CN210071136U

CN210071136U - Sampling mechanism for sampling invisible light wave band airy spot image

Info

Publication number: CN210071136U
Application number: CN201920840521.6U
Authority: CN
Inventors: 何帅
Original assignee: NANJING DONGLILAI PHOTOELECTRIC INDUSTRIAL Co Ltd
Current assignee: NANJING DONGLILAI PHOTOELECTRIC INDUSTRIAL Co Ltd
Priority date: 2019-06-04
Filing date: 2019-06-04
Publication date: 2020-02-14
Anticipated expiration: 2029-06-04

Abstract

The utility model provides a find the focus position of measured objective lens easily, can swiftly carry out the sampling mechanism of sampling to non-visible light wave band Ehrlich spot image. It includes: the device comprises a light source (1), a beam expander (11), a beam splitter prism (5), a tube mirror system (6), a measured object mirror (7), a first plane reflector (8) and a CCD (10); collimated beams of a non-visible light wave band emitted by a light source (1) are expanded by a beam expander (11) and then emitted as parallel light, enter a beam splitter prism (5), are focused on the surface of a first plane reflector (8) through a measured object lens (7), and light rays are reflected, returned along an original light path, enter a tube lens system (6) through the beam splitter prism (5) and then are focused on a target surface position of a CCD (10); the magnification of the beam expander (11) is to ensure that the diameter of the emergent beam is larger than the maximum clear aperture of the objective (7) to be measured; the position of the first plane reflector (8) relative to the measured object mirror (7) on the optical axis can be adjusted.

Description

Sampling mechanism for sampling invisible light wave band airy spot image

Technical Field

The utility model relates to a device that samples is carried out non-visible light wave band erichsen spot image, through the sampling back, can carry out non-visible light wave band erichsen spot energy distribution and detect, especially to the laser objective of laser stealthy cutting, can evaluate the homogeneity that is used for the focus energy distribution state of cutting through subsequent analysis processes after sampling its non-visible light wave band erichsen spot image.

Background

In the case of dicing a semiconductor chip using a laser lithography machine, a stealth dicing method is generally used to avoid scratching the chip surface by debris generated during dicing, as compared with the conventional dicing method, and the most significant difference of stealth dicing is a dicing technique in which laser light other than visible light is focused inside a workpiece material via an optical path system to form a starting point for dicing and the material is diced by cracking a crystal bond of the material. The cutting machine has the advantages of low cutting power, environmental protection, dust prevention, no need of cutting liquid, and little heat generated during cutting, which has no influence on the characteristics of workpiece materials.

Therefore, due to the change of the cutting method, the starting point for dividing is transferred from the surface of the traditional material to the interior of the workpiece material, the requirement on focusing capability of an optical path system used for focusing is higher, the roundness of a focus in the material and the energy distribution in the focus range are not good, the direction of cracking of the crystal bond is inconsistent with the depth of fracture, and the verticality of the cut edge of the material is affected. In order to facilitate adjustment and calibration, a laser cutting objective lens used in a focusing system is usually designed according to an adjustment wavelength and a working wavelength, wherein the adjustment wavelength is a visible light band, and the working wavelength is a non-visible light band, so that sampling of an airy spot image in the non-visible light band within a depth of field is difficult to realize, and of course, the roundness of the airy spot and the uniformity of energy cannot be accurately measured.

Disclosure of Invention

The utility model aims at providing a find the focus position of measured object mirror easily, can swiftly obtain the sampling mechanism that samples to non-visible light wave band eric spot image of non-visible light wave band eric spot image.

Sampling mechanism to sampling is carried out to non-visible light wave band Ehrlich spot image, it includes: the device comprises a light source 1, a beam expander 11, a beam splitter prism 5, a tube mirror system 6, a measured object mirror 7, a first plane reflector 8 and a CCD 10; the non-visible light wave band collimated light beam emitted by the light source 1 is expanded by the beam expander 11 and then emitted as parallel light, enters the beam splitter prism 5, is focused on the surface of the first plane reflector 8 through the measured object lens 7, and the light is reflected, returns along the original light path, enters the tube lens system 6 through the beam splitter prism 5 and is focused on the target surface position of the CCD 10; the amplification ratio of the beam expander 11 is to ensure that the diameter of the emergent beam is larger than the maximum clear aperture of the objective lens 7 to be measured; the position of the first plane mirror 8 on the optical axis relative to the object lens 7 to be measured can be adjusted.

In the above sampling mechanism, the light source 1 is a collimated non-visible light band laser.

The sampling mechanism further comprises an altimeter 9 for detecting the moving distance of the first plane reflecting mirror 8 relative to the measured object mirror 7.

In the sampling mechanism, the focal length of the tube lens system 6 is 200 mm.

In the sampling mechanism, a second plane mirror 12 is arranged between the tube mirror system 6 and the CCD10, and light emitted from the tube mirror system 6 is reflected by the second plane mirror 12 and then focused on the target surface of the CCD 10.

The beneficial effect of this technique: the non-visible light wave band collimated light beam emitted by the light source 1 is expanded by the beam expander 11, enters the beam splitter 5, is focused on the surface of the first plane reflector 8 through the measured object lens 7, the light is reflected and returns along the original light path, and then enters the tube lens system 6 through the beam splitter 5, in order to reduce the volume of the whole optical system, a second plane reflector 12 is added below the emergent end of the tube lens system 6, the light is focused on the target surface position of the sampling CCD10 through the second plane reflector 12, at the moment, the upper and lower positions of the first plane reflector 8 are adjusted within the depth of field range of the measured object lens 7, the focal position of the measured object lens 7 is searched, and then the first plane reflector 8 is moved on the optical axis near the focal position, so that the Airy spot images at different positions within the depth of field range can be obtained on the CCD.

The magnification of the beam expander 11 is such that the diameter of the outgoing beam is larger than the maximum clear aperture of the objective lens 7, and the beam expander 11 can also be called a high-power beam expander 11. And the accuracy of the final airy spot sampling result is improved by adopting the high-power beam expander 11.

The beneficial effect of this technique: the technology is that a flat reflector is placed on the object surface of the measured lens by utilizing the principle of the coaxial illumination light path of the microscope, the light source is a collimation laser with non-visible light wave band, the light returns to the flat reflector through the measured lens by the coaxial illumination system, and is imaged on the target surface of the sampling CCD by the beam splitter prism and the tube lens system. Because the light returns once along the original light path, the aberration of the measured objective lens is amplified by 2 times on the sampling CCD, and the ehrlichia aberration of the measured objective lens is easier to distinguish than the conventional mode of transmitting illumination. Meanwhile, the light source adopts a collimation laser with a non-visible light wave band, so that the problem that the energy uniformity and the roundness of the cerite under the working wavelength cannot be accurately measured in the field depth range because the working wavelength is the non-visible light wave band is solved.

When the device is used, the measured object mirror is placed on the designated installation surface, the main optical axis of the measured object mirror is coincided with the system optical axis, the focal position of the measured object mirror 7 is found by adjusting the upper position and the lower position of the first plane reflecting mirror 8, and the Ehrlich spot images at different positions in the depth of field range are sampled according to the reading of the altimeter 9. And finally, inputting the sampling result into a computer, and measuring the energy distribution and the roundness of the acquired erichsen spots at different positions in the field depth range by adopting the prior art to obtain the results of the energy distribution and the roundness of the erichsen spots.

Drawings

FIG. 1 is a schematic diagram of a sampling mechanism for sampling a non-visible band airy disk image;

FIG. 2 is a result of sampling airy plaques at different positions within the depth of field using the apparatus;

FIG. 3 is an algorithm processed airy disk profile;

FIG. 4 is a profile of the maximum inscribed circle of the airy disk after algorithm processing;

FIG. 5 is an energy distribution plot of an airy disk after being processed by an algorithm;

fig. 6 is a graph of the energy distribution of the focus area after being processed by the algorithm.

Detailed Description

The present technology is further described below with reference to the accompanying drawings and examples.

The method for detecting the energy of the invisible light wave band airy spot firstly adopts a sampling device of the invisible light wave band airy spot pattern shown in figure 1 to sample. Referring to fig. 1, a light source 1 selects collimated lasers with different wavelengths according to the actual working wavelength of an object lens 7 to be measured, a non-visible light waveband collimated laser beam emitted by the laser enters a beam splitter 5 after being expanded by a high-power beam expander 11, is focused on the surface of a first plane reflector 8 through a rear diaphragm of the object lens 7 to be measured, is reflected, returns along the original light path, enters a system 6 with a focal length of 200mm through the beam splitter 5, and is emitted to a second plane reflector 12, the light is focused on the target surface position of a sampling CCD10 through the second plane reflector 12, at the moment, the upper and lower positions of the first plane reflector 8 are adjusted within the depth of field range of the object lens 7 to find the focal position of the object lens 7 to be measured, and the airy spot images at different positions within the depth of field range are sampled according to the reading of a height gauge 9.

Referring to fig. 2, after finding the focus position of the objective lens 7 to be measured, the altimeter 9 is reset to zero, the readings of the altimeter 9 are recorded in sequence by adjusting the upper and lower positions of the first plane mirror 8, and the egyptian spots at different defocused positions are sampled by the CCD at the moment.

Referring to fig. 3, the image of the airy spot is input into a computer and the outline of the airy spot is identified by an algorithm belonging to the prior art, as shown in fig. 3.

Referring to fig. 4, the maximum inscribed circle contour in the airy disk contour in the sampling result is obtained after algorithm processing by using the maximum inscribed circle judgment rule. The ratio of the area of the maximum inscribed circle to the area occupied by the airy spot profile is calculated by integration, and the true circularity value (area ratio) K is 0.9234.

Referring to fig. 5, a contour map of the airy plaque energy distribution is obtained by an algorithmic process. As shown in fig. 6.

Referring to fig. 6, the energy distribution graphs of the focal area are compared through algorithm processing, and whether the energy distribution of the airy disk at the position is uniform or not is judged.

By sampling and detecting calculation through the sampling device, aiming at an objective lens for laser invisible cutting, the energy distribution and the roundness of the Ehrlich spots under a non-visible light wave band can be quickly and accurately sampled, analyzed, evaluated and detected as well as the image quality.

Claims

1. A sampling mechanism for sampling a non-visible wave band airy disk image is characterized in that: it includes: the device comprises a light source (1), a beam expander (11), a beam splitter prism (5), a tube mirror system (6), a measured object mirror (7), a first plane reflector (8) and a CCD (10); collimated beams of a non-visible light wave band emitted by a light source (1) are expanded by a beam expander (11) and then emitted as parallel light, enter a beam splitter prism (5), are focused on the surface of a first plane reflector (8) through a measured object lens (7), and light rays are reflected, returned along an original light path, enter a tube lens system (6) through the beam splitter prism (5) and then are focused on a target surface position of a CCD (10); the magnification of the beam expander (11) is to ensure that the diameter of the emergent beam is larger than the maximum clear aperture of the objective (7) to be measured; the position of the first plane reflector (8) relative to the measured object mirror (7) on the optical axis can be adjusted.

2. The sampling mechanism for sampling a non-visible band airy disk image of claim 1, wherein: the light source (1) is a quasi-straight non-visible light wave band laser.

3. The sampling mechanism for sampling a non-visible band airy disk image of claim 1, wherein: it also comprises a height meter (9) for detecting the distance of the first plane reflector (8) moving relative to the measured object mirror (7).

4. The sampling mechanism for sampling a non-visible band airy disk image of claim 1, wherein: the focal length of the tube lens system (6) is 200 mm.

5. The sampling mechanism for sampling a non-visible band airy disk image of claim 1, wherein: a second plane reflector (12) is arranged between the tube mirror system (6) and the CCD (10), and light rays emitted from the tube mirror system (6) are focused on the target surface position of the CCD (10) after being reflected by the second plane reflector (12).