VCSEL Laser and Its Fabrication Method

Abstract

A VCSEL laser is disclosed, comprising: a substrate, an N-DBR layer formed on the substrate, an active region formed on the N-DBR layer, a P-type semiconductor structure formed on the active region, and a growth confinement layer formed on the active region by an epitaxial growth process. Among them, the P-type semiconductor structure is surrounded by the growth confinement layer, and the growth confinement layer is used to allow free carriers to flow into the P-type semiconductor structure. A metal fusion layer is formed on the upper surfaces of the P-type semiconductor structure and the growth confinement layer, and a conductive substrate is formed on the metal fusion layer. In addition, a positive electrode electrically connected to the conductive substrate and a negative electrode electrically connected to the substrate are provided. Among them, the negative electrode forms a light-emitting hole corresponding to the P-type semiconductor structure.

Description

Technical Field

[0001] This application relates to the field of semiconductors, and more particularly to VCSEL lasers and their manufacturing methods. Background Art

[0002] A VCSEL laser (Vertical-Cavity Surface-Emitting Laser) is a semiconductor laser whose laser beam emits perpendicular to the top or bottom surface. Compared with traditional edge-emitting semiconductor lasers, it has characteristics such as high fiber coupling efficiency, low power consumption, small temperature drift, small size, easy integration and packaging.

[0003] In recent years, VCSEL lasers have been widely used in fields such as distance sensing and optical communication. For example, a VCSEL laser is used as a pulsed light source in the autonomous driving system of a vehicle to sense the distance information between the target object and the vehicle. Since the sensing distance of a VCSEL laser is achieved by increasing its luminous power, when the VCSEL laser is applied to long-distance sensing applications, it requires a relatively high luminous power.

[0004] For existing VCSEL lasers, in long-distance sensing applications, it is necessary to increase the current density to increase the luminous power of the VCSEL laser. However, limited by the structure of existing VCSEL lasers, the heat accumulation caused by high current density will cause a decrease in the photoelectric conversion efficiency, which in turn leads to a decrease in the luminous power of the VCSEL laser. That is, for existing VCSEL lasers, limited by their structure, it is difficult to obtain a relatively high luminous power, resulting in difficulty in being applied in the field of long-distance sensing.

[0005] Therefore, a new type of VCSEL laser adapted to long-distance sensing applications is needed. Summary of the Invention

[0006] One advantage of this application is to provide a VCSEL laser and its manufacturing method, wherein the VCSEL laser has a novel semiconductor structure, so that it still has a relatively high photoelectric conversion efficiency under the drive of a relatively high current density. Therefore, the VCSEL laser can have a relatively high luminous power and can be suitably applied to long-distance sensing applications.

[0007] Another advantage of the present application is to provide a VCSEL laser and a manufacturing method thereof. Among them, the VCSEL laser forms a growth barrier layer for current confinement around its P-type semiconductor structure through an epitaxial growth process to replace the existing oxidation confinement layer, so as to reduce the heat accumulation caused by the free carrier absorption effect through the growth confinement layer. That is, the VCSEL laser adopts a new current confinement structure to reduce the heat accumulation during its operation, so that it can still have a relatively high photoelectric conversion efficiency under the drive of a relatively high current density.

[0008] Another advantage of the present application is to provide a VCSEL laser and a manufacturing method thereof. Among them, the growth confinement layer formed around the P-type semiconductor structure can repair the lattice broken bonds on the outer peripheral wall of the P-type semiconductor structure to reduce the surface free carrier recombination effect on the outer peripheral wall. In this way, the VCSEL laser has a relatively high photoelectric conversion efficiency.

[0009] Another advantage of the present application is to provide a VCSEL laser and a manufacturing method thereof. Among them, the growth confinement layer formed around the P-type semiconductor structure increases the heat dissipation area of the VCSEL laser, thereby reducing the heat accumulation around the light-emitting active region and avoiding the decrease of the optical power and the photoelectric conversion efficiency caused by heat.

[0010] In order to achieve at least one of the above advantages or other advantages and purposes, according to one aspect of the present application, a VCSEL laser is provided, which includes:

[0011] A substrate;

[0012] An N-DBR layer formed on the substrate;

[0013] An active region formed on the N-DBR layer;

[0014] A P-type semiconductor structure formed on the active region;

[0015] A growth confinement layer formed on the active region by an epitaxial growth process, wherein the P-type semiconductor structure is surrounded by the growth confinement layer, and the growth confinement layer is used to allow free carriers to flow into the P-type semiconductor structure;

[0016] A metal fusion layer formed on the upper surfaces of the P-type semiconductor structure and the growth confinement layer;

[0017] A conductive substrate formed on the metal fusion layer; and

[0018] A positive electrode electrically connected to the conductive substrate and a negative electrode electrically connected to the substrate, wherein the negative electrode forms a light-emitting hole corresponding to the P-type semiconductor structure.

[0019] In the VCSEL laser according to the present application, the P-type semiconductor structure includes a P-DBR layer formed in the active region and a P-type ohmic contact semiconductor layer formed on the P-DBR layer, wherein the upper surface of the P-type ohmic contact semiconductor layer forms the upper surface of the P-type semiconductor structure.

[0020] In the VCSEL laser according to the present application, the P-type ohmic contact semiconductor layer is made of P-GaAs or P-InGaAs material.

[0021] In the VCSEL laser according to the present application, the growth limiting layer has the same height as the P-type semiconductor structure, and the upper surface of the growth limiting layer is flush with the upper surface of the P-type semiconductor structure.

[0022] In the VCSEL laser according to the present application, the growth limiting layer is circumferentially bonded to the outer peripheral surface of the P-type semiconductor structure.

[0023] In the VCSEL laser according to the present application, the material of the growth limiting layer is N-GaAs.

[0024] In the VCSEL laser according to the present application, the metal fusion layer includes a first ohmic contact metal layer formed on the upper surfaces of the P-type semiconductor structure and the growth limiting layer, and a first metal conductive layer formed on the first ohmic contact metal layer.

[0025] In the VCSEL laser according to the present application, the material of the first metal conductive layer is selected from one of the following materials: Au, Pt, Al, and Cu.

[0026] In the VCSEL laser according to the present application, the conductive substrate includes a substrate layer and a bonding layer formed on the lower surface of the substrate layer, and the bonding layer is bonded to the first metal conductive layer.

[0027] In the VCSEL laser according to the present application, the bonding layer includes a second ohmic contact metal layer formed on the lower surface of the substrate layer and a second metal conductive layer formed on the lower surface of the second ohmic contact metal layer.

[0028] In the VCSEL laser according to the present application, the material of the second metal conductive layer is the same as that of the first metal conductive layer.

[0029] In the VCSEL laser according to the present application, the substrate layer is selected from one of the following: a metal layer and a semiconductor layer.

[0030] In the VCSEL laser according to the present application, the semiconductor layer is a P-type silicon crystal layer.

[0031] In the VCSEL laser according to the present application, the semiconductor layer is a P-GaAs layer.

[0032] In the VCSEL laser according to the present application, the thickness of the substrate layer ranges from 50 μm to 200 μm.

[0033] In the VCSEL laser according to the present application, the substrate is an N-GaAs layer, and the thickness dimension of the substrate ranges from 5 μm to 20 μm.

[0034] In the VCSEL laser according to the present application, the diameter of the P-type semiconductor structure ranges from 8 μm to 15 μm.

[0035] In the VCSEL laser according to the present application, the diameter of the light-emitting hole ranges from 10 μm to 50 μm.

[0036] According to another aspect of the present application, there is also provided a method for manufacturing a VCSEL laser, which includes:

[0037] Form an epitaxial structure through an epitaxial growth process, wherein the epitaxial structure includes, from bottom to top: a substrate, an N-DBR layer, an active region, a P-DBR layer, and a P-type ohmic contact semiconductor layer;

[0038] Etch at least a part of the P-DBR layer and the electrical contact region to form a P-type semiconductor structure;

[0039] Form a growth confinement layer on the active region through an epitaxial growth process, wherein the growth confinement layer surrounds the P-type semiconductor structure, and the growth confinement layer is used to allow free carriers to flow into the P-type semiconductor structure;

[0040] Form a metal fusion layer on the upper surface of the P-type semiconductor structure through an electroplating process;

[0041] Bond a conductive substrate to the metal fusion layer through a bonding process;

[0042] Remove at least a part of the substrate to reduce the thickness dimension of the substrate;

[0043] Form a negative electrode on the lower surface of the substrate, wherein the negative electrode forms a light-emitting hole corresponding to the P-type semiconductor structure; and

[0044] Form a positive electrode on the conductive substrate.

[0045] In the method for preparing a VCSEL laser according to the present application, the P-type semiconductor structure includes a P-DBR layer formed in the active region and a P-type ohmic contact semiconductor layer formed in the P-DBR layer, wherein the upper surface of the P-type ohmic contact semiconductor layer forms the upper surface of the P-type semiconductor structure.

[0046] In the method for manufacturing a VCSEL laser according to the present application, a metal fusion layer is formed on the upper surface of the P-type semiconductor structure by an electroplating process, comprising:

[0047] forming a first ohmic contact metal layer on the upper surfaces of the P-type semiconductor structure and the growth restriction layer by an electroplating process; and

[0048] A first metal conductive layer is formed on the upper surface of the first ohmic contact metal layer through an electroplating process.

[0049] In the preparation method of the VCSEL laser according to the present application, a conductive substrate is bonded to the metal fusion layer through a bonding process, including: providing a substrate layer; forming a second ohmic contact metal layer on the lower surface of the substrate layer through an electroplating process; forming a second metal contact layer on the lower surface of the second ohmic contact metal layer through an electroplating process to form the conductive substrate; and bonding the second metal contact layer of the conductive substrate to the first metal conductive layer to bond the conductive substrate to the metal fusion layer.

[0050] Further objectives and advantages of the present application will be fully apparent through understanding of the following description and drawings.

[0051] These and other objects, features and advantages of the present application are fully reflected in the following detailed description, drawings and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 The figure shows a schematic diagram of an existing VCSEL laser.

[0053] Figure 2 FIG2 shows a schematic diagram of a VCSEL laser according to an embodiment of the present application.

[0054] Figure 3 FIG2 is a schematic diagram showing a modified implementation of the VCSEL laser according to an embodiment of the present application.

[0055] Figure 4 The figure shows a flow chart of the method for preparing the VCSEL laser according to an embodiment of the present application.

[0056] Figure 5A FIG2 shows one of the schematic diagrams of the preparation process of the VCSEL laser according to an embodiment of the present application.

[0057] Figure 5B Figure 2 shows the second schematic diagram of the manufacturing process of the VCSEL laser according to an embodiment of the present application.

[0058] Figure 5C Figure 3 shows the third schematic diagram of the manufacturing process of the VCSEL laser according to an embodiment of the present application. Detailed implementation manners

[0059] The following description is used to disclose the present application so that those skilled in the art can implement the present application. The embodiments described below are only examples, and those skilled in the art can think of other obvious variations. The basic principles defined in the following description can be applied to other implementation manners, variations, improvements, equivalent manners, and other technical solutions that do not depart from the spirit and scope of the present application.

[0060] It can be understood that the term "a" should be understood as "at least one" or "one or more". That is, in one embodiment, the number of an element can be one, while in other embodiments, the number of the element can be multiple. The term "a" cannot be understood as a limitation on the number.

[0061] Although ordinal numbers such as "first", "second", etc. will be used to describe various components, those components are not limited herein. The term is only used to distinguish one component from another. For example, the first component can be called the second component, and similarly, the second component can also be called the first component without departing from the teachings of the inventive concept. The term "and / or" used herein includes any and all combinations of one or more of the associated listed items.

[0062] The terms used herein are for the purpose of describing various embodiments only and are not intended to be limiting. As used herein, the singular forms are also intended to include the plural forms unless the context clearly indicates otherwise. Additionally, it will be understood that the terms "comprises" and / or "has" when used in this specification specify the presence of the stated features, numbers, steps, operations, components, elements, or combinations thereof, without excluding the presence or addition of one or more other features, numbers, steps, operations, components, elements, or groups thereof.

[0063] Overview of the Application

[0064] As mentioned above, in recent years, VCSEL lasers have been widely used in fields such as distance sensing and optical communication. For example, VCSEL lasers are used as pulsed light sources in the autonomous driving systems of vehicles, where they are used to sense the distance information between the target object and the vehicle. The luminous power of the VCSEL laser is an important parameter affecting the ranging range. Specifically, the ranging range of the VCSEL laser increases with the increase in the luminous power of the VCSEL laser. Therefore, when the VCSEL laser is applied to long-distance sensing applications, it requires a higher luminous power.

[0065] For existing VCSEL lasers, in long-distance sensing applications, it is necessary to increase the current density to increase the luminous power of the VCSEL laser. However, limited by the structure of the existing VCSEL lasers, the heat accumulation caused by the high current density will cause a decrease in the photoelectric conversion efficiency and then lead to a decrease in the luminous power of the VCSEL laser. That is, for existing VCSEL lasers, limited by their structure, it is difficult to obtain a high luminous power, resulting in their difficulty in being applied in the field of long-distance sensing.

[0066] Specifically, Figure 1 The figure shows a schematic diagram of an existing VCSEL laser. As Figure 1 shown, in the existing VCSEL laser, at least a part of the P-DRB layer is oxidized through an oxidation process (for example, a wet oxidation process) to form a non-conductive oxidation confinement layer 10P above the active region, so as to define the light-emitting aperture through the oxidation confinement layer 10P. However, the oxidation confinement layer formed through the oxidation process has many effects on the performance of the VCSEL laser.

[0067] First, during the operation of the VCSEL laser, due to the existence of the oxidation confinement layer, free carriers will have an absorption effect near the oxidation confinement layer, resulting in heat accumulation, which reduces the photoelectric conversion efficiency of the VCSEL laser.

[0068] Second, since the P-DBR is formed by alternately arranged high-aluminum layers and low-aluminum layers, during the oxidation of the P-DBR through the wet oxidation process, the high-aluminum layer and the low-aluminum layer with different aluminum contents have different etching rates. Therefore, after the oxidation confinement layer is formed, it will cause uneven internal stress of the P-DBR and / or lattice defects at the material structure interface. And heat accumulation will exacerbate the lattice defects. That is, when the power of the VCSEL laser is high, more heat accumulation will lead to an increase in the failure probability of the VCSEL laser.

[0069] In view of the above technical problems, the inventors of the present application have designed a VCSEL laser with a novel semiconductor structure, which can still have a relatively high photoelectric conversion efficiency under the drive of a relatively high current density, so that the VCSEL laser can have a relatively high luminous power and be suitably applied to long-distance sensing applications. Specifically, the VCSEL laser forms a growth barrier layer for current confinement around its P-type semiconductor structure through an epitaxial growth process to replace the existing oxidation confinement layer.

[0070] Based on this, the present application provides a VCSEL laser, which includes: a substrate; an N-DBR layer formed on the substrate; an active region formed on the N-DBR layer; a P-type semiconductor structure formed on the active region; a growth confinement layer formed on the active region through an epitaxial growth process, wherein the P-type semiconductor structure is surrounded by the growth confinement layer, and the growth confinement layer is used to allow free carriers to flow into the P-type semiconductor structure; a metal fusion layer formed on the upper surfaces of the P-type semiconductor structure and the growth confinement layer; a conductive substrate formed on the metal fusion layer; and a positive electrode electrically connected to the conductive substrate and a negative electrode electrically connected to the substrate, wherein the negative electrode forms a light-emitting hole corresponding to the P-type semiconductor structure.

[0071] Moreover, the present application also provides a method for manufacturing a VCSEL laser, which includes the steps of: forming an epitaxial structure through an epitaxial growth process, the epitaxial structure including, from bottom to top: a substrate, an N-DBR layer, an active region, a P-DBR layer, and a P-type ohmic contact semiconductor layer; etching at least a part of the P-DBR layer and the electrical contact region to form a P-type semiconductor structure; forming a growth confinement layer on the active region through an epitaxial growth process, wherein the growth confinement layer surrounds the P-type semiconductor structure, and the growth confinement layer is used to allow free carriers to flow into the P-type semiconductor structure; forming a metal fusion layer on the upper surface of the P-type semiconductor structure through an electroplating process; bonding a conductive substrate to the metal fusion layer through a bonding process; removing at least a part of the substrate to reduce the thickness dimension of the substrate; forming a negative electrode on the lower surface of the substrate, wherein the negative electrode forms a light-emitting hole corresponding to the P-type semiconductor structure; and forming a positive electrode on the conductive substrate.

[0072] After introducing the basic principle of the present application, various non-limiting embodiments of the present application will be specifically introduced below with reference to the accompanying drawings.

[0073] Exemplary VCSEL Laser

[0074] As Figure 2As shown, a VCSEL laser according to an embodiment of the present application is illustrated, which includes a semiconductor structure 10, a growth confinement layer 20, a metal fusion layer 30, a conductive substrate 40, a positive electrode 50, and a negative electrode 60. Accordingly, as Figure 2 shown, in the embodiment of the present application, the semiconductor structure 10 includes, from bottom to top: a substrate 11, an N-DBR layer 12, an active region 13, and a P-type semiconductor structure 14. Among them, the P-type semiconductor structure 14 includes a P-DBR layer 141 formed on the active region 13 and a P-type ohmic contact semiconductor layer 142 formed on the P-DBR layer 141. The growth confinement layer 20 is formed around the P-type semiconductor structure 14 of the semiconductor structure 10 through an epitaxial growth process. The metal fusion layer 30 is electrically connected to and stacked on the growth confinement layer 20 and the P-type semiconductor structure 14. The conductive substrate layer 40 is stacked on the metal fusion layer 30. The positive electrode 50 is electrically connected to the conductive substrate 40; the negative electrode 60 is electrically connected to the substrate 11.

[0075] Specifically, in the embodiment of the present application, the substrate 11 may include, but is not limited to, a silicon substrate, a sapphire substrate, a gallium arsenide substrate, etc. In this embodiment, the substrate 11 is implemented as an N-type doped gallium arsenide substrate (i.e., an N-GaAs substrate). The N-DRB layer 12 is formed on the substrate 11 through an epitaxial growth process. Among them, the N-DRB layer 12 is formed by an alternating layer of N-type doped AlGaAs with a high aluminum content and N-type doped AlGaAs with a low aluminum content. Among them, the AlGaAs with a high aluminum content and the AlGaAs with a low aluminum content have different refractive indexes to form an N-type distributed Bragg reflector (N-Distributed Bragg Reflector: N-DBR). In this embodiment, the P-DBR layer 141 of the P-type semiconductor structure 14 is grown through an epitaxial growth process, which is formed by an alternating layer of P-type doped AlGaAs with a high aluminum content and N-type doped AlGaAs with a low aluminum content. Among them, the AlGaAs with a high aluminum content and the AlGaAs with a low aluminum content have different refractive indexes to form a P-type distributed Bragg reflector (P-Distributed Bragg Reflector: P-DBR). In this embodiment, the P-type ohmic contact semiconductor layer 142 of the P-type semiconductor structure 14 is a P-type doped gallium arsenide layer or an indium gallium arsenide layer, that is, a P-GaAs layer or a P-lnGaAs, which can be formed on the upper surface of the P-DBR layer 141 through an epitaxial growth process.

[0076] As Figure 2As shown, in the embodiment of the present application, the active region 13 is set between the first semiconductor region forming the N-DBR layer 12 and the second semiconductor region forming the P-DBR layer 141. The active region 13 includes quantum wells, which can be made of AlInGaAs (e.g., AlInGaAs, GaAs, AlGaAs, and InGaAs), InGaAsP (e.g., InGaAsP, GaAs, InGaAs, GaAsP, and GaP), GaAsSb (e.g., GaAsSb, GaAs, and GaSb), InGaAsN (e.g., InGaAsN, GaAs, InGaAs, GaAsN, and GaN), or AlInGaAsP (e.g., AlInGaAsP, AlInGaAs, AlGaAs, InGaAs, InGaAsP, GaAs, InGaAs, GaAsP, and GaP). The active region 14A can also be made of other compositions for forming quantum well layers. That is, the active region 13 is sandwiched in the resonant cavity formed by the N-DBR layer and the P-DBR layer.

[0077] During operation, after current is injected into the active region 14, population inversion exists in the active region 04, such that when the gain provided by the laser medium is sufficient to exceed the loss, the light intensity will continuously increase. Thus, electrons at the bottom of the conduction band in the high-energy state transition to the low energy band. In this way, as light of a specific wavelength reflects back and forth in the resonant cavity formed by the P-DBR layer 141 and the N-DBR layer 12, the amplification process is continuously repeated, and laser light is formed.

[0078] In order to enable free carriers (also known as free charge carriers) to flow into the active region 13 through the P-type semiconductor structure 14 in a concentrated manner, in the embodiment of the present application, the VCSEL further includes a growth confinement layer 20 formed on the active region 13 by an epitaxial growth process, and the P-type semiconductor structure 14 is surrounded by the growth confinement layer 20. That is, the VCSEL forms a growth barrier layer 20 for current confinement around its P-type semiconductor structure 14 by an epitaxial growth process to replace the existing oxidation confinement layer.

[0079] It should be noted that in the embodiment of the present application, the growth limiting layer 20 has the same height as the P-type semiconductor structure 14, and the upper surface of the growth limiting layer 20 is flush with the upper surface of the P-type semiconductor structure. That is, in the embodiment of the present application, the growth limiting layer 20 is circumferentially bonded to the entire outer peripheral wall of the P-type semiconductor structure 14. In this way, the heat dissipation volume is increased, and the heat accumulation caused by the free carrier absorption effect is reduced, so that when the VCSEL laser operates under high current density conditions, a high photoelectric conversion efficiency and luminous power can be maintained, which is beneficial to its realization of long-distance detection.

[0080] Moreover, the growth limiting layer 20 formed around the P-type semiconductor structure 14 can repair the lattice broken bonds on the outer peripheral wall of the P-type semiconductor structure 14 to reduce the surface free carrier recombination effect on the outer peripheral wall. In this way, the VCSEL laser has a relatively high photoelectric conversion efficiency.

[0081] In a specific example of the present application, the material of the growth limiting layer 20 is N-type doped gallium arsenide, that is, the growth limiting layer is an N-GaAs layer. Preferably, the growth limiting layer is a low N-doped gallium arsenide layer.

[0082] Furthermore, since the growth limiting layer 20 has the same height as the P-type semiconductor structure 14 and the upper surface of the growth limiting layer 20 is flush with the upper surface of the P-type semiconductor structure, an installation plane is formed by the upper surface of the growth limiting layer 20 and the upper surface of the P-type semiconductor structure. Correspondingly, the metal fusion layer 30 can be formed on the installation plane in a stacked manner to simplify the manufacturing process and save costs.

[0083] More specifically, as Figure 2 shown, the metal fusion layer 30 includes a first ohmic contact metal layer 31 formed on the installation plane by an electroplating process, and a first metal conductive layer 32 formed on the first ohmic contact metal layer 31 by an electroplating process. The first ohmic contact metal layer 31 is made of a P-type doped ohmic contact metal, such as Ti, Pt, Au, W, or made of an alloy material, such as a TiPt alloy, etc. The material of the first metal conductive layer 32 is selected from one of the following materials: Au (gold), Pt (platinum), Al (aluminum), and Cu (copper). In this embodiment, metal Au is selected as the material of the first metal conductive layer 32.

[0084] It should be noted that in this embodiment, the first ohmic contact metal layer 31 is a metal material and the growth restriction layer 20 is a semiconductor material. Therefore, when the first ohmic contact metal layer 31 is superimposed on the growth restriction layer 20, a Schottky barrier is formed between the first ohmic contact metal layer 31 and the growth restriction layer 20, so that the working current cannot flow into the growth restriction layer 20 and is guided to flow into the P-type semiconductor structure 14.

[0085] It is worth mentioning that in the embodiment of the present application, the metal fusion layer 30 stacked on the P-type semiconductor structure 14 and the growth restriction layer 20 is made of a metal material. Therefore, when the heat source accumulates in the P-type semiconductor structure 14 and the active area 13, the metal fusion layer 30 can act as a heat-conducting element to guide the accumulated heat to the outside. That is, the metal fusion layer 30 can achieve heat conduction and facilitate heat dissipation, thereby reducing the heat accumulation generated when the VCSEL laser operates under high current density conditions, improving the photoelectric conversion efficiency, and thereby increasing the luminous power of the VCSEL laser.

[0086] Due to the presence of the metal fusion layer 30, if the laser is emitted from the front of the VCSEL laser, the metal fusion layer 30 will absorb part of the laser light, resulting in poor performance of the emitted laser light. Preferably, in the embodiment of the present application, the VCSEL laser is designed to emit light from the back side. That is, after the laser light is reflected and amplified multiple times in the resonant cavity formed by the P-DBR layer 142 and the N-DBR layer 12, it is emitted from the N-DBR layer and passes through the substrate 11 before reaching the outside world.

[0087] Accordingly, in order to improve the light transmittance of the substrate 11 and ensure good light output quality, the thickness of the substrate 11 should be reasonably designed. In this embodiment, the thickness of the substrate 11 of the VCSEL laser is designed to be relatively thin. Specifically, the thickness of the substrate 11 ranges from 5 μm to 20 μm. Of course, it should be understood that in the actual application of the VCSEL laser, the material and thickness of the substrate 11 can be adjusted according to needs and are not limited by this application.

[0088] To allow the laser to emit light, a light-emitting hole corresponding to the P-type semiconductor structure 14 is formed by electrically connecting to the negative electrode 60 electrically connected to the substrate 11. That is, in the embodiment of the present application, the negative electrode 60 is an annular electrode, and it forms a light-emitting hole corresponding to the P-type semiconductor structure 14. Here, the diameter of the light-emitting hole is designed according to the diameter of the P-type semiconductor structure 14. In the embodiment of the present application, the diameter of the P-type semiconductor structure 14 ranges from 8 um to 15 um, and the diameter of the light-emitting hole ranges from 10 um to 50 um. It should be understood that the range of the diameter of the light-emitting hole and the range of the diameter of the P-type semiconductor structure 14 can both be adjusted according to the actual application situation, and this is not limited by the present application.

[0089] To improve the light transmittance of the substrate 11, the thickness of the substrate 11 of the VCSEL laser is relatively thin. After the substrate 11 is thinned, the overall structural strength of the VCSEL laser may not be sufficient. Therefore, to ensure the stability of the overall structure of the VCSEL laser, in the embodiment of the present application, the VCSEL laser further includes the conductive substrate 40 formed on the upper surface of the metal fusion layer 30 in a stacked manner.

[0090] Specifically, the conductive substrate 40 includes a substrate layer 41 and a bonding layer 42 formed on the lower surface of the substrate layer 41. Among them, the conductive substrate 40 is bonded to the metal fusion layer through a bonding process. More specifically, in this embodiment, the bonding layer 42 includes a second ohmic contact metal layer 421 formed on the lower surface of the substrate layer 41 and a second metal conductive layer 422 formed on the lower surface of the second ohmic contact metal layer 421. Preferably, the second metal conductive layer 422 is made of the same material as the first metal conductive layer 32. In this way, when the conductive substrate 40 is bonded to the metal fusion layer 30, the first metal conductive layer 32 and the second metal conductive layer 42 are bonded to form a stable bonding structure, which is conducive to stably bonding the conductive substrate 40 to the metal fusion layer 30.

[0091] The function of the substrate layer 41 is to improve the overall structural strength of the VCSEL laser. Therefore, preferably, in the embodiment of the present application, the substrate layer 41 has a certain thickness. More specifically, in this embodiment, the thickness dimension of the substrate layer is 50 um to 200 um.

[0092] Moreover, the substrate layer should have the ability to conduct electricity. In this embodiment, the substrate layer 41 is selected from one of the following: a metal layer and a semiconductor layer. Among them, the semiconductor layer includes but is not limited to a P-type silicon crystal layer, a P-type gallium arsenide layer, etc.; the metal layer includes but is not limited to an Au layer, an Al layer, a Cu layer, etc.

[0093] As Figure 2 shown, in this embodiment, the positive electrode 50 is formed on the upper surface of the conductive substrate 40 in a stacked manner. Preferably, the positive electrode 50 can be designed as a planar electrode, which can avoid the carrier aggregation effect when current is injected into the positive electrode 50. Of course, the positive electrode 50 can also be implemented as a ring electrode, and this is not limited by the present application.

[0094] In summary, the VCSEL laser based on the embodiment of the present application is clarified. It has a novel semiconductor structure, so that it still has a relatively high photoelectric conversion efficiency under the drive of a relatively high current density. Therefore, the VCSEL laser can have a relatively high luminous power and can be suitably applied to long-distance sensing applications. After testing, the VCSEL array formed by the VCSEL laser according to the embodiment of the present application can be used to detect target objects more than 100 meters away.

[0095] Specifically, the VCSEL laser forms a growth barrier layer for current confinement around its P-type semiconductor structure through an epitaxial growth process to replace the existing oxidation confinement layer, so as to reduce the thermal accumulation caused by the free carrier absorption effect through the growth confinement layer. That is, the VCSEL laser adopts a novel current confinement structure to reduce the thermal accumulation during its operation, so that it can still have a relatively high photoelectric conversion efficiency under the drive of a high current density.

[0096] Moreover, the growth confinement layer formed around the P-type semiconductor structure can repair the lattice broken bonds on the outer peripheral wall of the P-type semiconductor structure to reduce the surface free carrier recombination effect on the outer peripheral wall. In this way, the VCSEL laser has a relatively high photoelectric conversion efficiency.

[0097] In addition, the growth confinement layer formed around the P-type semiconductor structure increases the thermal dissipation area of the VCSEL laser, thereby reducing the heat accumulation around the light-emitting active region and avoiding the decrease of the light power and the photoelectric conversion efficiency caused by heat.

[0098] It is worth mentioning that although in the embodiment of the present application, the VCSEL laser with backlight emission is taken as an example, it should be easily understood that the technical concept according to the embodiment of the present application can still be applied to the VCSEL laser with front light emission.

[0099] Specifically, as Figure 3 shown in the schematic deformation implementation, the VCSEL laser is implemented as a VCSEL laser with front light emission. In particular, compared with Figure 2The illustrated VCSEL laser. In this modified embodiment, the material of the first metal conductive layer 32 of the metal fusion layer 30 is preferably a transparent metal material to avoid excessive influence of the metal fusion layer 30 on the performance of the emitted laser. Correspondingly, in this modified embodiment, since the thickness of the substrate 11 does not need to be thinned, in this modified embodiment, there is no need to configure the conductive substrate 40 anymore, and the positive electrode 50 can be directly electrically connected to the metal fusion layer 30, where the positive electrode 50 forms a light-emitting hole corresponding to the P-type semiconductor structure 14.

[0100] Preparation Method of Exemplary VCSEL Laser

[0101] According to another aspect of the present application, there is also provided a method for manufacturing a VCSEL laser, which is used to manufacture the VCSEL laser as described above.

[0102] Figure 4 The flowchart of the method for manufacturing the VCSEL laser according to the embodiment of the present application is illustrated. Figures 5A to 5C The schematic diagram of the manufacturing process of the VCSEL laser according to the embodiment of the present application is illustrated. As Figure 4 shown, the method for manufacturing the VCSEL laser according to the embodiment of the present application includes: S110, forming an epitaxial structure 80 through an epitaxial growth process, where the epitaxial structure 80 includes, from bottom to top: a substrate 11, an N-DBR layer 12, an active region 13, a P-DBR layer 141, and a P-type ohmic contact semiconductor layer 142; S120, etching at least a part of the P-DBR layer 141 and the electrical contact region to form a P-type semiconductor structure 14; S130, forming a growth confinement layer 20 on the active region 13 through an epitaxial growth process, where the growth confinement layer 20 surrounds the P-type semiconductor structure 14, and the growth confinement layer 20 is used to allow free carriers to flow into the P-type semiconductor structure 14; S140, forming a metal fusion layer 30 on the upper surface of the P-type semiconductor structure 14 through an electroplating process; S150, bonding a conductive substrate 40 to the metal fusion layer 30 through a bonding process; S160, removing at least a part of the substrate 11 to reduce the thickness dimension of the substrate 11; S170, forming a negative electrode 60 on the lower surface of the substrate 11, where the negative electrode 60 forms a light-emitting hole corresponding to the P-type semiconductor structure 14; and S180, forming a positive electrode 50 on the conductive substrate 40.

[0103] In the manufacturing method according to the embodiment of the present application, in one example, as Figure 5AThe process of forming a metal fusion layer on the upper surface of the P-type semiconductor structure as shown includes: First, a first ohmic contact metal layer is formed on the upper surfaces of the P-type semiconductor structure and the growth limiting layer through an electroplating process. Then, a first metal conductive layer is formed on the upper surface of the first ohmic contact metal layer.

[0104] In the preparation method according to the embodiment of the present application, in one example, as Figure 5B shown, the process of bonding a conductive substrate to the metal fusion layer through a bonding process includes: First, a substrate layer is provided; Next, a second ohmic contact metal layer is formed on the lower surface of the substrate layer through an electroplating process; Then, a second metal contact layer is formed on the lower surface of the second ohmic contact metal layer to form the conductive substrate; Next, the second metal contact layer of the conductive substrate is bonded to the first metal conductive layer to bond the conductive substrate to the metal fusion layer.

[0105] Those skilled in the art should understand that the embodiments of the present application described above and shown in the drawings are only examples and do not limit the present application. The objectives of the present application have been fully and effectively achieved. The functions and structural principles of the present application have been demonstrated and explained in the embodiments, and without departing from the said principles, the embodiments of the present application can have any deformation or modification.

Claims

1. A VCSEL laser, characterized in that, Comprising: A substrate; An N-DBR layer formed on the substrate; An active region formed on the N-DBR layer; A P-type semiconductor structure formed on the active region, wherein the P-type semiconductor structure includes a P-DBR layer formed on the active region and a P-type ohmic contact semiconductor layer formed on the P-DBR layer; A growth limiting layer, formed on the active region by an epitaxial growth process after the formation of the P-type semiconductor structure, wherein the P-type semiconductor structure is surrounded by the growth limiting layer, and the growth limiting layer is made of a semiconductor material for allowing free carriers to flow into the P-type semiconductor structure; A metal fusion layer formed on the upper surfaces of the P-type semiconductor structure and the growth limiting layer, wherein the metal fusion layer includes a first ohmic contact metal layer formed on the upper surfaces of the P-type semiconductor structure and the growth limiting layer, and a first metal conductive layer formed on the first ohmic contact metal layer; wherein a Schottky barrier is formed between the first ohmic contact metal layer and the growth limiting layer to prevent the working current from flowing into the growth limiting layer; A conductive substrate formed on the metal fusion layer, including a substrate layer and a bonding layer formed on the lower surface of the substrate layer, and the bonding layer is bonded to the first metal conductive layer; and A positive electrode electrically connected to the conductive substrate and a negative electrode electrically connected to the substrate, wherein the negative electrode forms a light-emitting hole corresponding to the P-type semiconductor structure.

2. The VCSEL laser according to claim 1, wherein, The upper surface of the P-type ohmic contact semiconductor layer forms the upper surface of the P-type semiconductor structure.

3. The VCSEL laser according to claim 2, wherein The P-type ohmic contact semiconductor layer is made of P-GaAs or P-InGaAs material.

4. The VCSEL laser according to claim 2, wherein, The growth limiting layer has the same height as the P-type semiconductor structure, and the upper surface of the growth limiting layer is flush with the upper surface of the P-type semiconductor structure.

5. The VCSEL laser according to claim 4, wherein, The growth limiting layer is circumferentially bonded to the outer peripheral surface of the P-type semiconductor structure.

6. The VCSEL laser according to claim 2, wherein, The material of the growth limiting layer is N-GaAs.

7. The VCSEL laser according to claim 2, wherein, The material of the first metal conductive layer is selected from one of the following materials: Au, Pt, Al, and Cu.

8. The VCSEL laser according to claim 7, wherein The bonding layer includes a second ohmic contact metal layer formed on the lower surface of the substrate layer and a second metal conductive layer formed on the lower surface of the second ohmic contact metal layer.

9. The VCSEL laser according to claim 8, wherein, The material of the second metal conductive layer is the same as that of the first metal conductive layer.

10. The VCSEL laser according to claim 7, wherein, The substrate layer is selected from one of the following: a metal layer and a semiconductor layer.

11. The VCSEL laser according to claim 10, wherein, The semiconductor layer is a P-type silicon crystal layer.

12. The VCSEL laser according to claim 10, wherein, The semiconductor layer is a P-GaAs layer.

13. The VCSEL laser according to claim 7, wherein, The thickness of the substrate layer is 50 um to 200 um.

14. The VCSEL laser according to claim 1, wherein, The substrate is an N-GaAs layer, and the thickness dimension range of the substrate is 5 um to 20 um.

15. The VCSEL laser according to claim 1, wherein, The diameter range of the P-type semiconductor structure is 8 um to 15 um.

16. The VCSEL laser according to claim 15, wherein, The diameter range of the light-emitting hole is 10 um to 50 um.

17. A method for preparing a VCSEL laser, characterized in that, Comprising: Form an epitaxial structure by an epitaxial growth process, wherein the epitaxial structure includes, from bottom to top: a substrate, an N-DBR layer, an active region, a P-DBR layer, and a P-type ohmic contact semiconductor layer; Etch at least a portion of the P-DBR layer and the P-type ohmic contact semiconductor layer to form a P-type semiconductor structure; Form a growth confinement layer on the active region by an epitaxial growth process, wherein the growth confinement layer surrounds the P-type semiconductor structure and is configured to allow free carriers to flow into the P-type semiconductor structure; Form a metal fusion layer on the upper surface of the P-type semiconductor structure by an electroplating process; Bond a conductive substrate to the metal fusion layer by a bonding process; Remove at least a portion of the substrate to reduce the thickness dimension of the substrate; Form a negative electrode on the lower surface of the substrate, wherein the negative electrode forms a light-emitting hole corresponding to the P-type semiconductor structure; and Form a positive electrode on the conductive substrate; The P-type semiconductor structure includes a P-DBR layer formed in the active region and a P-type ohmic contact semiconductor layer formed on the P-DBR layer; Forming a metal fusion layer on the upper surface of the P-type semiconductor structure by an electroplating process includes: Form a first ohmic contact metal layer on the upper surfaces of the P-type semiconductor structure and the growth confinement layer by an electroplating process; and Form a first metal conductive layer on the upper surface of the first ohmic contact metal layer by an electroplating process; The conductive substrate includes a substrate layer and a bonding layer formed on the lower surface of the substrate layer, and the bonding layer is bonded to the first metal conductive layer.

18. The manufacturing method of the VCSEL laser according to claim 17, wherein, The upper surface of the P-type ohmic contact semiconductor layer forms the upper surface of the P-type semiconductor structure.

19. The manufacturing method of the VCSEL laser according to claim 17, wherein, Bonding a conductive substrate to the metal fusion layer by a bonding process includes: Provide a substrate layer; Form a second ohmic contact metal layer on the lower surface of the substrate layer by an electroplating process; Form a second metal contact layer on the lower surface of the second ohmic contact metal layer by an electroplating process to form the conductive substrate, wherein the second ohmic contact metal layer and the second metal contact layer form the bonding layer; and Bond the second metal contact layer of the conductive substrate to the first metal conductive layer to bond the conductive substrate to the metal fusion layer.

Images