WO2022079912A1 - Semiconductor light-receiving element - Google Patents

Semiconductor light-receiving element Download PDF

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Publication number
WO2022079912A1
WO2022079912A1 PCT/JP2020/039130 JP2020039130W WO2022079912A1 WO 2022079912 A1 WO2022079912 A1 WO 2022079912A1 JP 2020039130 W JP2020039130 W JP 2020039130W WO 2022079912 A1 WO2022079912 A1 WO 2022079912A1
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Prior art keywords
light
light receiving
semiconductor
reflected
incident
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PCT/JP2020/039130
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French (fr)
Japanese (ja)
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尚友 磯村
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 JP2021502631A priority Critical patent/JP6856295B1/en
Priority to PCT/JP2020/039130 priority patent/WO2022079912A1/en
Publication of WO2022079912A1 publication Critical patent/WO2022079912A1/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
    • H01L31/02—Details
    • H01L31/0232—Optical elements or arrangements associated with the device
    • 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 potential barriers, e.g. phototransistors

Definitions

  • the present invention relates to a semiconductor light receiving element used for optical communication, and particularly to a semiconductor light receiving element capable of high-speed operation by reducing the element capacitance and shortening the drift time.
  • the surface-incident type semiconductor light receiving element is provided with a light receiving portion having a light absorption layer on the first surface side of the semiconductor substrate, and is formed from an optical fiber cable arranged on the first surface side or the second surface side facing the first surface.
  • the emitted light is incident on the light receiving portion in the thickness direction of the light absorption layer.
  • it is required to reduce the element capacitance and the element resistance and shorten the drift time of the charge (carrier) generated in the light absorption layer of the light receiving portion.
  • the required diameter of the light receiving portion is about 10 ⁇ m.
  • the amount of light received decreases, so that the light receiving sensitivity decreases.
  • the thickness of the light absorption layer of the light receiving part is required to be 1 ⁇ m or less. Since the light absorption layer is thin, the quantum efficiency of converting light into carriers is lowered, and the light receiving sensitivity is lowered. Moreover, if the light absorption layer is made thin, the element capacity becomes large.
  • Patent Document 1 a semiconductor light receiving device having a condenser lens integrally formed on a semiconductor substrate in order to reduce a decrease in light receiving sensitivity when the area of the light receiving portion is reduced for high speed.
  • the element is known. Since the light that cannot reach the light receiving portion due to the spread of light is also collected by the condenser lens and incident on the light receiving portion, the decrease in the light receiving sensitivity is reduced even in the light receiving portion having a small area.
  • the light absorbing layer is condensed by a condensing lens and incident on the light receiving portion to form the light absorbing layer.
  • a semiconductor light receiving element that reflects the transmitted light, transmits the light absorbing layer again, and reflects the light toward the light receiving portion by a metal reflecting film formed on the central surface of the condenser lens. Since the light passes through the light absorption layer a plurality of times to improve the quantum efficiency, the decrease in the light receiving sensitivity is reduced.
  • Patent Document 1 since it is not possible to prevent a decrease in the light receiving sensitivity when the light absorption layer is thinned, it is difficult to reduce the decrease in the light receiving sensitivity and to increase the speed at the same time. Further, as in Patent Document 2, the metal reflective film formed on the central surface of the condensing lens blocks the optical axis having high light intensity and the light in the vicinity thereof when the incident light is incident on the entire condensing lens. Therefore, the improvement of the light receiving sensitivity is limited, and there is a possibility that the light receiving sensitivity is rather lowered.
  • An object of the present invention is to provide a semiconductor light receiving element capable of reducing a decrease in light receiving sensitivity due to high speed.
  • the semiconductor light-receiving element of the invention of claim 1 has a light-receiving portion formed by laminating a first semiconductor layer, a light absorption layer, and a second semiconductor layer on the first surface of the semiconductor substrate in this order, and has a light-receiving portion of the semiconductor substrate.
  • a semiconductor light receiving element having a condenser lens formed concentrically with the center line of the light receiving portion on the second surface side facing the first surface, the light absorbing layer side is concave on the surface of the second semiconductor layer.
  • the condensing lens is provided with a first reflecting portion formed in the center line, and a second reflecting portion formed in an annular shape on the outside of the window portion and in a concave shape on the light absorbing layer side.
  • the light incident from the window portion to the light receiving portion and transmitted through the light absorbing layer is reflected by the first reflecting portion, transmitted through the light absorbing layer again, and transmitted through the light absorbing layer again. It is characterized in that a part of the light emitted is reflected by the second reflecting portion and re-entered into the light receiving portion.
  • the light incident on the light receiving portion from the window portion and transmitted through the light absorbing layer is reflected by the first reflecting portion and transmitted through the light absorbing layer again. Then, a part of the light transmitted through the light absorption layer again is reflected by the second reflecting portion and re-entered into the light receiving portion. Therefore, the light incident from the window portion is transmitted twice through the light absorbing layer of the light receiving portion, and a part of the light is reflected by the second reflecting portion and can be transmitted through the light absorbing layer again. Therefore, since the quantum efficiency is improved, it is possible to reduce the decrease in the light receiving sensitivity when the light absorption layer is thinned in order to increase the speed of the semiconductor light receiving element.
  • the semiconductor light receiving element according to claim 2 has a radius of curvature of the first reflecting portion such that the light reflected by the first reflecting portion is between the light absorbing layer and the condensing lens. It is characterized in that it is set so as to be focused on the light and then spread to be incident on the second reflecting portion. According to the above configuration, the light that has been condensed and transmitted through the light absorption layer is spread toward the second reflection portion outside the window portion by the first reflection portion that has been miniaturized together with the light receiving portion for speeding up. Is reflected like.
  • the light incident from the window portion is reflected by the first reflecting portion, and a part of the light reflected by the first reflecting portion is reflected by the second reflecting portion, so that the light incident from the window portion absorbs light. It is possible to improve the quantum efficiency by transmitting through the layer a plurality of times and reduce the decrease in the light receiving sensitivity.
  • the semiconductor light receiving element is the light beam incident on the incident point where the light reflected by the first reflecting portion is incident on the second reflecting portion and the second light ray. It is characterized in that the radius of curvature of the second reflecting portion is set so that the normals of the reflecting portions overlap or approach each other. According to the above configuration, when the light reflected by the first reflecting portion is reflected by the second reflecting portion, the light reflected by the second reflecting portion coincides with the reflection point of the original first reflecting portion. It can be brought close and incident on the first reflecting portion.
  • the light transmitted through the light absorption layer can be reflected by the second reflecting portion and re-entered into the light absorption layer, and the light receiving sensitivity is lowered when the light absorption layer is thinned in order to increase the speed of the semiconductor light receiving element. Can be reduced.
  • the semiconductor light receiving element of the present invention it is possible to reduce the decrease in light receiving sensitivity due to high speed.
  • the semiconductor light receiving element 1 has a light receiving portion 3 as a semiconductor substrate 2 on the first surface 2a side of, for example, an n-InP substrate.
  • a condenser lens 4 formed concentrically with the center line CL of the light receiving unit 3 is provided.
  • An n-InP layer as the first semiconductor layer 5, an InGaAs layer as the light absorption layer 6, and a p-InP layer as the second semiconductor layer 7 are laminated on the first surface 2a of the semiconductor substrate 2 in this order.
  • the semiconductor substrate 2, the first semiconductor layer 5, and the second semiconductor layer 7 are transparent to infrared light used for optical communication.
  • the light receiving unit 3 forms the second semiconductor layer 7, the light absorption layer 6, and the first semiconductor layer 5 in a columnar or truncated cone shape by, for example, etching, and the surface 7a (light absorption layer) of the second semiconductor layer 7 is formed. It is a photodiode in which the surface opposite to 6) is formed in a partially spherical shape.
  • the surface 7a of the second semiconductor layer 7 is formed in a partially spherical shape to form a light receiving portion. 3 can also be formed.
  • the partially spherical surface 7a is covered with a dielectric film 8a (for example, SiN film, SiO2 film) except for the outer edge portion.
  • a metal film 8b for example, a laminated film of a Ti film and an Au film is selectively deposited so as to cover the surface 7a of the second semiconductor layer 7 and the dielectric film 8a, and the light absorption layer 6 side is concave.
  • the first reflective portion 8 that has become a reflective surface is formed.
  • the metal film 8b is connected to the outer edge portion of the surface 7a of the second semiconductor layer 7 and serves as an electrode (anode electrode) of the semiconductor light receiving element 1. Since the dielectric film 8a is provided between the metal film 8b and the second semiconductor layer 7 except for the outer edge portion of the surface 7a, unevenness is generated due to alloying at the interface between the metal film 8b and the second semiconductor layer 7. Is prevented and a smooth reflective surface is formed.
  • the side surface of the light receiving portion 3 may be covered with a protective film (for example, a SiN film or a SiO2 film).
  • An electrode 11 (cathode electrode) connected to the first semiconductor layer 5 exposed by etching is formed in a predetermined region on the first surface 2a side of the semiconductor substrate 2 separated from the light receiving portion 3.
  • the electrode 11 may be formed at a portion of the second surface 2b of the semiconductor substrate 2 separated from the condenser lens 4.
  • the first surface 2a side of the semiconductor light receiving element 1 is fixed to the mounting substrate, and the anode electrode and the cathode electrode are connected to the corresponding wirings on the mounting substrate, respectively, and the photocurrent converted by the light receiving unit 3 is obtained. Is taken out of the semiconductor light receiving element 1.
  • the condenser lens 4 is a convex lens formed concentrically with the center line CL of the light receiving portion 3 by etching the semiconductor substrate 2 from the second surface 2b side toward the first surface 2a side.
  • An antireflection film 12 (for example, a SiN film) for antireflection of incident light is formed on the second surface 2b of the semiconductor substrate 2 including the surface of the condenser lens 4.
  • a window portion 14 through which light is incident is provided in the vicinity of the center line CL of the condenser lens 4.
  • the window portion 14 is formed in a partially spherical shape having a radius of curvature r2.
  • the radius of curvature r3 of the outer portion 15 of the window portion 14 is set to be larger than the radius of curvature r2 of the window portion 14 and gradually increase as the distance from the window portion 14 increases.
  • a metal film 16 (for example, a laminated film of a Ti film and an Au film) is selectively deposited on the outer portion 15, and a second reflective portion 17 having an annular shape and a concave light absorption layer 6 side surrounding the window portion 14 is formed. ing.
  • the light emitted from the point I on the center line CL corresponding to the emission end of the optical fiber cable travels in the air while spreading with a divergence angle of 2 ⁇ (full angle) as shown by, for example, the rays IL1 and IL2. It is incident on the semiconductor light receiving element 1 from the window portion 14 of the condenser lens 4. The light incident on the light receiving unit 3 of the semiconductor light receiving element 1 is collected by the condenser lens 4 and transmitted through the light absorbing layer 6, reflected by the first reflecting unit 8 and transmitted through the light absorbing layer 6 again.
  • the first reflecting portion 8 is formed in a concave shape having a radius of curvature smaller than that of the window portion 14, and the light reflected by the first reflecting portion 8 is collected between the light absorbing layer 6 and the condenser lens 4. It spreads backward and reaches the condenser lens 4. A part of the light that has reached the condenser lens 4 is incident on the second reflecting portion 17.
  • the light incident on the second reflecting unit 17 is reflected by the second reflecting unit 17 toward the first surface 2a side of the semiconductor substrate 2 as shown by the reflected rays RL1 and RL2, and is re-incidented on the light receiving unit 3.
  • the light that has re-entered the light-receiving unit 3 and has passed through the light-absorbing layer 6 is reflected by the first reflecting unit 8 and is transmitted through the light-absorbing layer 6 once more. Therefore, the light incident from the window portion 14 is transmitted through the light absorption layer 6 twice, and a part of the light is transmitted through the light absorption layer 6 twice more, so that the quantum efficiency is improved. Therefore, when the light absorption layer 6 is thinned for high speed, the thickness of the light absorption layer 6 can be substantially compensated and the decrease in the light receiving sensitivity can be reduced.
  • FIG. 3 is an explanatory diagram of the relationship between the condenser lens 4, the first reflecting unit 8, and the second reflecting unit 17.
  • the partially spherical window portion 14 having a radius of curvature r2 in the condenser lens 4 is represented by an arc R2, and the center of the arc R2 having a radius of curvature r2 is a point O on the center line CL.
  • the partially spherical reflection surface of the first reflecting portion 8 having the radius of curvature r1 is represented by the arc R1, and the center of the arc R1 having the radius of curvature r1 is defined as C1.
  • the axis that coincides with the center line CL passing through the point O and the center C1 is the y-axis
  • the axis that passes through the point O and is orthogonal to the y-axis is the x-axis
  • the point O is the origin.
  • the light absorption layer 6 is parallel to the x-axis, is located between the center C1 and the arc R1 (first reflecting portion 8), and the y-axis passes through the center of the light absorption layer 6. Further, the reflection surface of the second reflection unit 17 is represented by a curve R3, and the arc R2a, which is an extension of the arc R2, is represented by a two-dot chain line. Since the condenser lens 4, the first reflecting portion 8, and the second reflecting portion 17 have symmetrical shapes centered on the y-axis, the light ray IL1 will be described as an example.
  • Light is emitted from the point I (0, r2 + h) separated from the condenser lens 4 on the y-axis by a distance h toward the light absorption layer 6 so that the optical axis coincides with the y-axis, as shown by the light ray IL1.
  • It has a divergence angle ⁇ (half angle) and is incident on the window portion 14 (arc R2) of the condenser lens 4.
  • ⁇ half angle
  • ⁇ the angle formed by the straight line OP and the y-axis
  • ⁇ be the angle formed by the straight line OP (normal line of the window portion 14 at the point P) and the line segment IP (ray IL1).
  • the light refracted and incident from the point P into the semiconductor substrate 2 passes through the light absorption layer 6 and is incident on the point Q (x1, y1) on the arc R1.
  • the center C1 of the arc R1 be the point C1 (0, ⁇ t) on the y-axis.
  • ⁇ be the angle formed by the straight line OP and the line segment PQ
  • ⁇ be the angle formed by the straight line C1Q (normal of the first reflecting portion 8 at the point Q) and the line segment PQ.
  • the angle formed by the tangent T1 of the straight line L1 orthogonal to the y-axis and the arc R1 is ⁇ .
  • the refractive index of the semiconductor substrate 2 with respect to air is n.
  • the radius of curvature r3 of the second reflecting portion 17 is larger than the radius of curvature r2 of the window portion 14, and gradually increases as the distance from the window portion 14 increases.
  • the light reflected at the point Q and incident on the point S is reflected at the point S toward the first surface 2a of the semiconductor substrate 2.
  • this virtual reflecting portion is represented by an arc R2a having a radius of curvature r2.
  • the light incident on the point Sa (x2, y2) where the arc R2a intersects the line segment QS is reflected symmetrically with respect to the straight line OSa (normal at the point Sa of the virtual reflection portion), so that the reflected light beam is reflected.
  • RL1a it cannot be re-entered into the light absorbing layer 6.
  • FIG. 4 shows the inclination angle of the straight line M with respect to the x-axis and the inclination angle of the tangent T2a at the point Sa with respect to the angle ⁇ formed by the straight line OP and the y-axis.
  • the curve R3 is composed of a plurality of points defined as described above with respect to the light incident on the window portion 14, and the radius of curvature r3 is gradually increased in order from the point closest to the window portion 14 to determine the curve R3, and the outside
  • the portion 15 can be smoothly connected to the window portion 14.
  • the radius of curvature r3 at the point S can be set by setting the slope of the tangent T3 of the second reflecting portion 17 at the point S to coincide with or close to the slope m1 of the straight line M orthogonal to the incident light. Then, the curve R3 can be determined by a plurality of points for which the radius of curvature r3 is set as described above for the light incident on the window portion 14.
  • the second reflecting portion 17 of the semiconductor light receiving element 1 has a reflecting surface whose cross section including the center line CL is represented by the curve R3 defined as described above.
  • the light that was supposed to be reflected at the point Sa like the reflected light ray RL1a can be reflected at the point S and re-entered into the light absorption layer 6 as shown by the reflected light ray RL1.
  • the straight line C3S is superimposed on the line segment QS, the reflected light ray RL1 is incident on the original reflection point Q, so that it can be reliably re-incidented on the light absorption layer 6, and is reflected at the point Q to be reflected on the light absorption layer. It can be incident on 6 once more.
  • the light ray IL2 can be re-entered into the light absorbing layer 6 as shown by the reflected light ray RL2 in the same manner as the light ray IL1.
  • the second reflecting portion 17 has a reflecting surface whose cross section including the center line CL is represented by the curve R3 defined as described above. Therefore, even if the second reflecting portion 17 is away from the center line CL, a part of the light incident on the window portion 14 and reflected by the first reflecting portion 8 is reflected like the reflected rays RL1 and RL2. It can be re-entered into the light absorption layer 6. Then, the light re-entered on the light absorbing layer 6 is reflected by the first reflecting unit 8 and is incident on the light absorbing layer 6 once more, so that the thickness of the light absorbing layer 6 is substantially quadrupled and the quantum is quantum.
  • the efficiency is improved, and even when the light absorption layer 6 is thinned, the decrease in light receiving sensitivity can be reduced.
  • the light corresponding to the center line CL and the light in the vicinity thereof are reflected by the first reflecting unit 8, the light reaches the window unit 14 and goes out of the semiconductor light receiving element 1.
  • the operation and effect of the semiconductor light receiving element 1 will be described.
  • the light incident on the light receiving unit 3 from the window portion 14 of the semiconductor light receiving element 1 and transmitted through the light absorbing layer 6 is reflected by the first reflecting unit 8 and transmitted through the light absorbing layer 6 again.
  • a part of the light transmitted through the light absorbing layer 6 again is reflected by the second reflecting unit 17 and re-entered into the light receiving unit 3.
  • the light incident from the window portion 14 can be transmitted twice through the light absorption layer 6 of the light receiving portion 3 by the first reflecting portion 8.
  • a part of the light transmitted through the light absorbing layer 6 twice is reflected by the second reflecting unit 17, and can be transmitted through the light absorbing layer 6 again. Therefore, since the quantum efficiency is improved, it is possible to reduce the decrease in the light receiving sensitivity when the light absorption layer 6 is thinned in order to increase the speed of the semiconductor light receiving element 1.
  • the radius of curvature r1 of the first reflecting portion 8 is such that the light reflected by the first reflecting portion 8 is condensed between the light absorbing layer 6 and the condensing lens 4 and then spreads to be incident on the second reflecting portion 17. Is set to. Therefore, the light transmitted through the light absorbing layer 6 is reflected so as to be spread toward the second reflecting portion 17 outside the window portion 14 by the first reflecting portion 8 which is miniaturized together with the light receiving portion 3 for speeding up. Can be made to. Therefore, the light incident from the window portion 14 is reflected by the first reflecting portion 8, and a part of the light reflected by the first reflecting portion is reflected by the second reflecting portion 17 to transmit the light absorbing layer 6 a plurality of times. As a result, the quantum efficiency is improved, so that the decrease in the light receiving sensitivity can be reduced.
  • the incident light ray (line segment QS) and the normal line (straight line C3S) of the second reflecting portion 17 overlap.
  • the radius of curvature r3 of the second reflecting portion 17 is set so as to approach each other. Therefore, when the light reflected by the first reflecting unit 8 is reflected by the second reflecting unit 17, the light reflected by the second reflecting unit 17 coincides with or approaches the original reflection point Q of the first reflecting unit 8. Can be incident.
  • the light transmitted through the light absorption layer 6 can be reflected by the second reflecting unit 17 and re-entered into the light absorption layer 6, and when the light absorption layer 6 is thinned for speeding up, the light receiving sensitivity becomes high. The decrease can be reduced.
  • the decrease in light receiving sensitivity is further reduced.
  • the materials of the semiconductor substrate 2, the first and second semiconductor layers 5, 7, and the light absorption layer 6 are not limited to the above, and it is appropriate to use a known material suitable for the wavelength of the received light. It is possible to form a semiconductor light receiving element 1 provided with a light receiving unit 3 having a size.
  • 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.

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  • Electromagnetism (AREA)
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Abstract

[Problem] To provide a semiconductor light-receiving element that makes it possible to mitigate decreases in light reception sensitivity accompanying increases in speed. [Solution] A semiconductor light-receiving element (1) having a light-receiving section (3) formed by layering a first semiconductor layer (5), a light-absorbing layer (6), and a second semiconductor layer (7) in this order on a first surface (2a) of a semiconductor substrate (2), in which a condenser lens (4) is formed concentrically with a central line (CL) of the light-receiving section (3) on a second surface (2b) side of the semiconductor substrate (2) opposite from the first surface (2a), and wherein a first reflective section (8) formed to have a concave shape on the light-absorbing layer (6) side is provided to the surface (7a) of the second semiconductor layer (7), the condenser lens (4) comprises a window section (14) near the central line (CL) and a second reflective section (17) formed as a ring on the outside of the window section (14) with a concave shape on the light-absorbing layer (6) side, light that enters the light-receiving section (3) from the window section (14) and is transmitted through the light-absorbing layer (6) is reflected by the first reflective section (8) and retransmitted through the light-absorbing layer (6), and some of the light retransmitted through the light-absorbing layer (6) is reflected by the second reflective section (17) and enters the light-receiving section (3) again.

Description

半導体受光素子Semiconductor light receiving element
　本発明は、光通信に用いられる半導体受光素子に関し、特に素子容量を小さくし、且つドリフト時間を短縮することにより高速動作可能な半導体受光素子に関する。 The present invention relates to a semiconductor light receiving element used for optical communication, and particularly to a semiconductor light receiving element capable of high-speed operation by reducing the element capacitance and shortening the drift time.
　従来から、光通信分野では、光ファイバケーブルを介して通信される情報量の増加に対応するために、伝送速度を高速化する技術の開発が進められている。伝送速度を高速化するために、受光した光信号を電気信号（光電流）に変換する受光素子を高速動作させることが要求されている。 Conventionally, in the field of optical communication, the development of technology for increasing the transmission speed has been promoted in order to cope with the increase in the amount of information communicated via the optical fiber cable. In order to increase the transmission speed, it is required to operate a light receiving element that converts a received optical signal into an electric signal (photocurrent) at high speed.
　受光素子としては、面入射型の半導体受光素子が広く利用されている。面入射型の半導体受光素子は、半導体基板の第１面側に光吸収層を有する受光部を備え、第１面側又は第１面に対向する第２面側に配置された光ファイバケーブルから出射された光が、受光部に光吸収層の厚さ方向に入射される。この半導体受光素子を高速動作させるために、素子容量及び素子抵抗の低減と、受光部の光吸収層で生成した電荷（キャリア）のドリフト時間の短縮が要求されている。 As the light receiving element, a surface incident type semiconductor light receiving element is widely used. The surface-incident type semiconductor light receiving element is provided with a light receiving portion having a light absorption layer on the first surface side of the semiconductor substrate, and is formed from an optical fiber cable arranged on the first surface side or the second surface side facing the first surface. The emitted light is incident on the light receiving portion in the thickness direction of the light absorption layer. In order to operate this semiconductor light receiving element at high speed, it is required to reduce the element capacitance and the element resistance and shorten the drift time of the charge (carrier) generated in the light absorption layer of the light receiving portion.
　素子容量の低減には、受光部の面積を小さくすることが必要である。例えば４０ＧＨｚ程度の周波数帯域で使用される面入射型半導体受光素子では、要求される受光部の直径は１０μｍ程度になる。しかし、受光部が小型化されると受光量が減少するので、受光感度が低下する。 To reduce the element capacity, it is necessary to reduce the area of the light receiving part. For example, in a surface-incident semiconductor light receiving element used in a frequency band of about 40 GHz, the required diameter of the light receiving portion is about 10 μm. However, when the light receiving portion is miniaturized, the amount of light received decreases, so that the light receiving sensitivity decreases.
　一方、ドリフト時間の短縮には、受光部の光吸収層の厚さを薄くすることが必要である。例えば４０ＧＨｚ程度の周波数帯域で使用される半導体受光素子では、光吸収層の厚さを１μｍ以下にすることが要求される。光吸収層が薄いので、光をキャリアに変換する量子効率が低下し、受光感度が低下する。その上、光吸収層を薄くすると素子容量が大きくなる。 On the other hand, in order to shorten the drift time, it is necessary to reduce the thickness of the light absorption layer of the light receiving part. For example, in a semiconductor light receiving element used in a frequency band of about 40 GHz, the thickness of the light absorption layer is required to be 1 μm or less. Since the light absorption layer is thin, the quantum efficiency of converting light into carriers is lowered, and the light receiving sensitivity is lowered. Moreover, if the light absorption layer is made thin, the element capacity becomes large.
　上記のように、高速化しながら受光感度の低下を軽減することは容易ではない。そこで、例えば特許文献１のように、高速化のために受光部の面積を小さくしたときに受光感度の低下を軽減するために、半導体基板に一体的に形成された集光レンズを有する半導体受光素子が知られている。光が広がるため受光部に到達できない光も集光レンズで集光して受光部に入射させるので、面積が小さい受光部でも受光感度の低下が軽減される。 As mentioned above, it is not easy to reduce the decrease in light receiving sensitivity while increasing the speed. Therefore, for example, as in Patent Document 1, a semiconductor light receiving device having a condenser lens integrally formed on a semiconductor substrate in order to reduce a decrease in light receiving sensitivity when the area of the light receiving portion is reduced for high speed. The element is known. Since the light that cannot reach the light receiving portion due to the spread of light is also collected by the condenser lens and incident on the light receiving portion, the decrease in the light receiving sensitivity is reduced even in the light receiving portion having a small area.
　また、高速化のために光吸収層を薄くしたときの受光感度の低下も軽減するために、特許文献２のように、集光レンズで集光して受光部に入射させ、光吸収層を透過した光を反射させて光吸収層を再度透過させ、この光を集光レンズの中央部表面に形成された金属反射膜によって受光部に向けて反射させる半導体受光素子が知られている。光が光吸収層を複数回透過して量子効率が向上するので、受光感度の低下が軽減される。 Further, in order to reduce the decrease in the light receiving sensitivity when the light absorbing layer is thinned for speeding up, as in Patent Document 2, the light absorbing layer is condensed by a condensing lens and incident on the light receiving portion to form the light absorbing layer. There is known a semiconductor light receiving element that reflects the transmitted light, transmits the light absorbing layer again, and reflects the light toward the light receiving portion by a metal reflecting film formed on the central surface of the condenser lens. Since the light passes through the light absorption layer a plurality of times to improve the quantum efficiency, the decrease in the light receiving sensitivity is reduced.
特開平２－１０５５８５号公報Japanese Unexamined Patent Publication No. 2-105585 特開平６－７７５１８号公報Japanese Unexamined Patent Publication No. 6-77518
　上記特許文献１では、光吸収層を薄くした場合に受光感度の低下を防ぐことができないので、受光感度の低下の軽減と高速化の両立が困難である。また、特許文献２のように、集光レンズの中央部表面に形成された金属反射膜は、入射光を集光レンズ全域に入射させる場合に光強度が強い光軸及びその近傍の光を遮ってしまうので、受光感度の向上が限定的になり、却って受光感度が低下する虞もある。 In the above Patent Document 1, since it is not possible to prevent a decrease in the light receiving sensitivity when the light absorption layer is thinned, it is difficult to reduce the decrease in the light receiving sensitivity and to increase the speed at the same time. Further, as in Patent Document 2, the metal reflective film formed on the central surface of the condensing lens blocks the optical axis having high light intensity and the light in the vicinity thereof when the incident light is incident on the entire condensing lens. Therefore, the improvement of the light receiving sensitivity is limited, and there is a possibility that the light receiving sensitivity is rather lowered.
　本発明の目的は、高速化に伴う受光感度の低下を軽減することができる半導体受光素子を提供することである。 An object of the present invention is to provide a semiconductor light receiving element capable of reducing a decrease in light receiving sensitivity due to high speed.
　請求項１の発明の半導体受光素子は、半導体基板の第１面に第１半導体層と光吸収層と第２半導体層をこの順に積層させて形成された受光部を有し、前記半導体基板の前記第１面に対向する第２面側に前記受光部の中心線と同心に形成された集光レンズを有する半導体受光素子において、前記第２半導体層の表面に、前記光吸収層側が凹面状に形成された第１反射部を備え、前記集光レンズは、前記中心線の近傍の窓部と、前記窓部の外側に環状に且つ前記光吸収層側が凹面状に形成された第２反射部を備え、前記窓部から前記受光部に入射して前記光吸収層を透過した光が、前記第１反射部によって反射されて前記光吸収層を再度透過し、前記光吸収層を再度透過した光の一部が前記第２反射部によって反射されて前記受光部に再入射するように構成したことを特徴としている。 The semiconductor light-receiving element of the invention of claim 1 has a light-receiving portion formed by laminating a first semiconductor layer, a light absorption layer, and a second semiconductor layer on the first surface of the semiconductor substrate in this order, and has a light-receiving portion of the semiconductor substrate. In a semiconductor light receiving element having a condenser lens formed concentrically with the center line of the light receiving portion on the second surface side facing the first surface, the light absorbing layer side is concave on the surface of the second semiconductor layer. The condensing lens is provided with a first reflecting portion formed in the center line, and a second reflecting portion formed in an annular shape on the outside of the window portion and in a concave shape on the light absorbing layer side. The light incident from the window portion to the light receiving portion and transmitted through the light absorbing layer is reflected by the first reflecting portion, transmitted through the light absorbing layer again, and transmitted through the light absorbing layer again. It is characterized in that a part of the light emitted is reflected by the second reflecting portion and re-entered into the light receiving portion.
　上記構成によれば、窓部から受光部に入射して光吸収層を透過した光は、第１反射部で反射されて光吸収層を再度透過する。そして、光吸収層を再度透過した光の一部が、第２反射部で反射されて受光部に再入射する。従って、窓部から入射した光は受光部の光吸収層を２回透過し、そのうちの一部は第２反射部によって反射されて光吸収層を再び透過することができる。それ故、量子効率が向上するので、半導体受光素子の高速化のために光吸収層を薄くした場合の受光感度の低下を軽減することができる。 According to the above configuration, the light incident on the light receiving portion from the window portion and transmitted through the light absorbing layer is reflected by the first reflecting portion and transmitted through the light absorbing layer again. Then, a part of the light transmitted through the light absorption layer again is reflected by the second reflecting portion and re-entered into the light receiving portion. Therefore, the light incident from the window portion is transmitted twice through the light absorbing layer of the light receiving portion, and a part of the light is reflected by the second reflecting portion and can be transmitted through the light absorbing layer again. Therefore, since the quantum efficiency is improved, it is possible to reduce the decrease in the light receiving sensitivity when the light absorption layer is thinned in order to increase the speed of the semiconductor light receiving element.
　請求項２の発明の半導体受光素子は、請求項１の発明において、前記第１反射部の曲率半径は、前記第１反射部で反射された光が前記光吸収層と前記集光レンズの間に集光した後広がって前記第２反射部に入射するように設定されたことを特徴としている。
　上記構成によれば、集光されて光吸収層を透過した光は、高速化のために受光部と共に小型化された第１反射部によって、窓部の外側の第２反射部に向かって広がるように反射される。それ故、窓部から入射した光は第１反射部で反射され、第１反射部で反射された光の一部が第２反射部で反射されるので、窓部から入射した光が光吸収層を複数回透過して量子効率が向上し、受光感度の低下を軽減することができる。 In the invention of claim 1, the semiconductor light receiving element according to claim 2 has a radius of curvature of the first reflecting portion such that the light reflected by the first reflecting portion is between the light absorbing layer and the condensing lens. It is characterized in that it is set so as to be focused on the light and then spread to be incident on the second reflecting portion.
According to the above configuration, the light that has been condensed and transmitted through the light absorption layer is spread toward the second reflection portion outside the window portion by the first reflection portion that has been miniaturized together with the light receiving portion for speeding up. Is reflected like. Therefore, the light incident from the window portion is reflected by the first reflecting portion, and a part of the light reflected by the first reflecting portion is reflected by the second reflecting portion, so that the light incident from the window portion absorbs light. It is possible to improve the quantum efficiency by transmitting through the layer a plurality of times and reduce the decrease in the light receiving sensitivity.
　請求項３の発明の半導体受光素子は、請求項１又は２の発明において、前記第１反射部で反射された光が前記第２反射部に入射する入射点において、入射する光線と前記第２反射部の法線が重なる又は接近するように前記第２反射部の曲率半径が設定されたことを特徴としている。
　上記構成によれば、第１反射部で反射された光が第２反射部で反射されたときに、この第２反射部で反射された光を元の第１反射部の反射点に一致又は接近させて第１反射部に入射させることができる。従って、光吸収層を透過した光を第２反射部で反射させて光吸収層に再入射させることができ、半導体受光素子の高速化のために光吸収層を薄くした場合の受光感度の低下を軽減することができる。 In the invention of claim 1 or 2, the semiconductor light receiving element according to the third aspect is the light beam incident on the incident point where the light reflected by the first reflecting portion is incident on the second reflecting portion and the second light ray. It is characterized in that the radius of curvature of the second reflecting portion is set so that the normals of the reflecting portions overlap or approach each other.
According to the above configuration, when the light reflected by the first reflecting portion is reflected by the second reflecting portion, the light reflected by the second reflecting portion coincides with the reflection point of the original first reflecting portion. It can be brought close and incident on the first reflecting portion. Therefore, the light transmitted through the light absorption layer can be reflected by the second reflecting portion and re-entered into the light absorption layer, and the light receiving sensitivity is lowered when the light absorption layer is thinned in order to increase the speed of the semiconductor light receiving element. Can be reduced.
　本発明の半導体受光素子によれば、高速化に伴う受光感度の低下を軽減することができる。 According to the semiconductor light receiving element of the present invention, it is possible to reduce the decrease in light receiving sensitivity due to high speed.
本発明の実施例に係る半導体受光素子を集光レンズ側から見た平面図である。It is a top view which looked at the semiconductor light receiving element which concerns on embodiment of this invention from the condenser lens side. 図１のII－II線に対応する入射光の入射経路を示す断面図である。It is sectional drawing which shows the incident path of the incident light corresponding to the line II-II of FIG. 図２の集光レンズと第１反射部と第２反射部の関係の説明図である。It is explanatory drawing of the relationship of the condenser lens of FIG. 2, the 1st reflection part and the 2nd reflection part. 第２反射部に入射する光線に直交する直線と第２反射部の接線の関係の説明図である。It is explanatory drawing of the relationship of the straight line orthogonal to the light beam incident on the 2nd reflection part, and the tangent line of the 2nd reflection part.
　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.
　図１、図２に示すように、半導体受光素子１は、半導体基板２として例えばｎ－ＩｎＰ基板の第１面２ａ側に受光部３を有する。第１面２ａに対向する第２面２ｂ側には、受光部３の中心線ＣＬと同心に形成された集光レンズ４を有する。半導体基板２の第１面２ａに、第１半導体層５としてｎ－ＩｎＰ層、光吸収層６としてＩｎＧａＡｓ層、第２半導体層７としてｐ－ＩｎＰ層がこの順に積層されている。半導体基板２、第１半導体層５、第２半導体層７は、光通信に使用される赤外光に対して透明である。 As shown in FIGS. 1 and 2, the semiconductor light receiving element 1 has a light receiving portion 3 as a semiconductor substrate 2 on the first surface 2a side of, for example, an n-InP substrate. On the side of the second surface 2b facing the first surface 2a, a condenser lens 4 formed concentrically with the center line CL of the light receiving unit 3 is provided. An n-InP layer as the first semiconductor layer 5, an InGaAs layer as the light absorption layer 6, and a p-InP layer as the second semiconductor layer 7 are laminated on the first surface 2a of the semiconductor substrate 2 in this order. The semiconductor substrate 2, the first semiconductor layer 5, and the second semiconductor layer 7 are transparent to infrared light used for optical communication.
　受光部３は、例えばエッチングによって第２半導体層７、光吸収層６、第１半導体層５を１つの円柱状又は円錐台状に形成し、この第２半導体層７の表面７ａ（光吸収層６と反対側の面）を部分球面状に形成したフォトダイオードである。第２半導体層７、光吸収層６、第１半導体層５を１つの正多角柱状又は正多角錐状に形成した後、第２半導体層７の表面７ａを部分球面状に形成して受光部３を形成することもできる。 The light receiving unit 3 forms the second semiconductor layer 7, the light absorption layer 6, and the first semiconductor layer 5 in a columnar or truncated cone shape by, for example, etching, and the surface 7a (light absorption layer) of the second semiconductor layer 7 is formed. It is a photodiode in which the surface opposite to 6) is formed in a partially spherical shape. After the second semiconductor layer 7, the light absorption layer 6, and the first semiconductor layer 5 are formed in a regular polygonal columnar shape or a regular polygonal pyramid shape, the surface 7a of the second semiconductor layer 7 is formed in a partially spherical shape to form a light receiving portion. 3 can also be formed.
　部分球面状の表面７ａは、外縁部分を除いて誘電体膜８ａ（例えばＳｉＮ膜、ＳｉＯ２膜）によって覆われている。そして、第２半導体層７の表面７ａと誘電体膜８ａを覆うように、金属膜８ｂ（例えばＴｉ膜とＡｕ膜の積層膜）が選択的に堆積されて、光吸収層６側が凹面状の反射面になった第１反射部８が形成されている。 The partially spherical surface 7a is covered with a dielectric film 8a (for example, SiN film, SiO2 film) except for the outer edge portion. Then, a metal film 8b (for example, a laminated film of a Ti film and an Au film) is selectively deposited so as to cover the surface 7a of the second semiconductor layer 7 and the dielectric film 8a, and the light absorption layer 6 side is concave. The first reflective portion 8 that has become a reflective surface is formed.
　金属膜８ｂは、第２半導体層７の表面７ａの外縁部分に接続され、半導体受光素子１の電極（アノード電極）になっている。表面７ａの外縁部分以外では、金属膜８ｂと第２半導体層７との間に誘電体膜８ａを備えているので、金属膜８ｂと第２半導体層７との界面における合金化による凹凸の発生が防止され、滑らかな反射面が形成されている。受光部３の側面は、保護膜（例えばＳｉＮ膜、ＳｉＯ２膜）によって覆われていてもよい。 The metal film 8b is connected to the outer edge portion of the surface 7a of the second semiconductor layer 7 and serves as an electrode (anode electrode) of the semiconductor light receiving element 1. Since the dielectric film 8a is provided between the metal film 8b and the second semiconductor layer 7 except for the outer edge portion of the surface 7a, unevenness is generated due to alloying at the interface between the metal film 8b and the second semiconductor layer 7. Is prevented and a smooth reflective surface is formed. The side surface of the light receiving portion 3 may be covered with a protective film (for example, a SiN film or a SiO2 film).
　受光部３から離隔した半導体基板２の第１面２ａ側の所定の領域には、例えばエッチングによって露出させた第１半導体層５に接続する電極１１（カソード電極）が形成されている。電極１１は半導体基板２の第２面２ｂにおける集光レンズ４から離隔した部位に形成されていてもよい。図示を省略するが、半導体受光素子１は第１面２ａ側が実装基板に固定され、且つアノード電極とカソード電極が実装基板上の対応する配線に夫々接続され、受光部３で変換された光電流が半導体受光素子１の外部に取り出される。 An electrode 11 (cathode electrode) connected to the first semiconductor layer 5 exposed by etching is formed in a predetermined region on the first surface 2a side of the semiconductor substrate 2 separated from the light receiving portion 3. The electrode 11 may be formed at a portion of the second surface 2b of the semiconductor substrate 2 separated from the condenser lens 4. Although not shown, the first surface 2a side of the semiconductor light receiving element 1 is fixed to the mounting substrate, and the anode electrode and the cathode electrode are connected to the corresponding wirings on the mounting substrate, respectively, and the photocurrent converted by the light receiving unit 3 is obtained. Is taken out of the semiconductor light receiving element 1.
　集光レンズ４は、第２面２ｂ側から第１面２ａ側に向かって半導体基板２をエッチングすることによって、受光部３の中心線ＣＬと同心に形成された凸レンズである。この集光レンズ４の表面を含む半導体基板２の第２面２ｂには、入射光の反射防止用の反射防止膜１２（例えばＳｉＮ膜）が形成されている。 The condenser lens 4 is a convex lens formed concentrically with the center line CL of the light receiving portion 3 by etching the semiconductor substrate 2 from the second surface 2b side toward the first surface 2a side. An antireflection film 12 (for example, a SiN film) for antireflection of incident light is formed on the second surface 2b of the semiconductor substrate 2 including the surface of the condenser lens 4.
　集光レンズ４の中心線ＣＬの近傍には、光が入射する窓部１４を有する。この窓部１４は、曲率半径ｒ２の部分球面状に形成されている。窓部１４の曲率半径ｒ２は第１反射部８の曲率半径ｒ１よりも大きく設定され、例えばｒ１＝５０μｍ、ｒ２＝９０μｍである。 A window portion 14 through which light is incident is provided in the vicinity of the center line CL of the condenser lens 4. The window portion 14 is formed in a partially spherical shape having a radius of curvature r2. The radius of curvature r2 of the window portion 14 is set to be larger than the radius of curvature r1 of the first reflecting portion 8, for example, r1 = 50 μm and r2 = 90 μm.
　窓部１４の外側部分１５の曲率半径ｒ３は、窓部１４の曲率半径ｒ２よりも大きく、且つ窓部１４から離れるにつれて徐々に大きくなるように設定されている。この外側部分１５には金属膜１６（例えばＴｉ膜とＡｕ膜の積層膜）が選択的に堆積され、窓部１４を囲む環状且つ光吸収層６側が凹面状の第２反射部１７が形成されている。 The radius of curvature r3 of the outer portion 15 of the window portion 14 is set to be larger than the radius of curvature r2 of the window portion 14 and gradually increase as the distance from the window portion 14 increases. A metal film 16 (for example, a laminated film of a Ti film and an Au film) is selectively deposited on the outer portion 15, and a second reflective portion 17 having an annular shape and a concave light absorption layer 6 side surrounding the window portion 14 is formed. ing.
　光ファイバケーブルの出射端に相当する中心線ＣＬ上の点Ｉから出射された光は、例えば光線ＩＬ１，ＩＬ２で示すように発散角２θ（全角）を有して広がりながら空気中を進行し、集光レンズ４の窓部１４から半導体受光素子１に入射する。半導体受光素子１の受光部３に入射する光は、集光レンズ４によって集光されて光吸収層６を透過し、第１反射部８で反射されて光吸収層６を再度透過する。 The light emitted from the point I on the center line CL corresponding to the emission end of the optical fiber cable travels in the air while spreading with a divergence angle of 2θ (full angle) as shown by, for example, the rays IL1 and IL2. It is incident on the semiconductor light receiving element 1 from the window portion 14 of the condenser lens 4. The light incident on the light receiving unit 3 of the semiconductor light receiving element 1 is collected by the condenser lens 4 and transmitted through the light absorbing layer 6, reflected by the first reflecting unit 8 and transmitted through the light absorbing layer 6 again.
　第１反射部８は窓部１４よりも曲率半径が小さい凹面状に形成されており、第１反射部８で反射された光は、光吸収層６と集光レンズ４の間に集光した後広がって集光レンズ４に到達する。集光レンズ４に到達した光うちの一部が、第２反射部１７に入射する。 The first reflecting portion 8 is formed in a concave shape having a radius of curvature smaller than that of the window portion 14, and the light reflected by the first reflecting portion 8 is collected between the light absorbing layer 6 and the condenser lens 4. It spreads backward and reaches the condenser lens 4. A part of the light that has reached the condenser lens 4 is incident on the second reflecting portion 17.
　第２反射部１７に入射した光は、反射光線ＲＬ１，ＲＬ２で示すように第２反射部１７によって半導体基板２の第１面２ａ側に向かって反射され、受光部３に再入射する。受光部３に再入射して光吸収層６を透過した光は、第１反射部８で反射されて光吸収層６をもう１回透過する。従って、窓部１４から入射した光は光吸収層６を２回透過し、そのうちの一部の光が光吸収層６をさらに２回透過するので、量子効率が向上する。それ故、高速化のために光吸収層６を薄くした場合に、光吸収層６の厚さを実質的に補って、受光感度の低下を軽減することができる。 The light incident on the second reflecting unit 17 is reflected by the second reflecting unit 17 toward the first surface 2a side of the semiconductor substrate 2 as shown by the reflected rays RL1 and RL2, and is re-incidented on the light receiving unit 3. The light that has re-entered the light-receiving unit 3 and has passed through the light-absorbing layer 6 is reflected by the first reflecting unit 8 and is transmitted through the light-absorbing layer 6 once more. Therefore, the light incident from the window portion 14 is transmitted through the light absorption layer 6 twice, and a part of the light is transmitted through the light absorption layer 6 twice more, so that the quantum efficiency is improved. Therefore, when the light absorption layer 6 is thinned for high speed, the thickness of the light absorption layer 6 can be substantially compensated and the decrease in the light receiving sensitivity can be reduced.
　図３は、集光レンズ４と第１反射部８と第２反射部１７の関係の説明図である。集光レンズ４における曲率半径ｒ２の部分球面状の窓部１４を円弧Ｒ２で表し、曲率半径ｒ２の円弧Ｒ２の中心を中心線ＣＬ上の点Ｏとする。また、第１反射部８の曲率半径ｒ１の部分球面状の反射面を円弧Ｒ１で表し、曲率半径ｒ１の円弧Ｒ１の中心をＣ１とする。点Ｏと中心Ｃ１を通る中心線ＣＬに一致させた軸をｙ軸とし、点Ｏを通りｙ軸に直交する軸をｘ軸とし、点Ｏを原点とする。 FIG. 3 is an explanatory diagram of the relationship between the condenser lens 4, the first reflecting unit 8, and the second reflecting unit 17. The partially spherical window portion 14 having a radius of curvature r2 in the condenser lens 4 is represented by an arc R2, and the center of the arc R2 having a radius of curvature r2 is a point O on the center line CL. Further, the partially spherical reflection surface of the first reflecting portion 8 having the radius of curvature r1 is represented by the arc R1, and the center of the arc R1 having the radius of curvature r1 is defined as C1. The axis that coincides with the center line CL passing through the point O and the center C1 is the y-axis, the axis that passes through the point O and is orthogonal to the y-axis is the x-axis, and the point O is the origin.
　光吸収層６は、ｘ軸と平行であり、中心Ｃ１と円弧Ｒ１（第１反射部８）の間に位置し、光吸収層６の中心をｙ軸が通る。また、第２反射部１７の反射面を曲線Ｒ３で表し、円弧Ｒ２を延長した円弧Ｒ２ａを二点鎖線で表している。集光レンズ４と第１反射部８と第２反射部１７はｙ軸を中心とした対称な形状なので、光線ＩＬ１を例にして説明する。 The light absorption layer 6 is parallel to the x-axis, is located between the center C1 and the arc R1 (first reflecting portion 8), and the y-axis passes through the center of the light absorption layer 6. Further, the reflection surface of the second reflection unit 17 is represented by a curve R3, and the arc R2a, which is an extension of the arc R2, is represented by a two-dot chain line. Since the condenser lens 4, the first reflecting portion 8, and the second reflecting portion 17 have symmetrical shapes centered on the y-axis, the light ray IL1 will be described as an example.
　ｙ軸上で集光レンズ４から距離ｈだけ離隔した点Ｉ（０，ｒ２＋ｈ）から、光軸がｙ軸に一致するように光吸収層６に向けて光が出射され、光線ＩＬ１で示すように発散角θ（半角）を有して集光レンズ４の窓部１４（円弧Ｒ２）に入射する。光線ＩＬ１の入射点を点Ｐ（ｘ０，ｙ０）とする。直線ＯＰとｙ軸がなす角をαとし、直線ＯＰ（点Ｐにおける窓部１４の法線）と線分ＩＰ（光線ＩＬ１）がなす角をγとする。このとき点Ｐ（ｘ０，ｙ０）とγとθは下記（１）～（４）式のように表される。
（１）ｘ０＝ｒ２×ｓｉｎ（α）
（２）ｙ０＝ｒ２×ｃｏｓ（α）
（３）γ＝θ＋α
（４）θ＝ｓｉｎ-1（ｘ０／（ｘ０2＋（ｒ２＋ｈ－ｙ０）2）1/2） Light is emitted from the point I (0, r2 + h) separated from the condenser lens 4 on the y-axis by a distance h toward the light absorption layer 6 so that the optical axis coincides with the y-axis, as shown by the light ray IL1. It has a divergence angle θ (half angle) and is incident on the window portion 14 (arc R2) of the condenser lens 4. Let the incident point of the light ray IL1 be the point P (x0, y0). Let α be the angle formed by the straight line OP and the y-axis, and let γ be the angle formed by the straight line OP (normal line of the window portion 14 at the point P) and the line segment IP (ray IL1). At this time, the points P (x0, y0), γ, and θ are expressed by the following equations (1) to (4).
(1) x0 = r2 x sin (α)
(2) y0 = r2 × cos (α)
(3) γ = θ + α
(4) θ = sin -1 (x0 / (x0 2 + (r2 + h−y0) 2 ) 1/2 )
　点Ｐから半導体基板２内に屈折して入射した光は、光吸収層６を透過して円弧Ｒ１上の点Ｑ（ｘ１，ｙ１）に入射する。円弧Ｒ１の中心Ｃ１をｙ軸上の点Ｃ１（０，－ｔ）とする。直線ＯＰと線分ＰＱがなす角をβとし、直線Ｃ１Ｑ（点Ｑにおける第１反射部８の法線）と線分ＰＱがなす角をδとする。点Ｑにおいて、ｙ軸に直交する直線Ｌ１と円弧Ｒ１の接線Ｔ１がなす角をφとする。また、空気に対する半導体基板２の屈折率をｎとする。このとき、βとδとφは下記（５）～（７）式のように表される。
（５）β＝ｓｉｎ-1（ｓｉｎ（γ）／ｎ）
（６）δ＝φ＋α－β
（７）φ＝－ｔａｎ-1（ｘ１／（ｙ１＋ｔ）） The light refracted and incident from the point P into the semiconductor substrate 2 passes through the light absorption layer 6 and is incident on the point Q (x1, y1) on the arc R1. Let the center C1 of the arc R1 be the point C1 (0, −t) on the y-axis. Let β be the angle formed by the straight line OP and the line segment PQ, and let δ be the angle formed by the straight line C1Q (normal of the first reflecting portion 8 at the point Q) and the line segment PQ. At the point Q, the angle formed by the tangent T1 of the straight line L1 orthogonal to the y-axis and the arc R1 is φ. Further, the refractive index of the semiconductor substrate 2 with respect to air is n. At this time, β, δ, and φ are expressed by the following equations (5) to (7).
(5) β = sin -1 (sin (γ) / n)
(6) δ = φ + α-β
(7) φ = -tan -1 (x1 / (y1 + t))
　円弧Ｒ１上の点Ｑに入射した光は、半導体基板２の第２面２ｂに向けて反射され、第２反射部１７の反射面を表す曲線Ｒ３上の点Ｓに入射する。直線Ｌ１と線分ＱＳがなす角をσとする。このときσは下記（８）式のように表される。
（８）σ＝π／２＋α－β＋２φ The light incident on the point Q on the arc R1 is reflected toward the second surface 2b of the semiconductor substrate 2 and is incident on the point S on the curve R3 representing the reflecting surface of the second reflecting portion 17. Let σ be the angle formed by the straight line L1 and the line segment QS. At this time, σ is expressed by the following equation (8).
(8) σ = π / 2 + α-β + 2φ
　第２反射部１７の曲率半径ｒ３は、窓部１４の曲率半径ｒ２よりも大きく、且つ窓部１４から離れるにつれて徐々に大きくなる。曲線Ｒ３上の点Ｓにおける第２反射部１７の曲率半径ｒ３の中心Ｃ３をｙ軸上の点Ｃ３とする。点Ｑで反射されて点Ｓに入射する光は、点Ｓで半導体基板２の第１面２ａに向けて反射される。 The radius of curvature r3 of the second reflecting portion 17 is larger than the radius of curvature r2 of the window portion 14, and gradually increases as the distance from the window portion 14 increases. Let the center C3 of the radius of curvature r3 of the second reflecting portion 17 at the point S on the curve R3 be the point C3 on the y-axis. The light reflected at the point Q and incident on the point S is reflected at the point S toward the first surface 2a of the semiconductor substrate 2.
　仮想的に曲率半径ｒ２の部分球面状のレンズに第２反射部１７に相当する仮想反射部を設けた場合、この仮想反射部が曲率半径ｒ２の円弧Ｒ２ａで表される。この場合、円弧Ｒ２ａが線分ＱＳと交差する点Ｓａ（ｘ２，ｙ２）に入射した光は、直線ＯＳａ（仮想反射部の点Ｓａにおける法線）に対して対称に反射されるので、反射光線ＲＬ１ａで示すように光吸収層６に再入射させることができない。 When a virtual reflecting portion corresponding to the second reflecting portion 17 is provided on a partially spherical lens having a radius of curvature r2, this virtual reflecting portion is represented by an arc R2a having a radius of curvature r2. In this case, the light incident on the point Sa (x2, y2) where the arc R2a intersects the line segment QS is reflected symmetrically with respect to the straight line OSa (normal at the point Sa of the virtual reflection portion), so that the reflected light beam is reflected. As shown by RL1a, it cannot be re-entered into the light absorbing layer 6.
　ここで、点Ｓａにおける入射光線を表す線分ＱＳａに直交する直線を直線Ｍとし、点Ｓａにおける円弧Ｒ２ａの接線を接線Ｔ２ａとする。そして、図４に、直線ＯＰとｙ軸がなす角αに対して、ｘ軸に対する直線Ｍの傾斜角と点Ｓａにおける接線Ｔ２ａの傾斜角を示す。αが大きい程、即ち点Ｐがｙ軸（中心線ＣＬ）から離れる程、直線Ｍの傾斜角及び点Ｓａにおける接線Ｔ２ａの傾斜角が大きくなり、これらの角度の差も大きくなる。そして角度の差が大きくなる程、図３に示すように反射光線ＲＬ１ａは点Ｓａで入射方向から大きくずれた方向に反射されることになる。 Here, the straight line orthogonal to the line segment QSa representing the incident light beam at the point Sa is defined as the straight line M, and the tangent line of the arc R2a at the point Sa is defined as the tangent line T2a. Then, FIG. 4 shows the inclination angle of the straight line M with respect to the x-axis and the inclination angle of the tangent T2a at the point Sa with respect to the angle α formed by the straight line OP and the y-axis. The larger α, that is, the farther the point P is from the y-axis (center line CL), the larger the inclination angle of the straight line M and the inclination angle of the tangent T2a at the point Sa, and the difference between these angles also increases. Then, as the difference in angle increases, as shown in FIG. 3, the reflected light ray RL1a is reflected at the point Sa in a direction greatly deviated from the incident direction.
　直線Ｍの傾きをｍ１とし、接線Ｔ２ａの傾きをｍ２ａとすると、傾きｍ１，ｍ２ａは下記（９），（１０）式のように表される。
（９）ｍ１＝－１／ｔａｎ（σ）
（１０）ｍ２ａ＝－ｘ２／ｙ２ Assuming that the slope of the straight line M is m1 and the slope of the tangent line T2a is m2a, the slopes m1 and m2a are expressed by the following equations (9) and (10).
(9) m1 = -1 / tan (σ)
(10) m2a = -x2 / y2
　円弧Ｒ１上の点Ｑ（ｘ１，ｙ１）は下記（１１），（１２）式の関係を満たす。
（１１）ｘ１2＋（ｙ１＋ｔ）2＝ｒ１2
（１２）ｙ１－ｙ０＝（ｘ１－ｘ０）×ｔａｎ（π／２－α＋β） The points Q (x1, y1) on the arc R1 satisfy the relationship of the following equations (11) and (12).
(11) x1 2 + (y1 + t) 2 = r1 2
(12) y1-y0 = (x1-x0) × tan (π / 2-α + β)
　円弧Ｒ２ａ上の点Ｓａ（ｘ２，ｙ２）は下記（１３），（１４）式の関係を満たす。
（１３）ｘ２2＋ｙ２2＝ｒ２2
（１４）ｙ２－ｙ１＝（ｘ２－ｘ１）×ｔａｎ（σ） The point Sa (x2, y2) on the arc R2a satisfies the relationship of the following equations (13) and (14).
(13) x2 2 + y2 2 = r2 2
(14) y2-y1 = (x2-x1) × tan (σ)
　以上の（１）～（１４）式の関係から、点Ｐ（ｘ０，ｙ０）とα、ｒ１、ｒ２、ｈ、ｔを与えると、他の角β、γ、δ、θ、φ、σが定まり、点Ｑ（ｘ１，ｙ１）と点Ｓａ（ｘ２，ｙ２）が定まる。そして、直線Ｃ３Ｓ（点Ｓにおける第２反射部１７の法線）が点Ｓａを通る線分ＱＳに重なる又は接近するように、直線ＱＳａ上に第２反射部１７の曲率半径ｒ３（線分Ｃ３Ｓ）を曲率半径ｒ２よりも大きく設定した点Ｓを定めることができる。曲線Ｒ３は、窓部１４に入射する光に対して上記のように定めた複数の点によって構成され、窓部１４に近い点から順に曲率半径ｒ３を徐々に大きくして曲線Ｒ３を定め、外側部分１５が窓部１４から滑らかに連なるようにすることができる。 From the relationship of the above equations (1) to (14), when the points P (x0, y0) and α, r1, r2, h, t are given, the other angles β, γ, δ, θ, φ, σ are obtained. The point Q (x1, y1) and the point Sa (x2, y2) are determined. Then, the radius of curvature r3 (line segment C3S) of the second reflecting portion 17 is placed on the straight line QSa so that the straight line C3S (normal line of the second reflecting portion 17 at the point S) overlaps or approaches the line segment QS passing through the point Sa. ) Can be set to be larger than the radius of curvature r2. The curve R3 is composed of a plurality of points defined as described above with respect to the light incident on the window portion 14, and the radius of curvature r3 is gradually increased in order from the point closest to the window portion 14 to determine the curve R3, and the outside The portion 15 can be smoothly connected to the window portion 14.
　点Ｓにおける第２反射部１７の接線Ｔ３の傾きを直線Ｍの傾きｍ１に近づけると、直線Ｃ３Ｓが線分ＱＳに接近し、接線Ｔ３の傾きを直線Ｍの傾きｍ１に一致させた（接線Ｔ３を直線Ｍと平行にした）場合には、直線Ｃ３Ｓが線分ＱＳに重なる。従って、点Ｓにおける第２反射部１７の接線Ｔ３の傾きを入射光に直交する直線Ｍの傾きｍ１に一致又は近づけて設定することによって、点Ｓにおける曲率半径ｒ３を設定することができる。そして、窓部１４に入射する光に対して上記のように曲率半径ｒ３を設定した複数の点によって曲線Ｒ３を定めることができる。 When the slope of the tangent line T3 of the second reflecting portion 17 at the point S approaches the slope m1 of the straight line M, the straight line C3S approaches the line segment QS, and the slope of the tangent line T3 matches the slope m1 of the straight line M (tangent line T3). Is parallel to the straight line M), the straight line C3S overlaps with the line segment QS. Therefore, the radius of curvature r3 at the point S can be set by setting the slope of the tangent T3 of the second reflecting portion 17 at the point S to coincide with or close to the slope m1 of the straight line M orthogonal to the incident light. Then, the curve R3 can be determined by a plurality of points for which the radius of curvature r3 is set as described above for the light incident on the window portion 14.
　半導体受光素子１の第２反射部１７は、中心線ＣＬを含む断面が上記のように定められた曲線Ｒ３で表される反射面を有する。これにより、点Ｓａで反射光線ＲＬ１ａのように反射されるはずだった光を点Ｓで反射させて、反射光線ＲＬ１で示すように光吸収層６に再入射させることができる。直線Ｃ３Ｓを線分ＱＳに重ねた場合には、反射光線ＲＬ１は元の反射点Ｑに入射するので、確実に光吸収層６に再入射させることができ、点Ｑで反射して光吸収層６にもう１回入射させることができる。 The second reflecting portion 17 of the semiconductor light receiving element 1 has a reflecting surface whose cross section including the center line CL is represented by the curve R3 defined as described above. As a result, the light that was supposed to be reflected at the point Sa like the reflected light ray RL1a can be reflected at the point S and re-entered into the light absorption layer 6 as shown by the reflected light ray RL1. When the straight line C3S is superimposed on the line segment QS, the reflected light ray RL1 is incident on the original reflection point Q, so that it can be reliably re-incidented on the light absorption layer 6, and is reflected at the point Q to be reflected on the light absorption layer. It can be incident on 6 once more.
　第２反射部１７はｙ軸に対称なので、光線ＩＬ２についても光線ＩＬ１と同様に、反射光線ＲＬ２で示すように光吸収層６に再入射させることができる。 Since the second reflecting portion 17 is symmetrical with respect to the y-axis, the light ray IL2 can be re-entered into the light absorbing layer 6 as shown by the reflected light ray RL2 in the same manner as the light ray IL1.
　上記のように第２反射部１７は、中心線ＣＬを含む断面が上記のように定められた曲線Ｒ３で表される反射面を有する。それ故、第２反射部１７は、中心線ＣＬから離れていても、窓部１４に入射して第１反射部８で反射された光のうちの一部を反射光線ＲＬ１，ＲＬ２のように光吸収層６に再入射させることができる。そして、光吸収層６に再入射した光が第１反射部８で反射されて光吸収層６にもう１回入射するので、光吸収層６の厚さが実質的に４倍になって量子効率が向上し、光吸収層６を薄くした場合でも受光感度の低下を軽減することができる。尚、中心線ＣＬに一致する光とその近傍の光は、第１反射部８で反射されると窓部１４に到達して、半導体受光素子１の外部に出てゆく。 As described above, the second reflecting portion 17 has a reflecting surface whose cross section including the center line CL is represented by the curve R3 defined as described above. Therefore, even if the second reflecting portion 17 is away from the center line CL, a part of the light incident on the window portion 14 and reflected by the first reflecting portion 8 is reflected like the reflected rays RL1 and RL2. It can be re-entered into the light absorption layer 6. Then, the light re-entered on the light absorbing layer 6 is reflected by the first reflecting unit 8 and is incident on the light absorbing layer 6 once more, so that the thickness of the light absorbing layer 6 is substantially quadrupled and the quantum is quantum. The efficiency is improved, and even when the light absorption layer 6 is thinned, the decrease in light receiving sensitivity can be reduced. When the light corresponding to the center line CL and the light in the vicinity thereof are reflected by the first reflecting unit 8, the light reaches the window unit 14 and goes out of the semiconductor light receiving element 1.
　上記半導体受光素子１の作用、効果について説明する。
　半導体受光素子１の窓部１４から受光部３に入射して光吸収層６を透過した光は、第１反射部８によって反射されて光吸収層６を再度透過する。この光吸収層６を再度透過した光の一部は、第２反射部１７によって反射されて受光部３に再入射する。 The operation and effect of the semiconductor light receiving element 1 will be described.
The light incident on the light receiving unit 3 from the window portion 14 of the semiconductor light receiving element 1 and transmitted through the light absorbing layer 6 is reflected by the first reflecting unit 8 and transmitted through the light absorbing layer 6 again. A part of the light transmitted through the light absorbing layer 6 again is reflected by the second reflecting unit 17 and re-entered into the light receiving unit 3.
　従って、窓部１４から入射した光は、第１反射部８によって受光部３の光吸収層６を２回透過することができる。この光吸収層６を２回透過した光のうちの一部は、第２反射部１７によって反射され、光吸収層６を再び透過することができる。それ故、量子効率が向上するので、半導体受光素子１の高速化のために光吸収層６を薄くした場合における受光感度の低下を軽減することができる。 Therefore, the light incident from the window portion 14 can be transmitted twice through the light absorption layer 6 of the light receiving portion 3 by the first reflecting portion 8. A part of the light transmitted through the light absorbing layer 6 twice is reflected by the second reflecting unit 17, and can be transmitted through the light absorbing layer 6 again. Therefore, since the quantum efficiency is improved, it is possible to reduce the decrease in the light receiving sensitivity when the light absorption layer 6 is thinned in order to increase the speed of the semiconductor light receiving element 1.
　第１反射部８の曲率半径ｒ１は、第１反射部８で反射された光が光吸収層６と集光レンズ４の間に集光した後広がって、第２反射部１７に入射するように設定されている。従って、光吸収層６を透過した光を、高速化のために受光部３と共に小型化された第１反射部８によって、窓部１４の外側の第２反射部１７に向けて広げるように反射させることができる。それ故、窓部１４から入射した光を第１反射部８で反射し、第１反射部で反射した光の一部を第２反射部１７で反射して光吸収層６を複数回透過させることにより量子効率が向上するので、受光感度の低下を軽減することができる。 The radius of curvature r1 of the first reflecting portion 8 is such that the light reflected by the first reflecting portion 8 is condensed between the light absorbing layer 6 and the condensing lens 4 and then spreads to be incident on the second reflecting portion 17. Is set to. Therefore, the light transmitted through the light absorbing layer 6 is reflected so as to be spread toward the second reflecting portion 17 outside the window portion 14 by the first reflecting portion 8 which is miniaturized together with the light receiving portion 3 for speeding up. Can be made to. Therefore, the light incident from the window portion 14 is reflected by the first reflecting portion 8, and a part of the light reflected by the first reflecting portion is reflected by the second reflecting portion 17 to transmit the light absorbing layer 6 a plurality of times. As a result, the quantum efficiency is improved, so that the decrease in the light receiving sensitivity can be reduced.
　第１反射部８の点Ｑで反射された光が第２反射部１７に入射する入射点Ｓにおいて、入射する光線（線分ＱＳ）と第２反射部１７の法線（直線Ｃ３Ｓ）が重なる又は接近するように第２反射部１７の曲率半径ｒ３が設定されている。従って、第１反射部８で反射した光を第２反射部１７で反射したときに、この第２反射部１７で反射した光を元の第１反射部８の反射点Ｑに一致又は接近させて入射させることができる。それ故、光吸収層６を透過した光を第２反射部１７で反射させて光吸収層６に再入射させることができ、高速化のために光吸収層６を薄くした場合に受光感度の低下を軽減することができる。 At the incident point S where the light reflected at the point Q of the first reflecting portion 8 is incident on the second reflecting portion 17, the incident light ray (line segment QS) and the normal line (straight line C3S) of the second reflecting portion 17 overlap. Alternatively, the radius of curvature r3 of the second reflecting portion 17 is set so as to approach each other. Therefore, when the light reflected by the first reflecting unit 8 is reflected by the second reflecting unit 17, the light reflected by the second reflecting unit 17 coincides with or approaches the original reflection point Q of the first reflecting unit 8. Can be incident. Therefore, the light transmitted through the light absorption layer 6 can be reflected by the second reflecting unit 17 and re-entered into the light absorption layer 6, and when the light absorption layer 6 is thinned for speeding up, the light receiving sensitivity becomes high. The decrease can be reduced.
　光ファイバケーブルとして出射端が円錐状に形成されたコニカルファイバから光を入射させて、光強度が強い部分が第２反射部１７で反射するように構成すれば、受光感度の低下を一層軽減することができる。尚、半導体基板２や第１、第２半導体層５，７、光吸収層６の材質は、上記に限られるものではなく、受光する光の波長に適した公知の材質を使用して適切なサイズの受光部３を備えた半導体受光素子１を形成することができる。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。 If light is incident from a conical fiber whose emission end is formed into a conical shape as an optical fiber cable and the portion having high light intensity is reflected by the second reflecting portion 17, the decrease in light receiving sensitivity is further reduced. be able to. The materials of the semiconductor substrate 2, the first and second semiconductor layers 5, 7, and the light absorption layer 6 are not limited to the above, and it is appropriate to use a known material suitable for the wavelength of the received light. It is possible to form a semiconductor light receiving element 1 provided with a light receiving unit 3 having a size. 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.
１　　　：半導体受光素子
２　　　：半導体基板
２ａ　　：第１面
２ｂ　　：第２面
３　　　：受光部
４　　　：集光レンズ
５　　　：第１半導体層
６　　　：光吸収層
７　　　：第２半導体層
７ａ　　：表面
８　　　：第１反射部
８ａ　　：誘電体膜
８ｂ　　：金属膜
１１　　：電極
１２　　：反射防止膜
１４　　：窓部
１５　　：外側部分
１６　　：金属膜
１７　　：第２反射部
ＣＬ　　：中心線 1: Semiconductor light receiving element 2: Semiconductor substrate 2a: First surface 2b: Second surface 3: Light receiving unit 4: Condensing lens 5: First semiconductor layer 6: Light absorption layer 7: Second semiconductor layer 7a: Surface 8: First reflective portion 8a: Dielectric film 8b: Metal film 11: Electrode 12: Antireflection film 14: Window portion 15: Outer portion 16: Metal film 17: Second reflective portion CL: Center line

Claims (3)

  1. 　半導体基板の第１面に第１半導体層と光吸収層と第２半導体層をこの順に積層させて形成された受光部を有し、前記半導体基板の前記第１面に対向する第２面側に前記受光部の中心線と同心に形成された集光レンズを有する半導体受光素子において、
    　前記第２半導体層の表面に、前記光吸収層側が凹面状に形成された第１反射部を備え、
    　前記集光レンズは、前記中心線の近傍の窓部と、前記窓部の外側に環状に且つ前記光吸収層側が凹面状に形成された第２反射部を備え、
    　前記窓部から前記受光部に入射して前記光吸収層を透過した光が、前記第１反射部によって反射されて前記光吸収層を再度透過し、前記光吸収層を再度透過した光の一部が前記第２反射部によって反射されて前記受光部に再入射するように構成したことを特徴とする半導体受光素子。     A light receiving portion formed by laminating a first semiconductor layer, a light absorption layer, and a second semiconductor layer in this order is provided on the first surface of the semiconductor substrate, and the second surface side facing the first surface of the semiconductor substrate is provided. In a semiconductor light receiving element having a condenser lens formed concentrically with the center line of the light receiving portion.
    The surface of the second semiconductor layer is provided with a first reflective portion having a concave light absorption layer side.
    The condenser lens includes a window portion in the vicinity of the center line and a second reflecting portion formed in an annular shape on the outside of the window portion and in a concave shape on the light absorption layer side.
    One of the light incident on the light receiving portion from the window portion and transmitted through the light absorbing layer is reflected by the first reflecting portion, transmitted through the light absorbing layer again, and transmitted through the light absorbing layer again. A semiconductor light receiving element characterized in that the portion is reflected by the second reflecting portion and re-entered into the light receiving portion.
  2. 　前記第１反射部の曲率半径は、前記第１反射部で反射された光が前記光吸収層と前記集光レンズの間に集光した後広がって前記第２反射部に入射するように設定されたことを特徴とする請求項１に記載の半導体受光素子。 The radius of curvature of the first reflecting portion is set so that the light reflected by the first reflecting portion is focused between the light absorbing layer and the condensing lens and then spreads to be incident on the second reflecting portion. The semiconductor light receiving element according to claim 1, wherein the semiconductor light receiving element is characterized by the above.
  3. 　前記第１反射部で反射された光が前記第２反射部に入射する入射点において、入射する光線と前記第２反射部の法線が重なる又は接近するように前記第２反射部の曲率半径が設定されたことを特徴とする請求項１又は２に記載の半導体受光素子。 At the incident point where the light reflected by the first reflecting portion is incident on the second reflecting portion, the radius of curvature of the second reflecting portion so that the incident light beam and the normal line of the second reflecting portion overlap or approach each other. The semiconductor light receiving element according to claim 1 or 2, wherein is set.
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JP2011119484A (en) * 2009-12-03 2011-06-16 Sharp Corp Solid-state image sensor and electronic information apparatus
JP2017092179A (en) * 2015-11-06 2017-05-25 凸版印刷株式会社 Solid state imaging device and method of manufacturing the same
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001320081A (en) * 2000-05-12 2001-11-16 Fujitsu Ltd Semiconductor light receiving element
JP2011091128A (en) * 2009-10-21 2011-05-06 Canon Inc Solid-state image pickup element
JP2011119484A (en) * 2009-12-03 2011-06-16 Sharp Corp Solid-state image sensor and electronic information apparatus
JP2017092179A (en) * 2015-11-06 2017-05-25 凸版印刷株式会社 Solid state imaging device and method of manufacturing the same
CN109461778A (en) * 2018-10-31 2019-03-12 中国电子科技集团公司第四十四研究所 A kind of structure and production method improving back-illuminated photodiode responsiveness

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