KR101001832B1 - Light Receiving Element Array Including Current-blocking layer and Method for Fabrication The Same - Google Patents

Abstract

A light receiving element array and a method of manufacturing the same are provided. The light-receiving element array includes a base substrate, a current blocking layer disposed on the base substrate, and a plurality of unit cells spaced apart from each other on the current blocking layer, each unit cell being a first type semiconductor layer disposed in turn, a photoelectric conversion And a unit light receiving element having a layer and a second type semiconductor layer. In addition, a method of manufacturing a light-receiving device array includes forming a current blocking layer on a base substrate, sequentially forming a first type semiconductor layer, a photoelectric conversion layer, and a second type semiconductor layer on the current blocking layer, and a second type semiconductor. Patterning the layer, the photoelectric conversion layer, and the first type semiconductor layer in order to form unit cells positioned on the current blocking layer and separated from each other, wherein each unit cell includes a unit light receiving element.

Light-Receiving Devices, Semi-Insulated Substrates, Current Blocking Layers

Description

Light-receiving element array having a current blocking layer and a method of manufacturing the same {Light Receiving Element Array Including Current-blocking layer and Method for Fabrication The Same

The present invention relates to a light receiving element, and more particularly, to a light receiving element array having a current blocking layer and a manufacturing method thereof.

A light receiving device is a device that converts light energy into electrical energy, and has the advantages of operating wavelength sensitivity, fast response speed, and minimum noise, and thus is widely used as an optical signal detecting device in optical communication.

In such optical communication, parallel optical interconnection is used to obtain a transmission speed of 10 Gbps or more, where a multi-channel light receiving element is almost used. However, the multi-channel light receiving device has a problem in that crosstalk is generated because a plurality of unit light receiving devices are integrated and electrical separation between the unit light receiving devices is not easy.

An object of the present invention for solving the above problems is to provide a light-receiving element array having a current blocking layer that can prevent the occurrence of crosstalk and a manufacturing method thereof.

The present invention for achieving the above-described first object includes a base substrate, a current blocking layer disposed on the base substrate and a plurality of unit cells spaced apart from each other on the current blocking layer, wherein each unit cell A light receiving element array including a unit light receiving element including a first type semiconductor layer, a photoelectric conversion layer, and a second type semiconductor layer, which are sequentially disposed.

The current blocking layer may be a semi-insulating layer, and the semi-insulating layer may be a GaAs layer or an InP layer.

The unit cell may further include a sidewall structure surrounding the unit light receiving element. The light receiving element array may further include a protective layer disposed on at least sidewalls of the unit light receiving elements, and on at least sidewalls of the unit light receiving elements, sidewalls of the sidewall structure, and an upper surface of the sidewall structure. It may further include a protective layer disposed.

The present invention for achieving the above-described second object is to form a current blocking layer on the base substrate, the step of forming a first type semiconductor layer, a photoelectric conversion layer and a second type semiconductor layer on the current blocking layer in order And patterning the second type semiconductor layer, the photoelectric conversion layer, and the first type semiconductor layer in order to form unit cells positioned on the current blocking layer and separated from each other, wherein each unit cell comprises a unit light receiving element. It provides a light receiving element array manufacturing method provided.

The forming of the separated unit cells may include forming a sidewall structure surrounding unit light receiving elements and unit light receiving elements by first patterning the second type semiconductor layer, the photoelectric conversion layer, and the first type semiconductor layer in sequence; The second patterning of the sidewall structures may include separating the unit cells by unit cells.

The method of manufacturing a light receiving element array further includes forming a protective layer on at least sidewalls of the unit light receiving elements, sidewalls of the sidewall structure, and an upper surface of the sidewall structure after forming the separated unit cells. can do.

As described above, a light receiving element array having a current blocking layer was manufactured. As a result, since the unit cells, that is, the unit light receiving element are separated from each other on the current blocking layer, it can be completely electrically separated. Therefore, it is possible to prevent the occurrence of crosstalk between the unit cells, that is, the unit photoreceptors.

In addition, by forming the current blocking layer on the general base substrate, not the semi-insulating substrate, and then forming the unit light receiving elements on the current blocking layer, it is possible to reduce the process cost together with the electrical separation between the unit light receiving elements.

With reference to the accompanying drawings, it will be described in detail a preferred embodiment of the present invention. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. Hereinafter, the same reference numerals are used for the same components in the drawings, and duplicate descriptions of the same components are omitted.

1A to 1F are schematic views illustrating a method of manufacturing a light receiving element array according to an exemplary embodiment of the present invention. FIG. 2 is a perspective view illustrating a structure of a multi-channel light receiving element array according to an embodiment of the present invention, and FIG. 1F corresponds to the cutting line I-I 'of FIG. 2.

Referring to FIG. 1A, a current blocking layer 13 may be formed on the base substrate 11. The base substrate 11 may be a compound semiconductor substrate. As an example, the base substrate 11 may be a III-V group semiconductor substrate. The III-V semiconductor substrate may be a GaAs substrate or an InP substrate.

The current blocking layer 13 may be a semi-insulating layer. The semi-insulating layer is a material layer having a high specific resistance by applying a special treatment to the compound semiconductor, and may be, for example, a compound semiconductor layer doped with impurities. Specifically, the resistance may be a C-doped GaAs layer having a value of 1 × 10 ⁷ Ω · cm or more, or an InP layer doped with Fe.

Before forming the current blocking layer 13, the buffer layer 12 may be formed on the base substrate 11. The buffer layer 12 may be a GaAs layer or an InP layer. The buffer layer 12 may be formed to minimize defects in the current blocking layer 13. However, the buffer layer 12 may be omitted.

The buffer layer 12 and the current blocking layer 13 may be formed using a crystal growth method, and the crystal growth method may be a metal organic chemical vapor deposition (MOCVD) method, a molecular beam deposition (MBE) method, or an HVPE method. (hydride or halide vapor phase epitaxy) or SVPE (sublimation vapor phase epitaxy).

Referring to FIG. 1B, a first type semiconductor layer 21 may be formed on the current blocking layer 13.

The first type semiconductor layer 21 may be a semiconductor layer to which n-type impurities are added at a high concentration, and specifically, may be a GaAs layer or an InP layer. The n-type impurity may be Si.

The photoelectric conversion layer 22 may be formed on the first type semiconductor layer 21. The photoelectric conversion layer 22 is a layer for absorbing light incident from the outside to form an electron-hole pair, wherein an intrinsic semiconductor layer or n-type impurity has a lower concentration than the first type semiconductor layer 21. The semiconductor layer may be added, and specifically, may be a GaAs layer or an InP layer.

The second type semiconductor layer 23 may be formed on the photoelectric conversion layer 22. The second type semiconductor layer 23 may be a semiconductor layer to which p-type impurities are added, and specifically, may be a GaAs layer or an InP layer. The p-type impurity may be Zn or Mg.

An ohmic contact layer 24 may be formed on the second type semiconductor layer 23. The ohmic contact layer 24 is a layer formed for ohmic contact with an electrode to be described later, but in some cases, for example, when the impurity concentration of the upper portion of the second type semiconductor layer 23 is sufficiently high, May be omitted. The ohmic contact layer 24 may be a layer doped with a higher p-type impurity than the second type semiconductor layer 23. For example, when the impurity concentration of the second type semiconductor layer 23 is 10 ¹⁸ cm ⁻³ , the impurity concentration of the ohmic contact layer 24 may be 10 ¹⁸ to 10 ²⁰ cm ⁻³ .

The first type semiconductor layer 21, the photoelectric conversion layer 22, the second type semiconductor layer 23, and the ohmic contact layer 24 may be formed using a crystal growth method, and the crystal growth method is MOCVD. Method, MBE method, HVPE method or SVPE method.

1C and 2, the ohmic contact layer 24, the second type semiconductor layer 23, and the photoelectric conversion layer 22 are first patterned to expose a portion of the first type semiconductor layer 21. Can be. In this case, a portion of the upper portion of the first type semiconductor layer 21 may also be etched. Accordingly, a plurality of unit light receiving elements 32 may be formed on the current blocking layer 13. Each unit light receiving element 32 may include a first type semiconductor layer 21, a photoelectric conversion layer 22, a second type semiconductor layer 23, and an ohmic contact layer 24.

Each unit light receiving element 32 may be surrounded by the sidewall structure 34. The sidewall structure 34 may also include a first type semiconductor layer 21, a photoelectric conversion layer 22, a second type semiconductor layer 23, and an ohmic contact layer 24.

Referring to FIG. 1D, the sidewall structures 34 may be second patterned to separate the unit cells 30. Specifically, the ohmic contact layer 24, the second type semiconductor layer 23, the photoelectric conversion layer 22, and the first type semiconductor layer 21 of the sidewall structure 34 are etched to partially expose the current blocking layer 13. Can be exposed. In this case, a portion of the upper portion of the current blocking layer 13 may also be etched.

When the buffer layer 12 is provided in the unit light receiving device 32 and the sidewall structure 34, the ohmic contact layer 24 and the second type semiconductor layer 23 of the sidewall structure 34 are photoelectric converted. A portion of the buffer layer 12 may be exposed by second patterning the layer 22, the first type semiconductor layer 21, and the current blocking layer 13. In this case, a portion of the upper portion of the buffer layer 12 may also be etched.

The unit cells 30 may include a unit light receiving element 32 and sidewall structures 34 surrounding the unit light receiving element 32. However, the present invention is not limited thereto, and the sidewall structures 34 may be omitted. Since the unit cells 30, that is, the unit light receiving elements 32 are separated from each other on the current blocking layer 13, they may be electrically separated completely. Therefore, cross talk between the unit cells 30, that is, the unit photoreceptors 32, is unlikely to occur.

On the other hand, in the related art, the unit light receiving element is electrically separated by using the substrate itself as a semi-insulating substrate made of a semi-insulating material, but the semi-insulating substrate has a disadvantage of being expensive. However, the light-receiving element array according to the embodiment of the present invention forms a current blocking layer on the general base substrate, not the semi-insulating substrate, and then forms the unit light receiving elements on the current blocking layer. Process costs can be reduced with electrical separation.

Referring to FIG. 1E, a protective layer 25 may be formed on at least sidewalls of the unit light receiving elements 30. In this case, the protective layer 25 may be formed in the exposed regions of the ohmic contact layer 24, the first type semiconductor layer 21, and the current blocking layer 13, and may be formed on the unit light receiving elements 30. When the buffer layer 12 is provided, the protective layer 25 is exposed to the buffer layer 12 in addition to the exposed regions of the ohmic contact layer 24, the first type semiconductor layer 21, and the current blocking layer 13. It can also be formed in the area.

The protective layer 25 may protect the unit light receiving elements 30 and may serve as an anti-reflection film so that light incident from the outside is not reflected.

In addition, the protective layer 25 may be formed on the sidewalls of the sidewall structure 34 and the top surface of the sidewall structure 34. Accordingly, the electrode pads and the sidewall structures 34 to be described later may be insulated. The protective layer 25 may be a SiN layer or a SiO ₂ layer.

1F and 2, each of the first electrode 26 and the second electrode 27 electrically connected to the first type semiconductor layer 21 and the ohmic contact layer 24 may be formed. In this case, the first type semiconductor layer 21 and the ohmic contact layer 24 may first etch a part of the protective layer 25 to expose the first type semiconductor layer 21 and the ohmic contact layer 24. The electrodes 26 and 27 may be connected to each other. The first etching may be dry etching or wet etching.

 The electrodes 26 and 27 may contain Au. Specifically, the electrodes 26 and 27 may be Ni / AuGe / Ti / Au, and the electrodes 27 may be Ti / Pt / Au. When the ohmic contact layer 24 is omitted, the second electrode 27 may be electrically connected to the second type semiconductor layer 23. The electrodes 26 and 27 may be formed in a ring shape using lithography.

In addition, in order to facilitate connection with an external circuit, a first electrode pad 28 and a second electrode pad 29 may be formed on the upper surface of the sidewall structure 34. The first electrode pad 28 and the second electrode pad 29 may be connected to the first electrode 26 and the second electrode 27. The first electrode pad 28 and the second electrode pad 29 may be Ti / Au.

In the light receiving element array including the current blocking layer manufactured as described above, the unit cells, that is, the unit light receiving elements may be separated from each other on the current blocking layer, and thus may be electrically separated completely. Therefore, cross talk between the unit cells, that is, the unit photoreceptors is difficult to occur.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims It can be understood that

1A to 1F are schematic views illustrating a method of manufacturing a light receiving element array according to an exemplary embodiment of the present invention.

2 is a perspective view showing the structure of a multi-channel light receiving element array according to an embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

11: base substrate 12: buffer layer

13: current blocking layer 21: first type semiconductor layer

22: photoelectric conversion layer 23: second type semiconductor layer

24: ohmic contact layer 25: protective layer

26, 27: electrode 28, 29: electrode pad

32: unit light receiving element 34: side wall structure

Claims (9)

A base substrate; A current blocking layer disposed on the base substrate; And Comprising a plurality of unit cells are spaced apart from each other on the current blocking layer, Each unit cell includes a first type semiconductor layer, a photoelectric conversion layer, and a second type semiconductor layer sequentially disposed on the current blocking layer. And a unit light receiving element to which the current blocking layer between the unit cells is exposed. The method of claim 1, And the current blocking layer is a semi-insulating layer. The method of claim 2, The semi-insulating layer is a GaAs layer or InP layer. The method of claim 1, And a protective layer disposed on at least sidewalls of the unit light receiving elements. The method of claim 1, The unit cell includes a sidewall structure surrounding the unit light receiving element. The method of claim 5, And a protective layer disposed on at least sidewalls of the unit light receiving elements, sidewalls of the sidewall structure, and an upper surface of the sidewall structure. Forming a current blocking layer on the base substrate; Forming a first type semiconductor layer, a photoelectric conversion layer, and a second type semiconductor layer on the current blocking layer in sequence; And Patterning the second semiconductor layer, the photoelectric conversion layer, and the first semiconductor layer in order to form unit cells positioned on the current blocking layer and separated from each other, wherein each unit cell includes a unit light receiving element. The light receiving element array manufacturing method. The method of claim 7, wherein The forming of the separated unit cells may include forming a sidewall structure surrounding unit light receiving elements and unit light receiving elements by first patterning the second type semiconductor layer, the photoelectric conversion layer, and the first type semiconductor layer; And And second patterning the sidewall structures and separating the sidewall structures for respective unit cells. The method of claim 8, After forming the separated unit cells, And forming a protective layer on at least sidewalls of the unit light receiving elements, sidewalls of the sidewall structure, and an upper surface of the sidewall structure.

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