Optical thin film analysis device not affected by substrate back reflection, and analysis method using same

Abstract

The present invention relates to an optical thin film analysis device that is not affected by reflection on the rear surface of a substrate, and an analysis method using the same. The present invention relates to an optical thin film analysis device and an analysis method using the same, and more particularly, to an optical thin film analysis device which can simultaneously measure the thickness of a thin film, and a refractive index and an extinction coefficient as optical constants by using an optical method without being affected by substrate back reflection, and to an analysis method using the same, and to an optical thin film analysis device which can improve spatial resolution and measurement accuracy by solving the problem of substrate back reflection. The invention provides an optical thin film analyzer and an analysis method using the same. The optical thin film analyzer simultaneously measures the thickness and the optical constant of a thin film.

Description

Technical Field

[0001] This invention relates to an optical thin film analysis apparatus and an analysis method thereon that are unaffected by reflections from the back of a substrate. More specifically, it relates to an optical thin film analysis apparatus and an analysis method thereon that can simultaneously measure the thickness of a thin film and its refractive index and extinction coefficient as optical constants using optical methods. Furthermore, it relates to an optical thin film analysis apparatus and an analysis method thereon that improves spatial resolution and measurement accuracy by addressing the reflection problem from the back of the substrate, while simultaneously measuring the thickness of a thin film and its optical constants. Background Technology

[0002] Since various research materials are fabricated as thin film samples on substrates, the measurement of thin film thickness is a crucial task in materials research. Optical methods for measuring thin film thickness are well-known for their non-contact / non-destructive nature, making them extremely useful. Furthermore, when the material is intended for optical applications, it is also necessary to measure optical constants such as refractive index and extinction coefficient; therefore, optical thin film analysis methods are of paramount importance.

[0003] On the other hand, optical thin film analysis methods include ellipsometry (refer to non-patent document 1), spectroscopic reflectance analysis (refer to non-patent document 2), spectroscopic transmission analysis (refer to non-patent document 2), and non-spectroscopic transmission analysis (refer to non-patent document 3).

[0004] However, when the substrate of the thin film is not thick (which is the case for most thin film samples in reality), the reflection of the beam on the back of the substrate becomes a major problem in optical thin film analysis methods.

[0005] Figure 1 This is a schematic diagram showing a portion of the light beam passing through the substrate 40, with the remainder being reflected by the substrate 40. (See diagram below.) Figure 1As shown, a portion of the incident beam 10 is split into a beam 20-1 reflected from a specific region 50R-1 on the front surface of the substrate 40 and a transmitted beam. Here, the transmitted beam is split into a beam reflected again from the back surface of the substrate 40 and a transmitted beam 30-1. Here, the reflected beam is split into a beam reflected again from a region 50R-2 on the front surface of the substrate 40 and a transmitted beam 20-2. Here, the reflected beam is split into a beam reflected again from the back surface of the substrate 40 and a transmitted beam 30-2. Here, the reflected beam is split into a beam reflected again from a region 50R-3 on the front surface of the substrate 40 and a transmitted beam 20-3. The reflected beam is split into a beam reflected again from the back surface of the substrate 40 and a transmitted beam 30-3. Here, the reflected beam continues to repeat from the front and back surfaces of the substrate 40. Therefore, the reflected beam 20 is composed of multiple beams such as 20-1, 20-2, and 20-3, while the transmitted beam 30 is composed of multiple beams such as 30-1, 30-2, and 30-3. The spacing Δ between the multiple beams can be expressed as Δ = 2d. s cosθ i tanθ s (where sinθ) i =n s sinθ s ), where n s d s θ i θ s These represent the refractive index of substrate 40, the thickness of substrate 40, the incident angle, and the refraction angle on substrate 40, respectively.

[0006] Figure 2 The spacing variation of the beam of light reflected multiple times from the substrate 40 relative to the incident angle of the beam on the substrate 40 is shown. Figure 2 This refers to a glass substrate with a refractive index of 1.5. From... Figure 2 It is known that in the case of a thin glass substrate with a refractive index of 1.5 and a thickness of 1 mm, the beam spacing ranges from 0 mm to 0.76 mm, which is a very small value. Due to this small beam spacing, the multiple reflected beams from the substrate overlap in space. Therefore, when the multiple reflected beams from the substrate overlap in space, they interfere with each other. This interference between the multiple reflected beams from the substrate can cause errors in the analysis of the thin film 50, making it difficult to obtain accurate measurement values. Furthermore, if there is back reflection from the substrate 40, not only the specific region (the region to be analyzed) 50R-1 of the thin film 50 will be measured, but also regions adjacent to the specific region 50R-1, such as 50R-2 and 50R-3, will be measured. This reduces the spatial resolution of the thin film 50 analysis. Moreover, when the uniformity of the thin film 50 is poor, there is a problem of reduced measurement accuracy.

[0007] Figure 3 This is a schematic diagram illustrating the formation of unevenness 60 on the back side of substrate 40 to prevent reflection from the back side of substrate 40 and eliminate the influence of the back side of conventional substrate 40. (As shown) Figure 3 As shown, when the back surface of substrate 40 is roughened to form an uneven surface 60, the reflection of the light beam is blocked. The reflected light beam 20 is detected by a reflective beam photodetector 200. This method solves the back surface reflection problem of substrate 40 and is mainly used in ellipsometry or spectroscopic reflectance analysis methods.

[0008] Figure 4 This is a schematic diagram illustrating a method for preventing mutual interference of multiple beams from the substrate 40 using a conventional beam-splitting light source 100. (e.g.) Figure 4 As shown, a spectroscopic light source 100 can be used to prevent mutual interference of multiple beams from the substrate 40. When using the spectroscopic light source 100 as the light source 100 to receive and analyze beams measured by the reflective beam photodetector 200 and the transparent beam photodetector 300, mutual interference of multiple beams on the substrate 40 can be prevented by setting the effective coherence length of the beams to be sufficiently short. Furthermore, when using a method that reduces the incident angle to a small value (perpendicular incidence) to almost 0° (the spacing between multiple beams becomes almost 0), it is also possible to measure only a specific region 50R-1 of the thin film 50. This method is a solution to the reflection problem on the back side of the substrate 40 and can be applied to spectroscopic reflectance analysis and spectroscopic transmission analysis.

[0009] Figure 5 This is a schematic diagram illustrating a method for spatially separating multiple reflected light beams in a conventional substrate. (Example) Figure 5As shown, multiple reflected beams can be spatially separated. By focusing the incident beam 10 to reduce its diameter and selecting an appropriate angle of incidence, the beams can be spatially separated. Since the beams are spatially separated, mutual interference between them does not occur. To obtain highly reliable analytical results, it is generally preferable to use multiple wavelengths of light source 100 instead of a single wavelength, and to measure multiple angles of incidence instead of just one. However, the problem remains that the measurement includes not only a specific region 50R-1 of the thin film 50 but also a large area. This method only partially solves the reflection problem on the back side of the substrate 40 and is used for nonspectroscopic transmission analysis. However, this method has the advantage of being applicable to nonspectroscopic thin film analysis methods. Because it is nonspectroscopic, it has the advantage of a simple analytical mechanism and can also be used for the analysis of new or unknown substances.

[0010] However, the methods described above are insufficient for analyzing the optical properties of high-precision thin films, and further research and development are needed.

[0011] Existing technical documents

[0012] Patent documents

[0013] Patent Document 1: Japanese Patent Publication No. 2003-302334

[0014] Patent Document 2: Japanese Patent Publication No. 2003-506697

[0015] Patent Document 3: U.S. Patent Publication No. 2004-0085537

[0016] Patent Document 4: European Patent Publication No. 3775835

[0017] Patent Document 5: Korean Patent Publication No. 2023-0109747

[0018] Non-patent literature

[0019] Non-patent literature 1 Lee Je-hyun, Park Min-soo, Yang Sung-mo, Park Sang-wook, Lee Min-ho, Kim Sang-yeol, “Precise measurement of ultra-micro optical anisotropy of tribologically treated polyimide alignment film using a reflective ellipsometer”, Journal of the Korean Optical Society, Vol. 26 (No. 4), pp. 195-202 (full text) (2015).

[0020] Non-patent literature 2 Vitaly P. Kutavichus, Valery V. Filippov and Vitali H. Huzouski, “Determination of optical parameters and thickness of weakly absorbing thin films from reflectance and transmittance spectra”, Appl. Opt. 45(19), 4547-4553 (full text, 2006)

[0021] Non-patent literature 3 Changsoo Jung and Bum Ku Rhee, “Simultaneous determination of thickness and optical constants of polymer thin film by analyzing transmittance”, Appl. Opt. 41 (19), 3861-3865 (full text, 2002). Summary of the Invention

[0022] The problem the invention aims to solve

[0023] Non-spectral transmittance analysis, a traditional method for thin film analysis that involves separating multiple reflected beams within the substrate space, offers significant advantages. However, it suffers from limitations in spatial resolution and measurement accuracy, as it measures not only specific regions of the thin film but also large areas.

[0024] To address the aforementioned problems, the present invention aims to provide an optical thin film analysis apparatus and an analysis method thereof that can simultaneously measure the thickness and optical constants (refractive index, extinction coefficient) of a thin film using optical methods, and solve the reflection problem on the back side of the substrate, thereby improving spatial resolution and measurement accuracy.

[0025] means for solving problems

[0026] An optical thin-film analysis apparatus according to an embodiment of the present invention, unaffected by reflection from the back side of a substrate, comprises: a light source for emitting a light beam; a substrate coated with a thin film through which the light beam emitted by the light source passes; a multiple beam splitter located between the light source and the substrate, for splitting the transmitted light beam through the substrate into multiple beams; a beam spacing expander for expanding the spacing between the multiple beams transmitted through the substrate; a beam filter for transmitting a portion of the beam expanded by the beam spacing expander and reflecting the remainder; a beam deviation compensator for compensating for deviations in the beam transmitted or reflected by the beam filter; and a light-transmitting photodetector for receiving the beam whose deviation has been compensated by the beam deviation compensator.

[0027] An optical thin film analysis method according to an embodiment of the present invention, unaffected by backside reflection of a substrate, includes: a first step of emitting a light beam from a light source; a second step of transmitting the light beam emitted in the first step through a multiple beam splitter; a third step of transmitting the light beam through the multiple beam splitter through a substrate coated with a thin film to split into multiple beams; a fourth step of transmitting the multiple beams of the third step through a beam spacing expander to expand the beam spacing; a fifth step of transmitting a portion of the expanded beam in the fourth step through a beam filter and reflecting the remainder; a sixth step of compensating for beam deviation by passing the transmitted or reflected beam in the fifth step through a beam deviation compensator; and a seventh step of receiving the beam with the deviation compensated in the sixth step by a photodetector.

[0028] The effects of the invention

[0029] The optical thin film analysis apparatus and analysis method according to the present invention have the effect of improving spatial resolution and measurement accuracy by solving the reflection problem on the back of the substrate, while simultaneously measuring the thickness and optical constants of the thin film. Attached Figure Description

[0030] Figure 1 This is a schematic diagram showing a portion of a light beam passing through a substrate, with the remainder being reflected by the substrate.

[0031] Figure 2 The spacing variation of the beams reflected multiple times from the substrate relative to the incident angle of the beams on the substrate is shown.

[0032] Figure 3 This is a schematic diagram illustrating the formation of irregularities on the back side of a substrate to prevent reflections from the back side of the substrate and eliminate the influence of the back side of a conventional substrate.

[0033] Figure 4 This is a schematic diagram illustrating a method for preventing mutual interference of multiple beams from a substrate using a conventional beam splitter.

[0034] Figure 5This is a schematic diagram illustrating a method for spatially separating multiple reflected light beams from a conventional substrate.

[0035] Figure 6 This is a schematic diagram illustrating the optical properties of a coated thin film obtained through the multiple beam splitter, beam spacing expander, and beam filter of the present invention.

[0036] Figure 7 Part (a) is a schematic diagram illustrating the use of a prism-based beam expander in the beam spacing expander of the present invention. Figure 7 Part (b) is a schematic diagram illustrating the use of a beam expander based on a pair of lenses in the beam spacing expander of the present invention.

[0037] Figure 8 This is a schematic diagram illustrating how the beam filter of the present invention uses a blocking screen or mirror to receive only a specific beam of light.

[0038] Figure 9 This is a schematic diagram illustrating the optical properties of a coated thin film obtained through the multiple beam splitter, beam spacing expander, beam filter, and beam deviation compensator of the present invention.

[0039] Figure 10 This is a schematic diagram illustrating the optical properties of a coated thin film obtained through the multiple beam splitter, beam filter, and beam deviation compensator of the present invention.

[0040] Figure 11 This is a schematic diagram illustrating the optical properties of a coated thin film obtained through the multi-beam splitter and beam filter of the present invention.

[0041] Figure 12 This is a schematic diagram illustrating the optical properties of a coated thin film obtained through the multi-beam splitter and beam deviation compensator of the present invention.

[0042] Figure 13 This is a flowchart illustrating a method for analyzing the optical properties of a coated thin film using the multiple beam splitter, beam spacing expander, beam filter, and beam deviation compensator of the present invention.

[0043] Figure 14 This is a flowchart illustrating a method for analyzing the optical properties of a coated thin film using the multiple beam splitter, beam filter, and beam deviation compensator of the present invention.

[0044] Figure 15 This is a flowchart illustrating a method for analyzing the optical properties of a coated thin film using the multiple beam splitter, beam spacing expander, and beam filter of the present invention.

[0045] Figure 16This is a flowchart illustrating a method for analyzing the optical properties of a coated thin film using the multi-beam splitter and beam filter of the present invention.

[0046] Figure 17 This is a flowchart illustrating a method for analyzing the optical properties of a coated thin film using the multi-beam splitter and beam deviation compensator of the present invention. Detailed Implementation

[0047] Hereinafter, an optical thin film analysis apparatus according to an embodiment of the present invention, which is unaffected by reflection from the back side of a substrate, will be described in detail with reference to the accompanying drawings.

[0048] An optical thin-film analysis apparatus according to an embodiment of the present invention, unaffected by back reflection of a substrate 40, includes: a light source 100 for emitting a light beam; a substrate 40 coated with a thin film 50 through which the light beam emitted by the light source 100 passes; a multiple beam splitter 400 located between the light source 100 and the substrate 40, for splitting the transmitted light beam 30 through the substrate 40 into multiple beams; a beam spacing expander 500 for expanding the spacing between the multiple beams passing through the substrate 40; a beam filter 600 for transmitting a portion of the beam expanded by the beam spacing expander 500 and reflecting the remainder; a beam deviation compensator 700 for compensating for deviations in the beams transmitted or reflected by the beam filter 600; and a photodetector 300 for receiving the beam whose deviation has been compensated by the beam deviation compensator 700.

[0049] An optical thin-film analysis apparatus according to an embodiment of the present invention, unaffected by back reflection of a substrate 40, includes: a light source 100 for emitting a light beam; a substrate 40 coated with a thin film 50 through which the light beam emitted by the light source 100 passes; a multiple beam splitter 400 located between the light source 100 and the substrate 40, for splitting the transmitted light beam 30 through the substrate 40 into multiple beams; a beam filter 600 for transmitting a portion of the multiple beams passing through the substrate 40 and reflecting the remainder; a beam deviation compensator 700 for compensating for deviations in the light beams transmitted or reflected by the beam filter 600; and a photodetector 300 for receiving the light beam with deviations compensated by the beam deviation compensator 700.

[0050] An optical thin-film analysis apparatus according to an embodiment of the present invention, unaffected by back reflection of a substrate 40, comprises: a light source 100 for emitting a light beam; a substrate 40 coated with a thin film 50 through which the light beam emitted by the light source 100 passes; a multiple beam splitter 400 located between the light source 100 and the substrate 40, for splitting the transmitted light beam 30 through the substrate 40 into multiple beams; a beam spacing expander 500 for expanding the spacing between the multiple beams passing through the substrate 40; a beam filter 600 for transmitting a portion of the beam expanded by the beam spacing expander 500 and reflecting the remainder; and a photodetector 300 for receiving the light beam transmitted or reflected by the beam filter 600.

[0051] An optical thin-film analysis apparatus according to an embodiment of the present invention, unaffected by back reflection of a substrate 40, includes: a light source 100 for emitting a light beam; a substrate 40 coated with a thin film 50 through which the light beam emitted by the light source 100 passes; a multiple beam splitter 400 located between the light source 100 and the substrate 40, for splitting the transmitted light beam 30 through the substrate 40 into multiple beams; a beam filter 600 for transmitting a portion of the multiple beams passing through the substrate 40 and reflecting the remainder; and a photodetector 300 for receiving the light beams transmitted or reflected by the beam filter 600.

[0052] An optical thin-film analysis apparatus according to an embodiment of the present invention, which is unaffected by back reflection of a substrate 40, includes: a light source 100 for emitting a light beam; a substrate 40 coated with a thin film 50 through which the light beam emitted by the light source 100 passes; a multiple beam splitter 400 located between the light source 100 and the substrate 40, for splitting the transmitted light beam 30 through the substrate 40 into multiple beams; a beam deviation compensator 700 for compensating for deviations in the light beam transmitted through the coated substrate 40; and a photodetector 300 for receiving the light beam whose deviation has been compensated by the beam deviation compensator 700.

[0053] The light source 100 can be a short-wavelength light source or a multi-wavelength light source.

[0054] The multiple beam splitter 400 may use a convex lens. When the convex lens is positioned in front of the thin film 50 sample, the multiple reflected beams 20 of the substrate 40 are focused independently, thus ultimately separating them spatially. The focal length of the lens of the multiple beam splitter 400 is preferably designed to be sufficiently small to satisfy the condition of Equation 1 below.

[0055] Formula 1

[0056] The diameter D of the beam at the focal point foc <<Multiple beam spacing Δ

[0057] In Equation 1, the beam diameter at the focal point is represented by D. foc =4λf / (πD in Here, D in D represents the diameter of the input beam. foc λ represents the diameter of the focused beam, λ represents the wavelength of the light, and f represents the focal length of the lens.

[0058] Figure 6 This is a schematic diagram illustrating the optical properties of the coated thin film 50 obtained through the multiple beam splitter 400, beam spacing expander 500, and beam filter 600 of the present invention. Figure 6 As shown, when the incident beam 10 irradiated from the light source 100 is obliquely incident on the substrate 40, it is divided into a reflected beam 20, which is partially reflected, and a transmitted beam 30, which is partially transmitted. When using a multiple beam splitter 400, the incident beam 10 before the multiple beam splitter 400 is defined as the first incident beam, and the incident beam 10 after the multiple beam splitter 400 is defined as the second incident beam. The Gaussian distribution of the second incident beam is formed to be narrower than that of the first incident beam. For example, in the first region 50R-1 of the thin film 50, the first incident beam is reflected by the first-1 reflected beam 20-1, and the first-1 transmitted beam 30-1 of the first incident beam is transmitted, which is reflected from the back side of the substrate 40. In the second region 50R-2 of the thin film 50, the first-2 reflected beam 20-2 is transmitted, and the first-2 transmitted beam 30-2 is reflected, which is reflected from the back side of the substrate 40. In the third region 50R-3 of the thin film 50, the first-3 reflected beam 20-3 is transmitted, and the first-3 transmitted beam 30-3 is reflected. When the multiplex beam splitter 400 is not used, the transmitted beam 30 is transmitted in such a way that the first-1 transmitted beam 30-1, the first-2 transmitted beam 30-2, and the first-3 transmitted beam 30-3 overlap with each other. However, when the multiplex beam splitter 400 is used, the transmitted beam is transmitted in such a way that the first-1 transmitted beam 30-1, the first-2 transmitted beam 30-2, and the first-3 transmitted beam 30-3 separate from each other. Therefore, when the photodetector receives only the first-1 transmitted beam 30-1, accurate measurements can be performed by minimizing the influence of the back side of the substrate 40 and improving the spatial resolution of the thin film 50.

[0059] The beam spacing expander 500 can further increase the spacing between the separated first-1 transmission beam 30-1, first-2 transmission beam 30-2, and first-3 transmission beam 30-3. If only the multiple beam splitter 400 is used, although the first-1 transmission beam 30-1, first-2 transmission beam 30-2, and first-3 transmission beam 30-3 are separated from each other, the distance between them is very short, making it difficult to remove the first-2 transmission beam 30-2 and the first-3 transmission beam 30-3 and measure only the first-1 transmission beam 30-1 using a photodetector. Therefore, the beam spacing expander 500 can be used to increase the spacing between the separated first-1 transmission beam 30-1, first-2 transmission beam 30-2, and first-3 transmission beam 30-3, etc.

[0060] Figure 7 Part (a) is a schematic diagram illustrating the use of prism-based beam expanders 510a and 520a in the beam spacing expander 500A of the present invention. Figure 7 Part (b) is a schematic diagram illustrating the beam spacing expander 500B of the present invention using beam expanders 510b, 520b based on a pair of lenses. Figure 7 As shown, the beam spacing expander 500 can use a prism-based beam expander ( Figure 7 (a) or a beam expander based on lens pairs ( Figure 7 (Part (b)). Prism-based beam expanders can consist of one or more prisms. The more prisms, the higher the magnification, but the manufacturing cost increases. Anamorphic prism pairs, including a first and a second prism, are convenient because the incident and outgoing beams travel in parallel directions. In lens-based beam expanders, the concave portion of a concave lens can be configured to face the incident beam, the flat portion of a concave lens to face the outgoing beam, the flat portion of a convex lens to face the beam exiting from the concave lens, and the convex portion of a convex lens to face the beam exiting from the convex lens. Since cylindrical lenses magnify the beam only in the horizontal direction, they are more useful than ordinary lenses.

[0061] When the beam spacing expander 500 uses a lens-based beam expander, it is preferable to satisfy the following equation 2 to perform beam expansion.

[0062] Formula 2

[0063] Focal length f of a concave lens cc Focal length f of the convex lens cx

[0064] Furthermore, the beam spacing expander 500 preferably satisfies the following formula 3 to maintain the mutual parallelism of multiple beams.

[0065] Formula 3

[0066] The distance d between the concave and convex lenses is equal to the focal length of the convex lens minus the focal length f of the concave lens. cx -f cc

[0067] The prism-based beam expander of the present invention has the advantage of having a smaller volume than the lens-based beam expander.

[0068] Figure 8 This is a schematic diagram illustrating how the beam filter 600 of the present invention uses a shielding screen and a mirror to receive a beam. For example... Figure 8 As shown, the beam filter 600 can utilize a shield or a mirror. A shield-type beam filter 600 blocks the path of the beam. Conversely, a mirror-type beam filter 600 reflects the beam to be blocked in different directions. The mirror-type beam filter 600 can use a knife-edge right-angle prism mirror. A knife-edge right-angle prism mirror has a mirror surface on at least one face of a triangle. The transmitted beam 30 is incident on the mirror surface at 45°, and the incident transmitted beam 30 is reflected by the mirror surface. The reflected transmitted beam 30D is received by a side-transmitting photodetector 300D. The beam filter 600 is preferably positioned near the focal point, providing good spatial separation for the transmitted beam 30. Slits or pinholes 310 can be provided in the beam filter 600 and the side-transmitting photodetector 300D to allow a portion 30-2D of the reflected transmitted beam to be transmitted.

[0069] On the other hand, when the direction parallel to the rotation axis of the substrate 40 is defined as the -y-axis direction, the direction of the transmitted beam 30 traveling from the substrate 40 to the beam filter 600 is defined as the z-axis direction, and the direction of the transmitted beam 30 after being reflected by the beam filter 600 is defined as the -x-axis direction, the beam filter 600 moves in the -x-axis direction due to the rotation of the substrate 40. For example, as the incident angle of the incident beam 10 increases, the beam filter 600 moves in the -x-axis direction to approach the side-transmitting photodetector 300D. Therefore, even if the substrate 40 rotates and the transmitted beam 30 deviates in the -x-axis direction, the mirror-reflected transmitted beam 30D will be received by the side-transmitting photodetector 300D because the beam filter 600 moves in conjunction with it. The beam filter 600 can be mounted on a moving device of the x-axis platform to control its position. When the beam filter 600 is a mirror type, the position of the beam filter 600 can be controlled in a feedback manner by measuring the reflected beam through the side-transmitting photodetector 300D.

[0070] Figure 9 This is a schematic diagram illustrating the optical properties of the coated thin film 50 obtained by means of the multiple beam splitter 400, beam spacing expander 500, beam filter 600, and beam deviation compensator 700 of the present invention. Figure 9 As shown, a beam deviation compensator 700 may be required. Due to refraction on the substrate 40, the beam deviates after passing through the thin-film-coated substrate 40. The beam deviation X caused by the thin-film-coated substrate 40 is represented by Equation 4.

[0071] Formula 4

[0072] X=d s (sinθ) i -cosθ i tanθ s )

[0073] (In Equation 4, sinθ exists) i =n s sinθ s The relationship, n s d s θ i θ s These represent the refractive index of substrate 40, the thickness of substrate 40, the angle of incidence, and the angle of refraction of substrate 40, respectively.

[0074] As can be seen from Equation 4, the beam deviation increases monotonically with increasing incident angle. The beam deviation caused by the thin-film-coated substrate 40 is further amplified by the beam spacing expander 500, thus, changes in the incident angle can significantly alter the incident position of the measurement beam at the photodetector. A convex lens can be used to compensate for this problem. If a convex lens is positioned in front of the photodetector to compensate for the beam deviation, the measurement beam can be fixed at a specific position on the photodetector regardless of changes in the incident angle.

[0075] In order to compensate for the beam deviation caused by the substrate 40 coated with a thin film, it is preferable to satisfy Equation 5.

[0076] Formula 5

[0077] The distance D between the beam deviation compensator 700 and the transparent beam photodetector C-D =Focal length f of beam deviation compensator 700 C

[0078] If the beam deviation compensator 700 is positioned such that the distance D between the focal point of the transmitted beam 30 and the beam deviation compensator 700 is satisfied... f-C The focal length f of the beam deviation compensator 700 C At the desired location, the beam is prevented from refocusing, thus allowing the beam to be incident on the transparent beam photodetector with the desired diameter.

[0079] Figure 9 The text describes a beam deviation compensated by a beam deviation compensator after the beam is received by a transparent photodetector and transmitted through a beam filter. However, it also describes a beam that can be received from a side-transparent photodetector... Figure 8 The beam reflected by the beam filter shown is compensated for by the beam deviation compensator.

[0080] Figure 10 This is a schematic diagram illustrating the optical properties of a coated thin film obtained through the multiple beam splitter 400, beam filter 600, and beam deviation compensator 700 of the present invention. Figure 10 As shown, when using the multiple beam splitter 400, beam filter 600 and beam deviation compensator 700, it has the advantage of being applicable to situations where the substrate of the thin film is thick enough and the beam spacing is large enough, so the beam spacing expander 500 is not required.

[0081] Figure 11 This is a schematic diagram illustrating the optical properties of the coated thin film obtained through the multiple beam splitter 400 and beam filter 600 of the present invention. Figure 11As shown, when using the multiple beam splitter 400 and the beam filter 600, it has the advantage of being applicable to situations where the substrate of the thin film is thick enough and the beam spacing is large enough, so the beam spacing expander 500 is not needed, and the photodetector receiver is wide enough and the light response is uniform enough, so the beam deviation compensator 700 is not needed.

[0082] Figure 12 This is a schematic diagram illustrating the optical properties of the coated thin film 50 obtained through the multi-beam splitter 400 and beam deviation compensator 700 of the present invention. Figure 12 As shown, when a beam is transmitted through a substrate 40 coated with a thin film, the beam deviation compensator 700 can compensate for beam deviation and separation. That is, as... Figure 3 As shown, an improved thin-film analysis method can be obtained by adding only the beam deviation compensator 700 to a conventional thin-film analysis method consisting of a light source 100, a multiplexer 400, and a photodetector. Since the beam deviation compensator 700 here also performs the function of focusing the separated multiple beams together, it can be considered as a beam deviation and separation compensator. When additional beam deviation and separation compensators are configured, it has the advantage that all multiple beams can be collected at the same position on the photodetector regardless of changes in the incident angle.

[0083] Figure 13 This is a flowchart illustrating a method for analyzing the optical properties of a coated thin film 50 using the multi-beam splitter 400, beam spacing expander 500, beam filter 600, and beam deviation compensator 700 of the present invention. Figure 13 As shown, an optical thin film analysis method according to an embodiment of the present invention, unaffected by back reflection of substrate 40, includes: a first step S10, in which a light beam is emitted from a light source 100; a second step S20, in which the light beam emitted in the first step passes through a multiple beam splitter 400; a third step S30, in which the light beam passing through the multiple beam splitter 400 passes through a substrate 40 coated with a thin film and is split into multiple beams; a fourth step S40, in which the multiple beams of the third step are passed through a beam spacing expander 500 to expand the beam spacing; a fifth step S50, in which a portion of the expanded beam in the fourth step is passed through a beam filter 600 to maintain the beam path and the remainder is reflected; a sixth step S60, in which the beam that maintains the path or the reflected beam in the fifth step is passed through a beam deviation compensator 700 to compensate for beam deviation; and a seventh step S70, in which a photodetector receives the beam whose deviation was compensated in the sixth step.

[0084] The first step is the step of emitting a light beam from the light source 100. The light source 100 can use short wavelengths or multiple wavelengths.

[0085] In the second step, the beam emitted from the light source 100 passes through a multiple beam splitter 400. The multiple beam splitter may use a convex lens. By using the multiple beam splitter 400, a narrow Gaussian distribution of multiple beams is generated as the beam passes through the inclined substrate 40, thereby separating the beams.

[0086] The third step involves passing a beam of light from a multi-beam splitter 400 through a substrate 40 coated with a thin film. The substrate 40 is mounted on a rotating support. To measure the optical properties of the thinner film 50, the beam is incident at a specific angle and undergoes multiple reflections on the back and front sides of the substrate 40. The beam passing through the back side of the substrate 40 travels in the form of multiple beams.

[0087] The fourth step involves expanding the beam spacing using the beam spacing expander 500. Although the beam is split into multiple beams using only the multiple beam splitter 400, the spacing between the separated beams remains narrow, making them difficult to separate and detect by a transparent photodetector. Therefore, it is necessary to expand the spacing between the multiple beams to make them easier to separate and detect by a transparent photodetector.

[0088] The fifth step involves passing a portion of the extended beam through the beam filter 600 to maintain the beam path while the remainder is reflected. This step involves either maintaining the path of a portion of the beam through the beam filter 600 and receiving and measuring it, or reflecting the remainder of the beam through the beam filter 600 and receiving and measuring it, in order to obtain the optical properties of a beam that transmits only through a specific area of ​​the substrate 40 coated with the thin film, thereby filtering the desired beam from the separated beams.

[0089] The sixth step is to compensate for beam deviation by passing the transmitted or reflected beam through the beam deviation compensator 700. For the transmitted beam in the sixth step, the beam deviation compensator 700 can be located on the front surface of the transparent beam photodetector 300, and for the reflected beam in the sixth step, the beam deviation compensator (not shown) can be located on the front surface of the side-transparent photodetector 300D.

[0090] The seventh step is the step of receiving the beam whose deviation has been compensated by the beam deviation compensator 700 by the light-transmitting beam photodetector 300 or the side-transmitting beam photodetector 300D.

[0091] Figure 14 This is a flowchart illustrating a method for analyzing the optical properties of a coated thin film 50 using the multi-beam splitter 400, beam filter 600, and beam deviation compensator 700 of the present invention. Figure 14As shown, an optical thin film analysis method according to an embodiment of the present invention, unaffected by back reflection of substrate 40, includes: a first step R10, in which a light beam is emitted from a light source 100; a second step R20, in which the light beam emitted in the first step passes through a multiple beam splitter 400; a third step R30, in which the light beam passing through the multiple beam splitter 400 passes through a substrate 40 coated with a thin film and is split into multiple beams; a fourth step R40, in which a portion of the multiple beams from the third step passes through a beam filter 600 to maintain the beam path while the remainder is reflected; a fifth step R50, in which the beam that maintains the path or the reflected beam from the fourth step passes through a beam deviation compensator 700 to compensate for beam deviation; and a sixth step R60, in which a photodetector receives the beam whose deviation was compensated in the fifth step.

[0092] Because of the fact that, in addition to Figure 13 Except for the fourth step (the beam spreading step) in the method for analyzing the optical properties of the coated thin film 50, the other steps are the same, therefore... Figure 14 Detailed descriptions will be omitted.

[0093] Figure 15 This is a flowchart illustrating a method for analyzing the optical properties of a coated thin film 50 using the multi-beam splitter 400, beam spacing expander 500, and beam filter 600 of the present invention. Figure 15 As shown, an optical thin film analysis method according to an embodiment of the present invention, unaffected by back reflection of substrate 40, includes: a first step Q10, in which a light beam is emitted from a light source 100; a second step Q20, in which the light beam emitted in the first step passes through a multiple beam splitter 400; a third step Q30, in which the light beam passing through the multiple beam splitter 400 passes through a substrate 40 coated with a thin film and is split into multiple beams; a fourth step Q40, in which the multiple beams of the third step are passed through a beam spacing expander 500 to expand the beam spacing; a fifth step Q50, in which a portion of the expanded beam in the fourth step passes through a beam filter 600 to maintain the beam path and the remainder is reflected; and a sixth step Q60, in which a photodetector receives the beam that maintained the path or the reflected beam in the fifth step.

[0094] Because of the fact that, in addition to Figure 13 Except for the sixth step (the step of compensating for beam deviation by the beam deviation compensator 700) in the method for analyzing the optical properties of the coated thin film 50, the other steps are the same. Figure 15 Detailed descriptions will be omitted.

[0095] Figure 16This is a flowchart illustrating a method for analyzing the optical properties of a coated thin film 50 using the multi-beam splitter 400 and beam filter 600 of the present invention. Figure 16 As shown, an optical thin film analysis method according to an embodiment of the present invention, which is unaffected by back reflection of substrate 40, includes: a first step P10, in which a light beam is emitted from a light source 100; a second step P20, in which the light beam emitted in the first step passes through a multiple beam splitter 400; a third step P30, in which the light beam passing through the multiple beam splitter 400 passes through a substrate 40 coated with a thin film and is split into multiple beams; a fourth step P40, in which a portion of the multiple beams in the third step is passed through a beam filter 600 to maintain the beam path and the remainder is reflected; and a fifth step P50, in which a photodetector receives the beam that maintained the path or the reflected beam in the fourth step.

[0096] Because of the fact that, in addition to Figure 13 Except for the fourth step (the step of beam spacing expansion when multiple beams pass through beam spacing expander 500) and the sixth step (the step of compensating for beam deviation when transmitted or reflected beams pass through beam deviation compensator 700) in the method for analyzing the optical properties of coated thin film 50, the other steps are the same. Figure 16 Detailed descriptions will be omitted.

[0097] Figure 17 This is a flowchart illustrating a method for analyzing the optical properties of a coated thin film 50 using the multi-beam splitter 400 and beam deviation compensator 700 of the present invention. Figure 17 As shown, an optical thin film analysis method according to an embodiment of the present invention, which is unaffected by back reflection of substrate 40, includes: a first step T10, in which a light beam is emitted from a light source 100; a second step T20, in which the light beam emitted in the first step passes through a multiple beam splitter 400; a third step T30, in which the light beam passing through the multiple beam splitter 400 passes through a substrate 40 coated with a thin film to split it into multiple beams; a fourth step T40, in which the multiple beams of the third step pass through a beam deviation compensator 700 to compensate for beam deviation; and a fifth step T50, in which a photodetector receives the beam whose deviation was compensated in the fourth step.

[0098] Because of the fact that, in addition to Figure 13 Except for the fourth step (the step of widening the beam spacing) and the fifth step (the step of transmission or reflection through the beam filter 600) in the method for analyzing the optical properties of the coated thin film 50, the other steps are the same. Figure 17 Detailed explanation omitted.

[0099] Although the above embodiments have been described using limited examples and drawings, those skilled in the art can make various modifications and variations based on the above description. For example, suitable results can be obtained by performing the described techniques in a different order than the described methods and / or by combining or integrating the constituent elements of the described systems, structures, devices, circuits, etc., in a different form than the described methods, or by substituting or replacing them with other constituent elements or equivalents. Therefore, other embodiments, other examples, and equivalents of the claims also fall within the scope of the claims described below.

Claims

1. An optical thin-film analysis device unaffected by reflections from the back of a substrate, characterized in that, include: Light source, emitting beams of light; A substrate coated with a thin film, through which a light beam emitted by the light source passes; A multi-beam splitter is located between the light source and the substrate, and splits the transmitted beam from the substrate into multiple beams; A beam spacing expander for expanding the spacing between the multiple beams that have been separated into several beams; A beam filter that allows a portion of the beam expanded by the beam spacing expander to be transmitted and the remainder to be reflected; A beam deviation compensator compensates for deviations in the beam transmitted or reflected by the beam filter; and A light-transmitting photodetector receives a beam whose deviation has been compensated by the beam deviation compensator.

2. An optical thin-film analysis device unaffected by reflections from the back side of a substrate, characterized in that, include: Light source, emitting beams of light; A substrate coated with a thin film, through which a light beam emitted by the light source passes; A multi-beam splitter is located between the light source and the substrate, and splits the transmitted beam from the substrate into multiple beams; A beam filter that allows a portion of the multiple beams, split into several parts, to be transmitted and the remainder to be reflected; A beam deviation compensator compensates for deviations in the beam transmitted or reflected by the beam filter; and A light-transmitting photodetector receives a beam whose deviation has been compensated by the beam deviation compensator.

3. An optical thin-film analysis device unaffected by reflections from the back side of a substrate, characterized in that, include: Light source, emitting beams of light; A substrate coated with a thin film, through which a light beam emitted by the light source passes; A multi-beam splitter is located between the light source and the substrate, and splits the transmitted beam from the substrate into multiple beams; A beam spacing expander for expanding the spacing between the multiple beams that have been separated into several beams; A beam filter that allows a portion of the beam expanded by the beam spacing expander to be transmitted and the remainder to be reflected; as well as A light-transmitting photodetector receives a light beam transmitted or reflected by the beam filter.

4. An optical thin-film analysis device unaffected by reflections from the back side of a substrate, characterized in that, include: Light source, emits a beam of light; A substrate coated with a thin film, through which a light beam emitted by the light source passes; A multi-beam splitter is located between the light source and the substrate, and splits the transmitted beam from the substrate into multiple beams; A beam filter that allows a portion of the multiple beams, split into several parts, to be transmitted and the remainder to be reflected; as well as A light-transmitting photodetector receives a light beam transmitted or reflected by the beam filter.

5. An optical thin-film analysis device unaffected by reflections from the back side of a substrate, characterized in that, include: Light source, emits a beam of light; A substrate coated with a thin film, through which a light beam emitted by the light source passes; A multi-beam splitter is located between the light source and the substrate, and splits the transmitted beam from the substrate into multiple beams; A beam deviation compensator compensates for the deviation and separation of the multiple beams that have been split into multiple parts; and A light-transmitting photodetector receives a beam whose deviation and separation have been compensated by the beam deviation compensator.

6. The optical thin film analysis apparatus according to any one of claims 1 to 5, unaffected by backside reflection of the substrate, characterized in that, The light source is short-wavelength or multi-wavelength, and the polarized light of the light beam is either s-polarized light or p-polarized light or a variable direction of s-polarized light and p-polarized light.

7. The optical thin film analysis apparatus according to any one of claims 1 to 5, characterized in that, When the light beam emitted from the light source before passing through the substrate is defined as the incident light beam, the light beam after passing through the substrate is defined as the transmitted light beam, and the light beam after being reflected by the substrate is defined as the reflected light beam, the substrate rotates via the substrate support, and the rotation axis of the substrate rotates with reference to a direction perpendicular to the plane formed by the incident light beam, the reflected light beam, and the transmitted light beam.

8. The optical thin film analysis apparatus according to any one of claims 1 to 5, characterized in that, The multiple beam splitter is a convex lens.

9. The optical thin film analysis apparatus according to claim 1 or 3, which is unaffected by reflection from the back side of the substrate, is characterized in that, The beam spacing expander is either a prism-based beam expander or a pair of lenses-based beam expander.

10. The optical thin film analysis apparatus according to any one of claims 1 to 4, characterized in that, The beam filter is a shield or a mirror.

11. The optical thin film analysis apparatus according to any one of claims 1, 2, and 5, characterized in that, The beam deviation compensator is a convex lens.

12. A method for analyzing optical thin films unaffected by reflections from the back side of a substrate, characterized in that, include: The first step is for a light source to emit a beam of light; The second step is that the beam emitted in the first step is transmitted through a multi-beam splitter. The third step involves the beam transmitted through the multi-beam splitter being transmitted through a substrate coated with a thin film and separated into multiple beams. The fourth step involves extending the beam spacing by transmitting the multiple beams from the third step through the beam spacing expander. The fifth step involves transmitting a portion of the expanded beam from the fourth step through a beam filter while the remainder is reflected. The sixth step involves ensuring that the transmitted or reflected beam from the fifth step is compensated for by a beam deviation compensator; and The seventh step involves the photodetector receiving the beam that compensated for the deviation in the sixth step.

13. A method for analyzing optical thin films unaffected by reflections from the back side of a substrate, characterized in that, include: The first step is for a light source to emit a beam of light; The second step is that the beam emitted in the first step is transmitted through a multi-beam splitter. The third step involves the beam transmitted through the multi-beam splitter being transmitted through a substrate coated with a thin film and separated into multiple beams. The fourth step involves transmitting a portion of the multiple beams from the third step through a beam filter while the remainder is reflected. The fifth step involves ensuring that the transmitted or reflected beam from the fourth step is compensated for by a beam deviation compensator; and The sixth step involves the photodetector receiving the beam that compensated for the deviation in the fifth step.

14. A method for analyzing optical thin films unaffected by reflections from the back surface of a substrate, characterized in that, include: The first step is for a light source to emit a beam of light; The second step is that the beam emitted in the first step is transmitted through a multi-beam splitter. The third step involves the beam transmitted through the multi-beam splitter being transmitted through a substrate coated with a thin film and separated into multiple beams. The fourth step involves extending the beam spacing by transmitting the multiple beams from the third step through the beam spacing expander. The fifth step involves transmitting a portion of the expanded beam from the fourth step through a beam filter while the remainder is reflected; and The sixth step involves the photodetector receiving the light beam transmitted or reflected in the fifth step.

15. A method for analyzing optical thin films unaffected by reflections from the back surface of a substrate, characterized in that, include: The first step is for a light source to emit a beam of light; The second step is that the beam emitted in the first step is transmitted through a multi-beam splitter. The third step involves the beam transmitted through the multi-beam splitter being transmitted through a substrate coated with a thin film and separated into multiple beams. The fourth step involves transmitting a portion of the multiple beams from the third step through a beam filter while the remainder is reflected; and The fifth step involves the photodetector receiving the light beam transmitted or reflected in the fourth step.

16. A method for analyzing optical thin films unaffected by reflections from the back surface of a substrate, characterized in that, include: The first step is for a light source to emit a beam of light; The second step is that the beam emitted in the first step is transmitted through a multi-beam splitter. The third step is to separate the beam transmitted through the multi-beam splitter into multiple beams by transmitting it through a substrate coated with a thin film. The fourth step involves using a beam deviation compensator to compensate for beam deviation and separation in the multiple beams generated in the third step; and The fifth step involves the photodetector receiving the beam that compensated for the deviation in the fourth step.

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