Objective lens for wafer surface defect detection

Abstract

The present invention provides an objective lens for wafer surface defect detection, comprising a first lens group, a second lens group, a third lens group and a fourth lens group, wherein the first lens group comprises a first lens, a second lens, a third lens and a fourth lens arranged in sequence according to the incident direction of light, and the optical focal powers of the lenses in the first lens group are: the optical focal power of the first lens is positive, the optical focal power of the second lens is negative, the optical focal power of the third lens is negative, and the optical focal power of the fourth lens is negative, and the optical focal power presented by the first lens group as a whole is negative. In the present application, the optical focal powers of the four lens groups are respectively negative, positive, positive and positive, and each lens group is composed of a plurality of lenses, so that when the light passes through the interface of different media, the light will be refracted, that is, the propagation direction of the light changes. The objective lens uses the principle of refraction to change the propagation direction of the light through the curvature of the lens to achieve focusing or divergence.

Description

Technical Field

[0001] The invention relates to the technical field of optical system design in semiconductor device processing and testing equipment, and in particular to an objective lens for wafer surface defect detection. Background Art

[0002] Semiconductor wafer defect detection refers to the process of detecting physical defects (such as particles, scratches, protrusions, etc.) and pattern defects (such as broken lines and short circuits in circuit patterns) on the surface of the wafer during the semiconductor manufacturing process. As the feature size of integrated circuits continues to shrink, the requirements for the resolution of the detection system are also increasing.

[0003] At present, the characteristics of semiconductor devices have reached the nanometer level, and the detection must be able to detect extremely small anomalies, which requires extremely high precision and resolution. Therefore, how to improve the resolution of the objective lens is an urgent problem to be solved.

[0004] A Chinese patent document discloses "an imaging objective lens", and its publication number is CN 117991481A. The patent document can effectively disperse the configuration of the positive refractive power in the objective lens by reasonably configuring the refractive power of the four lenses in the imaging objective lens, so that the third lens and the fourth lens with convex and concave shapes cooperate with each other, which can effectively reduce the overall sensitivity of the objective lens. However, the resolution of the objective lens in this patent is not high and is not suitable for defect detection of semiconductor wafers. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide an objective lens for wafer surface defect detection, so as to solve the problem that the existing objective lens has low resolution and is not suitable for defect detection of semiconductor wafers.

[0006] To achieve the above-mentioned purpose and other related purposes, the present invention provides an objective lens for wafer surface defect detection, comprising a first lens group, a second lens group, a third lens group and a fourth lens group, wherein the first lens group comprises a first lens, a second lens, a third lens and a fourth lens arranged in sequence according to the incident direction of light, the optical power of each lens in the first lens group is as follows: the optical power of the first lens is positive, the optical power of the second lens is negative, the optical power of the third lens is negative, and the optical power of the fourth lens is negative, and the optical power presented by the first lens group as a whole is negative;

[0007] The second lens group includes a fifth lens, a sixth lens and a seventh lens arranged in sequence according to the incident direction of light, the optical power of each lens in the second lens group is as follows: the optical power of the fifth lens is positive, the optical power of the sixth lens is positive, and the optical power of the seventh lens is positive, and the optical power of the second lens group as a whole is positive;

[0008] The third lens group includes an eighth lens, a ninth lens, a tenth lens and an eleventh lens arranged in sequence according to the incident direction of light, and the focal powers of the lenses in the third lens group are as follows: the focal power of the eighth lens is negative, the focal power of the ninth lens is positive, the focal power of the tenth lens is positive, and the focal power of the eleventh lens is positive, and the focal power of the third lens group as a whole is positive;

[0009] The fourth lens group includes a twelfth lens, a thirteenth lens, a fourteenth lens and a fifteenth lens arranged in sequence according to the incident direction of light, the focal powers of the lenses in the fourth lens group are as follows: the focal power of the twelfth lens is positive, the focal power of the thirteenth lens is positive, the focal power of the fourteenth lens is positive, and the focal power of the fifteenth lens is positive, and the aperture is located behind the twelfth lens;

[0010] The first lens group is used to receive light emitted by the light source and refract the light to the second lens group, the second lens group is used to collect light emitted from the first lens group and refract the collected light to the third lens group, the third lens group is used to collect light emitted from the second lens group and refract the collected light to the fourth lens group, the fourth lens group is used to focus the light on the wafer surface, and the lenses in the objective lens are on the same optical axis.

[0011] In the above technical solution of the present application, when the optical focal length is positive, it indicates that a convergence effect is produced on the incident light, and when the optical focal length is negative, it indicates that a divergence effect is produced on the incident light. The objective lens includes a first lens group with negative optical power, a second lens group with positive optical power, a third lens group with positive optical power, and a fourth lens group with positive optical power. The first lens group includes four lenses with optical powers of positive, negative, negative, and negative, respectively; the second lens group includes three lenses with optical powers of positive, positive, and positive, respectively; the third lens group includes four lenses with optical powers of negative, positive, positive, and positive, respectively; the fourth lens group includes four lenses with optical powers of positive, positive, positive, and positive, respectively; the first lens group is responsible for receiving the light source and refracting the light source to the second lens group, the second lens group collects the light emitted from the first lens group and refracts the collected light to the third lens group, the third lens group collects the light emitted from the second lens group and refracts the collected light to the fourth lens group, the fourth lens group focuses the light on the wafer, and the lenses in the objective lens are all on the same optical axis.

[0012] The aperture stop is a stop in an optical system that limits the solid angle (cone angle) of the imaging beam of the object point on the axis, also known as the effective stop; the aperture stop forms an entrance pupil by imaging the object space through the lens in front of it, and forms an exit pupil by imaging the image space through the lens behind it. The two are conjugate in the optical system. By setting the stop behind the twelfth lens, it is more advantageous for correcting aberrations. The objective lens provided in the present application is composed of four lens groups, and the four lens groups have negative, positive, positive, and positive focal powers respectively. Each lens group is composed of multiple lenses. When the light passes through the interface of different media, refraction occurs, that is, the propagation direction of the light changes. The objective lens uses the principle of refraction to change the propagation direction of the light through the curvature of the lens to achieve focusing or divergence. In the complex optical system constituted by the above technical solution of the present application, aberrations are corrected by using a combination of positive and negative focal powers. The above combination can help balance the optical performance of the system, such as spherical aberration, chromatic aberration, etc. The objective lens provided in this application can correct various aberrations, especially distortion, field curvature, astigmatism, axial chromatic aberration, and magnification chromatic aberration. It has high precision and resolution, with an NA of 0.83 and a theoretical resolution of σ=0.192μm. In the field of wafer inspection, it is a high-resolution objective lens that can detect extremely small abnormalities.

[0013] Preferably, the magnification β of the objective lens is -0.025x.

[0014] Preferably, the first lens group is used to receive light emitted by a light source through a tube lens with a focal length of 260 mm.

[0015] Preferably, the bandwidth of the objective lens is 260.68~261.32nm, the numerical aperture NA is 0.83, the object field of view Φ is 0.5mm, the theoretical resolution σ is 0.192μm, and each lens included in the objective lens is coated with an anti-reflection film of the bandwidth, and the anti-reflection film can improve the transmittance of the lens.

[0016] Preferably, the first lens is a biconvex lens, the second lens is a meniscus lens facing the wafer, the third lens is a biconcave lens, and the fourth lens is a biconcave lens.

[0017] Preferably, the fifth lens is a meniscus lens facing the light source, the sixth lens is a meniscus lens facing the light source, and the seventh lens is a meniscus lens facing the light source.

[0018] Preferably, the eighth lens is a meniscus lens facing the wafer, the ninth lens is a biconvex lens, the tenth lens is a meniscus lens facing the wafer, and the eleventh lens is a meniscus lens facing the wafer.

[0019] Preferably, the twelfth lens is a meniscus lens facing the wafer, the thirteenth lens is a meniscus lens facing the light source, the fourteenth lens is a meniscus lens facing the wafer, and the fifteenth lens is a meniscus lens facing the wafer.

[0020] The concave and convex of the lens is determined by the curvature of the lens; in the above technical solution, the present application sets different curvatures for each lens in order to achieve an optimized design of the optical system, correct aberrations, and improve imaging quality.

[0021] Preferably, the refractive index of the first lens is 1.40-1.47, the refractive index of the second lens is 1.41-1.50, the refractive index of the third lens is 1.42-1.47, and the refractive index of the fourth lens is 1.43-1.48.

[0022] Preferably, the refractive index of the fifth lens is 1.42-1.50, the refractive index of the sixth lens is 1.45-1.49, and the refractive index of the seventh lens is 1.44-1.50.

[0023] Preferably, the refractive index of the eighth lens is 1.39-1.52, the refractive index of the ninth lens is 1.41-1.48, the refractive index of the tenth lens is 1.42-1.47, and the refractive index of the eleventh lens is 1.41-1.52.

[0024] Preferably, the refractive index of the twelfth lens is 1.44-1.53, the refractive index of the thirteenth lens is 1.45-1.49, the refractive index of the fourteenth lens is 1.40-1.48, and the refractive index of the fifteenth lens is 1.45-1.49.

[0025] Preferably, the Abbe number of the first lens is 48.5-69.2, the Abbe number of the second lens is 50.2-69.7, the Abbe number of the third lens is 64.9-68.5, and the Abbe number of the fourth lens is 65.6-69.4.

[0026] Preferably, the Abbe number of the fifth lens is 58.4-67.9, the Abbe number of the sixth lens is 46.9-68.4, and the Abbe number of the seventh lens is 58.8-68.4.

[0027] Preferably, the Abbe number of the eighth lens is 59.9-69.1, the Abbe number of the ninth lens is 63.8-69.5, the Abbe number of the tenth lens is 60.8-67.9, and the Abbe number of the eleventh lens is 63.5-69.1.

[0028] Preferably, the Abbe number of the twelfth lens is 59.9-67.9, the Abbe number of the thirteenth lens is 65.2-68.1, the Abbe number of the fourteenth lens is 60.3-69.2, and the Abbe number of the fifteenth lens is 63.5-68.5.

[0029] Preferably, the lens in the objective lens satisfies the following relationship:

[0030] 0.49 <f / epd<0.6,

[0031] 0.2 <bfl / f<0.3,

[0032] 0.55 <fno<0.61,

[0033] ttl<120mm,

[0034] 2.1° <fov<2.3°,

[0035] Among them, f is the focal length of the objective lens, epd is the entrance pupil diameter, bfl is the distance between the vertex of the back surface of the last lens and the wafer, fno is the aperture number of the objective lens, ttl is the distance from the object side of the first lens of the first lens group to the image plane of the objective lens, and fov is the maximum half field of view angle range of the objective lens.

[0036] As described above, the objective lens for wafer surface defect detection of the present invention has the following beneficial effects:

[0037] (1) In this application, four lens groups are arranged with negative, positive, positive, and positive focal powers respectively, and each lens group is composed of multiple lenses. When light passes through the interface of different media, refraction occurs, that is, the propagation direction of the light changes. The objective lens uses the principle of refraction to change the propagation direction of light through the curvature of the lens to achieve focusing or divergence;

[0038] (2) By adopting a combination of positive and negative optical power lenses to correct aberrations, the above combination can help balance the optical performance of the system, such as spherical aberration, chromatic aberration, etc.; the objective lens provided in this application can correct a variety of aberrations, especially distortion, field curvature, astigmatism, axial chromatic aberration, and magnification chromatic aberration, and has high precision and resolution. The NA reaches 0.83 and the theoretical resolution is σ=0.192μm. In the field of wafer inspection, it is a high-resolution objective lens that can detect extremely small abnormalities. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Shown is a schematic diagram of the structure of an objective lens used for wafer surface defect detection.

[0040] Figure 2 Shown is the theoretical MTF curve of an objective lens used for wafer surface defect inspection.

[0041] Figure 3 Shown are the theoretical field curvature (left) and F-tan (Theta) distortion curves (right) of an objective lens used for wafer surface defect inspection.

[0042] Description of reference numerals: first lens group G1, second lens group G2, third lens group G3, fourth lens group G4, first lens L1, second lens L2, third lens L3, fourth lens L4, fifth lens L5, sixth lens L6, seventh lens L7, eighth lens L8, ninth lens L9, tenth lens L10, eleventh lens L11, twelfth lens L12, thirteenth lens L13, fourteenth lens L14, fifteenth lens L15. DETAILED DESCRIPTION

[0043] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] In the description of the present application, it should be noted that the terms "upper", "lower", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0045] Unless otherwise clearly specified and limited, the terms "connection", "fixation" and "setting" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, an indirect connection through an intermediate medium, or a connection between two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0046] like Figure 1As shown, the embodiment of the present application provides an objective lens for wafer surface defect detection, including a first lens group G1, a second lens group G2, a third lens group G3 and a fourth lens group G4, the first lens group includes a first lens L1, a second lens L2, a third lens L3 and a fourth lens L4 arranged in sequence according to the incident direction of light, the optical power of each lens in the first lens group is as follows: the optical power of the first lens is positive, the optical power of the second lens is negative, the optical power of the third lens is negative, and the optical power of the fourth lens is negative, and the optical power of the first lens group as a whole is negative;

[0047] The second lens group G2 includes a fifth lens L5, a sixth lens L6 and a seventh lens L7 arranged in sequence according to the incident direction of light, and the optical power of each lens in the second lens group is as follows: the optical power of the fifth lens is positive, the optical power of the sixth lens is positive, and the optical power of the seventh lens is positive, and the optical power of the second lens group as a whole is positive;

[0048] The third lens group G3 includes an eighth lens L8, a ninth lens L9, a tenth lens L10 and an eleventh lens L11 which are arranged in sequence according to the incident direction of light. The focal powers of the lenses in the third lens group are as follows: the focal power of the eighth lens is negative, the focal power of the ninth lens is positive, the focal power of the tenth lens is positive, and the focal power of the eleventh lens is positive. The focal power of the third lens group as a whole is positive.

[0049] The fourth lens group G4 includes a twelfth lens L12, a thirteenth lens L13, a fourteenth lens L14 and a fifteenth lens L15 arranged in sequence according to the incident direction of light, the focal powers of the lenses in the fourth lens group are as follows: the focal power of the twelfth lens is positive, the focal power of the thirteenth lens is positive, the focal power of the fourteenth lens is positive, and the focal power of the fifteenth lens is positive, and the aperture is located behind the twelfth lens;

[0050] The first lens group G1 is used to receive light emitted by the light source and refract the light to the second lens group G2. The second lens group G2 is used to collect light emitted from the first lens group and refract the collected light to the third lens group G3. The third lens group G3 is used to collect light emitted from the second lens group G2 and refract the collected light to the fourth lens group G4. The fourth lens group G4 is used to focus the light on the wafer surface. The lenses in the objective lens are on the same optical axis.

[0051] The magnification β of the objective lens is -0.025x, that is, it is reduced by 40 times; the first lens group is used to receive the light emitted by the light source through the tube lens with a focal length of 260mm.

[0052] The bandwidth of the objective lens is 260.68~261.32nm, the material is fused quartz, the numerical aperture NA is 0.83, the object field of view Φ is 0.5mm, the theoretical resolution σ is 0.192μm, and each lens included in the objective lens is coated with an anti-reflection film of the bandwidth.

[0053] In a specific implementation, the first lens L1 of the first lens group G1 is a biconvex lens, the second lens L2 is a meniscus lens facing the wafer, the third lens L3 is a biconcave lens, and the fourth lens L4 is a biconcave lens.

[0054] In a specific implementation, the fifth lens L5 in the second lens group G2 is a meniscus lens facing the light source, the sixth lens L6 is a meniscus lens facing the light source, and the seventh lens L7 is a meniscus lens facing the light source.

[0055] In a specific implementation, the eighth lens L8 of the third lens group G3 is a meniscus lens facing the wafer, the ninth lens L9 is a biconvex lens, the tenth lens L10 is a meniscus lens facing the wafer, and the eleventh lens L11 is a meniscus lens facing the wafer.

[0056] In a specific implementation, the twelfth lens L12 of the fourth lens group G4 is a meniscus lens facing the wafer, the thirteenth lens L13 is a meniscus lens facing the light source, the fourteenth lens L14 is a meniscus lens facing the wafer, and the fifteenth lens L15 is a meniscus lens facing the wafer.

[0057] In a specific embodiment, each lens satisfies the following relationship:

[0058] 1.40 <n11<1.47,

[0059] 1.41 <n12<1.50,

[0060] 1.42 <n13<1.47,

[0061] 1.43 <n14<1.48,

[0062] 1.42 <n21<1.50,

[0063] 1.45 <n22<1.49,

[0064] 1.44 <n23<1.50,

[0065] 1.39 <n31<1.52,

[0066] 1.41 <n32<1.48,

[0067] 1.42 <n33<1.47,

[0068] 1.41 <n34<1.52,

[0069] 1.44 <n41<1.53,

[0070] 1.45 <n42<1.49,

[0071] 1.40 <n43<1.48,

[0072] 1.45 <n44<1.49,

[0073] wherein, n11 is the refractive index of the first lens L1, n12 is the refractive index of the second lens L2, n13 is the refractive index of the third lens L3, n14 is the refractive index of the fourth lens L4, n21 is the refractive index of the first lens L5, n22 is the refractive index of the second lens L6, n23 is the refractive index of the third lens L7, n31 is the refractive index of the eighth lens L8, n32 is the refractive index of the ninth lens L9, n33 is the refractive index of the tenth lens L10, n34 is the refractive index of the eleventh lens L11, n41 is the refractive index of the twelfth lens L12, n42 is the refractive index of the thirteenth lens L13, n43 is the refractive index of the fourteenth lens L14, and n44 is the refractive index of the fifteenth lens L15.

[0074] In a specific embodiment, each lens satisfies the following relationship:

[0075] 48.5 <v11<69.2,

[0076] 50.2 <v12<69.7,

[0077] 64.9 <v13<68.5,

[0078] 65.6 <v14<69.4,

[0079] 58.4 <v21<67.9,

[0080] 46.9 <v22<68.4,

[0081] 58.8 <v23<68.4,

[0082] 59.9 <v31<69.1,

[0083] 63.8 <v32<69.5,

[0084] 60.8 <v33<67.9,

[0085] 63.5 <v34<69.1,

[0086] 59.9 <v41<67.9,

[0087] 65.2 <v42<68.1,

[0088] 60.3 <v43<69.2,

[0089] 63.5 <v44<68.5,

[0090] wherein, v11 is the Abbe number of the first lens L1, v12 is the Abbe number of the second lens L2, v13 is the Abbe number of the third lens L3, v14 is the Abbe number of the fourth lens L4, v21 is the Abbe number of the fifth lens L5, v22 is the Abbe number of the sixth lens L6, v23 is the Abbe number of the seventh lens L7, v31 is the Abbe number of the eighth lens L8, v32 is the Abbe number of the ninth lens L9, v33 is the Abbe number of the tenth lens L10, v34 is the Abbe number of the eleventh lens L11, v41 is the Abbe number of the twelfth lens L12, v42 is the Abbe number of the thirteenth lens L13, v43 is the Abbe number of the fourteenth lens L14, and v44 is the Abbe number of the fifteenth lens L15.

[0091] In a specific embodiment, each lens satisfies the following relationship:

[0092] 0.49 <f / epd<0.6,

[0093] 0.2 <bfl / f<0.3,

[0094] 0.55 <fno<0.61,

[0095] ttl<120mm,

[0096] 2.1° <fov<2.3°,

[0097] Among them, f is the focal length of the objective lens, epd is the entrance pupil diameter; bfl is the distance between the back surface vertex (close to the wafer direction) of the last lens L15 and the wafer; fno is the aperture number of the objective lens; ttl is the distance from the object side surface of the first lens L1 of the first lens group G1 to the image plane of the objective lens (wafer direction); fov is the maximum half field of view angle range of the objective lens.

[0098] In the embodiment of the present application, the image-side numerical aperture NA of the lens is 0.83. According to the formula σ=(Kλ) / NA, K is taken as 0.61, and the theoretical resolution σ of the lens can reach 0.192μm (K is the process coefficient factor).

[0099] During assembly, the air gap between lenses and the thickness of the lenses need to be fine-tuned to adjust the image quality deviation caused by surface processing and ensure that the imaging quality of the objective lens is optimal.

[0100] In this embodiment, all lenses in the objective lens used for wafer surface defect detection are made of fused quartz (SILICA), and their specific parameters are shown in Table 1.

[0101] Table 1. Parameters of the defect detection objective lens in this embodiment

[0102]

[0103] It can be seen from Table 1 that after implementing this embodiment according to the above scheme, the image quality of the objective lens is relatively close to the theoretical calculation result.

[0104] like Figure 2 As shown, the theoretical MTF curve of the objective lens obtained through simulation analysis with the software ZEMAX is close to the diffraction limit.

[0105] like Figure 3 As shown, the theoretical field curvature (left) and F-tan (Theta) distortion curve (right) of the objective lens are obtained through simulation analysis using the software ZEMAX. Among them, the meridian field curvature of the objective lens is less than 0.1μm, the sagittal field curvature is less than 0.1μm, and the maximum distortion is about 0.0288%.

[0106] The above specific implementation methods and results are not the best embodiment of the performance of the present invention, but all evaluation indicators have reached the design expectations.

[0107] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. An objective lens for wafer surface defect detection, characterized in that: The invention comprises a first lens group, a second lens group, a third lens group and a fourth lens group, wherein the first lens group comprises a first lens, a second lens, a third lens and a fourth lens arranged in sequence according to the incident direction of light, and the focal powers of the lenses in the first lens group are as follows: the focal power of the first lens is positive, the focal power of the second lens is negative, the focal power of the third lens is negative, and the focal power of the fourth lens is negative, and the focal power of the first lens group as a whole is negative; The second lens group includes a fifth lens, a sixth lens and a seventh lens arranged in sequence according to the incident direction of light, the optical power of each lens in the second lens group is as follows: the optical power of the fifth lens is positive, the optical power of the sixth lens is positive, and the optical power of the seventh lens is positive, and the optical power of the second lens group as a whole is positive; The third lens group includes an eighth lens, a ninth lens, a tenth lens and an eleventh lens arranged in sequence according to the incident direction of light, and the focal powers of the lenses in the third lens group are as follows: the focal power of the eighth lens is negative, the focal power of the ninth lens is positive, the focal power of the tenth lens is positive, and the focal power of the eleventh lens is positive, and the focal power of the third lens group as a whole is positive; The fourth lens group includes a twelfth lens, a thirteenth lens, a fourteenth lens and a fifteenth lens arranged in sequence according to the incident direction of light, the focal powers of the lenses in the fourth lens group are as follows: the focal power of the twelfth lens is positive, the focal power of the thirteenth lens is positive, the focal power of the fourteenth lens is positive, and the focal power of the fifteenth lens is positive, and the aperture is located behind the twelfth lens; The first lens group is used to receive light emitted by the light source and refract the light to the second lens group, the second lens group is used to collect light emitted from the first lens group and refract the collected light to the third lens group, the third lens group is used to collect light emitted from the second lens group and refract the collected light to the fourth lens group, the fourth lens group is used to focus the light on the wafer surface, and the lenses in the objective lens are on the same optical axis; The bandwidth of the objective lens is 260.68~261.32nm, the numerical aperture NA is 0.83, the object field of view Φ is 0.5mm, the theoretical resolution σ is 0.192μm, and each lens included in the objective lens is coated with an anti-reflection film of the bandwidth.

2. The objective lens for wafer surface defect detection according to claim 1, characterized in that: The magnification β of the objective lens is -0.025x; the first lens group is used to receive the light emitted by the light source through the tube lens with a focal length of 260mm.

3. The objective lens for wafer surface defect detection according to claim 1, characterized in that: The first lens is a biconvex lens, the second lens is a meniscus lens facing the wafer, the third lens is a biconcave lens, and the fourth lens is a biconcave lens.

4. The objective lens for wafer surface defect detection according to claim 1, characterized in that: The fifth lens is a meniscus lens facing the light source, the sixth lens is a meniscus lens facing the light source, and the seventh lens is a meniscus lens facing the light source.

5. The objective lens for wafer surface defect detection according to claim 1, characterized in that: The eighth lens is a meniscus lens facing the wafer, the ninth lens is a biconvex lens, the tenth lens is a meniscus lens facing the wafer, and the eleventh lens is a meniscus lens facing the wafer.

6. The objective lens for wafer surface defect detection according to claim 1, characterized in that: The twelfth lens is a meniscus lens facing the wafer, the thirteenth lens is a meniscus lens facing the light source, the fourteenth lens is a meniscus lens facing the wafer, and the fifteenth lens is a meniscus lens facing the wafer.

7. The objective lens for wafer surface defect detection according to claim 1, characterized in that: The refractive index of the first lens is 1.40-1.47, the refractive index of the second lens is 1.41-1.50, the refractive index of the third lens is 1.42-1.47, the refractive index of the fourth lens is 1.43-1.48, the refractive index of the fifth lens is 1.42-1.50), the refractive index of the sixth lens is 1.45-1.49, the refractive index of the seventh lens is 1.44-1.50, the refractive index of the eighth lens is 1.39-1.52, the refractive index of the ninth lens is 1.41-1.48, the refractive index of the tenth lens is 1.42-1.47, the refractive index of the eleventh lens is 1.41-1.52, the refractive index of the twelfth lens is 1.44-1.53, the refractive index of the thirteenth lens is 1.45-1.49, the refractive index of the fourteenth lens is 1.40-1.48, and the refractive index of the fifteenth lens is 1.45-1.

49.

8. The objective lens for wafer surface defect detection according to claim 1, characterized in that: The Abbe number of the first lens is 48.5-69.2, the Abbe number of the second lens is 50.2-69.7, the Abbe number of the third lens is 64.9-68.5, the Abbe number of the fourth lens is 65.6-69.4, the Abbe number of the fifth lens is 58.4-67.9, the Abbe number of the sixth lens is 46.9-68.4, the Abbe number of the seventh lens is 58.8-68.4, and the Abbe number of the eighth lens is 59. .9~69.1, the Abbe number of the ninth lens is 63.8~69.5, the Abbe number of the tenth lens is 60.8~67.9, the Abbe number of the eleventh lens is 63.5~69.1, the Abbe number of the twelfth lens is 59.9~67.9, the Abbe number of the thirteenth lens is 65.2~68.1, the Abbe number of the fourteenth lens is 60.3~69.2, and the Abbe number of the fifteenth lens is 63.5~68.

5.

9. The objective lens for wafer surface defect detection according to claim 1, characterized in that: The lens in the objective lens satisfies the following relationship: 0.49 <f / epd<0.6, 0.2 <bfl / f<0.3, ttl<120mm, 2.1° <fov<2.3°, Among them, f is the focal length of the objective lens, epd is the entrance pupil diameter, bfl is the distance between the vertex of the back surface of the last lens and the wafer, ttl is the distance from the object side of the first lens of the first lens group to the image plane of the objective lens, and fov is the maximum half field of view angle range of the objective lens.

Images