HK1204490B - Device for measuring film thickness and device for forming film - Google Patents

Abstract

Provided is a device for measuring film thickness capable of measuring optical film thickness with good precision. A device for measuring film thickness (6) comprising a projector (11) that projects light toward a monitor board (Sm) via a projector-side fiber (f1), an optical receiver (22) that receives, via a light receptor-side fiber (f2), light that is reflected by the monitor board (Sm) after being projected from the projector (11), and an optical sensing probe (13) formed by bundling a plurality of projector-side fibers (f1) and a plurality of light receptor-side fibers (f2), wherein a plurality of projector-side fiber (f1) end faces and a plurality of light receptor-side fiber (f2) end faces are disposed in the distal end face of the optical sensing probe (13) facing the monitor board (Sm). Each projector-side fiber (f1) end face is adjacent to a light receptor-side fiber (f2) end face and is arranged in an arcuate or annular shape, and each light receptor-side fiber (f2) end face is adjacent to a projector-side fiber (f1) end face and is arranged in an arcuate or annular shape.

Description

Film thickness measuring apparatus and film forming apparatus

Technical Field

The present invention relates to a film thickness measuring apparatus and a film forming apparatus equipped with the film thickness measuring apparatus, and more particularly to a film thickness measuring apparatus and a film forming apparatus equipped with the film thickness measuring apparatus, the film thickness measuring apparatus including: in order to measure the optical film thickness formed on the substrate to be measured, the film thickness measuring apparatus irradiates light to the substrate to be measured through an optical fiber, and receives reflected light reflected by the substrate to be measured through the optical fiber.

Background

In various fields using optical thin films, it is desired to form the optical thin film to a predetermined film thickness with high accuracy. On the other hand, accurate film thickness measurement is indispensable for highly accurate film thickness control of an optical thin film. The film thickness referred to herein is an optical film thickness, which is a value determined by a physical film thickness and a refractive index of the thin film.

As a method for measuring a film thickness, a reflectometry method is known which measures a film thickness by utilizing the following phenomenon: light reflected on the surface of the optical film and light reflected at the interface of the substrate and the optical film generate a phase difference due to a difference in path, and interference occurs. Various apparatuses have been proposed as film thickness measuring apparatuses using this measurement method.

As an example of a conventional film thickness measuring apparatus, there is a film thickness measuring apparatus mounted on a film forming apparatus described in patent document 1. In this device, light projected toward the optical film propagates from the light source through the optical fiber, and light reflected at the interface of the substrate and the optical film propagates to the beam splitter through the optical fiber.

When the film thickness measuring apparatus is mounted in a vacuum film forming apparatus, a monitor glass is set in the apparatus together with a substrate that is finally a multilayer film product, and a thin film is formed on the monitor glass under the same conditions as the substrate. In the film forming step, the optical film thickness of the thin film formed on the monitor glass side is measured to monitor the film forming state. This enables measurement of the optical film thickness of each layer of the multilayer film formed on the substrate side. In the conventional vacuum film forming apparatus, the monitor glass is replaced with a new glass, that is, a monitor glass before film formation, from a glass after film formation each time each layer of a multilayer film to be formed on a substrate is formed in a film forming step.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 3866933

Disclosure of Invention

Problems to be solved by the invention

In the reflective film thickness measurement, when an optical thin film is incident on a substrate with an angle, the measured value of the film thickness is thinner than the film thickness when the optical thin film is irradiated with light perpendicularly, that is, the original film thickness. Specifically, if the incident angle of light on the optical film of the substrate is θ, the refractive index of the optical film is n, and the original film thickness is d0, the measured value d of the film thickness satisfies the following equation (1).

d＝(d0/n²)×√{n²-(sinθ)²} (1)

Therefore, the larger the incident angle θ, the larger the measurement error Δ d (d 0-d) of the film thickness, and the accuracy of the measurement of the film thickness is reduced.

As shown in fig. 9, the incident angle θ corresponds to a half of an angle formed by the optical path of light incident toward the substrate and the optical path of light reflected on the substrate side. Fig. 9 is an explanatory view of an incident angle.

In consideration of the relationship between the incident angle θ and the measurement error Δ d of the film thickness, in a light projector that irradiates an optical thin film, it is desirable to reduce the area of a portion that actually irradiates light (effective light projection range) as much as possible to reduce the incident angle θ.

In addition, for the purpose of irradiating light to a predetermined position of the optical film with high accuracy, there are cases where: a condenser lens is provided between the light projector and the optical film, and the optical film is irradiated with light through the condenser lens. Also, for the purpose of reliably receiving reflected light reflected from the optical film, there are cases where: a light receiving lens is provided between the light receiver and the optical film, and the light reflected from the optical film is received by the light receiving lens. In this case, the illuminance is attenuated by the passage of light through the lens, and the measurement accuracy of the film thickness may be affected.

Further, if the monitor glass is replaced each time film formation of each layer is performed on a substrate on which a multilayer film is to be formed, variations occur between the monitor glasses in terms of size, surface state, and processing accuracy, and the variations may affect the thin film measurement accuracy.

Further, if the optical film thickness is not accurately measured for the above reasons, the accuracy of the film thickness control performed by reflecting the measurement result is also lowered, and it is difficult to obtain a thin film having a desired film thickness.

Therefore, an object of the present invention is to provide a film thickness measuring apparatus capable of measuring an optical film thickness with high accuracy. In view of the above, another object of the present invention is to provide a film deposition apparatus capable of accurately controlling the thickness of a thin film formed on a substrate based on an accurate measurement result of the optical film thickness.

Means for solving the problems

The above-described problem is solved by a film thickness measuring apparatus according to the present invention, comprising: an irradiation device that irradiates light to a substrate to be measured via an irradiation-side optical fiber composed of an optical fiber, in order to measure an optical film thickness of a film formed on the substrate to be measured; a light receiving device for receiving light reflected by the substrate to be measured after being irradiated from the irradiation device through a light receiving side optical fiber composed of an optical fiber, in order to measure the optical film thickness; and a probe formed by bundling the plurality of irradiation-side optical fibers and the plurality of light-receiving-side optical fibers, wherein the probe is configured such that end surfaces of the plurality of irradiation-side optical fibers and end surfaces of the plurality of light-receiving-side optical fibers are arranged on an opposing surface as an end surface provided on a side opposing the substrate for measurement, the end surfaces on which the plurality of irradiation-side optical fibers are arranged in an arc shape or a ring shape in a state where the end surfaces are adjacent to an end surface of at least one light-receiving-side optical fiber, the end surfaces on which the plurality of light-receiving-side optical fibers are arranged in an arc shape or a ring shape in a state where the end surfaces are adjacent to end surfaces of at least one irradiation-side optical fiber, a row formed by the end surfaces of the irradiation-side optical fibers and a row formed by the end surfaces of the light-receiving-side optical fibers are alternately arranged in a concentric circle shape, and no optical member is provided between the opposing surface and the substrate for measurement, the probe is configured such that the facing surface faces a non-film-formation surface of the measurement target substrate, the non-film-formation surface being located on a side opposite to a side on which the film is formed.

In the thin film measuring apparatus described above, if the end face of the irradiation side optical fiber and the end face of the light receiving side optical fiber are adjacent to each other on the facing surface, which is the end face, provided on the side of the probe facing the substrate to be measured, the incident angle of the light irradiated from the irradiation device to the thin film becomes smaller.

Specifically, regarding the angle formed by the optical path when the light irradiated from the end face of the irradiation side optical fiber is directed to the thin film and the optical path when the light is reflected by the substrate to be measured and directed to the end face of the light receiving side optical fiber, if the end face of the irradiation side optical fiber and the end face of the light receiving side optical fiber are adjacent to each other, the angle is smaller than the case where the end faces of the two optical fibers are not adjacent to each other. On the other hand, since the incident angle is 1/2, which is the size of the angle formed by the 2 optical paths, the incident angle also becomes smaller when the end surface of the irradiation-side optical fiber and the end surface of the light-receiving-side optical fiber are adjacent to each other. If the incident angle is reduced in this manner, the measurement error Δ d is reduced based on the relationship between the incident angle and the measurement error Δ d of the film thickness (specifically, the above equation (1)).

In addition, if the end face of the irradiation-side optical fiber and the end face of the light-receiving-side optical fiber are adjacent to each other, reflected light can be efficiently received by the light-receiving-side optical fiber.

In addition, regarding the accuracy of film thickness measurement, the higher the filling rate of the optical fibers in the end face of the probe, the higher the accuracy of film thickness measurement, and therefore, the end faces of the optical fibers are generally arranged densely within the end face of the probe. On the other hand, the denser the end faces of the optical fibers, the more easily the end faces of the irradiation-side optical fibers and the end faces of the light-receiving-side optical fibers are dense. In contrast, if the optical fibers are arranged on the end surface of the probe such that the end surface of the irradiation-side optical fiber and the end surface of the light-receiving-side optical fiber are arranged in an arc shape or a circular ring shape, the optical fibers can be efficiently arranged such that the irradiation-side optical fiber and the light-receiving-side optical fiber are adjacent to each other.

Due to the above-described operation, the film thickness measuring apparatus according to claim 1 can measure the optical film thickness with higher accuracy than the conventional apparatus.

Further, according to the film thickness measuring apparatus of the present invention, the film thickness measuring apparatus includes: an irradiation device that irradiates light to a substrate to be measured via an irradiation-side optical fiber composed of an optical fiber, in order to measure an optical film thickness of a film formed on the substrate to be measured; a light receiving device for receiving light reflected by the substrate to be measured after being irradiated from the irradiation device through a light receiving side optical fiber composed of an optical fiber, in order to measure the optical film thickness; and a probe in which a plurality of the irradiation-side optical fibers and a plurality of the light-receiving-side optical fibers are bundled, end faces of the irradiation-side optical fibers and end faces of the light-receiving-side optical fibers are arranged on facing surfaces as end faces provided on a side facing the substrate to be measured, the facing surfaces are arranged such that the end faces of the irradiation-side optical fibers are arranged in an arc shape or a circular ring shape while being adjacent to an end face of at least one of the light-receiving-side optical fibers, the end faces of the light-receiving-side optical fibers are arranged in an arc shape or a circular ring shape while being adjacent to end faces of at least one of the irradiation-side optical fibers, and a row of the end faces of the irradiation-side optical fibers and a row of the end faces of the light-receiving-side optical fibers are arranged so as to form a spiral opposite to each other, the probe is configured such that the facing surface is opposed to a non-film-formation surface of the substrate for measurement on a side opposite to a side on which the film is formed, in a state where no optical member is provided between the facing surface and the substrate for measurement.

In the above configuration, since the condensing lens and the light receiving lens are not used, light loss is suppressed, and reflected light can be received with relatively large illuminance when the reflected light is received by the light receiving side optical fiber. In addition, the S/N ratio when the light is subjected to spectroscopic analysis for film thickness calculation is increased in accordance with an increase in the amount of light received by the light-receiving-side optical fiber. Therefore, according to the configuration of claim 2, the optical film thickness can be measured with higher accuracy.

In the above-described film thickness measuring apparatus, it is more preferable that the plurality of irradiation-side optical fibers and the plurality of light-receiving-side optical fibers constituting the probe constitute a bundle-shaped optical fiber having end faces flush with the facing surface, and a distance between the facing surface and the film-forming surface is 2 times or more a diameter of the bundle-shaped optical fiber.

In the above configuration, the incident angle of light with respect to the thin film, in other words, the reflection angle of light reflected by the thin film is equal to or smaller than the numerical aperture NA of the light-receiving side optical fiber. In this case, the light receiving efficiency when light is received by the light receiving side optical fiber is further improved. Therefore, according to the configuration of claim 3, the optical film thickness can be measured with higher accuracy.

In the above-described film thickness measuring apparatus, the substrate for measurement may be a disk-shaped or annular substrate. That is, in the configuration according to claim 4, the optical film thickness of the thin film formed on the disc-shaped or annular substrate to be measured can be measured with high accuracy. Further, in a film thickness measuring apparatus capable of multipoint monitoring of film thickness, if a disk-shaped or annular substrate is used, the number of monitoring points can be further increased as compared with, for example, a rectangular substrate.

In the above film thickness measuring apparatus, the film thickness measuring apparatus may include: the irradiation device; a direct current stabilization power supply that supplies a direct current to a light source provided in the irradiation device; the probe; a spectroscope that includes the light receiving device and outputs an analog signal corresponding to a received light intensity when the light receiving device receives light reflected by the substrate for measurement; an amplifier that amplifies the analog signal output from the optical splitter; an A/D converter that converts the analog signal amplified by the amplifier into a digital signal; an electronic computer that calculates the optical film thickness based on the digital signal; and a signal processing circuit interposed between the a/D converter and the electronic computer, the signal processing circuit being configured to perform predetermined signal processing on the digital signal when the electronic computer calculates the optical film thickness. That is, the configuration according to claim 5 can measure the optical film thickness of the thin film with high accuracy, while including the same equipment as the configuration of the conventional thin film measuring apparatus.

In addition, the above-described problem is solved by a film deposition apparatus according to the present invention for depositing a deposition material on a surface of a substrate in a vacuum chamber to form a film on the substrate, the film deposition apparatus including: an evaporation mechanism for evaporating the evaporation material; an opening/closing member that opens and closes to cut a path of travel of the vapor deposition material evaporated by the evaporation mechanism toward the surface of the substrate; a control mechanism for controlling the opening and closing of the opening and closing member; and the film thickness measuring apparatus according to any one of claims 1 to 5, wherein the evaporation mechanism evaporates the vapor deposition material in order to vapor deposit the vapor deposition material on the surfaces of both the substrate and the substrate to be measured in a state where both the substrate and the substrate to be measured are housed in the vacuum chamber, the film thickness measuring apparatus measures the optical film thickness of a film formed on the substrate to be measured, and the control mechanism controls opening and closing of the opening and closing member based on a measurement result of the optical film thickness by the film thickness measuring apparatus.

In the film forming apparatus configured as described above, since the film thickness measuring apparatus capable of providing the above-described effects is provided, the film thickness can be measured with high accuracy, and further, the film thickness can be controlled based on the measurement result. Therefore, in the film deposition apparatus according to claim 6, the thickness of the thin film formed on the substrate can be accurately controlled based on the accurate measurement result of the optical film thickness.

In the above-described film formation apparatus, it is more preferable that the film thickness measurement device measures the optical film thickness of each of the multilayer films formed on the substrate to be measured layer by layer while the same substrate to be measured is disposed in the vacuum chamber and the multilayer film is also formed on the substrate to be measured while the multilayer film is formed on the substrate.

According to the above configuration, the optical film thickness of each layer of the multilayer film is measured every time each layer is formed on the measurement target substrate without replacing the measurement target substrate while the multilayer film is formed on the substrate, and therefore, the influence caused by changing the measurement target substrate every time the film thickness of each layer is measured can be suppressed. Therefore, if the film forming apparatus according to claim 7 is used, the film thickness of each layer of the multilayer film formed on the substrate can be measured with high accuracy, and the film thickness can be controlled with higher accuracy based on the measurement result.

ADVANTAGEOUS EFFECTS OF INVENTION

The film thickness measuring apparatus according to claim 1 can measure the optical film thickness with higher accuracy than the conventional apparatus.

In the film thickness measuring apparatus according to claim 2, the optical film thickness can be measured with higher accuracy according to the amount of increase in the S/N ratio of the spectroscopic analysis.

In the film thickness measuring apparatus according to claim 3, since the reflection angle of the light reflected by the thin film is equal to or smaller than the numerical aperture NA of the light-receiving side optical fiber, the optical film thickness can be measured with higher accuracy.

The film thickness measuring apparatus according to claim 4 can measure the optical film thickness of the thin film formed on the disk-shaped or annular substrate to be measured with high accuracy. Further, in a film thickness measuring apparatus capable of multipoint monitoring of film thickness, if a disk-shaped or annular substrate is used, the number of monitoring points can be further increased as compared with a rectangular substrate.

The film thickness measuring apparatus according to claim 5 is provided with the same equipment as that of a normal thin film measuring apparatus, and is capable of measuring the optical film thickness of the thin film with high accuracy.

The film forming apparatus according to claim 6 can measure the film thickness with high accuracy and control the film thickness with high accuracy based on the measurement result.

In the film forming apparatus according to claim 7, the influence of changing the substrate to be measured for each layer when measuring the optical film thickness of each layer of the multilayer film formed on the substrate can be suppressed, and accordingly, the film thickness of each layer of the multilayer film formed on the substrate can be measured with high accuracy, and the film thickness can be controlled with higher accuracy based on the measurement result.

Drawings

Fig. 1 is a diagram showing a schematic configuration of a film deposition apparatus according to the present embodiment.

Fig. 2 is a schematic side view of the probe of the present embodiment.

Fig. 3 (a) and (B) are diagrams showing arrangement positions of optical fibers in example 1.

Fig. 4 is a diagram showing the arrangement position of optical fibers in the comparative example.

Fig. 5 (a) and (B) are diagrams showing arrangement positions of optical fibers in example 2.

Fig. 6 is an explanatory diagram of the effectiveness of the arrangement position of the optical fibers according to the present embodiment.

Fig. 7 (a) and (B) are views showing other modifications of example 2.

Fig. 8 (a) and (B) are diagrams showing arrangement positions of optical fibers in example 3.

Fig. 9 is an explanatory view of an incident angle.

Detailed Description

Embodiments of the present invention (hereinafter, referred to as "the present embodiments") will be described below with reference to the drawings.

First, a schematic configuration of a film deposition apparatus according to the present embodiment will be described with reference to fig. 1. Fig. 1 is a diagram showing a schematic configuration of a film deposition apparatus according to the present embodiment.

The film forming apparatus according to the present embodiment is an apparatus for forming a multilayer film on a substrate by depositing a deposition material on a surface of the substrate in a vacuum chamber, and particularly is a vacuum deposition apparatus 100 for forming a film by a vacuum deposition method. In the vacuum deposition apparatus 100 of the present embodiment, a substrate (hereinafter, referred to as an actual substrate S) and a monitor substrate Sm for measuring film thickness are provided in the vacuum chamber 1, and the optical film thickness of the thin film formed on the monitor substrate Sm side can be measured while controlling the film thickness of the thin film formed on the actual substrate S side based on the measurement result.

Here, the actual substrate S is a substrate actually mounted on the thin film utilization device, and the actual substrate S is made of glass, for example. On the other hand, the monitor substrate Sm is a member used only for monitoring the film thickness, corresponding to the substrate to be measured, and is made of the same material as the actual substrate S, for example, glass. In particular, the monitor substrate Sm of the present embodiment is an annular substrate in plan view, and its preferred thickness is 1.0 to 2.0 mm.

In the present embodiment, a multilayer film is formed on the monitor substrate Sm under the same conditions as those of the actual substrate S. That is, in the present embodiment, the optical film thickness of the thin film on the actual substrate S side is controlled by monitoring the optical film thickness of the thin film on the monitor substrate Sm side while equally considering the optical film thickness of the thin film formed on the actual substrate S side and the optical film thickness of the thin film formed on the monitor substrate Sm side.

The structure of the vacuum vapor deposition apparatus 100 will be described, and as shown in fig. 1, the vacuum vapor deposition apparatus 100 includes, as main components, a vacuum chamber 1, a substrate holder 2, an evaporation mechanism 3, a shutter 4, a shutter control unit 5, and a film thickness measurement device 6.

An arcuate substrate holder 2 is housed in an upper space of the internal space of the vacuum chamber 1, and a plurality of actual substrates S are mounted on an inner surface of the substrate holder 2. An opening 2a is formed at the center of the inner surface of the substrate holder 2, and one monitor substrate Sm is disposed directly below the opening 2 a. The monitor substrate Sm disposed at this position is in a state where: a part of the monitor substrate Sm is exposed to the outside of the dome ドーム through the opening 2 a.

In addition, the substrate holder 2 is rotated around a rotation axis along the vertical direction during the film formation period, for the purpose of making the film formation amount uniform between the actual substrates S. During this time, the monitor substrate Sm is relatively rotated with respect to the substrate holder 2. That is, in the present embodiment, the monitor substrate Sm is held by a monitor substrate holder, not shown, which is separate from the substrate holder 2, and the substrate holder 2 and the monitor substrate holder are rotatable independently of each other.

On the other hand, the evaporation mechanism 3 is provided in a lower space of the internal space of the vacuum chamber 1. The evaporation mechanism 3 is a mechanism for evaporating a deposition material to be deposited on the actual substrate S or the monitor substrate Sm in order to form a thin film. Specifically, the evaporation mechanism 3 of the present embodiment is the same type of evaporation mechanism as an evaporation mechanism generally provided in a vacuum deposition apparatus, and examples thereof include an electron beam apparatus that heats and evaporates a deposition material held in a crucible, not shown, by an electron beam.

A shielding plate 4 is provided between the substrate holder 2 and the evaporation mechanism 3. The shutter 4 is an example of an opening/closing member, and the shutter 4 is moved to be opened and closed by a drive mechanism, not shown, in order to cut a traveling path of the vapor deposition material evaporated by the evaporation mechanism 3 toward the surface of the actual substrate S or the monitor substrate Sm. Specifically, when the shutter 4 is in the open position (the position of the shutter 4 shown by the solid line in fig. 1), the vapor deposition material evaporated by the evaporation mechanism 3 is scattered and can be supplied to the real substrate S or the monitor substrate Sm. On the other hand, when the shutter 4 is in the closed position (in fig. 1, the position of the shutter 4 indicated by the broken line), the shutter 4 blocks the vapor deposition material from scattering, and as a result, the vapor deposition material cannot be supplied to the real substrate S or the monitor substrate Sm.

The shutter control unit 5 corresponds to a control mechanism that controls opening and closing of the shutter 4, and in the present embodiment, the shutter control unit 5 is constituted by a 2 nd computer PC2 described later. Specifically, the 2 nd computer PC2 is connected to the shutter 4 via an interface not shown, and executes a control program installed in the 2 nd computer PC2 to output a control signal to the shutter 4. When the shutter 4 receives a control signal from the 2 nd computer PC2, the shutter 4 is opened and closed in accordance with the control signal.

The film thickness measuring device 6 is a device for measuring the optical film thickness of the thin film formed on the monitor substrate Sm, and particularly in the present embodiment, the film thickness measuring device 6 is a device for measuring the film thickness by the reflection method. That is, the film thickness measuring apparatus 6 of the present embodiment causes light to enter a thin film formed on the monitor substrate Sm, receives the light reflected by the monitor substrate Sm, and then disperses the reflected light to detect the light intensity (spectrum) for each wavelength. Then, the optical film thickness of the thin film formed on the monitor substrate Sm is calculated based on the detected light intensity.

The film thickness measuring apparatus 6 according to the present embodiment is an apparatus for measuring the optical film thickness of each layer film in a multilayer film formed on the monitor substrate Sm layer by layer. More specifically, as described above, the monitor substrate Sm rotates independently of the substrate holder 2, and a monitor substrate shield, not shown, is disposed directly below the monitor substrate Sm. The monitor substrate shield is a disk-shaped member, and an opening is formed in a central portion of the monitor substrate shield. A part of the monitor substrate Sm is exposed to the evaporation mechanism 3 through the opening.

On the other hand, in a state where both the actual substrate S and the monitor substrate Sm are housed in the vacuum chamber 1, the evaporation mechanism 3 evaporates the vapor deposition material in order to vapor deposit the vapor deposition material on the surfaces of both. As a result, thin films are formed on the deposition surfaces of the actual substrate S and the monitor substrate Sm under substantially the same conditions. At this time, the region of the deposition surface of the monitor substrate Sm on which the thin film is formed is only the region exposed through the opening formed in the monitor substrate shield.

As described above, in the present embodiment, a multilayer film is formed on the actual substrate S, and the vapor deposition material and the film formation conditions are switched to those for forming the next thin film layer each time the thin film of each layer is formed. On the other hand, although the multilayer film is also formed on the monitor substrate Sm under substantially the same conditions as the substrate, in the present embodiment, the monitor substrate Sm is rotated by a predetermined rotation angle relative to the stationary monitor substrate mask at a timing when the vapor deposition material and the film formation conditions are switched after completion of one layer of thin film. By rotating the monitor substrate Sm relative to the monitor substrate mask in this manner, the region of the monitor substrate Sm exposed through the opening formed in the monitor substrate mask is displaced in accordance with the above-described rotation angle, and as a result, the region in which the thin film is formed is displaced in accordance with the above-described rotation angle.

In the film formation process, a new thin film layer is formed in the monitor substrate Sm within an overlapping range of the region exposed before rotation (hereinafter referred to as the exposed region before rotation) and the region exposed after rotation (hereinafter referred to as the exposed region after rotation). On the other hand, a thin film of a new layer is not formed in a range that does not overlap with the exposed region after rotation in the exposed region before rotation. Therefore, the optical film thickness of the thin film to be formed is compared between the region of the monitor substrate Sm exposed before and after the rotation operation immediately before the film formation process is performed and the region not exposed after the rotation operation, and the film thickness of the thin film to be formed in each film formation process is determined.

Next, the structure of the film thickness measuring apparatus 6 according to the present embodiment will be described with reference to fig. 1 and 2. Fig. 2 is a schematic side view of the probe of the present embodiment.

As shown in fig. 1, the film thickness measuring apparatus 6 includes, as main components of the film thickness measuring apparatus 6: a projector 11, a DC stabilized power supply 12, a probe 13 for an optical sensor, a beam splitter 14, an amplifier 15, an A/D converter 16, a signal processing circuit 17, and 2 computers PC 1, PC 2.

The projector 11 is an example of an irradiation device, and the projector 11 irradiates the monitor substrate Sm with light through an irradiation side optical fiber f1 made of an optical fiber in order to measure the optical film thickness of a film formed on the monitor substrate Sm. Specifically, the projector 11 has a light source 21 formed of a halogen lamp or the like, and irradiates white light emitted from the light source 21 from the distal end surface of the optical sensor probe 13, in which the end surface of the irradiation side optical fiber f1 is disposed on the distal end surface of the optical sensor probe 13. Here, the projector 11 repeats turning off and on of the light source 21 in synchronization with the output cycle of the intensity of incident light in the spectroscope 14 in synchronization with the spectroscope 14. Then, a dc current is supplied from the dc stabilized power supply 12 to the light source 21 provided in the projector 11.

The spectrometer 14 includes a light receiving device 22, and outputs an analog signal corresponding to the received light intensity when the light receiving device 22 receives the light reflected by the monitor substrate Sm. More specifically, the light receiving Device 22 provided in the spectroscope 14 is constituted by, for example, a CCD (Charge Coupled Device), and the light receiving Device 22 receives light irradiated from the light projector 11 and reflected by the monitor substrate Sm through a light receiving side optical fiber f2 constituted by an optical fiber in order to measure the optical film thickness. The spectroscope 14 detects the light intensity (spectrum) of each wavelength after separating the light received by the light-receiving device 22, and outputs an electric signal according to the detection result. Here, the electric signal output from the spectroscope 14 corresponds to an analog signal corresponding to the received light intensity when the light receiving device 22 receives the reflected light.

The spectroscope 14 is configured to separate the light emitted from the projector 11 and output an electric signal indicating the intensity of the incident light for each wavelength of the incident light, that is, the intensity of the incident light. As described above, the spectroscope 14 outputs the electric signal indicating the intensity of the incident light and the electric signal indicating the intensity of the reflected light, respectively. The above 2 kinds of electric signals output from the spectroscope 14 are amplified by amplifiers 15, respectively, and then converted into digital signals by a/D converters 16. Then, the digital signal is input to the 2 nd computer PC 2.

The probe 13 for an optical sensor is an example of a probe, and is formed by bundling a plurality of irradiation side optical fibers f1 and a plurality of light receiving side optical fibers f 2. Specifically, as shown in fig. 2, the plurality of irradiation side optical fibers f1 connected to the projector 11 and the plurality of light receiving side optical fibers f2 connected to the light receiving device 22 are configured as bundles (bundles) and are accommodated in the flexible tube 23.

The irradiation side optical fiber f1 and the light receiving side optical fiber f2 each have a core and a cladding covering the core, and in the present embodiment, the core diameter is about 200 μm, and the optical fiber including the cladding has a diameter of about 235 μm.

Further, a connector 24A is attached to an end portion of the bundle of irradiation side fibers f1 on the side connected to the projector 11. Similarly, the connector 24B is attached to the end of the bundle of light-receiving side fibers f2 on the side connected to the light-receiving device 22.

The bundled irradiation side optical fiber f1 and light receiving side optical fiber f2 are bundled together at their free end sides to form the optical sensor probe 13. That is, the plurality of irradiation side optical fibers f1 and the plurality of light receiving side optical fibers f2 that constitute the probe 13 for the optical sensor constitute bundle-shaped optical fibers having end faces flush with each other on the surface of the free end side of the probe 13 for the optical sensor.

More specifically, as shown in fig. 2, the bundles of the optical fibers f1 and f2 are joined and collected by the intermediate connector 24C, and the optical fibers f1 and f2 are housed in the same flexible tube 23. Further, a cylindrical protection tube 25 is attached to one end portion of the irradiation side optical fiber f1 and the light receiving side optical fiber f2, which are bundled together and become a free end, and the protection tube 25 and the optical fibers f1 and f2 housed therein are disposed in the vacuum chamber 1.

The protection cylinder 25 is composed of a large diameter portion 25a and a small diameter portion 25b having different diameters, and the small diameter portion 25b constitutes the distal end portion of the optical sensor probe 13. The optical sensor probe 13 is provided such that one end surface of the small diameter portion 25b, which is the end surface thereof, faces the monitor substrate Sm at a position directly above the monitor substrate Sm. That is, one end surface of the small diameter portion 25b constituting the distal end surface of the optical sensor probe 13 corresponds to an opposed surface of the optical sensor probe 13 provided on the side opposed to the monitor substrate Sm.

In the small diameter portion 25b, the end faces of the irradiation side optical fiber f1 and the light receiving side optical fiber f2 are flush with each other. Therefore, the end faces of the plurality of irradiation side fibers f1 and the end faces of the plurality of light receiving side fibers f2 are disposed on the end face of the small diameter portion 25 b. Here, in the present embodiment, the end face of the irradiation side optical fiber f1 and the end face of the light receiving side optical fiber f2 are regularly arranged on one end face of the small diameter portion 25 b. The positions of the optical fibers f1 and f2 on the end surface of the small diameter portion 25b will be described in detail later.

As described above, the probe 13 for an optical sensor according to the present embodiment is configured by a bundle-shaped optical fiber in which a plurality of irradiation side optical fibers f1 and light receiving side optical fibers f2 are collected into one bundle. In the present embodiment, the number of the irradiation side optical fibers f1 and the light receiving side optical fibers f2 constituting the optical sensor probe 13 is 20 or more. Thus, the film thickness measuring apparatus 6 of the present embodiment can realize multipoint monitoring of the film thickness.

The 2 computers PC 1, PC2 can communicate with each other via ethernet (registered trademark), and the 1 st computer PC 1, which is one computer, is a computer that controls the projector 11. In the present embodiment, the 1 st computer PC 1 controls the light irradiation operation of the projector 11 via the programmable logic controller PLC for communication protocol conversion. The 2 nd computer PC2, which is another computer, is an example of an electronic computer, and calculates the optical film thickness of the thin film formed on the monitor substrate Sm based on a digital signal generated by converting the electric signal output from the optical splitter 14 by the a/D converter 16.

Further, a signal processing circuit 17 is interposed between the a/D converter 16 and the 2 nd computer PC 2. When the 2 nd computer PC2 calculates the optical film thickness, the signal processing circuit 17 performs predetermined signal processing on the above digital signal. Here, the predetermined signal processing is processing for converting the digital signal into a signal in a format suitable for the optical film thickness calculation performed by the 2 nd computer PC2, and is, for example, wavelet (wavelet) processing for removing components other than interference signals, frequency analysis processing, or the like.

As described above, the 2 nd computer PC2 corresponds to a control mechanism for controlling the opening and closing of the shutter 4, and controls the opening and closing of the shutter 4 based on the calculated value of the optical film thickness. Here, the calculated value of the optical film thickness calculated by the 2 nd computer PC2 is a measurement result of the optical film thickness measured by the film thickness measuring device 6.

The film thickness measuring apparatus 6 of the present embodiment described above is mostly the same in structure as a conventional reflection-type film thickness measuring apparatus, but 4 points described below are different from the conventional apparatus.

The point 1 is different in that no optical component such as a condenser lens or a light receiving lens is provided between the distal end surface of the optical sensor probe 13 and the monitor substrate Sm. That is, in the present embodiment, as shown in fig. 1, in a state where no optical component is provided between one end face of the small diameter portion 25b constituting the distal end face of the optical sensor probe 13 and the monitor substrate Sm, the optical sensor probe 13 is opposed to the non-deposition surface of the monitor substrate Sm at one end face of the small diameter portion 25 b. Here, the non-film-formation surface refers to a surface of the monitor substrate Sm which is located on the opposite side to the side on which the film is formed.

Since no optical component is provided between the distal end surface of the optical sensor probe 13 and the monitor substrate Sm in this way, the optical loss due to the passage of the optical component can be suppressed in the present embodiment. As a result, the light receiving side optical fiber f2 can receive the reflected light with a relatively large illuminance. Further, the S/N ratio when the light is subjected to spectroscopic analysis for calculating the film thickness can be increased according to the increase in the amount of light received by the light-receiving side fiber f 2. Therefore, the film thickness measuring apparatus 6 of the present embodiment can measure the optical film thickness with high accuracy.

In the case where no optical component is provided between the distal end surface of the optical sensor probe 13 and the monitor substrate Sm, the diameter of the effective light projecting spot can be regarded as corresponding to the diameter of the bundle fiber constituted by the irradiation side fiber f1 and the light receiving side fiber f2, that is, the diameter of the bundle fiber. Here, the bundle-shaped optical fiber diameter is a length defined by 2 end faces that are farthest from each other, out of the end faces of the plurality of irradiation side optical fibers f1 and the end faces of the plurality of light receiving side optical fibers f2 that are arranged on the distal end face of the optical sensor probe 13, and is about 1.8mm in the present embodiment.

The point 2 is different in that the distance between the distal end surface of the optical sensor probe 13 and the film formation surface of the monitor substrate Sm is 2 times or more the diameter of the bundle optical fiber. With this configuration, the incident angle of light with respect to the thin film, in other words, the reflection angle of light reflected by the thin film is equal to or smaller than the numerical aperture NA of the light-receiving side optical fiber f 2. In the present embodiment, the distance between the distal end surface of the probe 13 for an optical sensor and the film formation surface of the monitor substrate Sm is ensured to be 2 times or more the diameter of the bundle optical fiber by utilizing the above properties. As a result, the light receiving efficiency when light is received by the light receiving side optical fiber f2 is further improved, and the optical film thickness can be measured with higher accuracy.

Further, if the distance between the distal end surface of the probe 13 for an optical sensor and the film formation surface of the monitor substrate Sm is too short, the incident angle of light with respect to the thin film and the reflection angle of light reflected by the thin film become large, so that the light receiving efficiency of the probe 13 for an optical sensor (the ratio of the amount of light received by the probe 13 for an optical sensor to the amount of reflected light) decreases, resulting in a decrease in measurement accuracy. On the other hand, if the distance between the distal end surface of the optical sensor probe 13 and the film formation surface of the monitor substrate Sm is too long, the degree of attenuation increases during the period from when the light is reflected by the thin film until the light is received by the optical sensor probe 13, and therefore the measurement accuracy is degraded. On the other hand, if the distance between the distal end surface of the optical sensor probe 13 and the film formation surface of the monitor substrate Sm is 2 times or more, preferably 2 to 3 times, the diameter of the bundle optical fiber, it is possible to achieve a desired measurement accuracy.

Hereinafter, for convenience of explanation, the distance between the distal end surface of the optical sensor probe 13 and the film formation surface of the monitor substrate Sm will be referred to as the working distance WD.

The point of difference in the 3 rd embodiment is that the same monitor substrate Sm is disposed in the vacuum chamber 1 while the multilayer film is formed on the real substrate S, and the multilayer film is also formed on the monitor substrate Sm. That is, in the present embodiment, the monitor substrate Sm is not replaced while the multilayer film is formed on the actual substrate S. The film thickness measuring device 6 measures the optical film thickness of each layer film in the multilayer film formed on the monitor substrate Sm layer by layer. As a result, when the optical film thickness of each layer of the multilayer film is measured for each layer, the influence of the change of the monitor substrate Sm for each measurement can be suppressed.

Specifically, in a conventional film forming apparatus for forming a multilayer film, there is a film forming apparatus on which a monitor substrate changer (not shown) is mounted, and in such an apparatus, the monitor substrate changer replaces the monitor substrate Sm every time each layer of the multilayer film is formed on the actual substrate S. However, there may be variations in size, surface condition, and processing accuracy between monitor substrates, and the variations may affect the film measurement accuracy. That is, in terms of reproducibility of film thickness measurement, there is a problem in that the monitor substrate is replaced during the formation of the multilayer film.

In contrast, in the present embodiment, since the same monitor substrate Sm is continuously disposed in the vacuum chamber 1 while the multilayer film is formed on the actual substrate S, the influence of the deviation between the monitor substrates Sm does not affect the precision of the thin film measurement. Accordingly, the film thickness of each layer of the multilayer film formed on the monitor substrate Sm can be measured with high accuracy, and the optical film thickness of the film formed on the actual substrate S side can be controlled with higher accuracy based on the measurement result.

In the present embodiment, as described above, the annular substrate is used as the monitor substrate Sm, and the film thickness can be monitored at multiple points on the film thickness measuring apparatus 6 side. In the present embodiment, the bundle-shaped optical fiber has a diameter of about 1.8mm, and the optical sensor probe 13 includes 20 or more irradiation-side optical fibers f1 and light-receiving-side optical fibers f 2. As a result, in the film thickness measuring apparatus 6 of the present embodiment, the number of monitoring points (the number of measurement points) can be set to 80. In general, since 2 kinds of vapor deposition layers of a high refractive index vapor deposition material and a low refractive index vapor deposition material are formed on the monitor substrate Sm for the purpose of improving the light intensity and sensitivity, it is possible to cope with the case of forming a multilayer film composed of, for example, 160 layers (80 × 2) if the number of monitor dots is 80.

The 4 th difference is the arrangement position of the end surfaces of the irradiation side optical fiber f1 and the light receiving side optical fiber f2 on one end surface of the small diameter portion 25b as the distal end surface of the optical sensor probe 13. Specifically, in the present embodiment, each end face of the plurality of irradiation-side optical fibers f1 arranged on the distal end face of the optical sensor probe 13 is arranged in an arc shape or an annular shape so as to be adjacent to the end face of at least 1 light-receiving-side optical fiber f 2. Similarly, each of the end faces on which the plurality of light receiving side fibers f2 are disposed is disposed in an arc shape or an annular shape so as to be adjacent to each of the end faces of at least 1 of the irradiation side fibers f 1.

As described above, if the end face of the irradiation side optical fiber f1 and the end face of the light receiving side optical fiber f2 are adjacent to each other on the distal end face of the optical sensor probe 13, the incident angle of light irradiated from the light projector 11 to the film further decreases. Here, the size of the incident angle is 1/2 of the angle formed by the following 2 optical paths: an optical path when light irradiated from the end face of the irradiation side optical fiber f1 is directed to the film; and an optical path when the light is reflected on the surface of the thin film or the interface between the monitor substrate Sm and the thin film and directed to the end face of the light receiving side optical fiber f 2.

On the other hand, since the relationship shown in the above equation (1) holds between the incident angle θ and the measured value d of the film thickness, the measurement error Δ d of the film thickness increases as the incident angle θ increases. Specifically, when the refractive index of the film material is set to 1.47, the measurement errors Δ d are 0.07%, 0.2%, 0.5%, 0.7%, and 1.0%, respectively, when the incident angle θ is 3 °, 5 °, 8 °, 10 °, and 12 °. Conversely, the smaller the incident angle θ, the smaller the measurement error Δ d of the film thickness.

As described above, the farther the end face of the irradiation side optical fiber f1 and the end face of the light receiving side optical fiber f2 are apart from each other, the lower the light receiving efficiency, which is the ratio of the amount of light received by the light receiving side optical fiber f2, among the amounts of light reflected by the film. In contrast, if the end face of the irradiation side optical fiber f1 and the end face of the light receiving side optical fiber f2 are adjacent to each other, the light receiving efficiency is improved.

In addition, regarding the accuracy of film thickness measurement, since the higher the filling rate of the optical fibers in the distal end surface of the optical sensor probe 13, the higher the accuracy of film thickness measurement, the end surfaces of the optical fibers are generally arranged densely in the distal end surface of the optical sensor probe 13. On the other hand, the closer the end faces of the optical fibers are, the more easily the end faces of the irradiation side optical fiber f1 and the end face of the light receiving side optical fiber f2 become dense. Further, if the end surfaces of the same kind of optical fibers are arranged densely in a block, the end surface of the irradiation side optical fiber f1 and the end surface of the light receiving side optical fiber f2 are easily separated.

In contrast, if the optical fibers are arranged on the distal end surface of the optical sensor probe 13 such that the end surface of the irradiation side optical fiber f1 and the end surface of the light receiving side optical fiber f2 are arranged in an arc shape or a circular ring shape, the optical fiber arrangement in which the irradiation side optical fiber f1 and the light receiving side optical fiber f2 are adjacent to each other can be realized efficiently.

As an optical fiber arrangement in which the irradiation side optical fiber f1 and the light receiving side optical fiber f2 are adjacent to each other, the following arrangement is also conceivable: on the distal end surface of the optical sensor probe 13, the end surface of the irradiation side optical fiber f1 and the end surface of the light receiving side optical fiber f2 are aligned in a row, and the rows of the respective optical fibers are alternately arranged. However, in the case where the end faces of the optical fibers are densely arranged in the distal end surface of the optical sensor probe 13 for the above-described reason, it is physically difficult to realize an optical fiber arrangement in which the end face of the irradiation side optical fiber f1 and the end face of the light receiving side optical fiber f2 are arranged in a row and the rows of the various optical fibers are alternately arranged. Therefore, it is preferable to arrange the optical fibers such that the end surfaces of the optical fibers are arranged in an arc shape or a circular ring shape as in the present embodiment, because this is more efficient.

Due to the above-described operation, the film thickness measuring device 6 of the present embodiment can measure the optical film thickness more accurately than the conventional device.

Next, specific examples (examples 1 to 3) relating to the arrangement positions of the end faces of the irradiation side optical fiber f1 and the light receiving side optical fiber f2 on the distal end face of the optical sensor probe 13 will be described with reference to fig. 3 to 8.

Fig. 3 (a) and (B) are diagrams showing arrangement positions of optical fibers in example 1. Fig. 4 is a diagram showing the arrangement position of optical fibers in the comparative example. Fig. 5 (a) and (B) are diagrams showing arrangement positions of optical fibers in example 2. Fig. 6 is an explanatory diagram of the effectiveness of the arrangement position of the optical fibers according to the present embodiment, in which the solid line graph represents the data of example 1 and the broken line graph represents the data of the comparative example. Fig. 7 (a) and (B) are views showing other modifications of example 2. Fig. 8 (a) and (B) are diagrams showing arrangement positions of optical fibers in example 3. In fig. 3, 4, 6, 7, and 8, black circles indicate the arrangement positions of the irradiation side optical fibers f1, and white circles indicate the arrangement positions of the light receiving side optical fibers f 2.

First, the arrangement positions of the optical fibers in example 1 are explained, and as shown in fig. 3 (a) and (B), the irradiation side optical fiber f1 and the light receiving side optical fiber f2 are arranged such that the irradiation side optical fiber f1 and the light receiving side optical fiber f2 form opposite spirals to each other, and the entire optical fiber bundle is arranged in a circular shape. Since fig. 3 (a) and (B) show a configuration in which the arrangement position of the irradiation side optical fiber f1 and the arrangement position of the light receiving side optical fiber f2 are reversed from each other, only the configuration shown in fig. 3 (a) will be described below.

In example 1, as described above, the irradiation side optical fiber f1 and the light receiving side optical fiber f2 are arranged in an arc shape, more specifically, in a spiral shape. Thus, in example 1, the light can be irradiated to each portion of the monitor substrate Sm in the effective light projection range with a uniform light amount, and the light reflected by the monitor substrate Sm can be received under uniform conditions.

In addition, in example 1, the maximum incident angle is about 8.4 °, and the effective incident angle is about 1.5 °. Here, the maximum incident angle corresponds to half of the angle between the irradiation side optical fiber f1 and the light receiving side optical fiber f2 that are farthest from each other on the distal end surface of the optical sensor probe 13, and in fig. 3 (a), corresponds to half of the angle formed by the optical path of light irradiated from the irradiation side optical fiber f1 located on the outermost side and the optical path of light directed toward the light receiving side optical fiber f2 located at the center of the optical fiber bundle. The effective incident angle corresponds to half of the angle formed by the optical path of the light irradiated from the irradiation side optical fiber f1 and the optical path of the light directed toward the light receiving side optical fiber f2 adjacent to the optical fiber f 1.

The validity of the arrangement position of the optical fibers in example 1 is explained, and in example 1, the maximum incident angle and the effective incident angle are smaller than those in the comparative example shown in fig. 4. More specifically, in the comparative example, the plurality of irradiation-side optical fibers f1 are arranged in a semicircular shape, and the plurality of light-receiving-side optical fibers f2 are arranged in a semicircular shape, so that the entire optical fiber bundle is arranged in a circular shape.

In the comparative example, the maximum incident angle was about 11.1 °, and the effective incident angle was about 6 °. Here, the maximum incident angle in the comparative example corresponds to half of the angle formed by the optical path of the light irradiated from the irradiation side fiber f1 located at the outermost side and the optical path of the light directed to the light receiving side fiber f2 located at the farthest position from the optical fiber f 1. The effective incident angle in the comparative example corresponds to half the angle formed by the optical path of the light irradiated from the irradiation side optical fiber f1 at the center of gravity and the optical path of the light directed to the light receiving side optical fiber f2 at the center of gravity. The center of gravity position is a position of the center of gravity of the optical fiber group collected in a semicircular shape, and when the radius of the semicircle formed by the optical fiber group is r, the relative position of the center of gravity to the center of the semicircle can be expressed by a coordinate of (0, 2 r/pi).

As described above, in example 1, the maximum incident angle and the effective incident angle become smaller as compared with the comparative example. This is because, in example 1, the dispersion degree of each of the irradiation side optical fiber f1 and the light receiving side optical fiber f2 is increased, and the ratio of the irradiation side optical fiber adjacent to the light receiving side optical fiber f2 in the irradiation side optical fiber f1 and the ratio of the light receiving side optical fiber adjacent to the irradiation side optical fiber f1 in the light receiving side optical fiber f2 become higher than in the comparative example. Thus, in example 1, the effective light projection range is reduced and the measurement error of the optical film thickness is reduced compared to the comparative example.

In example 1, the relative reflected light amount (the ratio of the light amount of the reflected light to the light amount of the incident light) in the range of the working distance WD of 0 to 7mm is further increased as compared with the comparative example. Therefore, in the case where the working distance WD is in the range of 0 to 7mm, in example 1, the reflected light can be received with a higher light amount than in the comparative example. This improves the accuracy of spectroscopic analysis by the spectroscope 14, resulting in an improvement in the accuracy of measurement of the optical film thickness.

Next, the arrangement position of the optical fibers in example 2 will be described, and as shown in fig. 5 (a) and (B), the irradiation side optical fiber f1 and the light receiving side optical fiber f2 are arranged in a circular ring shape, and the circular rings formed by the optical fibers f1 and f2 are alternately arranged in a concentric circle shape. Since fig. 5 (a) and (B) show a configuration in which the arrangement position of the irradiation side optical fiber f1 and the arrangement position of the light receiving side optical fiber f2 are reversed from each other, only the configuration shown in fig. 5 (a) will be described below.

In example 2, as described above, the irradiation side optical fiber f1 and the light receiving side optical fiber f2 are arranged in an annular shape, and thus, the respective portions of the monitor substrate Sm in the effective light projection range can be irradiated with light of uniform quantity, and further, the light reflected by the monitor substrate Sm can be received under uniform conditions.

In addition, in example 2, the maximum incident angle is about 4.2 °, and the effective incident angle is about 1.5 °. Further, as shown in fig. 6, in example 2, the relative reflected light amount in the range of the working distance WD from 0 to 7mm is further increased as compared with the comparative example. Therefore, in the case where the working distance WD is in the range of 0 to 7mm, in example 2, the reflected light can be received with a higher light amount than in the comparative example, and as a result, the accuracy of the spectroscopic analysis by the spectroscope 14 is improved, and the accuracy of the measurement of the optical film thickness is improved.

As another modification of disposing the optical fibers in an annular shape, as shown in (a) and (B) of fig. 7, a configuration may be considered in which: the irradiation side fiber f1 is replaced with the light receiving side fiber f2 at an interval of about 90 ° in the outermost ring of the rings formed by the irradiation side fiber f 1. With such an arrangement, in example 2, the difference between the ratio of the light receiving side optical fiber f2 and the ratio of the irradiation side optical fiber f1 in the number of optical fibers in the optical fiber bundle is further smaller than in example 1. That is, it is preferable that the number of the irradiation side optical fibers f1 and the number of the light receiving side optical fibers f2 are close to each other in terms of the function of the probe, and for this reason, the optical fiber arrangement as shown in fig. 7 (a) or (B) may be adopted.

Next, the arrangement position of the optical fiber in example 3 will be explained. The example 3 is different from the above-described examples 1 and 2 in that the irradiation side optical fiber f1 and the light receiving side optical fiber f2 are not arranged in an arc shape or a circular ring shape. Specifically, in example 3, as shown in fig. 8 (a) and (B), 5 irradiation side optical fibers f1 arranged in a substantially V shape are arranged at regular intervals along the outer periphery of the optical fiber bundle, and a light receiving side optical fiber f2 is arranged so as to fill the gap between the irradiation side optical fibers f1 and the center of the optical fiber bundle, and the optical fiber bundle is arranged in a circular shape as a whole. In example 3, the maximum incident angle is about 8.4 °, and the effective incident angle is about 1.5 °. Therefore, in example 3, the maximum incident angle and the effective incident angle are smaller than those of the comparative example, and the effective light projection range is also smaller. Fig. 8 (a) and (B) show a configuration in which the arrangement position of the irradiation side fiber f1 and the arrangement position of the light receiving side fiber f2 are reversed from each other.

The film thickness measuring apparatus and the film deposition apparatus according to the present embodiment have been described above, but the present embodiment is merely an example for facilitating understanding of the present invention, and the components, the arrangement, and the like described above are not limited to the present invention, and various changes and improvements can be made according to the gist of the present invention, and it is needless to say that the present invention includes equivalents thereof. For example, the above description of the size, dimension, shape, and material of each device constituting the thin film measuring apparatus is merely an example for showing the effects of the present invention, and does not limit the present invention.

In the above-described embodiment, the vacuum vapor deposition apparatus 100 that forms a film by the vacuum vapor deposition method was described as an example of the film formation apparatus, but the present invention may be applied to a film formation apparatus that forms a film by the ion plating method or a film formation apparatus that forms a film by the ion beam vapor deposition method. The present invention is also applicable to a film deposition apparatus using a sputtering method in which ions are caused to strike a target to form a film.

In the above-described embodiment, the working distance WD, which is the distance between the distal end surface of the optical sensor probe 13 and the film formation surface of the monitor substrate Sm, is set to 2 times or more the diameter of the bundle optical fiber in order to improve the light receiving efficiency of the reflected light. However, the distance between the end surface of the optical sensor probe 13 and the film formation surface of the monitor substrate Sm may be less than 2 times the diameter of the bundle optical fiber.

In the above-described embodiment, an annular substrate is used as the monitor substrate Sm. For example, when measuring the optical film thickness and the film thickness by a quartz film thickness meter, an annular substrate is effective. This is because, in a film deposition apparatus that normally uses an annular monitor substrate Sm, the quartz film thickness gauge can be arranged at the center of the apparatus, specifically, at a position corresponding to the center of the substrate holder 2, for reasons of apparatus configuration. However, the monitor substrate Sm is not limited to an annular substrate, and may be a substrate having another shape, for example, a disk-shaped substrate.

In the above-described embodiment, the multilayer film is formed on the monitor substrate Sm side without replacing the monitor substrate Sm while the multilayer film is formed on the actual substrate S. That is, it may be: the monitor substrate Sm is replaced each time each of the multilayer films is formed. However, as described above, there are variations in size, surface condition, and processing accuracy between monitor substrates, and if the monitor substrate Sm is replaced each time the film thickness of each layer is measured, the above-described variations affect the measurement accuracy. In this regard, it is preferable that the monitor substrate Sm is not replaced while the multilayer film is formed on the actual substrate S.

In the above-described embodiment, the film formation apparatus for forming a multilayer film on the actual substrate S was described as an example, but the present invention can also be applied to an apparatus for forming a single-layer film on the actual substrate S.

Description of the reference symbols

1: a vacuum vessel;

2: a substrate holder;

2 a: an opening;

3: an evaporation mechanism;

4: a shielding plate;

5: a shutter control unit;

6: a film thickness measuring device;

11: a light projector;

12: a direct current stabilized power supply;

13: a probe for an optical sensor;

14: a light splitter;

15: an amplifier;

16: an A/D converter;

17: a signal processing circuit;

21: a light source;

22: a light receiving device;

23: a flexible tube;

24A: a connector;

24B: a connector;

24C: an intermediate connector;

25: a protective cylinder;

25 a: a large diameter portion;

25 b: a small diameter part;

100: a vacuum evaporation device;

f 1: an irradiation side optical fiber;

f 2: a light receiving side optical fiber;

PC 1: a 1 st computer;

PC 2: a 2 nd computer;

PLC: a programmable logic controller;

s: an actual substrate;

sm: the substrate is monitored.

Claims (6)

1. A film thickness measuring apparatus is characterized in that,

the film thickness measuring apparatus includes:

an irradiation device that irradiates light to a substrate to be measured via an irradiation-side optical fiber composed of an optical fiber, in order to measure an optical film thickness of a film formed on the substrate to be measured;

a light receiving device for receiving light reflected by the substrate to be measured after being irradiated from the irradiation device through a light receiving side optical fiber composed of an optical fiber, in order to measure the optical film thickness; and

a probe formed by bundling a plurality of the irradiation-side optical fibers and a plurality of the light-receiving-side optical fibers,

the probe is provided with a plurality of end faces of the irradiation-side optical fibers and a plurality of end faces of the light-receiving-side optical fibers on opposing surfaces which are end faces provided on a side opposing the substrate for measurement,

wherein the facing surface is formed by arranging end surfaces of the plurality of irradiation-side optical fibers in an arc shape or a circular ring shape so as to be adjacent to an end surface of at least one of the light-receiving-side optical fibers, and the end surfaces of the plurality of light-receiving-side optical fibers are arranged in an arc shape or a circular ring shape so as to be adjacent to an end surface of at least one of the irradiation-side optical fibers, and the end surfaces of the irradiation-side optical fibers and the end surfaces of the light-receiving-side optical fibers are arranged in a row so as to form a spiral in the opposite direction to each other,

the probe is configured such that no optical component is provided between the facing surface and the substrate for measurement, and the facing surface is opposed to a non-film-formation surface of the substrate for measurement, the non-film-formation surface being located on a side opposite to a side on which the film is formed.

2. The film thickness measuring apparatus according to claim 1,

the plurality of irradiation-side optical fibers and the plurality of light-receiving-side optical fibers constituting the probe constitute bundle-shaped optical fibers having end surfaces flush with the facing surfaces,

the distance between the facing surface and the film-forming surface is 2 times or more the diameter of the bundle-shaped optical fiber.

3. The film thickness measuring apparatus according to claim 2,

the substrate for measurement is a disk-shaped or annular substrate.

4. The film thickness measuring apparatus according to claim 1,

the film thickness measuring apparatus includes:

the irradiation device;

a direct current stabilization power supply that supplies a direct current to a light source provided in the irradiation device;

the probe;

a spectroscope that includes the light receiving device and outputs an analog signal corresponding to a received light intensity when the light receiving device receives light reflected by the substrate for measurement;

an amplifier that amplifies the analog signal output from the optical splitter;

an A/D converter that converts the analog signal amplified by the amplifier into a digital signal;

an electronic computer that calculates the optical film thickness based on the digital signal; and

a signal processing circuit interposed between the A/D converter and the electronic computer, the signal processing circuit being configured to perform predetermined signal processing on the digital signal when the electronic computer calculates the optical film thickness.

5. A film forming apparatus for forming a film on a substrate by depositing a deposition material on a surface of the substrate in a vacuum chamber,

the film-forming apparatus is characterized in that,

the film forming apparatus includes:

an evaporation mechanism for evaporating the evaporation material;

an opening/closing member that opens and closes to cut a path of travel of the vapor deposition material evaporated by the evaporation mechanism toward the surface of the substrate;

a control mechanism for controlling the opening and closing of the opening and closing member; and

the film thickness measuring apparatus according to any one of claims 1 to 4,

in order to deposit the vapor deposition material on the surfaces of both the substrate and the substrate to be measured in a state where both the substrate and the substrate to be measured are housed in the vacuum chamber, the evaporation mechanism evaporates the vapor deposition material, the film thickness measurement device measures the optical film thickness of a film formed on the substrate to be measured, and the control mechanism controls the opening and closing of the opening and closing member based on the measurement result of the optical film thickness by the film thickness measurement device.

6. The film forming apparatus according to claim 5,

while forming a multilayer film on the substrate, disposing the same substrate for measurement in the vacuum vessel, and forming the multilayer film also on the substrate for measurement,

the film thickness measuring device measures the optical film thickness of each layer film in the multilayer film formed on the substrate to be measured layer by layer.