WO2022003896A1 - End face incidence-type semiconductor light-receiving element, and method for manufacturing end face incidence-type semiconductor light-receiving element - Google Patents

End face incidence-type semiconductor light-receiving element, and method for manufacturing end face incidence-type semiconductor light-receiving element Download PDF

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Publication number
WO2022003896A1
WO2022003896A1 PCT/JP2020/025984 JP2020025984W WO2022003896A1 WO 2022003896 A1 WO2022003896 A1 WO 2022003896A1 JP 2020025984 W JP2020025984 W JP 2020025984W WO 2022003896 A1 WO2022003896 A1 WO 2022003896A1
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incident
light receiving
light
receiving element
face
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PCT/JP2020/025984
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French (fr)
Japanese (ja)
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健 臼井
悦司 大村
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株式会社京都セミコンダクター
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Priority to PCT/JP2020/025984 priority Critical patent/WO2022003896A1/en
Publication of WO2022003896A1 publication Critical patent/WO2022003896A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors
    • H01L31/10—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors characterised by at least one potential-jump barrier or surface barrier, e.g. phototransistors

Definitions

  • the present invention relates to a technique for improving the light receiving sensitivity of an end face incident type semiconductor light receiving element used in an optical communication system.
  • an optical signal emitted from a semiconductor laser on the transmitting side is incident on a semiconductor light receiving element on the receiving side via an optical fiber cable or the like, and the semiconductor light receiving element converts the optical signal into an electric signal and outputs the signal.
  • the semiconductor laser is housed in one package together with the semiconductor light receiving element, for example, in order to monitor the emission intensity fluctuating with temperature, and a laser module is configured.
  • the light receiving module on the receiving side has a semiconductor light receiving element and an alignment mechanism capable of precisely aligning the end of the optical fiber cable with the position of the semiconductor light receiving element.
  • the semiconductor light receiving element of the laser module or the light receiving module has the incident side on the main surface side of the semiconductor substrate on which the light receiving portion is formed or the back surface side facing the main surface so that the incident light is incident on the light receiving portion (photodiode). It is fixed upright to the main board using a sub-board that maintains its orientation towards.
  • the semiconductor light receiving element that monitors the semiconductor laser needs to reduce the return light (reflected light) from the semiconductor light receiving element that induces the noise of the semiconductor laser.
  • the incident surface of a front-side incident type or back-side incident type semiconductor light receiving element has irregularities in which a plurality of high-order crystal planes having a high-order plane orientation index are exposed by anisotropic etching.
  • Semiconductor light receiving elements are known. This unevenness reflects the incident light in a direction different from the incident direction and prevents the light from returning to the semiconductor laser.
  • Patent Document 2 there is known a light emitting element in which an unevenness having a sharp tip is formed by etching the emission surface of the light emitting element. By roughening the emission surface, the light extraction efficiency from the emission surface is increased.
  • the end face incident type semiconductor light receiving element is configured to reflect or refract incident light incident parallel to the main surface from the end face side of the semiconductor substrate and guide it to the light receiving portion on the main surface side.
  • semiconductor light receiving elements are required to improve light receiving sensitivity.
  • As an effective means for improving the light receiving sensitivity it is known to reduce the reflection of the incident light and increase the light incident on the light receiving portion.
  • reflection of incident light is reduced by forming a single-layer or multilayer antireflection film on the incident surface of the incident light.
  • the incident surface of the incident light of the end surface incident type semiconductor light receiving element as in Patent Documents 3 and 4 is the end surface of the semiconductor substrate formed by being divided into individual pieces by dicing, or the inclined surface formed by etching. .. It is not easy to form each of the antireflection films on the end face which is the incident surface of the divided semiconductor substrate because the manufacturing process increases and the manufacturing cost increases. Even if an antireflection film is formed on the inclined surface formed by etching, there is a possibility that a sufficient antireflection function cannot be exhibited because the incident angle is large.
  • An object of the present invention is to provide an end face incident type semiconductor light receiving element having an antireflection structure on the incident surface of the incident light to improve the light receiving sensitivity, and a method for manufacturing the end face incident type semiconductor light receiving element.
  • the end face incident type semiconductor light receiving element according to claim 1 has a light receiving portion on the main surface side of the semiconductor substrate, and reflects or refracts incident light incident parallel to the main surface from the end face side of the semiconductor substrate.
  • the end face incident type semiconductor light receiving element leading to the light receiving portion is characterized by having a microtexture having a plurality of protrusions formed by using the semiconductor material of the semiconductor substrate on the incident surface of the incident light of the semiconductor substrate. There is.
  • the incident surface is roughened by the microtexture of the incident surface of the semiconductor substrate, and the reflection of the incident light can be reduced. Therefore, it is possible to increase the light incident on the light receiving portion of the end face incident type semiconductor light receiving element by reducing the reflection of the incident light, and it is possible to improve the light receiving sensitivity.
  • the end face incident type semiconductor light receiving element according to claim 2 has the microtexture having an average height of the protrusions equal to or higher than the wavelength of the incident light and the protrusions in the cross section of the incident surface. It is characterized in that the average width of the base end is configured to occupy 80% or more of the average pitch of the protrusions. According to the above configuration, it is possible to further reduce the reflection on the incident surface and improve the light receiving sensitivity of the end surface incident type semiconductor light receiving element.
  • the incident surface of the semiconductor light receiving element according to claim 3 is formed such that the incident surface is perpendicular to the main surface, and the incident surface is formed from the back surface side of the semiconductor substrate facing the main surface. It has a reflecting portion extending to the main surface side, and is characterized in that the reflecting portion is configured to reflect incident light toward the light receiving portion. According to the above configuration, the microtexture can reduce the return light due to reflection on the incident surface, and most of the incident light is guided to the reflecting portion and reflected toward the light receiving portion. It is possible to improve the light receiving sensitivity of.
  • the end face incident type semiconductor light receiving element according to claim 4 is formed such that the incident surface is formed so as to be connected to the back surface of the semiconductor substrate facing the main surface at an blunt angle. It is characterized in that the surface is configured to refract the incident light toward the light receiving portion.
  • the incident surface provided with the microtexture reduces the reflection that increases because the incident light is obliquely incident on the incident surface, and at the same time, refracts the incident light toward the light receiving portion.
  • the light receiving sensitivity of the light receiving element can be improved.
  • the method for manufacturing an end face incident type semiconductor light receiving element is a light receiving portion forming step of forming a light receiving portion on the main surface side of the semiconductor substrate, and is incident parallel to the main surface from the end surface side of the semiconductor substrate.
  • the microtexture of the incident surface can be formed at the same time as dicing for dividing the end face incident semiconductor light receiving element into individual pieces, the light receiving sensitivity can be improved. Further, the microtexture can be formed without increasing the manufacturing process, and it is possible to prevent an increase in manufacturing cost.
  • the light receiving sensitivity can be improved by the antireflection structure of the incident surface of the incident light.
  • FIG. 1 It is sectional drawing of the main part of the end face incident type semiconductor light receiving element which concerns on Example 1 of this invention. It is a cross-sectional model diagram of a microtexture. It is a graph which shows the reflectance by the microtexture which concerns on Example 1.
  • FIG. It is sectional drawing of the main part which shows the process of forming a light receiving part. It is sectional drawing of the main part which shows the introduction mechanism formation process which forms the introduction mechanism by reflection. It is sectional drawing of the main part which shows the microtexture forming process which concerns on Example 1.
  • FIG. It is a perspective view which shows the example of the microtexture forming process by air blast. It is a perspective view of another example of the microtexture forming process by air blast.
  • the end face incident type semiconductor light receiving element 1A that reflects incident light and causes it to be incident on a light receiving portion will be described.
  • the end face incident type semiconductor light receiving element 1A has the (100) surface of the semiconductor substrate 10 which is an n-InP substrate as the main surface 10a, and the light in the InGaAs layer 11 formed on the main surface 10a side. It includes a light receiving unit 15 (photodiode) having an absorption region 11a and a p-type diffusion region 12a in the n-InP layer 12 formed on the InGaAs layer 11. Since the semiconductor substrate 10 is transparent to infrared light having a wavelength longer than 1000 nm, infrared light having a wavelength longer than 1000 nm incident on the semiconductor substrate 10 travels in the semiconductor substrate 10.
  • the p-type diffusion region 12a is formed by doping a predetermined region of the n-InP layer 12 with, for example, Zn, and although not shown, it is formed into a circular shape or a polygonal shape including a rectangle when viewed from the main surface 10a side. ing.
  • the region of the InGaAs layer 11 in contact with the p-type diffusion region 12a corresponds to the light absorption region 11a.
  • the light receiving unit 15 includes an electrode 16 connected to the p-type diffusion region 12a.
  • the region other than the connection portion of the electrode 16 is covered with, for example, a SiO2 film as the dielectric film 13.
  • the back surface 10b of the semiconductor substrate 10 facing the main surface 10a is provided with a substrate electrode 17 connected to the semiconductor substrate 10.
  • One of the substrate electrodes 17 or 16 (for example, the substrate electrode 17) is connected in a state of being placed on a predetermined wiring of a main board (for example, not shown), and the other (for example, the electrode 16) is connected to a predetermined wiring of the main board. Connected to by wire bonding.
  • the back surface 10b of the semiconductor substrate 10 has a groove portion 18 whose cross section is formed into an isosceles triangle or trapezoidal shape by the first inclined surface 18a and the second inclined surface 18b which are connected to the back surface 10b at obtuse angles.
  • the inclined surface of the groove portion 18 near the light receiving portion 15 is referred to as the first inclined surface 18a.
  • the groove 18 is formed by known anisotropic etching using a known etching solution having anisotropy depending on the crystal plane orientation (for example, a mixed solution of hydrogen bromide and methanol having a slow etching rate on the ⁇ 111 ⁇ plane). Will be done.
  • the first inclined surface 18a is formed with a reflective portion 20 extending from the back surface 10b side toward the main surface 10a side.
  • the reflecting portion 20 is formed by laminating a dielectric film (for example, SiN film, SiO2 film, etc.) and a metal film (for example, Ag film, Au film, etc.) in order to reflect incident light.
  • a dielectric film for example, SiN film, SiO2 film, etc.
  • a metal film for example, Ag film, Au film, etc.
  • the end surface 10c on the first inclined surface 18a side is an incident surface on which light is incident on the semiconductor substrate 10.
  • the end surface 10c is formed perpendicular to the main surface 10a of the semiconductor substrate 10 and parallel to the direction in which the groove 18 extends.
  • the light emitted from the semiconductor laser or the optical fiber has an incident angle of 0 ° with respect to the end face 10c, that is, is incident perpendicular to the end face 10c. Let this emission point be O.
  • the incident light incident on the end surface 10c from the emission point O and traveling in the semiconductor substrate 10 parallel to the main surface 10a and the back surface 10b is incident at 35.3 ° whose optical axis is close to the critical angle with respect to the reflecting portion 20. Since it becomes a corner, most of the incident light is reflected toward the light receiving portion 15.
  • the critical angle is reduced and the incident light is reflected in the reflecting portion 20. It is also possible to configure it so that it is totally reflected.
  • a microtexture 19 is formed on the end surface 10c, and the incident surface is roughened.
  • the microtexture 19 has a plurality of fine protrusions 19a having a triangular cross section, which is formed by physically processing a part of the semiconductor substrate 10, that is, formed by using the semiconductor material of the semiconductor substrate 10.
  • the plurality of fine protrusions 19a continuously change the refractive index between the semiconductor substrate 10 and the air to reduce the reflection on the end face 10c.
  • FIG. 2 is a cross-sectional model diagram of the microtexture 19 in the cross section of the end face 10c.
  • b be the width of the base end of the protrusions 19a
  • p be the arrangement pitch of the protrusions 19a.
  • these average values are defined as an average height H, an average width B, and an average pitch P, respectively.
  • FIG. 3 is a simulation result showing the reflectance of the end face 10c provided with the microtexture 19.
  • the relationship between the ratio (H / ⁇ ) of the average value (average height H) of the heights h of the plurality of protrusions 19a to the wavelength ⁇ of the incident light and the reflectance is determined by the density of the plurality of protrusions 19a in the cross section of the end face 10c. Shows.
  • the density of the protrusions 19a is the ratio of the average value (average width B) of the widths b of the base ends of the plurality of protrusions 19a to the average value (average pitch P) of the arrangement pitch ps of the plurality of protrusions 19a in the cross section of the end face 10c. It is represented by (B / P).
  • the reflectance When the end face 10c is flat without protrusions 19a, the reflectance is 27.4%, but the reflectance decreases as the ratio (H / ⁇ ) of the average height H of the protrusions 19a to the wavelength ⁇ of the incident light increases. Tend. Further, the reflectance is reduced as the density (B / P) of the protrusions 19a increases.
  • the ratio (H / ⁇ ) of the average height H of the protrusions 19a to the wavelength ⁇ of the incident light is 1 or more (the average height H of the protrusions 19a is the wavelength ⁇ or more of the incident light), and the density of the protrusions 19a is high.
  • (B / P) is 0.8 (80%) or more, the reflectance can be reduced to 5% or less.
  • the density (B / P) of the protrusions 19a is 1 (100%), the reflectance is measured when the ratio (H / ⁇ ) of the average height H of the protrusions 19a to the wavelength ⁇ of the incident light is 1 or more. It can be reduced to 1% or less.
  • the end face incident type semiconductor light receiving element 1A has an average height H equal to or higher than the wavelength ⁇ of the incident light as a microtexture 19 for roughening the end face 10c, and has a degree of density. It is provided with a plurality of protrusions 19a formed so that (B / P) is 80% or more. It should be noted that the groove is formed between the plurality of protrusions 19a, and the depth of the groove, the width of the bottom of the groove, and the pitch of the groove are used in the same manner as described above. It can also be said that the texture 19 has a groove in which the ratio of the width of the groove bottom in the cross section is 20% or less.
  • FIG. 4 shows a light receiving portion 15 in which an InGaAs layer 11, an n—InP layer 12, and a dielectric film 13 are laminated on the main surface 10a side of a semiconductor substrate 10 in a wafer state, and a p-type diffusion region 12a and an electrode 16 are provided.
  • the process of forming the light receiving portion to be formed is shown.
  • Zn is doped in a predetermined region of the n-InP layer 12 and heat-treated to form a p-type diffusion region 12a, and an electrode 16 connected to the p-type diffusion region 12a from the opening of the dielectric film 13 is formed.
  • the light receiving portion 15 is shown.
  • FIG. 5 shows an introduction mechanism forming step of forming a reflection unit 20 as an introduction mechanism for guiding incident light to the light receiving unit 15 on the back surface 10b side of the semiconductor substrate 10 in the state of a wafer.
  • the surface of the semiconductor substrate 10 on which the electrode 16 is formed is covered with a protective film (not shown), and the back surface 10b is covered with an etching mask having a predetermined portion corresponding to the light receiving portion 15 to perform known anisotropic etching.
  • the groove 18 is formed and the etching mask is removed.
  • a reflective portion 20 is formed on the first inclined portion 18a and a substrate electrode 17 is formed on the back surface 10b of the semiconductor substrate 10 by a known method such as a lift-off method to remove the protective film.
  • FIG. 6 shows a microtexture forming process during dicing.
  • the semiconductor substrate 10 in the state of a wafer attached to the support film 30 is ground and divided by a dicing blade 31 to form an end face 10c.
  • the end face 10c is ground by the abrasive grain portion 31a having the abrasive grains fixed to the dicing blade 31, and the microtexture 19 is formed on the end face 10c at the same time as dicing.
  • the abrasive grains of the abrasive grain portion 30a have a particle size larger than at least the wavelength ⁇ of the incident light so that the protrusions 19a having a height equal to or higher than the wavelength ⁇ of the light received by the end face incident type semiconductor light receiving element 1A can be formed.
  • Abrasive grain is selected. Further, the processing conditions such as the rotation speed and the moving speed of the dicing blade 31 are also appropriately selected.
  • the microtexture 19 may be formed on an end face other than the end face 10c.
  • the microtexture 19 By forming the microtexture 19 at the same time as dicing in this way, the microtexture 19 can be formed without increasing the manufacturing process, and the increase in manufacturing cost can be suppressed.
  • a plurality of bar-shaped semiconductor substrates 10 divided by a dicing blade 31 are arranged so that the end faces 10c can be seen, and a projection material is projected onto the end faces 10c by an air blast device 35 to form a microtexture 19.
  • the texture forming process is shown.
  • the microtexture 19 is formed by the air blasting device 35.
  • the projection conditions such as the particle size of the projection material, an appropriate condition capable of forming a protrusion 19a having a height equal to or higher than the wavelength ⁇ of the light received by the end face incident type semiconductor light receiving element 1A is selected.
  • the microtexture 19 is formed by the air blast device 35, it is divided in the direction orthogonal to the back surface 10b and the end surface 10c by, for example, a dicing blade (not shown).
  • a dicing blade not shown.
  • the microtexture 19 cannot be formed at the same time as dicing, the microtexture 19 can be collectively formed on the end faces 10c of the plurality of bar-shaped semiconductor substrates 10, so that the increase in manufacturing cost due to the increase in the manufacturing process can be reduced. ..
  • FIG. 8 shows another example of the microtexture forming step of forming the microtexture 19 by the air blasting device 35.
  • a plurality of dicing grooves 32 having an end surface 10c are formed on the semiconductor substrate 10 in a wafer state by a dicing blade (not shown), and a projection material is projected onto the plurality of dicing grooves 32 by an air blast device 35 to form a microtexture 19 on the end surface 10c.
  • the microtexture forming step of forming is shown. When a plurality of protrusions 19a cannot be formed at the same time as dicing, the microtexture 19 is formed by the air blasting device 35.
  • the surface of the semiconductor substrate 10 is covered with the protective mask 36 covered with rubber, and the projection material is projected onto the dicing groove 32 to form the microtexture 19.
  • the projection material may be projected only onto the dicing groove 32 from the vicinity of the dicing groove 32 along the dicing groove 32.
  • the projection conditions such as the particle size of the projection material, an appropriate condition capable of forming a protrusion 19a having a height equal to or higher than the wavelength ⁇ of the light received by the end face incident type semiconductor light receiving element 1A is selected.
  • the microtexture 19 is formed on the end surface 10c by the air blast device 35, the microtexture 19 is divided in the direction orthogonal to the back surface 10b and the dicing groove 32 by, for example, dicing, and is divided along the dicing groove 32 on which the microtexture 19 is formed.
  • the microtexture 19 cannot be formed at the same time as dicing, the microtexture 19 can be collectively formed on the end face 10c by the air blasting device 35, so that the increase in manufacturing cost due to the increase in the manufacturing process can be reduced.
  • An end face incident type semiconductor light receiving element 1B having a refracting surface for refracting incident light will be described as an introduction mechanism.
  • the same parts as those in the first embodiment are designated by the same reference numerals as those in the first embodiment, and the description thereof will be omitted.
  • the end face incident type semiconductor light receiving element 1B refracts light incident on the semiconductor substrate 10 from the emission point O on the end face 10d side toward the light receiving portion 15 by the end face 10d which is an incident surface and a refracting surface. , Leads to the light receiving unit 15.
  • the end surface 10d is formed so as to intersect the back surface 10b at a predetermined angle ⁇ 2, and the end surface 10d is connected to the back surface 10b at an obtuse angle of a predetermined angle ⁇ 2.
  • the predetermined angle ⁇ 2 is, for example, 135 °, but can be set to any obtuse angle.
  • the end face 10d is roughened with the microtexture 19.
  • FIG. 10 is a simulation result showing the reflectance of the end face 10d by the microtexture 19 when the density (B / P) of the protrusions 19a is 1, as a curve L4.
  • a curve L3 showing the reflectance of the end face 10c of Example 1 is also shown.
  • the predetermined angle ⁇ 2 is 135 °
  • the incident angle of the incident light on the end surface 10d is 45 °, so that the reflectance is larger than that of the end surface 10c having an incident angle of 0 °.
  • the ratio (H / ⁇ ) of the average height H of the protrusion 19a to the wavelength ⁇ of the incident light is 1 or more (the average height H of the protrusion 19a is equal to or more than the wavelength ⁇ of the incident light), there is no protrusion 19a.
  • the reflectance, which was more than 50%, can be reduced to 4% or less.
  • the light receiving portion 15 is formed in the light receiving element forming step of FIG.
  • the dicing blade 31 is obliquely applied to the semiconductor substrate 10 to obtain an end surface.
  • the microtexture 19 is formed on the end face 10d. That is, the introduction mechanism forming step and the microtexture forming step for guiding the incident light to the light receiving unit 15 are performed at the same time.
  • the other end faces may be formed by vertically applying the dicing blade 31 to the semiconductor substrate 10.
  • the microtexture 19 can be formed without increasing the manufacturing process, and the increase in manufacturing cost can be suppressed. If the microtexture 19 cannot be sufficiently formed at the same time as dicing, the microtexture 19 can be formed on the end face 10d by the air blasting device 35 as in the first embodiment.
  • the end face incident type semiconductor light receiving elements 1A and 1B reflect or refract incident light incident parallel to the main surface 10a from the end faces 10c and 10d sides of the semiconductor substrate 10 and guide the incident light to the light receiving portion 15 on the main surface 10a side.
  • the end faces 10c and 10d, which are the incident surfaces of the incident light, are provided with a microtexture 19 having a plurality of protrusions 19a formed by using the semiconductor material of the semiconductor substrate 10.
  • the end faces 10c and 10d of the semiconductor substrate 10 are roughened by the microtexture 19 and the reflection of the incident light can be reduced, the light incident on the light receiving portions 15 of the end face incident type semiconductor light receiving elements 1A and 1B is increased.
  • the light receiving sensitivity can be improved.
  • the average height H of the protrusions 19a is equal to or higher than the wavelength ⁇ of the incident light, and the average width B of the base end of the protrusions 19a in the cross section of the incident surface is 80% or more of the average pitch P of the protrusions 19a. It is configured to occupy. As a result, the reflection on the incident surface can be further reduced, and the light receiving sensitivity of the end surface incident type semiconductor light receiving elements 1A and 1B can be improved.
  • the end surface 10c of the end surface incident type semiconductor light receiving element 1A is formed perpendicular to the main surface 10a, and the reflecting portion 20 extending from the back surface 10b side facing the main surface 10a to the main surface 10a side directs the incident light toward the light receiving portion 15. It is configured to reflect. Therefore, the microtexture 19 can reduce the return light due to the reflection on the incident surface, guide most of the incident light to the reflecting unit 20, and the reflecting unit 20 reflects the incident light toward the light receiving unit 15. , The light receiving sensitivity of the end face incident type semiconductor light receiving element 1A can be improved.
  • the end surface 10d of the end surface incident type semiconductor light receiving element 1B is formed so as to be connected to the back surface 10b facing the main surface 10a at an obtuse angle, and the end surface 10d which is an incident surface is configured to refract the incident light toward the light receiving portion 15.
  • the end face 10d provided with the microtexture 19 reduces the reflection that increases because the incident light is obliquely incident on the end face 10d, and at the same time, refracts the incident light toward the light receiving portion 15, so that the end face incident type semiconductor light receiving element
  • the light receiving sensitivity of 1B can be improved.
  • the methods for manufacturing the end face incident semiconductor light receiving elements 1A and 1B include a light receiving portion forming step of forming the light receiving portion 15 on the main surface 10a side of the semiconductor substrate 10 and parallel to the main surface 10a from the end faces 10c and 10d sides of the semiconductor substrate 10.
  • a step of forming an introduction mechanism for forming an introduction mechanism that guides the incident light incident on the It has a microtexture forming step of forming the microtexture 19. Since the microtexture 19 on the incident surface can be formed at the same time as the dicing that divides the end face incident semiconductor light receiving elements 1A and 1B into individual pieces, the reflection on the incident surface can be reduced and the light receiving sensitivity can be improved. .. Further, the microtexture 19 can be formed without increasing the number of manufacturing steps, and an increase in manufacturing cost can be prevented.
  • an example of an end face incident type semiconductor light receiving element formed on an n-InP substrate has been described, the configuration of the present invention is not limited to this, and for example, an end face incident type semiconductor light receiving element formed on a Si substrate, a GaAs substrate, or the like is described. It can also be applied to elements.
  • a person skilled in the art can carry out the embodiment in a form in which various modifications are added to the above embodiment without departing from the spirit of the present invention, and the present invention also includes such modified embodiments.
  • 1A, 1B End face incident type semiconductor light receiving element 10: Semiconductor substrate 10a: Main surface 10b: Back surface 10c, 10d: End face (incident surface) 11: InGaAs layer 11a: Light absorption region 12: n-InP layer 12a: p-type diffusion region 13: Dielectric film 15: Light receiving portion 16: Electrode 17: Substrate electrode 18: Groove portion 18a: First inclined surface 19: Microtexture 19a: Protrusion 20: Reflector 30: Support film 31: Dicing blade 32: Dicing groove 35: Air blasting device

Abstract

[Problem] To provide an end face incidence-type semiconductor light-receiving element in which an anti-reflection structure is provided on the incident surface on which incident light is incident and the light reception sensitivity is improved, and a method for manufacturing the end face incidence-type semiconductor light-receiving element. [Solution] An end surface incidence-type semiconductor light-receiving element that has a light-receiving part on the main surface side of a semiconductor substrate and in which incident light incident in a direction parallel to the main surface from the end surface side of the semiconductor substrate is reflected or refracted and guided to the light-receiving part, wherein the incidence surface of the semiconductor substrate, on which the incident light is incident, is provided with a microtexture having a plurality of protrusions formed using the semiconductor material of the semiconductor substrate.

Description

端面入射型半導体受光素子及び端面入射型半導体受光素子の製造方法Manufacturing method of end face incident type semiconductor light receiving element and end face incident type semiconductor light receiving element
　本発明は、光通信システムで用いられる端面入射型半導体受光素子の受光感度向上技術に関する。 The present invention relates to a technique for improving the light receiving sensitivity of an end face incident type semiconductor light receiving element used in an optical communication system.
　光通信では、送信側の半導体レーザから出射された光信号が、光ファイバケーブル等を介して受信側の半導体受光素子に入射し、半導体受光素子が光信号を電気信号に変換して出力する。半導体レーザは、例えば温度によって変動する発光強度をモニタするために、半導体受光素子と共に１つのパッケージに収容されてレーザモジュールが構成されている。また、受信側の受光モジュールは、半導体受光素子と、光ファイバケーブルの端部を半導体受光素子の位置に精密に合わせることができる位置合わせ機構を有する。 In optical communication, an optical signal emitted from a semiconductor laser on the transmitting side is incident on a semiconductor light receiving element on the receiving side via an optical fiber cable or the like, and the semiconductor light receiving element converts the optical signal into an electric signal and outputs the signal. The semiconductor laser is housed in one package together with the semiconductor light receiving element, for example, in order to monitor the emission intensity fluctuating with temperature, and a laser module is configured. Further, the light receiving module on the receiving side has a semiconductor light receiving element and an alignment mechanism capable of precisely aligning the end of the optical fiber cable with the position of the semiconductor light receiving element.
　レーザモジュールや受光モジュールの半導体受光素子は、入射光が受光部（フォトダイオード）に入射するように、受光部が形成された半導体基板の主面側又はこの主面に対向する裏面側を入射側に向けた姿勢に維持するサブ基板を使用して、メイン基板に垂直に立てた状態で固定されている。 The semiconductor light receiving element of the laser module or the light receiving module has the incident side on the main surface side of the semiconductor substrate on which the light receiving portion is formed or the back surface side facing the main surface so that the incident light is incident on the light receiving portion (photodiode). It is fixed upright to the main board using a sub-board that maintains its orientation towards.
　半導体レーザをモニタする半導体受光素子は、半導体レーザのノイズを誘起させる半導体受光素子からの戻り光（反射光）を低減する必要がある。例えば特許文献１のように、表面入射型又は裏面入射型の半導体受光素子の入射面に、異方性エッチングによって高次の面方位指数を有する複数の高次結晶面を露出させた凹凸を有する半導体受光素子が知られている。この凹凸が入射光を入射方向と異なる方向に反射させ、半導体レーザに光が戻らないようにしている。 The semiconductor light receiving element that monitors the semiconductor laser needs to reduce the return light (reflected light) from the semiconductor light receiving element that induces the noise of the semiconductor laser. For example, as in Patent Document 1, the incident surface of a front-side incident type or back-side incident type semiconductor light receiving element has irregularities in which a plurality of high-order crystal planes having a high-order plane orientation index are exposed by anisotropic etching. Semiconductor light receiving elements are known. This unevenness reflects the incident light in a direction different from the incident direction and prevents the light from returning to the semiconductor laser.
　また、特許文献２のように、発光素子の出射面にエッチングを施すことによって、先端部が鋭利な形状の凹凸が形成された発光素子が知られている。出射面が粗面化されることによって出射面からの光抽出効率を増大させている。 Further, as in Patent Document 2, there is known a light emitting element in which an unevenness having a sharp tip is formed by etching the emission surface of the light emitting element. By roughening the emission surface, the light extraction efficiency from the emission surface is increased.
　一方、サブ基板を使用すると製造工程が増加して製造コストが増えるので、例えば特許文献３，４のように、半導体基板をメイン基板に直接固定することが可能な端面入射型半導体受光素子が知られている。端面入射型半導体受光素子は、半導体基板の端面側から主面に平行に入射する入射光を、反射又は屈折させて主面側の受光部に導くように構成されている。 On the other hand, if a sub-board is used, the manufacturing process increases and the manufacturing cost increases. Has been done. The end face incident type semiconductor light receiving element is configured to reflect or refract incident light incident parallel to the main surface from the end face side of the semiconductor substrate and guide it to the light receiving portion on the main surface side.
特開平６－５３５３８号公報Japanese Unexamined Patent Publication No. 6-5538 特開２０１８－１６０７０５号公報Japanese Unexamined Patent Publication No. 2018-160705 特許第３１５２９０７号公報Japanese Patent No. 3152907 特開平１１－３０７８０６号公報Japanese Unexamined Patent Publication No. 11-307806
　ところで、一般的に半導体受光素子には、受光感度向上の要求がある。この受光感度向上に有効な手段として、入射光の反射を低減して受光部に入射させる光を増加させることが知られている。例えば表面入射型又は裏面入射型の半導体受光素子では、入射光の入射面に単層又は多層の反射防止膜を形成することにより、入射光の反射を低減している。 By the way, in general, semiconductor light receiving elements are required to improve light receiving sensitivity. As an effective means for improving the light receiving sensitivity, it is known to reduce the reflection of the incident light and increase the light incident on the light receiving portion. For example, in a front-facing or back-incident type semiconductor light receiving element, reflection of incident light is reduced by forming a single-layer or multilayer antireflection film on the incident surface of the incident light.
　しかし、特許文献３，４のような端面入射型半導体受光素子の入射光の入射面は、ダイシングにより個片に分割されて形成された半導体基板の端面、又はエッチングにより形成された傾斜面である。分割された半導体基板の入射面である端面に反射防止膜を夫々形成することは、製造工程が増加して製造コストが増えるので容易ではない。エッチングにより形成された傾斜面に反射防止膜を形成しても、入射角が大きいので十分な反射防止機能を発揮できない虞がある。 However, the incident surface of the incident light of the end surface incident type semiconductor light receiving element as in Patent Documents 3 and 4 is the end surface of the semiconductor substrate formed by being divided into individual pieces by dicing, or the inclined surface formed by etching. .. It is not easy to form each of the antireflection films on the end face which is the incident surface of the divided semiconductor substrate because the manufacturing process increases and the manufacturing cost increases. Even if an antireflection film is formed on the inclined surface formed by etching, there is a possibility that a sufficient antireflection function cannot be exhibited because the incident angle is large.
　また、分割された半導体基板の端面に、特許文献１，２のようにエッチングによって凹凸を夫々形成することは、製造工程が増加して製造コストが増えるので容易ではない。 Further, it is not easy to form irregularities on the end faces of the divided semiconductor substrates by etching as in Patent Documents 1 and 2, because the manufacturing process increases and the manufacturing cost increases.
　本発明の目的は、入射光の入射面に反射防止構造を備えて受光感度を向上させた端面入射型半導体受光素子、及びこの端面入射型半導体受光素子の製造方法を提供することである。 An object of the present invention is to provide an end face incident type semiconductor light receiving element having an antireflection structure on the incident surface of the incident light to improve the light receiving sensitivity, and a method for manufacturing the end face incident type semiconductor light receiving element.
　請求項１の発明の端面入射型半導体受光素子は、半導体基板の主面側に受光部を有し、前記半導体基板の端面側から前記主面に平行に入射する入射光を反射又は屈折させて前記受光部に導く端面入射型半導体受光素子において、前記半導体基板の入射光の入射面に、前記半導体基板の半導体材料を用いて形成された複数の突起を有するマイクロテクスチャを備えたことを特徴としている。 The end face incident type semiconductor light receiving element according to claim 1 has a light receiving portion on the main surface side of the semiconductor substrate, and reflects or refracts incident light incident parallel to the main surface from the end face side of the semiconductor substrate. The end face incident type semiconductor light receiving element leading to the light receiving portion is characterized by having a microtexture having a plurality of protrusions formed by using the semiconductor material of the semiconductor substrate on the incident surface of the incident light of the semiconductor substrate. There is.
　上記構成によれば、半導体基板の入射面のマイクロテクスチャによって入射面が粗面化され、入射光の反射を低減することができる。従って、入射光の反射低減によって端面入射型半導体受光素子の受光部に入射する光を増加させることができ、受光感度を向上させることができる。 According to the above configuration, the incident surface is roughened by the microtexture of the incident surface of the semiconductor substrate, and the reflection of the incident light can be reduced. Therefore, it is possible to increase the light incident on the light receiving portion of the end face incident type semiconductor light receiving element by reducing the reflection of the incident light, and it is possible to improve the light receiving sensitivity.
　請求項２の発明の端面入射型半導体受光素子は、請求項１の発明において、前記マイクロテクスチャは、前記突起の平均高さが入射光の波長以上であって、前記入射面断面における前記突起の基端の平均幅が前記突起の平均ピッチの８０％以上を占めるように構成されたことを特徴としている。
　上記構成によれば、入射面の反射を一層低減して、端面入射型半導体受光素子の受光感度を向上させることができる。 In the invention of claim 1, the end face incident type semiconductor light receiving element according to claim 2 has the microtexture having an average height of the protrusions equal to or higher than the wavelength of the incident light and the protrusions in the cross section of the incident surface. It is characterized in that the average width of the base end is configured to occupy 80% or more of the average pitch of the protrusions.
According to the above configuration, it is possible to further reduce the reflection on the incident surface and improve the light receiving sensitivity of the end surface incident type semiconductor light receiving element.
　請求項３の発明の端面入射型半導体受光素子は、請求項１又は２の発明において、前記入射面は前記主面に垂直に形成され、前記主面に対向する前記半導体基板の裏面側から前記主面側に延びる反射部を有し、前記反射部が入射光を前記受光部に向けて反射するように構成されたことを特徴としている。
　上記構成によれば、マイクロテクスチャによって入射面での反射による戻り光を低減することができ、入射光の大部分を反射部に導いて受光部に向けて反射させるので、端面入射型半導体受光素子の受光感度を向上させることができる。 In the invention of claim 1 or 2, the incident surface of the semiconductor light receiving element according to claim 3 is formed such that the incident surface is perpendicular to the main surface, and the incident surface is formed from the back surface side of the semiconductor substrate facing the main surface. It has a reflecting portion extending to the main surface side, and is characterized in that the reflecting portion is configured to reflect incident light toward the light receiving portion.
According to the above configuration, the microtexture can reduce the return light due to reflection on the incident surface, and most of the incident light is guided to the reflecting portion and reflected toward the light receiving portion. It is possible to improve the light receiving sensitivity of.
　請求項４の発明の端面入射型半導体受光素子は、請求項１又は２の発明において、前記入射面は、前記主面に対向する前記半導体基板の裏面に鈍角に連なるように形成され、前記入射面が入射光を前記受光部に向けて屈折させるように構成されたことを特徴としている。
　上記構成によれば、マイクロテクスチャを備えた入射面は、入射光が入射面に斜めに入射するために増える反射を低減すると同時に、入射光を受光部に向けて屈折させるので、端面入射型半導体受光素子の受光感度を向上させることができる。 In the invention of claim 1 or 2, the end face incident type semiconductor light receiving element according to claim 4 is formed such that the incident surface is formed so as to be connected to the back surface of the semiconductor substrate facing the main surface at an blunt angle. It is characterized in that the surface is configured to refract the incident light toward the light receiving portion.
According to the above configuration, the incident surface provided with the microtexture reduces the reflection that increases because the incident light is obliquely incident on the incident surface, and at the same time, refracts the incident light toward the light receiving portion. The light receiving sensitivity of the light receiving element can be improved.
　請求項５の発明の端面入射型半導体受光素子の製造方法は、半導体基板の主面側に受光部を形成する受光部形成工程と、前記半導体基板の端面側から前記主面に平行に入射する入射光を前記受光部に導く導入機構を形成する導入機構形成工程と、ダイシングと同時に前記半導体基板の入射光の入射面を研削して複数の突起を備えたマイクロテクスチャを形成するマイクロテクスチャ形成工程と、を有することを特徴としている。 The method for manufacturing an end face incident type semiconductor light receiving element according to claim 5 is a light receiving portion forming step of forming a light receiving portion on the main surface side of the semiconductor substrate, and is incident parallel to the main surface from the end surface side of the semiconductor substrate. An introduction mechanism forming step of forming an introduction mechanism for guiding incident light to the light receiving portion, and a microtexture forming step of grinding the incident surface of the incident light of the semiconductor substrate at the same time as dicing to form a microtexture having a plurality of protrusions. And, it is characterized by having.
　上記構成によれば、端面入射型半導体受光素子を個片に分割するダイシングと同時に入射面のマイクロテクスチャを形成することができるので、受光感度を向上させることができる。また、製造工程を増やさずにマイクロテクスチャを形成することができ、製造コストの上昇を防ぐことができる。 According to the above configuration, since the microtexture of the incident surface can be formed at the same time as dicing for dividing the end face incident semiconductor light receiving element into individual pieces, the light receiving sensitivity can be improved. Further, the microtexture can be formed without increasing the manufacturing process, and it is possible to prevent an increase in manufacturing cost.
　本発明の端面入射型半導体受光素子及び端面入射型半導体受光素子の製造方法によれば、入射光の入射面の反射防止構造によって受光感度を向上させることができる。 According to the manufacturing method of the end face incident type semiconductor light receiving element and the end face incident type semiconductor light receiving element of the present invention, the light receiving sensitivity can be improved by the antireflection structure of the incident surface of the incident light.
本発明の実施例１に係る端面入射型半導体受光素子の要部断面図である。It is sectional drawing of the main part of the end face incident type semiconductor light receiving element which concerns on Example 1 of this invention. マイクロテクスチャの断面モデル図である。It is a cross-sectional model diagram of a microtexture. 実施例１に係るマイクロテクスチャによる反射率を示すグラフである。It is a graph which shows the reflectance by the microtexture which concerns on Example 1. FIG. 受光部形成工程を示す要部断面図である。It is sectional drawing of the main part which shows the process of forming a light receiving part. 反射による導入機構を形成する導入機構形成工程を示す要部断面図である。It is sectional drawing of the main part which shows the introduction mechanism formation process which forms the introduction mechanism by reflection. 実施例１に係るマイクロテクスチャ形成工程を示す要部断面図である。It is sectional drawing of the main part which shows the microtexture forming process which concerns on Example 1. FIG. エアブラストによるマイクロテクスチャ形成工程の例を示す斜視図である。It is a perspective view which shows the example of the microtexture forming process by air blast. エアブラストによるマイクロテクスチャ形成工程の他の例の斜視図である。It is a perspective view of another example of the microtexture forming process by air blast. 本発明の実施例２に係る端面入射型半導体受光素子の要部断面図である。It is sectional drawing of the main part of the end face incident type semiconductor light receiving element which concerns on Example 2 of this invention. 実施例２に係るマイクロテクスチャによる反射率を示すグラフである。It is a graph which shows the reflectance by the microtexture which concerns on Example 2. FIG. 実施例２に係るマイクロテクスチャ形成工程を示す要部断面図である。It is sectional drawing of the main part which shows the microtexture forming process which concerns on Example 2. FIG.
　以下、本発明を実施するための形態について実施例に基づいて説明する。 Hereinafter, embodiments for carrying out the present invention will be described based on examples.
　入射光を反射させて受光部に入射させる端面入射型半導体受光素子１Ａについて説明する。
　図１に示すように、端面入射型半導体受光素子１Ａは、ｎ－ＩｎＰ基板である半導体基板１０の（１００）面を主面１０ａとして、主面１０ａ側に形成されたＩｎＧａＡｓ層１１内の光吸収領域１１ａと、ＩｎＧａＡｓ層１１上に形成されたｎ－ＩｎＰ層１２内のｐ型拡散領域１２ａを有する受光部１５（フォトダイオード）を備えている。半導体基板１０は、波長が概ね１０００ｎｍより長い赤外光に対して透明であるため、半導体基板１０に入射した１０００ｎｍより長波長の赤外光は半導体基板１０内を進行する。 An end face incident type semiconductor light receiving element 1A that reflects incident light and causes it to be incident on a light receiving portion will be described.
As shown in FIG. 1, the end face incident type semiconductor light receiving element 1A has the (100) surface of the semiconductor substrate 10 which is an n-InP substrate as the main surface 10a, and the light in the InGaAs layer 11 formed on the main surface 10a side. It includes a light receiving unit 15 (photodiode) having an absorption region 11a and a p-type diffusion region 12a in the n-InP layer 12 formed on the InGaAs layer 11. Since the semiconductor substrate 10 is transparent to infrared light having a wavelength longer than 1000 nm, infrared light having a wavelength longer than 1000 nm incident on the semiconductor substrate 10 travels in the semiconductor substrate 10.
　ｐ型拡散領域１２ａは、ｎ－ＩｎＰ層１２の所定の領域に例えばＺｎをドープして形成され、図示を省略するが、主面１０ａ側から見て円形状又は矩形を含む多角形状に形成されている。このｐ型拡散領域１２ａに接するＩｎＧａＡｓ層１１の領域が光吸収領域１１ａに相当する。 The p-type diffusion region 12a is formed by doping a predetermined region of the n-InP layer 12 with, for example, Zn, and although not shown, it is formed into a circular shape or a polygonal shape including a rectangle when viewed from the main surface 10a side. ing. The region of the InGaAs layer 11 in contact with the p-type diffusion region 12a corresponds to the light absorption region 11a.
　受光部１５は、ｐ型拡散領域１２ａに接続された電極１６を備えている。ｎ－ＩｎＰ層１２は、電極１６の接続部以外の領域が誘電体膜１３として例えばＳｉＯ２膜に覆われている。主面１０ａに対向する半導体基板１０の裏面１０ｂには、半導体基板１０に接続された基板電極１７を備えている。この基板電極１７又は電極１６のうちの一方（例えば基板電極１７）が図示外のメイン基板の所定の配線に載置された状態で接続され、他方（例えば電極１６）がメイン基板の所定の配線にワイヤボンディングによって接続される。 The light receiving unit 15 includes an electrode 16 connected to the p-type diffusion region 12a. In the n-InP layer 12, the region other than the connection portion of the electrode 16 is covered with, for example, a SiO2 film as the dielectric film 13. The back surface 10b of the semiconductor substrate 10 facing the main surface 10a is provided with a substrate electrode 17 connected to the semiconductor substrate 10. One of the substrate electrodes 17 or 16 (for example, the substrate electrode 17) is connected in a state of being placed on a predetermined wiring of a main board (for example, not shown), and the other (for example, the electrode 16) is connected to a predetermined wiring of the main board. Connected to by wire bonding.
　半導体基板１０の裏面１０ｂには、この裏面１０ｂに夫々鈍角に連なる第１傾斜面１８ａ及び第２傾斜面１８ｂにより断面が二等辺三角形状又は台形状に形成された溝部１８を有する。ここでは、溝部１８の受光部１５に近い傾斜面を第１傾斜面１８ａとしている。 The back surface 10b of the semiconductor substrate 10 has a groove portion 18 whose cross section is formed into an isosceles triangle or trapezoidal shape by the first inclined surface 18a and the second inclined surface 18b which are connected to the back surface 10b at obtuse angles. Here, the inclined surface of the groove portion 18 near the light receiving portion 15 is referred to as the first inclined surface 18a.
　第１傾斜面１８ａ及び第２傾斜面１８ｂは半導体基板１０の｛１１１｝面であり、半導体基板１０の（１００）面と｛１１１｝面は５４．７°の角度で交差する。それ故、第１傾斜面１８ａは、裏面１０ｂにθ１＝１２５．３°の鈍角に連なる。この溝部１８は、結晶面方位に依存する異方性を有する公知のエッチング液（例えば｛１１１｝面のエッチング速度が遅い臭化水素とメタノールの混合液）を用いる公知の異方性エッチングによって形成される。 The first inclined surface 18a and the second inclined surface 18b are {111} surfaces of the semiconductor substrate 10, and the (100) surface and the {111} surface of the semiconductor substrate 10 intersect at an angle of 54.7 °. Therefore, the first inclined surface 18a is connected to the back surface 10b at an obtuse angle of θ1 = 125.3 °. The groove 18 is formed by known anisotropic etching using a known etching solution having anisotropy depending on the crystal plane orientation (for example, a mixed solution of hydrogen bromide and methanol having a slow etching rate on the {111} plane). Will be done.
　第１傾斜面１８ａには、裏面１０ｂ側から主面１０ａ側に向かって延びる反射部２０が形成されている。反射部２０は、入射光を反射するために、誘電体膜（例えばＳｉＮ膜、ＳｉＯ２膜等）と金属膜（例えばＡｇ膜、Ａｕ膜等）を積層して形成されている。例えば波長が１５５０ｎｍの入射光に対して、ｎ－ＩｎＰ基板及びＳｉＮ膜の屈折率を夫々３．２及び２．０とすると、スネルの法則により臨界角は３７．３°程度になる。 The first inclined surface 18a is formed with a reflective portion 20 extending from the back surface 10b side toward the main surface 10a side. The reflecting portion 20 is formed by laminating a dielectric film (for example, SiN film, SiO2 film, etc.) and a metal film (for example, Ag film, Au film, etc.) in order to reflect incident light. For example, assuming that the refractive indexes of the n-InP substrate and the SiN film are 3.2 and 2.0, respectively, for incident light having a wavelength of 1550 nm, the critical angle becomes about 37.3 ° according to Snell's law.
　第１傾斜面１８ａ側の端面１０ｃは、光が半導体基板１０に入射する入射面である。この端面１０ｃは、半導体基板１０の主面１０ａに垂直に且つ溝部１８が延びる方向に平行に形成されている。半導体レーザや光ファイバから出射される光は、端面１０ｃに対して入射角が０°、即ち端面１０ｃに垂直に入射する。この出射点をＯとする。 The end surface 10c on the first inclined surface 18a side is an incident surface on which light is incident on the semiconductor substrate 10. The end surface 10c is formed perpendicular to the main surface 10a of the semiconductor substrate 10 and parallel to the direction in which the groove 18 extends. The light emitted from the semiconductor laser or the optical fiber has an incident angle of 0 ° with respect to the end face 10c, that is, is incident perpendicular to the end face 10c. Let this emission point be O.
　出射点Ｏから端面１０ｃに入射して主面１０ａ及び裏面１０ｂに平行に半導体基板１０内を進行する入射光は、その光軸が反射部２０に対して臨界角に近い３５．３°の入射角になるので、入射光の大部分が受光部１５に向かって反射される。屈折率が小さい誘電体膜を選択することにより、又は金属膜及び誘電体膜を備えていない第１傾斜面１８ａを反射部２０とすることにより、臨界角を小さくして入射光が反射部２０で全反射するように構成することも可能である。 The incident light incident on the end surface 10c from the emission point O and traveling in the semiconductor substrate 10 parallel to the main surface 10a and the back surface 10b is incident at 35.3 ° whose optical axis is close to the critical angle with respect to the reflecting portion 20. Since it becomes a corner, most of the incident light is reflected toward the light receiving portion 15. By selecting a dielectric film having a small refractive index, or by using the first inclined surface 18a having no metal film and a dielectric film as the reflecting portion 20, the critical angle is reduced and the incident light is reflected in the reflecting portion 20. It is also possible to configure it so that it is totally reflected.
　入射光の端面１０ｃにおける反射を低減するために、端面１０ｃにはマイクロテクスチャ１９が形成され、入射面が粗面化されている。マイクロテクスチャ１９は、半導体基板１０の一部を物理的に加工して形成された、即ち半導体基板１０の半導体材料を用いて形成された断面が三角形状の微細な複数の突起１９ａを有する。微細な複数の突起１９ａは、半導体基板１０と空気の間の屈折率を連続的に変化させて端面１０ｃにおける反射を小さくしている。 In order to reduce the reflection of the incident light on the end surface 10c, a microtexture 19 is formed on the end surface 10c, and the incident surface is roughened. The microtexture 19 has a plurality of fine protrusions 19a having a triangular cross section, which is formed by physically processing a part of the semiconductor substrate 10, that is, formed by using the semiconductor material of the semiconductor substrate 10. The plurality of fine protrusions 19a continuously change the refractive index between the semiconductor substrate 10 and the air to reduce the reflection on the end face 10c.
　図２は、端面１０ｃの断面におけるマイクロテクスチャ１９の断面モデル図である。マイクロテクスチャ１９の突起１９ａの高さをｈ、突起１９ａの基端の幅をｂ、突起１９ａの配設ピッチをｐとする。また、これらの平均値を夫々平均高さＨ、平均幅Ｂ、平均ピッチＰとする。 FIG. 2 is a cross-sectional model diagram of the microtexture 19 in the cross section of the end face 10c. Let h be the height of the protrusions 19a of the microtexture 19, b be the width of the base end of the protrusions 19a, and p be the arrangement pitch of the protrusions 19a. Further, these average values are defined as an average height H, an average width B, and an average pitch P, respectively.
　図３は、マイクロテクスチャ１９を備えた端面１０ｃの反射率を示すシミュレーション結果である。入射光の波長λに対する複数の突起１９ａの高さｈの平均値（平均高さＨ）の比率（Ｈ／λ）と反射率の関係を、端面１０ｃの断面における複数の突起１９ａの密集度別に示している。突起１９ａの密集度は、端面１０ｃの断面における複数の突起１９ａの配設ピッチｐの平均値（平均ピッチＰ）に対する複数の突起１９ａの基端の幅ｂの平均値（平均幅Ｂ）の比率（Ｂ／Ｐ）で表される。 FIG. 3 is a simulation result showing the reflectance of the end face 10c provided with the microtexture 19. The relationship between the ratio (H / λ) of the average value (average height H) of the heights h of the plurality of protrusions 19a to the wavelength λ of the incident light and the reflectance is determined by the density of the plurality of protrusions 19a in the cross section of the end face 10c. Shows. The density of the protrusions 19a is the ratio of the average value (average width B) of the widths b of the base ends of the plurality of protrusions 19a to the average value (average pitch P) of the arrangement pitch ps of the plurality of protrusions 19a in the cross section of the end face 10c. It is represented by (B / P).
　端面１０ｃに突起１９ａがない平坦なときには反射率が２７．４％であるが、入射光の波長λに対する突起１９ａの平均高さＨの比率（Ｈ／λ）が大きくなるほど反射率が低減される傾向がある。また、突起１９ａの密集度（Ｂ／Ｐ）が大きくなるほど反射率が低減されている。 When the end face 10c is flat without protrusions 19a, the reflectance is 27.4%, but the reflectance decreases as the ratio (H / λ) of the average height H of the protrusions 19a to the wavelength λ of the incident light increases. Tend. Further, the reflectance is reduced as the density (B / P) of the protrusions 19a increases.
　特に、入射光の波長λに対する突起１９ａの平均高さＨの比率（Ｈ／λ）が１以上（突起１９ａの平均高さＨが入射光の波長λ以上）であって、突起１９ａの密集度（Ｂ／Ｐ）が０．８（８０％）以上であれば、反射率を５％以下に低減することができる。また、突起１９ａの密集度（Ｂ／Ｐ）が１（１００％）の場合には、入射光の波長λに対する突起１９ａの平均高さＨの比率（Ｈ／λ）が１以上で反射率を１％以下に低減することができる。 In particular, the ratio (H / λ) of the average height H of the protrusions 19a to the wavelength λ of the incident light is 1 or more (the average height H of the protrusions 19a is the wavelength λ or more of the incident light), and the density of the protrusions 19a is high. When (B / P) is 0.8 (80%) or more, the reflectance can be reduced to 5% or less. When the density (B / P) of the protrusions 19a is 1 (100%), the reflectance is measured when the ratio (H / λ) of the average height H of the protrusions 19a to the wavelength λ of the incident light is 1 or more. It can be reduced to 1% or less.
　このように反射率を低減するために、端面入射型半導体受光素子１Ａは、端面１０ｃを粗面化するマイクロテクスチャ１９として、入射光の波長λ以上の平均高さＨを有し、且つ密集度（Ｂ／Ｐ）が８０％以上となるように形成された複数の突起１９ａを備えている。尚、複数の突起１９ａの間を溝とし、溝の深さと溝底の幅と溝のピッチを用いて上記と同様にして、入射光の波長λ以上の平均深さの溝であって、マイクロテクスチャ１９の断面における溝底の幅の割合が２０％以下の溝を備えていると言うこともできる。 In order to reduce the reflectance in this way, the end face incident type semiconductor light receiving element 1A has an average height H equal to or higher than the wavelength λ of the incident light as a microtexture 19 for roughening the end face 10c, and has a degree of density. It is provided with a plurality of protrusions 19a formed so that (B / P) is 80% or more. It should be noted that the groove is formed between the plurality of protrusions 19a, and the depth of the groove, the width of the bottom of the groove, and the pitch of the groove are used in the same manner as described above. It can also be said that the texture 19 has a groove in which the ratio of the width of the groove bottom in the cross section is 20% or less.
　次に、端面入射型半導体受光素子１Ａの製造方法について説明する。
　図４は、ウェハの状態の半導体基板１０の主面１０ａ側にＩｎＧａＡｓ層１１とｎ－ＩｎＰ層１２と誘電体膜１３が積層され、ｐ型拡散領域１２ａと電極１６を備えた受光部１５を形成する受光部形成工程を示している。例えば、ｎ－ＩｎＰ層１２の所定の領域にＺｎをドープし、熱処理をしてｐ型拡散領域１２ａを形成し、誘電体膜１３の開口部からｐ型拡散領域１２ａに接続する電極１６を形成して受光部１５を形成する。 Next, a method of manufacturing the end face incident type semiconductor light receiving element 1A will be described.
FIG. 4 shows a light receiving portion 15 in which an InGaAs layer 11, an n—InP layer 12, and a dielectric film 13 are laminated on the main surface 10a side of a semiconductor substrate 10 in a wafer state, and a p-type diffusion region 12a and an electrode 16 are provided. The process of forming the light receiving portion to be formed is shown. For example, Zn is doped in a predetermined region of the n-InP layer 12 and heat-treated to form a p-type diffusion region 12a, and an electrode 16 connected to the p-type diffusion region 12a from the opening of the dielectric film 13 is formed. To form the light receiving portion 15.
　図５は、ウェハの状態の半導体基板１０の裏面１０ｂ側に、受光部１５に入射光を導く導入機構として反射部２０を形成する導入機構形成工程を示している。例えば、電極１６が形成された半導体基板１０の表面を図示外の保護膜で覆い、受光部１５に対応する所定の部位を開口したエッチングマスクによって裏面１０ｂを覆って公知の異方性エッチングを施し、溝部１８を形成してエッチングマスクを除去する。そして、例えばリフトオフ法などの公知の方法によって、第１傾斜部１８ａに反射部２０を形成し、半導体基板１０の裏面１０ｂに基板電極１７を形成して保護膜を除去する。 FIG. 5 shows an introduction mechanism forming step of forming a reflection unit 20 as an introduction mechanism for guiding incident light to the light receiving unit 15 on the back surface 10b side of the semiconductor substrate 10 in the state of a wafer. For example, the surface of the semiconductor substrate 10 on which the electrode 16 is formed is covered with a protective film (not shown), and the back surface 10b is covered with an etching mask having a predetermined portion corresponding to the light receiving portion 15 to perform known anisotropic etching. , The groove 18 is formed and the etching mask is removed. Then, a reflective portion 20 is formed on the first inclined portion 18a and a substrate electrode 17 is formed on the back surface 10b of the semiconductor substrate 10 by a known method such as a lift-off method to remove the protective film.
　図６は、ダイシング時におけるマイクロテクスチャ形成工程を示している。例えば、支持フィルム３０に貼り付けたウェハの状態の半導体基板１０をダイシングブレード３１によって研削して分割し、端面１０ｃを形成する。このとき、ダイシングブレード３１に砥粒を固着させた砥粒部３１ａによって端面１０ｃを研削し、ダイシングと同時に端面１０ｃにマイクロテクスチャ１９を形成する。 FIG. 6 shows a microtexture forming process during dicing. For example, the semiconductor substrate 10 in the state of a wafer attached to the support film 30 is ground and divided by a dicing blade 31 to form an end face 10c. At this time, the end face 10c is ground by the abrasive grain portion 31a having the abrasive grains fixed to the dicing blade 31, and the microtexture 19 is formed on the end face 10c at the same time as dicing.
　この砥粒部３０ａの砥粒は、端面入射型半導体受光素子１Ａが受光する光の波長λ以上の高さの突起１９ａを形成可能なように、少なくともこの入射光の波長λよりも大きい粒径の砥粒が選択される。また、ダイシングブレード３１の回転速度や移動速度などの加工条件についても適切に選択される。尚、端面１０ｃ以外の端面にもマイクロテクスチャ１９が形成されてもよい。 The abrasive grains of the abrasive grain portion 30a have a particle size larger than at least the wavelength λ of the incident light so that the protrusions 19a having a height equal to or higher than the wavelength λ of the light received by the end face incident type semiconductor light receiving element 1A can be formed. Abrasive grain is selected. Further, the processing conditions such as the rotation speed and the moving speed of the dicing blade 31 are also appropriately selected. The microtexture 19 may be formed on an end face other than the end face 10c.
　このように、ダイシングと同時にマイクロテクスチャ１９を形成することにより、製造工程を増やすことなくマイクロテクスチャ１９を形成することができ、製造コストの増加を抑えることができる。 By forming the microtexture 19 at the same time as dicing in this way, the microtexture 19 can be formed without increasing the manufacturing process, and the increase in manufacturing cost can be suppressed.
　図７は、ダイシングブレード３１により分割した複数のバー状の半導体基板１０を、端面１０ｃが見えるように配列し、エアブラスト装置３５によって投射材を端面１０ｃに投射してマイクロテクスチャ１９を形成するマイクロテクスチャ形成工程を示している。ダイシングと同時に複数の突起１９ａを形成できない場合に、このエアブラスト装置３５によってマイクロテクスチャ１９を形成する。投射材の粒径等の投射条件は、端面入射型半導体受光素子１Ａが受光する光の波長λ以上の高さの突起１９ａを形成可能な適切な条件が選択される。 In FIG. 7, a plurality of bar-shaped semiconductor substrates 10 divided by a dicing blade 31 are arranged so that the end faces 10c can be seen, and a projection material is projected onto the end faces 10c by an air blast device 35 to form a microtexture 19. The texture forming process is shown. When a plurality of protrusions 19a cannot be formed at the same time as dicing, the microtexture 19 is formed by the air blasting device 35. As the projection conditions such as the particle size of the projection material, an appropriate condition capable of forming a protrusion 19a having a height equal to or higher than the wavelength λ of the light received by the end face incident type semiconductor light receiving element 1A is selected.
　エアブラスト装置３５によってマイクロテクスチャ１９を形成した後は、裏面１０ｂ及び端面１０ｃに直交する方向に例えば図示外のダイシングブレードによって分割する。ダイシングと同時にマイクロテクスチャ１９を形成できない場合に、複数のバー状の半導体基板１０の端面１０ｃに一括してマイクロテクスチャ１９を形成できるので、製造工程の増加による製造コストの増加を小さくすることができる。 After the microtexture 19 is formed by the air blast device 35, it is divided in the direction orthogonal to the back surface 10b and the end surface 10c by, for example, a dicing blade (not shown). When the microtexture 19 cannot be formed at the same time as dicing, the microtexture 19 can be collectively formed on the end faces 10c of the plurality of bar-shaped semiconductor substrates 10, so that the increase in manufacturing cost due to the increase in the manufacturing process can be reduced. ..
　図８は、エアブラスト装置３５によってマイクロテクスチャ１９を形成するマイクロテクスチャ形成工程の他の例を示している。図示外のダイシングブレードによってウェハの状態の半導体基板１０に端面１０ｃを有する複数のダイシング溝３２を形成し、エアブラスト装置３５によって投射材を複数のダイシング溝３２に投射して端面１０ｃにマイクロテクスチャ１９を形成するマイクロテクスチャ形成工程を示している。ダイシングと同時に複数の突起１９ａを形成できない場合に、このエアブラスト装置３５によってマイクロテクスチャ１９を形成する。 FIG. 8 shows another example of the microtexture forming step of forming the microtexture 19 by the air blasting device 35. A plurality of dicing grooves 32 having an end surface 10c are formed on the semiconductor substrate 10 in a wafer state by a dicing blade (not shown), and a projection material is projected onto the plurality of dicing grooves 32 by an air blast device 35 to form a microtexture 19 on the end surface 10c. The microtexture forming step of forming is shown. When a plurality of protrusions 19a cannot be formed at the same time as dicing, the microtexture 19 is formed by the air blasting device 35.
　例えば、ダイシング溝３２以外の領域を保護するために、ゴムで覆われた保護マスク３６によって半導体基板１０の表面を覆い、投射材をダイシング溝３２に投射してマイクロテクスチャ１９を形成する。ダイシング溝３２の近傍からダイシング溝３２に沿って投射材をダイシング溝３２にのみ投射するようにしてもよい。投射材の粒径等の投射条件は、端面入射型半導体受光素子１Ａが受光する光の波長λ以上の高さの突起１９ａを形成可能な適切な条件が選択される。 For example, in order to protect the area other than the dicing groove 32, the surface of the semiconductor substrate 10 is covered with the protective mask 36 covered with rubber, and the projection material is projected onto the dicing groove 32 to form the microtexture 19. The projection material may be projected only onto the dicing groove 32 from the vicinity of the dicing groove 32 along the dicing groove 32. As the projection conditions such as the particle size of the projection material, an appropriate condition capable of forming a protrusion 19a having a height equal to or higher than the wavelength λ of the light received by the end face incident type semiconductor light receiving element 1A is selected.
　エアブラスト装置３５によって端面１０ｃにマイクロテクスチャ１９を形成した後は、裏面１０ｂ及びダイシング溝３２に直交する方向に例えばダイシングによって分割し、マイクロテクスチャ１９を形成したダイシング溝３２に沿って分割する。ダイシングと同時にマイクロテクスチャ１９を形成できない場合に、エアブラスト装置３５によって端面１０ｃに一括してマイクロテクスチャ１９を形成できるので、製造工程の増加による製造コストの増加を小さくすることができる。 After the microtexture 19 is formed on the end surface 10c by the air blast device 35, the microtexture 19 is divided in the direction orthogonal to the back surface 10b and the dicing groove 32 by, for example, dicing, and is divided along the dicing groove 32 on which the microtexture 19 is formed. When the microtexture 19 cannot be formed at the same time as dicing, the microtexture 19 can be collectively formed on the end face 10c by the air blasting device 35, so that the increase in manufacturing cost due to the increase in the manufacturing process can be reduced.
　導入機構として入射光を屈折させる屈折面を有する端面入射型半導体受光素子１Ｂについて説明する。実施例１と同様の部分には、実施例１と同じ符号を付して説明を省略する。　図９に示すように、端面入射型半導体受光素子１Ｂは、端面１０ｄ側の出射点Ｏから半導体基板１０に入射する光を入射面且つ屈折面である端面１０ｄによって受光部１５に向けて屈折させ、受光部１５に導く。 An end face incident type semiconductor light receiving element 1B having a refracting surface for refracting incident light will be described as an introduction mechanism. The same parts as those in the first embodiment are designated by the same reference numerals as those in the first embodiment, and the description thereof will be omitted. As shown in FIG. 9, the end face incident type semiconductor light receiving element 1B refracts light incident on the semiconductor substrate 10 from the emission point O on the end face 10d side toward the light receiving portion 15 by the end face 10d which is an incident surface and a refracting surface. , Leads to the light receiving unit 15.
　入射光を受光部１５に向けて屈折させるために、端面１０ｄは裏面１０ｂに所定の角度θ２で交差するように形成され、端面１０ｄが裏面１０ｂに所定の角度θ２の鈍角に連なっている。所定の角度θ２は、例えば１３５°であるが、任意の鈍角に設定できる。入射光の端面１０ｄにおける反射を低減するために、端面１０ｄはマイクロテクスチャ１９を備えて粗面化されている。 In order to refract the incident light toward the light receiving portion 15, the end surface 10d is formed so as to intersect the back surface 10b at a predetermined angle θ2, and the end surface 10d is connected to the back surface 10b at an obtuse angle of a predetermined angle θ2. The predetermined angle θ2 is, for example, 135 °, but can be set to any obtuse angle. In order to reduce the reflection of the incident light on the end face 10d, the end face 10d is roughened with the microtexture 19.
　図１０は、突起１９ａの密集度（Ｂ／Ｐ）が１の場合のマイクロテクスチャ１９による端面１０ｄの反射率を曲線Ｌ４で示したシミュレーション結果である。比較対象として実施例１の端面１０ｃの反射率を示す曲線Ｌ３を併記している。所定の角度θ２が１３５°の場合に、端面１０ｄにおける入射光の入射角は４５°になるので、入射角が０°の端面１０ｃと比べると反射率は大きくなっている。 FIG. 10 is a simulation result showing the reflectance of the end face 10d by the microtexture 19 when the density (B / P) of the protrusions 19a is 1, as a curve L4. As a comparison target, a curve L3 showing the reflectance of the end face 10c of Example 1 is also shown. When the predetermined angle θ2 is 135 °, the incident angle of the incident light on the end surface 10d is 45 °, so that the reflectance is larger than that of the end surface 10c having an incident angle of 0 °.
　しかし、入射光の波長λに対する突起１９ａの平均高さＨの比率（Ｈ／λ）が１以上（突起１９ａの平均高さＨが入射光の波長λ以上）であれば、突起１９ａがない場合に５０％を超えていた反射率を４％以下に低減することができる。 However, if the ratio (H / λ) of the average height H of the protrusion 19a to the wavelength λ of the incident light is 1 or more (the average height H of the protrusion 19a is equal to or more than the wavelength λ of the incident light), there is no protrusion 19a. The reflectance, which was more than 50%, can be reduced to 4% or less.
　次に、端面入射型半導体受光素子１Ｂの製造方法について説明する。
　実施例１と同様に、図４の受光素子形成工程において受光部１５を形成する。そして、図１１に示すように、裏面１０ｂに基板電極１７を形成したウェハの状態の半導体基板１０をダイシングによって分割する際に、半導体基板１０に対してダイシングブレード３１を斜めに当てることによって、端面１０ｄを形成すると同時に、端面１０ｄにマイクロテクスチャ１９を形成する。即ち、受光部１５に入射光を導く導入機構形成工程とマイクロテクスチャ形成工程を同時に行っている。これ以外の端面は、ダイシングブレード３１を半導体基板１０に垂直に当てて形成してもよい。 Next, a method of manufacturing the end face incident type semiconductor light receiving element 1B will be described.
Similar to the first embodiment, the light receiving portion 15 is formed in the light receiving element forming step of FIG. Then, as shown in FIG. 11, when the semiconductor substrate 10 in the state of a wafer in which the substrate electrode 17 is formed on the back surface 10b is divided by dicing, the dicing blade 31 is obliquely applied to the semiconductor substrate 10 to obtain an end surface. At the same time as forming the 10d, the microtexture 19 is formed on the end face 10d. That is, the introduction mechanism forming step and the microtexture forming step for guiding the incident light to the light receiving unit 15 are performed at the same time. The other end faces may be formed by vertically applying the dicing blade 31 to the semiconductor substrate 10.
　このように、ダイシングと同時に入射光を屈折させる端面１０ｄとマイクロテクスチャ１９を形成することにより、製造工程を増やすことなくマイクロテクスチャ１９を形成することができ、製造コストの増加を抑えることができる。ダイシングと同時にマイクロテクスチャ１９を十分に形成できない場合には、実施例１と同様にエアブラスト装置３５によって端面１０ｄにマイクロテクスチャ１９を形成することもできる。 In this way, by forming the microtexture 19 with the end face 10d that refracts the incident light at the same time as dicing, the microtexture 19 can be formed without increasing the manufacturing process, and the increase in manufacturing cost can be suppressed. If the microtexture 19 cannot be sufficiently formed at the same time as dicing, the microtexture 19 can be formed on the end face 10d by the air blasting device 35 as in the first embodiment.
　上記光半導体アレイ１Ａ，１Ｂの作用、効果について説明する。
　端面入射型半導体受光素子１Ａ，１Ｂは、半導体基板１０の端面１０ｃ，１０ｄ側から主面１０ａに平行に入射する入射光を、反射又は屈折させて主面１０ａ側の受光部１５に導く。この入射光の入射面である端面１０ｃ，１０ｄに、半導体基板１０の半導体材料を用いて形成された複数の突起１９ａを有するマイクロテクスチャ１９を備えている。半導体基板１０の端面１０ｃ，１０ｄがマイクロテクスチャ１９によって粗面化され、入射光の反射を低減することができるので、端面入射型半導体受光素子１Ａ，１Ｂの受光部１５に入射する光を増加させて受光感度を向上させることができる。 The actions and effects of the optical semiconductor arrays 1A and 1B will be described.
The end face incident type semiconductor light receiving elements 1A and 1B reflect or refract incident light incident parallel to the main surface 10a from the end faces 10c and 10d sides of the semiconductor substrate 10 and guide the incident light to the light receiving portion 15 on the main surface 10a side. The end faces 10c and 10d, which are the incident surfaces of the incident light, are provided with a microtexture 19 having a plurality of protrusions 19a formed by using the semiconductor material of the semiconductor substrate 10. Since the end faces 10c and 10d of the semiconductor substrate 10 are roughened by the microtexture 19 and the reflection of the incident light can be reduced, the light incident on the light receiving portions 15 of the end face incident type semiconductor light receiving elements 1A and 1B is increased. The light receiving sensitivity can be improved.
　また、マイクロテクスチャ１９は、突起１９ａの平均高さＨが入射光の波長λ以上であって、入射面断面における突起１９ａの基端の平均幅Ｂが突起１９ａの平均ピッチＰの８０％以上を占めるように構成されている。これにより、入射面の反射を一層低減して、端面入射型半導体受光素子１Ａ，１Ｂの受光感度を向上させることができる。 Further, in the microtexture 19, the average height H of the protrusions 19a is equal to or higher than the wavelength λ of the incident light, and the average width B of the base end of the protrusions 19a in the cross section of the incident surface is 80% or more of the average pitch P of the protrusions 19a. It is configured to occupy. As a result, the reflection on the incident surface can be further reduced, and the light receiving sensitivity of the end surface incident type semiconductor light receiving elements 1A and 1B can be improved.
　端面入射型半導体受光素子１Ａの端面１０ｃは主面１０ａに垂直に形成され、主面１０ａに対向する裏面１０ｂ側から主面１０ａ側に延びる反射部２０が、入射光を受光部１５に向けて反射するように構成されている。従って、マイクロテクスチャ１９によって入射面での反射による戻り光を低減することができ、入射光の大部分を反射部２０に導き、この反射部２０が受光部１５に向けて入射光を反射させるので、端面入射型半導体受光素子１Ａの受光感度を向上させることができる。 The end surface 10c of the end surface incident type semiconductor light receiving element 1A is formed perpendicular to the main surface 10a, and the reflecting portion 20 extending from the back surface 10b side facing the main surface 10a to the main surface 10a side directs the incident light toward the light receiving portion 15. It is configured to reflect. Therefore, the microtexture 19 can reduce the return light due to the reflection on the incident surface, guide most of the incident light to the reflecting unit 20, and the reflecting unit 20 reflects the incident light toward the light receiving unit 15. , The light receiving sensitivity of the end face incident type semiconductor light receiving element 1A can be improved.
　端面入射型半導体受光素子１Ｂの端面１０ｄは、主面１０ａに対向する裏面１０ｂに鈍角に連なるように形成され、入射面である端面１０ｄが入射光を受光部１５に向けて屈折させるように構成されている。従って、マイクロテクスチャ１９を備えた端面１０ｄは、入射光が端面１０ｄに斜めに入射するために増える反射を低減すると同時に、入射光を受光部１５に向けて屈折させるので、端面入射型半導体受光素子１Ｂの受光感度を向上させることができる。 The end surface 10d of the end surface incident type semiconductor light receiving element 1B is formed so as to be connected to the back surface 10b facing the main surface 10a at an obtuse angle, and the end surface 10d which is an incident surface is configured to refract the incident light toward the light receiving portion 15. Has been done. Therefore, the end face 10d provided with the microtexture 19 reduces the reflection that increases because the incident light is obliquely incident on the end face 10d, and at the same time, refracts the incident light toward the light receiving portion 15, so that the end face incident type semiconductor light receiving element The light receiving sensitivity of 1B can be improved.
　端面入射型半導体受光素子１Ａ，１Ｂの製造方法は、半導体基板１０の主面１０ａ側に受光部１５を形成する受光部形成工程と、半導体基板１０の端面１０ｃ，１０ｄ側から主面１０ａに平行に入射する入射光を受光部１５に導く導入機構を形成する導入機構形成工程と、ダイシングと同時に半導体基板１０の入射光の入射面である端面１０ｃ，１０ｄを研削して複数の突起１９ａを備えたマイクロテクスチャ１９を形成するマイクロテクスチャ形成工程を有する。端面入射型半導体受光素子１Ａ，１Ｂを個片に分割するダイシングと同時に、入射面のマイクロテクスチャ１９を形成することができるので、入射面での反射を低減して受光感度を向上させることができる。また、製造工程を増やさずにマイクロテクスチャ１９を形成することができ、製造コストの上昇を防ぐことができる。 The methods for manufacturing the end face incident semiconductor light receiving elements 1A and 1B include a light receiving portion forming step of forming the light receiving portion 15 on the main surface 10a side of the semiconductor substrate 10 and parallel to the main surface 10a from the end faces 10c and 10d sides of the semiconductor substrate 10. A step of forming an introduction mechanism for forming an introduction mechanism that guides the incident light incident on the It has a microtexture forming step of forming the microtexture 19. Since the microtexture 19 on the incident surface can be formed at the same time as the dicing that divides the end face incident semiconductor light receiving elements 1A and 1B into individual pieces, the reflection on the incident surface can be reduced and the light receiving sensitivity can be improved. .. Further, the microtexture 19 can be formed without increasing the number of manufacturing steps, and an increase in manufacturing cost can be prevented.
　ｎ－ＩｎＰ基板に形成された端面入射型半導体受光素子の例を説明したが、本発明の構成はこれに限られるものではなく、例えばＳｉ基板やＧａＡｓ基板等に形成された端面入射型半導体受光素子にも適用することができる。その他、当業者であれば、本発明の趣旨を逸脱することなく、上記実施形態に種々の変更を付加した形態で実施可能であり、本発明はその種の変更形態も包含するものである。 Although an example of an end face incident type semiconductor light receiving element formed on an n-InP substrate has been described, the configuration of the present invention is not limited to this, and for example, an end face incident type semiconductor light receiving element formed on a Si substrate, a GaAs substrate, or the like is described. It can also be applied to elements. In addition, a person skilled in the art can carry out the embodiment in a form in which various modifications are added to the above embodiment without departing from the spirit of the present invention, and the present invention also includes such modified embodiments.
１Ａ，１Ｂ　：端面入射型半導体受光素子
１０　　：半導体基板
１０ａ　：主面
１０ｂ　：裏面
１０ｃ，１０ｄ　：端面（入射面）
１１　　：ＩｎＧａＡｓ層
１１ａ　：光吸収領域
１２　　：ｎ－ＩｎＰ層
１２ａ　：ｐ型拡散領域
１３　　：誘電体膜
１５　　：受光部
１６　　：電極
１７　　：基板電極
１８　　：溝部
１８ａ　：第１傾斜面
１９　　：マイクロテクスチャ
１９ａ　：突起
２０　　：反射部
３０　　：支持フィルム
３１　　：ダイシングブレード
３２　　：ダイシング溝
３５　　：エアブラスト装置 1A, 1B: End face incident type semiconductor light receiving element 10: Semiconductor substrate 10a: Main surface 10b: Back surface 10c, 10d: End face (incident surface)
11: InGaAs layer 11a: Light absorption region 12: n-InP layer 12a: p-type diffusion region 13: Dielectric film 15: Light receiving portion 16: Electrode 17: Substrate electrode 18: Groove portion 18a: First inclined surface 19: Microtexture 19a: Protrusion 20: Reflector 30: Support film 31: Dicing blade 32: Dicing groove 35: Air blasting device

Claims (5)

  1. 　半導体基板の主面側に受光部を有し、前記半導体基板の端面側から前記主面に平行に入射する入射光を反射又は屈折させて前記受光部に導く端面入射型半導体受光素子において、
    　前記半導体基板の入射光の入射面に、前記半導体基板の半導体材料を用いて形成された複数の突起を有するマイクロテクスチャを備えたことを特徴とする端面入射型半導体受光素子。     In an end face incident type semiconductor light receiving element having a light receiving portion on the main surface side of the semiconductor substrate and reflecting or refracting incident light incident parallel to the main surface from the end face side of the semiconductor substrate to guide the light receiving portion to the light receiving portion.
    An end face incident type semiconductor light receiving element, characterized in that the incident surface of incident light of the semiconductor substrate is provided with a microtexture having a plurality of protrusions formed by using the semiconductor material of the semiconductor substrate.
  2. 　前記マイクロテクスチャは、前記突起の平均高さが入射光の波長以上であって、前記入射面断面における前記突起の基端の平均幅が前記突起の平均ピッチの８０％以上を占めるように構成されたことを特徴とする請求項１に記載の端面入射型半導体受光素子。 The microtexture is configured such that the average height of the protrusions is equal to or greater than the wavelength of the incident light, and the average width of the base end of the protrusions in the cross section of the incident surface occupies 80% or more of the average pitch of the protrusions. The end face incident type semiconductor light receiving element according to claim 1.
  3. 　前記入射面は前記主面に垂直に形成され、前記主面に対向する前記半導体基板の裏面側から前記主面側に延びる反射部を有し、前記反射部が入射光を前記受光部に向けて反射するように構成されたことを特徴とする請求項１又は２に記載の端面入射型半導体受光素子。 The incident surface is formed perpendicular to the main surface, has a reflecting portion extending from the back surface side of the semiconductor substrate facing the main surface to the main surface side, and the reflecting portion directs incident light toward the light receiving portion. The end face incident type semiconductor light receiving element according to claim 1 or 2, wherein the semiconductor light receiving element is configured to reflect light.
  4. 　前記入射面は、前記主面に対向する前記半導体基板の裏面に鈍角に連なるように形成され、前記入射面が入射光を前記受光部に向けて屈折させるように構成されたことを特徴とする請求項１又は２に記載の端面入射型半導体受光素子。 The incident surface is formed so as to be connected to the back surface of the semiconductor substrate facing the main surface at an obtuse angle, and the incident surface is configured to refract the incident light toward the light receiving portion. The end face entrance type semiconductor light receiving element according to claim 1 or 2.
  5. 　半導体基板の主面側に受光部を形成する受光部形成工程と、
    　前記半導体基板の端面側から前記主面に平行に入射する入射光を前記受光部に導く導入機構を形成する導入機構形成工程と、
    　ダイシングと同時に前記半導体基板の入射光の入射面を研削して複数の突起を備えたマイクロテクスチャを形成するマイクロテクスチャ形成工程と、
    　を有することを特徴とする端面入射型半導体受光素子の製造方法。     A light receiving portion forming step of forming a light receiving portion on the main surface side of the semiconductor substrate, and a light receiving portion forming step.
    An introduction mechanism forming step of forming an introduction mechanism for guiding incident light incident parallel to the main surface from the end surface side of the semiconductor substrate to the light receiving portion.
    A microtexture forming step of grinding the incident surface of the incident light of the semiconductor substrate at the same time as dicing to form a microtexture having a plurality of protrusions.
    A method for manufacturing an end face incident type semiconductor light receiving element.
PCT/JP2020/025984 2020-07-02 2020-07-02 End face incidence-type semiconductor light-receiving element, and method for manufacturing end face incidence-type semiconductor light-receiving element WO2022003896A1 (en)

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