Edge emitting laser structure and preparation method thereof

Abstract

The invention relates to the technical field of lasers, and discloses an edge-emitting laser structure and a preparation method thereof. The preparation method comprises the steps that an epitaxial structure comprising a first limiting layer, a first waveguide layer, an active layer, a second waveguide layer and a second limiting layer is formed on the surface of one side of a substrate layer, and the surface of the epitaxial structure comprises a first area and a second area surrounding the first area; ion implantation is carried out on one side of the epitaxial structure, an ion implantation region penetrating through the second limiting layer, the second waveguide layer and the active layer is formed in the epitaxial structure of the second region along the edges of the two sides of the first direction, and a current implantation region spaced from the ion implantation region in the first direction is formed in the epitaxial structure of the first region. The ion injection region can improve the current injection efficiency, effective electrical isolation is formed on the outer side wall surface, and short-circuit failure caused by solder climbing during packaging is avoided; and the surface of the epitaxial structure is still a flat surface, so that welding holes are avoided, and the packaging stability and performance of the edge-emitting laser structure are ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of lasers, and particularly relates to a structure of an edge-emitting laser and a preparation method thereof. Background Art

[0002] A semiconductor laser is a device that uses a semiconductor material as a gain medium and realizes light emission by relying on the transition between the energy bands of the material. Due to its characteristics such as small volume, stable structure, wide wavelength coverage range, and good reliability, it has been widely used in multiple fields such as optical communication, laser medicine, and industrial processing. Research shows that when a semiconductor laser works, about half of the electrical energy is converted into heat energy. With the increasing requirement for the output power of the laser, the heat dissipation problem has become one of the urgent problems to be solved. Poor heat dissipation will directly affect the life and performance of the semiconductor laser.

[0003] In a semiconductor laser, the heat generation of the laser structure is mainly concentrated in the active region on the surface of the chip within a few micrometers. To reduce the heat dissipation distance from the laser structure to the heat sink, the flip-chip bonding technology is generally used to directly connect the surface of the laser structure to the heat sink. In this way, the heat dissipation capacity of the laser structure can be increased by at least 20%, and at the same time, the performance can be greatly improved. However, during this packaging process, the solder is easily extruded and overflows to climb on the side wall of the laser structure. The thickness of the epitaxial layer on the surface of the laser structure is relatively small, and the climbing of the solder easily causes external electrical connection and short circuit of the epitaxial layer, resulting in the laser structure being unable to work normally and being easily burned out at this place, leading to the failure of the laser structure; at the same time, the flip-chip bonding technology is that the upper surface of the laser structure contacts the heat sink. The conventional edge-emitting laser structure is set as a wide-ridge structure, and there are relatively deep etching grooves on both sides of the ridge waveguide, making the upper surface of the laser structure present an uneven morphology, which is not conducive to the discharge of air between the laser structure and the heat sink during the packaging process, and it is easy to appear welding voids, thereby affecting the thermal conductivity and stability of the laser structure, resulting in the problem of the risk of failure of the laser structure. Summary of the Invention

[0004] In view of this, the present invention provides a structure of an edge-emitting laser and a preparation method thereof to solve the problems that solder climbs and welding voids occur during the packaging process of the existing semiconductor laser, resulting in the failure of the semiconductor laser.

[0005] In a first aspect, the present invention provides a preparation method of a structure of an edge-emitting laser, including:

[0006] Form an epitaxial structure on one side surface of a substrate layer. The epitaxial structure includes a first confinement layer, a first waveguide layer, an active layer, a second waveguide layer, and a second confinement layer that are stacked on the substrate layer; the surface of the epitaxial structure includes a first region and a second region surrounding the first region;

[0007] Ion implantation is performed on the side of the epitaxial structure away from the substrate layer to form ion implantation regions on both side edges of the epitaxial structure in the second region along the first direction, and the ion implantation regions penetrate at least the second confinement layer, the second waveguide layer, and the active layer; a current injection region is formed in the epitaxial structure of the first region, and there is a spacing distance between the current injection region and the ion implantation region in the first direction.

[0008] Beneficial effects: In the preparation method of the edge-emitting laser structure of the present invention, ion implantation is performed on the surface of the epitaxial structure away from the substrate layer to form ion implantation regions on both side edges of the epitaxial structure in the first direction, which penetrate the second confinement layer, the second waveguide layer, and the active layer. A current injection region having a spacing from the ion implantation regions is suitable to be formed between the ion implantation regions on both sides in the first direction. The formation of the ion implantation regions does not affect the internal structural performance of the current injection region, and at the same time, the formed high-resistance region can further improve the current injection efficiency and enhance the light output efficiency of the laser. More importantly, in the first direction, the outer surface of the ion implantation region forms an effective electrical isolation on the outer side wall surface of the edge-emitting laser structure, avoiding the short-circuit failure problem caused by solder climbing during flip-chip packaging; moreover, the formation of the ion implantation region does not change the surface topography of the surface of the epitaxial structure away from the substrate layer, and the surface of the epitaxial structure away from the substrate layer is still a flat surface. When flip-chip packaging the edge-emitting laser structure onto the heat sink surface, the solder will not have welding voids due to the uneven welding surface, facilitating the discharge of gas during the packaging process, ensuring the packaging stability and performance of the edge-emitting laser structure, and extending the service life.

[0009] In an optional implementation manner, in the first direction, the range of the spacing distance between the current injection region and the ion implantation region is 20 μm to 25 μm.

[0010] Beneficial effects: The spacing distance is set between 20 μm and 25 μm to reserve the influence of the channeling effect of ion implantation and the ion diffusion after annealing on the laser performance, ensuring the current injection requirement of the edge-emitting laser structure, that is, the stripe width requirement. If the distance is too small, the lateral ion diffusion caused by ion implantation may affect the performance of the current injection region; if the distance is too large, it is not conducive to the lateral confinement of the lateral current. The ion implantation regions are set up to the edge of the edge-emitting laser structure to form electrical isolation on the outer side wall surface, avoiding the formation of a short circuit due to the PN connection of the epitaxial layer caused by solder. Using ion implantation to replace the traditional ridge waveguide trench etching can not only play the role of current confinement of the ridge waveguide trench, but also avoid the unevenness of the chip surface caused by deep trenches, which is beneficial to the discharge of air between the laser structure and the heat sink during the packaging process, reducing the probability of void formation, and enhancing the thermal conductivity and packaging stability of the device.

[0011] In an optional implementation manner, performing ion implantation on the side of the epitaxial structure away from the substrate layer includes:

[0012] A first mask layer is formed on one surface of the epitaxial structure facing away from the substrate layer. The first mask layer covers the surface of the first region and part of the surface of the second region, so as to expose the edge regions on both sides in the first direction;

[0013] Ion implantation is performed on the surface of the epitaxial structure exposed by the first mask layer, so as to form ion implantation regions penetrating through the second confinement layer, the second waveguide layer and the active layer in the edge regions on both sides of the epitaxial structure in the first direction;

[0014] Remove the first mask layer;

[0015] Anneal the epitaxial structure after ion implantation.

[0016] Beneficial effects: By setting the first mask layer to protect the current region that does not need ion implantation and the interval part between the current injection region and the ion implantation region, accurate ion implantation is achieved, and at the same time, the internal performance of the current injection region is ensured. After three times of ion implantation and removing the first mask layer, it is also necessary to anneal the whole epitaxial structure to improve the impurity distribution uniformity in the ion implantation region and reduce the defects in the ion implantation region.

[0017] In an optional implementation manner, ion implantation is performed on one side of the epitaxial structure facing away from the substrate layer, including: performing multiple ion implantations on the edge regions on one side of the epitaxial structure facing away from the substrate layer in the first direction, and the implantation energies of the multiple ion implantations decrease in sequence.

[0018] Beneficial effects: Multiple ion implantations are performed on the surface of the epitaxial structure exposed by the first mask layer. Through multiple ion implantations, the depth of ion implantation can be accurately controlled, and at the same time, the ion concentration change of each part of the ion implantation region in the depth direction can be made gentle, ensuring the current lateral confinement effect on the inner side and the electrical isolation effect on the outer side.

[0019] In an optional implementation manner, an epitaxial structure is formed on one surface of the substrate layer, including: sequentially laminating and forming a first confinement layer, a first waveguide layer, an active layer, a second waveguide layer, a second confinement layer and a contact layer on the substrate layer;

[0020] After forming the epitaxial structure on one surface of the substrate layer and before performing ion implantation on one side of the epitaxial structure facing away from the substrate layer, it further includes: etching and removing at least part of the thickness of the contact layer located in the second region, so that part of the contact layer in the second region forms a positioning protrusion.

[0021] Beneficial effects: The contact resistance between the contact layer and the first limiting layer is small, which is convenient for forming a good ohmic contact; a positioning protrusion is formed on the part of the contact layer located in the first area corresponding to the current injection area, which is convenient for forming the subsequent first mask layer alignment mark point and controlling the current path, which helps to reduce the current injection of the front and rear cavity surfaces, and perform precise electrode setting and current injection, thereby reducing non-radiative recombination, reducing the temperature at the cavity surface, increasing the optical catastrophic damage threshold, and improving the photoelectric conversion efficiency.

[0022] In an optional embodiment, multiple ion implantations are performed on an edge region of the epitaxial structure facing away from the substrate layer in the first direction, including:

[0023] The first ion implantation is performed on the edge region of the epitaxial structure in the first direction away from the substrate layer. The implantation energy of the first ion implantation is 170 KeV and the implanted ion dose is 3.0E+15 cm -2 ;

[0024] A second ion implantation is performed on the edge region of the epitaxial structure in the first direction away from the substrate layer. The implantation energy of the second ion implantation is 90 KeV and the implanted ion dose is 3.0E+15 cm -2 ;

[0025] The third ion implantation is performed on the edge region of the epitaxial structure in the first direction away from the substrate layer. The implantation energy of the third ion implantation is 15 KeV, and the implanted ion dose is 3.0E+14 cm -2 .

[0026] Beneficial effect: three times of ion implantation with determined process parameters form an ion implantation area with a smooth transition of ion concentration in the vertical direction, and the energy of multiple ion implantations decreases, so that different ion areas are connected to each other and can maintain relative stability of their own performance.

[0027] In an optional embodiment, the thickness of the second waveguide layer is less than the thickness of the first waveguide layer to form an epitaxial structure with an asymmetric large optical cavity.

[0028] Beneficial effects: The epitaxial structure forms an optical resonant cavity with an asymmetric large optical cavity design, the thickness of the second waveguide layer is less than that of the first waveguide layer, the peak light intensity deviates from the active layer, and a larger catastrophic optical damage threshold optical power is allowed, and the edge-emitting laser structure realizes high-power light output.

[0029] In an optional embodiment, after ion implantation is performed on the side of the epitaxial structure facing away from the substrate layer, the method further includes: forming a passivation layer on the surface of the side of the epitaxial structure facing away from the substrate layer, wherein the passivation layer at least covers the surface of the second region to expose the current injection region in the first region.

[0030] Beneficial effects: The passivation layer forms a window on the positioning protrusion and covers the surfaces of other areas, which can further ensure the accuracy of current injection into the current injection area below the positioning protrusion.

[0031] In an alternative embodiment, after forming the passivation layer on the surface of the epitaxial structure facing away from the substrate layer, it further includes:

[0032] Forming a first electrode on the surface of the epitaxial structure facing away from the substrate layer, and the first electrode is connected to the surface of the current injection area;

[0033] Forming a second electrode on the surface of the substrate layer facing away from the epitaxial structure.

[0034] Beneficial effects: Setting the first electrode and the second electrode realizes the encapsulation of the electrical connection between the edge-emitting laser structure and other external structures, and realizes the finished product application.

[0035] In an alternative embodiment, after forming the passivation layer on the surface of the epitaxial structure facing away from the substrate layer, and before forming the first electrode on the surface of the epitaxial structure facing away from the substrate layer, it further includes: forming a seed layer on the surface of the epitaxial structure facing away from the substrate layer, and the first electrode is formed on the surface of the seed layer facing away from the substrate layer;

[0036] After forming the first electrode on the surface of the epitaxial structure facing away from the substrate layer, and before forming the second electrode on the surface of the substrate layer facing away from the epitaxial structure, it further includes: thinning the surface of the substrate layer facing away from the epitaxial structure.

[0037] Beneficial effects: Setting a seed layer between the first electrode and the contact layer helps to further improve the connection reliability between the relatively thick first electrode and the contact layer, reduce the surface contact resistance of the direct connection between the first electrode and the contact layer, and improve the current injection efficiency. The second electrode on one side of the substrate layer needs to achieve electrical communication through the substrate layer and the epitaxial structure. If the substrate layer is too thick, it is not conducive to heat dissipation and subsequent cleavage cutting. Therefore, thinning the substrate layer before forming the second electrode can improve the electrical connection efficiency and facilitate efficient electrical conduction.

[0038] In an alternative embodiment, in the step of forming the epitaxial structure on one side surface of the substrate layer, the epitaxial structure and the substrate layer form a laser chip, the laser chip includes a plurality of laser bars arranged at intervals along a second direction, and any one of the laser bars includes a plurality of edge-emitting laser structures arranged at intervals along a first direction, and the second direction is perpendicular to the first direction; the edge-emitting laser structure has a first cavity surface and a second cavity surface arranged oppositely in the second direction, and the first cavity surface is used for laser emission.

[0039] Beneficial effects: The substrate layer and the epitaxial structure can include a plurality of array edge-emitting laser structures, so as to facilitate the batch formation of a plurality of edge-emitting laser structures quickly.

[0040] In an alternative embodiment, after forming the second electrode on the surface of the substrate layer facing away from the epitaxial structure, the following steps are further included:

[0041] Cleaving the laser chip into a plurality of laser bars along a first direction;

[0042] Forming an antireflection film layer and a high-reflection film layer on opposite side surfaces of the laser bar along a second direction;

[0043] Cleaving the laser bar into a plurality of edge-emitting laser structures along the second direction.

[0044] Beneficial effects: The antireflection film is disposed on the surface of the laser bar for light emission, and the high-reflection film layer is disposed on the opposite surface relative to the antireflection film layer. After forming the antireflection film layer and the high-reflection film layer on the laser bar and then cleaving and forming the edge-emitting laser structure, it helps to simplify the preparation of the cavity film, improve the preparation efficiency and consistency. Cutting is performed in the cleavage groove extending along the second direction between adjacent edge-emitting laser structures in the laser bar to form a plurality of edge-emitting laser structures. The outer wall surfaces of each edge-emitting laser structure opposite to each other in the first direction both include the outer wall surfaces of the ion implantation regions; an antireflection film layer is disposed on the first cavity surface in the second direction to improve the laser output efficiency, and a high-reflection film layer is disposed on the second cavity surface to improve the reflection of the laser in the resonant cavity, so that more laser light exits from the side of the first cavity surface.

[0045] In a second aspect, the present invention further provides an edge-emitting laser structure, including a substrate layer, an epitaxial structure, and an ion implantation region. The epitaxial structure is disposed on one surface of the substrate layer and includes a first confinement layer, a first waveguide layer, an active layer, a second waveguide layer, and a second confinement layer stacked on the substrate layer. The surface of the epitaxial structure includes a first region and a second region surrounding the first region; the ion implantation region is formed at both side edges along the first direction in the epitaxial structure of the second region, and a current injection region is formed in the epitaxial structure of the first region. The ion implantation region penetrates at least the second confinement layer, the second waveguide layer, and the active layer, and there is a gap between the current injection region and the ion implantation region in the first direction.

[0046] Beneficial effects: In the edge-emitting laser structure of the present invention, ion implantation regions penetrating through the second confinement layer, the second waveguide layer, and the active layer are formed on both side edges of the epitaxial structure in the first direction. A current injection region having a gap with the ion implantation regions is adapted to be formed between the ion implantation regions on both sides in the first direction. The ion implantation regions do not affect the internal structural performance of the current injection region. At the same time, the formed high-resistance ion implantation regions can further improve the current injection efficiency and enhance the light output efficiency of the laser. More importantly, in the first direction, the outer side surfaces of the ion implantation regions form effective electrical isolation on the outer side wall surface of the edge-emitting laser structure, avoiding the short-circuit failure problem caused by solder climbing during flip-chip packaging; moreover, the formation of the ion implantation regions does not change the surface topography of the side surface of the epitaxial structure away from the substrate layer, and the side surface of the epitaxial structure away from the substrate layer remains a flat surface. When flip-chip packaging the edge-emitting laser structure onto the surface of the heat sink, the solder will not have welding voids due to the uneven welding surface, facilitating the discharge of gases during the packaging process, ensuring the packaging stability and performance of the edge-emitting laser structure, and extending the service life.

[0047] In an alternative embodiment, the epitaxial structure further includes: a contact layer disposed on the side surface of the second confinement layer facing away from the substrate layer, and the side of the contact layer facing away from the substrate layer has a positioning protrusion in the first region.

[0048] Beneficial effects: The positioning protrusions formed by the part of the contact layer corresponding to the current injection region in the first region facilitate the formation of subsequent alignment mark points of the first mask layer and the control of the current path, help reduce the current injection at the front and rear cavity surfaces, perform precise electrode setting and current injection, thereby reducing non-radiative recombination, lowering the temperature at the cavity surface, increasing the optical catastrophic damage threshold, and improving the photoelectric conversion efficiency.

[0049] In an alternative embodiment, it further includes a passivation layer, a seed layer, a first electrode, a second electrode, an antireflection film layer, and a high-reflection film layer. The passivation layer is disposed on the side surface of the epitaxial structure facing away from the substrate layer, and the passivation layer covers at least the second region of the epitaxial structure to expose the current injection region in the first region; the seed layer is disposed on the side surface of the epitaxial structure facing away from the substrate layer, and the seed layer is adapted to be connected to the positioning protrusion in the first region; the first electrode is disposed on the side surface of the seed layer facing away from the substrate layer; the second electrode is disposed on the side surface of the substrate layer facing away from the epitaxial structure; the antireflection film layer is disposed on the first cavity surface. The edge-emitting laser structure has opposite first and second cavity surfaces in the second direction, and the second direction is perpendicular to the first direction; the high-reflection film layer is disposed on the second cavity surface.

[0050] Beneficial effects: The passivation layer is made of a low-stress silicon nitride thin film, forms a window on the positioning protrusion, and covers other areas of the surface of the epitaxial structure, which can improve the accuracy of current injection. The first electrode and the second electrode are provided to achieve the electrical connection and encapsulation of the edge-emitting laser structure with other external structures, realizing the finished product application. A seed layer is provided between the first electrode and the contact layer, which helps to further improve the connection reliability between the relatively thick first electrode and the contact layer, reduce the surface contact resistance of the direct connection between the first electrode and the contact layer, and improve the current injection efficiency. An antireflection film layer is provided on the first cavity surface in the second direction to improve the laser output efficiency, and a high-reflection film layer is provided on the second cavity surface to improve the reflection of the laser in the resonant cavity, so that more laser light exits from the side of the first cavity surface, thereby improving the laser output efficiency of the laser. Description of the Drawings

[0051] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0052] Figure 1 is a schematic flow chart of the preparation method of the edge-emitting laser according to the embodiment of the present invention;

[0053] Figure 2 is a schematic structural diagram after forming an epitaxial structure on a substrate layer according to the embodiment of the present invention;

[0054] Figure 3 is a schematic structural diagram after forming a positioning protrusion on a contact layer according to the embodiment of the present invention;

[0055] Figure 4 is Figure 3 a top view schematic diagram of the corresponding edge-emitting laser structure after forming the positioning protrusion;

[0056] Figure 5 is a schematic structural diagram after forming a first mask layer on a contact layer according to the embodiment of the present invention;

[0057] Figure 6 is a schematic structural diagram after ion implantation according to the embodiment of the present invention;

[0058] Figure 7 is Figure 6 a top view schematic diagram of the corresponding edge-emitting laser structure after ion implantation;

[0059] Figure 8 is a schematic diagram of the ion concentration distribution after three times of ion implantation according to the embodiment of the present invention;

[0060] Figure 9 It is a schematic structural diagram after forming a passivation layer on the epitaxial structure in an embodiment of the present invention;

[0061] Figure 10 is Figure 9 A top view schematic diagram of the edge-emitting laser structure after forming the corresponding passivation layer;

[0062] Figure 11 It is a schematic structural diagram after forming a seed layer on the epitaxial structure in an embodiment of the present invention;

[0063] Figure 12 It is a schematic structural diagram after forming the first electrode in an embodiment of the present invention;

[0064] Figure 13 is Figure 12 A top view schematic diagram of the edge-emitting laser structure after forming the corresponding first electrode;

[0065] Figure 14 It is a top view schematic diagram of the laser chip in an embodiment of the present invention;

[0066] Figure 15 It is a schematic structural diagram of the edge-emitting laser structure in the first direction in an embodiment of the present invention;

[0067] Figure 16 is Figure 15 A schematic structural diagram of the corresponding edge-emitting laser structure in the second direction.

[0068] Description of reference numerals:

[0069] 100, laser chip; 101, laser bar; 10, edge-emitting laser structure; 11, first cavity surface; 12, second cavity surface;

[0070] 1, substrate layer;

[0071] 2, epitaxial structure; 201, first confinement layer; 202, first waveguide layer; 203, active layer; 204, second waveguide layer; 205, second confinement layer; 206, contact layer; 2061, positioning protrusion; 207, first region; 208, second region;

[0072] 3, ion implantation region; 301, first ion implantation; 302, second ion implantation; 303, third ion implantation;

[0073] 4, current injection region;

[0074] 5, passivation layer;

[0075] 61, first electrode; 611, cleavage groove; 62, second electrode;

[0076] 7. Seed layer;

[0077] 81. Anti-reflection film layer; 82. High-reflection film layer;

[0078] 91. First mask layer; 92. Second mask layer. Detailed implementation manners

[0079] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. In addition, it should be noted that, for the sake of description, only the parts related to the present invention rather than all the structures are shown in the accompanying drawings. In the following description, the description of well-known structures and technologies is omitted to avoid unnecessarily confusing the concepts of the present invention. Various structural schematic diagrams according to the embodiments of the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and for the purpose of clear expression, some details are enlarged and some details may be omitted. The shapes of various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are only exemplary. In practice, there may be deviations due to manufacturing tolerances or technical limitations, and those skilled in the art can design regions / layers with different shapes, sizes, and relative positions according to actual needs. In the context of the present invention, when a layer / element is referred to as being "on" another layer / element, the layer / element can be directly on the other layer / element, or there can be an intermediate layer / element between them. In addition, if a layer / element is "on" another layer / element in one orientation, then when the orientation is reversed, the layer / element can be "under" the other layer / element.

[0080] In the related art, the laser structure is fixed on the heat sink substrate through flip-chip bonding technology for packaging. The surface of the laser structure is directly connected to the heat sink, reducing the heat dissipation distance from the laser structure to the heat sink. The heat dissipation capacity of the laser structure can be increased by at least 20%, and at the same time, the performance of the laser structure is greatly improved. However, during the flip-chip packaging process, the solder is easily extruded and climbs up the side wall of the laser structure. Since the thickness of the epitaxial layer on the surface of the laser structure is only a few micrometers, the climbing of the solder can easily cause the PN connection and short circuit of the epitaxial layer, resulting in the laser structure being unable to work normally and being easily burned out, ultimately causing the failure of the laser structure; moreover, conventional high-power edge-emitting lasers usually have a wide-ridge structure, and there are etching grooves on both sides of the ridge structure, making the upper surface of the laser structure present an uneven morphology. It is difficult to discharge the air between the laser structure and the heat sink during the packaging process, and welding voids are likely to appear, thus affecting the thermal conductivity and stability of the laser structure and increasing the failure risk of the laser structure.

[0081] Based on this, referring to Figures 1 to 16 , this embodiment provides a method for preparing an edge-emitting laser structure, Figure 1Schematic flow chart of the unmodified preparation method, which includes the following steps:

[0082] Step S101, an epitaxial structure 2 is formed on one side surface of the substrate layer 1. The epitaxial structure 2 includes a first confinement layer 201, a first waveguide layer 202, an active layer 203, a second waveguide layer 204, and a second confinement layer 205 that are stacked on the substrate layer 1. The surface of the epitaxial structure 2 includes a first region 207 and a second region 208 that surrounds the first region 207.

[0083] Exemplarily, referring to Figure 2 , the above-mentioned substrate layer 1 is made of a gallium arsenide substrate, and the substrate layer 1 is set to an N-type conductivity type. Each structural layer of the epitaxial structure 2 is epitaxially grown in sequence on one side surface of the substrate layer 1. Among them, the first confinement layer 201 of the epitaxial structure 2 is aluminum gallium arsenide with a thickness between 2 μm and 3 μm, the first waveguide layer 202 is aluminum gallium arsenide with a thickness between 0.9 μm and 1.1 μm, the active layer 203 adopts a strained quantum well structure, the second waveguide layer 204 adopts aluminum gallium arsenide with a thickness between 0.2 μm and 0.4 μm, and the second confinement layer 205 adopts aluminum gallium arsenide with a thickness between 0.5 μm and 0.7 μm. Referring to Figure 3 and Figure 4 , on one side of the upper surface of the epitaxial structure 2, it is divided into a first region 207 and a second region 208 that surrounds the first region 207, so as to set different functional regions in the epitaxial structure 2 corresponding to the first region 207 and the second region 208. In this embodiment, the first region 207 is located at the center position of the surface of the epitaxial structure 2, and each of its edges has a certain distance from the edge of the epitaxial structure 2. Preferably, the distances between the edges of the first region 207 on the opposite sides and the edge of the epitaxial structure 2 are equal, that is, the widths of the second regions 208 on both sides of the first region 207 on the surface of the epitaxial structure 2 are equal. For example, in the first direction, the widths of the second regions 208 on both sides of the first region 207 are equal.

[0084] Step S102, ion implantation is performed on the side of the epitaxial structure 2 facing away from the substrate layer 1, so as to form ion implantation regions 3 along the two side edges in the first direction in the epitaxial structure 2 of the second region 208. The ion implantation regions 3 penetrate at least through the second confinement layer 205, the second waveguide layer 204, and the active layer 203. A current injection region 4 is formed in the epitaxial structure 2 of the first region 207. In the first direction, there is a spacing distance between the current injection region 4 and the ion implantation regions 3.

[0085] Referring to Figures 5 to 7, Exemplarily, a patterned first mask layer 91 can be disposed on one side of the upper surface of the epitaxial structure 2. When ion implantation is performed on one side of the upper surface of the epitaxial structure 2, an ion implantation region 3 is formed in the epitaxial structure 2 not covered by the first mask layer 91. The ion implantation region 3 extends from the second confinement layer 205 through the second waveguide layer 204 and the active layer 203 until it reaches the surface of the first waveguide layer 202. For example, it extends to a thickness of 0.1 μm to 0.2 μm on the surface of the first waveguide layer 202. The formed ion implantation region 3 passes through the active layer 203, reducing the recombination of photons in the active layer 203 on the opposite sidewall surfaces in the first direction in the active region, effectively improving the injection efficiency of the current injection region 4, and ensuring the light output efficiency of the device. The first direction in this embodiment is the direction opposite to the left and right sidewalls of the edge-emitting laser structure 10, and the light-emitting direction of the edge-emitting laser is the direction opposite to the front and rear cavity surfaces on the horizontal plane. That is, on the horizontal plane, the first direction is perpendicular to the light-emitting direction.

[0086] Based on the above solution, on the one hand, the ion implantation region 3 in this embodiment is formed in the epitaxial structure 2 of the second region 208 and is located at the edge position of the second region 208 relatively far from the first region 207 in the first direction. That is, in the first direction, a set of outer sidewall surfaces of the ion implantation region 3 constitutes a part of a set of outer sidewall surfaces of the epitaxial structure 2, forming an effective electrical isolation on the outer sidewall surface of the edge-emitting laser structure 10 and avoiding the short-circuit failure problem caused by solder climbing during flip-chip packaging; moreover, high-resistance regions of the epitaxial structure 2 are formed relatively by the ion implantation regions 3 at both edges in the first direction, and a low-resistance region is formed relatively by the epitaxial structure 2 between the ion implantation regions 3. The current injection region 4 is suitable for being formed in the low-resistance region. Therefore, the ion implantation region 3 is formed in the edge region of the epitaxial structure 2, and the current injection region 4 in the middle is kept at a certain distance from the ion implantation region 3. Defect treatment processes such as ion diffusion and annealing during the formation of the ion implantation region 3 will not affect the performance of the current injection region 4, making it easier to achieve efficient current injection in the middle epitaxial structure 2 and further improving the light output efficiency of the laser. On the other hand, in this embodiment, the formation of the ion implantation region 3 does not change the surface topography of the side surface of the epitaxial structure 2 far from the substrate layer 1. The side surface of the epitaxial structure 2 far from the substrate layer 1 still remains in a planar state and does not have an etched deep groove structure. When flip-chip packaging the edge-emitting laser structure 10 onto the heat sink surface, the solder will not have soldering voids due to the uneven welding surface, facilitating the discharge of gas during the packaging process, ensuring the packaging stability and performance of the edge-emitting laser structure 10, and extending the service life.

[0087] In summary, in the preparation method of the edge-emitting laser structure of this embodiment, ion implantation is performed on the surface of the epitaxial structure 2 away from the substrate layer 1 to form ion implantation regions 3 on both edges of the epitaxial structure 2 in the first direction, penetrating the second confinement layer 205, the second waveguide layer 204, and the active layer 203. A current injection region 4 having a gap with the ion implantation regions 3 is adapted to be formed between the ion implantation regions 3 on both sides in the first direction. The formation of the ion implantation regions 3 does not affect the internal structural performance of the current injection region 4. At the same time, the formed high-resistance region can further improve the current injection efficiency and enhance the light output efficiency of the laser. More importantly, in the first direction, the outer surface of the ion implantation regions 3 forms an effective electrical isolation on the outer wall surface of the edge-emitting laser structure 10, avoiding the short-circuit failure problem caused by solder climbing during flip-chip packaging; moreover, the formation of the ion implantation regions 3 does not change the surface topography of the surface of the epitaxial structure 2 away from the substrate layer 1. The surface of the epitaxial structure 2 away from the substrate layer 1 is still a flat surface. When flip-chip packaging the edge-emitting laser structure 10 onto the heat sink surface, the solder will not have soldering voids due to the uneven welding surface, facilitating the discharge of gases during the packaging process, ensuring the packaging stability and performance of the edge-emitting laser structure 10, and extending the service life.

[0088] As a preferred embodiment, in the above first direction, the range of the spacing distance between the current injection region 4 and the ion implantation regions 3 is set to be 20 μm to 25 μm.

[0089] That is, the ion implantation regions 3 are set 20 μm to 25 μm outside the current injection region 4 to the edge of the edge-emitting laser structure 10. The spacing distance is set between 20 μm and 25 μm to reserve the channels for ion implantation and the influence of ion diffusion after annealing on the performance of the laser, ensuring the current injection requirements of the edge-emitting laser structure 10, that is, the stripe width requirements. If the distance is too small, the lateral ion diffusion caused by ion implantation may affect the performance of the current injection region 4; if the distance is too large, it is not conducive to the lateral confinement of the lateral current and will cause unnecessary ion implantation. The ion implantation regions 3 are set until the edge of the edge-emitting laser structure 10 to form electrical isolation on the outer wall surface, avoiding the formation of a short circuit due to the PN connection of the epitaxial layer caused by solder. Using ion implantation to replace the traditional ridge waveguide trench etching can not only play the role of current confinement of the ridge waveguide trench but also avoid the unevenness of the chip surface caused by deep trenches, which is beneficial to the discharge of air between the laser structure and the heat sink during the packaging process, reducing the probability of void formation, and improving the thermal conductivity and packaging stability of the device.

[0090] In one embodiment, the step S102 of performing ion implantation on the side of the epitaxial structure 2 facing away from the substrate layer 1 includes:

[0091] Step S1021: A first mask layer 91 is formed on the surface of the epitaxial structure 2 facing away from the substrate layer 1. The first mask layer 91 covers the surface of the first region 207 and part of the surface of the second region 208, exposing the edge regions on both sides in the first direction.

[0092] See Figure 5 , a positive photoresist is coated on the entire surface of the epitaxial structure 2 facing away from the substrate layer 1. A high-viscosity photoresist with a target film thickness between 4 μm and 5 μm is used. Then, the photoresist on the surface of the epitaxial structure 2 where ion implantation is to be performed is removed, forming the first mask layer 91 required in this embodiment. The first mask layer 91 exposes a part of the epitaxial structure 2.

[0093] Step S1022: Ion implantation is performed on the surface of the epitaxial structure 2 exposed by the first mask layer 91 to form ion implantation regions 3 that penetrate the second confinement layer 205, the second waveguide layer 204, and the active layer 203 in the edge regions on both sides of the epitaxial structure 2 in the first direction.

[0094] See Figure 7 , the region exposed by the first mask layer 91 is a strip-shaped region at the edge of the epitaxial structure 2 in the first direction, and the other regions on the surface of the epitaxial structure 2 are covered by the first mask layer 91. Multiple ion implantation processes are performed on the part of the epitaxial structure 2 exposed by the first mask layer 91 to form a flat impurity distribution for current control.

[0095] Step S1023: The first mask layer 91 is removed.

[0096] Exemplarily, the first mask layer 91 can be removed by wet etching or other methods.

[0097] The anneal treatment is performed on the epitaxial structure 2 after ion implantation.

[0098] After three times of ion implantation and removal of the first mask layer 91, the anneal treatment needs to be performed on the whole epitaxial structure 2. The anneal temperature range is 410 °C to 430 °C, and the anneal duration range is 30 s to 60 s, to improve the impurity distribution uniformity in the ion implantation regions 3 and reduce the defects in the ion implantation regions 3.

[0099] In one embodiment, the step S102 of performing ion implantation on the side of the epitaxial structure 2 facing away from the substrate layer 1 includes: performing multiple ion implantations on the edge regions on the side of the epitaxial structure 2 facing away from the substrate layer 1 in the first direction, and the implantation energies of the multiple ion implantations decrease in sequence.

[0100] That is, multiple ion implantations are performed on the surface of the epitaxial structure 2 exposed by the first mask layer 91. Through multiple ion implantations, the depth of ion implantation can be accurately controlled, and at the same time, the change in ion concentration in each part of the ion implantation region 3 in the depth direction can be made gentle, ensuring the current lateral confinement effect on the inner side and the electrical isolation effect on the outer side. The implantation energy of the ion implantation decreases in sequence, that is, the ion implantation energy of the first ion implantation is the highest to ensure that the deepest structural layer is ion implanted first, and then the implantation energy decreases in sequence, that is, the depth of ion implantation gradually becomes shallower, and the subsequent ion implantation will not impact the prior ion implantation layer, ensuring the effect of each ion implantation and the performance of the final ion implantation region 3.

[0101] In this embodiment, the step S101 of forming the epitaxial structure 2 on one side surface of the substrate layer 1 includes: sequentially stacking and forming a first confinement layer 201, a first waveguide layer 202, an active layer 203, a second waveguide layer 204, a second confinement layer 205, and a contact layer 206 on the substrate layer 1.

[0102] Exemplarily, the contact layer 206 of this embodiment can adopt gallium arsenide with a thickness between 0.2 μm and 0.25 μm. The contact layer is a highly doped layer, which is convenient for forming a good ohmic contact with the seed layer subsequently.

[0103] After the step S101 of forming the epitaxial structure 2 on one side surface of the substrate layer 1 and before the step S102 of performing ion implantation on the side of the epitaxial structure 2 facing away from the substrate layer 1, it further includes: etching and removing at least a part of the thickness of the contact layer 206 located in the second region 208, so that a part of the contact layer 206 in the second region 208 forms a positioning protrusion 2061.

[0104] See Figure 2 and Figure 3That is, when forming the epitaxial structure 2, after the second confinement layer 205 is epitaxially grown, the entire contact layer 206 is epitaxially grown on the second confinement layer 205, and then the contact layer 206 of the thickness of part of the second region 208 is removed by wet etching, such as the contact layer 206 of the thickness between 0.1 μm and 0.15 μm, so that the contact layer 206 of the part of the current injection region 4 located in the first region 207 forms a positioning protrusion 2061, which is convenient for forming the subsequent first mask layer 91 alignment mark point and controlling the current path. The subsequent current injection region 4 is formed within the range of the positioning protrusion 2061, but it is not necessary to be completely consistent with the range of the positioning protrusion 2061. The positioning protrusion 2061 also helps to reduce the current injection at the cavity surface, especially the front and rear cavity surfaces, that is, the first cavity surface 11 and the second cavity surface 12 opposite to each other in the second direction perpendicular to the first direction, to achieve precise electrode setting and current injection, thereby reducing non-radiative recombination, reducing the temperature at the cavity surface, and improving the optical catastrophic damage threshold and photoelectric conversion efficiency. Of course, the entire contact layer 206 of the second region 208 may also be etched away. In the present embodiment, the figures show that the entire contact layer 206 of the second region 208 is etched away, and the etching of a portion of the thickness is not specifically shown.

[0105] Further, see Figure 8 The schematic diagram of ion concentration distribution of three ion implantations shown in the figure, wherein the above-mentioned multiple ion implantations are performed on the edge region of the side of the epitaxial structure 2 facing away from the substrate layer 1 in the first direction, including:

[0106] The first ion implantation 301 is performed on the edge region of the epitaxial structure 2 in the first direction away from the substrate layer 1. The implantation energy of the first ion implantation 301 is 170 KeV, and the implanted ion dose is 3.0E+15 cm -2 .

[0107] Exemplarily, the three ion implantations in this embodiment are all hydrogen ion implantations, and the ion implantations are performed at an angle of 7° between the ion beam and the vertical direction. The first ion implantation 301 is mainly formed in the active layer 203 and the second waveguide layer 204. In other embodiments, part of the ion implantation is implanted into the first waveguide layer 202 below the active layer 203. The ion implantation depth in the first waveguide layer 202 ranges from 0.1 μm to 0.2 μm. The energy of the first ion implantation 301 is the largest, and the target depth of the implantation area is the largest.

[0108] A second ion implantation 302 is performed on the edge region of the epitaxial structure 2 in the first direction away from the substrate layer 1. The implantation energy of the second ion implantation 302 is 90 KeV, and the implanted ion dose is 3.0E+15 cm -2 .

[0109] Exemplarily, the second ion implantation 302 of this embodiment is mainly formed in the second confinement layer 205. The energy of the second ion implantation 302 is less than that of the first ion implantation 301, but the ion dose implanted is the same as that of the first ion implantation 301. This is because the highest ion concentration of the ion implantation layer formed by the later ion implantation needs to be greater than that of the ion implantation layer formed earlier, so as to form a gently transitioning ion concentration distribution in the longitudinal stacking direction and form an ion implantation region 3 with good current blocking and electrical isolation as a whole.

[0110] A third ion implantation 303 is performed on the edge region of the side of the epitaxial structure 2 facing away from the substrate layer 1 in the first direction. The implantation energy of the third ion implantation 303 is 15 Kev, and the ion dose implanted is 3.0E+14 cm -2 .

[0111] Exemplarily, the third ion implantation 303 of this embodiment is mainly formed in a part of the remaining thickness of the contact layer 206 on the second confinement layer 205. The energy of the third ion implantation 303 is less than that of the second ion implantation 302, and the ion dose implanted is slightly less than that of the first ion implantation 301 and the second ion implantation 302, so that the ions of the third ion implantation 303 all stay on the surface layer of the epitaxial structure 2, so as to form the most effective electrical isolation on the surface of the epitaxial structure 2 and avoid carrier recombination.

[0112] Through the above three ion implantations, an ion implantation region 3 with a gently transitioning ion concentration in the vertical direction is formed, and the energies of the multiple ion implantations decrease. The different ion regions formed are connected to each other and can maintain the stability of their relative self-properties.

[0113] In one embodiment, the thickness of the second waveguide layer 204 is less than that of the first waveguide layer 202 to form an epitaxial structure 2 with an asymmetric large optical cavity.

[0114] Refer to Figure 2 , the optical resonator of the epitaxial structure 2 of this embodiment adopts an asymmetric large optical cavity design. The thickness of the second waveguide layer 204 is less than that of the first waveguide layer 202, and the peak light intensity deviates from the active layer 203, allowing a larger catastrophic optical damage threshold optical power, and the edge-emitting laser structure 10 realizes high-power light output.

[0115] In one embodiment, after the step S102 of ion implantation on the side of the epitaxial structure 2 facing away from the substrate layer 1, the preparation method of this embodiment further includes:

[0116] Step S103, forming a passivation layer 5 on the surface of the side of the epitaxial structure 2 facing away from the substrate layer 1. The passivation layer 5 covers at least the surface of the second region 208 to expose the current injection region 4 in the first region 207.

[0117] First, a low-stress silicon nitride thin film is deposited on the surface of the epitaxial structure 2 facing away from the substrate layer 1 after ion implantation. Then, dry etching is used to remove a part of the silicon nitride thin film located on the positioning protrusion 2061. Of course, a part of the silicon nitride at the edge of the positioning protrusion 2061 can be retained. Refer to Figure 9 and Figure 10 , a window is formed on the positioning protrusion 2061, and a passivation layer 5 covering the surface of other regions is formed. The epitaxial structure 2 exposed through the window of the passivation layer 5 forms a precise current injection region 4, which can further accurately ensure the accuracy of the range of the current injection region 4 below the positioning protrusion 2061.

[0118] Of course, it is not excluded that the width of the current injection region 4 in the first direction is equal to the width of the positioning protrusion 2061 in the first direction.

[0119] Furthermore, in the preparation method of the edge-emitting laser structure of this embodiment, after step S103 of forming the passivation layer 5 on the surface of the epitaxial structure 2 facing away from the substrate layer 1, it further includes:

[0120] Step S104, forming a first electrode 61 on the surface of the epitaxial structure 2 facing away from the substrate layer 1, and the first electrode 61 is connected to the surface of the current injection region 4.

[0121] Exemplarily, in this embodiment, an electroplating process is used to form a gold layer with a thickness between 3 μm and 4 μm on the surface of the epitaxial structure 2 facing away from the substrate layer 1 as the first electrode 61 connected to the contact layer 206, that is, the P-side electrode. The first electrode 61 is directly welded to the heat sink in the subsequent packaging process. The metal first electrode 61 is fused with the metal solder, and the bonding strength is high, effectively improving the heat conduction efficiency and the electrical conduction efficiency.

[0122] Step S105, forming a second electrode 62 on the surface of the substrate layer 1 facing away from the epitaxial structure 2.

[0123] Exemplarily, an electron beam evaporation method is used to evaporate a composite metal layer of Ti / Pt / Au stacked in sequence on the surface of the substrate layer 1 as the second electrode 62, that is, the N-side electrode. The metal platinum (Pt) with high soldering resistance is used in the intermediate layer, and the metal titanium (Ti) is used to directly contact the substrate layer 1 to improve the reliability. The outermost layer uses gold (Au) to realize the external electrical connection wire bonding with high electrical conductivity. The thickness range of the second electrode 62 is 200 nm to 300 nm.

[0124] In summary, the setting of the first electrode 61 and the second electrode 62 realizes the packaging of the electrical connection between the edge-emitting laser structure 10 and other external structures, and realizes the finished product application.

[0125] Furthermore, refer to Figure 11After step S103 of forming the passivation layer 5 on one side surface of the epitaxial structure 2 facing away from the substrate layer 1 and before step S104 of forming the first electrode 61 on one side surface of the epitaxial structure 2 facing away from the substrate layer 1, it further includes: forming a seed layer 7 on one side surface of the epitaxial structure 2 facing away from the substrate layer 1, and the first electrode 61 is formed on one side surface of the seed layer 7 facing away from the substrate layer 1.

[0126] Exemplarily, on the contact layer 206 on one side of the epitaxial structure 2 facing away from the substrate layer 1, metal titanium, platinum, and gold are sequentially evaporated by electron beam evaporation to form a composite metal layer of Ti / Pt / Au stack as the seed layer 7 for depositing the first electrode 61. Metal platinum (Pt) with high solder resistance is used in the intermediate layer, and metal titanium (Ti) is used to directly contact the contact layer 206 to improve reliability. Gold (Au) is used on the outermost side to contact the first electrode 61 with high conductivity. The thickness range of the seed layer 7 is 200 nm to 300 nm. Setting the seed layer 7 between the first electrode 61 and the contact layer 206 helps to further improve the connection reliability between the relatively thick first electrode 61 and the contact layer 206, reduce the surface contact resistance of the direct connection between the first electrode 61 and the contact layer 206, and improve the current injection efficiency.

[0127] After forming the first electrode 61 on one side surface of the epitaxial structure 2 facing away from the substrate layer 1 and before forming the second electrode 62 on one side surface of the substrate layer 1 facing away from the epitaxial structure 2, it further includes: thinning one side surface of the substrate layer 1 facing away from the epitaxial structure 2.

[0128] The second electrode 62 on one side of the substrate layer 1 needs to achieve electrical connection through the substrate layer 1 and the epitaxial structure 2. If the substrate layer 1 is too thick, it is not conducive to heat dissipation and subsequent cleavage cutting. Therefore, after thinning the substrate layer 1, the second electrode 62 is formed to improve the electrical connection efficiency. The thickness range of the thinned substrate layer 1 is 130 μm to 150 μm, which is convenient for efficient heat dissipation and cleavage cutting.

[0129] In one embodiment, in step S101 of forming the epitaxial structure 2 on one side surface of the substrate layer 1, the epitaxial structure 2 and the substrate layer 1 first form a laser chip 100. The laser chip 100 includes a plurality of laser bars 101 arranged at intervals along the second direction. Any one of the laser bars 101 includes a plurality of edge-emitting laser structures 10 arranged at intervals along the first direction. The second direction is perpendicular to the first direction, as Figure 14 shown; the edge-emitting laser structure 10 has a first cavity surface 11 and a second cavity surface 12 arranged oppositely in the second direction, and the first cavity surface 11 is used for laser emission.

[0130] As Figure 14As shown, the substrate layer 1 and the epitaxial structure 2 of this embodiment may include a plurality of array edge-emitting laser structures 10, so as to facilitate the batch formation of a plurality of edge-emitting laser structures 10. These edge-emitting laser structures 10 form a plurality of laser bars 101 arranged at intervals in the second direction. Each laser bar 101 includes a plurality of edge-emitting laser structures 10 arranged at intervals in the first direction. Each edge-emitting laser structure 10 includes opposite first cavity surface 11 and second cavity surface 12 along the second direction. One side of the first cavity surface 11 is used for emitting laser. Refer to Figure 16 .

[0131] Specifically, after the step S105 of forming the second electrode 62 on the surface of the substrate layer 1 facing away from the epitaxial structure 2, the preparation method of this embodiment further includes:

[0132] Step S106, cleaving the laser chip 100 into a plurality of laser bars 101 along the first direction.

[0133] As Figure 15 and Figure 16 shown, the edge of the first electrode 61 of the epitaxial structure 2 of each edge-emitting laser structure 10 has a cleavage groove 611. Specifically, by coating a positive photoresist on the seed layer 7, the photoresist is retained after exposure in the area where the cleavage groove needs to be formed, and the photoresist in other areas is removed to form the second mask layer 92; then the laser chip 100 is immersed in the electroplating solution, and thick gold is deposited in the area without photoresist to form the first electrode 61, as Figure 12 and Figure 13 shown; finally, the photoresist is removed to form the cleavage groove 611 for cleavage cutting. Then, the laser chip 100 is cleaved and cut along the cleavage groove 611 of the part shown by the vertical dotted line extending in the first direction in Figure 14 to form a plurality of laser bars 101. The number of laser bars 101 shown in this embodiment of Figure 4 is only for illustration, and more laser bars 101 can be set.

[0134] Step S107, forming an antireflection film layer 81 and a high-reflection film layer 82 on opposite side surfaces of the laser bar 101 along the second direction.

[0135] The antireflection film is provided on the light-emitting side surface of the laser bar 101, and the high-reflection film layer 82 is provided on the other side surface opposite to the antireflection film layer 81. After setting the antireflection film layer 81 and the high-reflection film layer 82 on the laser bar 101 and then cleaving and forming the edge-emitting laser structure 10, it helps to simplify the preparation of the cavity film and improve the preparation efficiency and consistency.

[0136] Step S108, cleaving the laser bar 101 into a plurality of edge-emitting laser structures 10 along the second direction.

[0137] Reference Figures 13 to 16 , cutting is performed in the partial cleavage groove 611 extending in the second direction between the adjacent edge-emitting laser structures 10 in the laser bar 101 to finally form a plurality of complete edge-emitting laser structures 10 as shown in Figure 15 and Figure 15 . Each outer wall surface of the edge-emitting laser structure 10 opposite in the first direction includes the outer wall surface of the ion implantation region 3; an antireflection film layer 81 is provided on the first cavity surface 11 in the second direction to improve the laser output efficiency, and a high-reflection film layer 82 is provided on the second cavity surface 12 to improve the reflection of the laser in the resonant cavity, so that more laser light exits from the side of the first cavity surface 11.

[0138] Reference Figure 15 and Figure 16 , this embodiment also provides an edge-emitting laser structure 10, which is prepared by using the preparation method of the above-mentioned edge-emitting laser structure, and includes: a substrate layer 1, an epitaxial structure 2 and an ion implantation region 3. The epitaxial structure 2 is disposed on one surface of the substrate layer 1 and includes a first confinement layer 201, a first waveguide layer 202, an active layer 203, a second waveguide layer 204 and a second confinement layer 205 stacked on the substrate layer 1. The surface of the epitaxial structure 2 includes a first region 207 and a second region 208 surrounding the first region 207; the ion implantation region 3 is formed on both side edges in the first direction of the epitaxial structure 2 in the second region 208, and the current injection region 4 is formed in the epitaxial structure 2 of the first region 207. The ion implantation region 3 at least penetrates the second confinement layer 205, the second waveguide layer 204 and the active layer 203, and there is a gap between the current injection region 4 and the ion implantation region 3 in the first direction.

[0139] The edge-emitting laser structure 10 of this embodiment forms ion implantation regions 3 that penetrate through the second confinement layer 205, the second waveguide layer 204, and the active layer 203 on both side edges of the epitaxial structure 2 in the first direction. A current injection region 4 having a gap with the ion implantation regions 3 is adapted to be formed between the ion implantation regions 3 on both sides in the first direction. The ion implantation regions 3 do not affect the internal structural performance of the current injection region 4. At the same time, the formed high-resistance ion implantation regions 3 can further improve the current injection efficiency and enhance the light output efficiency of the laser. More importantly, in the first direction, the outer surface of the ion implantation regions 3 forms an effective electrical isolation on the outer wall surface of the edge-emitting laser structure 10, avoiding the short-circuit failure problem caused by solder climbing during flip-chip packaging; moreover, the formation of the ion implantation regions 3 does not change the surface topography of the side surface of the epitaxial structure 2 away from the substrate layer 1. The side surface of the epitaxial structure 2 away from the substrate layer 1 is still a flat surface. When flip-chip packaging the edge-emitting laser structure 10 onto the heat sink surface, the solder will not have welding voids due to the uneven welding surface, facilitating the discharge of gases during the packaging process, ensuring the packaging stability and performance of the edge-emitting laser structure 10, and extending the service life.

[0140] Compared with the traditional high-power edge-emitting laser structure that uses ridge waveguide etching to achieve current control, it has no protection for the edge, is prone to solder climbing in the flip-chip packaging process, resulting in the failure of the laser structure. At the same time, the etched deep grooves are prone to cause packaging voids during the packaging process, leading to poor heat dissipation capacity of the device and unstable output performance. The edge-emitting laser structure 10 of this embodiment forms ion implantation regions 3 by ion implantation at the edge of the epitaxial structure 2 at a certain distance from the current injection region 4, replacing the traditional ridge waveguide etching process. Without affecting the performance and life of the laser structure, it is more suitable for subsequent flip-chip packaging applications, improving the overall yield and stability of the product. Since voids are not easily detected in the flip-chip packaging process, the detection cost is high, and it fluctuates greatly with factors such as the packaging machine and the thickness of the laser structure, so flattening the surface of the laser structure can greatly reduce the probability of voids, improve the polarization degree of the edge-emitting laser structure 10, and reduce the influence of factors such as the machine and the chip thickness.

[0141] In addition, the heat of the traditional edge-emitting laser structure 10 is conducted outward through the air in the trenches on both sides from the active layer 203 of the ridge waveguide, and the air has poor thermal conductivity. After ion implantation in the edge-emitting laser structure 10 of this embodiment, the heat is transferred in a solid material with good thermal conductivity, and the heat dissipation ability becomes better; in addition, the ridge waveguide will form a refractive index difference between the epitaxial structure 2 and the air, while the refractive index difference between the current injection region 4 and the ion implantation regions 3 in the solution after ion implantation is much smaller than the refractive index difference between the epitaxial structure 2 and the air. This embodiment helps to reduce the equivalent refractive index difference, and the slow-axis divergence angle becomes better.

[0142] In one embodiment, the epitaxial structure 2 of this embodiment further includes a contact layer 206. The contact layer 206 is disposed on a surface of the second confinement layer 205 facing away from the substrate layer 1. On the side of the contact layer 206 facing away from the substrate layer 1, there are positioning protrusions 2061 in the first region 207. The positioning protrusions 2061 are used to form a current injection region 4.

[0143] See Figure 15 , the positioning protrusions 2061 formed by a part of the contact layer 206 located in the first region 207 corresponding to the current injection region 4 facilitate subsequent control of the current path, contribute to reducing current injection at the cavity surface, especially the front and rear cavity surfaces, that is, the first cavity surface 11 and the second cavity surface 12 opposite to each other in the second direction perpendicular to the first direction, realize precise electrode setting and current injection, thereby reducing non-radiative recombination, reducing the temperature at the cavity surface, and improving the optical catastrophic damage threshold and the photoelectric conversion efficiency.

[0144] In one embodiment, referring to Figure 15 and Figure 16 , the above edge-emitting laser structure 10 further includes: a passivation layer 5, a seed layer 7, a first electrode 61, a second electrode 62, an antireflection film layer 81, and a high-reflection film layer 82. The passivation layer 5 is disposed on a surface of the epitaxial structure 2 facing away from the substrate layer 1. The passivation layer 5 covers at least the second region 208 of the epitaxial structure 2 so that the current injection region 4 in the first region 207 is exposed; the seed layer 7 is disposed on a surface of the epitaxial structure 2 facing away from the substrate layer 1. The seed layer 7 is adapted to be connected to the positioning protrusions 2061 in the first region 207; the first electrode 61 is disposed on a surface of the seed layer 7 facing away from the substrate layer 1; the second electrode 62 is disposed on a surface of the substrate layer 1 facing away from the epitaxial structure 2; the antireflection film layer 81 is disposed on the first cavity surface 11. The edge-emitting laser structure 10 has opposite first cavity surface 11 and second cavity surface 12 in the second direction, and the second direction is perpendicular to the first direction; the high-reflection film layer 82 is disposed on the second cavity surface 12.

[0145] The passivation layer 5 of this embodiment is made of a low-stress silicon nitride thin film. Windows are formed on the positioning protrusions 2061 to cover other areas of the surface of the epitaxial structure 2, which can improve the accuracy of current injection. The first electrode 61 and the second electrode 62 are provided to realize the encapsulation of the electrical connection between the edge-emitting laser structure 10 and other external structures, enabling finished product applications. A seed layer 7 is provided between the first electrode 61 and the contact layer 206, which helps to further improve the connection reliability between the relatively thick first electrode 61 and the contact layer 206, reduce the surface contact resistance of the direct connection between the first electrode 61 and the contact layer 206, and improve the current injection efficiency. An antireflection film layer 81 is provided on the first cavity surface 11 in the second direction to improve the laser output efficiency. A high-reflection film layer 82 is provided on the second cavity surface 12 to improve the reflection of the laser in the resonant cavity, so that more laser light exits from the side of the first cavity surface 11, thereby improving the laser output efficiency of the laser.

[0146] The further functional descriptions of the above-mentioned modules are the same as those in the corresponding above-mentioned embodiments, and will not be elaborated here.

[0147] In the above description, technical details such as the layout and etching of each layer are not described in detail. However, those skilled in the art should understand that various technical means can be used to form layers, regions, etc. of the required shapes. In addition, in order to form the same structure, those skilled in the art can also design methods that are not exactly the same as the methods described above. In addition, although the above embodiments are described separately, this does not mean that the measures in each embodiment cannot be used in combination advantageously.

[0148] Although the embodiments of the present invention are described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations fall within the scope defined by the appended claims.

Claims

1. A preparation method of an edge-emitting laser structure, characterized in that Including: An epitaxial structure is formed on one side surface of a substrate layer. The epitaxial structure includes a first confinement layer, a first waveguide layer, an active layer, a second waveguide layer, and a second confinement layer which are stacked on the substrate layer. The surface of the epitaxial structure includes a first region and a second region surrounding the first region. Ion implantation is performed on the side of the epitaxial structure facing away from the substrate layer to form ion implantation regions at both side edges in a first direction in the epitaxial structure of the second region. The ion implantation regions penetrate at least the second confinement layer, the second waveguide layer, and the active layer. A current injection region is formed in the epitaxial structure of the first region. In the first direction, there is a spacing distance between the current injection region and the ion implantation regions.

2. The manufacturing method of the edge-emitting laser structure according to claim 1, characterized in that In the first direction, the range of the spacing distance between the current injection region and the ion implantation regions is 20 μm to 25 μm.

3. The manufacturing method of the edge-emitting laser structure according to claim 1, characterized in that, The ion implantation on the side of the epitaxial structure facing away from the substrate layer includes: A first mask layer is formed on the side surface of the epitaxial structure facing away from the substrate layer. The first mask layer covers the surface of the first region and part of the surface of the second region to expose the edge regions on both sides in the first direction. Ion implantation is performed on the surface of the epitaxial structure exposed by the first mask layer to form ion implantation regions penetrating the second confinement layer, the second waveguide layer, and the active layer at both side edge regions of the epitaxial structure in the first direction. The first mask layer is removed. The epitaxial structure after ion implantation is annealed.

4. The manufacturing method of the edge-emitting laser structure according to claim 1, characterized in that The ion implantation on the side of the epitaxial structure facing away from the substrate layer includes: multiple ion implantations are performed on the edge regions in the first direction on the side of the epitaxial structure facing away from the substrate layer, and the implantation energies of the multiple ion implantations decrease in sequence.

5. The manufacturing method of the edge-emitting laser structure according to claim 4, characterized in that, The formation of the epitaxial structure on one side surface of the substrate layer includes: a first confinement layer, a first waveguide layer, an active layer, a second waveguide layer, a second confinement layer, and a contact layer are sequentially stacked on the substrate layer. After the epitaxial structure is formed on one side surface of the substrate layer and before the ion implantation is performed on the side of the epitaxial structure facing away from the substrate layer, it further includes: at least part of the thickness of the contact layer located in the second region is etched away so that part of the contact layer in the second region forms a positioning protrusion.

6. The manufacturing method of the edge-emitting laser structure according to claim 5, characterized in that, The multiple ion implantations on the edge regions in the first direction on the side of the epitaxial structure facing away from the substrate layer include: A first ion implantation is performed on an edge region of the epitaxial structure in a first direction away from the substrate layer, wherein the implantation energy of the first ion implantation is 170 KeV and the implanted ion dose is 3.0E+15 cm -2 ; A second ion implantation is performed on the edge region of the epitaxial structure in the first direction away from the substrate layer, wherein the implantation energy of the second ion implantation is 90 KeV and the implanted ion dose is 3.0E+15 cm -2 ; A third ion implantation is performed on the edge region of the epitaxial structure in the first direction away from the substrate layer, wherein the implantation energy of the third ion implantation is 15 KeV and the implanted ion dose is 3.0E+14 cm -2 .

7. The manufacturing method of the edge-emitting laser structure according to claim 1, characterized in that, The thickness of the second waveguide layer is less than the thickness of the first waveguide layer to form an epitaxial structure with an asymmetric large optical cavity.

8. The manufacturing method of the edge-emitting laser structure according to any one of claims 1-7, characterized in that, After the ion implantation is performed on the side of the epitaxial structure facing away from the substrate layer, it further includes: A passivation layer is formed on the side surface of the epitaxial structure facing away from the substrate layer. The passivation layer covers at least the surface of the second region to expose the current injection region in the first region.

9. The preparation method of the edge-emitting laser structure according to claim 8, characterized in that, After the passivation layer is formed on the side surface of the epitaxial structure facing away from the substrate layer, it further includes: A first electrode is formed on a surface of the epitaxial structure facing away from the substrate layer, and the first electrode is connected to a surface of the current injection region. A second electrode is formed on a surface of the substrate layer facing away from the epitaxial structure.

10. The preparation method of the edge-emitting laser structure according to claim 9, characterized in that, After a passivation layer is formed on a surface of the epitaxial structure facing away from the substrate layer and before the first electrode is formed on the surface of the epitaxial structure facing away from the substrate layer, it further includes: forming a seed layer on the surface of the epitaxial structure facing away from the substrate layer, and the first electrode is formed on a surface of the seed layer facing away from the substrate layer. After the first electrode is formed on a surface of the epitaxial structure facing away from the substrate layer and before the second electrode is formed on a surface of the substrate layer facing away from the epitaxial structure, it further includes: thinning a surface of the substrate layer facing away from the epitaxial structure.

11. The method for preparing the edge-emitting laser structure according to claim 10, characterized in that, In the step of forming the epitaxial structure on a surface of the substrate layer, the epitaxial structure and the substrate layer form a laser chip, the laser chip includes a plurality of laser bars arranged at intervals along a second direction, and any one of the laser bars includes a plurality of edge-emitting laser structures arranged at intervals along a first direction, and the second direction is perpendicular to the first direction; the edge-emitting laser structure has a first cavity surface and a second cavity surface arranged oppositely in the second direction, and the first cavity surface is used for laser emission.

12. The preparation method of the edge-emitting laser structure according to claim 11, characterized in that, After the second electrode is formed on a surface of the substrate layer facing away from the epitaxial structure, it further includes: Cleaving the laser chip into a plurality of laser bars along the first direction; Forming an antireflection film layer and a high-reflection film layer on opposite side surfaces of the laser bar along the second direction respectively; Cleaving the laser bar into a plurality of edge-emitting laser structures along the second direction.

13. An edge-emitting laser structure, characterized in that, It includes: A substrate layer; An epitaxial structure disposed on a surface of the substrate layer, the epitaxial structure includes a first confinement layer, a first waveguide layer, an active layer, a second waveguide layer and a second confinement layer stacked on the substrate layer; a surface of the epitaxial structure includes a first region and a second region surrounding the first region. An ion implantation region is formed at two side edges along the first direction in the epitaxial structure of the second region, and a current injection region is formed in the epitaxial structure of the first region; the ion implantation region at least penetrates through the second confinement layer, the second waveguide layer and the active layer, and there is an interval between the current injection region and the ion implantation region in the first direction.

14. The edge-emitting laser structure according to claim 13, wherein The epitaxial structure further includes: a contact layer disposed on a surface of the second confinement layer facing away from the substrate layer, and a positioning protrusion is provided on a side of the contact layer facing away from the substrate layer within the first region.

15. The edge-emitting laser structure according to claim 14, characterized in that, It further includes: A passivation layer disposed on a surface of the epitaxial structure facing away from the substrate layer, and the passivation layer at least covers the second region of the epitaxial structure so that the current injection region within the first region is exposed. A seed layer disposed on a surface of the epitaxial structure facing away from the substrate layer, and the seed layer is adapted to be connected to the positioning protrusion within the first region. A first electrode disposed on a surface of the seed layer facing away from the substrate layer. The second electrode is disposed on a surface of the substrate layer facing away from the epitaxial structure; The antireflection film layer is disposed on the first cavity surface. The edge-emitting laser structure has opposite first and second cavity surfaces in a second direction, and the second direction is perpendicular to the first direction; The high-reflection film layer is disposed on the second cavity surface.

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