A telecentric lens for double-side simultaneous equal-optical-path imaging of semiconductor dies

Abstract

The application relates to a telecentric lens for double-side simultaneous equal-optical-path imaging of semiconductor crystal grains, which comprises, in sequence along the light incidence direction, a right-angle turning prism, a cubic beam splitter, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens; the first lens is a double-convex lens, the second lens is a double-convex lens, the third lens is a concave-convex negative lens, the fourth lens is a convex-concave positive lens, the fifth lens is a double-concave lens, the sixth lens is a concave-convex positive lens, and the seventh lens is a double-convex lens, wherein the second lens and the third lens are combined into a cemented lens. The telecentric lens has high resolution, the MTF of the lens is greater than 0.4 in the full field of view when the Nyquist frequency is 100 lp / mm, and the optical distortion is less than 0.2%; therefore, the imaging equipment can greatly improve product quality and production efficiency in large-scale industrial production, machine vision can replace manual vision, the detection of non-contact precision components can be met, and the size and surface defects of products can be accurately measured.

Description

Technical Field

[0001] This invention relates to the field of lens technology, and in particular to a telecentric lens for simultaneous equal optical path imaging on both sides of a semiconductor grain. Background Technology

[0002] Currently, the field of machine vision inspection lacks a high-resolution, low-distortion, -1.5x magnification telecentric lens for inspecting both sides of semiconductor chips. To fill this market gap, a high-resolution, low-distortion machine vision inspection lens is developed through forward-thinking optical design. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a telecentric lens with high resolution and low distortion for simultaneous equal optical path imaging of two sides of a semiconductor grain.

[0004] The present invention is implemented using the following scheme: a telecentric lens for simultaneous equal optical path imaging on both sides of a semiconductor die, characterized in that: it includes a right-angle steering prism, a cubic beam splitter, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged sequentially along the incident direction of light; the first lens is a biconvex lens, the second lens is a biconvex lens, the third lens is a concave-convex negative lens, the fourth lens is a convex-concave positive lens, the fifth lens is a biconcave lens, the sixth lens is a concave-convex positive lens, and the seventh lens is a biconvex lens, wherein the second and third lenses are combined to form a cemented lens.

[0005] Furthermore, the first lens has an object-side radius of curvature of 119.77 mm and an image-side radius of curvature of -74.18 mm; the second lens has an object-side radius of curvature of 70.75 mm and an image-side radius of curvature of -37.69 mm; the third lens has an object-side radius of curvature of -37.69 mm and an image-side radius of curvature of -167.16 mm; the fourth lens has an object-side radius of curvature of 22.92 mm and an image-side radius of curvature of 32.40 mm; the fifth lens has an object-side radius of curvature of -48.26 mm and an image-side radius of curvature of 12.77 mm; the sixth lens has an object-side radius of curvature of -67.30 mm and an image-side radius of curvature of -25.67 mm; and the seventh lens has an object-side radius of curvature of 28.23 mm and an image-side radius of curvature of -227.47 mm.

[0006] Furthermore, there are two right-angle steering prisms: a top-side right-angle steering prism at the same horizontal level as the cubic beam splitter and a side-side right-angle steering prism at the same vertical direction as the cubic beam splitter. Each of the two right-angle steering prisms has a glass micro-light wedge on the side facing the cubic beam splitter. The air gap between the two right-angle steering prisms and the cubic beam splitter is 32.50 mm. The air gap between the cubic beam splitter and the first lens is 0.10 mm. The air gap between the first lens and the second lens is 29.95 mm. The second and third lenses are cemented lenses with an air gap of 0 mm. The air gap between the third and fourth lenses is 29.71 mm. The air gap between the fourth and fifth lenses is 18.14 mm. The air gap between the fifth and sixth lenses is 28.55 mm. The air gap between the sixth and seventh lenses is 12.43 mm.

[0007] Furthermore, the glass refractive index of the right-angle steering prism and the cubic beam splitter is 1.52238, the refractive index of the first lens is 1.57463, the refractive index of the second lens is 1.44101, the refractive index of the third lens is 1.66124, the refractive index of the fourth lens is 1.59885, the refractive index of the fifth lens is 1.66124, the refractive index of the sixth lens is 1.54626, and the refractive index of the seventh lens is 1.54626.

[0008] Furthermore, the glass material of the right-angle steering prism, the glass micro-light wedge, and the cubic beam splitter is H-K9L, the glass material of the first lens is H-ZPK7, the glass material of the second lens is H-FK95N, the glass material of the third lens is ZF1, the glass material of the fourth lens is H-ZPK5, the glass material of the fifth lens is ZF1, the glass material of the sixth lens is H-BAK2, and the glass material of the seventh lens is H-BAK2.

[0009] Furthermore, the outer diameter of the right-angle steering prism is 15mm, the outer diameter of the glass micro-light wedge is 15mm, the outer diameter of the cubic beam splitter is 25mm, the outer diameter of the first lens is 30mm, the outer diameter of the second lens is 26mm, the outer diameter of the third lens is 26mm, the outer diameter of the fourth lens is 16mm, the outer diameter of the fifth lens is 16mm, the outer diameter of the sixth lens is 16mm, and the outer diameter of the seventh lens is 16mm.

[0010] Furthermore, the right-angle steering prism has a thickness of 15mm, the glass micro-light wedge has an angle of 1.5°, and a center thickness of 1mm; the cubic beam splitter has a thickness of 25mm, the first lens has a center thickness of 3.45mm, the second lens has a center thickness of 12.60mm, the third lens has a center thickness of 16.98mm, the fourth lens has a center thickness of 10.29mm, the fifth lens has a center thickness of 3.27mm, the sixth lens has a center thickness of 2.10mm, and the seventh lens has a center thickness of 2.07mm.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] 1. To achieve high lens resolution and a lens MTF greater than 0.4 across the entire field of view at a Nyquist frequency of 100 lp / mm (e.g.) Figure 3 Optical distortion <0.2% (e.g.) Figure 6 This enables imaging equipment to replace human vision in large-scale industrial production, greatly improving product quality and production efficiency, meeting the requirements for non-contact precision component inspection, and accurately measuring product dimensions and surface defects.

[0013] 2. The lens can be adapted to a maximum of 2 / 3" CCD;

[0014] 3. The lens has a focal length of -38.53mm;

[0015] 4. The lens has a resolution of 1080p, providing high-definition images;

[0016] 5. The lens can achieve simultaneous equal optical path imaging on both sides of semiconductor grains.

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below through specific embodiments and related drawings. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the optical path structure of the present invention;

[0019] Figure 2 This is a schematic diagram illustrating the structural principle of the present invention;

[0020] Figure 3 This is a schematic diagram of the MTF performance of the present invention;

[0021] Figure 4 This is a schematic diagram of the defocused MTF performance of the present invention;

[0022] Figure 5 This is a schematic diagram of the relative illumination performance of the present invention;

[0023] Figure 6 This is a schematic diagram illustrating the field curvature and distortion performance of the present invention;

[0024] Figure 7 This is a dot diagram of the present invention;

[0025] Figure 8 This is a schematic diagram of the vertical aberration performance of the present invention;

[0026] The labels in the diagram are as follows: G1. First lens; G2. Second lens; G3. Third lens; G4. Fourth lens; G5. Fifth lens; G6. Sixth lens; G7. Seventh lens; a. Right-angle steering prism; b. Glass micro-light wedge; c. Cubic beam splitter. Detailed Implementation

[0027] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0028] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0029] like Figures 1-8 As shown, a telecentric lens for simultaneous equal optical path imaging on both sides of a semiconductor die is characterized by comprising a right-angle steering prism, a cubic beam splitter, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged sequentially along the incident direction of light; the first lens is a biconvex lens, the second lens is a biconvex lens, the third lens is a concave-convex negative lens, the fourth lens is a convex-concave positive lens, the fifth lens is a biconcave lens, the sixth lens is a concave-convex positive lens, and the seventh lens is a biconvex lens, wherein the second and third lenses are combined to form a cemented lens.

[0030] In this embodiment, the first lens has an object-side radius of curvature of 119.77 mm and an image-side radius of curvature of -74.18 mm; the second lens has an object-side radius of curvature of 70.75 mm and an image-side radius of curvature of -37.69 mm; the third lens has an object-side radius of curvature of -37.69 mm and an image-side radius of curvature of -167.16 mm; the fourth lens has an object-side radius of curvature of 22.92 mm and an image-side radius of curvature of 32.40 mm; the fifth lens has an object-side radius of curvature of -48.26 mm and an image-side radius of curvature of 12.77 mm; the sixth lens has an object-side radius of curvature of -67.30 mm and an image-side radius of curvature of -25.67 mm; and the seventh lens has an object-side radius of curvature of 28.23 mm and an image-side radius of curvature of -227.47 mm.

[0031] In this embodiment, there are two right-angle steering prisms: a top-mounted right-angle steering prism at the same horizontal level as the cubic beam splitter and a side-mounted right-angle rotating prism at the same vertical level as the cubic beam splitter. Each of the two right-angle steering prisms has a glass micro-light wedge on the side facing the cubic beam splitter. The air gap between the two right-angle steering prisms and the cubic beam splitter is 32.50 mm. The air gap between the cubic beam splitter and the first lens is 0.10 mm. The air gap between the first lens and the second lens is 29.95 mm. The second and third lenses are cemented lenses with an air gap of 0 mm. The air gap between the third and fourth lenses is 29.71 mm. The air gap between the fourth and fifth lenses is 18.14 mm. The air gap between the fifth and sixth lenses is 28.55 mm. The air gap between the sixth and seventh lenses is 12.43 mm.

[0032] In this embodiment, the glass refractive index of the right-angle steering prism and the cubic beam splitter is 1.52238, the refractive index of the first lens is 1.57463, the refractive index of the second lens is 1.44101, the refractive index of the third lens is 1.66124, the refractive index of the fourth lens is 1.59885, the refractive index of the fifth lens is 1.66124, the refractive index of the sixth lens is 1.54626, and the refractive index of the seventh lens is 1.54626.

[0033] In this embodiment, the glass materials of the right-angle steering prism, the glass micro-light wedge, and the cubic beam splitter are H-K9L, the glass material of the first lens is H-ZPK7, the glass material of the second lens is H-FK95N, the glass material of the third lens is ZF1, the glass material of the fourth lens is H-ZPK5, the glass material of the fifth lens is ZF1, the glass material of the sixth lens is H-BAK2, and the glass material of the seventh lens is H-BAK2.

[0034] In this embodiment, the outer diameter of the right-angle steering prism is 15mm, the outer diameter of the glass micro-light wedge is 15mm, the outer diameter of the cubic beam splitter is 25mm, the outer diameter of the first lens is 30mm, the outer diameter of the second lens is 26mm, the outer diameter of the third lens is 26mm, the outer diameter of the fourth lens is 16mm, the outer diameter of the fifth lens is 16mm, the outer diameter of the sixth lens is 16mm, and the outer diameter of the seventh lens is 16mm.

[0035] In this embodiment, the thickness of the right-angle steering prism is 15mm, the angle of the glass micro-light wedge is 1.5°, and the center thickness is 1mm; the thickness of the cubic beam splitter is 25mm, the center thickness of the first lens is 3.45mm, the center thickness of the second lens is 12.60mm, the center thickness of the third lens is 16.98mm, the center thickness of the fourth lens is 10.29mm, the center thickness of the fifth lens is 3.27mm, the center thickness of the sixth lens is 2.10mm, and the center thickness of the seventh lens is 2.07mm.

[0036] In this embodiment, the right-angle steering prism, glass micro-light wedge, cubic beam splitter, first lens, second lens, third lens, fourth lens, fifth lens, sixth lens and seventh lens are respectively fixed inside the main lens barrel by locking rings; the glass micro-light wedge with an angle of 1.5° is integrated on the steering prism.

[0037] In this embodiment, a light source and a semiconductor die are also included. The light source is located on the side opposite to the cubic beam splitter and the right-angle turning prism on the top surface. A transparent stage for supporting the semiconductor die is provided below the semiconductor die. The semiconductor die and the right-angle turning prism on the side are at the same horizontal height and are at the same vertical direction as the right-angle turning prism on the top surface.

[0038] In this embodiment, the specific parameters of the optical lens are shown in the table below:

[0039]

[0040] In this embodiment, the focal length of the optical lens is f=-38.53mm; the aperture is F / NO=6.63; and the distance from the outer surface of the right-angle steering prism to the central axis of the imaging plane is 197.3mm. The lens is compatible with a 2 / 3" CCD.

[0041] The performance test curve of this embodiment is as follows: Figure 4-8 Data from multiple tests of this lens clearly shows that its optical distortion is less than 0.2%, and its modulation transfer function (MTF) is greater than 0.4 at 100 lp / mm. Analysis of the MTF and defocus MTF performance curves indicates that the lens can achieve an image acquisition resolution of 1080P, providing high-definition images. The wavelength used in this invention is the visible light wavelength.

[0042] This invention, through complex optical calculations and design, yields the parameters of a telecentric lens for simultaneous imaging of two sides of a semiconductor die. The lens has a magnification of -1.5 and a focal length of -38.53mm, making it compatible with 2 / 3" CCDs. Practical application has proven that the telecentric lens for simultaneous, equal-path imaging of two sides of a semiconductor die, manufactured using this optical design, exhibits high resolution and low distortion (below 0.2%). It can simultaneously and clearly image two adjacent sides of a semiconductor die, meeting the requirements of practical machine vision inspection. This allows machine vision to replace manual vision in large-scale industrial production, significantly improving product quality and production efficiency, and enabling the accurate measurement of product dimensions and surface defects for non-contact precision component inspection.

[0043] Unless otherwise stated, if any of the technical solutions disclosed in this invention specify a numerical range, then the disclosed numerical range is a preferred numerical range. Anyone skilled in the art should understand that the preferred numerical range is merely one among many feasible numerical values ​​that has a more obvious or representative technical effect. Because there are many numerical values, it is impossible to list them all. Therefore, this invention discloses only some numerical values ​​to illustrate the technical solutions of this invention. Furthermore, the numerical values ​​listed above should not constitute a limitation on the scope of protection of this invention.

[0044] If this invention discloses or relates to mutually fixedly connected components or structural parts, then, unless otherwise stated, a fixed connection can be understood as: a detachable fixed connection (e.g., using bolts or screws), or a non-detachable fixed connection (e.g., riveting, welding). Of course, mutually fixed connections can also be replaced by an integral structure (e.g., manufactured in one piece using a casting process) (except where it is obviously impossible to use an integral molding process).

[0045] In addition, unless otherwise stated, the terms used in any of the technical solutions disclosed in this invention to indicate positional relationships or shapes include states or shapes that are similar to, close to, or approximate with those states or shapes.

[0046] Any component provided by this invention can be assembled from multiple individual components or can be a single component manufactured by a one-piece molding process.

[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A telecentric lens for simultaneous equal optical path imaging on both sides of a semiconductor die, characterized in that: It consists of a right-angle steering prism, a cubic beam splitter, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged sequentially along the incident light direction; the first lens is a biconvex lens, the second lens is a biconvex lens, the third lens is a concave-convex negative lens, the fourth lens is a convex-concave positive lens, the fifth lens is a biconcave lens, the sixth lens is a concave-convex positive lens, and the seventh lens is a biconvex lens, wherein the second and third lenses are combined to form a cemented lens; the first lens has an object-side radius of curvature of 119.77 mm and an image-side radius of curvature of -74.18 mm; the second lens has an object-side radius of curvature of 7 mm. The first lens has an object side radius of curvature of 0.75mm and an image side radius of curvature of -37.69mm; the second lens has an object side radius of curvature of -37.69mm and an image side radius of curvature of -167.16mm; the third lens has an object side radius of curvature of 22.92mm and an image side radius of curvature of 32.40mm; the fourth lens has an object side radius of curvature of -48.26mm and an image side radius of curvature of 12.77mm; the fifth lens has an object side radius of curvature of -67.30mm and an image side radius of curvature of -25.67mm; and the sixth lens has an object side radius of curvature of 28.23mm and an image side radius of curvature of -227.47mm.

2. The telecentric lens for simultaneous equal optical path imaging on both sides of a semiconductor grain according to claim 1, characterized in that: There are two right-angle steering prisms: a top-side right-angle steering prism at the same horizontal level as the cubic beam splitter and a side-side right-angle image-turning prism at the same vertical direction as the cubic beam splitter. Each of the two right-angle steering prisms has a glass micro-light wedge on the side facing the cubic beam splitter. The air gap between the two right-angle steering prisms and the cubic beam splitter is 32.50 mm. The air gap between the cubic beam splitter and the first lens is 0.10 mm. The air gap between the first and second lenses is 29.95 mm. The second and third lenses are cemented lenses with an air gap of 0 mm. The air gap between the third and fourth lenses is 29.71 mm. The air gap between the fourth and fifth lenses is 18.14 mm. The air gap between the fifth and sixth lenses is 28.55 mm. The air gap between the sixth and seventh lenses is 12.43 mm.

3. The telecentric lens for simultaneous equal optical path imaging of two sides of a semiconductor grain according to claim 2, characterized in that: The glass refractive index of the right-angle steering prism and the cubic beam splitter is 1.52238. The refractive index of the first lens is 1.57463, the refractive index of the second lens is 1.44101, the refractive index of the third lens is 1.66124, the refractive index of the fourth lens is 1.59885, the refractive index of the fifth lens is 1.66124, the refractive index of the sixth lens is 1.54626, and the refractive index of the seventh lens is 1.54626.

4. The telecentric lens for simultaneous equal optical path imaging of two sides of a semiconductor grain according to claim 2, characterized in that: The glass material of the right-angle steering prism, the glass micro-light wedge, and the cubic beam splitter is H-K9L. The glass material of the first lens is H-ZPK7, the glass material of the second lens is H-FK95N, the glass material of the third lens is ZF1, the glass material of the fourth lens is H-ZPK5, the glass material of the fifth lens is ZF1, the glass material of the sixth lens is H-BAK2, and the glass material of the seventh lens is H-BAK2.

5. The telecentric lens for simultaneous equal optical path imaging of two sides of a semiconductor grain according to claim 2, characterized in that: The outer diameter of the right-angle steering prism is 15mm, the outer diameter of the glass micro-light wedge is 15mm, the outer diameter of the cubic beam splitter is 25mm, the outer diameter of the first lens is 30mm, the outer diameter of the second lens is 26mm, the outer diameter of the third lens is 26mm, the outer diameter of the fourth lens is 16mm, the outer diameter of the fifth lens is 16mm, the outer diameter of the sixth lens is 16mm, and the outer diameter of the seventh lens is 16mm.

6. The telecentric lens for simultaneous equal optical path imaging of two sides of a semiconductor grain according to claim 2, characterized in that: The right-angle steering prism has a thickness of 15mm, the glass micro-light wedge has an angle of 1.5°, and a center thickness of 1mm; the cubic beam splitter has a thickness of 25mm, the first lens has a center thickness of 3.45mm, the second lens has a center thickness of 12.60mm, the third lens has a center thickness of 16.98mm, the fourth lens has a center thickness of 10.29mm, the fifth lens has a center thickness of 3.27mm, the sixth lens has a center thickness of 2.10mm, and the seventh lens has a center thickness of 2.07mm.

Images