WO2023178720A1 - 一种光学检测装置及方法 - Google Patents

一种光学检测装置及方法 Download PDF

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WO2023178720A1
WO2023178720A1 PCT/CN2022/084025 CN2022084025W WO2023178720A1 WO 2023178720 A1 WO2023178720 A1 WO 2023178720A1 CN 2022084025 W CN2022084025 W CN 2022084025W WO 2023178720 A1 WO2023178720 A1 WO 2023178720A1
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measured
imaging
module
focal plane
light
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PCT/CN2022/084025
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English (en)
French (fr)
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田依杉
兰艳平
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上海御微半导体技术有限公司
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    • 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
    • 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

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  • the present invention relates to the field of optical detection technology, and in particular to an optical detection device and method.
  • existing AOI equipment usually includes optical imaging modules, stages, material transfer systems, etc.
  • the optical imaging module includes an illumination unit, imaging objective lens, detector, etc.
  • the surface to be measured needs to be adjusted to the best focal plane to obtain a clear picture to facilitate the identification of defects on the surface to be measured.
  • the existing technology uses an optical system to scan and take pictures of the object to be tested in the vertical direction of the stage, but the scanning process takes a certain amount of time, which affects the detection efficiency on the production line.
  • Embodiments of the present invention provide an optical detection device and method to improve detection efficiency on the basis of ensuring the accuracy of optical detection.
  • the present invention provides an optical detection device, including a stage for carrying an object to be tested, an illumination module for emitting a detection beam to the object to be tested, and a focusing module for passing an optical component
  • the detection beam is split into the object to be measured and the reference focal plane respectively, and is converged to a spectrum recorder through optical components; the spectrum recorder is used to record the detection beam passing through the object to be measured and the reference focal plane.
  • the phase information and spectral wavelength of the interference beam after reflection from the surface respectively.
  • the optical detection device also includes a data processing module for obtaining the phase information and spectral wavelength of the interference beam, and calculating based on the phase information and spectral wavelength of the interference beam, when the surface of the object to be measured is placed on
  • the optimal focal plane is the optimal relative distance between the stage and the imaging objective.
  • a control module is used to control the driving part to drive the stage to move in a direction perpendicular to the plane where the stage is located, so that the relative distance between the stage and the imaging objective lens reaches the optimal relative distance.
  • the data processing module uses the principle of white light interference ranging, and calculates the surface of the object to be measured and places it in the optimal focal plane through the phase information and spectral wavelength of the interference beam.
  • the optimal relative distance between the stage and the imaging objective lens is the optimal relative distance. Based on the optimal relative distance, the stage can be adjusted once to complete the focusing process, thus avoiding multiple scanning and photographing of the object to be measured. It saves the focusing time and improves the detection efficiency while ensuring the accuracy of optical detection.
  • the optical detection device further includes an imaging module, configured to collect the imaging light beam after the detection beam is reflected by the object to be measured when the surface to be measured of the object to be measured is placed at the optimal focal plane, The object to be measured is imaged to form image information.
  • the data processing module is also used to obtain the image information from the imaging module and perform optical detection on the image information.
  • the data processing module is also used to obtain the light intensity of the interference beam, and determine the light intensity adjustment amount of the detection light path module according to the light intensity of the interference light beam; the detection light path module and the The data processing module is connected, and the detection light path module is also used to adjust the light intensity of the detection beam according to the light intensity adjustment.
  • the illumination module includes a focusing light source, a first mechanical switch, a first light splitting plate and an imaging light source; the focusing light source is used to emit a first detection beam, the imaging light source is used to emit a second detection beam, and the first mechanical switch, Used to control the opening or closing of the focusing optical path corresponding to the first detection beam;
  • the focusing module includes a light path of the surface to be measured, a reference surface light path and a focal surface measurement light path;
  • the light path of the surface to be measured includes a first imaging objective lens and a second light splitting plate adjacent to the object to be measured;
  • the reference surface light path includes a third two mechanical switches, a second imaging objective lens and a reference focal plane;
  • the focal plane measurement optical path includes a third spectroscopic plate, a lens and a spectrum recorder;
  • both the first detection beam and the second detection beam are incident on the object to be measured through the first light splitting plate, the second light splitting plate and the first imaging objective lens.
  • the first reflected beam is formed by reflection from the surface of the object to be measured; and when the second mechanical switch is turned on, both the first detection beam and the second detection beam pass through the first spectroscopic plate, the second The beam splitting plate and the second imaging objective lens are incident on the reference focal plane, and are reflected by the reference focal plane surface to form a second reflected beam, and the first reflected beam and the second reflected beam form the interference beam,
  • the interference beam enters the spectrum recorder through the lens.
  • the illumination module includes a focusing light source, a first polarizer, a first light splitting plate, an imaging light source and a second polarizer.
  • the focusing module includes a light path of the surface to be measured, a reference surface light path and a focal surface measurement light path; the light path of the surface to be measured includes a first imaging objective lens and a second light splitting plate adjacent to the object to be measured; the reference surface light path includes a third Two mechanical switches, a second imaging objective lens and a reference focal plane; the focal plane measurement optical path includes a third spectroscopic plate, an analyzer, a lens and a spectrum recorder; the polarization direction of the analyzer is the same as the first polarization The polarization direction of the second polarizer is the same but orthogonal to the polarization direction of the second polarizer.
  • the first detection beam and the second detection beam are both incident on the object to be measured through the first light splitting plate, the second light splitting plate and the first imaging objective lens, and are reflected by the surface of the object to be measured to form The first reflected light beam; and the first detection light beam passes through the first light splitting plate, the second light splitting plate, the analyzer, and the second imaging objective lens and is incident on the reference focal plane, passing through the reference focal plane Surface reflection forms a second reflected beam, the first reflected beam and the second reflected beam form the interference beam, and the interference beam is incident into the spectrum recording module through a lens.
  • the focusing light source is a broad spectrum light source.
  • the broad spectrum light source is a white light source.
  • the present invention also provides an optical detection method, which can apply the optical detection device as described in any embodiment of the first aspect, and the method includes:
  • Control the lighting module to emit a detection beam to the object to be tested, and the object to be tested is placed on the stage;
  • the control focus module uses the optical component to separate the detection beam into the object to be measured and the reference focal plane, and converges it to the spectrum recorder through the optical component;
  • the spectrum recorder is used to record the detection beam through the The phase information and spectral wavelength of the interference beam formed after reflection from the object to be measured and the reference focal plane respectively;
  • the stage is vertically The optimal relative distance between the stage and the imaging objective lens; a control module for controlling the driving part to drive the stage to move in a direction perpendicular to the plane where the stage is located, so that the stage The relative distance to the imaging objective lens reaches the optimal relative distance.
  • the method further includes: controlling the imaging module to collect the imaging beam after the detection beam is reflected by the object to be measured when the surface to be measured of the object to be measured is placed on the optimal focal plane,
  • the object to be measured is imaged to form image information;
  • the data processing module is controlled to obtain the image information from the imaging module, and perform overlay measurement on the image information.
  • the optical detection device and method proposed by the embodiments of the present invention calculate the distance between the stage and the imaging objective lens when the object to be measured is in the best focal plane by using the principle of white light interference ranging with a spectrum recorder.
  • the optimal relative distance between them avoids scanning images multiple times, saves scanning time, and improves productivity;
  • the light source of the focusing system and the light source of the imaging system are separated, and a special optical path design is used to provide the two light sources to The focusing system and imaging system do not interfere with each other, so that the spectrometer ranging technology can be better utilized while ensuring productivity.
  • Figure 1 is a schematic structural diagram of an optical detection device provided by an embodiment of the present invention.
  • Figure 2 is a schematic structural diagram of another optical detection device provided by an embodiment of the present invention.
  • Figure 3 is a schematic flow chart of an optical detection method provided by an embodiment of the present invention.
  • Illumination module 101 focus module 102, imaging module 103, data processing module 104, control module 105 and stage 106;
  • Object to be measured 4 first imaging objective lens 3, second imaging objective lens 6, reference focal plane 7;
  • Imaging objective lens 11 and camera 12 Imaging objective lens 11 and camera 12;
  • Figure 1 is a schematic structural diagram of an optical detection device proposed in an embodiment of the present invention.
  • the optical detection device includes: an illumination module 101, a focusing module 102, an imaging module 103, a data processing module 104, a control module 105 and a stage 106. in:
  • the stage 106 is used to carry the object 4 to be tested.
  • the object 4 under test may be a wafer or other semiconductor device.
  • the illumination system 101 is used to emit a detection beam to the object 4 to be measured.
  • the illumination system 01 includes a focusing light source 1-1, a first mechanical switch 14, an imaging light source 1-2 and a first light splitting plate 2-1.
  • the focusing light source 1-1 is used to emit a first detection beam
  • the imaging light source 1-2 is used to emit a second detection beam.
  • the focusing light source may be a broad spectrum light source.
  • the focusing light source is a white light source in order to use a spectrometer for distance measurement, and a design of two light sources is adopted, and a special optical path design is used to provide the two light sources to the focusing system and the imaging system respectively without affecting each other. interference.
  • the first mechanical switch 14 When the first mechanical switch 14 is turned on, the first detection beam emitted from the focusing light source 1-1 enters the object to be measured 4 and the reference focus through the first mechanical switch 14, the first spectroscopic plate 2-1, and the second spectroscopic plate 2-2. Side 7. When the first mechanical switch 14 is closed, the first detection beam emitted from the focusing light source 1 - 1 will not enter the object to be measured 4 and the reference focal plane 7 .
  • the focusing module 102 includes a surface optical path to be measured, a reference surface optical path and a focal surface measurement optical path.
  • the light path of the surface to be measured includes a first imaging objective lens 3 and a second spectroscopic plate 2-2 adjacent to the object to be measured 4; the light path of the reference surface includes a second mechanical switch 5, a second imaging objective lens 6 and a reference focal plane. 7.
  • Reference plane 7 is the best focal plane of the known objective lens.
  • the focal plane measurement optical path includes a third spectroscopic plate 8 , a lens 9 and a spectrum recorder 10 .
  • the lens 9 enters the spectrum recorder 10 .
  • the data processing module 104 is used to obtain the phase information and spectral wavelength of the interference beam, and calculate based on the phase information and spectral wavelength of the interference beam, when the surface of the object 4 to be measured is The optimal relative distance between the stage 106 and the imaging objective lens 12 when placed on the optimal focal plane; the control module 104 is used to control the driving part to drive the stage 7 perpendicular to the location of the stage. Move in the direction of the plane so that the relative distance between the stage and the imaging objective lens reaches the optimal relative distance.
  • the optimal focal plane refers to the focal plane with the best imaging effect
  • the optimal relative distance refers to the distance between the stage 106 and the imaging objective 12 when the surface to be measured is placed on the optimal focal plane. distance. It can be seen that this device uses the principle of white light interference ranging to calculate the optimal relative distance between the stage and the imaging objective lens when the object to be measured is in the optimal focal plane, thereby avoiding multiple scans of the image and saving scanning time. Improve productivity.
  • the device also includes an imaging module 103, which is used to collect the imaging beam formed after the detection beam is reflected by the object 7 when the surface to be measured of the object to be measured 7 is placed on the optimal focal plane.
  • the object to be measured 7 is imaged to form image information.
  • the data processing module 104 is also configured to obtain the image information from the imaging module 12 and perform overlay measurement on the image information.
  • the imaging module 103 includes a third beam splitting plate 8, an imaging objective lens 11 and a camera 12; when the surface to be measured of the object 4 to be measured is placed on the optimal focal plane, the second The detection beam passes through the first dichroic plate 2-1, the second dichroic plate 2-2 and the first imaging objective lens 3 and is incident on the object to be measured 4, and is reflected by the surface of the object to be measured 4 to form The third reflected light beam passes through the third beam splitting plate 8 , the imaging objective lens 11 and the camera 12 in sequence to form an imaging light beam.
  • the camera 12 is used to collect the imaging beam to image the object 4 to be measured.
  • the data processing module 104 obtains the image information from the imaging module 12 and performs overlay measurement or optical detection on the image information.
  • the lighting module in the optical detection device includes a focus Light source 1-1, first polarizer 3-1, first beam splitting plate 2-1, imaging light source 1-2 and second polarizer 3-2.
  • the focusing module includes a light path of the surface to be measured, a reference surface light path and a focal surface measurement light path;
  • the light path of the surface to be measured includes a first imaging objective lens 3 and a second spectroscopic plate 2-2 adjacent to the object to be measured 4;
  • the reference plane optical path includes the analyzer 3-3, the second imaging objective lens 6 and the reference focal plane 7;
  • the focal plane measurement optical path includes the third spectroscopic plate 8, the lens 9 and the spectrum recorder 10.
  • the polarization direction of the analyzer 3-3 is the same as the polarization direction of the first polarizer 3-1, but orthogonal to the polarization direction of the second polarizer 3-2.
  • the first detection beam emitted by the focusing light source 1-1 passes through the spectroscopic plates 2-1 and 2-2.
  • One beam enters the imaging optical path to obtain the focal plane information of the object to be measured 4, and the other beam enters the reference surface optical path. , obtain the information of reference focal plane 7.
  • the reflected beams of the object to be measured 4 and the reference focal plane 7 pass through the spectroscopic plate 2-2 and merge into one beam and undergo white light interference. They pass through the spectroscopic plate 8 and enter the spectrum recorder 10.
  • the spectrum recorder 10 records the interference pattern and transmits the data.
  • the signal is sent to the data processing module 13.
  • the data processing module 13 analyzes the phase information of the two arms in the spectral interference fringes.
  • the absolute distance is detected, and the relative distance between the object plane of the object 4 and the reference focal plane can be obtained. , thus focusing can be achieved.
  • the accuracy can be achieved within 10 nm, and the entire focal plane measurement process does not require multiple scans.
  • the second detection beam emitted by the imaging light source 1-2 can pass through the spectroscopic plates 2-1 and 2-2.
  • One beam enters the imaging light path to obtain the object surface information of the object 4 to be measured, and the other beam enters the reference light path and is Analyzer 5 intercepts.
  • the reflected light of the object to be measured 4 is transmitted through the spectroscopic plate 8 and is finally imaged on the camera 12 . Due to the special setting of polarization, the reflected light from the reference focal plane 7 and the broad spectrum white light emitted by the focus light source 1-1 will not enter the camera 12, and therefore will not affect the imaging.
  • the data processing module 104 is also used to obtain the light intensity of the interference beam, and determine the light intensity of the detection optical path module according to the light intensity of the interference beam. Adjustment amount; the lighting module 101 is connected to the data processing module 104, and the lighting module 101 is also used to adjust the light intensity of the detection beam according to the light intensity adjustment amount.
  • FIG. 3 is a flow chart of an optical detection method according to an embodiment of the present invention. As shown in Figure 3, the optical detection method can be executed by the controller, and the method includes the following steps:
  • the spectrum recorder is used to record the phase information and spectral wavelength of the interference beam formed after the detection beam is reflected by the object to be measured and the reference focal plane respectively.
  • the method also includes: controlling the imaging module to collect the imaging beam formed after the detection beam is reflected by the object to be measured when the surface to be measured of the object to be measured is placed on the optimal focal plane, and the The object to be measured is imaged to form image information; the data processing module is controlled to obtain the image information from the imaging module and perform overlay measurement on the image information.
  • the controller does not need to control the mechanical switch.
  • the optical detection device and method proposed in the embodiments of the present invention calculate the distance between the stage and the stage when the object to be measured is in the best focal plane by using the principle of white light interference distance measurement using the spectrum recorder.
  • the optimal relative distance between imaging objectives avoids scanning images multiple times, saves scanning time, and improves productivity;
  • the light source of the focusing system and the light source of the imaging system are separated, and a special optical path design is used to make the two light sources They are provided to the focusing system and imaging system respectively without interfering with each other, so that the spectrometer ranging technology can be better utilized while ensuring productivity.

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Abstract

一种光学检测装置及方法，光学检测装置包括用于承载待测对象（4）的载物台（106）和用于向待测对象（4）发射检测光束的照明模块（101），以及对焦模块（102），用于通过光学组件将检测光束经分光分别射入待测对象（4）和参考焦面（7），并通过光学组件汇聚至光谱记录仪（10）；数据处理模块（104），用于获取干涉光束的相位信息和光谱波长，并根据干涉光束的相位信息和光谱波长计算，当待测对象（4）的待测面置于最佳焦面时载物台（106）相对于成像物镜（3）之间的最佳相对距离；控制模块（105），用于控制驱动部驱动载物台（106）在垂直于载物台（106）所在平面的方向上运动，使载物台（106）相对于成像物镜（3）之间的相对距离达到最佳相对距离。装置用以在保证光学检测准确度的基础上提高检测效率。

Description

一种光学检测装置及方法
交叉引用
本申请要求2022年3月22日提交的申请号为202210298714X的中国专利申请的优先权。上述申请的内容以引用方式被包含于此。
技术领域
本发明涉及光学检测技术领域，尤其涉及一种光学检测装置及方法。
技术背景
近年来随着工业自动化、智能化的深入及普及，使用自动光学检测设备(Auto Optical Inspection，AOI)替代传统的人工目检，已成为技术发展趋势。AOI设备凭借其快速、精确的缺陷识别定位能力，在汽车、医药、交通、半导体等领域广泛使用。
目前，现有的AOI设备通常包括光学成像模块、载物台、物料传输系统等。其中光学成像模块包括照明单元、成像物镜和探测器等。通常AOI设备检测过程中，需要将待测面调整到最佳焦面，以获得清晰的图片，便于识别待测表面的缺陷。一般地，现有技术采用光学系统在垂直载物台方向上对待测对象进行扫描拍图，但扫描过程占用一定时长，影响了生产流水线上的检测效率。
基于上述背景，如何在保证光学检测准确度的基础上，对检测效率进行提升和优化，成为当前面临的一个技术难题。
发明概要
本发明实施例提供一种光学检测装置及方法，用以在保证光学检测准确度的基础上提高检测效率。
第一方面，本发明提供一种光学检测装置，包括用于承载待测对象的载物台，以及用于向所述待测对象发射检测光束的照明模块，以及对焦模块，用于通过光学组件将所述检测光束经分光分别射入待测对象和参考焦面，并通过光学组件汇聚至光谱记录仪；所述光谱记录仪，用于记录所述检测光束经所述待测对象和参考焦面分别反射后的干涉光束的相位信息和光谱波长。该光学检测装置还包括数据处理模块，用于获取所述干涉光束的相位信息和光谱波长，并根据所述干涉光束的相位信息和光谱波长计算，当所述待测对象的待测面置于最佳焦面时所述载物台与成像物镜之间的最佳相对距离。控制模块，用于控制驱动部驱动所述载物台在垂直于所述载物台所在平面的方向上运动，使得载物台与成像物镜之间的相对距离达到所述最佳相对距离。
本发明提供的光学检测装置的有益效果在于：本实施例中数据处理模块利用白光干涉测距的原理，通过干涉光束的相位信息和光谱波长计算待测对象的待测面置于最佳焦面时所述载物台与成像物镜之间的最佳相对距离，基于该最佳相对距离可以实现一次调整载物台，使得完成对焦过程，这样就可以避免对待测对象进行多次扫描拍图，节省了对焦时长，实现在保证光学检测准确度的基础上提高检测效率。
可选地，该光学检测装置还包括成像模块，用于在所述待测对象的待测面置于最佳焦面时，采集所述检测光束经所述待测对象反射后的成像光束，对待测对象进行成像形成图像信息。所述数据处理模块，还用于从所述成像模块获取所述图像信息，并对所述图像信息进行光学检测。
可选地，所述数据处理模块还用于获取所述干涉光束的光强，并根据所述干涉光束的光强确定所述检测光路模块的光强调整量；所述检测光路模块和所述数据处理模块连接，所述检测光路模块还用于根据所述光强调整量调整所述检测光束的光强。
可选地，所述照明模块包括对焦光源、第一机械开关、第一分光平板和成像光源；对焦光源用于出射第一检测光束，成像光源用于出射第二检测光束，第一机械开关，用于控制所述第一检测光束对应的对焦光路的开启或关闭；
所述对焦模块包括待测面光路、参考面光路和焦面测量光路；所述待测面光路包括临近所述待测对象的第一成像物镜、第二分光平板；所述参考面光路包括第二机械开关、第二成像物镜和参考焦面；所述焦面测量光路包括第三分光平板、透镜和光谱记录仪；
在第一机械开关打开时，所述第一检测光束和所述第二检测光束均经过所述第一分光平板、所述第二分光平板和所述第一成像物镜入射至所述待测对象，经所述待测对象表面反射形成第一反射光束；以及在第二机械开关打开时，所述第一检测光束和所述第二检测光束均经过所述第一分光平板、所述第二分光平板和所述第二成像物镜入射至所述参考焦面，经所述参考焦面表面反射形成第二反射光束，所述第一反射光束和所述第二反射光束形成所述干涉光束，所述干涉光束经所述透镜射入所述光谱记录仪。
可选地，所述照明模块包括对焦光源、第一起偏器、第一分光平板、成像光源和第二起偏器。所述对焦模块包括待测面光路、参考面光路和焦面测量光路；所述待测面光路包括临近所述待测对象的第一成像物镜、第二分光 平板；所述参考面光路包括第二机械开关、第二成像物镜和参考焦面；所述焦面测量光路包括第三分光平板、检偏器、透镜和光谱记录仪；所述检偏器的的偏振方向与所述第一起偏器的偏振方向相同，但与所述第二起偏器的偏振方向正交。
所述第一检测光束和所述第二检测光束均经过第一分光平板、所述第二分光平板和所述第一成像物镜入射至所述待测对象，经所述待测对象表面反射形成第一反射光束；以及所述第一检测光束经过所述第一分光平板、所述第二分光平板、检偏器、和所述第二成像物镜入射至参考焦面，经所述参考焦面表面反射形成第二反射光束，所述第一反射光束和所述第二反射光束形成所述干涉光束，所述干涉光束经透镜射入所述光谱记录模块。
可选地，所述对焦光源为宽光谱的光源。
可选地，所述宽光谱的光源为白光光源。
第二方面，本发明还提供一种光学检测方法，该方法可以应用如第一方面任一实施方式所述的光学检测装置，该方法包括：
控制照明模块向待测对象发射检测光束，所述待测对象置于载物台上；
控制对焦模块通过光学组件将所述检测光束经分光分别射入待测对象和参考焦面，并通过光学组件汇聚至光谱记录仪；所述光谱记录仪，用于记录所述检测光束经所述待测对象和参考焦面分别反射后形成的干涉光束的相位信息和光谱波长；
获取所述干涉光束的相位信息和光谱波长，并根据所述干涉光束的相位信息和光谱波长计算，当所述待测对象的待测面置于最佳焦面时所述载物台 在垂直于所述载物台与成像物镜之间的最佳相对距离；控制模块，用于控制驱动部驱动所述载物台在垂直于所述载物台所在平面的方向上运动，使得载物台与成像物镜之间的相对距离达到所述最佳相对距离。
可选地，所述方法还包括：控制所述成像模块在所述待测对象的待测面置于最佳焦面时，采集所述检测光束经所述待测对象反射后的成像光束，对所述待测对象进行成像形成图像信息；控制所述数据处理模块从所述成像模块获取所述图像信息，并对所述图像信息进行套刻测量。
与现有技术相比，本发明实施例提出的光学检测装置和方法，一方面通过将光谱记录仪利用白光干涉测距的原理计算待测对象处于最佳焦面时载物台与成像物镜之间的最佳相对距离，避免多次扫描图像，节省扫描时长，提高产率；另一方面，将对焦系统的光源和成像系统的光源分离，并利用特殊的光路设计使两个光源分别提供给对焦系统和成像系统，而互不干扰，这样在保证产率的前提下，可以更好的利用光谱仪测距技术。
附图说明
为了更清楚地说明本发明实施例中的技术方案，下面将对实施例描述中所需要使用的附图作简要介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域的普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为本发明实施例提供的一种光学检测装置结构示意图；
图2为本发明实施例提供的另一种光学检测装置结构示意图；
图3为本发明实施例提供的一种光学检测方法流程示意图。
附图标记
照明模块101、对焦模块102、成像模块103、数据处理模块104、控制模块105和载物台106；
对焦光源1-1、成像光源1-2；
第一分光平板2-1、第二分光平板2-2、第三分光平板8；
第一机械开关14、第二机械开关5；
待测对象4、第一成像物镜3、第二成像物镜6、参考焦面7；
透镜9、光谱记录仪10；
成像物镜11和相机12；
第一起偏器3-1、第二起偏器3-2和检偏器3-3
发明内容
为使本发明的内容更加清楚易懂，以下结合说明书附图，对本发明的内容作进一步说明。当然本发明并不局限于该具体实施例，本领域内的技术人员所熟知的一般替换也涵盖在本发明的保护范围内。
需要说明的是，在下述的具体实施方式中，在详述本发明的实施方式时，为了清楚地表示本发明的结构以便于说明，特对附图中的结构不依照一般比例绘图，并进行了局部放大、变形及简化处理，因此，应避免以此作为对本发明的限定来加以理解。
图1是本发明实施例提出的光学检测装置的结构示意图。如图1所示，该光学检测装置包括：照明模块101、对焦模块102、成像模块103、数据处理模块104、控制模块105和载物台106。其中：
载物台106，用于承载待测对象4。待测对象4可以是晶圆或者其他半导体器件。
照明系统101，用于向所述待测对象4发射检测光束。如图1所示，所述照明系统01包括对焦光源1-1、第一机械开关14、成像光源1-2和第一分光平板2-1。对焦光源1-1用于出射第一检测光束，成像光源1-2用于出射第二检测光束。对焦光源可以是宽光谱光源。一种可能的实施例中，对焦光源是白光光源，以便利用光谱仪测距，而且采用两个光源的设计，并利用特殊的光路设计使两个光源分别提供给对焦系统和成像系统，而互不干扰。第一机械开关14打开时，对焦光源1-1出射的第一检测光束经第一机械开关14、第一分光平板2-1、第二分光平板2-2射入待测对象4和参考焦面7。第一机械开关14关闭时，对焦光源1-1出射的第一检测光束不会射入待测对象4和参考焦面7。
对焦模块102包括待测面光路、参考面光路和焦面测量光路。所述待测面光路包括临近所述待测对象4的第一成像物镜3、第二分光平板2-2；所述参考面光路包括第二机械开关5、第二成像物镜6和参考焦面7，参考面7为已知物镜的最佳焦面。所述焦面测量光路包括第三分光平板8、透镜9和光谱记录仪10。在第二机械开关5打开时，所述第一检测光束和所述第二检测光束均经过所述第一分光平板2-1、所述第二分光平板2-2和所述第二成像物镜6入射至所述参考焦面7，经所述参考焦面7表面反射形成的第二反射光束，所述第一反射光束和所述第二反射光束形成所述干涉光束，所述干涉光束经所述透镜9射入所述光谱记录仪10。
在焦面测量阶段，数据处理模块104，用于获取所述干涉光束的相位信 息和光谱波长，并根据所述干涉光束的相位信息和光谱波长计算，当所述待测对象4的待测面置于最佳焦面时所述载物台106与成像物镜12之间的最佳相对距离；控制模块104，用于控制驱动部驱动所述载物台7在垂直于所述载物台所在平面的方向上运动，使得载物台与成像物镜之间的相对距离达到所述最佳相对距离。
值得说明的是，最佳焦面指的是成像效果最佳的焦面，最佳相对距离指的是当待测面置于最佳焦面时所述载物台106与成像物镜12之间的距离。可见，该装置通过将光谱记录仪利用白光干涉测距的原理计算待测对象处于最佳焦面时载物台与成像物镜之间的最佳相对距离，避免多次扫描图像，节省扫描时长，提高产率。
所述装置还包括成像模块103，用于在所述待测对象7的待测面置于最佳焦面时，采集所述检测光束经所述待测对象7反射后形成的成像光束，对所述待测对象7进行成像形成图像信息。所述数据处理模块104，还用于从所述成像模块12获取所述图像信息，并对所述图像信息进行套刻测量。
参见图1，在套刻测量阶段，所述成像模块103包括第三分光平板8、成像物镜11和相机12；在待测对象4的待测面置于最佳焦面时，所述第二检测光束经过所述第一分光平板2-1、所述第二分光平板2-2和所述第一成像物镜3入射至所述待测对象4，经所述待测对象4表面反射形成的第三反射光束，所述第三反射光束依次经过所述第三分光平板8、所述成像物镜11和所述相机12形成成像光束。所述相机12，用于采集所述成像光束对所述待测对象4进行成像。数据处理模块104从所述成像模块12获取所述图像信息，并对所述图像信息进行套刻测量或者光学检测。
本发明的另一个实施例，考虑机械开关在光学检测过程中存在开关耗时问题，本实施例还提供另一种光学检测装置，如图2所示，该光学检测装置中的照明模块包括对焦光源1-1、第一起偏器3-1、第一分光平板2-1、成像光源1-2和第二起偏器3-2。所述对焦模块包括待测面光路、参考面光路和焦面测量光路；所述待测面光路包括临近所述待测对象4的第一成像物镜3、第二分光平板2-2；所述参考面光路包括检偏器3-3、第二成像物镜6和参考焦面7；所述焦面测量光路包括第三分光平板8、透镜9和光谱记录仪10。所述检偏器3-3的的偏振方向与所述第一起偏器3-1的偏振方向相同，但与所述第二起偏器3-2的偏振方向正交。
在焦面测量过程中，对焦光源1-1发射的第一检测经过分光平板2-1和2-2，一束进入成像光路，获取待测对象4的焦面信息，一束进入参考面光路，获取参考焦面7的信息。待测对象4和参考焦面7的反射光束均经过分光平板2-2汇成一束并发生白光干涉，经过分光平板8进入到光谱记录仪10，光谱记录仪10记录干涉图，并传输数据信号到数据处理模块13中，数据处理模块13分析光谱干涉条纹中两臂相位信息，通过相位提取和展开，进行绝对距离的探测，可以获得待测对象4的物面与参考焦面的相对距离，从而可以实现对焦，本实施例中，精度可以实现在10nm以内，而且整个焦面测量过程不需要进行多次扫描。
在成像过程中，成像光源1-2发射的第二检测光束可以经过分光平板2-1和2-2，一束进入成像光路，获取待测对象4的物面信息，一束进入参考光路被检偏器5拦截。待测对象4的反射光透射过分光平板8，最终在相机12上进行成像。由于偏振的特殊设置，参考焦面7的反射光和对焦光源 1-1发出的宽光谱白光都不会进入到相机12，因此对成像不构成影响。
基于上述光学检测装置，一种可能的实施例中，所述数据处理模块104还用于获取所述干涉光束的光强，并根据所述干涉光束的光强确定所述检测光路模块的光强调整量；所述照明模块101和所述数据处理模块104连接，所述照明模块101还用于根据所述光强调整量调整所述检测光束的光强。
图3是本发明实施例的光学检测方法的流程图。如图3所示，该光学检测方法可以由控制器执行，该方法包括以下步骤：
S301，控制照明模块向待测对象发射检测光束，所述待测对象置于载物台上。
S302，控制对焦模块通过光学组件将所述检测光束经分光分别射入待测对象和参考焦面，并通过光学组件汇聚至光谱记录仪。
其中，所述光谱记录仪，用于记录所述检测光束经所述待测对象和参考焦面分别反射后形成的干涉光束的相位信息和光谱波长。
S303，控制数据处理模块获取所述干涉光束的相位信息和光谱波长，并根据所述干涉光束的相位信息和光谱波长计算，当所述待测对象的待测面置于最佳焦面时所述载物台与成像物镜之间的最佳相对距离。
S304，控制驱动部驱动所述载物台在垂直于所述载物台所在平面的方向上运动，使得载物台与成像物镜之间的相对距离达到所述最佳相对距离。
所述方法还包括：控制所述成像模块在所述待测对象的待测面置于最佳焦面时，采集所述检测光束经所述待测对象反射后形成的成像光束，对所述待测对象进行成像形成图像信息；控制所述数据处理模块从所述成像模块获 取所述图像信息，并对所述图像信息进行套刻测量。另外，在光学检测装置中不包括机械开关时，控制器则无需控制机械的开关。
综上，与现有技术相比，本发明实施例提出的光学检测装置和方法，一方面通过将光谱记录仪利用白光干涉测距的原理计算待测对象处于最佳焦面时载物台与成像物镜之间的最佳相对距离，避免多次扫描图像，节省扫描时长，提高产率；另一方面，将对焦系统的光源和成像系统的光源分离，并利用特殊的光路设计使两个光源分别提供给对焦系统和成像系统，而互不干扰，这样在保证产率的前提下，可以更好的利用光谱仪测距技术。
以上所述的仅为本发明的优选实施例，所述实施例并非用以限制本发明的专利保护范围，因此凡是运用本发明的说明书及附图内容所作的等同结构变化，同理均应包含在本发明的保护范围内。对所公开的实施例的上述说明，使本领域专业技术人员能够实现或使用本发明。
对这些实施例的多种修改对本领域的专业技术人员来说将是显而易见的，本文中所定义的一般原理可以在不脱离本发明的精神或范围的情况下，在其它实施例中实现。因此，本发明将不会被限制于本文所示的这些实施例，而是要符合与本文所公开的原理和新颖特点相一致的最宽的范围。

Claims (10)

  1. 一种光学检测装置，其特征在于，包括：
    载物台，用于承载待测对象；
    照明模块，用于向所述待测对象发射检测光束；
    对焦模块，用于通过光学组件将所述检测光束经分光分别射入待测对象和参考焦面，并通过光学组件汇聚至光谱记录仪；所述光谱记录仪，用于记录所述检测光束经所述待测对象和参考焦面分别反射后形成的干涉光束的相位信息和光谱波长；
    数据处理模块，用于获取所述干涉光束的相位信息和光谱波长，并根据所述干涉光束的相位信息和光谱波长计算，当所述待测对象的待测面置于最佳焦面时所述载物台与成像物镜之间的最佳相对距离；
    控制模块，用于控制驱动部驱动所述载物台在垂直于所述载物台所在平面的方向上运动，使得载物台与成像物镜之间的相对距离达到所述最佳相对距离。
  2. 根据权利要求1所述的光学检测装置，其特征在于，所述装置还包括：
    成像模块，用于在所述待测对象的待测面置于最佳焦面时，采集所述检测光束经所述待测对象反射后的成像光束，对所述待测对象进行成像形成图像信息；
    所述数据处理模块，还用于从所述成像模块获取所述图像信息，并对所述图像信息进行套刻测量。
  3. 根据权利要求1所述的光学检测装置，其特征在于，所述数据处理模块还用于获取所述干涉光束的光强，并根据所述干涉光束的光强确定所述检 测光路模块的光强调整量；
    所述照明模块和所述数据处理模块连接，所述照明模块还用于根据所述光强调整量调整所述检测光束的光强。
  4. 根据权利要求1所述的光学检测装置，其特征在于，所述照明模块包括对焦光源、第一机械开关、第一分光平板和成像光源；对焦光源用于出射第一检测光束，成像光源用于出射第二检测光束，第一机械开关，用于控制所述第一检测光束对应的对焦光路的开启或关闭；
    所述对焦模块包括待测面光路、参考面光路和焦面测量光路；所述待测面光路包括临近所述待测对象的第一成像物镜、第二分光平板；所述参考面光路包括第二机械开关、第二成像物镜和参考焦面；所述焦面测量光路包括第三分光平板、透镜和光谱记录仪；
    在第一机械开关打开时，所述第一检测光束和所述第二检测光束均经过所述第一分光平板、所述第二分光平板和所述第一成像物镜入射至所述待测对象，经所述待测对象表面反射形成第一反射光束；以及在第二机械开关打开时，所述第一检测光束和所述第二检测光束均经过所述第一分光平板、所述第二分光平板和所述第二成像物镜入射至所述参考焦面，经所述参考焦面表面反射形成第二反射光束，所述第一反射光束和所述第二反射光束形成所述干涉光束，所述干涉光束经所述透镜射入所述光谱记录仪。
  5. 根据权利要求4所述的光学检测装置，其特征在于，所述成像模块包括第三分光平板、成像物镜和相机；在所述待测对象的待测面置于最佳焦面时，所述第二检测光束经过所述第一分光平板、所述第二分光平板和所述第一成像物镜入射至所述待测对象，经所述待测对象表面反射形成第三反射光 束，所述第三反射光束依次经过所述第三分光平板、所述成像物镜和所述相机形成成像光束；
    所述相机，用于采集所述成像光束对所述待测对象进行成像。
  6. 根据权利要求4所述的光学检测装置，其特征在于，所述控制模块分别与所述第一机械开关和所述第二机械开关电连接，所述控制模块，还用于控制所述第一机械开关和所述第二机械开关同时打开或同时关闭。
  7. 根据权利要求1所述的光学检测装置，其特征在于，所述照明模块包括对焦光源、第一起偏器、第一分光平板、成像光源和第二起偏器；
    所述对焦模块包括待测面光路、参考面光路和焦面测量光路；所述待测面光路包括临近所述待测对象的第一成像物镜、第二分光平板；所述参考面光路包括检偏器、第二成像物镜、和参考焦面；所述焦面测量光路包括第三分光平板、透镜和光谱记录仪；所述检偏器的的偏振方向与所述第一起偏器的偏振方向相同，但与所述第二起偏器的偏振方向正交。
  8. 根据权利要求4所述的光学检测装置，其特征在于，所述对焦光源为宽光谱的光源。
  9. 一种光学检测方法，应用如权利要求1至8任一项所述的光学检测装置，其特征在于，包括：
    控制照明模块向待测对象发射检测光束，所述待测对象置于载物台上；
    控制对焦模块通过光学组件将所述检测光束经分光分别射入待测对象和参考焦面，并通过光学组件汇聚至光谱记录仪；所述光谱记录仪，用于记录所述检测光束经所述待测对象和参考焦面分别反射后形成的干涉光束的相位信息和光谱波长；
    控制数据处理模块获取所述干涉光束的相位信息和光谱波长，并根据所述干涉光束的相位信息和光谱波长计算，当所述待测对象的待测面置于最佳焦面时所述载物台与成像物镜之间的最佳相对距离；
    控制驱动部驱动所述载物台在垂直于所述载物台所在平面的方向上运动，使得载物台与成像物镜之间的相对距离达到所述最佳相对距离。
  10. 根据权利要求9所述的光学检测方法，其特征在于，所述方法还包括：
    控制所述成像模块在所述待测对象的待测面置于最佳焦面时，采集所述检测光束经所述待测对象反射后的成像光束，对所述待测对象进行成像形成图像信息；
    控制所述数据处理模块从所述成像模块获取所述图像信息，并对所述图像信息进行套刻测量。
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