Patent Publication Number: US-2022214288-A1

Title: Optical device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 U.S.C. § 119 to Japan Patent Application No. 2021-001199, filed on Jan. 7, 2021, in the Japan Intellectual Property Office, and Korean Patent Application No. 10-2021-0141900, filed on Oct. 22, 2021, in the Korean Intellectual Property Office, the disclosures of which are incorporated by reference herein in their entirety. 
     BACKGROUND 
     The inventive concept relates to an optical device, for example, an optical device for measuring a shape error of a three-dimensional structure formed on a wafer in a semiconductor device manufacturing process. 
     In a semiconductor device manufacturing process, it is necessary to measure the shape of a three-dimensional structure formed on a wafer, which affects device performance. Since dimensions of patterns of semiconductor devices to be measured are smaller than the resolution of a conventional optical microscope, it may be difficult to measure shapes of patterns using an optical microscope. Therefore, to directly measure the shapes of the patterns of semiconductor devices, a method with higher resolution, such as an electron microscope, is required, but electron microscopes have a problem in that the measurement time is too long. 
     An indirect optical measurement device including scatterometry has become indispensable for mass production of semiconductor devices in terms of measurement speed. In this case, the indirect optical measurement device may obtain an average shape of an illumination area by using a response such as reflectance without directly resolving the shape of the object to be observed. 
     On the other hand, along with the miniaturization of patterns of the devices, the required measurement accuracy is further increased, and it is necessary to detect lowered error signals with a good sensitivity. 
     In U.S. Pat. No. 8,054,467, by placing the detector on the conjugate pupil plane (i.e., Fourier transform plane) of the objective lens, not on the pattern of the device formed on the wafer as in a conventional optical microscope, methods of detecting a diffraction pattern appearing on the pupil plane or a change in the intensity of distribution within the pupil plane and performing high-sensitivity critical dimension (CD) measurement, pattern overlay measurement, or the like have been proposed. 
     SUMMARY 
     A semiconductor device is constructed by stacking various patterns by hundreds of manufacturing processes. The device pattern dimensions have been refined not only in the plane direction but also three-dimensionally, and the distance in the depth direction between the respective lamination patterns is also shortened. 
     Since the semiconductor device contains a light-transmitting material, when optical measurement is performed, mixing of signals from other than the pattern of the measurement object becomes a factor of measurement noise, thereby reducing measurement sensitivity. Noise due to signal mixing becomes more pronounced/significant as the distance between the stacked patterns becomes shorter. 
     In Critical Dimension (CD) metrology, which measures the dimensions of a device, a signal derived from an underlying pattern other than the pattern of a process to be measured in the vicinity of the surface becomes measurement noise, which may reduce the measurement accuracy. 
     In the conventional overlay measurement, in addition to the device pattern, a pattern for overlay measurement with a larger dimension than the device pattern was formed and measured, but due to the miniaturization of the device pattern, the error between the overlay measurement result in the pattern exclusively formed for overlay measurement and the overlay of the actual device is increasing. Accordingly, overlay measurement using a device pattern is required. In overlay measurement, when the overlay error of the patterns included in the two layers closest to the surface is measured, signals of the underlying patterns become noise, which may reduce measurement accuracy. 
     In U.S. Pat. No. 8,054,467, there is a problem in that unnecessary information of underlying layers of devices outside the focus of the optical system is detected together with a signal to be measured. 
     According to an aspect of the inventive concept, there is provided an optical device. The optical device includes: a light source configured to generate an input light; a pinhole plate on a path of the input light between the light source and an objective lens; a first lens arranged on the path of the input light passing through the pinhole plate and configured to collimate the input light so that the input light becomes a parallel light; an image sensor configured to detect a reflected light generated by the input light passing through the first lens being reflected by a sample; and a noise filter on a path of the reflected light between the image sensor and the objective lens, wherein the noise filter may be configured to remove a part of the reflected light generated by underlying layers below a measurement target layer of the sample among the reflected light. 
     According to another aspect of the inventive concept, there is provided an optical device. The optical device includes: a point light source configured to generate an input light; a first lens configured to collimate the input light such that the input light becomes a parallel light; an illumination pupil shape controller configured to modify the input light having passed through the first lens; a beam splitter configured to reflect the input light having passed through the illumination pupil shape controller toward a sample, and transmit a reflected light from the sample; an objective lens arranged on an optical path of the input light after the beam splitter, the objective lens configured to focus the input light to the sample, and to collimate the reflected light from the sample such that the reflected light becomes a parallel light; a second lens configured to focus the reflected light passing through the objective lens; a noise filter including a first noise filter plate with a pinhole arranged on a focus of the second lens for the reflected light; and an image sensor configured to detect the reflected light passing through the noise filter, wherein the noise filter may be configured to remove a part of the reflected light generated by underlying layers below a measurement target layer of the sample among the reflected light. 
     According to another aspect of the inventive concept, there is provided an optical device. The optical device includes: a point light source configured to generate an input light; a first lens configured to collimate the input light such that the input light becomes a parallel light; an illumination pupil shape controller configured to modify the input light passing through the first lens; a first objective lens configured to focus the input light passing through an illumination pupil shape controller toward a sample, the input light being incident obliquely on the sample; a second objective lens configured to collimate the reflected light such that the reflected light generated as the input light is reflected by the sample becomes a parallel light, the reflected light being reflected obliquely with respect to the sample; a second lens configured to focus the reflected light passing through the second objective lens; a noise filter including a first noise filter plate with a pinhole arranged on a focus of the second lens for the reflected light; and an image sensor configured to detect the reflected light passing through the noise filter, and wherein the noise filter may remove a part of the reflected light generated by underlying layers below a measurement target layer of the sample among the reflected light. 
     According to another aspect of the inventive concept, there is provided a method of manufacturing a semiconductor device. The method includes: acquiring an image of a sample by detecting a reflected light generated by an input light being reflected by the sample; and removing a noise by diffracted light from the image, wherein the acquiring of the image of the sample includes: modifying the input light; focusing the modified input light on the sample; collimating the reflected light so that the reflected light generated as the input light is reflected by the sample becomes a parallel light; and removing a part of the reflected light generated by underlying layers below a measurement target layer of the sample among the reflected light using a pinhole plate including a pinhole, and wherein the diffracted light may be generated by the pinhole plate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the inventive concept will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a schematic side view illustrating an optical device according to example embodiments; 
         FIG. 2  is a diagram illustrating part of an optical device according to example embodiments; 
         FIG. 3  is a diagram for describing a noise canceling device according to example embodiments; 
         FIGS. 4A and 4B  are diagrams for explaining a noise canceling device according to example embodiments; 
         FIGS. 5A to 5C  are diagrams for explaining a noise canceling device according to example embodiments; 
         FIG. 6  is a diagram for describing an illumination pupil shape controller of an optical device according to example embodiments; 
         FIG. 7  is a diagram for explaining a series of operations for removing noise of an optical device according to example embodiments; 
         FIG. 8  is a diagram for describing a noise canceling device according to example embodiments; 
         FIG. 9  is a schematic side view illustrating an optical device according to example embodiments; and 
         FIG. 10  is a flowchart illustrating a method of inspecting a semiconductor device according to example embodiments. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, embodiments of the inventive concept will be described with reference to the drawings. 
       FIG. 1  is a schematic side view for explaining an optical device  100  according to example embodiments. 
     Referring to  FIG. 1 , the optical device  100  may include a light source  101 , a pinhole plate  102 , a first lens  103 , an illumination pupil shape controller  104 , a first polarization controller  105 , a beam splitter  106 , an objective lens  107 , a second polarization controller  108 , a second lens  110 , a noise canceling device  111 , a third lens  112 , an image sensor  113 , and a processor  114 . 
     The light source  101  may generate an input light IL irradiated to a sample  150 . As a non-limiting example, the light source  101  may be a laser light source. As a non-limiting example, the light source  101  may be a variable wavelength light source capable of adjusting the wavelength of the input light IL. An embodiment of the variable wavelength light source may include a turret structure including a lamp light source and a plurality of filters. As a non-limiting example, the light source  101  may generate a broadband light. 
     The pinhole plate  102  may form/modify the input light IL into light generated by a point light source by confining the input light IL generated by the light source  101 . The pinhole plate  102  may include, for example, a pinhole  102 H that is a circular light-transmitting part on the optical axis of the light source  101 . For example, the optical axis of the light source  101  and/or the input light IL may pass through the center of the circular light-transmitting part of the pinhole plate  102 . 
     The input light IL passing through the pinhole plate  102  may be transferred to the first lens  103 . According to example embodiments, the first lens  103  may collimate the input light IL passing through the first lens  103 . In example embodiments, the input light IL having passed through the first lens  103  may be parallel light. 
     The input light IL having passed through the first lens  103  may be transferred to the illumination pupil shape controller  104 . The illumination pupil shape controller  104  may control a shape of a luminous flux of the input light IL having passed through the first lens  103 . The illumination pupil shape controller  104  may include a light-shielding part. As will be described later, by forming/modifying the input light IL by the illumination pupil shape controller  104 , in the processing after image detection by the image sensor  113 , an interpolation operation for removing diffraction generated in the pinhole  111 H of the noise canceling device  111  is enabled. Noise canceling devices described in this disclose may be also referred to as noise filters. 
     As shown in  FIG. 6 , the illumination pupil shape controller  104  may be a ring-shaped filter including a first light-shielding part  104 C 1  in the center part, a ring-shaped light-transmitting part  140 T surrounding the first light-shielding part  104 C 1 , and a second light-shielding part  104 C 2  of an edge surrounding the ring-shaped light-transmitting part  140 T. Accordingly, the beam cross-section of the input light IL having passed through the illumination pupil shape controller  104  may have a ring shape. 
     The input light IL passing through the illumination pupil shape controller  104  may be transferred to the first polarization controller  105 . The first polarization controller  105  may transmit a preset polarization component among the input light IL from the illumination pupil shape controller  104 . 
     The input light IL passing through the first polarization controller  105  may be transferred to the beam splitter  106 . The beam splitter  106  may transfer the input light IL to the objective lens  107  by reflecting the input light IL from the first polarization controller  105 . The objective lens  107  may focus the input light IL coming from the beam splitter  106  on the surface of the sample  150  to be measured/inspected. In addition, the objective lens  107  may refract the reflected light RL from the sample  150 . The reflected light RL refracted by the objective lens  107  may be collimated to be parallel light, but is not limited thereto. 
     The reflected light RL passing through the objective lens  107  may be transferred to the beam splitter  106 . The beam splitter  106  may transmit the reflected light RL. 
     The reflected light RL passing through the beam splitter  106  may be transferred to the second polarization controller  108 . The second polarization controller  108  may transmit a preset polarization component among the reflected light RL passing through the beam splitter  106 . 
     The reflected light RL passing through the second polarization controller  108  may be transferred to the second lens  110 . The second lens  110  may focus the reflected light RL on the pinhole  111 H of the noise canceling device  111 . Accordingly, the focus of the reflected light RL passing through the second lens  110  may be on the pinhole  111 H of the noise canceling device  111 . 
     The reflected light RL passing through the second lens  110  may be transferred to the noise canceling device  111 . The noise canceling device  111  may include, for example, a pinhole  111 H that is a circular light-transmitting part on the optical axis of the reflected light RL. For example, the optical axis of the reflected light RL may pass through the center of the circular light-transmitting part of the noise canceling device  111 . 
     The noise canceling device  111  may be arranged on a sample conjugate plane with respect to the optical axis direction. Also, the center of the pinhole  102 H of the pinhole plate  102  may be on the optical axis of the input light IL, and the center of the pinhole  111 H of the noise canceling device  111  may be on the optical axis of the reflected light RL. 
     The noise canceling device  111  may be a pinhole plate including the pinhole  111 H. The noise canceling device  111  may remove the reflected light RL of layers (e.g., the underlying layers  130  (see  FIG. 2 )) other than the measurement target layers  151  (see  FIG. 2 ) (e.g., two layers from the surface) of the sample  150 . 
     The reflected light RL passing through the noise canceling device  111  may be transferred to the third lens  112 . The third lens  112  may collimate the reflected light RL so that the reflected light RL having passed through the noise canceling device  111  becomes parallel light, e.g., after the reflected light RL pass through the third lens  112 . 
     The reflected light RL passing through the third lens  112  may be transferred to the image sensor  113 . The image sensor  113  may receive and detect the reflected light RL coming from the third lens  112 . The image sensor  113  may include a charge-coupled device (CCD) camera and/or a complementary metal-oxide-semiconductor (CMOS) image sensor. The image sensor  113  may be installed on the pupil plane. 
     With the above configuration, the optical device  100  may be configured to measure the surface of the sample  150 . Next, an operating principle of the optical device  100  will be described. 
     Next, a principle of blocking a component reflected from the underlying layers that are two layers below from the surface of the sample to be measured/inspected among the reflected light RL will be described. 
       FIG. 2  is a schematic diagram illustrating a part of the optical device  100  of  FIG. 1 . Because the reflected light RL from the sample  150  will be described with reference to  FIG. 2 , the light source  101 , the pinhole plate  102 , the first lens  103 , the first polarization controller  105 , and the illumination pupil shape controller  104  are omitted in  FIG. 2 . For convenience of illustration, the objective lens  107  and the second lens  110  are illustrated as a single lens. In addition, because the configuration for cutting the light reflected from the portion of the second layer or less from the surface of the sample  150  to be measured is described with reference to  FIG. 2 , the second polarization controller  108  is omitted in  FIG. 2 . 
     For example, when the sample  150  has a stacked structure like a semiconductor device, in addition to the reflected light RL reflected from the measurement target layers  151  adjacent to the surface of the sample shown by the solid line, the reflected light RL′ reflected from the pattern of the underlying layers  153  below the measurement target layers  151  travels along the optical system from the objective lens  107  to the second lens  110 . 
     In the conventional inspection method, light reflected from the pattern of underlying layers below the measurement target layers reaches the image sensor. The intensity distribution obtained by the image sensor is influenced by the pattern of the underlying layers  153  below the measurement target layers  151 , and the influence of the pattern of the underlying layers  153  below the measurement target layers  151  is measurement noise. 
     As providing the noise canceling device  111  to the conjugate plane of the sample  150 , the optical device  100  according to example embodiments may pass the reflected light RL from the measurement target layer  151  focused on the pinhole  111 H of the noise canceling device  111  by a confocal effect, and remove the reflected light RL′ from the underlying layers  153  defocused to the pinhole  111 H of the noise canceling device  110 . For example, when the sample  150  is a semiconductor device, by detecting only a pattern in the measurement target layers  151  with the image sensor  113 , a higher-sensitivity measurement becomes possible. 
     Next, the noise canceling device  111  will be described in more detail.  FIG. 3  is a diagram illustrating an example of light diffracted by a pinhole of the pinhole plate  111 . 
     Referring to  FIGS. 1 to 3 , the reflected light RL indicated in  FIG. 3 , which is an in-focus light beam, is focused on the pinhole  111 H of the noise canceling device  111 , so the reflected light RL may pass through the noise canceling device  111 . 
     On the other hand, a portion of the reflected light RL′ of  FIG. 2 , which is a defocus ray removed near the inner perimeter defining the pinhole  111 H of the noise canceling device  111 , generates the diffracted light DL by the inner perimeter of the noise canceling device  111 . This diffracted light DL generates an intensity distribution by the diffracted light DL that has no relation to the intensity distribution in the pupil plane of the reflected light RL generated by the structure of the measurement target layers  151  of the sample  150 , and reaches on the image sensor  113  so that the diffracted light DL becomes measurement noise. 
       FIG. 4A  is a diagram for explaining a noise canceling device  111   a  according to other example embodiments. 
       FIG. 4A  is a diagram illustrating an example of noise cancellation by a noise canceling device  111   a  of an optical device according to example embodiments.  FIG. 4A  is also a cross-sectional view of the noise canceling device  111   a . The noise canceling device  111   a  may be alternatively employed with respect to the noise canceling device  111  of  FIG. 1 . For example, the noise canceling device  111   a  of  FIG. 4A  may a substitute of the noise canceling device  111  of  FIG. 1  in certain embodiments. 
     Referring to  FIG. 4A , the noise canceling device  111   a  may include a first noise canceling plate  111 P 1  and a second noise canceling plate  111 P 2 . According to example embodiments, the reflected light RL may pass through the first noise canceling plate  111 P 1  after passing through the second noise canceling plate  111 P 2 . Noise canceling plates described in this disclosure may also be referred to as noise filter plates. 
     Similarly to the noise canceling device  111  of  FIG. 3 , the first noise canceling plate  111 P 1  may be a pinhole plate including a pinhole  111 H 1  that is a circular light-transmitting part. The first noise canceling plate  111 P 1  may be arranged on the imaging surface of the reflected light RL. The pinhole  111 H 1  of the first noise canceling plate  111 P 1  may be on a focal point for the second lens  110  (see  FIG. 1 ) of the reflected light RL. 
     The second noise canceling plate  111 P 2  may include a circular first light-shielding part  111 C 1  on the central optical axis, a first ring-shaped light-transmitting part  111 H 2  surrounding the circular first light-shielding part  111 C 1 , and a second light-shielding part  111 C 2  surrounding the circular first light-shielding part  111 C 1  and the first ring-shaped light-transmitting part  111 H 2 . 
     The center of the circular first light-shielding part  111 C 1  of the second noise canceling plate  111 P 2  and the center of the pinhole  111 H 1  of the first noise canceling plate  111 P 1  may be arranged on the same straight line L 1  (e.g., the optical axis of the reflected light RL). 
     In  FIG. 4A , the reflected light RL focused on the pinhole  111 H 1  may pass through the second noise canceling plate  111 P 2  and the first noise canceling plate  111 P 1 . And, a portion of the reflected light RL′ defocused with respect to the first noise canceling plate  111 P 1  is diffracted by the second noise canceling plate  111 P 2 , so that the diffracted light DL may be generated, e.g., from the defocused reflected light RL′. For example, the defocused reflected light RL′ may be turned into the diffracted light DL while passing through the second noise canceling plate  111 P 2 . Thereafter, the diffracted light DL may be blocked by the first noise canceling plate  111 P 1 . As a result, a majority of the diffracted light DL may be blocked by the noise canceling device  111   a.    
       FIG. 4B  is a diagram for explaining a noise canceling device  111   a ′ according to other example embodiments. 
     Referring to  FIG. 4B , the noise canceling device  111   a ′ may include a first noise canceling plate  111 P 1 , a second noise canceling plate  111 P 2 , and a third noise canceling plate  111 P 3  arranged along the direction of the reflected light RL and RL′. For example, the first noise canceling plate  111 P 1 , the second noise canceling plate  111 P 2 , and the third noise canceling plate  111 P 3  may be arranged along the optical axis of the reflected light RL and/or the optical axis of the reflected light RL′. 
     Since the first noise canceling plates  111 P 1  and the second noise canceling plate  111 P 2  are the same or substantially the same as those described with reference to  FIG. 4A , redundant descriptions thereof will be omitted. 
     Terms such as “same,” “equal,” “planar,” or “coplanar,” as used herein encompass identicality or near identicality including variations that may occur, for example, due to manufacturing processes. The term “substantially” may be used herein to emphasize this meaning, unless the context or other statements indicate otherwise. 
     The third noise canceling plate  111 P 3  may include a circular third light-shielding part  111 C 3  on the central optical axis, a second ring-shaped light-transmitting part  111 H 3  surrounding the circular third light-shielding part  111 C 3 , and a fourth light-shielding part  111 C 4  surrounding the circular third light-shielding part  111 C 3  and the second ring-shaped light-transmitting part  111 H 3 . 
     According to example embodiments, the reflected light RL transmitted through the pinhole  111 H 1  may pass through the second ring-shaped light-transmitting part  111 H 3 . In addition, the third and fourth light-shielding parts  111 C 3  and  111 C 4  may block the diffracted light DL having passed through the first noise canceling plates  111 P 1 . 
       FIG. 5A  is a diagram for explaining a noise canceling device  111   b  according to other example embodiments. 
       FIG. 5B  is a plan view of the noise canceling device  111   b  viewed from the side of a first noise canceling plate  111 P 1 ′ of the noise canceling device  111   b  according to example embodiments. 
       FIG. 5C  is a plan view of the noise canceling device  111   b  as viewed from the side of a second noise canceling plate  111 P 2 ′ of the noise canceling device  111   b  according to example embodiments. 
     Referring to  FIGS. 5A to 5C , the noise canceling device  111   b  may include a first noise canceling plate  111 P 1 ′, a second noise canceling plate  111 P 2 ′, and a light-transmitting plate  111 G arranged between the first noise canceling plate  111 P 1 ′ and the second noise canceling plate  111 P 2 ′. 
     In example embodiments, the light-transmitting plate  111 G may include or be formed of a light-transmitting material such as glass or quartz. 
     The first noise canceling plate  111 P 1 ′ and the second noise canceling plate  111 P 2 ′ may be layers of a light absorbing material such as chrome coated on the light-transmitting plate  111 G. 
     The first noise canceling plate  111 P 1 ′ may include a circular first light-shielding part  111 C 1 ′ on the central optical axis, a ring-shaped transmission part  111 H 1 ′ surrounding the circular first light-shielding part  111 C 1 ′, and a second light-shielding part  111 C 2 ′ surrounding the circular first light-shielding part  111 C 1 ′ and the ring-shaped light-transmitting part  111 H 1 ′. 
     The second noise canceling plate  111 P 2 ′ may include a pinhole  111 H 2 ′ that is a circular transmission part. 
     Based on what is described herein, a person skilled in the art will be able to implement an embodiment easily, in which the noise canceling device  111   a  of  FIG. 4 a   , the noise canceling device  111   a ′ of  FIG. 4 b   , and the noise canceling device  111   b  of  FIG. 5 a    are alternatively employed instead of the noise canceling device  111  of the optical device  100  of  FIG. 1 . 
       FIG. 6  is a diagram showing an example of the illumination pupil shape controller  104  of the optical device according to an embodiment. 
     Referring to  FIG. 6 , the illumination pupil shape controller  104  may include a first light-shielding part  104 C 1  placed on the center, a ring-shaped light-transmitting part  104 T surrounding the first light-shielding part  104 C 1 , and a second light-shielding part  104 C 2  surrounding the first light-shielding part  104 C 1  and the ring-shaped light-transmitting part  104 T. Accordingly, the input light IL (see  FIG. 1 ) passing through the illumination pupil shape controller  104  may be formed/modified to have a ring-shaped beam cross-section. Also, the illumination pupil shape controller  104  may include a spatial modulator such as a Digital Micromirror Device (DMD). 
     According to example embodiments, the distribution of the remaining diffracted light is calculated using the illumination pupil shape controller  104 . 
       FIG. 7  is a diagram illustrating an example of intensity distribution processing of the optical device  100  using the illumination pupil shape controller  104  according to example embodiments. In the graphs  801 ,  802 ,  803 , and  804 , the horizontal axis indicates the distance from the optical axis, and the vertical axis indicates the intensity of light. 
     Referring to  FIGS. 1, 6, and 7 , the central portion CP and the edge portion EP of the luminous flux of the incident light IL passing through the illumination pupil shape controller  104  may be removed. Therefore, as shown in the graph  801 , the light intensity of the central portion CP of the luminous flux corresponding to the first light-shielding part  104 C 1  and the light intensity of the edge portion EP of the luminous flux corresponding to the second light-shielding part  104 C 2  are about 0. In this example, the intensity of a ring-shaped part RP arranged between the center part CP and the edge part EP and corresponding to the ring-shaped light-transmitting part  104 T is substantially constant with respect to the distance from the optical axis. The image  811  represents the intensity of the luminous flux of the incident light IL in a plane perpendicular to the optical axis, which is corresponding to the graph  801 . 
     The intensity distribution of the reflected light RL from the sample  150  reaching the image sensor  113  is the same as the graph  802 . Referring to the graph  802 , the intensity distribution of the diffracted light DL (see  FIG. 3 ) generated by the noise canceling device  111  appears in the center part CP and the edge part EP corresponding to the first and second light-shielding parts  104 C 1  and  104 C 2  of the illumination pupil shape controller  104 . Image  812  represents the intensity of the luminous flux of reflected light RL in a plane perpendicular to the optical axis, which is corresponding to graph  802 . 
     Subsequently, the optical device  100  may extract the intensity of the center part CP and the edge part EP blocked by the illumination pupil shape controller  104  from the distribution of the graph  802 . Accordingly, the solid line portion of the graph  803  may be obtained. The image  813  represents the intensity of the luminous flux of the diffracted light DF (see  FIG. 3 ) in a plane perpendicular to the optical axis, which is according to the solid line portion of the graph  803 . 
     Then, through the interpolation operation based on the extracted intensity distribution, e.g., the intensity distribution of the center part CP and the edge part EP shown as a solid line in the graph  803 , the intensity distribution of the diffracted light DF (see  FIG. 3 ) of the non-extracted part, e.g., the ring-shaped part RP, may be calculated. The intensity distribution of the ring-shaped part RP is shown as a dashed line in the graph  803 . The intensity distribution of the entire graph  803  obtained by extraction and interpolation may be interpreted as an intensity distribution by the diffracted light DF (see  FIG. 3 ) generated by the noise canceling device  111 . The image  821  represents the intensity of the luminous flux of the diffracted light DF (see  FIG. 3 ) in a plane perpendicular to the optical axis along with the solid line portion of the graph  803 . The image  821  may be a noise image representing noise expressed by the diffracted light DF (see  FIG. 3 ). 
     Then, the optical device  100  may subtract the intensity distribution of the pupil by the diffracted light DL (e.g., any one of the graph  803  and the image  821 ) from the intensity distribution of the pupil measured by the image sensor  113  (e.g., any one of the graph  802  and the image  812 ). For example, the optical device  100  may subtract the intensity of the diffracted light DF from the measured intensity by the image sensor  113 . Accordingly, the optical device  100  may obtain a signal of the reflected light RL derived from only the measurement target layers  151  of the measurement sample  150 . 
     Therefore, image  814  is obtained by subtracting the image  821  from the image  812 . Such processing may be performed by a processor  114  included in the optical device  100  or an external processor for analyzing data generated by the optical device  100 . 
     The above-described measurement method by the optical device  100  may simultaneously measure all incident angles and all azimuth angles whose positions in the pupil plane correspond to incident angles and azimuth angles of illumination with respect to the sample using the intensity distribution according to the position on the pupil plane. Accordingly, processing such as reflectometry, ellipsometry, polarimetry, and scatterometry is performed on the measurement result of the optical device  100 , and the measurement value of the measurement sample structure is calculated. 
     The measurement method described above with reference to  FIGS. 6 and 7  may also be similarly applied to embodiments in which the noise canceling device  111   a  of  FIG. 4  and/or the noise canceling device  111   b  of  FIG. 5A  are alternatively employed in the position of the noise canceling device  111  of the optical device  100 . 
       FIG. 8  is a diagram illustrating an example of noise cancellation by a noise canceling device  111   c  of an optical device  100  according to example embodiments. 
     Referring to  FIGS. 1 and 8 , the noise canceling device  111   c  may be a light-transmitting substrate including a pinhole  111 Hc that is a circular hole. The center of the pinhole  111 Hc may be on the optical axis of the optical device  100 . 
     According to example embodiments, the noise canceling device  111   c  may include or be formed of a light-transmitting material. As a non-limiting example, the noise canceling device  111   c  may include or be formed of quartz and glass. 
     The noise canceling device  111   c  is designed so that the phase difference between the light passing through the pinhole  111 Hc and the light passing through the light-transmitting material/substrate of the noise canceling device  111   c  near the pinhole  111 Hc becomes half the wavelength of the input light IL. The noise canceling device  111   c  may have a thickness such that the phase difference between the light passing through the pinhole  111 Hc and the light passing through the light-transmitting material/substrate of the noise canceling device  111   c  near the pinhole  111 Hc becomes half the wavelength of the input light IL. For example, the phase difference between the light passing through the light-transmitting material/substrate of the noise canceling device  111   c  and the light passing through the pinhole  111 Hc may be a half wavelength. 
     Due to the phase shift of the half wavelength, the component of the straight direction (e.g., in a direction parallel to the optical axis of the optical device  100 ) of the diffracted light incident on the inner perimeter IR of the pinhole  111 Hc of the noise canceling device  111   c  may be canceled. Accordingly, the diffracted light DL incident on the inner perimeter IR of the pinhole  111 Hc of the noise canceling device  111   c  is irradiated to a position outside the pupil of the image sensor  113  through diffraction. 
     In the above embodiment, because the light diffracted by the noise canceling device  111   c  is directed out of pupil position of the image sensor  113 , measurement noise may be reduced. 
     However, this inventive concept is not limited to the embodiment, and appropriate changes may be made without departing from the purpose. For example, a person of ordinary skill in the art will be able to easily reach an optical device including a noise canceling device with two first noise canceling plates  111 P 1  of  FIG. 4A  and one second noise canceling plate  111 P 2  of  FIG. 4A  arranged therebetween. 
     The processor  114  for processing the signal of the image sensor  113  may include a central processing unit (CPU), a memory, and other circuits in its hardware, and may be implemented with a program loaded into the memory as a software. Accordingly, it will be understood by those skilled in the art that these functional blocks may be implemented in various forms with hardware only, software only, or a combination thereof, and are not limited thereto. 
     The above-described program may be stored using various types of non-transitory computer-readable media and supplied to the computer. Non-transitory computer-readable media may include or may be one of various types of tangible recording media. Examples of non-transitory computer-readable media include magnetic recording media (e.g., flexible disks, magnetic tapes, and hard disk drives), magneto-optical recording medium (e.g., an optical magnetic disk), compact disc read-only memory (CD-ROM), CD-recordable (CD-R), CD-rewritable (CD-R/W), semiconductor memory (e.g., mask read-only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), flash ROM, and random access memory (RAM)). Further, the program may be supplied to the computer by various types of transitory computer-readable media. Examples of transitory computer-readable media include electrical signals, optical signals, and electromagnetic waves. The temporary computer-readable medium may supply a program to the computer through a wired communication path such as an electric wire and optical fiber, or a wireless communication path. 
       FIG. 9  is a diagram for describing an optical device  200  according to example embodiments. 
     Referring to  FIG. 9 , the optical device  200  may include an inclination optical system, unlike the optical device  100  configured with the vertical optical system of  FIG. 1 . For example, in the optical device  100 , the input light IL may be incident on the substrate sample (e.g., on a top surface of the substrate sample) perpendicularly, and in the optical device  200 , the input light IL may be incident on the substrate sample (e.g., on a top surface of the substrate sample) in an inclined/oblique direction. 
     The optical device  200  may include a light source  101 , a pinhole plate  102 , a first lens  103 , an illumination pupil shape controller  104 , a first polarization controller  105 , a first objective lens  107   a , a second objective lens  107   b , a second polarization controller  108 , a second lens  110 , a noise canceling device  111 , a third lens  112 , an image sensor  113 , and a processor  114 . 
     Except for constituting the inclination/oblique optical system, the light source  101 , the pinhole plate  102 , the first lens  103 , the illumination pupil shape controller  104 , the first polarization controller  105 , the second polarization controller  108 , the second lens  110 , the noise canceling device  111 , the third lens  112 , the image sensor  113 , and the processor  114  are the same or substantially the same as those described with reference to  FIG. 1 , and therefore, a redundant description thereof will be omitted. 
     The first objective lens  107   a  may focus the input light IL passing through the first polarization controller  105  on the sample  150 . The second objective lens  107   b  may collimate the reflected light RL so that the reflected light RL becomes a parallel light. The reflected light RL passing through the second objective lens  107   b  may reach the second polarization controller  108 . 
       FIG. 10  is a flowchart illustrating a method of inspecting a semiconductor device according to example embodiments. 
     Referring to  FIGS. 1, 2, and 10 , a semiconductor device inspection method according to example embodiments may include acquiring an image of the sample  150  by detecting the reflected light RL generated as the input light IL is reflected by the sample  150  in P 10  and removing noise by the diffracted light from the image in P 20 . 
     In P 10 , the acquiring of the image of the sample  150  is more particularly as follows. 
     The light source  101  and the pinhole plate  102  may constitute a point light source, and the input light IL emitted from the point light source may be collimated to become parallel light by the first lens  103 . The collimated input light IL may be formed to have a ring-shaped beam cross-section by the illumination pupil shape controller  104 , and after passing through the first polarization controller  105 , the collimated input light IL may be reflected by the beam splitter  106  and directed to the objective lens  107 . The input light IL may be focused by the objective lens  107  onto the sample  150  such as a wafer on which a semiconductor device is formed. 
     After the reflected light RL is generated when the input light RL is reflected by the sample  150 , and collimated by the objective lens  107 , the reflected light RL may pass through the beam splitter  106  and the second polarization controller  108 . Subsequently, the reflected light RL may form an intermediate image by the second lens  110 . The noise canceling device  111  may be installed at the intermediate image position (i.e., the focus of the second lens  110  with respect to the reflected light RL) of the reflected light RL. As described with reference to  FIGS. 1 to 6 , the noise canceling device  111  may remove the reflected light RL′ generated from the underlying layers  153  below the measurement target layers  151  of the sample  150 . The reflected light RL passing through the noise canceling device  111  may be collimated to become a parallel light by the third lens  112 , and the image sensor  113  installed on the pupil plane of the reflected light RL may detect the reflected light RL. 
     In P 20 , as described with reference to  FIG. 8 , the removing of the noise by the diffracted light from the image may include extracting a radius-intensity distribution of the center part of the image of the sample  150  and a radius-intensity distribution of the part corresponding to the edge part of the input light, calculating a noise image by the diffracted light by performing an interpolation operation based on the radius-intensity distribution of the center part and the radius-intensity distribution of the edge part, and performing a subtraction operation between the image and the noise image (e.g., a subtraction of the noise image from the measured image). For example, the radius-intensity distribution of the center part of the image may be an intensity distribution of light within a certain distance from the center of the image of the sample  150 , and the radius-intensity distribution of the part corresponding to the edge part may be an intensity distribution of light in a range longer than a certain distance from the center of the input light. 
     In an example embodiment of the present disclosure, a method of manufacturing a semiconductor device is provided. The method of manufacturing the semiconductor device may include providing a substrate, forming one or a plurality of pattern layers on the substrate, and performing an inspection of the patterns of the one or the plurality pattern layers. In performing the inspection, the above described semiconductor device inspection method may be adopted. 
     While the inventive concept has been particularly shown and described with reference to embodiments thereof, it will be understood that various changes in form and details may be made therein without departing from the spirit and scope of the following claims.