JP5565446B2 - Optical device and method for manufacturing optical device - Google Patents

Description

The present invention relates to a manufacturing how optical devices and optical devices.

A wavelength tunable filter (Optical Tunable Filter) is known as one that separates only light having a specific wavelength from light having a plurality of wavelengths (see, for example, Patent Document 1).
For example, in the wavelength tunable filter according to Patent Document 1, a substrate having a plate shape and having a movable portion that can be displaced in the thickness direction is bonded to a substrate having a recess for allowing displacement of the movable portion. Has been. Reflective films are respectively formed on the bottom surface of the concave portion and the surface of the movable portion facing the concave portion. When light is incident between the pair of reflective films, the light is incident between them. Only light having a wavelength corresponding to the distance is emitted (wavelength separation).

In particular, in the wavelength tunable filter, the two substrates described above are each formed of silicon, but the movable portion has a main body having an opening, and a transparent plate such as glass provided to close the opening of the main body. The light can enter and exit through the transparent plate. Therefore, such a wavelength tunable filter can perform wavelength separation even for light in the visible light region.
However, in the wavelength tunable filter according to Patent Document 1, it is difficult to accurately join the transparent plate to the main body of the movable part, and the productivity is difficult. Therefore, it is difficult to reduce the cost of such a wavelength tunable filter.

JP 2006-235606 A

An object of the present invention is to provide while achieving cost reduction, manufacturing how optical device and an optical device a wavelength separation can be performed with high accuracy in a visible light region.

Such an object is achieved by the present invention described below.
The optical device of the present invention has a plate-like first glass substrate including a movable portion provided so as to be displaceable in the thickness direction,
A second glass substrate bonded to the first glass substrate and having a gap that enables the displacement between the movable portion and the movable portion;
A first reflective film provided on a surface of the movable part facing the second glass substrate;
A second reflective film provided on the second glass substrate so as to face the first reflective film;
Have
The light reflection is repeated between the first reflection film and the second reflection film to cause interference, and the wavelength according to the distance between the first reflection film and the second reflection film is increased. An optical device configured to emit light to the outside,
A first drive electrode provided on a surface of the movable part facing the second glass substrate;
A second drive electrode provided on the second glass substrate so as to face the first drive electrode;
A first metal film provided on the first glass substrate and having the same constituent material and layer configuration as the first drive electrode;
A second metal film provided on the second glass substrate and having the same constituent material and layer configuration as the second drive electrode;
Have
The first glass substrate and the second glass substrate are joined by joining the first metal film and the second metal film by metal bonding , and the first drive electrode and the second glass substrate By applying a voltage between the second drive electrode and generating an electrostatic attractive force between them, the movable part is displaced,
The gap between the first reflective film and the second reflective film is narrower than the gap between the first drive electrode and the second drive electrode .

Thereby, a 1st glass substrate and a 2nd glass substrate can be joined simply and firmly. Therefore, while achieving cost reduction, it is possible to perform wavelength separation in the visible light region with high accuracy.

In the optical device of the present invention, a first reflective film provided on a surface of the movable part facing the second glass substrate;
A second reflective film provided on the second glass substrate so as to face the first reflective film;
Have
The light incident between the first reflective film and the second reflective film is caused to interfere, and a wavelength corresponding to the distance between the first reflective film and the second reflective film is selected. It is preferable that it is comprised .
In the optical device of the present invention, it is preferable that the first glass substrate and the second glass substrate contain alkali metal ions.
Thereby, the bonding strength between the first glass substrate and the first metal film and the bonding strength between the second glass substrate and the second metal film can be improved.

In the optical device of the present invention, the first metal film provided on the first glass substrate and the second metal film provided on the second glass substrate are bonded by surface activation bonding. Is preferred.
Thereby, the 1st glass substrate and the 2nd glass substrate can be joined easily and firmly via the 1st metal film and the 2nd metal film.
In the optical device of the present invention, a recess for forming the gap is formed in the second glass plate,
The second reflective film is preferably provided at the bottom of the recess.

The optical device manufacturing method of the present invention is a method of manufacturing the optical device of the present invention,
And forming said first metal film and the first driving electrode by processing the first metal film formed on a substrate for forming the first glass substrate, said second glass a first step of forming a second metal film and the second driving electrode by processing the second metal film formed on a substrate to form a substrate,
And a second step of forming the metal layer by bonding the first metal film and the second metal film by bonding between metals.
Thereby, an optical device capable of performing wavelength separation in the visible light region with high accuracy can be provided.

In the method for producing an optical device of the present invention, it is preferable that the first metal film and the second metal film are bonded by surface activated bonding.
Thereby, the 1st glass substrate and the 2nd glass substrate can be joined easily and firmly via the 1st metal film and the 2nd metal film .
In the optical device manufacturing method of the present invention, it is preferable that each of the first metal film and the second metal film is composed of a plurality of metal layers having different constituent materials.
Thereby, desired characteristics can be imparted to each of the first metal film and the second metal film. For example, the metal layer on the first substrate side of the first metal film is made of a material having excellent adhesion to the first substrate, and the first metal film is bonded to the second metal film. The metal layer is made of a material suitable for bonding with the second metal film (material suitable for surface activated bonding). Similarly to this, the metal layer on the second substrate side of the second metal film is made of a material having excellent adhesion to the second substrate, and the second metal film is formed with the first metal film. The metal layer on the bonding side is made of a material suitable for bonding with the first metal film (material suitable for surface activated bonding). By configuring the first metal film and the second metal film in this manner, the mechanical strength of the optical device can be improved.

In the optical device manufacturing method of the present invention, in the first step, the metal film formed on the second substrate is processed to form a mask made of metal, and the mask is formed. And obtaining the second structure body by etching the second substrate, and processing the mask to form the second metal film and the second drive electrode. It is preferable.
Thereby, the manufacturing process can be simplified and the cost of the optical device can be reduced.

It is a top view which shows embodiment of the optical device (wavelength variable filter) of this invention. It is a top view which shows the wavelength variable filter shown in FIG. It is the sectional view on the AA line in FIG. It is a figure for demonstrating the 2nd structure with which the optical device shown in FIG. 1 was equipped. It is a figure for demonstrating the manufacturing method of the optical device shown in FIG. It is a figure for demonstrating the manufacturing method of the optical device shown in FIG. It is a figure for demonstrating the manufacturing method of the optical device shown in FIG. It is a figure for demonstrating the manufacturing method of the optical device shown in FIG. It is a figure which shows embodiment of a wavelength tunable filter module provided with the optical device of this invention. It is a figure which shows embodiment of an optical spectrum analyzer provided with the optical device of this invention.

Hereinafter will be described in detail with reference to preferred embodiments illustrating the manufacturing how optical devices and optical devices of the present invention in the accompanying drawings.
FIG. 1 is a plan view showing an embodiment of an optical device (tunable wavelength filter) of the present invention, FIG. 2 is a cross-sectional view taken along line AA in FIG. 1, and FIG. 3 is provided in the optical device shown in FIG. It is a figure for demonstrating a 2nd structure. In the following description, the front side of the page in FIG. 1 and FIG. 3 is referred to as “up”, the back side of the page is referred to as “down”, the right side is referred to as “right”, and the left side is referred to as “left”. Is called "upper", the lower side is called "lower", the right side is called "right", and the left side is called "left".

As shown in FIGS. 1 to 3, the optical device 1 is, for example, a wavelength tunable filter that receives light and emits only light (interference light) corresponding to a specific wavelength among the wavelengths of the light by interference action. is there. The optical device 1 is not limited to a wavelength tunable filter, and can be used for various optical devices such as an optical switch and an optical attenuator.
Such an optical device 1 has a first structure 2 and a second structure 3 bonded to each other, and a gap (first gap G1) for causing light to interfere is formed between them. Has been. When the light L enters the gap, only light having a wavelength corresponding to the size of the gap is emitted due to the interference action.

Hereinafter, each part which comprises the optical device 1 is demonstrated in detail sequentially.
The first structure 2 is light transmissive. The first structure 2 includes a movable portion 21 for making the first gap G1 variable, a support portion 22, and the movable portion 21 with respect to the support portion 22 in the vertical direction (that is, the thickness of the movable portion 21). And a plurality of connecting portions 23 for connecting them so as to be displaceable in the direction). These are integrally formed by forming an opening 24 having a different shape in the first structure 2. When the movable part 21, the support part 22, and the connecting part 23 are integrally formed, the position of the movable part 21 with respect to the second structure 3 can be further stabilized.

The constituent material of the first structure 2 is not particularly limited as long as it has light transmittance with respect to the wavelength of light to be used. For example, soda glass, crystalline glass, quartz glass, lead glass, Examples thereof include various glasses such as potassium glass, borosilicate glass, sodium borosilicate glass, and alkali-free glass, and crystals.
Among these, as a constituent material of the first structure 2, glass containing an alkali metal (mobile ion) such as sodium (Na) or potassium (K) is preferable. Thereby, the adhesiveness and joining strength of the 1st structure 2 and the metal layer 4 mentioned later can be improved, and these can be joined simply and firmly at the time of manufacture.
Further, when the first structure 2 is made of glass as a main material, the dimensional accuracy and mechanical characteristics of the movable portion 21 can be improved while enabling use in the visible light region.

The movable portion 21 has a plate shape and is located in a substantially central portion of the first structure 2 in a plan view and has a circular shape. Needless to say, the shape, size, and arrangement of the movable portion 21 are not particularly limited to the illustrated shapes.
The thickness (average) of the movable portion 21 is appropriately selected according to the constituent material, application, and the like, and is not particularly limited, but is preferably about 1 to 500 μm, and more preferably about 10 to 100 μm.
Further, the movable portion 21 has a first reflective film (HR coating) that reflects light with a relatively high reflectance on the surface facing the second structure 3 (that is, the lower surface of the movable portion 21). ) 25 is formed, and the first antireflection film (AR coating) that suppresses reflection of light on the surface opposite to the side facing the second structure 3 (that is, the upper surface of the movable portion 21). 26 is formed.

As shown in FIG. 2, the first reflective film 25 reflects light incident on a first gap G <b> 1 (described later) from below the optical device 1 a plurality of times with the second reflective film 34 (described later). Is for.
As shown in FIG. 2, the first antireflection film 26 reflects light incident on the first gap G1 from below the optical device 1 downward in the figure at the interface between the upper surface of the first structure 2 and the outside air. It is for preventing it from being done.

  The first reflective film (dielectric multilayer film) 25 and the first antireflection film 26 are not particularly limited as long as necessary optical characteristics can be obtained, but those composed of a dielectric multilayer film are preferable. . That is, each of the first reflective film (dielectric multilayer film) 25 and the first antireflection film 26 is preferably formed by alternately laminating a plurality of high refractive index layers and low refractive index layers. . Thereby, loss of light at the time of interference of light between the first reflective film 25 and the second reflective film 34 can be prevented, and optical characteristics can be improved.

The material constituting the high refractive index layer is not particularly limited as long as it can obtain the optical characteristics necessary for the first reflective film 25 and the first antireflection film 26. When used in the external light region, Ti ₂ O, Ta ₂ O ₅ , niobium oxide, etc. may be mentioned. When used in the ultraviolet light region, Al ₂ O ₃ , HfO ₂ , ZrO ₂ , ThO _2, etc. Is mentioned.
The material constituting the low refractive index layer is not particularly limited as long as it can obtain the optical characteristics necessary for the first reflective film 25 and the first antireflection film 26. For example, MgF ₂ , Examples thereof include SiO ₂ .
The number and thickness of the high refractive index layer and the low refractive index layer constituting the first reflective film 25 and the first antireflective film 26 are set according to the required optical characteristics. In general, when a reflective film is composed of a multilayer film, the number of layers required to obtain its optical characteristics is 12 or more, and when an antireflection film is composed of a multilayer film, the number of layers necessary for the optical characteristics is About 4 layers.

The first drive electrode 28 has an annular shape so as to surround the outer periphery of the first reflective film 25 described above.
The first drive electrode 28 is connected to an energization circuit (not shown), and can generate a potential difference between a second drive electrode 33 and a first drive electrode 28 described later. The energization circuit is connected to a control means (not shown) for controlling driving of the energization circuit based on a detection result of a detection circuit (not shown) described later.

The constituent material of the first drive electrode 28 is not particularly limited as long as it has conductivity, and examples thereof include metals such as Au, Cr, Al, Al alloy, Ni, Zn, and Ti. Can be mentioned.
Here, the first drive electrode 28 has the same layer configuration as a first metal film 41 described later. Therefore, when the first metal film 41 is composed of a plurality of metal layers, each metal layer is composed of the same constituent material as the constituent material of the first drive electrode 28 described above. The constituent materials may be the same or different between the layers.
The thickness (average) of the first drive electrode 28 is appropriately selected depending on the constituent material, application, and the like and is not particularly limited, but is preferably about 0.1 to 5 μm.
A support portion 22 is formed so as to surround such a movable portion 21, and the movable portion 21 is supported by the support portion 22 via a connecting portion 23.

  A plurality (four in the present embodiment) of the connecting portions 23 are provided at equal intervals in the circumferential direction around the movable portion 21 described above. The connecting portion 23 has elasticity (flexibility), whereby the movable portion 21 is spaced substantially in parallel with the second structure 3 in the thickness direction (up and down). ) Is displaceable. The number, position, and shape of the connecting portions 23 are not limited to those described above as long as the movable portion 21 can be displaced with respect to the support portion 22.

The first structure 2 is provided with an opening 27 for accessing an extraction electrode 331 described later from the outside. The opening 27 serves as a pressure release opening that prevents a pressure difference from the outside from occurring in the space between the first structure 2 and the second structure 3 in the manufacturing process of the optical device 1. Also works.
Further, the first structure 2 is provided with an opening 29 for accessing the extraction electrode 281 described above from the outside.
The second structure 3 is joined to such a first structure 2 on the lower surface of the support portion 22.

  The second structural body 3 has light transmissivity, and the second structural body 3 is provided on one surface side between the first structural body 2 and the second structural body 3. In order to form the first gap G1 between the first structure 2 and the second structure 3 inside the first recess 31 for forming the second gap G2 and inside the first recess 31. The second recess 32 is formed. Thereby, the 2nd structure 3 and the 1st structure 2 can be joined, forming the space | gap which accept | permits the displacement in the thickness direction of the movable part 21. FIG.

The constituent material of the second structure 3 is not particularly limited as long as it has light transmittance with respect to the wavelength of light to be used. For example, soda glass, crystalline glass, quartz glass, lead glass, Examples thereof include various glasses such as potassium glass, borosilicate glass, sodium borosilicate glass, and alkali-free glass, and crystals. In particular, as a constituent material of the second structure 3, soda glass, potassium glass, sodium borosilicate glass, or the like is preferably used. For example, Pyrex glass (registered trademark) manufactured by Corning, Inc. is preferably used.
Among these, as a constituent material of the second structure 3, glass containing an alkali metal (mobile ion) such as sodium (Na) or potassium (K) is preferable. Thereby, the adhesiveness and joining strength of the 2nd structure 3 and the metal layer 4 mentioned later can be improved, and these can be joined simply and firmly at the time of manufacture.

Further, when the second structural body 3 is made of glass as a main material, the dimensional accuracy of the first concave portion 31 and the second concave portion 32 and mechanical characteristics can be obtained while enabling use in the visible light region. Can be improved. When the dimensional accuracy of the first concave portion 31 and the second concave portion 32 is excellent, the dimensional accuracy of the first gap G1 and the second gap G2 is also excellent.
In particular, the difference between the thermal expansion coefficient of the first structure 2 and the thermal expansion coefficient of the second structure 3 is preferably as small as possible, specifically, 50 × 10 ⁻⁷ ° C. ⁻¹ or less. Is preferred.
This reduces the stress generated between the first structure 2 and the second structure 3 when the first structure 2 and the second structure 3 are exposed to a high temperature or a low temperature. Thus, damage to the first structure 2 or the second structure 3 can be prevented.

From such a viewpoint, the constituent material of the second structure 3 is preferably the same type as the constituent material of the first structure 2.
The thickness (average) of the second structure 3 is appropriately selected depending on the constituent material, application, etc., and is not particularly limited, but is preferably about 10 to 2000 μm, more preferably about 100 to 1000 μm. preferable.

  The first concave portion 31 has a circular outer shape, and is disposed at a position corresponding to the movable portion 21, the connecting portion 23, and the opening portion 24 described above. On the bottom surface of the first recess 31, an annular second drive electrode 33 and an insulating film (not shown) are laminated in this order at a position corresponding to the outer peripheral portion of the movable portion 21.

The second drive electrode 33 is connected to an energization circuit (not shown), and a potential difference can be generated between the second drive electrode 33 and the first drive electrode 28 described above. The energization circuit is connected to a control means (not shown) for controlling driving of the energization circuit based on a detection result of a detection circuit (not shown) described later.
The constituent material of the second drive electrode 33 is not particularly limited as long as it has conductivity like the constituent material of the first drive electrode 28 described above. For example, Au, Cr, Examples thereof include metals such as Al, Al alloy, Ni, Zn, and Ti.
Here, the second drive electrode 33 has the same layer configuration as a second metal film 42 (mask layer 7) described later. Therefore, when the second metal film 42 is composed of a plurality of metal layers, each metal layer is composed of the same material as that of the second drive electrode 33 described above. The constituent materials may be the same or different between the layers.

The thickness (average) of the second drive electrode 33 is appropriately selected depending on the constituent material, application, and the like, and is not particularly limited, but is preferably about 0.1 to 5 μm.
A second gap G <b> 2 is formed as an electrostatic gap (drive gap) for driving the movable portion 21 in the space in the first recess 31. That is, the second gap G <b> 2 is formed between the first drive electrode 28 and the second drive electrode 33.

The size of the second gap G2 (that is, the distance between the first drive electrode 28 and the second drive electrode 33) is appropriately selected according to the application, and is not particularly limited. It is preferably about 20 μm.
The second concave portion 32 has a circular outer shape, is substantially concentric with the first concave portion 31 described above, and has an outer diameter smaller than the outer diameters of the first concave portion 31 and the movable portion 21. A second reflecting film 34 having a substantially circular shape is provided on the bottom surface of the second recess 32 (the surface of the second structure 3 on the movable portion 21 side).

As described above, the second reflective film 34 reflects light incident on the first gap G1 from below the optical device 1 with the first reflective film 25 a plurality of times as shown in FIG. It is for making it happen. That is, the second reflective film 34 cooperates with the first reflective film 25 described above, and the size of the first gap G1 (that is, the second reflective film 34 and the first reflective film 25 and Light having a wavelength corresponding to the distance between the two. In the present embodiment, the size of the first gap G1 is larger than the size of the second gap G2 described above. Note that the first gap G1 and the second gap G2 are determined by the design of the wavelength range used, the driving voltage, and the like, and the relationship between the first gap G1 and the second gap G2 is the present embodiment. For example, when the used wavelength region is visible light, the first gap G1 may be smaller than the second gap G2.
The magnitude | size of the 1st gap G1 is suitably selected according to a use etc., Although it does not specifically limit, It is preferable that it is about 0.4-100 micrometers.

Since the second reflective film 34 is provided on the bottom surface of the second recess 32, the second reflective electrode 34 is provided regardless of the distance between the second drive electrode 33 and the first drive electrode 28 or the movable portion 21. The usable wavelength band can be set in accordance with the depth of the concave portion 32. Therefore, the drive voltage can be reduced even if the optical device 1 having various use wavelength bands is manufactured.
As shown in FIG. 3, the second structure 3 includes a third recess 36, a third recess 36, and a first recess in order to pull out the second drive electrode 33 described above. A groove portion 35 that communicates with 31 is formed.

The depth of the groove 35 and the third recess 36 is substantially the same as the depth of the first recess 31, and an extraction electrode 331 connected to the second drive electrode 33 is provided on the bottom of these grooves 35 and the third recess 36. Is provided.
The constituent material of the extraction electrode 331 can be the same as the constituent material of the second drive electrode 33 described above, and is not particularly limited as long as it has conductivity. For example, Au , Cr, Al, Al alloy, Ni, Zn, Ti, and other metals.

Further, the thickness (average) of the extraction electrode 331 is appropriately selected depending on the constituent material, application, and the like, and is not particularly limited, but is preferably about 0.1 to 5 μm. The extraction electrode 331 is preferably formed integrally with the second drive electrode 33 described above.
A second antireflection film 37 is formed on the other surface of the second structure 3 (that is, the surface opposite to the surface on which the first concave portion 31 and the like are formed). (See FIG. 2).

As shown in FIG. 2, the second antireflection film 37 is formed in the lower part of the figure at the interface between the lower surface of the second structure 3 and the outside air. This is for preventing reflection. The configuration of the first reflection film 25 and the first antireflection film 26 is the same as the configuration of the second reflection film 34 and the second antireflection film 37 described above.
The first structure 2 and the second structure 3 as described above are bonded via the metal layer 4.

  The metal layer 4 includes a first metal film 41 bonded to the lower surface of the first structure 2 and a second metal film 42 bonded to the upper surface of the first second structure 3. The first metal film 41 and the second metal film 42 are bonded to each other by surface activation bonding. That is, in the metal layer 4, the first metal film 41 bonded to the first structure 2 and the second metal film 42 bonded to the second structure 3 are bonded to each other by surface activation bonding. It has been made. Thereby, in the manufacturing process to be described later, the first structure 2 and the second structure 3 can be easily and firmly bonded via the metal layer 4. The surface activated bonding will be described later in detail.

As the constituent materials of the first metal film 41 and the second metal film 42, the same constituent materials as those of the first drive electrode 28 and the second drive electrode 33 described above can be used, respectively.
In particular, the constituent material of the first metal film 41 is preferably the same type as the constituent material of the second metal film 42. Thereby, the 1st metal film 41 and the 2nd metal film 42 can be joined simply and firmly.

  The constituent material of the first metal film 41 is preferably the same type as that of the first drive electrode 28, and the constituent material of the second metal film 42 is preferably the same type as that of the second drive electrode 33. In other words, the constituent material of the metal layer 4 is preferably the same type as the constituent material of the first drive electrode 28 and / or the second drive electrode 33. Thereby, the first metal film 41 and the first drive electrode 28 can be formed integrally, and the second metal film 42 and the second drive electrode 33 can be formed integrally. Therefore, the cost can be further reduced.

  Moreover, it is preferable that the first metal film 41 and the second metal film 42 each include a plurality of metal layers having different constituent materials. Thereby, desired characteristics can be imparted to each of the first metal film 41 and the second metal film 42. For example, the metal layer on the first structure 2 side of the first metal film 41 is made of a material having excellent adhesion to the first structure 2 and the second metal of the first metal film 41 is formed. The metal layer on the bonding side with the film 42 is made of a material suitable for bonding with the second metal film 42 (material suitable for surface activated bonding). Similarly, the metal layer on the second structure 3 side of the second metal film 42 is made of a material having excellent adhesion to the second structure 3, and the second metal film 42 is made of the second metal film 42. The metal layer on the bonding side with the first metal film 41 is made of a material suitable for bonding with the first metal film 41 (material suitable for surface activated bonding). By configuring the first metal film 41 and the second metal film 42 in this way, the mechanical strength of the optical device 1 can be improved.

The operation (action) of the optical device 1 having such a configuration will be described.
When a voltage is applied between the first drive electrode 28 and the second drive electrode 33 by an energization circuit (not shown), the first drive electrode 28 and the second drive electrode 33 are charged with opposite polarities. Thus, a Coulomb force (electrostatic attractive force) is generated between the two. At this time, a detection circuit (not shown) detects the displacement state of the movable portion 21, and based on the detection result, a control means (not shown) controls driving of the energization circuit.

Due to the Coulomb force, the movable portion 21 moves (displaces) downward toward the second drive electrode 33 and stops at a position where the elastic force of the connecting portion 23 and the Coulomb force are balanced. Thereby, the magnitude | size of the 1st gap G1 and the 2nd gap G2 changes.
On the other hand, as shown in FIG. 2, when the light L is irradiated from below the optical device 1 toward the first gap G1, the light L is emitted from the second antireflection film 37, the second structure 3, and the second structure 3. The light passes through the second reflective film 34 and enters the first gap G1. At this time, the light L is incident on the first gap G1 by the second antireflection film 37 with almost no loss.
The incident light is repeatedly reflected (interfered) between the first reflective film 25 and the second reflective film 34. At this time, the loss of the light L can be suppressed by the first reflective film 25 and the second reflective film 34.

  As described above, the first gap between the first reflective film 25 and the second reflective film 34 in the process in which light is repeatedly reflected between the first reflective film 25 and the second reflective film 34. Light having a wavelength that does not satisfy the interference condition corresponding to the magnitude of G1 is rapidly attenuated, and only light having a wavelength that satisfies the interference condition remains and is finally emitted from the optical device 1. Therefore, if the first gap G1 is changed (that is, the interference condition is changed) by changing the voltage applied between the first drive electrode 28 and the second drive electrode 33, the optical device 1 is changed. The wavelength of transmitted light can be changed.

As a result of the interference of the light L, light having a wavelength corresponding to the size of the first gap G1 (interference light) passes through the first reflective film 25, the movable portion 21, and the first antireflection film 26, The light is emitted above the optical device 1. At this time, since the first antireflection film 26 is formed on the upper surface of the movable portion 21, the light is emitted to the outside of the optical device 1 with almost no loss.
In the present embodiment, the light incident on the first gap G1 is emitted upward of the optical device 1. However, the light incident on the first gap G1 may be emitted downward of the optical device 1.
In the present embodiment, light is incident on the optical device 1 from below, but light may be incident from above.

In the optical device 1 as described above, the first structure 2 and the second structure 3 are joined via the metal layer 4 composed of metal as a main material, and the metal layer 4 is used as a conductor. By applying a voltage between the first drive electrode 28 and the second drive electrode 33, an electrostatic attractive force is generated between them to displace the movable portion 21.
Therefore, as will be described later, the first structure 2 and the second structure 3 can be easily and firmly joined to each other while being made of a transparent material such as glass. Therefore, wavelength separation in the visible light region can be performed with high accuracy while reducing costs.
In addition, since a voltage can be applied between the first drive electrode 28 and the second drive electrode 33 using the metal layer 4 as a conductor, there is no need to separately provide a structure for wiring or the like. Cost reduction can be achieved.

<Manufacturing method of optical device (tunable wavelength filter)>
Next, an example of the manufacturing method of the optical device 1 will be described with reference to FIGS.
4-8 is a figure for demonstrating the manufacturing process of the optical device 1. FIG. 4 to 8 show cross sections corresponding to the cross section taken along the line AA of FIG.
In the manufacturing method of the optical device 1 of the present embodiment, [A] a second process is performed by forming a metal film on the second substrate for forming the second structure 3 and processing the metal film. Forming the metal film 42 and the second drive electrode 33, [B] forming a metal film on the first substrate for forming the first structure 2, and processing the metal film The step of forming the first metal film 41 and the first drive electrode 28 by the first step (first step) and [C] joining the first metal film 41 and the second metal film 42 to form a metal A step of forming the layer 4 (second step). Hereinafter, each process will be described sequentially.

[A] Step of Forming Second Metal Film 42 and Second Drive Electrode 33 -A1-
First, as a substrate for forming the second structure 3, a second substrate 5 having light transmittance is prepared as shown in FIG.
As the second substrate 5, a substrate having a uniform thickness and having no deflection or scratch is preferably used. As the constituent material of the second substrate 5, those described in the description of the second structure 3 can be used. As described above, as the constituent material of the second substrate 5, it is preferable to use glass containing an alkali metal (mobile ion) such as sodium (Na) or potassium (K).

-A2-
Next, as shown in FIG. 4B, a mask layer 6 is formed (masked) on one surface of the second substrate 5.
Examples of the material constituting the mask layer 6 include metals such as Au / Cr, Au / Ti, Pt / Cr, and Pt / Ti, silicon such as polycrystalline silicon (polysilicon) and amorphous silicon, and silicon nitride. It is done. When silicon is used as the constituent material of the mask layer 6, the adhesion between the mask layer 6 and the second substrate 5 is improved. When a metal is used for the constituent material of the mask layer 6, the visibility of the mask layer 6 to be formed is improved.

The thickness of the mask layer 6 is not particularly limited, but is preferably about 0.01 to 1 μm, and more preferably about 0.09 to 0.11 μm. If the mask layer 6 is too thin, the second substrate 5 may not be sufficiently protected. If the mask layer 6 is too thick, the mask layer 6 may be easily peeled off due to internal stress of the mask layer 6.
The mask layer 6 can be formed by, for example, a chemical vapor deposition method (CVD method), a sputtering method, a vapor deposition method such as a vapor deposition method, a plating method, or the like.

-A3-
Next, as shown in FIG. 4C, an opening 61 having a plan view shape corresponding to the plan view shapes of the first recess 31, the groove 35, and the third recess 36 is formed in the mask layer 6. .
More specifically, first, for example, using a photolithography method, a photoresist is applied on the mask layer 6, and exposure and development are performed to form a resist mask having an opening corresponding to the opening 61. Next, the mask layer 6 is etched through this resist mask to remove a part of the mask layer 6, and then the resist mask is removed. In this way, an opening 61 is formed in the mask layer 6. As this etching, for example, dry etching with CF gas, chlorine-based gas, etc., wet etching with hydrofluoric acid + nitric acid aqueous solution, alkaline aqueous solution or the like can be used.

-A4-
Next, after etching one surface of the second substrate 5 through the mask layer 6, the mask layer 6 is removed, and as shown in FIG. A third recess 36 is formed.
As this etching, a dry etching method or a wet etching method can be used, but a wet etching method is preferably used. Thereby, the 1st recessed part 31 formed can be made into a more ideal column shape. In this case, for example, a hydrofluoric acid-based etchant is preferably used as the etchant for wet etching. Moreover, when alcohol (especially polyhydric alcohol), such as glycerol, is added to etching liquid, the bottom face of the 1st recessed part 31 formed can be made very smooth.

The method for removing the mask layer 6 is not particularly limited. For example, wet etching using an alkaline aqueous solution (for example, tetramethylammonium hydroxide aqueous solution), hydrochloric acid + nitric acid aqueous solution, hydrofluoric acid + nitric acid aqueous solution, CF gas, or chlorine-based gas. For example, dry etching or the like can be used.
In particular, when wet etching is used as a method for removing the mask layer 6, the mask layer 6 can be efficiently removed by a simple operation.

-A5-
Next, by using the same method as in steps A2 and A3 described above, as shown in FIG. 5A, the mask layer 7 having an opening in a plan view corresponding to the plan view in the second recess 32 is formed. Form.
This mask layer 7 is made of metal as a main material, and is used as an etching mask in step A6 to be described later, and then processed in step A7 to form the second drive electrode 33 and the second metal film 42. It will be. Therefore, the mask layer 7 is preferably composed of a plurality of metal layers having different constituent materials. Thereby, desired characteristics can be imparted to each of the second metal films 42. For example, the metal layer on the second substrate 5 side of the second metal film 42 is made of a material having excellent adhesion to the second substrate 5 and the first metal film 41 of the second metal film 42. The metal layer on the bonding side is made of a material suitable for bonding to the first metal film 41 (material suitable for surface activated bonding). By configuring the second metal film 42 in this way, the mechanical strength of the optical device 1 can be improved.
-A6-
Next, the second substrate 5 is etched through the mask layer 7 by using the same method as in the step A4 described above to form the second recess 32 as shown in FIG. 5B.

-A7-
Next, as shown in FIG. 5C, unnecessary portions of the mask layer 7 are removed by photolithography and etching, and the second drive electrode 33, the extraction electrode 331, and the second metal film 42 are formed. An insulating film (not shown) is formed on the second drive electrode 33.
As a method for removing unnecessary portions of the mask layer 7, a method similar to the above-described step A3 can be used.

  Thus, in this step, the metal film formed on the second substrate 5 is processed to form a mask layer 7 (mask) made of metal, and the mask layer 7 (mask) is interposed. A step of obtaining the second structure 3 by etching the second substrate 5, and a step of processing the mask layer 7 (mask) to form the second metal film 42 and the second drive electrode 33. Have Thereby, a manufacturing process can be simplified and cost reduction of the optical device 1 can be achieved.

-A8-
Next, as shown in FIG. 5D, a second reflective film 34 is formed on the bottom surface of the second recess 32.
More specifically, the second reflective film 34 is formed by alternately laminating the high refractive index layer and the low refractive layer as described above on the bottom surface of the second recess 32.
As a method for forming the high refractive index layer and the low refractive index layer, for example, chemical vapor deposition (CVD) or physical chemical vapor deposition (PVD) is preferably used.

[B] Step of forming first metal film 41 and first drive electrode 28 -B1-
On the other hand, as shown in FIG. 6A, a light-transmitting first substrate 9 is prepared as a substrate for forming the first structure 2.
As the first substrate 9, a substrate having a uniform thickness and having no deflection or scratch is preferably used. As the constituent material of the first substrate 9, those described in the description of the first structure 2 can be used. As described above, as the constituent material of the first substrate 9, it is preferable to use glass containing an alkali metal (mobile ion) such as sodium (Na) or potassium (K).

-B2-
Next, as shown in FIG. 6B, the first reflective film 25, the first drive electrode 28, and the first metal film 41 are formed on one surface of the first substrate 9.
As a method of forming the first reflective film 25, the same method as the method of forming the second reflective film 34 described above can be used.
As a method for forming the first drive electrode 28 and the first metal film 41, the same method as the method for forming the second drive electrode 33 and the second metal film 42 described above can be used.

[C] Step of forming metal layer 4 -C1-
Next, as shown in FIG. 6C, the first metal film 41 formed on the first substrate 9 and the second structure 3 (second substrate 5) formed on the first substrate 9. The metal layer 4 is formed by joining the two metal films 42.
The bonding method between the first metal film 41 and the second metal film 42 is not particularly limited, but a metal bonding method is preferable, and a surface activated bonding method is particularly preferable.

In surface activated bonding, the surface to be bonded is surface-treated under reduced pressure (in a vacuum) to bring the atoms on the surface into an active state that facilitates chemical bonding, and then bonded at a low temperature such as room temperature. Is to do.
More specifically, first, for example, the first substrate 9 on which the first metal film 41 is formed, and the second substrate 5 (second structure 3) on which the second metal film 42 is formed. And put them together in a vacuum chamber. Then, in vacuum (under reduced pressure), the surface of the first metal film 41 opposite to the first substrate 9 (surface to be a bonding surface), and the second substrate 5 of the second metal film 42 Is sputtered with an ion beam, plasma, or the like on each of the opposite surfaces (surfaces to be bonded surfaces). At this time, on the surfaces to be the bonding surfaces of the first metal film 41 and the second metal film 42, contaminants and the like that hinder the bonding are removed, and atoms having bonds are exposed. It becomes a state. By bringing the surfaces in such a state into contact (pressure contact) at room temperature, the first metal film 41 and the second metal film 42 can be easily and firmly bonded.

By performing the bonding at such a normal temperature, it is possible to prevent the first structure body 2 and the second structure body 3 from being subjected to thermal distortion or thermal stress. As a result, the obtained optical device 1 has extremely excellent characteristics (high reliability).
In addition, since the heating time and the cooling time are unnecessary for bonding, the time required for manufacturing the optical device 1 can be shortened. As a result, even in this respect. Cost reduction of the optical device 1 can be achieved.

-C2-
Next, as shown in FIG. 7A, etching or polishing is performed to thin the first substrate 9.
-C3-
Next, as shown in FIG. 7B, the mask layer 10 is formed on the surface of the first substrate 9 opposite to the second structure 3 by using the same method as in the above-described step A2. Form.

-C4-
Next, as shown in FIG. 7C, openings having a shape corresponding to the opening 24 and the opening 29 are formed in the mask layer 10 by using the same method as in step A3 described above.
-C5-
Next, by using a dry etching method or the like, the first substrate 9 is etched through the mask layer 10 having the openings as described above, and as shown in FIG. Form.

-C6-
Next, as shown in FIG. 8B, a first antireflection film 26 is formed on the surface of the first structure 2 opposite to the second structure 3, and the first structure 2 The second antireflection film 37 is formed on the surface of the second structure 3 opposite to the first structure 2. Thereby, the optical device 1 is obtained.
As a method for forming the first antireflection film 26 and the second antireflection film 37, the same method as that for forming the second reflection film 34 described above can be used.

In the optical device 1 as described above, the first structure 2 and the second structure 3 are joined via the metal layer 4 composed of metal as a main material, and the metal layer 4 is used as a conductor. By applying a voltage between the first drive electrode 28 and the second drive electrode 33, an electrostatic attractive force is generated between them to displace the movable portion 21.
Thereby, the first structure 2 and the second structure 3 can be easily and firmly joined to each other while being made of a transparent material such as glass. Therefore, wavelength separation in the visible light region can be performed with high accuracy while reducing costs.
In addition, since a voltage can be applied between the first drive electrode 28 and the second drive electrode 33 using the metal layer 4 as a conductor, there is no need to separately provide a structure for wiring or the like. Cost reduction can be achieved.

The optical device 1 (wavelength variable filter) as described above is used in a form as shown in FIG. 9 or FIG. 10, for example.
9, FIG, 10 illustrates an embodiment of a tunable filter module comprising an optical device of the present invention is a diagram showing an embodiment of an optical spectrum analyzer comprising an optical device of the present invention.
A wavelength tunable filter module 100 shown in FIG. 9 is installed in an optical transmission path of an optical network such as a wavelength division multiplexing (WDM) optical transmission system. Such a wavelength tunable filter module 100 includes the optical device 1 that is the wavelength tunable filter described above, the optical fiber 101 and the lens 102 that guide light to the optical device 1, and the light emitted from the optical device 1 to the outside. A lens 103 and an optical fiber 104 are provided.

In such a wavelength tunable filter module 100, light having a plurality of wavelengths is incident on the optical device 1 through the optical fiber 101 and the lens 102, and only light having a desired wavelength is extracted through the lens 103 and the optical fiber 104. Can do.
Such a wavelength tunable filter module 100 can perform wavelength separation in the visible light region with high accuracy while reducing costs.

  An optical spectrum analyzer 200 shown in FIG. 10 is a device that measures the spectrum characteristics (relationship between wavelength and intensity) of the light to be measured. Such an optical spectrum analyzer 200 includes a light incident unit 201 into which measured light is incident, the optical device 1 described above, and an optical system 202 that guides the measured light incident on the light incident unit 201 to the optical device 1. The light receiving element 203 that receives the light emitted from the optical device 1, the optical system 204 that guides the light emitted from the optical device 1 to the light receiving element 203, the drive of the optical device 1, and the output of the light receiving element 203 The control unit 205 that obtains the spectrum characteristics based on the above and the display unit 206 that displays the calculation result of the control unit 205 are provided.

In such an optical spectrum analyzer 200, the light to be measured incident on the light incident portion 201 is incident on the optical device 1 via the optical system 202. Then, the light emitted from the optical device 1 is received by the light receiving element 203 via the optical system 204, and the intensity of the light is obtained by the control unit 205. At this time, the control unit 205 obtains the intensity of the light received by the light receiving element 203 while sequentially changing the interference condition of the optical device 1. Then, the control unit 205 causes the display unit 206 to display information about the light intensity at each wavelength (for example, a spectrum waveform).
Such an optical spectrum analyzer 200 can perform wavelength separation in the visible light region with high accuracy while reducing costs.
Further, by using the optical device 1 described above, a wavelength tunable light source or a wavelength tunable laser can be realized.

Although the manufacturing how optical devices and optical devices of the present invention has been described with reference to the illustrated embodiments, the present invention is not limited thereto, the configuration of the components, optionally with the same function It can be replaced with the configuration of In addition, any other component may be added to the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Wavelength tunable filter 2 ... 1st structure 21 ... Movable part 22 ... Support part 23 ... Connection part 24 ... Opening part 25 ... 1st reflection film 26 ... 1st reflection prevention Membrane 27... Opening 28... First drive electrode 281, 331... Extraction electrode 3... Second structure 31... First recess 32. Electrode 34... Second reflective film 35... Groove 36. Third recess 37... Second antireflection film 4... Metal layer 41... First metal film 42. 5 ... 2nd substrate 6, 7 ... Mask layer 61 ... Opening 9 ... 1st substrate 10 ... Mask layer 100 ... Wavelength variable filter module 101 ... Optical fiber 102, 103 ... Lens 104 ... ... optical fiber 200 ... optical spectrum analyzer 201 ...... Light incident part 202 ...... Optical system 203 ...... Light receiving element 204 ...... Optical system G1 ...... First gap G2 ...... Second gap L ...... Light

Claims (9)

A first glass substrate having a movable part provided in a plate shape and displaceable in the thickness direction;
A second glass substrate bonded to the first glass substrate and having a gap that enables the displacement between the movable portion and the movable portion;
A first reflective film provided on a surface of the movable part facing the second glass substrate;
A second reflective film provided on the second glass substrate so as to face the first reflective film;
Have
The light reflection is repeated between the first reflection film and the second reflection film to cause interference, and the wavelength according to the distance between the first reflection film and the second reflection film is increased. An optical device configured to emit light to the outside,
A first drive electrode provided on a surface of the movable part facing the second glass substrate;
A second drive electrode provided on the second glass substrate so as to face the first drive electrode;
A first metal film provided on the first glass substrate and having the same constituent material and layer configuration as the first drive electrode;
A second metal film provided on the second glass substrate and having the same constituent material and layer configuration as the second drive electrode;
Have
The first glass substrate and the second glass substrate are joined by joining the first metal film and the second metal film by metal bonding, and the first drive electrode and the second glass substrate By applying a voltage between the second drive electrode and generating an electrostatic attractive force between them, the movable part is displaced,
An optical device, wherein a gap between the first reflective film and the second reflective film is narrower than a gap between the first drive electrode and the second drive electrode. A first reflective film provided on a surface of the movable part facing the second glass substrate;
A second reflective film provided on the second glass substrate so as to face the first reflective film;
Have
The light incident between the first reflective film and the second reflective film is caused to interfere, and a wavelength corresponding to the distance between the first reflective film and the second reflective film is selected. The optical device according to claim 1, wherein the optical device is configured as follows.   The optical device according to claim 1, wherein the first glass substrate and the second glass substrate contain alkali metal ions.   The first metal film provided on the first glass substrate and the second metal film provided on the second glass substrate are bonded together by surface activation bonding. An optical device according to claim 1. The second glass plate has a recess for forming the gap ,
The optical device according to claim 1, wherein the second reflective film is provided on a bottom portion of the concave portion. A method for producing the optical device according to claim 1, comprising:
The first glass film and the first drive electrode are formed by processing a metal film formed on the first substrate for forming the first glass substrate, and the second glass is formed. A first step of forming the second metal film and the second drive electrode by processing a metal film formed on a second substrate for forming a substrate;
A method of manufacturing an optical device, comprising: a second step of forming the metal layer by bonding the first metal film and the second metal film by bonding of metals.   The method for manufacturing an optical device according to claim 6, wherein the first metal film and the second metal film are bonded by surface activated bonding.   The method for manufacturing an optical device according to claim 6, wherein each of the first metal film and the second metal film includes a plurality of metal layers having different constituent materials.   In the first step, the metal film formed on the second substrate is processed to form a mask made of metal, and the second substrate is etched through the mask. 9. The method according to claim 6, further comprising: obtaining the second structure body, and processing the mask to form the second metal film and the second drive electrode. Optical device manufacturing method.

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