KR20100067961A - Multi-channel vertical-cavity surface-emitting laser(vcsel) and its manufacture method - Google Patents

Abstract

PURPOSE: A multi-channel surface emitting laser and a manufacturing method thereof are provided to compose the surface emitting laser at a plurality of unit cells formed on one substrate by laminating a semi-insulating layer. CONSTITUTION: A buffer layer(110) and a semi-insulating layer(120) are successively laminated on an upper substrate. A plurality of unit cells is located on the semi-insulating layer. The each unit cell includes a first semiconductor layer(130), a first reflective layer(140), an active layer(150), a second reflective layer(160) and a second semiconductor layer(170). A protective layer(180) is covered on the upper part of a mesa-etched unit cell. A first electrode(192) is electrically connected to the first semiconductor layer revealed through an etching of a prescribed part of the protective layer covered on the upper side of the semiconductor layer. A second electrode(194) is electrically connected to the second semiconductor layer revealed through the etching of the prescribed part of the protective layer covered on the upper side of the second semiconductor layer.

Description

MULTI-CHANNEL VERTICAL-CAVITY SURFACE-EMITTING LASER (VCSEL) AND ITS MANUFACTURE METHOD}

The present invention relates to a multichannel surface emitting laser and a method of manufacturing the same, which implement several channels in one device.

A surface emitting laser (VCSEL) is a semiconductor comprising an underlying substrate, a distributed Bragg reflector (DBR), an active layer on which lasing occurs, and an upper reflector that can be another DBR or other type of mirror. Device, and upper and lower electrode layers are provided. An opening is provided centrally at the upper or lower electrode to admit out the light of the device produced by the active layer when electrical voltage is applied through the upper and lower electrode layers.

Surface emitting lasers have many properties that make them well suited for use in low-cost optical communication networks. And, a symmetrical circular beam emitted from the surface emitting laser structure can be easily combined in the optical fiber.

Surface-emitting lasers are small in size and are densely arranged along two dimensions on a single semiconductor wafer, and unlike other types of lasers, such as edge emittind lasers, the resonating mirror is completely within the laser in the form of a DBR. The advantage is that there is no need to mechanically or chemically create a separate, reflecting facet that behaves as if it is growing.

However, in order to implement a multi-channel surface emission laser instead of one channel, cross-talk problems occur between channels, and in order to prevent the cross-talk problem, the process cost is improved when using a semi-insulated substrate rather than a general substrate. Problem occurs.

Therefore, there is a need for a method that can produce a multi-channel surface emitting laser at low processing cost using a general substrate.

The present invention forms a semi-insulating layer on top of a substrate instead of an expensive semi-insulating substrate in order to solve the problems of the prior art, thereby forming a multi-channel surface emitting laser on one substrate, while reducing the cross-to-channel spacing. It is an object of the present invention to provide a multichannel surface emitting laser and a method of manufacturing the same, which can prevent the same.

In order to achieve the above object, in the multichannel surface emitting laser of the present invention and a method of manufacturing the same, a multi-channel surface emitting laser can be manufactured using one substrate by stacking a semi-insulating layer on a general substrate.

The present invention relates to a multi-channel surface emitting laser, including a buffer layer and a semi-insulating layer sequentially stacked on the substrate, and includes a plurality of unit cells spaced apart from each other on the top of the semi-insulating layer, Each unit cell is a protective layer applied on top of a mesa-etched unit cell so that the first semiconductor layer, the first reflection layer, the active layer, the second reflection layer, and the second semiconductor layer are sequentially stacked, and the first semiconductor layer is exposed. And a first electrode electrically connecting the first semiconductor layer exposed by etching a predetermined portion of the protective layer applied on the first semiconductor layer, the second semiconductor layer being coated on the second semiconductor layer. It may include a surface emission laser having a second electrode electrically connected to the second semiconductor layer exposed by etching a predetermined portion of the protective layer.

In the present invention, two or more of the unit cells may be filled with a dielectric material.

In the present invention, the dielectric material may be formed of polyimide or BCB.

In the present invention, the active layer may be formed by sequentially stacking SCH, quantum well layer, and SCH oxide layer.

In addition, the present invention relates to a method for manufacturing a multi-channel surface emission laser, comprising the steps of sequentially stacking a substrate, a buffer layer, a semi-insulating layer, a first semiconductor layer, a first reflection layer, an active layer, a second reflection layer, and a second semiconductor layer And forming a unit cell through mesa etching, and forming a groove by performing mesa etching on the formed unit cell. And depositing a protective layer on an upper portion of the unit cell in which the mesa etching is performed, etching a predetermined portion of the lower surface of the groove to expose the first semiconductor layer, and attaching the first electrode pad to the etched portion. And forming a portion of the protective layer stacked on the second semiconductor layer, and forming the etched portion of the second electrode pad.

After forming the second electrode pad in the present invention, the method may further include filling a dielectric material in the grooves and side surfaces of the unit cells.

In addition, the present invention relates to a method for manufacturing a multi-channel surface emission laser, comprising the steps of sequentially stacking a substrate, a buffer layer, a semi-insulating layer, a first semiconductor layer, a first reflection layer, an active layer, a second reflection layer, and a second semiconductor layer. And forming a unit cell through mesa etching, and forming a groove in the formed unit cell, and laminating a passivation layer on the mesa-etched unit cell. And filling a dielectric material in the side surface and the groove of the unit cell in which the mesa etching is performed, and etching a predetermined portion of the lower surface of the groove filled with the dielectric material to expose the first semiconductor layer. And forming a first electrode pad on the etched portion, and etching a predetermined portion of the protective layer stacked on the second semiconductor layer, and forming the etched portion second electrode pad. have.

The present invention has the effect of forming a multi-channel surface emission laser by forming a plurality of unit cells on one substrate by stacking a semi-insulating layer during epitaxial growth, and by configuring a surface emission laser for each unit cell.

In addition, as a multi-channel surface emitting laser is manufactured by stacking semi-insulating layers without using an expensive semi-insulating substrate, the cross-talk phenomenon that may be formed between channels is prevented, and the gap between the channels is reduced to reduce the manufacturing process and manufacturing process. This has the effect of producing high performance multichannel surface emitting lasers with improved performance while reducing costs.

Preferred embodiments of the invention will be described with reference to the accompanying drawings. In adding reference numerals to components of the following drawings, it is determined that the same components have the same reference numerals as much as possible even if displayed on different drawings, and it is determined that they may unnecessarily obscure the subject matter of the present invention. Detailed descriptions of well-known functions and configurations will be omitted.

1A to 1F illustrate a method of manufacturing a multi-channel surface emitting laser according to an embodiment of the present invention.

Referring to FIG. 1A, the substrate 100, the buffer layer 110, the semi-insulating layer 120, the first semiconductor layer 130, the first reflection layer 140, the active layer 150, the second reflection layer 160, And a second semiconductor layer 170 are sequentially stacked.

The substrate 100 may be a compound semiconductor substrate instead of an expensive semi-insulating substrate, but is not limited thereto. It is preferable to use a III-V semiconductor substrate such as a gallium arsenide (GaAs) substrate or an indium phosphorus (InP) substrate. Do.

The buffer layer 110 may be stacked on the substrate 100 to be formed of gallium arsenide (GaAs) or indium phosphorus (InP), and may be omitted according to a user's selection.

The semi-insulating layer 120 is semi-insulated on top of the substrate 100 or the buffer layer 110 during the epitaxial growth process by using a general substrate instead of an expensive semi-insulating substrate to form several channel surface emitting lasers on a single substrate. Stacking layers 120 has the effect of reducing cross-talk between channels.

In this case, the semi-insulating layer 120 uses a metal organic chemical vapor deposition (MOCVD) method, a molecular beam deposition (MBE) method, a hydride or halide vapor phase epitaxy (HVPE) method, or a sublimation vapor phase epitaxy (SVPE) method. By laminating.

The first semiconductor layer 130 is stacked on top of the semi-insulating layer 120 and formed of a semiconductor layer to which n-type impurities are added. The second semiconductor layer 170 is a different impurity p from the first semiconductor layer 130. It is formed of a semiconductor layer to which type impurities are added.

The first reflection layer 140 is a distributed Bragg reflector to which the same impurities as the first semiconductor layer 130 is added, and may be formed as a multilayer mirror pair, and the second reflection layer 160 may be formed of the second semiconductor. The distributed Bragg reflector to which the same impurities as the layer 170 are added is formed in the same form as the first reflective layer 140.

In the first reflection layer 140 and the second reflection layer 160 formed of a plurality of mirror pairs, light injected therein is reciprocally amplified between the mirrors, and the first reflection layer 140 has a high doping level with the second reflection layer 160. The emission wavelength of the light is controlled by forming differently as much as possible to generate a difference in refractive index.

The active layer 150 is a region emitting light passing through the first and second reflection layers 140 and 160 and may be formed in a single layer or multiple layers. In the present invention, the SCH layer 152 and the quantum well layer 154 may be formed. ) And the SCH + oxide layer 156 are sequentially stacked.

Referring to FIG. 1B, one or more unit cells are formed on one substrate to implement devices of multiple channels.

The unit cell is formed by etching the epitaxially grown device in FIG. 1A to form a plurality of unit cells on one substrate.

In addition, a semi-insulating layer during unit cell etching to prevent cross-talk between channels, which may be generated by forming a plurality of unit cells, that is, multi-channel surface emission lasers, on one substrate 100. It is formed by etching up to 130.

In this case, a predetermined portion (upper part) of the semi-insulating layer 130 may also be etched, and the buffer layer 110 exposed by etching the semi-insulating layer 130 may also be etched in a predetermined portion (upper part).

Referring to FIG. 1C, in order to form a surface emitting laser in each unit cell, mesa etching is performed to form grooves A and B (three mesa pillars on a cross section). Figure 1c is a cross-sectional view showing that two of the grooves are formed, but shows one groove that is connected by etched round (see Figure 3)

In addition, the grooves A and B are etched to expose a portion of the first semiconductor layer 130 so that the grooves A and B may be electrically connected to the first semiconductor layer 130 through an electrode pad.

In the present invention, grooves are formed in each unit cell after etching to form unit cells, but the order of the two processes may be changed.

Referring to FIG. 1D, a protective film 180 is generally stacked on an upper surface of the device formed in FIG. 1C. Referring to FIG. 1E, a predetermined portion of the stacked protective film 180 is etched to form an electrode pad. In this case, the etching of the protective film may use a wet etching method or a dry etching method.

The passivation layer 180 serves as an anti-reflection film so that the light inside the device is not reflected to the outside, and induces insulation between the electrode pad and the mesa side formed by the mesa etching (etch for forming the groove) in the unit cell. In addition, the protective layer 180 may be formed of a silicon nitride (SiN) layer or a silicon oxide (SiO ₂ ) layer.

In more detail, the etching of the passivation layer 180 for forming the electrode pad of FIG. 1E may expose a portion of the first semiconductor layer 130 by etching the lower surfaces of the grooves A and B, and thus, the grooves B may be exposed. The upper surface of the mesa pillar formed by etching is etched to expose a portion of the second semiconductor layer 170.

At this time, the upper surface of the mesa pillar is etched at once in a circular shape (see FIG. 3) as the second electrode pad is formed later, and when the cross section is shown in FIG. 1E, the protective layer 180 is also in cross-sectional view (FIG. 1e) It appears to be etched into the trench structure.

Referring to FIG. 1F, an electrode pad is formed in a portion where the passivation layer 180 is etched in FIG. 1E.

In more detail, the first electrode 192 is formed on the first semiconductor layer 130 partially exposed on the lower surfaces of the grooves A and B to form the first electrode pad 193 and the first semiconductor layer 130. Connect electrically.

The first electrode 192 represents an n-type electrode including gold (Au) in the present invention. For example, the first electrode 192 may be formed of Ti / Pt / Au or Pt / Ti / Pt / Au.

In addition, in FIG. 1E, the second electrode 194 is formed on the second semiconductor layer 170 exposed by the passivation layer 180 etched in the trench structure on the mesa pillar, thereby forming the second electrode pad 195 and the second electrode. The semiconductor layer 170 is electrically connected.

Referring to FIG. 1G, a multi-channel surface emitting laser may be formed by only FIG. 1F, but a groove for dividing each unit cell and a mesa etching in the unit cell may be formed in order to improve insulation between respective channels. The dielectric material 200 is filled.

The dielectric material 200 may be formed of, but not limited to, polyimide or benzocyclobutene (BCB).

2A to 2C are views illustrating a method for manufacturing a multi-channel surface emitting laser according to another embodiment of the present invention.

Referring to FIG. 2A, the dielectric material 200 is filled in the side surfaces of the grooves and unit cells formed after the processes of FIGS. 1A to 1D.

Referring to FIG. 2B, a portion of the groove filled with the dielectric material 200 is etched to expose a portion of the first semiconductor layer 130, and an upper portion of the mesa pillar is exposed to expose a portion of the second semiconductor layer 170. A predetermined portion of the passivation layer 180 formed on the surface is etched.

Referring to FIG. 2C, the first electrode 192 is formed on the first semiconductor layer 130 etched and exposed in FIG. 2B, and the second electrode 194 is formed on the second semiconductor layer 170. Form.

2A to 2C show the same multi-channel surface emitting laser as in FIGS. 1A to 1G, but show different order of filling of the dielectric material 200 in the manufacturing method.

3A and 3B are views illustrating a multi-channel surface emitting laser according to an embodiment of the present invention.

Referring to FIG. 3A, a multi-channel surface emitting laser formed by FIGS. 1A to 1F is illustrated, and the drawings (FIGS. 1A to 1F) are cross-sectional views taken along the line AA ′ of FIG. 3A.

Referring to FIG. 3B, a multi-channel surface emitting laser formed by FIGS. 2A to 2C is illustrated, and the drawings (FIGS. 2A to 2C) show a cross section taken along line B-B 'in FIG. 3B.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "having" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art, and are not construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

Those skilled in the art can change or modify the described embodiments without departing from the scope of the present invention, and such changes or modifications are within the scope of the present invention. In addition, the materials of each component described herein can be readily selected and coped by a variety of materials known to those skilled in the art. In addition, those skilled in the art may omit some of the components described herein without adding to the performance or add the components to improve performance. In addition, those skilled in the art may change the order of the method steps described herein depending on the process environment or equipment. Therefore, the scope of the present invention should be determined by the appended claims and equivalents thereof, not by the embodiments described.

1A to 1F illustrate a method of manufacturing a multi-channel surface emitting laser according to an embodiment of the present invention.

2A to 2C illustrate a method of manufacturing a multi-channel surface emitting laser according to another embodiment of the present invention.

3A and 3B illustrate a multi-channel surface emitting laser in accordance with one embodiment of the present invention.

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

100 substrate 110 buffer layer

120: semi-insulating layer 130: first semiconductor layer

140: first reflective layer 150: active layer

152: SCH layer 154: quantum well layer (MQW)

156: SCH + oxide layer 160: second reflection layer

170: second semiconductor layer 180: protective film

192: first electrode 193: first electrode pad

194: second electrode 195: second electrode pad

200: dielectric material

Claims (6)

A buffer layer and a semi-insulating layer sequentially stacked on the substrate; It includes a plurality of unit cells spaced apart from each other on top of the semi-insulating layer, Each unit cell is a protective layer is applied on top of the mesa-etched unit cell so that the first semiconductor layer, the first reflection layer, the active layer, the second reflection layer, and the second semiconductor layer are sequentially stacked, and the first semiconductor layer is exposed. layer; A first electrode electrically connecting the first semiconductor layer exposed by etching a predetermined portion of the protective layer applied on the first semiconductor layer; And And a second electrode electrically connecting the second semiconductor layer exposed by etching a predetermined portion of the protective layer applied on the second semiconductor layer. 2. The multi-channel surface emitting laser of claim 1, wherein a gap between two or more of said unit cells is filled with a dielectric material. 3. The multichannel surface emission laser of claim 2, wherein the dielectric material is polyimide or BCB. Sequentially stacking a substrate, a buffer layer, a semi-insulating layer, a first semiconductor layer, a first reflection layer, an active layer, a second reflection layer, and a second semiconductor layer; Performing mesa etching to expose the buffer layer or semi-insulating layer to form at least one unit cell; Forming a groove by performing mesa etching on each of the unit cells; Stacking a protective layer on an upper portion of the unit cell in which the mesa etching is performed; Etching a predetermined portion of the lower surface of the groove to expose a first semiconductor layer, and forming a first electrode on the etched portion; And Etching a predetermined portion of the passivation layer stacked on the second semiconductor layer, and forming the etched portion second electrode; Multi-channel surface emission laser manufacturing method comprising a. 5. The method of claim 4, further comprising filling a dielectric material on the sides of the grooves and unit cells after forming the second electrode. Sequentially stacking a substrate, a buffer layer, a semi-insulating layer, a first semiconductor layer, a first reflection layer, an active layer, a second reflection layer, and a second semiconductor layer; Performing mesa etching to expose the buffer layer or the semi-insulating layer to form at least one unit cell, and forming a groove in each of the formed unit cells; Stacking a protective layer on an upper portion of the unit cell in which the mesa etching is performed; Filling a dielectric material into a side surface of the unit cell in which the mesa etching is performed and the groove; Etching a predetermined portion of the dielectric material filled in the grooves and a protective film formed on the lower surface of the dielectric material filled in the grooves to expose a first semiconductor layer, and forming a first electrode on the etched portions; And Etching a predetermined portion of the passivation layer stacked on the second semiconductor layer, and forming the etched portion second electrode; Multi-channel surface emission laser manufacturing method comprising a.

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