An aperture assembly, a measurement lens and an ellipsometer

Abstract

This application provides an aperture assembly, a measuring lens, and an ellipsometer. The aperture assembly, used for mounting on a lens housing to control the spot size, includes an aperture seat and an aperture. The aperture seat includes a first end and a second end. The first end has a first circular groove, and the second end has a second circular groove. The aperture seat also has a through hole extending from the first circular groove to the second circular groove, in which the aperture is installed. The sidewall of the first circular groove has two protrusions and a threaded hole penetrating the sidewall, with the two protrusions and the threaded hole evenly distributed circumferentially. The highest points of the two protrusions are on the same circumference, and the diameter of the circumference matches the outer diameter of the lens housing. A screw that can be screwed in and out is installed in the threaded hole. The aperture assembly of this application is assembled with the lens housing. The evenly distributed circumference of the two protrusions and the screw forms a three-point positioning, reducing stress concentration at the contact points, facilitating the finding of low-stress angles, and enabling rapid centering.

Description

Technical Field

[0001] This application relates to the field of semiconductor optical measurement equipment technology, and more specifically, to an aperture assembly, a measuring lens, and an ellipsometer. Background Technology

[0002] With the continuous development of semiconductor manufacturing processes, the technology is becoming increasingly complex, requiring ellipsometers to produce smaller and smaller measurement spots. Therefore, it is necessary to add an aperture stop to the lens in the ellipsometer optical path to control the measurement spot. The aperture stop is typically mounted on the lens using an aperture stop mount. However, the addition of the aperture stop mount introduces two variables: the stress on the mount and the center position of the measurement spot. The stress direction and the center position of the measurement spot directly affect the measurement structure.

[0003] In existing technology, the conventional approach is to fabricate a circular aperture mount that fits the lens housing. This mount is then fitted onto the lens housing, and after rotating to find an angle with minimal stress, it is locked in place with a set screw. However, if the aperture mount's circular hole fits too tightly with the lens housing, it becomes difficult to fit the mount securely. Conversely, if the aperture mount's circular hole fits too loosely, it can cause the aperture to become off-center. Furthermore, due to the loose fit, the contact between the aperture mount's circular hole and the lens housing is unstable, which can easily lead to changes in the center position of the light spot, further exacerbating measurement inaccuracies. Utility Model Content

[0004] The purpose of this application is to provide an aperture assembly, a measuring lens, and an ellipsometer, wherein the aperture assembly forms a three-point positioning by means of two convex peaks and a top wire evenly distributed around the circumference, which reduces stress concentration at the contact point, makes it easy to find the low stress angle, and enables rapid centering.

[0005] In one aspect, an aperture assembly is provided for mounting on a lens housing to control the size of the light spot, including an aperture mount and an aperture stop.

[0006] The aperture holder includes a first end and a second end. The first end has a first circular groove, and the second end has a second circular groove. The aperture holder also has a through hole extending from the first circular groove to the second circular groove, in which the aperture is installed. The sidewall of the first circular groove has two protrusions and a threaded hole penetrating the sidewall, the two protrusions and the threaded hole being evenly distributed circumferentially. The highest points of the two protrusions are on the same circumference, and the diameter of the circumference matches the outer diameter of the lens housing; a screw that can be screwed in and out is installed in the threaded hole.

[0007] In one feasible solution, the highest point of the convex peak is an arc surface that conforms to the outer wall of the lens housing.

[0008] In one feasible solution, the highest point of the convex peak has a pointed structure protruding toward the through-hole side, the pointed structure extending axially and forming line contact with the lens housing.

[0009] In one feasible scheme, the diameter of the circumference of the highest point of the two peaks is D1, the outer diameter of the lens housing is D2, and the absolute value of D1-D2 is less than or equal to 10um.

[0010] In one feasible embodiment, the end of the set screw installed in the threaded hole is rounded, with the end facing the inside of the first circular groove being rounded.

[0011] In one feasible solution, the set screw is a spring set screw.

[0012] In one feasible embodiment, the sidewall of the second circular groove is provided with a plurality of circumferentially distributed grooves, which extend axially and communicate with the second circular groove; the grooves are used to fill glue to fix the aperture.

[0013] In one feasible embodiment, a third circular groove is provided on the outer side of the second circular groove at the second end of the aperture seat, and the side wall of the third circular groove is provided with internal threads; the aperture assembly also includes a tightening ring, the outer circumferential wall of the tightening ring is provided with external threads, and the outer diameter of the tightening ring facing the second circular groove is smaller than the inner diameter of the second circular groove; the tightening ring is threadedly engaged with the third circular groove and pressed against the edge of the aperture.

[0014] Secondly, a measuring lens is also provided, including a lens and the aforementioned aperture assembly. The lens includes a lens housing. The first circular groove of the aperture seat of the aperture assembly is fitted onto the lens housing, placing the lens housing within the circumference enclosed by two protrusions. When the aperture seat is rotated until the center position of the light spot meets the requirements, the set screw is rotated to press against the surface of the lens housing.

[0015] Thirdly, an ellipsometer is also provided, including the aforementioned measuring lens.

[0016] Compared with the prior art, the beneficial effects of this application include at least the following: In the aperture assembly of this application, the aperture seat is precisely matched with the outer diameter of the lens housing through the circumferential diameter of the tops of the two convex peaks, avoiding the aperture misalignment problem caused by an excessively loose fit. Specifically, the two convex peaks and the top screw are evenly distributed circumferentially, forming a stable "three-point positioning structure". Compared with the "surface contact / unstable line contact" between the traditional circular aperture seat and the lens housing, this structure allows the aperture seat and the lens housing to maintain stable contact at all times, effectively preventing the aperture seat from undergoing slight displacement during measurement, thereby avoiding changes in the center position of the light spot and reducing measurement errors.

[0017] Meanwhile, compared to the traditional circular aperture seat and the lens housing's "surface contact / unstable line contact", only two convex peaks and the top screw contact the lens housing, resulting in three-point positioning contact. This reduces the number of contact points, significantly lowers the risk of stress concentration, and makes it easier to find an angle with less stress, thus enabling rapid centering of the aperture seat. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a three-dimensional structural schematic diagram of an aperture assembly according to an embodiment of this application.

[0020] Figure 2 for Figure 1 A schematic diagram of the exploded structure of the central aperture assembly from the first-end view.

[0021] Figure 3 for Figure 1 A schematic diagram of the exploded structure of the center aperture assembly from the second-end view.

[0022] Figure 4 This is a three-dimensional structural diagram of a measuring lens shown in an embodiment of this application.

[0023] Figure 5 for Figure 4 A schematic diagram of the exploded structure of the measuring lens.

[0024] Figure 6 for Figure 4 The front view of the measuring lens.

[0025] Figure 7 For along Figure 6 The first sectional view of AA.

[0026] Figure 8 For along Figure 6 The second sectional view of AA.

[0027] Figure 9 This is a three-dimensional structural schematic diagram of another aperture assembly shown in an embodiment of this application.

[0028] Figure 10 for Figure 9 Exploded view of the central aperture assembly.

[0029] In the diagram: 10. Aperture assembly; 1. Aperture seat; 11. First circular groove; 101. Convex peak; 1011. Arc surface; 1012. Tip structure; 102. Threaded hole; 103. Set screw; 12. Second circular groove; 121. Groove; 13. Through hole; 14. Third circular groove; 2. Aperture; 3. Tightening ring; 20. Lens; 21. Lens housing. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0031] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0032] like Figures 1 to 3 As shown, this application embodiment first provides an aperture assembly 10 for mounting on a lens housing to control the size of the light spot. The aperture assembly 10 includes an aperture seat 1 and an aperture 2.

[0033] The aperture seat 1 includes a first end and a second end. The first end is provided with a first circular groove 11, and the second end is provided with a second circular groove 12. The aperture seat 1 is also provided with a through hole 13 that passes through the first circular groove 11 to the second circular groove 12, and the aperture 2 is installed in the second circular groove 12.

[0034] See Figure 2 The sidewall of the first circular groove 11 is provided with two protrusions 101 and a threaded hole 102 that penetrates the sidewall. The two protrusions 101 and the threaded hole 102 are evenly distributed around the circumference. The tops of the two protrusions 101 are on the same circumference, and the diameter of the circumference is adapted to the outer diameter of the lens housing. A set screw 103 that can be screwed in and out is installed in the threaded hole 102.

[0035] In this embodiment, when the aperture assembly 10 is in use, the aperture 2 is installed in the second circular groove 12 of the aperture seat 1, and the set screw 103 is pre-installed in the threaded hole 102 of the aperture seat 1. During pre-installation, the extension length of the set screw 103 toward the inner side of the first circular groove 11 is controlled to avoid it protruding excessively from the inner wall of the first circular groove 11, so as to ensure that the aperture seat 1 can be smoothly fitted into the lens housing.

[0036] See Figure 4 , Figure 5 and Figure 6The first circular groove 11 of the aperture seat 1 is fitted onto the lens housing 21. At this time, the two protrusions 101 on the side wall of the first circular groove 11 play a key positioning role: because the tops of the two protrusions 101 are on the same circumference, and the diameter of this circumference matches the outer diameter of the lens housing 21. Since only the tops of the two protrusions 101 in the first circular groove 11 of the aperture seat 1 contact the lens housing 21, the contact area is significantly reduced. Therefore, by rotating the aperture seat 1 and using the protrusions 101, centering can be quickly achieved, and the number of contact points can be effectively reduced to reduce stress. Then, the set screw 103 is pre-rotated so that the head of the set screw 103 contacts the outer wall of the lens housing 21, which prevents the aperture seat 1 from loosening and avoids excessive compression, thus completing the assembly of the aperture assembly 10 and the lens housing 21.

[0037] In existing technologies, an overly tight fit between the aperture seat's through-hole and the lens housing leads to installation difficulties and may cause excessive stress, while an overly loose fit can cause misalignment. In this application, the circumferential diameter of the two protrusions 101 is precisely matched with the outer diameter of the lens housing 21, avoiding the aperture misalignment problem caused by an overly loose fit. Specifically, the two protrusions 101 and the set screw 103 are evenly distributed in a 120° circumference, forming a stable "three-point positioning structure." Compared to the "surface contact / unstable line contact" between the traditional through-hole aperture seat and the lens housing, this structure ensures that the aperture seat 1 and the lens housing 21 maintain stable contact at all times, effectively preventing minute displacement of the aperture seat 1 during measurement, thereby avoiding changes in the center position of the light spot and reducing measurement errors.

[0038] Meanwhile, only two protrusions 101 and top screw 103 contact the lens housing 21, forming a three-point positioning contact. This reduces the number of contact points, lowers the risk of stress concentration, and makes it easier to find an angle with less stress, thus enabling rapid centering of the aperture seat 1.

[0039] In some embodiments, such as Figure 7 and Figure 8 As shown, the set screw 103 installed in the threaded hole 102 has a rounded end facing the inner side of the first circular groove 11, which can further reduce stress concentration.

[0040] In some embodiments, the set screw 103 can be a spring set screw, that is, a spring is provided at the rear end of the round head of the spring set screw, so that the round head of the spring set screw has a certain compressibility when it is not compressed to the limit.

[0041] Thus, after the first circular groove 11 of the aperture seat 1 is fitted onto the lens housing, the two protrusions 101 on the side wall of the first circular groove 11 first play a key positioning role, and the aperture seat 1 can quickly achieve initial centering through the protrusions 101. Then, the pre-rotation of the set screw 103 makes the head of the spring set screw elastically contact the outer wall of the lens housing 21 (at this time, the spring set screw is not compressed to its limit), which avoids the aperture seat 1 from loosening and does not produce excessive compression.

[0042] Afterwards, while maintaining the elastic pre-tightened state of the set screw 103, slowly rotate the aperture seat 1. During this process, the contact between the two protrusions 101 and the lens housing 21 provides stable guidance for the rotation. At the same time, since it is not completely locked, the angle of the aperture seat 1 can be flexibly adjusted until the position of minimum stress of the aperture seat 1 is found (corresponding to the state where stress has the least impact on the measurement result in ellipsometric measurement), and the aperture 2 is centered, which is the preferred angle of the aperture seat 1.

[0043] After determining the preferred angle, tighten the set screw 103 to form a "three-point positioning" with the set screw 103 and the two protrusions 101, and firmly fix the aperture seat 1 on the lens housing 21, thus completing the installation and positioning of the aperture assembly 10.

[0044] During installation, the aperture seat 1 can rotate freely under the pre-tightened state of the set screw 103, which makes it easy for the operator to find the angle with the least stress on the aperture seat 1. This design directly addresses the pain point that the stress direction affects the measurement results. By optimizing the angle, the interference of the stress of the aperture seat 1 itself on the elliptic measurement optical path is reduced, further improving the measurement accuracy.

[0045] In some embodiments, such as Figure 7 As shown, the top of the convex peak 101 can be designed to be an arc surface 1011 that fits the outer wall of the lens housing.

[0046] In some embodiments, such as Figure 8 As shown, the top of the peak 101 can be designed to have a pointed structure 1012 protruding towards the through hole 13. The pointed structure 1012 extends axially and forms a line contact with the lens housing.

[0047] In some embodiments, the diameter of the circumference of the highest point of the two peaks 101 is D1, the outer diameter of the lens housing 21 is D2, and the absolute value of D1-D2 is less than or equal to 10 μm.

[0048] In existing solutions, considering the ease of assembly between the aperture seat's through hole and the lens housing, the diameter of the aperture seat's through hole is generally 50µm larger than the lens housing diameter to facilitate assembly and reduce stress concentration.

[0049] In this embodiment, due to the use of a three-point contact with two protrusions 101 and a top screw 103, the number of contact points between the lens and the lens housing 21 is significantly reduced, making the dimensions easier to control and effectively alleviating the stress concentration problem. Therefore, the absolute value of the difference between the diameter D1 of the circumference of the highest point of the protrusion 101 and the outer diameter D2 of the lens housing 21 can be reduced to no more than 10 μm, thereby significantly improving assembly accuracy and thus improving the center alignment accuracy of the aperture 2, which in turn improves the accuracy of the spot center position.

[0050] In some embodiments, such as Figure 3 As shown, the sidewall of the second circular groove 12 can be provided with a plurality of circumferentially distributed grooves 121. The grooves 121 extend axially and communicate with the second circular groove 12. The grooves 121 are used to fill optical glue to fix the aperture 2 and can also reduce stress problems.

[0051] In some embodiments, such as Figure 9 and Figure 10 As shown, a third circular groove 14 can also be provided on the outer side of the second circular groove 12 at the second end of the aperture seat 1, and the side wall of the third circular groove 14 is provided with internal threads. The aperture assembly 10 may also include a tightening ring 3, the outer circumferential wall of the tightening ring 3 is provided with external threads, and the outer diameter of the tightening ring 3 facing the second circular groove 12 is smaller than the inner diameter of the second circular groove 12. The tightening ring 3 is threadedly engaged with the third circular groove 14 and pressed against the edge of the aperture 2, thereby ensuring that the position of the aperture 2 in the aperture seat 1 remains stable over a long period of time.

[0052] like Figures 4 to 6 As shown, this application embodiment also provides a measuring lens, including a lens 20 and the aforementioned aperture assembly 10. The lens 20 includes a lens housing 21. The first circular groove 11 of the aperture seat 1 of the aperture assembly 10 is fitted onto the lens housing 21, and the lens housing 21 is positioned within the circumference enclosed by the two protrusions 101. When the aperture seat 1 is rotated until the center position of the light spot meets the requirements, the set screw 103 is rotated to press against the surface of the lens housing 21.

[0053] This application also provides an ellipsometer, including the aforementioned measuring lens.

[0054] The above description is only a partial preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An aperture assembly for mounting on a lens housing to control the size of the light spot, characterized in that, Includes aperture seat (1) and aperture (2); The aperture seat (1) includes a first end and a second end, the first end of which is provided with a first circular groove (11), and the second end of which is provided with a second circular groove (12); The aperture seat (1) is also provided with a through hole (13) that passes through the first circular groove (11) to the second circular groove (12), and the aperture (2) is installed in the second circular groove (12); The sidewall of the first circular groove (11) is provided with two protrusions (101) and a threaded hole (102) that penetrates the sidewall. The two protrusions (101) and the threaded hole (102) are evenly distributed around the circumference. The two peaks (101) are at the same circumference, and the diameter of the circumference is adapted to the outer diameter of the lens housing; a screw (103) that can be screwed in and out is installed in the threaded hole (102).

2. The aperture assembly according to claim 1, characterized in that, The top of the convex peak (101) is an arc surface (1011) that is adapted to the outer wall of the lens housing.

3. The aperture assembly according to claim 1, characterized in that, The top of the convex peak (101) has a pointed structure (1012) that protrudes toward the through hole (13), and the pointed structure (1012) extends axially and forms a line contact with the lens housing.

4. The aperture assembly according to any one of claims 1-3, characterized in that, The diameter of the circumference of the two peaks (101) is D1, the outer diameter of the lens housing is D2, and the absolute value of D1-D2 is less than or equal to 10um.

5. The aperture assembly according to claim 1, characterized in that, The end of the set screw (103) facing the inside of the first circular groove (11) is rounded.

6. The aperture assembly according to claim 1, characterized in that, The set screw (103) is a spring set screw.

7. The aperture assembly according to claim 1, characterized in that, The sidewall of the second circular groove (12) is provided with a plurality of grooves (121) distributed circumferentially, the grooves (121) extending axially and communicating with the second circular groove (12); The groove (121) is used to fill glue to fix the aperture (2).

8. The aperture assembly according to claim 7, characterized in that, A third circular groove (14) is also provided on the outer side of the second circular groove (12) at the second end of the aperture seat (1), and the side wall of the third circular groove (14) is provided with an internal thread; The aperture assembly also includes a tightening ring (3), the outer circumferential wall of the tightening ring (3) is provided with an external thread, and the outer diameter of the tightening ring (3) facing the second circular groove (12) is smaller than the inner diameter of the second circular groove (12); The tightening ring (3) is threaded into the third circular groove (14) and pressed against the edge of the aperture (2).

9. A measuring lens, characterized in that, Includes a lens (20) and an aperture assembly according to any one of claims 1 to 8, wherein the lens (20) includes a lens housing (21); The first circular groove (11) of the aperture seat (1) of the aperture assembly is fitted onto the lens housing (21), and the lens housing (21) is located within the circumference enclosed by the two protrusions (101); Rotate the aperture seat (1) until the center position of the light spot meets the requirements, then rotate the set screw (103) to press against the surface of the lens housing (21).

10. An ellipsometer, characterized in that, Includes the measuring lens as described in claim 9.

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