Small light spot film thickness measuring system based on multimode optical fiber collimator

Abstract

The utility model discloses a small light spot film thickness measuring system based on a multimode optical fiber collimator, which belongs to the technical field of optical measurement and comprises a light cylinder, a lens shell fixedly connected to the bottom end of the light cylinder, a light splitting shell fixedly connected to the bottom end of the lens shell, and a multimode optical fiber collimator fixedly connected to one side end of the light splitting shell. The bottom end of the light splitting shell is fixedly connected with an objective lens, one side end of the light barrel is fixedly connected with a reflection tube, one end, far away from the light barrel, of the reflection tube is fixedly connected with a CCD unit, an upper spectroscope is arranged in the light barrel and corresponds to the reflection tube and the CCD unit, a tube lens is arranged in the lens shell and corresponds to the upper spectroscope, and the CCD unit is fixedly connected with the upper spectroscope. A lower spectroscope is arranged in the light splitting shell, and the lower spectroscope corresponds to the tube lens, the multimode optical fiber collimator and the objective lens; according to the utility model, the emergent light is more collimated by the multimode optical fiber collimator, the light spot entering the objective lens is larger, and the light spot hitting a sample is smaller, so that the proportion of the light returning to the receiving optical fiber above is larger.

Description

TECHNICAL FIELD

[0001] The utility model relates to optical measurement technical field more specifically, relate to a kind of small light spot film thickness measurement system based on multimode optical fiber collimator. BACKGROUND

[0002] Optical film thickness measuring instrument is a kind of equipment using optical principle to measure film thickness. The measuring instrument uses optical interference, reflection or transmission to measure the thickness of the film. This measurement method is suitable for the measurement of many materials and films, has the advantages of high precision and non-contact, and is widely used in the fields of semiconductors, optical elements and coatings.

[0003] At present, most of the existing optical measurement film thickness devices use large light spots. After the test piece is photoetched, the area used for feature size measurement is usually very small. The large light spot will bring the film layer information outside the to-be-measured area, interfere with the final spectral reflectance curve, and cannot accurately measure the film layer thickness. UTILITY MODEL CONTENT

[0004] 1. Technical problem to be solved

[0005] In view of the problems in the prior art, the utility model aims to provide a small light spot film thickness measurement system based on a multimode optical fiber collimator, which aims to solve the problem that most of the existing optical measurement film thickness devices use large light spots, and after the test piece is photoetched, the area used for feature size measurement is usually very small. The large light spot will bring the film layer information outside the to-be-measured area, interfere with the final spectral reflectance curve, and cannot accurately measure the film layer thickness.

[0006] 2. Technical scheme

[0007] To solve the above problems, the utility model adopts the following technical scheme:

[0008] A small light spot film thickness measurement system based on a multimode optical fiber collimator, comprising a light barrel, a lens shell fixedly connected to the bottom end of the light barrel, a light splitting shell fixedly connected to the bottom end of the lens shell, a multimode optical fiber collimator fixedly connected to one side end of the light splitting shell, an objective lens fixedly connected to the bottom end of the light splitting shell, a reflection tube fixedly connected to one side end of the light barrel, a CCD unit fixedly connected to the end of the reflection tube away from the light barrel, an upper light splitting mirror arranged in the light barrel, and the upper light splitting mirror corresponding to the reflection tube and the CCD unit, a tube lens arranged in the lens shell, and the tube lens corresponding to the upper light splitting mirror, a lower light splitting mirror arranged in the light splitting shell, and the lower light splitting mirror corresponding to the tube lens, the multimode optical fiber collimator and the objective lens.

[0009] As a preferred embodiment of the utility model, the R:T ratio of the upper light splitting mirror is 10:90.

[0010] As a preferred scheme of the utility model, the R:T ratio of the lower beam splitter is 50:50.

[0011] As a preferred scheme of the utility model, the mounting angles of the upper beam splitter and the lower beam splitter are opposite, and the tube lens is located between the upper beam splitter and the lower beam splitter.

[0012] 3. Beneficial effects

[0013] Compared with the prior art, the utility model has the advantages that:

[0014] (1) In the scheme, the multi-mode optical fiber collimator makes the outgoing light more collimated, the light spot entering the objective lens is larger, and the light spot hitting the sample is smaller, so that the proportion of light returning to the upper receiving optical fiber is larger, the upper beam splitter and the lower beam splitter are installed in different directions, which eliminates the lateral displacement of light passing through the parallel plate when the light returns to the upper receiving optical fiber, the optical fiber is placed at the back focal point of the tube lens, and finally only a very small light spot is received, and the illumination field is not affected, and the film thickness measurement light spot can reach below 30um. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is a front view of the utility model.

[0016] Explanation of reference numerals in the drawing:

[0017] 1, light barrel; 11, upper beam splitter; 2, lens shell; 21, tube lens; 3, beam splitter shell; 31, lower beam splitter; 4, multi-mode optical fiber collimator; 5, objective lens; 6, reflecting tube; 7, CCD unit. DETAILED DESCRIPTION

[0018] The technical schemes in the embodiments of the utility model will be clearly and completely described below in combination with the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the utility model.

[0019] In the description of the utility model, it should be pointed out that the terms "upper", "lower", "inner", "outer", "top / bottom end" and the like indicate the orientation or positional relationship shown in the drawing, and are only for the convenience of describing the utility model and simplifying the description, and do not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, therefore it cannot be understood as a limitation on the utility model. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0020] In the description of the utility model, it is necessary to explain, unless another explicit provision and limitation, the term "installation", "set with", "sleeve / interface", "connection" and so on, should do the broad sense understanding, for example "connection", can be fixed connection, also can be detachable connection, or integrally connected;Can be mechanical connection, also can be electrical connection;Can be directly connected, also can be indirectly connected through the intermediate medium, can be the communication inside two elements.For the ordinary skilled in the art, the specific meaning of the above-mentioned terms in the utility model can be understood according to the specific circumstances.

[0021] Embodiment:

[0022] Please refer to Figure 1 A kind of small light spot film thickness measurement system based on multimode fiber collimator, including light barrel 1, the bottom end of light barrel 1 is fixedly connected with lens shell 2, the bottom end of lens shell 2 is fixedly connected with light splitting shell 3, one side end of light splitting shell 3 is fixedly connected with multimode fiber collimator 4, the bottom end of light splitting shell 3 is fixedly connected with objective lens 5, one side end of light barrel 1 is fixedly connected with reflection tube 6, the end away from light barrel 1 of reflection tube 6 is fixedly connected with CCD unit 7, light splitting mirror 11 is arranged in light barrel 1, and light splitting mirror 11 corresponds with reflection tube 6 and CCD unit 7, tube lens 21 is arranged in lens shell 2, and tube lens 21 corresponds with light splitting mirror 11, lower light splitting mirror 31 is arranged in light splitting shell 3, and lower light splitting mirror 31 corresponds with tube lens 21, multimode fiber collimator 4 and objective lens 5.

[0023] Specifically, the R:T ratio of the upper light splitting mirror 11 is 10:90.

[0024] Specifically, the R:T ratio of the lower light splitting mirror 31 is 50:50.

[0025] Specifically, the installation angle of the upper light splitting mirror 11 and the lower light splitting mirror 31 is opposite, and the tube lens 21 is located between the upper light splitting mirror 11 and the lower light splitting mirror 31.

[0026] In this embodiment, the optical fiber is arranged at the top of the light barrel 1, the light signal emitted by the light source is collimated by the multimode fiber collimator 4 and input into the objective lens 5, the sample reflected light is focused by the tube lens 21 and then transmitted to the spectrometer by the optical fiber, the software calculates the reflectivity of the sample, and the film layer information of the sample to be measured is obtained by combining the algorithm, the optical fiber is located at the back focal point of the tube lens 21, finally only a very small light spot is received, and the illumination field is not affected, there is a multimode optical fiber on the multimode fiber collimator 4, the multimode optical fiber is arranged on the back focal plane of a collimating lens, the collimating lens of the multimode fiber collimator 4 is composed of fused quartz, calcium fluoride and the like, the R:T ratio of the upper light splitting mirror 11 and the lower light splitting mirror 31, R and T represent reflectivity and transmissivity respectively.

[0027] Working principle: the light source emits light signal, after outputting as parallel light by multi-mode optical fiber collimator 4, reflecting on the surface of lower beam splitter 31, focusing on the sample sheet by objective lens 5, the reflected light with sample film layer information transmits through lower beam splitter 31 with R:T=50:50, then transmits through tube lens 21 and upper beam splitter 11 with R:T=10:90, focuses on the receiving optical fiber, then is transmitted to the spectrometer by optical fiber, the reflectivity of the sample is calculated by software, the film layer information of the sample to be measured is obtained by combining algorithm, at the same time, the reflected light on the surface of upper beam splitter 11 with R:T=10:90 is reflected into CCD unit 7, so that the surface detail information of the sample can be observed.

[0028] The above is only the preferred specific implementation of the present application, but the protection scope of the present application is not limited to this, any skilled person in the art can make equivalent replacement or change according to the technical scheme and improvement concept of the present application within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A small spot film thickness measurement system based on a multimode fiber collimator, comprising a light cylinder (1), characterized in that: The bottom end of the light cylinder (1) is fixedly connected with a lens shell (2), the bottom end of the lens shell (2) is fixedly connected with a light splitting shell (3), one side end of the light splitting shell (3) is fixedly connected with a multi-mode optical fiber collimator (4), the bottom end of the light splitting shell (3) is fixedly connected with an objective lens (5), one side end of the light cylinder (1) is fixedly connected with a reflecting tube (6), the end of the reflecting tube (6) away from the light cylinder (1) is fixedly connected with a CCD unit (7), an upper light splitting mirror (11) is arranged in the light cylinder (1) and corresponds to the reflecting tube (6) and the CCD unit (7), a tube lens (21) is arranged in the lens shell (2) and corresponds to the upper light splitting mirror (11), a lower light splitting mirror (31) is arranged in the light splitting shell (3) and corresponds to the tube lens (21), the multi-mode optical fiber collimator (4) and the objective lens (5).

2. The small spot film thickness measurement system based on multi-mode fiber collimator according to claim 1, characterized in that: The R:T ratio of the upper light splitting mirror (11) is 10:

90.

3. The small spot film thickness measurement system based on multi-mode fiber collimator according to claim 2, characterized in that: The R:T ratio of the lower light splitting mirror (31) is 50:

50.

4. The small spot film thickness measurement system based on multi-mode fiber collimator according to claim 3, characterized in that: The mounting angles of the upper light splitting mirror (11) and the lower light splitting mirror (31) are opposite, and the tube lens (21) is located between the upper light splitting mirror (11) and the lower light splitting mirror (31).

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