JP2018124373A - Wavelength selection element and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wavelength selection element comprising two substrates that are reliably aligned and fixed to each other with a predetermined distance therebetween, and to provide a method of manufacturing the same.SOLUTION: A wavelength selection element comprises a pair of light-transmissive substrates 11 having principal surfaces that face each other with a gap therebetween; a pair of reflective films 12 formed on the opposing principal surfaces to face each other with an optical distance therebetween; a bonding section 13 designed to bond the pair of substrates together and made of a curable adhesive having a cured hardness that is less than that of the pair of substrates; and a contact section 14 at which the pair of substrates come into direct contact with each other to define the gap.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a wavelength selection element such as an optical filter and a manufacturing method thereof.

  For example, the optical filter is an optical element configured to selectively emit only light having a predetermined wavelength (wavelength band) from incident light. For example, a wavelength selection element such as an optical filter has a configuration in which a pair of reflective films facing each other are arranged. For example, the pair of reflective films are arranged with a gap therebetween. Further, the interval between the reflective films is set according to the wavelength of light to be extracted.

  For example, in Patent Literature 1, a movable plate having a first light reflecting portion is opposed to a first base body provided so as to be displaceable in the thickness direction, and the first light reflecting portion is opposed to an optical gap. An optical device having a second substrate provided with a second light reflecting portion is disclosed. Further, the first and second bases are bonded via a bonding film.

JP 2009-134025

  The interval between the reflecting films (optical gap) is closely related to the wavelength of the extracted light (electromagnetic wave), that is, the wavelength selection characteristic (filtering characteristic). In consideration of reliably extracting only electromagnetic waves having a specific wavelength, it is preferable that the optical gap between the reflective films is constant in the entire region within the film.

  Further, as described in Patent Document 1, for example, a technique is known in which a reflective film is formed on each of a plurality of (for example, two) substrates, and the substrates are bonded together to form an optical filter. In such a configuration, the accuracy of the optical gap is affected by the positional relationship between the substrates, for example, the parallelism of the two substrates.

  In order to improve the filtering characteristics, it is preferable that the substrates are fixed so that a desired optical gap is reliably formed. Moreover, it is preferable that the position between the substrates is reliably determined. In addition, for example, it is preferable that the substrates can be easily bonded to each other without requiring a complicated apparatus.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a wavelength selection element in which substrates are securely positioned and fixed at desired intervals and a method for manufacturing the same. It is another object of the present invention to provide a wavelength selection element having high wavelength selection characteristics and a method for manufacturing the same, in which substrates are fixed and easily positioned and fixed at desired intervals.

  According to the first aspect of the present invention, a pair of substrates having translucency and having main surfaces facing each other with a gap therebetween are formed on the main surfaces facing each other, and are opposed to each other at an optical distance. A pair of reflective films, a pair of substrates bonded to each other, a bonding portion made of a curable adhesive having a smaller hardness after curing than the pair of substrates, and a pair of bumps that directly contact each other to define a gap It is characterized by having.

  According to a ninth aspect of the invention, there is provided a first reflective film forming step of forming a first reflective film on the first main surface of the first substrate, and a second main surface having a recess. A second reflective film forming step of forming a second reflective film in the concave portion of the second substrate, and curing on the region outside the concave portion on the second main surface of the second substrate, which is harder than the first substrate; A coating process for coating a joining member made of a curable adhesive having a low hardness and a first main surface of the second main surface so that the first and second reflective films face each other at an optical distance. It has an abutting process of directly abutting on the main surface and a joining process of curing the joining member and joining the first and second substrates.

(A) is a schematic top view of the wavelength selection element according to the first embodiment, (b) is a cross-sectional view of the wavelength selection element according to the first embodiment, and (c) is the wavelength selection according to the first embodiment. It is a partial expanded sectional view in an element. FIG. 6 is a schematic operation explanatory diagram of the wavelength selection element according to the first embodiment. FIG. 4 is a diagram illustrating each step of the method for manufacturing the wavelength selective element according to the first embodiment. (A)-(d) is a figure which shows the manufacturing method of the wavelength selection element based on Example 1. FIG. (A) And (b) is typical sectional drawing of the wavelength selection element which concerns on Example 1 and its comparative example, respectively. (A) And (b) is the typical top view and sectional drawing of the wavelength selection element which concern on the modification of Example 1, respectively. (A) And (b) is the typical top view and sectional drawing of the wavelength selection element concerning Example 2, respectively. (A) And (b) is typical sectional drawing of the wavelength selection element which concerns on Example 2 and its comparative example, respectively.

  Examples of the present invention will be described in detail below.

  FIG. 1A is a diagram schematically illustrating the upper surface of the wavelength selection element 10 according to the first embodiment. FIG. 1B is a cross-sectional view of the wavelength selection element 10. FIG.1 (b) is sectional drawing along the VV line in Fig.1 (a). Moreover, FIG.1 (c) is a partial expanded sectional view which expands and shows the part enclosed with the broken line of FIG.1 (b). The configuration of the wavelength selection element 10 will be described with reference to FIGS. The wavelength selection element 10 is, for example, an optical filter.

  The wavelength selection element 10 includes a pair of translucent substrates (hereinafter, may be referred to as substrate pairs) 11 that face each other. The substrate pair 11 is made of, for example, quartz, borosilicate glass, silicon, or the like. Further, as shown in FIG. 1B, the substrate pair 11 has a structure in which a first substrate 11A and a second substrate 11B each having a flat plate shape are arranged to face each other. Note that in this specification, translucency refers to a property of transmitting at least a part of electromagnetic waves including light (visible light).

  Further, as shown in FIG. 1B, the substrate pair 11 has a pair of main surfaces PP (hereinafter sometimes referred to as main surface pairs) PP that face each other with a gap GP. The main surface pair PP includes a first main surface PL1 provided on the first substrate 11A and a second main surface PL2 provided on the second substrate 11B. In other words, the wavelength selection element 10 includes the first and second substrates 11A and 11B having the first and second main surfaces PL1 and PL2 facing each other with the gap GP therebetween.

  In the present embodiment, the first main surface PL1 is composed of a central portion of one main surface (first main surface) MS1 of the first substrate 11A. In the present embodiment, as shown in FIGS. 1B and 1C, the main surface (second main surface) MS2 facing the main surface PL1 (main surface MS1) of the second substrate 11B is formed. Is provided with a recess, and the bottom surface of the recess is the second main surface PL2.

  In this embodiment, as shown in FIG. 1A, the first and second substrates 11A and 11B have a rectangular outer shape. Further, as shown in FIG. 1B, in the present embodiment, the first and second main surfaces PL1 and PL2 are arranged in parallel to each other. Second main surface PL2 has a circular shape.

  The wavelength selection element 10 includes a pair of reflection films (hereinafter, sometimes referred to as a reflection film pair) 12 having a characteristic of selectively transmitting electromagnetic waves. The reflective film pair 12 constitutes, for example, a Fabry-Perot etalon. Each of the reflective film pairs 12 is a thin film made of an alloy containing, for example, Ag and Ag, and is a reflective film (reflective film) having transparency. In this embodiment, the reflective film pair 12 has a circular shape when viewed from a direction perpendicular to the reflective film pair 12.

  As shown in FIG. 1B, the reflective film pair 12 is formed on the main surfaces PL1 and PL2 of the substrate pair 11, and is disposed opposite to each other with an optical distance DT. More specifically, the reflective film pair 12 is formed on the first reflective film 12A provided on the first main surface PL1 of the first substrate 11A and the second main surface PL2 of the second substrate 11B. And a second reflective film 12B provided on the substrate. In the present embodiment, the first and second reflective films 12A and 12B have mutually opposite surfaces arranged in parallel with each other.

  Further, the wavelength selection element 10 includes a joint portion 13 that joins the first and second substrates 11A and 11B to each other. As shown in FIG. 1A, in the present embodiment, the bonding portion 13 is composed of a plurality of bonding pieces 13 </ b> A that are scattered in a direction parallel to the substrate pair 11. In the following, when the joint portion 13 is referred to, it means both the joint portion 13 and the joint piece 13A.

  The reflective film pair 12 is provided in the central portion of the substrate pair 11, and the joint portion 13 is formed in the peripheral region of the substrate pair 11. Further, as shown in FIG. 1B, in this embodiment, the joint portion 13 is sandwiched between the first and second substrates 11A and 11B in this embodiment. That is, the substrate pair 11 is bonded to each other between the first and second substrates 11A and 11B.

  Further, as shown in FIG. 1B, the first and second substrates 11A and 11B have a contact portion 14 that directly contacts each other to define (define) the gap GP. The first and second substrates 11A and 11B are directly abutted (contacted) by the abutting portion 14. The height of the gap GP, that is, the facing distance between the first and second main surfaces PL1 and PL2, is determined by the abutting portion 14. Accordingly, the optical distance DT between the reflecting films 12A and 12B, that is, the resonator interval is determined by the abutting portion 14.

  In the present embodiment, the abutting portion 14 is provided so as to surround the outer periphery of the reflective film pair 12. Specifically, for example, the abutting portion 14 is formed in an annular shape so as to surround the outer periphery of the first reflective film 12A in a plane parallel to the first main surface PL1. Further, the joint portion 13 is formed outside the abutting portion 14. That is, in the present embodiment, the abutting portion 14 is provided between the joint portion 13 and the reflective film pair 12 when viewed from a direction perpendicular to the reflective film pair 12.

  Further, in the present embodiment, as shown in FIG. 1B, the bumping portion 14 has a main surface (second main surface) of one substrate (second substrate 11B in the present embodiment) of the substrate pair 11. The projection PJ on the flat top surface protruding from the surface PL2) and the main surface MS1 (first main surface PL1) of the other substrate (first substrate 11A in this embodiment) of the substrate pair 11 abut each other. Part. The protrusion PJ hits the first substrate 11A at the top surface, and defines (forms) a gap GP.

  Here, the protrusion PJ and the contact portion 14 will be described with reference to FIG. In addition, in FIG.1 (c), illustration of the 1st board | substrate 11A is abbreviate | omitted. In the present embodiment, the protrusion PJ is a portion protruding from the arrangement surface (surface for bonding) of the bonding portion 13 and the second main surface PL2 in the second substrate 11B. Specifically, in this embodiment, the protrusion PJ is a portion of the main surface MS2 remaining by forming a recess in the main surface MS2 of the second substrate 11B.

  The abutting portion 14 functions as a positioning portion for the reflective film pair 12 in the facing direction of the first and second substrates 11A and 11B (direction perpendicular to the first and second substrates 11A and 11B). On the other hand, the bonding portion 13 functions as a positioning portion for the reflective film pair 12 in a direction parallel to the substrate pair 11. That is, the position of the reflective film pair 12 in the direction perpendicular to the substrate pair 11 is determined by the bump 14, and the position of the reflective film pair 12 in the direction parallel to the substrate pair 11 is determined by the joint 13.

  Next, the operation of the wavelength selection element 10 will be described with reference to FIG. FIG. 2 is a cross-sectional view similar to FIG. 1B, but omits hatching. FIG. 2 is a diagram schematically illustrating the period from when the input light IL enters the wavelength selection element 10 until it is extracted to the outside as the selection light SL. First, the input light IL is incident on the wavelength selection element 10 through the first substrate 11A. The input light IL passes through the first substrate 11A and then passes through the first reflecting film 12A of the reflecting film pair 12.

  The input light IL repeats multiple reflections between the first and second reflective films 12A and 12B. At this time, in the input light IL, light having a wavelength corresponding to the optical distance DT (optical gap) of the reflective film pair 12 remains, and light having other wavelengths is attenuated. The remaining wavelength light passes through the second reflective film 12B as the selection light SL. Then, the selection light SL passes through the second reflective film 12B and then exits from the second substrate 11B. In this way, the wavelength selection element 10 selectively outputs (transmits) incident light (electromagnetic wave).

  FIG. 3 is a flowchart showing a manufacturing flow of the method for manufacturing the wavelength selecting element 10. 4A to 4D are cross-sectional views schematically showing the first or second substrate 11A or 11B in the process of manufacturing the wavelength selection element 10. FIG. The manufacturing method of the wavelength selection element 10 is demonstrated using FIG.3 and FIG.4 (a)-(d). In FIG. 4B, the shape of the second substrate 11B before processing is indicated by a broken line.

[Step of Forming First Reflective Film 12A]
First, the first reflective film 12A is formed on the first substrate 11A (FIG. 3, step S11). FIG. 4A is a cross-sectional view showing the first substrate 11A on which the first reflective film 12A is formed. Specifically, first, a first substrate 11A having a flat plate shape prepared by performing chemical mechanical polishing on both main surfaces is prepared. Next, the first reflective film 12A is formed on one (first main surface) MS1 of the main surface of the first substrate 11A. In the present embodiment, the central portion of the main surface MS1 is the first main surface PL1, and the first reflective film 12A is formed by forming a circular Ag film on the first main surface PL1.

[Formation Process of Protrusion PJ and Second Reflective Film 12B]
Next, the protrusion PJ and the second reflective film 12B are formed on the second substrate 11B (FIG. 3, step S12). FIG. 4B is a cross-sectional view showing the second substrate 11B on which the protrusions PJ and the second reflective film 12B are formed.

  Specifically, first, a second substrate 11B having a flat plate shape prepared by performing chemical mechanical polishing on both main surfaces is prepared. Next, a recess (first recess) RC1 is formed in the central portion of the main surface (second main surface) MS2 of the second substrate 11B. In addition, a recess (second recess) RC2 is formed in the peripheral region of main surface MS2. The recesses RC1 and RC2 can be formed, for example, by partially removing the main surface MS2 of the second substrate 11B by etching or the like.

  Note that a region where the recesses RC1 and RC2 are not formed is left on the main surface MS2 of the second substrate 11B. This remaining main surface MS2 becomes a protrusion PJ that protrudes relatively from the recesses RC1 and RC2. Further, the bottom surface of the recess RC1 serves as the second main surface PL2. In order to obtain a desired flatness, a flattening process may be performed on the bottom of the recess RC1. Thus, the protrusion PJ is formed on the second substrate 11B.

[Step of Forming Second Reflective Film 12B]
Next, the second reflective film 12B is formed on the second main surface PL2 which is the bottom surface of the recess RC1. In the present embodiment, the second reflective film 12B is formed by forming a circular Ag film on the second main surface PL2. In the present embodiment, the second reflective film 12B has the same shape and size as the first reflective film 12A.

[Coating process of joining member BD]
Next, the bonding member BD is applied to the second substrate 11B (FIG. 3, step S13). FIG. 4C is a cross-sectional view showing the second substrate 11B on which the bonding member BD is applied.

  Specifically, the bonding member BD is applied to a region outside the recess RC1 in the main surface MS2 of the second substrate 11B. In this embodiment, the bonding member BD is applied on the bottom surface of the recess RC2 formed on the main surface MS2 of the second substrate 11B. In the present embodiment, a curable adhesive made of an ultraviolet curable resin material was used as the bonding member BD.

  Further, the bonding member BD was applied to a plurality of locations on the bottom surface of the recess RC2. Moreover, as shown in FIG.4 (c), the viscosity and application quantity of the joining member BD were adjusted so that it might become the height exceeding protrusion PJ (main surface MS2). In addition, the application | coating process of this joining member BD, the butting process mentioned later, and a joining process were performed in air | atmosphere.

[Abutting step and bonding step of first and second substrates 11A and 11B]
Next, the first and second substrates 11A and 11B are brought into contact with each other (FIG. 3, step S14). Further, the bonding member BD is cured in a state where the first and second substrates 11A and 11B are in contact with each other, and the first and second substrates 11A and 11B are bonded to each other (step S15 in FIG. 3). FIG. 4D is a cross-sectional view showing the bonded first and second substrates 11A and 11B.

  Specifically, first, the first and second substrates 11A and 11B are abutted so that the first and second reflective films 12A and 12B face each other. In the present embodiment, the main surface MS1 of the first substrate 11A is directly abutted against (abuts) the protrusion PJ of the second substrate 11B. In this example, pressure was applied to the first and second substrates 11A and 11B to bring the main surface MS1 of the first substrate 11A into contact with the entire top surface of the protrusion PJ of the second substrate 11B. As a result, a bump 14 is formed.

  In the abutting step, the bonding member BD on the second substrate 11B is brought into contact with the main surface MS1 of the first substrate 11A. Specifically, after the main surface MS1 of the first substrate 11A is abutted against the second substrate 11B in the state shown in FIG. 4C, the bonding member BD first contacts the first substrate 11A. The protrusion PJ was abutted against the first substrate 11A.

  By forming the abutting portion 14 by the abutting step, the gap GP between the first and second main surfaces PL1 and PL2 and the optical distance DT between the first and second reflecting films 12A and 12B are formed (determined). )

  Subsequently, the first and second substrates 11 </ b> A and 11 </ b> B are bonded by curing the bonding member BD, and the bonding portion 13 is formed. In the present embodiment, the ultraviolet curable resin as the bonding member BD was irradiated with ultraviolet rays in a state where the bumps 14 were formed. As a result, the bonding member BD is cured to form the bonding portion 13, and the first and second substrates 11A and 11B are bonded. The wavelength selection element 10 was formed through such steps.

  Here, the joint portion 13 will be described. Fig.5 (a) is typical sectional drawing of the wavelength selection element 10 which concerns on a present Example. The joint portion 13 is made of a curable adhesive having a hardness (softness) after curing smaller than that of the first substrate 11A. The joint 13 has elasticity after curing, and this elastic force F1 is smaller than a bending stress (bending reaction force) F2 generated in the first substrate 11A after joining. This greatly improves the uniformity of the optical distance DT of the reflective film pair 12 in the wavelength selection element 10 after the bonding, that is, the product.

  Specifically, the bonding member BD, which is a curable adhesive serving as the bonding portion 13, contracts as compared to before the curing when it is cured. Accordingly, the first substrate 11A is bent (bent) toward the second substrate 11B, with the contact portion 14 as a fulcrum, on the bonding surface (contact surface) between the bonding portion 13 and the first substrate 11A. The power to work. And the contraction force which acts between the joining member BD and the first substrate 11A at the time of curing is inherent as the elastic force F1 even after curing. The first substrate 11A that has received the elastic force F1 generates a reaction force (reaction force against bending) F2 that repels the elastic force F1.

  However, by using a relatively low hardness (soft) material as the bonding portion 13, the reaction force F2 generated in the first substrate 11A can be made larger than the elastic force F1 of the bonding portion 13. Therefore, the deformation of the first substrate 11A due to the curing of the bonding member BD is suppressed, and the shape of the first substrate 11A is stabilized. As a result, the parallelism between the first and second main surfaces PL1 and PL2 is improved, and the gap GP has high in-plane uniformity. Therefore, the parallelism of the optical distance DT between the first and second reflective films 12A and 12B, that is, in-plane (in-film) uniformity is greatly improved. Therefore, the substrates are reliably positioned and fixed at a desired interval.

  For example, examples of the adhesive that can be used for the joint portion 13 include an acrylic adhesive and an epoxy adhesive. Moreover, as a hardening method of the junction part 13, an ultraviolet curing type or a thermosetting type is mentioned. Moreover, it is preferable that the adhesive agent of the junction part 13 consists of material which has a glass transition point lower than the environmental temperature in which the wavelength selection element 10 (substrate pair 11) is used. For example, when the joining portion 13 is formed of a resin material, the joining portion 13 is vitrified when the use environment temperature falls below the glass transition point, and does not have the elastic force F1 described above.

  FIG. 5B shows a wavelength having the same configuration as that of the wavelength selection element 10 except that the bonding portion 101 made of an adhesive whose hardness after curing is larger than that of the first substrate 11A is shown as a comparative example. A schematic cross-sectional view of the selection element 100 is shown. In the wavelength selection element 100 according to the comparative example, the elastic force F3 after the bonding portion 101 is cured is larger than the reaction force F2 of the first substrate 11A. In this case, as shown in FIG. 5B, the first and second substrates 11A and 11B are bonded in a state where the first substrate 11A is curved (warped state).

  Accordingly, when the joint portion 101 is provided, the uniformity of the gap GP0 between the first and second main surfaces PL1 and PL2 is lowered. And the uniformity of the optical distance DT0 between the first and second reflective films 12A and 12B is lowered. Therefore, the actual filtering characteristics of the wavelength selection element 100 are different from the designed filtering characteristics, and the selected light SL in the desired wavelength band may not be extracted.

  In turn, in the wavelength selection element 10, as described above, the first and second substrates 11A and 11B are joined by the joining portion 13 made of a curable adhesive having a hardness after curing smaller than that of the first substrate 11A. Has been. Therefore, the first and second substrates 11A and 11B are securely fixed at a desired interval, and the first and second reflective films 12A and 12B can be arranged at a desired interval.

  Further, the wavelength selection element 10 has a contact portion 14 between which the first and second substrates 11A and 11B directly abut between the first and second reflection films 12A and 12B and the joint portion 13. Accordingly, the gap GP between the first and second main surfaces PL1 and PL2 and the optical distance DT between the first and second reflection films 12A and 12B are reliably determined.

  Moreover, it is preferable that the joining part 13 has a plurality of joining pieces 13A scattered in the joining region (in this embodiment, in the region between the first and second substrates 11A and 11B). Thereby, it is possible to suppress variations in bonding strength and positional accuracy between the first and second substrates 11A and 11B during manufacturing. Specifically, for example, the possibility that foreign matter is mixed into the joint portion 13 is reduced. Therefore, the wavelength selection characteristic is stabilized.

  Further, the abutting portion 14 is a portion where the flat top surface of the protrusion PJ on the second substrate 11B (one substrate) and the main surface MS1 of the first substrate 11A (the other substrate) abut each other. Is preferred. In other words, it is preferable that the abutting portion 14 is a portion formed by directly abutting the surfaces.

  For example, in the present embodiment, the main surface MS1 of the first substrate 11A and the top surfaces of the protrusions PJ of the second substrate 11B that form the bumps 14 are rigid surfaces flattened by chemical mechanical polishing or the like. is there. By directly abutting the surfaces of the highly flattened rigid bodies, high parallelism between the first and second main surfaces PL1 and PL2, that is, high between the first and second reflection films 12A and 12B is obtained. Parallelism can be obtained.

  In the present embodiment, as described above, as a method for manufacturing the wavelength selection element 10, the substrate pair 11 is bonded using the bonding member BD made of a curable adhesive whose hardness after curing is smaller than that of the substrate pair 11. Steps S13 to S15 are included. Accordingly, it is possible to provide a wavelength selection element 10 having high wavelength selection characteristics in which substrates are securely positioned and fixed at desired intervals without requiring complicated processes, expensive apparatuses, and advanced manufacturing environments. can do. Moreover, the positioning accuracy between the substrates is further improved by performing the abutting step S14.

  In the present embodiment, the case where the abutting portion 14 is a portion where the substrate pair 11 directly abuts each other has been described. However, for example, the bumping portion 14, that is, the portion (contact portion) where one of the first and second substrates 11A and 11B abuts may be subjected to a surface treatment (surface processing) such as plating. That is, it is only necessary that the rigid portions of the first and second substrates 11A and 11B are in contact with each other.

  Further, in this embodiment, the case where the contact portion 14 forms surface contact with the flat top surface of the protrusion PJ of the second substrate 11B and the main surface MS1 of the first substrate 11A has been described. The configuration of 14 is not limited to this. For example, the top surface of the protrusion PJ may have a curved surface shape, and the contact portion 14 may be formed by point contact.

  In the present embodiment, the case where the abutting portion 14 is formed in an annular shape on the outer periphery of the reflective film pair 12 has been described. However, the configuration of the abutting portion 14 is not limited to this. For example, the contact portion 14 may be formed intermittently on the outer periphery of the reflective film pair 12. The abutting portion 14 may be composed of a plurality of abutting pieces (not shown) provided outside the reflective film pair 12. That is, the first and second substrates 11A and 11B may abut against each other in a plurality of regions separated from each other.

  In this embodiment, the case where the reflective film pair 12 has a circular planar shape has been described. However, the planar shape of the reflective film pair 12 is not limited to this. For example, the reflective film pair 12 may have a rectangular planar shape. Further, although the case where the substrate pair 11 has a rectangular planar shape has been described and illustrated, the planar shape of the substrate pair 11 is not limited thereto.

  Further, although the case where the protrusion PJ is formed on the main surface MS2 of the second substrate 11B has been described, the protrusion PJ may be formed on the first substrate 11A. Further, the protrusions PJ may be formed on both the first and second substrates 11A and 11B, and the protrusions PJ may be abutted against each other to form the contact portion 14.

  In this embodiment, the wavelength selection element 10 is formed on a pair of substrates 11 having translucency and having main surfaces PL1 and PL2 facing each other with a gap GP, and on the facing main surfaces PL1 and PL2. A pair of reflective films 12 facing each other at an optical distance DT, and a pair of substrates 11 joined to each other, and a joint portion 13 made of a curable adhesive having a smaller hardness after curing than the pair of substrates 11; A pair of substrates 11 directly contact each other and have a contact portion 14 that defines a gap GP. Therefore, it is possible to provide a wavelength selection element in which the substrates are reliably positioned and fixed at a desired interval.

  FIG. 6A is a diagram schematically illustrating the upper surface of the wavelength selection element 20 according to the second embodiment. FIG. 6B is a schematic cross-sectional view of the wavelength selection element 20. FIG. 6B is a cross-sectional view along the line WW in FIG. The wavelength selection element 20 has the same configuration as that of the wavelength selection element 10 except for the configuration of the joint portion 22 and the contact portion 23.

  The wavelength selection element 20 includes a pair of substrates (substrate pairs) 21 including first and second substrates 21A and 21B provided with first and second reflective films 12A and 12B. In addition, the joint portion 22 is provided outside the first sub-joint portion 22A and the first sub-joint portion 22A provided so as to surround the reflective film pair 12, and is harder than the first sub-joint portion 22A. And a second sub-joining portion 22B made of a curable adhesive having a high hardness later.

  The first sub-junction portion 22 </ b> A has the same configuration as the joint portion 13 in the wavelength selection element 10. The first sub-joining portion 22A is made of a curable adhesive having a hardness after curing that is smaller than that of the substrate pair 21. The second sub-joining portion 22B is made of a curable adhesive having a higher hardness after curing than the first sub-joining portion 22A. In the present embodiment, the second sub-joining portion 22 </ b> B is composed of a total of four joining pieces provided at each corner of the substrate pair 21.

  In the present embodiment, the abutting portion 23 provided on the substrate pair 21 of the wavelength selection element 20 is provided between the reflective film pair 12 and the first sub-joining portion 22A so as to surround the reflective film pair 12. It has a first sub-abutting portion 23A and a second sub-abutting portion 23B provided between the second sub-joining portion 22B and the first sub-abutting portion 23A.

  In the present embodiment, the first sub-abutment portion 23A has the same configuration as that of the abutment portion 14 in the wavelength selection element 10, and the first main surface PL1 (main surface MS1) of the first substrate 21A and the first sub-abutment portion 14A. The tops of the protrusions (first protrusions) PJ of the second substrate 21 </ b> B are in contact with each other.

  In the present embodiment, the second substrate 21B is a projection (second projection) provided in an annular shape so as to surround a predetermined region at each corner of the main surface MS2 of the second substrate 21B. It has PJ1. The second sub-abutting portion 23B is a portion where the first main surface PL1 of the first substrate 21A and the protrusion PJ1 of the second substrate 21B abut. Further, a second sub-joining portion 22B of the joining portion 22 is formed in a region surrounded by the protrusion PJ1.

  In other words, the wavelength selection element 20 has the joint portion 22 including the first and second sub-joint portions 22A and 22B having different hardnesses. The wavelength selection element 20 includes first and second sub-abutting portions 23A and 23B as the abutting portion 23, and a portion where the first and second substrates 21A and 21B abut each other at a plurality of locations. Have.

  In the present embodiment, both high uniformity (parallelism) of the gap GP between the first and second main surfaces PL1 and PL2 of the substrate pair 21 and a strong bonding force of the substrate pair 21 are realized. Specifically, the first sub joint portion 22A of the joint portion 22 and the first sub bump contact portion 23A of the bump portion 23 are provided in consideration of the uniformity of the gap GP as in the first embodiment. On the other hand, the bonding strength of the substrate pair 21 is improved by the second sub-joining portion 22B of the joining portion 22 and the second sub-butting portion 23B of the contacting portion 23.

  Thus, in the present embodiment, the first and second substrates 21A and 21B are joined by the joint portion 22 composed of a plurality of sub-joint portions. Therefore, it is possible to provide the wavelength selection element 20 in which the substrates are reliably positioned and fixed at a desired interval.

  FIG. 7A is a diagram schematically illustrating the upper surface of the wavelength selection element 30 according to the third embodiment. FIG. 7B is a cross-sectional view of the wavelength selection element 30. FIG. 7B is a cross-sectional view taken along line XX in FIG. The wavelength selection element 30 has the same configuration as the wavelength selection element 10 except for the configuration of the substrate pair 31, the movable portion 32, the support portion 33, and the drive electrode 34. The substrate pair 31 is made of the same material as the substrate pair 11.

  The wavelength selection element 30 is provided in a region inside the abutting portion 14 on the first substrate 31A, and a movable portion 32 that displaces the first reflective film 12A in the film thickness direction of the first reflective film 12A, and a movable portion. And a support portion 33 that movably supports 32. The wavelength selection element 30 includes first and second electrodes 34 </ b> A and 34 </ b> B, and includes a drive electrode 34 that generates an electrostatic force that moves the movable portion 32.

  More specifically, as shown in FIG. 7B, in this embodiment, the support portion 33 is formed of a thin film portion provided on the outer peripheral portion of the first reflective film 12A on the first substrate 31A. . The movable part 32 is a part of the first substrate 31 </ b> A inside the thin film part as the support part 33. The bottom surface of the movable portion 32 constitutes the first main surface PL1, and the first reflective film 12A is formed on the bottom surface of the movable portion 32.

  Further, in the present embodiment, the first and second surfaces are formed between the movable portion 32 and the reflective film pair 12 on the main surfaces PL1 and PL2 facing each other of the substrate pair 31 and facing each other with a gap. Two electrodes 34A and 34B are provided. The drive electrode 34 generates an electrostatic force that moves the movable portion 32 and displaces the first reflective film 12A. Although not shown, the wavelength selection element 30 has a drive circuit connected to the drive electrode 34.

  When a voltage is applied to the drive electrode 34, an electrostatic force (for example, electrostatic attractive force) is generated between the first and second electrodes 34A and 34B. The support portion 33 is elastically deformed by the electrostatic force. Accordingly, the movable portion 32 moves (displaces) together with the first reflective film 12A and the first electrode 34A, for example, toward the second substrate 31B. Thus, the wavelength selection element 30 has a function of changing the optical distance DT between the first and second reflection films 12A and 12B and adjusting the wavelength of the extracted electromagnetic wave (selection light SL). That is, the wavelength selection element 30 is a wavelength tunable optical filter.

  FIG. 8A is a schematic cross-sectional view of the wavelength selection element 30 during driving, that is, when the movable portion 32 moves and the first reflective film 12A is displaced. FIG. 8A shows the state of the wavelength selection element 30 when the first reflective film 12A is displaced so that the optical distance DT1 is smaller than the optical distance DT.

  Similar to the wavelength selection element 10, the bonding portion 13 is made of a curable adhesive having a hardness after curing that is lower than that of the substrate pair 31. Therefore, as described with reference to FIG. 5A, the elastic force F <b> 1 after the bonding portion 13 is cured is smaller than the bending reaction force F <b> 2 of the substrate pair 11. Accordingly, the bonding portion 13 expands and contracts due to the bending stress generated in the first substrate 31A after curing while maintaining the bonding force (the figure is an example of expansion).

  Thus, even when the bonding portion 13 is deformed by applying a deformation force (movable force) to the first substrate 31A by the drive electrode 34, for example, unnecessary deformation does not occur in the first substrate 31A. Therefore, the movable portion 32 can be moved by the joint portion 13 and the contact portion 14 so that the gap GP1 becomes an ideal distance, and the optical distance DT1 can be accurately changed.

  FIG. 8B is a cross-sectional view schematically showing a state during driving of the wavelength selection element 110 bonded by the bonding portion 101 instead of the bonding portion 13 as a comparative example. First, when the bonding portion 101 is used, after the bonding portion 101 is cured, the first substrate 31A undergoes unnecessary deformation due to curing shrinkage of the bonding portion 101. When the wavelength selection element 110 is driven in this state, not only the gap GP2 of the substrate pair 31 is not uniform, but the movable part 32 is likely to move with a displacement amount different from the design displacement amount. Accordingly, the optical distance DT2 of the reflective film pair 12 may deviate from the design uniformity and distance, and desired filtering characteristics may not be obtained.

  In turn, the wavelength selection element 30 is flexible even after the joint 13 is cured, so that the optical distance DT can be accurately adjusted to the designed optical distance DT1, and the uniformity thereof is also high.

  Thus, in this embodiment, the wavelength selection element 30 is provided inside the abutting portion 14 in one of the substrate pairs 31 (the first substrate 31A in this embodiment), and the optical distance of the reflective film pair 12 is set. It has a movable part 32 that displaces DT. Therefore, for example, even when the wavelength selection characteristic is changed by displacing the first reflective film 12A, the wavelength variable type in which the substrates are reliably positioned at a desired interval by having the joint portion 13 and the abutting portion 14. The wavelength selection element 30 can be provided.

  The above-described embodiments can be combined with each other. For example, the wavelength selection element 30 according to the third embodiment may include the bonding portion 22 and the bump portion 23 of the wavelength selection element 20 according to the second embodiment instead of the bonding portion 13 and the bump portion 14.

10, 20, 30 Wavelength selection elements 11, 21, 31 A pair of substrates 11A, 21A, 31A A first substrate 11B, 21B, 31B A second substrate 12 A pair of reflection films 12A A first reflection film 12B A second reflection Membrane PP A pair of main surfaces 13 and 22 Joining parts 14 and 23 Abutting part 32 Moving part 33 Supporting part

Claims (9)

A pair of substrates having translucency and having main surfaces facing each other with a gap;
A pair of reflective films formed on the main surfaces facing each other and facing each other at an optical distance;
Bonding the pair of substrates to each other, a bonding portion made of a curable adhesive having a smaller hardness after curing than the pair of substrates;
A wavelength selection element comprising: a pair of abutting portions where the pair of substrates directly abut each other to define the gap.   The wavelength selection element according to claim 1, wherein the abutting portion is formed so as to surround an outer periphery of the pair of reflective films between the pair of reflective films and the joint portion.   3. The wavelength selection element according to claim 2, further comprising a movable portion that is provided inside the bumping portion on one of the pair of substrates and that displaces the optical distance of the pair of reflective films. The joint portion is provided on the outer side of the first sub-joint portion and the first sub-joint portion provided so as to surround the pair of reflective films, and is hardened more than the first sub-joint portion. A second sub-joint portion made of a curable adhesive having a high hardness,
The abutting portions are provided between the pair of reflective films and the first sub-joining portion, and surround the pair of reflecting films, the first sub-abutting portion, the second sub-joining portion, and the first sub-joining portion. 4. The wavelength selection element according to claim 2, further comprising a second sub-abutment portion provided between the first sub-abutment portion.   The said joining part consists of a hardening type adhesive agent whose elastic force after hardening is smaller than the bending reaction force which used the said abutting part of said pair of board | substrate as a fulcrum. The wavelength selection element according to 1. The pair of substrates is used at an environmental temperature within a predetermined range,
The wavelength selection element according to claim 1, wherein the bonding portion is made of a material having a glass transition point lower than the environmental temperature.   The wavelength selection element according to claim 1, wherein the bonding portion includes a plurality of bonding pieces scattered between each of the pair of substrates.   The wavelength selecting element according to claim 1, wherein the joint portion is made of an acrylic adhesive or an epoxy adhesive. A first reflective film forming step of forming a first reflective film on the first main surface of the first substrate;
A second reflective film forming step of forming a second reflective film in the concave portion of the second substrate having the second main surface provided with the concave portion;
An application step of applying a bonding member made of a curable adhesive having a hardness after curing that is lower than that of the first substrate on a region outside the concave portion of the second main surface of the second substrate;
An abutting step of directly abutting the first main surface against the second main surface such that the first and second reflective films face each other at an optical distance;
A method of manufacturing a wavelength selective element, comprising: a step of curing the bonding member and bonding the first and second substrates.

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