JP2017015946A - Interference filter, optical module, electronic apparatus, and method for manufacturing interference filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an interference filter having high spectral accuracy, an optical module, an electronic apparatus, and a method for manufacturing an interference filter.SOLUTION: A wavelength interference filter 5 includes a fixed reflection film 54 and a movable reflection film 55, and a fixed substrate 51 where the fixed reflection film 54 is disposed. The fixed substrate 51 includes: a counter surface 51A including a first reflection film region A1 where the fixed reflection film 54 is disposed; and an outer surface 51B opposite to the counter surface 51A and including a first light-transmitting region A2 overlapping the first reflection film region A1 in a plan view observed in a normal direction. The first reflection film region A1 has an arithmetic average roughness larger than that of the first light-transmitting region A2.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an interference filter, an optical module, an electronic device, and a method for manufacturing the interference filter.

Conventionally, an interference filter having a pair of reflective films is known (see, for example, Patent Document 1).
In such an interference filter, a first substrate provided with a reflective film made of an alloy film such as AgC and a first substrate provided with a fixed mirror (reflective film) made of an alloy film such as AgC. And a second substrate provided with a movable mirror (reflective film) made of an alloy film such as AgC. Since an Ag alloy film or an Ag film has high reflectance characteristics with respect to a wide wavelength range, by selecting such an Ag alloy film or an Ag film as a reflective film, for example, a desired target wavelength from a wide target wavelength range. Can be transmitted from the interference filter.

  On the other hand, such an Ag alloy film or an Ag film has a problem in terms of long-term reliability because it easily deteriorates because atoms easily move and aggregate. On the other hand, in order to suppress the deterioration of the Ag alloy film or the Ag film, a configuration in which a protective film is formed on the surface is known (for example, see Patent Document 2).

JP 2014-194556 A JP 2012-42584 A

  By the way, in the said patent document 2, by forming a protective film on a reflecting film, surface diffusion of a reflecting film can be suppressed and deterioration and alteration of a film can be suppressed. However, the film stress of the protective film may cause shape deterioration such as hillocks and whiskers. When such hillocks and whiskers occur, the distance between the reflective films facing each other varies depending on the position of the reflective film, so that the half-value width of the light emitted from the interference filter is widened and the spectral accuracy is reduced. There are challenges.

  An object of the present invention is to provide an interference filter, an optical module, an electronic device, and a method for manufacturing the interference filter having high spectral accuracy.

  An interference filter according to an application example of the present invention includes a pair of reflection films and a substrate on which any one of the pair of reflection films is provided, and the substrate includes any one of the pair of reflection films. A light transmission region that overlaps with the reflection film region in a plan view as viewed from a normal direction to the first surface, and a first surface having a reflection film region to be provided, and a surface opposite to the first surface And the reflective film region has an arithmetic mean roughness larger than that of the light transmission region.

In this application example, the reflective film region of the substrate has an arithmetic average roughness larger (coarse) than the light transmission region.
The light transmission region of the substrate is a surface on which light is incident on a pair of reflection films, or a surface through which light having a predetermined wavelength emitted by the light interference effect of the pair of reflection films is transmitted. It is formed on the optical surface in order to suppress scattering and the like. On the other hand, in this application example, on the surface of the substrate opposite to the light transmission region, a reflection film region having an arithmetic average roughness larger than that of the light transmission region is provided, and a reflection film is provided in the reflection film region. ing. By providing a reflective film in such a reflective film region, the reflective film can be brought into close contact with the substrate, and generation of hillocks and whiskers can be suppressed. Therefore, inconvenience that the gap size is not uniform due to the influence of hillocks and whiskers between the pair of reflective films is suppressed, and light having a desired target wavelength can be emitted from the interference filter with high spectral accuracy. Further, when the emitted light is emitted from the light transmission region of the substrate, as described above, the light transmission region has an arithmetic average roughness smaller than that of the reflective film region, so that there is no scattering of the emitted light, and the target wavelength. A decrease in the light intensity of the emitted light can be suppressed.

In the interference filter of this application example, it is preferable that a plurality of rough surface forming bodies smaller than the area of the reflection film in the plan view are scattered on the surface of the reflection film region.
In this application example, a plurality of rough surface forming bodies are scattered in the reflective film region, so that the arithmetic average roughness is larger than that of the light transmission region. Such a rough surface forming body can be formed by, for example, leaving a part of the electrode when removing the electrode by etching when an electrode made of a metal film or the like is provided on the interference filter. . In this case, when an electrode is provided in the interference filter, it is possible to form a rough surface at the same time when determining the shape of the electrode by etching, and it is not necessary to separately perform a roughening process on the reflective film region, so that the manufacturing efficiency is good It becomes.

In the interference filter of this application example, the reflective film region has a surface roughened layer disposed so as to cover the first surface, and the surface roughened layer has an arithmetic average surface that is more than the light transmission region. It is preferable that the roughness is large, and one of the pair of reflective films is provided on the surface of the surface roughened layer.
In this application example, the substrate is provided in the reflective film region, has a surface roughened layer having a rough surface, and the reflective film is provided on the surface of the surface roughened layer. In this application example, as in the above application example, the adhesion of the reflective film can be improved, so that generation of hillocks and whiskers is suppressed, and light having a desired target wavelength is emitted from the interference filter with high spectral accuracy. Can do.

In the interference filter of this application example, the arithmetic average roughness in the reflective film region is preferably 1 nm or more and 8 nm or less.
In this application example, the arithmetic average roughness of the reflective film region is a rough surface of 1 nm to 8 nm. Here, when the arithmetic average roughness is less than 1 nm, the surface becomes an optical surface, and many hillocks and whiskers are generated in the reflective film. On the other hand, when the arithmetic average roughness is larger than 8 nm, light scattering by the rough surface and aggregation of metal atoms constituting the reflection film are promoted, so that the spectral accuracy characteristic of the interference filter is deteriorated. On the other hand, when the arithmetic average roughness of the rough surface is 1 nm or more and 8 nm or less as described above, the reflective film can be adhered to the substrate, generation of hillocks and whiskers can be suppressed, and the interference filter Deterioration of spectral accuracy characteristics can also be suppressed.

An optical module according to an application example of the invention includes the interference filter as described above and a light receiving unit that receives light emitted from the interference filter.
In this application example, as described above, the light having a desired target wavelength can be emitted from the interference filter with high spectral accuracy, and the target wavelength included in the incident light is received by the light receiving unit. The light intensity of the light can be accurately measured.

An electronic apparatus according to an application example of the invention includes the optical module as described above and a control unit that controls the optical module.
In this application example, as described above, light of a target wavelength can be detected by the optical module with high spectral accuracy from the interference filter, and various processing such as spectral measurement processing is performed with high accuracy based on the detection result. Can do.

  An interference filter manufacturing method according to an application example of the present invention includes a pair of reflective films and a substrate on which any one of the pair of reflective films is provided, and the substrate is any of the pair of reflective films. Light that overlaps the reflective film region in a plan view as viewed from the normal direction to the first surface, and a first surface having the reflective film region on which the first surface is provided, and a surface opposite to the first surface A second surface including a transmissive region, wherein the reflective film region for forming the reflective film of the substrate has an arithmetic average roughness that is greater than that of the light transmissive region. A roughening step for roughening the surface and a reflective film forming step for forming any one of the pair of reflective films on the reflective film region.

In this application example, a roughening step for making the arithmetic average roughness of the reflective film region of the substrate rougher than that of the light transmitting region is performed, and the reflective film is formed on the roughened reflective film region in the reflective film forming step. Is deposited.
As a result, similar to the above-described invention, the adhesion of the reflective film provided in the reflective film region can be increased as compared with the case where a reflective film is provided on the optical surface, and the occurrence of hillocks and whiskers can be suppressed. The spectral accuracy of the interference filter can be increased.

In the manufacturing method of the interference filter according to this application example, it is preferable that the roughening step is roughened by performing an etching process on the reflective film region of the substrate.
In this application example, the reflective film region is roughened by performing an etching process on the substrate. Usually, in order to set the gap dimension between the pair of reflective films to a predetermined initial dimension, the substrate may be etched to form a groove. In this application example, the reflective film region is roughened during the etching for forming the shape of the substrate. Specifically, for example, the etching time in the etching process can be made longer than the normal etching time for performing the substrate shape, or the etching surface can be roughened by changing the composition of the etching solution. It becomes.
In this application example, the surface roughening step can be performed during the etching process for forming the substrate shape, and the manufacturing efficiency can be improved.

In the method of manufacturing an interference filter according to this application example, it is preferable that the roughening step is performed by performing a polishing process on the reflective film region of the substrate.
In this application example, the reflective film region is roughened by performing a polishing process on the substrate. Examples of the polishing treatment include blast treatment and mechanical polishing treatment. In this case, the reflective film region can be reliably roughened, and the arithmetic average roughness of the reflective film region can be accurately set to a desired arithmetic average roughness.

An interference filter manufacturing method according to this application example includes a rough surface forming layer forming step of forming a rough surface forming layer on the substrate, and the roughening step includes viewing the substrate from the substrate thickness direction. The rough surface forming layer overlapping the reflective film region in a plan view is etched, and a part of the rough surface forming layer is left on the substrate by the etching process to form a plurality of rough surface forming bodies. It is preferable to roughen the surface.
In this application example, after the rough surface forming layer is formed on the substrate by the rough surface forming layer forming step, the rough surface forming layer is etched by the roughening step, and one surface of the rough surface forming layer is formed in the reflective film region. A part is left and a plurality of rough surface forming bodies are scattered.
As a result, similar to the above application example, a reflective film region having an arithmetic average roughness larger than that of the light transmission region can be formed, and the reflective film can be brought into close contact with the substrate to suppress the occurrence of hillocks and whiskers.
Further, as the rough surface forming layer, for example, an electrode layer constituting an electrostatic actuator for changing the dimension between a pair of reflecting films, an electrode layer for releasing charged charges of the substrate, or a specific portion of the substrate A protective layer for protection can be used. In this case, the reflective film region can be roughened at the same time when the electrode layer and the protective layer are formed. For example, a separate process for roughening the reflective film region is not required, and the manufacturing efficiency can be improved. .

In the method for manufacturing an interference filter according to this application example, the rough surface forming layer is a conductive layer for forming an electrode, and the roughening step performs the etching process by masking a position where the electrode is formed. It is preferable to implement.
In this application example, a conductive layer for forming an electrode is used as the rough surface forming layer, and in the roughening step, the region where the electrode is formed is masked, and the rough surface forming layer is etched. . As a result, the reflection film region can be roughened at the same time as the electrodes are formed on the interference filter.

In the manufacturing method of the interference filter according to this application example, the rough surface forming layer is any one of Cr, W, Ti, and ITO, or an alloy material mainly containing any one of Cr, W, Ti, and ITO. It is preferable that
In this application example, the rough surface forming layer is made of Cr, W, Ti, and ITO, or an alloy material containing any one of them as a main component. When Cr, W, Ti, ITO, or an alloy thereof is used as the electrode layer, a part of the electrode layer is likely to remain on the substrate in the etching process, and the reflective film region is easily roughened. Therefore, the formation of the electrode layer and the roughening of the reflective film region can be efficiently performed.

In the method for manufacturing an interference filter according to this application example, the roughening step includes forming a surface roughened layer in a region covering at least the reflective film region of the substrate, and roughening a surface of the surface roughened layer. Is preferable.
In this application example, a surface roughened layer is formed on at least the reflective film region of the substrate, and after the surface of the surface roughened layer is roughened, the reflective film is formed on the surface roughened layer. Even in this case, similarly to the above-described invention, the reflective film can be formed on the roughened reflective film region, and generation of hillocks and whiskers can be suppressed.

In the interference filter manufacturing method according to this application example, the roughening step roughens the surface of the surface roughened layer by performing O ₂ plasma treatment on the surface roughened layer. It is preferable.
In this application example, the surface roughened layer is roughened by performing O ₂ plasma treatment on the surface roughened layer. In this case, since the surface of the surface roughened layer is oxidized by the O ₂ plasma treatment, the adhesion can be further improved when a metal film is used as the reflective film.

The top view which shows schematic structure of the wavelength variable interference filter which concerns on 1st embodiment of this invention. Sectional drawing at the time of cut | disconnecting the wavelength variable interference filter in FIG. 1 by the AA line. The flowchart which shows the manufacturing method of the wavelength variable interference filter in 1st embodiment. The figure which shows the board | substrate shape in each step included in the fixed board | substrate formation step in the manufacturing method of the wavelength variable interference filter of 1st embodiment. The figure which shows the board | substrate shape in each step included in the movable board | substrate formation step in the manufacturing method of the wavelength variable interference filter of 1st embodiment. The figure which shows the board | substrate shape in each step included in the fixed board | substrate formation step in the manufacturing method of the wavelength variable interference filter in the modification of 1st embodiment. Sectional drawing which shows schematic structure of the wavelength variable interference filter of 2nd embodiment. The figure which shows the board | substrate shape in the electrode formation step of a fixed board | substrate formation step, and the roughening step in the manufacturing method of the wavelength variable interference filter of 2nd embodiment. Sectional drawing which shows schematic structure of the wavelength variable interference filter of 3rd embodiment. The figure which shows the board | substrate shape in the roughening step of the fixed board | substrate formation step in the manufacturing method of the wavelength variable interference filter of 3rd embodiment. The perspective view which shows schematic structure of the printer in 4th embodiment. FIG. 10 is a block diagram illustrating a schematic configuration of a printer according to a fourth embodiment. Sectional drawing which shows schematic structure of the spectrometer incorporated in the printer of 4th embodiment.

[First embodiment]
Hereinafter, the variable wavelength interference filter (interference filter) according to the first embodiment of the present invention will be described.
[Configuration of wavelength tunable interference filter]
FIG. 1 is a plan view showing a schematic configuration of a variable wavelength interference filter 5 according to the first embodiment.
FIG. 2 is a cross-sectional view of the tunable interference filter 5 in FIG. 1 taken along line AA.
As shown in FIGS. 1 and 2, the variable wavelength interference filter 5 includes a translucent fixed substrate 51 and a movable substrate 52 that constitute the substrate of the present invention. The fixed substrate 51 and the movable substrate 52 are each formed of, for example, various glasses such as soda glass, crystalline glass, quartz glass, lead glass, potassium glass, borosilicate glass, and alkali-free glass, crystal, and the like. . The fixed substrate 51 and the movable substrate 52 are integrally formed by bonding with a bonding film 53 formed of, for example, a plasma polymerization film mainly containing siloxane.

A fixed reflection film 54 that is one of a pair of reflection films according to the present invention is provided on an opposing surface 51A (first surface in the present invention) of the fixed substrate 51 that faces the movable substrate 52, and the fixed substrate 51 of the movable substrate 52 is provided. A movable reflective film 55, which is the other of the pair of reflective films in the present invention, is provided on the facing surface 52A (first surface in the present invention) that faces the surface. The fixed reflection film 54 and the movable reflection film 55 are disposed to face each other with a gap G interposed therebetween.
The wavelength variable interference filter 5 is provided with an electrostatic actuator 56 used to adjust (change) the size of the gap G. The electrostatic actuator 56 includes a fixed electrode 561 provided on the facing surface 51A of the fixed substrate 51 and a movable electrode 562 provided on the facing surface 52A of the movable substrate 52.
In the following description, a plan view seen from the thickness direction of the fixed substrate 51 or the movable substrate 52, that is, a plan view seen from the film thickness direction of the fixed reflection film 54 and the movable reflection film 55. Is referred to as filter plan view. In the present embodiment, the center point of the fixed reflection film 54 and the center point of the movable reflection film 55 coincide with each other in the filter plan view, and the center point of these reflection films 54 and 55 in the plan view is indicated by O.

(Configuration of fixed substrate 51)
The fixed substrate 51 is made of, for example, a glass substrate, and has a facing surface 51A (first surface in the present invention) facing the movable substrate 52 and an outer surface 51B (second surface in the present invention) opposite to the facing surface 51A. And have. One end side (side C1-C2 in FIG. 1) of the fixed substrate 51 protrudes outward from the substrate edge (side C5-C6 in FIG. 1) of the movable substrate 52.
Further, as shown in FIG. 2, an electrode arrangement groove 511 and a reflection film installation portion 512 formed by, for example, etching processing or the like are provided on the facing surface 51 </ b> A side of the fixed substrate 51.
On the other hand, the outer surface 51B of the fixed substrate 51 is formed on an optical surface having an arithmetic average roughness Ra of, for example, less than 1 nm. Thereby, with respect to the outer surface 51 </ b> B of the fixed substrate 51, it is possible to suppress a light amount loss due to light scattering, irregular reflection, or the like, a fluctuation in light incident angle (emission angle), and the like. In addition, on the outer side surface 51B of the fixed substrate 51, a region that overlaps a first reflective film region A1 described later in the filter plan view is a light transmission region A2 in the present invention. In the present embodiment, since incident light is vertically incident on the reflection films 54 and 55 of the wavelength tunable interference filter 5, in the filter plan view, the outer surface 51B of the fixed substrate 51 is first in the filter plan view. The region overlapping the reflective film region A1 is defined as the first light transmission region A2, but this is not the case when the incident angle with respect to the wavelength variable interference filter 5 is an angle other than 90 °. That is, when light is incident (or emitted) at an incident angle α that is not 90 ° with respect to the reflective films 54 and 55, the area incident (or emitted) on the first reflective film area A1 on the outer surface 51B is the first light. It becomes a transmission region A2.

The electrode placement groove 511 is formed in an annular shape centering on the filter center point O of the fixed substrate 51 in the filter plan view, for example. Further, a wiring groove (not shown) that communicates from the electrode arrangement groove 511 to the side C <b> 3-C <b> 4 of the fixed substrate 51 is provided on the facing surface 51 </ b> A of the fixed substrate 51.
And the fixed electrode 561 which comprises the electrostatic actuator 56 is provided in the groove bottom face of the electrode arrangement | positioning groove | channel 511, and it opposes the movable electrode 562 of the movable part 521. FIG. Note that an insulating film for ensuring insulation between the fixed electrode 561 and the movable electrode 562 may be stacked over the fixed electrode 561.
A fixed extraction electrode 563 is provided on a part of the outer peripheral edge of the fixed electrode 561. The fixed extraction electrode 563 is extracted along the wiring groove provided from the electrode arrangement groove 511 toward the side C3-C4. Further, the wiring groove is provided with a bump portion 565A (see FIG. 1) protruding toward the movable substrate 52, and the fixed extraction electrode 563 extends to the bump portion 565A. The fixed extraction electrode 563 is in contact with and electrically connected to the fixed connection electrode 565 provided on the movable substrate 52 side on the bump portion 565A. The fixed connection electrode 565 extends from the region facing the wiring groove to the electrical surface 524 (see FIG. 1), and forms a fixed electrode pad 565P on the electrical surface 524.

As shown in FIG. 2, the reflection film installation portion 512 protrudes from the center portion of the electrode placement groove 511 toward the movable substrate 52.
The protruding front end surface of the reflection film installation portion 512 is a first reflection film region A1 (reflection film region in the present invention), and a fixed reflection film 54 is provided on the surface.
Here, as the fixed reflective film 54, an Ag film or an Ag alloy film is preferably used. Such an Ag film or an Ag alloy film has high reflection characteristics over a wide wavelength range from the visible light region to the near infrared region. Therefore, by using an Ag film or an Ag alloy film for the fixed reflective film 54 and the movable reflective film 55 of the wavelength tunable interference filter 5, it becomes possible to select and emit a desired target wavelength from a wide target wavelength range. . On the other hand, in Ag films and Ag alloy films, Ag atoms are easy to move, and the film quality is likely to change (deteriorate easily) due to aggregation. Therefore, in this case, it is preferable to provide the protective film 541 on the fixed reflective film 54. As the protective film 541, for example, a transparent conductive oxide such as ITO or IGO, an oxide insulator such as SiO ₂ or Al ₂ O _3, or the like can be used.

Further, the arithmetic average roughness Ra of the first reflective film region A1 of the present embodiment is a rough surface having an arithmetic average roughness Ra larger than that of the outer surface 51B (first light transmission region A2) of the fixed substrate 51.
Specifically, the arithmetic average roughness Ra of the first reflective film region A1 is preferably 1 nm or more and 8 nm or less, and more preferably 5 nm or more and 8 nm or less.
Here, when the arithmetic average roughness Ra of the first reflective film region A1 is less than 1 nm, it becomes an optical surface, like the outer surface 51B of the fixed substrate 51. In this case, the adhesion of the fixed reflective film 54 to the first reflective film region A1 is lowered. In this case, protrusions such as hillocks and whiskers are easily formed, and when the hillocks and whiskers are formed, the surface of the fixed reflective film 54 does not become a uniform plane.
Table 1 below shows the case where the arithmetic average roughness Ra in the first reflective film region A1 is an optical surface of less than 1 nm (Comparative Example), and the arithmetic average roughness Ra is 1 nm or more and 8 nm or less. 6 is a table showing the adhesion of a fixed reflective film 54.

  For example, when an Ag alloy film is formed as the fixed reflection film 54 by sputtering, if the arithmetic average roughness Ra is small as in the comparative example, the adhesion to the fixed substrate 51 is reduced, and the fixed reflection film 54 is configured. As a result, the generation of hillocks, whiskers, film alteration, and the like is promoted.

  On the other hand, if the arithmetic average roughness Ra is larger than 8 nm, the irregularities on the surface of the first reflective film region A1 cause scattering of light incident on or emitted from the fixed reflective film 54, or the light traveling direction is changed and reflected. When the optical distance between the films 54 and 55 is changed, the filter characteristics of the wavelength variable interference filter 5 are deteriorated. That is, the light that has passed through the wavelength tunable interference filter 5 contains a lot of light having a wavelength other than the target wavelength, and the full width at half maximum is widened. Furthermore, when the arithmetic average roughness Ra is too rough, aggregation of Ag atoms is promoted, and generation of nodules and the like is promoted.

  On the other hand, in the present embodiment, as described above, the arithmetic average roughness Ra of the first reflective film region A1 is set to 1 nm or more and 8 nm or less. In this case, as shown in Table 1, the adhesiveness (adhesive force) between the fixed reflective film 54 and the first reflective film region A1 is improved as compared with the comparative example. Table 1 shows an example where the arithmetic average roughness Ra is 1.26 nm as an example, but the adhesiveness is further increased by further increasing (roughening) the arithmetic average roughness Ra. In this case, the movement of Ag atoms is suppressed, and it is possible to further suppress film alteration, generation of hillocks and whiskers.

In addition, the deterioration of the filter characteristics of the wavelength tunable interference filter 5 due to the arithmetic average roughness Ra in the first reflective film region A1 depends on the target wavelength range to be spectrally divided by the wavelength variable interference filter 5, and the minimum wavelength in the target wavelength range is By setting the arithmetic average roughness Ra to 1/50 or less, it is possible to suppress a decrease in filter characteristics. For example, in the present embodiment, the visible light region (400 nm to 700 nm) is set as the target wavelength region. In this case, since the minimum wavelength λ _min in the target wavelength region is 400 nm, the arithmetic average roughness Ra of the first reflective film region A1 is preferably set to 8 nm (= 400/50 nm) or less. In this case, since it coincides with the above-described conditions for suppressing the generation of hillocks and whiskers, the arithmetic average roughness Ra of the first reflective film region A1 may be set to 1 nm or more and 8 nm or less.
Further, for example, when the target wavelength region includes the ultraviolet region (for example, 200 nm to 700 nm), the arithmetic mean roughness Ra of the first reflective film region A1 is set to 4 nm or less to suppress generation of hillocks and whiskers. Is preferably an arithmetic average roughness Ra of 1 nm or more. Therefore, in this case, the arithmetic average roughness Ra is preferably set to 1 nm or more and 4 nm or less.

  In the present embodiment, an Ag film or an Ag alloy film is exemplified as the fixed reflective film 54, but the same applies when other metal reflective films (for example, Au, Al, etc.) are used. When such a metal reflection film is selected as the fixed reflection film 54, the arithmetic average roughness Ra of the first reflection film region A1 may be set as described above.

(Configuration of movable substrate)
The movable substrate 52 includes, for example, a circular movable portion 521 centered at the filter center point O in the filter plan view as shown in FIG. 1, and a holding portion 522 that is coaxial with the movable portion 521 and holds the movable portion 521. A substrate outer peripheral portion 525 provided outside the holding portion 522.
Further, as shown in FIG. 1, one end side (side C <b> 7-C <b> 8 in FIG. 1) of the movable substrate 52 projects outward from the substrate edge (side C <b> 3-C <b> 4 in FIG. 1) of the fixed substrate 51. The projecting portion constitutes an electrical component surface 524.

As shown in FIG. 2, the movable portion 521 is formed to have a thickness dimension larger than that of the holding portion 522. For example, in this embodiment, the movable portion 521 is formed to have the same dimension as the thickness dimension of the movable substrate 52. The movable portion 521 is formed to have a diameter that is larger than at least the diameter of the outer peripheral edge of the reflective film installation portion 512 in the filter plan view. A movable reflective film 55 and a movable electrode 562 are provided on the facing surface 52A of the movable portion 521.
Moreover, the area | region which opposes the fixed reflective film 54 of the movable part 521 is 2nd reflective film area | region A3, and becomes the rough surface whose arithmetic mean roughness Ra is 1 nm or more and 8 nm or less similarly to 1st reflective film area | region A1. .
Furthermore, the outer surface 52B (second surface in the present invention) opposite to the fixed substrate 51 of the movable portion 521 is similar to the outer surface 51B of the fixed substrate 51 with an optical surface having an arithmetic average roughness Ra of less than 1 nm. Become. Moreover, the area | region which overlaps with 2nd reflective film area | region A3 in filter planar view among the outer surface 52B becomes 2nd light transmissive area | region A4. As in the case of the first light transmission region A2, when light is incident (or emitted) at an incident angle α other than 90 ° with respect to the reflective films 54 and 55, the light is incident on the second reflective film region A3 on the outer surface 52B. The area to be (or emitted) is the second light transmission area A4.

The movable reflective film 55 is provided in the second reflective film region A3 provided at the center of the opposed surface 52A of the movable part 521, and faces the fixed reflective film 54 via the gap G between the reflective films. As the movable reflective film 55, a reflective film having the same configuration as that of the fixed reflective film 54 described above may be used, and a protective film 551 may be provided on the surface.
Here, in the second reflective film region A3 of the movable part 521 provided with the movable reflective film 55, the arithmetic average roughness Ra is 1 nm or more and 8 nm or less as described above. Therefore, like the fixed reflective film 54, the occurrence of hillocks and whiskers is suppressed.

  The movable electrode 562 faces the fixed electrode 561 with a predetermined gap and is formed in an annular shape having the same shape as the fixed electrode 561. The movable electrode 562 forms an electrostatic actuator 56 together with the fixed electrode 561. The movable substrate 52 is provided with a movable extraction electrode 564 connected to the outer peripheral edge of the movable electrode 562. The movable lead electrode 564 is provided from the movable portion 521 along the region facing the wiring groove and across the electrical component surface 524, and the electrical component surface 524 forms a movable electrode pad 564P.

  Further, as described above, the fixed connection electrode 565 is provided on the movable substrate 52, and the fixed connection electrode 565 is connected to the fixed extraction electrode 563 via the bump portion 565A.

The holding part 522 is a diaphragm that surrounds the periphery of the movable part 521, and has a thickness dimension smaller than that of the movable part 521. Such a holding part 522 is easier to bend than the movable part 521, and the movable part 521 can be displaced toward the fixed substrate 51 by a slight electrostatic attraction. At this time, since the movable portion 521 has a thickness dimension larger than that of the holding portion 522 and rigidity, the shape change of the movable portion 521 is suppressed even when the holding portion 522 is pulled toward the fixed substrate 51 by electrostatic attraction. Is done. Therefore, the movable reflective film 55 provided on the movable portion 521 is hardly bent, and the fixed reflective film 54 and the movable reflective film 55 can be always maintained in a parallel state.
In this embodiment, the diaphragm-like holding part 522 is illustrated, but the present invention is not limited to this. For example, a configuration in which beam-like holding parts arranged at equiangular intervals around the filter center point O are provided. And so on.

  The substrate outer peripheral portion 525 is provided outside the holding portion 522 in the filter plan view. The surface of the substrate outer peripheral portion 525 that faces the fixed substrate 51 is bonded to the fixed substrate 51 through the bonding film 53.

[Manufacturing method of tunable interference filter]
Next, a method for manufacturing the wavelength variable interference filter as described above will be described with reference to the drawings.
FIG. 3 is a flowchart in the method of manufacturing the wavelength tunable interference filter according to this embodiment.
In the manufacture of the variable wavelength interference filter 5, as shown in FIG. 4, the fixed substrate 51 is formed by the fixed substrate forming step S1, the movable substrate 52 is formed by the movable substrate forming step S2, and these are performed by the substrate bonding step S3. The fixed substrate 51 and the movable substrate 52 are joined.

[Fixed substrate forming step]
FIG. 4 is a diagram showing an outline of the substrate shape in each step included in the fixed substrate forming step S1.
In the fixed substrate forming step S1, as shown in FIG. 4A, first, the surface (opposing surface 51A, outer surface 51B) of the base material (first glass substrate M1) for forming the fixed substrate 51 is arithmetically operated. Precision polishing is performed so that the average roughness Ra is less than 1 nm, for example, to a thickness of 500 μm.

Thereafter, an etching process is performed on the first glass substrate M1 using a resist pattern patterned by a photolithography method as a mask. As a result, as shown in FIG. 4B, the formation positions of the electrode placement groove 511, the reflection film installation part 512, and the wiring groove in the first glass substrate M1 are set to the groove depth of the protruding tip surface of the reflection film installation part 512. Etching is performed up to the size, and the surface of the protruding tip surface (first reflection film region A1) of the reflection film installation portion 512 is roughened (roughening step). The wiring trench is not shown in FIG.
Specifically, regions other than the electrode arrangement groove 511, the reflection film installation portion 512, and the wiring groove are masked, and buffered hydrofluoric acid (for example, NH ₄ HF ₂ (20.2 wt%), NH ₄ F (21 (2 wt%) mixed aqueous solution). Here, when a concave groove having an arithmetic average roughness Ra of less than 1 nm is formed by etching on a glass substrate, for example, the temperature during the etching process is set to 30 degrees, for example, an etching process of about 10 minutes and a drying process. And a plurality of times alternately. On the other hand, in this embodiment, the etching process is performed once with the temperature during the etching process being 30 degrees and the etching time being approximately 1 hour. Thus, the 1st reflective film area | region A1 from which arithmetic mean roughness Ra will be 2-3 nm can be formed by implementing a long-time etching process without putting a drying process in between.

  Thereafter, as shown in FIG. 4C, etching is further performed while masking areas other than the electrode placement groove 511 and the wiring groove region. In this etching process, buffered hydrofluoric acid similar to the etching process performed previously can be used. Further, in the present etching process, similarly to the above, the etching process may be performed for about 1 hour to increase the arithmetic average roughness Ra, and the short-time etching process and the drying process are alternately performed, The arithmetic average roughness Ra of the electrode placement groove 511 and the groove bottom surface of the wiring groove may be reduced.

In addition, although the above illustrated the etching process using the process in a liquid, it is not limited to this. For example, when performing a gas layer treatment as an etching treatment, the surface is etched by plasma treatment using fluorine gas. As the fluorine gas, for example, HFC (hydrofluorocarbon) such as CF ₄ , C ₂ F ₄ , C ₂ F ₆ , C ₃ F _8, or fluorine-containing compounds such as SF ₆ , SF ₃ , XeF ₂ may be used. it can. The fluorine gas as described above is transported after being diluted with a carrier gas. As the carrier gas, an inert gas is preferably used, and a rare gas such as He, Ar, Ne, or Xe, N _2, or the like can be used. For example, when the fluorine gas is CF ₄ and the carrier gas is N ₂ , the flow rate ratio of the fluorine gas and the carrier gas (CF ₄ : N ₂ ) is between 1: 1000 and 1:10. It is preferable to set to. Even in this case, the first reflective film region having a desired arithmetic average roughness Ra (for example, 2 to 3 nm) can be obtained by performing the etching process for about 1 hour and performing the etching process once without performing the drying process in between. A1 can be formed.
Thus, the schematic shape of the fixed substrate 51 is formed.

Next, a bump portion 565A is formed in the wiring groove, and then a fixed electrode 561 and a fixed extraction electrode 563 are formed as shown in FIG. 4D (electrode formation step). Specifically, an electrode material for forming the fixed electrode 561 and the fixed extraction electrode 563 (not shown in FIG. 4) is formed on the first glass substrate M1 by using an evaporation method, a sputtering method, or the like. The bump portion 565A may be formed by, for example, forming a material for forming the bump portion 565A such as a Ti thin film on the facing surface 51A and then removing the region other than the bump portion 565A by etching. For example, the bump portion 565A may be formed during the etching process.
As an electrode material of the fixed electrode 561 and the fixed extraction electrode 563, for example, a laminate of an ITO film, a TiW film and an Au film, a laminate of a Cr film and an Au film, or the like can be used. Various film materials having good conductivity and conductivity can be used.
And a resist is apply | coated to the 1st glass substrate M1, and a resist is patterned according to the shape of the fixed electrode 561 and the fixed extraction electrode 563 using the photolithographic method. Then, after patterning the fixed electrode 561 and the fixed extraction electrode 563 by wet etching, the remaining resist is removed.
4C, when the groove bottom surface of the electrode placement groove 511 and the wiring groove is roughened in the same manner as the first reflective film region A1, the fixed electrode 561 and the fixed extraction electrode 563 are replaced with the first glass substrate. It can be formed with high adhesion to M1.

Thereafter, as shown in FIG. 4E, a fixed reflective film 54 and a protective film 541 are formed (reflective film forming step).
Specifically, a material for forming the fixed reflective film 54 and the protective film 541 (for example, Ag alloy, ITO) is laminated on the first glass substrate M1 by sputtering or the like, and the first reflective film is formed by etching. The forming material deposited outside the region A1 is removed.
At this time, as described above, the surface of the first reflective film region A1 is roughened during the etching process so that the arithmetic average roughness Ra is 2 to 3 nm. For this reason, the formed fixed reflective film 54 is formed on the first glass substrate M1 with high adhesion, and generation of hillocks, whiskers, and the like is suppressed.

[Movable substrate formation step]
FIG. 5 is a diagram showing an outline of the substrate shape in each step included in the movable substrate forming step S2.
In the movable substrate forming step S2, as shown in FIG. 5 (A), first, the surface of the second glass substrate M2 for forming the movable substrate 52 is precisely adjusted so that the arithmetic average roughness Ra is less than 1 nm. Polish to a thickness of, for example, 500 μm.

Then, an etching process is performed by masking a region other than the holding portion 522 of the second glass substrate M2, thereby forming the holding portion 522 and changing the substrate shape of the movable substrate 52 as shown in FIG. decide.
Thereafter, as shown in FIG. 5 (C), the second reflective film region A3 is roughened by masking other than the second reflective film region A3 on the facing surface 52A of the second glass substrate M2 and performing an etching process. (Roughening step). In this etching process, the same buffered hydrofluoric acid as in the fixed substrate forming step S1 may be used. However, in this case, if the etching time is long, a groove is formed in the movable portion 521. To be shorter. In addition, it is preferable to adjust arithmetic mean roughness Ra by using the etching liquid which diluted buffered hydrofluoric acid further.
In this embodiment, an example in which only the second reflective film region A3 is roughened is shown, but the entire facing surface 52A of the movable substrate 52 may be roughened. In this case, the adhesion of the movable electrode 562, the movable extraction electrode 564, the fixed connection electrode 565, and the bonding film 53 to the movable substrate 52 can be improved.

  Thereafter, a conductive layer for forming the movable electrode 562, the movable extraction electrode 564 (not shown in FIG. 5), and the fixed connection electrode 565 (not shown in FIG. 5) on the opposing surface 52A of the second glass substrate M2 is formed by a CVD method. Film formation is performed using sputtering or the like. As the conductive layer 561 and the fixed extraction electrode 563, for example, a laminate of an ITO film, a TiW film and an Au film, a laminate of a Cr film and an Au film, or the like can be used. Then, the conductive layer is formed into a desired shape by an etching process, and the movable electrode 562, the movable extraction electrode 564, and the fixed connection electrode 565 are formed (electrode formation step).

Next, the movable reflective film 55 and the protective film 551 are formed (reflective film forming step).
Specifically, the material for forming the movable reflective film 55 and the protective film 551 (for example, Ag alloy, ITO) is laminated on the second glass substrate M2 by sputtering or the like, as in the case of forming the fixed reflective film 54 and the protective film 541. Then, the film forming material is formed, and the forming material formed outside the second reflective film region A3 is removed by etching.
At this time, as described above, the surface of the second reflective film region A3 is roughened during the etching process, and the arithmetic average roughness Ra is 2 to 3 nm. For this reason, the formed movable reflective film 55 is formed on the movable substrate 52 with high adhesion, and generation of hillocks, whiskers and the like is suppressed.

[Board bonding step]
Next, the substrate bonding step S3 will be described.
In the substrate bonding step S3, first, a plasma polymerized film containing polyorganosiloxane as a main component is applied, for example, to the first bonding portion 513 of the first glass substrate M1 and the second bonding portion 523 of the second glass substrate M2. A film is formed by a CVD method or the like.
Then, in order to providing the activation energy to the plasma-polymerized film of the first glass substrate M1 and the second glass substrate M2, performing the O ₂ plasma treatment or UV treatment. In the case of O ₂ plasma treatment, the treatment is performed for 30 seconds under conditions of an O ₂ flow rate of 1.8 × 10 ⁻³ (m ³ / h), a pressure of 27 Pa, and an RF power of 200 W. In the case of UV treatment, the treatment is performed for 3 minutes using excimer UV (wavelength 172 nm) as a UV light source.
After applying activation energy to the plasma polymerized film, the alignment of the first glass substrate M1 and the second glass substrate M2 is adjusted, and the first glass substrate M1 and the second glass substrate M2 are stacked via the plasma polymerized film. In addition, a load of 98 (N), for example, is applied to the joint portion for 10 minutes. Thereby, the 1st glass substrate M1 and the 2nd glass substrate M2 are joined.
4 and 5 show an example in which one fixed substrate 51 and one movable substrate 52 are formed from the first glass substrate M1 and the second glass substrate M2, respectively. A plurality of fixed substrates 51 may be formed from the glass substrate M1, and a plurality of movable substrates 52 may be formed from one second glass substrate M2. In this case, after the substrate bonding step S3, the plurality of wavelength variable interference filters 5 are separated from each other by cutting predetermined positions of the first glass substrate M1 and the second glass substrate M2.

[Operational effects of the first embodiment]
The tunable interference filter 5 of the present embodiment includes a fixed substrate 51 (first glass substrate) in which the surfaces of the opposing surface 51A and the outer surface 51B are precisely polished to have an arithmetic average roughness Ra of less than 1 nm in the fixed substrate forming step S1. For M1), the first etching process is performed up to the groove depth of the reflective film installation part 512. At this time, by performing the etching process for about 1 hour without providing a drying process in between, the arithmetic average of the first reflective film region A1 which is the protruding tip surface is formed simultaneously with the formation of the reflective film installation part 512. The roughness Ra is made larger (rougher) than the outer surface 51B including the first light transmission region A2 (roughening step). Thereafter, after forming the electrode arrangement groove 511 and the wiring groove, the fixed reflection film 54 is formed in the first reflection film region A1 (reflection film formation step).
Similarly, in the movable substrate forming step S2, the second surface is compared with the movable substrate 52 (second glass substrate M2) in which the facing surface 52A and the outer surface 52B are precisely polished and the arithmetic average roughness Ra is less than 1 nm. The reflective film region A3 is etched to make the arithmetic average roughness Ra a rough surface having a thickness of 2 to 3 nm (roughening step). Thereafter, the movable reflective film 55 is formed on the second reflective film region A3 (reflective film step).
That is, in the wavelength tunable interference filter 5 of the present embodiment, the first reflective film region A1 of the fixed substrate 51 has an arithmetic average roughness Ra larger (rougher) than the first light transmission region A2, and the first reflective film region. A fixed reflective film 54 is provided on A1. The second reflective film region A3 of the movable substrate 52 has an arithmetic average roughness Ra larger (rougher) than the second light transmission region A4, and the movable reflective film 55 is provided on the second reflective film region A3. Yes.

  Thereby, in this embodiment, compared with the case where the fixed reflective film 54 and the movable reflective film 55 are provided on the optical surface, the fixed reflective film 54 and the movable reflective film 55 are respectively attached to the fixed substrate 51 and the movable substrate 52 with high adhesion. Can be provided. Therefore, the film alteration of the reflective films 54 and 55, generation of hillocks and whiskers can be suppressed, and light having a desired wavelength can be emitted from the wavelength variable interference filter 5 with high spectral accuracy. Further, in the substrates 51 and 52, the light transmission regions A2 and A4, which are light passage surfaces other than the reflection film regions A1 and A3, have smaller (fine) arithmetic average roughness Ra than the reflection film regions A1 and A3. In this embodiment, the optical surface is such that the arithmetic average roughness Ra of these light transmission regions A2 and A4 is less than 1 nm. As a result, light scattering and the like in the light transmission regions A2 and A4 are suppressed, and a decrease in light amount due to this is also suppressed. As described above, light of a desired target wavelength can be emitted from the wavelength variable interference filter 5 with high spectral accuracy and high light intensity.

  In the present embodiment, since the reflective films 54 and 55 are covered with the protective films 541 and 551, a metal film with low deterioration resistance such as an Ag film or an Ag alloy film is used as the reflective films 54 and 55. Even in this case, film alteration (for example, oxidation) due to environmental changes can be suppressed. Further, as described above, since the reflective films 54 and 55 are provided on the substrates 51 and 52 with high adhesion, even if film stress from the protective films 541 and 551 is applied, hillocks and whiskers are generated. Can be suppressed.

  In the present embodiment, the reflection film regions A1 and A3 are formed on a rough surface having an arithmetic average roughness Ra of 1 nm or more and 8 nm or less. Here, when the arithmetic average roughness Ra is less than 1 nm, an optical surface is formed, and hillocks and whiskers are generated in the reflection films 54 and 55, and the spectral accuracy of the wavelength variable interference filter 5 is lowered. In addition, when the arithmetic average roughness Ra is larger than 8 nm, Ag atoms are likely to be aggregated due to surface irregularities, and film alteration, hillocks, whiskers, etc. are promoted. As a result, the filter characteristics deteriorate (for example, increase in light loss). On the other hand, in the present embodiment, the arithmetic average roughness Ra as described above can suppress the generation of hillocks and whiskers while suppressing the deterioration of the filter characteristics. Accuracy can be increased.

In the present embodiment, the arithmetic average roughness Ra is set to a desired roughness by controlling the etching time for the first glass substrate M1 in the roughening step of the fixed substrate forming step S1. In this case, for example, as compared with the case where a plurality of types of etching solutions having different compositions are used, one type of etching solution may be used, and the manufacturing cost can be reduced. Further, the arithmetic average roughness Ra of the etched surface can be easily adjusted as compared with the case where the composition and concentration of the etching solution are changed, and the reflection film regions A1 and A3 having the desired arithmetic average roughness Ra can be easily formed. Can be formed.
In addition, in the fixed substrate forming step S1, the first reflective film region A1, which is the protruding tip surface, can be roughened simultaneously with the formation of the reflective film installation portion 512, so that the shape of the fixed substrate 51 is shaped. Later, the number of processes can be reduced and manufacturing efficiency can be improved as compared with the case where a separate roughening step is performed.

[Modification of First Embodiment]
In the first embodiment, the example in which the etching process is used in the roughening step is shown, but the present invention is not limited to this.
FIG. 6 is a schematic view showing the shape of the substrate at each step included in the fixed substrate forming step.
In the present modification, as in the first embodiment, as shown in FIG. 6A, the facing surface 51A and the outer surface 51B of the first glass substrate M1 are precisely polished. Next, as shown in FIG. 6B, by performing a plurality of etching treatments and drying treatments, an electrode arrangement groove 511, a reflective film installation portion 512, and a wiring that have an arithmetic average roughness Ra of less than 1 nm. A groove (not shown) is formed.

In this modification, after that, for example, a polishing process is performed on the protruding tip surface of the reflective film installation portion 512, and the arithmetic average roughness Ra is, for example, 1 nm or more as shown in FIG. A first reflective film region A1 having a rough surface of 8 nm or less is formed (roughening step).
As the polishing treatment, for example, a polishing pad such as a nonwoven fabric or polyurethane foam having cerium oxide abrasive grains (primary particle average particle size 0.05 μm, secondary particle average particle size about 0.5 μm) provided on the surface is used. The reflective film regions A1 and A3 are polished with a load of 100 gf / cm ² and a rotational speed of 80 rpm. In this case, the arithmetic average roughness Ra of the reflection film regions A1 and A3 can be set to about 1.5 nm. Further, the arithmetic average roughness Ra can be appropriately adjusted by changing the cerium oxide abrasive grains and the processing conditions (load and speed).
Thereafter, as in the first embodiment, after forming the fixed electrode 561 and the fixed extraction electrode 563 as shown in FIG. 6D, the reflective film forming step is performed as shown in FIG. 6E. Then, the fixed reflective film 54 is formed on the first reflective film region A1.

  The same applies to the movable substrate forming step S2, and in the first embodiment, the etching process is performed as the roughening step. However, by performing the polishing process as described above, the surface of the second reflective film region A3 is performed. May be roughened.

  Further, the polishing process performed in the roughening step is not limited to the one using the above polishing pad. For example, a blasting process may be performed as a polishing process. As the blasting treatment, for example, the reflective film regions A1 and A3 are roughened by spraying abrasive grains such as cerium oxide abrasive grains having an average grain diameter of 0.05 μm. The arithmetic average roughness Ra can be adjusted as appropriate by controlling the air flow rate and the like.

[Second Embodiment]
Next, a second embodiment according to the present invention will be described.
In the first embodiment described above, the reflective film regions A1 and A3 having a larger arithmetic average roughness Ra than the light transmission regions A2 and A4 are obtained by directly processing the surfaces of the substrates 51 and 52 (glass substrates M1 and M2). Formed. In contrast, in the second embodiment, the reflective film region A1, which has a larger arithmetic average roughness Ra than the light transmission regions A2, A4, without processing the surfaces of the substrates 51, 52 (glass substrates M1, M2). It differs from the first embodiment in that A3 is formed.
FIG. 7 is a cross-sectional view showing a schematic configuration of the variable wavelength interference filter 5A of the present embodiment. In the following description, the same reference numerals are given to the configurations already described, and the description thereof is omitted or simplified.

In the wavelength tunable interference filter 5A of the present embodiment, as shown in FIG. 7, a plurality of coarse areas having an area smaller than the area of the fixed reflection film 54 are formed on the first reflection film region A1 of the reflection film installation portion 512 of the fixed substrate 51. The surface forming bodies 514 are scattered, and the rough surface forming bodies 514 make the arithmetic average roughness Ra of the first reflective film region A1 1 nm or more and 8 nm or less.
Similarly, a plurality of rough surface forming bodies 526 are scattered on the second reflective film region A3 of the movable portion 521 of the movable substrate 52, and the arithmetic operation of the second reflective film region A3 is performed by these rough surface forming bodies 526. The average roughness Ra is 1 nm or more and 8 nm or less.

The rough surface forming body 514 as described above is formed as follows.
FIG. 8 is a diagram illustrating a state of the fixed substrate in the roughening step and the electrode forming step included in the fixed substrate forming step in the present embodiment.
In the present embodiment, as shown in FIGS. 6A and 6B described above, the facing surface 51A and the outer surface 51B of the first glass substrate M1 are precisely polished, and a plurality of etching processes and drying processes are performed. By carrying out, the electrode arrangement groove 511, the reflective film installation part 512, and the wiring groove that have an arithmetic average roughness Ra of less than 1 nm are formed.
Thereafter, as shown in FIG. 8A, an electrode material for forming a fixed electrode 561 and a fixed extraction electrode 563 (not shown) on the facing surface 51A of the first glass substrate M1 is deposited by vapor deposition or sputtering. A rough surface forming layer 566 is formed by using a method or the like (rough surface forming layer film forming step).
The electrode material for forming the rough surface forming layer 566 is made of, for example, any one of Cr, W, Ti, and ITO or an alloy material mainly containing any one of Cr, W, Ti, and ITO. That is, as an electrode material for forming the rough surface forming layer 566, a conductive layer having good adhesion to the first glass substrate M1 can be used. Further, Au or the like may be further laminated on the rough surface forming layer 566.

Thereafter, a resist Re is applied to the first glass substrate M1, and as shown in FIG. 8 (B), the resist Re is patterned in accordance with the shapes of the fixed electrode 561 and the fixed extraction electrode 563 using a photolithography method. .
Next, as shown in FIG. 8C, the rough surface forming layer 566 is patterned by wet etching to form the fixed electrode 561 and the fixed extraction electrode 563, and then the resist Re is removed. In this embodiment, at the time of this wet etching, simultaneously with the formation of the fixed electrode 561 and the fixed extraction electrode 563, a part of the rough surface forming layer 566 is left in the first reflective film region A 1 to form a plurality of rough surface forming bodies 514. Form.
Here, by using the rough surface forming layer 566 having high adhesion, a plurality of portions of the rough surface forming layer 566 can be easily scattered without using a separate mask or the like when the rough surface forming layer 566 is etched. It becomes possible to make it remain. Moreover, the thickness dimension of the rough surface forming body 514 becomes sufficiently smaller than the layer thickness of the rough surface forming layer 566 during the etching process, and the arithmetic average roughness Ra can be set to 1 nm or more and 8 nm or less.
As described above, in this embodiment, the roughening step is simultaneously performed by the electrode formation step.
Thereafter, the fixed substrate 51 is formed by performing the reflective film forming step as in the first embodiment.

  The same applies to the movable substrate forming step S2, and in the electrode forming step, a part of the conductive layer is formed as a rough surface forming layer and a part thereof is left to form the rough surface forming body 526. it can.

[Operational effects of the second embodiment]
In the present embodiment, in the rough surface forming layer film forming step, a rough surface forming layer 566 made of an electrode material is formed on the substrates 51 and 52 (glass substrates M1 and M2). Then, the rough surface forming layer 566 is etched according to the electrode shape, so that a part of the rough surface forming layer 566 is scattered on the reflective film regions A1 and A3, and the rough surface forming body 514 is left. , 526.
The reflection film regions A1 and A3 formed in this way are rough surfaces having an arithmetic average roughness Ra of 1 nm or more and 8 nm or less because a plurality of rough surface forming bodies 514 and 526 are scattered on the surface. Therefore, the reflective films 54 and 55 can be formed on the reflective film regions A1 and A3 with high adhesion, and generation of hillocks and whiskers can be suppressed.
In the present embodiment, the reflective film regions A1 and A3 can be roughened simultaneously when forming the electrode shape, and the electrode forming step and the roughening step can be performed simultaneously. For this reason, compared with the case where an electrode formation step and a roughening step are each implemented as a separate process, the number of processes can be reduced and the improvement of manufacturing efficiency can be aimed at.

[Third embodiment]
Next, a third embodiment according to the present invention will be described.
In the first embodiment described above, the reflective film regions A1 and A3 having a larger arithmetic average roughness Ra than the light transmission regions A2 and A4 are obtained by directly processing the surfaces of the substrates 51 and 52 (glass substrates M1 and M2). Formed. On the other hand, in the third embodiment, the reflective film regions A1, A3 having a larger arithmetic average roughness Ra than the light transmission regions A2, A4 are provided by providing a layer having a rough surface on the substrates 51, 52. It differs from the first embodiment in that it is formed.

FIG. 9 is a cross-sectional view showing a schematic configuration of the variable wavelength interference filter 5B of the present embodiment.
In the wavelength tunable interference filter 5B of this embodiment, as shown in FIG. 9, a surface roughening layer 515 is provided on the protruding front end surface of the reflective film installation portion 512 of the fixed substrate 51. In the surface roughening layer 515, the surface facing the movable substrate 52 is a rough surface having an arithmetic average roughness Ra of 1 nm or more and 8 nm or less, and constitutes the first reflective film region A1.
Similarly, a surface roughening layer 527 is provided in a region facing the fixed reflection film 54 in the central region of the facing surface 52A of the movable portion 521 of the movable substrate 52. In the surface roughened layer 527, the surface facing the fixed substrate 51 is a rough surface having an arithmetic average roughness Ra of 1 nm or more and 8 nm or less, and constitutes the second reflective film region A3.

The surface roughening layer 515 as described above is formed as follows.
FIG. 10 is a diagram illustrating a state of the fixed substrate in the roughening step included in the fixed substrate forming step in the present embodiment.
In this embodiment, first, each process of FIG. 6 (A) and FIG. 6 (B) in the fixed board | substrate formation step of the modification of 1st Embodiment mentioned above is implemented. That is, the opposing surface 51A and the outer surface 51B of the first glass substrate M1 are precisely polished, and a plurality of etching treatments and drying treatments are performed, whereby the electrode arrangement groove 511 having an arithmetic average roughness Ra of less than 1 nm, the reflection A film installation part 512 and a wiring groove are formed.
Thereafter, a surface roughened layer 515 is formed on the opposing surface 51A of the first glass substrate M1 by sputtering or the like, and as shown in FIG. The surface roughening layer 515 is removed. Here, as the surface roughening layer 515, for example, Ti, SiO ₂ , Al ₂ O ₃ or the like can be used. Further, the thickness dimension of the surface roughened layer 515 is, for example, 3 nm.

Next, as shown in FIG. 10B, O ₂ plasma treatment is performed on the surface of the roughened surface layer 515. Thereby, irregularities are formed on the surface of the surface roughening layer 515 to be roughened.
At this time, as in the second embodiment, the first reflective film region having an arithmetic average roughness Ra larger than that of the first light transmission region A2 by leaving the surface roughened layer 515 to be partly scattered. A1 may be formed.
Thereafter, similarly to the first embodiment, the fixed substrate 51 is formed by performing the electrode forming step and the reflective film forming step. Here, in this embodiment, since the surface of the surface roughened layer 515 is roughened by the O ₂ plasma treatment, the surface of the surface roughened layer 515 is in an oxidized state. For this reason, in the reflective film formation step, the fixed reflective film 54 can be formed on the first reflective film region A1 with higher adhesion.

The same applies to the movable substrate forming step S2, and in the roughening step, a surface roughening layer 527 is formed in a region facing the fixed reflective film 54, and the surface is subjected to O ₂ plasma treatment. Thereby, the surface of the surface roughening layer 527 can be roughened, and the second reflective film region A3 is formed.

[Operational effects of the third embodiment]
In the present embodiment, in the roughening step, surface roughening layers 515 and 527 are formed on the substrates 51 and 52 (glass substrates M1 and M2), and the surfaces are roughened by O ₂ plasma treatment.
As a result, similar to the first embodiment, reflection film areas A1 and A3 having an arithmetic average roughness Ra larger than the light transmission areas A2 and A4 are formed, and the reflection film areas A1 and A3 are formed on the reflection film areas A1 and A3. The reflective films 54 and 55 can be formed with high adhesion, and generation of hillocks and whiskers can be suppressed.
In the present embodiment, the surface of the surface roughening layers 515 and 527 is roughened by O ₂ plasma treatment, so that the reflective film regions A1 and A3 are in an oxidized state. For this reason, in the reflective film formation step, the reflective films 54 and 55 can be formed with higher adhesion.

[Fourth embodiment]
Next, a fourth embodiment according to the present invention will be described.
In the fourth embodiment, an example of an optical module (spectrometer) and electronic device (printer) in which the wavelength variable interference filter 5 described in the first to third embodiments is incorporated will be described with reference to the drawings.

[Schematic configuration of printer]
FIG. 11 is a diagram illustrating an external configuration example of the printer 10 according to the fourth embodiment. FIG. 12 is a block diagram illustrating a schematic configuration of the printer 10 according to the present embodiment.
As shown in FIG. 11, the printer 10 includes a supply unit 11, a transport unit 12, a carriage 13, a carriage moving unit 14, and a control unit 15 (see FIG. 12). The printer 10 controls the units 11, 12, 14 and the carriage 13 based on print data input from an external device 20 such as a personal computer, and prints an image on the medium A. Further, the printer 10 of the present embodiment forms a color patch for color measurement at a predetermined position on the medium A based on preset print data for calibration, and performs spectral measurement on the color patch. As a result, the printer 10 compares the actual measurement value for the color patch with the calibration print data to determine whether or not the printed color has color misregistration. To correct the color.
Hereinafter, each configuration of the printer 10 will be specifically described.

The supply unit 11 is a unit that supplies the medium A to be image formed to the image forming position. The supply unit 11 includes, for example, a roll body 111 (see FIG. 11) around which the medium A is wound, a roll drive motor (not shown), a roll drive wheel train (not shown), and the like. Then, based on a command from the control unit 15, the roll drive motor is rotationally driven, and the rotational force of the roll drive motor is transmitted to the roll body 111 via the roll drive wheel train. As a result, the roll body 111 rotates and the paper surface wound around the roll body 111 is supplied downstream (+ Y direction) in the Y direction (sub-scanning direction).
In the present embodiment, an example in which the paper surface wound around the roll body 111 is supplied is shown, but the present invention is not limited to this. For example, the medium A may be supplied by any supply method such as supplying the medium A such as a sheet of paper loaded on a tray or the like one by one with a roller or the like.

The transport unit 12 transports the medium A supplied from the supply unit 11 along the Y direction. The transport unit 12 includes a transport roller 121, a transport roller 121, a driven roller (not shown) that is driven by the transport roller 121, and a platen 122.
The conveyance roller 121 is driven by a conveyance motor (not shown), and when the conveyance motor is driven under the control of the control unit 15, the conveyance roller 121 is rotationally driven by the rotation force, and the medium A is moved between the conveyance roller 121 and the driven roller. It is transported along the Y direction while being sandwiched. A platen 122 facing the carriage 13 is provided on the downstream side (+ Y side) in the Y direction of the transport roller 121.

The carriage 13 includes a printing unit 16 that prints an image on the medium A, and a spectroscope 17 that performs spectroscopic measurement at a predetermined measurement position R (see FIG. 12) on the medium A.
The carriage 13 is provided by a carriage moving unit 14 so as to be movable along a main scanning direction intersecting with the Y direction.
Further, the carriage 13 is connected to the control unit 15 by a flexible circuit 131, and performs a printing process by the printing unit 16 and a spectroscopic measurement process by the spectroscope 17 based on a command from the control unit 15.
The detailed configuration of the carriage 13 will be described later.

The carriage moving unit 14 constitutes a moving mechanism in the present invention, and reciprocates the carriage 13 along the X direction based on a command from the control unit 15.
The carriage moving unit 14 includes, for example, a carriage guide shaft 141, a carriage motor 142, and a timing belt 143.
The carriage guide shaft 141 is disposed along the X direction, and both ends are fixed to, for example, a casing of the printer 10. The carriage motor 142 drives the timing belt 143. The timing belt 143 is supported substantially parallel to the carriage guide shaft 141, and a part of the carriage 13 is fixed. When the carriage motor 142 is driven based on a command from the control unit 15, the timing belt 143 travels forward and backward, and the carriage 13 fixed to the timing belt 143 is guided by the carriage guide shaft 141 and reciprocates.

Next, the configuration of the printing unit 16 and the spectroscope 17 provided on the carriage 13 will be described with reference to the drawings.
[Configuration of Printing Unit 16]
The printing unit 16 forms an image on the medium A by ejecting ink onto the medium A individually at a portion facing the medium A.
The printing unit 16 is detachably mounted with ink cartridges 161 corresponding to a plurality of colors of ink, and ink is supplied from each ink cartridge 161 to an ink tank (not shown) via a tube (not shown). . Further, nozzles (not shown) for ejecting ink droplets are provided on the lower surface of the printing unit 16 (position facing the medium A) corresponding to each color. For example, piezo elements are arranged in these nozzles, and by driving the piezo elements, ink droplets supplied from the ink tank are ejected and land on the medium A to form dots.

[Configuration of spectrometer]
FIG. 13 is a cross-sectional view showing a schematic configuration of the spectrometer 17.
The spectroscope 17 is an optical module according to the present invention, and includes a light source unit 171, an optical filter device 172, a light receiving unit 173, and a light guide unit 174 as shown in FIG. 13.
The spectroscope 17 emits illumination light from the light source unit 171 to the measurement position R on the medium A, and causes the light component reflected at the measurement position R to be incident on the optical filter device 172 by the light guide unit 174. Then, the optical filter device 172 emits (transmits) light having a predetermined wavelength from the reflected light and causes the light receiving unit 173 to receive the light. The optical filter device 172 can select a transmission wavelength based on the control of the control unit 15, and measure the light amount of each wavelength of visible light to perform spectroscopic measurement of the measurement position R on the medium A. Is possible.

[Configuration of light source section]
The light source unit 171 includes a light source 171A and a light collecting unit 171B. The light source unit 171 irradiates the light emitted from the light source 171A into the measurement position R of the medium A from the normal direction with respect to the surface of the medium A.
The light source 171A is preferably a light source that can emit light of each wavelength in the visible light region. As such a light source 171A, for example, a halogen lamp, a xenon lamp, a white LED, and the like can be exemplified, and in particular, a white LED that can be easily installed in a limited space in the carriage 13 is preferable. The condensing unit 171B is configured by, for example, a condensing lens and condenses light from the light source 171A at the measurement position R. In FIG. 13, the condensing unit 171B displays only one lens (condensing lens), but may be configured by combining a plurality of lenses.

[Configuration of optical filter device]
The optical filter device 172 includes a housing 6 and a wavelength variable interference filter 5 housed inside the housing 6. The housing 6 has a housing space inside, and the wavelength variable interference filter 5 is housed in the housing space. The housing 6 has terminal portions connected to the electrode pads 564 </ b> P and 565 </ b> P of the wavelength variable interference filter, and the terminal portions are connected to the control unit 15. Based on a command signal from the control unit 15, a predetermined voltage is applied to the electrostatic actuator 56 of the wavelength tunable interference filter 5, whereby light having a wavelength corresponding to the applied voltage is emitted from the wavelength tunable interference filter 5. Is done.
In the present embodiment, an example in which the wavelength variable interference filter 5 described in the first embodiment is provided in the housing 6 is shown. However, the wavelength variable interference filters 5A and 5B are provided in the housing 6. Also good.

[Configuration of light receiving unit and light guiding optical system]
Returning to FIG. 13, the light receiving unit 173 is disposed on the optical axis of the wavelength tunable interference filter 5 and receives light transmitted through the wavelength tunable interference filter 5. The light receiving unit 173 outputs a detection signal (current value) corresponding to the amount of received light based on the control of the control unit 15. The detection signal output by the light receiving unit 173 is input to the control unit 15 via an IV converter (not shown), an amplifier (not shown), and an AD converter (not shown).
The light guide unit 174 includes a reflecting mirror 174A and a band pass filter 174B.
The light guide unit 174 reflects the light reflected at 45 ° with respect to the surface of the medium A at the measurement position R onto the optical axis of the wavelength variable interference filter 5 by the reflecting mirror 174A. The band-pass filter 174B transmits light in the visible light range (for example, 380 nm to 720 nm) and cuts ultraviolet light and infrared light. As a result, light in the visible light region is incident on the wavelength variable interference filter 5, and light having a wavelength selected by the wavelength variable interference filter 5 in the visible light region is received by the light receiving unit 173.

[Control unit configuration]
The control unit 15 is a control unit of the present invention, and includes an I / F 151, a unit control circuit 152, a memory 153, and a CPU (Central Processing Unit) 154 as shown in FIG. Yes.
The I / F 151 inputs print data input from the external device 20 to the CPU 154.
The unit control circuit 152 includes control circuits for controlling the supply unit 11, the transport unit 12, the printing unit 16, the light source 171A, the variable wavelength interference filter 5, the light receiving unit 173, and the carriage moving unit 14, respectively. The operation of each unit is controlled based on the command signal. The control circuit of each unit may be provided separately from the control unit 15 and connected to the control unit 15.

The memory 153 stores various programs and various data for controlling the operation of the printer 10.
As various data, for example, V-λ data indicating the wavelength of light transmitted through the variable wavelength interference filter 5 with respect to the voltage applied to the electrostatic actuator 56 when controlling the variable wavelength interference filter 5, and print data For example, print profile data that stores the ejection amount of each ink with respect to the included color data. Moreover, the light emission characteristic (light emission spectrum) with respect to each wavelength of the light source 171A, the light reception characteristic (light reception sensitivity characteristic) with respect to each wavelength of the light receiving unit 173, and the like may be stored.

  The CPU 154 reads out and executes various programs stored in the memory 153, thereby driving the supply unit 11, the transport unit 12, and the carriage moving unit 14, printing control of the printing unit 16, and measurement control (wavelength control) by the spectrometer 17. Performs drive control of the electrostatic actuator 56 of the variable interference filter 5, light reception control of the light receiving unit 173), color measurement processing based on the spectroscopic measurement result using the spectroscope 17, and correction (update) processing of print profile data. To do.

[Operational effects of this embodiment]
The spectroscope 17 of this embodiment includes the wavelength variable interference filter 5 described in the first to third embodiments, and a light receiving unit 173 that receives light transmitted through the wavelength variable interference filter 5.
Here, the wavelength tunable interference filter 5 includes the reflection films 54 and 55 provided in the reflection film areas A1 and A3 having a larger arithmetic average roughness Ra than the light transmission areas A2 and A4, and has high adhesion. Since the substrates 51 and 52 are in close contact with each other, generation of hillocks and whiskers is suppressed. Therefore, the wavelength tunable interference filter 5 can transmit the light of the target wavelength with sufficient light intensity with high spectral accuracy, and the light receiving unit 173 receives the light to perform spectral analysis on the color patch to be measured. Measurement can be performed with high accuracy.

  Further, the printer 10 according to the present embodiment performs color measurement processing on a color patch or the like according to the spectroscopic measurement result measured by the spectroscope 17, and updates the print profile data according to the result. At this time, as described above, since the spectroscope 17 can perform high-precision spectroscopic measurement, accurate chromaticity with respect to the color patch can be measured, and the print profile data is updated based on the measurement result. By (correcting), the color reproduced by the user can be faithfully printed on the medium A by the printing unit 16.

[Other Embodiments]
It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, in the first embodiment, first, after etching the first glass substrate M1 to the depth of the reflection film installation portion 512, the etching processing was performed to the depth of the electrode placement groove 511 and the wiring groove. On the other hand, for example, the electrode placement groove 511 and the wiring groove are first formed by masking the areas other than the electrode placement groove 511 and the wiring groove region to form the electrode placement groove 511 and the wiring groove. The reflective film installation portion 512 may be formed by performing an etching process while masking this region. In this case, when forming the reflective film installation part 512, as in the first embodiment, for example, by performing one etching process without a drying process over a long period of time, the arithmetic average roughness It is possible to form the first reflective film region A1 in which Ra is 1 nm or more and 8 nm or less.

In the first embodiment, the example in which the arithmetic average roughness Ra of the reflective film regions A1 and A3 is controlled by controlling the etching time during the etching process has been described. However, the present invention is not limited to this. For example, the arithmetic average roughness Ra may be controlled by changing the composition or concentration of the etching solution or etching gas used for the etching process. For example, even when a buffered hydrofluoric acid aqueous solution containing more than 20.2 wt% NH ₄ HF _{2 and} more than 21.2 wt% NH ₄ F is used, etching and drying are repeated. The arithmetic average roughness Ra of the surface can be increased.

In 2nd embodiment, although the example using the same electrode material as the electrodes 561 and 562 was shown as the rough surface formation bodies 514 and 526, it is not limited to this.
A material different from the electrodes 561 and 562 (for example, a Ti film) is formed in a region where the reflective films 54 and 55 are provided to form a rough surface forming layer, and a part of the rough surface forming layer remains to form a plurality of rough surfaces. The arithmetic average roughness Ra of the reflection film regions A1 and A3 may be made rougher than the arithmetic average roughness Ra of the light transmission regions A2 and A4 by performing an etching process so as to be scattered as a surface forming body.

In the third embodiment, the O ₂ plasma treatment is exemplified in the roughening step of roughening the surfaces of the surface roughening layers 515 and 527, but the present invention is not limited to this. For example, as in the first embodiment or a modification of the first embodiment, an etching process or a polishing process (mechanical polishing process, blast process, etc.) may be performed.

  In the first to third embodiments, the wavelength variable interference filter 5 capable of changing the size of the gap G between the reflection films 54 and 55 by the electrostatic actuator 56 is exemplified as the interference filter. However, the present invention is not limited to this. For example, the present invention can be applied to a wavelength-fixed interference filter that transmits only a predetermined wavelength.

In the first to third embodiments, the fixed reflective film 54 is provided on the fixed substrate 51, the movable reflective film 55 is provided on the movable substrate 52, and the reflective films 54 and 55 on the substrates 51 and 52 are provided. Although the example in which the areas A1 and A3 have the arithmetic average roughness Ra larger than the light transmission areas A2 and A4 has been shown, the present invention is not limited to this. For example, only one of the first reflection film region A1 and the second reflection film region A3 may have a configuration in which the arithmetic average roughness Ra is larger than that of the light transmission regions A2 and A4. In this case, hillocks and whiskers may occur in either one of the reflection films 54 and 55, but spectral accuracy is higher than when hillocks and whiskers are generated in both the pair of reflection films 54 and 55. Can be suppressed.
In addition, either the fixed reflection film 54 or the movable reflection film 55 may be configured not to be provided on the substrate. For example, the fixed reflective film 54 is provided in the first reflective film region A1 of the fixed substrate 51, and the movable reflective film 55 is opposed to the fixed reflective film 54 via a gap G via a spacer or the like, for example. Also good. That is, a configuration in which the movable substrate 52 is not provided may be used.

In the fourth embodiment, the printer 10 is exemplified as the electronic apparatus of the present invention. However, the optical module and the electronic apparatus of the present invention can be applied in various other fields.
For example, the electronic device of the present invention may be used in an optical-based system for detecting the presence of a specific substance. As such a system, for example, an in-vehicle gas leak detector that detects a specific gas with high sensitivity by adopting a spectroscopic measurement method using the optical module of the present invention, a photoacoustic rare gas detector for a breath test, etc. Examples of the gas detection device can be exemplified. Other examples of systems for detecting the presence of specific substances include non-invasive measurement equipment for saccharides by near-infrared spectroscopy and non-invasive measurement equipment for information on food, living organisms, minerals, etc. it can.
Furthermore, for example, by changing the intensity of light of each wavelength over time, it is also possible to transmit data using light of each wavelength. In this case, a specific wavelength is provided by a wavelength variable interference filter provided in the optical module. The light transmitted by the light having a specific wavelength can be extracted by separating the light of the light and receiving the light by the light receiving unit. Optical communication can also be carried out by processing the light data of each wavelength with an electronic device equipped with such a data extraction optical module.
Furthermore, as an electronic device, the present invention can be applied to a spectroscopic camera, a spectroscopic analyzer, or the like that captures a spectroscopic image by spectrally separating light with the optical module of the present invention.
In addition, the optical module of the present invention may be used as a bandpass filter. For example, only light in a narrow band centered on a predetermined wavelength out of light in a predetermined wavelength range emitted from a light emitting element may be used as a wavelength variable interference filter. It can also be used as an optical laser device for spectroscopic transmission.
Furthermore, the optical module of the present invention may be used as a biometric authentication device. For example, the optical module can be applied to authentication devices such as blood vessels, fingerprints, retinas, and irises using light in the near infrared region or visible region.

  As described above, the optical module and the electronic apparatus of the present invention can be applied to any device that separates predetermined light from incident light. And since the optical module of this invention can disperse | distribute a some wavelength with one device as mentioned above, the measurement of the spectrum of a some wavelength and the detection with respect to a some component can be implemented accurately. Therefore, compared with the conventional apparatus which extracts a desired wavelength by a plurality of devices, it is possible to promote downsizing of the optical module and the electronic apparatus, and for example, it can be suitably used as a portable or in-vehicle optical device.

  In addition, the specific structure for carrying out the present invention can be appropriately changed to other structures and the like within a range in which the object of the present invention can be achieved.

  5, 5A, 5B: Wavelength variable interference filter (interference filter), 10: Printer (electronic device), 16: Printing unit, 17: Spectrometer (optical module), 51: Fixed substrate, 51A: Opposing surface (first surface) ), 51B ... Outer surface (second surface), 52 ... Movable substrate, 52A ... Opposite surface (first surface), 52B ... Outer surface (second surface), 54 ... Fixed reflective film, 55 ... Movable reflective film, 56 ... Electrostatic actuator, 173 ... Light receiving part, 512 ... Reflective film installation part, 514 ... Rough surface forming body, 515 ... Surface roughening layer, 521 ... Movable part, 522 ... Holding part, 526 ... Rough surface forming body, 527 ... Surface roughening layer, 541 ... protective film, 551 ... protective film, 561 ... fixed electrode, 562 ... movable electrode, 563 ... fixed extraction electrode, 564 ... movable extraction electrode, 565 ... fixed connection electrode, 566 ... rough surface forming layer, A1 ... first reflective film region, A2 ... Ikko transmissive region, A3 ... second reflecting film region, A4 ... second light transmitting region, G ... gap.

Claims (14)

A pair of reflective films;
A substrate on which any one of the pair of reflective films is provided,
The substrate includes a first surface provided with a reflective film region on which one of the pair of reflective films is provided, a surface opposite to the first surface, and viewed from a normal direction to the first surface. In plan view, the second surface including a light transmission region overlapping the reflective film region,
The interference filter, wherein the reflective film region has an arithmetic average roughness larger than that of the light transmission region. The interference filter according to claim 1,
The interference filter, wherein the surface of the reflective film region is dotted with a plurality of rough surface forming bodies smaller than the area of the reflective film in the plan view. The interference filter according to claim 1,
The reflective film region has a surface roughening layer disposed to cover the first surface,
The surface roughening layer, the surface has a larger arithmetic average roughness than the light transmission region,
Any one of the pair of reflective films is provided on the surface of the surface roughening layer. The interference filter according to any one of claims 1 to 3,
The arithmetic average roughness in the reflective film region is 1 nm or more and 8 nm or less. The interference filter according to any one of claims 1 to 4,
An optical module comprising: a light receiving unit that receives light emitted from the interference filter. An optical module according to claim 5;
A control unit for controlling the optical module;
An electronic device characterized by comprising: A first surface having a reflective film region in which any one of the pair of reflective films is provided, and a substrate on which any one of the pair of reflective films is provided; And a second surface including a light transmission region that overlaps with the reflective film region in a plan view as viewed from a normal direction to the first surface on a surface opposite to the first surface. A method,
A roughening step of roughening a reflective film region for forming the reflective film of the substrate so that an arithmetic mean roughness is rougher than that of the light transmission region;
A reflective film forming step of forming any one of the pair of reflective films on the reflective film region;
The manufacturing method of the interference filter characterized by implementing. In the manufacturing method of the interference filter according to claim 7,
In the roughening step, the reflective film region of the substrate is roughened by performing an etching process. In the manufacturing method of the interference filter according to claim 7,
In the roughening step, the reflective film region of the substrate is roughened by performing a polishing process. In the manufacturing method of the interference filter according to claim 7,
A rough surface forming layer forming step of forming a rough surface forming layer on the substrate;
In the roughening step, the rough surface forming layer that overlaps the reflective film region in a plan view when the substrate is viewed from the thickness direction of the substrate is etched, and a part of the rough surface forming layer is formed by the etching process. A method of manufacturing an interference filter, wherein the surface is roughened by forming a plurality of rough surface forming bodies on the substrate. In the manufacturing method of the interference filter of Claim 10,
The rough surface forming layer is a conductive layer for forming an electrode,
In the roughening step, the etching process is performed by masking the formation position of the electrode. In the manufacturing method of the interference filter according to claim 10 or claim 11,
The rough surface forming layer is made of any one of Cr, W, Ti, and ITO, or an alloy material mainly containing any one of Cr, W, Ti, and ITO. . In the manufacturing method of the interference filter according to claim 7,
In the roughening step, a surface roughening layer is formed in a region covering at least the reflective film region of the substrate, and the surface of the surface roughening layer is roughened. . In the manufacturing method of the interference filter according to claim 13,
In the roughening step, the surface of the roughened layer is roughened by performing O ₂ plasma treatment on the roughened surface.

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