JP2011027643A - Infrared sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an infrared sensor having high sensitivity, low cost and a small environmental load, capable of suppressing peeling of an infrared reflection prevention film or an infrared optical filter film. <P>SOLUTION: In the infrared sensor that includes a package 2 for storing an infrared detection element 1, and a first infrared transmitting member 41 and a second infrared transmitting member 42 for blocking an opening part 2a of the package 2, a space enclosed by the package 2 and the first infrared transmitting member 41 has a vacuum atmosphere. The first infrared transmitting member 41 is formed of ZnS, and fixed to the package 2 by a bonding part 51 including a lead-free glass frit so as to block the opening part 2a from the inside of the package 2, and the second infrared transmitting member 42, wherein the infrared optical filter film 43 and the infrared reflection preventing film 44 are laminated together is formed of Si, and fixed to the package 2 with a bonding part 52 comprising a lead-free conductive adhesive usable at a low temperature, in comparison with the glass frit. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an infrared sensor.

  Conventionally, as shown in FIG. 8, a thermal infrared detecting element 1 ′ for detecting infrared rays, a package 2 ′ for housing the infrared detecting element 1 ′, and a package 2 ′ formed of ZnS which is an infrared transmitting material. The first lens 31 disposed in front of the opening 2a ′ and the second lens 31 made of Si, which is an infrared transmitting material, is fixed to the package 2 ′ so as to close the opening 2a ′ of the package 2 ′. There has been proposed an infrared sensor that includes a lens 32 and includes an optical system that condenses infrared rays on the infrared detection element 1 ′ with the first lens 31 and the second lens 32 (see Patent Document 1). . In this infrared sensor, since the optical system is composed of the first lens 31 and the second lens 32, the aberration of the optical system can be reduced.

  Here, in the infrared sensor having the configuration shown in FIG. 8, an infrared antireflection film is laminated on each of the front and rear surfaces of the first lens 31, and an infrared antireflection film is laminated on the front surface of the second lens 32. An infrared optical filter film (wavelength selective filter film) that blocks infrared rays having a wavelength of less than 8 μm is laminated on the rear surface of the second lens 32.

  In the infrared sensor disclosed in Patent Document 1, the environmental load can be reduced by adopting Si as the infrared transmitting material of the second lens 32 as compared with the case where ZnSe or GaAs is adopted. In addition, the cost can be reduced and the cost can be reduced as compared with the case where Ge is employed.

JP 2006-47343 A

  By the way, the above Patent Document 1 describes that a space surrounded by the package 2 ′ and the second lens 32 is a vacuum atmosphere as one means for increasing the sensitivity of the infrared sensor having the configuration shown in FIG. 8. Has been. Here, in the infrared sensor having the configuration shown in FIG. 8, the second lens 32 needs to be fixed to the package 2 ′ with a low melting point glass in order to ensure airtightness and a desired degree of vacuum. When the second lens 32 is fixed to the package 2 ′, the temperature is increased to about 400 to 600 ° C., and the infrared antireflection film and the infrared optical filter film formed on the second lens 32 are peeled off. It sometimes occurred. Moreover, in the infrared sensor of the structure shown in FIG. 8, it is thought that low melting glass contains lead, and it was not preferable from the point of environmental load.

  The present invention has been made in view of the above-mentioned reasons, and its purpose is to reduce environmental impact and to suppress the peeling of the infrared antireflection film and the infrared optical filter film and to increase the sensitivity and the cost. It is to provide a possible infrared sensor.

  The invention of claim 1 is a heat-type infrared light receiving element, a package made of an inorganic material and containing an infrared detection element, having an opening formed in front of the infrared detection element, and a first infrared transmission material The first infrared transmitting member formed by the first infrared transmitting member fixed to the package so as to close the opening from the inside of the package and the second infrared transmitting material formed to close the opening from the outside of the package. An infrared sensor having a vacuum atmosphere in a space surrounded by the package and the first infrared transmitting member, wherein the package includes a mounting member on which the infrared detection element is mounted; And a cover member joined to the mounting member so as to surround the infrared detecting element between the opening member and the mounting member. The overmaterial is ZnS, the first infrared transmission member is fixed to the cover member with a lead-free glass frit, the second infrared transmission material is Si, and the second infrared transmission member is an infrared optical device. It is characterized in that at least one of a filter film and an infrared antireflection film is laminated, and the second infrared transmission member is fixed to the cover member with a lead-free conductive adhesive or a resin adhesive. To do.

  According to the present invention, the first infrared transmitting member formed of ZnS is fixed to the package with the lead-free glass frit so as to close the opening from the inside of the package, and the package and the first infrared transmitting member are fixed. The space surrounded by the transmissive member is a vacuum atmosphere, and the second infrared transmissive member formed of Si and laminated with at least one of the infrared optical filter film and the infrared antireflection film is compared with the glass frit. Since it is fixed to the package with a lead-free conductive adhesive or resin adhesive that can be used at low temperatures, it has a low environmental impact, and the infrared antireflection film and infrared optical filter film can be peeled off. This can be suppressed, and high sensitivity and low cost can be achieved.

  According to a second aspect of the present invention, in the first aspect of the invention, at least one of the first infrared transmitting member and the second infrared transmitting member is formed in a lens shape for condensing infrared rays on the infrared detecting element. It is characterized by.

  According to the present invention, at least one of the first infrared transmitting member and the second infrared transmitting member is formed in a lens shape that collects infrared rays on the infrared detection element, whereby the first As compared with the case where both the infrared transmissive member and the second infrared transmissive member are formed in a flat plate shape, higher sensitivity can be achieved.

  According to a third aspect of the present invention, in the first aspect of the invention, the second infrared transmitting member is formed in a lens shape that collects infrared rays to the infrared detecting element using a silicon substrate, and the lens A solution that etches and removes oxides of constituent elements of a silicon substrate after an anode having a contact pattern with a silicon substrate designed according to the shape is formed on one surface side of the silicon substrate so that the contact with the silicon substrate is ohmic contact It is characterized by being formed by removing the porous portion after forming a porous portion to be a removal site by anodizing the other surface side of the silicon substrate in the electrolyte solution.

  According to this invention, high sensitivity can be achieved by forming the second infrared transmitting member in a lens shape for condensing infrared rays on the infrared detecting element, and the second infrared transmitting member having the lens shape is provided. Etching the oxide of the constituent elements of the silicon substrate after forming an anode with a contact pattern designed with the silicon substrate according to the lens shape so that the contact with the silicon substrate is ohmic contact on one surface side of the silicon substrate Precise polishing because it is formed by removing the porous part after forming the porous part as the removal site by anodizing the other surface side of the silicon substrate in the electrolytic solution consisting of the solution to be removed The cost of the second infrared transmitting member can be reduced as compared with the case where it is formed using an apparatus.

  The invention of claim 1 has an effect that the environmental load is small, peeling of the infrared antireflection film and the infrared optical filter film can be suppressed, and high sensitivity and cost can be reduced.

It is a schematic sectional drawing of the infrared sensor of Embodiment 1. It is explanatory drawing of the manufacturing method of an infrared sensor same as the above. It is a schematic sectional drawing of the infrared sensor of Embodiment 2. It is principal process sectional drawing for demonstrating the manufacturing method of the 2nd infrared rays transmissive member in an infrared sensor same as the above. It is explanatory drawing of the manufacturing method of the 2nd infrared transmission member in an infrared sensor same as the above. It is a schematic sectional drawing of the infrared sensor of Embodiment 3. It is a schematic sectional drawing of the infrared sensor of Embodiment 4. It is a schematic sectional drawing of the infrared sensor of a prior art example.

(Embodiment 1)
The infrared sensor of the present embodiment is a thermal infrared receiver 1 and a package 2 made of an inorganic material and containing the infrared detector 1, and an opening 2 a is formed in front of the light receiving surface of the infrared detector 1. The package 2, the first infrared transmitting member 41 formed of the first infrared transmitting material and fixed to the package 2 so as to close the opening 2 a from the inside of the package 2, and the second infrared transmitting material. A second infrared transmitting member 42 fixed to the package 2 so as to close the opening 2a from the outside of the package 2, and a space surrounded by the package 2 and the first infrared transmitting member 41 is a vacuum atmosphere. is there.

  In the infrared sensor of the present embodiment, not only the infrared detection element 1 but also a signal processing IC chip 5 that performs signal processing on an output voltage that is an output signal of the infrared detection element 1 is housed in the package 2 described above. . Here, the infrared detection element 1 and the signal processing IC chip 5 are arranged side by side, and pads (not shown) corresponding to each other of the infrared detection element 1 and the signal processing IC chip 5 are bonded wires (see FIG. (Not shown) are electrically connected to each other.

  The above-described package 2 is formed in a rectangular box shape having an opening on one side, and a package body 21 made of a multilayer ceramic substrate (ceramic package) on which the infrared detection element 1 and the signal processing IC chip 5 are mounted on the inner bottom surface side, and the above-described package 2. The package lid 22 is made of a metal lid that has an opening 2 a and is covered on the one surface side of the package body 21, and the infrared transmission members 41 and 42 are fixed to the package lid 22. . Here, the peripheral part of the package lid 22 is joined to a rectangular frame-shaped metal pattern (not shown) formed on the one surface of the package body 21 by seam welding. In the present embodiment, the package body 21 constitutes a mounting member on which the infrared detection element 1 is mounted, and the package lid 22 has an opening 2a and surrounds the infrared detection element 1 between the mounting member. The cover member joined to the mounting member is configured.

  Further, as the infrared detection element 1, an infrared detection element including a thermopile type sensing element as an infrared detection unit is used. However, the infrared detection element is not limited thereto, and an infrared detection element including a bolometer type sensing element as an infrared detection unit. Alternatively, an infrared detection element including a pyroelectric sensing element as an infrared detection unit may be used. In addition, as the infrared detection element 1, an element having only one infrared detection unit may be used, or an element having a plurality of infrared detection units arranged in a two-dimensional array. It may be used.

  The bonding method of the infrared detection element 1 and the signal processing IC chip 5 and the package body 21 is not limited to a bonding method using a conductive adhesive such as lead-free solder or silver paste. A bonding method using Au—Sn eutectic or Au—Si eutectic may be employed. However, the bonding method capable of direct bonding such as the room temperature bonding method improves the distance accuracy between the infrared detecting element 1 and the first infrared transmitting member 41 as compared with the bonding method using the conductive adhesive. Above is advantageous.

  Here, the package body 21 has a conductor pattern (not shown) made of a metal material (for example, Cu) electrically connected to the infrared detection element 1 and the signal processing IC chip 5 on the inner bottom surface side. A plurality of external connection electrodes (not shown) made of a metal material (for example, Cu) electrically connected to each of the conductor patterns are formed across the outer bottom surface and the outer surface. ing. In this embodiment, since the infrared detection element 1 and the signal processing IC chip 5 are accommodated in the package body 21, the infrared detection element 1 is connected to the conductor via the bonding wire, the signal processing IC chip 5, or the like. When the signal processing IC chip 5 is not housed in the package body 21, the infrared detection element 1 is electrically connected to an appropriate conductor pattern via a bonding wire. do it.

  The package body 21 is formed with a shield conductor pattern 23 made of a metal material (for example, Cu). The infrared detection element 1 and the signal processing IC chip 5 are formed on the shield conductor pattern 23 of the package body 21. Connected appropriately. Here, the infrared sensor of the present embodiment has a ground external connection electrode (not shown) made of a metal material (for example, Cu or the like) electrically connected to the shield conductor pattern 23 on the package body 21. Is provided across the outer bottom surface and the outer surface of the package body 21, and the external connection electrode for the ground is electrically connected to a ground pattern such as a circuit board on which the infrared sensor is secondarily mounted. Further, it is possible to reduce the influence of external electromagnetic noise on the infrared detection element 1 and the signal processing IC chip 5 and to prevent the S / N ratio from being lowered due to the external electromagnetic noise. As can be seen from the above description, the package body 21 is formed of an inorganic material (ceramic and each of the above metal materials).

  The package lid 22 is made of a metal material such as Kovar, and Ni plating is applied for vacuum sealing. Note that the metal material of the package lid 22 is not limited to Kovar.

  The first infrared transmitting member 41 is a condensing infrared lens that condenses infrared rays onto the infrared detecting element 1 and is formed in a lens shape of a plano-convex aspheric lens. It is fixed to the package lid 22 so as to be on the detection element 1 side. Here, the first infrared transmitting member 41 also serves as a window material for making the inside of the package 2 a vacuum atmosphere, and is fixed (sealed) to the package lid 22 by a joint portion 51 made of lead-free glass frit. Wearing). More specifically, the first infrared transmitting member 41 joins the peripheral portion of the first infrared transmitting member 41 to the peripheral portion of the opening 2 a on one surface (the lower surface in FIG. 1) of the package lid 22. It is fixed by the part 51. Here, as the lead-free glass frit, for example, a material that melts at about 400 ° C. to 600 ° C. may be used.

  The second infrared transmitting member 42 is a lead-free conductive adhesive on the periphery of the opening 2a on the other surface (upper surface in FIG. 1) of the package lid 22 so as to close the opening 2a of the package lid 22. It is fixed by a joint portion 52 made of (for example, lead-free solder, silver paste, etc.). Here, the material of the joint portion 52 is not limited to a lead-free conductive adhesive, and may be, for example, a resin adhesive such as an epoxy resin or an acrylic resin, but in any case, the temperature is lower than that of the glass frit described above. Use one that can be joined with However, as described above, by using a conductive adhesive as the material of the joint portion 52, the second infrared transmitting member 42 is connected to the shield conductor pattern of the package body 21 via the joint portion 52 and the package lid 22. Therefore, the shield against electromagnetic noise can be improved, and the S / N ratio can be prevented from decreasing due to external electromagnetic noise.

  By the way, the infrared sensor of this embodiment assumes the infrared rays of the wavelength range (8 micrometers-13 micrometers) of 10 micrometer vicinity radiated | emitted from a human body as infrared rays of a detection target, As the above-mentioned each infrared transmissive material, following Table 1 ZnS, ZnSe, Si, Ge, GaAs, and the like having physical property constants as described above are conceivable. In the present embodiment, the first infrared transmitting material of the first infrared transmitting member 41 has a transmittance at a wavelength of 10 μm. Employing the highest ZnS, as the second infrared transmitting material of the second infrared transmitting member 42, the environmental load is small, the cost of the second infrared transmitting member 42 can be reduced, and compared with ZnS. Si having a small wavelength dispersion is employed.

  As can be seen from Table 1 above, ZnS has a transmittance of about 80% for infrared rays having a wavelength of 10 μm, and is higher than Si, Ge, GaAs, etc., so that the infrared ray transmitting material of the first infrared ray transmitting member 41 is high. By adopting ZnS, there is an advantage that it is not necessary to provide an infrared antireflection film on the first infrared transmitting member 41. On the other hand, ZnSe is an infrared transmitting material having a transmittance close to that of ZnS. However, since it contains Se, it is not preferable from the viewpoint of environmental load.

  Si is a low-cost infrared transmissive material, but has a transmittance of about 43% for infrared rays having a wavelength of 10 μm. Therefore, like the infrared sensor of this embodiment, Si is an infrared transmissive material for the second infrared transmissive member 42. When Si is employed, the infrared reflection preventing film 44 is laminated on the infrared incident surface side of the second infrared transmitting member 42 and the infrared optical filter film 43 is laminated on the infrared emitting surface side of the second infrared transmitting member 42. It is preferable. The infrared optical filter film 43 is optically designed so as to block infrared rays of less than 8 μm. However, the infrared optical filter film 43 is not suitable for the detection target infrared ray depending on the use of the infrared sensor (for example, human body detection, gas detection). Appropriate optical design may be performed according to the wavelength or wavelength range. Here, the infrared reflection preventing film 44 and the infrared optical filter film 43 may be formed by alternately laminating a plurality of types of thin films having different refractive indexes, for example. In the present embodiment, the infrared reflection preventing film 44 and the infrared optical filter film 43 are laminated on the second infrared transmitting member 42. However, at least one of the infrared reflection preventing film 44 and the infrared optical filter film 43 is used. What is necessary is just to laminate. The second infrared transmitting member 42 described above may be formed using a silicon wafer, and the infrared optical filter film 43 is formed on the one surface side of the silicon wafer that is the basis of the many second infrared transmitting members 42. In addition, after forming the infrared antireflection film 44 on the other surface side, it may be diced into the individual second infrared transmitting members 42.

  Hereinafter, the manufacturing method of the infrared sensor of the present embodiment will be described with reference to FIG. 2, but in FIG. 2, the shielding conductor pattern 23 in the infrared sensor of FIG. 1 is omitted.

  First, after performing the mounting process of mounting the infrared detecting element 1 and the signal processing IC chip 5 formed separately on the inner bottom surface side of the package body 21, the first infrared transmitting member 41 is the above lead-free glass frit. The package lid 22 fixed to the one surface side by the joint portion 51 is overlapped on the one surface side of the package body 21 in a vacuum, and the peripheral portion of the package lid 22 is sealed to the package body 21 by seam welding. Thereafter, the second infrared transmitting member 42 is joined to the other surface side of the package lid 22 by the lead-free conductive adhesive (for example, lead-free solder having a melting temperature of less than 400 ° C., silver paste, etc.). By fixing by the portion 52, an infrared sensor having the configuration shown in FIG. 1 is obtained.

  According to the infrared sensor of the present embodiment described above, the lead-free glass in which the first infrared transmitting member 41 formed of ZnS closes the opening 2a from the inside of the package 2 with respect to the package 2. The space fixed by the frit and surrounded by the package 2 and the first infrared transmitting member 41 is a vacuum atmosphere, and at least one of the infrared optical filter film 43 and the infrared antireflection film 44 is formed of Si. Since the laminated second infrared transmitting member 42 is fixed to the package 2 with a lead-free conductive adhesive or resin adhesive that can be used at a lower temperature than the glass frit, The load is small, and it is possible to suppress the peeling of the infrared antireflection film 44 and the infrared optical filter film 43 and to increase the sensitivity and cost. It made.

  Moreover, in the infrared sensor of this embodiment, since the 1st infrared transmission member 41 is formed in the lens shape which condenses infrared rays to the light-receiving surface of the infrared detection element 1, the 1st infrared transmission member 41 and the 1st As compared with the case where both the two infrared transmission members 42 are formed in a flat plate shape, higher sensitivity can be achieved.

(Embodiment 2)
The basic configuration of the infrared sensor of the present embodiment is substantially the same as that of the first embodiment. As shown in FIG. 3, the first infrared transmitting member 41 made of ZnS has a flat plate shape and is made of Si. The difference is that the shape of the second infrared transmitting member 42 is a lens shape of a plano-convex aspherical lens. Here, the second infrared transmitting member 42 is fixed to the package lid 22 such that the plane is the package lid 22 side and the convex curved surface is the opposite side of the package lid 22 side. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.

  The above-described lens-shaped second infrared transmitting member 42 is formed using a semiconductor lens manufacturing method (for example, Japanese Patent No. 3897055, Japanese Patent No. 3897056, etc.) using an anodizing technique. .

  Hereinafter, a method for manufacturing the second infrared transmitting member 42 will be described with reference to FIGS. 4 and 5. Specifically, a part of the semiconductor wafer 40 made of a silicon wafer having a p-type conductivity is anodized. A manufacturing method for manufacturing a semiconductor lens made of a silicon lens as the second infrared transmitting member 42 by removing the porous portion 48 made of porous silicon (see FIG. 4D) formed by making it porous in the process. Will be explained. In this embodiment, the resistivity of the semiconductor wafer 40 is set to 80 Ωcm, but this value is not particularly limited. However, the resistivity of the semiconductor wafer 40 is preferably 0.1 to 1000 Ωcm, more preferably several Ωcm to several hundred Ωcm.

First, a cleaning process for cleaning the semiconductor wafer 40 made of a silicon wafer shown in FIG. 4A, a marking process for providing a mark on one surface of the semiconductor wafer 40 (the lower surface in FIG. 4A), and then the semiconductor wafer. A conductive film (for example, an Al film, an Al—Si film, etc.) having a predetermined film thickness (for example, 1 μm) serving as a basis of the anode 46 (see FIG. 4C) used in the anodizing step on the one surface side of 40 The structure shown in FIG. 4B is obtained by performing a conductive layer forming step for forming a conductive layer 45 made of Here, in the conductive layer forming step, after the conductive layer 45 is formed on the one surface of the semiconductor wafer 40 by, for example, sputtering, the conductive layer 45 is sintered in an N ₂ gas and H ₂ gas atmosphere ( By performing heat treatment, ohmic contact between the conductive layer 45 and the semiconductor wafer 40 is obtained. The method for forming the conductive layer 45 is not limited to the sputtering method, and other known thin film forming methods such as a vapor deposition method may be employed.

  After the conductive layer forming step, a patterning step for patterning the conductive layer 45 so as to provide a circular opening 47 in the conductive layer 45 is performed, thereby obtaining the structure shown in FIG. Here, in the patterning step, a resist layer (not shown) having a portion corresponding to the opening 47 is formed on the one surface side of the semiconductor wafer 40 by using a photolithography technique, and then the resist layer The unnecessary portion of the conductive layer 45 is removed by etching using, for example, a wet etching technique or a dry etching technique to form an opening 47 to form an anode 46 composed of the remaining portion of the conductive layer 45, and then The resist layer is removed. If the conductive layer 45 is an Al film or an Al—Si film, when unnecessary portions of the conductive layer 45 are etched away by a wet etching technique, for example, a phosphoric acid-based etchant may be used. For example, a reactive ion etching apparatus or the like may be used when the unnecessary portion is removed by dry etching. Further, in the present embodiment, the anode 46 in which the contact pattern with the semiconductor wafer 40 is designed according to the desired lens shape is formed on the one surface side of the semiconductor wafer 40 in the conductive layer forming process and the patterning process. The anode forming step is configured.

  After the patterning process described above, the cathode 125 (see FIG. 5) disposed opposite to the other surface side (the upper surface side of FIG. 4A) of the semiconductor wafer 40 in the electrolytic solution B for anodization (see FIG. 5). 4 is performed by conducting an anodic oxidation process (anodic oxidation process) in which a porous portion 48 made of porous silicon serving as a removal site is formed on the other surface side of the semiconductor wafer 40 by energizing between the anode 46 and the anode 46. The structure shown in (d) is obtained. In the present embodiment, since the semiconductor wafer 40 having a p-type conductivity is used, it is not necessary to irradiate the other surface side of the semiconductor wafer 40 with light in the anodic oxidation process. When using an n-type conductivity type, it is necessary to irradiate light. Further, as the electrolytic solution B, a mixed solution in which a 55 wt% hydrogen fluoride aqueous solution and ethanol are mixed at a ratio of 1: 1 is used. The concentration of the hydrogen fluoride aqueous solution and the mixing ratio of the hydrogen fluoride aqueous solution and ethanol are used. Is not particularly limited. Also, the liquid mixed with the aqueous hydrogen fluoride solution is not limited to ethanol, and is not particularly limited as long as it is a liquid that can remove bubbles generated by an anodizing reaction, such as alcohol such as methanol, propanol, and isopropanol (IPA). .

By the way, when a part of the semiconductor wafer 40 made of a p-type silicon wafer is made porous in the anodic oxidation step, it is considered that the following reaction occurs when the hole is h ⁺ and the electron is e ^−. .
Si + 2HF + (2-n) h ⁺ → SiF ₂ + 2H ⁺ + ne ⁻
SiF ₂ + 2HF → SiF ₄ + H ₂
SiF ₄ + 2HF → SiH ₂ F ₆
That is, in the anodic oxidation of the semiconductor wafer 40 made of a silicon wafer, it is known that porosity or electropolishing occurs due to the balance between the supply amount of F ions and the supply amount of holes h ⁺ , and the supply amount of F ions. When the number of holes is larger than the supply amount of holes, porous formation occurs, and when the supply amount of holes h ⁺ is larger than the supply amount of F ions, electrolytic polishing occurs. Therefore, when a p-type silicon wafer is used as the semiconductor wafer 40 as in the present embodiment, the rate of pore formation by anodic oxidation is determined by the supply amount of holes h ⁺ , and therefore flows in the semiconductor wafer 40. The speed of porous formation is determined by the current density of the current, and the thickness of the porous portion 48 is determined. In the present embodiment, a current flows through the semiconductor wafer 40 along a path indicated by an arrow in FIG. 5, so that the center line of the opening 47 along the thickness direction of the anode 46 is formed on the other surface side of the semiconductor wafer 40. The in-plane distribution of the current density is such that the current density gradually increases as the distance from the surface of the semiconductor wafer 40 increases. The porous portion 48 formed on the other surface side of the semiconductor wafer 40 has the above-described opening 47 of the anode 46. The closer it is to the center line, the thinner it becomes. The in-plane distribution of the current density described above is a distribution of the electric field strength in the semiconductor wafer 40 determined by the contact pattern between the anode 47 and the semiconductor wafer 40 when the anode 46 and the cathode 125 are energized. The current density increases as the electric field strength increases, and the current density decreases as the electric field strength decreases.

  After the above-described anodic oxidation step is completed, the porous portion removing step for removing the porous portion 48 is performed to obtain the second infrared transmitting member 41 having the structure shown in FIG. Here, if an alkaline solution (for example, an aqueous solution of KOH, NaOH, TMAH, or the like) or an HF solution is used as an etching solution for removing the porous portion 48 made of porous silicon, the porous portion 48 is removed. In the part removing step, the anode 46 formed of an Al film or an Al—Si film can also be removed by etching.

  After the porous portion removing step, a filter film forming step of laminating the infrared optical filter film 43 on the one surface side of the semiconductor wafer 40 is performed and an infrared antireflection film 44 is laminated on the other surface side of the semiconductor wafer 40. After performing the antireflection film forming step, a dicing step for separating the individual second infrared transmitting members 42 may be performed.

  According to the method of manufacturing the second infrared transmitting member 42 described above, the current density of the current flowing in the semiconductor wafer 40 in the anodizing process is determined by the contact pattern between the anode 46 formed in the anode forming process and the semiconductor wafer 40. Since the distribution is determined, it is possible to control the in-plane distribution of the thickness of the porous portion 48 formed in the anodic oxidation step, and it is possible to form the porous portion 48 having a continuously changing thickness. Since the second infrared transmitting member 42 having a desired lens shape is formed by removing the porous portion 48 in the porous portion removing step, the desired lens shape (arbitrary shape) is used without using an expensive precision polishing apparatus. ) Of the second infrared transmitting member 42 can be manufactured at low cost. Moreover, in the manufacturing method of the above-mentioned 2nd infrared rays transmissive member 42, even if the lens diameter is about several mm, it can be formed by one anodic oxidation process and one porous part removal process. There is also.

  According to the infrared sensor of the present embodiment described above, as in the first embodiment, the environmental load is small, the peeling of the infrared antireflection film 44 and the infrared optical filter film 43 can be suppressed, and high sensitivity and low cost can be achieved. Can be realized. Moreover, in the infrared sensor of this embodiment, since the 2nd infrared transmissive member 42 is formed in the lens shape which condenses infrared rays to the light-receiving surface of the infrared detection element 1, high sensitivity can be achieved, and the said The second infrared transmitting member 42 in the shape of a lens has an anode 46 designed with a contact pattern with the semiconductor wafer 40 that is a silicon substrate in accordance with the lens shape. The contact with the semiconductor wafer 40 is made on the one surface side of the semiconductor wafer 40. Porous that becomes a removal site by anodizing the other surface side of the semiconductor wafer 40 in the electrolytic solution B made of a solution for etching and removing oxides of constituent elements of the semiconductor wafer 40 after forming the ohmic contact. Since it is formed by removing the porous portion 48 after forming the portion 48, compared to the case where it is formed using an expensive precision polishing apparatus, It attained the cost of the second infrared transmitting member 42.

  In the infrared sensor of the present embodiment, the shape of the first infrared transmitting member 41 formed of ZnS is a flat plate shape, and the shape of the second infrared transmitting member 42 formed of Si is a plano-convex non-type. Since the lens shape is a spherical lens, the second infrared transmitting member 42 of the first embodiment is formed by forming the second infrared transmitting member 42 made of Si having a refractive index larger than that of ZnS into a lens shape. As a result, the second infrared transmitting member 42 can be made thinner than the infrared transmitting member 41 of the first embodiment. Since the total thickness of the second infrared transmitting member 42 and the first infrared transmitting member 41 can be made thinner than that in the first embodiment, the overall height of the infrared sensor can be reduced as compared with the first embodiment.

(Embodiment 3)
The basic configuration of the infrared sensor of the present embodiment is substantially the same as that of the first embodiment. As shown in FIG. 6, the second infrared transmitting member 42 is formed in a lens shape as in the second embodiment. The point of using is different. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, 2, and description is abbreviate | omitted.

  Therefore, according to the infrared sensor of the present embodiment, as in the first embodiment, the environmental load is small, the peeling of the infrared antireflection film 44 and the infrared optical filter film 43 can be suppressed, and high sensitivity and low cost can be achieved. Can be realized. Moreover, in the infrared sensor of this embodiment, since the 1st infrared transmission member 41 and the 2nd infrared transmission member 42 are each formed in the lens shape, the 1st infrared transmission member 41 and the 2nd infrared transmission are carried out. The optical system constituted by the member 42 can realize a high-resolution optical system and can achieve higher sensitivity.

(Embodiment 4)
The basic configuration of the infrared sensor of the present embodiment is substantially the same as that of the first embodiment, and is different in that the package 2 is configured by a can package as shown in FIG. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.

  The package 2 in the present embodiment is formed in a disk-shaped metal base (stem) 24 on which the infrared detection element 1 and the signal processing IC chip 5 are mounted, and a bottomed cylindrical shape with an open rear surface. It is comprised with the metal cap 25 sealed by the metal base 24 so that the signal processing IC chip 5 may be covered, and in the front wall located in front of the infrared detection element 1 (upper part of FIG. 7) in the cap 25 An opening 2a is formed. In the present embodiment, as in the first embodiment, the space surrounded by the package 2 and the first infrared transmitting member 41 is a vacuum atmosphere. In the present embodiment, the metal base 24 constitutes a mounting member on which the infrared detection element 1 is mounted, and the cap 25 has an opening 2a and surrounds the infrared detection element 1 between the mounting member. The cover member joined to the mounting member is configured.

  Here, the cap 25 and the metal base 24 are made of a metal material such as Kovar, the surface of the cap 25 is plated with Ni, and the portion of the metal base 24 that is joined to the cap 25 is plated with Ni. After applying, Au plating is applied.

  The metal base 24 has a plurality of terminal holes (through which a plurality of terminal pins 26 electrically connected via pads (not shown) of the signal processing IC chip 5 and bonding wires (not shown) are inserted. The terminal pin 26 is sealed by a sealing portion (not shown) in a form inserted through the terminal hole. As a material for the terminal pin 26, Kovar, which is a kind of sealing alloy, is used, but other sealing alloys, sealing metals, and the like may be used. The plurality of terminal pins 26 include a signal output terminal pin 25, a power supply terminal pin 26, a ground terminal pin 26, and the like. The sealing portion that seals the signal output terminal pin 25 and the power supply terminal pin 26 is formed of an insulating lead-free glass frit and seals the ground terminal pin 26. The part is formed of a metal material. In short, the signal output terminal pin 26 and the power supply terminal pin 26 are electrically insulated from the metal base 24, whereas the ground terminal pin 26 has the same potential as the metal base 24. Thus, the infrared sensor of the present embodiment can also enhance the shielding effect against external electromagnetic noise as in the first embodiment, and can achieve high sensitivity by improving the S / N ratio.

  In manufacturing the infrared sensor of the present embodiment, the first infrared transmitting member 41 is fixed to the cap 25 by the joint portion 51 made of lead-free glass frit, and then the metal base 24 is surrounded in vacuum. The cap 25 is sealed by joining an outer flange portion 25c extending outward from the rear end edge of the cap 25 to the portion by resistance welding, and then the second infrared transmitting member is attached to the cap 25. 42 is fixed to the cap 25 by a joint portion 52 made of a lead-free conductive adhesive or resin adhesive similar to that of the first embodiment.

  Therefore, according to the infrared sensor of the present embodiment, as in the first embodiment, the environmental load is small, the peeling of the infrared antireflection film 44 and the infrared optical filter film 43 can be suppressed, and high sensitivity and low cost can be achieved. Can be realized. The combination of the first infrared transmitting member 41 and the second infrared transmitting member 42 is not limited to the combination of the first embodiment, and may be a combination of the second embodiment or the third embodiment.

1 Infrared detector 2 Package 2a Opening 21 Package body (mounting member)
22 Package lid (cover member)
24 Metal base (mounting member)
25 Cap (cover member)
41 First Infrared Transmitting Member 42 Second Infrared Transmitting Member 43 Infrared Optical Filter Film 44 Infrared Antireflective Film 51 Bonding Portion 52 Bonding Portion

Claims (3)

  A thermal infrared receiving element, a package made of an inorganic material and containing an infrared detecting element and having an opening formed in front of the infrared detecting element, and a first infrared transmitting material formed from the inside of the package A first infrared transmission member fixed to the package so as to close the opening, and a second infrared transmission made of the second infrared transmission material and fixed to the package so as to close the opening from the outside of the package An infrared sensor having a space surrounded by the package and the first infrared transmitting member as a vacuum atmosphere, the package having a mounting member on which an infrared detection element is mounted and the opening And a cover member joined to the mounting member so as to surround the infrared detection element between the mounting member and the first infrared transmitting material is made of ZnS. The first infrared transmitting member is fixed to the cover member with a lead-free glass frit, the second infrared transmitting material is Si, and the second infrared transmitting member is provided with an infrared optical filter film and an infrared reflecting material. An infrared sensor characterized in that at least one of the protective film is laminated and the second infrared transmitting member is fixed to the cover member with a lead-free conductive adhesive or a resin adhesive.   2. The infrared sensor according to claim 1, wherein at least one of the first infrared transmitting member and the second infrared transmitting member is formed in a lens shape for condensing infrared rays on the infrared detection element. .   The second infrared transmitting member is formed in a lens shape for condensing infrared rays to the infrared detection element using a silicon substrate, and an anode in which a contact pattern with the silicon substrate is designed according to the lens shape Is formed on the one surface side of the silicon substrate so that the contact with the silicon substrate becomes ohmic contact, and then the other surface side of the silicon substrate is anoded in an electrolytic solution composed of a solution for etching away oxides of constituent elements of the silicon substrate. The infrared sensor according to claim 1, wherein the infrared sensor is formed by forming a porous part to be a removal site by oxidation and then removing the porous part.

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