Optical thin film analysis apparatus not affected by backside reflection of substrate and analysis method by same

Abstract

The present invention relates to an optical thin film analysis apparatus not affected by backside reflection of a substrate and an analysis method by same, and more specifically, to an optical thin film analysis apparatus not affected by backside reflection of a substrate that can simultaneously measure the thickness of a thin film, and the refractive index and extinction coefficient as optical constants of the thin film using an optical method and an analysis method by same, and to an optical thin film analysis apparatus that simultaneously measures the thickness of a thin film and an optical constant with improved spatial resolution and measurement accuracy by solving a reflection problem on the backside of a substrate and an analysis method by same.

Description

Optical thin film analysis device not affected by backside reflection of substrate and analysis method using the same

[0001] The present invention relates to an optical thin film analysis device that is not affected by the reflection from the back of a substrate and an analysis method therefor, and more specifically, to an optical thin film analysis device that is not affected by the reflection from the back of a substrate and an analysis method therefor that can simultaneously measure the thickness and optical constants, such as the refractive index and the extinction coefficient, of a thin film by an optical method, and to an optical thin film analysis device that is not affected by the reflection from the back of a substrate and an analysis method therefor that can simultaneously measure the thickness and optical constants of a thin film with improved spatial resolution and measurement precision by solving the reflection problem from the back of a substrate.

[0002] Since various research materials are fabricated as thin film samples on substrates, measuring the thickness of these thin film samples is a crucial task in materials research. Optical methods for measuring thin film thickness are known to be highly useful because they utilize non-contact and non-destructive methods. Furthermore, when materials are used in optics, optical constants such as refractive index and extinction coefficient must also be measured, making optical thin film analysis methods crucial.

[0003] Meanwhile, ellipsometry (see Non-patent Document 1), spectral reflectance analysis (see Non-patent Document 2), spectral transmission analysis (see Non-patent Document 2), and nonspectroscopic transmission analysis (see Non-patent Document 3) are being used as optical thin film analysis methods.

[0004] However, when the substrate of the thin film is not thick (which is realistically the case for most thin film samples), optical thin film analysis methods suffer from beam reflection from the back of the substrate.

[0005] FIG. 1 is a schematic diagram showing a portion of a light beam passing through a substrate (40) and a portion of the light beam being reflected by the substrate (40). As shown in FIG. 1, a portion of the incident light beam (10) is divided into a light beam (20-1) reflected from a specific area (50R-1) on the front surface of the substrate (40) and a light beam transmitted therethrough. Here, the transmitted light beam is divided into a light beam reflected again from the back surface of the substrate (40) and a light beam transmitted therethrough (30-1). Here, the reflected light beam is further divided into a light beam reflected from an area (50R-2) on the front surface of the substrate (40) and a light beam transmitted therethrough (20-2). Here, the reflected light beam is further divided into a light beam reflected from the back surface of the substrate (40) and a light beam transmitted therethrough (30-2). Here, the reflected light beam is divided into a light beam reflected from an area (50R-3) on the front surface of the substrate (40) and a transmitted light beam (20-3). The reflected light beam is divided into a light beam reflected from the back surface of the substrate (40) and a transmitted light beam (30-3). Here, the reflected light beam continues to be reflected repeatedly from the front and back surfaces of the substrate (40). Therefore, the reflected light beam (20) is composed of multiple light beams such as 20-1, 20-2, 20-3, etc., and the transmitted light beam (30) is composed of multiple light beams such as 30-1, 30-2, 30-3, etc. The spacing (Δ) between the multiple light beams is Δ=2d. s cosθ i tanθ s (Here, sinθ i =n s sinθ s ) can be expressed as, where n s , d s , θ i , θ s Each represents the refractive index of the substrate (40), the thickness of the substrate (40), the incident angle, and the refraction angle at the substrate (40).

[0006] Fig. 2 shows the change in spacing of light rays multiple times reflected from the substrate (40) with respect to the incident angle of the light rays on the substrate (40). Fig. 2 is for a glass substrate with a 'refractive index = 1.5'. From Fig. 2, it can be seen that in the case of a thin glass substrate with a 'refractive index = 1.5, thickness = 1 mm', the spacing of light rays has a very small value in the numerical range of 0-0.76 mm. Due to such a small spacing of light rays, the multiple reflections of light rays on the substrate spatially overlap. Therefore, when the multiple reflections of light rays on the substrate spatially overlap, the light rays cause mutual interference with each other. The mutual interference of the multiple reflections of light rays on the substrate causes an error in the analysis of the thin film (50), making it difficult to obtain accurate measurement values. In addition, if there is a back reflection of the substrate (40), not only a specific area of ​​the thin film (50) (the area to be analyzed, 50R-1) but also the adjacent areas (50R-2, 50R-3, etc.) of the specific area (50R-1) are measured. This reduces the spatial resolution of the thin film (50) analysis. Furthermore, if the uniformity of the thin film (50) is poor, there is a problem of low measurement precision.

[0007] Fig. 3 is a schematic diagram showing a method of preventing reflection from the back surface of a substrate (40) by forming unevenness (60) on the back surface of a substrate (40) to eliminate the influence of the back surface of a conventional substrate (40). As shown in Fig. 3, when the back surface of a substrate (40) is roughly processed to form unevenness (60), reflection of light is blocked. The reflected light (20) is detected by a reflection light detector (200). This method is a method for solving the problem of reflection from the back surface of a substrate (40) and is mainly used in ellipsometry or spectroscopic reflectance analysis.

[0008] Fig. 4 is a schematic diagram of a method for preventing mutual interference of multiple light beams of a substrate (40) using a conventional spectral light source (100). As shown in Fig. 4, mutual interference of multiple light beams of a substrate (40) can be prevented using a spectral light source (100). When the spectral light source (100) is used as a light source (100) to receive and analyze light beams measured by a reflection light detector (200) and a transmission light detector (300), the effective coherence length of the light beams can be sufficiently reduced to prevent mutual interference of multiple light beams of the substrate (40). In addition, when the incident angle is almost 0 o By using a method of making the (vertical incidence) small (where the spacing between multiple light beams becomes almost 0), it is possible to include only a specific area (50R-1) of the thin film (50) in the measurement. This method can be applied to spectroscopic reflectance analysis and spectroscopic transmission analysis as a method for solving the problem of back reflection of the substrate (40).

[0009] Figure 5 schematically illustrates a method for spatially separating multiple reflected light beams on a conventional substrate. As shown in Figure 5, multiple reflected light beams can be spatially separated. By focusing the incident light beam (10) to reduce its diameter and selecting an appropriate angle of incidence, the light beams can be spatially separated. Therefore, since the light beams are spatially separated, mutual interference between the light beams does not occur. To obtain reliable analysis results, it is generally recommended to use a light source (100) with multiple wavelengths rather than a single wavelength and to perform measurements for multiple angles of incidence rather than a single wavelength. However, the problem still remains that a wide area, not just a specific region (50R-1) of the thin film (50), is included in the measurement. This method partially, but not completely, resolves the issue of backside reflection of the substrate (40) and is used in nonspectroscopic transmission analysis. However, this method has the advantage of being applicable to nonspectroscopic thin film analysis methods. Because it is a non-spectral method, it has the advantage of a simple analysis mechanism and can be used to analyze new or unknown substances.

[0010] However, the above-described method is insufficient for analyzing the optical properties of thin films with high accuracy, and research and development in this area is needed.

[0011] <Prior Art Literature>

[0012] Patent Document

[0013] (Patent Document 1) Reference Patent Document 1: Japanese Patent Application Laid-Open No. 2003-302334

[0014] (Patent Document 2) Reference Patent Document 2: Japanese Patent Application Laid-Open No. 2003-506697

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

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

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

[0018] <Non-patent literature>

[0019] (Non-patent literature 1) Lee Je-Hyeon, Park Min-Su, Yang Seong-Mo, Park Sang-Wook, Lee Min-Ho, Kim Sang-Yeol, Precise Measurement of Ultrafine Optical Anisotropy of Rubbed Polyimide Alignment Films Using a Reflective Ellipsometer, Journal of the Korean Optical Society, Vol. 26 (No. 4), 195-202 (2015)

[0020] (Non-patent Document 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. Full text of 45 (19), 4547-4553 (2006)

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

[0022] Non-spectral transmittance analysis, a conventional thin film analysis method that spatially separates multiple reflected light beams from a substrate, offers significant advantages over non-spectral methods. However, it also involves measuring a wide area of ​​the thin film, rather than just a specific region. This limits the spatial resolution and measurement precision of thin film analysis.

[0023] The present invention is intended to solve the above problems, and provides an optical thin film analysis device and an analysis method using the same, which can simultaneously measure the thickness and optical constants (refractive index, extinction coefficient) of a thin film by an optical method, and which solves the reflection problem on the back of a substrate to simultaneously measure the thickness and optical constants of a thin film with improved spatial resolution and measurement precision.

[0024] An optical thin film analysis device that is not affected by the reflection from the back surface of a substrate, according to one embodiment of the present invention, comprises: a light source that emits light; a substrate coated with a thin film through which light emitted from the light source is transmitted; a multi-beam splitter positioned between the light source and the substrate that splits transmitted light passing through the substrate into multiple beams; a beam spacing expander that expands the spacing of multiple beams transmitted through the substrate; a beam filter that transmits a portion of the light beam expanded by the beam spacing expander and reflects the remaining portion; a beam deviation compensator that compensates for a deviation of light beams transmitted or reflected by the beam filter; and a light detector for transmitting light beams that receive light beams whose deviation has been compensated for by the beam deviation compensator.

[0025] An optical thin film analysis method that is not affected by the back surface reflection of a substrate according to one embodiment of the present invention comprises: a first step of emitting light from a light source; a second step of transmitting the light emitted in the first step through a multi-beam splitter; a third step of transmitting the light transmitted through the multi-beam splitter through a thin film-coated substrate and separating the light into multiple light beams; a fourth step of transmitting the multiple light beams through a beam gap expander and expanding the intervals between the light beams; a fifth step of transmitting a portion of the light beams expanded in the fourth step through a beam filter and reflecting the remaining portions of the light beams; a sixth step of transmitting or reflecting the light beams transmitted in the fifth step through a beam gap compensator and compensating for the deviation of the light beams; and a seventh step of receiving the light beams whose deviation has been compensated for in the sixth step through a photodetector.

[0026] According to the optical thin film analysis device of the present invention and the analysis method thereof, the problem of reflection from the back of a substrate is solved, thereby achieving the effect of simultaneously measuring the thickness and optical constant of a thin film with improved spatial resolution and measurement precision.

[0027] Figure 1 shows a schematic diagram in which a portion of light passes through a substrate and the remaining portion is reflected by the substrate.

[0028] Figure 2 shows the change in spacing between multiple reflected light rays from a substrate with respect to the incident angle of the light rays on the substrate.

[0029] Figure 3 shows a schematic diagram of preventing backside reflection of a substrate by forming a protrusion on the backside of a substrate to eliminate the influence of the backside of a conventional substrate.

[0030] Figure 4 shows a schematic diagram of a method for preventing mutual interference of multiple light beams on a substrate using a conventional spectral light source.

[0031] Figure 5 shows a schematic diagram of a method for spatially separating multiple reflected light beams of a conventional substrate.

[0032] Figure 6 shows a schematic diagram for obtaining optical properties of a thin film coated through a multi-beam splitter, a beam gap expander, and a beam filter of the present invention.

[0033] FIG. 7(a) shows a schematic diagram of a beam spacing expander of the present invention using a prism-based beam expander, and FIG. 7(b) shows a schematic diagram of a beam spacing expander of the present invention using a pair of lens-based beam expanders.

[0034] Figure 8 is a schematic diagram showing a light filter of the present invention that receives only specific light rays by using a blocking screen or mirror.

[0035] Figure 9 shows a schematic diagram for obtaining optical characteristics of a coated thin film through a multi-beam splitter, a beam gap expander, a beam filter, and a beam deviation compensator of the present invention.

[0036] Figure 10 shows a schematic diagram for obtaining optical properties of a coated thin film through a multi-beam splitter, a beam filter, and a beam deviation compensator of the present invention.

[0037] Figure 11 shows a schematic diagram for obtaining optical properties of a thin film coated through a multi-beam splitter and a beam filter of the present invention.

[0038] Figure 12 shows a schematic diagram for obtaining optical characteristics of a coated thin film through a multi-beam splitter and a beam deviation compensator of the present invention.

[0039] FIG. 13 shows a flow chart of a method for analyzing optical properties of a coated thin film using a multi-beam splitter, a beam gap expander, a beam filter, and a beam deviation compensator of the present invention.

[0040] FIG. 14 shows a flow chart of a method for analyzing the optical properties of a coated thin film using a multi-beam splitter, a beam filter, and a beam deviation compensator of the present invention.

[0041] FIG. 15 shows a flow chart of a method for analyzing the optical properties of a coated thin film using a multi-beam splitter, a beam gap expander, and a beam filter of the present invention.

[0042] Figure 16 shows a flow chart of a method for analyzing the optical properties of a coated thin film using a multi-beam splitter and a beam filter of the present invention.

[0043] Figure 17 shows a flow chart of a method for analyzing the optical properties of a coated thin film using a multi-beam splitter and a beam deviation compensator of the present invention.

[0044] Below, with reference to the drawings, an optical thin film analysis device that is not affected by the back surface reflection of a substrate, which is one embodiment of the present invention, is specifically described.

[0045] An optical thin film analysis device that is not affected by the back reflection of a substrate (40), which is one embodiment of the present invention, comprises: a light source (100) that emits light; a substrate (40) coated with a thin film (50) through which light emitted from the light source (100) is transmitted; a multi-beam splitter (400) positioned between the light source (100) and the substrate (40) and separating the transmitted light beam (30) passing through the substrate (40) into several beams; a beam spacing expander (500) that expands the intervals of the multiple beams passing through the substrate (40); a beam filter (600) that transmits a portion of the light beam expanded by the beam spacing expander (500) and reflects the remaining portion; a beam deviation compensator (700) that compensates for the deviation of the light beam transmitted or reflected by the beam filter (600); And it includes a photodetector (300) that receives the light beam whose deviation has been compensated in the light beam deviation compensator (700).

[0046] An optical thin film analysis device that is not affected by the back reflection of a substrate (40), which is one embodiment of the present invention, comprises: a light source (100) that emits light; a substrate (40) coated with a thin film (50) through which light emitted from the light source (100) is transmitted; a multi-beam splitter (400) positioned between the light source (100) and the substrate (40) and splitting the transmitted light (30) passing through the substrate (40) into several beams; a beam filter (600) that transmits a portion of the multiple beams passing through the substrate (40) and reflects the remaining portions; a beam deviation compensator (700) that compensates for a deviation of the beams transmitted or reflected by the beam filter (600); and a photodetector (300) that receives the beams whose deviation is compensated for by the beam deviation compensator (700).

[0047] An optical thin film analysis device that is not affected by the back reflection of a substrate (40), which is one embodiment of the present invention, comprises: a light source (100) that emits light; a substrate (40) coated with a thin film (50) through which light emitted from the light source (100) is transmitted; a multi-beam splitter (400) positioned between the light source (100) and the substrate (40) and separating the transmitted light beam (30) passing through the substrate (40) into several beams; a beam spacing expander (500) that expands the spacing of the multiple beams passing through the substrate (40); a beam filter (600) that transmits a portion of the light beam expanded by the beam spacing expander (500) and reflects the remaining portion; and a photodetector (300) that receives the light beam transmitted or reflected by the beam filter (600).

[0048] An optical thin film analysis device that is not affected by the back reflection of a substrate (40), which is one embodiment of the present invention, comprises: a light source (100) that emits light; a substrate (40) coated with a thin film (50) through which light emitted from the light source (100) is transmitted; a multi-beam splitter (400) positioned between the light source (100) and the substrate (40) and splitting the transmitted light (30) passing through the substrate (40) into several beams; a beam filter (600) that transmits a portion of the multiple beams passing through the substrate (40) and reflects the remaining portions; and a photodetector (300) that receives the beams transmitted or reflected by the beam filter (600).

[0049] An optical thin film analysis device that is not affected by the back reflection of a substrate (40), which is one embodiment of the present invention, comprises: a light source (100) that emits light; a substrate (40) coated with a thin film (50) through which light emitted from the light source (100) is transmitted; a multi-beam splitter (400) positioned between the light source (100) and the substrate (40) and splitting the transmitted light (30) transmitted through the substrate (40) into several beams; a beam deviation compensator (700) that compensates for deviation of light transmitted through the coated substrate (40); and a photodetector (300) that receives light beams whose deviation is compensated for by the beam deviation compensator (700).

[0050] The above light source (100) can use a short wavelength light source or a multi-wavelength light source.

[0051] The above multi-beam splitter (400) can use a convex lens. When the convex lens is placed in front of the thin film (50) sample, the multiple reflected light rays (20) of the substrate (40) are independently focused, and as a result, they are spatially separated from each other. It is preferable that the focal length of the lens of the above multi-beam splitter (400) be designed to be sufficiently small to satisfy the condition of Equation 1 below.

[0052] Diameter of the beam at the focus (D) foc ) << Multi-beam spacing (Δ) [Formula 1]

[0053] In the above equation 1, the diameter of the light beam at the focus is D foc =4λf / (πD in ) is represented as 'D in : Diameter of the input light beam, D foc : represents the diameter of the focal beam, λ: wavelength of light, and f: focal length of the lens.

[0054] FIG. 6 is a schematic diagram for obtaining the optical characteristics of a coated thin film (50) through a multi-beam splitter (400), a beam gap expander (500), and a beam filter (600) of the present invention. As shown in FIG. 6, when an incident beam (10) irradiated from the light source (100) is incident on a substrate (40) at an angle, it is divided into a reflected beam (20) that is partially reflected and a transmitted beam (30) that is partially transmitted. When a multi-beam splitter (400) is used, when the incident beam (10) before being incident on the multi-beam splitter (400) is defined as a first incident beam, and the incident beam (10) after being incident on the multi-beam splitter (400) is defined as a second incident beam, the Gaussian distribution of the second incident beam is formed narrower than the Gaussian distribution of the first incident beam. For example, the first incident light ray is reflected as a 1-1 reflected light ray (20-1) in the first region (50R-1) of the thin film (50) and transmitted as a 1-1 transmitted light ray (30-1), the 1-1 transmitted light ray (30-1) is reflected on the back surface of the substrate (40), the 1-2 reflected light ray (20-2) is transmitted in the second region (50R-2) of the thin film (50), and the 1-2 transmitted light ray (30-2) is reflected, the 1-2 transmitted light ray (30-2) is reflected on the back surface of the substrate (40), the 1-3 reflected light ray (20-3) is transmitted in the third region (50R-3) of the thin film (50), and the 1-3 transmitted light ray (30-3) is reflected. When the multi-beam separator (400) is not used, the first-first transmitted light beam (30-1), the first-second transmitted light beam (30-2), and the first-third transmitted light beam (30-3) are transmitted so as to overlap each other, but when the multi-beam separator (400) is used, the first-first transmitted light beam (30-1), the first-second transmitted light beam (30-2), and the first-third transmitted light beam (30-3) are separated from each other and the transmitted light beams are transmitted so as to proceed.Therefore, by receiving only the 1-1 transmitted light beam (30-1) from the photodetector, the spatial resolution of the thin film (50) can be increased while minimizing the influence of the back surface of the substrate (40), enabling accurate measurement.

[0055] The above-described light beam spacing expander (500) can further widen the spacing between the first-first transmitted light beam (30-1), the first-second transmitted light beam (30-2), and the first-third transmitted light beam (30-3), which are separated from each other. Here, if only the multi-beam splitter (400) is used, the first-first transmitted light beam (30-1), the first-second transmitted light beam (30-2), and the first-third transmitted light beam (30-3) are separated from each other, but the spacing between them is very short, so it is not easy to remove the first-second transmitted light beam (30-2) and the first-third transmitted light beam (30-3) and measure only the first-first transmitted light beam (30-1) with a photodetector. Therefore, the interval between multiple light beams can be widened by using a light beam spacing expander (500) to separate the first-first transmission light beam (30-1), the first-second transmission light beam (30-2), and the first-third transmission light beam (30-3).

[0056] FIG. 7(a) is a schematic diagram showing a beam spacing expander (500A) of the present invention using a prism-based beam expander (510a, 520a), and FIG. 7(b) is a schematic diagram showing a beam spacing expander (500B) of the present invention using a pair of lens-based beam expanders (510b, 520b). As shown in FIG. 7, the beam spacing expander (500) can use a prism-based beam expander (FIG. 7(a)) or a lens pair-based beam expander (FIG. 7(b)). The prism-based beam expander can be composed of one or more prisms. The more prisms there are, the higher the magnification, but the higher the manufacturing cost. An anamorphic prism pair including a first prism and a second prism can be convenient because the directions in which the incident beam and the output beam travel are parallel. In a lens-based beam magnifier, the concave part of a concave lens can be arranged to face the incoming side of the incident beam, the flat part of the concave lens can be arranged to face the outgoing side of the incident beam, the flat part of a convex lens can be arranged to face the incoming side of the beam exiting from the concave lens, and the convex part of a convex lens can be arranged to face the side of the beam exiting from the convex lens. Since a cylindrical lens magnifies a beam only in the horizontal direction, it can be more useful than a normal lens.

[0057] When the above light beam gap expander (500) uses a lens-based light beam expander, it is preferable to satisfy the following equation 2 for light beam expansion.

[0058] Concave lens focal length (f) cc ) < convex lens focal length (f) cx ) [Formula 2]

[0059] In addition, it is preferable that the light beam gap expander (500) satisfy the following equation 3 in order to maintain the mutual parallelism of multiple light beams.

[0060] The distance between the concave lens and the convex lens (d) = the focal length of the convex lens - the focal length of the concave lens (f cx - f cc ) [Formula 3]

[0061] The prism-based light beam expander of the present invention has the advantage of having a smaller volume than a lens-based light beam expander.

[0062] Fig. 8 is a schematic diagram showing a beam filter (600) of the present invention that receives beams using a blocking screen and a mirror. As shown in Fig. 8, the beam filter (600) can use a blocking screen or a mirror. A blocking screen-type beam filter (600) blocks the path of beams. On the other hand, a mirror-type beam filter (600) reflects the beams to be blocked in another direction. 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 side of a triangle, and a transmitted light ray (30) is incident at an incident angle of 45 on the mirror surface, and the incident transmitted light ray (30) is reflected from the mirror surface, and the reflected transmitted light ray (30D) is received by a side transmitted light detector (300D). It is preferable that the light ray filter (600) be arranged near the focus, which is a location where the spatial separation of the transmitted light ray (30) is good. A slit or pinhole (301) may be provided in the light ray filter (600) and the side transmitted light detector (300D), so that a portion (30-2D) of the reflected transmitted light ray may be transmitted.

[0063] Meanwhile, when the direction parallel to the rotation axis of the substrate (40) is defined as the -y-axis direction, the direction in which the transmitted light (30) traveling from the substrate (40) toward the light filter (600) is defined as the z-axis direction, and the direction in which the transmitted light (30) is reflected from the light filter (600) and traveling is defined as the -x-axis direction, the light 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 light (10) increases, the light filter (600) moves in the -x-axis direction closer to the side transmission light photodetector (300D). Accordingly, even if the substrate (40) is rotated and the transmitted light (30) deviates in the -x-axis direction, the transmitted light (30D) reflected on the mirror surface is received by the side transmission light detector (300D) because the light filter (600) moves in conjunction. Here, the light filter (600) is mounted on the moving device of the x-axis stage so that its position can be controlled. When the light filter (600) is of a mirror type, the reflected light can be measured by the side transmission light detector (300D) so that the position of the light filter (600) can be controlled in a feedback manner.

[0064] FIG. 9 is a schematic diagram for obtaining optical characteristics of a coated thin film (50) through a multi-beam splitter (400), a beam gap expander (500), a beam filter (600), and a beam deviation compensator (700) of the present invention. As shown in FIG. 9, a beam deviation compensator (700) may be required. Due to refraction in the substrate (40), a deviation of the beam occurs after the thin film (50) is transmitted through the substrate (40) coated with the thin film (50). The beam deviation X due to the substrate (40) coated with the thin film (50) is expressed by Equation 4.

[0065] X = d s (sinθ i -cosθ i tanθ s ) [Formula 4]

[0066] (In the above equation 4, sinθ i =n s sinθ s has a relationship of n s , d s , θ i , θ s represent the refractive index of the substrate (40), the thickness of the substrate (40), the incident angle, and the refraction angle at the substrate (40), respectively.

[0067] From the above equation 4, it can be seen that as the incident angle increases, the light beam deviation monotonically increases. The light beam deviation due to the substrate (40) coated with the thin film (50) is further amplified by the light beam gap expander (500), and thereby the change in the incident angle can greatly change the incident position of the measured light beam on the light detector. A convex lens can be used as a method of compensating for this problem. By arranging the convex lens in front of the light detector to compensate for the light beam deviation, the measured light beam can be fixed to a specific position of the light detector regardless of the change in the incident angle.

[0068] In order to compensate for the light ray deviation caused by the substrate (40) coated with the thin film (50), it is desirable to satisfy Equation 5.

[0069] Distance (D) between the light beam deviation compensator (700) and the light beam photodetector for transmission C-D ) = focal length (f) of the light deviation compensator (700) C ) [Formula 5]

[0070] The above light ray deviation compensator (700) is the distance (D) between the focus of the transmitted light ray (30) and the light ray deviation compensator (700). f-C ) < Focal length (f) of the light deviation compensator (700) C ) is placed in a position that satisfies the conditions, the light beam can be incident on the transmission light beam photodetector with the desired diameter because the refocusing of the light beam is prevented.

[0071] In Fig. 9, it is described that light transmitted through a light filter and the deviation of the light beam compensated for by a light deviation compensator is received by a light beam photodetector for transmission, but it is also possible for light reflected from the light filter described in Fig. 8 to pass through a light deviation compensator and receive the deviation-compensated light beam by a side transmission light detector.

[0072] Fig. 10 is a schematic diagram for obtaining optical characteristics of a coated thin film through a multi-ray splitter (400), a light ray filter (600), and a light ray deviation compensator (700) of the present invention. As shown in Fig. 10, when the multi-ray splitter (400), the light ray filter (600), and the light ray deviation compensator (700) are used, the thin film substrate has an advantage in that it can be applied when the light ray interval is sufficiently large because the light ray interval is sufficiently thick, and thus a light ray interval expander (500) is not necessarily required.

[0073] Fig. 11 is a schematic diagram for obtaining the optical characteristics of a thin film coated through a multi-ray splitter (400) and a light filter (600) of the present invention. As shown in Fig. 11, when the multi-ray splitter (400) and the light filter (600) are used, the substrate of the thin film is thick enough so that the light ray spacing is sufficiently large, so that a light ray spacing expander (500) is not necessarily required, and the photodetector light-receiving section is sufficiently wide and the optical response is sufficiently uniform, so that a light ray deviation compensator (700) is not necessarily required. This has the advantage of being applicable.

[0074] FIG. 12 is a schematic diagram for obtaining the optical characteristics of a coated thin film (50) through a multi-beam splitter (400) and a beam deviation compensator (700) of the present invention. As shown in FIG. 12, when light transmitted from a substrate (40) coated with a thin film (50) is transmitted through the beam deviation compensator (700), it is possible to compensate for both the deviation and separation of the light beams. That is, as shown in FIG. 3, an improved thin film analysis method can be obtained by simply adding the beam deviation compensator (700) to a thin film analysis method consisting of a conventional light source (100), a multi-beam splitter (400), and a light detector. Since the beam deviation compensator (700) here performs the function of gathering the separated multiple beams into one place, it can be referred to as a beam deviation and separation compensator. By additionally arranging the beam deviation and separation compensator, it has the advantage of being able to gather all multiple beams into the same location of the light detector regardless of a change in the incident angle.

[0075] FIG. 13 is a flow chart of a method for analyzing the optical characteristics of a coated thin film (50) using a multi-beam separator (400), a beam gap expander (500), a beam filter (600), and a beam deviation compensator (700) of the present invention. As shown in FIG. 13, an optical thin film analysis method that is not affected by the backside reflection of a substrate (40) according to one embodiment of the present invention comprises: a first step (S10) of emitting a beam of light from a light source (100); a second step (S20) of passing the beam of light emitted in the first step through a multi-beam separator (400); a third step (S30) of passing the beam of light passing through the multi-beam separator (400) through a substrate (40) coated with a thin film (50) and separating it into multiple beams; a fourth step (S40) of passing the multiple beams in the third step through a beam gap expander (500) and expanding the intervals of the beams; The light beam expanded in the fourth step includes a fifth step (S50) in which a portion of the light beam is maintained along a path by a light beam filter (600) and the remaining portion of the light beam is reflected; a sixth step (S60) in which the light beam whose path is maintained or reflected in the fifth step passes through a light beam deviation compensator (700) and the deviation of the light beam is compensated; and a seventh step (S70) in which the light beam whose deviation is compensated in the sixth step is received by a photodetector.

[0076] The above first step is a step in which light rays are emitted from a light source (100). The light source (100) may use a single wavelength or multiple wavelengths.

[0077] In the second step, the light beam emitted from the light source (100) passes through a multi-beam splitter (400). The multi-beam splitter may use a convex lens. By using the multi-beam splitter (400), the light beam can be split by narrowing the Gaussian distribution of the multiple light beams when they pass through the inclined substrate (40).

[0078] The third step is a step in which light passing through a multi-beam separator (400) passes through a substrate (40) coated with a thin film (50). The substrate (40) is placed on a rotating stand, and in order to measure the optical properties of the thin film (50), light is incident at a specific incident angle and causes multiple reflections on the back and front surfaces of the substrate (40). Here, light passing through the back surface of the substrate (40) progresses as multiple light rays.

[0079] The fourth step described above is the step where the interval between light beams is expanded as they pass through the light beam gap expander (500). Although the light beams are separated into multiple light beams using only the multi-beam splitter (400), the intervals between the separated light beams are still narrow, making it difficult to separate and detect them using a transmission-type light beam detector. Therefore, it is necessary to expand the interval between the multiple light beams so that they can be easily separated and detected using a transmission-type light beam detector.

[0080] In the fifth step, the expanded light beam is a step in which a part of the light beam maintains its path and the remaining part of the light beam is reflected by the light beam filter (600). In order to obtain the optical characteristics of the light beam transmitted only to a specific area of ​​the substrate (40) coated with the thin film (50), the path of a part of the light beam is maintained by the light beam filter (600) and the light beam is received and measured, or the remaining part of the light beam is reflected by the light beam filter (600) and the light beam is received and measured. This is a step in which the desired light beam is filtered from the separated light beam.

[0081] In the above 6th step, the transmitted or reflected light passes through the light deviation compensator (700), and this is the step in which the deviation of the light is compensated. For the light transmitted in the 6th step, the light deviation compensator (700) can be positioned in front of the light beam photodetector (300) for transmission, and for the light reflected in the 6th step, the light deviation compensator (not shown) can be positioned in front of the light beam photodetector (300D) for side transmission.

[0082] The above seventh step is a step of receiving the light beam whose deviation has been compensated by the light beam deviation compensator (700) by the light beam photodetector for transmission (300) or the light beam photodetector for side transmission (300D).

[0083] FIG. 14 is a flow chart of a method for analyzing the optical characteristics of a coated thin film (50) using a multi-beam splitter (400), a beam filter (600), and a beam deviation compensator (700) of the present invention. As shown in FIG. 14, an optical thin film analysis method that is not affected by the backside reflection of a substrate (40), which is one embodiment of the present invention, comprises: a first step (R10) of emitting a beam of light from a light source (100); a second step (R20) of passing the beam of light emitted in the first step through a multi-beam splitter (400); a third step (R30) of passing the beam of light passing through the multi-beam splitter (400) through a substrate (40) coated with a thin film (50) and splitting it into multiple beams; a fourth step (R40) of maintaining a portion of the beam path of the multiple beams in the third step and reflecting the remaining portions of the beams by a beam filter (600); In the fourth step, the light beam or reflected light beam whose path is maintained passes through a light beam deviation compensator (700) and the deviation of the light beam is compensated for, a fifth step (R50); and in the fifth step (R60), the light beam whose deviation is compensated for in the fifth step is received by a photodetector.

[0084] Fig. 14 is the same as the step of enlarging the light beam in the fourth step in the method for analyzing the optical properties of the coated thin film (50) of Fig. 13, so a detailed description is omitted.

[0085] FIG. 15 is a flow chart of a method for analyzing the optical properties of a coated thin film (50) using a multi-beam separator (400), a beam gap expander (500), and a beam filter (600) of the present invention. As shown in FIG. 15, an optical thin film analysis method that is not affected by the backside reflection of a substrate (40), which is one embodiment of the present invention, comprises: a first step (Q10) of emitting a beam of light from a light source (100); a second step (Q20) of passing the beam of light emitted in the first step through a multi-beam separator (400); a third step (Q30) of passing the beam of light passing through the multi-beam separator (400) through a substrate (40) coated with a thin film (50) and separating it into multiple beams; a fourth step (Q40) of passing the multiple beams in the third step through a beam gap expander (500) and expanding the intervals of the beams; The light beam expanded in the fourth step includes a fifth step (Q50) in which a portion of the light beam is maintained along a path by a light beam filter (600) and the remaining portion of the light beam is reflected; and a sixth step (Q60) in which the light beam whose path is maintained or reflected in the fifth step is received by a photodetector.

[0086] Fig. 15 is a method for analyzing the optical characteristics of the coated thin film (50) of the thin film of Fig. 13. In the sixth step, the transmitted or reflected light passes through the light deviation compensator (700), and the other steps are the same except for the step where the deviation of the light is compensated, so a detailed description thereof is omitted.

[0087] FIG. 16 is a flow chart of a method for analyzing the optical properties of a coated thin film (50) using a multi-beam separator (400) and a light filter (600) of the present invention. As shown in FIG. 16, an optical thin film analysis method that is not affected by the backside reflection of a substrate (40), which is one embodiment of the present invention, comprises: a first step (P10) of emitting light from a light source (100); a second step (P20) of passing the light emitted in the first step through a multi-beam separator (400); a third step (P30) of passing the light passing through the multi-beam separator (400) through a substrate (40) coated with a thin film (50) and separating the light into multiple light beams; a fourth step (P40) of maintaining a portion of the light beam path of the multiple light beams in the third step and reflecting the remaining portion of the light beams by the light filter (600); In the fourth step, the light beam or reflected light beam whose path is maintained is received by a photodetector, which includes a fifth step (P50);

[0088] Fig. 16 is a method for analyzing the optical characteristics of the coated thin film (50) of the thin film of Fig. 13. Except for the step in which the intervals of the light rays are expanded while the multiple light rays pass through the light beam gap expander (500) in the fourth step and the step in which the transmitted or reflected light rays pass through the light beam deviation compensator (700) and the deviation of the light rays is compensated for in the sixth step, the other steps are the same and therefore detailed descriptions are omitted.

[0089] FIG. 17 is a flow chart of a method for analyzing the optical characteristics of a coated thin film (50) using a multi-beam separator (400) and a beam deviation compensator (700) of the present invention. As shown in FIG. 12, an optical thin film analysis method that is not affected by the back reflection of a substrate (40) according to one embodiment of the present invention comprises: a first step (T10) of emitting a beam of light from a light source (100); a second step (T20) of passing the beam of light emitted in the first step through a multi-beam separator (400); a third step (T30) of passing the beam of light passing through the multi-beam separator (400) through a substrate (40) coated with a thin film (50) and separating it into multiple beams; a fourth step (T40) of compensating for the deviation of the beams while passing through a beam deviation compensator (700) in the third step; And the light beam whose deviation has been compensated in the fourth step is received by a photodetector in the fifth step (T50);

[0090] Fig. 17 is a method for analyzing the optical characteristics of the coated thin film (50) of the thin film of Fig. 13. Except for the step of expanding the light beam in the fourth step and the step of transmitting or reflecting by the light beam filter (600) in the fifth step, the other steps are the same, so a detailed description is omitted.

[0091]

[0092] Although the above-described embodiments have been described with limited examples and drawings, those skilled in the art will recognize that various modifications and variations are possible based on the above teachings. For example, appropriate results can be achieved even if the described techniques are performed in a different order than described, and / or components of the described systems, structures, devices, circuits, etc. are combined or combined in a different manner than described, or are replaced or substituted with other components or equivalents. Therefore, other implementations, other embodiments, and equivalents of the claims also fall within the scope of the following claims.

Claims

1. A light source that emits light; A substrate coated with a thin film through which light emitted from the light source is transmitted; A multi-beam splitter positioned between the light source and the substrate, which splits the transmitted light beams transmitted through the substrate into multiple beams; A beam spacing expander that expands the spacing of the multiple beams of light separated into the above-mentioned multiple beams; A light filter that transmits some of the light rays expanded by the above light beam gap expander and reflects the remaining parts; A light deviation compensator that compensates for the deviation of light transmitted or reflected from the light filter; and An optical thin film analysis device that is not affected by the back surface reflection of a substrate, including a transmission photodetector that receives a light beam whose deviation has been compensated for by the above light beam deviation compensator.

2. A light source that emits light; A substrate coated with a thin film through which light emitted from the light source is transmitted; A multi-beam splitter positioned between the light source and the substrate, which splits the transmitted light beams transmitted through the substrate into multiple beams; A light filter that transmits some of the multiple light rays separated into the above-mentioned multiple light rays and reflects the remaining parts; A light deviation compensator that compensates for the deviation of light transmitted or reflected from the light filter; and An optical thin film analysis device that is not affected by the back surface reflection of a substrate, including a transmission photodetector that receives a light beam whose deviation has been compensated for by the above light beam deviation compensator.

3. A light source that emits light; A substrate coated with a thin film through which light emitted from the light source is transmitted; A multi-beam splitter positioned between the light source and the substrate, which splits the transmitted light beams transmitted through the substrate into multiple beams; A beam spacing expander that expands the spacing of the multiple beams of light separated into the above-mentioned multiple beams; A light filter that transmits a portion of the light beam expanded by the above light beam gap expander and reflects the remaining portion; and An optical thin film analysis device that is not affected by the back surface reflection of a substrate, including a transmission photodetector that receives light transmitted or reflected from the above light filter.

4. A light source that emits light; A substrate coated with a thin film through which light emitted from the light source is transmitted; A multi-beam splitter positioned between the light source and the substrate, which splits the transmitted light beams transmitted through the substrate into multiple beams; A light filter that transmits some of the above-mentioned multiple light beams and reflects the remaining parts; and An optical thin film analysis device that is not affected by the back surface reflection of a substrate, including a transmission photodetector that receives light transmitted or reflected from the above light filter.

5. A light source that emits light; A substrate coated with a thin film through which light emitted from the light source is transmitted; A multi-beam splitter positioned between the light source and the substrate, which splits the transmitted light beams transmitted through the substrate into multiple beams; A light beam deviation compensator that compensates for the deviation and separation of the multiple light beams separated into the above; and An optical thin film analysis device that is not affected by the back surface reflection of a substrate, including a transmission photodetector that receives light rays whose deviation and separation are compensated for in the above light ray deviation compensator.

6. In any one of claims 1 to 5, An optical thin film analysis device that is not affected by the back surface reflection of a substrate, wherein the light source is a single wavelength or multiple wavelengths, and the polarization of the light beam of the light source is either s polarization or p polarization or a variable direction of s polarization and p polarization.

7. In any one of claims 1 to 5, An optical thin film analysis device that is not affected by back surface reflection of a substrate, wherein the light emitted from the light source is defined as an incident light before it is transmitted through the substrate, a transmitted light after it is transmitted through the substrate, and a reflected light after it is reflected through the substrate, wherein the substrate is rotated by a substrate support, and the rotation axis of the substrate is rotated based on a direction perpendicular to a plane formed by the incident light, the reflected light, and the transmitted light.

8. In any one of claims 1 to 5, An optical thin film analysis device that is not affected by the back surface reflection of a substrate, characterized in that the above multi-beam splitter is a convex lens.

9. In claim 1 or 3, An optical thin film analysis device that is not affected by the back surface reflection of a substrate, characterized in that the above light beam gap expander is a prism-based light beam expander or a pair of lens-based light beam expander.

10. In any one of claims 1 to 4, An optical thin film analysis device that is not affected by reflection from the back surface of a substrate, characterized in that the above light filter is a blocking screen or mirror.

11. In any one of claims 1, 2 and 5, An optical thin film analysis device that is not affected by the back surface reflection of a substrate, characterized in that the above-mentioned light deviation compensator is a convex lens.

12. The first step is to emit light from a light source; The light beam emitted in the first step is transmitted through a multi-beam splitter in the second step; A third step in which light passing through the above multi-beam separator is separated into multiple light beams while passing through a substrate coated with a thin film; In the third step, the multiple light beams pass through the light beam gap expander, and the fourth step is where the gap between the light beams is expanded; In the fourth step, the expanded light beam is filtered through a light beam filter, and a fifth step is achieved where some of the light beam is transmitted and the remaining part of the light beam is reflected; In the fifth step, the transmitted or reflected light passes through a light deviation compensator, and the sixth step is where the deviation of the light is compensated; and An optical thin film analysis method that is not affected by the back surface reflection of a substrate, including a seventh step in which the light beam whose deviation has been compensated in the sixth step is received by a photodetector.

13. The first step is to emit light from a light source; The light beam emitted in the first step is transmitted through a multi-beam splitter in the second step; A third step in which light passing through the above multi-beam separator is separated into multiple light beams while passing through a substrate coated with a thin film; In the third step, the multiple light beams are filtered, and a fourth step is where some of the light beams are transmitted and the remaining parts of the light beams are reflected; In the fourth step, the transmitted or reflected light passes through a light deviation compensator, and the fifth step is where the deviation of the light is compensated; and An optical thin film analysis method that is not affected by the back surface reflection of a substrate, including a sixth step in which the light beam whose deviation has been compensated in the fifth step is received by a photodetector.

14. The first step is to emit light from a light source; The light beam emitted in the first step is transmitted through a multi-beam splitter in the second step; A third step in which light passing through the above multi-beam separator is separated into multiple light beams while passing through a substrate coated with a thin film; In the third step, the multiple light beams pass through the light beam gap expander, and the fourth step is where the gap between the light beams is expanded; In the fourth step, the light beam is expanded, and a fifth step is performed in which part of the light beam is transmitted through a light filter and the remaining part of the light beam is reflected; and An optical thin film analysis method that is not affected by backside reflection of a substrate, including a sixth step in which the transmitted or reflected light beam in the fifth step is received by a photodetector.

15. The first step is to emit light from a light source; The light beam emitted in the first step is transmitted through a multi-beam splitter in the second step; A third step in which light passing through the above multi-beam separator is separated into multiple light beams while passing through a substrate coated with a thin film; In the third step, the multiple light beams are filtered through a light beam filter, and a fourth step is achieved in which some of the light beams are transmitted and the remaining portions of the light beams are reflected; and An optical thin film analysis method that is not affected by backside reflection of a substrate, including a fifth step in which the transmitted or reflected light beam in the fourth step is received by a photodetector.

16. The first step is to emit light from a light source; The light beam emitted in the first step is transmitted through a multi-beam splitter in the second step; A third step in which light passing through the above multi-beam separator is separated into multiple light beams while passing through a substrate coated with a thin film; In the third step, the multiple light beams pass through a light beam deviation compensator, and the fourth step is where the deviation and separation of the light beams are compensated; and An optical thin film analysis method that is not affected by the back surface reflection of a substrate, including a fifth step in which the light beam whose deviation has been compensated in the fourth step is received by a photodetector.

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