and dark linear edge extending substantially radially from the optical axis of the imaging optical system through the imaging optical system with respect to the periphery of the detected pattern region on the object is provided. An image of a bright-dark pattern obtained by projecting a pattern, reflecting from the periphery and obtained through the imaging optical system,
Each of the first and second photoelectric conversion means arranged at a conjugate position before and after the in-focus position receives the light and converts the light into a contrast signal of the first and second light-dark patterns, and the converted first and second contrast signals are obtained. A focusing step of relatively controlling the object to a focus position of the imaging optical system based on a contrast signal of a second bright-dark pattern, and a detected pattern on the object controlled in the focusing step. And a detected pattern detecting step of detecting the image signal of the detected pattern by receiving the light obtained from the area through the image forming optical system by the photoelectric conversion means for the detection. The present invention also projects a light-dark pattern having straight edges of light and dark extending substantially radially from the optical axis of the imaging optical system through the imaging optical system to the periphery of the detected pattern area on the object. Then, the images of the bright and dark patterns reflected from the periphery and obtained through the imaging optical system are arranged at the conjugate positions before and after the in-focus position.
The first photoelectric conversion element constituting each of the photoelectric conversion means receives the light and converts it into a first signal corresponding to the dark pattern, and the second signal constitutes each of the first and second photoelectric conversion means. The photoelectric conversion element receives the light and converts it into a second signal corresponding to the bright pattern, and the first and second signals in each of the first and second photoelectric conversion means are converted into the first and second signals. First and second obtained corresponding to photoelectric conversion means
A focusing step of relatively controlling the object to a focusing position of the imaging optical system based on the contrast signal of the light-dark pattern, and a detected pattern area on the object controlled in the focusing step. And a detected pattern detecting step of detecting the image signal of the detected pattern by receiving light obtained through the imaging optical system by the photoelectric conversion means for detection.

Further, according to the present invention, a first pattern (reference pattern) and a second pattern having a height difference on a sample (semiconductor wafer or the like) are provided.
Pattern (measurement pattern: resist pattern, etc.) is formed on the periphery of the detected pattern area, and a straight line edge of light and darkness that extends substantially radially from the optical axis of the imaging optical system is formed through the imaging optical system. An image of a light-dark pattern obtained by projecting a light-dark pattern having the light reflected from the periphery and obtained through the imaging optical system is received by a photoelectric conversion unit and converted into a contrast signal of the light-dark pattern, and the contrast of the converted light-dark pattern is converted. A focusing step of relatively controlling the sample to a focusing position of the imaging optical system based on a signal; and the first and second detection pattern areas on the sample controlled in the focusing step. The optical image from the pattern is imaged through the imaging optical system by the detection optical system having an optical path length difference according to the height difference and received by the photoelectric conversion means. The image signals of the first and second patterns are detected, the center position of the first pattern is calculated from the image signal of the first pattern, and the center position of the second pattern is calculated from the image signal of the second pattern. The detected pattern detecting step of calculating a dimension between the calculated center of the first pattern and the calculated center of the second pattern.

Further, according to the present invention, a first pattern (reference pattern) and a second pattern having a height difference on a sample (semiconductor wafer or the like) are provided.
Pattern (measurement pattern: resist pattern, etc.) formed on the periphery of the detected pattern area through a focusing optical system to form a straight edge of light and darkness that extends substantially radially from the optical axis of the focusing optical system. A first pattern corresponding to the dark pattern is obtained by receiving the image of the dark pattern among the images of the bright pattern obtained by projecting the bright pattern and the reflected pattern from the periphery and obtained through the imaging optical system. The image forming optical system based on the contrast signal of the light-dark pattern obtained by converting the signal of the light pattern into the second signal corresponding to the light pattern by receiving the image of the light pattern by the second photoelectric conversion element. From the focusing step of relatively controlling the sample to the in-focus position, and the first and second patterns in the detected pattern region on the sample controlled in the focusing step. An optical image is formed through the image forming optical system by a detection optical system having an optical path length difference according to the height difference and is received by photoelectric conversion means to detect image signals of first and second patterns, The center position of the first pattern is calculated from the image signal of the first pattern, and the center position of the second pattern is calculated from the image signal of the second pattern,
The detected pattern detection step of calculating a dimension between the calculated center of the first pattern and the calculated center of the second pattern is a pattern detection method.

Further, according to the present invention, a first pattern (reference pattern) and a second pattern having a height difference on a sample (semiconductor wafer or the like) are provided.
Pattern (measurement pattern: resist pattern, etc.) formed on the periphery of the detected pattern area through a focusing optical system to form a straight edge of light and darkness that extends substantially radially from the optical axis of the focusing optical system. An image of a bright-dark pattern obtained by projecting a bright-dark pattern that is provided, reflected from the periphery and obtained through the imaging optical system, of the first and second photoelectric conversion units disposed at conjugate positions before and after the focus position. The light is received by each and converted into contrast signals of the first and second light and dark patterns, and the sample is placed at the focus position of the imaging optical system based on the converted contrast signals of the first and second light and dark patterns. And a focusing step for relatively controlling the focusing step, and an optical image from the first and second patterns in the detected pattern area on the sample controlled by the focusing step Through the detection optical system having an optical path length difference according to the height difference, and the photoelectric conversion means receives the light to detect the image signals of the first and second patterns, and the image signal of the first pattern. From the image signal of the second pattern, the center position of the second pattern is calculated from the image signal of the second pattern, and the calculated center of the first pattern and the center of the second pattern are calculated. And a detected pattern detecting step of calculating a dimension between them.

Further, according to the present invention, a first pattern (reference pattern) and a second pattern having a height difference on a sample (semiconductor wafer or the like) are provided.
Pattern (measurement pattern: resist pattern, etc.) formed on the periphery of the detected pattern area through a focusing optical system to form a straight edge of light and darkness that extends substantially radially from the optical axis of the focusing optical system. An image of a bright-dark pattern obtained by projecting a bright-dark pattern which is provided, reflected from the periphery and obtained through the imaging optical system, of the first and second photoelectric conversion means arranged at a conjugate position before and after the focus position The first photoelectric conversion element constituting each receives the light and converts it into the first signal corresponding to the dark pattern, and the second photoelectric conversion element constituting each of the first and second photoelectric conversion means. Light is received and converted into a second signal corresponding to the bright pattern, and the first and second signals in each of the first and second photoelectric conversion means correspond to the first and second photoelectric conversion means. First obtained And a second focusing step for relatively controlling the sample to a focusing position of the imaging optical system based on the contrast signal of the dark and light pattern, and a detected pattern on the sample controlled in the focusing step. The light images from the first and second patterns in the area are imaged through the imaging optical system by a detection optical system having an optical path length difference according to the height difference, and received by photoelectric conversion means to receive the first image. And the image signal of the second pattern is detected, the center position of the first pattern is calculated from the image signal of the first pattern, and the center position of the second pattern is calculated from the image signal of the second pattern. And a detected pattern detecting step of calculating a dimension between the calculated center of the first pattern and the calculated center of the second pattern.

The present invention also provides a light-dark pattern projection optics for projecting a light-dark pattern having straight edges of light and dark extending substantially radially from an optical axis of the image-forming optical system through an image-forming optical system onto an object. System and photoelectric conversion means for receiving an image of a light-dark pattern reflected from the object by the light-dark pattern projected by the light-dark pattern projection optical system and obtained through the imaging optical system and converting it into a contrast signal of the light-dark pattern. And auto-focusing means for relatively controlling the object at the focus position of the imaging optical system based on the contrast signal of the light-dark pattern converted by the photoelectric conversion means. It is a matching device. The present invention also relates to a light-dark pattern projection optical system for projecting a light-dark pattern having straight edges of light and dark extending substantially radially from an optical axis of the image-forming optical system through the image-forming optical system onto an object, A first image corresponding to the dark pattern by receiving the image of the dark pattern among the images of the bright and dark pattern reflected from the object by the bright and dark pattern projected by the light and dark pattern projection optical system and obtained through the imaging optical system. First and second photoelectric conversion elements for converting the signal into a second signal corresponding to the bright pattern by receiving an image of the bright pattern, and a first photoelectric conversion element converted from the first photoelectric conversion element.
Control for relatively controlling the object at the focus position of the imaging optical system based on the contrast signal of the light-dark pattern obtained from the signal of No. 2 and the second signal converted from the second photoelectric conversion element. And an automatic focusing device.

The present invention also relates to a light-dark pattern projection optics for projecting a light-dark pattern having straight edges of light and dark extending substantially radially from the optical axis of the image-forming optical system through an image-forming optical system onto an object. First and second bright and dark patterns by receiving light from each of a system and a bright and dark pattern projected by the bright and dark pattern projection optical system to obtain an image of the bright and dark pattern obtained from the object through the imaging optical system. First and second photoelectric conversion means arranged at conjugate positions before and after the in-focus position so as to be converted into the contrast signal of
Focusing point of the imaging optical system based on the contrast signal of the first light-dark pattern converted by the first photoelectric conversion means and the contrast signal of the second light-dark pattern converted by the second photoelectric conversion means An automatic focusing device, comprising: a control unit that relatively controls the object at a position. The present invention also relates to a light-dark pattern projection optical system for projecting a light-dark pattern having straight edges of light and dark extending substantially radially from an optical axis of the image-forming optical system through the image-forming optical system onto an object, A first signal corresponding to the dark pattern, which is received by the dark pattern of the image of the bright and dark pattern reflected from the object by the bright and dark pattern projection optical system and obtained from the object through the imaging optical system. And a second photoelectric conversion element for receiving the bright pattern and converting it into a second signal corresponding to the bright pattern. The first and second signals are converted into first and second photoelectric conversion elements. First and second photoelectric conversion means arranged at conjugate positions before and after the focus position for obtaining the contrast signal of the second bright-dark pattern, and first photoelectric conversion means obtained from each of the first and second photoelectric conversion means. 1st and 1st Is the automatic focusing apparatus characterized by comprising a control means for relatively controlling the object in-focus position of the imaging optical system on the basis of the contrast signal light and dark pattern.

Further, according to the present invention, an image forming optical system for forming an optical image of the detected pattern from the detected pattern region on the object, and an optical image of the detected pattern formed by the image forming optical system. A pattern detection device having a photoelectric conversion means for detection for receiving an image signal of a detection pattern by receiving
A light-dark pattern for projecting a light-dark pattern having straight edges of light and dark extending substantially radially from the optical axis of the imaging optical system through the imaging optical system to the periphery of the detected pattern region on the object. A projection optical system and a photoelectric device that receives a light-dark pattern image reflected by the object by the light-dark pattern projected by the light-dark pattern projection optical system and obtained through the imaging optical system and converts it into a contrast signal of the light-dark pattern. A focusing device having conversion means and control means for relatively controlling the object at a focus position of the imaging optical system based on the contrast signal of the light-dark pattern converted by the photoelectric conversion means is provided. It is a pattern detection device characterized by the above. The present invention also provides
An image forming optical system for forming a light image of the detected pattern from the detected pattern region on the object, and a light image of the detected pattern formed by the image forming optical system are received to detect the detected pattern. A pattern detection apparatus having a photoelectric conversion means for detection for detecting an image signal, the bright and dark pattern extending substantially radially from an optical axis of the imaging optical system through the imaging optical system with respect to the object. A light-dark pattern projection optical system that projects a light-dark pattern having linear edges, and an image of a light-dark pattern obtained through the imaging optical system by being reflected from the object by the light-dark pattern projected by the light-dark pattern projection optical system. First and second of which a dark pattern image is received and converted into a first signal corresponding to the dark pattern, and a light pattern image is received and converted into a second signal corresponding to the bright pattern.
Of the photoelectric conversion element, the first signal converted from the first photoelectric conversion element, and the second signal converted from the second photoelectric conversion element based on the contrast signal of the light-dark pattern, It is a pattern detection apparatus comprising a focusing device having a control means for relatively controlling the object at a focus position of an imaging optical system.

Further, according to the present invention, an image forming optical system for forming an optical image of the detected pattern from the detected pattern region on the object, and an optical image of the detected pattern formed by the image forming optical system. A pattern detecting device having a photoelectric conversion means for detection for detecting an image signal of a detection pattern by receiving
A light-dark pattern projection optical system for projecting a light-dark pattern having straight edges of light and dark extending substantially radially from an optical axis of the image-forming optical system through the image-forming optical system onto the object, and the light-dark pattern projection An image of a light-dark pattern reflected from the object by the light-dark pattern projected by an optical system and obtained through the imaging optical system is received by each and converted into a contrast signal of the first and second light-dark patterns. The first and second photoelectric conversion means arranged at conjugate positions before and after the in-focus position, the contrast signal of the first bright-dark pattern converted by the first photoelectric conversion means, and the second photoelectric conversion means. A focusing device having control means for relatively controlling the object at a focus position of the imaging optical system based on the contrast signal of the second bright-dark pattern converted by the conversion means. A pattern detection device characterized by comprising a.

Further, according to the present invention, an image forming optical system for forming an optical image of the detected pattern from the detected pattern region on the object, and an optical image of the detected pattern formed by the image forming optical system. A pattern detecting device having a photoelectric conversion means for detection for detecting an image signal of a detection pattern by receiving
A light-dark pattern projection optical system for projecting a light-dark pattern having a straight edge of light and dark extending substantially radially from an optical axis of the image-forming optical system through the image-forming optical system onto the object, and the light-dark pattern projection Converting the first and second light signals corresponding to the dark pattern among the images of the light and dark pattern reflected from the object by the light and dark pattern projected by the optical system and obtained through the imaging optical system; 1
Photoelectric conversion element and a second photoelectric conversion element for receiving the bright pattern and converting it into a second signal corresponding to the bright pattern, and the first and second bright and dark patterns from the first and second signals. First and second photoelectric conversion means arranged at conjugate positions before and after the in-focus position for obtaining the contrast signal of
A first obtained from each of the first and second photoelectric conversion means
And a focusing device having a control means for relatively controlling the object at the focus position of the imaging optical system based on the contrast signal of the second bright-dark pattern. Is.

The present invention also provides a first method in which there is a height difference on a sample.
The optical images from the first and second patterns in the detected pattern area in which the second pattern and the second pattern are formed by forming an optical path length difference according to the height difference through an image forming optical system. A detection optical system that receives the image signals of the first and second patterns received by the photoelectric conversion means, and the center position of the first pattern is calculated from the image signal of the first pattern converted by the photoelectric conversion means. Then, from the image signal of the second pattern converted by the photoelectric conversion means to the second
The center position of the pattern is calculated, and the calculated first position is calculated.
A pattern detecting device having a calculating means for calculating a dimension between the center of the pattern and the center of the second pattern, wherein the image is formed on the periphery of the detected pattern region through the image forming optical system. A light-dark pattern projection optical system for projecting a light-dark pattern having straight edges of light and dark extending substantially radially from the optical axis of the optical system, and reflection from the object by the light-dark pattern projected by the light-dark pattern projection optical system. Photoelectric conversion means for receiving an image of a light-dark pattern obtained through the imaging optical system and converting it into a contrast signal of the light-dark pattern, and the image formation based on the contrast signal of the light-dark pattern converted by the photoelectric conversion means. A pattern detection device comprising a focusing device having a control means for relatively controlling the object at a focus position of an optical system. It is a device.

Further, according to the present invention, a bright-dark pattern having straight edges of light and dark extending substantially radially from an optical axis of the imaging optical system is projected on the object, and the object is projected. The image of the light-dark pattern reflected from the image-forming optical system is received by the photoelectric conversion means as the amount of transmitted light through a light-shielding mask (light-receiving window) having a pattern corresponding to the light-dark pattern and converted into a contrast signal of the light-dark pattern. The automatic focusing method is characterized in that the object is converted, and the object is relatively controlled to a focus position of the imaging optical system based on the converted contrast signal of the light-dark pattern. The present invention also projects a light-dark pattern having a straight edge of light and dark extending substantially radially from the optical axis of the imaging optical system through the imaging optical system onto the object and reflecting from the object. The image of the dark pattern among the images of the bright and dark patterns obtained through the imaging optical system is received by the first photoelectric conversion element as the amount of transmitted light through the light shielding mask (light receiving window) having the pattern corresponding to this dark pattern. And converts it into a first signal corresponding to the dark pattern, and an image of the bright pattern is received by the second photoelectric conversion element as a transmitted light amount through a light-shielding mask (light receiving window) having a pattern corresponding to the bright pattern. Focusing of the imaging optical system based on a contrast signal of a light-dark pattern which is converted into a second signal corresponding to the bright pattern and is obtained as a difference signal between the first signal and the second signal. An automatic focusing method characterized by relatively controlling the object in position.

According to the present invention, a light-dark pattern having straight linear edges of light and dark extending substantially radially from the optical axis of the imaging optical system is projected on the object, and the object is projected. An image of a light-dark pattern reflected from the image-forming optical system and obtained by the image-forming optical system is formed by a pattern corresponding to the light-dark pattern by each of the first and second photoelectric conversion means arranged at conjugate positions before and after the focus position. The light is received as a transmitted light amount through a light-shielding mask (light receiving window) having the above, and is converted into the contrast signals of the first and second light and dark patterns, and the above-mentioned result is obtained based on the converted contrast signals of the first and second light and dark patterns. The automatic focusing method is characterized in that the object is controlled relatively to a focus position of the image optical system.

With the above structure, the surface of the object or sample can be focused with high accuracy without using an expensive exit-side telecentric optical system with adjustable magnification as a detection optical system including an imaging optical system (objective lens). Matching can be achieved. Further, with the above-mentioned configuration, an expensive one-dimensional linear image sensor is further used as a photoelectric conversion element without using an expensive exit-side telecentric optical system with adjustable magnification as a detection optical system including an imaging optical system (objective lens). It is possible to realize highly accurate focusing of the surface of the object or sample without using. Further, with the above configuration, the surface of the object or sample can be focused with high accuracy without using an expensive exit-side telecentric optical system with adjustable magnification as a detection optical system including an imaging optical system (objective lens). Realized, and as a result, the optical image of the pattern to be detected formed on the surface of the object or sample is focused and focused by the imaging optical system to detect a clear image signal of the pattern to be detected. As a result, a fine defect inspection on the pattern to be detected can be realized with high reliability. Further, with the above configuration, the surface of the object or sample can be focused with high accuracy without using an expensive exit-side telecentric optical system with adjustable magnification as a detection optical system including an imaging optical system (objective lens). As a result, the light image of the pattern to be detected formed on the surface of the object or sample with a plurality of patterns with height differences is focused and focused by the imaging optical system to form an image. It is possible to detect a clear image signal of a pattern and measure the dimension between a plurality of patterns with high accuracy.

[0023]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a first block diagram of an automatic focusing method and pattern detection method including the apparatus according to the present invention
It is a schematic structure figure showing an example of. That is, the automatic focusing device includes an illumination light source 9 for focus detection, for example, FIG.
As shown in FIG. 2, a light-dark pattern having substantially no edges other than the radial direction (a light-dark pattern having straight edges of light and dark extending substantially radially around the optical axis of the objective lens 3) is repeated about three times or more. Formed (center 101
Is a visual field detected by the pattern detection image sensor 8. ) A mask 10 and a condenser lens 1 for projecting a light-dark pattern formed on the mask 10 onto the surface of an object (sample) 4 through an objective lens (imaging optical system) 3 to form an image.
1, an objective lens (imaging optical system) 3, an object (sample) 4 such as a semiconductor wafer on which a pattern for detection is formed, a printed wiring board, a thin film multilayer substrate, a TFT thin film, etc. And an optical image (which may be a reflected light image or a transmitted light image) formed by the objective lens (imaging optical system) 3 from the pattern to be detected formed on the object (sample) 4. Image sensor (linear image sensor, which detects light (receives light and converts it into an image signal))
(TV camera or the like) 8, a light-shielding mask 13A which is provided at a position apart from the in-focus position by a certain distance in the front side and shields a dark pattern through an inner bright pattern of a light-dark pattern, and a light-receiving element (sensor) for detecting the amount of transmitted light. ) 14A and a light-shielding mask 13B which is provided at a position separated by a predetermined distance h to the front side from the in-focus position and shields the light pattern through the dark and light patterns of the light-dark pattern (the transmittance is inverted with respect to the light-shielding mask 13A). And a light receiving element (sensor) 14B that detects the amount of transmitted light, and a position (a light shielding mask 13A,
13B and a light-shielding mask 15A that is provided at a position conjugate with 13B and shields the dark pattern through the inner-light pattern of the light-dark pattern
And a light receiving element (sensor) 16 for detecting the amount of transmitted light
A and a light-shielding mask 15B which is provided at a position away from the in-focus position by a distance to the rear side and shields the light pattern through the inner-dark pattern of the light-dark pattern (the transmittance is inverted with respect to the light-shielding mask 15A), and the light-shielding mask 15B. A light receiving element (sensor) 16B for detecting the amount of transmitted light, a signal 31A (S14A) obtained from the light receiving element (sensor) 14A, and a signal 31B (S14) obtained from the light receiving element (sensor) 14B.
B), for example, a contrast signal CA of a light-dark pattern formed of a difference signal, a signal 32A (S16A) obtained from the light receiving element (sensor) 16A, and a light receiving element (sensor) 16
A focus position determination circuit 17 that determines the in-focus position where the signal 32B (S16B) obtained from B and the contrast signal CB of the light-dark pattern, which is, for example, a difference signal, substantially match in the allowable range, and the focus position determination circuit 17 The vertical movement mechanism 18 is configured to move the sample table 7 up and down in order to adjust the position of the surface of the object 4 in the Z direction on the basis of the determination result.

Next, a bright and dark pattern (of the objective lens 3) repeated about three times or more is projected around the pattern to be detected on the surface of the object 4 through the objective lens 3 with substantially no edge other than in the radial direction. A mask 10 that creates a light-dark pattern that is repeated about three times or more and that has bright and dark linear edges extending substantially radially around the optical axis will be described. An example of the mask 10 is shown in FIG. That is, the mask 10a has a central portion formed of a transparent circular region that illuminates the light emitted from the illumination light source 9 with respect to the region (field of view) in which the pattern detection image sensor 8 detects the detected pattern on the object 4. 101 and an outer peripheral portion 102 formed by repeatedly forming a light-dark pattern (transparent pattern and opaque pattern) having straight edges of light and dark extending substantially radially around the optical axis of the objective lens 3 over the entire circumference. Has been formed. The outer peripheral portion 102 is an area in which the light-dark pattern is projected on the surface of the object 4 through the objective lens 3 for automatic focusing. This light-dark pattern (bright-dark pattern in which an extended line of a light-dark linear boundary (linear edge) is repeated in the circumferential direction toward the optical axis of the objective lens 3) has a bright portion (for example, every 5 degrees in the circumferential direction). It is formed by repeating transparent portions / dark portions (opaque portions). And the mask 10a is made of Cr
Etc. (forms a dark portion (opaque portion).) A glass mask or etching mask. When the illumination light source for illuminating the detected pattern on the object 4 to the area (field of view) detected by the image sensor 8 for pattern detection is provided separately from the illumination light source 9, the central portion 101 is provided. To be an opaque area.

Another embodiment of the mask 10 is shown in FIG.
And shown in FIG. The mask 10 shown in FIG.
In b, the area where the light-dark pattern is formed is the outer peripheral portion 1
2 shows the case of being formed in one side area of No. 02. In the mask 10c shown in FIG. 5A, the case where the area where the bright and dark pattern is formed is formed in the symmetrical area of the outer peripheral portion 102 is shown. The masks 10b and 10c shown in FIG. 4A and FIG. 5A have a central portion 101 formed of a transparent circular region that illuminates light emitted from the illumination light source 9.
And a peripheral portion 102 formed by repeating a light-dark pattern (transparent pattern and opaque pattern) having straight edges of light and dark extending substantially radially around the optical axis of the objective lens 3 about three times or more. ing. FIG. 6A shows a shape similar to the mask 10a shown in FIG.

Next, the light-shielding masks 13A and 15A installed in front of the light-receiving elements (sensors) 14A and 16A and the light-shielding masks 13B and 15B installed in front of the light-receiving elements (sensors) 14B and 16B will be described. FIG.
As shown in (b), the light-shielding masks 13Aa and 15Aa
Is a central portion 10 that shields patterns other than automatic focusing.
3 and the light image of the light-dark pattern projected through the surface of the object 4 and reflected and obtained through the objective lens 3,
An outer peripheral portion 104 is formed by repeatedly forming a transparent portion that transmits a light pattern light image and an opaque portion that blocks a dark pattern light image over the entire circumference. This peripheral part 1
04 is formed in a shape similar to the light-dark pattern of the outer peripheral portion 102 of the mask 10a. As shown in FIG. 2C, the light-shielding masks 13Ba and 15Ba are obtained through the objective lens 3 by being projected and reflected on the central portion 103 which shields the pattern other than the automatic focusing and the surface of the object 4. Of the light image of the bright and dark pattern to be formed, it is formed of a transparent portion that transmits the light image of the dark pattern and an outer peripheral portion 104 that is repeatedly formed over the entire circumference and an opaque portion that blocks the light image of the bright pattern. . The outer peripheral portion 104 is formed in a shape similar to the light-dark pattern of the outer peripheral portion 102 of the mask 10a.

Further, the light shielding masks 13A, 15A, 13B,
Another embodiment of 15B is shown in FIG. 4 (b) (c) and FIG.
6 (b) and 6 (c) and FIGS. 6 (b) and 6 (c). FIG.
In the light-shielding masks 13Ab and 15Ab shown in (b), a region formed by repeatedly forming a transparent portion that transmits a light pattern light image and an opaque portion that shields a dark pattern light image is formed in one region of the outer peripheral portion 104. This shows the case where Shading masks 13Bb and 15B shown in FIG.
In b, a region in which a transparent portion that transmits a dark pattern light image and an opaque portion that blocks a bright pattern light image are repeatedly formed is formed in one side region of the outer peripheral portion 104. Shading mask 13A shown in FIG.
In c and 15Ac, a case is shown in which a region formed by repeatedly forming a transparent portion that transmits a light pattern light image and an opaque portion that blocks a dark pattern light image is formed in a symmetrical region of the outer peripheral portion 104. is there. In the light-shielding masks 13Bc and 15Bc shown in FIG. 5C, a region formed by repeatedly forming a transparent portion that allows the light image of the dark pattern to pass therethrough and an opaque portion that blocks the light image of the light pattern is a symmetrical region of the outer peripheral portion 104. It shows the case of forming. In the light-shielding masks 13Ad and 15Ad shown in FIG. 6B, a region formed by a transparent portion (a ring shape) that allows the light image of the bright pattern and the light image of the dark pattern to pass is formed over the entire circumference of the outer peripheral portion 104. This shows the case where In the light-shielding masks 13Ba and 15Ba shown in FIG. 6C, FIG.
Similarly to the case shown in FIG. 3, a case is shown in which an outer peripheral portion 104 is formed with a region in which a transparent portion that transmits a dark pattern light image and an opaque portion that blocks a light pattern light image are repeatedly formed over the entire circumference. It is a thing. 4 (b) (c) and FIG.
The light-shielding masks 13A, 15A, 13B, and 15B shown in (b) and (c) and FIGS. 6B and 6C have a central portion 103 formed of an opaque circular region that shields a pattern other than automatic focusing, and the mask 10. The light-dark pattern (transparent pattern and opaque pattern) having linear edges of light and dark extending substantially radially around the optical axis of the objective lens 3 similar to the pattern formed in FIG. It is formed from the outer peripheral portion 104. These light-shielding masks 13A, 13B, 15A, and 15B are made of a glass mask such as Cr (which forms a dark portion (opaque portion)) or an etching mask, like the mask 10. Further, the light shielding masks 13A, 13B, 15A and 15B may be formed on the light receiving surfaces of the light receiving elements (sensors) 14A, 14B, 16A and 16B.

Therefore, the light receiving elements (sensors) 14A, 16
A is to detect the light amount of the bright pattern that has passed through the light shielding masks 13Aa and 15Aa, and Z of the surface of the object 4 is detected.
The light amount signals 31A and 32A as shown in FIG. 2D are output for the coordinates (focal point Z). The position Z where the light amount signals 31A and 32A are maximum is the in-focus position.
The light receiving elements (sensors) 14B and 16B are the light shielding mask 13.
The light amount of the dark pattern that has passed through Ba and 15Ba is detected, and the light amount signals 31B and 32B as shown in FIG.
Will be output. The position Z where the light amount signals 31B and 32B are the minimum is the in-focus position. Therefore, in the focus position determination circuit 17, which is the computer 21, the light amount signals 31A and 32A shown in FIG. 2D and the light amount signal 3 shown in FIG.
By taking the difference (contrast) from 1B and 32B, the Z coordinate (focal point Z) of the surface of the object 4 is shown in FIG.
The contrast signals 33 (CA), 3 as shown in (f)
4 (CB) can be calculated (extracted). And
The contrast signals 33 (CA) and 34 (CB) are
As shown in FIG. 2F, the peak value is shown at the in-focus position.

Using the masks 10b and 10c shown in FIGS. 4A and 5A, the light-shielding masks 13Ab and 15Ab shown in FIGS. 4B and 5C and FIGS.
13Bb, 15Bb, 13Ac, 15Ac, 13Bc,
Even when 15Bc is used, a similar contrast signal can be obtained. Also, using the mask 10a shown in FIG. 6A, the light-shielding mask 13Ad shown in FIG.
When 15Ad is used, the light receiving element (sensor) 14
A and 16A detect the total amount of light of the light-dark pattern that has passed through the light-shielding masks 13Ad and 15Ad, and output almost constant light amount signals 31A and 32A with respect to the Z coordinate (focus position Z) of the surface of the object 4. Therefore, the light receiving elements (sensors) 14B and 16B are output from the light shielding masks 13Ba and 1Ba, respectively.
The light amount of the dark pattern that has passed through 5Ba is detected, and the light amount signals 31B and 32B as shown in FIG. 2E are output with respect to the Z coordinate (focal point Z) of the surface of the object 4. Become. Therefore, the substantially constant light amount signals 31A and 32A calculated in the focus position determination circuit 17 and those in FIG.
The contrast signal, which is the difference (contrast) between the light amount signals 31B and 32B shown in (e), is the Z of the surface of the object 4.
With respect to the coordinates (focal point Z), a waveform substantially similar to the signal shown in FIG.

In the embodiment shown in FIG. 1, the light-receiving elements (sensors) 14A and 1A including the light-shielding masks 13A and 13B are included.
4B and the light-shielding masks 15A and 15B, and the light-receiving elements (sensors) 16A and 16B are installed at conjugate positions (positions indicating a constant distance) h before and after the in-focus position with respect to the objective lens 3. The circuit 17 includes the light receiving element 14
A contrast signal 33 (CA) indicated by the difference between the light amount signal 31A (S14A) output from A and the light amount signal 31B (S14B) output from the light receiving element 14B, and the light amount signal 32A output from the light receiving element 16A. (S16A)
And the light quantity signal 32B (S1
6B) and the contrast signal 34 (CB)
And are calculated based on, for example, the following equation (1), equation (2), or equation (3), and the difference between the calculated contrast signal 33 (CA) and the contrast signal 34 (CB) is calculated. To be within the allowable range ε (contrast signal 3
3 and the contrast signal 34 coincide with each other within the allowable range ε), and the up-and-down mechanism 18 is drive-controlled (PID control) so as to finely move the surface of the object (sample) 4 in the Z-axis direction.
However, when the calculated difference between the contrast signal 33 and the contrast signal 34 falls within the allowable range (when the contrast signal 33 and the contrast signal 34 match within the allowable range), the object (sample) 4 The surface is determined to be in focus with respect to the objective lens (imaging optical system) 3.

That is, the focus position determination circuit 17 outputs signals (light quantity signals) 31A (S14A) and 32 from the light receiving elements (sensors) 14A, 16A, 14B and 16B, respectively.
A (S16A), 31B (S14B), 32B (S16
Based on B), the positions before and after the in-focus position (shading mask 13
At the positions where A and 13B and the light-shielding masks 15A and 15B are respectively arranged), the contrast signal 3 is calculated based on, for example, the following (Formula 1), (Formula 2) or (Formula 3).
3 (CA) and 34 (CB) are calculated. CA = (S14A-S14B) / (S14A + S14B) CB = (S16A-S16B) / (S16A + S16B) (Equation 1) CA = (S14B-2 * S14A) / S14B CB = (S16B-2 * S16A) / S16B (Number) 2) CA = S14A CB = S16A (Equation 3) Then, the focus position determination circuit 17 which is the computer 21
The vertical mechanism 18 of the sample stage 7 is controlled by PID control using the value of A-CB or (CA-CB) / (CA + CB). Further, the focus position determination circuit 17 uses the contrast signal 3
3 (CA) and the contrast signal 34 (CB) are compared, and when CA is larger than CB + allowable value ε, the up-and-down mechanism 18 of the sample table 7 is drive-controlled to slightly move the sample table 7 downward, and CA Is smaller than CB-permissible value ε, the up-and-down mechanism 18 of the sample table 7 is drive-controlled to slightly move the sample table 7 upward, and when CA is within the CB ± allowable value ε (CA and CB
(When the difference between and is within the allowable value ε)), it is determined that the surface of the object 4 is at the in-focus position of the objective lens 3, and the automatic in-focus operation is ended. That is, the focus position determination circuit 17 finely controls the up-and-down mechanism 18 in the Z-axis direction based on the in-focus information of the surface of the object 4 detected from each of the light receiving elements 14A, 14B, 16A, and 16B of the automatic focusing system. Then, the pattern to be detected is positioned at an appropriate focus position.

That is, when the surface of the object (sample) 4 is at the in-focus position of the objective lens (imaging optical system) 3, the contrast signal 33 at the positions of the light shielding masks 13A and 13B and the light shielding masks 15A and 15B. The contrast signals 34 at the positions are equal. When the surface of the object 4 moves (positions) above the focus position of the objective lens (imaging optical system) 3, the contrast signal 33 detected at the positions of the light shielding masks 13A and 13B becomes larger. On the other hand, when the surface of the object 4 moves (positions) below the focus position of the objective lens (imaging optical system) 3, the contrast signal 34 detected at the positions of the light shielding masks 13A and 13B becomes larger. As described above, the four light shielding masks 13A, 13B and 15
A, 15B and four light-receiving portions are combined with four light-receiving elements (sensors) 14A, 14B and 16A, 16B, and the objective lens (imaging optical system) 3 is not a usual inexpensive exit side telecentric. Even if an optical system is used, the surface of the object (sample) 4 can be focused with high accuracy.

By the way, when an ordinary inexpensive optical system on the exit side, which is not telecentric, is used as the objective lens (imaging optical system) 3, the direction of the chief ray differs depending on the image height as shown in FIG. When a light-receiving element (sensor) including a light-shielding mask is installed at a position other than the in-focus position 100, detection images at front and rear positions 101 and 102 of the in-focus position (FIG. 3B).
It shows in (d). ), The detection magnification changes with respect to the detection image at the in-focus position 100 (shown in FIG. 3C). However, as described above, the projection pattern projected on the surface of the object (sample) 4 is as shown in FIGS. 2 (a), 4 (a) and 5 (a) formed on the mask 10. Since the extension line of the light-dark linear boundary (linear edge) is a light-dark pattern that is repeated in the circumferential direction toward the optical axis of the objective lens 3, even if the detection magnification changes, the angle shape (angle) of the light-dark pattern is changed. Information) will be maintained. Therefore, the light-shielding mask 13 is provided on the light receiving elements 14A and 14B.
A and 13B are used as light-shielding masks 1 on the light receiving elements 16A and 16B.
Even if only the 5A and 15B are installed, even if the detection magnification is changed by using an ordinary inexpensive optical system on the exit side telecentric as the objective lens (imaging optical system) 3, the change in the detection magnification is affected. Without this, it is possible to realize focusing with high accuracy, and as a result, it becomes possible to detect the pattern to be detected formed on the object (sample) 4 with high resolution by the pattern detection image sensor 8. . That is, it is not necessary to use an exit side telecentric optical system with adjustable magnification as the objective lens (imaging optical system) 3, and it is possible to inexpensively and highly accurately measure the in-focus position, that is, to control the in-focus position. In addition, the pattern detection image sensor 8 can detect the detected pattern with high resolution to measure the size of the detected pattern with high accuracy, and inspect the microscopic defects existing on the detected pattern with high accuracy. .

Next, a first modification of the above embodiment will be described with reference to FIG. That is, the light receiving element 14A,
16A corresponding to each of 16A,
As 15A, the outer peripheral portion 104 used for automatic focus detection is formed of a transmissive portion along the entire circumference, and the central portion 103 uses light-shielding masks 13Ad and 15Ad formed of light-shielding portions, which correspond to the respective light-receiving elements 14B and 16B. As the light-shielding masks 13B and 15B installed as the light-shielding masks, light-shielding masks 13Ba and 15Ba that shield a light pattern and transmit a dark pattern are used.
Then, the focus position determination circuit 17 includes the light receiving elements 14A and 14A.
Output signals 31A (S14A), 31B (S14B), 32A (S) output from B, 16A, and 16B, respectively.
16A) and 32B (S16B), the contrast signals 33 (CA) and 34 (CB) at the respective focus positions Z (Z coordinates) are calculated based on the above-described equation (2). In contrast to the above, the light-shielding masks 13Aa and 15Aa that shield the dark pattern and transmit the light pattern are used as the light-shielding masks 13A and 15A installed corresponding to the light-receiving elements 14A and 16A, respectively. , 16
Light-shielding masks 13B, 15 installed corresponding to each of B
As B, the outer peripheral portion 104 used for automatic focus detection may be formed of a transparent portion over the entire circumference, and the central portion 103 may be a light shielding mask formed of a light shielding portion. Also in this case, the focus position determination circuit 17 uses the light receiving elements 14A, 14B, 16
Output signal 31A output from each of A and 16B
(S14A), 31B (S14B), 32A (S16
From A) and 32B (S16B), the contrast signals 33 (CA) and 34 (CB) at the respective focal positions Z (Z coordinates) may be calculated based on the above-mentioned equation (2). According to such a modification, the light shielding masks 13A, 1
5A or the light-shielding masks 13B and 15B does not have a pattern in the outer peripheral portion 104, and thus alignment with the light-dark pattern projected on the surface of the object 4 by the mask 10 can be eliminated. However, as the light-shielding masks 13A and 15A, light-shielding masks 13Aa and 15Aa that shield a dark pattern and transmit a light pattern are used, and as the light-shielding masks 13B and 15B, light-shielding masks 13Ba and 15Ba that shield a light pattern and transmit a dark pattern are used. The sensitivity of the contrast signal will be slightly lowered as compared with the case where it is used.

A second modification of the above embodiment will be described. That is, in the above-described embodiment, the case where four light receiving elements and four light blocking masks are installed is shown. However, the light blocking mask 13A is installed on the light receiving element 14A and the light blocking mask 15A is installed on the light receiving element 16A, and a contrast signal composed of a bright pattern is provided. Focusing with or configuration of light receiving element 14B
To the light-shielding mask 13B, and the light-receiving element 16B to the light-shielding mask 1
Even if 5B is installed and focusing is performed with a contrast signal consisting of a dark pattern, the focusing accuracy can be realized although it is slightly inferior. That is, the light shielding masks 13B and 15
It is not necessary to install B and the light receiving elements (sensors) 14B and 16B. In this case, the focus position determination circuit 17 described above from the output signals S14A and S16A output from the light receiving elements (sensors) 14A and 16A, respectively (Formula 3).
The contrast signals 33 (CA) and 34 (CB) at each focus position Z (Z coordinate) are calculated based on the equation. According to this modification, since the light amount is not normalized, the accuracy is slightly low, but the device configuration can be simplified because the light shielding masks 13B and 15B and the sensors 14B and 16B are not used.

A third modification of the above embodiment will be described. That is, the focus position determination circuit 17, which is the computer 21, uses the light receiving elements (sensors) 14A, 14B, 16
Output signal S14 output from each of A and 16B
From A, S14B, S16A, and S16B, the contrast signals CA and CB at the respective focal positions Z are calculated based on the above-described equation (1), and the value of CA-CB or (CA-CB) / (CA + CB) is calculated. Using sample stand 7
The up / down mechanism 18 is controlled by PID control. According to this modified example, the circuit can be assembled digitally, but it can be configured only with an analog circuit, so that the device configuration can be simplified and high-speed automatic focusing control can be realized. A fourth modification of the above embodiment will be described.
As shown in Fig. 7, the illumination light source 9 may be configured to guide the light emitted from a light source 9'such as a halogen lamp using a fiber 9 ". Further, without using the mask 10, a bright and dark linear boundary ( A partial illumination light source can also realize a light beam of a bright and dark pattern in which an extended line of a linear edge) is repeated in the circumferential direction toward the optical axis of the objective lens 3. That is, a lens optical system provided in the partial illumination light source. Or a mirror optical system, or the liquid crystal display element may be used as the mask. In this case, the shape of the light-shielding pattern formed on the light-shielding mask is projected on the surface of the object 4. It becomes possible to adjust the shape of the pattern (bright and dark pattern in which the extended line of the light-dark linear boundary (linear edge) is repeated in the circumferential direction toward the optical axis of the objective lens 3) to an optimum state. A fifth modified example of No. 1 will be described, that is, the light shielding masks 13A, 13B, 1 shown in FIG.
5A, 15B and light receiving elements (sensors) 14A, 14B, 1
Instead of using 6A and 16B, shading masks 13A and 1A
It can also be realized by using a sensor having sensitivity only to the portions corresponding to the transmissive portions of 3B, 15A and 15B.
In the case of this modification, since it is not necessary to use a light shielding mask, the optical system becomes simple.

Secondly, the automatic focusing method according to the present invention and the pattern detection method including the apparatus and the second apparatus
The embodiment will be described with reference to FIGS. 7 and 9. FIG. 7 and FIG. 9 are block diagrams of an LSI overlay dimension measuring apparatus. First, the measurement of the overlay dimension of the LSI will be described. In recent years, as patterns of LSI wafers have become finer and multilayer resists have been used, step heights have become higher and higher, and the overlay accuracy in each step has become severe at 100 nm or less. For the purpose of measuring the overlay accuracy, a method for measuring the size of a pattern to be detected and an apparatus therefor provided with the automatic focusing method and apparatus therefor according to the present invention, as shown in FIG. A measurement target resist pattern serving as a mask for etching the underlying reference pattern (first pattern) 91 that is the formed measurement target pattern (detection target pattern) 90 and the pattern of the next layer formed thereon. The deviation accuracy from the (second pattern) 92 is measured with an accuracy of 10 nm or less, and the fluctuation of the process state is monitored. Then, this monitor result is fed back to the projection exposure apparatus or the like as necessary. In addition, if the measured positional deviation is large, work such as removing the resist is performed.

Next, the pattern measurement for the measurement target pattern 90 will be described. Measurement target pattern 9 below
The case shown in FIG. 8 as 0 will be described. The overlay dimension measuring apparatus shown in FIGS. 7 and 9 measures (measures) the relative displacement amount of the measurement pattern (second pattern) 92 with respect to the reference pattern (first pattern) 91 having a high step with an accuracy of 10 nm or less. ) Is a device. The LSI superposition device is composed of an illumination light source 9 composed of, for example, a fiber and a halogen lamp, a mask 10 provided at a position conjugate with a focus position on the surface of the object (semiconductor wafer 93) 4, and the illumination light source 9 described above. An object (semiconductor wafer) formed through the objective lens (imaging optical system) 3 with a bright-dark pattern having straight edges of light and dark that are substantially radially extended about the optical axis of the objective lens 3 which is illuminated and formed on the mask 10. 93)
4. An illumination optical system 12 including a condenser lens 11 for projecting an image on the surface of 4 and forming an image, and an objective lens (imaging optical system) 3
And an optical image that is reflected from the object (semiconductor wafer 93) 4 on which the measurement target pattern 90, which is a pattern to be detected, and is imaged through the objective lens (imaging optical system) 3 is detected to form an image. A detection optical system 35 for converting into a signal, and image signals 38a from each of the X-axis and Y-axis pattern detection one-dimensional image sensors 8a and 8b of the detection optical system 35,
Alignment deviation determination unit (calculator) 19 that calculates the relative deviation amount of the measurement pattern (second pattern) 92 with respect to the reference pattern (first pattern) 91 that is a high step pattern based on 38b, and the surface of the object 4. The light-shielding masks 13A and 13B and the light-shielding mask 1 which are provided so that a position separated by a predetermined distance h to the front and rear of the in-focus position is the conjugate position.
5A, 15B and light receiving elements (sensors) 14A, 14B and light receiving elements (sensors) 16A, 1A for detecting the amount of transmitted light.
6B and the pattern contrast at each focus position Z (Z coordinate) based on the signals 31A, 31B, 32A, 32B from the light receiving elements 14A, 14B, 16A, 16B, and the allowable range of the surface of the object 4. A focus position determination circuit 17 for determining the in-focus position, and a vertical mechanism for the sample table 7 for adjusting the focus position Z (Z coordinate) of the surface of the object 4 based on the determination result from the focus position determination circuit 17. 18 and an XY stage system 20 for positioning the object 4
And a control system (computer) 21 including image processing. The detection optical system 35 includes an objective lens system including an objective lens (imaging optical system) 3 and a half mirror 21, a branching optical system 27 which is a beam splitter, and an optical path having a plurality of focal positions. Relay optical systems 37a, 37b having different lengths and including a wedge 36 for fine adjustment of optical path length;
Two image sensors (a TV camera may be used) 8a and 8b that share a synchronization signal corresponding to each optical path are provided. In addition, 41 is an output means which outputs the measured data. Reference numeral 42 denotes an input means composed of a keyboard or the like, which designates calculation ranges 61 and 62 for image processing on the computer 21 and a reference pattern (first pattern) formed on the object (semiconductor wafer 93) 4. ) 91 and resist pattern (second pattern) 92
It is input so that it can be associated with the design information of. Further, the input means 42 is designed such that the computer 21 has design information of the detection optical system 35, an image processing program, and a PID (Proportional-Integral) for focus control.
Differential Input a control program, calculation program, etc. Reference numeral 43 is a display means such as a display for displaying the image signals 38, 38a, 38b detected by the image sensors 8, 8a, 8b and the calculation ranges 61, 62 etc. inputted by the input means 42. An external storage device 44 stores data such as design information of the detection optical system 8 input by the input means or the like and design information of the reference pattern 91 and the resist pattern 92 formed on the object (semiconductor wafer) 4. To do. In the computer 21, there is a memory for storing a CPU and programs,
Along with the control, the misalignment determination unit (image processing) 19
In step 3, arithmetic processing is performed based on the image signals 38, 38a, 38b detected by the image sensors 8, 8a, 8b to calculate the deviation amount of the resist pattern 92 with respect to the reference pattern 91 with a super precision of 10 nm or less. Then, the calculated result may be output by the output means 41 or may be directly output to the projection exposure apparatus via the network 46.

Next, the operation of the pattern measuring device will be described. First, on the sample table 7, for example, the sample 4 of the measurement target pattern 90 in which the resist pattern 92 of the measurement target pattern is formed on the base reference pattern (first pattern) 91 as shown in FIG. The reference plane is placed so that the orientation flat alignment does not cause a deviation in the rotation direction (θ direction). The thickness of the resist pattern 92 and the surface condition of the sample to be adjusted by the automatic focusing system (automatic focusing device) are set on the sample 4 having the measurement target pattern 90 formed on the sample table 7. Various different varieties are possible. Therefore, in the computer 21, as described above, the semiconductor wafer 9 on which the measurement target pattern 90 is formed is formed.
As the sample 3 is placed on the sample table 7, the input means 4
2 inputs information on the type of the measurement target pattern 90. Then, the computer 21 determines the standard of the reference pattern 91 and the resist pattern 92 based on the design information of the reference pattern 91 and the resist pattern 92 formed on the semiconductor wafer corresponding to the type stored in the external storage device 44. Reference pattern 91 corresponding to the product type for the step H0
Then, the thickness of the optical path length fine adjustment wedge 36 corresponding to the change ΔH in level difference between the resist pattern 92 and the resist pattern 92 is calculated. The difference in optical path length between the relay optical systems 37a and 37b is configured to correspond to the standard step difference H0 between the reference pattern 91 and the resist pattern 92. Therefore, the computer 21
Between the relay optical system 37a and the relay optical system 37b, the optical path length fine adjustment wedge 36 is provided so that a difference in optical path length corresponding to a step between the reference pattern 91 and the resist pattern 92 depending on the type of semiconductor wafer can be obtained. The thickness of is adjusted (controlled) and the focus offset value of the automatic focusing system is adjusted (controlled). That is, since the automatic focusing system adjusts a plurality of focusing positions with respect to the measurement target pattern 90, it is also necessary to adjust the focusing focus offset value of the automatic focusing system according to the type of the measurement target pattern 90. Therefore, the computer 21 uses the external storage device 44.
The automatic focusing system by calculating the focusing point offset value of the automatic focusing system corresponding to the standard pattern 90 to be measured based on the design information of the measuring target pattern 90 corresponding to the type stored in It is possible to adjust (control) the in-focus offset value of.

Next, after the object (semiconductor wafer 93) 4 is mounted on the sample table 7, the computer 21 moves the XY stage 20 based on the design information of the measurement pattern 90 to make a high step as shown in FIG. Reference pattern to have (first pattern)
The center position of the measurement target pattern 90 composed of 91 and the measurement pattern (second pattern) 92 is positioned substantially on the optical axis of the objective lens 3. Next, from the image sensor 8a,
When the detected image signal 38a as shown in FIG. 10 is detected,
It is input to the image processing (misalignment determination unit) 19 of the computer 21. In the image processing 19 of the computer 21, the detected image signal 38a thus detected is converted into, for example, a digital signal and converted into a binarized signal with a predetermined threshold value, the center position of the binarized signal is obtained, and the center of the binarized signal is calculated. The XY stage system 20 is moved and positioned so that the position is substantially located at the center of the detection field 51 of the image sensor 8a (optical axis of the objective lens 3). Further, in the computer 21, the detected detection image signal 38a is displayed on the display means 43 such as a display, and the center of the whole of the displayed detection image signal 38a is
The measurement target pattern 90 may be positioned by moving the XY stage system 20 so as to align with the optical axis of the detection optical system 35 set on the screen of the display means 43.

Next, the automatic focusing system will be described. The light emitted from the illumination light source 9 illuminates the mask 10 and has a bright and dark linear edge that extends substantially radially around the optical axis of the objective lens 3 formed on the outer peripheral portion 102 of the mask 10. The light and dark pattern that it has is the condenser lens 11.
Is collected by the object lens (imaging optical system) 3 and the measurement target pattern 9 on the target object (semiconductor wafer 93) 4 is collected.
It is projected and imaged on the surface around 0. The illumination light that has passed through the central portion 101 of the mask 10 is condensed by the condenser lens 11 and illuminates the measurement target pattern 90 on the target object (semiconductor wafer 93) 4 through the objective lens (imaging optical system) 3. The reflected light of the light-dark pattern projected and imaged on the surface around the measurement target pattern 90 on the target object (semiconductor wafer 93) 4 passes through the objective lens 3 and the half mirror 22 and the light blocking masks 13A and 13B and the light blocking mask 15A. ,
An image is formed in the vicinity of an intermediate position (focus point position) between 15B and 15B. The light receiving elements (sensors) 14A and 16A receive the light amount of the light pattern having passed through the light shielding masks 13A and 15A, and the light amount signal 31A as shown in FIG. 2 (d) with respect to the Z coordinate of the surface of the object 4. (S14A), 32A (S16
A) is output. Light receiving element (sensor) 14B, 16B
2 receives the amount of light of the dark pattern that has passed through the light-shielding masks 13B and 15B, and
Light amount signals 31B (S14B), 32 as shown in FIG.
B (S16B) is output. The focus position determination circuit 17
The light amount signals 31A and 32A as shown in FIG. 2D output from the light receiving elements (sensors) 14A and 16A and the light amount signals 31A and 32A output from the light receiving elements (sensors) 14B and 16B are shown in FIG. 2E. The contrast signals 33, 3 as shown in FIG. 2F with respect to the Z coordinate of the surface of the object 4 are obtained by taking the difference (contrast) from the light amount signals 31B, 32B.
Calculate 4. That is, the focus position determination circuit 17 includes output signals (light amount signals) S14A, S16A, S from the light receiving elements (sensors) 14A, 16A, 14B, 16B, respectively.
Based on 14B and S16B, at the positions before and after the in-focus position (the positions where the light-shielding masks 13A and 13B and the light-shielding masks 15A and 15B are arranged), for example, the formula (1) or the formula (2) described above is used. Alternatively, the contrast signals 33 (CA) and 34 (CB) are calculated based on the equation (3).

Then, the focus position determination circuit 17 is set to CA-
The vertical mechanism 18 of the sample table 7 is controlled by PID control using the value of CB or (CA-CB) / (CA + CB). Further, the focus position determination circuit 17 uses the contrast signal 33 (C
A) is compared with the contrast signal 34 (CB) to obtain C
When A is larger than CB + allowable value ε, the up-and-down mechanism 18 of the sample table 7 is drive-controlled to slightly move the sample table 7 downward, and CA
Is smaller than CB-tolerance ε, the up-and-down mechanism 18 of the sample table 7 is drive-controlled to slightly move the sample table 7 upward, and when CA is within the CB ± tolerance ε (the difference between CA and CB). The difference is ±
It is determined that the surface of the object 4 has reached the focusing position of the objective lens 3 (when the value is within the allowable value ε), and the automatic focusing operation is ended. That is, the focus position determination circuit 17 in the computer 21 moves up and down based on the surface focusing information of the object (semiconductor wafer 93) 4 detected from each of the light receiving elements 14A, 14B, 16A, 16B of the automatic focusing system. The mechanism 18 is finely controlled in the Z-axis direction to position the measurement target pattern 90 at an appropriate focus position. in this way,
Measurement target pattern 9 on the target object (semiconductor wafer 93) 4
Since the light-dark pattern projected and imaged on the surface around 0 is a light-dark pattern having straight edges of light and dark extending substantially radially around the optical axis of the objective lens 3, the objective lens (image formation Even if a normal inexpensive exit side non-telecentric optical system is used as the optical system 3, the surface around the measurement target pattern 90 on the object (semiconductor wafer 93) 4 can be focused with high accuracy. .

Next, the reflected light from the pattern 90 to be measured illuminated by the illumination optical system 12 is captured (focused) by the objective lens 3 and divided by the branching optical system 27 which is a half mirror to divide it into the image sensor 8a and the image sensor. 8b and a reference pattern (first pattern) at different in-focus positions at the same time
The detected image signal 38a and the detected image signal 38b indicating 91 and the resist pattern (second pattern) are detected.
The waveforms of the detected image signals 38a and 38b thus detected are shown in FIGS. FIG. 11 shows an image sensor 8a
The waveform in the X direction of the central portion of the measurement target pattern 90 of FIG. 8 detected by FIG. 8 is detected by the image sensor 8b in FIG.
Is a waveform in the X direction at the center of the measurement target pattern 90. In the image sensor 8a, the reference pattern 91 and the image sensor 8b are focused on the resist pattern 92. In the image processing 19 in the computer 21, each of the detected image signals 38a and 38b is converted into a digital signal, and the center position of each pattern is calculated based on the symmetric pattern matching processing. That is, in the symmetry pattern matching process, c is set as the symmetric center position coordinate, the detection signal (detection image signal) is folded back at this symmetric center c, and compared, and the symmetric center position CP with the highest degree of coincidence is obtained.
Is the accurate center position of the detection signal. First,
The folding center c is determined, and the difference (f (c-x) between -x f (c-x) and + x f (c + x) is determined from this folding center c.
x) -f (c + x)) is integrated by changing the value of x in the set calculation range, then the same is changed by changing the value of the folding center c, and folding is performed such that these integrated values show the minimum. The center c is the center position CP of the pattern. Calculator 2
When the center position CPa of the reference pattern 91 is calculated by performing the symmetry pattern matching process in the image processing 19 of No. 1, the data of the reference pattern center calculation range 61 set by being input as the value of the range of x, for example. When calculating the center position CPb of the resist pattern 92 by performing the symmetric pattern matching process, the data of the reference pattern center calculation range 62 that is input and set as the value of the range of x is used. Therefore, in the image processing 19 in the computer 21, the calculated center position of the reference pattern 91 is CPa, and the calculated center position of the resist pattern 92 is CPb.

Next, the computer 21 calculates the positions of the image sensors 8a and 8b based on the difference between the center position CPa of the reference pattern 91 and the center position CPb of the resist pattern 92 based on the following equation (4). The offset value β of the difference is subtracted, and the magnification correction value in the detection optical system 35 including the objective lens 3 configured by the non-telecentric optical system on the exit side (magnification deviation: slight fluctuation of magnification, particularly optical path length according to high step) The value δ obtained by correcting Δα is the reference pattern 91 and the resist pattern 9
It is calculated as the amount of deviation from 2 in the X direction. The Y direction is calculated by the same method. [delta] = ((CPa-CPb) * [Delta] [alpha]) + [beta] (Equation 4) As a result, it is possible to measure the shift amount [delta] between the reference pattern 91 and the resist pattern 92 on the image sensors 8a and 8b in the X and Y directions. Then, the shift amount on the sample (semiconductor wafer) is calculated by the computer 21 by dividing the shift amount δ on the image sensors 8a and 8b by the magnification α of the detection optical system 35 including the objective lens 3. be able to. When the magnification α is 100 times, if the deviation amount δ can be calculated with an accuracy of 1 μm or less on the image sensors 8a and 8b, it will be 1 on the sample (semiconductor wafer).
The measurement can be performed with an accuracy of 0 nm or less. The magnification α is determined by inputting the design information of the detection optical system 35 including the objective lens 3 into the calculator 21 by the input means 42 such as a keyboard. Further, the magnification α and the like can be calculated from the relationship of the above equation (3) from the relationship with the dimension measured by the pattern measuring device using a calibration sample whose dimension is known using SEM or the like. That is, as a result, the computer 21 causes the detection optical system 3 including the objective lens 3 to be detected.
The factor α of 5 can be accurately determined.

From the above, one measurement target pattern 90
The deviation of the pattern with respect to is measured. After that, the process moves to the next measurement target pattern to be measured. Repeat this,
After the measurement is completed for all the patterns to be measured, the sample (semiconductor wafer) is removed and the measurement is completed. According to the present embodiment, it is possible to perform focus position adjustment at low cost, with high accuracy, and at high speed, and to realize high-speed, high-precision alignment deviation measurement.

Next, a third embodiment of the automatic focusing method and the pattern detecting method including the apparatus and the apparatus according to the present invention will be described with reference to FIG. Figure 13 shows the LSI
It is a block diagram of the pattern defect inspection apparatus of. The pattern inspection apparatus for an LSI includes an illumination optical system 1 that illuminates the light from an illumination light source 9 onto an inspection field (inspection region) of an object (semiconductor wafer) 4 via an objective lens 3 and an object (semiconductor wafer) 4. A light-dark pattern provided at a position conjugate with the in-focus position and having substantially no edge in the radial direction (a light-dark pattern having light-dark linear edges extending substantially radially around the optical axis of the objective lens 3) The mask 10 is formed by repeating the above process about 3 times or more in the circumferential direction, the image sensor 8 that receives the reflected image of the illumination light from the objective lens 3 and the object 4, and outputs an image signal. Defect determination circuit 19 'for detecting a pattern defect based on the received image signal
And a light-shielding mask 1 provided such that a position separated by a predetermined distance h above the in-focus position of the object 4 is a conjugate position.
3A, 13B and light receiving element 14 for detecting the amount of transmitted light
A, 14B and light-shielding masks 15A, 15B provided so as to be conjugate positions at a predetermined distance h below the in-focus position of the object 4, and light-receiving elements 16A, 16B for detecting the amount of transmitted light, Elements 14A, 14B,
Based on the focus position determination circuit 17 that determines the in-focus position of the object 4 by calculating the contrast at each focus position Z based on the light amount signals from 16A and 16B, and the determination result from the focus position determination circuit 17. It comprises an up-and-down mechanism 18 of the sample table 7 for adjusting the focus position of the object 4, an XY stage 20 for scanning the object 4, and an overall control computer 21.

In this pattern inspection apparatus, an object (semiconductor wafer to be inspected) 4 is mounted on the sample stage 7, and then the XY stage 20 is scanned by a command from the overall control computer 21.
The focus position determination circuit 17 includes light receiving elements 14A, 14B, 1
Output signal S14 output from each of 6A and 16B
From A, S14B, S16A, and S16B, the contrast signals CA and CB at the respective focus positions are calculated based on, for example, the above-described equation (1), and automatic focus control is always performed when the XY stage 20 is scanned. CA is C
If it is larger than B + tolerance ε, the vertical mechanism 18 of the sample table 7
When CA is smaller than CB−allowable value ε, the up / down mechanism 18 of the sample table 7 is moved up so that CA is CB.
If the value is within ± allowable value ε, the vertical mechanism 18 is not moved. By repeating this operation during scanning, automatic focus control is always applied. Then, the reflected light or transmitted light from the pattern area for detection on the object (semiconductor wafer to be inspected) 4 corresponding to the central portion 101 of the mask 10 is imaged by the objective lens 3. The image sensor 8 receives the formed reflected light image or transmitted light image and obtains a grayscale image signal of a circuit pattern such as a wiring pattern existing in the pattern area for detection. In addition, a ring-shaped illumination is applied as the illumination light, the specular reflection light obtained from the circuit pattern through the objective lens 3 is blocked, and the diffracted reflection light image is received by the image sensor 8. A grayscale image signal is obtained. Defects existing in the circuit pattern can be detected by performing chip comparison or cell comparison on the obtained grayscale image signals.

In any case, the objective lens (imaging optical system)
Even if the detection magnification is changed by using an ordinary inexpensive optical system whose exit side is non-telecentric as 3, the focusing can be realized with high accuracy without being affected by the change in the detection magnification. As a result, the image sensor 8 can detect the grayscale image signal of the circuit pattern formed on the semiconductor wafer with high resolution, and the minute defect existing on the circuit pattern can be detected. In this embodiment, the half mirror 23, which is a branch optical system, is installed between the condenser lens 11 and the mask 10. According to this embodiment, the mask 10 and the light blocking mask 15
Since A and 15B are installed close to each other, the influence of drift is small, and the lens optical system includes the mask 10 and the light-shielding mask 15.
Adjustment is easy because it is not between A and 15B.

As described above, according to this embodiment,
Inexpensive, highly accurate, and fast focusing,
As a result, high-speed and highly accurate pattern defect inspection can be realized. Next, a first modification of this embodiment will be described. The mask 10 and the light-shielding mask 13 shown in FIG.
Instead of A, 13B (15A, 15B), each pattern of the mask 10c and the light shielding masks 13Ac, 13Bc shown in FIG. 5 may be used. According to this modification, since a plurality of fan-shaped masks are used, the linear image sensor 8 can be arranged in a plurality of fan-shaped gaps, and the field of view used by the linear image sensor 8 can be widened. .

The automatic focusing method and apparatus according to the present invention may have the configuration shown in FIG. That is, a light-dark pattern having substantially no edge in the radial direction (a light-dark pattern having a straight edge of light and dark extending substantially radially around the optical axis of the objective lens 3) is provided about three times or more in the circumferential direction. As a repeatedly formed mask, FIG.
10A and 10B, which are half of the structure shown in FIG. This is a case where 15A and 15B are installed. In the case of this embodiment, each of the light receiving elements 16A and 16B is composed of two light receiving elements 16AA, 16AB, 16BA and 16BB corresponding to each of the masks 10A and 10B. Then, the focus position determination circuit 17 includes the light receiving element 16
Light amount signal 141A and light receiving element 16BA obtained from AA
The contrast signal CA ′ of the bright-dark pattern projected by the mask 10A based on the following (Equation 5) or (Equation 6) from the difference signal with the light amount signal 141B obtained from
Similarly, the light amount signal 142A obtained from the light receiving element 16AB and the light amount signal 1 obtained from the light receiving element 16BB are calculated similarly.
The contrast signal CB ′ of the light-dark pattern projected by the mask 10B is calculated from the difference signal with respect to 42B based on the following equation (5) or equation (6), and CA ′ is C
If it is larger than B ′ + allowable value ε ′, the vertical movement mechanism 18 of the sample table 7 is drive-controlled to be slightly moved downward, and CA ′ is CB′−.
If it is smaller than the allowable value ε ', the vertical movement mechanism 18 of the sample table 7
When CA 'is within CB' ± tolerance ε '(when CA' and CB 'match within tolerance ε'), the surface of the target object 4 is aligned. It is determined that the focus position is reached, and the automatic focusing operation is ended.

CA ′ = (141A-141B) / (141A + 141B) CB ′ = (142A-142B) / (142A + 142B) (Equation 5) CA ′ = (141B-2 × 141A) / 141B CB ′ = (142B-2) × 142A) / 142B (Equation 6) In the case of this embodiment, the light and dark patterns formed on each of the masks 10A and 10B are projected onto different areas of the surface of the object 4 through the objective lens 3 to receive the light receiving elements 16AA and 16A.
The 6BA and the light receiving elements 16AB and 16BB respectively receive the reflected light images of the bright and dark patterns of different regions formed through the objective lens 3. Therefore, when the pattern density or the like changes in the different area on the surface of the object 4 and the reflection characteristic changes, the light receiving elements 16AA and 16B are received.
A and the light receiving elements 16AB and 16BB are the light-shielding mask 15.
The amount of light received through each of A and 15B changes, and C
Even if A ′ coincides with CB ′, the surface of the object 4 will not be in the in-focus position. That is, in the case of this embodiment, it is easily affected by the fluctuation of the reflection characteristic on the surface of the object 4. Therefore, when the object 4 is applied to the surface of which the reflection characteristic does not change, the focusing can be realized with high accuracy as in the above embodiment.

[0052]

According to the present invention, the surface of the object or sample can be measured without using an expensive exit side telecentric optical system capable of adjusting magnification as a detection optical system including an imaging optical system (objective lens). The effect that the focusing can be realized with high accuracy is achieved.

Further, according to the present invention, as a detection optical system including an imaging optical system (objective lens), an expensive telephotocentric optical system capable of adjusting the magnification is not used, and a photoelectric conversion element is expensive. It is possible to achieve highly accurate focusing of the surface of the object or the sample without using the one-dimensional linear image sensor.
Further, according to the present invention, as the detection optical system including the imaging optical system (objective lens), the surface of the object or the sample is focused with high accuracy without using an expensive exit side telecentric optical system capable of adjusting the magnification. As a result, the optical image of the pattern to be detected formed on the surface of the object or sample is focused and focused by the imaging optical system to form a clear image signal of the pattern to be detected. Can be detected to inspect a fine defect on the pattern to be detected with high reliability. Further, according to the present invention, an imaging optical system (objective lens)
As a detection optical system that includes a high-accuracy adjustable exit side telecentric optical system, the surface of the object or sample can be focused with high accuracy, and as a result, the surface of the object or sample can be highly focused. A plurality of patterns are formed by detecting the clear image signal of the pattern to be detected by focusing the optical image of the pattern to be detected formed by a plurality of steps The effect that the dimension between the two can be measured with high accuracy is achieved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of a pattern detection device including an automatic focusing device according to the present invention.

2A is a light-dark pattern formed on a mask, FIG. 2B is a light-shielding pattern formed on a light-shielding mask, and FIG. 2D is an amount of light received by each light-receiving element. And (f) is a diagram showing a contrast signal waveform with respect to the focus position Z.

FIG. 3A shows that the detection magnification changes between the in-focus position and the positions before and after it, when the exit side is configured by a non-telecentric optical system as an objective lens (imaging optical system), and FIG. ) (C) and (d) show detection images at the focus position and positions before and after it, and (e) is a view showing a light-shielding pattern formed on the light-shielding mask.

4A shows a light-dark pattern different from that shown in FIG. 2A formed on the mask, and FIGS. 4B and 4C are formed on the light-shielding mask in correspondence with the light-dark pattern shown in FIG. It is a figure which shows the light shielding pattern.

5A shows a light-dark pattern different from that shown in FIGS. 2A and 4A formed on a mask, FIG.
(B) (c) is a figure which shows the light-shielding pattern formed in the light-shielding mask corresponding to the light-dark pattern shown in (a).

6A is a diagram showing the same light-dark pattern as that shown in FIG. 2A formed on a mask, and FIGS. 6B and 6C are diagrams showing light-shielding patterns formed on a light-shielding mask.

FIG. 7 is a schematic configuration diagram showing a second embodiment of the pattern detection device including the automatic focusing device according to the present invention.

8A and 8B are views showing a pattern to be measured which includes a reference pattern having a high level difference formed on a semiconductor wafer and a resist pattern. FIG. 8A is a plan view and FIG. 8B is a front sectional view.

FIG. 9 is a schematic configuration view different from FIG. 7 showing a second embodiment of the pattern detection apparatus including the automatic focusing device according to the present invention.

10 is a diagram showing a detected image signal waveform detected by the image sensor shown in FIGS. 7 and 9. FIG.

11 is a center position C of a reference pattern based on a detected image signal detected by the image sensor shown in FIGS. 7 and 9;
It is explanatory drawing for calculating Pa.

12 is an explanatory diagram for calculating a center position CPb of a resist pattern based on a detection image signal detected by the image sensor shown in FIGS. 7 and 9. FIG.

FIG. 13 is a schematic configuration diagram showing a third embodiment of a pattern detection device including an automatic focusing device according to the present invention.

FIG. 14 is a schematic configuration diagram showing another embodiment of the automatic focusing device according to the present invention.

FIG. 15 is a schematic configuration diagram showing a conventional automatic focusing device for one-dimensionally repeating fringe pattern projection.

FIG. 16 is a diagram showing a relationship between a conventional one-dimensionally repeated stripe pattern and light-receiving pixels of a one-dimensional linear image sensor.

FIG. 17 is a diagram showing a contrast signal waveform detected by each one-dimensional linear image sensor arranged at a position before and after a conventional focusing point.

FIG. 18 is a diagram showing a relationship between a contrast signal difference signal detected by each conventional one-dimensional linear image sensor and a focus position Z (Z coordinate).

[Explanation of symbols]

3 ... Objective lens (imaging optical system), 4 ... Object (sample), 7 ... Sample stand 8, 8a, 8b ... Image sensor, 9 ... Illumination light source 10, 10a, 10b, 10c, 10A, 10B ... Mask 11 ... Condensing lens, 12 ... Illumination optical system 13A, 13Aa to 13Ad, 13B, 13Ba to 13
Bc, 15A, 15Aa to 15Ad, 15B, 15Ba
-15Bc ... Shading mask 14A, 14B, 16A, 16B ... Light receiving element (sensor) that detects the amount of transmitted light 17 ... Focus position determination circuit, 18 ... Vertical mechanism, 19 ... Misalignment determination unit (image processing) in computer 19 '... Defect detection unit (image processing) in the computer, 2
0 ... XY stage 21 ... Calculator (overall control unit), 22-27 ... Half mirror (branching optical system) 35 ... Detection optical system, 36 ... Optical path length adjusting wedge 37a, 37b ... Relay optical system, 41 ... Output means ,
42 ... Input means 43 ... Display means (display), 44 ... External storage device 90 ... Measurement target pattern, 91 ... Reference pattern 92 ... Measurement pattern (resist pattern)

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] February 1, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of a pattern detection device including an automatic focusing device according to the present invention.

2A is a light-dark pattern formed on a mask, FIG. 2B is a light-shielding pattern formed on a light-shielding mask, and FIG. 2D is an amount of light received by each light-receiving element. And (f) is a diagram showing a contrast signal waveform with respect to the focus position Z.

FIG. 3A shows that the detection magnification changes between the in-focus position and the positions before and after it, when the exit side is configured by a non-telecentric optical system as an objective lens (imaging optical system), and FIG. ) (C) (d) show detection images at the in-focus position and the positions before and after it, and (e)
(F) is a figure which shows the light-shielding pattern formed in the light-shielding mask.

4A shows a light-dark pattern different from that shown in FIG. 2A formed on the mask, and FIGS. 4B and 4C are formed on the light-shielding mask in correspondence with the light-dark pattern shown in FIG. It is a figure which shows the light shielding pattern.

5A shows a light-dark pattern different from that shown in FIGS. 2A and 4A formed on a mask, FIG.
(B) (c) is a figure which shows the light-shielding pattern formed in the light-shielding mask corresponding to the light-dark pattern shown in (a).

6A is a diagram showing the same light-dark pattern as that shown in FIG. 2A formed on a mask, and FIGS. 6B and 6C are diagrams showing light-shielding patterns formed on a light-shielding mask.

FIG. 7 is a schematic configuration diagram showing a second embodiment of the pattern detection device including the automatic focusing device according to the present invention.

8A and 8B are views showing a pattern to be measured which includes a reference pattern having a high level difference formed on a semiconductor wafer and a resist pattern. FIG. 8A is a plan view and FIG. 8B is a front sectional view.

FIG. 9 is a schematic configuration view different from FIG. 7 showing a second embodiment of the pattern detection apparatus including the automatic focusing device according to the present invention.

10 is a diagram showing a detected image signal waveform detected by the image sensor shown in FIGS. 7 and 9. FIG.

11 is a center position C of a reference pattern based on a detected image signal detected by the image sensor shown in FIGS. 7 and 9;
It is explanatory drawing for calculating Pa.

12 is an explanatory diagram for calculating a center position CPb of a resist pattern based on a detection image signal detected by the image sensor shown in FIGS. 7 and 9. FIG.

FIG. 13 is a schematic configuration diagram showing a third embodiment of a pattern detection device including an automatic focusing device according to the present invention.

FIG. 14 is a schematic configuration diagram showing another embodiment of the automatic focusing device according to the present invention.

FIG. 15 is a schematic configuration diagram showing a conventional automatic focusing device for one-dimensionally repeating fringe pattern projection.

FIG. 16 is a diagram showing a relationship between a conventional one-dimensionally repeated stripe pattern and light-receiving pixels of a one-dimensional linear image sensor.

FIG. 17 is a diagram showing a contrast signal waveform detected by each one-dimensional linear image sensor arranged at a position before and after a conventional focusing point.

FIG. 18 is a diagram showing a relationship between a contrast signal difference signal detected by each conventional one-dimensional linear image sensor and a focus position Z (Z coordinate).

[Explanation of reference numerals] 3 ... Objective lens (imaging optical system), 4 ... Object (sample), 7 ... Sample stage 8, 8a, 8b ... Image sensor, 9 ... Illumination light source 10, 10a, 10b, 10c, 10A 10B ... Mask 11 ... Condensing lens 12 ... Illumination optical system 13A, 13Aa-13Ad, 13B, 13Ba-13
Bc, 15A, 15Aa to 15Ad, 15B, 15Ba
-15Bc ... Shading mask 14A, 14B, 16A, 16B ... Light receiving element (sensor) that detects the amount of transmitted light 17 ... Focus position determination circuit, 18 ... Vertical mechanism, 19 ... Misalignment determination unit (image processing) in computer 19 '... Defect detection unit (image processing) in the computer, 2
0 ... XY stage 21 ... Calculator (overall control unit), 22-27 ... Half mirror (branching optical system) 35 ... Detection optical system, 36 ... Optical path length adjusting wedge 37a, 37b ... Relay optical system, 41 ... Output means ,
42 ... Input means 43 ... Display means (display), 44 ... External storage device 90 ... Measurement target pattern, 91 ... Reference pattern 92 ... Measurement pattern (resist pattern)

Claims (21)

[Claims] 1. A light-dark pattern having straight light-dark edges extending substantially radially from an optical axis of the imaging optical system through an imaging optical system is projected onto an object and reflected from the object. The light-dark pattern image obtained through the image-forming optical system is received by photoelectric conversion means and converted into a light-dark pattern contrast signal, and the focusing point of the image-forming optical system is adjusted based on the converted light-dark pattern contrast signal. An automatic focusing method, characterized in that the object is controlled relative to a position. 2. A light-dark pattern having straight linear edges of light and dark extending substantially radially from an optical axis of the imaging optical system through an imaging optical system is projected onto the object and reflected from the object. The image of the dark pattern among the images of the bright and dark pattern obtained through the imaging optical system is received by the first photoelectric conversion element and converted into the first signal corresponding to the dark pattern, and at the same time, the image of the bright pattern is formed. The object is relatively moved to the focus position of the imaging optical system based on the contrast signal of the light-dark pattern obtained by receiving the light by the second photoelectric conversion element and converting it into the second signal corresponding to the light pattern. An automatic focusing method characterized by controlling. 3. A light-dark pattern having straight linear edges of light and dark extending substantially radially from an optical axis of the imaging optical system through an imaging optical system is projected onto the object and reflected from the object. The image of the bright and dark pattern obtained through the image forming optical system is received by each of the first and second photoelectric conversion means arranged at a conjugate position before and after the in-focus position to receive the first and second bright and dark images. It is characterized in that the object is converted into a contrast signal of a pattern, and the object is relatively controlled at a focus position of the imaging optical system based on the converted contrast signals of the first and second bright and dark patterns. Automatic focusing method. 4. A light-dark pattern having straight linear edges of light and dark extending substantially radially from an optical axis of the image forming optical system is projected on the object and reflected from the object. The image of the bright and dark pattern obtained through the image forming optical system is received by the first photoelectric conversion elements constituting each of the first and second photoelectric conversion means arranged at conjugate positions before and after the focus position. And then converted into a first signal corresponding to the dark pattern, and the second signal corresponding to the bright pattern is received by the second photoelectric conversion element constituting each of the first and second photoelectric conversion means. Converted to the first and second
The imaging optical system based on the contrast signals of the first and second bright and dark patterns obtained from the first and second signals in each of the photoelectric conversion means in correspondence with the first and second photoelectric conversion means. The automatic focusing method, characterized in that the object is controlled relatively to the in-focus position. 5. A light-dark pattern having straight light-dark edges extending substantially radially from the optical axis of the imaging optical system is projected onto the periphery of a detected pattern region on an object through the imaging optical system. Then, the image of the light-dark pattern reflected from the periphery and obtained through the image-forming optical system is received by the photoelectric conversion means and converted into a contrast signal of the light-dark pattern, and based on the converted contrast signal of the light-dark pattern, Focusing step for relatively controlling the object to the in-focus position of the imaging optical system, and light obtained through the imaging optical system from the detected pattern region on the object controlled in the focusing step. And a detected pattern detecting step of detecting an image signal of the detected pattern by receiving light from the detected photoelectric conversion means. 6. A light-dark pattern having straight line edges of light and dark extending substantially radially from an optical axis of the imaging optical system through an imaging optical system to the periphery of a pattern area to be detected on an object. Then, of the bright and dark pattern images reflected from the periphery and obtained through the imaging optical system, the dark pattern image is received by the first photoelectric conversion element and converted into a first signal corresponding to the dark pattern. Along with the second bright pattern image
The relative control of the object to the focus position of the imaging optical system based on the contrast signal of the light-dark pattern obtained by receiving the light by the photoelectric conversion element and converting it into the second signal corresponding to the light pattern. Focusing step and detecting the image signal of the detected pattern by receiving light obtained through the imaging optical system from the detected pattern area on the object controlled in the focusing step by the photoelectric conversion means for detection And a detected pattern detecting step. 7. A light / dark pattern having straight edges of light and dark extending substantially radially from an optical axis of the imaging optical system is projected to the periphery of a pattern area to be detected on an object through the imaging optical system. Then, the image of the bright and dark pattern reflected from the periphery and obtained through the imaging optical system is received by each of the first and second photoelectric conversion units arranged at conjugate positions before and after the in-focus position. The first and second converted contrast signals of the first and second light and dark patterns, and the converted first and second
A focusing step for relatively controlling the object to a focusing position of the imaging optical system based on the contrast signal of the bright and dark pattern of, and a detected pattern area on the object controlled in the focusing step. And a detected pattern detecting step of detecting the image signal of the detected pattern by receiving the light obtained through the imaging optical system by the photoelectric conversion means for detection. 8. A light-dark pattern having straight linear edges of light and dark extending substantially radially from an optical axis of the imaging optical system is projected onto the periphery of a detected pattern region on an object through the imaging optical system. Then, the image of the bright and dark pattern reflected from the periphery and obtained through the image forming optical system constitutes each of the first and second photoelectric conversion means arranged at conjugate positions before and after the in-focus position. The first photoelectric conversion element receives the light and converts it into a first signal corresponding to the dark pattern, and the second photoelectric conversion element constituting each of the first and second photoelectric conversion means receives the light and receives the bright pattern. To a second signal corresponding to the first and second photoelectric conversion means and obtained from the first and second signals in each of the first and second photoelectric conversion means in correspondence with the first and second photoelectric conversion means. Contrast of 1st and 2nd light and dark patterns Focusing step of relatively controlling the object to the focus position of the imaging optical system based on the signal, and the imaging optical system from the detected pattern area on the object controlled in the focusing step. And a detected pattern detecting step of detecting the image signal of the detected pattern by receiving light obtained through the photoelectric conversion means for detection by the detected photoelectric conversion means. 9. An imaging optical system is provided to the periphery of a pattern area to be detected in which a first pattern and a second pattern having a height difference are formed on a sample, and substantially from the optical axis of the imaging optical system. A light-dark pattern having a straight edge of light and dark that radially extends to is projected, and the image of the light-dark pattern which is reflected from the periphery and obtained through the imaging optical system is received by the photoelectric conversion means to form a contrast signal of the light-dark pattern. And a focusing step of relatively controlling the sample to a focusing position of the imaging optical system based on the converted contrast signal of the light-dark pattern, and the focusing step on the sample controlled in the focusing step. The optical images from the first and second patterns in the detected pattern region are imaged through the imaging optical system by a detection optical system having an optical path length difference according to the height difference, and photoelectric conversion is performed. The image signal of the first and second patterns is detected by receiving light by the replacement means,
The center position of the first pattern is calculated from the image signal of the first pattern, the center position of the second pattern is calculated from the image signal of the second pattern, and the calculated center of the first pattern is calculated. A detected pattern detecting step of calculating a dimension between the center of the second pattern and the center of the second pattern. 10. An imaging optical system is provided to the periphery of a pattern area to be detected in which a first pattern and a second pattern having a height difference are formed on a sample, and substantially from the optical axis of the imaging optical system. A light-dark pattern having a straight edge of light and dark that radially extends on the image, and the image of the dark pattern among the image of the light-dark pattern obtained from the periphery and reflected through the imaging optical system is converted into a first photoelectric conversion element. And a light-dark pattern obtained by converting a light-pattern image into a first signal corresponding to a dark pattern, and a light-pattern image received by a second photoelectric conversion element and converted into a second signal corresponding to a light pattern. Focusing step of relatively controlling the sample to a focusing position of the imaging optical system based on the contrast signal of the image forming optical system, and the first and the first and the second patterns in the detected pattern area on the sample controlled in the focusing step. The optical image from the second pattern is imaged through the imaging optical system by the detection optical system having an optical path length difference according to the height difference, and is received by the photoelectric conversion means to receive the first and second patterns. Detect the image signal,
The center position of the first pattern is calculated from the image signal of the first pattern, the center position of the second pattern is calculated from the image signal of the second pattern, and the calculated center of the first pattern is calculated. A detected pattern detecting step of calculating a dimension between the center of the second pattern and the center of the second pattern. 11. An imaging optical system is provided to the periphery of a pattern area to be detected in which a first pattern and a second pattern having a height difference are formed on a sample, and substantially from the optical axis of the imaging optical system. An image of a bright-dark pattern obtained by projecting a bright-dark pattern having radially extending light-dark linear edges on the periphery and being reflected from the periphery and obtained through the imaging optical system is arranged at a conjugate position before and after a focus position. Each of the first and second photoelectric conversion means receives the light and converts it into the contrast signals of the first and second light and dark patterns, and based on the converted contrast signals of the first and second light and dark patterns, A focusing step of relatively controlling the sample to a focus position of the imaging optical system; and a step of controlling the sample from the first and second patterns in the detected pattern area on the sample controlled by the focusing step. An optical image is formed through the image forming optical system by a detection optical system having an optical path length difference according to the height difference and is received by photoelectric conversion means to detect image signals of first and second patterns,
The center position of the first pattern is calculated from the image signal of the first pattern, the center position of the second pattern is calculated from the image signal of the second pattern, and the calculated center of the first pattern is calculated. A detected pattern detecting step of calculating a dimension between the center of the second pattern and the center of the second pattern. 12. An imaging optical system is provided to the periphery of a pattern area to be detected in which a first pattern and a second pattern having a height difference are formed on a sample, and substantially from the optical axis of the imaging optical system. An image of a bright-dark pattern obtained by projecting a bright-dark pattern having radially extending light-dark linear edges on the periphery and being reflected from the periphery and obtained through the imaging optical system is arranged at a conjugate position before and after the in-focus position. The first photoelectric conversion element constituting each of the first and second photoelectric conversion means receives the light and converts it into the first signal corresponding to the dark pattern, and at the same time, the first photoelectric conversion means of the first and second photoelectric conversion means. The second photoelectric conversion element constituting each receives the light and converts it into the second signal corresponding to the bright pattern, and the first and second signals in each of the first and second photoelectric conversion means are converted into the above-mentioned signals. Compatible with the first and second photoelectric conversion means A focusing step of relatively controlling the sample to a focusing position of the imaging optical system based on the contrast signals of the first and second bright and dark patterns obtained by the above; and the focusing step controlled by the focusing step. Optical images from the first and second patterns in the detected pattern region on the sample are imaged through the imaging optical system by a detection optical system having an optical path length difference according to the height difference, and photoelectric conversion means. To detect the image signals of the first and second patterns,
The center position of the first pattern is calculated from the image signal of the first pattern, the center position of the second pattern is calculated from the image signal of the second pattern, and the calculated center of the first pattern is calculated. A detected pattern detecting step of calculating a dimension between the center of the second pattern and the center of the second pattern. 13. A light-dark pattern projection optical system for projecting a light-dark pattern having straight line edges of light and dark extending substantially radially from an optical axis of the image forming optical system through an image forming optical system on an object. Photoelectric conversion means for receiving an image of a light-dark pattern reflected from the object by the light-dark pattern projection optical system and obtained through the imaging optical system by the light-dark pattern projected by the light-dark pattern to convert it into a contrast signal of the light-dark pattern; An automatic focusing apparatus comprising: a control unit that relatively controls the object at a focus position of the imaging optical system based on the contrast signal of the light-dark pattern converted by the photoelectric conversion unit. 14. A light-dark pattern projection optical system which projects a light-dark pattern having straight edges of light and dark extending substantially radially from an optical axis of the imaging optical system through an imaging optical system on an object, A first image corresponding to the dark pattern by receiving the image of the dark pattern among the images of the dark pattern reflected from the object by the bright and dark pattern projection optical system and obtained from the object through the imaging optical system. First and second photoelectric conversion elements for converting the first photoelectric conversion element to a second signal corresponding to the bright pattern by receiving the image of the bright pattern and converting the first signal to the second signal corresponding to the bright pattern. Control for relatively controlling the object at the focus position of the imaging optical system based on the contrast signal of the light-dark pattern obtained from the signal of No. 2 and the second signal converted from the second photoelectric conversion element. Means and Automatic focusing apparatus characterized by comprising. 15. A light-and-dark pattern projection optical system for projecting a light-dark pattern having straight line edges of light and dark extending substantially radially from an optical axis of the imaging optical system through an imaging optical system on an object. An image of a light-dark pattern reflected from the object by the light-dark pattern projected by the light-dark pattern projection optical system and obtained through the imaging optical system is received by each and contrast signals of the first and second light-dark patterns are received. The first and second photoelectric conversion means arranged at the conjugate positions before and after the in-focus position so as to be converted into, and the contrast signal of the first bright-dark pattern converted by the first photoelectric conversion means, and Control means for relatively controlling the object at a focus position of the imaging optical system based on the contrast signal of the second bright-dark pattern converted by the second photoelectric conversion means. Automatic focusing device according to claim. 16. A light-dark pattern projection optical system for projecting a light-dark pattern having straight linear edges of light and dark extending substantially radially from an optical axis of the imaging optical system through an imaging optical system on an object. A first signal corresponding to the dark pattern, which is received by the dark pattern of the image of the bright and dark pattern reflected from the object by the bright and dark pattern projection optical system and obtained from the object through the imaging optical system. And a second photoelectric conversion element for receiving the bright pattern and converting it into a second signal corresponding to the bright pattern. The first and second signals are converted into first and second photoelectric conversion elements. First and second photoelectric conversion means arranged at conjugate positions before and after the focus position for obtaining the contrast signal of the second bright-dark pattern, and first photoelectric conversion means obtained from each of the first and second photoelectric conversion means. 1st and 1st Automatic focusing apparatus characterized by comprising a control means for relatively controlling the object in-focus position of the imaging optical system based on a contrast signal of the light-dark pattern. 17. An imaging optical system for forming a light image of a detected pattern from a detected pattern region on an object, and a light image of the detected pattern formed by the imaging optical system. And a photoelectric conversion means for detection for detecting an image signal of a detected pattern by means of the imaging optical system for the periphery of the detected pattern area on the object. A light-dark pattern projection optical system that projects a light-dark pattern having straight edges of light and dark that extend substantially radially from the optical axis of the system, and the light-dark pattern projected by the light-dark pattern projection optical system reflects from the object. Photoelectric conversion means for receiving an image of a light-dark pattern obtained through the imaging optical system and converting it into a contrast signal of the light-dark pattern, and a light-dark pattern controller converted by the photoelectric conversion means. A pattern detection apparatus comprising: a focusing device having a control unit that relatively controls the object at a focus position of the imaging optical system based on a trust signal. 18. An image forming optical system for forming a light image of a detected pattern from a detected pattern region on an object, and a light image of the detected pattern formed by the image forming optical system. And a photoelectric conversion unit for detection for detecting an image signal of a detection pattern, which is substantially radial from an optical axis of the imaging optical system through the imaging optical system with respect to the object. A light-dark pattern projection optical system for projecting a light-dark pattern having straight dark and light edges, and a light-dark pattern projected by the light-dark pattern projection optical system to be reflected from the object and obtained through the imaging optical system. Among the images of the light and dark patterns, the image of the dark pattern is received and converted into the first signal corresponding to the dark pattern,
First and second photoelectric conversion elements for receiving an image of a bright pattern and converting it into a second signal corresponding to the bright pattern;
Of the first signal converted from the photoelectric conversion element and the second signal converted from the second photoelectric conversion element based on the contrast signal of the light-dark pattern A pattern detecting apparatus comprising: a focusing device having a control unit that relatively controls the object. 19. An image forming optical system for forming a light image of a detected pattern from a detected pattern region on an object, and a light image of the detected pattern formed by the image forming optical system. And a photoelectric conversion unit for detection for detecting an image signal of a detection target pattern, which is substantially radial from the optical axis of the imaging optical system through the imaging optical system with respect to the object. A light-dark pattern projection optical system for projecting a light-dark pattern having straight dark and light edges, and a light-dark pattern projected by the light-dark pattern projection optical system to be reflected from the object and obtained through the imaging optical system. First and second photoelectric conversion means arranged at conjugate positions before and after the in-focus position so that the image of the light-dark pattern is received by each and converted into the contrast signals of the first and second light-dark patterns. , Focusing point of the imaging optical system based on the contrast signal of the first light-dark pattern converted by the first photoelectric conversion means and the contrast signal of the second light-dark pattern converted by the second photoelectric conversion means A pattern detection device comprising a focusing device having a control means for controlling the object relative to a position. 20. An imaging optical system for forming a light image of a detected pattern from a detected pattern region on an object, and a light image of the detected pattern formed by the imaging optical system. And a photoelectric conversion unit for detection for detecting an image signal of a detection pattern, which is substantially radial from an optical axis of the imaging optical system through the imaging optical system with respect to the object. A light-dark pattern projection optical system for projecting a light-dark pattern having straight dark and light edges, and a light-dark pattern projected by the light-dark pattern projection optical system to be reflected from the object and obtained through the imaging optical system. A first of the light-dark pattern images, which receives the dark pattern and converts it into a first signal corresponding to the dark pattern.
Photoelectric conversion element and a second photoelectric conversion element for receiving the bright pattern and converting it into a second signal corresponding to the bright pattern, and the first and second bright and dark patterns from the first and second signals. First and second photoelectric conversion means arranged at conjugate positions before and after the in-focus position for obtaining the contrast signal of
A first obtained from each of the first and second photoelectric conversion means
And a focusing device having a control means for relatively controlling the object at a focusing position of the imaging optical system based on a contrast signal of the second bright-dark pattern. . 21. An optical image from the first and second patterns in a detected pattern area, in which a first pattern and a second pattern having a height difference are formed on a sample, is passed through the imaging optical system to obtain the height. A detection optical system that forms an image with an optical path length difference according to the difference, receives the light by photoelectric conversion means, and detects the image signals of the first and second patterns, and the first optical system converted by the photoelectric conversion means. The center position of the first pattern is calculated from the image signal of the pattern, the center position of the second pattern is calculated from the image signal of the second pattern converted by the photoelectric conversion means, and the calculated first position is calculated. A pattern detecting device having a calculating means for calculating a dimension between a center of a pattern and a center of a second pattern, wherein the image forming optical system is provided to the periphery of the detected pattern region through the image forming optical system. System A light-dark pattern projection optical system for projecting a light-dark pattern having light-dark straight edges extending substantially radially from an optical axis, and reflecting from the object by the light-dark pattern projected by the light-dark pattern projection optical system, A photoelectric conversion means for receiving an image of a light-dark pattern obtained through the imaging optical system and converting it into a contrast signal of the light-dark pattern, and a photoelectric conversion means of the imaging optical system based on the contrast signal of the light-dark pattern converted by the photoelectric conversion means. A pattern detection apparatus comprising: a focusing device having a control means for relatively controlling the object at a focused position.