Vertical cavity surface emitting laser
By introducing an etching stop layer into a vertical cavity surface-emitting laser, the problem of inflexible adjustment of the passivation layer thickness is solved, thereby improving the laser's output performance and system stability.
Patent Information
- Application Number
- CN202511727221.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-24
- Publication Date
- 2026-02-17
AI Technical Summary
In the prior art, the reflected light from the coupled optical link system of a vertical cavity surface-emitting laser (VCSEL) returns from the exit window, affecting the laser's fundamental transverse mode, leading to a decrease in the stability of the optical link system, and making the passivation layer thickness adjustment inflexible.
By introducing an etch stop layer between the first passivation structure and the second passivation layer, ensuring that the etch stop layer and the second passivation layer are made of different materials, the thickness of the passivation layer in the opening area can be precisely controlled, forming an opening area that overlaps with the light-emitting area, thereby improving the flexibility and accuracy of thickness adjustment.
Precise control of the passivation layer thickness was achieved, improving the light output performance and system stability of the vertical cavity surface-emitting laser.
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Figure CN121546430A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of laser technology, and more particularly to a vertical cavity surface-emitting laser. Background Technology
[0002] A vertical-cavity surface-emitting laser (VCSEL) is a semiconductor laser diode that emits a laser beam perpendicular to its surface. VCSELs can be tested during the production process. They are widely used in various fields, such as fiber optic communication, biometrics, lidar, medical aesthetics, and industrial cutting. Due to their advantages such as small size, high power, ease of integration, and stable operation, VCSELs are widely applied in optical communication, optical interconnects, and optical storage.
[0003] Vertical-cavity surface-emitting lasers (VCSELs) or multi-junction VCSELs require small divergence angles. Current chip fabrication processes can employ surface relief (SR) or emitters nitride (EN) processes to limit higher-order transverse modes, thereby modifying the beam pattern and reducing the divergence angle. However, in these technologies, reflected light from the coupled optical link system returns to the VCSEL from the exit window, adversely affecting the laser's fundamental transverse modes and reducing the overall stability of the optical link system. Therefore, how to flexibly adjust the passivation layer thickness in the exit region of a VCSEL has become a pressing technical problem that needs to be solved. Summary of the Invention
[0004] This invention provides a vertical cavity surface-emitting laser (VCSEL) to improve the flexibility of passivation layer thickness adjustment and enhance the light output performance of the VCSEL.
[0005] The present invention provides a vertical cavity surface-emitting laser, comprising: a first electrode layer, a substrate, a first reflective layer, a light-emitting layer, an oxide layer, a second reflective layer, a first passivation structure, an etch stop layer, a second passivation layer, and a second electrode layer, which are sequentially stacked.
[0006] The vertical cavity surface emitter (VCSEL) further includes an emitting region and a non-emitting region; the second passivation layer includes an opening region and a non-opening region; in the thickness direction of the VCSEL, the emitting region overlaps with the opening region, and the non-emitting region overlaps with the non-opening region.
[0007] Optionally, the second passivation layer has a high etch selectivity ratio with the etch stop layer.
[0008] Optionally, the etching stop layer includes a groove region and a non-groove region;
[0009] In the thickness direction of the vertical cavity surface-emitting laser, the groove region overlaps with the opening region, and the non-groove region overlaps with the non-emitting region.
[0010] Optionally, the etch stop layer includes etch openings;
[0011] In the thickness direction of the vertical cavity surface-emitting laser, the etched opening region overlaps with the light-emitting region.
[0012] Optionally, the vertical-cavity surface-emitting laser also includes:
[0013] The third passivation layer is located on the side of the second electrode layer that faces away from the substrate.
[0014] Optionally, the first passivation structure includes at least two sub-passivation layers.
[0015] Optionally, the first passivation structure includes a first sub-passivation layer and a second sub-passivation layer.
[0016] Optionally, the etching stop layer includes silicon dioxide, aluminum oxide, or silicon oxynitride.
[0017] Optionally, the second passivation layer comprises silicon nitride.
[0018] Optionally, the vertical cavity surface-emitting laser further includes a first ohmic metal, which is located on the side of the second reflective layer opposite to the first electrode layer and is disposed in the same layer as the first passivation structure.
[0019] The technical solution provided by this invention uses an etching stop layer between the first passivation structure and the second passivation layer. The etching stop layer and the second passivation layer are made of different materials, so that the material of the etching stop layer is not removed when the second passivation layer is etched. After etching the passivation material of the second passivation layer in the light-emitting region, an opening region overlapping with the light-emitting region can be formed in the second passivation layer. This allows for precise control of the thickness of the passivation layer in the opening region, improving the control accuracy of the passivation layer thickness in the opening region and enhancing the light output effect of the vertical cavity surface emitter laser. Attached Figure Description
[0020] Figure 1 A schematic diagram of a vertical cavity surface-emitting laser provided in an embodiment of the present invention.
[0021] Figure 2 A schematic diagram of another vertical cavity surface-emitting laser provided in an embodiment of the present invention;
[0022] Figure 3 A schematic diagram of another vertical cavity surface-emitting laser provided in an embodiment of the present invention;
[0023] Figure 4 A schematic diagram of another vertical cavity surface-emitting laser provided in an embodiment of the present invention;
[0024] Figure 5 This is a schematic diagram of a vertical cavity surface-emitting laser provided in an embodiment of the present invention. Detailed Implementation
[0025] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.
[0026] Figure 1 A schematic diagram of a vertical cavity surface-emitting laser provided in an embodiment of the present invention is shown below. Figure 1 As shown, the vertical-cavity surface-emitting laser 100 includes a first electrode layer 11, a substrate 12, a first reflective layer 13, a light-emitting layer 14, an oxide layer 15, a second reflective layer 16, a first passivation structure 17, an etch stop layer 18, a second passivation layer 19, and a second electrode layer 20, which are stacked sequentially. The vertical-cavity surface-emitting laser 100 also includes a light-emitting region A1 and a non-light-emitting region A2; the second passivation layer 19 includes an opening region 191 and a non-opening region 192; in the thickness direction Z of the vertical-cavity surface-emitting laser, the light-emitting region A1 overlaps with the opening region 191, and the non-light-emitting region A2 overlaps with the non-opening region 192.
[0027] The first electrode layer 11 and the second electrode layer 20 may include alloys of molybdenum, germanium, palladium, ruthenium, gold, aluminum, magnesium, copper, tungsten, titanium, iridium, argon, chromium, platinum, or other metals. The first electrode layer 11 and the second electrode layer 20 may be either N-type or P-type electrode layers; for example, the first electrode layer 11 is an N-type electrode layer and the second electrode layer 12 is a P-type electrode layer. The first reflective layer 13 and the second reflective layer 16 include distributed Bragg mirrors; for example, the first reflective layer 13 is an N-type distributed Bragg mirror and the second reflective layer 16 is a P-type distributed Bragg mirror. The light-emitting layer 14 includes multiple quantum wells, etc. The oxide layer 15 includes oxide materials such as aluminum oxide, which can be set according to actual needs and are not specifically limited here. The first passivation structure 17 includes materials such as silicon nitride.
[0028] Specifically, the different materials of the etch stop layer 18 and the second passivation layer 19 result in different etch formulations for the two. Consequently, when removing the passivation material of the second passivation layer 19 located in the opening region 191, the passivation material of the etch stop layer 18 will not be removed. This ensures that the thickness C1 of the passivation layer in the light-emitting region A1 is the sum of the thickness of the first passivation structure 17 and the thickness of the etch stop layer 18, thereby improving the control precision of the passivation layer thickness in the light-emitting region A1. This also prevents the passivation layer thickness in the light-emitting region A1 from being too large and affecting the light emission effect, thus improving the light output effect of the vertical cavity surface-emitting laser.
[0029] The technical solution of this invention uses an etch stop layer between the first passivation structure and the second passivation layer. The etch stop layer is made of a different material than the second passivation layer, so that the material of the etch stop layer is not removed when the second passivation layer is etched. After the passivation material of the second passivation layer is etched in the light-emitting region, an opening region overlapping with the light-emitting region can be formed in the second passivation layer. This allows for precise control of the thickness of the passivation layer in the opening region, improving the control accuracy of the passivation layer thickness in the opening region and enhancing the light output effect of the vertical cavity surface emitter laser.
[0030] Understandably, when fabricating a vertical-cavity surface-emitting laser (VCSEL), the thicknesses of the first passivation structure 17 and the etch stop layer 18 can be controlled to ensure that the sum of their thicknesses meets design requirements and improves application performance. (Reference) Figure 1 The vertical cavity surface emitter laser 100 also includes a first ohmic metal 101, which is located on the side of the second reflective layer 16 away from the first electrode layer 11 and is disposed in the same layer as the first passivation structure 17. The second electrode layer 20 is electrically connected to the first ohmic metal 101 so that an electrical signal is applied to the first ohmic metal 101 through the second electrode layer 20, so that the first ohmic metal 101 excites the light-emitting layer 14 to emit a laser beam under the action of the electrical signal.
[0031] It should be noted that the top view structure of the first ohmic metal 101 can be set according to actual needs. In an optional embodiment, the top view structure of the first ohmic metal 101 is annular, but it can also be other shapes, which are not specifically limited here. The first ohmic metal 101 and the second electrode 20 can be manufactured in the same step, or they can be manufactured in different steps, depending on the actual design.
[0032] Optionally, the second passivation layer 19 has a high etch selectivity ratio with the etch stop layer 18.
[0033] A high etching selectivity ratio indicates that the ratio of the etching rate of the second passivation layer 19 to the etching rate of the etching stop layer 18 is relatively large.
[0034] Specifically, the second passivation layer 19 and the etch stop layer 18 have a high etch selectivity ratio, which means that during the removal of the second passivation layer 19, the etching process will automatically stop when the etch stop layer 18 is reached, thereby achieving precise control of the etching depth and thus achieving precise control of the passivation layer thickness in the light-emitting region A1.
[0035] Optional, Figure 2 A schematic diagram of another vertical cavity surface-emitting laser provided in an embodiment of the present invention is shown below. Figure 2 As shown, the etching stop layer 18 includes a groove region 181 and a non-groove region 182; in the thickness direction Z of the vertical cavity surface-emitting laser, the groove region 181 overlaps with the opening region 181, and the non-groove region 182 overlaps with the non-emitting region A2.
[0036] The thickness of the grooved region 181 is less than the thickness of the non-grooved region 182.
[0037] Specifically, when it is necessary to control the reduction of the passivation layer thickness within the light-emitting region A1, an etching solution can be used to etch the etch stop layer 18 overlapping with the light-emitting region A1, based on the second passivation layer 19 including the opening area. This removes part of the material in the etch stop layer 18 overlapping with the light-emitting region A1, forming a groove region 181. If the thickness of the first passivation structure 17 is a, the thickness of the etch stop layer 18 is b, and the etching thickness within the groove region 181 is f, then the total passivation layer thickness C2 of the light-emitting region A1 is the sum of the thickness a of the first passivation structure 17 and the thickness b of the etch stop layer 18, minus the etching thickness f. The etching selectivity ratio of the second passivation layer 19 to the etch stop layer 18 can be reduced to partially remove the etch stop layer 18 while etching the second passivation layer 19. The remaining thickness of the groove region 181 can be set according to actual needs to suit different application requirements.
[0038] Optional, Figure 3 A schematic diagram of another vertical-cavity surface-emitting laser provided in an embodiment of the present invention is shown below. Figure 3 As shown, the etching stop layer 18 includes an etching opening 180; in the thickness direction Z of the vertical cavity surface-emitting laser, the etching opening 180 overlaps with the light-emitting region A1.
[0039] In this process, after selective etching, the etching stop material at the etching opening 180 of the etching stop layer 18 is etched away. That is, the thickness of the etching opening 180 is the same as the thickness of the etching stop layer 18. If the thickness of the etching stop layer 18 is b, then the thickness of the etching opening 180 is also b.
[0040] Specifically, when it is necessary to further reduce the thickness of the passivation layer in the light-emitting region A1, the material of the etching stop layer 18 overlapping with the light-emitting region A1 can be removed to form an etching opening 180, thereby reducing the thickness of the passivation layer in the light-emitting region A1. At this time, the thickness C3 of the passivation layer in the light-emitting region A1 is the thickness of the first passivation structure 17. By reasonably designing the thickness of the first passivation structure 17, the thickness of the light-emitting region A1 can meet the design requirements and improve the light-emitting effect of the light-emitting region A1.
[0041] Optional, Figure 4 A schematic diagram of another vertical-cavity surface-emitting laser provided in an embodiment of the present invention is shown below. Figure 4 As shown, the vertical cavity surface-emitting laser 100 also includes a third passivation layer 21, located on the side of the second electrode layer 20 away from the substrate 13.
[0042] The third passivation layer 21 includes materials such as silicon oxide, which can be set according to actual needs, and no specific limitation is made here.
[0043] Specifically, by providing a third passivation layer 21 on the side of the second electrode layer 20 facing away from the substrate 13, the third passivation layer 21 can protect the second electrode layer 20 from the intrusion of external moisture and other contaminants, thereby improving the operational reliability and safety of the second electrode layer 20. Furthermore, the passivation layer thickness in the light-emitting region A1 is also increased to meet the requirements of scenarios where increased passivation layer thickness is necessary, while simultaneously improving the protection effect of the vertical-cavity surface-emitting laser 100.
[0044] Optionally, the first passivation structure 17 includes at least two sub-passivation layers.
[0045] in, Figure 5 A schematic diagram of a vertical cavity surface-emitting laser provided in an embodiment of the present invention is shown below. Figure 5 As shown, the first passivation structure 17 includes a first sub-passivation layer 171 and a second sub-passivation layer 172.
[0046] Specifically, after the second reflective layer 16 is fabricated, the second reflective layer 16, the oxide layer 15 (which is not yet oxidized), and the light-emitting layer 14 need to be etched to form grooves. Oxidizing gas is then introduced into the grooves to react with the material in the oxide layer 15 (which is not yet oxidized) to form the oxide layer 15. The unoxidized oxide layer 15 can include high-alumina AlGaAs or AlAs, which oxidizes to form aluminum oxide. During the formation of the oxide layer 15, to protect the side of the second reflective layer 16 facing away from the substrate 13, a first sub-passivation layer 171 can be provided on the second reflective layer 16. After oxidation, a second sub-passivation layer 172 can be provided on top of the first sub-passivation layer 171. The second sub-passivation layer 172 covers the first sub-passivation layer 171 and the etched groove surface to protect the exposed light-emitting layer 14, oxide layer 15, and second reflective layer 16, preventing external moisture from entering the interior of the vertical-cavity surface-emitting laser and improving the light output performance of the vertical-cavity surface-emitting laser.
[0047] It should be noted that, based on the first passivation structure 17 including at least two sub-passivation layers, the first passivation structure 17 may also include three or more sub-passivation layers, which can be set according to actual needs. When it is necessary to set the vertical cavity surface-emitting laser to have a thicker structure, the number of sub-passivation layers or the thickness of the sub-passivation layers in the first passivation structure 17 can be increased to meet the thickness requirements of the vertical cavity surface-emitting laser and improve the structural diversity of the vertical cavity surface-emitting laser.
[0048] Optionally, the etch stop layer 18 may include silicon dioxide, aluminum oxide, or silicon oxynitride.
[0049] Specifically, silicon dioxide (SiO2) possesses high chemical stability, high insulation, high transparency, high resistivity, high dielectric strength (withstanding high voltage), and a relatively low dielectric constant. It exhibits high transmittance in the visible and near-infrared bands, improving the transmittance of the emitted laser beam from a vertical-cavity surface-emitting laser (VCSEL). Alumina (SiO2) exhibits excellent chemical stability, strong corrosion resistance, strong oxidation resistance, good barrier properties against water and many corrosive gases, and excellent insulation properties. It can also be fabricated into highly transparent films to enhance the output efficiency of VCSELs. Silicon oxynitride (SiO2) can be considered an "alloy" of silicon dioxide (SiO2) and silicon nitride (Si3N4), and its properties can be continuously adjusted by regulating the nitrogen-to-oxygen ratio (N:O). SiO2 has good chemical stability, strong corrosion resistance, good insulation, high transmittance, is dense, and hard, preventing impurities from penetrating the device. Therefore, using these materials as etching stop layers can improve the protection of VCSELs and enhance their output efficiency.
[0050] It should be noted that the etching stop layer shown above may include silicon dioxide, aluminum oxide, or silicon oxynitride. In other optional embodiments, the etching stop layer may also include materials such as poly(p-phenylenebenzobisoxazole) fiber (PBO), benzocyclobutene (BCB), silicon nitride (SiN), indium tin oxide (ITO), aluminum nitride (AlN), zinc oxide (ZnO), or fluoride films (such as MgF2 or CaF2), which can be set according to actual needs. Furthermore, to achieve a higher etching selectivity between the second passivation layer 19 and the etching stop layer 18, the material of the second passivation layer 19 may be different from the material of the etching stop layer 18. In an optional embodiment, the second passivation layer 19 includes silicon nitride.
[0051] Specifically, silicon nitride has a dense atomic structure and high bond energy, which resists chemical corrosion and can effectively achieve water and oxygen barrier. In other optional embodiments, the second passivation layer 19 may also include materials such as silicon oxynitride, aluminum nitride, or fluoride films, which can be set according to actual needs.
[0052] In other alternative embodiments, when the second passivation layer 19 is silicon nitride, the etch stop layer 18 can be made of a material other than silicon oxide. The materials of the second passivation layer 19 and the etch stop layer 18 can be interchanged, or the positions of the second passivation layer 19 and the etch stop layer 18 can be interchanged. For example, the second passivation layer 19 can be aluminum oxide and the etch stop layer 18 can be silicon nitride, or other materials can be used, without specific limitations here.
[0053] Based on the same inventive concept, the present invention also provides an electronic device, which includes the vertical-cavity surface-emitting laser provided in any embodiment of the present invention. The electronic device includes, but is not limited to, optical modules and integrated optoelectronic chips. For example, the electronic device includes a robotic vacuum cleaner, etc., and can be configured according to actual needs; no specific limitations are made here. Therefore, this electronic device possesses the technical features of the vertical-cavity surface-emitting laser provided in the embodiments of the present invention and can achieve the beneficial effects of the vertical-cavity surface-emitting laser provided in the embodiments of the present invention. Similarities can be referred to the above description of the vertical-cavity surface-emitting laser provided in the embodiments of the present invention, and will not be repeated here.
[0054] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.
Claims
1. A vertical cavity surface emitting laser, characterized by Comprise: a first electrode layer, a substrate, a first reflective layer, a light emitting layer, an oxidation layer, a second reflective layer, a first passivation structure, an etching stop layer, a second passivation layer and a second electrode layer are sequentially stacked; The vertical cavity surface emitting laser further comprises a light emitting region and a non-light emitting region; the second passivation layer comprises an opening region and a non-opening region; in the thickness direction of the vertical cavity surface emitting laser, the light emitting region overlaps with the opening region, and the non-light emitting region overlaps with the non-opening region.
2. The vertical cavity surface emitting laser according to claim 1, characterized in that The second passivation layer has a high etching selectivity ratio with the etching stop layer.
3. The vertical cavity surface emitting laser of claim 1, wherein, The etching stop layer comprises a groove region and a non-groove region; In the thickness direction of the vertical cavity surface emitting laser, the groove region overlaps with the opening region, and the non-groove region overlaps with the non-light emitting region.
4. The vertical cavity surface emitting laser of claim 1, wherein, The etching stop layer comprises an etching opening; In the thickness direction of the vertical cavity surface emitting laser, the etching opening region overlaps with the light emitting region.
5. The vertical cavity surface emitting laser of claim 1, wherein, Further comprise: A third passivation layer is located on the side of the second electrode layer away from the substrate.
6. The vertical cavity surface emitting laser of claim 1, wherein, The first passivation structure comprises at least two sub-passivation layers.
7. The vertical cavity surface emitting laser of claim 6, wherein, The first passivation structure comprises a first sub-passivation layer and a second sub-passivation layer.
8. The vertical cavity surface emitting laser of claim 1, wherein, The etching stop layer comprises silicon dioxide, aluminum oxide or silicon oxynitride.
9. The vertical cavity surface emitting laser of claim 1, wherein, The second passivation layer comprises silicon nitride.
10. The vertical cavity surface emitting laser of claim 1, wherein, The vertical cavity surface emitting laser further comprises a first ohmic metal, which is located on the side of the second reflective layer away from the first electrode layer and is disposed in the same layer as the first passivation structure.