JP3897056B1 - Manufacturing method of semiconductor lens - Google Patents

Abstract

A semiconductor lens manufacturing method capable of easily forming a semiconductor lens having an arbitrary shape and a smooth surface.
A semiconductor lens manufacturing method for manufacturing a semiconductor lens (FIG. 1 (e)) by removing a part of a semiconductor substrate (FIG. 1 (a)) made of a p-type silicon substrate. An anode forming step of forming an anode 12 (FIG. 1C) having a pattern designed according to a desired lens shape so as to make ohmic contact with one surface side of the semiconductor substrate 10, and oxidation of constituent elements of the semiconductor substrate 10 A porous portion 14 made of porous silicon which becomes a removal site on the other surface side of the semiconductor substrate 10 by energizing between the cathode 12 and the anode 12 facing each other on the other surface side of the semiconductor substrate 10 in an electrolyte solution for dissolving the substance. An anodic oxidation step for forming (FIG. 1D) and a porous portion removing step for removing the porous portion 14.
[Selection] Figure 1

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.

  In the method of 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, and p-type silicon is used during anodization. Since the substrate isotropically progresses like isotropic etching, the one surface of the p-type silicon substrate 100 is formed as shown in FIG. The depth dimension a1 of the concave portion 101 formed in this step is substantially equal to the radius a2 of the circular opening surface of the concave portion 101. As a result, a plano-convex spherical lens can be manufactured as a microlens. In Patent Document 1, a plano-convex cylindrical lens can be manufactured as a micro lens as a result of making the shape of the opening portion rectangular when manufacturing a micro lens mold. Is also disclosed.

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.

  Conventionally, in a semiconductor lens manufacturing method for manufacturing a semiconductor lens by removing a part of a semiconductor substrate by wet etching or dry etching, a semiconductor substrate made of a compound semiconductor material (for example, InP, GaAs, InAs) is used. A technique for forming a semiconductor lens having an arbitrary shape (for example, a spherical lens, an aspherical lens, a cylindrical lens, etc.) by appropriately designing a pattern of an etching mask layer formed on one surface has been proposed (for example, Patent Documents). 3).

Here, when an aspherical lens is manufactured by the method for manufacturing a semiconductor lens disclosed in Patent Document 3, a plurality of annular rings provided concentrically in a plane orthogonal to the thickness direction of the semiconductor substrate in the etching mask layer. By designing the pattern so that the opening width of the opening portion increases as the distance from the central axis along the thickness direction increases, the etching depth and side etching amount during etching can be changed for each opening portion. After the etching, the etching mask layer is removed, and then a smoothing process for removing unnecessary protrusions is performed.
JP 2000-263556 A Japanese Patent Laid-Open No. 55-13960 Japanese Patent Laid-Open No. 11-298046

  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. A plano-convex aspherical lens could not be formed as a lens.

  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.

  In the technique described in Patent Document 2, the anode used in the anodic oxidation process is simply pressed against and brought into contact with the other surface of the high-resistance semiconductor substrate, so that 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.

  Further, in the method of manufacturing a semiconductor lens disclosed in Patent Document 3, only an unnecessary protrusion cannot be selectively removed even if a smoothing process is performed after etching. , Aspherical lenses, cylindrical lenses, etc.) were difficult to form.

  The present invention has been made in view of the above-described 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 and a smooth surface.

  The invention of claim 1 is a semiconductor lens manufacturing method for manufacturing a semiconductor lens by removing a part of a semiconductor substrate, and an anode having a pattern designed according to a desired lens shape is provided on one surface side of the semiconductor substrate. An anode forming step for forming an ohmic contact with the substrate, and a removal site 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 electrolytic solution. An anodizing step for forming the porous portion and a porous portion removing step for removing the porous portion. In the anodizing step, the entire area of the porous portion on the other surface of the semiconductor substrate is to be formed. It is characterized by using a solution that is brought into contact with the electrolytic solution and that removes an oxide of a constituent element of the semiconductor substrate by etching.

  According to this invention, since the in-plane distribution of the current density of the current flowing through the semiconductor substrate in the anodizing process is determined by the pattern of the anode formed in the anode forming process, the thickness of the porous portion formed in the anodizing process is determined. The in-plane distribution can be controlled and a porous portion with a continuously changing thickness can be formed. In addition, in the anode forming step, the anode is formed so as to be in ohmic contact with the semiconductor substrate, In the anodic oxidation process, the entire region of the porous portion formation region on the other surface of the semiconductor substrate is brought into contact with the electrolytic solution, and a solution that removes the oxide of the constituent elements of the semiconductor substrate by etching is used as the electrolytic solution. A porous portion having a desired thickness distribution can be easily formed by a single anodic oxidation step, and the porous portion can be removed in the porous portion removing step so that a desired lens shape can be obtained. Since the body lens is formed, it is possible and the surface is easily form a smooth semiconductor lens in arbitrary shape.

  According to a second aspect of the present invention, in the first aspect of the invention, in the anode forming step, a conductive layer serving as a basis of the anode is formed on the one surface side of the semiconductor substrate, and then the conductive layer has a circular shape. The anode is formed by patterning the conductive layer so as to provide an opening.

  According to this invention, since the current density of the current flowing through the semiconductor substrate in the anodic oxidation step has an in-plane distribution that decreases as it approaches the center line of the aperture of the anode, the other surface of the semiconductor substrate On the side, the closer to the center line of the aperture portion of the anode, the thinner the porous portion, and an aspherical lens having a smooth surface can be formed as a semiconductor lens.

  According to a third aspect of the present invention, there is provided a semiconductor lens manufacturing method for manufacturing a semiconductor lens by removing a part of a semiconductor substrate, wherein an insulating layer having a pattern designed according to a desired lens shape is provided on one surface side of the semiconductor substrate. Forming an insulating layer; and forming an anode made of a conductive layer covering the insulating layer and an exposed portion of the one surface on the one surface side of the semiconductor substrate so as to make ohmic contact with the semiconductor substrate; An anode that forms a porous portion as a removal site by making the other surface side of the semiconductor substrate porous by energizing between the cathode and the anode disposed opposite to the other surface side of the semiconductor substrate in the electrolytic solution An oxidation step and a porous portion removal step for removing the porous portion, and in the anodization step, the entire region of the porous portion on the other surface of the semiconductor substrate is brought into contact with the electrolytic solution, and As a solution liquid, characterized by using a solution to etch away the oxide of the constituent elements of the semiconductor substrate.

  According to this invention, since the in-plane distribution of the current density of the current flowing through the semiconductor substrate in the anodizing process is determined by the pattern of the insulating layer formed in the insulating layer forming process, the porous portion formed in the anodizing process The in-plane distribution of thickness can be controlled, and it is possible to form a porous part with a continuously varying thickness. In addition, in the anode formation process, the anode is formed in ohmic contact with the semiconductor substrate. In the anodic oxidation step, the entire region of the porous portion formation region on the other surface of the semiconductor substrate is brought into contact with the electrolytic solution, and a solution for etching and removing oxides of the constituent elements of the semiconductor substrate is used as the electrolytic solution. Since it is used, a porous portion having a desired thickness distribution can be easily formed by a single anodizing step, and the desired lens shape can be obtained by removing the porous portion in the porous portion removing step. Since the semiconductor lens is formed, it is possible and the surface is easily form a smooth semiconductor lens in arbitrary shape. Further, since the in-plane distribution of the current density of the current flowing through the semiconductor substrate in the anodic oxidation process is determined by the insulating layer pattern, the in-plane distribution of the current density is determined by the anode pattern as in the first aspect of the invention. Thus, a semiconductor substrate having a low resistivity can be used.

  According to a fourth aspect of the present invention, there is provided a semiconductor lens manufacturing method for manufacturing a semiconductor lens by removing a part of a semiconductor substrate, wherein an insulating layer having a pattern designed according to a desired lens shape is provided on one surface side of the semiconductor substrate. An insulating layer forming step to be formed, and a current-carrying electrode disposed opposite to the one surface side of the semiconductor substrate in a current-carrying electrolyte solution in contact with the surface of the semiconductor substrate and the surface of the insulating layer and in ohmic contact with the semiconductor substrate Porous part which becomes a removal site by making the other surface side of the semiconductor substrate porous by energizing between the cathode disposed opposite to the other surface side of the semiconductor substrate in the electrolytic solution for anodic oxidation An anodizing step for forming the porous portion and a porous portion removing step for removing the porous portion. In the anodizing step, the entire area of the porous portion formation region on the other surface of the semiconductor substrate is anodized. Electric Brought into contact with the liquid, and, as an electrolyte for anodic oxidation, is characterized by using a solution to etch away the oxide of the constituent elements of the semiconductor substrate.

  According to the present invention, since the in-plane distribution of the current density of the current flowing to the other surface side of the semiconductor substrate in the anodizing step is determined by the pattern of the insulating layer formed in the insulating layer forming step, it is formed in the anodizing step. It is possible to control the in-plane distribution of the thickness of the porous portion to be formed, and to form a porous portion having a continuously changing thickness, and in the anodizing step, the other surface of the semiconductor substrate Since the entire region of the porous portion formation region is brought into contact with the anodizing electrolyte, and a solution for removing oxides of constituent elements of the semiconductor substrate by etching is used as the anodizing electrolyte, the desired thickness is obtained. A porous portion having a thickness distribution can be easily formed by a single anodizing step, and a semiconductor lens having a desired lens shape is formed by removing the porous portion in the porous portion removing step. , And surface meaning shape it is possible to easily form a smooth semiconductor lenses. In the anodizing step, the energizing electrode disposed in the energizing electrolyte in contact with the one surface of the semiconductor substrate and the surface of the insulating layer and the other surface side of the semiconductor substrate are disposed in the anodizing electrolyte. Since the porous portion is formed by energizing between the negative electrode and the negative electrode, the anode forming step in the invention of claim 3 is unnecessary, and the number of steps can be reduced as compared with the invention of claim 3. There is.

  According to a fifth aspect of the present invention, in the third or fourth aspect of the present invention, in the insulating layer forming step, after forming an insulating film serving as a basis of the insulating layer on the one surface side of the semiconductor substrate, the insulating film The insulating layer is formed by patterning in a circular shape.

  According to the present invention, the current density of the current flowing through the semiconductor substrate in the anodizing step has an in-plane distribution that decreases as it approaches the center line of the insulating layer that matches the thickness direction of the semiconductor substrate. In the semiconductor substrate, the closer to the center line of the insulating layer, the thinner the porous portion, and an aspherical lens having a smooth surface can be formed as a semiconductor lens.

  According to a sixth aspect of the present invention, in any of the third to fifth aspects of the present invention, the insulating layer is made of a silicon oxide film or a silicon nitride film.

  According to the present invention, since the insulating layer can be easily formed generally by a semiconductor manufacturing process, and the positional accuracy and pattern accuracy of the insulating layer can be increased, a semiconductor lens with less distortion is formed. Can do.

  The invention of claim 7 is characterized in that, in the invention of claims 1 to 6, in the anodizing step, the shape of the porous portion is controlled by adjusting an electric resistance value of the electrolytic solution. To do.

  According to this invention, it becomes easier to control the shape of the porous portion.

  The invention of claim 8 is the first porous part removing step of removing the first porous part, which is the porous part, in the porous part removing step in the invention of claim 1 to claim 7. The second porous portion having a thickness distribution corresponding to a desired lens shape on the one surface side of the semiconductor substrate after the first porous portion removing step. The second porous portion is removed after the formation by the anodizing step described in the item.

  According to this invention, a biconvex lens, a biconcave lens, an uneven lens, or the like can be formed as a semiconductor lens.

  In the inventions of claims 1 to 8, there is an effect that it is possible to easily form a semiconductor lens having an arbitrary shape and a smooth surface.

(Embodiment 1)
In this embodiment, as a semiconductor lens manufacturing method for manufacturing a semiconductor lens by removing a part of a semiconductor substrate, a part of a semiconductor substrate 10 (see FIG. 1A) made of a silicon substrate is subjected to an anodic oxidation process. A manufacturing method for manufacturing a semiconductor lens 1 (see FIG. 1 (e)) made of a silicon lens by removing the porous portion 14 (see FIG. 1 (d)) made of porous silicon formed by making it porous. Illustrate. Here, the semiconductor lens 1 in the present embodiment is a plano-convex aspherical lens. In the present embodiment, a semiconductor substrate 10 having a p-type conductivity is used and the resistivity of the semiconductor substrate 10 is set to 80 Ωcm. However, this value is not particularly limited.

  Hereinafter, the manufacturing method of the semiconductor lens 1 described above will be described with reference to FIGS.

First, an anode 12 (FIG. 1) used in an anodic oxidation process described later on one surface side (a lower surface side of FIG. 1A) of a semiconductor substrate (wafer until dicing described later) 10 shown in FIG. (C) and conductive property for forming the conductive layer 11 made of a conductive film (for example, an Al film, an Al-Si film, etc.) having a predetermined film thickness (for example, 1 μm), which is the basis of FIG. By performing the layer forming step, the structure shown in FIG. 1B 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, ohmic contact between the conductive layer 11 and the semiconductor substrate 10 is obtained. 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.

  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 or an Al—Si film, when unnecessary portions of the conductive layer 11 are removed by 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. In the present embodiment, the anode 12 having a pattern designed according to a desired lens shape is brought into ohmic contact with the semiconductor substrate 10 on the one surface side of the semiconductor substrate 10 in the conductive layer forming process and the patterning process. Thus, the anode forming step is formed. The radius of the circular aperture 13 is set to 1 mm, but this value is not particularly limited and 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. 3) and the anode disposed opposite to the other surface side (the upper surface side of FIG. 1A) of the semiconductor substrate 10 in the electrolytic solution B for anodization (see FIG. 3). 1 (d), an anodic oxidation process (anodic oxidation process) is performed to form a porous portion 14 made of porous silicon serving as a removal site on the other surface side of the semiconductor substrate 10 by energizing the semiconductor substrate 10 as shown in FIG. ) Is obtained.

Here, in the anodizing step, an anodizing apparatus A having the configuration shown in FIG. 3 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 hydrofluoric acid in which a 55 wt% aqueous solution of hydrogen fluoride and ethanol are mixed at a ratio of 1: 1 as a solution for etching and removing SiO ₂ that is an oxide of Si that is a constituent element of the semiconductor substrate 10. Although the system solution is used, 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. In the anodizing step, energization is performed under a condition of a predetermined current density, but energization may be performed under a condition of a predetermined voltage.

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 p-type 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 ^+. Porous formation occurs when the supply amount of H is greater than the supply amount of holes, and electropolishing occurs when the supply amount of holes h ⁺ is greater than the supply amount of F ions. Therefore, when a p-type silicon substrate is used as the semiconductor substrate 10 as in the present embodiment, 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 the present embodiment, current flows through the semiconductor substrate 10 along the path indicated by the arrow in FIG. 4, and therefore, on the other surface side (upper surface side in FIG. 4) of the semiconductor substrate 10, The in-plane distribution of the current density is such that the current density gradually increases as the distance from the center line (the center line along the thickness direction of the semiconductor substrate 10) increases, and is formed on the other surface side of the semiconductor substrate 10. The porous portion 14 is gradually thinner as it approaches the center line of the aperture 13 of the anode 12. The in-plane distribution of the current density described above corresponds to the distribution of the electric field strength in the semiconductor substrate 10 determined by the contact pattern between the anode 12 and the semiconductor substrate 10 when the anode 12 and the cathode 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, 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 made of porous silicon, the porous portion 14 is removed. In the part removing step, 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. 1E and 2B can be obtained. Therefore, after that, a dicing process for separating the individual semiconductor lenses 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. In addition, when an alkaline solution is used as an etching solution in the porous portion removing step for removing the porous portion 14 made of porous silicon, the porous portion 14 is removed by etching at room temperature without heating the etching solution. Can do.

  According to the manufacturing method of the semiconductor lens 1 of the present embodiment described above, the in-plane distribution of the current density of the current flowing in the semiconductor substrate 10 in the anodic oxidation process is determined by the pattern of the anode 12 formed in the anode forming process. The in-plane distribution of the thickness of the porous portion 14 formed in the anodizing step can be controlled, and the porous portion 14 having a continuously changing thickness can be formed. In addition, in the anode forming step, The anode 12 is formed in ohmic contact with the semiconductor substrate 10, and in the anodic oxidation step, the entire region of the porous portion 14 to be formed on the other surface of the semiconductor substrate 10 is brought into contact with the electrolyte B, and As the electrolytic solution B, a solution made of a hydrofluoric acid-based solution that removes the oxide of the constituent element of the semiconductor substrate 10 by etching is used. Since the semiconductor lens 1 having a desired lens shape can be formed by removing the porous portion 14 in the porous portion removing step, the surface can be formed into an arbitrary shape and smooth. The semiconductor lens 1 can be easily formed.

  Here, in the anode forming step in this embodiment, 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) Since the in-plane distribution becomes smaller as it approaches the center line of the aperture 13, the thickness of 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. Therefore, a planoconvex aspherical lens having a smooth surface can be formed as the semiconductor lens 1. The optical axis of the semiconductor lens 1 formed in this way 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 embodiment, 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 resistivity of the semiconductor substrate 10 may be set within a range of, for example, about several Ωcm to several hundred Ωcm, and the semiconductor lens 1 having a gently curved surface with a larger curvature radius as the resistivity is decreased. As the resistivity increases, the short focus semiconductor lens 1 having a smaller radius of curvature can be formed. In addition, the shorter focal length semiconductor lens 1 having a smaller radius of curvature can be formed as the semiconductor substrate 10 is thinner, and the semiconductor lens 1 having a gently curved surface having a larger radius of curvature can be formed as the thickness is larger.

  In addition, the electrical resistance value of the electrolytic solution B can be adjusted, for example, by changing the concentration of the aqueous hydrogen fluoride solution or the mixing ratio of the aqueous hydrogen fluoride solution and ethanol. By appropriately setting conditions other than the shape of the anode 12 (for example, the electric resistance value of the electrolytic solution B), it becomes easier to control the shape of the semiconductor lens 1.

  Further, as the planar shape of the cathode 25, for example, as shown in FIG. 5A, in the state of being opposed to the semiconductor substrate 10, the opening 13 of the anode 12 (see FIG. 5C) and the center line A planar shape having a circular opening portion 25a (see FIG. 5B) that coincides with each other may be employed. Here, the inner diameter of the opening portion 25a of the cathode 25 is not necessarily set to the same value as the inner diameter of the opening portion 13 of the cathode 12, and the thickness of the semiconductor substrate 10, the electric resistance value of the electrolyte B, the cathode 25, and the like. It may be set as appropriate in consideration of the distance between the semiconductor substrate 10 and the semiconductor substrate 10. 5A schematically shows a path of current flowing through the semiconductor substrate 10, and a downward arrow in FIG. 5A shows a path of electrons moving in the electrolytic solution B. This is shown schematically.

  In addition, as a parameter for controlling the lens shape, there is an anodizing process time (the above-mentioned predetermined time) in the anodizing process. The longer the processing time is, the thicker the porous part 14 is, the thicker the porous part 14 is. As the difference between the thickness of the portion and the thickness of the thin portion increases to form a curved surface with a small radius of curvature, and the processing time is short and the thickness of the porous portion 14 is reduced, the thickness of the thick portion and the thin portion in the porous portion 14 are reduced. The difference with the thickness of the film becomes small, and a curved surface with a large curvature radius can be formed.

  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. In short, if the energization conditions are changed so that the porosity of the portion on the boundary side with the semiconductor substrate 10 is smaller than the porosity of the portion on the surface side in the porous portion 14 that is the removal site at the time of the energization, The porosity of the portion on the boundary side with the semiconductor substrate 10 in the porous portion 14 is smaller than the porosity of the portion on the surface side, and fine irregularities are formed on the curved surface when the porous portion 14 is removed. Therefore, the semiconductor lens 1 having a smoother curved surface can be formed.

Further, in the semiconductor lens 1 formed by the manufacturing method of the present embodiment, as shown in FIG. 6, the lens portion 1a and the flange portion 1b surrounding the lens portion 1a over the entire circumference may be formed continuously and integrally. It becomes possible. For example, a disk-shaped silicon substrate (silicon wafer) having a diameter of 100 mm, a thickness of 0.5 mm, and a resistivity of 80 Ωcm is used as the semiconductor substrate 10, and the conductive layer 11 is used as a condition for the anode formation step. The thickness of the 1 μm thick Al film, the sintering temperature of the conductive layer 11 is 420 ° C., the sintering time is 20 minutes, the inner diameter of the circular opening 13 in the anode 12 is 2 mm, and the conditions of the anodizing step are electrolytic The liquid B is a hydrofluoric acid-based solution in which a 55 wt% hydrogen fluoride aqueous solution and ethanol are mixed at a ratio of 1: 1, the predetermined current density is 30 mA / cm ² , and the predetermined time is 180 minutes. As a condition, the surface on the convex curved surface side of the semiconductor lens 1 formed when the etching solution is 10% KOH aqueous solution and the etching time is 15 minutes (the surface of the lens portion 1a and the flange) FIG. 7 shows the result obtained by measuring the surface 1b) with a non-contact three-dimensional surface shape measuring device manufactured by Zygo, which can perform non-contact measurement of the surface shape using light interference. 7, the flat portion corresponds to the surface of the flange portion 1b, and the curved portion corresponds to the surface of the lens portion 1a. Here, the thickness of the porous portion 14 formed in the above-described anodic oxidation step gradually increases with increasing distance from the vicinity of the center line of the aperture 13 described above, and is about 0.00% near the center line of the aperture 13. About 105 mm (105 μm), the portion overlapping the anode 12 (the portion corresponding to the flange portion 1 b) was about 0.3 mm (300 μm). Further, the etching rate of the porous part 14 in the porous part removing step is 10 times or more than the etching rate of the semiconductor substrate 10, and the porous part 14 is selectively etched away from the semiconductor substrate 10 in about 15 minutes. be able to.

  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 the present embodiment, as is clear from the above description, a curved surface having a height difference of several hundred μm is formed by one anodizing step and one porous portion removing step. Therefore, not only a lens generally called a micro lens having a diameter of several hundreds of μm or less, but also a lens having a lens diameter of about several mm, one anodic oxidation step and one porous Part removing step can be formed.

  As described above, the semiconductor lens 1 in which the lens 1a and the flange portion 1b are integrally formed integrally includes an infrared detection element (for example, a pyroelectric element, a thermopile, etc.) 60 like the infrared sensor shown in FIG. Since the flange portion 1b can be fixed to the peripheral portion of the window hole 51a on the rear surface of the front wall 51 in a state where the lens portion 1a is disposed in the window hole 51a formed in the front wall 51 of the accommodated case 50, FIG. As shown in FIG. 9, it can be easily attached to the case 50 as compared with the conventional infrared lens 200 formed by polishing a silicon substrate or a germanium substrate. The case 50 in the infrared sensor shown in FIG. 8 includes a bottomed cylindrical case body 50a whose rear surface is open and a base plate 50b that closes the rear surface of the case body 50a.

  By the way, in the above-described manufacturing method, 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 plano-convex cylindrical lens as shown in FIG. 10 can be formed as the semiconductor lens 1.

  If a low-resistance semiconductor substrate having a resistivity close to that of the conductor is used as the semiconductor substrate 10 and the electric resistance value of the electrolyte B is increased, the in-plane distribution of the current density of the current flowing through the semiconductor substrate 10 will be described. Becomes susceptible to the resistance of the electrolyte B. Therefore, as shown in FIG. 11A, an anode 12 that covers the entire surface of the one surface (the lower surface in FIG. 11A) of the semiconductor substrate 10 and is in ohmic contact with the semiconductor substrate 10 is provided. If a cathode 25 having a circular aperture 25a as shown in a) and (b) is used, electrons move in the electrolyte B along the path indicated by the arrow in FIG. Therefore, on the other surface side of the semiconductor substrate 10, the current density decreases as it approaches the center line of the circular aperture 25a of the cathode 25, and the thickness decreases as it approaches the center line of the aperture 25a. The formed porous portion 14 can be formed, and a plano-convex aspherical lens can be formed as the semiconductor lens 1. Further, when the low-resistance semiconductor substrate 10 is used as described above, the anode 12 is not provided, and the one surface of the semiconductor substrate 10 in the anodizing step is applied to the energizing electrode in the anodizing apparatus A shown in FIG. You may arrange | position so that 21 may be contact | connected.

(Embodiment 2)
The manufacturing method of the semiconductor lens 1 of the present embodiment is substantially the same as that of the first embodiment, and in order to form a plano-concave aspherical lens as shown in FIGS. 12 is different from that of FIG. 12A (that is, the point where the pattern of the anode 12 is circular) as shown in FIG.

  First, by performing an anode forming step of forming an anode 12 having a circular planar shape on one surface side (the lower surface side of FIG. 14A) of a semiconductor substrate 10 made of a p-type silicon substrate, FIG. ) Is obtained.

  Thereafter, a porous portion 14 made of porous silicon is formed on the other surface side of the semiconductor substrate 10 (upper surface side in FIG. 14A) in the anodizing step, thereby obtaining the structure shown in FIG. 14B. Here, the porous portion 14 is formed in a shape in which the thickness gradually decreases as the distance from the center line of the anode 12 along the thickness direction of the semiconductor substrate 10 increases.

  Subsequently, by removing the porous portion 14 in the porous portion removing step to form a concave curved surface on the other surface side of the semiconductor substrate 10, a plano-concave aspheric lens having a structure shown in FIG. Get.

  By the way, in the manufacturing method described above, the anode 12 having a circular planar shape is formed in the anode forming step. However, if the anode 12 having a rectangular planar shape is formed (that is, the pattern of the anode 12 is a rectangular shape). Accordingly, a plano-concave cylindrical lens can be formed as the semiconductor lens 1.

(Embodiment 3)
The manufacturing method of the semiconductor lens 1 of the present embodiment is substantially the same as that of the first embodiment. In the first embodiment, the anode 12 having the circular aperture 13 is formed in the anode forming step. Insulating layer formation for forming a circular insulating layer 15 (see FIG. 15) having a pattern design according to a desired lens shape on the one surface side (lower surface side in FIG. 15) of the semiconductor substrate 10 before the anode forming step. In the anode forming step, as shown in FIG. 15, the conductive layer (for example, an Al film) that contacts the insulating layer 15 and the exposed portion of the one surface of the semiconductor substrate 10 on the one surface side of the semiconductor substrate 10. The difference is that the anode 12 made of an Al—Si film or the like is formed. Since other steps are the same as those in the first embodiment, description thereof is omitted.

  In the above-described insulating layer forming step, an insulating film (for example, a silicon oxide film, a silicon nitride film, or the like) that forms the basis of the insulating layer 15 is formed on the one surface side of the semiconductor substrate 10, and then a photolithography technique and an etching technique are performed. The insulating layer 15 is formed by patterning the insulating film into a circular shape by using it.

  Thus, according to the manufacturing method of the present embodiment, the contact pattern of the anode 12 with respect to the semiconductor substrate 10 is determined by the pattern of the insulating layer 15 formed in the insulating layer forming step, and the anode is determined by the contact pattern and the pattern of the insulating layer 15. Since the in-plane distribution of the current density of the current flowing through the semiconductor substrate 10 in the oxidation process is determined, the in-plane distribution of the thickness of the porous portion 14 formed in the anodic oxidation process can be controlled as in the first embodiment. It is possible to form a porous portion 14 made of porous silicon having a continuously changing thickness, and removing the porous portion 14 in the porous portion removing step allows the semiconductor lens 1 having a desired lens shape. Therefore, it is possible to easily form the semiconductor lens 1 having an arbitrary shape and a smooth surface.

  Here, in the present embodiment, the insulating layer 15 in which the current density of the current flowing through the semiconductor substrate 10 on the other surface side (the upper surface side in FIG. 14) of the semiconductor substrate 10 in the anodic oxidation process coincides with the thickness direction of the semiconductor substrate 10. Therefore, the closer to the center line of the insulating layer 15, the thinner the porous portion 14 becomes, and the surface of the semiconductor lens 1 becomes smoother. An aspheric lens having a convex surface can be formed. The optical axis of the semiconductor lens 1 thus formed coincides with the center line of the insulating layer 15.

  In this embodiment, since the insulating layer 15 is composed of an insulating film made of a silicon oxide film or a silicon nitride film, the insulating layer 15 can generally be easily formed by a semiconductor manufacturing process. Since the position accuracy and pattern accuracy of 15 can be increased, the semiconductor lens 1 with less distortion can be formed. The insulating film is not limited to a silicon-based insulating film such as a silicon oxide film or a silicon nitride film, and may be formed of an organic material such as a resist.

  In the present embodiment, since the contact pattern between the anode 12 and the semiconductor substrate 10 and the pattern of the insulating layer 15 control the in-plane distribution of the current density of the current flowing through the semiconductor substrate 10 in the anodic oxidation process, Thus, compared to the case where the in-plane distribution of the current density is controlled mainly only by the contact pattern between the anode 12 and the semiconductor substrate 10, it is possible to use a semiconductor substrate having a lower resistivity.

  In this embodiment, the insulating layer 15 is a circular pattern, but the pattern of the insulating layer 15 may be appropriately designed according to a desired lens shape. If the insulating layer 15 is a rectangular pattern, A cylindrical lens having a convex curved surface can be formed, and if the insulating layer 15 is formed in a pattern having a circular aperture, an aspherical lens having a concave curved surface can be formed, and the insulating layer 15 can be formed into a rectangular shape. If it is formed in a pattern having an aperture, a cylindrical lens having a concave curved surface can be formed.

(Embodiment 4)
The manufacturing method of the semiconductor lens 1 of the present embodiment is substantially the same as that of the first embodiment. Instead of the anode forming step in the first embodiment, a planar shape in which a pattern is designed according to a desired lens shape as shown in FIG. Is different in that an insulating layer forming step of forming the circular insulating layer 16 on the one surface side of the semiconductor substrate 10 is adopted. In the anodizing step, an anodizing apparatus D as shown in FIG. 17 is used, and the one surface of the semiconductor substrate 10 (the right side in FIG. 17) of the semiconductor substrate 10 made of a p-type silicon substrate is used. A current-carrying electrode 21 comprising a platinum electrode disposed opposite to the one surface side of the semiconductor substrate 10 in the current-carrying electrolyte C in contact with the surface and the surface of the insulating layer 16 and in ohmic contact with the semiconductor substrate 10; 10 on the other surface side (left surface side in FIG. 17) from the voltage source 31 between the cathode 25 made of a platinum electrode disposed opposite to the other surface side of the semiconductor substrate 10 in the electrolytic solution B for anodic oxidation. By doing so, the other surface side of the semiconductor substrate 10 is made porous so that the porous portion 14 serving as a removal site is formed. Here, as each of the electrolytic solutions B and C, a mixed solution in which a 55 wt% aqueous solution of hydrogen fluoride and ethanol are mixed at a ratio of 1: 1 is used. The concentration of the aqueous solution of hydrogen fluoride or the aqueous solution of hydrogen fluoride and ethanol is used. The mixing ratio is not particularly limited, and the solution mixed with the hydrogen fluoride solution is not limited to ethanol as described above. Since other steps are the same as those in the first embodiment, description thereof is omitted.

  The anodizing apparatus D shown in FIG. 17 has a first processing tank member 41 that has an upper surface opened and an opening window 41a is formed on the right side wall in FIG. 17 and constitutes a first processing tank together with the semiconductor substrate 10. The upper surface is opened and an opening window 42 a is formed on the left side wall in FIG. 17, and the second processing tank member 42 that constitutes the second processing tank together with the semiconductor substrate 10, and the other surface side of the semiconductor substrate 10. A seal member 43 formed of an O-ring interposed between the peripheral portion and the peripheral portion of the opening window 41a in the right side wall of the first processing tank member 41; the peripheral portion on the one surface side of the semiconductor substrate 10; And a sealing member 44 made of an O-ring interposed between the left side wall of the processing tank member 42 and the peripheral portion of the opening window 42a, and the electrolytic solution B for anodization is placed in the first processing tank. Passed through the second treatment tank Electrolyte C of use is placed. The treatment tank members 41 and 42 may be made of a material having resistance to the electrolytic solutions B and C, for example, a fluorine resin such as Teflon (registered trademark).

In addition, the anodizing device D is based on the current sensor 32 that detects the current flowing from the voltage source 31 to the energizing electrode 21 and the detected current of the current sensor 32 in the same manner as the anodizing device A described in the first embodiment. And a control unit 33 composed of a microcomputer for controlling the output voltage of the voltage source 31, and the control unit 33 has a predetermined current density (for example, 30 mA / cm ² ) from the voltage source 31 to the energizing electrode 21. The voltage source 31 is controlled so that the current flows for a predetermined time (for example, 120 minutes). 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.

  Thus, according to the manufacturing method of the present embodiment, the in-plane distribution of the current density of the current flowing to the other surface side of the semiconductor substrate 10 in the anodic oxidation step is caused by the pattern of the insulating layer 16 formed in the insulating layer forming step. Therefore, the in-plane distribution of the thickness of the porous portion 14 formed in the anodic oxidation process can be controlled, and the porous portion 14 having a continuously changing thickness can be formed. In the oxidation step, the entire region of the porous portion 14 to be formed on the other surface of the semiconductor substrate 10 is brought into contact with the electrolytic solution B for anodic oxidation, and the configuration of the semiconductor substrate 10 is used as the electrolytic solution B for anodic oxidation. Since a solution made of a hydrofluoric acid-based solution for removing the oxide of the element by etching is used, the porous portion 14 having a desired thickness distribution can be easily formed by a single anodic oxidation process. The Since the semiconductor lens 1 having a desired lens shape is formed by removing at porosifying portion removing step, it is possible and the surface in any shape to form a smooth semiconductor lens 1 easily. In the anodic oxidation step, the energizing electrode 21 and the semiconductor substrate disposed in the energizing electrolyte C in contact with the one surface of the semiconductor substrate 10 and the surface of the insulating layer 16 on the one surface side of the p-type silicon substrate 10. Since the porous portion 14 is formed by energizing the cathode 25 disposed in the electrolytic solution B for anodic oxidation on the other surface side of 10 described above, the anode forming step described in the second embodiment is unnecessary. There is an advantage that the number of steps can be reduced as compared with the manufacturing method of the second embodiment.

(Embodiment 5)
In this embodiment, as a method for manufacturing the semiconductor lens 1, a manufacturing method for manufacturing a biconvex aspherical lens as shown in FIG. 18 (h) will be described with reference to FIG. Description of this process will be omitted as appropriate.

  First, a predetermined film thickness serving as a basis for the anode 12 (see FIG. 18C) used in the anodizing process on one surface side (the lower surface side in FIG. 18A) of the semiconductor substrate 10 shown in FIG. The structure shown in FIG. 18B is obtained by performing a conductive layer forming step of forming a conductive layer 11 made of a conductive film (for example, 1 μm) (for example, an Al film, an Al—Si film, etc.). .

  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, thereby obtaining the structure shown in FIG. In the conductive layer forming step and the patterning step, a pattern was designed according to the shape (curvature radius, etc.) of the first convex curved surface Cv1 (see FIG. 18 (e)), which is one convex curved surface of the desired lens shape. An anode forming step (hereinafter referred to as a first anode forming step) for forming an anode (hereinafter referred to as a first anode) 12 is configured.

  After the patterning step, a cathode (hereinafter referred to as a first electrode) disposed opposite to the other surface side (the upper surface side of FIG. 18A) of the semiconductor substrate 10 in an electrolyte for anodization (hereinafter referred to as a first electrolyte). The porous portion 14 (hereinafter referred to as the first porous portion) made of porous silicon which becomes a removal site on the other surface side of the semiconductor substrate 10 by energizing between the first anode 12 and the first anode 12. The structure shown in FIG. 18D is obtained by performing an anodic oxidation step (hereinafter referred to as a first anodic oxidation step).

  After the end of the first anodizing step, a porous portion removing step for removing the first porous portion 14 (hereinafter referred to as a first porous portion removing step) is performed. Here, if an alkaline solution or an HF solution is used as an etching solution for removing the first porous portion 14 as in the first embodiment, the first anode 12 is also etched in the first porous portion removing step. The structure shown in FIG. 18E can be obtained.

  After the first porous portion removing step described above, a first anode forming step is performed on the other surface side where the first convex curved surface Cv1 is formed by removing the first porous portion 14 in the semiconductor substrate 10. Similarly, the second anode 17 having a pattern designed according to the shape (curvature radius, etc.) of the second convex curved surface Cv2 which is the other convex curved surface of the desired lens shape is formed, as shown in FIG. Get the structure. The second anode 17 is formed so as to be in ohmic contact with the semiconductor substrate 10, similarly to the first anode 12. Further, the second anode 17 is designed in such a pattern that a circular opening portion whose center line coincides with the circular opening portion 13 of the first anode 12 is provided.

  Thereafter, a current is passed between the second cathode 17 and the second anode 17 disposed opposite to the one surface side of the semiconductor substrate 10 in the second electrolytic solution for anodic oxidation, and the one surface side of the semiconductor substrate 10. A structure shown in FIG. 18G is obtained by performing a second anodic oxidation step for forming a second porous portion 18 made of porous silicon to be a removal site. As the second electrolytic solution, a hydrofluoric acid solution is used as in the first electrolytic solution, and platinum is adopted as the material of the second cathode as in the first cathode.

  After the completion of the second anodizing step, a second porous portion removing step for removing the second porous portion 18 is performed. Here, if an alkaline solution or an HF-based solution is used as an etching solution for removing the second porous portion 18 as in the first porous portion removing step, the second porous portion removing step uses the second porous portion 18 in the second porous portion removing step. The anode 17 can also be removed by etching, and the semiconductor lens 1 having the structure shown in FIG. 18H can be obtained. Thereafter, a dicing process for separating the individual semiconductor lenses 1 may be performed. Note that the second porous portion removing step for removing the second porous portion 18 and the second anode removing step for removing the second anode 17 may be performed separately.

  Thus, in the manufacturing method of the present embodiment, a biconvex aspherical lens having a smooth surface can be formed as the semiconductor lens 1.

(Embodiment 6)
In the present embodiment, as a method for manufacturing the semiconductor lens 1, a manufacturing method for manufacturing a concavo-convex aspherical lens as shown in FIG. 19F will be described with reference to FIG. Explanation of the steps is omitted as appropriate. In the present embodiment, a semiconductor substrate 10 having a p-type conductivity is used as in the first embodiment, but the impurity concentration is a low impurity concentration of 1 × 10 ¹⁶ cm ⁻³ or less, and the resistivity Is 1 Ωcm or more. In addition, each center line described below means a center line along the thickness direction of the semiconductor substrate 10 as in the first embodiment.

  First, in accordance with the shape (curvature radius, etc.) of a concave curved surface Cc (see FIG. 19F), which is one curved surface of a desired lens shape, on one surface side of the semiconductor substrate 10 (the lower surface side of FIG. 19A). The structure shown in FIG. 19A is obtained by performing an anode formation step (hereinafter referred to as a first anodic oxidation step) for forming a circular anode (hereinafter referred to as a first anode) 12 having a pattern design. Get. Here, the first anode 12 needs to be formed so that the center line coincides with the center line of the region where the semiconductor lens 1 is to be formed in the semiconductor substrate 10.

  After the first anode forming step, the cathode disposed opposite to the other surface side (the upper surface side of FIG. 19A) of the semiconductor substrate 10 in the electrolytic solution for anodic oxidation (hereinafter referred to as the first electrolytic solution). (Hereinafter referred to as a first cathode) and a first anode 12 and a porous portion 14 (hereinafter referred to as a first cathode) made of porous silicon which becomes a removal site on the other surface side of the semiconductor substrate 10 by energization. The structure shown in FIG. 19B is obtained by performing an anodic oxidation step (hereinafter referred to as a first anodic oxidation step) for forming a porous portion 14). In the first anodic oxidation step, the current flows more easily in the region where the first anode 12 is formed in the semiconductor substrate 10, and it becomes difficult for the current to flow gradually away from the region. Of these, the current density in the region overlapping the first anode 12 is increased, and the first porous portion 13 is gradually reduced in thickness as the distance from the center line of the first anode 12 increases.

  After the first anodic oxidation step, the first porous portion 14 is removed to perform the first porous portion removing step of forming the concave curved surface Cc on the other surface side of the semiconductor substrate 10. The structure shown in 19 (c) is obtained. Here, since the alkaline solution is used as the etching solution for removing the first porous portion 14 as in the first embodiment, the first anode 12 is also used when the first porous portion 14 is removed. Can be removed. Depending on the material of the first anode 12, the porous portion removing step for removing the first porous portion 14 and the anode removing step for removing the first anode 12 may be performed separately.

  After the first porous portion removing step, the second anode 17 having a pattern designed according to the shape (curvature radius, etc.) of the convex curved surface Cv (see FIG. 19F), which is the other curved surface of the desired lens shape. By performing a second anode forming step for forming the semiconductor substrate 10 on the other surface side, the structure shown in FIG. 19D is obtained. The second anode 17 has a circular opening 17a, and the dimensions of the opening 17a are designed based on a desired radius of curvature of the convex curved surface Cv. The second anode 17 is formed so as to be in ohmic contact with the semiconductor substrate 10, similarly to the first anode 12.

  After the second anode forming step described above, a current is passed between the second cathode 17 and the second anode 17 disposed opposite to the one surface side of the semiconductor substrate 10 in the second electrolytic solution for anodization. Then, by performing a second anodizing step for forming a second porous portion 18 made of porous silicon serving as a removal site on the one surface side of the semiconductor substrate 10, the structure shown in FIG. . The second electrolytic solution is the same hydrofluoric acid solution as the first electrolytic solution, and the second cathode material is platinum as in the first cathode. Here, in the second anodic oxidation step, the second anode 17 on the other surface side of the semiconductor substrate 10 is formed around the concave curved surface Cc (in other words, not formed on the concave curved surface Cc). Therefore, the current density of the current flowing through the semiconductor substrate 10 decreases as it approaches the center line of the opening 17a of the second anode 17 (that is, the surface whose current density decreases as it approaches the center line passing through the center of the concave surface Cc). The second porous portion 18 formed on the one surface side of the semiconductor substrate 10 is gradually thinner as it approaches the center line of the concave curved surface Cc.

  After the second anodic oxidation step, the second porous portion 18 is removed to perform the second porous portion removing step of forming the convex curved surface Cv on the one surface side of the semiconductor substrate 10. The semiconductor lens 1 having the structure shown in 19 (f) can be obtained. In this embodiment, since the alkaline solution described in the first embodiment is used as the etching solution for removing the second porous portion 18, the second porous portion 18 is removed when the second porous portion 18 is removed. The second anode 17 can also be removed. Note that the second anode 17 is not necessarily removed, and may be left as an infrared light shielding mask in the semiconductor lens 1. Since the semiconductor substrate 10 is in a wafer state until the second porous portion removing step, a dicing step for separating the wafer from the wafer into individual semiconductor lenses 1 may be performed after the second porous portion removing step. .

  According to the manufacturing method of the semiconductor lens 1 of the present embodiment described above, the current flowing through the semiconductor substrate 10 in the first anodic oxidation process by the pattern of the first anode 12 formed in the first anode forming process. Since the in-plane distribution of the density is determined, it becomes easy to control the in-plane distribution of the thickness of the first porous portion 14 formed in the first anode forming step, and as a result, the first porous portion removing step is performed. Thus, the concave curved surface Cc having a desired radius of curvature can be formed, and the in-plane distribution of the thickness of the semiconductor substrate 10 after the first porous portion removing step and the second anode forming step are used. The in-plane distribution of the current density of the current flowing through the semiconductor substrate 10 in the second anodic oxidation process is determined by the pattern of the two anodes 17, and as a result, a convexity of a desired curvature radius is obtained in the second porous portion removing process. A curved surface Cv can be formed Et al, it is possible curvature radius respective radii of curvature and the convex curved surface Cv of the concave surface Cc to easily form a semiconductor lens 1 constituting the large concave and convex lenses as compared to the thickness of the semiconductor substrate 10. The optical axis of the semiconductor lens 1 formed by the manufacturing method described above coincides with the center line of the first anode 12 and the center line of the aperture 17a of the second anode 17 described above.

(Embodiment 7)
In the present embodiment, as a method for manufacturing the semiconductor lens 1, a manufacturing method for manufacturing a concavo-convex aspherical lens as shown in FIG. 20E will be described with reference to FIG. Explanation of the steps is omitted as appropriate. In the present embodiment, a semiconductor substrate 10 having a p-type conductivity is used as in the first embodiment, but the impurity concentration is a low impurity concentration of 1 × 10 ¹⁶ cm ⁻³ or less, and the resistivity Is 1 Ωcm or more. In addition, each center line described below means a center line along the thickness direction of the semiconductor substrate 10 as in the first embodiment.

  First, according to the shape (curvature radius, etc.) of the convex curved surface Cv (see FIG. 20 (e)) which is one curved surface of the desired lens shape on one surface side (the lower surface side of FIG. 20 (a)) of the semiconductor substrate 10. A structure shown in FIG. 20A is obtained by performing an anode forming step (hereinafter referred to as a first anodic oxidation step) for forming a patterned anode (hereinafter referred to as a first anode) 12. Here, the first anode 12 has an opening 13 whose center line coincides with the center line of the region where the semiconductor lens 1 is to be formed in the semiconductor substrate 10.

  After the first anode forming step, the cathode disposed opposite to the other surface side (the upper surface side of FIG. 20A) of the semiconductor substrate 10 in the electrolytic solution for anodic oxidation (hereinafter referred to as the first electrolytic solution). (Hereinafter referred to as a first cathode) and a first anode 12 and a porous portion 14 (hereinafter referred to as a first cathode) made of porous silicon which becomes a removal site on the other surface side of the semiconductor substrate 10 by energization. The structure shown in FIG. 20B is obtained by performing an anodic oxidation step (hereinafter referred to as a first anodic oxidation step) for forming a porous portion 14).

  After the first anodizing step, the first porous portion 14 is removed to form a convex curved surface Cv on the other surface side of the semiconductor substrate 10 (hereinafter referred to as the first porous portion). After that, the shape of the concave curved surface Cc (see FIG. 20E), which is the other curved surface of the desired lens shape, at the center of the convex curved surface Cv on the other surface side of the semiconductor substrate 10 is performed. The structure shown in FIG. 20C is obtained by performing a second anode forming step of forming a circular second anode 17 whose pattern is designed according to the radius of curvature. The second anode 17 needs to be formed so that the center line coincides with the center line of the region where the semiconductor lens 1 is to be formed (the center line of the convex curved surface Cv) and has a diameter smaller than the lens diameter. The second anode 17 is formed so as to be in ohmic contact with the semiconductor substrate 10, similarly to the first anode 12.

  After the second anode forming step described above, a second cathode and a second anode 17 which are disposed opposite to the one surface side of the semiconductor substrate 10 in the second electrolyte solution placed in the treatment tank for anodization, 20 (d) by conducting a second anodizing step of forming a second porous portion 18 made of porous silicon which becomes a removal site on the one surface side of the semiconductor substrate 10 by energizing during this period. The structure shown in is obtained. The second electrolytic solution is the same hydrofluoric acid solution as the first electrolytic solution, and the second cathode material is platinum as in the first cathode. Here, in the second anodic oxidation step, since the second anode 17 on the other surface side of the semiconductor substrate 10 is formed at the central portion of the convex curved surface Cv, the current density of the current flowing through the semiconductor substrate 10 is the first density. The second porous portion 18 formed on the one surface side of the semiconductor substrate 10 is away from the center line of the second anode 17. It gets thinner gradually as you leave.

  After the second anodizing step, the second porous portion 18 is removed to form a concave curved surface Cc on the one surface side of the semiconductor substrate 10 by removing the second porous portion 18. The semiconductor lens 1 having the structure shown in 20 (e) can be obtained. In this embodiment, since the alkaline solution described in the first embodiment is used as the etching solution for removing the second porous portion 18, the second porous portion 18 is removed when the second porous portion 18 is removed. The second anode 17 can also be removed. Note that the second anode 17 is not necessarily removed, and may be left as an infrared light shielding mask in the semiconductor lens 1. Since the semiconductor substrate 10 is in a wafer state until the second porous portion removing step, a dicing step for separating the wafer from the wafer into individual semiconductor lenses 1 may be performed after the second porous portion removing step. .

  According to the manufacturing method of the semiconductor lens 1 of the present embodiment described above, the current flowing through the semiconductor substrate 10 in the first anodic oxidation process by the pattern of the first anode 12 formed in the first anode forming process. Since the in-plane distribution of the density is determined, it becomes easy to control the in-plane distribution of the thickness of the first porous portion 14 formed in the first anode forming step, and as a result, the first porous portion removing step is performed. Thus, a convex curved surface Cv having a desired radius of curvature can be formed, and the first in-plane distribution of the thickness of the semiconductor substrate 10 after the first porous portion removing step and the second anode forming step are used. The in-plane distribution of the current density of the current flowing in the semiconductor substrate 10 in the second anodic oxidation process is determined by the pattern of the two anodes 17, and as a result, a concave having a desired radius of curvature is obtained in the second porous portion removing process. A curved surface Cc can be formed. Et al., Each curvature radius of the curvature radius and the concave surface Cc convex surface Cv can be easily formed of a semiconductor lens 1 constituting the large concave and convex lenses as compared to the thickness of the semiconductor substrate 10. The optical axis of the semiconductor lens 1 formed by the manufacturing method described above coincides with the center line of the aperture 13 of the first anode 12 and the center line of the second anode 17.

(Embodiment 8)
In the present embodiment, as a method for manufacturing the semiconductor lens 1, a manufacturing method for manufacturing a biconcave aspherical lens as shown in FIG. 21 (f) will be described with reference to FIG. Explanation of the steps is omitted as appropriate. In the present embodiment, a semiconductor substrate 10 having a p-type conductivity is used as in the first embodiment, but the impurity concentration is a low impurity concentration of 1 × 10 ¹⁶ cm ⁻³ or less, and the resistivity Is 1 Ωcm or more. In addition, each center line described below means a center line along the thickness direction of the semiconductor substrate 10 as in the first embodiment.

  First, the shape (curvature radius, etc.) of the first concave curved surface Cc1 (see FIG. 21C), which is one concave curved surface of a desired lens shape, on one surface side of the semiconductor substrate 10 (the lower surface side of FIG. 21A). ), An anode forming step (hereinafter referred to as a first anodic oxidation step) for forming a circular anode (hereinafter referred to as a first anode) 12 having a pattern designed according to FIG. 21A is performed. The structure shown in is obtained. Here, the first anode 12 needs to be formed so that the center line coincides with the center line of the region where the semiconductor lens 1 is to be formed in the semiconductor substrate 10.

  After the first anode forming step, the cathode disposed opposite to the other surface side of the semiconductor substrate 10 (the upper surface side in FIG. 21A) in the electrolytic solution for anodic oxidation (hereinafter referred to as the first electrolytic solution). (Hereinafter referred to as a first cathode) and a first anode 12 and a porous portion 14 (hereinafter referred to as a first cathode) made of porous silicon which becomes a removal site on the other surface side of the semiconductor substrate 10 by energization. The structure shown in FIG. 21B is obtained by performing an anodic oxidation step (hereinafter referred to as a first anodic oxidation step) for forming a porous portion 14). In the first anodic oxidation step, the current flows more easily in the region where the first anode 12 is formed in the semiconductor substrate 10, and it becomes difficult for the current to flow gradually away from the region. Of these, the current density in the region overlapping the first anode 12 is increased, and the first porous portion 13 is gradually reduced in thickness as the distance from the center line of the first anode 12 increases.

  After the first anodic oxidation step, by performing the first porous portion removing step of forming the first concave curved surface Cc1 on the other surface side of the semiconductor substrate 10 by removing the first porous portion 14 The structure shown in FIG. 21C is obtained. Here, since the alkaline solution described in the first embodiment is used as the etching solution for removing the first porous portion 14, the first anode 12 is removed when the first porous portion 14 is removed. Can also be removed. Depending on the material of the first anode 12, the porous portion removing step for removing the first porous portion 14 and the anode removing step for removing the first anode 12 may be performed separately.

By performing an insulating film forming step of forming an insulating film 19 made of a SiO ₂ film having a predetermined film thickness (for example, 200 nm) on the entire surface of the other surface side of the semiconductor substrate 10 after the first porous portion removing step. The structure shown in FIG. 21 (d) is obtained. Here, the insulating film 19 may be formed by a general thin film forming technique such as a CVD method. The insulating film 19 is not limited to the SiO ₂ film, and the SiO ₂ film except an inorganic film such as a SiON film or _{the Si} 3 _{N 4} film, or an organic film such as a resist film.

  After the insulating film forming step, the insulating film 19 has a circular shape whose dimension (inner diameter) is designed based on the shape (curvature radius, etc.) of the second concave curved surface Cc2 (see FIG. 21 (f)) which is the other concave curved surface. A second anode 17 is formed on the entire surface of the other surface side of the semiconductor substrate 10 after performing the opening portion forming step of exposing a part of the first concave curved surface Cc1 by forming the opening portion 19a. By performing the anode forming step 2, the structure shown in FIG. 21E is obtained. In other words, the pattern of the second anode 17 is designed according to the shape of the second concave curved surface Cc2. The second anode 17 is formed so as to be in ohmic contact with the semiconductor substrate 10, similarly to the first anode 12.

  After the second anode forming step, the second cathode and the second cathode disposed opposite to the one surface side of the semiconductor substrate 10 in the second electrolytic solution placed in a treatment tank (not shown) for anodization. By performing a second anodic oxidation step of forming a second porous portion 18 made of porous silicon which becomes a removal site on the one surface side of the semiconductor substrate 10 by energizing between the anode 17 and FIG. The structure shown in (e) is obtained. As the second electrolytic solution, a mixed solution in which a 55 wt% aqueous solution of hydrogen fluoride and ethanol are mixed at a ratio of 1: 1 as in the first electrolytic solution is used. Similar to the cathode of No. 1, platinum is adopted. Here, in the second anodic oxidation step, only a part of the second anode 17 is directly formed on the first concave curved surface Cc1 through the opening 19a of the insulating film 19 on the other surface side of the silicon substrate 10. Since the other portions are formed on the insulating film 19, the current density of the current flowing through the semiconductor substrate 10 gradually decreases as the distance from the center line of the second anode 17 increases (that is, in the current density plane). The distribution is an in-plane distribution in which the current density decreases as the distance from the center line passing through the center of the first concave curved surface Cc1 decreases), and the second porous portion 18 formed on the one surface side of the semiconductor substrate 10 The thickness gradually decreases as the distance from the center line of the 1-concave curved surface Cc1 increases. That is, since the second porous portion 18 is formed over a wider range than the opening portion 19a, the inner diameter of the above-described opening portion 19a needs to be smaller than the lens diameter of the desired semiconductor lens 1. is there.

  After the second anodic oxidation step, a second porous portion removing step is performed in which the second porous portion 18 is removed to form the second concave curved surface Cc2 on the one surface side of the semiconductor substrate 10, and thereafter The semiconductor lens 1 having the structure shown in FIG. 21F can be obtained by removing the second anode 17 and the insulating film 19 so as to expose the first concave curved surface Cc1 again. In the present embodiment, if an HF-based solution is used as an etching solution for removing the second porous portion 18, the second anode is removed in the second porous portion removing step for removing the second porous portion 18. 17 and the insulating film 19 can also be removed. In addition, if the alkaline solution described in the first embodiment is used in the second porous portion removing step, the second anode 17 can also be removed when the second porous portion 18 is removed. After the second porous portion removing step, the insulating film 19 may be removed by wet etching or dry etching with an HF-based solution.

  According to the manufacturing method of the semiconductor lens 1 of the present embodiment described above, the current flowing through the semiconductor substrate 10 in the first anodic oxidation process by the pattern of the first anode 12 formed in the first anode forming process. Since the in-plane distribution of the density is determined, it becomes easy to control the in-plane distribution of the thickness of the first porous portion 14 formed in the first anode forming step, and as a result, the first porous portion removing step is performed. Thus, the first concave curved surface Cc1 having a desired radius of curvature can be formed, and formed in the in-plane distribution of the thickness of the semiconductor substrate 10 and the second anode forming step after the first porous portion removing step. In the second anodic oxidation step, the semiconductor substrate 10 is formed by the pattern of the portion formed directly on the first concave curved surface Cc1 of the second anode 17 (that is, the contact pattern between the second anode 17 and the semiconductor substrate 10). Current density of current flowing through As a result, the second concave curved surface Cc2 having a desired radius of curvature can be formed in the second porous portion removing step, so that the radius of curvature of each of the concave curved surfaces Cc1 and Cc2 is determined. The semiconductor lens 1 constituting a biconcave lens that is larger than the thickness of the semiconductor substrate 10 can be easily formed. The optical axis of the semiconductor lens 1 formed by the manufacturing method described above coincides with the center line of the first anode 12 and the center line of the opening 19a of the insulating film 19.

  By the way, in each said embodiment, although the p-type silicon substrate is employ | adopted as the semiconductor substrate 10, the conductivity type of the semiconductor substrate 10 may be not only p-type but n-type. Further, the material of the semiconductor substrate 10 is not limited to Si, and may be any semiconductor material that can be made porous by anodic oxidation. For example, Ge, SiC, GaAs, GaP, InP, or the like may be used. Here, as an electrolytic solution for removing oxides of constituent elements of the semiconductor substrate 10, for example, an electrolytic solution as shown in Table 1 below may be used.

  In each of the above embodiments, a single lens such as a plano-convex lens, a plano-concave 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, a single lens is used. In addition to the above, it is possible to form so-called multi-lenses in which adjacent single lenses overlap each other, so-called array lenses in which the above-mentioned single lenses are arranged in an array, or lenses in which a plurality of types of single lenses are combined. It becomes.

FIG. 6 is an explanatory diagram of the semiconductor lens manufacturing method according to the first embodiment. 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. It is explanatory drawing of a manufacturing method same as the above. 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 measurement figure of the surface shape of the semiconductor lens manufactured by the manufacturing method same as the above. It is a schematic block diagram of the infrared sensor provided with the semiconductor lens in the same as the above. The comparative example of 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 perspective view of the semiconductor lens formed by the other manufacturing method same as the above. It is explanatory drawing of another manufacturing method same as the above. 6 is an explanatory diagram of a method for manufacturing a semiconductor lens in Embodiment 2. FIG. It is a schematic perspective view of the semiconductor lens in the same as the above. It is explanatory drawing of the manufacturing method of the semiconductor lens in the same as the above. 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 a schematic block diagram of the anodizing apparatus used with the manufacturing method same as the above. It is explanatory drawing of the manufacturing method of the semiconductor lens in Embodiment 5. It is explanatory drawing of the manufacturing method of the silicon lens in Embodiment 6. It is explanatory drawing of the manufacturing method of the semiconductor lens in Embodiment 7. FIG. 10 is an explanatory diagram of a semiconductor lens manufacturing method according to Embodiment 8. 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 (1st anode)
13 Opening portion 14 Porous portion (first porous portion)
15 Insulating layer 17 Anode (second anode)
18 Porous part (second porous part)
19 Insulating film 19a Opening portion Cc Concave surface Cc1 First concave surface Cc2 Second concave surface Cv Convex surface Cv1 First convex surface Cv2 Second convex surface

Claims (8)

  A semiconductor lens manufacturing method for manufacturing a semiconductor lens by removing a part of a semiconductor substrate, wherein an anode whose pattern is designed according to a desired lens shape is in ohmic contact with the semiconductor substrate on one surface side of the semiconductor substrate And 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 each other surface side of the semiconductor substrate in the electrolytic solution. An anodizing step and a porous portion removing step for removing the porous portion, and in the anodizing step, the entire region of the porous portion formation region on the other surface of the semiconductor substrate is brought into contact with the electrolytic solution; and A method for producing a semiconductor lens, comprising using, as an electrolytic solution, a solution for removing oxides of constituent elements of a semiconductor substrate by etching.   In the anode forming step, after forming a conductive layer serving as a basis for the anode on the one surface side of the semiconductor substrate, the conductive layer is patterned so as to provide a circular opening in the conductive layer. The method of manufacturing a semiconductor lens according to claim 1, wherein the anode is formed.   A semiconductor lens manufacturing method for manufacturing a semiconductor lens by removing a part of a semiconductor substrate, and forming an insulating layer having a pattern design according to a desired lens shape on one surface side of the semiconductor substrate; Forming an anode comprising an insulating layer and a conductive layer covering an exposed portion of the one surface on the one surface side of the semiconductor substrate so as to make ohmic contact with the semiconductor substrate; and Anodizing step for forming a porous portion to be a removal site by making the other surface side of the semiconductor substrate porous by energizing between a cathode and an anode arranged opposite to each other on the other surface side; and a porous portion In the anodic oxidation process, the entire porous region formation region on the other surface of the semiconductor substrate is brought into contact with the electrolytic solution, and the semiconductor is used as the electrolytic solution. The method of manufacturing a semiconductor lens characterized by using a solution of oxide is etched off of the constituent elements of the substrate.   A semiconductor lens manufacturing method for manufacturing a semiconductor lens by removing a part of a semiconductor substrate, and forming an insulating layer having a pattern design according to a desired lens shape on one surface side of the semiconductor substrate; An energizing electrode and an anodizing electrolyte disposed opposite to the one surface side of the semiconductor substrate in the energizing electrolyte in contact with the surface of the semiconductor substrate and the surface of the insulating layer and in ohmic contact with the semiconductor substrate An anodic oxidation step of forming a porous portion serving as a removal site by making the other surface side of the semiconductor substrate porous by energizing between the cathode disposed opposite to the other surface side of the semiconductor substrate A porous portion removing step for removing the porous portion, and in the anodic oxidation step, the entire region of the porous portion formation region on the other surface of the semiconductor substrate is brought into contact with the electrolytic solution for anodization, and , As an electrolytic solution for anodization, a method of manufacturing a semiconductor lens characterized by using a solution of oxide is etched off of the constituent elements of the semiconductor substrate.   In the insulating layer forming step, an insulating film serving as a base of the insulating layer is formed on the one surface side of the semiconductor substrate, and then the insulating film is patterned in a circular shape to form the insulating layer. The manufacturing method of the semiconductor lens of Claim 3 or Claim 4 to do.   6. The method of manufacturing a semiconductor lens according to claim 3, wherein the insulating layer is made of a silicon oxide film or a silicon nitride film.   The semiconductor lens manufacturing method according to claim 1, wherein in the anodizing step, the shape of the porous portion is controlled by adjusting an electric resistance value of the electrolytic solution. Method.   The porous portion removing step is a first porous portion removing step of removing the first porous portion that is the porous portion, and after the first porous portion removing step, the one of the semiconductor substrates is removed. A second porous portion having a thickness distribution according to a desired lens shape on the surface side is formed by the anodizing step according to any one of claims 1 to 7, and then the second porous portion is formed. The method of manufacturing a semiconductor lens according to claim 1, wherein the portion is removed.

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