A vertical cavity surface emitting laser and a method for manufacturing the same

Abstract

The present invention discloses a vertical cavity surface emitting laser and a manufacturing method thereof, which relates to the field of laser technology. The vertical cavity surface emitting laser comprises: a substrate; a first ohmic contact layer formed on a first surface of the substrate; a first reflective layer formed on a surface of the first ohmic contact layer away from the substrate, comprising a first groove and a plurality of second grooves, wherein the first groove is exposed to the first ohmic contact layer, and the bottom thickness of each second groove is greater than zero. The etched second groove does not need to be exposed to the first ohmic contact layer, and only a portion of the first reflective layer needs to be etched, thereby reducing the resistance of the light-emitting unit under the same light-emitting area, improving the photoelectric conversion efficiency of the light-emitting unit, and reducing the spacing between the light-emitting units, thereby improving the light-emitting area per unit area.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of laser technology, and in particular to a vertical cavity surface emitting laser and a manufacturing method thereof. Background Art

[0002] Vertical Cavity Surface Emitting Laser (VCSEL) is developed based on gallium arsenide semiconductor materials. Different from other light sources such as LED (light emitting diode) and LD (Laser Diode), it has the advantages of small size, circular output spot, single longitudinal mode output, small threshold current, low price, and easy integration into large-area arrays. It is widely used in optical communications, optical interconnection, optical storage, high-power applications, industrial cutting, ranging, Lidar, medical and other fields.

[0003] In terms of optical fiber communication, the VCSEL market is developing unprecedentedly, and it has replaced high-priced LDs in North America for the construction of Gigabit and 10 Gigabit Ethernet data communication networks, resulting in an explosive growth in the demand for high-speed VCSEL transceiver modules. VCSEL also has good application prospects in other areas. In terms of optical printing, the electronicization of optical scanning technologies such as polygonal mirrors in laser printers has been a problem that has not been solved for many years, but has gradually been improved with the development of technology.

[0004] In traditional VCSELs, the distance between adjacent light-emitting units is large, the light-emitting area per unit area is small, and the resistance of a single light-emitting unit is large. The photoelectric conversion efficiency of the laser is low, and the overall structure is not compact. Summary of the invention

[0005] The present invention provides a vertical cavity surface emitting laser and a manufacturing method thereof, so as to reduce the distance between two adjacent light-emitting units, increase the light-emitting area per unit area, and reduce the resistance of the light-emitting unit, thereby improving the photoelectric conversion efficiency of the laser.

[0006] To achieve the above object, an embodiment of the present invention provides a vertical cavity surface emitting laser, comprising:

[0007] substrate;

[0008] A first ohmic contact layer is formed on the first surface of the substrate;

[0009] The first reflective layer is formed on a surface of the first ohmic contact layer facing away from the substrate, and includes a first groove and a plurality of second grooves. The first groove is exposed to the first ohmic contact layer, and a bottom thickness of each second groove is greater than zero.

[0010] Optionally, the first reflective layer further includes a first mesa-shaped structure and a second mesa-shaped structure, and a plurality of third mesa-shaped structures are arranged on the second mesa-shaped structure.

[0011] Optionally, along the direction from the substrate to the first ohmic contact layer, the first terrace structure is provided with a first active layer, a first second reflective layer, a first second ohmic contact layer, a first insulating layer and a first electrode layer in sequence;

[0012] A first conductive metal is disposed at the bottom of the first trench, a first insulating layer is disposed on the sidewall, and the first insulating layer extends to the bottom of the first trench and covers a portion of the first conductive metal;

[0013] The first electrode layer is electrically connected to the first conductive metal.

[0014] Optionally, the first groove comprises a first rectangular groove.

[0015] Optionally, the first groove further includes a second rectangular groove, and the second rectangular groove and the first rectangular groove form a T-shaped groove or an L-shaped groove.

[0016] Optionally, the first electrode layer is electrically connected only to the first conductive metal in the second rectangular groove.

[0017] Optionally, along the direction from the substrate to the first ohmic contact layer, each of the third terrace structures is sequentially provided with a second active layer, a second second reflective layer, a second second ohmic contact layer, a second conductive metal layer, a second insulating layer and a second electrode layer;

[0018] The second insulating layer covers a portion of the second conductive metal layer and covers the bottom and sidewalls of each second groove, and the second electrode layer is electrically connected to the second conductive metal layer.

[0019] Optionally, the second groove is an annular groove; and the third terrace structure is a cylindrical terrace.

[0020] To achieve the above object, another embodiment of the present invention provides a method for manufacturing a vertical cavity surface emitting laser, comprising the following steps:

[0021] providing a substrate;

[0022] forming a first ohmic contact layer on a surface of one side of the substrate;

[0023] forming an epitaxial structure on a surface of the first ohmic contact layer facing away from the substrate, wherein the epitaxial structure includes a first reflective layer, an active layer, and a second reflective layer formed in sequence in a direction from the substrate to the first ohmic contact layer;

[0024] forming a second ohmic contact layer on a surface of the epitaxial structure facing away from the first ohmic contact layer;

[0025] forming a plurality of second conductive metal layers on a surface of the second ohmic contact layer facing away from the epitaxial structure;

[0026] forming a third insulating layer on a side of the plurality of second conductive metal layers away from the second ohmic contact layer;

[0027] forming a first groove and a plurality of second grooves, wherein the first groove is exposed to the first ohmic contact layer, and the second grooves sequentially penetrate the second ohmic contact layer, the second reflective layer, the active layer and a portion of the first reflective layer;

[0028] oxidizing the second reflective layer in a plurality of the second grooves;

[0029] forming the first conductive metal layer in the first trench;

[0030] forming a fourth insulating layer on a surface of the third insulating layer facing away from the second conductive metal layer;

[0031] forming a third trench and a plurality of fourth trenches, wherein the third trench is used to expose a portion of the first conductive metal layer; and each of the fourth trenches is used to expose a portion of the second conductive metal layer;

[0032] A first electrode layer and a second electrode layer are formed.

[0033] Optionally, forming the first groove includes:

[0034] A rectangular groove is formed.

[0035] Optionally, forming the first groove includes:

[0036] A T-shaped groove or an L-shaped groove is formed.

[0037] According to the vertical cavity surface emitting laser and the manufacturing method thereof proposed in the embodiment of the present invention, the etched second groove does not need to be exposed to the first ohmic contact layer, and only a portion of the first reflective layer needs to be etched. Therefore, under the same light-emitting area, the resistance of the light-emitting unit is reduced, the photoelectric conversion efficiency of the light-emitting unit is improved, and the spacing between the light-emitting units is reduced, thereby increasing the light-emitting area per unit area. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a schematic structural diagram of a vertical cavity surface emitting laser according to an embodiment of the present invention;

[0039] Figure 2 is a schematic structural diagram of a vertical cavity surface emitting laser according to an embodiment of the present invention;

[0040] Figure 3 is a top view of a vertical cavity surface emitting laser according to an embodiment of the present invention;

[0041] Figure 4 is a top view of a vertical cavity surface emitting laser according to another embodiment of the present invention;

[0042] Figure 5 yes Figure 4 Sectional view of BB';

[0043] Figure 6 yes Figure 4 Sectional view of CC';

[0044] Figure 7 is a top view of a vertical cavity surface emitting laser according to another embodiment of the present invention;

[0045] Figure 8 is a top view of a vertical cavity surface emitting laser according to another embodiment of the present invention;

[0046] Fig. 9 is a flow chart of a method for manufacturing a vertical cavity surface emitting laser according to an embodiment of the present invention;

[0047] Fig.10 is a flow chart of a method for manufacturing a vertical cavity surface emitting laser according to an embodiment of the present invention;

[0048] Fig.11 is a structural schematic diagram of steps S1-S8 in a method for manufacturing a vertical cavity surface emitting laser according to an embodiment of the present invention;

[0049] Figure 12 to Figure 13 is a structural schematic diagram of step S9 in the method for manufacturing a vertical cavity surface emitting laser according to an embodiment of the present invention;

[0050] Fig.14 is a structural schematic diagram of step S10 in the method for manufacturing a vertical cavity surface emitting laser according to an embodiment of the present invention;

[0051] Fig.15 is a structural schematic diagram of step S11 in the method for manufacturing a vertical cavity surface emitting laser according to an embodiment of the present invention;

[0052] Figure 16 to Figure 17 is a structural schematic diagram of step S12 in the method for manufacturing a vertical cavity surface emitting laser according to an embodiment of the present invention;

[0053] Fig.18 is a structural schematic diagram of step S13 in the method for manufacturing a vertical cavity surface emitting laser according to an embodiment of the present invention;

[0054] Fig.19is a structural schematic diagram of step S14 in the method for manufacturing a vertical cavity surface emitting laser according to an embodiment of the present invention;

[0055] Fig. 20 is a structural schematic diagram of step S15 in the method for manufacturing a vertical cavity surface emitting laser according to an embodiment of the present invention;

[0056] Fig.21 is a structural schematic diagram of step S16 in the method for manufacturing a vertical cavity surface emitting laser according to an embodiment of the present invention;

[0057] Figure 22 to Figure 24 It is a structural schematic diagram of step S17 in the method for manufacturing a vertical cavity surface emitting laser according to an embodiment of the present invention. DETAILED DESCRIPTION

[0058] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0059] Figure 1 Schematic diagram of the structure of the vertical cavity surface emitting laser of the embodiment of the present invention. Figure 1 As shown, the vertical cavity surface emitting laser 100 comprises:

[0060] Substrate 101;

[0061] A first ohmic contact layer 102 is formed on a first surface of the substrate 101;

[0062] The first reflective layer 103 is formed on the surface of the first ohmic contact layer 102 facing away from the substrate 101 and includes a first groove 104 and a plurality of second grooves 105. The first groove 104 is exposed to the first ohmic contact layer 102. The bottom thickness of each second groove 105 is greater than zero.

[0063] Alternatively, if Figure 1 As shown, the first reflective layer 103 further includes a first mesa structure 106 and a second mesa structure 107 , and a plurality of third mesa structures 108 are disposed on the second mesa structure 107 .

[0064] Alternatively, if Figure 2 As shown, along the direction from the substrate 101 to the first ohmic contact layer 102, the first mesa structure 106 is sequentially provided with a first active layer 1061, a first second reflective layer 1062, a first second ohmic contact layer 1063, a first insulating layer 1064 and a first electrode layer 1065;

[0065] A first conductive metal layer 109 is disposed at the bottom of the first trench 104 , and a first insulating layer 1064 is disposed on the sidewall thereof. The first insulating layer 1064 extends to the bottom of the first trench 104 and covers a portion of the first conductive metal 109 ;

[0066] The first electrode layer 1065 is electrically connected to the first conductive metal 109 .

[0067] Alternatively, if Figure 2 As shown, along the direction from the substrate 101 to the first ohmic contact layer 102, each third mesa structure 108 is sequentially provided with a second active layer 1081, a second second reflective layer 1082, a second second ohmic contact layer 1083, a second conductive metal layer 1084, a second insulating layer 1085 and a second electrode layer 1086;

[0068] The second insulating layer 1085 covers a portion of the second conductive metal layer 1084 , and covers the bottom and sidewall of each second trench 105 , and the second electrode layer 1086 is electrically connected to the second conductive metal layer 1084 .

[0069] It can be understood that the second active layer 1081, the second second reflective layer 1082, the second second ohmic contact layer 1083, the second conductive metal layer 1084, the second insulating layer 1085 and the second electrode layer 1086 formed on the third terrace structure 108 form a laser light-emitting unit.

[0070] Combination Figures 1 to 3 As shown, Figure 2 for Figure 3 Sectional view along line AA'.

[0071] Alternatively, if Figure 3 As shown, the first groove 104 includes a first rectangular groove 1041 .

[0072] It should be noted that the first active layer 1061 and the second active layer 1081 are arranged in the same layer, the first second reflective layer 1062 and the second second reflective layer 1082 are arranged in the same layer, and the first second ohmic contact layer 1063 and the second second ohmic contact layer 1083 are arranged in the same layer, wherein the first ohmic contact layer, the first reflective layer, the active layer, the second reflective layer and the second ohmic contact layer are sequentially grown on the substrate by epitaxial growth.

[0073] In this embodiment, the substrate 101 can be any semi-insulating material suitable for forming a vertical cavity surface emitting laser. The substrate 101 is, for example, a semi-insulating GaAs substrate, which is a GaAs substrate not doped with impurities and has a very high resistance. The resistivity of the semi-insulating GaAs substrate is above 107Ω·cm. In some embodiments, a conductive substrate or an insulating substrate can also be used instead of a semi-insulating substrate. In this case, the laser array can be formed on a GaAs substrate, separated from the GaAs substrate, and then pasted onto a substrate with high thermal conductivity such as an insulating AlN substrate or a conductive Cu substrate. The substrate 101 can be an N-type substrate.

[0074] The first ohmic contact layer 102 is an N-type doped layer with a relatively high concentration to form an ohmic contact layer, so as to reduce the contact resistance of the ohmic contact between the first conductive metal 109 and the first ohmic contact layer 102, wherein the first ohmic contact layer can be an N-type doped ohmic contact layer. The first ohmic contact layer 102 can be formed by chemical vapor deposition.

[0075] The first reflective layer 103 may be composed of, for example, two materials with different refractive indices, including AlGaAs and GaAs, or AlGaAs with a high aluminum component and AlGaAs with a low aluminum component, and the first reflective layer 103 may be an N-type reflector, or an N-type Bragg reflector. The first active layer 1061 and the second active layer 1081 both include a stacked quantum well composite structure, which is composed of GaAs and AlGaAs, or InGaAs and AlGaAs materials stacked and arranged, and the active layer is used to convert electrical energy into light energy. The first second reflection layer 1062 and the second second reflection layer 1082 may both be composed of two materials with different refractive indices, AlGaAs and GaAs, or AlGaAs with a high aluminum component and AlGaAs with a low aluminum component, and the first second reflection layer 1062 and the second second reflection layer 1082 may both be P-type reflectors, and the first second reflection layer 1062 and the second second reflection layer 1082 may both be P-type Bragg reflectors, wherein the first second reflection layer 1062 and the second second reflection layer 1082 contain at least one AlGaAs layer with the highest Al component content as a limiting current layer for subsequent wet oxidation; in other embodiments, according to specific design requirements, the first reflection layer 103 may also contain at least one AlGaAs layer with the highest Al component content as a limiting current layer for subsequent wet oxidation. The first reflection layer 103 and the second reflection layer are used to enhance the reflection of the light generated by the active layer.

[0076] The first reflective layer 103 or the second reflective layer includes a series of alternating layers of materials with different refractive indices, wherein the effective optical thickness of each alternating layer (the thickness of the layer multiplied by the refractive index of the layer) is an odd integer multiple of a quarter of the operating wavelength of the vertical cavity surface emitting laser, that is, the effective optical thickness of each alternating layer is a quarter of the odd integer multiple of the operating wavelength of the vertical cavity surface emitting laser. Suitable dielectric materials for forming the alternating layers of the first reflective layer 103 or the second reflective layer include tantalum oxide, titanium oxide, aluminum oxide, titanium nitride, nitride silicon, etc. Suitable semiconductor materials for forming the alternating layers of the first reflective layer 103 or the second reflective layer include gallium nitride, aluminum nitride and aluminum gallium nitride. However, it is not limited thereto. In some embodiments, the first reflective layer 103 and the second reflective layer may also be formed of other materials.

[0077] The number of alternating layer pairs of the first reflective layer 103 is less than that of the second reflective layer, that is, the reflectivity of the second reflective layer is higher than that of the first reflective layer. Thus, light is emitted from the first reflective layer 103, that is, the laser in this embodiment is a bottom-emitting laser.

[0078] The first reflective layer 103 , the first second reflective layer 1062 , and the second second reflective layer 1082 can all be formed by chemical vapor deposition.

[0079] The active layer may include one or more semiconductor layers including one or more quantum well layers or one or more quantum dot layers sandwiched between corresponding pairs of barrier layers.

[0080] The first active layer 1061 and the second active layer 1081 can be formed by chemical vapor deposition.

[0081] The first second ohmic contact layer 1063 and the second second ohmic contact layer 1083 both have a P-type doped layer with a higher concentration to form an ohmic contact layer, so as to reduce the contact resistance of the ohmic contact between the second conductive metal 1084 and the second second ohmic contact layer 1083, wherein the first ohmic contact layer can be a P-type doped ohmic contact layer. The second ohmic contact layer 1063 can be formed by chemical vapor deposition.

[0082] The first insulating layer 1064 and the second insulating layer 1085 can be made of silicon nitride, silicon oxide or other insulating materials, and the second insulating layer 1085 can effectively isolate the adjacent third mesa structure. In this embodiment, the first insulating layer 1064 and the second insulating layer 1085 can be formed by chemical vapor deposition, for example.

[0083] The first electrode layer 1065 is located on the first insulating layer 1064 and partially covers the first conductive metal layer 109 to form a common cathode. The second electrode layer 1086 is located on the second insulating layer 1085 and partially covers the second conductive metal 1084. The second electrode layers 1086 of multiple light-emitting units are connected together to form an anode.

[0084] Among them, the material of the first electrode layer 1065 may include one or a combination of Au metal, Ag metal, Pt metal, Ge metal, Pd metal, Ti metal and Ni metal, and the material of the second electrode layer 1086 may include one or a combination of Au metal, Ag metal, Pt metal, Ge metal, Pd metal, Ti metal and Ni metal.

[0085] Alternatively, if Figure 3 As shown, the second groove 105 is an annular groove; the third terrace structure 108 is a cylindrical terrace.

[0086] That is to say, on the substrate 101, a plurality of array-arranged second grooves 105 are provided to form a plurality of array-arranged light-emitting units, wherein the spacing of the second grooves 105 is as small as possible, and only the gap of the wet oxidation current limiting layer 10821 in the second reflective layer 1082 can be met. Thus, the light-emitting area per unit area is increased, the power value of the laser is increased, and at the same time, the structure of the entire laser chip is made more compact.

[0087] It should be noted that the bottom thickness of the second groove 105 is greater than zero (that is, the bottom thickness of the second groove 105 relative to the contact surface between the first reflective layer 103 and the second active layer 1081 is greater than zero), that is, the first reflective layer 103 is not etched through, and the cross-sectional area of ​​each light-emitting unit is the same. The smaller the etching depth, the smaller the resistance of the light-emitting unit. In order to limit the current and make the voltage performance good, it is necessary to completely etch the active layer and part of the first reflective layer 103. Then, for the same operating current and the same energy, the smaller the resistance, the smaller the energy consumed by the light-emitting unit itself, and the larger the output energy, so that the power conversion efficiency of the light-emitting unit is greater and the performance is better. Among them, the thickness can be (angstroms), preferably

[0088] Alternatively, if Figures 4 to 8 As shown, the first groove 104 further includes a second rectangular groove 1042 , and the second rectangular groove 1042 and the first rectangular groove 1041 form a T-shaped groove or an L-shaped groove.

[0089] Optionally, the first electrode layer 1065 is electrically connected only to the first conductive metal layer 109 in the second rectangular groove 1042 .

[0090] like Figure 4 As shown, the first groove 104 is a T-shaped groove, and the first electrode layer 1065 is electrically connected only to the first conductive metal layer 109 in the second rectangular groove 1042, wherein: Figure 5 for Figure 4 The cross-sectional view of BB'. Figure 5 It can be seen that the first electrode layer 1065 is not connected to the first conductive metal layer 109 in the first rectangular groove 1041 . Figure 6 for Figure 4 From the cross-sectional view taken along line CC′, it can be seen that the first electrode layer 1065 is electrically connected to the first conductive metal layer 109 in the second rectangular groove 1042 .

[0091] In addition, if Figure 7 and Figure 8 As shown, the second rectangular groove 1042 and the first rectangular groove 1041 form an L-shaped groove.

[0092] The first electrode layer 1065 is only electrically connected to the first conductive metal layer 109 in the second rectangular groove 1042. Since the first electrode layer 1065 must maintain a predetermined safety distance from the light-emitting unit, and the electrode portion of the first electrode layer 1065 deposited in the first rectangular groove 1041 cannot be used as a pad (i.e., cannot be used as a subsequent electrical connection with other devices), the first electrode layer 1065 is electrically connected to the first conductive metal layer 109 in the second rectangular groove 1042 to reduce the width of the first rectangular groove 1041. Figure 4 In the CC' direction, only a small part of the first electrode layer 1065 is electrically connected to the first conductive metal layer 109 in the second rectangular groove 1042. Excluding the connecting part, the upper and lower parts of the first electrode layer 1065 can be used as wiring space, reducing the unusable area of ​​the first electrode layer 1065 and improving the utilization rate of the first electrode layer 1065.

[0093] Compared to Figure 3 In the arrangement of the first electrode layer 1065 and the first rectangular groove 1041, most of the area of ​​the first electrode layer 1065 is arranged in the first rectangular groove 1041, and only the left part of the first electrode layer 1065 can be used as a wiring space. Figure 4 , Figure 7 and Figure 8 The configuration in the embodiment improves the utilization rate of the first electrode layer 1065. The second rectangular groove 1042 can be located at any position on the left side of the first rectangular groove 1041.

[0094] Fig. 9 FIG. 1 is a flow chart of a method for manufacturing a vertical cavity surface emitting laser according to an embodiment of the present invention. Fig. 9 As shown, the method comprises the following steps:

[0095] S101, providing a substrate;

[0096] S102, forming a first ohmic contact layer on a surface of one side of the substrate;

[0097] S103, forming an epitaxial structure on a surface of the first ohmic contact layer facing away from the substrate, wherein the epitaxial structure includes a first reflective layer, an active layer, and a second reflective layer formed in sequence in a direction from the substrate to the first ohmic contact layer;

[0098] S104, forming a second ohmic contact layer on a surface of the epitaxial structure facing away from the first ohmic contact layer;

[0099] S105, forming a plurality of second conductive metal layers on a surface of the second ohmic contact layer facing away from the epitaxial structure;

[0100] S106, forming a third insulating layer on a side of the plurality of second conductive metal layers away from the second ohmic contact layer;

[0101] S107, forming a first trench and a plurality of second trenches, wherein the first trench is exposed to the first ohmic contact layer, and the second trenches sequentially penetrate the second ohmic contact layer, the second reflective layer, the active layer, and a portion of the first reflective layer;

[0102] S108, oxidizing the second reflective layer in the plurality of second grooves;

[0103] S109, forming a first conductive metal layer in the first trench;

[0104] S110, forming a fourth insulating layer on a surface of the third insulating layer facing away from the second conductive metal layer;

[0105] S111, forming a third trench and a plurality of fourth trenches, wherein the third trench is used to expose a portion of the first conductive metal layer; and each fourth trench is used to expose a portion of the second conductive metal layer;

[0106] S112, forming a first electrode layer and a second electrode layer.

[0107] It should be noted that, in step S107, a first groove and a plurality of second grooves are formed, wherein the first groove is exposed to the first ohmic contact layer, and the second grooves sequentially penetrate the second ohmic contact layer, the second reflective layer, the active layer and a portion of the first reflective layer;

[0108] There are several implementation methods. The first one is to form a plurality of second grooves first and then form the first groove. The second one is to form the first groove first and then form a plurality of second grooves. The third one is to form the first groove and the second groove at the same time. Step S108 and step S109 are performed according to the order of forming the first groove and the second groove. If a plurality of second grooves are formed first and then the first groove is formed, step S108 is performed first and then step S109. If a first groove is formed first and then a plurality of second grooves are formed, step S109 is performed first and then step S108. If the first groove and the second groove are formed at the same time, step S108 and step S109 are performed at the same time.

[0109] The following description will be made by taking the example of first forming a plurality of second grooves and then forming the first grooves.

[0110] like Figures 10 to 24 As shown, the method for manufacturing the vertical cavity surface emitting laser comprises the following steps:

[0111] S1, providing a substrate 201;

[0112] Among them, the substrate 201 can be any semi-insulating material suitable for forming a vertical cavity surface emitting laser. The substrate 201 is, for example, a semi-insulating GaAs substrate, which is a GaAs substrate not doped with impurities and has a very high resistance. The resistivity of the semi-insulating GaAs substrate is above 107Ω·cm. In some embodiments, a conductive substrate or an insulating substrate can also be used instead of a semi-insulating substrate. In this case, the laser array can be formed on a GaAs substrate, separated from the GaAs substrate, and then pasted to a substrate with high thermal conductivity such as an insulating AlN substrate or a conductive Cu substrate, and the substrate 101 can be an N-type substrate.

[0113] S2, forming a first ohmic contact layer 202 on one side surface of the substrate 201;

[0114] The first ohmic contact layer 202 is an N-type doped layer with a relatively high concentration to form an ohmic contact layer, so as to reduce the contact resistance of the ohmic contact between the first conductive metal and the first ohmic contact layer 202, wherein the first ohmic contact layer can be an N-type doped ohmic contact layer. The first ohmic contact layer 202 can be formed by chemical vapor deposition.

[0115] S3, forming a first reflective layer 203 on a surface of the first ohmic contact layer 202 facing away from the substrate 201;

[0116] S4, forming an active layer 204 on a surface of the first reflective layer 203 facing away from the first ohmic contact layer 202;

[0117] S5, forming a second reflective layer 205 on a surface of the active layer 204 that is away from the first reflective layer 203;

[0118] The first reflective layer 203 may be composed of two materials with different refractive indices, including AlGaAs and GaAs, or AlGaAs with a high aluminum component and AlGaAs with a low aluminum component, and the first reflective layer 203 may be an N-type reflector, and the first reflective layer 203 may be an N-type Bragg reflector. The active layer 204 includes a quantum well composite structure arranged in a stacked manner, and is composed of GaAs and AlGaAs, or InGaAs and AlGaAs materials arranged in a stacked manner. The active layer 204 is used to convert electrical energy into light energy. The second reflective layer 205 may include two materials with different refractive indices, including AlGaAs and GaAs, or AlGaAs with a high aluminum component and AlGaAs with a low aluminum component, and the second reflective layer 205 may be a P-type reflector, and the second reflective layer 205 may be a P-type Bragg reflector. The first reflective layer 103 and the second reflective layer 205 are used to enhance the reflection of the light generated by the active layer 204.

[0119] The first reflective layer 103 or the second reflective layer 205 includes a series of alternating layers of materials with different refractive indices, wherein the effective optical thickness of each alternating layer (the thickness of the layer multiplied by the refractive index of the layer) is an odd integer multiple of a quarter of the operating wavelength of the vertical cavity surface emitting laser, that is, the effective optical thickness of each alternating layer is a quarter of the odd integer multiple of the operating wavelength of the vertical cavity surface emitting laser. Suitable dielectric materials for forming the alternating layers of the first reflective layer 203 or the second reflective layer 205 include tantalum oxide, titanium oxide, aluminum oxide, titanium nitride, nitride silicon, etc. Suitable semiconductor materials for forming the alternating layers of the first reflective layer 203 or the second reflective layer 205 include gallium nitride, aluminum nitride and aluminum gallium nitride. However, it is not limited thereto. In some embodiments, the first reflective layer 203 and the second reflective layer 205 may also be formed of other materials.

[0120] The number of alternating layer pairs of the first reflective layer 203 is less than that of the second reflective layer 205 , that is, the reflectivity of the second reflective layer 205 is higher than that of the first reflective layer 203 , and thus, light is emitted from the first reflective layer 203 , that is, the laser in this embodiment is a bottom-emitting laser.

[0121] The first reflective layer 203 and the second reflective layer 205 can both be formed by chemical vapor deposition.

[0122] The active layer 204 may include one or more semiconductor layers including one or more quantum well layers or one or more quantum dot layers sandwiched between corresponding pairs of barrier layers.

[0123] The active layer 204 can be formed by chemical vapor deposition.

[0124] S6, forming a second ohmic contact layer 206 on a surface of the second reflective layer 205 facing away from the active layer 204;

[0125] The second ohmic contact layer 206 has a P-type doped layer with a higher concentration to form an ohmic contact layer, so as to reduce the contact resistance of the ohmic contact between the second conductive metal and the second ohmic contact layer 206, wherein the first ohmic contact layer can be a P-type doped ohmic contact layer. The second ohmic contact layer 206 can be formed by chemical vapor deposition.

[0126] S7, forming a plurality of second conductive metal layers 207 on a surface of the second ohmic contact layer 206 facing away from the second reflective layer 205;

[0127] S8, such as Fig.11 As shown, a third insulating layer 208 is formed on one side of the plurality of second conductive metal layers 207 away from the second ohmic contact layer 206;

[0128] In this embodiment, the second conductive metal layer 207 may be, for example, in the shape of a circular ring. In some embodiments, the second conductive metal layer 207 may also be in the shape of an elliptical ring, a rectangular ring, or a hexagonal ring. The shape of the second conductive metal layer 207 may be selected as required. (In this embodiment, only one second conductive metal layer 207 is taken as an example.) The third insulating layer 208 is formed to prevent the second conductive metal layer 207 from being oxidized.

[0129] S9, such as Figures 12 to 13 As shown, a plurality of second grooves 210 are formed, wherein the second grooves 210 sequentially penetrate the second ohmic contact layer 206, the second reflective layer 205, the active layer 204 and a portion of the first reflective layer 203;

[0130] It should be noted that after forming multiple second conductive metal layers 207, a patterned photoresist layer 209 needs to be formed on the third insulating layer 208, the patterned photoresist layer 209 exposes part of the third insulating layer 208, and the third insulating layer 208 is etched downward according to the patterned photoresist layer 209 to form multiple second grooves 210. Fig.11 The arrow direction indicates the etching direction. Fig.12 The two second grooves 210 are actually an annular groove, and a circular table is included in the middle, and the circular table is used to form a light-emitting unit.

[0131] S10, such as Fig.14 As shown, the second reflective layer 205 is oxidized;

[0132] After forming a plurality of second grooves 210 , a current limiting layer 211 needs to be formed in the mesa structure to form a light-emitting hole. In this embodiment, the sidewalls of the second grooves 210 are oxidized by high-temperature oxidation of highly doped aluminum to form a plurality of current limiting layers 211 in the second reflective layer 205 .

[0133] S11, such as Fig.15 As shown, a fourth insulating layer 212 is formed on a surface of the third insulating layer 208 that is away from the second conductive metal layer 207 ; wherein the fourth insulating layer 212 is formed to prevent the sidewall of the mesa structure in the second trench 210 from being further oxidized.

[0134] S12, such as Fig.16 and Fig.17 As shown, a first trench 213 is formed, wherein the first trench 213 is exposed to the first ohmic contact layer 202;

[0135] It should be noted that the first groove 213 may be a rectangular groove, a T-shaped groove or an L-shaped groove, and its shape may be set in advance in the patterned photoresist layer 209 .

[0136] S13, such as Fig.18 As shown, a first conductive metal layer 214 is formed in the first trench 213 ; wherein the first conductive metal layer 214 can be deposited in the first trench 213 by chemical vapor deposition, sputtering, evaporation, electroplating or chemical plating.

[0137] S14, such as Fig.19 As shown, a fifth insulating layer 215 is formed on the surface of the fourth insulating layer 212 facing away from the third insulating layer 208; wherein the fifth insulating layer 215 is to prevent Fig.18 The second reflective layer in the left mesa structure in the center orientation is oxidized.

[0138] S15, such as Fig. 20 As shown, a third trench 216 is formed, and the third trench 216 is used to expose a portion of the first conductive metal layer 214;

[0139] S16, such as Fig.21 As shown, a plurality of fourth grooves 217 are formed, each of which is used to expose a portion of the second conductive metal layer 207;

[0140] S17, forming a first electrode layer 218 and a second electrode layer 219.

[0141] It should be noted that if the first groove 213 is a rectangular groove, the formation of the first electrode layer 218 is as follows: Fig. 22 As shown in the figure, the first groove 213 is a T-shaped groove or an L-shaped groove, and the formation of the first electrode layer 218 is as follows: Fig.23As shown. It is understandable that Fig. 22 for Figure 3 Section along AA'. Fig.23 for Figure 4 Section along BB'. Fig.24 FIG. 2 is a diagram showing the formation of the second electrode layer 219. The first electrode layer 218 and the second electrode layer 219 may be formed by chemical vapor deposition.

[0142] Among them, the material of the first electrode layer 218 may include one or a combination of Au metal, Ag metal, Pt metal, Ge metal, Ti metal and Ni metal, and the material of the second electrode layer 219 may include one or a combination of Au metal, Ag metal, Pt metal, Ge metal, Ti metal and Ni metal.

[0143] To sum up, in the vertical cavity surface emitting laser and the manufacturing method thereof proposed in the embodiment of the present invention, the etched second groove does not need to be exposed to the first ohmic contact layer, and only a portion of the first reflective layer needs to be etched. Therefore, under the same light-emitting area, the resistance of the light-emitting unit is reduced, the photoelectric conversion efficiency of the light-emitting unit is improved, and the spacing between the light-emitting units is reduced, thereby increasing the light-emitting area per unit area.

[0144] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A vertical cavity surface emitting laser, characterized in that: include: substrate; A first ohmic contact layer is formed on the first surface of the substrate; A first reflective layer is formed on a surface of the first ohmic contact layer facing away from the substrate, and comprises a first groove and a plurality of second grooves, wherein the first groove is exposed to the first ohmic contact layer, and the bottom thickness of each of the second grooves is greater than zero; The first reflective layer further comprises a first mesa-shaped structure and a second mesa-shaped structure, and a plurality of third mesa-shaped structures are arranged on the second mesa-shaped structure; Along the direction from the substrate to the first ohmic contact layer, each of the third terrace structures is sequentially provided with a second active layer, a second second reflective layer, a second second ohmic contact layer, a second conductive metal layer, a second insulating layer and a second electrode layer to form a laser light-emitting unit; A plurality of second grooves arranged in an array are provided to form a plurality of light emitting units arranged in an array.

2. The vertical cavity surface emitting laser according to claim 1, characterized in that: In a direction from the substrate to the first ohmic contact layer, the first terrace structure is provided with a first active layer, a first second reflective layer, a first second ohmic contact layer, a first insulating layer and a first electrode layer in sequence; A first conductive metal is disposed at the bottom of the first trench, a first insulating layer is disposed on the sidewall, and the first insulating layer extends to the bottom of the first trench and covers a portion of the first conductive metal; The first electrode layer is electrically connected to the first conductive metal.

3. The vertical cavity surface emitting laser according to claim 2, characterized in that: The first groove includes a first rectangular groove.

4. The vertical cavity surface emitting laser according to claim 3, characterized in that: The first groove further includes a second rectangular groove, and the second rectangular groove and the first rectangular groove form a T-shaped groove or an L-shaped groove.

5. The vertical cavity surface emitting laser according to claim 4, characterized in that: The first electrode layer is electrically connected only to the first conductive metal in the second rectangular groove.

6. The vertical cavity surface emitting laser according to claim 1, characterized in that: The second insulating layer covers a portion of the second conductive metal layer and covers the bottom and sidewall of each second trench, and the second electrode layer is electrically connected to the second conductive metal layer.

7. The vertical cavity surface emitting laser according to claim 6, characterized in that: The second groove is an annular groove; the third terrace structure is a cylindrical terrace.

8. A method for manufacturing a vertical cavity surface emitting laser, implemented based on the vertical cavity surface emitting laser according to any one of claims 1 to 7, characterized in that: The following steps are involved: providing a substrate; forming a first ohmic contact layer on a surface of one side of the substrate; forming an epitaxial structure on a surface of the first ohmic contact layer facing away from the substrate, wherein the epitaxial structure includes a first reflective layer, an active layer, and a second reflective layer formed in sequence in a direction from the substrate to the first ohmic contact layer; forming a second ohmic contact layer on a surface of the epitaxial structure facing away from the first ohmic contact layer; forming a plurality of second conductive metal layers on a surface of the second ohmic contact layer facing away from the epitaxial structure; forming a third insulating layer on a side of the plurality of second conductive metal layers away from the second ohmic contact layer; forming a first groove and a plurality of second grooves, wherein the first groove is exposed to the first ohmic contact layer, and the second grooves sequentially penetrate the second ohmic contact layer, the second reflective layer, the active layer and a portion of the first reflective layer; oxidizing the second reflective layer in a plurality of the second grooves; forming a first conductive metal layer in the first trench; forming a fourth insulating layer on a surface of the third insulating layer facing away from the second conductive metal layer; forming a third trench and a plurality of fourth trenches, wherein the third trench is used to expose a portion of the first conductive metal layer; and each of the fourth trenches is used to expose a portion of the second conductive metal layer; A first electrode layer and a second electrode layer are formed.

9. The method for manufacturing a vertical cavity surface emitting laser according to claim 8, characterized in that: Forming the first trench includes: A rectangular groove is formed.

10. The method for manufacturing a vertical cavity surface emitting laser according to claim 8, characterized in that: Forming the first trench includes: A T-shaped groove or an L-shaped groove is formed.

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