JP2007108776A - Method of manufacturing semiconductor lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing semiconductor lens capable of easily forming a semiconductor lens having an arbitrary shape. <P>SOLUTION: The method of manufacturing the semiconductor lens 1 (Fig. 1(f)) comprising a silicon lens made by removing part of a semiconductor substrate 10 (Fig. 1(a)) made of p-type silicon substrate comprises: an anode forming step of forming an anode 12 (Fig. 1(c)) by pattern design in accordance with a desired lens shape; an anodizing step of forming a porous part 14 (Fig. 1(e)) made of porous silicon as a removal part on the other surface side of the semiconductor substrate 10 by supplying power between a cathode oppositely arranged on the other surface side of the semiconductor substrate 10 and the anode 12 in an electrolytic solution; and a porous part removing step of removing a porous part 14, wherein an in-plane distribution of resistance value designed according to a desired lens shape is formed on the semiconductor substrate 10 between the anode forming step and the anodizing step (Fig. 1(d)). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor lens.

  Conventionally, a method for manufacturing a microlens mold using a conductive substrate and a method for manufacturing a microlens using the microlens mold have been proposed (see Patent Document 1). In Patent Document 1, a synthetic resin lens is exemplified as a microlens.

  In the method for manufacturing a microlens mold disclosed in Patent Document 1, for example, a silicon nitride film is deposited on one surface of a low-resistance p-type silicon substrate that is a conductive substrate, and then a photolithography technique and an etching technique are used. Then, a circular opening is formed at a predetermined portion of the silicon nitride film, and then a part of the one surface side of the p-type silicon substrate is made porous by anodizing using the silicon nitride film as a mask layer. Thus, a hemispherical porous silicon portion is formed. Thereafter, the silicon dioxide portion is formed by oxidizing the entire porous silicon portion, the mask layer is removed, and then the silicon dioxide portion is removed to form a desired convex lens on the one surface of the p-type silicon substrate. A recess corresponding to the shape is formed, and then a thermal oxide film is formed on each of the one surface side and the other surface side of the p-type silicon substrate. In the above-described anodizing treatment, the gap between the cathode disposed opposite to the one surface side of the p-type silicon substrate and the anode plate disposed in contact with the other surface of the semiconductor substrate in the electrolytic solution for anodization. The porous silicon part is formed by energizing the current.

  By the way, in the method for manufacturing a microlens mold disclosed in Patent Document 1, a p-type silicon substrate having a low resistance that is relatively close to the resistivity of a conductor is used. Since the porous silicon substrate progresses isotropically like isotropic etching, the shape of the opening is made circular so that the p-type silicon substrate 100 has the above-mentioned shape as shown in FIG. The depth dimension a1 of the concave portion 101 formed on one surface and the radius a2 of the circular opening surface of the concave portion 101 are substantially equal, and as a result, a spherical lens can be manufactured as a microlens. In addition, Patent Document 1 also discloses that a cylindrical lens can be manufactured as a microlens by making the shape of the opening portion rectangular when manufacturing a microlens mold. Yes.

Conventionally, an anode without providing a mask layer having a pattern designed in accordance with the mesa shape on one surface side of a semiconductor substrate having a high resistance (for example, a resistivity of about 10 ⁸ Ωcm) such as a semi-insulating GaAs substrate. As a method for forming a mesa shape using an oxidation technique, an anode (electrode) whose shape is designed in accordance with the mesa shape is brought into contact with the other surface side of the semiconductor substrate, and then the above-mentioned semiconductor substrate in the anode and the electrolytic solution. A method has been proposed in which an anodic oxidation process is performed in which an oxide film is formed by energizing a cathode disposed opposite to one surface, followed by an oxide film removal process in which the oxide film is removed by etching (for example, a patent) Reference 2).

In the mesa shape forming method described in Patent Document 2, the in-plane distribution of the current density of the current flowing through the semiconductor substrate is determined by the shape of the anode and the thickness of the oxide film in the anodizing step. A mesa shape in which the slope is gentle and the side surface and the flat surface of the mesa are smoothly continuous can be formed.
JP 2000-263556 A Japanese Patent Laid-Open No. 55-13960

  By the way, in the method for manufacturing a microlens mold disclosed in Patent Document 1, only a microlens mold for forming a microlens having a uniform curvature radius of a convex curved surface can be manufactured. Aspherical lenses and concave lenses could not be formed as lenses. In addition, in the method for manufacturing a microlens mold disclosed in Patent Document 1, the lens diameter (= 2 × a2) of the microlens that can be manufactured is limited by the thickness of the p-type silicon substrate 100, which is larger. In order to manufacture a microlens having a lens diameter, it is necessary to use a p-type silicon substrate 100 having a larger thickness, which increases costs.

  In addition, it is conceivable to manufacture a plano-concave semiconductor lens by using the method of forming the concave portion 101 on the p-type silicon substrate 100 described in Patent Document 1, but the curvature radius of the concave curved surface is used as the semiconductor lens. However, only a plano-concave spherical lens or cylindrical lens can be formed, and an aspherical lens cannot be formed. Also, in such a method for manufacturing a semiconductor lens, bubbles generated during anodizing treatment are desorbed through the openings of the mask layer, so that bubbles gather around the openings and the rate of progress of porous formation As a result, there is a case where a concave curved surface having a desired radius of curvature cannot be formed.

Then, although it is possible to apply the technique of the said patent document 2 to the manufacturing method of a semiconductor lens, in an anodic oxidation process, with the increase in the thickness of the formed oxide film, it is between an anode and a cathode. For example, when a GaAs substrate having a thickness of 400 μm and a resistivity of 10 ⁸ Ωcm is used as the semiconductor substrate, the thickness of the oxide film is increased when the oxide film is formed with a constant current of 1 mA / cm ^2. Since the potential difference becomes as high as 400 V even if the thickness is about 0.6 μm, it is necessary to repeat the basic process consisting of the anodizing process and the oxide film removing process, which complicates the manufacturing process and provides the desired lens shape. It was difficult to manufacture the semiconductor lens.

  Further, in the technique described in Patent Document 2, since the anode used in the anodizing process is merely pressed against and brought into contact with the other surface of the high-resistance semiconductor substrate, the contact resistance between the semiconductor substrate and the anode is large. The contact between the semiconductor substrate and the anode becomes a Schottky contact, and there is a problem in the controllability and reproducibility of the in-plane distribution of the current density.

  The present invention has been made in view of the above reasons, and an object of the present invention is to provide a method of manufacturing a semiconductor lens capable of easily forming a semiconductor lens having an arbitrary shape.

  The invention of claim 1 is a method of manufacturing a semiconductor lens by removing a part of a semiconductor substrate to form a semiconductor lens, and an anode having a pattern designed according to a desired lens shape is formed on one surface side of the semiconductor substrate. An anodic oxidation step for forming a porous portion serving as a removal site on the other surface side of the semiconductor substrate by passing an electric current between the cathode and the anode disposed opposite to the other surface side of the semiconductor substrate in the electrolytic solution. And a porous part removing process for removing the porous part. In the anode forming process, the anode is formed so that the contact between the anode and the semiconductor substrate becomes ohmic contact, and in the anodic oxidation process, an electrolyte is used. An in-plane distribution of a resistance value designed according to a desired lens shape is formed on the semiconductor substrate before the anodizing step, using a solution for removing oxides of constituent elements of the semiconductor substrate by etching. Distribution type Characterized by comprising providing a step.

  According to the present invention, the current density of the current flowing in the semiconductor substrate in the anodic oxidation process due to the contact pattern between the anode and the semiconductor substrate formed in the anode forming process and the in-plane distribution of the resistance value formed in the in-plane distribution forming process. Since the in-plane distribution is determined, it becomes easy to control the in-plane distribution of the thickness of the porous portion formed in the anodic oxidation process, and in the anode forming process, the contact between the anode and the semiconductor substrate becomes an ohmic contact. In the anodic oxidation step, a solution for removing the oxide of the constituent element of the semiconductor substrate is used as the electrolytic solution in the anodic oxidation step, so that the porous portion having a desired thickness distribution can be formed in one anodic oxidation step. Since a semiconductor lens having a desired lens shape is formed by removing the porous portion in the porous portion removing step, the semiconductor substrate to be used can be made thicker. It is possible to easily form any shape of the semiconductor lens without.

  According to a second aspect of the present invention, in the first aspect of the invention, in the in-plane distribution forming step, the thickness of the semiconductor substrate is adjusted so that the in-plane distribution of the resistance value of the semiconductor substrate becomes a desired in-plane distribution. It is characterized by that.

  According to the present invention, since the in-plane distribution of the resistance value is formed by adjusting the thickness of the semiconductor substrate, the design of the in-plane distribution of the resistance value of the semiconductor substrate is facilitated.

  According to a third aspect of the present invention, in the invention of the second aspect, the in-plane distribution forming step is a step of adjusting the thickness of the semiconductor substrate using an anodizing process and an etching process before the anode forming step. An electrode forming process for forming an electrode patterned according to a desired thickness of the semiconductor substrate on the one surface side of the semiconductor substrate, and the other surface side of the semiconductor substrate in an electrolyte for adjusting the thickness An anodizing process for forming a porous portion for adjusting the thickness on the other surface side of the semiconductor substrate by energizing between a cathode and an electrode arranged opposite to each other, and etching and removing the porous portion for adjusting the thickness And an etching process. In the electrode formation process, the electrode is formed so that the contact between the electrode and the semiconductor substrate is ohmic contact. In the anodization process, the thickness is adjusted. As a solution liquid, characterized by using a solution of oxide is etched off of the constituent elements of the semiconductor substrate.

  According to this invention, since the thickness of the semiconductor substrate is adjusted using an anodization process and an etching process in the in-plane distribution forming step before the anode forming step, the thickness in the in-plane distribution forming step is It is possible to form an in-plane distribution with a continuously changing thickness on the semiconductor substrate, and control of the curvature radius and focal length of the semiconductor lens becomes easy.

  According to a fourth aspect of the present invention, in the second aspect of the invention, the in-plane distribution forming step is a step of adjusting the thickness of the semiconductor substrate using an anodizing process and an etching process after the anode forming step. There is a porous portion for adjusting the thickness on the other surface side of the semiconductor substrate by energizing between the cathode and the anode disposed opposite to the other surface side of the semiconductor substrate in the electrolyte for adjusting the thickness. And an etching process for etching and removing the porous portion for adjusting the thickness. In the anodizing process, the oxide of the constituent element of the semiconductor substrate is removed by etching as an electrolyte for adjusting the thickness. A solution is used.

  According to this invention, since the thickness of the semiconductor substrate is adjusted using the anodizing process and the etching process in the in-plane distribution forming step after the anode forming step, the in-plane distribution forming step It is possible to form an in-plane distribution in which the thickness continuously changes on the semiconductor substrate, and control of the curvature radius and focal length of the semiconductor lens becomes easy. According to the present invention, since the anode formed in the anode forming step is used in the anodic oxidation process, the in-plane distribution forming step can be simplified as compared with the invention of claim 3.

  According to a fifth aspect of the present invention, in the first aspect of the invention, in the in-plane distribution forming step, impurities are selectively added to the semiconductor substrate so that the in-plane distribution of the resistance value of the semiconductor substrate becomes a desired in-plane distribution. It is introduced in.

  According to the present invention, the in-plane distribution of the resistance value can be formed by controlling the concentration and the introduction site of the impurity introduced into the semiconductor substrate by a general semiconductor manufacturing process such as ion implantation or diffusion. .

  According to a sixth aspect of the present invention, in the first to fifth aspects of the invention, a p-type silicon substrate is used as the semiconductor substrate.

  According to this invention, compared with the case where an n-type silicon substrate is used as the semiconductor substrate, the anodizing apparatus used in the anodizing step can be simplified, and the cost can be reduced.

  According to the first aspect of the invention, it is possible to easily form a semiconductor lens having an arbitrary shape.

(Basic example)
In this basic example, as a basic manufacturing method common to the semiconductor lens manufacturing methods described in the first to third embodiments described later, a semiconductor substrate 10 made of a p-type silicon substrate (see FIG. 2A) is used. A semiconductor lens 1 (see FIG. 2 (e)) made of a silicon lens by removing the porous portion 14 (see FIG. 2 (d)) made of porous silicon formed by making part of it porous in the anodizing step. ) Is exemplified. In this basic example, the resistivity of the semiconductor substrate 10 is set to 80 Ωcm, but this value is not particularly limited. However, the resistivity of the semiconductor substrate 10 is preferably 0.1 to 1000 Ωcm, more preferably several Ωcm to several hundred Ωcm.

First, after performing the cleaning process for cleaning the semiconductor substrate 10 shown in FIG. 2A and the marking process for providing a mark on one surface of the semiconductor substrate 10 (the lower surface in FIG. 2A), the above-described one of the semiconductor substrates 10 is performed. Conductivity comprising a metal film (for example, an Al film) having a predetermined film thickness (for example, 1 μm) serving as a basis for the anode 12 (see FIGS. 2C and 3A) used in the anodizing process on the surface side. By performing the conductive layer forming step for forming the conductive layer 11, the structure shown in FIG. 2B is obtained. Here, in the conductive layer formation step, the conductive layer 11 is formed on the one surface of the semiconductor substrate 10 by, for example, sputtering, and then the sintering of the conductive layer 11 in an N ₂ gas and H ₂ gas atmosphere ( By performing heat treatment, the conductive layer 11 in which the contact with the semiconductor substrate 10 is in ohmic contact is formed. The method for forming the conductive layer 11 is not limited to the sputtering method, and for example, a vapor deposition method may be employed. The material of the conductive layer 11 is not limited to Al, and any material that can make ohmic contact with the semiconductor substrate 10 may be used. For example, Al—Si containing Al as a main component may be employed.

  After the conductive layer forming step, a patterning step for patterning the conductive layer 11 so as to provide a circular opening 13 in the conductive layer 11 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 portion 13 is formed on the one surface side of the semiconductor substrate 10 by using a photolithography technique, and then a resist is formed. Using the layer as a mask, unnecessary portions of the conductive layer 11 are etched away by, for example, wet etching technique or dry etching technique to provide an opening 13 to form the anode 12 composed of the remaining portion of the conductive layer 11, and The resist layer is removed. If the conductive layer 11 is an Al film, when unnecessary portions of the conductive layer 11 are removed by wet etching, for example, a phosphoric acid-based etchant may be used, and the unnecessary portions of the conductive layer 11 are dried. In the case of etching removal by an etching technique, for example, a reactive ion etching apparatus or the like may be used. In this basic example, the conductive layer forming step and the patterning step described above constitute an anode forming step in which the anode 12 having a pattern designed according to the desired lens shape is formed on the one surface side of the semiconductor substrate 10. ing. The radius of the circular opening 13 may be set as appropriate based on the design value of the lens diameter of the semiconductor lens 1.

  After the patterning step, the cathode 25 (see FIG. 4) and the anode disposed opposite to the other surface side of the semiconductor substrate 10 (upper surface side in FIG. 2A) in the electrolytic solution B for anodic oxidation (see FIG. 4). 2 (d) by conducting an anodic oxidation step (anodic oxidation treatment) for forming a porous portion 14 as a removal site on the other surface side of the semiconductor substrate 10 by energizing the semiconductor substrate 10. obtain.

  Here, in the anodizing step, an anodizing apparatus A having the configuration shown in FIG. 4 is used. The anodizing apparatus A has a flat plate-like energizing electrode 21 that is brought into contact with the anode 12 formed on the one surface side of the semiconductor substrate 10, and the semiconductor substrate 10 is in a form in which the anode 12 and the energizing electrode 21 are brought into contact with each other. A disk-shaped support table 22 that supports the cylindrical body, a cylindrical tube body 23 that is disposed above the support table 22 with the center line as the vertical direction, and an inner casing that is integrally formed at the lower end of the tube body 23. A seal member 24 formed of an O-ring interposed between the portion 23 a and the peripheral portion of the semiconductor substrate 10, an outer flange portion 23 b continuously formed integrally with the lower end portion of the cylindrical body 23, and a peripheral portion of the support base 22 And an electrolyte B for anodization is placed in a space surrounded by the other surface of the semiconductor substrate 10, the seal member 24, and the cylindrical body 23.

As the electrolytic solution B, a solution for removing SiO ₂ that is an oxide of Si that is a constituent element of the semiconductor substrate 10, for example, a mixed solution in which a 55 wt% hydrogen fluoride aqueous solution and ethanol are mixed in a ratio of approximately 1: 1. However, the concentration of the aqueous hydrogen fluoride solution and the mixing ratio of the aqueous hydrogen fluoride solution and ethanol are not particularly limited. Further, 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 the anodizing reaction, such as alcohol such as methanol, propanol, and isopropanol (IPA). . The cylindrical body 23 may be formed of a material having resistance to the electrolytic solution B, for example, a fluorine-based resin such as Teflon (registered trademark).

The anodic oxidation apparatus A is a voltage source that applies a voltage between the anode 12 and the cathode 25 through the energizing electrode 21 and the cathode 25 made of a platinum electrode disposed opposite to the other surface of the semiconductor substrate 10. 31, a current sensor 32 that detects a current flowing from the voltage source 31 to the energization electrode 21, and a control unit 33 that includes a microcomputer that controls the output voltage of the voltage source 31 based on the current detected by the current sensor 32. The control unit 33 controls the voltage source 31 so that a current having a predetermined current density (for example, 30 mA / cm ² ) flows from the voltage source 31 to the energizing electrode 21 for a predetermined time (for example, 120 minutes). It is like that. The processing conditions for the anodizing step are not particularly limited, and the above-described predetermined current density and the above-mentioned predetermined time may be set as appropriate.

By the way, when a part of the semiconductor substrate 10 made of a p-type silicon substrate 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 substrate 10 made of a silicon substrate, 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, porosification 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 substrate is used as the semiconductor substrate 10 as in this basic example, the rate of porosity by anodic oxidation is determined by the supply amount of holes h ⁺ , and therefore flows in the semiconductor substrate 10. The speed of porous formation is determined by the current density of the current, and the thickness of the porous portion 14 is determined. In this basic example, a current flows through the semiconductor substrate 10 along the path indicated by the arrow in FIG. 5, so that the other surface side (upper surface side in FIG. 5) of the semiconductor substrate 10 is along the thickness direction of the anode 12. The in-plane distribution of the current density is such that the current density gradually increases as the distance from the center line of the opening 13 increases, and the porous portion 14 formed on the other surface side of the semiconductor substrate 10 has the anode 12. It becomes gradually thinner toward the center line of the aperture 13.

  After the above-described anodic oxidation step is completed, a porous portion removing step for removing the porous portion 14 is performed. Here, if an alkaline solution (for example, an aqueous solution of KOH, NaOH, TMAH, etc.) or an HF solution is used as an etching solution for removing the porous portion 14, in the porous portion removing step for removing the porous portion 14, The anode 12 formed of the Al film or the Al—Si film can also be removed by etching, and the semiconductor lens 1 having the structure shown in FIGS. 2E and 3B can be obtained. A dicing process for separating the semiconductor lens 1 may be performed. Note that the porous portion removing step for removing the porous portion 14 and the anode removing step for removing the anode 12 may be performed separately.

  According to the manufacturing method of the semiconductor lens 1 of the present basic example described above, the current density surface of the current flowing in the semiconductor substrate 10 in the anodic oxidation process due to the contact pattern between the anode 12 formed in the anode forming process and the semiconductor substrate 10. Since the internal distribution is determined, it is possible to control the in-plane distribution of the thickness of the porous portion 14 formed in the anodizing step, and it is possible to form the porous portion 14 having a continuously changing thickness, Moreover, in the anode forming step, the anode 12 is formed so that the contact between the anode 12 and the semiconductor substrate 10 is ohmic contact, and in the anodic oxidation step, an oxide of a constituent element of the semiconductor substrate 10 is etched as the electrolytic solution B. Since the solution to be removed is used, the porous part 14 having a desired thickness distribution can be easily formed by one anodic oxidation process, and the porous part 14 is removed by the porous part removing process. Since the semiconductor lens 1 having a desired lens shape is formed by, it is possible to easily form the semiconductor lens 1 of arbitrary shape.

  Here, in the anode forming step in this basic example, after forming the conductive layer 11 serving as the basis of the anode 12 on the one surface side of the semiconductor substrate 10, the circular opening 13 is provided in the conductive layer 11. Since the anode 12 is formed by patterning the conductive layer 11 as described above, the current density of the current flowing through the semiconductor substrate 10 on the other surface side of the semiconductor substrate 10 in the anodic oxidation step is the anode 12 (conductive layer). 11), the in-plane distribution becomes smaller as it approaches the center line of the aperture 13, so that the porous portion 14 becomes closer to the center line of the aperture 13 of the anode 12 on the other surface side of the semiconductor substrate 10. Thus, a plano-convex spherical lens or aspherical lens can be formed as the semiconductor lens 1. Note that the optical axis of the semiconductor lens 1 formed in this manner coincides with the center line of the aperture 13 described above.

  By the way, in the manufacturing method of the semiconductor lens 1 described above, the lens shape (in this basic example, the aspherical surface of the planoconvex aspherical lens is determined by the in-plane distribution of the current density of the current flowing through the semiconductor substrate 10 in the anodizing step. Since the curvature radius and lens diameter are determined, the resistivity and thickness of the semiconductor substrate 10, the electrical resistance value of the electrolyte B used in the anodizing step, the distance between the semiconductor substrate 10 and the cathode 25, the plane of the cathode 25 The lens shape is controlled by appropriately setting the shape (the shape in a plane parallel to the semiconductor substrate 10 in a state of being opposed to the semiconductor substrate 10), the inner diameter of the circular aperture 13 in the anode 12, and the like. Can do. Here, the electric resistance value of the electrolytic solution B can be adjusted by, for example, changing the concentration of the aqueous hydrogen fluoride solution or the mixing ratio of the aqueous hydrogen fluoride solution and ethanol. Further, by appropriately setting conditions other than the shape of the anode 12 (for example, the electric resistance value of the electrolytic solution B), the shape of the semiconductor lens 1 can be more easily controlled.

  Further, in the above-described anodizing step, the control unit 33 controls the output voltage of the voltage source 31 so that the current density of the current detected by the current sensor 32 becomes a predetermined current density. However, if the current density is decreased continuously or stepwise before the end of energization to reduce the porosity and the porosity of the semiconductor substrate 10, the porous portion 14 is removed. It becomes possible to make the surface of the semiconductor lens 1 after that smoother.

  Further, in the semiconductor lens 1 manufactured by the above-described manufacturing method, as shown in FIGS. 6 and 7, the lens portion 1a and the flange portion 1b surrounding the lens portion 1a over the entire circumference can be formed continuously and integrally. For example, the infrared sensor having the configuration shown in FIGS. 6 and 7 can be easily attached to the package 50. Hereinafter, the infrared sensor configured as shown in FIGS. 6 and 7 will be briefly described.

  Here, the infrared sensor shown in FIGS. 6 and 7 includes an infrared detection element 61 composed of a thermal infrared detection element (for example, pyroelectric element, thermopile, etc.) and a signal processing circuit that performs signal processing on the output of the infrared detection element 61. The provided circuit block 60 and a package 50 made of a can package for storing the circuit block 60 are provided.

  The package 50 includes a disk-shaped stem 51 on which the circuit block 60 is mounted via a spacer 71 made of an insulating material, and a metal cap 52 fixed to the stem 51 so as to cover the circuit block 60. A plurality (three in this case) of terminal pins 55 that are electrically connected to appropriate portions of the circuit block 60 are provided so as to penetrate the stem 51. The cap 52 is formed in a bottomed cylindrical shape with the rear surface open, and the rear surface is closed by the stem 51. In addition, a rectangular (in this embodiment, a square shape) translucent window 53 is formed on the front wall of the cap 52 positioned in front of the infrared detection element 61, and infrared rays are transmitted to the light receiving surface of the infrared detection element 61. As an optical member for condensing light, the above-described semiconductor lens 1 is disposed from the inside of the cap 52 so as to cover the transparent window 53.

  In the stem 51, a plurality of terminal holes 51b through which the terminal pins 55 are inserted are penetrated in the thickness direction, and the sealing portions 54 are formed so that the terminal pins 55 are inserted into the terminal holes 51b. It is sealed by.

  The cap 52 and the stem 51 described above are formed of a steel plate, and an outer flange portion 52c extending outward from the rear edge of the cap 52 with respect to the flange portion 51c formed on the peripheral portion of the stem 51 is provided. Sealed by welding.

  The circuit block 60 includes a first circuit board 62 made of a printed wiring board (for example, a composite copper-clad laminate) on which ICs 63 and electronic components 64 that are components of the signal processing circuit are mounted on different surfaces. A resin layer 65 laminated on the mounting surface side of the electronic component 64 in the first circuit board 62, and a metal layer (hereinafter, copper or the like) made of a metal material (for example, copper) on the surface of an insulating base made of glass epoxy or the like. A shield layer 66 formed on the resin layer 65 and a printed wiring board (for example, a composite copper-clad laminate) on which the infrared detection element 61 is mounted and laminated on the shield plate 66. And a second circuit board 67.

  Here, in the second circuit board 67, a thermal insulation hole 67a for thermally insulating the sensing element of the infrared detection element 61 and the second circuit board 67 is provided in the thickness direction. The circuit block 60 has through holes 62b, 65b, 66b, 67b through which the terminal pins 55 are inserted into the first circuit board 62, the resin layer 65, the shield plate 66, and the second circuit board 67, respectively. The infrared detection element 61 and the signal processing circuit are electrically connected via the terminal pin 55 so as to penetrate in the thickness direction. Of the three terminal pins 55 of the above-described infrared sensor, one is a power supply terminal pin 55 (55a), the other is a signal output terminal pin 55 (55b), and the other is a ground. Terminal pin 55 (55c), and the shield layer of the shield plate 66 is electrically connected to the ground terminal pin 55c. Here, the sealing portions 54 and 54 (54a and 54b) for sealing the terminal pins 55a and 55b are formed of insulating sealing glass, and the sealing portion 54 for sealing the terminal pins 55c. (54c) is formed of a metal material. In short, the terminal pins 55 a and 55 b are electrically insulated from the stem 51, whereas the ground terminal pin 55 c has the same potential as the stem 51.

  In the semiconductor lens 1, the lens portion 1a is formed in the shape of a plano-convex aspheric lens, and the outer peripheral shape of the base portion 1b, which is a portion other than the lens portion 1a, is formed in a rectangular shape. In addition, the semiconductor lens 1 is provided with an infrared blocking unit 1 d that blocks infrared rays that are to enter the light receiving surface of the infrared detecting element 61 through the base unit 1 b that is a part other than the lens unit 1 a located inside the light transmitting window 53. It has been. Here, the infrared blocking portion 1d is configured by an infrared reflective film made of a metal material (for example, Al, Al-Si, etc.), but the material of the infrared reflective film is not limited to Al, Al-Si, or the like. Any material can be used as long as it is glossy and capable of reducing unevenness when forming a thin film, and in particular, a metal material such as Au, Ag, Al or the like having an infrared reflectance higher than 0.9, or a metal material thereof. It is preferable to adopt a material. In addition, as the infrared reflecting film constituting the infrared blocking unit 1d, a dielectric film or a dielectric multilayer film may be employed. The infrared blocking unit 1d is not limited to the infrared reflecting film that reflects infrared rays, but may be configured by a film having a function of scattering infrared rays. Moreover, you may make it leave the above-mentioned anode 12 as the infrared rays prevention part 1d.

  In the infrared sensor using the semiconductor lens 1 described above, the flange portion 1 b is fixed to the peripheral portion of the light transmitting window 53 on the rear surface of the front wall of the cap 52 with the lens portion 1 a disposed in the light transmitting window 53 of the cap 52. Therefore, it can be easily attached to the package 50 as compared with a conventional infrared lens formed by polishing a silicon substrate or a germanium substrate.

  Further, in the infrared sensor using the semiconductor lens 1 described above, it is possible to block the infrared rays that are about to enter the infrared detecting element 61 through the base portion 1b, which is a portion other than the lens portion 1a, by the infrared blocking portion 1d. It is possible to prevent unnecessary infrared rays from entering the infrared detection element 61 from outside the detection area determined by the shape of the portion 1a and the like, and to increase the sensitivity of the infrared detection element 61. In the above infrared sensor, a conductive material (for example, solder) is used as a bonding material for bonding the semiconductor lens 1 and the cap 52, and an electromagnetic shield is provided by electrically connecting the semiconductor lens 1 and the cap 52. This can be performed, and the influence of electromagnetic noise on the infrared detection element 61 can be prevented.

  By the way, in the above-mentioned infrared sensor, the transparent window 53 of the cap 52 is opened in a rectangular shape. However, the transparent window 53 of the cap 52 is opened in a circular shape, and the semiconductor lens 1 is formed only by the lens portion 1a. It is also conceivable that the cap 52 and the semiconductor lens 1 are bonded to each other by dropping into the transparent window 53. However, when such a configuration is adopted, when the semiconductor lens 1 is dropped into the transparent window 53, the plane perpendicular to the optical axis of the semiconductor lens 1 is inclined with respect to the front wall of the cap 52, and the semiconductor lens 1 and the infrared detection element 61 are not parallel to each other, and the condensing point of the semiconductor lens 1 may be displaced from the infrared detection element 61.

  On the other hand, in the infrared sensor having the configuration shown in FIGS. 6 and 7, as described above, the opening shape of the translucent window 53 into which the base portion 1b of the semiconductor lens 1 is dropped in the cap 52 has a base portion 1b on each side. The flange portion 1c is shorter than each side of the lens portion 1a and larger than the lens diameter of the lens portion 1a, and is formed thinner in the periphery of the base portion 1b of the semiconductor lens 1 than other portions. The peripheral portion of the base portion 1b is fixed to the cap 52 through a joint portion 58 made of the above-mentioned joining material in a form in contact with the rear surface of the wall. Therefore, the parallelism between the semiconductor lens 1 and the infrared detection element 61 can be increased, and the condensing point of the semiconductor lens 1 can be prevented from deviating from the infrared detection element 61.

  By the way, when a technique for forming an oxide film as a removal site in the anodizing process as in the technique described in Patent Document 2 is used, anodization is used to form a curved surface having a height difference of several tens of μm. It is necessary to repeat the process and the oxide film removing process, and it is difficult to obtain a desired lens shape. On the other hand, in the manufacturing method of the semiconductor lens 1 of this basic example, a curved surface having a height difference of several hundred μm can be formed by one anodic oxidation process and one porous part removing process. In addition to a lens having a lens diameter of several hundred μm or less, which is generally called a microlens, a single anodizing step and a single porous portion removing step are formed even for a lens having a lens diameter of about several millimeters. Can do.

  In the manufacturing method described above, the anode 12 provided with the circular opening 13 is formed in the anode forming step. However, the shape of the opening 13 is not a circular shape but a rectangular shape. For example, a cylindrical lens can be formed as the semiconductor lens 1. If the anode 12 has a circular planar shape, a plano-concave aspherical lens can be formed as the semiconductor lens 1.

(Embodiment 1)
Hereinafter, although the manufacturing method of the semiconductor lens 1 of this embodiment is demonstrated based on FIG. 1, description is abbreviate | omitted suitably about the process similar to a basic example.

  First, a cleaning process and a marking process are performed on the semiconductor substrate 10 made of a p-type silicon substrate shown in FIG. 1A, and then anodized on one surface side of the semiconductor substrate 10 (the lower surface side in FIG. 1A). The structure shown in FIG. 1B is obtained by carrying out a conductive layer forming step for forming the conductive layer 11 made of an Al film that is the basis of the anode 12 (see FIG. 1C) used in the process.

  After the conductive layer forming step, a patterning step for patterning the conductive layer 11 so as to provide a circular opening 13 in the conductive layer 11 is performed, thereby obtaining the structure shown in FIG. The conductive layer forming process and the patterning process constitute an anode forming process.

  Incidentally, in the manufacturing method described in the above basic example, in the anodic oxidation process, the in-plane distribution of the current density of the current flowing in the semiconductor substrate 10 is determined depending on the contact pattern between the anode 12 and the semiconductor substrate 10. The current density of the current flowing in the periphery of the formation region of the semiconductor lens 1 is larger than the current density of the current flowing in the center portion of the formation region of the semiconductor lens 1. Since the thickness of the portion corresponding to the central portion is also relatively thick, it becomes difficult to form the semiconductor lens 1 having a smaller curvature of the convex curved surface when the thickness of the semiconductor substrate 10 is limited in advance.

  On the other hand, in the manufacturing method of this embodiment, the in-plane distribution for forming the in-plane distribution of the resistance value designed according to the desired lens shape on the semiconductor substrate 10 between the anode forming step and the anodizing step. A forming step is provided. Here, in the in-plane distribution forming process in the present embodiment, the in-plane distribution of the resistance value is controlled by controlling the thickness of the semiconductor substrate 10 as shown in FIG. (In other words, the thickness of the semiconductor substrate 10 is adjusted so that a desired in-plane distribution of the resistance value is formed on the semiconductor substrate 10). The in-plane distribution design becomes easy. In FIG. 1D, the other surface of the semiconductor substrate 10 is formed such that the thickness of the central portion of the semiconductor lens 1 formation region of the semiconductor substrate 10 is larger than the thickness of the peripheral portion of the semiconductor lens 1 formation region. Concavities and convexities are formed on the upper surface (the upper surface in FIG. 1C), and the resistance value is larger in a region where the semiconductor substrate 10 is thicker than in a thin region. Here, in the etching for adjusting the thickness of the semiconductor substrate 10, dry etching is performed using, for example, a reactive ion etching apparatus (RIE apparatus) or an inductively coupled plasma (IPC) type etching apparatus, but KOH or TMAH. For example, wet etching may be used.

  After the patterning step and the in-plane distribution forming step are completed, the semiconductor is energized between the cathode 25 and the anode 12 that are disposed opposite to the other surface side of the semiconductor substrate 10 in the electrolytic solution B for anodization. The structure shown in FIG. 1E is obtained by performing an anodic oxidation process for forming a porous portion 14 to be a removal site on the other surface side of the substrate 10. Here, in this embodiment, in the region where the thickness of the semiconductor substrate 10 is thick, the resistance value is larger than that in the thin region and the current does not flow easily, and the basic in-plane distribution forming step is not provided before the anodizing step. Compared to the manufacturing method of the example, the current density at the center of the formation region of the semiconductor lens 1 of the semiconductor substrate 10 is reduced (in other words, the current density at the center of the formation region of the semiconductor lens 1 of the semiconductor substrate 10 is Therefore, the thickness of the porous portion 14 at the periphery of the formation region of the semiconductor lens 1 can be increased, and the radius of curvature of the convex curved surface can be increased. A porous portion 14 corresponding to a smaller semiconductor lens 1 can be formed.

  After the end of the anodizing process, a porous part removing process for removing the porous part 14 is performed. Here, if an alkaline solution (for example, an aqueous solution of KOH, NaOH, TMAH, etc.) or an HF solution is used as an etching solution for removing the porous portion 14, an Al film or an Al-Si film is used in the porous portion removing step. 1 can be removed by etching, and the structure shown in FIG. 1F can be obtained. Thereafter, a dicing process for separating the individual semiconductor lenses 1 may be performed. The porous part removing step and the anode removing step for removing the anode 12 may be performed separately.

  Therefore, in the manufacturing method of the present embodiment, the semiconductor in the anodic oxidation step is formed by the contact pattern between the anode 12 formed in the anode forming step and the semiconductor substrate 10 and the in-plane distribution of the resistance value formed in the in-plane distribution forming step. Since the in-plane distribution of the current density of the current flowing through the substrate 10 is determined, it is easy to control the in-plane distribution of the thickness of the porous portion 14 formed in the anodizing process, and the porous portion 14 is removed. Since the semiconductor lens 1 having a desired lens shape is formed by removing in the process, the semiconductor lens 1 having an arbitrary shape can be formed without increasing the thickness of the semiconductor substrate 10 to be used as compared with the manufacturing method of the basic example described above. It can be easily formed.

  In this embodiment, the in-plane distribution forming step is provided between the anodic forming step and the anodizing step. However, the in-plane distribution forming step is not necessarily provided between the anodic forming step and the anodizing step. However, it may be provided before the anodizing step.

(Embodiment 2)
Hereinafter, although the manufacturing method of the semiconductor lens 1 of this embodiment is demonstrated based on FIG. 8, description is abbreviate | omitted suitably about the process similar to Embodiment 1. FIG.

  First, a cleaning process and a marking process are performed on the semiconductor substrate 10 made of a p-type silicon substrate shown in FIG. 8A, and then anodized on one surface side of the semiconductor substrate 10 (the lower surface side in FIG. 8A). As an in-plane distribution forming step of performing an anode forming step of forming the anode 12 used in the process and then forming an in-plane distribution of resistance values designed according to a desired lens shape on the semiconductor substrate 10, The structure shown in FIG. 8C is obtained by adjusting the thickness using an anodic oxidation process and an etching process.

Here, in the in-plane distribution forming step in the present embodiment, the in-plane distribution of the resistance value is controlled by controlling the thickness of the semiconductor substrate 10 as shown in FIG. 8C using an anodizing process and an etching process. (In other words, the thickness of the semiconductor substrate 10 is adjusted so that a desired in-plane distribution of the resistance value is formed on the semiconductor substrate 10). The in-plane distribution design becomes easy. Here, in the in-plane distribution forming step, the cathode 25 (see FIG. 4) and the anode 12 which are disposed to face the other surface side of the semiconductor substrate 10 (the upper surface side in FIG. 8B) in the electrolyte for adjusting the thickness. 8a to obtain the structure shown in FIG. 8 (b) by performing an anodic oxidation process for forming a thickness adjusting porous portion 16 on the other surface side of the semiconductor substrate 10. The structure shown in FIG. 8C is obtained by performing an etching process for removing the porous portion 16 by etching. In the anodic oxidation process, the same electrolytic solution as the electrolytic solution B used in the anodic oxidation step described in the basic example is used as the electrolytic solution for adjusting the thickness. That is, a solution for removing SiO ₂ which is an oxide of a constituent element of the semiconductor substrate 10 is used.

  After the above-described in-plane distribution forming step is completed, a current is passed between the cathode 25 and the anode 12 that are disposed to face the other surface side of the semiconductor substrate 10 in the electrolytic solution B for anodization. The structure shown in FIG. 8D is obtained by performing an anodic oxidation step for forming the porous portion 14 to be a removal site on the other surface side. Here, in this embodiment, in the region where the thickness of the semiconductor substrate 10 is thick, the resistance value is larger than that in the thin region and the current does not flow easily, and the basic in-plane distribution forming step is not provided before the anodizing step. Compared to the manufacturing method of the example, the current density at the center of the formation region of the semiconductor lens 1 of the semiconductor substrate 10 is reduced (in other words, the current density at the center of the formation region of the semiconductor lens 1 of the semiconductor substrate 10 is Therefore, the thickness of the porous portion 14 at the periphery of the formation region of the semiconductor lens 1 can be increased, and the radius of curvature of the convex curved surface can be increased. The porous portion 14 corresponding to the semiconductor lens 1 having a smaller focal length can be formed.

  Since the structure shown in FIG. 8 (e) can be obtained by performing the porous portion removing step for removing the porous portion 14 after the anodic oxidation step is completed, dicing that is then separated into individual semiconductor lenses 1 is performed. What is necessary is just to perform a process. In the present embodiment, the anode 12 is left as the infrared ray blocking portion 1d described in the basic example.

  According to the manufacturing method of the semiconductor lens 1 of the present embodiment described above, the thickness of the semiconductor substrate 10 is adjusted using the anodizing process and the etching process in the in-plane distribution forming process after the anode forming process. In the in-plane distribution forming step, it is possible to form an in-plane distribution having a continuously varying thickness on the semiconductor substrate 10, and control of the radius of curvature, focal length, etc. of the semiconductor lens 1 is easier than in the first embodiment. become. Further, by reducing the current density in the anodizing step as compared with the current density in the in-plane distribution forming step, the porosity of the porous portion 14 can be reduced. The smoothness of the surface of the semiconductor lens 1 after removal can be improved.

  In the above manufacturing method, the in-plane distribution forming step is performed after the anode forming step. However, the in-plane distribution forming step may be performed before the anode forming step. In this case, the in-plane distribution forming step includes an electrode formation process in which an electrode having a pattern designed in accordance with a desired thickness of the semiconductor substrate 10 is formed on the one surface side of the semiconductor substrate 10 and a semiconductor in an electrolyte for adjusting the thickness. An anodic oxidation process in which a porous portion for thickness adjustment is formed on the other surface side of the semiconductor substrate 10 by energizing between the cathode and the electrode opposed to the other surface side of the substrate 10; And an etching process for removing the porous portion by etching. In the electrode formation process, the electrode is formed so that the contact between the electrode and the semiconductor substrate 10 is ohmic contact. In the anodization process, as an electrolyte for adjusting the thickness. A solution for removing the oxide of the constituent element of the semiconductor substrate 10 by etching is used. If such a manufacturing method is adopted, the thickness of the semiconductor substrate 10 is adjusted by using an anodizing process and an etching process in the in-plane distribution forming process prior to the anode forming process, and therefore, before the anode forming process. In the in-plane distribution forming step, the semiconductor substrate 10 can be formed with an in-plane distribution whose thickness is continuously changed, and the anode 12 and the semiconductor substrate 10 formed in the anode forming step after the in-plane distribution forming step. The curvature radius and focal length of the semiconductor lens 1 can be easily controlled based on the contact pattern and the thickness distribution of the semiconductor substrate 10.

  However, as described above, in the anodic oxidation process, the manufacturing method using the anode 12 formed in the anodic forming process uses the anodic oxidation process and the etching process to reduce the thickness of the semiconductor substrate 10 before the anodic forming process. Therefore, the in-plane distribution process can be simplified as compared with the case where the in-plane distribution process to be adjusted is provided.

(Embodiment 3)
Hereinafter, the manufacturing method of the semiconductor lens 1 of the present embodiment will be described with reference to FIG. 9, but description of the same steps as the basic example will be omitted as appropriate.

  First, a cleaning process and a marking process are performed on the semiconductor substrate 10 made of a p-type silicon substrate shown in FIG. 9A, and then anodized on one surface side of the semiconductor substrate 10 (the lower surface side in FIG. 9A). The structure shown in FIG. 9B is obtained by carrying out a conductive layer forming step for forming the conductive layer 11 made of an Al film serving as the basis of the anode 12 (see FIG. 9C) used in the process.

  After the conductive layer forming step, a patterning step for patterning the conductive layer 11 so as to provide the circular opening 13 in the conductive layer 11 is performed, whereby the structure shown in FIG. 9C is obtained. The conductive layer forming process and the patterning process constitute an anode forming process.

  By the way, in the manufacturing method described in the above basic example, as described in the first embodiment, when the thickness of the semiconductor substrate 10 is limited in advance, the curvature of the convex curved surface of the semiconductor lens 1 is smaller. Formation becomes difficult.

  On the other hand, in the manufacturing method of this embodiment, the in-plane distribution for forming the in-plane distribution of the resistance value designed according to the desired lens shape on the semiconductor substrate 10 between the anode forming step and the anodizing step. A forming step is provided. Here, in the in-plane distribution forming process in the present embodiment, an ion implantation method or a diffusion method is used, as shown in FIG. 9D, the other surface side of the semiconductor substrate 10 (the upper surface side in FIG. 9C). The in-plane distribution of the resistance value is formed by forming the low resistance layer 15 by selectively introducing the p-type impurity into the predetermined portion (in other words, the resistance value surface of the semiconductor substrate 10). (Impurities are selectively introduced into the semiconductor substrate 10 so that the internal distribution becomes a desired in-plane distribution). Therefore, the concentration of the impurity introduced into the semiconductor substrate 10 by a general semiconductor manufacturing process such as an ion implantation method or a diffusion method. And by controlling the introduction site, an in-plane distribution of resistance values can be formed. In FIG. 9D, the resistance of the semiconductor substrate 10 is such that the resistance value of the peripheral portion of the semiconductor lens 1 formation region of the semiconductor substrate 10 is smaller than the resistance value of the central portion of the semiconductor lens 1 formation region. A low resistance layer 15 is formed on the other surface side.

  After the patterning step and the in-plane distribution forming step are completed, the semiconductor is energized between the cathode 25 and the anode 12 that are disposed opposite to the other surface side of the semiconductor substrate 10 in the electrolytic solution B for anodization. The structure shown in FIG. 9E is obtained by performing an anodic oxidation process for forming a porous portion 14 to be a removal site on the other surface side of the substrate 10. Here, in this embodiment, the resistance value of the region where the low resistance layer 15 is not formed is larger than that of the region where the low resistance layer 15 is formed in the semiconductor substrate 10, and the current does not flow easily. Compared with the manufacturing method of the basic example in which the in-plane distribution forming step is not provided before the step, the current density in the central portion of the formation region of the semiconductor lens 1 in the semiconductor substrate 10 is reduced (in other words, the semiconductor substrate 10 Among them, the difference between the current density at the center of the formation region of the semiconductor lens 1 and the current density at the periphery of the formation region of the semiconductor lens 1 can be increased), so that the porous portion 14 in the periphery of the formation region of the semiconductor lens 1 The thickness can be increased, and the porous portion 14 corresponding to the semiconductor lens 1 having a smaller curvature of the convex curved surface can be formed.

  After the end of the anodizing process, a porous part removing process for removing the porous part 14 is performed. Here, if an alkaline solution (for example, an aqueous solution of KOH, NaOH, TMAH, etc.) or an HF solution is used as an etching solution for removing the porous portion 14, an Al film or an Al-Si film is used in the porous portion removing step. 9 can be removed by etching, and the structure shown in FIG. 9F can be obtained. Thereafter, a dicing process for separating the individual semiconductor lenses 1 may be performed. The porous part removing step and the anode removing step for removing the anode 12 may be performed separately.

  Thus, in the manufacturing method of the present embodiment, as in the first embodiment, the contact pattern between the anode 12 formed in the anode forming step and the semiconductor substrate 10 and the in-plane resistance value formed in the in-plane distribution forming step. Since the distribution determines the in-plane distribution of the current density of the current flowing through the semiconductor substrate 10 in the anodic oxidation process, it becomes easy to control the in-plane distribution of the thickness of the porous portion 14 formed in the anodic oxidation process. Since the semiconductor lens 1 having a desired lens shape is formed by removing the portion 14 in the porous portion removing step, the semiconductor lens 1 having an arbitrary shape is easily formed as compared with the manufacturing method of the basic example described above. It becomes possible.

  In this embodiment, the in-plane distribution forming step is provided between the anodic forming step and the anodizing step. However, the in-plane distribution forming step is not necessarily provided between the anodic forming step and the anodizing step. However, it may be provided before the anodizing step.

(Embodiment 4)
Hereinafter, the manufacturing method of the semiconductor lens 1 of the present embodiment will be described with reference to FIG. 10, but description of the same steps as the basic example will be omitted as appropriate.

  First, a cleaning process and a marking process are performed on the semiconductor substrate 10 made of a p-type silicon substrate shown in FIG. 10A, and then an in-plane distribution of resistance values designed according to a desired lens shape is applied to the semiconductor substrate 10. An in-plane distribution forming step to be formed is provided. Here, in the in-plane distribution forming process in the present embodiment, an ion implantation method or a diffusion method is used, as shown in FIG. 10B, one surface side of the semiconductor substrate 10 (the lower surface side in FIG. 10A). The in-plane distribution of the resistance value is formed by forming the low resistance layer 15 by selectively introducing the p-type impurity into the predetermined portion (ie, the in-plane distribution of the desired resistance value). Thus, the in-plane distribution of the resistance value can be formed by controlling the concentration and site of the impurity introduced into the semiconductor substrate 10 by a general semiconductor manufacturing process such as ion implantation or diffusion. In FIG. 10B, the resistance value of the semiconductor substrate 10 is such that the resistance value of the periphery of the formation region of the semiconductor lens 1 in the semiconductor substrate 10 is smaller than the resistance value of the central portion of the formation region of the semiconductor lens 1. A low resistance layer 15 is formed on the one surface side.

  Thereafter, a conductive layer forming step of forming a conductive layer 11 made of an Al film serving as a basis of the anode 12 (see FIG. 10D) used in the anodizing step on the one surface side of the semiconductor substrate 10 is performed. Thus, the structure shown in FIG.

  After the conductive layer forming step, a patterning step for patterning the conductive layer 11 so as to provide a circular opening 13 in the conductive layer 11 is performed, thereby obtaining the structure shown in FIG. The conductive layer forming process and the patterning process constitute an anode forming process.

  After the patterning step, an electric current is passed between the cathode 25 and the anode 12 that are disposed opposite to the other surface side of the semiconductor substrate 10 in the electrolytic solution B for anodic oxidation, and the other surface side of the semiconductor substrate 10 is moved to the other surface side. A structure shown in FIG. 10E is obtained by performing an anodizing step for forming the porous portion 14 to be a removal site. Here, in this embodiment, the resistance value of the region where the low resistance layer 15 is not formed is larger than that of the region where the low resistance layer 15 is formed in the semiconductor substrate 10, and the current does not flow easily. Compared with the manufacturing method of the basic example in which the in-plane distribution forming step is not provided before the step, the current density in the central portion of the formation region of the semiconductor lens 1 in the semiconductor substrate 10 is reduced (in other words, the semiconductor substrate 10 Among them, the difference between the current density at the center of the formation region of the semiconductor lens 1 and the current density at the periphery of the formation region of the semiconductor lens 1 can be increased), so that the porous portion 14 in the periphery of the formation region of the semiconductor lens 1 The thickness can be increased, and the porous portion 14 corresponding to the semiconductor lens 1 having a smaller curvature of the convex curved surface can be formed.

  After the end of the anodizing process, a porous part removing process for removing the porous part 14 is performed. Here, if an alkaline solution (for example, an aqueous solution of KOH, NaOH, TMAH, etc.) or an HF solution is used as an etching solution for removing the porous portion 14, it is formed of an Al film in the porous portion removing step. Since the anode 12 can also be removed by etching and the structure shown in FIG. 10F can be obtained, a dicing process for separating the individual semiconductor lenses 1 may be performed thereafter. The porous part removing step and the anode removing step for removing the anode 12 may be performed separately.

  Thus, in the manufacturing method of the present embodiment, as in the third embodiment, the contact pattern between the anode 12 formed in the anode forming step and the semiconductor substrate 10 and the in-plane resistance value formed in the in-plane distribution forming step. Since the distribution determines the in-plane distribution of the current density of the current flowing through the semiconductor substrate 10 in the anodic oxidation process, it becomes easy to control the in-plane distribution of the thickness of the porous portion 14 formed in the anodic oxidation process. Since the semiconductor lens 1 having a desired lens shape is formed by removing the portion 14 in the porous portion removing step, the semiconductor lens 1 having an arbitrary shape is easily formed as compared with the manufacturing method of the basic example described above. It becomes possible.

  In each of the above embodiments, a method of manufacturing a plano-convex lens as the semiconductor lens 1 has been described. However, by appropriately setting an in-plane distribution of a contact pattern and a resistance value between the anode 12 and the semiconductor substrate 10. It is also possible to manufacture cylindrical lenses and plano-concave lenses. Here, in the case of manufacturing a plano-concave lens, if the resistance corresponding to the central portion of the lens in the semiconductor substrate 10 is reduced, the semiconductor substrate 10 used is manufactured in the same manner as in the case of manufacturing a plano-convex lens. A lens having an arbitrary shape can be easily formed without increasing the thickness. Further, the one surface of the semiconductor substrate 10 is adopted by adopting a process from the removal of the porous portion 14 to the formation of the porous portion (first porous portion) 14 on the other surface side of the semiconductor substrate 10. If the second porous portion having a thickness distribution corresponding to the desired lens shape is formed on the side and then removed, a biconvex lens, a biconcave lens, an uneven lens, or the like can be formed.

  In each of the embodiments described above, a p-type silicon substrate is employed as the semiconductor substrate 10, but the material of the semiconductor substrate 10 is not limited to Si, and an anodic oxidation process such as Ge, SiC, GaAs, GaP, InP, or the like. Other materials that can be made porous may be used, and the conductivity type is not limited to p-type, but may be n-type. However, when the conductivity type of the semiconductor substrate 10 is p-type, the porous portion can be formed without irradiating the semiconductor substrate 10 with light in the anodic oxidation process. Compared with the n-type, the anodizing apparatus used in the anodizing step can be simplified, and the cost can be reduced.

  For example, an electrolytic solution as shown in Table 1 below may be used as the electrolytic solution B used in the anodizing step to remove oxides of constituent elements of the semiconductor substrate 10.

  Instead of the semiconductor substrate 10, it is also possible to use a metal substrate (for example, an Al substrate, a Ti substrate, etc.) that can be made porous by anodization. In each of the above embodiments, a single lens such as a plano-convex lens, a biconvex lens, a biconcave lens, a concavo-convex lens, and a cylindrical lens has been described as the semiconductor lens 1. However, according to the technical idea of the present invention, the single lens is not limited. Also, it is possible to form a so-called multi-lens in which adjacent single lenses overlap each other, a so-called array lens in which the above-described single lenses are arranged in an array, or a lens in which a plurality of types of single lenses are combined.

FIG. 6 is a cross-sectional view of main processes for explaining the method of manufacturing a semiconductor lens in the first embodiment. It is explanatory drawing of the manufacturing method of a basic example. It is explanatory drawing of a manufacturing method same as the above. It is a schematic block diagram of the anodizing apparatus used with the manufacturing method same as the above. It is explanatory drawing of a manufacturing method same as the above. The infrared sensor provided with the semiconductor lens in the same as above is shown, (a) is a schematic plan view, and (b) is a schematic sectional view. It is a schematic exploded perspective view of an infrared sensor same as the above. FIG. 10 is a main process sectional view for illustrating the method for manufacturing a semiconductor lens in the second embodiment. FIG. 10 is a main process sectional view for explaining the method for manufacturing a semiconductor lens in the third embodiment. FIG. 10 is a main process cross-sectional view for describing a method for manufacturing a semiconductor lens in a fourth embodiment. It is explanatory drawing of the manufacturing method of the conventional metal mold | die for microlenses.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor lens 10 Semiconductor substrate 11 Conductive layer 12 Anode 13 Opening part 14 Porous part

Claims (6)

  A semiconductor lens manufacturing method for manufacturing a semiconductor lens by removing a part of a semiconductor substrate, an anode forming step for forming an anode with a pattern design according to a desired lens shape on one surface side of the semiconductor substrate, and electrolysis An anodic oxidation step of forming a porous portion to be a removal site on the other surface side of the semiconductor substrate by energizing between the cathode and the anode opposed to the other surface side of the semiconductor substrate in the liquid; And removing the porous part to be removed. In the anode forming process, the anode is formed so that the contact between the anode and the semiconductor substrate becomes ohmic contact. In the anodic oxidation process, the constituent elements of the semiconductor substrate are used as an electrolyte. An in-plane distribution forming step for forming an in-plane distribution of resistance values designed in accordance with a desired lens shape is provided on the semiconductor substrate before the anodizing step so as to use a solution for removing oxide by etching. The method of manufacturing a semiconductor lens characterized by and.   2. The semiconductor lens manufacturing method according to claim 1, wherein in the in-plane distribution forming step, the thickness of the semiconductor substrate is adjusted so that the in-plane distribution of the resistance value of the semiconductor substrate becomes a desired in-plane distribution. Method.   The in-plane distribution forming step is a step of adjusting the thickness of the semiconductor substrate using an anodic oxidation process and an etching process before the anode forming step, and a pattern is formed according to a desired thickness of the semiconductor substrate. An electrode forming process for forming the designed electrode on the one surface side of the semiconductor substrate, and an electric current is passed between the cathode and the electrode arranged opposite to the other surface side of the semiconductor substrate in the electrolyte for adjusting the thickness. An anodic oxidation process for forming a porous portion for thickness adjustment on the other surface side of the semiconductor substrate, and an etching process for etching away the porous portion for thickness adjustment. An electrode is formed so that the contact with the semiconductor substrate becomes ohmic contact, and in the anodizing process, an acid of the constituent element of the semiconductor substrate is used as an electrolyte for adjusting the thickness. The process according to claim 2, wherein the semiconductor lens characterized by using a solution things removed by etching.   The in-plane distribution forming step is a step of adjusting the thickness of the semiconductor substrate using an anodic oxidation process and an etching process after the anode forming step. An anodizing process in which a porous portion for adjusting the thickness is formed on the other surface side of the semiconductor substrate by energizing between the cathode and the anode disposed opposite to the other surface side, and a porous material for adjusting the thickness 3. The method according to claim 2, further comprising: an etching process for etching away a portion of the semiconductor substrate, wherein an anodic oxidation process uses a solution for etching away an oxide of a constituent element of the semiconductor substrate as an electrolyte for adjusting the thickness. Manufacturing method of a semiconductor lens.   2. The semiconductor according to claim 1, wherein in the in-plane distribution forming step, impurities are selectively introduced into the semiconductor substrate so that the in-plane distribution of the resistance value of the semiconductor substrate becomes a desired in-plane distribution. Lens manufacturing method.   The method of manufacturing a semiconductor lens according to claim 1, wherein a p-type silicon substrate is used as the semiconductor substrate.

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