WO2009144883A1 - Semiconductor light-receiving element and method of manufacture thereof - Google Patents

Semiconductor light-receiving element and method of manufacture thereof Download PDF

Info

Publication number
WO2009144883A1
WO2009144883A1 PCT/JP2009/002174 JP2009002174W WO2009144883A1 WO 2009144883 A1 WO2009144883 A1 WO 2009144883A1 JP 2009002174 W JP2009002174 W JP 2009002174W WO 2009144883 A1 WO2009144883 A1 WO 2009144883A1
Authority
WO
WIPO (PCT)
Prior art keywords
light
light receiving
mesa
layer
semiconductor
Prior art date
Application number
PCT/JP2009/002174
Other languages
French (fr)
Japanese (ja)
Inventor
渡邉さわき
Original Assignee
日本電気株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 日本電気株式会社 filed Critical 日本電気株式会社
Priority to JP2010514345A priority Critical patent/JP5278428B2/en
Publication of WO2009144883A1 publication Critical patent/WO2009144883A1/en

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components 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
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14601—Structural or functional details thereof
    • H01L27/14625—Optical elements or arrangements associated with the device

Definitions

  • the present invention relates to a semiconductor light receiving element that converts an optical signal into an electric signal and a manufacturing method thereof, and more particularly to a semiconductor light receiving element in which a plurality of waveguide type light receiving elements are integrated on the same substrate and a manufacturing method thereof.
  • WDM transmission technology that multiplexes and transmits optical signals with a plurality of wavelengths in one optical fiber is applied to realize economical and large-capacity information transmission.
  • WDM transmission apparatus increasing the transmission speed per wavelength is being studied in order to reduce the apparatus cost.
  • DPSK differential phase shift keying
  • OOK On / Off / Keying
  • the DPSK system can improve reception sensitivity by a factor of two. Therefore, the effectiveness of this method has been confirmed particularly at a transmission rate of 10 Gbit / s or more.
  • a balanced optical receiver including a 1-bit delay interferometer and two light receiving elements is used for receiving a DPSK optical signal (for example, Non-Patent Document 1).
  • Non-Patent Document 2 and 3 a balance type light receiving element in which a waveguide type light receiving element capable of high-speed operation is integrated on one chip is also being promoted.
  • the semiconductor light receiving element is: A light-receiving layer formed on a semiconductor substrate; An optical waveguide formed on the semiconductor substrate, for transmitting signal light to the light receiving layer, and having a region not including the light receiving layer on the light incident end face side; A waveguide type light receiving element comprising the light receiving layer and the optical waveguide, and a plurality of waveguide type light receiving elements integrated on the same semiconductor substrate; A light shielding mesa composed of a semiconductor layer is provided between the light incident end faces of the adjacent optical waveguides.
  • a method for manufacturing a semiconductor light receiving element according to the present invention is as follows. On a semiconductor substrate, a plurality of waveguide type light receiving elements each including a light receiving layer and an optical waveguide that transmits signal light to the light receiving layer and has a region that does not include the light receiving layer on the light incident end face side, A light shielding mesa composed of a semiconductor layer is formed between the light incident end faces of the adjacent optical waveguides.
  • the present invention it is possible to provide a light receiving element capable of reducing optical crosstalk without affecting high frequency characteristics and a method for manufacturing the same.
  • FIG. 2 is a sectional view taken along the line II-II in FIG.
  • FIG. 3 is a sectional view taken along line III-III in FIG. It is a top view of the integrated light receiving element which concerns on Embodiment 2 of this invention.
  • FIG. 5 is a VV cross-sectional view of FIG. 4.
  • FIG. 6 is a sectional view taken along line VI-VI in FIG. 4.
  • FIG. 8 is a sectional view taken along line VIII-VIII in FIG.
  • FIG. 8 is a sectional view taken along line IX-IX in FIG. 7.
  • FIG. 10 is a diagram for explaining the effect of the third embodiment. It is a figure explaining the angle when the light which injected into the light shielding mesa is emitted. It is a figure explaining the angle when the light which injected into the light shielding mesa is emitted.
  • FIG. 10 is a plan view of another integrated light receiving element according to the third embodiment.
  • Embodiment 1 1 to 3 show an integrated light receiving element 100 according to a first embodiment of the present invention.
  • FIG. 1 is a plan view of the integrated light receiving element 100.
  • 2 is a cross-sectional view taken along the line II-II in FIG. 3 is a cross-sectional view taken along the line III-III in FIG.
  • the integrated light receiving element 100 is an element including two light receiving elements. As shown in FIG. 1, the integrated light receiving element 100 receives signal lights 14a and 14b from the direction indicated by the arrows. Each light receiving element is formed independently, and has optical waveguides 19a and 19b on the incident end face side of the signal lights 14a and 14b, respectively. The optical waveguides 19a and 19b do not have a light absorption layer. In the present embodiment, two light receiving elements are provided, but the present invention is not limited to this, and a plurality of light receiving elements may be used.
  • a light shielding mesa 13 having a semiconductor layer is disposed in the vicinity of the light incident end face between the optical waveguide 19a and the optical waveguide 19b.
  • the integrated light receiving element 100 includes a semi-insulating semiconductor substrate 101 and a semiconductor layer stacked on the semi-insulating semiconductor substrate 101.
  • the semiconductor substrate 101 is, for example, a semi-insulating Fe-doped InP substrate. As shown in FIG.
  • the semiconductor layers are, for example, a buffer layer 102, an n-InP cladding layer 103, an n-InGaAsP guide layer 104, an i-InGaAs light absorption layer (light-receiving layer) 105, p- It is obtained by sequentially laminating an InP clad layer 106 and a p-InGaAs contact layer 107 to a predetermined thickness.
  • a plurality of mesas (light receiving mesas 11a and 11b, light shielding mesas 13) each having layers 102 to 107, and signal lights 14a and 14b of the light receiving mesas 11a and 11b.
  • An optical waveguide 19 having layers 102 to 104 is formed on the incident end face side.
  • the mesas 11a, 11b, 13, 19a, and 19b are formed by a well-known etching process after the layers 102 to 107 are stacked.
  • the light receiving mesas 11a and 11b are formed in a quadrangular prism shape, for example.
  • Each of the light receiving mesas 11 a and 11 b includes semiconductor layers 102 to 107 and p-side electrodes 111 a and 111 b provided on the contact layer 107.
  • the light absorption layer 105 of the light receiving mesas 11a and 11b is a light receiving layer.
  • the distance W1 between the first light receiving mesa 11a and the second light receiving mesa 11b is, for example, 50 ⁇ m or less, but the distance W1 is not limited to this.
  • the p-side electrodes 111a and 111b are, for example, stacked electrodes containing Au.
  • the n-side electrodes 121a and 121b use the n-cladding layer 103 as an n-side contact layer.
  • the n-side electrodes 121a and 121b are also laminated electrodes containing Au, for example.
  • the protective film 108 is an insulating film, for example, a silicon nitride film.
  • a buffer layer 102, an n-InP cladding layer 103, an n-InGaAsP guide layer 104, an i-InGaAs light absorption layer (light receiving layer) 105, a p-InP cladding layer 106, and a p-InGaAs contact layer. 107 are sequentially laminated by, for example, a gas source MBE (Molecular Beams Epitaxy).
  • the light receiving mesas 11a and 11b, the optical waveguides 19a and 19b, the light shielding mesa 13, the n-cladding layer 103 or the buffer layer 102 are exposed by a plurality of etching processes with different depths.
  • the etched region (n contact region) and the etched region until the semi-insulating semiconductor substrate 101 is exposed are formed.
  • the optical waveguides 19a and 19b are passive waveguides for guiding the signal lights 14a and 14b to the photoelectric conversion units (light receiving mesas 11a and 11b).
  • the light receiving mesas 11 a and 11 b and the light shielding mesa 13 are regions that are not etched and have the light absorption layer 105.
  • the light receiving mesas 11a and 11b photoelectrically convert the signal lights 14a and 14b, respectively.
  • the n-contact region, the light receiving mesas 11a and 11b, the light shielding mesa 13, and the optical waveguides 19a and 19b are left, and etching is performed until the semi-insulating semiconductor substrate 101 is reached.
  • the light receiving mesas 11a and 11b, the optical waveguides 19a and 19b, and the light shielding mesa 13 are electrically isolated.
  • generation of parasitic capacitance when the p-side and n-side pad electrodes are formed is prevented.
  • a protective film 108 is formed on the surface of the integrated light receiving element 100.
  • the protective film 108 covers the sidewalls and tops of the mesas 11a, 11b, 13, 19a, and 19b, as well as the exposed buffer layer 102, n-cladding layer 103, and semi-insulating semiconductor substrate 101 around each mesa. Formed.
  • portions of the protective film 108 formed on the tops of the light receiving mesas 11a and 11b and portions formed on the buffer layer 102 or the n-cladding layer 103 are selectively removed by etching.
  • hydrofluoric acid is used as the etchant.
  • the p-side electrodes 111a and 111b and the n-side electrodes 121a and 121b are formed on the portions where the protective film 108 has been removed. Specifically, p-side electrodes 111a and 111b are formed on top of the light receiving mesas 11a and 11b, respectively, and n-side electrodes 121a and 121b are formed on the buffer layer 102 or the n-cladding layer 103.
  • the p-side electrode 111 a and the n-side electrode 121 b formed on the top of the light receiving mesa 11 a are connected via the extraction electrode 122.
  • the extraction electrode 122 is connected to the surface of the semiconductor substrate 101 via the protective film 108.
  • the p-side electrode 111b and the n-side electrode 121a form lead wirings on the surface of the semiconductor substrate 101 through the protective film 108.
  • an antireflection film 130 such as a silicon nitride film is formed on the incident end face of the element. Thereby, the integrated light receiving element of the present embodiment is completed.
  • the signal lights 14a and 14b are incident from the direction indicated by the arrows in FIGS.
  • the incident signal lights 14a and 14b propagate through the n-guide layer 104 as a core layer for optical waveguide, and are photoelectrically converted by oozing out into the light absorption layer 105 of the light receiving mesa 11, thereby causing p-side electrodes 111a, 111b, It is taken out as an electric signal to an external electric circuit connected to the n-side electrodes 121a and 121b.
  • the light shielding mesa 13 has the same crystal structure as the light receiving mesas 11a and 11b.
  • the light absorption layer 105 of the light shielding mesa 13 absorbs scattered light. Since the refractive index of InP with respect to light having a wavelength of 1.55 ⁇ m is about 3.2, there is no total reflection for the incidence of light from the air. On the contrary, the light incident from the InP to the air at an angle of 71.6 ° or less is totally reflected at the interface between the light shielding mesa and the outside and travels through the light shielding mesa 13. In this way, stray light can be kept in the light shielding mesa 13, stray light entering the light shielding mesa 13 cannot be easily emitted to the outside, is gradually absorbed by the internal light absorption layer 105, and eventually disappears.
  • the optical waveguide is formed on the incident end face side of the light receiving mesas 11a and 11b, and the photoelectric conversion portion is formed at a position away from the incident end face.
  • the light absorption layer 105 is not formed in this optical waveguide, unlike a normal waveguide type light receiving element, almost no light is incident from the side surface on the incident end face side of the light absorption layer 105 of the photoelectric conversion unit. . Therefore, if the light shielding mesa 13 is disposed in the vicinity of the incident end face of the signal light, for example, between the optical waveguides, stray light can be suppressed before reaching the light receiving mesa 11.
  • the integrated light receiving element 100 in which crosstalk is suppressed without affecting the high frequency characteristics.
  • the protective film 108 on the side wall of the light shielding mesa 13 is a film that becomes an antireflection film, reflection when stray light enters the light shielding mesa 13 can be suppressed.
  • the light shielding mesa 13 has the same crystal layer structure as the light receiving mesas 11a and 11b. However, if the light shielding mesa 13 is formed of a crystal layer having a sufficient absorption coefficient by a method such as selective growth, the light shielding mesa A light receiving element in which talk is suppressed can be provided.
  • FIG. 4 is a plan view of the integrated light-receiving element 200 according to the second embodiment.
  • 5 is a VV cross-sectional view of FIG. 4
  • FIG. 6 is a VI-VI cross-sectional view of FIG.
  • the integrated light receiving element 200 is different from the first embodiment in that the two light receiving elements are not connected to each other and are arranged independently. The other points are the same as in the first embodiment.
  • the integrated light receiving element 200 includes light receiving mesas 21a and 21b similar to those of the first embodiment, and a light shielding mesa 23 disposed therebetween.
  • the light receiving mesas 21a and 21b and the light shielding mesa 23 have substantially the same configuration as in the first embodiment.
  • adjacent light receiving elements are not connected to each other by electrodes, and are different in that they operate independently.
  • the extraction electrode 122 in the first embodiment is not formed.
  • the light receiving elements are not connected in series, and an integrated light receiving element that operates independently can achieve substantially the same effect as the above embodiment.
  • an integrated light receiving element in which two light receiving elements are integrated is used, but the present invention is not limited to this.
  • FIG. 7 is a plan view of the integrated light receiving element 300 according to the third embodiment.
  • 8 is a cross-sectional view taken along line VIII-VIII in FIG. 7
  • FIG. 9 is a cross-sectional view taken along line IX-IX in FIG.
  • the integrated light receiving element 300 of the present embodiment is different in that the width of the light shielding mesa 33 gradually increases from the incident end face side toward the inside. The other points are the same as in the first embodiment.
  • the light shielding mesa 33 is formed between the optical waveguides 19a and 19b so as to gradually increase with a spread angle ⁇ 15 with respect to the traveling direction of the signal lights 14a and 14b.
  • the spread angle ⁇ 15 is preferably 11 ° or more.
  • the signal lights 14a and 14b are incident from the direction indicated by the arrows in FIG.
  • the light shielding mesa 33 serves as a trapping area for stray light generated by light, scattering, or the like that is not coupled to the optical waveguide.
  • the width of the light shielding mesa 33 is gradually increased with an angle ⁇ 15.
  • FIG. 10 shows a model of the light shielding mesa 33 of the present embodiment.
  • FIG. 11 shows an angle ⁇ 17 incident from the side wall in the light shielding mesa 33 to the other side wall with respect to the angle ⁇ 15 of the light shielding mesa 33 when the stray light 16 from the direction parallel to the signal lights 14a and 14b is incident on the light shielding mesa 33.
  • FIG. 12 shows the side wall in the light shielding mesa 33 with respect to the angle ⁇ 15 of the light shielding mesa 33 when the stray light 18 from the direction perpendicular to the signal light 14a, 14b (direction toward the other light receiving element) enters the light shielding mesa 33.
  • An angle ⁇ 17 incident on the other side wall is shown.
  • the incident angle of stray light that causes crosstalk is considered to be in the range from the direction parallel to the signal light 14a and 14b (0 °) to the direction perpendicular (90 °).
  • the angle ⁇ 15 of the light shielding mesa 33 is gradually increased to 11 ° or more, the light incident on the light shielding mesa 33 is totally reflected by the inner side wall, refracted at least once inside the light shielding mesa 33, and light shielding mesa. 33 light absorption layers 105 can be passed twice. Therefore, even when a sufficient width of the light shielding mesa 33 cannot be ensured, the optical path length within the light shielding mesa 33 can be substantially secured and light can be effectively shielded.
  • the protective film 108 on the side wall of the light shielding mesa 33 is a film that serves as an antireflection film, reflection when stray light enters the light shielding mesa 33 can be suppressed.
  • the light shielding mesa 33 has the same crystal layer structure as the light receiving mesas 11a and 11b. However, if the light shielding mesa 33 is formed of a crystal layer having a sufficient absorption coefficient by a method such as selective growth, the light shielding mesa A light receiving element in which talk is suppressed can be provided.
  • the width of the light shielding mesa 33 is monotonically and gradually increased.
  • it may be a multistage incremental mesa that gradually increases at a certain angle and then decreases once and then increases again. .
  • By gradually increasing the number of steps in this manner the location where the light shielding mesa is arranged is narrow, and a desired angle can be obtained even when the monotonically increasing light shielding mesa cannot achieve the desired angle, and light reception with reduced crosstalk is achieved.
  • An element can be provided. Also, as shown in FIG. 13, the same effect can be obtained with an integrated light receiving element in which the light shielding mesa 23 in FIG. 4 is replaced with the light shielding mesa 33 in FIG.
  • the semiconductor mesa structure disposed between the light incident end faces of the optical waveguide is It becomes a light shielding wall for scattered light and stray light generated at the light incident end face, and can prevent the scattered light and stray light from reaching the adjacent light receiving element.
  • the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention described above.
  • the present invention is applied to a semiconductor light receiving element that converts an optical signal into an electric signal and a method for manufacturing the same, and particularly to a semiconductor light receiving element in which a plurality of waveguide light receiving elements are integrated on the same substrate and a method for manufacturing the same. .

Abstract

Provided are a light-receiving element and method of manufacture thereof whereby optical crosstalk can be reduced, without affecting high-frequency performance. A semiconductor photodetection element comprises a light-receiving layer (105) that is formed on a semiconductor substrate (101), a light guide (19), formed on the semiconductor substrate (101), that transmits signal light to the light-receiving layer (105) and that has a region that does not contain the light-receiving layer (105) on the optical input end face side, a plurality of integrated light guide type light-receiving elements on the same semiconductor substrate (101) a light-receiving layer (105) and light guide (19), and an optical screening mesa (13) constituted of a semiconductor layer which comprises between the mutual optical input end faces of adjacent light guides (19a), (19b).

Description

半導体受光素子及びその製造方法Semiconductor light receiving element and manufacturing method thereof
　本発明は、光信号を電気信号に変換する半導体受光素子及びその製造方法に関し、特に複数の導波路型受光素子が同一基板上に集積された半導体受光素子及びその製造方法に関する。 The present invention relates to a semiconductor light receiving element that converts an optical signal into an electric signal and a manufacturing method thereof, and more particularly to a semiconductor light receiving element in which a plurality of waveguide type light receiving elements are integrated on the same substrate and a manufacturing method thereof.
　インターネット等の広帯域マルチメディア通信サービスの爆発的な需要増加に伴って、より大容量かつ高機能な光ファイバ通信システムの開発が求められている。長距離光伝送システムでは、１本の光ファイバ中に複数の波長の光信号を多重化して伝送するＷＤＭ伝送技術を適用し、経済的かつ大容量の情報伝送を実現している。ＷＤＭ伝送装置では、装置コスト低減のために波長あたりの伝送速度の高速化が検討されている。 With the explosive increase in demand for broadband multimedia communication services such as the Internet, development of higher capacity and higher performance optical fiber communication systems is required. In a long-distance optical transmission system, WDM transmission technology that multiplexes and transmits optical signals with a plurality of wavelengths in one optical fiber is applied to realize economical and large-capacity information transmission. In the WDM transmission apparatus, increasing the transmission speed per wavelength is being studied in order to reduce the apparatus cost.
　しかし、伝送速度の高速化又は伝送路の長距離化を図ろうとすると、受信装置において、光Ｓ／Ｎ比の劣化が問題となる。この問題を解決するために、近年、受信感度を向上させることができる位相変調として、差動位相シフトキーイング（ＤＰＳＫ：Differential Phase Shift Keying）変調の研究及び開発が進められている。２値信号として光の強度を用いる従来のＯＯＫ（On Off Keying）方式と比較して、ＤＰＳＫ方式は受信感度を２倍向上させることができる。そのため、特に、１０Ｇｂｉｔ／ｓ以上の伝送速度において、この方式の有効性が確認されている。一般的に、ＤＰＳＫ光信号の受信には、１ビット遅延干渉計と２つの受光素子からなるバランスド光受信器が用いられる（例えば、非特許文献１）。 However, if the transmission speed is increased or the transmission path is extended, deterioration of the optical S / N ratio becomes a problem in the receiving apparatus. In order to solve this problem, research and development of differential phase shift keying (DPSK) modulation has recently been advanced as phase modulation that can improve reception sensitivity. Compared with a conventional OOK (On / Off / Keying) system that uses light intensity as a binary signal, the DPSK system can improve reception sensitivity by a factor of two. Therefore, the effectiveness of this method has been confirmed particularly at a transmission rate of 10 Gbit / s or more. In general, a balanced optical receiver including a 1-bit delay interferometer and two light receiving elements is used for receiving a DPSK optical signal (for example, Non-Patent Document 1).
　また、小型化、高機能化の観点から、高速動作が可能な導波路型受光素子を１チップに集積化したバランス型受光素子の研究及び開発も進められている（例えば、非特許文献２及び３）。 Further, from the viewpoint of miniaturization and high functionality, research and development of a balance type light receiving element in which a waveguide type light receiving element capable of high-speed operation is integrated on one chip is also being promoted (for example, Non-Patent Document 2 and 3).
　しかしながら、この非特許文献２や非特許文献３に開示された半導体受光素子のように複数の受光素子を集積する場合、隣り合う受光素子間の光のクロストークが問題となる。光の入射部が非常に近接した位置になるため、隣の受光素子で結合できなかった光（迷光）や迷光等によって発生した散乱光が隣の受光素子へのクロストークとなり、受光素子の特性が劣化する。また、バランス型受光素子では、２つの受光素子を直列に接続して集積するため、受光部間に配線電極が必要になる。そこで、単純に受光部間に遮光壁を設けようとすると、２つの受光素子間の配線が長くなってしまい、高周波特性を悪化させてしまう。 However, when a plurality of light receiving elements are integrated like the semiconductor light receiving elements disclosed in Non-Patent Document 2 and Non-Patent Document 3, crosstalk of light between adjacent light receiving elements becomes a problem. Because the light incident part is located very close, the light (stray light) that could not be coupled by the adjacent light receiving element or the scattered light generated by stray light, etc., crosstalks to the adjacent light receiving element, and the characteristics of the light receiving element Deteriorates. Further, in the balanced light receiving element, two light receiving elements are connected in series and integrated, so that a wiring electrode is required between the light receiving portions. Therefore, if a light shielding wall is simply provided between the light receiving portions, the wiring between the two light receiving elements becomes long, and the high frequency characteristics are deteriorated.
　本発明は、高周波特性に影響を与えることなく、光クロストークを低減できる受光素子及びその製造方法を提供することを目的とする。 It is an object of the present invention to provide a light receiving element capable of reducing optical crosstalk without affecting high frequency characteristics and a method for manufacturing the same.
　本発明に係る半導体受光素子は、
　半導体基板上に形成された受光層と、
　前記半導体基板上に形成され、前記受光層に信号光を伝達し、光入射端面側に前記受光層を含まない領域を有する光導波路と、
　前記受光層と前記光導波路とを備え、同一の前記半導体基板上に複数集積された導波路型受光素子と、
　隣接する前記光導波路の光入射端面の相互間に半導体層から構成される遮光メサとを備えているものである。 The semiconductor light receiving element according to the present invention is:
A light-receiving layer formed on a semiconductor substrate;
An optical waveguide formed on the semiconductor substrate, for transmitting signal light to the light receiving layer, and having a region not including the light receiving layer on the light incident end face side;
A waveguide type light receiving element comprising the light receiving layer and the optical waveguide, and a plurality of waveguide type light receiving elements integrated on the same semiconductor substrate;
A light shielding mesa composed of a semiconductor layer is provided between the light incident end faces of the adjacent optical waveguides.
　他方、本発明に係る半導体受光素子の製造方法は、
　半導体基板上に、受光層と、前記受光層に信号光を伝達し、光入射端面側に前記受光層を含まない領域を有する光導波路とを備えた導波路型受光素子を複数集積し、
　隣接する前記光導波路の光入射端面の相互間に半導体層から構成される遮光メサを形成するものである。 On the other hand, a method for manufacturing a semiconductor light receiving element according to the present invention is as follows.
On a semiconductor substrate, a plurality of waveguide type light receiving elements each including a light receiving layer and an optical waveguide that transmits signal light to the light receiving layer and has a region that does not include the light receiving layer on the light incident end face side,
A light shielding mesa composed of a semiconductor layer is formed between the light incident end faces of the adjacent optical waveguides.
　本発明によれば、高周波特性に影響を与えることなく、光クロストークを低減できる受光素子及びその製造方法を提供することができる。 According to the present invention, it is possible to provide a light receiving element capable of reducing optical crosstalk without affecting high frequency characteristics and a method for manufacturing the same.
本発明の実施の形態１に係る集積受光素子の平面図である。It is a top view of the integrated light receiving element which concerns on Embodiment 1 of this invention. 図１のＩＩ－ＩＩ断面図である。FIG. 2 is a sectional view taken along the line II-II in FIG. 図１のＩＩＩ－ＩＩＩ断面図である。FIG. 3 is a sectional view taken along line III-III in FIG. 本発明の実施の形態２に係る集積受光素子の平面図である。It is a top view of the integrated light receiving element which concerns on Embodiment 2 of this invention. 図４のＶ－Ｖ断面図である。FIG. 5 is a VV cross-sectional view of FIG. 4. 図４のＶＩ－ＶＩ断面図である。FIG. 6 is a sectional view taken along line VI-VI in FIG. 4. 本発明の実施の形態３に係る集積受光素子の平面図である。It is a top view of the integrated light receiving element which concerns on Embodiment 3 of this invention. 図７のＶＩＩＩ－ＶＩＩＩ断面図である。FIG. 8 is a sectional view taken along line VIII-VIII in FIG. 図７のＩＸ－ＩＸ断面図である。FIG. 8 is a sectional view taken along line IX-IX in FIG. 7. 実施の形態３の効果を説明する図である。FIG. 10 is a diagram for explaining the effect of the third embodiment. 遮光メサに入射した光が出射するときの角度を説明する図である。It is a figure explaining the angle when the light which injected into the light shielding mesa is emitted. 遮光メサに入射した光が出射するときの角度を説明する図である。It is a figure explaining the angle when the light which injected into the light shielding mesa is emitted. 実施の形態３に係る他の集積受光素子の平面図である。FIG. 10 is a plan view of another integrated light receiving element according to the third embodiment.
　以下、本発明を適用した具体的な実施の形態について、図面を参照しながら詳細に説明する。ただし、本発明が以下の実施の形態に限定される訳ではない。また、説明を明確にするため、以下の記載及び図面は、適宜、簡略化されている。 Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiment. In addition, for clarity of explanation, the following description and drawings are simplified as appropriate.
実施の形態１
　図１～図３には、本発明の第１の実施の形態に係る集積受光素子１００が示されている。図１は、集積受光素子１００の平面図である。図２は、図１のＩＩ－ＩＩ断面図である。また、図３は、図１のＩＩＩ－ＩＩＩ断面図である。 Embodiment 1
1 to 3 show an integrated light receiving element 100 according to a first embodiment of the present invention. FIG. 1 is a plan view of the integrated light receiving element 100. 2 is a cross-sectional view taken along the line II-II in FIG. 3 is a cross-sectional view taken along the line III-III in FIG.
　集積受光素子１００は、２つの受光素子を備えた素子である。図１に示すように、この集積受光素子１００は矢印で示された方向から信号光１４ａ及び１４ｂを受ける。それぞれの受光素子は独立して形成されており、信号光１４ａ及び１４ｂの入射端面側に各々光導波路１９ａ及び１９ｂを有している。この光導波路１９ａ及び１９ｂは光吸収層を有していない。本実施の形態では２つの受光素子を有しているが、これに限られるものではなく、複数であればよい。 The integrated light receiving element 100 is an element including two light receiving elements. As shown in FIG. 1, the integrated light receiving element 100 receives signal lights 14a and 14b from the direction indicated by the arrows. Each light receiving element is formed independently, and has optical waveguides 19a and 19b on the incident end face side of the signal lights 14a and 14b, respectively. The optical waveguides 19a and 19b do not have a light absorption layer. In the present embodiment, two light receiving elements are provided, but the present invention is not limited to this, and a plurality of light receiving elements may be used.
　各々の光導波路１９ａ及び１９ｂの延長上には、２つの受光素子を構成する受光メサ１１ａ及び１１ｂが形成されている。また、光導波路１９ａと光導波路１９ｂとの間の光入射端面近傍に、半導体層を有する遮光メサ１３が配置されている。 On the extension of each of the optical waveguides 19a and 19b, light receiving mesas 11a and 11b constituting two light receiving elements are formed. A light shielding mesa 13 having a semiconductor layer is disposed in the vicinity of the light incident end face between the optical waveguide 19a and the optical waveguide 19b.
　以下に、本実施の形態の集積受光素子１００の詳細について説明する。集積受光素子１００は、半絶縁半導体基板１０１と、この半絶縁半導体基板１０１上に積層された半導体層とを有する。半導体基板１０１は、例えば、半絶縁性のＦｅドープＩｎＰ基板である。半導体層は、図２に示すように、例えば、半導体基板１０１上にバッファ層１０２、ｎ－ＩｎＰクラッド層１０３、ｎ－ＩｎＧａＡｓＰガイド層１０４、ｉ－ＩｎＧａＡｓ光吸収層（受光層）１０５、ｐ－ＩｎＰクラッド層１０６、ｐ－ＩｎＧａＡｓコンタクト層１０７を所定の厚みに順次積層することにより得られるものである。 Hereinafter, details of the integrated light receiving element 100 of the present embodiment will be described. The integrated light receiving element 100 includes a semi-insulating semiconductor substrate 101 and a semiconductor layer stacked on the semi-insulating semiconductor substrate 101. The semiconductor substrate 101 is, for example, a semi-insulating Fe-doped InP substrate. As shown in FIG. 2, the semiconductor layers are, for example, a buffer layer 102, an n-InP cladding layer 103, an n-InGaAsP guide layer 104, an i-InGaAs light absorption layer (light-receiving layer) 105, p- It is obtained by sequentially laminating an InP clad layer 106 and a p-InGaAs contact layer 107 to a predetermined thickness.
　このような集積受光素子１００の半導体基板１０１上には、各層１０２～１０７を有する複数のメサ（受光メサ１１ａ、１１ｂ、遮光メサ１３）、及び、受光メサ１１ａ、１１ｂの信号光１４ａ、１４ｂの入射端面側に各層１０２～１０４を有する光導波路１９が形成されている。詳しくは後述するが、各メサ１１ａ、１１ｂ、１３、１９ａ、１９ｂは、前記各層１０２～１０７を積層した後、周知のエッチング処理により形成されるものである。 On the semiconductor substrate 101 of such an integrated light receiving element 100, a plurality of mesas ( light receiving mesas 11a and 11b, light shielding mesas 13) each having layers 102 to 107, and signal lights 14a and 14b of the light receiving mesas 11a and 11b. An optical waveguide 19 having layers 102 to 104 is formed on the incident end face side. As will be described in detail later, the mesas 11a, 11b, 13, 19a, and 19b are formed by a well-known etching process after the layers 102 to 107 are stacked.
　図１及び図２に示すように、受光メサ１１ａ、１１ｂは、例えば、四角柱形状で形成される。この受光メサ１１ａ、１１ｂは、各々半導体層１０２～１０７と、コンタクト層１０７上に設けられたｐ側電極１１１ａ、１１１ｂとを有する。受光メサ１１ａ、１１ｂの光吸収層１０５は受光層である。第１の受光メサ１１ａと、第２の受光メサ１１ｂとの間の距離Ｗ１は、例えば、５０μｍ以下であるが、距離Ｗ１はこれに限られるものではない。 As shown in FIGS. 1 and 2, the light receiving mesas 11a and 11b are formed in a quadrangular prism shape, for example. Each of the light receiving mesas 11 a and 11 b includes semiconductor layers 102 to 107 and p- side electrodes 111 a and 111 b provided on the contact layer 107. The light absorption layer 105 of the light receiving mesas 11a and 11b is a light receiving layer. The distance W1 between the first light receiving mesa 11a and the second light receiving mesa 11b is, for example, 50 μm or less, but the distance W1 is not limited to this.
　ｐ側電極１１１ａ、１１１ｂは、例えば、Ａｕを含有する積層電極である。ｎ側電極１２１ａ、１２１ｂは、ｎ－クラッド層１０３をｎ側のコンタクト層として用いる。このｎ側電極１２１ａ、１２１ｂも、例えば、Ａｕを含有する積層電極である。 The p- side electrodes 111a and 111b are, for example, stacked electrodes containing Au. The n- side electrodes 121a and 121b use the n-cladding layer 103 as an n-side contact layer. The n- side electrodes 121a and 121b are also laminated electrodes containing Au, for example.
　遮光メサ１３と光導波路１９ａ、１９ｂの頂部及び側壁、受光メサ１１ａ、１１ｂの周囲のバッファ層１０２、ｎ－クラッド層１０３の表面、さらには、受光メサ１１ａ、１１ｂの側壁には、保護膜１０８が形成されている。この保護膜１０８は、絶縁膜であり、例えば、シリコン窒化膜である。 The top and side walls of the light shielding mesa 13 and the optical waveguides 19a and 19b, the buffer layer 102 around the light receiving mesas 11a and 11b, the surface of the n-cladding layer 103, and the protective film 108 on the side walls of the light receiving mesas 11a and 11b. Is formed. The protective film 108 is an insulating film, for example, a silicon nitride film.
　次に、集積受光素子１００の製造方法について説明する。まず、半導体基板１０１上に、バッファ層１０２、ｎ－ＩｎＰクラッド層１０３、ｎ－ＩｎＧａＡｓＰガイド層１０４、ｉ－ＩｎＧａＡｓ光吸収層（受光層）１０５、ｐ－ＩｎＰクラッド層１０６、ｐ－ＩｎＧａＡｓコンタクト層１０７を、例えば、ガスソースＭＢＥ（Molecular Beam Epitaxy）により順次積層する。 Next, a method for manufacturing the integrated light receiving element 100 will be described. First, on the semiconductor substrate 101, a buffer layer 102, an n-InP cladding layer 103, an n-InGaAsP guide layer 104, an i-InGaAs light absorption layer (light receiving layer) 105, a p-InP cladding layer 106, and a p-InGaAs contact layer. 107 are sequentially laminated by, for example, a gas source MBE (Molecular Beams Epitaxy).
　そして、図２、３に示すように、深さの異なる複数回のエッチング工程により、受光メサ１１ａ、１１ｂ、光導波路１９ａ、１９ｂ、遮光メサ１３、ｎ－クラッド層１０３又はバッファ層１０２が露出するまでエッチングした領域（ｎコンタクト領域）及び半絶縁半導体基板１０１が露出するまでエッチングした領域を形成する。 As shown in FIGS. 2 and 3, the light receiving mesas 11a and 11b, the optical waveguides 19a and 19b, the light shielding mesa 13, the n-cladding layer 103 or the buffer layer 102 are exposed by a plurality of etching processes with different depths. The etched region (n contact region) and the etched region until the semi-insulating semiconductor substrate 101 is exposed are formed.
　この光導波路１９ａ、１９ｂは信号光１４ａ、１４ｂを光電変換部（受光メサ１１ａ、１１ｂ）に導波させるための受動導波路である。受光メサ１１ａ、１１ｂ及び遮光メサ１３はエッチングを施さず、光吸収層１０５を有した領域である。この受光メサ１１ａ、１１ｂが、各々信号光１４ａ、１４ｂを光電変換する。 The optical waveguides 19a and 19b are passive waveguides for guiding the signal lights 14a and 14b to the photoelectric conversion units ( light receiving mesas 11a and 11b). The light receiving mesas 11 a and 11 b and the light shielding mesa 13 are regions that are not etched and have the light absorption layer 105. The light receiving mesas 11a and 11b photoelectrically convert the signal lights 14a and 14b, respectively.
　次に、ｎ－コンタクト領域及び、受光メサ１１ａ、１１ｂと遮光メサ１３、光導波路１９ａ、１９ｂを残し、半絶縁半導体基板１０１に達するまでエッチングを行なう。これにより、受光メサ１１ａと１１ｂ、光導波路１９ａと１９ｂ、遮光メサ１３間の電気的アイソレーションがなされる。また、ｐ側及びｎ側のパッド電極を形成した際の寄生容量発生を防ぐ。 Next, the n-contact region, the light receiving mesas 11a and 11b, the light shielding mesa 13, and the optical waveguides 19a and 19b are left, and etching is performed until the semi-insulating semiconductor substrate 101 is reached. As a result, the light receiving mesas 11a and 11b, the optical waveguides 19a and 19b, and the light shielding mesa 13 are electrically isolated. In addition, generation of parasitic capacitance when the p-side and n-side pad electrodes are formed is prevented.
　次に、集積受光素子１００の表面に、保護膜１０８を形成する。この保護膜１０８は、各メサ１１ａ、１１ｂ、１３、１９ａ、１９ｂの側壁、頂部、さらには、各メサの周囲の露出したバッファ層１０２もしくはｎ－クラッド層１０３もしくは半絶縁半導体基板１０１を覆うように形成される。 Next, a protective film 108 is formed on the surface of the integrated light receiving element 100. The protective film 108 covers the sidewalls and tops of the mesas 11a, 11b, 13, 19a, and 19b, as well as the exposed buffer layer 102, n-cladding layer 103, and semi-insulating semiconductor substrate 101 around each mesa. Formed.
　その後、保護膜１０８のうち、受光メサ１１ａ、１１ｂの頂部に形成された部分、バッファ層１０２もしくはｎ－クラッド層１０３上に形成された部分を、エッチングにより、選択的に除去する。ここでは、エッチング液としては、例えば、フッ酸を使用する。 Thereafter, portions of the protective film 108 formed on the tops of the light receiving mesas 11a and 11b and portions formed on the buffer layer 102 or the n-cladding layer 103 are selectively removed by etching. Here, for example, hydrofluoric acid is used as the etchant.
　次に、保護膜１０８が除去された部分に、ｐ側電極１１１ａ、１１１ｂ、ｎ側電極１２１ａ、１２１ｂをそれぞれ形成する。具体的には、受光メサ１１ａ、１１ｂの頂部にｐ側電極１１１ａ、１１１ｂを各々形成し、バッファ層１０２、もしくはｎ－クラッド層１０３上にｎ側電極１２１ａ、１２１ｂを形成する。ここで、受光メサ１１ａの頂部に形成されたｐ側電極１１１ａとｎ側電極１２１ｂとが引出電極１２２を介して接続されている。引出電極１２２は半導体基板１０１の表面上に保護膜１０８を介して接続されている。 Next, the p- side electrodes 111a and 111b and the n- side electrodes 121a and 121b are formed on the portions where the protective film 108 has been removed. Specifically, p- side electrodes 111a and 111b are formed on top of the light receiving mesas 11a and 11b, respectively, and n- side electrodes 121a and 121b are formed on the buffer layer 102 or the n-cladding layer 103. Here, the p-side electrode 111 a and the n-side electrode 121 b formed on the top of the light receiving mesa 11 a are connected via the extraction electrode 122. The extraction electrode 122 is connected to the surface of the semiconductor substrate 101 via the protective film 108.
　また、ｐ側電極１１１ｂ及びｎ側電極１２１ａは半導体基板１０１の表面上に保護膜１０８を介して引き出し配線を形成する。最後に、素子の入射端面に反射防止膜１３０、例えば、シリコン窒化膜を形成する。これにより、本実施の形態の集積受光素子が完成する。 Further, the p-side electrode 111b and the n-side electrode 121a form lead wirings on the surface of the semiconductor substrate 101 through the protective film 108. Finally, an antireflection film 130 such as a silicon nitride film is formed on the incident end face of the element. Thereby, the integrated light receiving element of the present embodiment is completed.
　以下に、本実施の形態の動作、効果について説明する。本実施の形態では、図１、３の矢印で示された方向から信号光１４ａ、１４ｂを入射する。入射された信号光１４ａ、１４ｂはｎ－ガイド層１０４を光導波のためのコア層として伝播し、受光メサ１１の光吸収層１０５に染み出すことにより光電変換され、ｐ側電極１１１ａ、１１１ｂ、ｎ側電極１２１ａ、１２１ｂに接続された外部の電気回路に電気信号として取り出される。 Hereinafter, the operation and effect of this embodiment will be described. In the present embodiment, the signal lights 14a and 14b are incident from the direction indicated by the arrows in FIGS. The incident signal lights 14a and 14b propagate through the n-guide layer 104 as a core layer for optical waveguide, and are photoelectrically converted by oozing out into the light absorption layer 105 of the light receiving mesa 11, thereby causing p- side electrodes 111a, 111b, It is taken out as an electric signal to an external electric circuit connected to the n- side electrodes 121a and 121b.
　すべての信号光が、受光メサ１１ａ、１１ｂに結合されずに、一部の信号光が周囲に漏れた場合、隣接する受光素子にとって、この光はクロストークの要因となる。また、光入射端面やモジュール内で発生した散乱光も同様である。この迷光を遮光メサ１３で吸収する。本実施例では、遮光メサ１３は受光メサ１１ａ、１１ｂと同一の結晶構造を有する。 When all signal light is not coupled to the light receiving mesas 11a and 11b and some signal light leaks to the surroundings, this light causes crosstalk for the adjacent light receiving elements. The same applies to the light incident end face and the scattered light generated in the module. This stray light is absorbed by the light shielding mesa 13. In this embodiment, the light shielding mesa 13 has the same crystal structure as the light receiving mesas 11a and 11b.
　遮光メサ１３の光吸収層１０５において散乱光を吸収する。波長１．５５μｍの光に対するＩｎＰの屈折率は約３．２であることから、空気中からの光の入射に対して、全反射は存在しない。逆に、ＩｎＰ中から空気中へは角度７１．６°以下で入射した光は遮光メサと外部への界面で全反射され、遮光メサ１３内を進行する。このように、遮光メサ１３に迷光をとどめることができ、遮光メサ１３に入った迷光は外部へ出ることができにくく、内部の光吸収層１０５で次第に吸収され、最終的には消滅する。 The light absorption layer 105 of the light shielding mesa 13 absorbs scattered light. Since the refractive index of InP with respect to light having a wavelength of 1.55 μm is about 3.2, there is no total reflection for the incidence of light from the air. On the contrary, the light incident from the InP to the air at an angle of 71.6 ° or less is totally reflected at the interface between the light shielding mesa and the outside and travels through the light shielding mesa 13. In this way, stray light can be kept in the light shielding mesa 13, stray light entering the light shielding mesa 13 cannot be easily emitted to the outside, is gradually absorbed by the internal light absorption layer 105, and eventually disappears.
　このように本実施の形態に係る集積受光素子１００では、受光メサ１１ａ、１１ｂの入射端面側に光導波路が形成され、光電変換部が入射端面から離れた位置に形成されている。また、この光導波路には、光吸収層１０５が形成されていないため、通常の導波路型受光素子と異なり、光電変換部の光吸収層１０５の入射端面側の側面からはほとんど光が入射しない。したがって、遮光メサ１３は信号光の入射端面付近、例えば、光導波路の相互間に配置しておけば、受光メサ１１へ到達する前に迷光を抑制することができる。 Thus, in the integrated light receiving element 100 according to the present embodiment, the optical waveguide is formed on the incident end face side of the light receiving mesas 11a and 11b, and the photoelectric conversion portion is formed at a position away from the incident end face. Further, since the light absorption layer 105 is not formed in this optical waveguide, unlike a normal waveguide type light receiving element, almost no light is incident from the side surface on the incident end face side of the light absorption layer 105 of the photoelectric conversion unit. . Therefore, if the light shielding mesa 13 is disposed in the vicinity of the incident end face of the signal light, for example, between the optical waveguides, stray light can be suppressed before reaching the light receiving mesa 11.
　これにより、高周波特性に影響を与えることなく、クロストークを抑制した集積受光素子１００を提供することができる。
　また、遮光メサ１３側壁の保護膜１０８を反射防止膜となるような膜とすれば、迷光が遮光メサ１３へ入射するときの反射を抑制することができる。
　さらに、本実施の形態では、遮光メサ１３は、受光メサ１１ａ、１１ｂと同一の結晶層構造としたが、選択成長などの方法により、十分な吸収係数を有する結晶層で形成すれば、よりクロストークを抑制した受光素子を提供することができる。 Thereby, it is possible to provide the integrated light receiving element 100 in which crosstalk is suppressed without affecting the high frequency characteristics.
Further, if the protective film 108 on the side wall of the light shielding mesa 13 is a film that becomes an antireflection film, reflection when stray light enters the light shielding mesa 13 can be suppressed.
Further, in the present embodiment, the light shielding mesa 13 has the same crystal layer structure as the light receiving mesas 11a and 11b. However, if the light shielding mesa 13 is formed of a crystal layer having a sufficient absorption coefficient by a method such as selective growth, the light shielding mesa A light receiving element in which talk is suppressed can be provided.
実施の形態２
　次に、図４及び図５、図６を参照して、本発明の第２の実施の形態に係る集積受光素子２００について説明する。図４は、実施の形態２に係る集積受光素子２００の平面図である。図５は、図４のＶ－Ｖ断面図、図６は、図４のＶＩ－ＶＩ断面図である。集積受光素子２００は、２つの受光素子が相互に接続されておらず、独立して配置されている点が第１実施の形態と異なる。他の点については、実施の形態１と同様である。 Embodiment 2
Next, an integrated light receiving element 200 according to a second embodiment of the present invention will be described with reference to FIGS. 4, 5, and 6. FIG. 4 is a plan view of the integrated light-receiving element 200 according to the second embodiment. 5 is a VV cross-sectional view of FIG. 4, and FIG. 6 is a VI-VI cross-sectional view of FIG. The integrated light receiving element 200 is different from the first embodiment in that the two light receiving elements are not connected to each other and are arranged independently. The other points are the same as in the first embodiment.
　集積受光素子２００は、実施の形態１と同様の受光メサ２１ａ、２１ｂと、それらの相互間に配置された遮光メサ２３とを有する。受光メサ２１ａ、２１ｂと遮光メサ２３は実施の形態１と略同様の構成である。しかし、隣り合う受光素子の相互間が電極により接続されておらず、独立して動作する点が異なる。具体的には、実施の形態１における引出電極１２２が形成されていない。 The integrated light receiving element 200 includes light receiving mesas 21a and 21b similar to those of the first embodiment, and a light shielding mesa 23 disposed therebetween. The light receiving mesas 21a and 21b and the light shielding mesa 23 have substantially the same configuration as in the first embodiment. However, adjacent light receiving elements are not connected to each other by electrodes, and are different in that they operate independently. Specifically, the extraction electrode 122 in the first embodiment is not formed.
　本実施の形態によれば、受光素子が直列に接続されておらず、独立して動作する集積受光素子においても、前記実施の形態と略同様の効果を奏することができる。なお、本実施の形態でも２個の受光素子を集積した集積受光素子としたが、これに限られるものではない。 According to this embodiment, the light receiving elements are not connected in series, and an integrated light receiving element that operates independently can achieve substantially the same effect as the above embodiment. In this embodiment, an integrated light receiving element in which two light receiving elements are integrated is used, but the present invention is not limited to this.
実施の形態３
　次に、図７及び図８、図９を参照して、本発明の第３の実施の形態に係る集積受光素子３００について説明する。図７は、実施の形態３に係る集積受光素子３００の平面図である。図８は、図７のＶＩＩＩ－ＶＩＩＩ断面図、図９は、図７のＩＸ－ＩＸ断面図である。本実施の形態の集積受光素子３００は、遮光メサ３３の幅が、入射端面側から内部へ向かって漸増している点が異なる。他の点については、実施の形態１と同様である。 Embodiment 3
Next, an integrated light-receiving element 300 according to the third embodiment of the present invention will be described with reference to FIGS. FIG. 7 is a plan view of the integrated light receiving element 300 according to the third embodiment. 8 is a cross-sectional view taken along line VIII-VIII in FIG. 7, and FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. The integrated light receiving element 300 of the present embodiment is different in that the width of the light shielding mesa 33 gradually increases from the incident end face side toward the inside. The other points are the same as in the first embodiment.
　遮光メサ３３は、光導波路１９ａと１９ｂの間に信号光１４ａ、１４ｂの進行方向に対して広がり角度θ１５をもって漸増するような形状に形成されている。この広がり角度θ１５は１１°以上であることが好ましい。 The light shielding mesa 33 is formed between the optical waveguides 19a and 19b so as to gradually increase with a spread angle θ15 with respect to the traveling direction of the signal lights 14a and 14b. The spread angle θ15 is preferably 11 ° or more.
　以下に、本実施の形態の動作、効果について説明する。本実施の形態では、図７の矢印で示された方向から信号光１４ａ、１４ｂを入射する。実施の形態１及び２と同様に、遮光メサ３３は光導波路に結合されなかった光や散乱等で発生した迷光の捕獲領域となる。本実施の形態では遮光メサ３３の幅が角度θ１５をもって漸増している。 Hereinafter, the operation and effect of this embodiment will be described. In the present embodiment, the signal lights 14a and 14b are incident from the direction indicated by the arrows in FIG. As in the first and second embodiments, the light shielding mesa 33 serves as a trapping area for stray light generated by light, scattering, or the like that is not coupled to the optical waveguide. In the present embodiment, the width of the light shielding mesa 33 is gradually increased with an angle θ15.
　図１０は本実施の形態の遮光メサ３３のモデルを示している。図１１は信号光１４ａ、１４ｂと平行方向からの迷光１６が遮光メサ３３に入射したときの、遮光メサ３３の角度θ１５に対する、遮光メサ３３内の側壁から他方の側壁へ入射する角度θ１７を示している。図１２は信号光１４ａ、１４ｂと垂直な方向（他方の受光素子へ向かう方向）からの迷光１８が遮光メサ３３に入射したときの、遮光メサ３３の角度θ１５に対する、遮光メサ３３内の側壁から他方の側壁へ入射する角度θ１７を示している。 FIG. 10 shows a model of the light shielding mesa 33 of the present embodiment. FIG. 11 shows an angle θ17 incident from the side wall in the light shielding mesa 33 to the other side wall with respect to the angle θ15 of the light shielding mesa 33 when the stray light 16 from the direction parallel to the signal lights 14a and 14b is incident on the light shielding mesa 33. ing. FIG. 12 shows the side wall in the light shielding mesa 33 with respect to the angle θ15 of the light shielding mesa 33 when the stray light 18 from the direction perpendicular to the signal light 14a, 14b (direction toward the other light receiving element) enters the light shielding mesa 33. An angle θ17 incident on the other side wall is shown.
　このモデルで考えれば、信号光１４ａ、１４ｂと平行方向からの迷光１６に対しては、メサの側壁へ入射した光は全反射により遮光メサ３３内部に閉じ込められる。また、信号光１４と垂直な方向からの迷光１８に対しては、遮光メサ３３が１１°以上の広がり角度θ１５を有していれば、光は全反射により遮光メサ３３内部に閉じ込められる。本実施の形態では、クロストークの原因となる迷光の入射する角度は信号光１４ａ、１４ｂと平行な方向（０°）から垂直な方向（９０°）の範囲であると考えられる。 Considering this model, with respect to the stray light 16 from the direction parallel to the signal lights 14a and 14b, the light incident on the side wall of the mesa is confined inside the light shielding mesa 33 by total reflection. Further, with respect to the stray light 18 from the direction perpendicular to the signal light 14, if the light shielding mesa 33 has a spread angle θ15 of 11 ° or more, the light is confined inside the light shielding mesa 33 by total reflection. In the present embodiment, the incident angle of stray light that causes crosstalk is considered to be in the range from the direction parallel to the signal light 14a and 14b (0 °) to the direction perpendicular (90 °).
　したがって、この遮光メサ３３の角度θ１５が１１°以上で漸増していれば、遮光メサ３３内に入射した光は内側の側壁で全反射され、遮光メサ３３内部で少なくとも１回屈折され、遮光メサ３３の光吸収層１０５を２回通ることができる。そのため、遮光メサ３３の幅を十分に確保できない場合でも、実質的に、遮光メサ３３内での光路長を確保でき、効果的に遮光することができる。 Therefore, if the angle θ15 of the light shielding mesa 33 is gradually increased to 11 ° or more, the light incident on the light shielding mesa 33 is totally reflected by the inner side wall, refracted at least once inside the light shielding mesa 33, and light shielding mesa. 33 light absorption layers 105 can be passed twice. Therefore, even when a sufficient width of the light shielding mesa 33 cannot be ensured, the optical path length within the light shielding mesa 33 can be substantially secured and light can be effectively shielded.
　さらに、遮光メサ３３側壁の保護膜１０８を反射防止膜となるような膜とすれば、迷光が遮光メサ３３へ入射するときの反射を抑制することができる。
　さらに、本実施の形態では、遮光メサ３３は、受光メサ１１ａ、１１ｂと同一の結晶層構造としたが、選択成長などの方法により、十分な吸収係数を有する結晶層で形成すれば、よりクロストークを抑制した受光素子を提供することができる。 Furthermore, if the protective film 108 on the side wall of the light shielding mesa 33 is a film that serves as an antireflection film, reflection when stray light enters the light shielding mesa 33 can be suppressed.
Further, in the present embodiment, the light shielding mesa 33 has the same crystal layer structure as the light receiving mesas 11a and 11b. However, if the light shielding mesa 33 is formed of a crystal layer having a sufficient absorption coefficient by a method such as selective growth, the light shielding mesa A light receiving element in which talk is suppressed can be provided.
　さらに、本実施の形態では、遮光メサ３３の幅は単調に漸増する形状としたが、ある一定角度で漸増した後、幅を一度減少させ、再び漸増するような多段漸増メサであってもよい。このように多段漸増させることで、遮光メサを配置する場所が狭く、単調漸増の遮光メサでは所望の角度にすることができない場合にも所望の角度を得ることができ、クロストークを抑制した受光素子を提供できる。
　また、図１３に示すように、図４における遮光メサ２３を図７における遮光メサ３３に置き換えた集積受光素子でも、同様の効果を奏することができる。 Further, in the present embodiment, the width of the light shielding mesa 33 is monotonically and gradually increased. However, it may be a multistage incremental mesa that gradually increases at a certain angle and then decreases once and then increases again. . By gradually increasing the number of steps in this manner, the location where the light shielding mesa is arranged is narrow, and a desired angle can be obtained even when the monotonically increasing light shielding mesa cannot achieve the desired angle, and light reception with reduced crosstalk is achieved. An element can be provided.
Also, as shown in FIG. 13, the same effect can be obtained with an integrated light receiving element in which the light shielding mesa 23 in FIG. 4 is replaced with the light shielding mesa 33 in FIG.
　以上、説明したとおり、本発明により、同一半導体基板上に複数個の半導体受光素子を集積化した半導体集積受光素子において、光導波路の光入射端面付近の相互間に配置された半導体メサ構造が、光入射端面で発生する散乱光や迷光の遮光壁となり、散乱光や迷光が隣の受光素子へ到達することを防ぐことができる。さらに、本発明は上述した実施の形態のみに限定されるものではなく、既に述べた本発明の要旨を逸脱しない範囲において種々の変更が可能であることは勿論である。 As described above, according to the present invention, in the semiconductor integrated light receiving element in which a plurality of semiconductor light receiving elements are integrated on the same semiconductor substrate, the semiconductor mesa structure disposed between the light incident end faces of the optical waveguide is It becomes a light shielding wall for scattered light and stray light generated at the light incident end face, and can prevent the scattered light and stray light from reaching the adjacent light receiving element. Furthermore, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention described above.
　この出願は、２００８年５月２８日に出願された日本出願特願２００８－１３９５７３を基礎とする優先権を主張し、その開示の全てをここに取り込む。 This application claims priority based on Japanese Patent Application No. 2008-139573 filed on May 28, 2008, the entire disclosure of which is incorporated herein.
　本発明は、光信号を電気信号に変換する半導体受光素子及びその製造方法に適用され、特に複数の導波路型受光素子が同一基板上に集積された半導体受光素子及びその製造方法に適用される。 The present invention is applied to a semiconductor light receiving element that converts an optical signal into an electric signal and a method for manufacturing the same, and particularly to a semiconductor light receiving element in which a plurality of waveguide light receiving elements are integrated on the same substrate and a method for manufacturing the same. .
１１ａ、１１ｂ、２１ａ、２１ｂ　受光メサ
１３、２３、３３　遮光メサ
１４ａ、１４ｂ　信号光
θ１５　広がり角度
１６、１８　迷光
θ１７　角度
１９ａ、１９ｂ、２９ａ、２９ｂ　光導波路
１００、２００、３００　集積受光素子
１０１　半導体基板
１０２　バッファ層
１０３　ｎ－クラッド層
１０４　ｎ－ガイド層
１０５　光吸収層
１０６　ｐ－クラッド層
１０７　ｐ－コンタクト層
１０８　保護膜
１１１ａ、１１１ｂ、２１１ａ、２１１ｂ　ｐ側電極
１２１ａ、１２１ｂ、２２１ａ、２２１ｂ　ｎ側電極
１２２　引出電極
１３０　反射防止膜 11a, 11b, 21a, 21b Light receiving mesa 13, 23, 33 Light shielding mesa 14a, 14b Signal light θ15 Spreading angle 16, 18 Stray light θ17 Angle 19a, 19b, 29a, 29b Optical waveguide 100, 200, 300 Integrated light receiving element 101 Semiconductor substrate 102 buffer layer 103 n-cladding layer 104 n-guide layer 105 light absorption layer 106 p-cladding layer 107 p-contact layer 108 protective films 111a, 111b, 211a, 211b p- side electrodes 121a, 121b, 221a, 221b n-side electrodes 122 Extraction electrode 130 Antireflection film

Claims (7)

  1. 　半導体基板上に形成された受光層と、
    　前記半導体基板上に形成され、前記受光層に信号光を伝達し、光入射端面側に前記受光層を含まない領域を有する光導波路と、
    　前記受光層と前記光導波路とを備え、同一の前記半導体基板上に複数集積された導波路型受光素子と、
    　隣接する前記光導波路の光入射端面の相互間に半導体層から構成される遮光メサとを備える半導体受光素子。     A light-receiving layer formed on a semiconductor substrate;
    An optical waveguide formed on the semiconductor substrate, for transmitting signal light to the light receiving layer, and having a region not including the light receiving layer on the light incident end face side;
    A waveguide type light receiving element comprising the light receiving layer and the optical waveguide, and a plurality of waveguide type light receiving elements integrated on the same semiconductor substrate;
    A semiconductor light receiving element comprising: a light shielding mesa composed of a semiconductor layer between light incident end faces of adjacent optical waveguides.
  2. 　前記遮光メサを構成する前記半導体層が光吸収層を含むことを特徴とする請求項１に記載の半導体受光素子。 The semiconductor light receiving element according to claim 1, wherein the semiconductor layer constituting the light shielding mesa includes a light absorption layer.
  3. 　前記遮光メサは前記受光メサと同一の結晶層構造を有する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。 3. The semiconductor light receiving element according to claim 1, wherein the light shielding mesa has the same crystal layer structure as the light receiving mesa.
  4. 　前記遮光メサの幅が、光入射端面から漸増し、かつ前記光導波路との距離が順次狭くなるように形成されていることを特徴とする請求項１～３のいずれか一項に記載の半導体受光素子。 The semiconductor according to any one of claims 1 to 3, wherein a width of the light shielding mesa is formed so as to gradually increase from a light incident end face and a distance from the optical waveguide is sequentially reduced. Light receiving element.
  5. 　前記遮光メサの幅が複数段にわたって漸増することを特徴とする請求項１～３のいずれか一項に記載の半導体受光素子。 The semiconductor light receiving element according to any one of claims 1 to 3, wherein the width of the light shielding mesa gradually increases over a plurality of stages.
  6. 　前記遮光メサの側壁に、反射防止膜が形成されていることを特徴とする請求項１～５のいずれか一項に記載の半導体受光素子。 6. The semiconductor light receiving device according to claim 1, wherein an antireflection film is formed on a side wall of the light shielding mesa.
  7. 　半導体基板上に、受光層と、前記受光層に信号光を伝達し、光入射端面側に前記受光層を含まない領域を有する光導波路とを備えた導波路型受光素子を複数集積し、
    　隣接する前記光導波路の光入射端面の相互間に半導体層から構成される遮光メサを形成する半導体受光素子の製造方法。     On a semiconductor substrate, a plurality of waveguide type light receiving elements each including a light receiving layer and an optical waveguide that transmits signal light to the light receiving layer and has a region that does not include the light receiving layer on the light incident end face side,
    A method for manufacturing a semiconductor light receiving element, wherein a light shielding mesa composed of a semiconductor layer is formed between light incident end faces of adjacent optical waveguides.
PCT/JP2009/002174 2008-05-28 2009-05-18 Semiconductor light-receiving element and method of manufacture thereof WO2009144883A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2010514345A JP5278428B2 (en) 2008-05-28 2009-05-18 Semiconductor light receiving element and manufacturing method thereof

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2008-139573 2008-05-28
JP2008139573 2008-05-28

Publications (1)

Publication Number Publication Date
WO2009144883A1 true WO2009144883A1 (en) 2009-12-03

Family

ID=41376773

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2009/002174 WO2009144883A1 (en) 2008-05-28 2009-05-18 Semiconductor light-receiving element and method of manufacture thereof

Country Status (2)

Country Link
JP (1) JP5278428B2 (en)
WO (1) WO2009144883A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2019149464A (en) * 2018-02-27 2019-09-05 住友電気工業株式会社 Semiconductor optical integrated device

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6450016A (en) * 1987-08-20 1989-02-27 Nec Corp Demultiplexing and photodetecting device
JPH02246268A (en) * 1989-03-20 1990-10-02 Fujitsu Ltd Photoreceptor
JPH06268196A (en) * 1993-03-15 1994-09-22 Toshiba Corp Optical integrated device
JPH08181350A (en) * 1994-12-27 1996-07-12 Nec Corp Semiconductor optical integrated device
JPH10107310A (en) * 1996-09-26 1998-04-24 Japan Aviation Electron Ind Ltd Waveguide-type photodiode array
JP2000353818A (en) * 1999-06-11 2000-12-19 Nec Corp Waveguide-type photodetector
WO2002007226A1 (en) * 2000-07-18 2002-01-24 Nippon Sheet Glass Co., Ltd. Photodetector array

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6450016A (en) * 1987-08-20 1989-02-27 Nec Corp Demultiplexing and photodetecting device
JPH02246268A (en) * 1989-03-20 1990-10-02 Fujitsu Ltd Photoreceptor
JPH06268196A (en) * 1993-03-15 1994-09-22 Toshiba Corp Optical integrated device
JPH08181350A (en) * 1994-12-27 1996-07-12 Nec Corp Semiconductor optical integrated device
JPH10107310A (en) * 1996-09-26 1998-04-24 Japan Aviation Electron Ind Ltd Waveguide-type photodiode array
JP2000353818A (en) * 1999-06-11 2000-12-19 Nec Corp Waveguide-type photodetector
WO2002007226A1 (en) * 2000-07-18 2002-01-24 Nippon Sheet Glass Co., Ltd. Photodetector array

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
"The 20th Annual Meeting of the IEEE Lasers and Electro-Optics Society, 2007 (LEOS 2007), 21-25 October 2007", 2007, article S.WATANABE ET AL.: "Dual Evanescently Coupled Waveguide Photodiodes for Ultra-high Bit Rate DPSK/DQPSK systems", pages: 387 - 388 *
A.UMBACH ET AL.: "Integrated Limiting Balanced Photoreceiver for 43 Gbit/s DPSK Transmission", ECOC 2005 PROCEEDINGS, vol. 3, pages 497 - 498 *
P.J.WINZER ET AL.: "Degradations in Balanced DPSK Receivers", IEEE PHOTONICS TECHNOLOGY LETTERS, vol. 15, no. 9, September 2003 (2003-09-01), pages 1282 - 1284 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2019149464A (en) * 2018-02-27 2019-09-05 住友電気工業株式会社 Semiconductor optical integrated device
JP7037958B2 (en) 2018-02-27 2022-03-17 住友電気工業株式会社 Semiconductor optical integrated device

Also Published As

Publication number Publication date
JP5278428B2 (en) 2013-09-04
JPWO2009144883A1 (en) 2011-10-06

Similar Documents

Publication Publication Date Title
JP5747592B2 (en) Receiver
US9147781B2 (en) Light receiving element with offset absorbing layer
JP3544352B2 (en) Semiconductor light receiving element
JP6318468B2 (en) Waveguide type semiconductor light-receiving device and manufacturing method thereof
US9025241B2 (en) Gain medium providing laser and amplifier functionality to optical device
EP2510390A1 (en) Waveguide optically pre-amplified detector with passband wavelength filtering
JP5477148B2 (en) Semiconductor optical wiring device
US8131122B2 (en) Monolithically integrated multi-directional transceiver
KR101510356B1 (en) Nano-wire optical block devices for amplifying, modulating, and detecting optical signals
JP4318981B2 (en) Waveguide type light receiving element
JP2017219562A (en) Optical circuit device, optical transceiver using the same, and optical semiconductor element
JP4762834B2 (en) Optical integrated circuit
JP5526611B2 (en) Semiconductor light receiving element and method for manufacturing semiconductor light receiving element
US20080137178A1 (en) Reflection-type optical modulator module
JP4291085B2 (en) Waveguide type light receiving element
JP5278428B2 (en) Semiconductor light receiving element and manufacturing method thereof
JP2010113157A (en) Optical receiver
JP5278429B2 (en) Semiconductor light receiving element and manufacturing method thereof
JP4217855B2 (en) Semiconductor photo detector
US7177337B2 (en) Semiconductor optical integrated circuit
JP3331828B2 (en) Optical transmission / reception module
KR100265858B1 (en) Wavelength division multiplexing device with monolithically integrated semiconductor laser and photodiode
CN115079347B (en) Light emitting and receiving component and optical path coupling method for light emitting and receiving component
WO2023214573A1 (en) Photodetection device and light receiver
JP2011165848A (en) Surface incident type photodiode

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 09754392

Country of ref document: EP

Kind code of ref document: A1

WWE Wipo information: entry into national phase

Ref document number: 2010514345

Country of ref document: JP

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 09754392

Country of ref document: EP

Kind code of ref document: A1