CN116540393A - Automatic focusing system and method, semiconductor defect detection system and method - Google Patents
Automatic focusing system and method, semiconductor defect detection system and method Download PDFInfo
- Publication number
- CN116540393A CN116540393A CN202310828033.4A CN202310828033A CN116540393A CN 116540393 A CN116540393 A CN 116540393A CN 202310828033 A CN202310828033 A CN 202310828033A CN 116540393 A CN116540393 A CN 116540393A
- Authority
- CN
- China
- Prior art keywords
- target
- image
- objective
- focusing
- projection
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000001514 detection method Methods 0.000 title claims abstract description 117
- 230000007547 defect Effects 0.000 title claims abstract description 45
- 238000000034 method Methods 0.000 title claims abstract description 37
- 239000004065 semiconductor Substances 0.000 title claims abstract description 32
- 238000003384 imaging method Methods 0.000 claims abstract description 38
- 230000003287 optical effect Effects 0.000 claims abstract description 33
- 238000000926 separation method Methods 0.000 claims description 19
- 230000007246 mechanism Effects 0.000 claims description 10
- 230000004044 response Effects 0.000 claims description 8
- 230000000149 penetrating effect Effects 0.000 claims description 5
- 230000005540 biological transmission Effects 0.000 claims description 3
- 238000007689 inspection Methods 0.000 claims description 3
- 230000006870 function Effects 0.000 description 12
- 238000010586 diagram Methods 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 238000013461 design Methods 0.000 description 3
- 238000005286 illumination Methods 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000010191 image analysis Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B21/00—Microscopes
- G02B21/0004—Microscopes specially adapted for specific applications
- G02B21/002—Scanning microscopes
- G02B21/0024—Confocal scanning microscopes (CSOMs) or confocal "macroscopes"; Accessories which are not restricted to use with CSOMs, e.g. sample holders
- G02B21/0052—Optical details of the image generation
- G02B21/006—Optical details of the image generation focusing arrangements; selection of the plane to be imaged
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B21/00—Microscopes
- G02B21/0004—Microscopes specially adapted for specific applications
- G02B21/002—Scanning microscopes
- G02B21/0024—Confocal scanning microscopes (CSOMs) or confocal "macroscopes"; Accessories which are not restricted to use with CSOMs, e.g. sample holders
- G02B21/008—Details of detection or image processing, including general computer control
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B21/00—Microscopes
- G02B21/02—Objectives
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B21/00—Microscopes
- G02B21/36—Microscopes arranged for photographic purposes or projection purposes or digital imaging or video purposes including associated control and data processing arrangements
- G02B21/364—Projection microscopes
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Optics & Photonics (AREA)
- Immunology (AREA)
- General Health & Medical Sciences (AREA)
- Biochemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Pathology (AREA)
- Health & Medical Sciences (AREA)
- Engineering & Computer Science (AREA)
- Computer Vision & Pattern Recognition (AREA)
- General Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Automatic Focus Adjustment (AREA)
- Microscoopes, Condenser (AREA)
Abstract
The invention provides an automatic focusing system and method, a semiconductor defect detection system and method, and a computer readable storage medium. The automatic focusing system includes: the projection target is obliquely arranged on the projection optical axis; a first light source for providing a first light transmitted along a projection optical axis, and projecting a projection target onto a focusing target surface through a microscope objective to form a first plane image; the imaging objective lens is combined with the micro objective lens to carry out secondary imaging on the first plane image so as to form a second plane image on the surface of the detector; the detector is used for acquiring a second plane image and obtaining a clear image at the intersection point position of the second plane image and the surface of the detector; and a controller communicatively coupled to the detector and configured to: determining the adjustment distance from the surface of the focusing target to the focal plane of the objective lens of the microscope objective lens according to the pixel coordinates of the clear image in the second plane image; and adjusting the position of the microscope objective and/or the focusing target according to the adjustment distance.
Description
Technical Field
The present invention relates to the field of semiconductor defect detection technology, and in particular, to an auto-focus system, an auto-focus method, a semiconductor defect detection system, a semiconductor defect detection method, and a computer readable storage medium.
Background
In the technical field of semiconductor defect detection, automatic focusing is a key for realizing high-precision and automatic detection of a system. The automatic focusing performance of the system has a great influence on the defect detection efficiency and the false detection rate of the system. The excellent automatic focusing performance has very important significance for an optical microscope imaging detection system.
The auto-focusing technology is mainly classified into an active type and a passive type. The active focusing technology is to measure the distance between the objective lens and the imaging target by laser, ultrasonic wave and other methods and compare the distance with the known focal plane, thereby obtaining the defocusing amount to drive the motor to the focal plane. The method has high precision, high speed and strong applicability, but the range of automatic focusing is not high and the requirement on the integrated adjustment precision of the automatic focusing system is very high. The passive focusing technology is to acquire current image information through an image processing and analyzing technology, so as to judge whether the current image is in an out-of-focus or in-focus position. The method has simple structure, but has high calculation amount, low speed and low range capable of automatically focusing.
In order to overcome the above-mentioned drawbacks of the prior art, there is a need in the art for an auto-focusing technique for realizing real-time auto-focusing of a sample to be tested, and improving the speed, accuracy, applicability and auto-focusing range of the auto-focusing, so as to further improve the overall performance of the semiconductor defect detection system.
Disclosure of Invention
The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.
In order to overcome the defects in the prior art, the invention provides an automatic focusing system, a microscope imaging system, an automatic focusing method and a computer readable storage medium, which can realize real-time automatic focusing of a sample to be tested, improve the speed, precision, applicability and automatic focusing range of automatic focusing, and further improve the overall performance of a semiconductor defect detection system.
Specifically, the above-mentioned autofocus system provided according to the first aspect of the present invention includes: the projection target is obliquely arranged on the projection optical axis; a first light source for providing a first light transmitted along the projection optical axis, and projecting the projection target onto a focusing target surface through a microscope objective to form a first plane image; an imaging objective lens, which is combined with the micro objective lens to perform secondary imaging on the first plane image so as to form a second plane image on the surface of the detector; the detector acquires the second plane image and obtains a clear image at the intersection point position of the second plane image and the surface of the detector; and a controller communicatively coupled to the detector and configured to: determining the adjustment distance from the surface of the focusing target to the focal plane of the objective lens of the microscope objective lens according to the pixel coordinates of the clear image in the second plane image; and adjusting the position of the microscope objective and/or the focusing target according to the adjustment distance.
Preferably, in an embodiment of the present invention, the step of determining the distance from the focusing target surface to the objective focal plane of the microscope objective according to the pixel coordinates of the clear image in the second plane image includes: acquiring a second plane image acquired by the detector through the detector; analyzing the second plane image to determine first pixel coordinates of a clear image therein; determining a pixel distance H between the first pixel coordinate and a second pixel coordinate corresponding to the focusing target when the focusing target is positioned on an objective focal plane of the microscope objective; and substituting the pixel distance H into a pre-fitted function X DF (H) To determine the adjustment distance X of the microscope objective and/or the focusing target.
Preferably, in an embodiment of the invention, the function X is fitted DF (H) The method comprises the following steps: placing a focusing calibration object on an objective focal plane of the microscope objective, and collecting and analyzing a second plane image of the projection objective to determine a second pixel coordinate of a clear image; determining a stepping quantity delta X according to the focal depth of the micro objective lens, and respectively adjusting the positions of the micro objective lens and/or the focusing target in a stepping way m times in the direction of expanding and shrinking the adjusting distance X so as to respectively obtain first pixel coordinates of a plurality of corresponding clear images; respectively determining corresponding pixel distances according to the second pixel coordinates and each first pixel coordinate; taking the pixel distance H as an independent variable, and taking the adjusting distance X corresponding to the microscope objective and/or the focusing target as an independent variable, and performing interpolation fitting to determine the function X DF (H)。
Preferably, in an embodiment of the present invention, the auto-focusing system further comprises a projection objective. The projection objective is arranged between the projection objective and the microscope objective and is used for converging the first light penetrating through the projection objective to the microscope objective so as to form the first plane image. The inclination angle Q of the projection target relative to the vertical plane of the projection optical axis is based on the value range-mDeltaX of the adjusting distance X and the object space half field of view F of the microscope objective obj And from the microscope objective to the projection objective, wherein,
。
preferably, in an embodiment of the present invention, the auto-focusing system further comprises a driving mechanism. The driving mechanism is connected with the controller and adjusts the position of the micro objective lens and/or the focusing target according to a control instruction provided by the controller.
Preferably, in an embodiment of the present invention, the auto-focusing system further comprises a color separator. The color separation film is used for integrating the automatic focusing system into a microscope imaging system, reflecting first light rays in a first wavelength range emitted by the first light source and transmitting second light rays in a second wavelength range emitted by the second light source in the microscope imaging system. The color separation film reflects first light rays penetrating through the projection target to the microscope imaging system to form the first plane image on the surface of the focusing target, and reflects the first light rays reflected by the focusing target to the imaging objective to form the second plane image, and transmits second light rays to the microscope imaging system to illuminate the focusing target and transmits second light rays reflected by the focusing target to the detection camera in the microscope imaging system to collect detection images of the focusing target.
Furthermore, the auto-focusing method provided according to the second aspect of the present invention includes the steps of: the projection target is obliquely arranged on a projection optical axis; providing a first light ray transmitted along the projection optical axis to the projection target, and projecting the projection target to a focusing target surface through a microscope objective to form a first plane image; acquiring a second plane image formed on the surface of the detector by the first plane image through the imaging objective lens and the secondary imaging of the micro objective lens; determining the adjustment distance from the surface of the focusing target to the focal plane of the objective lens of the microscope objective lens according to the pixel coordinates of the clear image in the second plane image; and adjusting the position of the microscope objective and/or the focusing target according to the adjustment distance.
Further, the above-described semiconductor defect detection system provided according to the third aspect of the present invention includes: a microobjective; a second light source transmitting a second light of a second wavelength range to the microscope objective via a color separation film to illuminate a detection target; the detection camera acquires second light rays reflected by the detection target through the transmission of the micro objective lens and the color separation film so as to acquire a detection image of the detection target; and the automatic focusing system provided by the first aspect of the invention reflects the first light ray in the first wavelength range to the micro objective lens through the color separation film so as to form a first plane image of the projection objective target on the surface of the detection target, and reflects the first light ray reflected by the detection target through the micro objective lens and the color separation film so as to form a second plane image of the projection objective target on the surface of the detector, and automatically focuses the detection target according to the pixel coordinates of a clear image in the second plane image.
Further, the above-described semiconductor defect detection method provided according to the fourth aspect of the present invention includes the steps of: synchronously acquiring a detection image and a focusing image from the surface of a detection target, wherein the focusing image comprises a plane image formed by projecting a projection target with an inclined optical axis on the surface of the detection target; analyzing the focusing image to determine the coordinate position of a clear image of the plane image in the focusing image; responding to the coordinate position of the clear image not conforming to the preset standard position, and longitudinally adjusting the position of the micro objective and/or the detection target according to the coordinate position so as to enable the detection target to coincide with the focal plane of the objective of the micro objective; and responding to the coordinate position of the clear image to accord with the standard position, analyzing the detection image to determine a defect detection result of the detection target.
Further, the above-described computer-readable storage medium according to the fifth aspect of the present invention has stored thereon computer instructions. The computer instructions, when executed by a controller, implement the above-described auto-focusing method provided in the second aspect of the present invention, or the above-described semiconductor defect detection method provided in the fourth aspect of the present invention.
Drawings
The above features and advantages of the present invention will be better understood after reading the detailed description of embodiments of the present disclosure in conjunction with the following drawings. In the drawings, the components are not necessarily to scale and components having similar related features or characteristics may have the same or similar reference numerals.
Fig. 1 illustrates an architecture diagram of a semiconductor defect detection system provided in accordance with some embodiments of the present invention.
Fig. 2 illustrates a flow chart of an auto-focus method provided in accordance with some embodiments of the present invention.
Fig. 3A-3D illustrate schematic diagrams of projected target patterns provided in accordance with some embodiments of the present invention.
Fig. 4 illustrates a schematic diagram of pixel distances provided by first pixel coordinates and second pixel coordinates according to some embodiments of the invention.
Fig. 5 illustrates a flow chart of a semiconductor defect detection method provided in accordance with some embodiments of the present invention.
Detailed Description
Further advantages and effects of the present invention will become apparent to those skilled in the art from the disclosure of the present specification, by describing the embodiments of the present invention with specific examples. While the description of the invention will be presented in connection with a preferred embodiment, it is not intended to limit the inventive features to that embodiment. Rather, the purpose of the invention described in connection with the embodiments is to cover other alternatives or modifications, which may be extended by the claims based on the invention. The following description contains many specific details for the purpose of providing a thorough understanding of the present invention. The invention may be practiced without these specific details. Furthermore, some specific details are omitted from the description in order to avoid obscuring the invention.
In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
In addition, the terms "upper", "lower", "left", "right", "top", "bottom", "horizontal", "vertical" as used in the following description should be understood as referring to the orientation depicted in this paragraph and the associated drawings. This relative terminology is for convenience only and is not intended to be limiting of the invention as it is described in terms of the apparatus being manufactured or operated in a particular orientation.
It will be understood that, although the terms "first," "second," "third," etc. may be used herein to describe various elements, regions, layers and/or sections, these elements, regions, layers and/or sections should not be limited by these terms and these terms are merely used to distinguish between different elements, regions, layers and/or sections. Accordingly, a first component, region, layer, and/or section discussed below could be termed a second component, region, layer, and/or section without departing from some embodiments of the present invention.
As described above, the conventional active autofocus technique and passive autofocus technique have respective defects, and have common defects that the range of autofocus is small, which makes it difficult to meet the actual requirements of semiconductor defect detection.
In order to overcome the above-mentioned drawbacks of the prior art, the present invention provides an auto-focusing system, a microscope imaging system, an auto-focusing method, and a computer readable storage medium, which can implement real-time auto-focusing detection of a wafer waiting for a sample to be tested, and improve the speed, precision, adaptability, and auto-focusing range of auto-focusing, thereby being more beneficial to improving the overall performance of a semiconductor defect detection system.
In some non-limiting embodiments, the above-described auto-focusing method provided by the second aspect of the present invention may be implemented via the above-described auto-focusing system provided by the first aspect of the present invention. The above-described semiconductor defect detection method provided by the fourth aspect of the present invention may be implemented via the above-described semiconductor defect detection system provided by the third aspect of the present invention.
Specifically, the autofocus system may be integrated into the above-described semiconductor defect detection system provided in the third aspect of the present invention via a color separation film, in which the first memory and the first processor are configured. The first memory includes, but is not limited to, the above-described computer-readable storage medium provided in the fourth aspect of the present invention, on which computer instructions are stored. The first processor is coupled to the first memory and configured to execute computer instructions stored on the memory to implement an auto-focus method provided by the second aspect of the present invention. In addition, the semiconductor defect detection system may be configured with a second memory and a second processor. The second memory includes, but is not limited to, the above-described computer-readable storage medium provided in the fourth aspect of the present invention, on which computer instructions are stored. The second processor is coupled to the second memory and configured to execute computer instructions stored on the memory to implement the semiconductor defect detection method provided in the fourth aspect of the present invention.
Referring specifically to fig. 1, fig. 1 is a block diagram illustrating a semiconductor defect detection system according to some embodiments of the present invention.
In the embodiment shown in fig. 1, the semiconductor defect detection system 10 provided in the third aspect of the present invention may include the autofocus system, the second light source 12, the micro objective 13, and the detection camera 14 provided in the first aspect of the present invention. The auto-focusing system further comprises a first light source 111, a projection target 112, a projection objective 113, an imaging objective 114, and a detector 115.
Specifically, the first light source 111 is configured to provide a first light ray transmitted along the projection optical axis. The projection target 112 is at a predetermined angleQThe projection optical axis is obliquely arranged. The projection objective 113 is disposed at the rear end of the projection objective 112, and is used for collimating the first light beam penetrating the projection objective 112, and transmitting the first light beam to the rear end of the microscope objective 13 through the dichroic sheet 116 and the dichroic sheet 15, so as to converge on the surface of a focusing target 141 (e.g. a wafer to be subjected to defect detection) of the object side of the microscope objective 13 to form a first plane image P11 of the projection objective 112. Here, 50: 50. The color separator 15 can reflect a first light beam with a first wavelength range (e.g., 650 nm-1000 nm) from a first light source 111 of the auto-focusing system and transmit a second light beam with a second wavelength range (e.g., 430-650 nm) from a second light source 12 of the microscopic imaging system to integrate the auto-focusing system into the microscopic imaging systemAnd avoids the influence of an automatic focusing system on microscope imaging.
It will be appreciated by those skilled in the art that the above-described beam splitter 116 and color splitter 15 are merely one non-limiting embodiment for implementing an integrated design of the optical path, and are intended to illustrate the main concept of the present invention and to provide an integrated, miniaturized design of the optical path, and are not intended to limit the scope of the present invention.
Alternatively, in other embodiments, a person skilled in the art may use conventional optical elements such as mirrors to set the target projection optical path, the target imaging optical path, the target illumination optical path, and the microscope imaging optical path in different orientations of the microscope objective 13, so as to achieve the basic function of auto-focusing as well.
Further, in response to forming the first planar image P11 of the projection target 112 on the surface of the focusing target 141, the micro objective 13 correspondingly obtains a virtual image of the first planar image P11, and performs secondary imaging on the virtual image of the first planar image P11 through the micro objective 13, the color separation film 15, the light separation film 116 and the imaging objective 114, so as to form a second planar image P21 of the projection target 112 on the detection surface of the detector 115.
At this time, since the projection target 112 is disposed obliquely with respect to the projection optical axis, the first plane image P11 thereof intersects the objective focal plane 142 of the microscope objective 13 while maintaining an oblique posture, and the intersection point position B2 corresponds to the position B1 on the projection target 112. Correspondingly, the second planar image P21 of the projection target 112 also maintains an oblique posture with the detection surface of the detector 115, and a clear image at the position B1 on the projection target 112 is obtained at the intersection point position B3 of the two.
As shown in fig. 1, since the projection surface of the focusing target 141 deviates from the objective focal plane 142 of the microscope objective 13, the position B3 of the clear image also deviates correspondingly from the center position A3 of the detection surface of the detector 115. For this reason, the auto-focusing system provided by the present invention may be further configured with a controller (not shown). The controller is communicatively coupled to the detector 115 and is capable of acquiring a focused image of the second planar image P21 via the detector 115, identifying and calculating the pixel coordinates of the position B3 of the sharp image therein to determine the adjustment distance X of the focus target 141 from the objective focal plane 142 of the microscope objective 13, and thereby achieving auto-focusing of the focus target 141.
The operation of the controller and the autofocus system will be described in connection with some embodiments of the autofocus method. It will be appreciated by those skilled in the art that these examples of measurement methods are merely some non-limiting embodiments provided by the present invention, and are intended to clearly illustrate the general concepts of the present invention and to provide some embodiments that are convenient for public implementation, and are not intended to limit the overall functionality or overall operation of the controller and autofocus system. Similarly, the controller and the automatic focusing system are just one non-limiting embodiment provided by the invention, and do not limit the execution main and execution sequence of each step in the measuring methods.
Referring to fig. 1 and fig. 2 in combination, fig. 2 is a flowchart illustrating an auto-focusing method according to some embodiments of the invention.
As shown in fig. 1 and 2, in the auto-focusing process, a technician may first tilt the projection objective 112 on the projection optical axis, and turn on the first light source 111 to provide the first light transmitted along the projection optical axis to the projection objective 112, so as to sequentially project the projection objective 112, the projection objective 113, the beam splitter 116, the color splitter 15 and the microscope objective 13 on the projection optical axis, and project the projection objective 112 onto the surface of the focusing target 141 of the object side of the microscope objective 13, so as to form the first plane image P11. Here, the tilt angle of the projection target 112 with respect to the vertical plane of the projection optical axisQCan be preferably based on the adjustment range of the focusing target 141 and the object side half field of view F of the microscope objective 13 obj The determination, a specific determination method thereof will be described later.
Then, the micro objective 13 obtains the virtual image of the first plane image P11 as described above, and performs secondary imaging on the virtual image of the first plane image P11 through the micro objective 13, the color separation film 15, the beam splitter 116 and the imaging objective 114, so as to form a second plane image P21 of the projection target 112 on the detection surface of the detector 115. The controller may acquire a focused image of the second plane image P21 via the detector 115 and perform image analysis thereon to determine a position (i.e., an intersection point position B3) of the clear image in the focused image.
Then, the controller may determine an adjustment distance X of the surface of the focusing target 141 from the objective focal plane 142 of the microscope objective 13 according to the first pixel coordinates L (X, y) of the clear image in the focusing image of the second plane image P21, and adjust the position of the microscope objective 13 and/or the focusing target 141 according to the adjustment distance X, so that the surface of the focusing target 141 coincides with the objective focal plane 142 of the microscope objective 13, and accomplish the auto focusing of the microscope objective 13 and the focusing target 141.
Please refer to fig. 3A to fig. 3D and fig. 4. Fig. 3A-3D illustrate schematic diagrams of projected target patterns provided in accordance with some embodiments of the present invention. Fig. 4 illustrates a schematic diagram of a sharp image acquired by a detector provided in accordance with some embodiments of the invention.
As shown in fig. 3A to 3D, in some embodiments of the present invention, the pattern of the projection target 112 in fig. 1 may be selected from a horizontal grating pattern shown in fig. 3A, or may be selected from a slanted grating pattern shown in fig. 3B, a circular light shielding pattern shown in fig. 3C, a slanted grating array pattern shown in fig. 3D, or the like.
Taking the horizontal grating pattern shown in fig. 3A as an example, the grating structure thereof blocks a portion of the first light outputted from the first light source 111, so as to form a first planar image P11 of the stripe on the surface of the focusing target 141, and form a second planar image P21 of the stripe on the detection surface of the detector 115.
In some embodiments, the technician may pre-fit a function X of the adjustment distance X with respect to the pixel coordinates of the sharp image prior to performing auto-focusing DF (H) And according to the pixel coordinates of the identified sharp image and the fitted function X DF (H) To determine the adjustment distance X.
Specifically, in fitting function X DF (H) In the process, a technician may first place a focus calibration object (e.g., a semiconductor wafer sample) on the objective focal plane 142 of the microscope objective 13, form a first planar image P12 of the projection objective 112 on the surface thereof, and collect the projection object via the detector 115The shadow target 112 forms a focused image of the second planar image P22 on its detection surface. At this time, since the point A2 on the optical axis of the first plane image P12 coincides with the objective focal plane 142 of the microscope objective 13, the intersection point position A2 of the first plane image P12 and the projection surface of the focus calibration object corresponds to the intersection point position A1 of the projection target 112 and the projection optical axis. Correspondingly, the intersection point of the second planar image P22 of the projection target 112 and the detection surface of the detector 115 is also located at the center position A3 of the detection surface of the detector 115 (i.e., a clear image is formed at the center position A3 of the detection surface of the detector 115).
Then, as shown in fig. 1 and 4, the controller may analyze the focusing image to determine the second pixel coordinate L of the clear image at the position A3 0 (x 0 , y 0 ) Determining a stepping amount (i.e. Δx=n×df) according to n times Depth of Focus (DF) of the microscope objective 13, and respectively adjusting the position of the microscope objective 13 m times in a direction of expanding and contracting the adjustment distance X in a stepping manner to obtain a plurality of corresponding first pixel coordinates L of the clear images respectively -m (x -m , y -m ) ~ L m (x m , y m ) And calculates each first pixel coordinate L as shown in FIG. 4 -m (x -m , y -m ) ~ L m (x m , y m ) And the second pixel coordinate L 0 (x 0 , y 0 ) Is a pixel distance H -m ~H m 。
After that, the technician can make the above-mentioned pixel distance H -m ~H m As independent variables, and interpolation fitting is carried out by taking the adjusting distances-mDeltaX corresponding to the microscope objective 13 as dependent variables to determine a corresponding function X DF (H)。
Thus, the following function X based on pre-fitting DF (H) In response to resolving the first pixel coordinates L (x, y) of the sharp image in the second planar image P21 of the focus target 141 during auto-focusing, the controller may compare it with the second pixel coordinates L of the corresponding focus calibration object as shown in fig. 4 0 (x 0 , y 0 ) Comparing to calculate the pixel distance H between the two images, and substituting the pixel distance H into the pre-simulated imageFunction X of synthesis DF (H) To determine the adjustment distance X of the microscope objective 13 and/or of the focusing object. Then, the controller can make a control command according to the adjustment distance X to control the driving mechanism 131 to drive the micro objective 13 to move up and down, so that the objective focal plane 142 of the micro objective 13 coincides with the focusing target 141, and automatic focusing of the focusing target is achieved.
It will be appreciated by those skilled in the art that the above example of adjusting the position of the micro objective lens 13 to achieve auto focusing is merely provided as a non-limiting embodiment, and is intended to clearly illustrate the main concept of the present invention and to provide a specific solution for public implementation, not to limit the scope of the present invention.
Alternatively, in other embodiments, a driving mechanism may be disposed on a stage on which the focusing target 141 (e.g. a wafer to be measured) is disposed, and the controller controls the stage driving mechanism to move the focusing target 141 up and down, so as to achieve the purpose of auto-focusing.
Further, as shown in fig. 1, in response to the up-and-down displacement of the micro objective 13 and/or the focusing target 141, the second plane image P21 of the projection target 112 is also displaced up-and-down with respect to the detection surface of the detector 115, thereby changing the intersection position with the detection surface and changing the pixel coordinates of the clear image. For this purpose, the tilt angle of the projection target 112 with respect to the vertical plane of the projection optical axisQThe following conditions may be used to adapt to the adjustment range requirement of the auto-focus function:
。
further, the inclination angleQMay be preferablyOr->Thereby obtaining while adapting to the requirement of the adjusting range of the automatic focusing functionThe maximum focusing accuracy is obtained. For example, for a microscope objective with a magnification of 50, its object space is half field of view F obj =1mm. When setting upQWhen the magnification of the microscope objective 13 to the imaging objective 114 is 2 times, the adjustment range af=tan (30 °) ×1 mm/2=0.29 mm of the auto-focusing function can obtain a relatively balanced adjustment range and focusing accuracy.
Therefore, based on the above description, the automatic focusing system, the automatic focusing method and the computer readable storage medium provided by the invention can realize real-time automatic focusing of the sample to be tested, and improve the speed, precision, applicability and automatic focusing range of the automatic focusing.
Further, as shown in fig. 1, in addition to the above-mentioned autofocus system provided in the first aspect of the present invention, the above-mentioned semiconductor defect detection system provided in the second aspect of the present invention is further provided with a second light source 12, a micro objective lens 13, and a detection camera 14.
In some embodiments, the illumination path of the second light source 12 is via 50:50 is integrated into the detection light path of the microscope imaging system. The second light source 12 emits a second light in a second wavelength range (e.g., 430-650 nm) along the illumination optical axis, and transmits the second light to the color separation film 15 via the half mirror 16. As described above, the color separation film 15 transmits the second light of the second wavelength range and transmits it to the detection target (i.e., the focusing target 141 of the auto-focusing system) via the micro objective lens 13 to illuminate the detection target. After being reflected by the surface of the detection target, the second light is transmitted to the detection camera 14 through the transmission of the micro objective lens 13, the color separation film 15, the half-reflecting half-lens 16 and the lens barrel 17 in sequence, so as to be collected and generate a detection image of the detection target.
Referring to fig. 1 and 5 in combination, fig. 5 illustrates a flow chart of a semiconductor defect detection method provided in accordance with some embodiments of the present invention.
As shown in fig. 1 and 5, in the process of performing defect detection on a detection target (e.g., a wafer with a defect to be detected), a technician may first adjust the height of the micro objective 13 via the driving mechanism 131, so that the detection target coincides with the objective focal plane 142 of the micro objective 13, and synchronously acquire a detection image and a focusing image of the surface of the detection target via the detection camera 14 and the detector 115.
The autofocus system may then parse the focused image in real time to determine the coordinate position of the sharp image of the second plane image P22 of the projection target 112 in the focused image. In response to the determination that the coordinate position of the clear image meets the standard position A3, the semiconductor defect detection system may determine that the detection target is currently located at the in-focus position, so as to analyze the synchronously acquired detection image to determine a defect detection result of the detection target.
Then, the technician can laterally adjust the horizontal position of the inspection object through the object stage driving mechanism to respectively determine the wafer defects of each area of the inspection object. In this process, in response to the surface of the detection target being fluctuated by the change in the structure height, the detection image acquired by the detection camera 14 will be blurred by the defocus of the detection target. At the same time, the autofocus system also deviates the clear image in the in-focus image from the center position A3 to the edge position B3.
In response to a determination that the coordinate position of the clear image does not conform to the preset standard position, the semiconductor defect detection system may determine that the detection target is currently located at the defocus position. The automatic focusing system may determine the adjustment distance X of the microscope objective 13 according to the pixel distance H between the actual coordinate position of the clear image and the preset standard position as described above, and adjust the position of the microscope objective 13 in real time via the driving mechanism 131, so that the clear image returns to the central position A3 again, and the detection target coincides with the objective focal plane 142 of the microscope objective 13 again. Then, in response to the judgment result that the coordinate position of the clear image returns to the standard position, the semiconductor defect detection system can judge that the detection target returns to the normal focus position, so that the movement of the driving mechanism is stopped, and the defect detection result of the detection target in the corresponding area is continuously acquired.
Therefore, the microscope imaging system provided by the invention can automatically focus and automatically start and stop the detection between the detection target and the microscope objective 13 in real time along with the height change of the surface of the detection target in the detection process of the wafer defect, so that the detection precision, the reliability and the detection efficiency of the wafer defect detection system are integrally improved.
While, for purposes of simplicity of explanation, the methodologies are shown and described as a series of acts, it is to be understood and appreciated that the methodologies are not limited by the order of acts, as some acts may, in accordance with one or more embodiments, occur in different orders and/or concurrently with other acts from that shown and described herein or not shown and described herein, as would be understood and appreciated by those skilled in the art.
The various illustrative logical modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. An autofocus system, comprising:
the projection target is obliquely arranged on the projection optical axis;
a first light source for providing a first light transmitted along the projection optical axis, and projecting the projection target onto a focusing target surface through a microscope objective to form a first plane image;
an imaging objective lens, which is combined with the micro objective lens to perform secondary imaging on the first plane image so as to form a second plane image on the surface of the detector;
the detector acquires the second plane image and obtains a clear image at the intersection point position of the second plane image and the surface of the detector; and
a controller communicatively coupled to the detector and configured to: determining the adjustment distance from the surface of the focusing target to the focal plane of the objective lens of the microscope objective lens according to the pixel coordinates of the clear image in the second plane image; and adjusting the position of the microscope objective and/or the focusing target according to the adjustment distance.
2. The autofocus system of claim 1, wherein said step of determining the distance of said focus target surface to the objective focal plane of said microscope objective based on the pixel coordinates of the sharp image in said second planar image comprises:
acquiring a second plane image acquired by the detector through the detector;
analyzing the second plane image to determine first pixel coordinates of a clear image therein;
determining a pixel distance H between the first pixel coordinate and a second pixel coordinate corresponding to the focusing target when the focusing target is positioned on an objective focal plane of the microscope objective; and
substituting the pixel distance H into a pre-fitted function X DF (H) To determine the adjustment distance X of the microscope objective and/or the focusing target.
3. Autofocus system according to claim 2, characterized in that said function X is fitted DF (H) The method comprises the following steps:
placing a focusing calibration object on an objective focal plane of the microscope objective, and collecting and analyzing a second plane image of the projection objective to determine a second pixel coordinate of a clear image;
determining a stepping quantity delta X according to the focal depth of the micro objective lens, and respectively adjusting the positions of the micro objective lens and/or the focusing target in a stepping way m times in the direction of expanding and shrinking the adjusting distance X so as to respectively obtain first pixel coordinates of a plurality of corresponding clear images;
respectively determining corresponding pixel distances according to the second pixel coordinates and each first pixel coordinate; and
taking the pixel distance H as an independent variable and taking the adjusting distance X corresponding to the microscope objective and/or the focusing target as an independent variable to perform interpolation fitting to determine the function X DF (H)。
4. An autofocus system as in claim 3, further comprising:
the projection objective is arranged between the projection objective and the microscope objective and is used for converging first light penetrating through the projection objective to the microscope objective so as to form the first plane image, wherein the inclination angle Q of the projection objective on the vertical plane of the projection optical axis is the value range-mDeltaX according to the adjusting distance X, and the object side half view field F of the microscope objective obj And from the microscope objective to the projection objective, wherein,
。
5. the autofocus system of claim 1, further comprising:
and the driving mechanism is connected with the controller and used for adjusting the position of the micro objective lens and/or the focusing target according to the control instruction provided by the controller.
6. The autofocus system of claim 1, further comprising a color separator for integrating the autofocus system into a microscope imaging system, reflecting a first light of a first wavelength range from the first light source, and transmitting a second light of a second wavelength range from a second light source in the microscope imaging system, wherein,
the color separation film reflects the first light rays penetrating through the projection objective to the microscope imaging system to form the first plane image on the surface of the focusing objective, and reflects the first light rays reflected by the focusing objective to the imaging objective to form the second plane image,
the color separation film also transmits the second light to the microscope objective lens to illuminate the focusing target, and transmits the second light reflected by the focusing target to a detection camera in the microscope imaging system so as to collect a detection image of the focusing target.
7. An automatic focusing method, comprising the steps of:
the projection target is obliquely arranged on a projection optical axis;
providing a first light ray transmitted along the projection optical axis to the projection target, and projecting the projection target to a focusing target surface through a microscope objective to form a first plane image;
acquiring a second plane image formed on the surface of the detector by the first plane image through the imaging objective lens and the secondary imaging of the micro objective lens;
determining the adjustment distance from the surface of the focusing target to the focal plane of the objective lens of the microscope objective lens according to the pixel coordinates of the clear image in the second plane image; and
and adjusting the position of the microscope objective and/or the focusing target according to the adjusting distance.
8. A semiconductor defect inspection system, comprising:
a microobjective;
a second light source transmitting a second light of a second wavelength range to the microscope objective via a color separation film to illuminate a detection target;
the detection camera acquires second light rays reflected by the detection target through the transmission of the micro objective lens and the color separation film so as to acquire a detection image of the detection target; and
the automatic focusing system according to any one of claims 1 to 6, wherein the first light beam with a first wavelength range is reflected to the micro-objective lens through the color separation film to form a first plane image of a projection target on the surface of the detection target, the first light beam reflected by the detection target is reflected and obtained through the micro-objective lens and the color separation film to form a second plane image of the projection target on the surface of the detector, and the detection target is automatically focused according to pixel coordinates of a clear image in the second plane image.
9. A method for detecting a semiconductor defect, comprising the steps of:
synchronously acquiring a detection image and a focusing image from the surface of a detection target, wherein the focusing image comprises a plane image formed by projecting a projection target with an inclined optical axis on the surface of the detection target;
analyzing the focusing image to determine the coordinate position of a clear image of the plane image in the focusing image;
responding to the coordinate position of the clear image not conforming to the preset standard position, and longitudinally adjusting the position of the micro objective and/or the detection target according to the coordinate position so as to enable the detection target to coincide with the focal plane of the objective of the micro objective; and
and analyzing the detection image to determine a defect detection result of the detection target in response to the coordinate position of the clear image conforming to the standard position.
10. A computer readable storage medium having stored thereon computer instructions which, when executed by a processor, implement the auto-focus method of claim 7 or the semiconductor defect detection method of claim 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310828033.4A CN116540393B (en) | 2023-07-07 | 2023-07-07 | Automatic focusing system and method, semiconductor defect detection system and method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310828033.4A CN116540393B (en) | 2023-07-07 | 2023-07-07 | Automatic focusing system and method, semiconductor defect detection system and method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN116540393A true CN116540393A (en) | 2023-08-04 |
| CN116540393B CN116540393B (en) | 2024-01-30 |
Family
ID=87444017
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310828033.4A Active CN116540393B (en) | 2023-07-07 | 2023-07-07 | Automatic focusing system and method, semiconductor defect detection system and method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116540393B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117078662A (en) * | 2023-10-11 | 2023-11-17 | 杭州睿影科技有限公司 | Detection method and device for laminated battery, image processing equipment and medium |
Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4639587A (en) * | 1984-02-22 | 1987-01-27 | Kla Instruments Corporation | Automatic focusing system for a microscope |
| JP2004029069A (en) * | 2002-06-21 | 2004-01-29 | Mitsutoyo Corp | Autofocus device |
| US20050121596A1 (en) * | 2002-03-13 | 2005-06-09 | Yeda Research And Development Company Ltd. | Auto-focusing method and device |
| US7142315B1 (en) * | 2004-01-16 | 2006-11-28 | Kla-Tencor Technologies Corporation | Slit confocal autofocus system |
| JP2010151928A (en) * | 2008-12-24 | 2010-07-08 | Tamron Co Ltd | Focus detection system for lens device |
| CN104932092A (en) * | 2015-06-15 | 2015-09-23 | 上海交通大学 | Automatic focusing microscope based on eccentric beam method and focusing method thereof |
| CN106772923A (en) * | 2015-11-24 | 2017-05-31 | 睿励科学仪器（上海）有限公司 | Atomatic focusing method and system based on angled slots |
| CN108646396A (en) * | 2018-04-27 | 2018-10-12 | 合肥工业大学 | Auto-focusing microscopic system |
| WO2021019597A1 (en) * | 2019-07-26 | 2021-02-04 | 株式会社日立ハイテク | Nucleic acid analysis device and method |
| WO2021184169A1 (en) * | 2020-03-16 | 2021-09-23 | 中国科学院深圳先进技术研究院 | Real-time automatic focusing system for microscope |
-
2023
- 2023-07-07 CN CN202310828033.4A patent/CN116540393B/en active Active
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4639587A (en) * | 1984-02-22 | 1987-01-27 | Kla Instruments Corporation | Automatic focusing system for a microscope |
| US20050121596A1 (en) * | 2002-03-13 | 2005-06-09 | Yeda Research And Development Company Ltd. | Auto-focusing method and device |
| JP2004029069A (en) * | 2002-06-21 | 2004-01-29 | Mitsutoyo Corp | Autofocus device |
| US7142315B1 (en) * | 2004-01-16 | 2006-11-28 | Kla-Tencor Technologies Corporation | Slit confocal autofocus system |
| JP2010151928A (en) * | 2008-12-24 | 2010-07-08 | Tamron Co Ltd | Focus detection system for lens device |
| CN104932092A (en) * | 2015-06-15 | 2015-09-23 | 上海交通大学 | Automatic focusing microscope based on eccentric beam method and focusing method thereof |
| CN106772923A (en) * | 2015-11-24 | 2017-05-31 | 睿励科学仪器（上海）有限公司 | Atomatic focusing method and system based on angled slots |
| CN108646396A (en) * | 2018-04-27 | 2018-10-12 | 合肥工业大学 | Auto-focusing microscopic system |
| WO2021019597A1 (en) * | 2019-07-26 | 2021-02-04 | 株式会社日立ハイテク | Nucleic acid analysis device and method |
| WO2021184169A1 (en) * | 2020-03-16 | 2021-09-23 | 中国科学院深圳先进技术研究院 | Real-time automatic focusing system for microscope |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117078662A (en) * | 2023-10-11 | 2023-11-17 | 杭州睿影科技有限公司 | Detection method and device for laminated battery, image processing equipment and medium |
Also Published As
| Publication number | Publication date |
|---|---|
| CN116540393B (en) | 2024-01-30 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP7609804B2 (en) | Self-calibration and directional focusing system and method for infinity corrected microscopes - Patents.com | |
| JP5015955B2 (en) | Automatic focusing method and system of automatic microscope | |
| CN109540004B (en) | Optical detection system and detection method thereof | |
| JP4613357B2 (en) | Apparatus and method for adjusting optical misregistration measuring apparatus | |
| JP6363382B2 (en) | Film thickness measuring apparatus and method | |
| US11567293B2 (en) | Autofocus device, and optical apparatus and microscope including the same | |
| KR101891182B1 (en) | Apparatus for controlling auto focus | |
| JP2006184303A (en) | Image inspecting device | |
| CN116540393B (en) | Automatic focusing system and method, semiconductor defect detection system and method | |
| CN119275160A (en) | Wafer alignment device and wafer bonding method | |
| CN108693624B (en) | Imaging method, device and system | |
| CN114441531B (en) | Automatic focusing method with image recognition, device, computer and storage medium | |
| CN114234835B (en) | Testing equipment and testing methods | |
| JP2001311866A (en) | Autofocus method and apparatus for microscope | |
| JP4384446B2 (en) | Autofocus method and apparatus | |
| JP4573252B2 (en) | Alignment system, alignment system control method, program, and measuring apparatus | |
| JP2000352661A (en) | Focusing device | |
| JP2004102032A (en) | Scanning type confocal microscope system | |
| JPH09230250A (en) | Optical microscope automatic focusing device | |
| JP2828145B2 (en) | Optical section microscope apparatus and method for aligning optical means thereof | |
| CN108693113B (en) | Imaging method, device and system | |
| JP7664524B2 (en) | Crack detection device and method for controlling the crack detection device | |
| US20240319487A1 (en) | Microscope and method for autofocusing | |
| JP2019163946A (en) | Noncontact surface profile measurement device | |
| JP4381687B2 (en) | Total reflection fluorescence microscope |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |