JP5543525B2 - Optical device and manufacturing method thereof - Google Patents

Description

  The present invention relates to an optical device using at least two transparent substrates and a method for manufacturing the same.

  Many optical devices are used in which a desired characteristic is obtained by combining a plurality of optical members that transmit light. In such an optical device, a technique for bonding a plurality of optical members is important.

  As an optical device that combines a plurality of optical components, there is an etalon filter (see Patent Document 1). The etalon filter uses two flat-shaped partial transmission mirrors, and a gap adjusting member (gap member) is sandwiched between them to determine the distance between the two partial transmission mirrors so that the desired resonator characteristics can be obtained. doing. In the etalon filter having such a structure, the gap member and each partial transmission mirror are joined and assembled.

  The above-described optical component bonding includes bonding (bonding) using an organic adhesive, bonding by solder, surface activated bonding, bonding by optical contact, and the like. Surface activated bonding is a technique in which a bonding surface is cleaned using an ion gun in a high vacuum to expose the bonding hands of surface atoms and are directly bonded by overlapping. The optical contact is a technique for activating and hydrophilizing a bonding surface by irradiation with plasma or excimer laser light, and temporarily bonding by superimposing and then dehydrating and completely bonding by high-temperature treatment.

Japanese Patent Laid-Open No. 04-061181

  However, the above-described joining technique has the following problems. First, in the case of using an organic adhesive, there is a problem in reliability due to a decrease in adhesive strength due to a change over time in an environment such as high temperature and high humidity due to the characteristics of the adhesive. In addition, organic adhesives have problems such as thermal expansion and contraction of the adhesive and changes in the optical path length, resulting in unstable characteristics. In addition, it is not easy to make the thickness of the adhesive uniform among products, and there is a problem that variations in product characteristics occur. This variation in thickness is the same in joining using solder.

  On the other hand, according to the surface activated bonding and the optical contact, there is almost no decrease in the adhesive strength due to the change over time, and no adhesive is used, so that there is no problem in terms of variation. However, in surface activated bonding, a high degree of vacuum is required, and in order to bond the activated regions to each other, alignment and the like are necessary, and the manufacturing apparatus becomes expensive, leading to an increase in product cost. is there. In addition, the optical contact requires a high temperature treatment of 250 ° C. or higher, and there is a problem in that, when trying to join parts having different thermal expansion coefficients, the heat treatment peels off and a crack occurs. Further, when the surface roughness of the joint surface of the optical member becomes rough, there is a problem that the joint strength decreases in the surface activated joint and the optical contact.

  The present invention has been made to solve the above problems, and an object of the present invention is to make it possible to manufacture an optical device having a high bonding strength between optical components without causing an increase in product cost. To do.

An optical device according to the present invention includes a first metal layer formed in a bonding region of a peripheral portion excluding a central portion of a first substrate made of a transparent material containing silicon dioxide, and one surface of a second substrate. At least a second metal layer formed in contact with and integrated with the first metal layer, wherein the first metal layer and the second metal layer include a metal having a positive free energy of formation of oxide at room temperature. The first metal layer and the second metal layer are made of materials and have a thickness that is three times or more the surface roughness of the formation surface on which the first metal layer and the second metal layer are formed .

  In the optical device, the second substrate may be made of a transparent material containing silicon dioxide, and the second metal layer only needs to be formed in a bonding region in a peripheral portion excluding the central portion of the second substrate.

In the optical device, a third metal layer formed in a bonding region in a peripheral portion excluding a central portion of the third substrate made of a transparent material containing silicon dioxide, and formed on the other surface of the second substrate. At least a fourth metal layer that is in contact with and integrated with the third metal layer, and the third metal layer and the fourth metal layer are made of a metal material that includes a metal having a positive free energy of formation of oxide at room temperature. It is good also as what is done. The third metal layer and the fourth metal layer may have a thickness that is at least three times the surface roughness of the surface on which they are formed. Moreover, the metal material should just be selected from Au, Pt, and the alloy containing these metals.

In addition, the method for manufacturing an optical device according to the present invention includes a step of forming a first metal layer in a bonding region in a peripheral portion excluding a central portion of a first substrate made of a transparent material containing silicon dioxide, and a second step. Forming the second metal layer on one surface of the substrate, and bringing the first metal layer of the first substrate and the second metal layer of the second substrate into contact with each other, thereby bringing the first substrate and the second substrate into contact with each other; At least a step of joining with the metal layer and the second metal layer, wherein the first metal layer and the second metal layer are made of a metal material containing a metal having a positive free energy of formation of oxide at room temperature , The layer and the second metal layer are formed to have a thickness that is at least three times the surface roughness of the surface on which they are formed .

  In the method for manufacturing an optical device, the second substrate is made of a transparent material containing silicon dioxide, and the second metal layer may be formed in a bonding region in a peripheral portion excluding the central portion of the second substrate.

In the method of manufacturing an optical device, a step of forming a third metal layer in a bonding region in a peripheral portion excluding a central portion of the third substrate made of a transparent material containing silicon dioxide, and the other of the second substrate Forming a fourth metal layer on the surface, and bringing the third metal layer of the third substrate and the fourth metal layer of the second substrate into contact with each other, thereby bringing the third substrate and the second substrate into contact with the third metal layer and A step of joining with a fourth metal layer, and the third metal layer and the fourth metal layer may be made of a metal material containing a metal having a positive free energy of formation of oxide at room temperature.

In the method for manufacturing an optical device , the third metal layer and the fourth metal layer may be formed to have a thickness that is three times or more the surface roughness of the formation surface on which the third metal layer and the fourth metal layer are formed. Moreover, the metal material should just be selected from Au, Pt, and the alloy containing these metals.

  As described above, according to the present invention, it is possible to obtain an excellent effect that an optical device having a high bonding strength between optical components can be manufactured without causing an increase in product cost.

FIG. 1A is a configuration diagram showing a state in each step for explaining a method of manufacturing an optical device according to Embodiment 1 of the present invention. FIG. 1B is a configuration diagram showing a state in each step for explaining the method of manufacturing an optical device according to Embodiment 1 of the present invention. FIG. 1C is a configuration diagram showing a state in each step for explaining the method of manufacturing an optical device according to Embodiment 1 of the present invention. FIG. 2 is a plan view showing the configuration of the optical device according to Embodiment 1 of the present invention. FIG. 3 is a cross-sectional view showing the configuration of the optical device according to Embodiment 2 of the present invention. FIG. 4 is a characteristic diagram showing a result of measuring the tensile strength of a sample in which test pieces having respective surface roughnesses are joined to each other with the thickness of each metal layer.

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

[Embodiment 1]
First, Embodiment 1 of the present invention will be described with reference to FIGS. 1A, 1B, and 1C. 1A, 1B, and 1C are configuration diagrams showing states in respective steps for explaining a method of manufacturing an optical device according to Embodiment 1 of the present invention. 1A, 1B, and 1C schematically show cross sections.

  First, as shown in FIG. 1A, a first metal layer 102 is formed in a bonding region in a peripheral portion excluding the central portion of the first substrate 101 made of a transparent material containing silicon dioxide. The first substrate 101 is, for example, a quartz plate. The first substrate 101 may be a quartz plate, a glass plate, or the like. The first metal layer 102 is formed on the surface of the first substrate 101 by, for example, a vacuum film forming method. The first metal layer 102 is made of a metal material containing a metal having a positive free energy of formation of oxide at room temperature, such as Au, Pt, and alloys containing these metals. Further, the first metal layer 102 is formed to a thickness that is three times or more the surface roughness of the formation surface. In the Japanese Industrial Standard, “normal temperature” is set to 20 ° C. ± 15 ° C. (5-35 ° C.). The surface roughness is an arithmetic average roughness.

  Next, as shown in FIG. 1B, a second metal layer 104 is formed on one surface of the second substrate 103. The second substrate 103 is a substrate made of a transparent material containing, for example, silicon dioxide, and is a quartz plate, a quartz plate, a glass plate, or the like, for example. Further, the second metal layer 104 is formed in a bonding region in a peripheral portion except for the central portion of the second substrate 103. For example, the second metal layer 104 is formed by a vacuum film formation method. The second metal layer 104 is made of a metal material containing a metal having a positive free energy of formation of oxide at room temperature, such as Au, Pt, and alloys containing these metals. The second metal layer 104 is formed to have a thickness that is three times or more the surface roughness of the formation surface.

  Here, selective formation of each metal layer in the bonding region will be described using the first metal layer 102 as an example. For example, a resist pattern having an open bonding region is formed on the surface of the first substrate 101. The resist pattern may be formed by a known photolithography technique. With the resist pattern thus formed, the above-described metal material is deposited by a vacuum film forming method. Thereafter, if the resist pattern is removed (lifted off) using an organic solvent or the like, the first metal layer 102 can be selectively formed in the bonding region. In this case, the metal material may be deposited by vacuum vapor deposition, sputtering, or ion plating.

  Further, as shown below, the first metal layer 102 may be formed. First, a metal film made of a metal material to be the first metal layer 102 is formed on the surface of the first substrate 101. Also in this case, the metal film may be formed by a vacuum film forming method, a sputtering method, or the like. Next, a resist pattern is formed on the formed metal film so as to cover the bonding region and open other regions. The resist pattern may be formed by a known photolithography technique. Next, the metal film is selectively etched using the formed resist pattern as a mask. For example, when a metal film is made of Au, the metal film can be selectively etched by wet etching with an etchant composed of iodine, ammonium iodide, water, and ethanol. Thereby, the first metal layer 102 can be selectively formed in the junction region. Further, when there is a concern of contamination due to adsorption of organic substances or the like on the bonding surface, it is desirable to clean with heating, UV light, plasma, or the like after forming the metal layer.

  Further, in the sputtering method or the like, the first metal layer 102 may be formed by selectively depositing a metal material on the bonding region using a stencil mask.

  As described above, after each metal layer is formed, the first metal layer 102 of the first substrate 101 and the second metal layer 104 of the second substrate 103 are brought into contact with each other as shown in FIG. 1C. Here, in consideration of the flatness of the first substrate 101 and the second substrate 103, the second substrate 103 is placed on the first substrate 101 with the first metal layer 102 and the second metal layer 104 facing each other. In some cases, the first metal layer 102 and the second metal layer 104 may be in a state of being in partial contact with each other simply by being placed thereon. In such a state, the first metal layer 102 and the second metal layer 104 do not come into contact (contact) with a surface having a certain size. In such a case, a certain amount of load is applied between the first substrate 101 and the second substrate 103 so that a region in contact with the surface exists.

  As described above, when the first metal layer 102 and the second metal layer 104 are brought into contact with each other, the first metal layer 102 and the second metal layer 104 are directly bonded. Here, the mechanism of direct bonding will be described. The metal layer formed by sputtering or the like is a thin film having a microcrystalline structure. By superimposing thin films having this microcrystalline structure, metal atoms are diffused at the bonding interface of the thin films, thereby firmly bonding the two substrates. If the first metal layer 102 and the second metal layer 104 are integrated as described above, the first substrate 101 and the second substrate 103 can be joined by the first metal layer 102 and the second metal layer 104. Since the first metal layer 102 and the second metal layer 104 are composed of a metal material containing a metal having a positive free energy of formation of oxide at room temperature, a natural oxide film is formed on the surface even in the atmosphere. There is no, and the state which joined directly is easily obtained by making both contact | abut. This joining is not limited to the atmosphere, and may be performed in a reduced pressure environment, or may be performed in an atmosphere at or above atmospheric pressure. Further, the bonding environment is not limited to the atmosphere, and may be, for example, nitrogen or an inert gas. The bonding temperature may be room temperature. Moreover, you may heat as needed in order to assist the spreading | diffusion of bonding films.

  According to the manufacturing method described above, the first metal layer 102 formed in the bonding region of the peripheral portion excluding the central portion of the first substrate 101 made of the transparent material containing silicon dioxide, and the transparent material containing silicon dioxide. Thus, an optical device including at least a second metal layer 104 formed in a peripheral joining region excluding the central portion of the second substrate 103 and being in contact with and integrated with the first metal layer 102 is obtained. According to this optical device, as shown in the plan view of FIG. 2, a bonding region is provided in the peripheral portion except for the central portion 201, and a metal layer is formed in the central portion 201 of the first substrate 101 and the second substrate 103. Not formed. Therefore, the central portion 201 of the bonded first substrate 101 and second substrate 103 is in a state where light is transmitted. Therefore, according to the present embodiment, the light transmitted through the central portion 201 is in a state in which the optical characteristics of both the first substrate 101 and the second substrate 103 are reflected.

[Embodiment 2]
Next, a second embodiment of the present invention will be described. In the second embodiment, the etalon filter shown in FIG. 3 will be described as an example. In this etalon filter, a quartz plate (first substrate) 301 and a quartz plate (third substrate) 302 are arranged to face each other with a spacer (second substrate) 303 made of quartz. As described above, the space 321 exists between the quartz plate 301 and the quartz plate 302 by arranging the spacers 303 via the spacers 303. Further, the quartz plate 301 and the quartz plate 302 are provided with a reflective film 304 and a reflective film 305 on one opposing surface. Further, an antireflection film 306 and an antireflection film 307 are provided on the other surfaces of the quartz plate 301 and the quartz plate 302, respectively.

  Further, the quartz plate 301 and the spacer 303 are joined via the first metal layer 311 and the second metal layer 312. The first metal layer 311 is formed on the reflective film 304 in the bonding region 322 of the quartz plate 301. The bonding region 322 is provided in the peripheral portion excluding the transmission region 323 in the central portion of the quartz plate 301. The second metal layer 312 is formed on the joint surface (one surface) of the spacer 303 with the quartz plate 301. The first metal layer 311 and the second metal layer 312 are joined together by bringing the opposing surfaces into contact with each other. The quartz plate 301 and the spacer 303 are joined by the first metal layer 311 and the second metal layer 312 which are integrated in this way.

  Similarly, the quartz plate 302 and the spacer 303 are joined via the third metal layer 313 and the fourth metal layer 314. The third metal layer 313 is formed on the reflective film 305 in the bonding region 322 of the quartz plate 302. The bonding region 322 is a peripheral region excluding the transmission region 323 at the central portion of the quartz plate 302. The fourth metal layer 314 is formed on the joint surface (the other surface) of the spacer 303 with the quartz plate 302. The third metal layer 313 and the fourth metal layer 314 are joined together by bringing the opposing surfaces into contact with each other. The quartz plate 302 and the spacer 303 are joined by the third metal layer 313 and the fourth metal layer 314 integrated in this manner.

  The first metal layer 311, the second metal layer 312, the third metal layer 313, and the fourth metal layer 314 are made of a metal material containing a metal having a positive free energy of formation of oxide at room temperature. These may be any of Au, Pt, and alloys containing these metals, for example. Further, the first metal layer 311, the second metal layer 312, the third metal layer 313, and the fourth metal layer 314 are formed to have a thickness of three times or more of the surface roughness (arithmetic average roughness) of the formation surface. Yes. By the way, metals such as Au and Pt do not have high adhesion to quartz or metal oxides. For this reason, for example, each metal layer is composed of an adhesion layer made of a metal such as Ta, Ti, Cr, or Ni formed on the formation surface side and a metal layer made of Au, Pt or the like formed thereon. A layer structure is preferable.

  The etalon filter described above is a so-called Fabry-Perot interferometer. By setting the interval between the reflective film 304 and the reflective film 305 to be an integral multiple of ½ of the desired wavelength of light, in the optical path of “quartz plate 301 -space 321 -quartz plate 302” of the transmission region 323, Light having a desired wavelength can be transmitted.

  Hereinafter, a method for manufacturing the etalon filter which is an optical device according to the present embodiment will be briefly described. First, a quartz plate 301 having a reflection film 304 formed on one surface and an antireflection film 306 formed on the other surface, a reflection film 305 formed on one surface, and an antireflection film 307 on the other surface. A quartz plate 302 on which is formed is prepared. Each quartz plate has a size of 4 mm × 4 mm and a plate thickness of 1 mm.

Further, as is well known, the reflection film 304 and the antireflection film 306 are configured by alternately laminating a plurality of dielectric layers having different refractive indexes. Examples of the dielectric include silicon dioxide (SiO ₂ , refractive index = 1.445), titanium dioxide (TiO ₂ , refractive index = 2.3), tantalum pentoxide (Ta ₂ O ₅ , refractive index = 2.2). It is. Desired reflectance and transmittance (optical characteristics) can be obtained by appropriately setting the layer thickness and the number of stacked layers of each dielectric layer. For example, the reflective film 304 can be configured by laminating 10 or less dielectric layers having a thickness of about submicron. Each dielectric layer can be formed by, for example, a vacuum film forming method.

Next, the first metal layer 311 is formed in the bonding region 322 on one surface (reflection film forming surface) of the quartz plate 301. For example, a Ta layer is formed to a thickness of about 2 nm by a vacuum film forming method, and then an Au layer is formed to a thickness of about 10 nm to form the first metal layer 311 . Similarly, the third metal layer 313 is formed in the bonding region 322 on one surface (reflection film forming surface) of the quartz plate 302.

  Next, the second metal layer 312 is formed on one joint surface of the spacer 303. The spacer 303 is formed in such a dimension that the distance between the quartz plate 301 and the quartz plate 302 is 3 mm. In addition, the spacer 303 is formed so that the dimension of the cross section in the light transmission direction in the space 321 is φ1.5 mm in the assembled state. As the second metal layer 312, for example, a Ta layer is formed to a thickness of about 2 nm by a vacuum film forming method, and then an Au layer is formed to a thickness of about 10 nm. Similarly, a fourth metal layer 314 is formed on the other joint surface of the spacer layer 303.

Next, the first metal layer 311 of the quartz plate 301 and the second metal layer 312 of the spacer 303 are brought into contact with each other so that the quartz plate 301 and the spacer 303 are integrated with each other. 312 is joined. Similarly, by contacting the fourth metal layer 314 of the third metal layer 313 and the spacer 303 of the quartz plate 302 by integral, a quartz plate 302 and the spacer 303 third metal layer 313 and fourth metal layer joined by 31 4.

  Here, a certain amount of load is applied between both of the objects to be joined so that there is a region where the joining surfaces are in close contact with each other. When the flatness of the joint surface is high and a region in contact with the surface is formed only by its own weight in the mounted state, it is not necessary to apply a load. By doing in this way, as mentioned above, if the 1st metal layer 311 and the 2nd metal layer 312 are made to contact, the 1st metal layer 311 and the 2nd metal layer 312 will join directly. Similarly, the third metal layer 313 and the fourth metal layer 314 are directly joined.

Thus, if first metal layer 311 and the second metal layer 312 together, the quartz plate 301 and the spacer 303 can be joined by the first metal layer 311 and the second metal layer 312. Similarly, if the third metal layer 313 and the fourth metal layer 314 are integrated, the quartz plate 302 and the spacer 303 can be joined by the third metal layer 313 and the fourth metal layer 314.

  Since the first metal layer 311 and the second metal layer 312 are made of a metal material containing a metal that has a positive free energy of formation of oxide at room temperature, a natural oxide film is formed on the surface even in the atmosphere. There is no, and the state which joined directly is easily obtained by making both contact | abut. The same applies to the third metal layer 313 and the fourth metal layer 314.

  Hereinafter, the relationship between the layer thickness of the metal layer used for bonding and the surface roughness of the formation surface will be described. First, a plurality of 10 mm × 10 mm crystal plates (test pieces) having different surface roughness of the bonding surface are prepared, and a plurality of samples are prepared by forming metal layers having different layer thicknesses on the bonding surface and bonding them. Measure the tensile strength of the sample. The surface roughness (calculated average roughness) of the test piece is Ra 0.3 nm, Ra 0.7 nm, and Ra 1.5 nm. In the bonding, a metal layer composed of a Ta layer and an Au layer having a thickness of 2 nm is formed on the bonding surface (entire surface) of each test piece, and the metal layers are brought into contact with each other.

  In addition, each sample is manufactured by changing the thickness of the Au layer. In the specimen of Ra 0.3 nm, samples with the Au layer thicknesses of 0.3, 0.7, 1.0, 1.5, 2.5, and 5.5 (nm) are manufactured. In addition, for a specimen having a Ra of 0.7 nm, a sample having a Au layer thickness of 0.7, 1.4, 2.1, 3.5, 5.6, 9.8 (nm) was prepared. Yes. In addition, for a specimen having a thickness of Ra 1.5 nm, samples with Au layer thicknesses of 1.5, 3.0, 4.5, 6.0, 10.5, 25.5 (nm) were prepared. Yes.

  In FIG. 4, the result of having measured the tensile strength of the sample which joined the test pieces of each surface roughness with the thickness of each metal layer is shown. In FIG. 4, the horizontal axis represents a value obtained by dividing the thickness T (nm) of the formed metal layer by the surface roughness Ra (nm) of the test piece. Further, in FIG. 4, a black square is a sample using a test piece having a surface roughness Ra of 0.3 nm, a white circle is a sample using a test piece having a surface roughness Ra of 0.7 nm, and a black triangle is a test having a surface roughness Ra of 1.5 nm. It is a measurement result of the sample using a piece. As can be seen from FIG. 4, in any surface roughness of the test piece, the tensile strength is saturated when the thickness of the metal layer is set to three times or more of the surface roughness.

  Next, 10 mm × 10 mm crystal plates (test pieces) having different surface roughness of the bonding surfaces were prepared, and samples were prepared by bonding them by various bonding methods, and the tensile strength of the prepared samples was measured. Will be described. The surface roughness of the test piece is Ra 0.3 nm, Ra 0.7 nm, Ra 1.3 nm, Ra 3 nm. The bonding method includes optical contact, surface activated bonding, and the above-described bonding method according to the present invention. In the bonding method according to the present invention, a metal layer composed of a Ta layer having a thickness of 2 nm and an Au layer having a thickness of 10 nm is formed on the bonding surface (entire surface) of each test piece, and the metal layers are brought into contact with each other. At this time, in order to tightly join the two test pieces in which the metal layers were brought into contact with each other, the pressure was applied with 20 kgf.

  Table 1 below shows the results of measuring the tensile strength of the samples obtained by joining the test pieces having respective surface roughnesses with each joining method. The unit of tensile strength shown in the table is MPa. In the table, “25 or more” indicates a state in which, in the tensile strength test, when the pressure is 25 MPa or more, the entire sample is broken and a test with a higher strength cannot be performed.

  As shown in Table 1, it can be seen that, according to the bonding method of the present invention, when the surface roughness is 0.3 nm, a stronger bonding strength is obtained compared to the optical contact and the surface activated bonding. Further, it can be seen that the bonding method of the present invention provides high bonding strength even at a surface roughness of 0.7 nm or more, which cannot be bonded by optical contact and surface activation bonding. Thus, when the surface roughness is in the range of 0.3 nm to 0.7 nm, the bonding method of the present invention has a higher bonding strength than the optical contact and the surface activated bonding. In addition, when the surface roughness is 0.7 nm or more, bonding is possible only by the bonding method of the present invention.

  As described above, according to the present invention, metal layers made of a metal material containing a positive metal having a positive oxide generation temperature at normal temperature are brought into contact with each other and joined together, resulting in an increase in product cost. Thus, an optical device having a high bonding strength between optical components can be manufactured. In particular, by setting the thickness of the metal layer to three times or more the surface roughness of the formation surface, a greater bonding strength can be obtained. In addition, optical devices can be manufactured by joining parts made of various materials.

  The present invention is not limited to the embodiment described above, and many modifications and combinations can be implemented by those having ordinary knowledge in the art within the technical idea of the present invention. It is obvious. For example, the bonding region for forming the metal layer may be the entire region surrounding the central portion of the substrate, or may be partially provided in the peripheral portion other than the central portion of the substrate. Moreover, when using a spacer for gap preparation, a spacer may be made into an integral structure and a spacer may be comprised from several components. Further, the spacer need not be made of the same material as the first substrate made of a transparent material containing silicon dioxide. Further, a plurality of optical devices may be manufactured at the same time by using a large-area substrate (for example, 2 inches in diameter and 1 mm in thickness) and cutting it after bonding.

  DESCRIPTION OF SYMBOLS 101 ... 1st board | substrate, 102 ... 1st metal layer, 103 ... 2nd board | substrate, 104 ... 2nd metal layer, 201 ... Center part.

Claims (10)

Forming a first metal layer in a bonding region in a peripheral portion excluding a central portion of the first substrate made of a transparent material containing silicon dioxide;
Forming a second metal layer on one surface of the second substrate;
The first substrate and the second substrate are joined by the first metal layer and the second metal layer by bringing the first metal layer of the first substrate into contact with the second metal layer of the second substrate. And at least a process of
The first metal layer and the second metal layer are composed of a metal material containing a metal having a positive free energy of formation of oxide at room temperature ,
The first metal layer and the second metal layer are formed to have a thickness not less than three times the surface roughness on the formation surface of the first metal layer and the second metal layer. Method. In the manufacturing method of the optical device of Claim 1,
The second substrate is made of a transparent material containing silicon dioxide,
The method of manufacturing an optical device, wherein the second metal layer is formed in a bonding region in a peripheral portion excluding a central portion of the second substrate. In the manufacturing method of the optical device of Claim 1,
Forming a third metal layer in a bonding region in a peripheral portion excluding a central portion of a third substrate made of a transparent material containing silicon dioxide;
Forming a fourth metal layer on the other surface of the second substrate;
The third substrate and the second substrate are joined by the third metal layer and the fourth metal layer by bringing the third metal layer of the third substrate into contact with the fourth metal layer of the second substrate. Comprising the steps of:
The method for producing an optical device, wherein the third metal layer and the fourth metal layer are made of a metal material containing a metal having a positive free energy of formation of an oxide at room temperature. In the manufacturing method of the optical device according to claim 3,
The optical device is characterized in that the third metal layer and the fourth metal layer are formed to have a thickness of three times or more of the surface roughness on the formation surface of the third metal layer and the fourth metal layer. Method. In the manufacturing method of the optical device of any one of Claims 1-4 ,
The method of manufacturing an optical device, wherein the metal material is selected from Au, Pt, and alloys containing these metals. A first metal layer formed in a bonding region in a peripheral portion excluding the central portion of the first substrate made of a transparent material containing silicon dioxide;
At least a second metal layer formed on one surface of the second substrate and in contact with the first metal layer;
The first metal layer and the second metal layer are made of a metal material containing a metal having a positive free energy of formation of oxide at room temperature ,
The optical device, wherein the first metal layer and the second metal layer are formed to have a thickness that is at least three times the surface roughness of the surface on which the first metal layer and the second metal layer are formed. . The optical device according to claim 6.
The second substrate is made of a transparent material containing silicon dioxide,
The optical device, wherein the second metal layer is formed in a bonding region in a peripheral portion excluding a central portion of the second substrate. The optical device according to claim 6.
A third metal layer formed in a bonding region in a peripheral portion excluding the central portion of the third substrate made of a transparent material containing silicon dioxide;
And at least a fourth metal layer formed on the other surface of the second substrate and in contact with the third metal layer.
The optical device, wherein the third metal layer and the fourth metal layer are made of a metal material containing a metal having a positive free energy of formation of an oxide at room temperature. The optical device according to claim 8.
The optical device, wherein the third metal layer and the fourth metal layer are formed to have a thickness that is at least three times the surface roughness of the formation surface of the third metal layer and the fourth metal layer. . The optical device according to any one of claims 6 to 9 ,
The optical device is characterized in that the metal material is selected from Au, Pt, and alloys containing these metals.

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