Fabry-Perot interference filter having layer with thinned edge portion and production method for Fabry-Perot interference filter

The Fabry-Perot interference filter includes: a substrate having a first surface, a first laminate having a first mirror portion disposed on the first surface, a second laminate having a second mirror portion facing the first mirror portion with an air gap interposed therebetween, and an intermediate layer defining the air gap between the first and second laminate. The substrate has an outer edge portion positioned outside an outer edge of the intermediate layer when viewed from a direction perpendicular to the first surface. The second laminate further includes a covering portion covering the intermediate layer and a peripheral edge portion positioned on the first surface in the outer edge portion. The second mirror portion, the covering portion, and the peripheral edge portion are integrally formed so as to be continuous with each other. The peripheral edge portion is thinned along an outer edge of the outer edge portion.

TECHNICAL FIELD

The present disclosure relates to a Fabry-Perot interference filter and a method for producing a Fabry-Perot interference filter.

BACKGROUND ART

A Fabry-Perot interference filter in the related art includes a substrate, a first layer having a first mirror portion disposed on the substrate, a second layer having a second mirror portion facing the first mirror portion with an air gap interposed therebetween, and an intermediate layer defining the air gap between the first layer and the second layer (refer to, for example, Patent Literature 1).

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

In the Fabry-Perot interference filter as described above, because the respective thicknesses of the first layer, the intermediate layer and the second layer are extremely thin such as, for example, about several tens of nm to several tens of μm, there is a concern that peeling of each layer may occur in use or the like.

An object of one aspect of the present disclosure is to provide a Fabry-Perot interference filter and a method for producing a Fabry-Perot interference filter, which can suppress the occurrence of peeling in each layer on a substrate.

Solution to Problem

A Fabry-Perot interference filter according to one aspect of the present disclosure includes a substrate having a first surface, a first layer having a first mirror portion disposed on a first surface, a second layer having a second mirror portion facing the first mirror portion with an air gap interposed therebetween on a side opposite to the substrate with respect to the first mirror portion, and an intermediate layer defining the air gap between the first layer and the second layer, in which the substrate has an outer edge portion positioned outside an outer edge of the intermediate layer when viewed from a direction perpendicular to the first surface, in which the second layer further includes a covering portion covering the intermediate layer and a peripheral edge portion positioned on the first surface in the outer edge portion, in which the second mirror portion, the covering portion and the peripheral edge portion are integrally formed so as to be continuous with each other, and in which the peripheral edge portion is thinned along the outer edge of the outer edge portion.

In this Fabry-Perot interference filter, the second layer further includes, in addition to the first mirror portion, a covering portion covering the intermediate layer and a peripheral edge portion positioned on the first surface in the outer edge portion, and the first mirror portion, the covering portion and the peripheral edge portion are integrally formed so as to be continuous with each other. As a result, because the intermediate layer is covered with the second layer, peeling of the intermediate layer is suppressed. In addition, because the intermediate layer is covered with the second layer, deterioration of the intermediate layer is suppressed even in a case where the air gap is formed in the intermediate layer, for example, by etching, so that the stability of the intermediate layer is improved. Furthermore, in this Fabry-Perot interference filter, the peripheral edge portion is thinned along the outer edge of the outer edge portion. Thus, for example, even in a case where the Fabry-Perot interference filter is obtained by cutting the wafer including the portion corresponding to the substrate along the outer edge of the outer edge portion, degradation of each layer on the substrate is suppressed, and as a result, the stability of each layer is improved. As described above, according to the Fabry-Perot interference filter, it is possible to suppress the occurrence of peeling in each layer on the substrate. The phrase “the peripheral edge portion is thinned along the outer edge of the outer edge portion” denotes that “the thickness of the portion of the peripheral edge portion along the outer edge of the outer edge portion is smaller (including zero) than the thickness of the other portions excluding the portion of the peripheral edge portion along the outer edge of the outer edge portion”.

In the Fabry-Perot interference filter according to one aspect of the present disclosure, the covering portion may cover the outer edge of the first layer. According to this, it is possible to more reliably suppress peeling of the first layer. In addition, for example, even in a case where the Fabry-Perot interference filter is obtained by cutting the wafer including the portion corresponding to the substrate along the outer edge of the outer edge portion, it is possible to more preferably suppress degradation of the first layer.

In the Fabry-Perot interference filter according to one aspect of the present disclosure, the first layer may be a laminate including a silicon nitride layer. According to this, because the silicon nitride layer of the first layer is not exposed to the outside, even in the case of forming an air gap in the intermediate layer by etching using, for example, a hydrofluoric acid gas, it is possible to suppress the generation of residues by reaction of the hydrofluoric acid gas and the silicon nitride layer.

In the Fabry-Perot interference filter according to one aspect of the present disclosure, the second layer is a laminate including a plurality of layers, and the peripheral edge portion may be thinned along the outer edge of the outer edge portion by removing a portion of the plurality of layers. According to this, it is possible to protect the first surface of the substrate by the remaining portions of the plurality of layers that are not removed.

The Fabry-Perot interference filter according to one aspect of the present disclosure may further include a third layer disposed on a second surface of the substrate opposing to the first surface. The third layer may be thinned along the outer edge of the outer edge portion. According to this, because the third layer is disposed on the second surface of the substrate, it is possible to suppress warping of the substrate caused by a mismatch in layer configuration between the first surface side and the second surface side of the substrate. In addition, for example, even in a case where the Fabry-Perot interference filter is obtained by cutting the wafer including the portion corresponding to the substrate along the outer edge of the outer edge portion, deterioration of the third layer is suppressed, and as a result, the stability of each layer of the third layer is improved. The phrase “the third layer is thinned along the outer edge of the outer edge portion” denotes that “the thickness of the portion of the third layer along the outer edge of the outer edge portion is smaller (including zero) than the thickness of the other portions excluding the portion of the third layer along the outer edge of the outer edge portion.

A method for producing a Fabry-Perot interference filter according to one aspect of the present disclosure is a method for producing the Fabry-Perot interference filter, including: a first step of preparing a wafer including a plurality of portions corresponding to the substrate and forming the first layer having the first mirror portion for each of the portions corresponding to the substrate; a second step of forming the intermediate layer having a removal scheduled portion corresponding to the air gap for each of the portions corresponding to the substrate after the first step; a third step of forming the second layer having the second mirror portion a plurality of through holes formed therein, the covering portion covering the intermediate layer, and the peripheral edge portion thinned along the outer edge of the outer edge portion for each of the portions corresponding to the substrate after the second step; a fourth step of forming the air gap positioned between the first mirror portion and the second mirror portion for each of the portions corresponding to the substrate by removing the removal scheduled portion by etching through the through hole after the third step; and a fifth step of obtaining the Fabry-Perot interference filter by cutting the wafer along the outer edge of the outer edge portion after the fourth step.

In the method for producing the Fabry-Perot interference filter, after forming the second layer having the covering portion covering the intermediate layer, the removal scheduled portion of the intermediate layer is removed by etching. Therefore, it is possible to suppress degradation of the intermediate layer at the time of removing the removal scheduled portion by etching. Furthermore, in the method for producing the Fabry-Perot interference filter, after forming the second layer having the peripheral edge portion thinned along the outer edge of the outer edge portion, the Fabry-Perot interference filter is obtained by cutting the wafer along the outer edge of the outer edge portion. Therefore, it is possible to suppress deterioration of each layer on the substrate at the time of cutting the wafer. In addition, in the Fabry-Perot interference filter produced by the method for producing the Fabry-Perot interference filter, because the intermediate layer is covered with the second layer, peeling of the intermediate layer is suppressed. As described above, according to the method for producing the Fabry-Perot interference filter, it is possible to suppress the occurrence of peeling in each layer on the substrate.

In the method for producing the Fabry-Perot interference filter according to one aspect of the present disclosure, in the fifth step, the wafer may be cut along the outer edge of the outer edge portion by forming a modified region in an inner portion of the wafer along the outer edge of the outer edge portion by irradiation with a laser beam and by extending a crack from the modified region in a thickness direction of the wafer. According to this, because the peripheral edge portion is thinned along the outer edge of the outer edge portion, it is possible to preferably focus the laser beam on the inner portion of the wafer, and thus, it is possible to cut the wafer with a high accuracy.

Advantageous Effects of Invention

According to one aspect of the present disclosure, it is possible to provide a Fabry-Perot interference filter and a method for producing a Fabry-Perot interference filter, which can suppress the occurrence of peeling in each layer on a substrate.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings. In addition, in the following description, the same reference numerals are used for the same or corresponding elements, and redundant description are omitted.

As illustrated inFIGS. 1, 2, and 3, the Fabry-Perot interference filter1includes a substrate11. The substrate11has a first surface11aand a second surface11bopposing to the first surface11a. An antireflection layer21, a first laminate (first layer)22, an intermediate layer23, and a second laminate (second layer)24are laminated in this order on the first surface11a. An air gap S is defined between the first laminate22and the second laminate24by a frame-shaped intermediate layer23.

The shapes and positional relationships of portions when viewed from a direction perpendicular to the first surface11a(in plan view) are as follows. The outer edge of the substrate11has, for example, a rectangular shape. The outer edge of the substrate11and the outer edge of the second laminate24coincide with each other. The outer edge of the antireflection layer21, the outer edge of the first laminate22, and the outer edge of the intermediate layer23coincide with each other. The substrate11has an outer edge portion11positioned outside the outer edge of the intermediate layer23. The outer edge portion11cis, for example, in a frame shape and surrounds the intermediate layer23when viewed from the direction perpendicular to the first surface11a.

The Fabry-Perot interference filter1transmits light having a predetermined wavelength in the light transmission region1adefined in the central portion thereof. The light transmission region1ais, for example, a cylindrical region. The substrate11is made of, for example, silicon, quartz, glass, or the like. In a case where the substrate11is made of silicon, the antireflection layer21and the intermediate layer23are made of, for example, a silicon oxide. The thickness of the intermediate layer23is, for example, several tens of nm to several tens of μm.

A portion of the first laminate22corresponding to the light transmission region1afunctions as the first mirror portion31. The first mirror portion31is disposed on the first surface11awith the antireflection layer21interposed therebetween. The first laminate22is configured by alternately laminating a plurality of polysilicon layers25and a plurality of silicon nitride layers26layer by layer. In this embodiment, the polysilicon layer25a, the silicon nitride layer26a, the polysilicon layer25b, the silicon nitride layer26b, and the polysilicon layer25care laminated on the antireflection layer21in this order. It is preferable that the optical thickness of each of the polysilicon layer25and the silicon nitride layer26constituting the first mirror portion31is an integral multiple of ¼ of the center transmission wavelength. The first mirror portion31may be disposed directly on the first surface11awithout interposing the antireflection layer21therebetween.

A portion of the second laminate24corresponding to the light transmission region1afunctions as the second mirror portion32. The second mirror portion32faces the first mirror portion31with the air gap S interposed therebetween on the side opposite to the substrate11with respect to the first mirror portion31. The second mirror portion32is disposed on the first surface11awith the antireflection layer21, the first laminate22, and the intermediate layer23interposed therebetween. The second laminate24is configured by alternately laminating a plurality of polysilicon layers27and a plurality of silicon nitride layers28layer by layer. In this embodiment, the polysilicon layer27a, the silicon nitride layer28a, the polysilicon layer27b, the silicon nitride layer28b, and the polysilicon layer27care laminated on the intermediate layer23in this order. It is preferable that the optical thickness of each of the polysilicon layer27and the silicon nitride layer28constituting the second mirror portion32is an integral multiple of ¼ of the center transmission wavelength.

In the first laminate22and the second laminate24, a silicon oxide layer may be used instead of the silicon nitride layer. In addition, as a material of each layer constituting the first laminate22and the second laminate24, there may be used a titanium oxide, a tantalum oxide, a zirconium oxide, a magnesium fluoride, an aluminum oxide, a calcium fluoride, silicon, germanium, a zinc sulfide, or the like.

In the second laminate24, in a portion corresponding to the air gap S, a plurality of through holes24bextending from the surface24aof the second laminate24on the side opposite to the intermediate layer23to the air gap S are formed. The plurality of through holes24bare formed to such an extent that the through holes do not substantially affect the function of the second mirror portion32. The plurality of through holes24bare used to form the air gap S by removing a portion of the intermediate layer23by etching.

In addition to the second mirror portion32, the second laminate24further has a covering portion33and a peripheral edge portion34. The second mirror portion32, the covering portion33, and the peripheral edge portion34have the same laminate structure and are integrally formed so as to be continuous with each other. The covering portion33surrounds the second mirror portion32when viewed from the direction perpendicular to the first surface11a. The covering portion33covers the surface23aof the intermediate layer23on the side opposite to the substrate11, the side surface23bof the intermediate layer23, the side surface22aof the first laminate22, and the side surface21aof the antireflection layer21and reaches the first surface11a. That is, the covering portion33covers the outer edge of the intermediate layer23, the outer edge of the first laminate22, and the outer edge of the antireflection layer21.

The peripheral edge portion34surrounds the covering portion33when viewed from the direction perpendicular to the first surface11a. The peripheral edge portion34is positioned on the first surface11ain the outer edge portion11c. The outer edge of the peripheral edge portion34coincides with the outer edge of the substrate11when viewed from the direction perpendicular to the first surface11a.

The peripheral edge portion34is thinned along the outer edge of the outer edge portion11c. That is, the portion of the peripheral edge portion34along the outer edge of the outer edge portion11cis thinner than the other portions excluding the portions of the peripheral edge portion34along the outer edge. In this embodiment, the peripheral edge portion34is thinned by removing a portion of the polysilicon layer27and the silicon nitride layer28constituting the second laminate24. The peripheral edge portion34has a non-thinned portion34acontinuous with the covering portion33and a thinned portion34bsurrounding the non-thinned portion34a. In the thinned portion34b, the polysilicon layer27and the silicon nitride layer28other than the polysilicon layer27adirectly provided on the first surface11aare removed.

The height of the surface34cof the non-thinned portion34aon the side opposite to the substrate11from the first surface11ais lower than the height of the surface23aof the intermediate layer23from the first surface11a. The height of the surface34cof the non-thinned portion34afrom the first surface11ais, for example, 700 nm to 1400 nm. The height of the surface23aof the intermediate layer23from the first surface11ais, for example, 2000 nm to 4000 nm. The width of the thinned portion34b(the distance between the outer edge of the non-thinned portion34aand the outer edge of the outer edge portion11c) is 0.01 times or more the thickness of the substrate11. The width of the thinned portion34bis, for example, 5 μm to 400 μm. The thickness of the substrate11is, for example, 500 μm to 800 μm.

A first electrode12is formed in the first mirror portion31so as to surround the light transmission region1a. The first electrode12is formed by doping impurities into the polysilicon layer25cto lower the resistance thereof. The second electrode13is formed in the first mirror portion31so as to include the light transmission region1a. The second electrode13is formed by doping impurities into the polysilicon layer25cto lower the resistance thereof. The size of the second electrode13is preferably the size including the entire light transmission region1a, but may be substantially the same as that of the light transmission region1a.

A third electrode14is formed in the second mirror portion32. The third electrode14faces the first electrode12and the second electrode13with the air gap S interposed therebetween. The third electrode14is formed by doping impurities into the polysilicon layer27ato lower the resistance thereof.

Terminals15are provided in a pair so as to face each other with the light transmission region1ainterposed therebetween. Each terminal15is disposed in a through hole extending from the surface24aof the second laminate24to the first laminate22. Each terminal15is electrically connected to the first electrode12via the wiring12a.

Terminals16are provided in a pair so as to face each other with the light transmission region1ainterposed therebetween. Each terminal16is disposed in a through hole extending from the surface24aof the second laminate24to an inner portion of the intermediate layer23. Each terminal16is electrically connected to the second electrode13via the wiring13aand is also electrically connected to the third electrode14via the wiring14a. The direction in which the pair of terminals15face each other and the direction in which the pair of terminals16face each other are perpendicular to each other (refer toFIG. 1).

Trenches17and18are provided with the surface22bof the first laminate22. The trench17extends annularly so as to surround a portion of the wiring13aconnected to the terminal16. The trench17electrically insulates the first electrode12from the wiring13a. The trench18extends annularly along an inner edge of the first electrode12. The trench18electrically insulates the first electrode12from the region inside the first electrode12(the second electrode13). The region in each of the trench17and18may be an insulating material or an air gap.

A trench19is provided with the surface24aof the second laminate24. The trench19extends annularly so as to surround the terminal15. The trench19electrically insulates the terminal15from the third electrode14. The region in the trench19may be an insulating material or an air gap.

An antireflection layer41, a third laminate (third layer)42, an intermediate layer (third layer)43, and a fourth laminate (third layer)44are laminated in this order on the second surface11bof the substrate11. The antireflection layer41and the intermediate layer43have structures similar to those of the antireflection layer21and the intermediate layer23, respectively. The third laminate42and the fourth laminate44have laminate structures symmetrical to the first laminate22and the second laminate24with respect to the substrate11, respectively. The antireflection layer41, the third laminate42, the intermediate layer43, and the fourth laminate44have a function of suppressing warping of the substrate11.

The third laminate42, the intermediate layer43and the fourth laminate44are thinned along the outer edge of the outer edge portion11c. That is, the portions of the third laminate42, the intermediate layer43, and the fourth laminate44along the outer edge of the outer edge portion11care thinner than other portions excluding the portions of the third laminate42, the intermediate layer43, and the fourth laminate44along the outer edge. In this embodiment, the third laminate42, the intermediate layer43, and the fourth laminate44are thinned by entirely removing the third laminate42, the intermediate layer43, and the fourth laminate44in the portions overlapping with the thinned portion34bwhen viewed from the direction perpendicular to the first surface11a.

An opening40ais provided with the third laminate42, the intermediate layer43and the fourth laminate44so as to include the light transmission region1a. The opening40ahas substantially the same diameter as the size of the light transmission region1a. The opening40ais opened to the light emitting side, and the bottom surface of the opening40areaches the antireflection layer41.

A light shielding layer45is formed on the light-emitting-side surface of the fourth laminate44. The light shielding layer45is made of, for example, aluminum or the like. A protective layer46is formed on the surface of the light shielding layer45and the inner surface of the opening40a. The protective layer46covers the outer edges of the third laminate42, the intermediate layer43, the fourth laminate44, and the light shielding layer45and covers the antireflection layer41on the outer edge portion11c. The protective layer46is made of, for example, an aluminum oxide. It is possible to ignore the optical influence by the protective layer46by setting the thickness of the protective layer46to 1 to 100 nm (preferably about 30 nm).

In the Fabry-Perot interference filter1configured as described above, when a voltage is applied between the first electrode12and the third electrode14through the terminals15and16, an electrostatic force corresponding to the voltage is generated between the first electrode12and the third electrode14. Due to the electrostatic force, the second mirror portion32is attracted toward the first mirror portion31side fixed to the substrate11, and thus, the distance between the first mirror portion31and the second mirror portion32is adjusted. As described above, in the Fabry-Perot interference filter1, the distance between the first mirror portion31and the second mirror portion32is variable.

The wavelength of light passing through the Fabry-Perot interference filter1depends on the distance between the first mirror portion31and the second mirror portion32in the light transmission region1a. Therefore, by adjusting the voltage applied between the first electrode12and the third electrode14, it is possible to appropriately select the wavelength of the transmitting light. At this time, the second electrode13has the same potential as the third electrode14. Therefore, the second electrode13functions as a compensation electrode for maintaining the first mirror portion31and the second mirror portion32flat in the light transmission region1a.

In the Fabry-Perot interference filter1, for example, while varying the voltage applied to the Fabry-Perot interference filter1(that is, changing the distance between the first mirror portion31and the second mirror portion32in the Fabry-Perot interference filter1), by detecting the light transmitted through the light transmission region1aof the Fabry-Perot interference filter1by a photodetector, it is possible to obtain an optical spectrum.

As described above, in the Fabry-Perot interference filter1, the second laminate24further includes the covering portion33covering the intermediate layer23and the peripheral edge portion34positioned on the first surface11ain the outer edge portion11cin addition to the first mirror portion31, and the first mirror portion31, the covering portion33, and the peripheral edge portion34are integrally formed so as to be continuous with each other. As a result, because the intermediate layer23is covered with the second laminate24, it is possible to suppress peeling of the intermediate layer23. In addition, because the intermediate layer23is covered with the second laminate24, even in a case where the air gap S is formed in the intermediate layer23, for example, by etching, deterioration of the intermediate layer23is suppressed, and as a result, the stability of the intermediate layer23is improved. Furthermore, in the Fabry-Perot interference filter1, the peripheral edge portion34is thinned along the outer edge of the outer edge portion11c. Therefore, for example, even in a case where the Fabry-Perot interference filter1is obtained by cutting the wafer including the portion corresponding to the substrate11along the outer edge of the outer edge portion11c, deterioration of each layer on the substrate11is suppressed, and as a result, the stability of each layer on the substrate is improved. As described above, according to the Fabry-Perot interference filter1, it is possible to suppress the occurrence of peeling in each layer on the substrate11. Furthermore, in the Fabry-Perot interference filter1, because the side surface23bof the intermediate layer23is covered with the second laminate24, it is possible to suppress the incidence of light from the side surface23bof the intermediate layer23, and it is possible to suppress the generation of stray light.

In addition, in the Fabry-Perot interference filter1, the covering portion33covers the outer edge of the first laminate22. Therefore, it is possible to more reliably suppress peeling of the first laminate22. In addition, for example, even in a case where the Fabry-Perot interference filter1is obtained by cutting a wafer including a portion corresponding to the substrate11along the outer edge of the outer edge portion11c, it is possible to more preferably suppress deterioration of the first laminate22.

In addition, in the Fabry-Perot interference filter1, the outer edge of the silicon nitride layer26included in the first laminate22is covered with the covering portion33. Therefore, because the silicon nitride layer26of the first laminate22is not exposed to the outside, even in the case of forming the air gap S in the intermediate layer23by etching using, for example, a hydrofluoric acid gas, it is possible to suppress the generation of residues by reaction of the hydrofluoric acid gas and the silicon nitride layer26.

In addition, the Fabry-Perot interference filter1is thinned along the outer edge of the outer edge portion11cby removing a portion of the polysilicon layer27and the silicon nitride layer28constituting the second laminate24. Therefore, it is possible to protect the first surface11aof the substrate11by the remaining portions of the polysilicon layer27and the silicon nitride layer28constituting the second laminate24that are not removed. Furthermore, in the Fabry-Perot interference filter1, only the polysilicon layer27aremains in the thinned portion34b. Therefore, because the surface of the thinned portion34bbecomes smooth, for example, in order to cut the wafer including the portion corresponding to the substrate11along the outer edge of the outer edge portion11c, even in a case where the laser beam is focused on an inner portion of the wafer along the outer edge of the outer edge portion11c, it is possible to accurately cut the wafer by preferably focusing the laser beam on the inner portion of the wafer, and it is possible to more preferably suppress deterioration of each layer on the substrate11.

In addition, in the Fabry-Perot interference filter1, the third laminate42and the fourth laminate44are disposed on the second surface11bof the substrate11, and the third laminate42and the fourth laminate44are thinned along the outer edge the outer edge portion11c. Therefore, it is possible to suppress warping of the substrate11caused by a mismatch in layer configuration between the first surface11aside and the second surface11bside of the substrate11. Furthermore, for example, even in a case where the Fabry-Perot interference filter1is obtained by cutting the wafer including the portion corresponding to the substrate11along the outer edge of the outer edge portion11c, deterioration of the third laminate42and the fourth laminate44is suppressed, and as a result, the stability of each layer on the substrate11is improved.

Next, an example of a method for producing the Fabry-Perot interference filter1will be described with reference toFIGS. 4 to 7. First, as illustrated inFIG. 4(a), a wafer10including a plurality of portions R corresponding to the substrate11is prepared, and the first laminate22having the first mirror portion31is formed for each of the portions R corresponding to the substrates11of the wafer10(first step). The wafer10is, for example, a silicon wafer. In the wafer10, the portions R are arranged, for example, in a lattice pattern so as to be adjacent to each other. Dicing lines L are set on the boundary between the portions R.

In the first step, first, the antireflection layer21is formed on the first surface11aof the portion R, and at the same time, the antireflection layer41is formed on the second surface11bof the portion R. Subsequently, the polysilicon layer25a, the silicon nitride layer26a, the polysilicon layer25b, the silicon nitride layer26b, and the polysilicon layer25cconstituting the first laminate22are laminated in this order on the antireflection layer21. Simultaneously with the lamination of the first laminate22, the polysilicon layer and the silicon nitride layer constituting the third laminate42are laminated on the antireflection layer41. At the time of lamination of the first laminate22, after the polysilicon layer25and the silicon nitride layer26are laminated over the first surface11a, portions of the polysilicon layer25and the silicon nitride layer26, which are positioned on the outer edge portion11c, when viewed from the direction perpendicular to the first surface11aare removed by etching. In addition, in parallel with the lamination of the first laminate22, the first electrode12and the second electrode13are formed by doping impurities into the polysilicon layers25band25cto partially lower the resistance thereof. Subsequently, trenches17and18are formed by etching.

Subsequently, as illustrated inFIG. 4(b), the intermediate layer23having the removal scheduled portion50corresponding to the air gap S is formed for each portion R (second step). In the second step, first, the intermediate layer23is formed over the first surface11aof the portion R so that the first laminate22is covered with the intermediate layer23. Simultaneously with the formation of the intermediate layer23, the intermediate layer43is formed on the third laminate42. Subsequently, the portion of the intermediate layer23positioned on the outer edge portion11cwhen viewed from the direction perpendicular to the first surface11ais removed by etching. During this etching, the portion of the antireflection layer21positioned on the outer edge portion11cwhen viewed from the direction perpendicular to the first surface11ais removed. In addition, during this etching, the air gap is formed in the portion corresponding to the wiring13aand terminals15and16inFIG. 3.

Subsequently, as illustrated inFIGS. 5(a), 5(b), and 6(a), the second laminate24having the second mirror portion32in which the plurality of through holes24bare formed, the covering portion33which covers the intermediate layer23, and the peripheral edge portion34which is thinned along the outer edge of the outer edge portion11cis formed for each portion R (third step).

In the third step, first, the polysilicon layer27a, the silicon nitride layer28a, the polysilicon layer27b, the silicon nitride layer28b, and the polysilicon layer27cconstituting the second laminate24are laminated in this order on the intermediate layer23. More specifically, as illustrated inFIG. 5(a), the second laminate24is laminated over the first surface11aof the portion R so that the surface23aand the side surface23bof the intermediate layer23, the side surface22aof the first laminate22, and the side surface21aof the antireflection layer21are covered with the second laminate24. Simultaneously with the lamination of the second laminate24, the polysilicon layer and the silicon nitride layer constituting the fourth laminate44are laminated on the intermediate layer43. Subsequently, as illustrated inFIG. 5(b), by removing the portions of the polysilicon layer27other than the polysilicon layer27aand the silicon nitride layer28corresponding to the thinned portion34bby etching, the peripheral edge portion34thinned along the outer edge of the outer edge portion11cis formed. In addition, in parallel with the lamination of the second laminate24, the third electrode14is formed by doping impurities into the polysilicon layer27ato partially lower the resistance thereof. Subsequently, terminals15and16are formed.

Subsequently, as illustrated inFIG. 6(a), by partially etching the second laminate24, the through holes24bextending from the surface24aof the second mirror portion32to the removal scheduled portion50are formed. Subsequently, a light shielding layer45is formed on the fourth laminate44. Subsequently, by removing the portions of the third laminate42, the intermediate layer43, the fourth laminate44, and the light shielding layer45overlapping with the thinned portion34bwhen viewed from the perpendicular direction by etching, the third laminate42, the intermediate layer43and the fourth laminate44are thinned along the outer edge of the outer edge portion11c. In addition, during this etching, opening40ais formed in the third laminate42, the intermediate layer43, the fourth laminate44, and the light shielding layer45. Subsequently, the protective layer46is formed on the surface of the light shielding layer45and on the inner surface of the opening40a.

Subsequently, as illustrated inFIG. 6(b), by removing the removal scheduled portion50by etching through the through holes24b, the air gap positioned between the first mirror portion31and the second mirror portion32S is formed for each portion R (fourth step). In the fourth step, the removal scheduled portion50is removed by gas phase etching through the through holes24b. For this gas phase etching, for example, a hydrofluoric acid gas is used.

Subsequently, as illustrated inFIG. 6(b), the Fabry-Perot interference filter1is obtained by cutting the wafer10along the outer edge of the outer edge portion11cin the dicing lines L (fifth step). In the fifth step, for example, the wafer10is cut along the outer edge of the outer edge portion11cby forming a modified region in an inner portion of the wafer10along the outer edge of the outer edge portion11cby irradiation with a laser beam from the first surface11aside and by extending a crack in the thickness direction of the wafer10from the modified region.

As described above, in the method for producing the Fabry-Perot interference filter1, after forming the second laminate24having the covering portion33covering the intermediate layer23, the removal scheduled portion50of the intermediate layer23is removed by etching. Therefore, it is possible to suppress deterioration of the intermediate layer23at the time of removing the removal scheduled portion50by etching. Furthermore, in the method for producing the Fabry-Perot interference filter1, after forming the second laminate24having the peripheral edge portion34thinned along the outer edge of the outer edge portion11c, the Fabry-Perot interference filter1is obtained by cutting the wafer10along the outer edge of the outer edge portion11c. Therefore, it is possible to suppress deterioration of each layer on the substrate11at the time of cutting the wafer10. In addition, in the Fabry-Perot interference filter1produced by the method for producing the Fabry-Perot interference filter1, because the intermediate layer23is covered with the second laminate24, peeling of the intermediate layer23is suppressed. As described above, according to the method for producing the Fabry-Perot interference filter1, it is possible to suppress the occurrence of peeling in each layer on the substrate11.

In addition, in the method for producing the Fabry-Perot interference filter1, the wafer10is cut by forming a modified region in an inner portion of the wafer10by irradiation with a laser beam and by extending a crack from the modified region in the thickness direction of the wafer10. By forming the thinned portion34b, it is possible to preferably focus the laser beam on an inner portion of the wafer10, and thus, it is possible to cut the wafer10with a high accuracy.

Although an embodiment of the present disclosure has been described above, an aspect of the present disclosure is not limited to the embodiment described above. For example, the materials and shapes of the respective components are not limited to the above-described materials and shapes, and various materials and shapes can be adopted.

The peripheral edge portion34may be thinned by entirely removing the polysilicon layer27and the silicon nitride layer28in the thinned portion34b. In this case, when viewed from the direction perpendicular to the first surface11a, the outer edge of the peripheral edge portion34is positioned inside the outer edge portion of the outer edge portion11c. In the thinned portion34b, the polysilicon layer27or the silicon nitride layer28may be further disposed on the polysilicon layer27a. That is, the thickness of the portion of the peripheral edge portion34along the outer edge of the outer edge portion11cmay be smaller (including zero) than the thickness of the other portion excluding the portion of the peripheral edge portion34along the outer edge of the outer edge portion11c. The third laminate42, the intermediate layer43, and the fourth laminate44may be thinned by removing a portion of each layer in a region overlapping with the thinned portion34bwhen viewed from the direction perpendicular to the first surface11a. In other words, the thickness of the portions of the third laminate42, the intermediate layer43, and the fourth laminate44along the outer edge of the outer edge portion11cmay be smaller (including zero) than the thickness of the other portions excluding the portions of the third laminate42, the intermediate layer43, and the fourth laminate44along the outer edge of the outer edge portion11c.

The first laminate22may be interposed between the peripheral edge portion34and the first surface11aof the outer edge portion11c. In this case, when viewed from the direction perpendicular to the first surface11a, the outer edge of the first laminate22may be positioned between the outer edge of the intermediate layer23and the outer edge of the outer edge portion11cand may coincide with the outer edge of the outer edge portion11c. In this case, the portion (peripheral edge portion) positioned on the first surface11aof the outer edge portion11cin the first laminate22may be thinned along the outer edge of the outer edge portion11c. According to this configuration, even in a case where the Fabry-Perot interference filter1is obtained by cutting the wafer10including the portion R corresponding to the substrate11along the outer edge of the outer edge portion11c, it is possible to more preferably suppress deterioration of each layer on the substrate11. Furthermore, because the peripheral edge portion of the first laminate22is thinned along the outer edge of the outer edge portion11c, in a case where the wafer10is cut by forming a modified region in an inner portion of the wafer10by irradiation with a laser beam and by extending a crack in the thickness direction of the wafer10from the modified region, it is possible to more preferably irradiate the inner portion of the wafer10with the laser beam. In a case where the outer edge of the first laminate22coincides with the outer edge of the outer edge portion11c, the peripheral edge portion34does not cover the outer edge of the first laminate22.

The Fabry-Perot interference filter1may not have a laminate structure (the antireflection layer41, the third laminate42, the intermediate layer43, the fourth laminate44, the light shielding layer45, and the protective layer46) provided on the second surface11bof the substrate11. The third laminate42, the intermediate layer43and the fourth laminate44may not be thinned along the outer edge of the outer edge portion11c. In the fifth step, the wafer10may be cut by another dicing method such as blade dicing. In the above-described embodiment, the thinned portion34bcontinuously surrounds the non-thinned portion34a. However, the thinned portion34bmay intermittently surround the non-thinned portion34a. That is, the peripheral edge portion34may be thinned along at least a portion of the outer edge of the outer edge portion11c.

In the above-described embodiment, the peripheral edge portion34may not be thinned along the outer edge of the outer edge portion11c. Even in this case, because the intermediate layer23is covered with the second laminate24, peeling of the intermediate layer23is suppressed. In addition, because the covering portion33covers the outer edge of the first laminate22and the first laminate22is covered with the second laminate24, peeling of the first laminate22is suppressed.

As in the Fabry-Perot interference filter1A of Modified Example 1 illustrated inFIG. 8(a), in the Fabry-Perot interference filter1of the above-described embodiment, the outer edge of the polysilicon layer25cmay be positioned inside the outer edge of the first laminate22when viewed from the direction perpendicular to the first surface11a, and the intermediate layer23may be interposed between the outer edge of the polysilicon layer25cand the polysilicon layer27a. According to Modified Example 1, similarly to the above-described embodiment, it is possible to suppress the occurrence of peeling in each layer on the substrate11. Furthermore, in Modified Example 1, the electrical insulation between the polysilicon layer25cin which the first electrode12is formed and the polysilicon layer27ain which the third electrode14is formed can be enhanced. Therefore, it is possible to suppress the occurrence of leakage of current between the first electrode12and the third electrode14through the polysilicon layers25cand27a. As a result, it is possible to suppress an increase in the voltage applied between the first electrode12and the third electrode14.

As in the Fabry-Perot interference filter1B of Modified Example 2 illustrated inFIG. 8(b), in the Fabry-Perot interference filter1A of Modified Example 1, a trench52extending annularly so as to surround the terminals15and16may be provided with the polysilicon layer27a. According to Modified Example 2, similarly to the above-described embodiment, it is possible to suppress the occurrence of peeling in each layer on the substrate11. Furthermore, in Modified Example 2, the electrical insulation between the polysilicon layer25cin which the first electrode12is formed and the polysilicon layer27ain which the third electrode14is formed can be further enhanced. Therefore, it is possible to further suppress the occurrence of leakage of current between the first electrode12and the third electrode14through the polysilicon layers25cand27a.

As in the Fabry-Perot interference filter1C of Modified Example 3 illustrated inFIG. 9(a), in the Fabry-Perot interference filter1of the above-described embodiment, the trench52extending annularly so as to surround the terminals15and16may be provided with the polysilicon layer27a, and a trench53extending annularly so as to surround the terminals15and16may be provided with the polysilicon layer25c. According to Modified Example 3, similarly to the above-described embodiment, it is possible to suppress the occurrence of peeling of each layer on the substrate11. Furthermore, in Modified Example 3, the electrical insulation between the polysilicon layer25cin which the first electrode12is formed and the polysilicon layer27ain which the third electrode14is formed can be enhanced. Therefore, it is possible to suppress the occurrence of leakage of current between the first electrode12and the third electrode14through the polysilicon layers25cand27a.

As in the Fabry-Perot interference filter ID of Modified Example 4 illustrated inFIG. 9(b), in the Fabry-Perot interference filter1of the above-described embodiment, the outer edge of the first laminate22may be positioned inside the outer edge of the intermediate layer23when viewed from the direction perpendicular to the first surface11a, and the intermediate layer23may be interposed between the outer edge of the first laminate22and the second laminate24. According to Modified Example 4, similarly to the above-described embodiment, it is possible to suppress the occurrence of peeling of each layer on the substrate11. Furthermore, in Modified Example 4, the electrical insulation between the polysilicon layer25cin which the first electrode12is formed and the polysilicon layer27ain which the third electrode14is formed can be enhanced. As a result, it is possible to effectively suppress the occurrence of leakage of current between the first electrode12and the third electrode14through the polysilicon layers25cand27a.

As in the Fabry-Perot interference filter1E of Modified Example 5 illustrated inFIG. 10, in the Fabry-Perot interference filter1of the above-described embodiment, the portion covering the outer edge of the first laminate22and the intermediate layer23in the polysilicon layer27amay be removed. According to Modified Example 5, similarly to the above-described embodiment, it is possible to suppress the occurrence of peeling in each layer on the substrate11. Furthermore, in Modified Example 5, because the polysilicon layer25cis covered with the silicon nitride layer28a, the electrical insulation between the polysilicon layer25cin which the first electrode12is formed and the polysilicon layer27ain which the third electrode14is formed can be enhanced. Therefore, it is possible to suppress the occurrence of leakage of current between the first electrode12and the third electrode14through the polysilicon layers25cand27a.

REFERENCE SIGNS LIST