KR970007978B1 - Anamorphic lens of c.c.d. camera - Google Patents

Abstract

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Description

Anamorphic Lens for C.C.D Camera

1 is a state diagram showing the size of the chip to be measured.

2 is a structural diagram of an anamorphic imaging optical system to which the present invention is applied.

(A) is a schematic cross-sectional view of a lens having a focal length of 200 mm and having a 1: 1 magnification by symmetrically arranging five lenses.

(B) is a schematic sectional view in which the apocal cylinder optical system is inserted in the middle of an optical system, and only the imaging magnification of the horizontal direction is reduced by 0.25 times.

(C) is the optical path diagram for the horizontal imaging state that the size of 25mm is reduced 0.25 times to 6.26mm.

(D) is a state diagram of the phase of image formation on the axis of Fig. 2 (C).

(E) (b) is an optical path diagram in which a 1: 1 imaging is performed without changing the magnification by a cylinder optical system in which the vertical imaging state is arranged in the middle.

3 is an image forming structure using conventional C.C.D.

(A) In the state that it was formed into C.C.D in the state that used a general lens.

(B) is a structural diagram of an optical system formed by using an ordinary lens and four mirrors.

(C) is the state that was formed in Mr. C.D of Figure 4 (b).

4 is a mine aberration road of the anamorphic optical system of the present invention,

(A) is the ray aberration diagram in the longitudinal direction.

(B) is the ray aberration diagram in the transverse direction.

* Explanation of symbols for main parts of the drawings

100 spherical lens system 101 first lens

102: second lens 103: interval

200: apocal cylinder lens system 300: anamorphic lens system

400: C.C.D

The present invention relates to an anamorphic lens (ANAMORPHICLENS) for the CCD CAMERA of the semiconductor inspection equipment, more specifically, when the aspect ratio of the inspection object does not match the aspect ratio of the C.C.D. It relates to a C.C.D camera lens having an imaging ratio of 0.25 times in the horizontal direction and one imaging magnification in the vertical direction.

The industrial field of use of the present invention is an optical system used for equipment that distinguishes good and bad by measuring with a limit of about 0.01 mm whether the height of the legs of a semiconductor parent is evenly manufactured.

More specifically, the optical system is applied to a lens system in which 5 × 25mm semiconductor parent is imaged differently in the horizontal and vertical imaging magnifications so that it can be observed in 6.6 × 8.8mm C.C.D.

When the semiconductor chip is manufactured by a predetermined manufacturing method, the product is inspected to cover good and bad products during the inspection process. An inspection of whether the height of the legs of the semiconductor chip is made evenly is included in the inspection item.

In the above inspection of the height of the legs of the semiconductor parent, in order to completely form a 5 × 25mm semiconductor chip in the 6.6 × 8.8mm standard C.C.D by using a general lens system, the imaging size is 0.3 as the characteristic of the lens. It is necessary to reduce the size so that it can be imaged to the standard of C.C.D. In this case, the size of the image determined by the reduction is about 1.5 × 7.5mm.

If C.C.D is used in the inspection process as described above, only 109 pixels corresponding to 1.5mm out of 480 pixels of 6.6mm in the horizontal direction of C.C.D. Due to the small image size, the measurement error of the measurer is inevitably increased.

In order to eliminate the measurement error, the use of C.C.D in expensive tombs can double the imaging performance, which reduces the measurement error. Since the number of Pixels is about twice, the purchase price is about 10 times higher than that of general C.C.D.

Therefore, the use of high resolution C.C.D., which is expensive, is inefficient in measuring equipment, so to obtain this point economically, as shown in (b) of FIG. 4, the general lens system R and four mirrors (M1, M2, M3, M4) Provided a measuring device for inspecting semiconductor chips using general C.C.D.

At this time, the M2 and M3 mirrors with reflection function were inclined at 45 °, tilted slightly vertically and horizontally, and the subjects passing through the ordinary lens R formed an image of C.C.D.

However, the conventional measuring means using the reflector has a complicated internal structure of the optical system, which makes it difficult to manufacture, and it is troublesome to adjust the focus by realigning the optical system easily even with a small impact.

To solve this problem, the configuration of five lens systems for correcting aberration at 1: 1 magnification and infinite focal cylinder optical system with different magnifications in the vertical and horizontal directions are required. Specific arrangements are required to obtain.

An object of the present invention is to provide a configuration in which a spherical lens system having a focal length is opposed to each other, and a cylinder lens system having an infinite focal distance is installed between these spherical lens systems so that magnification of an image forming state is different from each other in the vertical and horizontal directions. For the purpose.

Another object of the present invention is that the magnification in the vertical direction is 1: 1, and only the magnification in the horizontal direction is reduced by 0.25 times.

Next, the Example about this invention is described in detail.

The present invention is explained in detail in the configuration shown in Figs.

1 is a state diagram showing the size of a chip to be measured, and FIG. 2 is a structural diagram of an anamorphic imaging optical system to which the present invention is applied. As a schematic cross-sectional view of the state made of, the second lens 102 made of the same lens group at the position facing the first lens 101 is provided so as to be maintained on the coaxial line.

In this case, the first and second lenses 101 and 102 are installed to maintain a constant gap 103.

It can be seen that a predetermined interval 103 is formed between these first and second lenses 101 and 102.

FIG. 2B is a structure in which each magnification in the vertical and horizontal directions is different from the center of the gap 103 formed between the first and second lenses 101 and 102 using the cylinder lens. An afocal cylinder lens system 200 (also called an infinite focal lens system (afocai) is provided.

The spherical lens system 100 by the first and second lenses 102 and 102 and the afocal cylinder lens system 200 are formed as described above, and the afocal cylinder lens system 200 is disposed at an interval 103 between the spherical lens systems 100. The configuration in which is provided is called an anamorphic lens system 300.

The spherical lens system 100 and the anamorphic lens system 300 are fixed at a predetermined position in the barrel using a general barrel (not shown) in order to prevent their unique positions from changing due to the anamorphic lens system 300 installation structure. do.

FIG. 2 (C) (D) is an optical path diagram for a horizontal imaging state and an imaging state for an axial object point showing a 25 mm size reduced by 0.25 times to 6.25 mm, which passes through an axis of the anamorphic lens system 300. When the width of the subject is imaged on the C. C. 400, the horizontal direction is refracted by the refractive characteristics of the optical system, and the image is reduced in size with only the horizontal size being 0.25 times smaller than the actual width.

Fig. 2 (e) is an optical path diagram in which a 1: 1 image is formed without changing the magnification by an afocal cylinder lens system in which a vertical image forming state is disposed in the middle, and the width of the subject is not reduced in the vertical direction at all. It can be seen that the image is formed in the C. C. D (400) without.

In the above-described anamorphic lens system 300, the curved surface r formed on the lens system in the state where the arrangement is completed is formed from 1 to 22 surfaces, and they are formed with different curvatures and thicknesses to obtain the characteristics of the lens. The effective diameter is preferably formed to have almost the same dimensions.

(Example 1)

The first and second lenses 101 and 102, which face each other with a predetermined interval 103, select ones having a focal length of 200 mm, and arrange spherical lens groups symmetrically to achieve 1: 1 magnification. .

The gap 103 formed between the first and second lenses 101 and 102 has no change in magnification in the vertical direction, and the three afocal cylinder lens systems in which the change in magnification is reduced by 0.25 times in the horizontal direction. Place 200.

In arranging the lens system 200 described above, fixing between them is a normal barrel.

Referring to the effect of the present invention made of such a configuration as follows.

The spherical lens system 100 having a focal point facing each other at predetermined intervals forms a 1: 1 magnification according to the characteristics of the lens.

However, in the process of forming an image, the apocal cylinder lens system 200 does not cause a change in magnification in the vertical direction due to the characteristics of the optical system, but produces a change that is distorted only in the horizontal direction.

In the above action, the object forms a reduced image of 0.25 times in the horizontal direction. At this time, if the size of the object is 5 (height) x 25 (length) mm, the object height of the reduced image is 5 x 6.25 mm.

By doing so, the present invention can confirm that the height of the subject is formed in a state of 1: 1 in the general C.C.D.400 without using a high resolution C.C.D. It can be measured.

Such an application state of the present invention is an image processing optical system for various automatic inspection processes (for example, semiconductor marking) in addition to the legs inspection of semiconductors, and is used when the aspect ratio of the inspection object does not match the aspect ratio of C.C.D.

As described above, since the installation configuration of the lens system of the present invention is installed on the coaxial line, even if it is subjected to a slight impact during use, the installation position of the lens does not change, and its function is continued, and the installation configuration of the optical system is simple. There is an advantage that the assembly is easy, and furthermore, since the precision measurement is possible by a simple and easy assembly, there is an advantage that the measurement performance is remarkably improved.

Claims (3)

In measuring the accuracy of the product in the state where the image of the subject passing through the lens system is formed on the C. C. 400, the first and second lens systems 101 and 102, which consist of five elements, are prescribed. Spherical lens system 100 installed oppositely at intervals 103 to achieve a 1: 1 magnification, and anamorphic lens system installed at intervals 103 to refract the longitudinal and horizontal imaging ratio of the object to be examined differently ( C. C. anamorphic lens for the camera, characterized in that consisting of. The anamorphic lens for a C. C. camera according to claim 1, wherein the optical system for varying the vertical and horizontal imaging ratios comprises an apocal cylinder lens system (200). The anamorphic lens for C.C.D camera according to claim 1, wherein the aspect ratio of the image is reduced by 0.25 times in the horizontal direction.