Preparation method of passivation layer and vertical cavity surface emitting laser

Abstract

The invention provides a preparation method of a passivation layer and a vertical cavity surface emitting laser, and relates to the technical field of semiconductors. The method comprises the following steps: providing a substrate, wherein at least one laser is formed on the surface of the substrate; forming a first passivation layer on the surface of the at least one laser, wherein the first passivation layer has first stress; a second passivation layer is formed on the side, away from the substrate, of the first passivation layer, the second passivation layer has second stress, and the difference between the first stress and the second stress is within a preset threshold value. The preparation method of the passivation layer provided by the invention can improve the reliability of the laser.

Description

Technical Field

[0001] The present disclosure relates to the field of measurement technology, and in particular to a method for preparing a passivation layer and a vertical cavity surface emitting laser. Background Art

[0002] VCSEL (Vertical Cavity Surface Emitting Laser) is a semiconductor laser that emits laser light perpendicular to the top surface. Due to its unique advantages such as high modulation speed, circular spot that is easy to couple with optical fiber, single longitudinal mode, low threshold operating current, low power consumption, and easy large-scale integration of two-dimensional arrays, it has a wide range of applications in short-distance and ultra-short-distance optical interconnection data transmission, optical communications, supercomputers, and 5G fronthaul.

[0003] In order to stabilize the characteristics of the laser and improve the yield and reliability, a passivation layer is usually prepared on the surface of the laser to isolate the laser surface from the surrounding atmosphere. The passivation layer structure commonly used at present is a double-layer composite passivation layer. During the preparation process, due to the inconsistent thermal expansion coefficient between the composite passivation layer and the laser, it is easy to cause the large composite passivation layer to detach from the laser or crack, which is not conducive to improving the yield and reliability of the laser. Summary of the invention

[0004] In view of this, the present disclosure provides a method for preparing a passivation layer and a vertical cavity surface emitting laser, in order to at least partially solve the above-mentioned technical problems.

[0005] According to one aspect of the present disclosure, a method for preparing a passivation layer is provided, comprising: providing a substrate, wherein at least one laser is formed on the surface of the substrate; forming a first passivation layer on the surface of the at least one laser, wherein the first passivation layer has a first stress; forming a second passivation layer on the first passivation layer, wherein the second passivation layer has a second stress, wherein the difference between the first stress and the second stress is within a preset threshold.

[0006] According to an embodiment of the present disclosure, the second stress is greater than the first stress, and the preset threshold is 200 MPa.

[0007] According to an embodiment of the present disclosure, the material of the first passivation layer includes silicon nitride, and the material of the second passivation layer includes benzocyclobutene.

[0008] According to an embodiment of the present disclosure, the first stress is greater than or equal to 50 MPa and less than or equal to 500 MPa.

[0009] According to an embodiment of the present disclosure, a method for forming a first passivation layer includes: forming a first passivation layer on a surface of a laser using a PECVD process, wherein the reaction gas includes: NH 3 With SiH 4 , NH3 With SiH 4 The flow ratio is 6:1~12:1, the growth temperature is 200℃~350℃, the RF power is 30W~200W, and the reaction pressure is 66Pa~134Pa.

[0010] According to an embodiment of the present disclosure, before the step of forming the second passivation layer, an adhesion layer is formed on the surface of the first passivation layer.

[0011] According to an embodiment of the present disclosure, a method for forming a second passivation layer includes: forming liquid benzocyclobutene on the surface of the adhesion layer using a spin coating process; and performing a curing process on the liquid benzocyclobutene to form a second passivation layer at a curing temperature of 250° C. to 350° C.

[0012] According to an embodiment of the present disclosure, the rotation speed used in the spin coating process is 1000 r / min to 5000 r / min.

[0013] According to an embodiment of the present disclosure, at least one laser exposes a portion of the substrate surface, and in the step of forming a first passivation layer on the surface of at least one laser, the first passivation layer is also formed on the exposed substrate surface.

[0014] According to another aspect of the present disclosure, a vertical cavity surface emitting laser is provided, comprising: a substrate and at least one laser located on a surface of the substrate; a first passivation layer located on the surface of the at least one laser and prepared by the above-mentioned passivation layer preparation method, the first passivation layer having a first stress; a second passivation layer located on the first passivation layer, the second passivation layer having a second stress, and a difference between the first stress and the second stress being within a preset threshold.

[0015] The present disclosure provides a method for preparing a passivation layer and a vertical cavity surface emitting laser, which have at least the following beneficial effects:

[0016] The first passivation layer formed has a first stress, so that the first passivation layer generates tensile stress on the surface of the laser in advance, so that the laser is pre-deformed, and then a second passivation layer is formed on the surface of the first passivation layer, and the second passivation layer has a second stress, so that the second passivation layer generates tensile stress on the first passivation layer. The difference between the stress of the first passivation layer and the stress of the second passivation layer is controlled within a preset threshold, so that the stress of the formed second passivation layer matches that of the first passivation layer. Since the laser has been pre-deformed, even if the second passivation layer generates tensile stress in the same direction on the first passivation layer, the problem of the first passivation layer being separated from the surface of the laser due to a large deformation caused by the contraction of the second passivation layer can be avoided, thereby ensuring that the first passivation layer and the second passivation layer provide greater protection for the laser and improving the reliability of the laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] To further illustrate the technical content of the present disclosure, the following will be described in detail with reference to examples and drawings, wherein:

[0018] Figure 1 is a flowchart of a method for preparing a passivation layer according to an embodiment of the present disclosure;

[0019] Figure 2 It is a structural schematic diagram corresponding to the steps of forming a first passivation layer and a second passivation layer in a method for preparing a passivation layer according to an embodiment of the present disclosure;

[0020] Figure 3 is a schematic diagram of stress matching of a method for preparing a passivation layer according to an embodiment of the present disclosure;

[0021] Figure 4 It is a structural schematic diagram corresponding to the steps of forming a first passivation layer and a second passivation layer in another method for preparing a passivation layer according to an embodiment of the present disclosure.

[0022] Description of reference numerals:

[0023] 101. substrate, 102. emitter, 103. first passivation layer, 104. second passivation layer, 111. N-type doped Bragg reflector, 112. P-type doped Bragg reflector, 113. active layer. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present disclosure will be described clearly and completely below in combination with the embodiments and the drawings in the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0025] It should be noted that in the drawings or descriptions, similar or identical parts all use the same figure numbers. The implementation methods not shown or described in the drawings are forms known to ordinary technicians in the relevant technical field. In addition, although the demonstration of parameters containing specific values ​​can be provided herein, it should be understood that the parameters do not need to be exactly equal to the corresponding values, but can be approximated to the corresponding values ​​within an acceptable error tolerance or design constraint. In addition, the directional terms mentioned in the following embodiments, such as "upper", "lower", "front", "back", "left", "right", "inside", "outside", etc., are only referenced to the directions of the drawings. Therefore, the directional terms used are used to illustrate and not to limit the present disclosure. In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present disclosure, the descriptions of "first", "second", etc. are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" can explicitly or implicitly include at least one of the features.

[0026] Figure 1 is a flowchart of a method for preparing a passivation layer according to an embodiment of the present disclosure, Figure 2 It is a structural schematic diagram corresponding to the steps of forming a first passivation layer and a second passivation layer in a method for preparing a passivation layer according to an embodiment of the present disclosure; Figure 3 is a schematic diagram of stress matching of a method for preparing a passivation layer according to an embodiment of the present disclosure; Figure 4 FIG. 1 is a schematic structural diagram corresponding to the steps of forming a first passivation layer and a second passivation layer in another method for preparing a passivation layer according to an embodiment of the present disclosure. Figures 1 to 4 The preparation method of the passivation layer of the embodiment of the present disclosure is described in detail. It should be understood that Figures 1 to 4 The illustrations and the following descriptions are merely examples, intended to help those skilled in the art understand the solutions of the present disclosure, and are not intended to limit the scope of protection of the present disclosure.

[0027] like Figures 1 to 4 As shown, the method for preparing the passivation layer includes:

[0028] S1, providing a substrate, and forming at least one laser on a surface of the substrate 101.

[0029] In some embodiments, the substrate 101 may be any one of silicon, silicon oxide, glass, quartz, diamond, silicon carbide, indium phosphide, gallium nitride, gallium arsenide or sapphire. In some embodiments, the substrate 101 may also be a two-dimensional material such as graphene, carbon nanotubes, fullerene or molybdenum disulfide.

[0030] In some embodiments, there may be only one laser 102. In some embodiments, there may be multiple lasers 102. In some embodiments, the laser may be a vertical cavity surface emitting laser.

[0031] In some embodiments, the laser 102 includes: an N-type doped Bragg emitter 111, an active layer 113, a P-type doped Bragg emitter 112, a first electrode, and a second electrode. The N-type doped Bragg emitter 111 is located on the surface of the substrate 101, and the active layer 113 is located between the N-type doped Bragg emitter 111 and the P-type doped Bragg emitter 112. The P-type doped Bragg emitter 112 is located on the surface of the active layer 113. The orthographic projection of the P-type doped Bragg emitter 112 on the surface of the substrate 101 is located within the orthographic projection of the N-type doped Bragg emitter 111 on the surface of the substrate 101, and partially overlaps with the orthographic projection of the N-type doped Bragg emitter 111 on the surface of the substrate 101. The first electrode is located on the surface of the N-type doped Bragg emitter 111, and the second electrode is located on the surface of the P-type doped Bragg emitter 112.

[0032] In some embodiments, a method of forming a transmitter may include:

[0033] First, an N-type doped Bragg emitter 111 is formed on the substrate 101. The N-type doped Bragg emitter 111 is formed by alternately stacking N-type doped first semiconductor layers and N-type doped second semiconductor layers. The refractive index of the first semiconductor layer is greater than that of the second semiconductor layer.

[0034] In some embodiments, an epitaxial growth process may be used to form the alternately stacked first semiconductor layers and second semiconductor layers.

[0035] Next, an active layer 113 is formed on the N-type doped Bragg emitter 111 . In some embodiments, the active layer 113 is composed of 1 to 3 quantum wells.

[0036] Then, a P-type doped Bragg emitter 112 is formed on the surface of the active layer 113. The P-type doped Bragg emitter 112 is formed by alternately stacking a P-type doped third semiconductor layer and a P-type doped fourth semiconductor layer. The refractive index of the third semiconductor layer is greater than that of the fourth semiconductor layer.

[0037] In some embodiments, an epitaxial growth process may be used to form the alternately stacked third semiconductor layers and fourth semiconductor layers.

[0038] Finally, an electroplating process may be used to form a first electrode on the surface of the N-type doped Bragg reflector and a second electrode on the surface of the P-type doped Bragg reflector.

[0039] In some embodiments, the material of the first electrode may be a nickel-copper alloy, and the material of the second electrode may be a nickel-copper alloy.

[0040] S2, forming a first passivation layer 103 on a surface of at least one laser 102, wherein the first passivation layer 103 has a first stress.

[0041] Under the action of the first stress, the first passivation layer 103 will generate tensile stress on the surface of the laser 102 in advance, so that the laser 102 is pre-deformed. Figure 4 , the first passivation layer 103 will drive the laser 102 to contract and deform along the D1 direction. In this way, after the second passivation layer is formed, even if the second stress generated by the second passivation layer causes the first passivation layer 103 to deform in the D1 direction, since the laser 102 has been pre-deformed along the D1 direction, the deformation degree of the first passivation layer 103 relative to the laser 102 is not too large, thereby avoiding the problem of the first passivation layer 103 falling off from the surface of the laser 102 due to the deformation degree of the first passivation layer 103 being too large compared to the deformation degree of the laser 102.

[0042] In some embodiments, the first stress is greater than or equal to 50 MPa and less than or equal to 500 MPa. For example, it can be 50 MPa, 60 MPa, 80 MPa, 100 MPa, 120 MPa, 150 MPa, 180 MPa, 200 MPa, 230 MPa, 260 MPa, 300 MPa, 350 MPa, 380 MPa, 420 MPa or 500 MPa. Within this range, the first stress is large enough to cause the first passivation layer 103 to drive the emitter to pre-deform without causing the first passivation layer 103 to fall off directly from the emitter surface.

[0043] In some embodiments, the first passivation layer 103 is located on the surface of the P-type doped Bragg emitter 112 except the second electrode and on the surface of the N-type doped Bragg emitter 111 except the first electrode.

[0044] In some embodiments, the method for forming the first passivation layer 103 includes: forming the first passivation layer 103 on the surface of the laser 102 by using a PECVD (plasma enhanced chemical vapor deposition) process, wherein the reaction gas includes: NH 3 With SiH 4 , NH 3 With SiH 4The flow ratio is 6:1 to 12:1, for example, it can be 6:1, 7:1, 8:1, 9:1, 10:1, 11:1 or 12:1. The growth temperature of the first passivation layer 103 is 200°C to 350°C, for example, it can be 200°C, 230°C, 250°C, 280°C, 300°C, 320°C or 350°C. The RF power is 30W to 200W, for example, it can be 30W, 60W, 90W, 120W, 150W, 180W or 200W. The reaction pressure is 66Pa to 134Pa, for example, it can be 66Pa, 80Pa, 93Pa, 106Pa, 120Pa or 134Pa. Under the above process conditions, the first stress of the first passivation layer 103 can be controlled so that the first stress meets expectations.

[0045] In some embodiments, the material of the first passivation layer 103 may be silicon nitride, and the thickness of the first passivation layer 103 may be 5 nm to 1000 nm, for example, 5 nm, 50 nm, 80 nm, 150 nm, 200 nm, 230 nm, 260 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm or 1000 nm. Within the above thickness range, the thickness of the first passivation layer 103 matches the desired first stress value, so that the first passivation layer 103 can drive the laser 102 to deform under the action of the first stress without causing the first passivation layer 103 to fall off directly from the surface of the laser 102.

[0046] In some embodiments, at least one laser 102 exposes a portion of the surface of the substrate 101, and in the step of forming the first passivation layer 103 on the surface of at least one laser 102, the first passivation layer 103 is also formed on the exposed surface of the substrate 101. In other words, the laser 102 is only formed on a portion of the surface of the substrate 101, so that a portion of the surface of the substrate 101 is exposed. In the step of forming the first passivation layer 103, the first passivation layer 103 is also formed on the exposed surface of the substrate 101.

[0047] It can be understood that if the first passivation layer 103 is still located on the surface of the substrate 101, the first stress generated by the first passivation layer 103 will also give a tensile stress to the surface of the substrate 101, causing the substrate 101 to be pre-deformed. In this way, after the second passivation layer is subsequently formed, even if the second stress generated by the second passivation layer causes the first passivation layer 103 to be deformed, since the substrate 101 has been pre-deformed, the deformation degree of the first passivation layer 103 relative to the substrate 101 is not too large, thereby avoiding the problem of the first passivation layer 103 falling off from the surface of the substrate 101 due to the deformation degree of the first passivation layer 103 being too large compared to the deformation degree of the substrate 101.

[0048] S3, forming a second passivation layer 104 on the first passivation layer 103, the second passivation layer 104 has a second stress, and the difference between the first stress and the second stress is within a preset threshold.

[0049] The second passivation layer 104 covers the first passivation layer 103. In some embodiments, the orthographic projection of the second passivation layer 104 on the surface of the substrate 101 coincides with the orthographic projection of the first passivation layer 103 on the surface of the substrate 101.

[0050] In some embodiments, the second stress is greater than the first stress, and the preset threshold is 200 MPa. Within this range, the stress of the formed second passivation layer 104 matches that of the first passivation layer 103, preventing the first passivation layer 103 from being detached from the laser 102 due to the excessive second stress causing a large deformation of the first passivation layer 103.

[0051] In some embodiments, before forming the second passivation layer 104, an adhesion layer is formed on the surface of the first passivation layer 103. In this way, the adhesion between the first passivation layer 103 and the second passivation layer 104 is strong.

[0052] In some embodiments, the step of forming the adhesion layer includes:

[0053] The adhesive is spin-coated on the surface of the first passivation layer 103 by a spin coating process at a rotation speed of 2000 r / min to 3500 r / min, and then baked on a hot plate at 80° C. to 140° C. for 50s to 80s to form an adhesive layer.

[0054] After forming the adhesion layer, the second passivation layer 104 is formed.

[0055] In some embodiments, the material of the first passivation layer 103 includes silicon nitride, and the material of the second passivation layer 104 includes benzocyclobutene (BCB). The use of a composite structure of silicon nitride and benzocyclobutene can achieve good step coverage, and both benzocyclobutene and silicon nitride have good electrical insulation properties, and therefore have good passivation properties. It can also avoid the problem of poor thermal stress caused by using a single layer of silicon nitride and the problem of poor step coverage caused by using a single layer of benzocyclobutene.

[0056] In some embodiments, the method of forming the second passivation layer 104 includes:

[0057] A spin coating process is adopted to form liquid benzocyclobutene on the surface of the adhesion layer.

[0058] In some embodiments, the rotation speed used in the spin coating process is 1000r / min~5000r / min, for example, it can be 1000r / min~1500r / min, 1500r / min~2000r / min, 2000r / min~2500r / min, 2500r / min~3000r / min, 3000r / min~3500r / min, 3500r / min~4000r / min, 4000r / min~4500r / min or 4500r / min~5000r / min.

[0059] The liquid benzocyclobutene is cured to form the second passivation layer 104 at a curing temperature of 250° C. to 350° C., for example, 250° C. to 270° C., 270° C. to 285° C., 285° C. to 300° C., 300° C. to 315° C., 315° C. to 330° C. or 330° C. to 350° C. Within this range, the stress of the formed second passivation layer 104 meets expectations.

[0060] In some embodiments, liquid benzocyclobutene may be solidified in a nitrogen atmosphere, for example, in a nitrogen-filled oven to obtain solid benzocyclobutene as the second passivation layer 104 .

[0061] In the method for preparing the passivation layer provided in the above embodiment, the difference between the stress of the first passivation layer 103 and the stress of the second passivation layer 104 is controlled within a preset threshold value, so that the stress of the formed second passivation layer 104 matches that of the first passivation layer 103. The first stress generated by the first passivation layer 103 generates a tensile stress on the surface of the laser 102 in advance, so that the laser 102 is pre-deformed. In this way, even if the second passivation layer 104 generates a tensile stress in the same direction on the first passivation layer 103, the problem of the first passivation layer 103 being separated from the surface of the laser 102 due to a large deformation caused by the contraction of the second passivation layer 104 can be avoided.

[0062] Another aspect of the present disclosure provides a vertical cavity surface emitting laser 102, referring to Figure 2 The vertical cavity surface emitting laser 102 includes: a substrate 101 and at least one laser 102 located on the surface of the substrate 101; a first passivation layer 103 located on the surface of the at least one laser 102 and prepared by the passivation layer preparation method provided by the above embodiment, wherein the first passivation layer 103 has a first stress; a second passivation layer 104 located on the first passivation layer 103, wherein the second passivation layer 104 has a second stress, and the difference between the first stress and the second stress is within a preset threshold.

[0063] In some embodiments, the substrate 101 may be any one of silicon, silicon oxide, glass, quartz, diamond, silicon carbide, indium phosphide, gallium nitride, gallium arsenide or sapphire. In some embodiments, the substrate 101 may also be a two-dimensional material such as graphene, carbon nanotubes, fullerene or molybdenum disulfide.

[0064] In some embodiments, there may be only one laser 102 , and in some embodiments, there may be multiple lasers 102 .

[0065] In some embodiments, the laser 102 includes: an N-type doped Bragg emitter 111, an active layer 113, a P-type doped Bragg emitter 112, a first electrode, and a second electrode. The N-type doped Bragg emitter 111 is located on the surface of the substrate 101, and the active layer 113 is located between the N-type doped Bragg emitter 111 and the P-type doped Bragg emitter 112. The P-type doped Bragg emitter 112 is located on the surface of the active layer 113. The orthographic projection of the P-type doped Bragg emitter 112 on the surface of the substrate 101 is located within the orthographic projection of the N-type doped Bragg emitter 111 on the surface of the substrate 101, and partially overlaps with the orthographic projection of the N-type doped Bragg emitter 111 on the surface of the substrate 101. The first electrode is located on the surface of the N-type doped Bragg emitter 111, and the second electrode is located on the surface of the P-type doped Bragg emitter 112.

[0066] In some embodiments, the N-type doped Bragg emitter 111 is formed by alternately stacking N-type doped first semiconductor layers and N-type doped second semiconductor layers, and the refractive index of the first semiconductor layer is greater than the refractive index of the second semiconductor layer.

[0067] In some embodiments, the P-type doped Bragg emitter 112 is formed by alternately stacking a P-type doped third semiconductor layer and a P-type doped fourth semiconductor layer, and the refractive index of the third semiconductor layer is greater than the refractive index of the fourth semiconductor layer.

[0068] In some embodiments, the material of the first electrode may be a nickel-copper alloy, and the material of the second electrode may be a nickel-copper alloy.

[0069] In some embodiments, the material of the first passivation layer 103 may be silicon nitride, and the thickness of the first passivation layer 103 may be 5 nm to 1000 nm, for example, 5 nm, 50 nm, 80 nm, 150 nm, 200 nm, 230 nm, 260 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm or 1000 nm. Within the above thickness range, the thickness of the first passivation layer 103 matches the desired first stress value, so that the first passivation layer 103 can drive the laser 102 to deform under the action of the first stress without causing the first passivation layer 103 to fall off directly from the surface of the laser 102.

[0070] In some embodiments, an adhesion layer is disposed between the first passivation layer 103 and the second passivation layer 104 to improve adhesion between the first passivation layer 103 and the second passivation layer 104 .

[0071] In some embodiments, the material of the second passivation layer 104 may be benzocyclobutene.

[0072] In the vertical cavity surface emitting laser 102 provided in the above embodiment, the difference between the stress of the first passivation layer 103 and the stress of the second passivation layer 104 is within a preset threshold, so that the stress of the formed second passivation layer 104 matches the stress of the first passivation layer 103, which can avoid the problem of the first passivation layer 103 detaching from the surface of the laser 102 due to a large deformation caused by the contraction of the second passivation layer 104, thereby ensuring that the first passivation layer 103 and the second passivation layer 104 provide greater protection for the laser 102 and improving the reliability of the laser 102.

[0073] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present disclosure in detail. It should be understood that the above are only specific embodiments of the present disclosure and are not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A method for preparing a passivation layer, characterized in that: include: Providing a substrate, wherein at least one laser is formed on a surface of the substrate; forming a first passivation layer on the surface of the at least one laser, wherein the first passivation layer has a first stress; A second passivation layer is formed on the first passivation layer, the second passivation layer has a second stress, and a difference between the first stress and the second stress is within a preset threshold.

2. The method for preparing a passivation layer according to claim 1, characterized in that: The second stress is greater than the first stress, and the preset threshold is 200 MPa.

3. The method for preparing a passivation layer according to claim 2, characterized in that: The material of the first passivation layer includes silicon nitride, and the material of the second passivation layer includes benzocyclobutene.

4. The method for preparing a passivation layer according to claim 3, characterized in that: The first stress is greater than or equal to 50 MPa and less than or equal to 500 MPa.

5. The method for preparing a passivation layer according to claim 4, characterized in that: The method for forming the first passivation layer includes: using a PECVD process to form the first passivation layer on the surface of the laser, wherein the reaction gas includes: NH3 and SiH4, the flow ratio of NH3 to SiH4 is 6:1~12:1, the growth temperature is 200℃~350℃, the RF power is 30W~200W, and the reaction pressure is 66Pa~134Pa.

6. The method for preparing a passivation layer according to claim 3, characterized in that: Before the step of forming the second passivation layer, an adhesion layer is formed on the surface of the first passivation layer.

7. The method for preparing a passivation layer according to claim 6, characterized in that: The method of forming the second passivation layer includes: Using a spin coating process to form liquid benzocyclobutene on the surface of the adhesion layer; The liquid benzocyclobutene is subjected to a curing process to form the second passivation layer, and the curing temperature is 250° C. to 350° C.

8. The method for preparing a passivation layer according to any one of claim 7, characterized in that: The rotation speed used in the spin coating process is 1000 r / min to 5000 r / min.

9. The method for preparing a passivation layer according to claim 8, characterized in that: The at least one laser exposes a portion of the substrate surface, and in the step of forming a first passivation layer on the surface of the at least one laser, the first passivation layer is also formed on the exposed substrate surface.

10. A vertical cavity surface emitting laser, characterized in that: include: A substrate and at least one laser located on a surface of the substrate; A first passivation layer located on the surface of the at least one laser and prepared by the method for preparing a passivation layer according to any one of claims 1 to 9, wherein the first passivation layer has a first stress; The second passivation layer located on the first passivation layer is prepared by the passivation layer preparation method according to any one of claims 1 to 9, the second passivation layer has a second stress, and the difference between the first stress and the second stress is within a preset threshold.

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