WO2023178719A1 - 一种光学量测装置及方法 - Google Patents

一种光学量测装置及方法 Download PDF

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Publication number
WO2023178719A1
WO2023178719A1 PCT/CN2022/084020 CN2022084020W WO2023178719A1 WO 2023178719 A1 WO2023178719 A1 WO 2023178719A1 CN 2022084020 W CN2022084020 W CN 2022084020W WO 2023178719 A1 WO2023178719 A1 WO 2023178719A1
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imaging
light source
optical
focal plane
measured
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PCT/CN2022/084020
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English (en)
French (fr)
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兰艳平
孙刚
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上海御微半导体技术有限公司
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Publication of WO2023178719A1 publication Critical patent/WO2023178719A1/zh

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
    • G03F7/70605—Workpiece metrology
    • G03F7/70616—Monitoring the printed patterns
    • G03F7/70633—Overlay, i.e. relative alignment between patterns printed by separate exposures in different layers, or in the same layer in multiple exposures or stitching
    • 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
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/20—Exposure; Apparatus therefor
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/708—Construction of apparatus, e.g. environment aspects, hygiene aspects or materials
    • G03F7/7085—Detection arrangement, e.g. detectors of apparatus alignment possibly mounted on wafers, exposure dose, photo-cleaning flux, stray light, thermal load

Definitions

  • the present invention relates to the field of optical detection technology, and in particular, to an optical measurement device and method.
  • the object of the present invention is to provide an optical measurement device and method to improve detection accuracy and detection efficiency.
  • the present invention provides an optical measurement device, including a stage for carrying an object to be measured, an illumination system for emitting a detection beam, and a focusing system for recording the passage of the detection beam through the optical component.
  • the split light is respectively injected into the object to be measured and the reference focal plane, and is converged to the spectrum detector through the optical assembly.
  • the spectrum detector is used to record the information of the interference beam formed after the detection beam is reflected by the object to be measured and the reference focal plane.
  • the device also includes The imaging system is used to collect the imaging beam formed after the detection beam is reflected by the object to be measured.
  • the imaging system includes the optical path of the microscope objective lens and the optical path of the camera; the focusing system and the imaging system share the optical path of the microscope objective lens.
  • the device also includes a data processing system for obtaining the information of the interference beam from the spectrum detector, performing focal plane measurement of the object to be measured based on the information of the interference beam, and obtaining the image information formed by the imaging beam from the imaging system, and based on the image information Carry out overlay measurements on the object to be tested.
  • a data processing system for obtaining the information of the interference beam from the spectrum detector, performing focal plane measurement of the object to be measured based on the information of the interference beam, and obtaining the image information formed by the imaging beam from the imaging system, and based on the image information Carry out overlay measurements on the object to be tested.
  • the beneficial effect of the optical measurement device provided by the present invention is that the sampling pulse light source of this embodiment replaces the traditional continuous light source, which can greatly reduce the sampling time, reduce the impact of platform vibration, and improve measurement accuracy and productivity.
  • the lighting system also includes an infrared light source and an infrared illumination light path.
  • the measurement of infrared light is achieved by adding an infrared light source and an infrared illumination light path, which is suitable for the measurement of silicon wafers with poor visible light transmittance of some film layers, thereby improving process adaptability.
  • the pulse light source is a xenon flash lamp or a pulse laser light source, and the pulse width of the pulse light source ranges from 1 us to 30 us.
  • the reference surface optical path includes a photoelectric shutter device, an imaging objective lens and a reference surface, and the reference surface is the best focal plane of a known objective lens;
  • the focal surface measurement optical path includes an analyzer and an imaging tube lens;
  • the optical measurement device also includes a controller, the controller is connected to the focusing system, and the controller is used to control the photoelectric shutter device to be in an open state when performing focal plane measurement; when performing overlay measurement , the photoelectric shutter device is controlled to be closed. Because the traditional mechanical shutter opening and closing time is long and prone to vibration, this implementation uses a photoelectric shutter device to replace the traditional mechanical shutter switch, which can increase the shutter opening and closing time from milliseconds to microseconds.
  • the controller is also used to adjust the switching voltage of the photoelectric shutter device according to the reflectivity of the object to be measured.
  • the light transmittance of the reference optical path can be achieved, thereby ensuring that the measurement light intensity remains unchanged after the reflectivity of the measurement object changes.
  • the illumination system includes a first dichroic prism; the first dichroic prism is located on the emission path of the detection light beam.
  • the focusing system includes a second dichroic prism and a third dichroic prism, and the right-angled surfaces of the second dichroic prism and the third dichroic prism are at an angle of 45° to the receiving surface of the imaging system.
  • the focusing light source is a continuous stable light source.
  • the continuous stable light source is a white light source.
  • the present invention also provides an optical measurement method.
  • the method can apply the optical measurement device as described in any embodiment of the first aspect.
  • the method includes:
  • the spectrum detector that controls the focusing system records the information of the interference beam formed after the detection beam is reflected by the object to be measured and the reference focal plane;
  • the optical measurement device and method proposed by the embodiments of the present invention can greatly reduce the sampling time, reduce the impact of platform vibration, and improve measurement accuracy and productivity by adjusting the traditional continuous light source to a pulse light source.
  • Using a photoelectric shutter device to replace the traditional mechanical shutter switch can increase the shutter opening and closing time from milliseconds to microseconds, thus improving detection accuracy and efficiency.
  • Figure 1 is a schematic structural diagram of an optical measurement device provided by an embodiment of the present invention.
  • Figure 2 is a schematic structural diagram of another optical measurement device provided by an embodiment of the present invention.
  • 3A is a schematic diagram of the light transmission path of a photoelectric shutter device in an open state according to an embodiment of the present invention
  • 3B is a schematic diagram of the light transmission path of a photoelectric shutter device in a closed state according to an embodiment of the present invention
  • Figure 4 is a schematic structural diagram of another optical measurement device provided by an embodiment of the present invention.
  • FIG. 5 is a schematic flowchart of an optical measurement method provided by an embodiment of the present invention.
  • Illumination system 01 focus system 02, imaging system 03, data processing system 04 and stage 05
  • the first beam splitting prism 201 and the second beam splitting prism 202 are identical to each other.
  • Photoelectric shutter device 5 reference objective lens 6, reference surface 7, third beam splitting prism 8, imaging tube lens 9 and spectrum detector 10, imaging tube lens 11, camera 12, analyzer 13
  • FIG. 1 is a schematic structural diagram of an optical measurement device according to an embodiment of the present invention.
  • the optical measurement device includes: illumination system 01, focusing system 02, imaging system 03, data processing system 04 and stage 05. in:
  • Stage 05 is used to carry the object 4 to be tested.
  • the object to be tested can be a wafer or other semiconductor device.
  • Illumination system 01 used to emit detection beams.
  • the lighting system 01 includes an imaging light source 103 .
  • the imaging light source 103 is a pulse light source.
  • the pulse light source can be a xenon flash lamp or a pulse laser light source, and the pulse width of the light source can be 1 to 30 us.
  • the illumination system 01 also includes a first dichroic prism 201, and a first transparent lens group 102 and a second transparent lens group 104 disposed on both sides of the first dichroic prism 201.
  • the focusing optical path includes the focusing light beam emitted by the focusing light source 101 passing through the first transparent lens group 102 and then entering the first dichroic prism 201 and being reflected by the first dichroic prism 201 .
  • the imaging optical path includes that the imaging light beam emitted by the imaging light source 103 passes through the second transparent lens group 104 and then enters the first dichroic prism 201, and is transmitted through the first dichroic prism 201.
  • Focusing system 02 is used to separate the detection beam into the object to be measured and the reference focal plane through the optical component, and converge it to the spectrum detector through the optical component.
  • the spectrum detector is used to record the detection beam passing through the to-be-measured object. Information about the interference beam formed after reflection between the measuring object and the reference focal plane.
  • the focusing system 02 includes a microscope objective lens optical path, a reference surface optical path, and a focal plane measurement optical path.
  • the optical path to be measured includes the second dichroic prism 202 and the microscope objective lens 3 on the side adjacent to the object to be measured. After the detection beam is reflected by the second dichroic prism 202, all the reflected light passes through the microscope objective lens 3 and irradiates the object to be measured.
  • the optical path of the reference surface includes the reference surface 7 and the reference objective lens 6 . After the detection beam is transmitted through the second beam splitting prism 202 , all the transmitted light passes through the reference objective lens 6 and is irradiated to the reference surface 7 .
  • the focal plane measurement optical path includes a third dichroic prism 8, an imaging tube lens 9 and a spectrum detector 10.
  • the right-angled surfaces of the second dichroic prism 202 and the third dichroic prism 8 are both at an angle of 45° to the receiving surface of the imaging system. ° angle.
  • Focal plane measurement is achieved by mathematically processing the interference signal.
  • electro-optical detectors can be used to collect interference signals; at the same time, the principle of spectral modulation can also be used for measurement. At different vertical heights, the light intensity distribution of different wavelengths will change. By using a spectral detector to collect the spectral distribution, Thus achieving fixed focus plane measurement. It can be seen that focal plane measurement can be achieved based on the above lighting system and focusing system.
  • Imaging system 03 is used to collect the imaging beam formed after the detection beam is reflected by the object to be measured 4.
  • the imaging system 03 includes a microscope objective light path and a camera light path.
  • the microscopic objective light path includes a microscope objective lens and a camera light path. Imaging tube lens 11; the focusing system 02 and the imaging system 03 share the optical path of the microscope objective lens.
  • the camera optical path includes camera 12.
  • the data processing system 04 can obtain the image information formed by the imaging beam from the imaging system, and perform overlay measurement on the object to be measured based on the image information.
  • the reference surface optical path includes a photoelectric shutter device 5 , a reference objective lens 6 and a reference surface 7 .
  • the focal plane measurement optical path includes a focusing light source 101, an analyzer 13, and an imaging tube lens 9.
  • the focus light source 101 may be a continuous stable light source, and the continuous stable light source may be a white light source.
  • the optical measurement device further includes a controller (not shown in the figure), the controller is connected to the focusing system, and the controller is used to control the photoelectric
  • the photoelectric shutter device 5 is in an open state; when overlay measurement is performed, the photoelectric shutter device 5 is controlled to be in a closed state.
  • the analyzer 13 can ensure that the two light path branches incident on the spectrum detector 10 are consistent.
  • the photoelectric shutter device 5 includes a polarizer 501 and an electro-optical switch 502 .
  • the polarizer 501 is used to form polarized light, and the electro-optical switch 502 can be rotated to control the emission of polarized light.
  • the electro-optical switch 502 is in the open state, P-polarized light and S-polarized light pass through the polarizer 501 and the electro-optical switch 502, and the reference objective lens 6 emits S-polarized light.
  • the S-polarized light is incident on the reference surface, and then the S-polarized light is reflected It can be reflected through the reference objective lens 6, polarizer 501 and electro-optical switch 502.
  • the photoelectric shutter device 5 is used, so the transmitted light intensity can be quickly adjusted.
  • the voltage of the photoelectric shutter device can be adjusted year-on-year, thereby adjusting the light transmittance ratio, thereby Ensure the consistency of the light intensity with the reference light path.
  • an infrared light source 105 and an infrared illumination light path can be added to the device shown in Figure 1.
  • the infrared illumination light path includes an illumination lens group 106 and a spectroscopic lens 203.
  • the infrared light source The infrared light emitted from 105 is injected into the object to be measured 4 through the illumination lens group 106, the dichroic lens 203 and the dichroic lens 201, thereby achieving the measurement of infrared light, thereby increasing the accuracy of silicon wafers with poor visible light transmittance of some film layers. measurement to improve process adaptability.
  • FIG. 5 is a flow chart of an optical measurement method according to an embodiment of the present invention. As shown in Figure 5, the optical measurement method can be executed by the controller. The optical measurement method includes the following steps:
  • S504 control the data processing system to obtain the information of the interference beam from the spectrum detector, perform focal plane measurement on the object to be measured based on the information of the interference beam, and obtain the image formed by the imaging beam from the imaging system information, and perform overlay measurement on the object to be measured based on the image information.
  • the controller can also control the switching state of the photoelectric shutter device 5 according to measurement needs. Because the traditional mechanical shutter opening and closing time is long and prone to vibration, this implementation uses a photoelectric shutter device to replace the traditional mechanical shutter switch, which can increase the shutter opening and closing time from milliseconds to microseconds.
  • the optical measurement device and method proposed in the embodiments of the present invention can greatly reduce the sampling time, reduce the impact of platform vibration, and improve measurement accuracy and productivity by adjusting the traditional continuous light source to a pulse light source.
  • the photoelectric shutter device is used to replace the traditional mechanical shutter switch, which can increase the shutter opening and closing time from milliseconds to microseconds, thereby improving detection accuracy and detection efficiency.

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Abstract

一种光学量测装置及方法，光学量测装置包括用于承载待测对象（4）的载物台（05）；用于发射检测光束的照明***（01），照明***（01）包括成像光源（103）和成像光路，其中成像光源（103）为脉冲光源；对焦***（02），用于记录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探测器（10）；成像***（03），用于采集检测光束经待测对象（4）反射后的成像光束；数据处理***（04），用于从光谱探测器（10）获取干涉光束的信息，并根据干涉光束的信息对待测对象（4）进行焦面测量，以及从成像***（03）获取成像光束所形成的图像信息，根据图像信息对待测对象（4）进行套刻测量。光学量测装置及方法可以提高检测准确度且提高检测效率。

Description

一种光学量测装置及方法
交叉引用
本申请要求2022年3月22日提交的申请号为2022102845740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，尤其涉及一种光学量测装置及方法。
技术背景
随着近几年半导体行业的飞速发展，对整个生产良率要求也越来越高，这样就需要更加精准的和检测和量测设备运用到半导体的制造工艺中，而不是仅仅局限于最终的产品检测。套刻精度作为光刻工艺过程中的核心指标之一，其直接影响最终的产品良率。目前已经大量使用套刻量测设备对其套刻精度进行量测，并将量测结果作为补偿值对套刻工艺进行补偿，从而可以大大提高产品良率。
但随着光刻工艺节点不断向前发展，光刻工艺层数也在不断增加，故需要量测的层数也要增加，且工艺会更加复杂。故对量测设备的产率和工艺适应性提出了更高的要求。
现有设备上，目前限制整体量测效率最关键的因素包括相机积分时间及***振动要求。由于目前采用的连续光装置，且由于一些机械快门的运动，故采样时间长，结构稳定慢。且由于采用连续光源，对结构的的稳定性要求会更高，故严重制约了产率的提高。
基于上述背景，如何在不断提高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
本发明的目的在于提供一种光学量测装置及方法，用以提高检测准确度和检测效率。
第一方面，本发明提供一种光学量测装置，包括用于承载待测对象的载物台，和用于发射检测光束的照明***，以及对焦***，用于记录通过光学组件将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探测器，光谱探测器用于记录检测光束经待测对象和参考焦面反射后形成的干涉光束的信息，该装置还包括成像***，用于采集检测光束经待测对象反射后形成的成像光束，成像***包括显微物镜光路和相机光路；对焦***和成像***共用显微物镜光路。该装置还包括数据处理***，用于从光谱探测器获取干涉光束的信息，并根据干涉光束的信息对待测对象进行焦面测量，以及从成像***获取成像光束所形成的图像信息，根据图像信息对待测对象进行套刻测量。
本发明提供的光学量测装置的有益效果在于：本实施例采样脉冲光源替代传统的连续光源，可以大大降低采样时间，降低平台振动影响，提高测量精度和产率。
可选地，所述照明***还包括红外光源和红外照明光路。该实施方案中通过增加红外光源和红外照明光路，从而实现红外光的测量，从而适用于部分膜层对可见光透过率比较差的硅片的测量，从而提高工艺适应性。
可选地，所述脉冲光源为闪烁氙灯或者脉冲激光光源，所述脉冲光源的光源脉宽取值范围为1us～30us。
可选地，所述参考面光路包括光电式快门装置、成像物镜和参考面，所述参考面为已知物镜的最佳焦面；所述焦面测量光路包括检偏器和成像管镜；所述光学量测装置还包括控制器，所述控制器与所述对焦***连接，所述控制器，用于当进行焦面测量时，控制光电式快门装置处于开启状态；当进行套刻测量时，控制光电式快门装置处于关闭状态。因传统的机械快门开关闭时间长，并且容易产生振动，该实施方案利用光电式快门装置替代传统的机械快门开关，可以将快门开关闭时间从毫秒级提升到微秒级。
可选地，所述控制器，还用于根据待测对象的反射率调整光电式快门装置的开关电压。这样可以实现参考光路的透光比，从而保证测量对象反射率发生变化后，测量光强保证不变。
可选地，所述照明***包括第一分光棱镜；所述第一分光棱镜位于检测光束的发射路径上。
可选地，所述对焦***包括第二分光棱镜和第三分光棱镜，所述第二分光棱镜与所述第三分光棱镜的直角面均与所述成像***的接收面呈45°角。
可选地，所述对焦光源为连续稳定光源。
可选地，所述连续稳定光源为白光光源。
第二方面，本发明还提供一种光学量测方法，该方法可以应用如第一方面任一实施方式所述的光学量测装置，该方法包括：
控制照明***发射检测光束；
控制对焦***的光谱探测器记录所述检测光束均经所述待测对象和参考焦面反射后形成的干涉光束的信息；
控制成像***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；
控制数据处理***从所述光谱探测器获取所述干涉光束的信息，并根据所述干涉光束的信息对所述待测对象进行焦面测量，以及从成像***获取成像光束所形成的图像信息，根据图像信息对所述待测对象进行套刻测量。
与现有技术相比，本发明实施例提出的光学量测装置和方法，通过将传统的连续光源调整为脉冲光源，可以大大降低采样时间，降低平台振动影响，提高测量精度和产率，另外利用光电式快门装置替代传统的机械快门开关，可以将快门开关闭时间从毫秒级提升到微秒级，从而提高检测精度和检测效率。
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量测装置结构示意图；
图2为本发明实施例提供的另一种光学量测装置结构示意图；
图3A为本发明实施例提供的一种光电式快门装置处于开启状态的光传输路径示意图；
图3B为本发明实施例提供的一种光电式快门装置处于关闭状态的光传输路径示意图；
图4为本发明实施例提供的另一种光学量测装置结构结构示意图；
图5为本发明实施例提供的一种光学量测方法流程示意图。
图标说明：
照明***01、对焦***02、成像***03、数据处理***04和载物台05
对焦光源101、成像光源103、第一透明镜组102、第二透明镜组104
第一分光棱镜201、第二分光棱镜202
光电式快门装置5、参考物镜6、参考面7、第三分光棱镜8、成像管镜9和光谱探测器10、成像管镜11、相机12、检偏器13
起偏器501、电光开关502
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量测装置的结构示意图。该光学量测装置包括：照明***01、对焦***02、成像***03、数据处理***04和载物台05。其中：
载物台05，用于承载待测对象4。待测对象可以是晶圆或者其他半导体 器件。
照明***01，用于发射检测光束。如图1所示，所述照明***01包括成像光源103。本实施例中，成像光源103为脉冲光源。可选地，脉冲光源可以为闪烁氙灯或者脉冲激光光源，光源脉宽可以为1～30us。
该照明***01还包括第一分光棱镜201，以及设置于第一分光棱镜201两侧的第一透明镜组102和第二透明镜组104。其中，对焦光路包括对焦光源101发射的对焦光束经过第一透明镜组102后射入第一分光棱镜201，经由第一分光棱镜201完成反射。成像光路包括成像光源103发射的成像光束经过第二透明镜组104后射入第一分光棱镜201，经由第一分光棱镜201完成透射。
对焦***02，用于通过光学组件将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探测器，所述光谱探测器用于记录所述检测光束经所述待测对象和所述参考焦面反射后形成的干涉光束的信息。
具体来说，对焦***02包括显微物镜光路、参考面光路和焦面测量光路。待测量光路包括临近待测对象这一侧的第二分光棱镜202和显微物镜3，检测光束经过第二分光棱镜202反射后，一路反射光经过显微物镜3照射到待测对象。参考面光路包括参考面7和参考物镜6，检测光束经过第二分光棱镜202透射后，一路透射光经过参考物镜6照射到参考面7。焦面测量光路包括第三分光棱镜8、成像管镜9和光谱探测器10，所述第二分光棱镜202与所述第三分光棱镜8的直角面均与所述成像***的接收面呈45°角。待测对象4上的光斑经过显微物镜3和成像管镜9后，成像在成像管镜9的焦面上，另外，参考面7上的光斑经过参考物镜6和成像管镜9后，同样成像在 成像管镜9的焦面上。数据处理***04从所述光谱探测器10获取所述干涉光束的信息，并根据所述干涉光束的信息对所述待测对象4进行焦面测量。
具体地，在进行焦面测量时，若利用干涉原理进行测量时，当两者光程完全相同时，不产生干涉，当测量对象垂向变化时，两者产生光程差，从而产生干涉，通过对干涉信号进行数学处理，从而实现焦面测量。另外，可采用电光探测器采集干涉信号；同时，也可采用光谱调制原理进行测量，在不同垂向高度下，不同波长的光强分布会发生变化，通过采用光谱探测器对光谱分布进行采集，从而实现定焦面测量。可见，基于上述照明***和对焦***可以实现焦面测量。
成像***03，用于采集所述检测光束经所述待测对象4反射后形成的成像光束，所述成像***03包括显微物镜光路和相机光路，所述显微物镜光路包括显微物镜和成像管镜11；所述对焦***02和成像***03共用显微物镜光路。相机光路包括相机12。
具体地，在套刻测量时，检测光束经过第二分光棱镜202后，反射光经过显微物镜3照射到待测对象4上的标记，经过显微物镜3和成像管镜11反射后的成像光束射入到相机12上，数据处理***04通过算法对标记进行计算，从而获取套刻误差。可见，在套刻测量过程中，数据处理***04可以从成像***获取成像光束所形成的图像信息，根据图像信息对所述待测对象进行套刻测量。
一种可能的实施例中，如图2所示，参考面光路包括光电式快门装置5、参考物镜6和参考面7。所述焦面测量光路包括对焦光源101和检偏器13和成像管镜9。对焦光源101可以为连续稳定光源，该连续稳定光源可以为 白光光源。该实施例中，所述光学量测装置还包括控制器(图中未示出)，所述控制器与所述对焦***连接，所述控制器，用于当进行焦面测量时，控制光电式快门装置5处于开启状态；当进行套刻测量时，控制光电式快门装置5处于关闭状态。检偏器13可以保证射入到光谱探测器10的两个光路分支是一致的。
参见图3A所示，光电式快门装置5包括起偏器501和电光开关502。起偏器501用于形成偏振光，电光开关502能够被旋转，用于控制偏振光的出射。当电光开关502处于开启状态时，P偏振光和S偏振光经过起偏器501和电光开关502，以及参考物镜6出射S偏振光，该S偏振光射入参考面，然后反射的S偏振光可以经过参考物镜6、起偏器501和电光开关502反射出来。
参见图3B所示，当电光开关502处于关闭状态时，P偏振光和S偏振光经过起偏器501和电光开关502，以及参考物镜6出射S偏振光，该S偏振光射入参考面，然后反射的S偏振光经过参考物镜6和起偏器501，无法从电光开关502射出，进而实现阻断光束。
上述实施方案中，因采用光电式快门装置5，所以可以快速调整透光光强，当待测对象4的反射率发生变化时，可以同比调整光电式快门装置电压，从而调整透光比，从而保证与参考光路的光强的一致性。
本发明的另一个实施例，如图4所示，还可以在图1所示的装置的基础上增加红外光源105和红外照明光路，红外照明光路包括照明镜组106和分光透镜203，红外光源105出射的红外光经照明镜组106、分光透镜203和分光透镜201射入待测对象4，从而实现红外光的测量，继而增加了对部分 膜层对可见光透过率比较差的硅片的测量，从而提高工艺适应性。
图5是本发明实施例的光学量测方法的流程图。如图5所示，该光学量测方法可以由控制器执行，该光学量测方法包括以下步骤：
S501，控制照明***发射检测光束。
S502，控制对焦***的光谱探测器记录所述检测光束均经所述待测对象和参考焦面反射后形成的干涉光束的信息。
S503，控制成像***采集所述检测光束经所述待测对象反射形成后的成像光束。
S504，控制数据处理***从所述光谱探测器获取所述干涉光束的信息，并根据所述干涉光束的信息对所述待测对象进行焦面测量，以及从成像***获取成像光束所形成的图像信息，根据图像信息对所述待测对象进行套刻测量。
另外，控制器还可以根据测量需要，控制光电式快门装置5的开关状态。因传统的机械快门开关闭时间长，并且容易产生振动，该实施方案利用光电式快门装置替代传统的机械快门开关，可以将快门开关闭时间从毫秒级提升到微秒级。
综上，与现有技术相比，本发明实施例提出的光学量测装置和方法，通过将传统的连续光源调整为脉冲光源，可以大大降低采样时间，降低平台振动影响，提高测量精度和产率，另外利用光电式快门装置替代传统的机械快门开关，可以将快门开关闭时间从毫秒级提升到微秒级，从而提高检测精度和检测效率。
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. 一种光学量测装置，其特征在于，包括：
    载物台，用于承载待测对象；
    照明***，用于发射检测光束，所述照明***包括照明光源和照明光路，其中，所述成像光源为脉冲光源；
    对焦***，用于通过光学组件将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探测器，所述光谱探测器用于记录所述检测光束经所述待测对象和所述参考焦面反射后形成的干涉光束的信息；所述对焦***包括显微物镜光路、参考面光路和焦面测量光路，所述焦面测量光路包括所述所述光谱探测器；
    成像***，用于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，所述成像***包括显微物镜光路和相机光路，所述显微物镜光路包括显微物镜和成像管镜；对焦***和成像***共用显微物镜光路；
    数据处理***，用于从所述光谱探测器获取所述干涉光束的信息，并根据所述干涉光束的信息对所述待测对象进行焦面测量，以及从成像***获取成像光束所形成的图像信息，根据图像信息对所述待测对象进行套刻测量。
  2. 根据权利要求1所述的光学量测装置，其特征在于，所述照明***还包括红外光源和红外照明光路。
  3. 根据权利要求1或2所述的光学量测装置，其特征在于，所述脉冲光源为闪烁氙灯或者脉冲激光光源，所述脉冲光源的光源脉宽取值范围为1us～30us。
  4. 根据权利要求1所述的光学量测装置，其特征在于，所述参考面光路 包括光电式快门装置、成像物镜和参考面，所述参考面为已知物镜的最佳焦面；
    所述焦面测量光路包括对焦光源、检偏器和成像管镜；
    所述光学量测装置还包括控制器，所述控制器与所述对焦***连接，所述控制器，用于当进行焦面测量时，控制光电式快门装置处于开启状态；当进行套刻测量时，控制光电式快门装置处于关闭状态。
  5. 根据权利要求4所述的光学量测装置，其特征在于，所述控制器，还用于根据待测对象的反射率调整所述光电式快门装置的开关电压。
  6. 根据权利要求1所述的光学量测装置，其特征在于，所述照明***包括第一分光棱镜；所述第一分光棱镜位于检测光束的发射路径上。
  7. 根据权利要求6所述的光学量测装置，其特征在于，所述对焦***包括第二分光棱镜和第三分光棱镜，所述第二分光棱镜与所述第三分光棱镜的直角面均与所述成像***的接收面呈45°角。
  8. 根据权利要求4所述的光学量测装置，其特征在于，所述对焦光源为连续稳定光源。
  9. 根据权利要求8所述的光学量测装置，其特征在于，所述连续稳定光源为白光光源。
  10. 一种光学量测方法，应用如权利要求1至8任一项所述的光学量测装置，其特征在于，包括：
    控制照明***发射检测光束；
    控制对焦***的光谱探测器记录所述检测光束均经所述待测对象和参考焦面反射后形成的干涉光束的信息；
    控制成像***采集所述检测光束经所述待测对象反射形成后的成像光束；
    控制数据处理***从所述光谱探测器获取所述干涉光束的信息，并根据所述干涉光束的信息对所述待测对象进行焦面测量，以及从成像***获取成像光束所形成的图像信息，根据图像信息对所述待测对象进行套刻测量。
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