KR102062367B1 - 30mm Equivalent Focal Length 1x Magnification Optical System only Used for 2D Focal Plane Array Available in Precision Sensing for 0.1 to 10 Terahertz band - Google Patents

Abstract

The present invention relates to a 30 mm-equivalent focal length 1x magnification optical system only used for a 2D focal plane array to perform precision detection within a band of 0.1 to 10 terahertz that is capable of increasing inspection efficiency in a semiconductor manufacturing process. According to the present invention, the optical system comprises: a first lens including a first convex surface (R1) formed on a subject side and a first concave surface (R2) formed on an image side and having a positive refractive index; a second lens including a second convex surface (R4) formed on the subject side and a second concave surface (R5) formed on the image side and having a positive refractive index; an aperture disposed between the first and second lenses; and an image surface receiving light outputted from the second lens to form an image of a subject.

Description

30mm Equivalent Focal Length 1x Magnification Optical System only Used for 2D Focal Plane Array Available in Precision Sensing for 0.1 to 10 Terahertz band}

The present invention relates to a 30 mm equivalent focal length 1x magnification optical system dedicated to 2D focal plane arrays capable of precise detection of the 0.1 to 10 terahertz band, and is applied to various production process monitoring, such as semiconductor packages, foods, pharmaceuticals, and biological tissues. The present invention relates to an optical system capable of detecting internal structures, defects, or crack component distribution of various materials composed of dielectrics.

The terahertz (THz) wavelength region applied to the present invention is light in the range of 93 μm to 104 μm and is applicable to the production process monitoring, and the mainly used area is the semiconductor manufacturing field, and the yield that was difficult with the imaging technique in the conventional semiconductor process inspection. Improvements are made by applying high resolution terahertz technology to enable crack detection.

The wavelength of 93 μm to 104 μm applied to the present invention is a terahertz optical system capable of observing internal structures such as semiconductor microscopic defects because the wavelength is shorter than that of the Sub-THz region.

Electromagnetic waves with a frequency of 0.1 to 10 terahertz (THz) are waves between infrared and microwave and have intermediate characteristics between light and chariot.

In addition, unlike X-rays, electromagnetic waves having a terahertz frequency have characteristics that can be observed internally while being less harmful to humans.

However, as the conventional frequency unit sensor takes a huge amount of time to acquire the image of the scanning (scanning) method, it is applicable only to some basic research, it was difficult to apply to the production process.

In addition, it was invisible and required to undergo a complex refining process on an optical table, so only professional researchers could use it.

In addition, the development of terahertz-related optical systems has been insufficient and only depended on imports.

Therefore, an attempt has been made to maintain the efficiency of the inspection of the production process through the invention of the high resolution terahertz optical system in the wavelength range of 93㎛ ~ 104㎛.

Prior Document 1: Korean Patent Publication No. 10-1777661 (2017.09.06)

The present invention has been made to solve the above-mentioned problems of the prior art, an object of the present invention is dedicated to 2D focal plane array capable of precise detection of the 0.1 to 10 terahertz band that can increase the inspection efficiency for the semiconductor production process It is to provide a 30mm equivalent focal length 1x magnification optics.

It is also an object of the present invention to provide a 30 mm equivalent focal length 1x magnification optical system for 2D focal plane arrays capable of precise detection of 0.1 to 10 terahertz bands of 93 μm to 104 μm wavelength bands, which only depended on imports.

In order to achieve the above object, the 30 mm equivalent focal length 1x magnification optical system dedicated to 2D focal plane array capable of precise detection of 0.1 to 10 terahertz band according to the present invention is capable of transmitting to 0.1 to 10 terahertz band. It features a two-group two-sheet optical system made of HRFZ-Si material (High Resistivity Float Zone Silicon).

The light incident from the subject is primarily refracted at the first convex surface of the first lens, and the light passing through the aperture is passed through the first concave surface that is secondarily refracted.

In addition, the light passing through the aperture is refracted in the tertiary at the second convex surface of the second lens, and after passing through, is imaged in the 2D focal plane array of the image plane through the last quaternary refraction in the second concave surface.

That is, the optical system according to the present invention has a configuration in which the diaphragm is positioned between the first lens and the second lens as a two-group two-sheet optical system.

In this case, the first convex surface R1, the first concave surface R2, the second convex surface R4, and the second concave surface R5 are defined by the relationship shown below in [Formula 1] and [Table 1]. As 30mm (EFL) 1x magnification optical system for exclusive use of 0.1-10 terahertz characterized by being prescribed,

[식 1]

[Equation 1]

TABLE 1

Here, k is a conical surface coefficient, A4, A6, A8 and A10 are aspherical coefficients, h is a distance from the optical axis to the concave or convex surface of each lens, and c represents the center curvature.

TABLE 2

Here, the radius of curvature and the surface thickness may have an allowable range of ± 0.5%.

(Diameters of the convex surfaces R1 and R4 of each lens) / (Diameter of the concave surfaces R2 and R5 of each lens) may have a tolerance of ± 0.5%.

In addition, the lens is characterized in that the edge portion extending between the convex surface (R1, R4) and the concave surface (R2, R5) of each lens in the direction perpendicular to the optical axis is characterized.

(Average value of the center thickness (TC) / diameter of the convex surfaces (R1, R4) and the concave surfaces (R2, R5) of each lens) has an allowable range of ± 0.5%, and (edge thickness of each lens) / ( The convex surfaces R1 and R4 and the central thickness TC of the concave surfaces R2 and R5 of the respective lenses may have an allowable range of ± 0.5%.

In addition, the 0.1 ~ 10 terahertz 30mm (EFL) 1x magnification camera according to the present invention,

From the subject set in front of the lens surface,

A first lens and a second lens spaced apart from each other;

An aperture disposed between the first lens and the second lens; And,

The image plane for forming an image of the subject through the light passing through the second lens may be sequentially disposed.

For example, in the camera according to the present invention, the distance between the target (subject) and the first convex surface R1 is 35.6 mm ± 0.5%, and the center of the first convex surface R1 and the first concave surface R2. The thickness TC is 25mm ± 0.5%, the distance between the first concave surface R2 and the aperture R3 is 12mm ± 0.5%, the distance from the aperture R3 to the second convex surface R4 is 21mm ± 0.5%, The center thickness TC of the second convex surface R4 and the second concave surface R5 is 20 mm ± 0.5%, and the distance from the second concave surface R5 to the image plane with the sensor is 15 mm ± 0.5%. It is characterized by that.

As a conventional unit sensor takes a huge amount of time to acquire an image of a scanning method, it is only applicable to some basic researches, but it is difficult to apply to a production process. Since it is invisible, a complicated refining process is required on an optical table. Only professional researchers could use it. While the development of the terahertz (THz) related optical system has been insufficient, the present invention has a configuration as described above. However, according to the present invention having the above-described configuration, only 2D focal plane arrays capable of precise sensing in the 0.1 to 10 terahertz band are available. As a 30mm equivalent focal length 1x magnification optical system, high-resolution terahertz optics in the wavelength range of 93㎛ to 104㎛ have efficiency in the inspection of the production process, and it has the advantage that domestic production of terahertz lenses is enabled. .

1 is a block diagram showing the structure of the terahertz 30mm (EFL) 1x magnification optical system according to the present invention.
Figure 2 is a light trace analysis of the terahertz 30mm (EFL) 1x magnification optical system according to the present invention.
3A is a side sectional view showing a configuration example of the first stove.
3B is a side sectional view showing a configuration example of a second stove.
4 is a graph showing the longitudinal spherical abberration of the terahertz 30mm (EFL) 1x magnification optical system according to the present invention.
5 is an aberration analysis graph of astigmatism of a terahertz 30 mm (EFL) 1 × magnification optical system according to the present invention.
6 is a graph showing distortion of a terahertz 30mm (EFL) 1x magnification optical system according to the present invention.
7 is a graph of a Modulation Transfer Function (MTF) showing a terahertz 30 mm (EFL) 1 × magnification optical system according to the present invention.
FIG. 8 shows a spot diagram of a terahertz 30 mm (EFL) 1 × magnification optics in accordance with the present invention. FIG.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram showing the structure of the terahertz 30mm (EFL) 1x magnification optical system according to the present invention, Figure 2 is a light trace analysis diagram of the terahertz 30mm (EFL) 1x magnification optical system according to the present invention, Figure 3a Fig. 3B is a side cross-sectional view showing a constitution example of the first range, Fig. 3B is a side cross-sectional view showing a constitution example of the first range, and Fig. 4 is a longitudinal spherical abberration of a terahertz 30 mm (EFL) 1x magnification optical system according to the present invention. 5 is an aberration analysis graph of astigmatism of the terahertz 30mm (EFL) 1x magnification optical system according to the present invention, and FIG. 6 is a terahertz 30mm (EFL) 1x magnification according to the present invention. 7 is a graph illustrating distortion aberration of an optical system, and FIG. 7 is a graph analyzing a MTF (Modulation Transfer Function) representing a terahertz 30 mm (EFL) 1x magnification optical system according to the present invention, and FIG. 8 is according to the present invention. La MHz 30mm (EFL) is a diagram showing a spot diagram (spot diagram) of the 1x magnification optical system.

As shown in Figures 1 to 3, the optical system according to the present invention includes a red made of HRFZ-Si material (High Resistivity Float Zone Silicon) capable of transmitting in the 0.1 ~ 10 terahertz band, the first lens ( 100) and a second group of two optical systems of the second lens 200.

First, the light incident from the subject P is primarily refracted by the first convex surface R1 of the first lens 100, and the light that passes continuously is secondly refracted by the first concave surface R2. After passing through the aperture 300.

As such, the light passing through the iris 300 is refracted in the third convex surface R4 of the second lens 200 in a third order, and after passing through the second concave surface R5 in the second concave surface R5, successively. After the image is formed, an image is formed on a 2D focal plane array of the image plane 400.

As described above, the optical system according to the present invention has a configuration in which the diaphragm 300 is disposed between the first lens 100 and the second lens 200 as a two-group two-sheet optical system.

Since the diaphragm 300 is disposed between the first lens 100 and the second lens 200, the diaphragm 300 not only prevents light from entering the optical system, but also has advantageous properties for MTF optical performance.

The first lens 100 and the second lens 200 have a positive refractive index as a whole, and both surfaces of the first lens 100 and the second lens 200 are aspherical.

Preferably, the first lens 100 and the second lens 200 are formed of a mold silicon optical material. Silicon optical materials are widely used in military civil fields based on a wide wavelength band, and are available in the existing market. Compared to the lower price.

In addition, the silicon optical material is possible to configure a variety of optical system from small diameter lens to large diameter lens on the basis of the optical characteristics of refractive index 3.41 and material transmittance of 50% or more.

When the optical system is composed of the optical material according to the present invention, it is possible to manufacture a high resolution camera for terahertz corresponding to 0.1 to 1.0, and to easily configure a localized terahertz 30mm (EFL) 1x magnification camera optical system.

In addition, the terahertz 30mm (EFL) 1x magnification camera of the present invention employing a lens of such a material can be designed for a two-group two-layer optical system for terahertz applied 19200 pixels (sensor).

On the other hand, the concave and convex surfaces of the lens according to the present invention is defined by the relationship between the following [Equation 1] and [Table 1] and [Table 2] 0.1 ~ 10 terahertz only 30mm (EFL) 1x magnification optical system.

[식 1]

[Equation 1]

TABLE 1

Here, k is a conical surface coefficient, A4, A6, A8 and A10 are aspherical coefficients, h is a distance from the optical axis to the concave or convex surface of each lens, and c represents the center curvature.

TABLE 2

Here, the radius of curvature and the surface thickness may have an allowable range of ± 0.5%.

In this case, (diameter of convex surfaces R1 and R4 of each lens) / (diameter of concave surfaces R2 and R5 of each lens) may have a tolerance of ± 0.5%.

Each of the lenses 100 and 200 may have edge portions 110 and 120 extending between the convex surfaces R1 and R4 and the concave surfaces R2 and R5 in a direction perpendicular to the optical axis.

In addition, according to the present invention, the distance between the target (subject, P) and the first convex surface (R1) is 35.6mm ± 0.5%, the central thickness (1) of the first convex surface (R1) and the first concave surface (R2) TC) is 25mm ± 0.5%, the distance between the first concave surface (R2) and the aperture (R3) is 12mm ± 0.5%, the distance from the aperture (R3) to the second convex surface (R4) is 21mm ± 0.5%, the first 2 The central thickness TC of the convex surface R4 and the second concave surface R5 is 20 mm ± 0.5%, and the distance from the second concave surface R5 to the image plane 400 of the sensor 400 is 15 mm. It can consist of ± 0.5%.

That is, the 0.1 to 10 terahertz 30 mm (EFL) 1x magnification camera according to the present invention may be arranged to be spaced apart from each other from the subject P set in front of the lens surface 35.6 mm from the first lens 100 and the second lens 200. ), An aperture 300 disposed between the first lens 100 and the second lens 200, and an image surface 400 that forms an object through light passing through the second lens 200.

When the thickness tolerance is set in the first lens 100 and the second lens 200 of the present invention, it is possible to manufacture the lens within the tolerance of the manufactured lens, thereby producing a lens having a constant optical performance.

In addition, by manufacturing the corner portion of the lens (100,200) in the form of a chamfer can be advantageous to the optical system assembly and production.

On the other hand, the refractive index of the lens (100, 200) is 3.41 and the dispersion ratio is appropriately 2421.0.

Through such conditions, as shown in FIGS. 4 to 8, a predetermined angle of view can be obtained, and at the same time, longitudinal spherical aberration, astigmatism, and distortion can be minimized, and MTF (Modulation Transfer Functions) representing the resolution can be obtained. A good state can be obtained from the value.

Hereinafter, an exemplary embodiment of a 0.1 to 10 terahertz 30 mm (EFL) 1x magnification camera according to the present invention will be described based on the configuration as described above.

First, the lens of the 0.1 ~ 10 terahertz 30mm (EFL) 1x magnification camera according to the present invention is a lens of a high resolution terahertz camera optical system that can be applied to semiconductor process inspection, made of silicon optical material and diamond turning machine (DTM) : Diamond Turning Machine) Aspherical lens was manufactured by ultra precision machine.

In addition, the curvature radii of the first convex surface R1 and the first concave surface R2 of the first lens 100 are 46.70 (aspherical surface), 90.14 (aspherical surface), and the effective diameters of the first double convex surface R1, respectively. (CA) was 50.0 mm and the diameter of the 1st concave surface R2 was set to 32.0 mm.

The thickness of the first lens 100 was formed to 25.0mm.

For mounting, a chamfer extending from the first convex surface R1 and the second concave surface R2 is formed to be perpendicular to the optical axis. In consideration of this, the diameter of the entire lens is set to 55.0 mm.

The chamfer is rounded to 2.0 mm but can be adjusted appropriately.

In addition, the radiuses of curvature of the second convex surface R4 and the concave surface R5 of the second lens 200 are 31.49 (aspherical surface), 90.14 (aspherical surface), and the effective diameters of the second double convex surface R4 are The diameter of 42.0 mm and the second concave surface R5 was set to 24.0 mm.

The thickness of the second lens was formed to 20.0 mm.

For mounting, the chamfers extending from the convex surface R1 and the concave surface R2 are formed perpendicular to the optical axis, and in consideration of this, the diameter of the entire lens is set to 46.0 mm.

The chamfer is rounded to 2.0 mm but can be adjusted appropriately.

In addition, the diaphragm 300 is disposed between the first concave surface R2 and the second convex surface R4, and the distance between the diaphragm 300 and the first concave surface R2 is 12.0 mm. The distance from the diaphragm 300 to the second convex surface R4 is 21.0 mm.

The distance from the second concave surface R5 to the image surface 400 on which the sensor S is disposed is set to 10.759 mm.

The terahertz lens has a refractive index of 3.41 and a dispersion of 2421.0.

In addition, a 100 μm sensor of 160 * 120 pixels may be adopted as the sensor S of the image plane 400.

The following experimental results were obtained with a 0.1 to 10 terahertz 30 mm (EFL) 1x magnification camera of the present invention having such a configuration.

The 0.1-10 terahertz 30mm (EFL) 1x magnification camera according to the present invention shows that the values of the images are shown adjacent to the central axis in almost all fields, indicating that the aberration correction of various aberrations is good, as well as MTF (optical requirement performance). / Resolution).

In addition, the peripheral light quantity ratio of the optical system of the present invention was secured 90% or more on the basis of 1.0 Field, the distortion rate is 1.4% optical system performance is secured on the basis of 1.0 Field.

Therefore, the present invention can apply the high resolution terahertz optical system, it is possible to increase the inspection efficiency for the existing semiconductor production process.

In addition, it is possible to localize existing terahertz optics, which depended only on existing imports.

Embodiments of the present invention are merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible within the scope of the following claims.

100 ... first lens
200 ... second lens
300 ... Aperture
400 ... image plane
P ... Subject
S ... sensor

Claims (5)

An optical system disposed along an optical axis,
A first lens having a first convex surface R1 formed on the side of the projectile and a first concave surface R2 formed on the image side and having a positive refractive index;
A second lens having a second convex surface R4 formed on the side of the projectile and a second concave surface R5 formed on the image side and having a positive refractive index;
An aperture disposed between the first lens and the second lens; And,
It is configured to include an image plane for receiving the light from the second lens to form an image,
The first convex surface R1, the first concave surface R2, the second convex surface R4, and the second concave surface R5 are represented by the relations of Equations 1, 1, and 2 below. A 30 mm (EFL) 1x magnification optical system for 0.1-10 terahertz, characterized by what is specified by

[Equation 1]
TABLE 1

Where k is the conical surface coefficient, A4, A6, A8 and A10 are aspherical coefficients, h is the distance from the optical axis to the concave or convex surface of each lens and c represents the center curvature;
TABLE 2

Here, the radius of curvature and the surface thickness may have a tolerance of ± 0.5%, (diameter of the convex surfaces (R1, R4) of each lens) / (diameter of the concave surfaces (R2, R5) of each lens) ± May have a tolerance of 0.5%
The method of claim 1,
The first lens and the second lens have an edge portion extending between the convex surface and the concave surface of each lens in a direction perpendicular to the optical axis. .
The method of claim 2,
(Average value of the center thickness TC / diameter of each of the convex surfaces R1 and R4 and the concave surfaces R2 and R5 of the first and second lenses has an allowable range of ± 0.5%. Edge thickness of each lens of the first lens and the second lens) / (center thickness TC of the convex surfaces R1 and R4 and the concave surfaces R2 and R5 of the first and second lenses) ± A 30 mm (EFL) 1x magnification optical system for 0.1-10 terahertz, characterized by a tolerance of 0.5%.
The method according to any one of claims 1 to 3,
The distance between the target (subject) and the first convex surface R1 is 35.6 mm ± 0.5%, and the center thickness TC of the first convex surface R1 and the first concave surface R2 is 25 mm ± 0.5%, The distance between the first concave surface R2 and the aperture R3 is 12 mm ± 0.5%, the distance from the aperture R3 to the second convex surface R4 is 21 mm ± 0.5%, and the second convex surface R4 and the second 2, the center thickness T of the concave surface R5 is 20 mm ± 0.5%, and the distance from the second concave surface R5 to the image surface 400 of the sensor 400 is 15 mm ± 0.5%. 30mm (EFL) 1x magnification optical system for exclusive use of 0.1-10 terahertz characterized by.
The method according to any one of claims 1 to 3,
The radius of curvature of the first convex surface R1 and the first concave surface R2 of the first lens is 46.70 (aspherical surface) and 90.14 (aspherical surface), respectively, and the effective diameter CA of the first double convex surface R1 is 50.0. mm, the diameter of the first concave surface (R2) is set to 32.0mm, the thickness of the first lens is formed to 25.0mm,
The radiuses of curvature of the second convex surface R4 and the concave surface R5 of the second lens are 31.49 (aspherical surface) and 90.14 (aspherical surface), respectively, and the effective diameters of the second double convex surface R4 are 42.0 mm and second. The diameter of the concave surface (R5) is set to 24.0mm, the thickness of the second lens is 30mm (EFL) 1x magnification optical system for 0.1 ~ 10 terahertz, characterized in that formed in 20.0mm.

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