JP2009007651A - Method of film-coating neutral-density filter, apparatus for forming neutral-density filter, neutral-density filter using the same, and image pick-up light quantity diaphragm device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film coating method where, when film layer is formed in response to optical characteristics on substrate, gradation range layer can be stably formed on a plurality of substrates at the same time without variation. <P>SOLUTION: In the method of film-coating neutral-density filter where, in a film coating chamber, target is sputtered with a working gas, the plurality of targets at least composed of first and second substances with different optical properties is sputtered on substrate with the working gas, and a dielectric film layer and a metal film layer are formed, so as to be a stacked shape, the dielectric film layer is film-formed in such a manner that each target composed of a dielectric substance or a metal substance is sputtered with a working gas, so as to form a film on each substrate with sputtered particles, and thereafter, the formed film is irradiated with plasma, and a film is formed with the produced compound. Further, the metal film layer is film-formed in such a manner that each target composed of a metal substance is sputtered with a working gas, so as to form a film on the substrate with sputtered particles, or the formed film is irradiated with plasma, and a film is formed with the produced compound. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a neutral density filter that adjusts the amount of light of a photographing device such as a video camera or a digital still camera, a film forming method thereof, a manufacturing apparatus, and a light amount restricting device. The present invention relates to an improvement in gradation film formation that gradually decreases.

  In general, this type of neutral density filter is widely used as an ND filter (Neutral Density Filter) in various imaging apparatuses. This ND filter forms a thin film having excellent light absorption characteristics on a resin or glass substrate. The ND filter is known to be formed as a single thin film having a uniform concentration as a whole, or as a gradation thin film whose density is continuously changed (gradual decrease).

  In recent years, as the resolution of an imaging apparatus increases, image quality degradation such as image blur due to the influence of diffracted light tends to be noticeable when the amount of light is reduced under bright subject conditions. Therefore, for example, as disclosed in Patent Document 1, it has been proposed to attach an ND filter to an aperture blade that adjusts the amount of light to suppress a diffraction phenomenon that occurs at the time of small aperture. In the case of a single-density ND filter, diffraction occurs due to the small aperture formed by the end of the ND filter and the aperture shape, resulting in degradation of image quality. In order to prevent the deterioration, there has been proposed a gradation filter in which the density gradually decreases toward the opening diameter side.

  Conventionally, as a film forming method for producing such a gradation filter, it has been proposed to produce the gradation filter by a micro-photographic method (for example, Japanese Patent No. 2754518). For example, Patent Document 2 discloses the creation of a gradation layer with a deposited film.

  In Patent Document 2, a substrate (deposition base material) is mounted on a sample stage of a vacuum vapor deposition apparatus (physical vapor deposition method), and an evaporation component is heated and evaporated while the stage is rotated (revolved) to form a film on the substrate. A gradation film forming method is disclosed. Thus, it is widely known that a thin film is produced by vacuum deposition or sputtering.

  However, in general vacuum deposition apparatus or sputtering apparatus, it is impossible to form a film by linearly changing (gradually decreasing) the film thickness. That is, this type of apparatus is configured for the purpose of producing a uniform thin film. In order to form a gradation film using a vacuum vapor deposition apparatus in Patent Document 2, the following measures are taken. The gradation film generation mechanism disclosed in Patent Document 2 is shown in FIG. In this film forming method, a large number of substrates 50 are mounted radially on a vapor deposition stage (vapor deposition umbrella) 51 as shown in FIG. Then, a mask 53 having an opening 52 is arranged at a position spaced from the vapor deposition stage 51, and the vapor deposition stage 51 and the mask 53 are equipped in the apparatus so as to rotate (revolve) about the same axis X. Therefore, the vapor deposition source 54 is disposed at a position Y that is offset from the rotation axis X by a predetermined amount. In this state, the vapor deposition stage 51 is rotated to evaporate film forming components from the vapor deposition source. Then, a part of the film forming component emitted from the vapor deposition source 54 adheres to the substrate from the opening 52 and the other is blocked by the mask 53.

  When the vapor deposition stage 51 and the mask 53 are rotated (revolved) with such a structure, a geometrical relationship as shown in FIG. That is, when the vapor deposition source 54 is expressed as a point evaporation source with respect to the substrate 50 mounted on the stage 51, the vapor deposition source 54 rotates along an arc locus inclined at a predetermined angle θ as shown in the figure. The inclination angle θ coincides with the angle θ of the substrate 50 mounted on the dome-shaped stage 51. Therefore, the vapor deposition component is projected from the evaporation source 54 to the substrate 50 through the opening 52 of the mask 53 along an arc locus inclined at an angle θ. Accordingly, a film layer having a film thickness d gradually decreasing from d1 to d2 is formed on the substrate as shown in FIG. With this film layer, the transmitted light amount has a high transmittance in a portion with a high density (film thickness d1), and a low transmittance in a portion with a low density (film thickness d2).

In the case of generating a conventional gradation film, a mask plate is provided between the substrate and the target in the vapor deposition tank as described above, and is formed from a position inclined by a predetermined angle (α angle shown in FIG. 1) with respect to the mask opening. The film component (evaporated particles) is formed to evaporate. Therefore, although not disclosed in Patent Document 2, the distance between the target and the mask plate L1 in FIG. 1 is set sufficiently larger (longer) than the distance d between the mask plate and the substrate, and vapor deposition projected from the target. The component is controlled to draw a straight line like parallel rays. As a result, the geometrically formed film thickness changes linearly as shown in FIG.
Japanese Patent No. 2754518 (FIGS. 1 and 4) Japanese Patent Laying-Open No. 2005-345746 (FIG. 1)

  As described above, there is known a gradation filter formed so as to have a thickness such that the density gradually decreases toward the center of the optical path when the amount of imaging light is attenuated in various imaging apparatuses. Conventionally, the gradation filter is formed into a film by a vapor deposition apparatus as described in Patent Document 1 described above. However, this method has a problem that when a plurality of filter materials are generated at the same time, the film thickness differs for each material and the yield is extremely bad. That is, when a filter having a predetermined attenuation rate is mass-produced, individual attenuation characteristics are different, and there is a defect that optical characteristics vary.

  Along with this, there is a problem that the film thickness does not change uniformly (linearly). This is because when the ideal film thickness is expressed by a broken line in FIG. 5B, the filter produced by the method of the above-mentioned Patent Document 2 has a disadvantage that the optical characteristics vary as shown by the chain line in FIG. As described above, in the conventional method of forming a gradation filter using a vapor deposition apparatus, it is known that there are large variations in the optical characteristics of individual materials when a plurality of substrates are produced simultaneously, and the gradation film layer does not attenuate linearly. Yes. Therefore, it is said that the production requires advanced experience and know-how such as vacuum state management in the tank, vapor deposition condition management of vapor deposition components, and float condition management of vapor deposition components in the tank.

The reason why the optical characteristics vary for each material in the film forming method disclosed in Patent Document 2 is considered to be as follows. First, as shown in the geometric model in FIG. 2, the substrate 50 (a, b, c) is mounted on the dome-shaped stage 51 in a state where the angles θ are different (θ ₁ , θ ₂ , θ ₃ ). ing. The masks 53 (x, y, z) corresponding to the respective substrates 50 are arranged at the same angle θ (θ ₁ , θ ₂ , θ ₃ ). The evaporation source 54 is disposed at a position offset from the rotation center by a predetermined angle (α angle shown in FIG. 2) with respect to the stage (vapor deposition umbrella) on which the substrate and the mask are mounted.

Accordingly, the vapor deposition components scattered from the vapor deposition source 54 pass through the mask at different angles to form a film on the substrate. Therefore, film layers having different widths are formed on the substrate 50a and the substrate 50b. At the same time, in the stage 51 that rotates about the rotation axis X, the vapor deposition components from the vapor deposition source 54 are different in the illustrated distances L ₁ and L ₂ between the substrate 50a and the substrate 50b. Accordingly, the film thicknesses formed on both the substrates are naturally different, and this is analyzed as the cause of the variation in the optical characteristics for each material.

Next, the reason why the film layer is not linearly attenuated in the film forming method disclosed in Patent Document 2 is considered to be as follows. In the film forming method of this document, as shown in FIG. 1, gradation layers are formed before and after the direction in which the substrate and the mask plate rotate. For this reason, the gradation layer adheres to the evaporation component emitted from the evaporation source while rotating on the substrate. In such film formation, the atmosphere in the chamber changes as the substrate rotates. Due to this change, the deposited film thickness becomes unstable, and the film thickness as geometrically formed cannot be obtained. At the same time, in the film forming method in which the vapor deposition material is heated and vapor-deposited in the vapor deposition tank of the same document, the particles of the film formation material are large (compared to film formation by reactive sputtering of the present invention described later), Since the particles are large, it is analyzed that the film thickness varies greatly if the film forming conditions change slightly. At the same time, for example, when silicon dioxide is used as the vapor deposition component, the component deposited from the vapor deposition source is generated in an unstable state such as “SiO ₂ ”, “SiO”, or an intermediate oxide thereof. Such an oxide shift is randomly generated by the film forming means, so that it is considered that a stable film layer cannot be formed.

  In view of this, the present inventor paid attention to the generation of a gradation filter using a known reactive sputtering apparatus (for example, Japanese Patent Application Laid-Open No. 11-279757), and in this case, devised a film forming method in which the above-described variation does not occur. It came to do.

The present invention provides a film forming method capable of stably forming a gradation layer with a gradually decreasing film thickness on a plurality of substrates simultaneously on a transparent substrate without variation. The main challenge is to provide
Furthermore, the present invention is capable of gradually decreasing the thickness of the gradation layer linearly, and at the same time, a film forming method and manufacturing apparatus for a neutral density filter that does not deteriorate with time, and a neutral density filter using the same. Offering is the issue.

  To achieve the above object, the present invention employs the following configuration. A target is sputtered with a working gas in a deposition chamber, and a plurality of targets made of at least first and second materials having different optical characteristics are sputtered with a working gas on a substrate to laminate a dielectric film layer and a metal film layer. The dielectric film layer is formed by sputtering a target made of a dielectric material or a metal material with an operating gas and forming a film with sputtered particles on the substrate, The formed film is formed with a compound generated by irradiating plasma. The metal film layer is formed by sputtering a target made of a metal substance with an operating gas and forming a film with sputtered particles on the substrate, or forming a film with a compound generated by irradiating the formed film with plasma. The dielectric film layer and the light-absorbing metal film are formed by (1) mounting the substrate on a cylindrical rotating drum disposed in the film forming chamber, and (2) forming the target with a plate-like material. (3) A mask plate having a mask opening is arranged on the rotating drum so as to form a predetermined film-forming gap between the substrate and the substrate surface. Therefore, a film is formed by applying a sputtering voltage to the target while rotating the rotating drum, and the film is formed on the substrate from the mask opening of the mask plate on the front edge and the rear edge in the rotation direction of the rotating drum. A gradation layer is formed in which the film thickness gradually decreases due to the diffusion of sputtered particles generated in the gap.

  The substrate and the mask plate are arranged on the circumference of the rotating drum, and the film forming gap is formed by a spacer member arranged between the substrate and the mask plate. At least one of the front and rear edges of the mask opening formed on the mask plate is arranged on a straight line orthogonal to the rotation direction of the rotary drum.

  The film formation cap between the substrate and the mask plate is formed at a predetermined interval set according to the film formation width of the gradation layer. The film formation gap between the substrate and the mask plate is formed at a predetermined interval with respect to the distance between the target and the substrate.

  The neutral density filter according to the present invention includes a substrate, and a dielectric film layer and a metal film layer formed in a laminated manner on the substrate. The dielectric film layer is formed by sputtering a target made of a dielectric substance with a working gas and then irradiating with a reactive gas. The metal film layer is formed by applying a target made of a metal substance to the working gas. The film is formed by sputtering. At this time, the dielectric film layer and the metal film layer are formed by diffusion of sputtered particles from a mask opening edge of a mask plate that forms a film formation gap with the substrate when the target is sputtered. Forms a gradation layer that gradually decreases.

  An imaging light amount diaphragm device according to the present invention is configured by an aperture blade that is disposed in an imaging optical path and adjusts an imaging light amount, and a neutral density filter attached to the aperture blade. The neutral density filter has the above-described configuration.

  An attenuating filter manufacturing apparatus according to the present invention is an attenuating filter manufacturing apparatus for forming a dielectric film layer and a metal film layer on a substrate in a layered form, and includes a film forming chamber and the film forming chamber. A cylindrical rotating drum disposed on the rotating drum, a plurality of substrates mounted on the rotating drum, and a dielectric material disposed at a distance from the substrate in a first area partitioned in the film forming chamber. A first target comprising: a reactive gas supply source disposed in a second area of the film forming chamber; and a second target comprising a metal material disposed in the third area of the film forming chamber. And a working gas supply source for sputtering disposed in the first area and the third area. The first and second targets are made of a plate-like material and are arranged in the film formation chamber substantially parallel to the substrate surface, and a mask plate having a mask opening is provided between the rotary drum and the substrate. Are arranged so as to form a film forming gap. Therefore, a film is formed by applying a sputtering voltage to the target while rotating the rotating drum, and this film formation forms a gradation layer in which the film thickness gradually decreases due to diffusion of sputtered particles generated in the film forming gap.

  The mask plate is arranged so that the front and rear edges of the mask opening are orthogonal to the rotation direction of the rotary drum. A gradation layer is formed on the substrate at the front edge and the rear edge in the rotational direction of the rotating drum.

  In the present invention, when a film is formed by mounting a substrate on the peripheral surface of a cylindrical rotating drum disposed in a film forming chamber, the target is configured in a plate shape and disposed substantially parallel to the substrate surface, Since the target is sputtered to form a film through this substrate and a mask plate that forms a predetermined film formation gap, the following effects can be obtained.

  The substrate and the mask plate mounted on the rotating drum always maintain the same geometric positional relationship with respect to the target when the film is formed by rotating the rotating drum. Therefore, since the positional relationship of each factor for film formation is stable, a substantially uniform film layer is formed even if a plurality of substrates (film formation base materials) are arranged on the rotating drum, and the film layers of each substrate vary. Will not occur.

  The dielectric film layer formed on the substrate is formed by sputtering a target made of a dielectric substance with an operating gas (such as argon gas) to form a film with sputtered particles on the substrate, or plasma is formed on the formed film. Since the film is formed with a compound formed by irradiation, there is no fear of deterioration with time. That is, in the case of silicon (Si) or aluminum (Al), a film is formed on the substrate with these fine particles, and this is irradiated with a reactive gas such as oxygen, nitrogen or fluorine to form a compound film. The film is not formed with a simple molecular structure. Therefore, the dielectric film layer is not changed by these gases (oxygen or nitrogen in the air) under the use environment, and the optical characteristics are not deteriorated.

  In particular, according to the present invention, a gradation layer whose thickness gradually decreases linearly is formed by sputtered particles diffusing from a mask opening having a film-forming gap between the substrate and the substrate. Decreases gradually from the edge toward the periphery. Therefore, the sputtered particles of the present invention are extremely fine compared to the vapor deposition components in the conventional vacuum vapor deposition method, and therefore, when diffusing from the mask opening to the periphery, it is attenuated in the same manner as the light diffusion, and the normal direction of the mask opening on the substrate. A film having a uniform thickness is generated, and a film (gradation film) having a thickness that gradually attenuates in proportion to the diffusion angle is formed around the film.

  Furthermore, by forming this gradation film with sputtered particles that diffuse before and after the rotation direction of the mask opening, a stable film thickness that does not vary when a film is formed by mounting a plurality of substrates around the rotating drum. Attenuation is obtained.

  The present invention will be described in detail below based on the preferred embodiments shown in the drawings. 3 and 4 are model diagrams showing a conceptual configuration of a film forming method according to the present invention. FIG. 3 is a conceptual diagram for causing vapor deposition components to fly from the target. FIG. 4 is a diagram illustrating a substrate mounted on a rotating drum and a target. The arrangement relationship is shown.

  The film forming method of the neutral density filter according to the present invention will be described. The neutral density filter (ND filter) 43 of the present invention forms a light-absorbing thin film layer 20 on a substrate (deposition base material) 10 as shown in FIG. The thin film layer 20 is formed into a single-concentration film layer 20a having a uniform thickness and uniform translucency, and a gradation film layer 20b having a gradually decreasing film thickness. The one shown in the figure is formed in a laminated form from a light absorption layer 21 of a metal film rich in light absorption and an intermediate layer (dielectric film layer; hereinafter the same) 22 for adjusting the light reflection characteristics. The light absorption layer (metal film; the same applies hereinafter) 21 and the intermediate layer 22 are formed in a plurality of layers in the form of a laminate. A coating layer 23 is formed on the uppermost layer. These film forming materials will be described later.

The present invention is characterized in that the neutral density filter 43 formed as described above is formed as follows.
(1) The light absorption layer 21 and the intermediate layer 22 are formed by reactive sputtering. As shown in FIG. 3A, a substrate 10 (deposition base material; the same applies hereinafter) is mounted on a stage 31 in a chamber 30, and a target 32 is disposed so as to face the substrate 10. The stage 31 is constituted by a cylindrical rotary drum so as to rotate relative to the target 32. A target 32 is placed on the cathode electrode, and a voltage is applied to the stage 31. This voltage is supplied from, for example, a high frequency power source. Therefore, an operating gas (eg, argon gas) is introduced into the chamber 30 that is substantially in a vacuum state. Then, the working gas becomes a plasma state in the chamber, and the ions move at high speed and collide with the target 32. As a result, particles fly from the target 32 (sputtering phenomenon) and adhere to the substrate 10.

  (2) In the present invention, the light absorption layer 21 is composed of a target made of a metal material rich in light absorption, and the intermediate layer 22 is composed of a dielectric material sputtered with a target such as Si or Al. The intermediate layer 22 is formed by sputtering this dielectric substance with an operating gas and forming a film with sputtered particles on the substrate, or forming a film with a compound generated by irradiating the formed film with plasma. That is, a film is formed on the substrate with particles such as Si and Al, and then a reactive gas such as oxygen gas, nitrogen gas, and fluorine gas is irradiated. As a result, an oxide film, a nitride film, and a fluoride film are generated.

  (3) Accordingly, in the present invention, when the substrate 10 is mounted on a rotating drum (stage; hereinafter the same) 31 in the chamber 30 and the target 32 is mounted on a cathode electrode, the target 32 is planarly deposited with a plate-like material. It is characterized in that it is configured as a source and this plate-like material is arranged substantially parallel to the surface of the substrate 10. As shown in FIG. 3A, the substrate 10 mounted on the periphery of the rotary drum (stage) 31 and the target 32 are arranged in parallel with a distance L (flight distance) from this substrate. Thereby, the planar vapor deposition source and the substrate 10 are maintained in a uniform distance relationship in the XX direction of FIG.

  Next, the present invention is characterized in that a mask plate 34 having a mask opening 33 is disposed between the target 32 and the substrate 10. The mask plate 34 is preferably attached to the rotating drum 31 as a set with the substrate 10. A predetermined film formation gap d is formed between the mask plate 34 and the substrate 10. The setting of the film forming gap d will be described later.

  In particular, at least one of the front edge 33a and the rear edge 33b of the mask opening 33 perpendicular to the rotation direction of the rotating drum 31 (YY shown in FIG. 3B) is at least one of the substrate 10 and the mask plate 34 is Y-. Arranged so as to be orthogonal to the Y direction. The illustrated upper edge 33 a and lower edge 33 b are formed in parallel with each other, and the mask plate 34 is mounted on the rotating drum 31 so that the upper and lower edges 33 a, 33 b are orthogonal to the rotating direction of the rotating drum 31.

  With such a configuration, the rotating drum 31 is rotated at a predetermined speed, a high frequency voltage is applied between the substrate 10 and the target 32, and simultaneously, an operating gas is introduced into the chamber. As a result, a film is formed on the substrate. As shown in FIGS. 3A and 3B, the film formation at this time is sputtered in the film formation gap d on the upper edge 33a and the lower edge 33b of the mask opening 33 in the rotation axis direction YY of the rotary drum 31. A gradation film layer 20b is generated by the diffusion of particles. A uniform film layer 20a is generated at the center of the opening. When this film formation state is described with reference to FIG. 5A, diffusion of sputtered particles occurs from the periphery (left and right edges and upper and lower edges) of the mask opening 33 toward the outer periphery. It is known that the diffusion of sputtered particles causes a diffusion phenomenon similar to that of light in atomic or molecular fine particles. It has been investigated that this diffusion attenuates in proportion to the diffusion angle.

  Accordingly, the film thickness formed on the outer peripheral portion of the mask opening 33 generated on the substrate 10 is similar to the cosine curve shown in FIG. 5B, and the film along the linear component indicated by Lx in FIG. A thickness is generated. The present invention is characterized in that such film formation is formed in the XX direction of FIG. 4A orthogonal to the rotation direction of the substrate 10 rotating with respect to the target 32. Accordingly, it is possible to form the gradation film layer 20b whose film thickness is linearly attenuated without being affected by the rotation of the rotary drum 31.

  The configuration of the mask plate 34 will be described. The substrate 10 is mounted on the rotary drum 31 as shown in FIG. Although the specific configuration is not shown, it is attached to the rotating drum 31 via a mounting jig. At this time, a frame-like spacer member 34S is provided between the substrate 10 and the mask plate 34 is attached to the spacer member 34S. The mask plate 34 is provided with a mask opening 33 corresponding to the film formation area, and at least one of the front end edge 33a and the rear end edge 33b of the opening 33 is orthogonal to the rotation direction of the rotary drum 31 (X-X direction in the drawing). It attaches to the rotating drum 31 so that it may be provided with the line segment to perform. A film formation gap d is formed between the spacer member 34S and the substrate 10. In this case, the film formation gap d (interval between the substrate and the mask plate) is obtained by the following equation for a desired (design value) film formation width ΔX. [D = k × ΔX / tan θ], the correction value k and the diffusion angle θ are obtained as experimental values from the atmosphere in the chamber.

  As shown by the solid line in FIG. 5B, the gradation layer formed as described above has a film thickness gradient approximately approximate to the ideal concentration gradient (broken line in the figure). On the other hand, in the film forming method by vacuum vapor deposition described in Patent Document 2 described above, the film thickness has poor linearity as indicated by a chain line in FIG. As is clear from this, in the film forming method of the present invention, the film thickness gradually decreases linearly, and the concentration gradient and light transmittance are also linearly attenuated.

Specific embodiments of the film forming method of the present invention described above will be described.
[Substrate material]
The above-described substrate 10 is made of transparent glass or a synthetic resin plate. In the case of a synthetic resin, for example, polyethylene phthalate (PET), polyethylene naphthalate (PEN), norbornene resin or the like is used. As the other substrate material, a suitable material is selected according to the use environment.
[Dielectric material]
The aforementioned dielectric film layer (intermediate layer) is made of oxide, nitride, or fluoride such as silicon or aluminum. For this reason, the deposition target 32 uses a plate-like member made of Si (silicon) or Al (aluminum).
[Metal substance]
For the metal film (light absorption layer), a metal oxide rich in light absorption such as chromel (nickel-chromium alloy), niobium (Nb) titanium (Ti), or the like is used.
[Coating layer]
As the above-mentioned coating layer 23, a hard or water-repellent material such as magnesium fluoride is used. In this case, the target 32 is MgO (magnesium oxide).

[Filter manufacturing equipment]
The sputtering apparatus shown in FIG. 6 will be described. The apparatus shown in FIG. 6 includes an outer casing 30a that forms a chamber 30, a cylindrical rotating drum 31 that is rotatably housed in the chamber 30, and a sputter that is disposed at a distance from the rotating drum 31. It is comprised with the electrode 35. FIG.

  The inside of the chamber 30 is formed in a vacuum, and therefore a vacuum pump (not shown) is provided. The chamber 30 is divided into a plurality of areas 36 a to 36 d by a shielding plate 37. In the figure, a first area 36a for sputtering a first target 32a (hereinafter referred to as “metal target”) for forming the light absorption layer 21 and a second target 32b (hereinafter referred to as “dielectric”) for forming the intermediate layer 22 are formed. A second area 36b for sputtering a body target, a third area 36c for sputtering a third target 32c for forming the coating layer 23 (hereinafter referred to as a “coat layer target”), and a first area for irradiation with an active gas. It is divided into 4 areas 36d. A pair of sputter electrodes 35a and 35b are built in the first, second and third areas 36a to 36c, respectively.

  The pair of sputter electrodes 35a and 35b are connected to an AC power source, and are arranged so that one is a cathode and the other is an anode. Each sputter electrode 35a, 35b is connected to a power supply coil 35c so that an alternating voltage is applied. A target 32 is mounted on each of the sputter electrodes 35a and 35b in the first, second and third areas 36a to 36c. The target 32 is made of a plate material and constitutes a planar vapor deposition source. An operating gas such as argon is introduced into the first, second, and third areas 36a to 36c through a controller 38. 38 g shown is an argon gas supply cylinder. An active gas (oxygen gas, nitrogen gas, fluorine gas, etc.) is supplied to the fourth area 36d from a supply cylinder 38g via a controller 38.

A reactive gas generation chamber 39 is provided in the fourth area 36d, and is configured so that the gas from the supply cylinder 38g is turned into plasma and irradiated into the fourth area 36d. In such an apparatus configuration, the rotating drum 31 is rotated at a predetermined speed, the metal target 32a in the first area 36a is sputtered to deposit a metal film (for example, Nb) on the substrate 10, and then the derivative target in the second area 36b. A dielectric film layer (for example, Si) is deposited on the substrate 10 by sputtering 32b. Next, an active gas (eg, O ₂ ) is irradiated onto the substrate in the fourth area 36d. Then, the dielectric film layer on the substrate is oxidized to generate an oxide (eg, SiO ₂ ) film.

  Thus, after laminating | stacking the light absorption layer 21 and the intermediate | middle layer 22 in multiple layers, the coating layer target 32c of the 3rd area 36c is sputtered, and the coating layer 23 is made to adhere to the uppermost layer.

  As described above, in the present invention, when the neutral density filter (ND filter) 43 is formed, the substrate 10 and the mask plate 34 are mounted on the rotary drum 31, and the planar vapor deposition source (described above) is parallel to the substrate 10. A film component is sputtered from each target) to form a film. At this time, a film-forming gap d having a predetermined interval is formed between the mask plate 34 and the substrate 10. Accordingly, the substrate 10 corresponding to the mask opening 33 of the mask plate 34 has the single concentration film layer 20a, and the gradation film layer 20b in which the film thickness gradually decreases linearly around the upper edge 33a and the lower edge 33b of the mask opening 33. Is formed.

  As described above, the present invention is characterized in that the gradation film layer 20b is formed on the upper and lower edges of the mask opening 33 orthogonal to the rotation direction of the rotating substrate 10. Therefore, the gradation film layer 20b is formed by a geometric film formation model and is not affected by conditions such as the rotation of the substrate 10.

  Furthermore, the present invention is characterized in that the film forming pressure is adjusted by adjusting the amount of operating gas introduced by the controller 38 described above. By adjusting the film formation pressure, the film formation width (the above-mentioned ΔX) of the gradation film layer 20b can be matched at the edges of the dielectric film layer (intermediate layer) 22 and the metal film (light absorption layer) 21. Become. That is, the thickness gradient (concentration gradient) of the gradation film layer 20b is set for each film layer by adjusting the pressure of the operating gas. For example, the thickness gradient of the dielectric film layer 22 and the thickness gradient of the metal film 21 are individually set. It can be set.

"Improvement of reflectance characteristics"
In the present invention, when setting the thickness gradient of the dielectric film layer 22 and the thickness gradient of the metal film 21, respectively, at the same time, in order to suppress the change of the reflectance R% in the gradation region and prevent the ghost phenomenon, As shown in FIG. 8 (a), the AR coating process is normally performed in the visible light range 400 nm to 700 nm VS. However, as shown in the figure, since the film thickness of the gradation portion becomes thin, the thickness varies. It is easy to capture the tendency that the reflectance characteristic tends to shift from d1 to d2 due to the change in film thickness, and therefore the AR coating treatment range is from 400 nm to 700 nm in the visible light region as shown in FIG. 8B. By adjusting the thickness gradient of the dielectric film layer 22 and the thickness gradient of the metal film 21 and increasing the number of layers so as to suppress the change in the reflectance R% to a higher wavelength of about 1200 nm, VS It can be a range of AR coating process to a wide band as shown. Even if the film thickness of the gradation portion is slightly changed by this broadband AR coating process and the reflectance characteristic is shifted from d3 to d4 to the lower wavelength side, the AR coating characteristic in the visible light range 400 nm to 700 nm VS is almost constant. Can be maintained.

"Explanation of light intensity adjustment device"
As shown in FIG. 7, the light amount adjusting device E according to the present invention arranges one or a plurality of light amount adjusting blades 42 in an openable and closable manner in a substrate 40 and an optical path opening 41 formed in the substrate 40. The amount of light passing through the optical path opening 41 is adjusted by the light amount adjusting blade 42. The illustrated one is configured to adjust the amount of light with a pair of blades 42a and 42b, and each blade is formed with constrictions 42x and 42y so as to adjust the amount of light in a small aperture state. Therefore, the ND filter 43 is attached to the narrowed portion 42x of the one blade 42a. The ND filter 43 is formed by cutting the single concentration film layer 20a and the gradation film layer 20b formed on the substrate 10 described above. The light amount adjustment blade 42a is attached so that the light transmittance increases toward the center of the optical path.

It is a model figure of the film-forming method of the conventional neutral density filter, (a) is explanatory drawing of an apparatus structure, (b) is explanatory drawing of the arrangement configuration of a board | substrate and a mask board. It is a model figure of the film-forming method of the conventional neutral density filter shown in FIG. 1, (a) is a film-forming model of a gradation film layer, (b) is expansion explanatory drawing of the state formed into the film | membrane on the board | substrate. BRIEF DESCRIPTION OF THE DRAWINGS It is a conceptual explanatory drawing of the film-forming method concerning this invention, (a) is a model figure which makes a vapor deposition component fly from a target, (b) is a principal part enlarged view. The arrangement | positioning relationship between the board | substrate with which the rotating drum was mounted | worn, and a target is shown, (a) is a whole perspective view, (b) is sectional drawing. (A) It is shape explanatory drawing of the neutral density filter concerning this invention, (b) is a related figure of the density | concentration of a neutral density filter, and the film-forming position, (c) is the film thickness and diffusion distance of a neutral density filter. The schematic diagram which shows the relationship. Sectional drawing of the sputtering device concerning this invention. The perspective view which shows arrangement | positioning of a light quantity adjustment apparatus. (A) (b) The characteristic view for demonstrating AR coating characteristic.

Explanation of symbols

E Light quantity adjustment device F Neutral density filter (ND filter)
d Deposition gap 10 Substrate (deposition base material)
11 Gas pressure adjusting hole 20 Thin film layer 20a Single concentration film layer 20b Gradation film layer 21 Light absorption layer (metal film)
22 Intermediate layer (dielectric film layer)
23 coating layer 30 chamber 30a outer casing 31 stage (rotating drum)
32 target 32a first target (metal target)
32b Second target (derivative target)
32c Third target (coat layer target)
33 Mask opening 33a Upper edge 33b Lower edge 34 Mask plate 34S Spacer member 35 Sputter electrode (35a, 35b)
35c Power supply coil 36a 1st area 36b 2nd area 36c 3rd area 36d 4th area 37 Shielding plate 38 Controller 38g Supply cylinder 39 Reactive gas generation chamber 40 Substrate 41 Optical path opening 42 Light quantity adjustment blade (42a, 42b)
42x Constriction part 42y Constriction part 43 ND filter

Claims (9)

A target is sputtered with a working gas in a deposition chamber, and a plurality of targets made of at least first and second materials having different optical characteristics are sputtered with a working gas on a substrate to laminate a dielectric film layer and a metal film layer. A method of forming a neutral density filter,
The dielectric film layer is
A target is sputtered with an operating gas to form a film with sputtered particles on the substrate, and then the film is formed with a compound generated by irradiating a reactive gas to the film.
The metal film layer is
A target made of a metal material is sputtered with an operating gas, and a film is formed on the substrate with sputtered particles or a compound of sputtered particles and reactive gas,
Film formation of the dielectric film layer and the metal film layer is as follows:
(1) The substrate is mounted on a cylindrical rotating drum disposed in the film forming chamber,
(2) The target is arranged with a plate-like material substantially parallel to the substrate surface,
(3) A mask plate having a mask opening is arranged on the rotating drum so as to form a predetermined film-forming gap between the substrate and the substrate.
A film is formed by applying a sputtering voltage to the target while rotating the rotating drum,
A gradation layer is formed on the substrate at the front edge and the rear edge in the rotation direction of the rotating drum, and the film thickness gradually decreases due to the diffusion of sputtered particles generated in the film forming gap from the mask opening of the mask plate. A film forming method for a neutral density filter. The substrate and the mask plate are arranged on the circumference of the rotating drum,
The film forming gap is formed by a spacer member disposed between the substrate and the mask plate,
2. The neutral density filter according to claim 1, wherein at least one of front and rear edges of the mask opening formed in the mask plate is arranged on a straight line orthogonal to a rotation direction of the rotary drum. Membrane method. 3. The neutral density filter according to claim 1, wherein the film formation cap between the substrate and the mask plate is formed at a predetermined interval set in accordance with a film formation width of the gradation layer. The film forming method. The film formation gap between the substrate and the mask plate is formed at a predetermined interval with respect to the distance between the target and the substrate. A film forming method for the dark filter as described. The substrate is made of polyethylene phthalate (PET), polyethylene naphthalate (PEN), norbornene resin or other transparent plastics or transparent glass,
This substrate is provided with a notch opening at the edge that forms the gradation film layer in the film formation area,
5. The neutral density filter film forming method according to claim 1, wherein the notch opening constitutes a through hole for adjusting diffusion of sputtered particles. A substrate,
It is composed of a dielectric film layer and a metal film layer formed in a laminated form on the substrate,
The dielectric film layer is formed by sputtering a target made of a dielectric substance with a working gas to form a film, and then irradiating with a reactive gas.
The metal film layer is formed by sputtering a target made of a metal material with an operating gas,
The dielectric film layer layer and the metal film layer are:
When the target is sputtered, it has a gradation layer in which the film thickness gradually decreases due to diffusion of sputtered particles from the mask opening edge of the mask plate that forms a film forming gap with the substrate. A neutral density filter. A diaphragm blade that is arranged in the imaging optical path and adjusts the imaging light amount;
A neutral density filter attached to the diaphragm blades,
An imaging light quantity diaphragm device, wherein the neutral density filter has the configuration according to claim 6. An apparatus for manufacturing a neutral density filter for forming a dielectric film layer and a metal film layer on a substrate in a laminated form,
A deposition chamber;
A cylindrical rotating drum disposed in the film forming chamber;
A plurality of substrates mounted on the rotating drum;
A first target made of a dielectric material disposed at a distance from the substrate in a first area divided in the film forming chamber;
A plasma (reactive gas) supply source disposed in a second area in the film formation chamber;
A second target made of a metallic material disposed in a third area in the film forming chamber;
A working gas supply source for sputtering disposed in the first area and the third area;
With
The first and second targets are plate-like materials and are disposed in the film formation chamber approximately parallel to the substrate surface,
A mask plate having a mask opening is disposed on the rotating drum so as to form a predetermined film forming gap with the substrate.
A film is formed by applying a sputtering voltage to the target while rotating the rotating drum,
The film forming apparatus forms a gradation layer whose thickness is gradually reduced by diffusion of sputtered particles generated in the film forming gap. The mask plate is arranged so that front and rear edges of the mask opening are orthogonal to the rotation direction of the rotating drum,
9. The neutral density filter manufacturing apparatus according to claim 8, wherein gradation layers are formed on the substrate at front and rear edges in the rotation direction of the rotating drum.

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