Wafer detection scattered light collection objective and wafer detection equipment
By designing a wafer inspection scattered light acquisition objective lens and adopting a catadioptric mirror group structure with twelve lenses and aperture stops, the problem of nanoscale wafer defect detection in existing technologies has been solved, realizing efficient wafer defect detection with a large field of view, and reducing cost and complexity.
Patent Information
- Application Number
- CN202411839378.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-13
- Publication Date
- 2025-11-25
- Estimated Expiration
- 2044-12-13
AI Technical Summary
Existing technologies are difficult to effectively detect nanoscale wafer defects, especially in the deep ultraviolet band, and have low detection efficiency, low material transmittance, and difficulty in color difference correction over a large field of view.
Design a wafer inspection scattered light collection objective lens, employing twelve lenses and an aperture stop. Through a catadioptric mirror group structure, a large numerical aperture and a large field of view are achieved. Fused silica material is used to correct chromatic aberration and improve detection capability.
It achieves high signal-to-noise ratio nanoscale defect detection, improves detection efficiency and imaging quality, and reduces production costs and assembly difficulty.
Smart Images
Figure CN119620341B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of optical imaging technology, in particular to a wafer detection scattered light collection objective lens and wafer detection equipment. BACKGROUND
[0002] Wafer defect detection is the key to improving good products in semiconductor process, and using optics, especially laser, to detect wafer surface defects is a common technical route. Due to the limitation of optical resolution, it is necessary to collect scattered light of defects for detecting defects, especially nanoscale defects. In order to improve the signal-to-noise ratio, a high numerical aperture lens is needed. In order to balance the production capacity, the scanning field of view needs to be as large as possible, so a large field of view objective lens is needed. Laser light source is a common wafer detection light source, and quasi-continuous (QCW) deep ultraviolet (DUV) laser is often used to achieve high power. The bandwidth of QCW laser is generally greater than 50pm, which must be considered for large numerical aperture objective lenses. In the deep ultraviolet (DUV) region, the transmittance of ordinary optical materials is very low, and there are few materials that can be used. It is very difficult to correct chromatic aberration.
[0003] The existing patent (publication number: CN117348201) discloses a catadioptric objective lens. Although the wavelength is very wide and the numerical aperture can reach 0.9, the wavelength can only reach the ultraviolet band, not the deep ultraviolet band, and the scanning field of view is 1mm, which has limitations. Therefore, we propose a wafer detection scattered light collection objective lens and wafer detection equipment. SUMMARY
[0004] The purpose of the present application is to provide a wafer detection scattered light collection objective lens and wafer detection equipment, with a numerical aperture of 0.9 and a field of view of 2.6mm, which can greatly improve the detection capability of scattered light of defects.
[0005] To achieve the above purpose, the present application provides the following technical scheme: a wafer detection scattered light collection objective lens applied to wafer defect detection, the scattered light collection lens comprising, in order along its optical axis direction from the object plane to the image plane, a first lens group, a second lens group, a third lens group, a fourth lens group, twelve lenses and an aperture stop, and the twelve lenses and the aperture stop are coaxially arranged;
[0006] The first lens group is a catadioptric lens group with positive focal power, which is used to image the object plane to the intermediate image plane by two reflections;
[0007] The second lens group comprises four lenses with positive focal power, which is used to collimate the intermediate image into quasi-parallel light;
[0008] The third lens group comprises three lenses with negative focal power, which is used to adjust the incident height of quasi-parallel light;
[0009] The fourth mirror group includes two lenses with positive focal length, which collimate the adjusted light rays and change the divergent light rays into collimated light rays.
[0010] Further, the first mirror group includes a first mirror, a second mirror and a third mirror, which are coaxially arranged along the optical axis from the object plane to the image plane.
[0011] Further, the first mirror is a meniscus positive lens, the first surface of the first mirror away from the second mirror is a convex surface, the central transmission area is circular, and the area of the central transmission area accounts for less than 10% of the total area of the first surface, and the remaining area is a reflection area;
[0012] The second surface of the first mirror facing the second mirror is a plane or a convex surface or a concave surface with a large radius of curvature, |R|≥1000;
[0013] The second mirror is a meniscus negative lens, which is curved towards the object plane, and the third mirror is a reflection surface, which is set as a concave surface, and the central area of the third mirror is hollowed out for transmission, and the central hollowed-out area is circular, accounting for less than 5% of the total area of the reflection surface.
[0014] Further, the second mirror group includes a fourth mirror, a fifth mirror, a sixth mirror, a seventh mirror and an aperture stop, which are coaxially arranged along the optical axis from the object plane to the image plane.
[0015] Further, the fourth mirror is a meniscus negative lens, which is curved towards the image plane; the fifth mirror is a biconvex positive lens; the sixth mirror is set as a plano-convex positive lens, a biconvex positive lens or a meniscus positive lens;
[0016] The seventh mirror is a meniscus positive lens, which is curved towards the image plane, and the aperture stop is installed on the side of the seventh mirror facing the image plane.
[0017] Further, the third mirror group includes an eighth mirror, a ninth mirror and a tenth mirror, which are coaxially arranged along the optical axis from the object plane to the image plane.
[0018] Further, the eighth mirror is set as a meniscus negative lens, which is curved towards the image plane; the ninth mirror is set as a biconvex positive lens; and the tenth mirror is set as a meniscus negative lens, which is curved towards the object plane.
[0019] Further, the fourth mirror group includes an eleventh mirror and a twelfth mirror, which are coaxially arranged along the optical axis from the object plane to the image plane.
[0020] Further, the eleventh mirror is set as a meniscus negative lens, which is curved towards the image plane, and the twelfth mirror is set as a plano-convex positive lens, a biconvex positive lens or a meniscus positive lens.
[0021] According to a second aspect of the present application, the present application provides a wafer detection device comprising the wafer detection scattered light collection objective lens described above.
[0022] The present application has at least the following advantages:
[0023] 1. Large numerical aperture: the numerical aperture can reach 0.9, realizing the collection of a scattering light cone angle within 64°.
[0024] 2. Large field of view: the field of view can reach 2.6mm, which greatly improves the detection efficiency compared with the scanning field of view of about 0.5mm of a common microscope or about 1mm of the prior art.
[0025] 3. The present application can realize good correction of aberration of large numerical aperture and large field of view by using only twelve lenses, which reduces the number of lenses, reduces production cost, and reduces assembly difficulty.
[0026] 4. The present application corrects chromatic aberration by using a catadioptric type, which can realize a wider laser bandwidth compared with the general refractive type using CaF2 and fused quartz, and the cost is lower because all fused quartz materials are used.
[0027] Of course, any product implementing the present application does not necessarily need to achieve all the advantages described above at the same time. BRIEF DESCRIPTION OF DRAWINGS
[0028] Figure 1 A structure diagram of a wafer detection scattered light collection objective lens provided for an embodiment of the present application;
[0029] Figure 2 A point column diagram of a wafer detection scattered light collection objective lens provided for an embodiment of the present application;
[0030] Figure 3 A transfer function MTF diagram of a wafer detection scattered light collection objective lens provided for an embodiment of the present application;
[0031] Figure 4 A field curvature and distortion diagram of a wafer detection scattered light collection objective lens provided for an embodiment of the present application.
[0032] Reference signs:
[0033] 1, first lens; 2, second lens; 3, third lens; 4, fourth lens; 5, fifth lens; 6, sixth lens; 7, seventh lens; 8, aperture stop; 9, eighth lens; 10, ninth lens; 11, tenth lens; 12, eleventh lens; 13, twelfth lens; G1, first lens group; G2, second lens group; G3, third lens group; G4, fourth lens group. DETAILED DESCRIPTION
[0034] The technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present disclosure.
[0035] Please refer to Figures 1-4 The present disclosure provides a technical solution: a wafer detection scattered light collection objective lens applied to wafer defect detection. The scattered light collection lens includes, in sequence along the optical axis direction from the object plane to the image plane, a first lens group G1, a second lens group G2, a third lens group G3, a fourth lens group G4, twelve lenses, and an aperture stop 8, and the twelve lenses and the aperture stop 8 are coaxially arranged.
[0036] The first lens group G1 is a catadioptric lens group, has positive focal power, and is used for imaging the object plane to an intermediate image plane through twice reflection.
[0037] The second lens group G2 includes four lenses, has positive focal power, and is used for collimating the intermediate image as quasi-parallel light.
[0038] The third lens group G3 includes three lenses, has negative focal power, and is used for adjusting the incident height of the quasi-parallel light.
[0039] The fourth lens group G4 includes two lenses, has positive focal power, and is used for collimating the adjusted light to change the divergent light into collimated light.
[0040] For the technical solution of the present embodiment, the first lens group G1 includes a first lens 1, a second lens 2, and a third lens 3, which are coaxially distributed in sequence along the optical axis direction from the object plane to the image plane. Specifically, the first lens 1 is a meniscus positive lens, the first face of the first lens 1 away from the second lens 2 is a convex face, the central transmission area is circular, and the central transmission area accounts for less than 10% of the area of the entire first face, and the remaining area is a reflection face area.
[0041] The second face of the first lens 1 toward the second lens 2 is a plane or a convex face or a concave face with a large radius of curvature, |R|≥1000.
[0042] The second lens 2 is a meniscus negative lens, which is curved toward the object plane. The third lens 3 is a reflection face, which is set as a concave face, and the central area of the third lens 3 is hollowed out for transmission. The central hollowed-out area is circular and accounts for less than 5% of the entire area of the reflection face.
[0043] According to the technical scheme of the embodiment, the second lens group G2 comprises a fourth lens 4, a fifth lens 5, a sixth lens 6, a seventh lens 7 and an aperture stop 8, and the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7 and the aperture stop 8 are coaxially arranged in sequence along the optical axis direction from the object plane to the image plane, specifically, the fourth lens 4 is a meniscus negative lens, and is curved towards the image plane; the fifth lens 5 is a biconvex positive lens; the sixth lens 6 can be a plano-convex positive lens, a biconvex positive lens or a meniscus positive lens, which is not limited in the embodiment and can be selected according to the actual situation.
[0044] The seventh lens 7 is a meniscus positive lens, and is curved towards the image plane; the aperture stop 8 is installed on the side of the seventh lens 7 facing the image plane, and is arranged in the lens group, which is beneficial to control the lens size of the overall optical path system; in addition, the aperture stop is close to the image plane, that is, on the right side of the lens 7 close to the concave surface, which is beneficial to correct the off-axis aberration and realize good imaging effect of each field of view.
[0045] According to the technical scheme of the embodiment, the third lens group G3 comprises an eighth lens 9, a ninth lens 10 and a tenth lens 11, and the eighth lens 9, the ninth lens 10 and the tenth lens 11 are coaxially arranged in sequence along the optical axis direction from the object plane to the image plane, specifically, the eighth lens 9 is arranged as a meniscus negative lens, and is curved towards the image plane; the ninth lens 10 is arranged as a biconvex positive lens; and the tenth lens 11 is arranged as a meniscus negative lens, and is curved towards the object plane.
[0046] According to the technical scheme of the embodiment, the fourth lens group G4 comprises an eleventh lens 12 and a twelfth lens 13, and the eleventh lens 12 and the twelfth lens 13 are coaxially arranged in sequence along the optical axis direction from the object plane to the image plane, specifically, the eleventh lens 12 is arranged as a meniscus negative lens, and is curved towards the image plane; and the twelfth lens 13 is arranged as a plano-convex positive lens, a biconvex positive lens or a meniscus positive lens, which is not limited in the embodiment and can be selected according to the actual situation.
[0047] It should be noted that all the lenses in the embodiment are arranged as spherical surfaces, the design of the spherical surface can make the light as parallel as possible before entering the lens, thereby reducing the influence of aberration, and all the lenses are made of fused quartz material, the refractive index of the fused quartz material is very high, which can reach 3.4 to 3.9, which makes the propagation speed of light in the lens slow, thereby making the outgoing light more concentrated, which is beneficial to improve the quality of imaging.
[0048] Further, the numerical aperture of the objective lens described in the embodiment is equal to 0.9, and the field of view is equal to 2.6 mm.
[0049] The element parameters are as follows:
[0050]
[0051]
[0052] Figure 2 The spot diagram of the objective lens is given, and it can be seen that the spot size of each field of view in the spectral bandwidth range is close to the diffraction limit, and the maximum field of view is +-1.3mm; Figure 3 The transfer function of the objective lens is given, and the field of view at each wavelength is close to the diffraction limit, and the 3000lp / mm MTF is more than 0.2, achieving very high resolution; Figure 4 The field curvature and distortion diagram is given, and the field curvature at each wavelength is basically corrected, and is less than the focal depth, and in addition, the distortion is within 1%.
[0053] In summary, the light rays on the object plane are converged after passing through the first lens 1 and exit to the second lens 2, are slightly diverged by the second lens 2 and are incident to the third lens 3 at a suitable angle, the reflected light rays enter the second lens 2 and the first lens 1 in turn, are reflected on the reflecting surface of the first lens 1 and are focused on the intermediate image plane by the first lens 1 and the second lens 2, the intermediate image exits parallel light rays after passing through the second lens group G2, the third lens group G3 and the fourth lens group G4, the intermediate image is formed by the catadioptric way of the first lens group G1, the aperture angle of the subsequent optical path is reduced, the lens size of the optical path is further reduced, and the spherical aberration is corrected, and finally a relatively perfect imaging effect is formed.
[0054] Embodiment two:
[0055] The embodiment provides a wafer detection device, which comprises the wafer detection scattered light collection objective lens described in embodiment one.
[0056] It should be noted that the other parts in the wafer detection scattered light collection objective lens and the wafer detection device provided in the present application can be designed, manufactured and sold respectively, or they can be assembled together and then sold as a whole. Whether the single body formed before the combination or the whole formed after the combination, they all fall within the protection scope of the present application.
[0057] It should be noted that in this paper, the relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment.
[0058] Those of ordinary skill in the art, with the benefit of this disclosure, would understand the specific meaning of the above terms in the context of the present application. When an element is referred to as being "on", "connected to", "mounted to", or "disposed to" another element, it can be directly on, connected to, mounted to, or disposed to the other element or intervening elements can also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements can be present. As used herein, the terms "vertical", "horizontal", "upper", "lower", "left", "right", and similar expressions are intended for purposes of illustration only and are not intended to be limiting.
[0059] Although embodiments of the present application have been shown and described, it would be appreciated by those of ordinary skill in the art that various modifications, alternatives, substitutions, and equivalents can be made to these embodiments without departing from the principles and spirit of the application, the scope of which is defined by the appended claims and their equivalents.
[0060] In the description of the specification, reference to "one embodiment", "an example", "a specific example", or the like means that a particular feature, structure, material, or characteristic being described is included in at least one embodiment or example of the disclosure. The appearances of the above-described terms in various places in the specification are not necessarily referring to the same embodiment or example. Furthermore, the described specific features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.
Claims
1. A wafer inspection scattered light acquisition objective, used for wafer defect detection, characterized in that, The scattered light acquisition lens includes, from the object plane to the image plane along its optical axis, a first lens group (G1), a second lens group (G2), a third lens group (G3), and a fourth lens group (G4), totaling twelve lenses and an aperture stop (8), and all twelve lenses and the aperture stop (8) are coaxially arranged. The first mirror group (G1) is a catadioptric mirror group with positive optical power, used to image the object plane onto the intermediate image plane through two reflections; The first lens group (G1) includes a first lens (1), a second lens (2) and a third lens (3). The first lens (1) is a positive lens, the second lens (2) is a negative lens, and the third lens (3) is a reflecting surface. The third lens (3) is set as a concave surface. The second lens group (G2) includes four lenses with positive power, used to collimate the intermediate image into quasi-parallel light; Among them, the second lens group (G2) includes the fourth lens (4), the fifth lens (5), the sixth lens (6), and the seventh lens (7). The fourth lens (4) is a negative lens, and the fifth lens (5), the sixth lens (6), and the seventh lens (7) are all positive lenses. The third lens group (G3) comprises three lenses with negative optical power, used to adjust the incident height of quasi-parallel rays; Among them, the third lens group (G3) includes the eighth lens (9), the ninth lens (10) and the tenth lens (11). The eighth lens (9) and the tenth lens (11) are negative lenses, and the ninth lens (10) is a positive lens. The fourth lens group (G4) includes two lenses with positive optical power, used to collimate the adjusted light and convert divergent light into collimated light. The fourth lens group (G4) includes the eleventh lens (12) and the twelfth lens (13), with the eleventh lens (12) being a negative lens and the twelfth lens (13) being a positive lens.
2. The wafer inspection scattered light collection objective lens according to claim 1, characterized in that: The first lens (1), the second lens (2) and the third lens (3) are coaxially distributed from the object plane to the image plane along the optical axis.
3. The wafer inspection scattered light collection objective lens according to claim 2, characterized in that: The first lens (1) is a meniscus lens. The first surface of the first lens (1) away from the second lens (2) is a convex surface. The central transmission area is circular, and the central transmission area accounts for less than 10% of the total area of the first surface. The remaining areas are all reflective surfaces. The second surface of the first lens (1) facing the second lens (2) is a plane, a convex surface, or a concave surface, with a large radius of curvature, |R|≥1000; The second lens (2) is a meniscus negative lens, bent towards the object surface. The third lens (3) has a hole in the center area for transmission. The hole in the center area is circular and occupies less than 5% of the total area of the reflecting surface.
4. The wafer inspection scattered light collection objective lens according to claim 2, characterized in that: The second lens group (G2) also includes an aperture stop (8), and the fourth lens (4), the fifth lens (5), the sixth lens (6), the seventh lens (7) and the aperture stop (8) are coaxially distributed from the object plane to the image plane along the optical axis.
5. The wafer inspection scattered light acquisition objective lens according to claim 4, characterized in that: The fourth lens (4) is a meniscus negative lens, bent toward the image plane; the fifth lens (5) is a biconvex positive lens; the sixth lens (6) is set as a plano-convex positive lens, a biconvex positive lens or a meniscus positive lens; The seventh lens (7) is a meniscus positive lens, which is bent toward the image plane. The aperture stop (8) is installed on the side of the seventh lens (7) facing the image plane.
6. The wafer inspection scattered light collection objective lens according to claim 4, characterized in that: The eighth lens (9), the ninth lens (10), and the tenth lens (11) are coaxially distributed from the object plane to the image plane along the optical axis.
7. The wafer inspection scattered light collection objective lens according to claim 6, characterized in that: The eighth lens (9) is configured as a meniscus negative lens, bent toward the image plane; the ninth lens (10) is configured as a biconvex positive lens; and the tenth lens (11) is configured as a meniscus negative lens, bent toward the object plane.
8. The wafer inspection scattered light collection objective lens according to claim 7, characterized in that: The eleventh lens (12) and the twelfth lens (13) are coaxially distributed from the object plane to the image plane along the optical axis.
9. The wafer inspection scattered light collection objective lens according to claim 8, characterized in that: The eleventh lens (12) is configured as a meniscus negative lens, bent toward the image plane, and the twelfth lens (13) is configured as a plano-convex positive lens, a biconvex positive lens, or a meniscus positive lens.
10. A wafer inspection device, characterized in that, The wafer inspection scattered light collection objective lens includes any one of claims 1 to 9.