Measurement System and Method of Diffraction of Light

Abstract

SUMMARY OF THE INVENTION [0003] Embodiments of the present disclosure relate to a measurement system and method for diffracting light. The measurement system includes a stage, an optical arm, and one or more detector arms. A method for diffracting light is provided, the method comprising: diffracting light at a wavelength λ laser A light beam having a fixed beam angle θ and a maximum orientation angle φ max projecting the beam onto a first zone of a first substrate at a target maximum beam angle θ; obtaining a displacement angle Δθ; t-max determining θ t-max = θ0 + Δθ, the target maximum beam angle θ t-max and determining the corrected grating pitch formula P t-grating =λ laser / (sinθ t-max +sinθ0) by the test grating pitch P t-grating The measurement system and method allows for measurement of non-uniform properties of a region of an optical device, such as grating pitch and grating orientation.

Description

Technical Field

[0001]

[0001] Embodiments of the present disclosure relate to apparatuses and methods, and more particularly, to a measurement system and method for diffracting light.

Background Art

[0002]

[0002] Virtual reality generally refers to a simulated environment generated by a computer that makes a user feel as if they are actually present. A virtual reality experience is generated in 3D and can be viewed through a head-mounted display (HMD) such as glasses, or other wearable display devices with a near-eye display panel as a lens, to display a virtual reality environment in place of the actual environment.

[0003]

[0003] However, in augmented reality, it is possible to experience seeing an image of a virtual object generated for display as part of the environment while the user views the surrounding environment through the display lens of glasses or other HMD devices. Augmented reality can include all kinds of inputs such as audio and tactile inputs, as well as virtual images, graphics, videos, etc. that enhance or expand the environment experienced by the user. To realize an augmented reality experience, it is necessary to superimpose a virtual image on the surrounding environment, and the superimposition is performed by an optical device.

[0004]

[0004] One of the drawbacks in this technical field is that manufactured optical devices tend to have non-uniform characteristics such as grating pitch and grating orientation (grating direction). Also, deposited optical devices may inherit the non-uniformity of those substrates, such as local warping or deformation of the substrate. Further, when deposition is performed on a substrate disposed on a support surface with irregularities such as defects or particles on the support surface, the substrate may tilt, and the deposited optical device may also inherit the distortion.

[0005]

[0005] Therefore, what is needed in the art is an apparatus and method for detecting non-uniformity of an optical device.

SUMMARY OF THE INVENTION

[0006]

[0006] In one embodiment, a measurement system is provided that includes a stage, an optical arm coupled to an arm actuator configured to scan the optical arm and rotate the optical arm about an axis, and a detector arm. The stage has a substrate support surface. The stage is coupled to a stage actuator configured to move the stage along a scanning path and rotate the stage about an axis. The optical arm includes a laser positioned adjacent to a beam splitter positioned in an optical path adjacent to a photodetector, the laser being operable to project an optical beam deflected at a beam angle θ along an optical path to the stage onto the beam splitter. The detector arm includes a detector actuator configured to scan the detector arm and rotate the detector arm about an axis, a first focusing lens, and a detector.

[0007]

[0007] In another embodiment, a measurement system is provided that includes a stage, an optical arm coupled to an arm actuator configured to scan the optical arm and rotate the optical arm about an axis, a first detector arm, and a second detector arm. The stage has a substrate support surface. The stage is coupled to a stage actuator configured to move the stage along a scanning path and rotate the stage about an axis. The optical arm includes a laser positioned adjacent to a beam splitter positioned in an optical path adjacent to a photodetector, the laser being operable to project an optical beam deflected at a beam angle θ along an optical path to the stage onto the beam splitter. Each detector arm includes a detector actuator configured to scan the detector arm, a first focusing lens, and a detector.

[0008]

[0008] In yet another embodiment, an optical beam having a wavelength λ laser is projected at a fixed beam angle θ0 and a maximum orientation angle (maximum direction angle) φmax projecting onto a first zone of a first substrate, obtaining a displacement angle Δθ, and determining a target maximum beam angle θ t-max where θ t-max = θ0 + Δθ, determining the target maximum beam angle θ t-max and determining a modified grating pitch formula P t-grating = λ laser / (sin θ t-max + sin θ0), thereby determining a test grating pitch P t-grating is provided, including a method of diffracting light.

[0009]

[0009] In the measurement system and the measurement method, local non-uniformities in the region of the optical device, such as grating pitch and grating orientation, are measured. The values of the local non-uniformities are useful for evaluating the performance of the optical device.

[0010]

[0010] To understand the features of the present disclosure described above in detail, the present disclosure summarized above will be described more specifically with reference to some embodiments illustrated in the accompanying drawings. However, it should be noted that the accompanying drawings merely show typical embodiments and should not be regarded as limiting the scope of the embodiments, and other equally effective embodiments are also acceptable.

Brief Description of the Drawings

[0011]

Figure 1A

Figure 1B

Figure 1C

Figure 2

Figure 3

Figure 4A

Figure 4B

Figure 4C

Figure 4D

Figure 5

[0012]

[0016] For ease of understanding, the same reference numbers are used as much as possible to indicate the same elements common to the drawings. The elements and features of one embodiment are considered to be beneficially incorporated into other embodiments without further elaboration.

DETAILED DESCRIPTION OF THE INVENTION

[0013]

[0017] Embodiments of the present disclosure relate to a measurement system and method for measuring local non-uniformities of an optical device. The measurement system includes a stage, an optical arm, and one or more detector arms including one or more focusing lenses. Light projected from the optical arm is reflected by a substrate disposed on the stage, and the reflected light from the substrate surface is incident on the detector. Using the deflection from the optical center of the focusing lens, the local non-uniformity of the optical device is determined. The method of diffracting light includes measuring a scattered light beam from the substrate surface, and local strain is obtained from the measurement value. Embodiments disclosed herein may be particularly useful for measuring the local uniformity of an optical system, but are not limited thereto.

[0014]

[0018] As used herein, the term "about" means a variation of + / - 10% from the nominal value. It should be understood that the above variations may be included in any value presented herein.

[0015]

[0019] FIG. 1A is a schematic diagram showing a first configuration 100A of a measurement system 101 according to an embodiment. As shown, the measurement system 101 includes a stage 102, an optical arm 104A, and one or more detector arms 150. The measurement system 101 is configured to diffract light generated by the optical arm 104. The light generated by the optical arm 104 is directed toward a substrate disposed on the stage 102, and the diffracted light is incident on one or more detector arms 150.

[0016]

[0020] As shown, the stage 102 includes a support surface 106 and a stage actuator 108. The stage 102 is configured to hold a substrate 103 on the support surface 106. The stage 102 is coupled to the stage actuator 108. The stage actuator 108 is configured to move the stage 102 along the X and Y directions in a scanning path 110 and rotate the stage 102 about the Z axis. The stage 102 is configured to move and rotate the substrate 103 during operation of the measurement system 101 such that light from the optical arm 104A is incident on different portions or regions of the substrate 103.

[0017]

[0021] The substrate 103 includes one or more optical devices 105 having one or more regions 107 of the grating 109. Each region 107 has a grating 109 having an orientation angle φ and a pitch P (FIG. 3), and P is defined as the distance between adjacent points, such as adjacent first edges 301 or the mass centers of adjacent gratings 109. The pitch P and the orientation angle φ of the grating 109 in the first region 111 may be different from the pitch P and the orientation angle φ of the grating 109 in the second region 113 of the one or more regions 107. Also, due to local warping or other deformations of the substrate 103, local variations in the pitch P' and local variations in the orientation angle φ' may occur. The measurement system 101 can be used to measure the pitch P and the orientation angle φ of the grating 109 for each of the regions 107 of each optical device 105. The substrate 103 can be a single crystal wafer of any size, such as having a radius of from about 150 mm to about 450 mm. As shown, the light beam 126A from the optical arm 104A is scattered from the region 107 to become the initial R0 beam 450, which will be described in detail below.

[0018]

[0022] The optical arm 104, detector arm 150, and stage 102 are coupled to a controller 130. The controller 130 facilitates the control and automation of the method for measuring the pitch P and orientation angle φ of the grating 109 described herein. The controller may include a central processing unit (CPU) (not shown), a memory (not shown), and support circuitry (or I / O) (not shown). The CPU can be one of any form of computer processor used to control various processes and hardware (such as motors and other hardware) in the industry and to monitor processes (such as the position of the transfer device and the scanning time, etc.). The memory (not shown) is connected to the CPU and can be an easily accessible memory such as random access memory (RAM). It can encode software instructions and data and store them in the memory and instruct the CPU. Also, support circuitry (not shown) for assisting the processor in a conventional manner is connected to the CPU. The support circuitry can include conventional cache, power supply, clock circuit, input / output circuit, subsystem, etc. A program (or computer instruction) readable by the controller determines tasks executable on the substrate 103. The program can be software readable by the controller and can include, for example, code for monitoring and controlling the position of the substrate and the position of the optical arm, etc.

[0019]

[0023] As shown, the optical arm 104A includes a white light source 114A, a first beam splitter 116A, a second beam splitter 118A, a laser 120, a detector 122, and a spectrometer 124. The white light source 114 can be a fiber-coupled light source. The first beam splitter 116A is positioned in the optical path 126A adjacent to the white light source 114. The white light source 114 is operable, according to one embodiment, to project white light at a beam angle θ along the optical path 126A to the substrate 103. The laser 120 can be a fiber-coupled light source. The laser 120 is positioned adjacent to the first beam splitter 116A. The laser 120 is operable to project an optical beam having a wavelength onto the first beam splitter 116A such that the optical beam is deflected at a beam angle θ along the optical path 126A to the substrate 103. The second beam splitter 118A is disposed in the optical path 126A adjacent to the first beam splitter 116A. The second beam splitter 118A is operable to deflect the optical beam reflected by the substrate 103 to the detector 122. The spectrometer 124 is coupled to the detector 122 and determines the wavelength of the optical beam deflected to the detector 122. The optical beam described herein can be a laser beam. The optical arm 104 sends an optical beam along the optical path 126 such that the light is deflected by the substrate 103 and measured by one or more detector arms 150.

[0020]

[0024] Figure 1B is a schematic diagram showing a second configuration 100B of the measurement system 101 according to an embodiment. As shown, the optical arm 104B includes a laser 120, a beam splitter 128, and a beam position detector 132. The beam position detector 132 may include an image sensor such as a CCD or CMOS sensor. The beam splitter 128 is positioned in the optical path 126B adjacent to the beam position detector 132. The laser 120 is positioned adjacent to the beam splitter 128. The laser 120 is operable to project an optical beam having a wavelength onto the beam splitter 128 such that the optical beam is deflected at a beam angle θ along the optical path 126B to the substrate 103. The optical arm 104B includes, according to an embodiment, a polarizer 156 such as a half-wave plate and a quarter-wave plate 158. The polarizer 156 is between the laser 120 and the beam splitter 128. The polarizer 156 maximizes the efficiency of the optical beam deflected by the beam splitter 128 at the beam angle θ. The quarter-wave plate 158 is in the optical path 126B and is positioned adjacent to the beam splitter 128. The quarter-wave plate 158 maximizes the efficiency of the optical beam reflected by the substrate 103 reaching the beam position detector 132 and reduces the optical beam reflected to the laser 120.

[0021]

[0025] FIG. 1C is a schematic diagram showing a third configuration 100C of the measurement system 101 according to an embodiment. The optical arm 104C includes lasers 134a, 134b, ··· 134n (collectively referred to as "a plurality of lasers 134") and beam splitters 136a, 136b, ··· 136n (collectively referred to as "a plurality of beam splitters 136"). The plurality of beam splitters 136 are positioned adjacent to each other in the optical path 126C, adjacent to the beam position detector 132. The laser 134a is configured to project an optical beam having a first wavelength onto the beam splitter 136a such that the optical beam of the first wavelength is deflected at a beam angle θ along the optical path 126c to the substrate 103. The laser 134b is configured to project an optical beam having a second wavelength onto the beam splitter 136b such that the optical beam of the second wavelength is deflected at a beam angle θ along the optical path 126c to the substrate 103. The laser 134n is configured to project an optical beam having a third wavelength onto the beam splitter 136n such that the optical beam of the third wavelength is deflected at a beam angle θ along the optical path 126C to the substrate 103.

[0022]

[0026] The optical arm 104C may include polarizers 156a, 156b,... 156n (collectively referred to as "a plurality of polarizers 156C") and a quarter-wave plate 158. The plurality of polarizers 156C are between the plurality of lasers 134 and the plurality of beam splitters 136. The plurality of polarizers 156C maximize the efficiency of the optical beam deflected by the plurality of beam splitters 136 at the beam angle θ. The quarter-wave plate 158 is in the optical path 126C and is positioned adjacent to the beam splitter 136n. The quarter-wave plate 158 maximizes the efficiency with which the optical beam reflected by the substrate 103 reaches the beam position detector 132. The quarter-wave plate 158 is replaceable according to a desired wavelength.

[0023]

[0027] In any of the above-described configurations 100A, 100B, and 100C, the optical arms 104A, 104B, and 104C may include an arm actuator 112, and the arm actuator is configured to rotate the optical arm 104 about the z-axis and scan the optical arm in the z-direction. During measurement, the optical arm 104 may be fixed.

[0024]

[0028] The beam position detectors 132 of the second configuration 100B and the third configuration 100C are operable to determine the beam position of the light beam reflected by the substrate 103 to the beam position detector 132. FIG. 2A is a diagram showing a position-sensitive detector 201A according to an embodiment, that is, the beam position detector 132 as a lateral sensor. FIG. 2B is a diagram showing the beam position detector 132 as a quadrant sensor 201B according to an embodiment. FIG. 2C is a diagram showing the beam position detector 132 as an image sensor array 201C such as a charge-coupled device (CCD) array or a complementary metal-oxide semiconductor (CMOS) array according to some embodiments.

[0025]

[0029] FIG. 4A is a schematic diagram showing a detector arm 150 according to an embodiment. As shown, the detector arm 150 includes a detector 410, a detector arm actuator 152, and a first focusing lens 401. The detector arm actuator 152 is configured to rotate the detector arm 150 about the z-axis and scan the detector arm 150 in the z-direction. In FIGS. 4A to 4D, the light from the optical path 126 is reflected by the region 107 of the substrate 103. This light is reflected by the initial R0 beam 450 and focused by the first focusing lens 401 into the first R0 beam 411. The first R0 beam 411 is incident on the detector 410. The detector 410 is any optical device used in the art for detecting light, such as a CCD array or a CMOS array.

[0026]

[0030] Before measuring the area 107, the measurement system 101 can be calibrated with a known substrate 103, and the detector arm 150 can be positioned such that the first R0 beam 411 is incident on the optical center 401c of the first focusing lens 401. Any of the measurement systems 101 described above and below can be calibrated with a known substrate 103 as described herein. Due to the local distortion of the area 107, the initial R0 beam 450 in the reference area 107 no longer enters the optical center 401c of the focusing lens 401. For example, there may be local warping of the substrate 103 in the area 107, or overall wafer tilt, wedge, warp, bow, etc. The presence of particles on the support surface may cause the substrate 103 to tilt on the support surface 106, and the particles disposed between the substrate 103 and the support surface may cause local and / or overall distortion such as an increase in the height of the area 107 and the tilt of the area with respect to the support surface (shown as the tilted substrate 103t in FIGS. 4A to 4D). In these cases with the tilted substrate 103t, according to one embodiment, the initial R0 beam 450t is incident on the first focusing lens 401 at the first angle Δθ1, and the first R0 beam 411t is focused on a portion of the detector 410 that is separated from the focused first R0 beam 411 of the known substrate 103 by about the first delta distance Δ1. The first delta distance Δ1 is obtained by Δ1 = f1 * tan(Δθ1), where f1 is the focal length of the focusing lens 401. Thus, using the first delta distance Δ1 and the first angle Δθ1, local distortion information can be obtained as will be described in more detail below. According to one embodiment, the resolution of the detector 410 is less than about Δ1.

[0027]

[0031] Figure 4B is a schematic diagram showing a detector arm 150 according to an embodiment. As shown, the detector arm 150 further includes a second focusing lens 402 and a third focusing lens 403. An initial R0 beam 450t is incident on the first focusing lens 401 at an angle of Δθ1, and the first focusing lens focuses the initial R0 beam into a first R0 beam 411t. The first R0 beam 411t is incident on the second focusing lens 402, and the first focusing lens focuses the first R0 beam into a second R0 beam 412t. According to one embodiment, the second R0 beam 412 is incident on a second incident spot on the third focusing lens 403, and the third focusing lens focuses the second R0 beam into a third R0 beam 413t that is about a second delta distance Δ2 away from a portion of the detector 410 that is focused from the third R0 beam of a known substrate, where Δ2 = Δ1 * which is f3 / f2, where f2 is the focal length of the second focusing lens and f3 is the focal length of the third focusing lens. Further, Δ2 = f3 * f1 * which is tan(Δθ1) / f2. Thus, using the second delta distance Δ2, local strain information can be obtained through the first angle Δθ1, as will be described in more detail below. In some embodiments, the second delta distance Δ2 is greater than the first delta distance Δ1, such that it is possible to use a detector 410 with a lower resolution since the detector is limited only by the magnitude of the second delta distance Δ2. According to one embodiment, the resolution of the detector 410 is less than about Δ2.

[0028]

[0032] As described above, three focusing lenses 401, 402, 403 are included in the detector arm 150, but any number of focusing lenses can be used, and the lenses can be configured in the same manner as described above such that a larger delta distance is produced that is measured by the detector 410.

[0029]

[0033] FIG. 4C is a schematic diagram showing a measurement system 101 including a first detector arm 150 and a second detector arm 150' according to an embodiment. The first detector arm 150 is substantially similar to the detector arm described above with reference to FIG. 4A. As shown, the second detector arm 150' includes a first focusing lens 401', a detector 410', and a detector actuator 152'. In this embodiment, the light traveling along the optical path 126 is backscattered to generate a reflected R1 beam 450t'. The second detector arm 150t' is located behind the optical arm 104 according to one embodiment, and the optical arm is at least partially transparent to the reflected R1 beam 450t'.

[0030]

[0034] According to one embodiment, the reflected R1 beam 450t' is incident on a third focusing spot on the first focusing lens 401' at a third delta distance Δ3 from the optical center 401c' of the first focusing lens, and the first focusing lens focuses the reflected R1 beam into a first R1 beam 411t'. The third delta distance Δ3 is obtained by Δ3 = f1' * tan(Δθ2), where f1' is the focal length of the focusing lens 401'. Thus, using the third delta distance Δ3 and the second angle Δθ2, local strain information can be obtained, as will be described in more detail below. According to one embodiment, the resolution of the detector 410' is less than about Δ3. The displacement angle Δθ is obtained by Δθ = Δθ2 - Δθ1, and the displacement angle Δθ provides local strain of the pitch of the grating P t-grating as described in more detail below.

[0031]

[0035] Figure 4D is a schematic diagram showing a measurement system 101 including a first detector arm 150 and a second detector arm 150' according to an embodiment. The first detector arm 150 is substantially similar to the detector arm described above with reference to FIG. 4B. As shown, the second detector arm 150' includes a first focusing lens 401', a second focusing lens 402', a third focusing lens 403', a detector 410', and a detector actuator 152'. In this embodiment, light traveling along the optical path 126 is backscattered to generate a reflected R1 beam 450t'. The second detector arm 150' is located behind the optical arm 104 according to an embodiment, and the optical arm is at least partially transparent to the reflected R1 beam 450'.

[0032]

[0036] According to an embodiment, the reflected R1 beam 450t' is incident on a third focusing spot of the first focusing lens 401' at a third delta distance Δ3 from the optical center 401c' of the first focusing lens, and the first focusing lens focuses the reflected R1 beam into a first R1 beam 411t'. The first R1 beam 411t' is incident on the second focusing lens 402', and the first focusing lens focuses the first R1 beam into a second R1 beam 412t'. The second R1 beam 412t' is incident on a fourth focusing spot at a fourth delta distance Δ4 from the optical center 403c' of the third focusing lens 403', and the third focusing lens focuses the second R1 beam into a third R1 beam 413t' onto a portion of the detector 410' that is about the fourth delta distance Δ4 away from the focused third R1 beam of the known substrate. Thus, using the fourth delta distance Δ4, similar to the second delta distance Δ2, local strain information can be obtained.

[0033]

[0037] In some embodiments, the fourth delta distance Δ4 is greater than the third delta distance Δ3, such that the detector is only limited by the magnitude of the fourth delta distance Δ4, thereby enabling the use of a detector 410' with a lower resolution. The two delta distances Δ2, Δ4 enable more detailed measurement of local distortion in region 107. According to one embodiment, the third delta distance Δ3 is greater than the first delta distance Δ3. According to one embodiment, the resolution of detector 410' is less than about Δ4. According to one embodiment, the focal length of the first focusing lens 401 of the first detector arm 150 is different from the focal length of the second focusing lens 402 of the first detector arm, and the focal length of the second focusing lens of the first detector arm is different from the focal length of the third focusing lens 403 of the first detector arm.

[0034]

[0038] Figures 4C - 4D show a measurement system 101 having two detector arms 150, 150' with the same number of focusing lenses, but it should be understood that any odd number of lenses can be used for each detector arm. For example, the first detector arm 150 can have one focusing lens, the second detector arm 150' can have three focusing lenses, or vice versa. In other examples, the first detector arm 150 has five focusing lenses and the second detector arm 150' has three focusing lenses.

[0035]

[0039] In all of the above and following embodiments, Δ1, Δ2, Δ3, and Δ4 range from about 10um to about 1mm, and Δθ1, Δθ2, Δθ3, and Δθ4 range from about 0.001° to about 1°, for example, from about 0.001° to about 0.1°.

[0036]

[0040] Figure 5 is a flowchart of a method 500 for diffracting light according to one embodiment. Although the method steps are described in relation to Figure 5, those skilled in the art will understand that any system configured to execute the method steps in any order falls within the scope of the embodiments described herein.

[0037]

[0041] Method 500 begins at step 540, where a light beam having a wavelength λ is projected onto a first region 107 of a first substrate 103 at a fixed beam angle θ0 and a maximum orientation angle φ max using any of the configurations 100A, 100B, 100C of FIGS. 1A - 1C, FIGS. 4A - 4D of the measurement system 101 and any of the configurations of the detector arm 150. The white light source 114 projects white light at the fixed beam angle θ0 along the optical path 126A to the reference region 107, and the reference region 107 has one or more gratings 109, where θ0 = arcsin(λ laser / 2P grating ), and P grating is the design / average pitch of the grating.

[0038]

[0042] At step 550, a displacement angle Δθ is obtained. According to some embodiments, the displacement angle Δθ is equal to a first angle Δθ1, where Δ1 = f1 * tan(Δθ1), and the displacement distance Δ1 measured as described above. In some embodiments, the displacement angle Δθ is obtained by Δθ = Δθ2 - Δθ1, where in the above formula, the second angle Δθ2 is, as described above, Δ2 = f1 * f3 * tan(Δθ2) / f2.

[0039]

[0043] At step 560, the stage 102 is rotated until an initial intensity maximum value (initial I max ) at the fixed beam angle θ0 is measured, and the maximum orientation angle φ max is obtained. The maximum orientation angle φ max corresponds to the orientation angle φ of one or more gratings 109 in the reference region 107. A target maximum beam angle θ t-max is calculated, and θ t-max = θ0 + Δθ. In the calculation of the target maximum beam angle θ t-max using Δθ, overall distortions such as the overall tilt and warp of the substrate are taken into account.

[0040]

[0044] At step 570, at the maximum orientation angle φ max the test grating pitch P t-gratingis determined. To determine the initial pitch, a fixed beam angle θ0 and a maximum orientation angle φ max are used to project white light, and the equation P t-grating =P grating +ΔP=λ laser / (sinθ t-max +sinθ0) is solved. Further, the change ΔP in the measured pitch is obtained as follows.

[0041] TIFF0007702880000001.tif17170

[0045]

[0042]

[0046] The change in the measured pitch ΔP can be from about 1 pm to about 5 nm.

[0043]

[0047] In one embodiment, steps 540, 550, 560, and 570 are repeated. In step 570, the stage 102 is scanned along the scanning path 110, and steps 540, 550, 560 are repeated for subsequent zones of one or more regions 107 of one or more optical devices 105, or steps 540, 550, 560 are repeated for subsequent regions. Further, by repeating steps 540, 550, 560, and 570 after rotating the entire substrate 103 by about 180° about the z-axis, the overall measurement of the wafer wedge becomes possible.

[0044]

[0048] As described above, an apparatus and method configured to measure local non-uniformity of an optical device are included. The reflected laser light is detected by a detector arm. The detector arm includes one or more focusing lenses, and the one or more focusing lenses focus light onto a detector such as a camera. The displacement of the reflected light with respect to the test substrate is used to calculate the existing local non-uniformity. The substrate can be scanned so that the non-uniformity of different regions of the substrate can be measured.

[0045]

[0049] In this measurement system and method, non-uniform characteristics of an optical device on a substrate, such as grating pitch and grating orientation, can be measured. Further, this measurement system and method can determine local warping and deformation of the underlying substrate. Also, defects of the underlying support surface, such as particle imperfections, can be located to determine whether the substrate and the optical device have acceptable characteristics. The measurement can be performed on substrates or optical devices of various sizes and shapes.

[0046]

[0050] Although the foregoing is directed to embodiments of the present disclosure, it is possible to devise other further embodiments of the present disclosure without departing from its basic scope as determined by the following claims.

Claims

1. A stage having a substrate support surface, the stage being coupled to a stage actuator configured to move the stage along a scanning path and rotate the stage about an axis orthogonal to the substrate support surface, An optical arm configured to scan an optical arm in a direction in which the axis extends and rotate the optical arm about the axis, and to project a light beam onto a substrate disposed on the substrate support surface along an optical path of a beam angle θ, A laser positioned adjacent to a beam splitter positioned in the optical path adjacent to a first detector, the laser operable to project a light beam deflected at the beam angle θ along the optical path to the stage onto the beam splitter, and A first detector disposed on the optical arm and operable to detect a light beam reflected onto the optical arm in the optical path passing through the beam splitter Including an optical arm; A detector arm, A detector actuator configured to scan the detector arm in a direction in which the axis extends and rotate the detector arm about the axis such that diffracted light of the light beam generated by the optical arm is incident on the detector arm, A first focusing lens, A second detector configured to obtain a first delta distance Δ1 that separates a first incident spot of an initial R0 beam projected onto the first focusing lens from the optical center of the first focusing lens and determine local distortion information, Including a detector arm; A measurement system comprising.

2. The optical arm further, A white light source operable to project white light at the beam angle θ along the optical path to the stage, A spectrometer coupled to the first detector and configured to determine the wavelength of the light beam deflected by the first detector, The measurement system according to claim 1, comprising.

3. The optical arm further, A polarizer positioned between the laser and the beam splitter, A quarter-wave plate positioned adjacent to the beam splitter in the optical path, The measurement system according to claim 1, comprising.

4. The resolution of the first detector is about Δ １ less than that of the measurement system according to claim 1.

5. The measurement system according to claim 1, further comprising a second focusing lens and a third focusing lens.

6. The initial R ０ beam is focused by the first focusing lens into a first R ０ beam, and the first R ０ beam is focused by the second focusing lens into a second R ０ beam, and the second R ０ beam is focused by the third focusing lens into a third R ０ beam, the measurement system according to claim 5.

7. the third R ０ The beam is incident on the third focusing lens at a third incident spot, The third incident spot is separated from the optical center of the third focusing lens by a second delta distance Δ ２ only, the second delta distance Δ ２ is greater than the first delta distance Δ １ ​ The measurement system according to claim 6.

8. A stage having a substrate support surface, the stage being coupled to a stage actuator configured to move the stage along a scanning path and rotate the stage about an axis orthogonal to the substrate support surface, an optical arm configured to scan along the direction in which the axis extends and rotate the optical arm about the axis, the optical arm being coupled to an arm actuator configured to project a light beam onto a substrate disposed on the substrate support surface along an optical path of a beam angle θ, a laser positioned adjacent to a beam splitter positioned in the optical path adjacent to a first detector, the laser being operable to project a light beam deflected at the beam angle θ along the optical path to the stage onto the beam splitter, and a first detector disposed on the optical arm and operable to detect a light beam reflected to the optical arm in the optical path passing through the beam splitter comprising an optical arm; a first detector arm and a second detector arm, each coupled to a detector actuator configured to scan the first detector arm or the second detector arm, a first focusing lens, a second detector configured to obtain a first delta distance Δ1 that moves a first incident spot of an initial R0 beam projected onto the first focusing lens away from the optical center of the first focusing lens to determine local distortion information, comprising the first detector arm and the second detector arm; A measurement system comprising.

9. The measurement system according to claim 8, wherein the second detector arm is disposed behind the optical arm.

10. The optical beam is reflected by a workpiece disposed on the stage to form a reflected R １ beam, and the reflected R １ beam is incident on the first focusing lens of the second detector arm at a first incident spot of the second detector arm. The first incident spot of the second detector arm is separated from the optical center of the first focusing lens of the second detector arm by a third delta distance Δ ３ only. The measurement system according to claim 9.

Images