JP5442375B2 - Optical element manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing an optical element in which a coating layer is formed on a substrate, and more particularly, to a method for manufacturing a small optical element such as a small mirror, prism, or infrared cut filter used in an optical apparatus.

  Conventionally, an optical element in which a coating layer is formed on a substrate has been widely used in various optical apparatuses or optical devices. Typical optical elements include an infrared cut filter used for a CCD image sensor, a small mirror used for an optical reading device, or a prism used for an image display device.

  In such an optical element, a coating layer is formed by vacuum deposition, sputtering, or the like. For example, a mirror manufactured using vacuum deposition is disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2003-114313). The mirror described in Patent Document 1 has a configuration in which a silver reflective layer is formed on the surface of a substrate made of a glass plate or the like. Further, since silver easily reacts with corrosive gases such as sulfurous acid gas in the atmosphere to blacken (corrode), a protective layer is provided on the surface of the reflective layer to prevent corrosion.

  In recent years, there has been an increasing demand for small mirrors having a side length of about 1 to 20 mm as mirrors installed in optical devices used in optical reading devices, projectors, projection televisions, and the like. The small mirror is mounted on, for example, an optical MEMS (Micro-Electro-Mechanical-Systems) device. In the optical MEMS device, a movable plate having a mirror surface is rotated around an axis by electromagnetic driving or electrostatic driving so that light incident on the mirror surface is changed in a desired direction. The mirror surface is formed by attaching a small mirror having a reflective layer formed on a substrate to one surface of the movable plate.

  Thus, not only the small mirror described above, but also the optical element is being miniaturized. When a small optical element is manufactured, a coating layer is formed on a large parent substrate, and then the parent substrate is diced so as to have a specified dimension. 12A and 12B are views showing a conventional small mirror as an example, in which FIG. 12A is a plan view seen from the reflecting surface side, and FIG. 12B is a side sectional view. The small mirror 101 has a configuration in which a coating layer 105 including a reflective layer 106 and a protective layer 107 is formed on the flat surface 103 of the base material 102 in this order from the base material 102 side.

JP 2003-114313 A

However, in the conventional optical element, since the parent base material is diced after forming the coating layer, there is a problem that chipping occurs at the cut and fine film peeling occurs. In particular, when the coating layer contains a metallic material such as silver like a small mirror, water, oxygen, or corrosive gas enters from this film peeling, and the coating layer corrodes starting from the film peeling. There was a case.
Therefore, an object of the present invention is to provide a method for manufacturing an optical element that can prevent the coating layer from being peeled off by dicing.

  In order to solve the above-described problems, the present invention provides a method for producing an optical element in which a coating layer is formed on a substrate, a dicing sheet is attached to the back surface of the parent substrate, and the surface side of the parent substrate is diced. A dicing step for dividing the substrate into a plurality of base materials, and a film forming step for forming the coating layer on the surfaces of the plurality of base materials adhered to the dicing sheet after performing the dicing step, A pickup step of removing the plurality of base materials on which the coating layer has been formed from the dicing sheet.

According to the manufacturing method of the present invention, since the coating layer is formed after the parent substrate is diced, it is possible to prevent the peripheral portion of the coating layer from being peeled off by the dicing blade or the film peeling from being caused by chipping. .
In addition, since the coating layer is formed on the surface of the substrate while the plurality of substrates are adhered to the dicing sheet, the plurality of substrates can be formed at a time.
In addition, an optical element refers to a wavelength selection filter layer typified by an infrared cut layer, a reflective layer (including a highly reflective film), an antireflection layer, or the like on a substrate such as a flat plate, a prism, or a lens. A coating layer is formed.

  Furthermore, a plurality of substrates adhered to the dicing sheet has a minute gap in the dicing line, and the film forming material enters from the gap in the coating layer forming process, so that the coating layer is at least part of the chipping surface. It extends from the flat surface of the base material to the chipping surface side so as to cover. As a result, the optical element can be made to have a structure that does not easily peel off, and water, oxygen, corrosive gas, and the like can be prevented from entering the film. Therefore, it becomes possible to manufacture an optical element having high corrosion resistance.

This is apparent from the result of the reliability test conducted by the present inventors, but can be considered as follows.
The chipping surface is a surface exposed by dicing a part of the base material, and most of the chipping surface is a cleavage plane. The cleavage plane is mainly formed at the grain boundary, and has higher adhesion to the coating layer than the flat surface of the substrate created by cutting or polishing. Therefore, it is considered that the chipping surface has higher adhesion than the flat surface of the substrate.
In the optical element manufactured according to the present invention, since the coating layer covers at least a part of the chipping surface by the above configuration, the end of the coating layer is positioned on the chipping surface with high adhesion, and the coating layer is A structure in which film peeling is difficult can be achieved.

Further, it is preferable that the optical element is a small mirror, and in the film forming step, a metallic reflective film and a corrosion-resistant protective layer are sequentially formed as the coating layer.
This prevents oxygen, water, or corrosive gas from entering between the base material and the coating layer and corroding the metallic reflective film, making it possible to manufacture small mirrors with high corrosion resistance. It becomes.

In the film forming step, it is preferable to form the coating layer on the base material by vacuum deposition while maintaining the temperature of the base material below the heat resistance temperature of the dicing sheet.
This is because the coating layer is formed by vacuum deposition in the film forming step, so that the degree of freedom in selecting the coating material is widened and the accuracy of thin film formation can be increased.
Furthermore, since the temperature of the substrate is maintained below the heat resistance temperature of the dicing sheet during vacuum deposition, the dicing sheet is deformed by heat, or the adhesiveness of the adhesive coated on the dicing sheet is reduced, Or it can prevent that an adhesive changes.
Vacuum deposition includes ion plating.

Further, in the film forming step, a boat in which a plurality of the substrates adhered to the dicing sheet are disposed in a chamber maintained in a vacuum, and the evaporation materials of the plurality of the substrates and the coating layer are accommodated. It is preferable to deposit the coating layer while supplying a high-frequency power between them and applying a DC voltage.
The evaporated particles evaporated from the evaporation material are ionized in the vicinity of the substrate because high-frequency power is supplied between the substrate and the boat. The evaporated particles including the ionized particles are attracted to and adhered to the substrate surface by a DC voltage applied between the substrate and the boat.
On the other hand, the dissociated electrons are attracted to the evaporation source side opposite to the base material and collide with the evaporation material on the boat so that the evaporation material can be evaporated at a low temperature. Therefore, it becomes easy to maintain the substrate temperature below the heat resistance temperature of the dicing sheet.

Further, in the dicing step, the parent base material may be diced with a laser beam, and this makes it possible to cut a base material that is difficult to cut by blade dicing. Furthermore, high-speed dicing is possible.
In particular, when a reflective layer is included in the coating layer like a mirror, conventionally, laser light could not be used to cut the parent substrate on which the coating layer was formed, but in the present invention, before the coating layer is formed, Since dicing is performed, dicing using laser light becomes possible.

Furthermore, before the said film-forming process, it is good to provide the washing | cleaning process of wash | cleaning the said base material in the state in which the said several base material was affixed on the said dicing sheet.
The cleaning process is performed mainly for the purpose of removing scattered matter generated by dicing. Conventionally, since the substrate on which the coating layer is formed is cleaned, a cleaning method is selected so that the coating layer does not peel off. It was necessary and advanced technology was required for cleaning.
In the present invention, since the diced substrate is washed before the film forming step, the washing can be easily performed. Further, ultrasonic cleaning or the like that could not be used conventionally can be used, and the degree of freedom of the cleaning method is expanded.

According to the manufacturing method of the present invention, since the coating layer is formed after the parent substrate is diced, it is possible to prevent the peripheral portion of the coating layer from being peeled off by the dicing blade or the film peeling from being caused by chipping. .
In addition, since the coating layer is formed on the surface of the substrate while the plurality of substrates are adhered to the dicing sheet, the plurality of substrates can be formed at a time.
Furthermore, in the optical element manufactured by the manufacturing method of the present invention, since the coating layer covers at least a part of the chipping surface, the end of the coating layer is positioned on the chipping surface with high adhesion, A structure in which the layer is hardly peeled off can be obtained.
Therefore, it becomes possible to manufacture a highly durable optical element.

It is a figure explaining the manufacturing method of this embodiment. It is a figure which shows the parent base material which carried out dicing, (a) is the top view which looked at the parent base material from the reflective surface side, (b) is a sectional side view of a parent base material, (c) is an actual parent base material It is the photograph taken from the reflective surface side. It is a block diagram of a vacuum evaporation system. It is a block diagram of an ion plating apparatus. It is a figure which shows the small mirror manufactured with the manufacturing method of this embodiment, (a) is the top view seen from the reflective surface side, (b) is a sectional side view. It is a table | surface which shows the heat resistance characteristic of resin material. It is a schematic diagram which shows the structural example of a coating layer. It is a graph which shows the temperature change of the base material in the film-forming process. It is the photograph which image | photographed the coating layer of the small mirror manufactured by the method of the Example. It is a table | surface which shows the result of the reliability test of a small mirror. It is the photograph which image | photographed the small mirror after a reliability test, (a) shows the state which the coating layer discolored and corroded, (b) shows the state which the coating layer corroded and the film | membrane floated. It is a figure which shows the conventional small mirror, (a) is the top view seen from the reflective surface side, (b) is a sectional side view.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the shape of the component described in this example is not intended to limit the scope of the present invention, but is merely an illustrative example.
The optical element manufactured in the embodiment of the present invention has a wavelength selective filter layer represented by an infrared cut layer, a reflective layer (including a highly reflective film) on a substrate such as a flat plate, a prism, or a lens, Or the thing in which coating layers, such as an antireflection layer, were formed into a film. For example, what is used for optical devices and optical apparatuses, such as a small mirror, an infrared cut filter, and a prism, is mentioned.

A method for manufacturing an optical element in the embodiment of the present invention will be described below.
A large-sized parent substrate 1 as shown in FIG. 1 (a) is prepared, a dicing sheet 2 is adhered to the back surface 1b of the parent substrate 1 as shown in (b), and the parent substrate 1 as shown in (c). A dicing step of dicing the surface side of the substrate 1 and dividing it into a plurality of substrates 11;
As shown in FIGS. 1D and 1E, a film forming step of forming a coating layer 15 on the surfaces of a plurality of base materials 11 while being adhered to the dicing sheet 2,
As shown in FIG. 1 (f), a pick-up step of removing the plurality of base materials 11 on which the coating layer 15 is formed from the dicing sheet 2 is provided.

The specific procedure of each process is shown below.
The substrate 1 shown in FIG. 1A has a flat surface 1a. When manufacturing a flat element such as a small mirror or an infrared cut filter, the parent base material 1 is a large flat base material 1. When manufacturing a columnar element such as a prism, a long columnar parent substrate 1 is used.

In the dicing step, first, a dicing sheet 2 is attached to the back surface 1b of the parent substrate 1 as shown in FIG. The dicing sheet 2 has an adhesive surface formed on one surface of the resin sheet. The pressure-sensitive adhesive coated on the pressure-sensitive adhesive surface is preferably a resin whose physical properties are changed by ultraviolet rays or heat. For example, a resin in which the pressure-sensitive adhesive is cured by irradiating with ultraviolet rays and the adhesive strength is reduced, or a resin in which foaming is caused by application of heat and the adhesive strength is reduced. When a resin whose physical properties change due to heat is used, a resin whose physical properties change at a temperature higher than the vapor deposition temperature is selected.
Subsequently, as shown in FIG.1 (c), the surface side of the base material 1 is diced with a dicer. The dicing may be blade dicing using a dicing blade or laser dicing using laser light. For laser dicing, either ablation processing or stealth dicing can be used.

  2A and 2B are diagrams showing a parent substrate diced by a dicing blade, wherein FIG. 2A is a plan view of the parent substrate viewed from the reflective surface side, FIG. 2B is a side sectional view of the parent substrate, and FIG. Is a photograph of an actual parent substrate taken from the reflective surface side. As shown to Fig.2 (a), the base material 11 fragmented by the dicing is in the state where it arranged in multiple numbers on the dicing sheet 2, and was affixed. As shown in FIGS. 2B and 2C, a chipping surface 13 is generated on the peripheral edge 12 of the base material 11 by dicing. In the photograph of FIG. 2C, the gap width (horizontal) H of the cut line 5 by dicing is about 170 μm. The reason why the vertical and horizontal gap widths are different on the photograph is that the substrate 11 is stressed.

  In the film forming step, as shown in FIG. 1 (d), the coating layer 15 is formed on the plurality of base materials 11 while being adhered to the dicing sheet 2. As a film forming method, vacuum deposition, sputtering, or the like is used. Preferably, the film is formed using vacuum deposition. Note that vacuum deposition includes ion plating. By forming the coating layer 15 using vacuum vapor deposition, the degree of freedom of material selection is widened, the accuracy of thin film formation can be increased, and a high-quality optical element can be provided.

For vacuum deposition, for example, an electron beam vacuum deposition apparatus 50 shown in FIG. 3 is used.
In the chamber 51 maintained in a vacuum, the parent substrate 11 attached to the dicing sheet 2 is disposed. In the chamber 51, a crucible 53 that houses an evaporation material 52 that is a material of the reflective layer 16 is installed.
Then, in a state where the substrate 11 is heated by the heater 55, the evaporation material 52 is irradiated with an electron beam by the electron gun 54 and evaporated. The evaporation material 52 is vapor-deposited on the surface 11 a of the base material 11, and there is a gap at the cut 5 between the base material 11 and the base material 11 attached to the dicing sheet 2. It vapor-deposits so that at least one part of 13 may be covered. In this way, the evaporation material is deposited on the substrate 11 to form the reflective layer 16. During vapor deposition, the electron gun 54 is controlled so that the temperature of the parent substrate 1 is lower than the heat resistance temperature of the dicing sheet.
After forming the reflective layer 16, the crucible 53 containing the evaporation material 52, which is the material of the reflective layer 16, is replaced with the crucible 53 containing the evaporation material 52, which is the material of the protective layer 17. The protective layer 17 is formed by vacuum evaporation.

  In addition, although the case where the electron beam vacuum deposition apparatus 50 was used was demonstrated here, it is not limited to this, You may use other vacuum deposition apparatuses, such as a resistance heating apparatus and an ion plating apparatus. The resistance heating device is a device that heats and evaporates an evaporation source by resistance heating and adheres it to the surface of a substrate in a vacuum.

  An ion plating apparatus is an apparatus for partially evaporating atoms evaporated from a heated evaporation source with a glow discharge or plasma from a high-frequency antenna under reduced pressure, and depositing an evaporation material on a substrate to which a negative bias voltage is applied. is there. In particular, in the manufacturing method of this embodiment, it is preferable to form a film using the ion plating apparatus 60 shown in FIG. In the ion plating apparatus 60, a plurality of base materials 11 adhered to the dicing sheet 2 are arranged in a chamber 71 maintained in a vacuum, and high frequency power is supplied to the plurality of base materials 11. The coating layer 15 is vapor-deposited while applying a DC voltage between the boat 61 containing the evaporation material 69 of the coating layer 15.

The evaporated particles evaporated from the evaporation material 69 are ionized in the vicinity of the base material 11 because the high-frequency power is supplied to the base material 11. The evaporated particles including the ionized particles are attracted and attached to the surface of the base material 11 by the DC voltage applied between the base material 11 and the boat 61.
On the other hand, the dissociated electrons are attracted to the evaporation source 69 side opposite to the base material 11 and concentrate and collide with the evaporation material 69 on the boat 61, so that the evaporation material 69 can be evaporated at a low temperature. Become. Therefore, it becomes easy to maintain the substrate temperature below the heat resistance temperature of the dicing sheet 2.
A detailed configuration of the ion plating apparatus 60 and a specific film forming method using the same will be described later.

Thus, when forming the coating layer 3 by vacuum deposition, it is preferable to form the coating layer 15 while maintaining the temperature of the base material 11 below the heat resistance temperature of the dicing sheet 2.
Thereby, at the time of vacuum deposition, it can prevent that the dicing sheet 2 deform | transforms with a heat | fever, and the base material 11 peels from the dicing sheet 2 or inclines, and film-forming precision falls. In addition, the pressure-sensitive adhesive coated on the dicing sheet 2 may be reduced in adhesiveness, deteriorated or denatured by heat at or above the heat-resistant temperature. There is a possibility that the dicing sheet 2 is peeled off or tilted at a temperature higher than the heat-resistant temperature, or in the case of an ultraviolet detachable resin, it cannot be removed even when irradiated with ultraviolet rays. Therefore, when the base material 3 is set to a temperature lower than the heat resistance temperature of the dicing sheet 2, film formation can be performed without causing these problems. In general, many resin sheets used for the dicing sheet 2 have a heat resistance of about 75 ° C. (see FIG. 6). Therefore, it is preferable to maintain the temperature of the base material 11 at less than 75 ° C, preferably less than 70 ° C.

In the film forming step, the coating layer 15 may have a multilayer structure as shown in FIG. In this case, film formation is performed layer by layer in order from the substrate 11 side.
When manufacturing a small mirror, at least a metallic reflective layer 16 and a protective layer 17 having corrosion resistance are sequentially formed on the substrate 11. A detailed description of the coating layer 15 when manufacturing a small mirror will be described later.

In the pickup process, as shown in FIG. 1 (f), the substrate 11 on which the coating layer 15 is formed is picked up from the dicing sheet 2 by a suction collet or the like. In the case of the dicing sheet 2 coated with the ultraviolet peelable adhesive, the coating layer 15 was formed by irradiating the dicing sheet 2 with ultraviolet rays to change the physical properties of the ultraviolet peelable adhesive to reduce the adhesive strength. The substrate 11 is picked up.
As a result, as shown in FIGS. 5A and 5B, the entire surface 11 a of the base material 11 is covered, and at least a part of the chipping surface 13 is extended from the surface 11 a of the base material 11. The small mirror 10 with the coating layer 15 formed can be manufactured.

As described above, according to the manufacturing method described above, since the coating layer 15 is formed after the parent substrate 1 is diced, the peripheral portion of the coating layer 15 is peeled off by the dicing blade, or the film is peeled off by chipping. Can be prevented.
Moreover, since the coating layer 15 is formed on the substrate surface 11a with the plurality of substrates adhered to the dicing sheet 2, the plurality of substrates 11 can be formed at a time.
Furthermore, since the coating layer 15 covers at least a part of the chipping surface 13 in the optical element manufactured by the manufacturing method of the present invention, the end of the coating layer 15 is located on the chipping surface 13 with high adhesion. As a result, the coating layer 15 can be structured to be difficult to peel off.
Therefore, it becomes possible to manufacture a highly durable optical element.

In the manufacturing method described above, it is preferable to perform a cleaning step of cleaning the plurality of base materials 11 adhered to the dicing sheet 2 after the dicing step. In the cleaning process, the scattered matter adhering to the base material 11 is removed by dicing using pure water or the like. Ultrasonic waves can also be used for cleaning.
In this way, the substrate can be easily cleaned by cleaning the diced substrate before the film forming step. Further, ultrasonic cleaning or the like that could not be used conventionally can be used, and the degree of freedom of the cleaning method is expanded.

Here, with reference to FIG. 7, the structural example of the coating layer 15 in the case of manufacturing a small mirror is shown.
The coating layer 15 includes at least the reflective layer 16 and the protective layer 17 among the adhesion improving layer 18, the reflective layer 16, the intermediate layer 19, the protective layer 17, and the water repellent layer (not shown) in order from the substrate 11 side. It has other layers selectively.

In the small mirror shown in FIG. 7A, the coating layer 15 is formed by laminating the adhesion improving layer 18, the reflective layer 16, and the protective layer 17 in this order from the base 11 side on the flat surface 11 a of the base 11. Yes.
In the small mirror shown in FIG. 7B, the adhesion improving layer 18a, the adhesion improving layer 18b, the reflective layer 16, and the protective layer 17 are laminated on the flat surface 11a of the substrate 11 in this order from the substrate 11 side. Layer 15 is formed.
In the small mirror shown in FIG. 7C, the adhesion improving layer 18a, the adhesion improving layer 18b, the reflective layer 16, the intermediate layer 19, and the protective layer 17 are formed on the flat surface 11a of the substrate 11 in this order from the substrate 11 side. The coating layer 15 is formed by laminating.

  The material of the base material 11 is not particularly limited as long as each layer of the coating layer 15 can be formed. For example, glass, thermoplastic resin, thermosetting resin, infrared transmitting metal, aluminum, or super steel material such as carbon steel or alloy steel Can be mentioned. Examples of these alloy steels include stainless steels such as chrome steel, nickel chrome steel, nickel chrome molybdenum steel, and manganese molybdenum steel. These cast steels can also be mentioned. In order to increase the adhesion with the coating layer 15, the surface of the substrate 11 is preferably smooth. For example, a surface-polished product is suitable for a glass material. Of course, even a non-polished product can be used as long as it is a glass material having a flat surface. As the infrared transmitting metal, silicon, germanium, chalcogenite glass, and the like are preferable in terms of surface smoothness and adhesion to each layer.

  As the thermoplastic resin, an olefin resin such as a cycloolefin polymer, an acrylic resin such as polyacrylic acid ester or polymethacrylic acid ester, an ABS resin, polycarbonate or nylon, or polyphenylene sulfide can be used.

  As the thermosetting resin, phenol resin, epoxy resin, polyurethane, or the like can be used. Alternatively, the thermosetting resin includes these thermosetting resins and at least one selected from unsaturated polyester resins and curing agents that cure the resins, thermoplastic resins, inorganic fillers, and reinforcing fibers. The resin composition may be used.

The adhesion improving layer 18 mainly has a function of improving the adhesion between the surface 11a of the base material 11 and the reflective layer 16 and effectively preventing moisture from passing through the base material 11 and penetrating into the reflective layer 16. . The adhesion improving layer 18 may be formed of a metal or a dielectric material, for example, Cu, Cr, CrO, Cr ₂ O ₃ , ZrO ₂ , Y ₂ O ₃ , La ₂ Ti ₃ O ₈ , SiO _2. , TiO ₂ , Al ₂ O ₃ , and a material composed of at least one selected from the group consisting of any two or more of these. The film thickness is preferably 30 to 80 nm in consideration of adhesion. If the film thickness of the adhesion improving layer 18 is less than 30 nm, the adhesion tends to deteriorate. Further, since the adhesion improving layer 18 is desirably as thin as possible as long as the adhesion is good, the film thickness is preferably 80 nm or less. The adhesion improving layer 18 may have a multilayer structure of two or more layers.

  The reflective layer 16 is formed of a metallic material, for example, a metallic material containing silver. The silver alloy is preferably an alloy containing at least one or more selected from the group consisting of bismuth (Bi), gold, copper, palladium, or platinum. The reflective layer 16 may have a reflectance of 92% or more on the surface (reflective surface) opposite to the base 11. Preferably, when combined with a protective layer 17 composed of a multi-layered dielectric layer, which will be described later, the base material 11 has a reflectance of 97% or more when it is a glass material, and a reflectance of 96% or more when it is a resin material. Should be used. The film thickness of the reflective layer 16 is, for example, 70 to 130 nm. This is because when the thickness of the reflective layer 16 is less than 70 nm, light is easily transmitted and the reflectance is low, and when it exceeds 130 nm, the reflectance is not improved and the cost is increased. Further, the reflective layer 16 may be one having an arithmetic average roughness of the surface on the protective layer 17 side of 3 nm or less. The surface roughness of the reflective layer 16 can be measured, for example, by observation with an atomic force microscope (AFM). A surface roughness of 3 nm or less means a substantially flat surface. This suppresses light scattering on the surface of the layer, which is a major cause of a decrease in reflectance. Further, the surface of the reflective layer 16 on the protective layer 17 side preferably has a peak intensity by X-ray diffraction of 20 times or more of the total of other peak intensities. This means that the crystal orientation is high, the crystal density is high, and the film properties are homogeneous. Thereby, it is considered that high reflectance is realized by suppressing light scattering and absorption.

The protective layer 17 is formed of a corrosion-resistant material having optical transparency. The protective layer 17 is, for example, ZrO ₂ , Y ₂ O ₃ , MgF ₂ , LaTiO ₃ , La ₂ TiO ₈ , SiO ₂ , TiO ₂ , Al ₂ O ₃ , SiN, LaTixOy, or any two or more thereof. At least one material selected from the group consisting of a mixture is used. The protective layer 17 is preferably composed of two or more layers. The protective layer 17 is provided mainly for the purpose of preventing corrosion of the reflective layer 16, but the material and film thickness, and in the case of a multilayer structure of two or more layers, a combination of layers is selected, and the reflectivity is reduced. More preferably, it is configured to have an increasing action. In this case, the protective layer 17 is formed by laminating two or more dielectric layers having different refractive indexes, and constitutes a highly reflective layer (reflection increasing layer) by multilayer interference. The thickness of each of the plurality of dielectric layers is appropriately selected depending on the refractive index and the wavelength of light. The thickness per layer is preferably 10 nm or more and 20 nm or less, and more preferably 18 nm or less. Further, the protective layer 17 preferably has an arithmetic average roughness of the surface on the side not in contact with the reflective layer 16 (the reflective surface side) of 5 nm or less. Thereby, the surface of the protective layer 5 also becomes a substantially flat surface, and together with the reflective layer 16, the scattering and absorption of light are suppressed, thereby contributing to the realization of a high reflectance.

The intermediate layer 19 mainly has high adhesion to both the reflective layer 16 and the protective layer 17 and has a function of preventing moisture penetration to a higher degree. For the intermediate layer 19, for example, a material made of at least one selected from the group consisting of Y ₂ O ₃ , MgF ₂ , Al ₂ O ₃ or SiO ₂ is used. The film thickness is 20 nm or more, preferably 50 nm or more, more preferably 65 nm or more. Moreover, since the performance improvement is not recognized even if it is more than that, it is preferable that it is 100 nm or less.
The water repellent layer mainly has a function of effectively preventing moisture penetration and further improving the corrosion resistance and durability of the small mirror. The water repellent layer is preferably formed of, for example, a fluorine compound or a compound containing fluorine and silicon. The film thickness is preferably 15 to 40 nm, thereby effectively exerting the above function.

  In the film forming process, an ion plating apparatus 60 shown in FIG. 4 can also be used. Note that the interior of the chamber 71 of FIG. 4 is schematically shown by a sectional view thereof. In the following film forming method, the evaporation material 69 and, if necessary, the film forming conditions are changed so that the film can be continuously formed on the base material 11 with one apparatus 60.

First, the case where an adhesion improving layer is formed on the surface of the substrate 11 will be described.
A boat 61 is disposed in the lower part of the chamber 71 in the ion plating apparatus 60 shown in FIG. In addition, a crucible 78 is also provided that irradiates an electron beam with an electron gun 79 instead of heating with the boat 61 to evaporate the evaporation material 69. The boat 61 holding the evaporation material 69 or the crucible 78 holding the evaporation material 69 is called an evaporation source. A base material holding part 62 for holding the base material 11 is provided in the upper part of the chamber 71 so as to face the evaporation source. As the evaporation material 69 for forming the adhesion improving layer, Cu, Cr, CrO, Cr ₂ O ₃ , Y ₂ O ₃ , La ₂ Ti ₃ O ₈ , SiO ₂ , TiO ₂ , or Al ₂ O ₃ are used. Can be used. The base material holding part 62 is configured to hold a plurality of base materials 11 that are stuck to the dicing sheet 2. When the adhesion improving layer is a multilayer having different components, these metal or metal oxide layers (thin films) are sequentially formed on the substrate 11 by the method described below.

  The base material holding part 62 is made of a conductive material, and holds the base material 11 and also functions as an electrode. High frequency power from a high frequency power supply (RF) 65 is applied to the substrate holding unit 62 via a matching device (MN) 64 and a capacitor 67 as a DC shielding filter. The capacitor 67 may function as a part of the matching circuit using a variable capacitor. Furthermore, the cathode side of the direct-current voltage application power source (DC) 66 is connected to the substrate holding part 62 via a coil 68 as a high-frequency shielding filter. The terminal on the opposite side of the base material holding part 62 of the high-frequency power supply power source 65 is connected to the anode side of the DC voltage application power source 66, and these are grounded.

  The boat 61 is made of, for example, a material having high electrical resistance, and generates heat for evaporating the evaporating material 69 upon receiving power supply from a heating power source 63 including, for example, an AC power source. The boat 61 is further connected to the anode side of a DC voltage application power source 66. As another method, as described above, the evaporation material 69 can be evaporated by irradiating the evaporation material 69 accommodated and held in the crucible 78 from the electron gun 79. In FIG. 4, an arrow from the electron gun 79 to the evaporation material 69 held in the crucible 78 represents the state of electron beam irradiation.

The space in the chamber 71 is exhausted by a vacuum pump 74 through an exhaust duct 72 and an exhaust valve 73, and is brought into a predetermined vacuum state during the film formation period. In order to supply an inert gas (for example, argon gas) and a reactive gas (for example, oxygen gas) into the chamber 71, the chamber 71 is provided with a flow rate control device (MFC) 76 and a gas supply pipe 77. An inert gas supply source 81 and a reactive gas supply source 83 are connected. Supply / stop from the inert gas supply source 81 is performed by opening and closing the valve 81a. Supply / stop from the reactive gas supply source 83 is performed by opening and closing the valve 83a. The reactive gas is supplied only when forming an adhesion improvement layer of a metal oxide such as Y ₂ O ₃ , SiO ₂ , TiO ₂ , and Al ₂ O ₃ , and an adhesion improvement layer of Cu and Cr is provided. When forming, only the inert gas is supplied without supplying the reactive gas.

The degree of vacuum in the chamber 71 is measured by a vacuum gauge 75, and the flow rate control device 76 is controlled by a control device 80 comprising a microcomputer or the like based on the output of the vacuum gauge 75. Thereby, the gas supply amounts from the inert gas supply source 81 and the reactive gas supply source 83 are controlled so that the degree of vacuum in the chamber 71 is maintained at a predetermined value. In order to obtain a dense adhesion improving layer, the degree of vacuum at the time of layer formation in the chamber 71 is 1.0 × 10 ^{−3 to} 5.0 × 10 ⁻² Pa, preferably 5.0 × 10 ^−3. It is good that it is -3.0 * 10 ^<-2 > Pa. The oxygen gas concentration is adjusted within a range of about 1.0 × 10 ⁻² × 3.0 × 10 ⁻² Pa.

  In order to measure the layer formation speed on the surface of the base material 11, a film thickness monitor 84 is provided in association with the base material holding part 62. The output signal of the film thickness monitor 84 is input to the control device 80, and the control device 80 controls the output of the heating power source 63 based on the output of the film thickness monitor 84. In this way, the evaporation amount of the evaporation material 69 is controlled by controlling the amount of current supplied to the boat 61 or adjusting the current value of the electron gun 79 so that the layer formation speed becomes a desired value. Adjusted. In order to obtain a dense adhesion improving layer, the formation rate of the layer is 1 to 20 Å / second, preferably 2 to 15 Å / second. Hereinafter, taking the evaporation of the evaporation material 69 by heating the boat 61 as an example, the layer formation procedure and the state in the chamber 71 at that time will be described in more detail.

The high-frequency power supply power source 65 may be a high-frequency power source having a frequency of 10 to 50 MHz, for example, but may be set to 13.56 MHz, for example, and the output 20 to the unit area (cm ² ) of the substrate holding part 62 as a discharge electrode. A high frequency power of 200 mW, preferably 25 to 150 mW, is applied to the substrate holding part 62. The preferable output range varies depending on the type of the evaporation material 69 and the size of the base material holding portion 62, and thus is set appropriately within the above range. A high-frequency electric field corresponding to this is formed in the chamber 71, so that plasma composed of the gas supplied from the gas supply pipe 77 and the evaporated material evaporated from the evaporation material 69 is generated in the chamber 71. Among the ionized particles in the plasma, positively charged particles are attracted to the surface of the substrate 11 by the DC bias applied to the substrate holding unit 62 from the DC voltage application power source 66. The applied voltage from the DC voltage applying power source 66 is 100V to 400V, preferably 180 to 230V.

  On the other hand, the dissociated electrons in the plasma are attracted to the boat 61 connected to the anode side of the DC voltage application power source 66. At this time, since the evaporation material 69 continuously evaporates from the evaporation source, the luminous body shaped like a plasma leg descends to the evaporation source due to the collision between the evaporated particles and the electrons is brought near the evaporation source. It can be seen. Then, the electrons collected in the vicinity of the evaporation source are sucked into the boat 61 that is grounded and connected to the anode side, and collides with the evaporation material 69 on the boat 61. Thus, the evaporation of the evaporation material 69 is promoted by the heating by the boat 61 and the collision of electrons. That is, an effect of promoting evaporation at a low temperature (deposition assist effect) by concentrated electron collision with the evaporation material 69 can be obtained.

  As shown in FIG. 4, the chamber 71 is not connected to any of the DC voltage application power source 66 and the high frequency power supply source 65, and is not grounded. That is, the chamber 71 is in an electrically floating state. For this reason, high frequency discharge does not occur between the substrate holder 62 and the chamber 71, and charged particles in the plasma in the chamber 71 are not attracted to the inner wall of the chamber 71. Accordingly, positively-charged particles or positively-charged particles in the plasma are efficiently guided to the surface of the substrate 11, and electrons that are negatively charged particles in the plasma are transferred to the evaporation material 69 on the boat 61. It will be guided intensively. As a result, a good thin film can be formed, and evaporation of the evaporation material 69 can be efficiently promoted by an electron beam.

  When the plasma is stabilized in the chamber 71, the evaporation material 69 evaporates so as to be sucked up by the plasma by irradiation of the electron beam from the plasma to the evaporation material 69. Therefore, in order to keep the deposition speed of the evaporation material 69 that adheres to the base material 11, the control device 80 reduces the output of the heating power source 63 based on the output of the film thickness monitor 84. That is, the energization current or energization voltage to the boat 61 is lowered. Thereby, the evaporation rate is adjusted.

Since the evaporation of the evaporation material 69 is promoted by the electron beam supplied from the plasma, the heating current value of the boat 61 can be kept low, so that the evaporation of the evaporation material 69 is continuously maintained at a relatively low heating temperature. It is possible to form a thin film by vapor deposition utilizing the action of plasma.
That is, if the evaporation rate = (evaporation rate by heating) + (evaporation rate by the deposition assist effect) is maintained and the deposition assist effect is increased, the radiant heat from the evaporation source can be suppressed and the influence on the substrate 11 is reduced. Therefore, a thin film can be formed without increasing the temperature of the substrate 11, and in the case of this embodiment, the coating can be maintained while maintaining a temperature of 70 ° C. or lower. Therefore, the temperature of the base material 11 can be maintained so as to be equal to or lower than the heat resistant temperature of the dicing sheet 2 during vapor deposition.

After the formation of the adhesion improving layer, a silver alloy material is accommodated and held as the evaporation material 69 in the boat 61 or the crucible 78 of the evaporation source, and the adhesion improving layer on the substrate 11 is formed in the same manner as the formation of the adhesion improving layer. A silver alloy film is formed on the surface to obtain a reflective layer. At this time, an inert gas is supplied, but a reactive gas such as oxygen gas is not supplied. In the case of obtaining a dense silver alloy reflective layer, the degree of vacuum in the chamber 71 is 1.0 × 10 ^{−3 to} 5.0 × 10 ⁻² Pa, preferably 5.0 × 10 ^{−3 to} 3.0 ×. 10 ⁻² Pa is preferable, and the formation rate of the reflective layer is 3 to 20 ３〜 / second, preferably 5 to 15 Å.

After forming the silver alloy reflective layer, a protective layer (reflection-enhancing layer) is formed on the surface of the reflective layer in the same manner as the formation of the adhesion improving layer. As the evaporation material 69 for forming the protective layer, ZrO ₂ , Y ₂ O ₃ , MgF ₂ , LaTiO ₃ , La ₂ Ti ₃ O ₈ , SiO ₂ , TiO ₂ , Al ₂ O ₃ , SiN, LaTixOy, or these Any two or more of these can be used. When the protective layer is a multilayer having different components, a thin film of these compounds is sequentially formed on the reflective layer of the silver alloy.

  When forming the intermediate layer, the water-repellent layer, or both, if necessary, the boat 61 or the crucible 78 as the evaporation source accommodates and holds the above-described compound as the evaporation material 69 to form the adhesion improving layer. Layer formation is performed by a compliant operation. When these layers are not metal oxides, oxygen gas which is a reactive gas is not supplied.

  For supplying each of the evaporating materials 69 to the boat 61 or the crucible 78, for example, each material of the adhesion improving layer, the reflective layer, and the protective layer is supplied to the boat 61 in this order from a coating material supplier (not shown). Alternatively, evaporation may be sequentially performed under predetermined film forming conditions, and a layer may be continuously formed on the surface of the substrate 11. In addition, when forming an intermediate | middle layer, a water-repellent layer, or both, you may make it form a film | membrane continuously similarly in the formation order.

  During these film formations, the substrate 11 is held at 70 ° C. or lower. Therefore, even if it is a resinous base material, each above-mentioned layer can be favorably formed in the surface of a resinous base material, without receiving the influence of a deformation | transformation etc. of the base material by a heat | fever. Furthermore, since the dicing sheet 2 is not affected by deformation due to heat, the film can be formed satisfactorily.

A reliability test for evaluating corrosion resistance was performed using the small mirror of the present invention.
(Example)
In the dicing step, a glass polished product having a surface 1a of 76 mm × 76 mm and a thickness of 0.1 mm is used as the parent substrate 1, and a dicing sheet 2 is attached to the surface 1a of the parent substrate 1, and the parent substrate 1 is subjected to parent dicing by blade dicing. The base material 1 was diced and divided into base materials 11 having a surface 11a of 3 mm × 3 mm. The dicing sheet 2 used was a resin sheet made of polyethylene terephthalate (PET) coated with an acrylic ultraviolet peelable adhesive. The dicing sheet 2 has a heat resistant temperature of 120 ° C. for the resin sheet and a heat resistant temperature of 80 ° C. for the adhesive.
A cleaning process was performed after the dicing process. In the cleaning process, the base material 11 was cleaned with pure water while being adhered to the dicing sheet 2.

After the cleaning process, a film forming process was performed.
In the film forming step, the plurality of base materials 11 adhered to the dicing sheet 2 are formed on the base material 11 in the order of the following (1) to (4) using the ion plating apparatus 60 shown in FIG. Stacked to produce a small mirror.
(1) Adhesion improving layer 18: Two layers of chromium (Cr) (thickness 20 nm) and copper (Cu) (thickness 60 nm) were laminated in this order.
(2) Reflective layer 16: Silver-bismuth (Ag-Bi) alloy (“Ag-1.0 at% Bi alloy (bismuth: 1.9 wt%)” manufactured by Kobelco Research Institute, Inc.) (thickness 120 nm)
(3) Protective layer 17: Magnesium fluoride (MgF ₂ ) (thickness 54.1 nm), yttrium oxide (Y ₂ O ₃ ) (thickness 20 nm), MERCK Substance H5 Patinal (trademark) (LaTixOy) (thickness) 39.5 nm) was laminated on the Ag-Bi layer in this order.
(4) Water-repellent layer: WRCK Substance WR1 Pattern (trademark) (silicon fluoride compound) (thickness 20 nm) manufactured by MERCK was laminated on the LaTixOy layer.

(1) Adhesion improving layer 18
Evaporating material 69: Cr, Cu (First, a Cr film was formed by the following operation, and then a Cu film was formed on the Cr film by the same operation)
Gas introduced into chamber 71: Argon gas RF power supply power supply 65 applied to base material holding part 62: 31.6 mW / cm ² at a frequency of 13.56 MHz (applied per unit area of base material holding part 62 Power)
DC application power supply 66: The cathode side is connected to the substrate holding part 62, and the anode side is connected to the boat 61. Applied voltage from the DC application power supply 66 to the substrate holding part 62: 200V
Chamber 71: The degree of vacuum in the electrically floating chamber 71 that is not grounded: 1.5 × 10 ⁻³ Pa or less Formation speed of the adhesion improving layer: 3 Å / sec (Cr), 6 Å / sec (Cu)
Evaporation source heating: resistance heating by the heating power source 63 In this way, two adhesion improving layers 18 composed of a Cr film having a thickness of 20 nm and a Cu film having a thickness of 60 nm were formed on the substrate 11.

(2) Reflective layer 16
Evaporating material 69: Ag-Bi
Gas introduced into chamber 71: Argon gas RF power supply power supply 65 applied to base material holding part 62: 31.6 mW / cm ² at a frequency of 13.56 MHz (applied per unit area of base material holding part 62 Power)
DC application power supply 66: The cathode side is connected to the substrate holding part 62, and the anode side is connected to the boat 61. Applied voltage from the DC application power supply 66 to the substrate holding part 62: 200V
Chamber 71: Electrically floating state that is not grounded Vacuum degree in chamber 71: 1.5 × 10 ⁻³ Pa or less Formation speed of reflection layer: 10 Å / sec Heating of evaporation source: Resistive heating by heating power source 63 Thus, the reflective layer 16 made of an Ag—Bi film having a thickness of 120 nm was formed on the Cu film.

(3) Protective layer 17
Evaporation material 69: MgF ₂ , Y ₂ O ₃ , LaTixOy (formed in this order)
Gas introduced into the chamber 71: argon gas (MgF ₂ ), oxygen gas (Y ₂ O ₃ , LaTixOy)
Applied power from the high-frequency power supply source 65 to the base material holding unit 62: 52.6 at the frequency of 13.56 MHz (during MgF ₂ film formation), 100 (during Y ₂ O ₃ film formation), or 80 (LaTixOy formation) During film formation) mW / cm ² (applied power per unit area of the substrate holding part 62)
DC application power source 66: The cathode side is connected to the base material holding unit 62, and the anode side is connected to the boat 61. Applied voltage from the DC application power source 66 to the base material holding unit 62: 250V (MgF ₂ ), 400 (Y ₂ O ₃ ), 300 (LaTixOy)
Chamber 71: Degree of vacuum in electrically floating chamber 71 not grounded: 1.5 × 10 ⁻³ Pa or less Formation rate of protective layer: 8 Å / sec (MgF ₂ ), 2 Å / sec (Y ₂ O ₃ , LaTixOy)
Evaporation source heating: resistance heating or electron beam heating by a heating power source 63 In this way, a three-layer protective layer 17 composed of a film (MgF ₂ ), a film (Y ₂ O ₃ ) and a film (LaTixOy) 11 was formed.

(4) Water-repellent layer evaporating material 69: MERCK Substance WR1 Pattern (trademark)
Gas introduced into the chamber 71: Formation speed of the non-water repellent layer: 7 Å / sec Since no introduced gas is used when the water repellent layer is formed, the gas supply amount is 0 and the degree of vacuum in the chamber is 5. 0 × 10 ⁻² Pa or less.

When the film was formed under the above conditions using the apparatus shown in FIG. 4, a thermocouple was attached to the substrate 11 and the temperature change during the film formation process was measured. FIG. 8 is a graph showing the temperature change of the substrate 11. L1 is film period Cr film, L2 is deposition time of the Cu film, L3 is deposition period Ag-Bi film, film formation time of the MgF ₂ film L4, L5 film formation period of _Y 2 _{O 3,} L6 is a LaTixOy film formation period. In L1, since the evaporation material is Cr having a high melting point, the temperature rises due to radiant heat. In L2, the temperature is lowered because the radiant heat is low. After L3, the temperature is maintained or gradually rises. Is maintained at 75 ° C. or lower.

  After the film formation process, a pickup process was performed. In the pick-up process, the dicing sheet 2 was irradiated with ultraviolet rays to change the physical properties of the pressure-sensitive adhesive to facilitate peeling, and the substrate 11 on which the coating layer 15 composed of the above layers was formed was picked up by a suction collet. A photograph of the small mirror manufactured in this example is shown in FIG. As shown in the figure, it can be seen that the coating layer 15 is formed up to the chipping surface.

(Comparative example)
First, a film forming process was performed. In the film forming step, the coating layer 15 is formed by laminating the layers in the order of (1) to (4) on the parent substrate 1 in the same manner as in the embodiment, using the ion plating apparatus 60 shown in FIG. did. As the parent substrate 1, a glass polished product having a surface 1a of 76 mm × 76 mm and a thickness of 0.1 mm was used. The configuration of the coating layer 15 is the same as in the example.
A dicing process was performed after the film forming process. In the dicing process, the parent base material 1 on which the coating layer 15 was formed was taken out from the ion plating apparatus 60, and the parent base material 1 was diced with a dicing blade, and the surface 1a was divided into the base material 11 having a size of 3 mm × 3 mm.

A cleaning process was performed after the dicing process. In the cleaning step, the parent substrate 1 on which the coating layer 15 was formed was cleaned with pure water.
After the cleaning process, a pickup process was performed. In the pickup process, the dicing sheet 2 was irradiated with ultraviolet rays to peel off the adhesive, and the substrate 11 on which the coating layer 15 composed of the above layers was formed was picked up by a suction collet.

Using the reflective mirrors of Examples and Comparative Examples manufactured as described above, tests were performed under the conditions (1) to (6) while changing environmental conditions.
(1) Under high temperature and high humidity conditions, the small mirrors of Examples and Comparative Examples were placed in a space of temperature 48.9 ° C. and humidity 95% and left for 24 hours.
(2) Under high temperature and high humidity conditions, the small mirrors of the example and the comparative example were placed in a space at a temperature of 60 ° C. and a humidity of 90% and left for 100 hours.
(3) The high temperature condition was that the small mirrors of the example and the comparative example were placed in a space of 140 ° C. and left for 72 hours.
(4) For low temperature conditions, the small mirrors of the example and the comparative example were placed in a space at a temperature of −25 ° C. and left for 72 hours.
(5) The temperature cycle condition was that after the small mirrors of the example and the comparative example were placed in a space at a temperature of 60 ° C. and left for 3 hours, then cooled for 1 hour, and further placed in a space at a temperature of 25 ° C. and left for 3 hours. The 8 hour temperature cycle with 1 hour cooling was repeated 6 times.
(6) The salt water spraying condition was that water with a salt concentration of 5% was sprayed on the small mirrors of the examples and comparative examples, and then placed in a space at a temperature of 35 ° C. and left for 24 hours.

After performing the test under these conditions, the small mirror was visually observed to evaluate the state of the coating layer.
FIG. 10 is a table showing the result of the reliability test of the small mirror. In this table, A shows no change, B shows discoloration and corrosion of the film, and C shows film missing and film floating.
FIG. 11 is a photograph of a small mirror after the reliability test, where (a) shows a state where the coating layer has been discolored and corroded, and (b) shows a state where the coating layer has corroded and the film has floated.

  (1) Under high temperature and high humidity conditions, the small mirror of the example did not change, but the small mirror of the comparative example showed discoloration and corrosion of the coating layer. (2) Under high temperature and high humidity conditions, the small mirror of the example did not change, but the small mirror of the comparative example showed missing coating layer and film floating (photo of FIG. 11A). From this result, it is apparent that the small mirror of the example has extremely higher corrosion resistance than the small mirror of the comparative example under high temperature and high humidity conditions.

No change was observed in any of the small mirrors under (3) high temperature conditions, (4) low temperature conditions, and (5) temperature cycle conditions.
(6) Under the salt spray conditions, discoloration and corrosion of the coating layer were observed in the small mirror of the example, and missing and film floating were observed in the small mirror of the example. From this result, discoloration and corrosion occurred in the small mirror of the example under the salt spray condition, but the small mirror of the comparative example was missing the coating layer and the film floated under the same condition (FIG. 11 (b). Therefore, it can be seen that the small mirror of the example is superior in corrosion resistance to the small mirror of the comparative example even under salt spray conditions.
Thus, it is clear from the result of the reliability test that the small mirror of the present invention has higher corrosion resistance than the conventional small mirror.

DESCRIPTION OF SYMBOLS 1 Parent substrate 2 Dicing sheet 11 Base material 15 Coating layer 16 Reflective layer 17 Protective layer 18, 18a, 18b Adhesion improvement layer 19 Intermediate | middle layer 50 Vacuum deposition apparatus 51 Chamber 52 Evaporating material 53 Crucible 54 Electron gun 55 Heater 60 Ion Plating device 61 Boat 62 Base material holding part 65 High frequency power supply power 66 DC voltage application power supply (DC)
69 Evaporating material 71 Chamber 74 Vacuum pump 78 Crucible 79 Electron gun 80 Control device

Claims (6)

In the method of manufacturing an optical element in which a coating layer is formed on a substrate,
A dicing step of attaching a dicing sheet to the back surface of the parent substrate, dicing the surface side of the parent substrate, and dividing the substrate into a plurality of the substrates;
After performing the dicing step, a film forming step of forming the coating layer on the surfaces of the plurality of base materials adhered to the dicing sheet;
A method of manufacturing an optical element, comprising: a pickup step of removing the plurality of base materials on which the coating layers are formed from the dicing sheet. The optical element is a small mirror;
The method for manufacturing an optical element according to claim 1, wherein in the film forming step, a metallic reflective film and a corrosion-resistant protective layer are sequentially formed as the coating layer.   The said film-forming process WHEREIN: The said coating layer is formed into a film by vacuum deposition, maintaining the temperature of the said base material below the heat-resistant temperature of the said dicing sheet, The film formation process of Claim 1 or 2 characterized by the above-mentioned. A method for manufacturing an optical element.   In the film forming step, a plurality of the substrates adhered to the dicing sheet are arranged in a vacuum maintained chamber, and a plurality of the substrates and a boat storing the coating layer evaporation material are provided. 4. The method of manufacturing an optical element according to claim 1, wherein the coating layer is deposited while supplying a high-frequency power therebetween and applying a DC voltage.   5. The method of manufacturing an optical element according to claim 1, wherein in the dicing step, the parent base material is diced with a laser beam.   6. The method according to claim 1, further comprising a cleaning step of cleaning the base material in a state where a plurality of the base materials are adhered to the dicing sheet before the film forming step. The manufacturing method of the optical element of description.

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