Polarized beam manipulation background

Abstract

A polarization beam manipulation unit comprising: (i) a polarization beam splitter exhibiting a polarization extinction ratio based on the incident angle of the radiation light; and (ii) a telecentric lens located in front of the polarizing beam splitter configured to: (a) receive a non-collimated input beam comprising rays of different angles of incidence, and (b) convert the non-collimated input beam into a collimated input beam comprising rays of light parallel to each other when incident to the polarizing beam splitter.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit and priority of U.S. Patent Application No. 18 / 956,613, filed November 22, 2024, entitled “Polarizing Beam Manipulation Background”, the entirety of which is incorporated herein by reference.

[0003] Related technologies are shown

[0004] The polarization beam splitter is configured to split the input beam into a first polarized beam that is reflected and a second polarized beam that is transmitted.

[0005] The polarization extinction ratio is the ratio between the reflected first polarized beam and the transmitted second polarized beam.

[0006] It has been found that the polarization extinction ratio varies significantly (e.g., by a factor exceeding ten) along the longitudinal field of view of the polarization beam splitter. This field of view corresponds to the point where the input beam is formed on the polarization beam splitter.

[0007] Currently, there is an increasing demand for improving the uniformity of polarization extinction ratio within the field of view. Summary of the Invention

[0008] A polarization beam manipulation unit is provided, comprising (a) a polarization beam splitter that exhibits a polarization extinction ratio based on the incident angle of the radiating rays; and (b) a telecentric lens located in front of the polarization beam splitter, configured to (a) receive a non-collimated input beam comprising rays with different incident angles, and (b) convert the non-collimated input beam into collimated input beams that are parallel to each other when incident on the polarization beam splitter.

[0009] A polarization-based beam manipulation method is provided, the method comprising: (a) receiving a non-collimated input beam comprising rays with different incident angles by a telecentric lens; (b) converting the non-collimated input beam into collimated input beams parallel to each other when incident on a polarization beam splitter displaying a polarization extinction ratio based on the incident angle of the radiated rays by the telecentric lens; and (c) optically processing the collimated input beam through the polarization beam splitter.

[0010] The attached diagram shows

[0011] The subject matter of the invention is specifically pointed out by way of example and is clearly stated at the end of the specification. However, the embodiments, in terms of organization and methods of operation, as well as the likenesses, features, and advantages thereof, are best understood by referring to the following detailed description and accompanying illustrations.

[0012] Figure 1 An example of a polarization beam manipulation unit is shown;

[0013] Figure 2 An example of the polarization extinction ratio of the field of view along the longitudinal axis of the polarization beam splitter is shown, illustrating the situation without a telecentric lens and with the proposed polarization beam manipulation unit.

[0014] Figure 3 An example of the system is shown; and

[0015] Figure 4 An example of the method is shown.

[0016] It should be understood that, for the sake of simplicity and clarity, the elements shown in the figures are not necessarily drawn to scale. For example, the dimensions of some elements may be exaggerated relative to others to improve clarity. Furthermore, reference numerals may be repeated in the figures when deemed appropriate to indicate corresponding or similar elements. Detailed Implementation

[0017] A solution is provided to reduce the difference between polarization extinction ratios, enabling polarization property control during microscopic examination, especially during optical examination of patterned samples such as patterned wafers.

[0018] According to an embodiment, the polarization property control involves at least controlling the polarization of light transmitted to the sample or controlling the polarization of light reflected from the sample.

[0019] Polarization control may involve the use of a polarization beam splitter. Alternatively, polarization property control may be performed by one or more other polarization control elements located in the illumination channel, and, alternatively, in the collection channel.

[0020] According to an embodiment, the polarization property control is used to reduce image background (e.g., by blocking the polarization component of the reflected beam reflected by the pattern) and to enhance signals from specific regions of the wafer by selecting the optimal polarization state that penetrates the wafer pattern.

[0021] According to an embodiment, the blocking is performed by a polarization beam splitter that does not transmit the polarization component of the beam reflected by the pattern to the collection channel, but instead transmits the polarization component of the reflected beam generated by the illumination beam penetrating the pattern to the collection channel.

[0022] Figure 1An example of a polarization beam manipulation unit 100 is shown, which includes (i) a polarization beam splitter 102 that exhibits a polarization extinction ratio based on the incident angle of the radiating rays, and (ii) a telecentric lens 104 located in front of the polarization beam splitter, configured to (a) receive a non-collimated input beam 121 comprising rays with different incident angles, and (b) convert the non-collimated input beam into a collimated input beam 123 that is parallel to each other when incident on the polarization beam splitter.

[0023] Figure 1 The diagram also shows the longitudinal axis 119 of the polarization beam splitter 102, the point 121-1 formed by the collimated input beam 123 on the input surface 129 of the collimated input beam 123, and the field of view segment 119-1 of the polarization beam splitter along the longitudinal axis. The polarization beam splitter also includes a first surface 127 and a second surface 128.

[0024] Parallel light rays are almost identical in terms of the polarization extinction ratio they experience, and substantially identical light rays can tolerate differences below a certain threshold—for example, differences of 10-50%, 15-200%, 20-450%, etc.

[0025] According to one embodiment, assuming that the light rays at the center of the field of view of the polarizing beam splitter are perpendicular to the polarizing beam splitter, then the polarized beam (in the absence of a telecentric lens) will provide the light rays at the center of the field of view with a much higher polarization extinction ratio compared to the light rays around the polarizing beam splitter that are off-center from the field of view.

[0026] According to the embodiment, the back focal plane 101 of the telecentric lens 104 coincides with the point light source 126 of the non-collimated input beam 121.

[0027] According to the embodiments, the telecentric lens improves the uniformity of the polarization extinction ratio in the longitudinal field of view of the polarization beam splitter by at least ten times, or at least twenty times, or at least thirty times, or at least fifty times, or at least one hundred times.

[0028] For example, in the absence of a telecentric lens, the highest polarization extinction ratio exceeds the lowest polarization extinction ratio by more than one hundred, while the highest polarization extinction ratio of the proposed polarization beam manipulation unit exceeds the lowest polarization extinction ratio by no more than ten.

[0029] Figure 2 Examples of polarization extinction ratios along the field of view are shown in the longitudinal direction of a polarizing beam splitter without a telecentric lens (Figure 11) and in the case of using the proposed polarizing beam manipulation unit (Figure 12). The X-axis represents a point in the field of view, and the Y-axis represents the polarization extinction ratio – expressed on a logarithmic scale.

[0030] According to the embodiments, such as Figure 1As shown, the polarization beam splitter 102 is a cube, including a first right-angle prism 111 and a second right-angle prism 112.

[0031] According to an embodiment, the hypotenuse surface 113 of the first right-angle prism is covered with a polarizing coating. According to an embodiment, the hypotenuse surface of the second right-angle prism is also covered with a polarizing coating.

[0032] Figure 3 An example of system 130 is shown, which includes an illumination channel 140, one or more collection channels 150, and a polarization beam manipulation unit 100. The illumination channel 140 shares a polarization beam splitter 102 and an objective lens 131 with the one or more collection channels 150.

[0033] According to an embodiment, illumination channel 140 guides a non-collimated input beam 121 to a telecentric lens, which provides a collimated input beam 123 (with a first polarization) to a polarizing beam splitter 102. The polarizing beam splitter 102 is configured to: (i) reflect the collimated input beam 123 toward a first surface 127 of the polarizing beam splitter; (ii) receive a reflected beam 125 with a second polarization orthogonal to the first polarization at the first surface 127; and (iii) guide the reflected beam 125 to a second surface 128 of the polarizing beam splitter. The collimated input beam 123 passes through an input surface 129.

[0034] According to an embodiment, the second surface is opposite to the first surface, and the input surface is perpendicular to the first surface.

[0035] Figure 3 One or more collection channels 150 are shown, including a bright field collection channel 151 (including a bright field collection channel optics 151-1 and a bright field sensor 151-2) and a gray field collection channel 152 (including a gray field collection channel optics 152-1 and a gray field sensor 152-2), which share a second beam splitter 153—for example, an apertured mirror that performs spatial (rather than angle-based) beam splitting.

[0036] The number of collection channels can be any number (one or more).

[0037] Figure 4 An example of a polarization-based beam manipulation method 200 is shown.

[0038] According to an embodiment, method 200 is limited to beam splitting.

[0039] According to an embodiment, method 200 is not merely beam splitting.

[0040] According to an embodiment, method 200 includes: a. Step 210: Receive the non-collimated input beam containing rays with different incident angles through a telecentric lens.

[0041] b. Step 220 converts the non-collimated input beam into a collimated input beam using a telecentric lens. The collimated input beam comprises rays that are parallel to each other when incident on a polarizing beamsplitter, which exhibits a polarization extinction ratio based on the incident angle of the radiated rays.

[0042] c. Step 230: Optical processing is performed on the collimated input beam using a polarizing beam splitter. According to an embodiment, the processing includes guiding the collimated input beam (or certain polarization components of the collimated input beam) to the sample (via the objective lens).

[0043] d. Step 240, optical processing of the reflected beam from the sample. According to an embodiment, the processing includes guiding the reflected beam (or certain polarization components of the reflected beam) to at least one collection channel.

[0044] According to one embodiment, the back focal plane of the telecentric lens coincides with the point source of the non-collimated input beam.

[0045] According to one embodiment, step 220 includes improving the uniformity of the polarization extinction ratio in the longitudinal field of view of the polarization beamsplitter by at least ten times.

[0046] According to one embodiment, the polarization beam splitter is a cube, comprising a first right-angle prism and a second right-angle prism.

[0047] According to one embodiment, the hypotenuse surface of the first right-angle prism is covered with a polarizing coating.

[0048] According to one embodiment, the collimated input beam is a first polarized light, wherein the optical processing in steps 230 and 240 includes: a. Reflect the collimated input beam onto the first surface of the polarizing beam splitter.

[0049] b. The reflected beam of second polarized light is received on the first surface, and the second polarized light is orthogonal to the first polarized light.

[0050] c. Guide the reflected beam to the second surface of the polarizing beam splitter.

[0051] According to an embodiment, the second surface is opposite to the first surface, wherein the collimated input beam is received by a third surface perpendicular to the first surface.

[0052] Numerous specific details are set forth in the foregoing detailed description to provide a thorough understanding of embodiments of this disclosure.

[0053] However, those skilled in the art will understand that the embodiments disclosed herein can be implemented without these specific details. In other instances, some well-known methods, procedures, and elements have not been described in detail so as not to obscure the embodiments disclosed herein.

[0054] The subject matter considered as embodiments of this disclosure is specifically pointed out and explicitly claimed at the end of the specification. However, these disclosed embodiments, in terms of organization and manipulation methods, as well as their purposes, features, and advantages, are most readily understood by reference to the following detailed description, read in conjunction with the accompanying illustrations.

[0055] It should be noted that, for the sake of simplicity and clarity, the elements shown in the figures are not necessarily drawn to scale. For example, the dimensions of some elements may be exaggerated relative to others for clarity. Furthermore, where appropriate, reference numerals may be repeated in the figures to indicate corresponding or similar elements.

[0056] Since most of the disclosed examples can be implemented using optical elements and circuits known to those skilled in the art, the details will not be explained in more detail than is deemed necessary above in order to understand and appreciate the basic concepts of the examples disclosed and to avoid confusion or distraction from the teachings of the embodiments disclosed.

[0057] Any references to the methods in this specification shall be adapted accordingly to systems capable of performing the methods.

[0058] Any references to the system in the specification shall apply accordingly to the methods that may be performed by the system.

[0059] The term "and / or" indicates addition or substitution. For example, A and / or B means only A, only B, or A and B.

[0060] The foregoing description lists many specific details to provide a deeper understanding of the public demonstration.

[0061] However, those skilled in the art will understand that embodiments of this disclosure can be practiced without these specific details. In other instances, known methods, procedures, and components have not been described in detail so as not to obscure the embodiments of this disclosure.

[0062] The subject matter considered as an embodiment of this disclosure is specifically pointed out and explicitly claimed at the end of the specification. However, the organization and operation of the disclosed embodiments, as well as their objects, features, and advantages, are best understood by referring to the following detailed description, and in conjunction with the appendix. Figure 1 Start reading.

[0063] In the foregoing specification, the disclosed embodiments have been described with reference to specific examples. However, it will be apparent that various modifications and alterations can be made without departing from the broader spirit and scope of the appended claims.

[0064] For any reference to the terms “including”, “own”, or “contains”, it shall apply as appropriate to “consisting of” and / or as appropriate to “consisting substantially of”.

[0065] However, other modifications, changes, and alternatives are possible. Therefore, these instructions and illustrations should be considered illustrative rather than restrictive.

[0066] In the claims, any reference marks placed in parentheses should not be construed as limiting the claims. The term "comprising" does not exclude the presence of other elements or steps besides those listed in the claims. Furthermore, the terms "a" or "an" as used herein are defined as one or more. Similarly, the use of introductory phrases such as "at least one" and "one or more" in the claims should not be construed as implying that other claim elements introduced by the indefinite article "a" or "an" are limited to embodiments containing only one such element, even if the same claim contains the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an." This is also true for the use of definite articles. Unless otherwise shown, terms such as "first" and "second" are used to arbitrarily distinguish the elements described by these terms. Therefore, these terms are not necessarily intended to indicate the temporality or other priority of these elements. The fact that certain measures are listed in mutually different claims does not mean that combinations of these measures cannot be used advantageously.

[0067] While certain features of this embodiment have been demonstrated and described herein, many modifications, substitutions, alterations, and equivalents will arise for those skilled in the art. Therefore, it should be understood that the appended claims are intended to cover all such modifications and alterations and are consistent with the true spirit of the described embodiments.

Claims

1. A polarization beam manipulation unit, comprising: A polarization beamsplitter that exhibits a polarization extinction ratio based on the incident angle of the radiated light; as well as A telecentric lens located before the polarizing beam splitter is configured to: (a) receive a non-collimated input beam comprising rays with different incident angles, and (b) convert the non-collimated input beam into a collimated input beam comprising rays that are parallel to each other when incident on the polarizing beam splitter.

2. The polarization beam manipulation unit as claimed in claim 1, wherein the telecentric lens has a back focal plane that coincides with the point source of the non-collimated input beam.

3. The polarization beam manipulation unit as claimed in claim 1, wherein the telecentric lens improves the uniformity of the polarization extinction ratio in the field of view along the longitudinal axis of the polarization beam splitter by a factor of at least ten.

4. The polarization beam manipulation unit as claimed in claim 1, wherein the polarization beam splitter is a cube, comprising a first right-angle prism and a second right-angle prism.

5. The polarization beam manipulation unit as claimed in claim 4, wherein the inclined surface of the first right-angle prism is covered with a polarization coating.

6. The polarization beam manipulation unit according to any one of claims 1 to 5, wherein the collimated input beam is a first polarized light, wherein the polarization beam splitter is configured to: (i) reflect the collimated input beam to a first surface of the polarization beam splitter, (ii) receive a reflected beam of a second polarized light orthogonal to the first polarized light at the first surface, and (iii) guide the reflected beam to a second surface of the polarization beam splitter.

7. The polarization beam manipulation unit of claim 6, wherein the second surface is opposite to the first surface, and wherein the collimated input beam is received by a third surface perpendicular to the first surface.

8. A polarization-based beam manipulation method, the method comprising: A non-collimated input beam, including light rays with different incident angles, is received through a telecentric lens; The telecentric lens converts the non-collimated input beam into a collimated input beam, which includes rays that are parallel to each other when incident on the polarizing beamsplitter, which exhibits a polarization extinction ratio based on the incident angle of the radiated rays. as well as The collimated input beam is optically processed by the polarization beam splitter.

9. The method of claim 8, wherein the telecentric lens has a back focal plane that coincides with the point source of the non-collimated input beam.

10. The method of claim 8, wherein the conversion includes improving the uniformity of the polarization extinction ratio in the field of view of the longitudinal axis of the polarization beamsplitter by a factor of at least ten.

11. The method of any one of claims 8 to 10, wherein the polarizing beam splitter is a cube, comprising a first right-angle prism and a second right-angle prism.

12. The method of claim 11, wherein the hypotenuse surface of the first right-angle prism is covered with a polarizing coating.

13. The method of any one of claims 8 to 10, wherein the collimated input beam is a first polarized light, and the optical processing comprises: (i) Reflecting the collimated input beam onto the first surface of the polarizing beam splitter; (ii) A reflected beam of second polarized light is received on the first surface, the second polarized light being orthogonal to the first polarized light; (iii) Directing the reflected beam toward the second surface of the polarizing beam splitter.

14. The method of claim 13, wherein the second surface is opposite to the first surface, and wherein the collimated input beam is received by a third surface perpendicular to the first surface.

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