A semiconductor laser and its fabrication method

Abstract

The application provides a semiconductor laser and a preparation method thereof. The semiconductor laser comprises a substrate, a laminated structure, a conductive region, a first isolation groove and a second isolation groove. The laminated structure is arranged above the substrate and comprises at least an ohmic contact layer arranged at the topmost layer and an N-type confinement layer arranged at the bottommost layer. The conductive region is formed at the top of the laminated structure and extends along a first direction of the semiconductor laser, and the first direction is the extension direction of the cavity length of the semiconductor laser. The first isolation groove is formed on both sides of the conductive region in a second direction perpendicular to the first direction. The second isolation groove is formed between the conductive region and the first isolation groove, and the first isolation groove extends to the N-type confinement layer or the substrate. The second isolation groove extends to the ohmic contact layer. The semiconductor laser can cut off the internal, surface and near-surface current diffusion bypass of the semiconductor laser, improve the current injection efficiency of the semiconductor laser, and improve the yield and reliability of the semiconductor laser.

Description

Technical Field

[0001] This application relates to the field of semiconductor laser technology, and more specifically, to a semiconductor laser and a method for fabricating the same. Background Technology

[0002] With the increasing and in-depth application of semiconductor lasers in fields such as optical communication, optical storage, sensing, and materials processing, the requirements for their output power, conversion efficiency, reliability, and lifespan are also rising. Effectively controlling the injection current path, optimizing the process, and reducing potential failure risks are core challenges in the design and manufacture of semiconductor lasers.

[0003] Current-limiting structures commonly found in existing technologies primarily rely on single isolation trenches etched on both sides of the conductive region. However, this structure suffers from several significant technical drawbacks in practical applications: 1. A single isolation trench structure is often insufficient in terms of physical size and electrical isolation characteristics to completely block lateral current diffusion. Some injected current bypasses the isolation trench, forming an ineffective bypass path in the non-gain region of the device's active area. This leads to a decrease in the proportion of current effectively injected into the active area, limiting the overall photoelectric conversion efficiency of the device. 2. In actual manufacturing processes, isolation trenches often have non-horizontal or non-vertical sidewall shapes, typically with a certain tilt angle. At the trench opening, unavoidable "bird's beak" protrusions or overhangs often form. This results in inconsistent etching rates and poor uniformity across different areas of the isolation trench during metal etching, easily leading to incomplete etching, metal residue, unwanted electrical paths, increased short-circuit risk, and consequently, significantly reduced device yield and reliability.

[0004] Furthermore, cleaving trenches used for cleaving positioning also have significant drawbacks. After etching, the sidewalls and bottom of cleaving trenches used for cleaving positioning in semiconductor lasers directly expose the semiconductor material inside the device. This structural material exposure poses significant risks: First, during subsequent chip manufacturing, packaging, or use, moisture and ionic contaminants in the environment can easily penetrate the semiconductor material through the exposed surface of the cleaving trench, forming conductive channels on the semiconductor surface and causing significant edge leakage current in the device. Second, the intrusion of contaminants and moisture can induce surface degradation of the semiconductor material, which not only further exacerbates the risk of leakage current but also impairs the long-term operational stability and reliability of the device, becoming a potential source of failure. Summary of the Invention

[0005] In view of this, this application provides a semiconductor laser and its fabrication method, aiming to solve the technical problems of insufficient current diffusion control, poor etching uniformity, and edge leakage caused by the exposure of semiconductor material in the cleavage trench in the prior art.

[0006] The technical solution provided in this application is as follows:

[0007] In a first aspect, this application provides a semiconductor laser, the semiconductor laser comprising:

[0008] Substrate;

[0009] A stacked structure is disposed above the substrate, the stacked structure including at least an ohmic contact layer disposed on the top layer of the stacked structure and an N-type confinement layer disposed on the bottom layer of the stacked structure;

[0010] A conductive region is formed on the top of the stacked structure and extends along a first direction, which is the direction in which the cavity length of the semiconductor laser extends.

[0011] A first isolation groove is formed on the top of the stacked structure and on both sides of the conductive area in a second direction, wherein the second direction is on the same horizontal plane as the first direction and perpendicular to the first direction;

[0012] A second isolation trench is formed on the top of the stacked structure and is formed in the second direction between the conductive region and the first isolation trench;

[0013] Wherein, the first isolation trench extends to the N-type confinement layer or the substrate;

[0014] Furthermore, the second isolation groove extends into the ohmic contact layer.

[0015] Furthermore, the centerline of the first isolation groove and the centerline of the second isolation groove are arranged parallel to each other along the first direction.

[0016] Furthermore, the surface of the conductive region is covered with a first metal layer and a second metal layer;

[0017] The bottom wall and side wall of the first isolation groove each have a first insulating film, a first metal layer, a second metal layer and a second insulating film stacked together;

[0018] The first metal layer and the second metal layer covering the surface of the conductive area extend to the first isolation trench and cover the bottom wall and side wall of the first isolation trench.

[0019] Furthermore, the bottom wall of the second isolation groove has the first insulating film and the second insulating film stacked together; the side wall of the second isolation groove has a layer of the second insulating film;

[0020] The first insulating film and the second insulating film, which are stacked in the first isolation groove, extend into the second isolation groove and cover the bottom wall of the second isolation groove.

[0021] Furthermore, the semiconductor laser also includes: a cleavage groove;

[0022] The cleaving groove is disposed on the outer side of the first isolation groove away from the conductive area, and the extension depth of the cleaving groove in the stacked structure is the same as the extension depth of the second isolation groove in the stacked structure;

[0023] The bottom wall of the cleavage groove has a layer of the first insulating film, and the thickness of the first insulating film is 20nm-50nm.

[0024] Furthermore, the sidewall of the cleavage groove has a layer of the second insulating film;

[0025] The first insulating film and the second insulating film, which are stacked in the first isolation groove, extend to the cleavage groove and cover the cleavage groove.

[0026] Furthermore, the conductive region further includes: a ridge waveguide;

[0027] The ridge waveguide is disposed at the center of the conductive region, and the extension length of the ridge waveguide in the first direction and the second direction is less than the extension length of the conductive region in the first direction and the second direction, respectively.

[0028] On the other hand, this application also provides a method for fabricating a semiconductor laser, which includes the following steps:

[0029] Step S11: Grow a stacked structure on the substrate;

[0030] Step S12: A conductive region is formed on the surface of the stacked structure, and first isolation trenches are etched on both sides of the conductive region along the second direction, with the two first isolation trenches being spaced apart from the conductive region.

[0031] Step S13: A second isolation trench is etched between the conductive region and the first isolation trench to form a second isolation trench. At the same time, a cleavage trench is etched on the outer side of the first isolation trench away from the conductive region.

[0032] Wherein, the first isolation groove extends to a greater depth than the second ...

[0033] Furthermore, prior to step S13, the following is also included:

[0034] Step S101: A first insulating film of a first predetermined thickness is grown on the surface of the stacked structure, and the first insulating film covers the surface of the conductive area and the bottom and side walls of the first isolation groove.

[0035] Step S102: Etch downwards from the first insulating film formed at the center of the conductive region surface to form a ridge waveguide;

[0036] Step S103: A first metal layer is deposited on the surface of the stacked structure. The first metal layer covers the first insulating film and covers the surface of the conductive area as well as the bottom and side walls of the first isolation trench.

[0037] Step S104: Thicken the first metal layer on the surface of the conductive region;

[0038] Step S105: A second metal layer is deposited on the surface of the first metal layer of the stacked structure, and the second metal layer covers the surface of the conductive area and the bottom and side walls of the first isolation trench.

[0039] Furthermore, after step S13, the following is also included:

[0040] Step S106: A second insulating film of a second predetermined thickness is grown on the surface of the second metal layer of the laminated structure;

[0041] The second insulating film covers the surface of the conductive area, the bottom and side walls of the first isolation groove, the bottom and side walls of the second isolation groove, and the bottom and side walls of the cleavage groove.

[0042] Furthermore, after step S106, the method further includes:

[0043] Step S107: Etch the second insulating film of the conductive region and the cleavage groove, wherein the etching depth is greater than the second preset thickness and less than the sum of the first preset thickness and the second preset thickness;

[0044] Step S108: Thin the bottom surface of the substrate, deposit metal to form a back metal, and anneal the second metal layer on the surface of the conductive area and the back metal to form the semiconductor laser.

[0045] The solution provided in this application has the following beneficial effects:

[0046] 1. The semiconductor laser provided in this application, by setting a first isolation trench and a second isolation trench with different depths along the stacking direction of the stacked structure on both sides of the conductive region, wherein the first isolation trench extends to the N-type confinement layer or substrate, and the second isolation trench extends to the ohmic contact layer, the greater penetration depth of the first isolation trench in the deeper layers of the semiconductor laser can concentrate the injected current along a direction perpendicular to the substrate plane to the ridge waveguide at the center of the conductive region, avoiding the lateral diffusion of charge carriers inside the semiconductor laser and the formation of undesirable leakage channels, thereby improving the recombination efficiency of charge carriers and improving the current injection efficiency of the semiconductor laser; at the same time, the second isolation trench can... It can cut off the surface metal layer connection of the semiconductor laser and the lateral current path near the surface of the semiconductor laser, eliminate the diffusion bypass of electrode current from the surface of the semiconductor device to the non-functional area, and avoid carrier bypass leakage near the surface of the semiconductor laser. The combined effect of the first isolation trench and the second isolation trench can not only form complete current isolation from the surface to the depth of the semiconductor laser, improve the control accuracy of current diffusion from the surface to the depth of the semiconductor laser, but also greatly enhance the effective carrier flux injected into the semiconductor laser, thereby maximizing the excitation laser conversion efficiency. At the same time, it can also improve the yield and reliability of the semiconductor laser.

[0047] 2. The semiconductor laser provided in this application retains the two layers of metal deposited inside the first isolation trench. This is because in actual production, the isolation trench often has a non-horizontal or non-vertical sidewall shape, and at the trench opening, an unavoidable "bird's beak"-shaped protrusion or overhang structure often forms. Therefore, in the prior art, when etching the metal layer of the isolation trench, due to the non-horizontal or non-vertical structure of the isolation trench, the etching rate and etching uniformity cannot be guaranteed, resulting in uneven and incomplete etching of the metal layer. This easily leads to metal layer residue, which in turn forms an undesirable electrical path inside the semiconductor laser, causing damage to the semiconductor laser. In this application, however, the entire inside of the first isolation trench is deposited by vapor deposition. The two metal layers are retained without etching, fundamentally avoiding the problem of uneven and incomplete etching caused by non-planar geometric features such as the non-horizontal or non-vertical structure of the isolation trench and the "bird's beak" protrusion. At the same time, an insulating film, two metal layers, and another insulating film are stacked on the first isolation trench. By retaining the metal layer inside the first isolation trench and setting an insulating film at the bottom and top of the metal layer inside the first isolation trench, necessary electrical insulation can be provided to prevent the formation of unwanted ohmic contacts or leakage paths between the metal inside the device and the semiconductor substrate or epitaxial layer, avoid current conduction inside the semiconductor device, improve the breakdown voltage of the device, and ensure the reliability of the semiconductor laser.

[0048] 3. The semiconductor laser provided in this application, by covering the second isolation trench with an insulating film, can cut off the surface metal layer connection and the lateral current path near the surface, completely blocking the diffusion bypass of current from the electrode metal layer through the device surface or shallow region to the non-functional regions on both sides of the active region; compared with the single isolation trench in the prior art, this application can improve the control accuracy of the surface and near-surface current of the semiconductor laser by setting the second isolation trench, thereby greatly improving the current injection efficiency and ensuring that more current is effectively injected into the active region and converted into laser output.

[0049] 4. The semiconductor laser provided in this application has a continuous and dense insulating film of a certain thickness remaining on the sidewalls and bottom of the cleavage groove. The film thickness is thin enough that it will not cause abnormal stress or fracture during the cleavage process, thereby avoiding the degradation of the cleavage surface quality or the generation of a large number of dust particles that would harm the optical properties of the semiconductor laser cavity surface. Furthermore, it can form effective physical and electrochemical isolation. The retained insulating film can completely cover the exposed semiconductor material on the sidewalls and bottom of the cleavage groove, which not only effectively prevents moisture and ionic contaminants from directly contacting and penetrating into the exposed semiconductor material and causing pollution, but also forms electrical isolation in the cleavage groove, reducing and avoiding the problem of side leakage.

[0050] 5. The semiconductor laser fabrication method provided in this application improves the current injection efficiency of the semiconductor laser by depositing a first insulating film to form a basic passivation layer at the bottom of the first and second isolation trenches, thereby isolating the current diffusion bypass inside, on the surface, and near the surface of the semiconductor laser. Furthermore, by retaining the first and second metal layers inside the first isolation trench without etching, the uneven and incomplete etching of the metal film caused by the non-horizontal or non-vertical structure of the isolation trench and the "bird's beak" protrusion at the top, as in the prior art, is completely avoided. Moreover, the photolithography and development steps in the prior art are eliminated before the two metal evaporation depositions on the front side, thus avoiding the introduction of photoresist and developer. Organic materials are used to completely avoid the contamination problems caused by photoresist and developer residues in existing technologies, further avoid metal adhesion problems caused by contaminant residues, and avoid the reliability risks of semiconductor lasers caused by subsequent metal detachment. At the same time, by depositing a second insulating film, physical isolation can be formed on the surfaces of the first and second isolation trenches to shield the semiconductor laser from the erosion of moisture and ionic contaminants in the air. Furthermore, a sufficiently thin insulating film can be formed on the surface of the cleavage trench, which can not only ensure normal chip cleavage but also effectively block the erosion of semiconductor materials by moisture and ionic contaminants. At the same time, electrical isolation can be formed in the cleavage trench to avoid the risk of side leakage.

[0051] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0052] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 This is a cross-sectional schematic diagram of a semiconductor laser provided in an embodiment of this application;

[0054] Figure 2 This is a cross-sectional schematic diagram of a semiconductor laser provided in an embodiment of this application. Only the location of the first isolation groove is shown in this figure.

[0055] Figure 3 This is a top view of a semiconductor laser provided in an embodiment of this application. Only the positions of the first isolation trench, the second isolation trench, and the cleavage trench are shown in this figure.

[0056] Figure 4 This is a schematic diagram of the structure of the first isolation trench of a semiconductor laser in actual production.

[0057] Figure 5 A flowchart illustrating a method for fabricating a semiconductor laser provided in this application embodiment;

[0058] Figures 6A-6J This is a cross-sectional structural diagram of each step in the manufacturing method of the semiconductor laser provided in the embodiments of this application.

[0059] Explanation of reference numerals in the attached figures:

[0060] 100 - Substrate; 200 - Stacked structure; 201 - N-type confinement layer; 202 - N-type waveguide layer; 203 - Quantum well layer; 204 - P-type waveguide layer; 205 - P-type confinement layer; 206 - Ohmic contact layer; 300 - Conductive region; 301 - Ridge waveguide; 400 - First isolation trench; 401 - "Bird's beak" shaped protrusion; 500 - Second isolation trench; 600 - Cleavage trench; 701 - First insulating film; 702 - First metal layer; 703 - Second metal layer; 704 - Second insulating film. Detailed Implementation

[0061] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0062] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0063] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0064] In the description of this application, it should be noted that the terms "inner," "outer," "upper," "lower," "vertical," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0065] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, features in the following embodiments can be combined with each other.

[0066] In view of the shortcomings of the prior art, the technical solution of this application is proposed. The technical solution of this application will be described in detail below.

[0067] Please see Figures 1-3 , Figure 1 This is a cross-sectional schematic diagram of a semiconductor laser provided in an embodiment of this application. Figure 2 This is a cross-sectional schematic diagram of a semiconductor laser provided in an embodiment of this application. Figure 3 A top view of a semiconductor laser provided in an embodiment of this application.

[0068] The semiconductor laser includes: a substrate 100, a stacked structure 200, a conductive region 300, a first isolation trench 400, and a second isolation trench 500.

[0069] The substrate 100 may be a GaAs substrate or other compound semiconductor materials, such as GaN.

[0070] The stacked structure 200 is disposed above the substrate 100, and the stacked structure 200 includes at least an ohmic contact layer 206 disposed on the top layer of the stacked structure 200 and an N-type confinement layer 201 disposed on the bottom layer of the stacked structure 200.

[0071] Specifically, the stacked structure 200 is disposed above the substrate 100 along the stacking direction. The stacking direction is defined as the vertical direction from the bottom interface of the N-type confinement layer 201 to the top interface of the ohmic contact layer 206, which is consistent with the epitaxial growth direction of the semiconductor laser and parallel to the current injection direction of the semiconductor laser.

[0072] In one embodiment, the stacked structure 200 includes, from bottom to top, an N-type confinement layer 201, an N-type waveguide layer 202, a quantum well layer 203, a P-type waveguide layer 204, a P-type confinement layer 205, and an ohmic contact layer 206. The N-type confinement layer 201 serves as an electron injection channel and the lower optical confinement boundary, and its high bandgap characteristics form a bottom carrier barrier. The N-type waveguide layer 202 receives the electron flow and guides the photon transmission path, and its bandgap gradient allows electrons to be qualitatively injected into the quantum well layer 203. The quantum well layer 203 serves as the core active region for carrier recombination luminescence, and the quantum size effect confines the carriers in the quantum well layer 203, forcing the radiative recombination of carriers to occur in its potential well space. The P-type waveguide layer 204 is symmetrically arranged with the N-type waveguide layer 202, and is used to guide the hole transmission path. Together with the N-type waveguide layer 202, it forms the lateral boundary of the optical resonator to constrain the light field distribution. The P-type confinement layer 205 serves as a hole injection channel and the upper optical confinement boundary, and forms a double heterojunction structure with the N-type confinement layer 201. The ohmic contact layer 206 realizes the ohmic contact between the metal electrode and the semiconductor material, and its narrow bandgap heavy doping characteristics eliminate the interface barrier.

[0073] The conductive region 300 is formed on the top of the stacked structure 200 and extends along a first direction, which is the direction in which the cavity length of the semiconductor laser extends. The surface of the conductive region 300 is covered with a first metal layer 702 and a second metal layer 703. The conductive region 300 is made of a high thermal conductivity material, and its bottom surface is in close contact with the top of the stacked structure 200. The first metal layer 702 and the second metal layer 703 are made of materials such as Au, Ti, Pt, and their compounds and are tightly attached to the surface of the conductive region 300, forming the main channels for heat diffusion.

[0074] In one embodiment, the conductive region 300 further includes a ridge waveguide 301. The ridge waveguide 301 is disposed at the center of the conductive region 300 and extends along the first direction and a second direction perpendicular to the first direction. The extension length of the ridge waveguide 301 in the first direction and the second direction is less than the extension length of the conductive region 300 in the first direction and the second direction, respectively; that is, the ridge waveguide 301 is located at the center of the conductive region 300 in the second direction, and the ridge waveguide 301 is strictly symmetrical in the second direction.

[0075] Specifically, the ridge waveguide 301 serves as the electrical injection region of the semiconductor laser to achieve current injection. A high-reflectivity film and an anti-reflection film are fabricated on the end face of the ridge waveguide 301 along its extension direction to form a resonant cavity. The high-reflectivity film, called the rear cavity surface, can be considered a total reflection mirror, and the anti-reflection film, called the front cavity surface, can be considered a half-reflection mirror. When the semiconductor laser is powered on, electrons and holes located in the quantum well layer 203 undergo radiative recombination, releasing photons. These photons reflect back and forth within the resonant cavity, generating gain. The purpose of this back-and-forth reflection of photons within the resonant cavity is to allow the excited light to pass through the gain medium of the quantum well layer 203 multiple times to achieve sufficient amplification. When the amplification is sufficient to penetrate the anti-reflection film, the laser beam is emitted from one side of the anti-reflection film. Furthermore, only light of a specific wavelength that resonates between the two cavity surfaces can exit from the cavity surface on the anti-reflection film side. However, in the first direction, the ridge waveguide 301 has an asymmetrical structure. Please refer to [link to relevant documentation]. Figure 1 With reference to the geometric center of the ridge waveguide 301, the inward amount of the ridge waveguide 301 on the side near the light-emitting end face is greater than the inward amount on the side away from the light-emitting end face; in the second direction, the ratio of the ridge width of the ridge waveguide 301 to the width of the semiconductor laser can be adjusted as needed. When a positive voltage is applied to the top electrode of the ridge waveguide 301, holes are injected longitudinally through the ohmic contact layer 206 into the P-type confinement layer 205. Constrained by the narrow width of the ridge waveguide 301, the holes are focused directly above the quantum well layer 203. Simultaneously, electrons are injected from the N-type confinement layer 201, pass through the N-type waveguide layer 202, and enter the quantum well layer 203. Within the quantum well layer 203, electrons and holes undergo radiative recombination, releasing photons. These photons are reflected back and forth along the first direction within the resonant cavity. When photons pass through the quantum well layer 203, stimulated emission is triggered, causing photons of the same phase and wavelength to amplify in an avalanche-like manner. Finally, when the amplification reaches a point where they can penetrate the antireflection coating, laser light is emitted from one side of the antireflection coating.

[0076] The first isolation trench 400 is formed on the top of the stacked structure 200 and on both sides of the conductive region 300 in a second direction. The second direction is on the same horizontal plane as the first direction and perpendicular to the first direction. The second direction is the ridge width direction of the ridge waveguide 301. The first isolation trench 400 is symmetrically disposed on both sides of the conductive region 300 along the second direction. The second direction is perpendicular to the first direction and parallel to the plane where the substrate 100 is located. The trench depth direction of the first isolation trench 400 is perpendicular to the plane where the substrate 100 is located, and the extension depth of the first isolation trench 400 in the first direction is the same as the extension depth of the conductive region 300 in the first direction, so as to form a continuous isolation around the conductive region 300. The second direction is the main channel for lateral diffusion of charge carriers. By setting the first isolation trench 400, the injected current can be forced to be strictly confined in the second direction to the ridge waveguide 301 in the central region of the conductive region 300, ensuring that the charge carrier recombination luminescence process only occurs in the effective gain region of the quantum well layer 203, thereby improving the recombination efficiency of charge carriers.

[0077] The second isolation trench 500 is formed on the top of the stacked structure 200 and is formed in the second direction between the conductive region 300 and the first isolation trench 400. The second isolation trench 500 is disposed in the transition region defined between the outer sidewall of the conductive region 300 and the inner sidewall of the first isolation trench 400. The depth direction of the trench is perpendicular to the plane where the substrate 100 is located, and the second isolation trench 500 extends independently along the first direction. Its extension depth is the same as the extension depth of the conductive region 300 and the first isolation trench 400. Along the second direction, there is a non-contact physical gap between the outer sidewall of the second isolation trench 500 and the conductive region 300 and the first isolation trench 400. This physical gap makes the conductive region 300, the second isolation trench 500 and the first isolation trench 400 present a clear sequential arrangement relationship in the second direction.

[0078] In one embodiment, the width of the physical interval between the first isolation trench 400 and the second isolation trench 500 is controlled to be approximately 5 micrometers to 10 micrometers. The width of the physical interval between the first isolation trench 400 and the conductive region 300 is equal to the sum of the width of the second isolation trench 500 and the width of the physical interval between the second isolation trench 500 and the conductive region 300. The width of the physical interval between the first isolation trench 400 and the conductive region 300 depends on the width of the second isolation trench 500. The width of the second isolation trench 500 varies depending on the device structure of the semiconductor laser and is typically controlled to be between 10 micrometers and 30 micrometers.

[0079] Specifically, the first isolation trench 400 extends to the N-type confinement layer 201 or the substrate 100; and the second isolation trench 500 extends to the ohmic contact layer 206. The etching depth of the first isolation trench 400 continues downward in the stacking direction, penetrating the entire P-type confinement layer 205 and the P-type waveguide layer 204, and finally penetrating the quantum well layer 203, so that the bottom interface of its trench terminates inside the N-type confinement layer 201 or the substrate 100, realizing full depth coverage of the stacked structure 200 from the top surface of the ohmic contact layer 206 to the N-type confinement layer 201 or the substrate 100; this depth characteristic enables the first isolation trench 400 to form a longitudinal isolation deeply buried inside the semiconductor laser in the carrier transport path. The etching depth of the second isolation trench 500 is controlled to reach only the internal material layer of the ohmic contact layer 206 and not extend further down to the P-type confinement layer 205 region. The bottom boundary of the second isolation trench 500 is limited within the thickness of the ohmic contact layer 206, so that the depth of the second isolation trench 500 is limited to the junction between the surface metal electrode layer of the semiconductor laser and the underlying semiconductor functional layer, thereby isolating the surface current near the surface electrode of the semiconductor laser. The bottom interface of the first isolation trench 400 extends deeper into the internal functional area of ​​the stacked structure 200 than the bottom interface of the second isolation trench 500. This configuration allows the first isolation trench 400 to undertake the main interception function of the carrier diffusion path and heat transfer channel in the deep region of the semiconductor laser, while the second isolation trench 500 focuses on the current leakage and local thermal field modulation of the surface and near-surface of the semiconductor laser.

[0080] In this embodiment, by providing a first isolation trench 400 and a second isolation trench 500 with different depths along the stacking direction of the stacked structure 200 on both sides of the conductive region 300 of the semiconductor laser, the trench depth of the first isolation trench 400 is set to extend into the N-type confinement layer 201 or the substrate 100, so that the first isolation trench 400 and the conductive region 300 together constitute a carrier confinement channel to block the lateral transport path of electrons inside the semiconductor laser, so that the injected current converges in a direction perpendicular to the plane of the substrate 100 to the quantum well layer 203 below the ridge waveguide 301. This ensures that the recombination and luminescence process of charge carriers only occurs in the effective gain region of the quantum well layer 203 below the ridge waveguide 301, thereby improving the recombination efficiency of charge carriers and the current injection efficiency of the semiconductor laser. By setting the depth of the second isolation trench 500 to extend into the ohmic contact layer 206, the connection of the surface metal layer of the semiconductor laser can be completely cut off and the lateral current path near the surface of the semiconductor laser can be cut off, eliminating the bypass of electrode current diffusion from the surface of the semiconductor device to the non-functional region, and avoiding charge carrier bypass leakage near the surface of the semiconductor laser.

[0081] The first isolation trench 400 and the second isolation trench 500 can form multiple current isolations in the stacking direction. The first isolation trench 400 suppresses the lateral diffusion of charge carriers inside the semiconductor laser, while the second isolation trench 500 can prevent surface leakage on the top surface of the semiconductor laser, thereby controlling the charge carrier transport channel and preventing the injected current from forming an invalid bypass path in the non-gain region of the semiconductor laser. This increases the proportion of current injected into the active gain region of the semiconductor laser, thereby improving the overall photoelectric conversion efficiency of the semiconductor laser. At the same time, the combined effect of the first isolation trench 400 and the second isolation trench 500 can not only significantly improve the control accuracy of current diffusion from the surface to the deep layers of the semiconductor laser, but also greatly enhance the effective charge carrier flux injected into the ridge waveguide 301, thereby maximizing the excitation laser conversion efficiency. In addition, the deep trench structure of the first isolation trench 400 provides a vertical channel for heat dissipation from the semiconductor laser and can work together with the shallow thermal field modulation of the second isolation trench 500 to maintain the temperature balance of the semiconductor laser.

[0082] In one embodiment, the centerline of the first isolation trench 400 and the centerline of the second isolation trench 500 are arranged parallel to each other along the first direction of the semiconductor laser. The first isolation trench 400, the second isolation trench 500, and the conductive region 300 are parallel to each other along the first direction of the semiconductor laser, and all three extend independently along the first direction with the same extension depth, forming different continuous isolations around the conductive region 300. This ensures that the transport path of charge carriers is strictly constrained to the ridge waveguide 301 in the central region of the conductive region 300, ensuring that the recombination and light emission process only occurs in the effective gain region of the quantum well layer 203 located below the ridge waveguide 301, thereby improving the recombination efficiency of charge carriers.

[0083] In this embodiment, by arranging the first isolation trench 400 and the second isolation trench 500 in parallel, double isolation is formed on both sides of the conductive region 300. This not only blocks the lateral carrier diffusion path along the second direction, but also ensures the uniform transmission of heat distribution and mechanical stress between the first isolation trench 400 and the second isolation trench 500. At the same time, the parallel arrangement of the first isolation trench 400 and the second isolation trench 500 can optimize the light field distribution of the semiconductor laser. The two can form a continuous and uniform optical reflection boundary in the second direction, suppressing the distortion scattering of the light field at the edge of the conductive region 300. Furthermore, the parallel arrangement of the two can avoid the quantum well region from being subjected to asymmetric lattice distortion.

[0084] In one embodiment, the surface of the conductive region 300 is covered with a first metal layer 702 and a second metal layer 703; the bottom wall and sidewalls of the first isolation trench 400 each have a first insulating film 701, the first metal layer 702, the second metal layer 703, and a second insulating film 704 stacked together; wherein the first metal layer 702 and the second metal layer 703 covering the surface of the conductive region 300 extend into the first isolation trench 400 and cover the bottom wall and sidewalls of the first isolation trench 400. The first insulating film 701 is made of SiO2 or SiN. x A high dielectric strength material densely covers the interface of the trench wall as a basic passivation layer; the first metal layer 702 and the second metal layer 703 are made of materials such as Au, Ti, Pt and their compounds, which are tightly attached to the surface of the first insulating film 701 to form the main channels for heat diffusion; the second insulating film 704 is made of SiO2 and SiN. x A high dielectric strength material is applied to the surface of the second metal layer 703 to form a second passivation layer, providing surface mechanical protection and environmental isolation for the semiconductor laser.

[0085] Specifically, in actual production, the first isolation groove 400 often has a non-horizontal or non-vertical sidewall shape, with a certain angle and a "bird's beak"-shaped protrusion 401 at the top, such as... Figure 4 As shown, Figure 4 This is a schematic diagram of the structure of the first isolation trench 400 in actual production of a semiconductor laser. It can be seen that the first isolation trench 400 is an inverted trapezoid with a protrusion at the top, which is the "beak"-shaped protrusion 401. In existing technology, the first metal layer 702 and the second metal layer 703 covering the first isolation trench 400 are etched. Due to the non-horizontal or non-vertical structure of the first isolation trench 400, the etching rate of different areas of the first isolation trench 400 is inconsistent during metal film etching, resulting in poor uniformity and easy metal residue. Residual metal can form unwanted electrical paths, increasing the risk of short circuits in the semiconductor laser and reducing device yield and reliability. Therefore, in this application, the first metal layer 702 and the second metal layer 703 inside the first isolation trench 400 are left unetched, directly avoiding the problem of uneven and incomplete metal film etching caused by their irregular structure.

[0086] In this embodiment, a reliable electrical isolation is formed by covering all semiconductor materials at the bottom of the first isolation trench 400 with a first insulating film 701. By retaining the first metal layer 702 and the second metal layer 703 covering the first insulating film 701, the problem of incomplete etching of the metal film caused by the non-horizontal or non-vertical structure of the isolation trench in the prior art is avoided. This fundamentally avoids the risk of unexpected electrical path formation caused by metal residue, reduces the short-circuit risk of the semiconductor laser, and improves the yield and long-term reliability of the semiconductor laser. At the same time, by covering the second metal layer 703 with a second insulating film 704, the semiconductor laser is provided with surface mechanical protection and environmental isolation, which can block the erosion of external moisture and particulate contaminants, inhibit material degradation caused by oxidation corrosion and process contamination, and further improve the reliability of the semiconductor laser. Through this design, the lateral isolation of the internal current of the semiconductor laser is finally achieved, ultimately improving the yield and reliability of the semiconductor laser.

[0087] In one embodiment, the bottom wall of the second isolation groove 500 has a first insulating film 701 and a second insulating film 704 stacked together; the side wall of the second isolation groove 500 has a layer of the second insulating film 704; wherein, the first insulating film 701 and the second insulating film 704 stacked together in the first isolation groove 400 extend to the second isolation groove 500 and cover the bottom wall of the second isolation groove 500. Both the bottom wall and the side wall of the second isolation groove 500 are made of SiO2 and SiN. x A first insulating film 701 and a second insulating film 704 are respectively covered with high dielectric strength materials. The first insulating film 701 completely covers the semiconductor material at the bottom of the second isolation trench 500 to form lateral current isolation for the surface and near surface of the semiconductor laser. The second insulating film 704 completely covers the first insulating film 701 and the sidewall of the second isolation trench 500 to form complete environmental isolation.

[0088] Specifically, please refer to Figure 1The first insulating film 701 is also covered on the contact surface between the conductive region 300 and the top of the stacked structure 200. The first insulating film 701 at this location and the first insulating film 701 on the bottom wall and side wall of the first isolation trench 400 and the bottom wall of the second isolation trench 500 are formed in the same deposition step during the process. By depositing the conductive region 300, the bottom wall and side wall of the first isolation trench 400 and the surface of the second isolation trench 500 in the same deposition step, the interface connection defects that may be caused by step deposition can be avoided, and a uniform and dense insulating film can be formed on the bottom wall and side wall of the first isolation trench 400 and the surface of the second isolation trench 500, thereby blocking the leakage current on the surface, near the surface and inside of the semiconductor laser.

[0089] In this embodiment, by uniformly covering the bottom wall of the second isolation trench 500 with a uniform and dense first insulating film 701, the connection of the surface metal layer of the semiconductor laser and the lateral current path near the surface can be cut off, blocking the diffusion bypass of current from the electrode metal layer of the semiconductor laser through the device surface or shallow region to the non-functional regions on both sides of the quantum well layer 203 located below the ridge waveguide 301. Compared with the single isolation trench in the prior art, by setting the second isolation trench 500 that extends into the ohmic contact layer 206 at the top of the semiconductor laser, the control accuracy of the surface and near-surface current of the semiconductor laser can be improved, avoiding the lateral leakage current channel that may be generated in the ohmic contact layer 206 of the semiconductor laser, thereby greatly improving the current injection efficiency and ensuring that more current is effectively injected into the quantum well layer 203 located below the ridge waveguide 301 and converted into laser output. At the same time, by uniformly covering the first insulating film 701 and the side wall of the second isolation trench 500 with a second insulating film 704, surface mechanical protection and environmental isolation are formed to avoid the corrosion of external moisture and particulate contaminants and improve the reliability of the semiconductor laser.

[0090] In one embodiment, the semiconductor laser further includes: a cleaving groove 600; the cleaving groove 600 is disposed on the outer side of the first isolation groove 400 away from the conductive region 300, and the extension depth of the cleaving groove 600 in the stacked structure 200 is consistent with the extension depth of the second isolation groove 500 in the stacked structure 200; wherein, the bottom wall of the cleaving groove 600 has a first insulating film 701, the thickness of the first insulating film 701 being 20nm-50nm; and, the side wall of the cleaving groove 600 has a second insulating film 704; the first insulating film 701 and the second insulating film 704 stacked in the first isolation groove 400 extend to the cleaving groove 600 and cover the cleaving groove 600. The depth of the cleavage groove 600 is consistent with the depth of the second isolation groove 500 in the stacking direction. The cleavage process of the semiconductor laser is a key step in manufacturing the resonant cavity. Its core is to form an optical reflecting surface on a specific crystal plane of the semiconductor crystal through mechanical fracture. The cleavage groove 600 and the first isolation groove 400 are strictly parallel in the first direction of the semiconductor laser. In a view perpendicular to the plane of the substrate 100, the outer boundary of the cleavage groove 600 and the outer boundary of the first isolation groove 400 are spaced apart and do not overlap, forming mutually physically separated independent structures. The parallel arrangement of the two can ensure the integrity of the end face of the semiconductor laser resonant cavity.

[0091] The cleavage groove 600 has a first insulating film 701 on its surface, and the thickness of the first insulating film 701 is 20nm-50nm. The sufficiently thin first insulating film 701 can not only ensure that the cracks in the cleavage cleavage propagate stably along the preset crystal orientation without producing deviation branches or dust splashes, avoiding the risk of film cracking caused by the difficulty of cleavage and mechanical stress mismatch due to excessive thickness of the insulating film; it can also form a sealing medium layer at the interface of the cleavage groove 600 that is sufficient to isolate the penetration of external moisture, preventing moisture and ionic contaminants from directly contacting and penetrating into the exposed semiconductor material and causing contamination; at the same time, it can form uniform electrical isolation, reducing and avoiding the risk of lateral leakage.

[0092] In this embodiment, by arranging the cleavage groove 600 parallel to the outer region of the first isolation groove 400, it can be ensured that the stress propagation generated during cleavage fracture will not affect the core optical resonant structure of the ridge waveguide 301 located in the conductive region 300, providing a mechanical stress guiding path for subsequent cavity surface cleavage; and by covering the surface of the cleavage groove 600 with a thin first insulating film 701, normal chip cleavage can be ensured, and abnormal stress or fracture can be avoided during the cleavage process, thereby avoiding degradation of the cleavage surface quality or the generation of a large number of dust particles that harm the cavity surface optical characteristics of the semiconductor laser; at the same time, covering the cleavage groove 600 with the first insulating film 701 can form isolation on the surface of the semiconductor laser, preventing contaminants and moisture from penetrating the semiconductor material and causing degradation; and the first insulating film 701 will form electrical isolation at the edge of the cleavage groove 600, preventing the formation of conductive channels on the surface of the semiconductor laser, thereby eliminating the risk of side leakage.

[0093] This application also provides a method for fabricating a semiconductor laser, used to form the aforementioned semiconductor laser. Please refer to... Figure 5 and Figures 6A-6J , Figure 5 This is a flowchart illustrating a method for fabricating a semiconductor laser according to an embodiment of this application. Figures 6A-6J This is a schematic cross-sectional view of each step in the manufacturing method of the semiconductor laser provided in this application embodiment. The manufacturing method of this semiconductor laser includes the following steps:

[0094] Step S11: Grow a stacked structure 200 on the substrate 100.

[0095] In actual production, the incoming bare wafers first need to be cleaned by sequentially cleaning them with acetone, isoacetone, and pure water, and then dried with nitrogen gas. Afterwards, the N-type confinement layer 201, the N-type waveguide layer 202, the quantum well layer 203, the P-type waveguide layer 204, the P-type confinement layer 205, and the ohmic contact layer 206 are sequentially grown on the substrate 100 to form the stacked structure 200. The N-type confinement layer 201 and the P-type confinement layer 205 work together to confine the charge carriers and optical field to the vicinity of the quantum well layer 203 located below the ridge waveguide 301 of the semiconductor laser. The materials of the N-type confinement layer 201 and the P-type confinement layer 205 are typically chosen to have a wider bandgap than the quantum well layer 203. Materials such as GaAs-based or InP-based materials are used. The N-type waveguide layer 202 is used to form an optical waveguide structure. The material of the N-type waveguide layer 202 is typically chosen to have a refractive index between that of the confinement layer and the quantum well layer 203. The quantum well layer 203 is the region where carrier recombination occurs and stimulated emission occurs. This structure can greatly improve the recombination efficiency and gain of carriers. The P-type waveguide layer 204 is symmetrically arranged with the N-type waveguide layer 202 to jointly form an optical waveguide structure. Its material selection is the same as that of the N-type waveguide layer 202. The ohmic contact layer 206 is located at the top of the stacked structure 200 and is used to form a good ohmic contact with the metal electrode of the semiconductor laser to reduce contact resistance and reduce heat generation. The material of each film layer is not limited here. The thickness of each film layer can also be selected according to actual needs, and its thickness is not limited here. Each film layer can be formed layer by layer using molecular beam epitaxy or metal-organic chemical vapor deposition. The formation method of each film layer is not limited here.

[0096] Step S12: A conductive region 300 is formed on the surface of the stacked structure 200, and first isolation grooves 400 are respectively etched on both sides of the conductive region 300 along the second direction, with the two first isolation grooves 400 being spaced apart from the conductive region 300.

[0097] Please see Figure 6A , Figure 6ATo form a semiconductor laser after performing step S12, the conductive region 300 and the first isolation trench 400 extending parallel to the first direction are formed on the top of the stacked structure 200 using photolithography and etching processes. Photoresist is spin-coated onto the surface of the stacked structure 200, and the pattern of the conductive region 300 is defined using laser direct writing exposure. The pattern is transferred to the surface of the ohmic contact layer 206 and the underlying semiconductor material using reactive ion etching to form protrusions. Simultaneously, a mask secondary alignment technique is used to etch at predetermined positions on both sides of the conductive region 300 to form the first isolation trench 400 penetrating the stacked structure 200 to the N-type confinement layer 201 or the substrate 100, and there is a strict physical distance between the first isolation trench 400 and the conductive region 300.

[0098] Step S13: A second isolation trench 500 is etched between the conductive region 300 and the first isolation trench 400. Simultaneously, a cleaving trench 600 is etched on the outer side of the first isolation trench 400 away from the conductive region 300. The extension depth of the first isolation trench 400 in the stacked structure 200 is greater than the extension depth of the second isolation trench 500 in the stacked structure 200, and the extension depth of the cleaving trench 600 in the stacked structure 200 is the same as the extension depth of the second isolation trench 500 in the stacked structure 200.

[0099] Please see Figure 6G , Figure 6G To form the semiconductor laser after performing step S13, a second isolation trench 500 is formed between the conductive region 300 and the first isolation trench 400 using photolithography and etching processes. Simultaneously, a cleaving trench 600 is formed on the outer side of the first isolation trench 400 away from the conductive region 300. The second isolation trench 500 and the cleaving trench 600 have the same etching depth in the stacking direction, extending to the ohmic contact layer 206 without touching the P-type confinement layer 205. Furthermore, the cleaving trench 600 and the first isolation trench 400 are strictly parallel in the second direction to ensure the integrity of the semiconductor laser resonator end face.

[0100] Using the fabrication method in this embodiment, a semiconductor laser as described in the above embodiments can be obtained. In this embodiment, the semiconductor laser fabrication method yields a semiconductor laser in which: in a first direction, the conductive region 300, the first isolation trench 400, and the second isolation trench 500 have the same depth, forming different continuous isolations surrounding the conductive region 300. This strictly constrains the carrier transport path to the ridge waveguide 301 in the central region of the conductive region 300, ensuring that the radiative recombination and luminescence process of carriers only occurs in the effective gain region of the quantum well layer 203, thereby improving the carrier recombination efficiency and current injection efficiency; in the first direction, the conductive region 300, the first isolation trench 400, and the second isolation trench 500 are arranged parallel to each other, and there is a strict physical interval between them. This physical spacing allows the conductive region 300, the second isolation trench 500, and the first isolation trench 400 to have a clear sequential arrangement in the second direction. In the stacking direction, the first isolation trench 400 extends into the N-type confinement layer 201, and the second isolation trench 500 extends into the ohmic contact layer 206. The second isolation trench 500 blocks the current on the surface and near the surface of the semiconductor laser, while the first isolation trench 400 forms current isolation in the deep layer of the semiconductor laser. The two work together to control and improve the control accuracy of current diffusion from the surface to the deep layer of the semiconductor laser, thereby greatly enhancing the effective carrier flux injected into the electric injection region and maximizing the excitation laser conversion efficiency.

[0101] Furthermore, prior to step S13, the following is also included:

[0102] Step S101: A first insulating film 701 of a first predetermined thickness is grown on the surface of the laminated structure 200, and the first insulating film 701 covers the surface of the conductive region 300 and the bottom and side walls of the first isolation groove 400. (See also...) Figure 6B , Figure 6B To form a semiconductor laser after performing step S101, a first insulating film 701 of a first predetermined thickness is grown on the surface of the stacked structure 200, the surface of the conductive region 300, and the bottom and sidewalls of the first isolation trench 400 using a deposition technique. The first predetermined thickness is 80nm-200nm, and the material of the first insulating film 701 can be SiO2 or SiN. x Any one of the materials with equal dielectric strength.

[0103] Step S102: Etch downwards from the first insulating film 701 formed at the center of the surface of the conductive region 300 to form the ridge waveguide 301. (See also...) Figure 6C , Figure 6CThis is for the semiconductor laser formed after performing step S102. After depositing and forming the first insulating film 701, the first insulating film 701 in the central region of the conductive region 300 needs to be etched to form an electrode opening, that is, to form the ridge waveguide 301. The etching depth is greater than the first preset thickness, that is, the first insulating film 701 in the central region of the conductive region 300 is completely etched away in this step.

[0104] Step S103: A first metal layer 702 is deposited on the surface of the stacked structure 200. The first metal layer 702 covers the first insulating film 701, and the first metal layer 702 covers the surface of the conductive region 300 and the bottom and side walls of the first isolation trench 400. Please refer to [link / reference]. Figure 6D , Figure 6D This is for the semiconductor laser formed after performing step S103. After etching the first insulating film 701 of the ridge waveguide 301, a metal vapor deposition is performed on the entire surface of the stacked structure 200 to cover the first metal layer 702. The first metal layer 702 covers the surface of the conductive region 300, the bottom wall and the side wall of the first isolation trench 400. It can be understood that the first metal layer 702 deposited in this step also covers the ridge waveguide 301 located at the center of the conductive region 300. The material of the first metal layer 702 can be any one of Au, Ti, Pt and their compounds.

[0105] Step S104: Thicken the first metal layer 702 on the surface of the conductive region 300. (See also...) Figure 6E , Figure 6E This is for the semiconductor laser formed after performing step S104. In this step, the surface of the already formed first metal layer 702 on the conductive region 300 is thickened using electrochemical electroplating or physical vapor deposition techniques, according to the law of resistance: In this context, R represents the resistance of the metal layer, ρ represents its resistivity, L represents its length, and A represents its cross-sectional area. It can be understood that the resistance R of the metal layer is directly proportional to its resistivity ρ and length L, and inversely proportional to its cross-sectional area A. The initially deposited first metal layer 702 is very thin, with a small cross-sectional area A, resulting in a large resistance R. When a large current passes through the semiconductor laser, a high voltage drop and heat will be generated on the thin metal layer, easily damaging the semiconductor laser. Therefore, it is necessary to thicken the first metal layer 702 on the surface of the conductive region 300 to increase its cross-sectional area A, thereby reducing its parasitic resistance. Simultaneously, metal is an excellent heat conductor; the thickened metal layer provides greater heat capacity and a wider heat conduction path, enabling faster heat conduction from the interior of the semiconductor laser, reducing the junction temperature of the semiconductor laser, and improving its reliability.

[0106] Step S105: A second metal layer 703 is deposited on the surface of the first metal layer 702 of the stacked structure 200, and the second metal layer 703 covers the surface of the conductive region 300 and the bottom and side walls of the first isolation trench 400. (See also...) Figure 6F , Figure 6F This is for the semiconductor laser formed after performing step S105. After thickening the first metal layer 702 on the surface of the conductive region 300, a full-surface metal vapor deposition is performed on the surface of the stacked structure 200 to cover the second metal layer 703. The second metal layer 703 covers the surface of the conductive region 300, the bottom wall and sidewalls of the first isolation trench 400. It can be understood that the second metal layer 703 deposited in this step also covers the ridge waveguide 301 located at the center of the conductive region 300. The material of the second metal layer 703 can be any one of Au, Ti, Pt and their compounds. After performing two metal vapor depositions, step S13 is performed to form the second isolation trench 500 and the cleavage trench 600. It is understood that the etching in step S13 is performed on the semiconductor laser formed after step S105. In step S13, the second metal layer 703 and the first metal layer 702 between the conductive region 300 and the first isolation trench 400 are etched. The etching depth is greater than the sum of the thicknesses of the first metal layer 702 and the second metal layer 703, but less than the sum of the thicknesses of the first metal layer 702, the second metal layer 703, and the first insulating film 701. At the same time, the cleavage trench 600 is etched to form on the outer side of the first isolation trench 400 away from the conductive region 300. The etching depth of the cleavage trench 600 is consistent with the etching depth of the second isolation trench 500.

[0107] In this embodiment, the first insulating film 701 is deposited on the stacked structure 200, the conductive region 300 (excluding the ridge waveguide 301), and the bottom and sidewalls of the first isolation trench 400 to form a basic passivation layer, thereby preventing unwanted lateral current diffusion inside the semiconductor laser. Furthermore, before the two metal evaporation depositions on the front side, the photolithography and development steps in the prior art are eliminated, allowing the first metal layer 702 and the second metal layer 703 to cover the entire surface of the stacked structure 200, the conductive region 300, and the bottom and sidewalls of the first isolation trench 400. This not only avoids the introduction of photoresist but also the need for further development. The use of organic materials such as liquids completely avoids the contamination problems caused by the residue of photoresist and developer in existing technologies, and further avoids the metal adhesion problems caused by the residue of contaminants, thus avoiding the reliability risks of semiconductor lasers caused by subsequent metal detachment. At the same time, by leaving the two layers of metal inside the first isolation trench 400 unetched, the problem of incomplete etching of the metal film caused by the non-horizontal or non-vertical structure of the isolation trench and the "bird's beak" protrusion at the top in existing technologies is directly avoided, thus avoiding the risk of the formation of unexpected electrical paths caused by metal residue, reducing the short circuit risk of semiconductor lasers, and improving the reliability of semiconductor lasers.

[0108] Furthermore, after step S13, the following is also included:

[0109] Step S106: A second insulating film 704 of a second predetermined thickness is grown on the surface of the second metal layer 703 of the laminated structure 200; the second insulating film 704 covers the surface of the conductive region 300, the bottom and side walls of the first isolation trench 400, the bottom and side walls of the second isolation trench 500, and the bottom and side walls of the cleavage trench 600. Please refer to... Figure 6H , Figure 6H To form a semiconductor laser after performing step S106, a second insulating film 704 of a second predetermined thickness is grown on the surface of the stacked structure 200, the surface of the conductive region 300, the bottom and sidewalls of the first isolation trench 400, the bottom and sidewalls of the second isolation trench 500, and the bottom and sidewalls of the cleavage trench 600 using a deposition technique. The second predetermined thickness is 80nm-200nm, and the material of the second insulating film 704 can be SiO2 or SiN. x Any one of the materials with equal dielectric strength.

[0110] In this embodiment, a second passivation layer is formed by depositing a second insulating film 704 to form a sealing medium layer that isolates external moisture penetration on the surface of the second metal layer 703 covering the bottom and side walls of the first isolation tank 400, thereby preventing moisture and particulate contaminants from contaminating the semiconductor laser. At the same time, a second insulating film 704 is formed on the bottom and side walls of the second isolation tank 500 to form electrical isolation, thereby cutting off the lateral current diffusion channels on and near the surface of the semiconductor laser.

[0111] Furthermore, after step S106, the method further includes:

[0112] Step S107: Etch the second insulating film 704 of the conductive region 300 and the cleavage trench 600, wherein the etching depth is greater than the second preset thickness and less than the sum of the first preset thickness and the second preset thickness. (See also...) Figure 6I , Figure 6I To form a semiconductor laser after performing step S107, after depositing a second insulating film 704 of a second preset thickness on the surface of the stacked structure 200, the surface of the conductive region 300, the bottom and sidewalls of the first isolation trench 400, the bottom and sidewalls of the second isolation trench 500, and the bottom and sidewalls of the cleavage trench 600, it is necessary to etch the second insulating film 704 on the surface of the conductive region 300 to expose the second metal layer 703 on the surface of the conductive region 300. The etching depth is greater than the second preset thickness and less than the sum of the first preset thickness and the second preset thickness.

[0113] Specifically, after step S105, etching is required between the conductive region 300 and the first isolation trench 400, and on the outer side of the first isolation trench 400 away from the conductive region 300, to form the second isolation trench 500 and the cleavage trench 600; that is, step S13 is performed. Please refer to [link to relevant documentation]. Figure 6F , Figure 6F To execute the semiconductor laser formed after step S105, in step S13, the first metal layer 702 and the second metal layer 703 between the conductive region 300 and the first isolation trench 400, and on the outer side of the first isolation trench 400 away from the conductive region 300, need to be over-etched. In this step, the first insulating film 701 at the bottom will also be etched. For example, assuming the first preset thickness is 100nm, and ignoring the thickness of the first metal layer 702 and the second metal layer 703, in step S13, the etching depth of the first insulating film 701 is 20nm. Therefore, after step S13, 80nm of the first insulating film 701 remains on the bottom wall of the second isolation trench 500 and the cleavage trench 600.

[0114] Please see Figure 6I , Figure 6I In order to form a semiconductor laser after performing step S107, the second insulating film 704 on the surface of the conductive region 300 and the bottom wall of the cleavage trench 600 needs to be etched in step S107. In order to fully expose the metal layer of the conductive region 300, but at the same time retain a very thin insulating film on the bottom wall of the cleavage trench 600, the etching depth of step S107 is greater than the second preset thickness and less than the sum of the first preset thickness and the second preset thickness. For example, assuming the second preset thickness is 100nm, after step S106, the sum of the thickness of the first insulating film 701 remaining on the bottom wall of the cleavage trench 600 and the deposited second insulating film 704 is 180nm. When performing step S107, if the etching depth of the second insulating film 704 is 130nm, it can be ensured that the second insulating film 704 on the surface of the conductive region 300 is completely etched, exposing the metal layer; at the same time, it ensures that 50nm of insulating film remains on the bottom wall of the cleavage trench 600.

[0115] In one embodiment, after step S107, the method further includes: step S108: thinning the bottom surface of the substrate 100, depositing metal to form a back metal, and annealing the second metal layer 703 on the surface of the conductive region 300 and the back metal to form the semiconductor laser described in the above structural embodiment. Please refer to... Figure 6I , Figure 6I For the semiconductor laser formed after performing step S107 in this embodiment of the application, the bottom surface of the substrate 100 is thinned after performing step S107. After the semiconductor laser is manufactured, the wafer thickness is usually relatively thick, which is not suitable for packaging. Therefore, thinning the bottom surface of the substrate 100 not only facilitates subsequent cleaving and packaging, but also improves the heat dissipation capacity of the semiconductor laser, avoiding damage to the semiconductor laser due to overheating, and can also reduce the bulk resistance of the substrate itself. A metal thin film is deposited on the bottom surface (i.e., the back side) of the thinned substrate 100 using physical vapor deposition processes such as vacuum evaporation or electron beam evaporation to form a back metal, so that the bottom surface of the substrate 100 forms a low-resistance, non-rectified ohmic contact. Annealing is performed on the semiconductor laser with the back metal layer formed. Through heat treatment, the second metal layer 703 on the surface of the conductive region 300 melts, causing the back metal to react with the substrate 100 and form a good ohmic contact. The molten second metal layer 703 can diffuse with the back metal, and after cooling, forms a strong eutectic bonding interface with high thermal and electrical conductivity, ultimately forming a complete semiconductor laser device. Figure 6JThis is the complete semiconductor laser device formed after performing step S108.

[0116] In this embodiment, the etching time and etching depth of the insulating film are controlled to ensure that the insulating film on the surface of the conductive region 300 is completely etched, exposing the bottom metal layer. At the same time, an insulating film with a thickness of 20nm-50nm remains in the cleavage trench 600. The thickness of the insulating film remaining in the cleavage trench 600 is thin enough that it will not cause abnormal stress or fracture during the cleavage process, thereby avoiding a decrease in the quality of the cleavage surface or the generation of a large number of dust particles that would harm the optical properties of the semiconductor laser cavity surface. Furthermore, it can form effective physical and electrochemical isolation in the cleavage trench 600. The retained insulating film will not affect the normal cleavage of the chip, and it can completely cover the exposed semiconductor material on the sidewalls and bottom of the cleavage trench 600. This not only effectively prevents moisture and ionic contaminants from directly contacting and penetrating into the exposed semiconductor material and causing contamination, but also forms electrical isolation in the cleavage trench, reducing and avoiding the problem of side leakage.

[0117] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application. It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0118] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A semiconductor laser, characterized by, The semiconductor laser comprises: a substrate (100); a laminated structure (200) disposed above the substrate (100), the laminated structure (200) comprising at least an ohmic contact layer (206) disposed at the topmost layer of the laminated structure (200) and an N-type confinement layer (201) disposed at the bottommost layer of the laminated structure (200); a conductive region (300) formed on the top of the laminated structure (200), the conductive region (300) extending along a first direction, the first direction being the extension direction of the cavity length of the semiconductor laser; a first isolation groove (400) formed on the top of the laminated structure (200) and on both sides of the conductive region (300) in a second direction, the second direction being in the same horizontal plane as the first direction and perpendicular to the first direction; a second isolation groove (500) formed on the top of the laminated structure (200) and between the conductive region (300) and the first isolation groove (400) in the second direction; wherein the first isolation groove (400) extends to the N-type confinement layer (201) or the substrate (100); and the second isolation groove (500) extends to the ohmic contact layer (206).

2. The semiconductor laser of claim 1, wherein, The center line of the first isolation groove (400) and the center line of the second isolation groove (500) are arranged in parallel along the first direction.

3. The semiconductor laser of claim 1, wherein, The surface of the conductive region (300) is covered with a first metal layer (702) and a second metal layer (703); The bottom wall and the side wall of the first isolation groove (400) are both provided with a first insulating film (701), the first metal layer (702), the second metal layer (703) and a second insulating film (704) stacked; wherein the first metal layer (702) and the second metal layer (703) covering the surface of the conductive region (300) extend to the first isolation groove (400) and cover the bottom wall and the side wall of the first isolation groove (400).

4. The semiconductor laser of claim 3, wherein, The bottom wall of the second isolation groove (500) is provided with the first insulating film (701) and the second insulating film (704) stacked; the side wall of the second isolation groove (500) is provided with a layer of the second insulating film (704); wherein the first insulating film (701) and the second insulating film (704) stacked in the first isolation groove (400) extend to the second isolation groove (500) and cover the bottom wall of the second isolation groove (500).

5. The semiconductor laser of claim 4, wherein, The semiconductor laser further comprises a cleaving groove (600); The cleaving groove (600) is disposed outside the first isolation groove (400) away from the conductive region (300), and the extension depth of the cleaving groove (600) in the laminated structure (200) is consistent with the extension depth of the second isolation groove (500) in the laminated structure (200); wherein the bottom wall of the cleaving groove (600) is provided with a layer of the first insulating film (701), and the thickness of the first insulating film (701) is 20-50 nm. The side wall of the cleaving groove (600) has a layer of the second insulating film (704); The first insulating film (701) and the second insulating film (704) of the first isolation groove (400) are extended to the cleaving groove (600) and cover the cleaving groove (600).

6. The semiconductor laser of claim 1, wherein, The conductive region (300) further comprises a ridge waveguide (301); The ridge waveguide (301) is arranged at the center position of the conductive region (300), and the extension lengths of the ridge waveguide (301) in the first direction and the second direction are respectively less than the extension lengths of the conductive region (300) in the first direction and the second direction.

7. A method for producing a semiconductor laser for forming a semiconductor laser as claimed in any one of the preceding claims 1 to 6, characterized in that The preparation method of the semiconductor laser comprises the following steps: Step S11: growing a laminated structure (200) on a substrate (100); Step S12: forming a conductive region (300) on the surface of the laminated structure (200), and etching a first isolation groove (400) on both sides of the conductive region (300) in a second direction, respectively, two first isolation grooves (400) being arranged apart from the conductive region (300), respectively; Step S13: etching a second isolation groove (500) between the conductive region (300) and the first isolation groove (400), and etching a cleaving groove (600) on the outer side of the first isolation groove (400) away from the conductive region (300); The extension depth of the first isolation groove (400) in the laminated structure (200) is greater than the extension depth of the second isolation groove (500) in the laminated structure (200), and the extension depth of the cleaving groove (600) in the laminated structure (200) is consistent with the extension depth of the second isolation groove (500) in the laminated structure (200).

8. The method of claim 7, wherein the semiconductor laser is a distributed feedback semiconductor laser. Before the step S13, it further comprises: Step S101: growing a first insulating film (701) with a first preset thickness on the surface of the laminated structure (200), and the first insulating film (701) covers the surface of the conductive region (300) and the bottom wall and the side wall of the first isolation groove (400); Step S102: etching from the first insulating film (701) formed at the center position of the surface of the conductive region (300) downward to form a ridge waveguide (301); Step S103: evaporating a first metal layer (702) on the surface of the laminated structure (200), the first metal layer (702) being covered on the first insulating film (701), and the first metal layer (702) covering the surface of the conductive region (300) and the bottom wall and the side wall of the first isolation groove (400); Step S104: thickening the first metal layer (702) on the surface of the conductive region (300); Step S105: evaporating a second metal layer (703) on the surface of the first metal layer (702) of the laminated structure (200), and the second metal layer (703) covers the surface of the conductive region (300) and the bottom wall and sidewall of the first isolation groove (400).

9. The method of claim 8, wherein the semiconductor laser is a vertical cavity surface emitting laser (VCSEL). After the step S13, it further includes: Step S106: growing a second insulating film (704) with a second preset thickness on the surface of the second metal layer (703) of the laminated structure (200); The second insulating film (704) covers the surface of the conductive region (300), the bottom wall and sidewall of the first isolation groove (400), the bottom wall and sidewall of the second isolation groove (500), and the bottom wall and sidewall of the cleaving groove (600).

10. The method of claim 9, wherein the semiconductor laser is a distributed feedback semiconductor laser. After the step S106, it further includes: Step S107: etching the second insulating film (704) of the conductive region (300) and the cleaving groove (600), and the etching depth is greater than the second preset thickness and less than the sum of the first preset thickness and the second preset thickness; Step S108: thinning the bottom surface of the substrate (100), evaporating metal to form a back metal, and annealing the second metal layer (703) on the surface of the conductive region (300) and the back metal to form the semiconductor laser.

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