JP2014048402A - Optical filter member and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a filter member capable of further reducing incident angle dependency.SOLUTION: An optical filter member 3 includes a substrate 31 comprising an infrared absorbing glass and an optical film provided on a surface of the substrate 31. The optical film includes a first dielectric multilayer film 32 and a second dielectric multilayer film 33, each having a plurality of dielectric layers with different refractive indices. An average refractive index in the entire second dielectric multilayer film 33 is higher than an average refractive index in the entire first dielectric multilayer film 32.

Description

  The present invention relates to an optical filter member and an imaging device.

  For example, an optical filter member having a structure in which an optical film is formed on the surface of borosilicate glass as a part for blocking infrared rays included in a wavelength range outside the visible range in a color imaging device having an imaging element such as a CCD or CMOS Has been used. In a color imaging device or the like, when infrared rays included in a wavelength range outside the visible region are incident on the imaging element, an imaging filter is used, and thus an optical filter that blocks infrared rays is used. The optical film in the optical filter is obtained by alternately stacking, for example, 40 to 50 layers of two types of optical layers having different refractive indexes. Note that the imaging apparatus may include a lens that collects light on the optical filter member.

JP 2008-60121 A

  With the recent thinning of the imaging device, the distance between the lens and the optical filter member has been reduced, and the light incident on the central region of the optical filter member and the light incident on the peripheral region of the optical filter member The difference in the incident angle of light is increasing. Since the optical layer constituting the optical film has different optical characteristics depending on the difference in the incident angle of light, the difference in the incident angle of the light tends to cause a difference in the hue near the center of the captured image, for example, so-called ghost. Since it is likely to occur, the quality of the image may be affected. There is also a demand for improving the image quality in the optical filter member by improving the transmittance of light in a desired wavelength range.

  An optical filter member according to one aspect of the present invention includes a base made of infrared absorbing glass and an optical film provided on the surface of the base. The optical film includes a first dielectric multilayer film and a second dielectric multilayer film in which a plurality of dielectric layers having different refractive indexes are stacked. The average refractive index of the entire second dielectric multilayer film is higher than the average refractive index of the entire first dielectric multilayer film.

  An imaging apparatus according to another aspect of the present invention includes the optical filter member having the above-described configuration and an imaging element provided below the optical filter member.

In the optical filter member according to one aspect of the present invention, the optical film includes a first dielectric multilayer film and a second dielectric multilayer film in which a plurality of dielectric layers each having a different refractive index are laminated. Since the average refractive index of the entire second dielectric multilayer film is higher than the average refractive index of the entire first dielectric multilayer film, the optical filter member according to one aspect of the present invention has a difference in light incident angle. Therefore, it is possible to reduce the difference in color between the vicinity of the center of the captured image and the periphery of the captured image, and it is possible to realize an imaging apparatus with improved image quality. In addition, in the optical filter member according to one aspect of the present invention, since the base is made of infrared absorbing glass, an image can be obtained with a natural hue and an image pickup apparatus with improved image quality can be realized. Therefore, the optical filter member according to one aspect of the present invention improves the image quality by reducing the difference in hue between the vicinity of the center of the captured image and the periphery due to the difference in the incident angle of light while making the image a natural hue. It is possible to realize the image pickup apparatus.

  An image pickup apparatus according to another aspect of the present invention includes the optical filter member having the above-described configuration, so that changes in optical characteristics due to a difference in the incident angle of light in the optical filter member are reduced while making an image have a natural hue. And the quality of the captured image is improved.

It is a longitudinal cross-sectional view which shows the imaging device in embodiment of this invention. It is a longitudinal cross-sectional view which shows the optical filter member in the imaging device shown by FIG. FIG. 3 is an enlarged view of a portion indicated by reference numeral A in the optical filter member shown in FIG. 2. It is a figure which shows the other example of the optical filter member shown by FIG. (A) is a graph which shows the permeation | transmission characteristic of the base | substrate in the optical filter member of embodiment of this invention, (b) is a graph which shows the permeation | transmission characteristic of a 1st dielectric multilayer, (c) is 2nd 2 is a graph showing the transmission characteristics of the dielectric multilayer film, and FIG. 4D is a graph showing the transmission characteristics of the optical filter member. (A)-(d) is a longitudinal cross-sectional view which shows the manufacturing process of the optical filter member shown by FIG. It is a longitudinal cross-sectional view which shows the other example of the optical filter member shown by FIG. (A) is a graph which shows the permeation | transmission characteristic of the base | substrate in the conventional optical filter member, (b) is a graph which shows the permeation | transmission characteristic of a 1st dielectric multilayer, (c) is a 2nd dielectric multilayer It is a graph which shows the permeation | transmission characteristic of a film | membrane, (d) is a graph which shows the permeation | transmission characteristic of the conventional optical filter member.

  Hereinafter, an optical filter member in an exemplary embodiment of the present invention will be described with reference to the drawings.

  First, an example of an imaging apparatus having the optical filter member 3 in the embodiment of the present invention will be described with reference to FIG. The imaging device includes an element mounting member 1, an imaging element 2 mounted on the element mounting member 1, and an optical filter member 3 provided above the imaging element 2. The optical filter member 3 in the present embodiment blocks a specific wavelength range in light incident on the imaging device.

  Next, details of the optical filter member 3 in the present embodiment will be described with reference to FIGS. Other configurations of the imaging apparatus will be described later.

  The optical filter member 3 includes a base 31 made of infrared-absorbing glass and an optical film provided on the surface of the base 31. The optical film is formed by laminating a plurality of dielectric layers each having a different refractive index. 1 dielectric multilayer film 32 and second dielectric multilayer film 33, and the average refractive index of the entire second dielectric multilayer film 33 is higher than the average refractive index of the entire first dielectric multilayer film 32. high.

The base 31 is made of infrared absorbing glass. As shown in FIG. 5A, the infrared absorbing glass has a reduced transmittance of infrared rays included in a wavelength range larger than 700 nm, and is, for example, blue transparent. Note that the infrared absorbing glass transmits visible light included in the range of 400 nm to 700 nm. The transmittance of the substrate 31 is about 30% longer when the incident angle is 40 degrees than when the incident angle is 0 degrees, and the transmittance decreases overall, but the transmittance of the substrate 31 is reduced in the infrared region side. The wavelength at the half value of the peak transmittance is substantially the same wavelength, and the wavelength at the half value of the peak transmittance does not depend on the incident angle.

The base 31 is made of, for example, a container made of a metal having a melting point higher than the melting temperature of glass (preferably platinum (Pt, for example) so as to effectively reduce the amount of impurities dissolved). ) And then gradually cooled over several days to form a block shape. Thereafter, it is cut into a predetermined thickness and outer dimensions. Thereafter, lapping is performed using an abrasive made of alumina or the like, and optical polishing is performed using an abrasive made of alumina, cerium oxide, or the like, and the substrate 31 is obtained by dividing. By manufacturing in this way, it is possible to reduce the amount of impurities that generate α-rays that affect the image sensor and dissolve in the high-purity glass material. In addition, as an infrared absorbing glass having a characteristic of transmitting visible light and absorbing infrared light, for example, phosphate glass containing copper oxide is widely known. This is because when Cu ²⁺ is present in a glass network former mainly composed of P ₂ O _5, hexacoordination having an absorption band in the vicinity of a wavelength of 800 nm is more easily obtained than tetracoordination having absorption in visible light. It is to become. With such a relationship between the P ₂ O ₅ component and Cu ²⁺ , it becomes possible to obtain a glass having both visible light transmittance, infrared light absorption, and sharp cutting properties.

The base 31 preferably has a thickness included in the range of 0.03 mm to 0.5 mm, for example. By being 0.03 mm or more, a sufficient effect of infrared absorption by the substrate 31 can be obtained, and absorption characteristics in the infrared region can be satisfied with respect to light incident on the optical filter member 3 from an oblique direction. The shut-off characteristic of the outer region can be improved. Further, the strength of the base 31 can be sufficiently obtained. When the thickness of the base 31 is 0.5 mm or less, the thickness can be reduced, and the height of the imaging device can be reduced.

In the present invention, even if the transmittance of the substrate 31 in the infrared region is larger than the transmittance of the filter made of only infrared absorbing glass, most of the infrared rays are blocked by the first dielectric multilayer film 32. Therefore, the infrared absorbing glass can be made thinner. The reflectance of the base 31 is about several percent over the range from 200 nm to 1200 nm.

As shown in FIG. 5B, the first dielectric multilayer film 32 has a reduced transmittance of ultraviolet rays included in a wavelength range smaller than 400 nm, and has a wavelength larger than 700 nm. The transmittance of infrared rays included in the range is reduced. In order to obtain such filter characteristics, a first high refractive index dielectric layer 32a made of a dielectric material having a refractive index of 1.7 or more and a first low refractive index dielectric made of a dielectric material having a refractive index of 1.6 or less. The body layer 32b is formed by laminating a plurality of layers alternately over 40 to 50 layers by vapor deposition or sputtering. The first dielectric multilayer film 32 is shorter on the infrared region side by about 40 nm when the incident angle is 40 degrees than when the wavelength at the half value of the peak transmittance of the first dielectric multilayer film 32 is 0 degrees. It shifts to the wavelength side.

As shown in FIG. 5C, the second dielectric multilayer film 33 has a reduced transmittance of ultraviolet rays included in a wavelength range smaller than 400 nm, and has a wavelength larger than 650 nm. The transmittance of infrared rays included in the range is reduced. In order to obtain such filter characteristics, the second high-refractive-index dielectric layer 33a made of a dielectric material having a refractive index of 2.0 or more and a dielectric having a refractive index smaller by 0.1 or more than the second high-refractive-index dielectric layer 33a. The second low-refractive-index dielectric layer 33b made of a body material is formed by laminating a plurality of layers alternately and successively over 40 to 50 layers using a vapor deposition method or a sputtering method. The second dielectric multilayer film 33 is shorter on the infrared region side by about 20 nm when the wavelength at the half value of the peak transmittance of the second dielectric multilayer film 33 is an incident angle of 40 degrees than when the incident angle is 40 degrees. It shifts to the wavelength side. Even at the maximum incident angle predicted in advance, the wavelength at the half value of the peak transmittance of the second dielectric multilayer film 33 is set shorter than the wavelength at the half value of the peak transmittance of the first dielectric multilayer film 32. The wavelength at the half value of the peak transmittance of the second dielectric multilayer film 33 can be set to the wavelength at the half value of the peak transmittance of the light passing through the optical film. The angle dependency of the transmittance can be reduced.

The average refractive index of the entire first dielectric multilayer film 32 is n32, the average refractive index of the entire second dielectric multilayer film 33 is n33, and the first and second high refractive index dielectric materials 32a, 33a, and The refractive index of each layer of each of the first and second low refractive index dielectric materials 32b and 33b is n1, n2, n3, n4, the number of layers is p1, p2, p3, p4, and the thickness of each layer. Is t1, t2, t3, t4, the average refractive indexes n32, n33 can be expressed as follows.
n32 = (n1 * p1 * t1 + n2 * p2 * t2) / (p1 * t1 + p2 * t2)
n33 = (n3 * p3 * t3 + n4 * p4 * t4) / (p3 * t3 + p4 * t4)
n33> n32.

As will be described later, the first dielectric multilayer film 32 and the second dielectric multilayer film 33 are preferably formed by ion beam assisted deposition. As shown in FIG. 5D, the optical filter member 3 in which the above is combined has reduced transmittance of ultraviolet rays included in a wavelength range smaller than 400 nm, and has a wavelength range larger than 650 nm. The transmittance of the infrared rays contained in is reduced. The transmittance of the optical filter member 3 at each wavelength is the product of the transmittance of the substrate 31, the transmittance of the first dielectric multilayer film 32, and the transmittance of the second dielectric multilayer film 33 at each wavelength.

  Since the influence of the light incident angle on the optical film is larger than the influence of the light incident angle on the substrate 31 made of infrared absorbing glass, the light incident angle on the entire optical filter member 3 is reduced by reducing the influence of the light incident angle on the optical film. The influence of can be reduced.

  Further, in the optical filter member 3 according to one aspect of the present invention, the wavelength at the half value of the peak transmittance of the optical film is larger than the wavelength at the half value of the peak transmittance of the substrate 31 on the infrared region side. Similar to the above, the characteristics of the second dielectric multilayer film 33 mainly affect only the wavelength region larger than the peak transmittance region of the second dielectric multilayer film 33. Since the transmittance is already less than half value, the influence on the imaging characteristics is smaller.

Examples of the high refractive index dielectric material 32a having a refractive index of 1.7 or more suitable for the first dielectric multilayer film 32 include tantalum pentoxide (refractive index: 2.16), titanium oxide (refractive index: 2.52), There are niobium pentoxide (refractive index: 2.33), lanthanum oxide (refractive index: 1.88), zirconium oxide (refractive index: 2.40), and the like. As the low refractive index dielectric material 32b having a refractive index of 1.6 or less, for example, silicon oxide (Refractive index: 1.46), lanthanum fluoride (refractive index: 1.59) or magnesium fluoride (refractive index: 1.38). From the viewpoint of mechanical properties such as hardness or stability, and optical properties such as refractive index necessary for providing a function as a desired optical filter, titanium oxide is used as the high refractive index dielectric layer 32a. It is desirable to use silicon oxide as the refractive index dielectric layer 32b.

For example, tantalum pentoxide (refractive index: 2.16), titanium oxide (refractive index: 2.52), quintoxide may be used as the high refractive index dielectric material 33a having a refractive index of 2.0 or more suitable for the second dielectric multilayer film 33. There are niobium oxide (refractive index: 2.33), zirconium oxide (refractive index: 2.40), and the like. As the low refractive index dielectric material 33b whose refractive index is 0.1 or more smaller than that of the high refractive index dielectric material, for example, titanium oxide (refractive For the rate: 2.52), there are tantalum pentoxide (refractive index: 2.16), niobium pentoxide (refractive index: 2.33) or zirconium oxide (refractive index: 2.40). Each of the dielectric materials may be used in accordance with the refractive index of the dielectric material used. However, in order to reduce the angular dependence of the second dielectric multilayer film 33, the dielectric having a high refractive index of the second dielectric multilayer film 33 is used. The average refractive index of the body material 33a and the low-refractive index dielectric material 33b is preferably as large as possible, but is necessary for imparting mechanical properties such as hardness or stability and a function as a desired optical filter. From optical characteristics such as refractive index, it is desirable to use titanium oxide as the high refractive index dielectric layer 33a and tantalum pentoxide as the low refractive index dielectric layer 33b.

  As described above, the optical film is preferably formed by an ion beam assisted deposition method. The ion beam assisted vapor deposition method is a vacuum vapor deposition method in which cation irradiation is used in combination with a vacuum vapor deposition method that is a film forming process. As the cation used in the ion beam assist method, for example, one generated from a plasma obtained by introducing both an inert gas composed of argon and an active gas composed of oxygen gas into an ion source of the apparatus is used.

In the ion beam assisted vapor deposition method, for example, the base 31 is placed in a vapor deposition dome installed in a vacuum vapor deposition apparatus, and oxygen is supplied sufficiently to prevent oxygen deficiency in order to obtain an optically good optical film. Then, vacuum deposition is performed while using cation irradiation in a state where the degree of vacuum is set to about 1 × 10 ⁻³ Pa in the vacuum deposition apparatus. The surface temperature of the substrate 31 when the optical film is formed in the vacuum deposition apparatus is managed by measuring the temperature in the vicinity of the substrate 31 with a thermocouple, and the temperature range is 30 to 350 ° C. using a heating wire heater or the like. To a degree. After that,
A high refractive index dielectric layer 32a and a low refractive index dielectric layer 32b for forming the first dielectric multilayer film 32 on the entire main surface of the substrate 31 or in a desired region facing the imaging device by masking. Next, in order to form a second dielectric multilayer film, a high refractive index dielectric layer 33a and a low refractive index dielectric layer 33b are alternately and sequentially added in combination with a cation irradiation for a total of 10 to 30 By applying a dielectric layer of about one layer, a mother optical filter member 3 ′ to be the optical filter member 3 on which an optical film is formed is obtained.

  When the cations collide with the gas molecules of the vapor deposition material flying in the vacuum, the gas molecules of the vapor deposition material are excited to obtain a large kinetic energy. Then, when the gas molecules of the vapor deposition material that have obtained this large kinetic energy reach the surface of the substrate 31 that is the adherend, it moves over a wide area of the surface of the adherend and adheres as the wide area moves. Since the probability of finding a place in a lower energy state on the surface of the material is greatly increased, the molecules of the deposited material are uniformly deposited on the surface of the deposited material without agglomeration, and the deposited atoms existing around A densely packed optical film can be formed without agglomerating and forming nuclei.

  The dielectric layer directly formed on the surface of the substrate 31 is preferably a Si film having high adhesion to glass because adhesion between the substrate 31 and the optical film is improved. In addition, since the substrate 31 made of infrared absorbing glass is relatively weak against moisture, the optical film preferably includes a barrier layer having a property that moisture cannot easily pass through. Examples of the structure in which the optical film includes a barrier layer include a structure in which a part of the optical film in the thickness direction is a barrier layer, or a structure in which the entire optical film in the thickness direction is a barrier layer. If the entire thickness direction of the optical film is a barrier layer, it is preferable because the possibility of moisture passing through the optical film and reaching the surface of the substrate 31 is further reduced. As a result, the weather resistance of the optical filter member 3, specifically, the problem that fogging occurs on the surface of the base 31 due to the infrared absorbing glass by the high temperature and high humidity test is improved.

  One example of a structure in which a part of the optical film in the thickness direction is a barrier layer is a structure in which the optical film has a water-resistant coating layer 34 as shown in FIG. That is, the water resistant coating layer 34 is a barrier layer. The water-resistant coating layer 34 has a stronger property against moisture than the base 31 made of infrared absorbing glass, and is made of, for example, a silicone material. In order to protect the surface of the base 31, the water-resistant coating layer 34 is preferably in direct contact with the surface of the base 31 as in the example shown in FIG. 4.

  As another example of the structure in which a part in the thickness direction of the optical film is a barrier layer, in the structure shown in FIG. 3, a plurality of high-refractive index dielectric layers 32a and 33a and low-refractive index dielectric layers 32b and 33b are used. Some of them are formed by ion beam assisted deposition to be amorphous. A part of the plurality of high-refractive index dielectric layers 32a and 33a and low-refractive index dielectric layers 32b and 33b are made amorphous, so that it is difficult for moisture to pass therethrough.

It should be noted that the stress of the optical film can be reduced by forming a barrier layer by ion beam assisted vapor deposition only on the part close to the surface of the substrate 31, not the entire optical film, and not using ion beam assisted vapor deposition for other parts. The optical filter member 3 can be adjusted in a wider range, and is difficult to warp even if the base 31 is thin. In this case, if the barrier layer has a thickness of about 150 nm or more, it becomes easy to reduce moisture permeation. Further, as an example of the structure in which the entire thickness direction of the optical film is a barrier layer, in the structure shown in FIG. 3, a plurality of high-refractive index dielectric layers 32a and 33a and low-refractive index dielectric layers 32b and 33b are used. Some of them are made amorphous by ion beam assisted deposition.

  In addition, if the outermost layer of the optical film is formed into an amorphous film that is easily amorphized and has good weather resistance, it is difficult for moisture to enter the optical film from the outside. Since it becomes difficult to change, it is more preferable.

  Note that by forming an optical film by ion beam assisted vapor deposition, not only a Si film that is easily amorphized but also a film using other elements is easily amorphized. As a result, the water permeability of the optical film is further reduced, so that the optical film functions as a barrier layer against moisture, so that the surface of the substrate generally made of an infrared absorbing glass having low water resistance reacts with moisture. Thus, it is possible to prevent a decrease in light transmittance generated in this manner, and the water resistance reliability is improved.

  Further, in the optical filter member 3 of the present embodiment, when the optical film includes a barrier layer having a property of preventing moisture from passing through, the substrate 31 made of infrared absorbing glass having a relatively weak property against moisture. Deterioration of the surface of the optical film is reduced. For example, the possibility of peeling of the optical film is reduced.

  Further, in the optical filter member 3 of the present embodiment, when the barrier layer is formed by an ion beam assisted deposition method, the barrier layer is amorphized, and the possibility of moisture permeating through the optical film is reduced. Yes.

  Further, in the optical filter member 3 of the present embodiment, when the barrier layer is provided on the surface of the base 31, the protection of the surface of the base 31 is improved.

  In addition, since the imaging apparatus according to the present embodiment includes the optical filter member 3 described above, the change in optical characteristics due to the difference in the incident angle of light in the optical filter member is reduced, and the quality of the captured image is improved. Has been.

  Hereinafter, the element mounting member 1 and the imaging element 2 of the above-described imaging apparatus will be described in more detail. The element mounting member 1 includes a substrate 11 and a frame body 12 joined to the substrate 11 so as to sandwich the lead terminal 13 therebetween.

  The substrate 11 is made of a ceramic such as an aluminum oxide sintered body (alumina ceramic), a mullite sintered body, a steatite sintered body, or an aluminum nitride sintered body.

  The substrate 11 can be manufactured as follows. For example, if the substrate 11 is made of an aluminum oxide sintered body, first, an appropriate organic binder, solvent, plasticizer, and dispersant are added to the raw material powder such as aluminum oxide, silicon oxide, magnesium oxide, and calcium oxide. Then, a slurry is made, and this slurry is granulated using a conventionally known spray drying method. Next, this granule is press-molded with a press mold of a predetermined shape to produce a production mold body, and the production mold body is baked at a high temperature of about 1500 ° C. to form the substrate 11. A green sheet is produced using the above raw material powder, and the green sheet is punched out with a mold or the like to obtain an appropriate size. A plurality of green sheets may be laminated to a predetermined thickness.

  It is preferable to flatten the surface of the substrate 11 by lapping or the like so as to have a flatness of 20 μm or less because tilting and distortion are less likely to occur when the imaging device 2 is mounted. If the portion of the outer peripheral portion of the mounting portion facing the frame is also made flat, the frame is joined without tilting, and the optical filter member 3 bonded thereon is not tilted with respect to the image sensor 7. Therefore, it is preferable.

  The lead terminal 13 is made of metal such as Fe—Ni—Co alloy, Fe—Ni alloy, copper (Cu), or copper alloy. From the viewpoint of hermetic reliability, those having a small thermal expansion coefficient with respect to the thermal expansion coefficient of the substrate 11 are preferable. If the substrate 11 is made of an aluminum oxide sintered body, for example, Fe-42% Ni Alloys are preferred. A nickel plating layer and a gold plating layer may be sequentially deposited on the surface of the lead terminal 13 in order to prevent corrosion and improve conductivity.

  The lead terminal 13 is a lead frame having a shape in which a plurality of lead terminals are expanded so as to extend inward from the inner periphery of the frame by punching a plate material made of the above metal using a die. A plurality of lead terminals 13 are obtained by separating the frame after connecting the frame to the mounting substrate. The lead frame can also be manufactured by etching. If a lead frame-shaped resist film is formed on a metal plate and the lead terminal 8c is made of copper, for example, the resist film can be prepared by etching with ferric chloride and then peeling off the resist film.

  The frame 12 is made of ceramics such as an aluminum oxide sintered body (alumina ceramics), a mullite sintered body, a steatite sintered body, or an aluminum nitride sintered body, like the substrate 11, and is mounted on the mounting substrate. It can be produced by a method similar to that described above. It is preferable that the frame 12 and the substrate 11 are made of the same material because the thermal expansion coefficients are the same, so that it is difficult for thermal stress generated between them to be applied to the bonding material 14 or the lead terminal 13 therebetween.

  If the surface of the frame body 12 is also flattened by lapping or the like to have a flatness of 20 μm or less, the frame body 12 is inclined with respect to the mounting substrate 11 and the optical filter member 3 is inclined with respect to the frame body 12. The optical filter member 3 is preferably bonded without being inclined with respect to the image pickup device 2 as a result.

Glass or resin can be used as the bonding material 14 for bonding the substrate 11 and the frame body 12 with the lead frame interposed therebetween. Examples of the glass include low-melting glass such as PbO glass, PbO—SiO glass, BiO—SiO glass, PO—SiO glass, and BO—SiO glass. Examples of the resin include an epoxy resin, a polyimide resin, a polyamideimide resin, and a polyetherimide resin. In any case, in order to make the thermal expansion coefficient close to that of the mounting substrate or the frame, for example, it may contain a filler such as inorganic powder such as silica. When the bonding material is a low-melting glass, for example, a glass component containing 56 to 66% by mass of lead oxide, 4 to 14% by mass of boron oxide, 1 to 6% by mass of silicon oxide, and 1 to 11% by mass of zinc oxide, A glass paste obtained by adding and mixing an appropriate organic solvent and solvent to a powder obtained by adding 4 to 15% by mass of a zirconium oxide silica-based compound powder as a filler is applied to the lower surface of the frame by a printing method such as a screen printing method. The low melting point glass is applied to the frame by printing and coating to a thickness and firing at a temperature of about 430 ° C. This frame is placed on the mounting board with the low melting point glass facing down, and the bonding material is remelted by heating to about 470 ° C with a heating device such as a tunnel-type atmosphere furnace or oven. The periphery of each lead terminal sandwiched between the upper surface of the frame and the outer peripheral edge of the frame is covered with a bonding material, and the frame and the lead terminal are firmly bonded to the mounting substrate by cooling and solidifying the low melting point glass, thereby imaging. An element storage package is produced. When the bonding material is a resin, for example, 10 to 30% by mass of tetrahydromethylphthalic anhydride is added as a curing agent to the main agent made of a liquid epoxy resin of bisphenol A type, and silica powder is added as a filler. The epoxy resin paste obtained by adding 30-80% by mass and adding a colorant such as carbon black and an organic solvent such as 2-methoxyethanol is mixed with the bottom surface of the frame by a printing method such as a screen printing method. The film is printed and applied to a predetermined thickness, and the solvent is dried at a temperature of about 60 ° C. to 80 ° C. to adhere the resin layer to the frame. The frame is placed on the mounting substrate with the bonding material facing down, heated by a heating device such as a tunnel type atmospheric furnace or oven, and held at a peak temperature of about 150 ° C. for 1 hour, thereby forming a resin layer. The periphery of each lead terminal 13 sandwiched between the upper surface of the mounting substrate and the outer peripheral edge of the frame body is covered with resin and cured, and the frame body 12 and the lead terminal 13 are firmly bonded to the substrate 11. The element mounting member 1 is obtained.

The element mounting member 1 manufactured as described above and the optical filter member 3 are generally bonded via an adhesive 5 made of an ultraviolet curable epoxy resin or a thermosetting epoxy resin. For example, when a thermosetting epoxy resin is used as the adhesive 5, the adhesive 5 is applied to the element mounting member 1 or the optical filter member 3 by a conventionally known screen printing method or dispensing method, etc. It is carried out by applying heating at a temperature of ˜150 ° C. for 60 to 90 minutes. The image sensor 2 is a CCD or a CMOS. For example, the imaging element 2 is bonded and fixed to the upper surface of the element mounting member 1 with a conductive adhesive made of an epoxy resin containing silver powder, and the electrodes of the imaging element 2 and the terminals of the element mounting member 1 are made of gold or the like. By connecting the optical filter member 3 to the element mounting member 1 with an adhesive 5 so as to close the opening of the element mounting member 1, the imaging device is obtained.

  Hereinafter, the manufacturing method of the optical filter member 3 will be described with reference to FIG.

As shown in FIG. 6A, the method of manufacturing the optical filter member 3 includes a high refractive index dielectric layer 32a and a low refractive index layer on one main surface of a flat base 31 'made of infrared absorbing glass. A plurality of refractive index dielectric layers 32b are alternately stacked to form a first dielectric multilayer film 32, and a high refractive index dielectric layer 33a and a low refractive index dielectric layer 33b are alternately disposed on the other main surface. A step of forming a mother optical filter member 3 ′ by depositing a plurality of layers to form a second dielectric multilayer film 33, and an outer peripheral portion on the frame body 72 as shown in FIG. A step of closely fixing the other main surface of the mother optical filter member 3 ′ to the supported pressure-sensitive adhesive sheet 71, and a first dielectric of the mother optical filter member 3 ′ as shown in FIG. A plurality of optical filter member regions arranged vertically and horizontally on the mother optical filter member 3 ′ by scanning the multilayer film 32 with an ultraviolet laser. A step of forming a groove 3a ′ whose inner surface is covered with glass melted and solidified, and the mother optical filter member 3 ′ is cleaved along the groove 3a ′ as shown in FIG. 6 (d). Process. As a result, the adjacent first dielectric multilayer films 32 do not collide with each other during the manufacturing process, so that a flat-shaped mother optical filter member 3 in which an optical film is formed on the main surface of the mother optical filter member 3 ′. Even when the optical filter member 3 is formed by sticking 'to the adhesive sheet 71, the optical filter member 3 with less generation of foreign matters can be formed. When the groove 3a ′ is formed by irradiating an ultraviolet laser, when the wavelength of the ultraviolet laser irradiated by the optical film formed on the front surface of the base substrate 31 is reflected at a high rate exceeding 85%, It is necessary to irradiate energy that can be processed even if it is reflected, and since the reflectance changes when processing starts, it becomes difficult to adjust the ultraviolet laser, but the optical film formed on the front surface of the mother substrate 31 irradiates If the wavelength of the ultraviolet laser is absorbed or transmitted by 15% or more, the ultraviolet laser can be efficiently used for forming the groove 3 ', and the change in reflectance during processing becomes small. Since adjustment is also easy, it is preferable.

The pressure-sensitive adhesive sheet 71 generally has a two-layer structure of a support sheet and a pressure-sensitive adhesive layer provided on one surface of the support sheet. Although the thickness of the adhesive sheet 71 is not specifically limited, Usually, it is 30-300 micrometers, Preferably it is 50-100 micrometers. The pressure-sensitive adhesive component of the pressure-sensitive adhesive for the pressure-sensitive adhesive layer can be selected from compounds constituting general-purpose pressure-sensitive adhesives, such as rubber-based, acrylic-based, silicone-based, urethane-based, polyester-based, or A polyvinyl ether type adhesive agent etc. can be mentioned. In some cases, a pressure-sensitive adhesive component may be provided with an absorptivity imparting agent that enhances the absorption rate of the laser beam to form a pressure-sensitive adhesive. The thickness of the pressure-sensitive adhesive layer is not particularly limited, but is usually 1 to 100 μm, preferably 5 to 50 μm.

The frame body 72 is generally in the form of a ring with a linear portion or groove for positioning positioned on the outer periphery, and the mother optical filter member 3 ′ is positioned via the adhesive sheet 71 to prevent the generation of foreign matter. However, it is a jig used for the purpose of mass production or reproducibility, 0.5 mm
In many cases, a metal plate of about 1 mm is formed by etching. If the amount used is large, a mold may be made and injection molded with a thermoplastic resin.

  By forming a pressure-sensitive adhesive layer on the support sheet and forming the pressure-sensitive adhesive sheet 71, the frame 72 is bonded with the pressure-sensitive adhesive layer, and the mother optical filter member 3 'is attached to the pressure-sensitive adhesive layer at the center to perform laser processing. The process can proceed with good mass productivity or reproducibility while preventing the generation of foreign matters.

The laser device is a device that generates light having a uniform wavelength and phase, and in this embodiment, processing is performed using a laser having an ultraviolet wavelength of 266 nm. When an ultraviolet laser is used, the spot diameter can be reduced to about 20 μm or less, so that the influence on the periphery of the portion irradiated with the laser is small.

  In the laser dicing apparatus used in the present embodiment, the first dielectric multilayer film 32 on the upper surface of the mother optical filter member 3 ′ made of infrared absorbing glass fixed to the frame body 72 via the adhesive sheet 71 is focused. The groove 3a ′ is formed in the mother optical filter member 3 ′ by irradiating the laser beam. The energy of the ultraviolet laser beam that has passed through the first dielectric multilayer film 32 is converted into heat at the surface portion of the mother optical filter member 3 'to melt a part of the surface portion of the mother optical filter member 3'. The first dielectric multilayer film 32 is partially evaporated by the heat generated on the surface portion of the base optical filter member 3 '.

The 266 nm ultraviolet laser can reduce the spot diameter to about 20 μm and does not transmit through the infrared absorbing glass, so that the adhesive sheet 71 is not affected by heat and high-precision dimensional processing can be performed. Further, in the portion where the groove 3a 'is formed by the irradiation with the ultraviolet laser, the first dielectric multilayer film 32 and the base 31 are welded at the side portion 3a to form an integral glassy layer. It prevents the intrusion of moisture from the surface, so the optical characteristics change little over time, but the vitreous layer is an amorphous layer formed by ultraviolet laser processing in a short time. The effect of preventing the ingress of moisture is higher.

  Next, the base optical filter member 3 ′ is cleaved to form the optical filter member 3 by pushing up directly below the respective grooves 3 a ′ from the back surface of the adhesive sheet 71.

Next, the optical filter member 3 can be produced by applying the ultraviolet light from the back surface of the adhesive sheet 71 to cure the adhesive sheet 71, reducing the adhesiveness, and picking up the optical filter member 3. The mother optical filter member 3 ′ can be cut using a dicing saw. In that case, the first dielectric multilayer film 32 and the base 31 are not welded.

  As shown in FIG. 7, the optical filter member 3 may be provided with a second dielectric multilayer film 33 on the upper surface of the base 31 so as to overlap the first dielectric multilayer film 32.

  Further, the optical filter member 3 may be provided with a second dielectric multilayer film 33 on the lower surface of the base 31 so as to overlap the first dielectric multilayer film 32.

  It is preferable that the optical filter member 3 is such that the main surface of the base 31 made of infrared absorbing glass having relatively low resistance is not exposed.

  Further, the optical filter member 3 in the present embodiment may have an antireflection film 35 as shown in FIG. The antireflection film 35 reduces the light reflected upward by the element mounting member 1 or the image sensor 2 from being reflected downward by the lower surface of the optical filter member 3 and entering the image sensor 2 as a ghost or flare. Or the first dielectric multilayer film 32 is provided to prevent the light from being reflected from the surface and the amount of light entering the image sensor 2 from decreasing. Thus, the antireflection film 35 is formed on the surface of the optical filter member 3 that comes into contact with the air, and reduces the amount of reflected light.

  The antireflection film 35 includes a high refractive index dielectric layer made of a dielectric material having a refractive index of 1.7 or more and a low refractive index dielectric layer made of a dielectric material having a refractive index of 1.6 or less, for example. It is formed by laminating several layers one after the other by vapor deposition or sputtering.

  As an insulating material having a refractive index of 1.7 or more suitable for the antireflection film 35, for example, tantalum pentoxide, titanium oxide, niobium pentoxide, lanthanum oxide, zirconium oxide, or the like is used, and the refractive index is 1. Examples of the insulating material of 6 or less include silicon oxide, lanthanum fluoride, and magnesium fluoride. From the mechanical properties such as hardness or stability, and the optical properties such as refractive index required to give the function as a desired optical filter, titanium oxide is used as the high refractive index dielectric layer, and low refractive index Silicon oxide is desirable as the dielectric constant layer.

  Since the base 31 made of infrared absorbing glass is relatively weak against moisture, it is preferable to form a barrier layer having a property that moisture cannot easily pass through the upper and lower surfaces of the base 31. Note that it is preferable that the antireflection film 35 includes a barrier layer instead of forming a barrier layer alone, because not only moisture permeation can be prevented but also ghosts and flares can be reduced.

  Examples of the structure in which the antireflection film 35 includes a barrier layer include a structure in which a part of the antireflection film 35 in the thickness direction is a barrier layer, or a structure in which the entire thickness direction of the antireflection film 35 is a barrier layer. If the entire thickness direction of the antireflection film 35 is a barrier layer, it is preferable because the possibility of moisture passing through the antireflection film 35 and reaching the surface of the substrate 31 is further reduced.

  One example of a structure in which a part of the antireflection film 35 in the thickness direction is a barrier layer is a structure in which the antireflection film 35 has a water-resistant coating layer. That is, the water resistant coating layer is a barrier layer.

  As another example of a structure in which a part of the antireflection film 35 in the thickness direction is a barrier layer, a plurality of high-refractive index dielectric layers and a part of low-refractive index dielectric layers are formed by an ion beam assisted deposition method to be amorphous. There is something that has become. A part of the plurality of high-refractive index dielectric layers and low-refractive index dielectric layers is made amorphous, so that it is difficult for moisture to pass therethrough.

  In addition, as an example of a structure in which the entire thickness direction of the antireflection film 35 is a barrier layer, all of a plurality of high-refractive index dielectric layers and low-refractive index dielectric layers are formed by an ion beam assisted deposition method. There is something that has become.

  In the optical filter member 3 according to the present embodiment, when the antireflection film 35 provided on the base 31 includes a barrier layer having a property of preventing moisture from passing through, the optical filter member 3 is, for example, the element mounting member 1. In the process prior to bonding, the deterioration of the surface of the base 31 made of infrared absorbing glass having a relatively weak property against moisture is reduced, and the possibility of peeling of the antireflection film 33, for example, is reduced. ing.

DESCRIPTION OF SYMBOLS 1 ... Member for element mounting 2 ... Imaging element 3 ... Optical filter member
31 ・ ・ ・ ・ ・ Substrate
32 ・ ・ ・ ・ ・ first dielectric multilayer film
32a ... High refractive index dielectric layer
32b ・ ・ ・ ・ Low refractive index dielectric layer
33 ・ ・ ・ ・ ・ Second dielectric multilayer film
33a ... High refractive index dielectric layer
33b ... Low refractive index dielectric layer
34 ・ ・ ・ ・ ・ Water-resistant coating layer
35 ... Anti-reflective coating 4 ... Bonding wire 5 ... Adhesive

Claims (3)

  A first dielectric multilayer comprising a base made of infrared absorbing glass and an optical film provided on the surface of the base, wherein the optical film is formed by laminating a plurality of dielectric layers each having a different refractive index. An optical film comprising a film and a second dielectric multilayer film, wherein an average refractive index of the entire second dielectric multilayer film is higher than an average refractive index of the entire first dielectric multilayer film Filter member.   2. The optical filter member according to claim 1, wherein a wavelength at a half value of the peak transmittance of the optical film is larger than a wavelength at a half value of the peak transmittance of the substrate on the infrared region side. The optical filter member according to claim 1 or 2,
An imaging device comprising: an imaging device provided below the optical filter member.

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