JP3086504U - Optical film characteristic evaluation device and optical film characteristic evaluation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive optical film characteristic evaluation apparatus and an optical film characteristic evaluation system capable of quickly and accurately evaluating optical characteristics such as light transmission characteristics of a thin film such as a DWDM filter. . SOLUTION: In the optical film characteristic evaluation apparatus for analyzing the signal light received by the light receiving means and evaluating the characteristics of the optical film sample, the flatness of the chip mounting surface is set to ± 0.1 ° or less. An optical film sample is mounted on a precisely polished sample mounting surface, light from a light source is condensed on the sample, and the optical film sample is irradiated with light, and transmitted light from the optical film sample is received and received. The configuration is such that the amount of transmitted light at an arbitrary incident angle of light is calculated based on the transmitted light. This eliminates the need to drive the optical system every time evaluation is performed, enabling quick and highly accurate evaluation.
In addition, an inexpensive optical film characteristic evaluation device and an optical film characteristic evaluation system can be obtained.

Description

[Detailed description of the invention]

[0001]

[Technical field to which the invention belongs]

 The present invention relates to an optical film characteristic evaluation apparatus and an optical film characteristic evaluation system, and more particularly, to a quick and highly accurate evaluation of optical characteristics such as light transmission characteristics of a multilayer film such as a DWDM filter, and The present invention relates to an inexpensive optical film characteristic evaluation device and an optical film characteristic evaluation system.

[0002]

[Prior art]

 In the field of optical communication, DWDM (Dense Wavelength Division Multiplexing) communication system wavelength division filters (DWDM filters) consist of alternating dielectric thin films with different refractive indices on a glass substrate whose surface is polished with high precision. A technology for accurately and quickly evaluating optical characteristics such as light transmission characteristics of a multilayer film formed of several tens to several hundreds of layers is an important technology in DWDM filter manufacturing.

[0003] In general, a DWDM filter is important in light transmission characteristics when light is incident on the filter at an angle of 0 to 5 ° (especially 1.8 ° or 2.0 °). It is important to measure transmission characteristics accurately. For this reason, in the conventional optical film characteristic evaluation apparatus, a filter is mounted on a sample stage having an automatic light incident angle adjustment function, and firstly, adjustment is performed so that light is vertically incident on the surface of the filter, and then, By tilting the sample stage by a desired angle, the angle between the filter surface and the incident light is set, and the amount of transmitted light under the light incident angle condition is measured.

FIG. 9 is a diagram for explaining a configuration of an optical system provided in a conventional optical film characteristic evaluation apparatus. The light emitted from the light source is guided to the optical fiber 91, emitted from the light irradiating section 92, collected by the lens 93, and made incident on the chip 94 of the DWDM filter. The light incident on the chip 94 is repeatedly reflected and refracted inside the multilayer film of the chip 94, and the light transmitted from the surface opposite to the incident surface is received by the light receiving unit 95 and guided by the optical fiber 96. Then, it is led to a signal light analyzer (not shown).

[0005] First, the chip 94 is mounted on a chip holder whose chip mounting surface is adjusted to coincide with a horizontal plane, and incident light is vertically incident on the surface of the chip 94 mounted on the chip holder. After the adjustment as described above, the entire optical system including the lens 93 is tilted so that the incident light has a desired incident angle φ on the surface of the chip 94, and the light transmission characteristics in that state are evaluated. The procedure of doing is taken.

[0006]

[Problems to be solved by the invention]

 However, such an evaluation system for an optical system requires a precise sample stage equipped with an automatic incident angle adjustment function that inclines the entire optical system including the lens exactly by the angle φ between the chip surface and the horizontal plane. As a result, there has been a problem that the optical film characteristic evaluation device and the optical film characteristic evaluation system are expensive.

Further, most of the time required to evaluate the optical characteristics of each chip is spent on the adjustment of the above-described optical system, and as a result, the throughput of the optical characteristics evaluation has to be significantly reduced. There was also a problem.

Further, since the transmission wavelength characteristic of the DWDM filter does not always have a uniform distribution in the plane, the measurement position of the optical characteristic also needs to be determined with an accuracy within ± 0.02 mm. With the characteristic evaluation device, it was difficult to determine the sample position with such accuracy.

The present invention has been made in view of such a problem, and a purpose thereof is to provide a quick and accurate optical characteristic such as a light transmission characteristic of a thin film or a multilayer film such as a DWDM filter. An object of the present invention is to provide an optical film characteristic evaluation apparatus and an optical film characteristic evaluation system that can be evaluated, can easily determine the position of a measurement sample, and are inexpensive.

[0010]

Means for Solving the Problems According to the present invention, in order to achieve such an object, the invention according to claim 1 uses a light for condensing light from a light source and irradiating the sample with light. Irradiation means, sample mounting means for mounting the optical film sample, and light receiving means for receiving reflected light or transmitted light from the optical film sample, and the signal light received by the light receiving means is provided. An optical film characteristic evaluation apparatus for analyzing and evaluating characteristics of the optical film sample, wherein a flatness of a sample mounting surface of the sample mounting means is ± 0.1 ° or less.

The invention according to claim 2 is a sample storage means for storing an optical film sample as an evaluation sample, an optical film characteristic evaluation means for evaluating the optical characteristics of the optical film sample, and the optical device. An optical film property evaluation system comprising: a sample transport means for transferring a film sample to the optical film property evaluation means, wherein the optical film property evaluation means is the optical film property evaluation apparatus according to claim 1. It is characterized by.

Further, according to a third aspect of the present invention, in the optical film characteristic evaluation system according to the second aspect, an image recognition unit is provided between the sample storage unit and the optical film characteristic evaluation unit. The amount of deviation of the optical film sample from the reference position being transported by the sample transporting means is determined by the image recognition means, and based on the determination result, the optical film sample is mounted on the reference position of the sample mounting means. It is characterized by being placed.

[0013]

[Embodiment of the invention]

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram for explaining the configuration of a chip holder provided in the optical film characteristic evaluation device of the present invention. FIG. 1A is a plan view of the chip holder, and FIG. It is sectional drawing of a chip holder.

The chip holder 10 has a chip mounting surface 13 having a size of 1.4 mm × 1.4 mm, and a light incident hole 11 having a diameter of 1.0 mm is provided in a central portion. Are provided with vacuum chuck holes 12a to 12d having a diameter of 0.2 to 0.3 mm.

The DWDM filter chip has a rectangular cross section of approximately 1.4 mm × 1.4 mm, and the four corners of the chip are vacuum-sucked through the vacuum chuck holes 12 a to 12 d and set on the chip mounting surface 13. Light incident from the lower surface side of the holder 10 and passing through the light entrance hole 11 is received.

The chip mounting surface 13 is processed to be extremely flat, and an ideal plane (geometric plane) when the chip mounting surface 13 is assumed to be completely flat, and a chip mounting surface 13 are formed on the chip mounting surface 13. High-precision polishing is performed so that the angle between the chip and the chip surface when the chip is actually mounted is ± 0.1 ° or less. The flatness of the chip mounting surface 13 is assumed to be a narrow band transmission filter chip having a λ / 4 optical film thickness in which TiO ₂ and SiO ₂ are alternately laminated. It was determined based on the result of simulating the incident angle dependence.

FIG. 2 is a diagram for explaining the relationship between the transmission characteristics of a narrow band transmission filter used for DWDM and the like and the incident angle. FIG. 2A shows a case where the light incident angle is 0.0 °. , 1.8 °, 3.0 °, and 5.0 °, the light transmittance at each wavelength is shown. FIG. 2B shows that the chip mounting surface is inclined and the inclination angle is changed. The relative change of the center wavelength when the corresponding light incident angle α is changed from 0 to 5 ° is shown.

As shown in FIG. 2A, the amount of light transmitted through the chip changes according to the incident angle of light on the chip surface. This is because the transmission wavelength of the interference thin film changes according to the incident angle of light. This is a phenomenon caused by:

As shown in FIG. 2B, the center wavelength of the transmitted light changes depending on the tilt angle of the chip (that is, the incident angle of light). The relationship with the angle can be understood from the following principle of wavelength change of the single-layer film.

[0021] Figure 3 deposition is a diagram for light interference thin film of a single layer to understand the changes in the transmission wavelength in the case of incident, the vacuum of the refractive index n _0, on the substrate having a refractive index n _s the single layer film of refractive Oriritsu n of thickness d that is, shows a state in which light is incident at an incident angle theta _0.

In the figure, if the optical path difference between the light reflected at point D and the light that is incident on the thin film at an incident angle θ and then reflected by the back surface of the thin film and emitted from point C is Δ, the optical path difference Δ , by performing the calculation of simple geometrical optics, Δ = 2nd (1 / cosθ -tanθ · sinθ) = 2nd · cosθ = 2d (n 2 -n o 2 sinθ 0) 1/2 and Motomari, the incident angle θ _It can be seen that when ₀ changes, the optical path difference Δ changes correspondingly. The more the optical path difference Δ is changed to the incident angle theta ₀ of the light incident on the filter is changed, so that the center wavelength changes.

For example, in the evaluation of the optical characteristics of a narrow band filter, it is necessary to determine the center wavelength at 1550 nm with an accuracy of ± 0.010 nm. In this method, the center wavelength of transmitted light is determined with an accuracy of ± 0.010 nm by adjusting the chip so that it is perpendicular to the chip surface (0 ° alignment), and then tilting the chip by a desired angle. Is extremely difficult.

The reason is that the accuracy of 0 ° alignment determined at the chip position where the light intensity takes the maximum value is at most about ± 0.01 ° due to noise in optical measurement, and after this 0 ° alignment, When the tip is further tilted by 2 to 5 °, the tilt error is about ± 0.003 °, so that the overall angular error is about ± 0.013 °, and the center wavelength error Δλ is Δλ / λ = sin θ · dθ = In addition to ± 1.2 × 10 ⁻⁵ and Δλ = ± 0.019 nm, the center wavelength of the transmitted light is, as shown in FIG. The larger the value, the greater the change due to slight inclination angle error.

Therefore, the dependence of the transmitted light intensity on the light incident angle is theoretically determined based on the transmitted light amount measured under the condition of accurate vertical light incidence without performing the chip tilting as employed in the conventional evaluation apparatus. By obtaining the amount of transmitted light at a desired light incident angle, higher accuracy evaluation is possible. That is, in FIG. 2B, if the inclination angle is in a range of ± 0.1 ° centering on 0 °, the relative change of the center wavelength is at most Δλ / λ ₀ ≒ 5 × 10 ⁻⁶ and Δλ ≦ It can be set to 0.01 nm. That is, the ideal plane (geometric plane) when the chip mounting surface is assumed to be completely flat, and the chip surface when the chip is actually mounted on the chip mounting surface. The angle between the incident light and the incident light is determined to be ± 0.1 ° or less, and the dependence of the transmitted light intensity on the incident light angle is theoretically determined based on the amount of transmitted light measured under the condition of perpendicular incident light. By obtaining the light quantity, it is possible to evaluate with higher accuracy than the conventional evaluation device.

FIG. 4 is a view for explaining the configuration of the optical film characteristic evaluation apparatus of the present invention including a chip holder which is polished with high precision so that the flatness of the chip mounting surface is ± 0.1 degrees or less. FIG.

The light emitted from the light source is guided to the optical fiber 41, emitted from the light irradiating section 42, condensed by the lens 43, and directed to the DWDM filter chip 45 mounted on the chip holder 44. Incident. The light incident on the chip 45 is repeatedly reflected and refracted inside the multilayer film 45a of the chip 45, and the light transmitted from the surface opposite to the incident surface is received by the light receiving unit 46, and is received by the optical fiber 47. The light is guided to an analyzer (not shown).

FIG. 5 shows the light incident angle of the amount of light transmitted through the DWDM filter when the DWDM filter is mounted on the chip holder having the configuration shown in FIG. 4 and the chip mounting surface of the chip holder is slightly inclined from the horizontal plane. This is the result of obtaining dependency. Here, the transmitted light amount under the perfect vertical incidence condition is R _max, and the minimum value of the transmitted light amount obtained by the high precision evaluation is R _min . As can be seen from this figure, the angle between the incident light and the chip surface is ± 0.1 degrees or less, in other words, the difference between the chip surface and the horizontal plane when the chip is actually mounted on the chip mounting surface. It was confirmed that by polishing the chip mounting surface with high accuracy so that the angle formed was ± 0.1 degrees or less, the accuracy required for transmission characteristic evaluation could be secured.

As described above, the chip holder provided in the optical film characteristic evaluation device of the present invention is highly polished so that the flatness of the chip mounting surface is ± 0.1 degrees or less. Unlike the conventional optical film characteristic evaluation device, even if the entire optical system including the lens is not provided with a precise driving device that inclines exactly by the angle formed between the chip surface and the horizontal surface, it is possible to maintain the accuracy within the allowable accuracy. The transmittance can be measured.

If an automatic evaluation system for optical film characteristics is provided with the above-described optical film characteristic evaluation device, high-precision and quick evaluation can be performed.

FIG. 6 is a diagram for explaining the configuration of the optical film characteristic evaluation system of the present invention. The optical film characteristic evaluation system includes a chip tray 61, a suction nozzle 63, a nozzle arm 64, and a transfer arm 65. , A CCD camera 66, a rotary table 67, a chip holder 68 provided on the rotary table 67, and optical film characteristic evaluation sections 69 a and 69 b.

The chip 62 of the DWDM filter to be evaluated is placed on the chip tray 61, and the nozzle arm 64 movably on the transfer arm 65 moves to a position corresponding to the chip tray 61. Then, the chip 62 is vacuum-sucked by the suction nozzle 63 provided at the tip of the nozzle arm 64.

Next, the nozzle arm 64 is moved to the position where the CCD camera 66 is installed, the center point of the chip surface is recognized using the image recognition function of the CCD camera 66, and the position is corrected by a rotation operation in the XY plane. Then, the wafer is transported to the chip holder 68 and positioned in the chip holder 68 having a chip mounting surface polished with high precision, and then fixed by vacuum chucking.

When the chip 62 is set on the chip holder 68, the chip is moved to the optical film characteristic evaluation section 69 a or 69 b by rotation of the turntable 67, and desired optical characteristics are evaluated.

Here, since the center wavelength of the transmitted light of the chip is not uniform in the chip surface but differs depending on the evaluation position, positioning when setting the chip on the chip holder 68 is also extremely important.

FIG. 7 is a diagram for explaining an example of actually measuring the in-plane distribution of the center wavelength of transmitted light of a DWDM chip having a rectangle having a side of 1.4 mm, and illustrates a measurement position (x position) of the chip. It can be seen that the center wavelength differs depending on the parentheses.

FIG. 8 is a view for explaining a chip positioning step in the optical film characteristic evaluation system of the present invention. A chip 82 placed on a chip tray 81 is provided at the tip of a nozzle arm 84. When the CCD camera 86 moves to the installation position of the CCD camera 86 after being vacuum-sucked by the suction nozzle 83, the CCD camera 86 recognizes an image of a shift Δ between the center point of the suction nozzle 83 and the center point of the chip 82.

The nozzle arm 84 is moved to the position of the tip holder 87 by the transfer arm 85, and the center of the tip 82 and the tip holder 87 are determined based on the deviation Δ between the center point of the suction nozzle 83 and the center point of the tip 82 already measured. The tip 82 is set in the tip holder 87 after the position is corrected so that the centers of the two coincide with each other.

[0039]

[Effect of the invention]

 As described above, in the optical film property evaluation apparatus of the present invention, the optical film sample is placed on the sample mounting surface polished with high precision so that the flatness of the chip mounting surface is ± 0.1 ° or less. The light from the light source is condensed on this, the light is irradiated to the optical film sample, the transmitted light from the optical film sample is received, and the transmitted light from the optical film sample is received. The configuration for calculating the amount of transmitted light eliminates the need to drive the optical system each time evaluation is performed, enabling quick and high-precision evaluation, and inexpensive optical film characteristic evaluation devices and optical films. A characterization system is obtained.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams for explaining the configuration of a chip holder provided in the optical film characteristic evaluation device of the present invention, wherein FIG. 1A is a plan view of the chip holder, and FIG. .

FIGS. 2A and 2B are diagrams for explaining a relationship between transmission characteristics and an incident angle of a narrow-band transmission filter used for DWDM or the like, and FIG. 2A illustrates a case where light incident angles are 0.0 ° and 1.8 °. ,
The light transmittance at each wavelength in the case of 3.0 ° and 5.0 ° is shown, and (b) shows that the chip mounting surface is inclined and the light incident angle α corresponding to the inclination angle is set to 0. The relative change of the center wavelength when the angle is changed up to ５5 ° is shown.

FIG. 3 is a diagram for understanding a change in transmission wavelength when light is incident on a single-layer interference thin film.

FIG. 4 is a diagram for explaining the configuration and characteristics of the optical film characteristic evaluation device of the present invention.

FIG. 5 Places a DWDM filter on a tip holder,
It is the result of measuring the change in the amount of reflected light of the DWDM filter when the chip mounting surface of the chip holder is slightly inclined from the horizontal plane.

FIG. 6 is a diagram for explaining the configuration of the optical film characteristic evaluation system of the present invention.

FIG. 7 is a diagram for explaining an example of actually measuring the in-plane distribution of the center wavelength of transmitted light of a DWDM chip having a rectangle having a side of 1.4 mm.

FIG. 8 is a diagram for explaining a chip positioning step in the optical film characteristic evaluation system of the present invention.

FIG. 9 is a diagram for explaining a configuration of an optical system provided in a conventional optical film characteristic evaluation apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Chip holder 11 Light incidence hole 12, 12a, 12b, 12c, 12d Vacuum chuck hole 13 Chip mounting surface 41 Optical fiber 42 Light irradiation part 43 Lens 44 Chip holder 45 Chip 45a Multilayer film 46 Light receiving part 47 Optical fiber 61 Chip tray 62 Chip 63 Suction Nozzle 64 Nozzle Arm 65 Transfer Arm 66 CCD Camera 67 Rotary Table 68 Chip Holder 69a, b Optical Film Characteristics Evaluation Unit 81 Chip Tray 82 Chip 83 Suction Nozzle 84 Nozzle Arm 85 Transfer Arm 86 CCD Camera 87 Chip Holder 91 Light Fiber 92 Light irradiation unit 93 Lens 94 Chip 95 Light receiving unit 96 Optical fiber

Claims (3)

[Utility model registration claims] 1. A light irradiating means for condensing light from a light source and irradiating the sample with light, a sample mounting means for mounting an optical film sample, and a reflected light from the optical film sample Or an optical film property evaluation apparatus comprising light receiving means for receiving transmitted light, analyzing signal light received by the light receiving means and evaluating characteristics of the optical film sample, wherein the sample of the sample mounting means An optical film characteristic evaluation device, wherein the flatness of the mounting surface is ± 0.1 ° or less. 2. A sample storage unit for storing an optical film sample as an evaluation sample, an optical film characteristic evaluation unit for evaluating optical characteristics of the optical film sample, and a transporting the optical film sample to the optical film characteristics evaluation unit. An optical film characteristic evaluation system, comprising: a sample transporting unit that performs the optical film characteristic evaluation. The optical film characteristic evaluation system according to claim 1, wherein the optical film characteristic evaluation unit is the optical film characteristic evaluation device according to claim 1. 3. An image recognizing means is provided between the sample storage means and the optical film characteristic evaluation means, and the amount of deviation of the optical film sample being transported by the sample transport means from a reference position is obtained by the image recognizing means. The optical film characteristic evaluation system according to claim 2, wherein the optical film sample is mounted on a reference position of a sample mounting means based on the determination result.