Vertical Cavity Surface Emitting Laser and Method for Preparing the Same

Abstract

The present application provides a vertical cavity surface emitting laser and a preparation method thereof, relating to the technical field of vertical cavity surface emitting lasers. The method includes providing an epitaxial structure, which includes a substrate, an N-type contact layer, an N-type reflective layer, a quantum well layer, and a P-type reflective layer stacked in sequence; forming a P-pole metal electrode on the P-type reflective layer, and forming a first anti-reflection film layer on the P-pole metal electrode to cover the P-type reflective layer; etching a trench from the first anti-reflection film layer to the N-type contact layer; forming an oxidation structure by extending into the P-type reflective layer from the sidewall of the trench, and forming a second anti-reflection film layer on the first anti-reflection film layer to cover the trench; etching the second anti-reflection film layer from the trench to expose the N-type contact layer, and forming an N-pole metal electrode on the exposed N-type contact layer; etching the first anti-reflection film layer and the second anti-reflection film layer to expose the P-pole metal electrode; leading out a P electrode through the P-pole metal electrode, and leading out an N electrode through the N-pole metal electrode.

Description

Technical Field

[0001] This application relates to the technical field of vertical cavity surface emitting lasers, and particularly to a vertical cavity surface emitting laser and a method for manufacturing the same. Background Art

[0002] When manufacturing an existing vertical cavity surface emitting laser, when forming an oxide layer in a P-type reflective layer, a PI (polymer material) platform groove is etched on the device to the P-type reflective layer, and the oxide layer is formed in the P-type reflective layer by the PI platform groove. After formation, the PI platform groove is filled completely to obtain a vertically cavity surface emitting laser device with a complete structure. Such a manufacturing process is cumbersome, and filling the PI platform groove after etching it will increase the parasitic capacitance effect, thereby affecting the characteristics of the vertical cavity surface emitting laser device. Summary of the Invention

[0003] The purpose of the embodiments of this application is to provide a vertical cavity surface emitting laser and a method for manufacturing the same, which directly form an oxide layer using the groove of the N-pole metal electrode, reduce the process flow, reduce the parasitic capacitance effect, and improve the device characteristics.

[0004] On the one hand, an embodiment of this application provides a method for manufacturing a vertical cavity surface emitting laser, including providing an epitaxial structure, where the epitaxial structure includes a substrate, an N-type contact layer, an N-type reflective layer, a quantum well layer, and a P-type reflective layer stacked in sequence; forming a P-pole metal electrode on the P-type reflective layer, and forming a first anti-reflection film layer on the P-pole metal electrode to cover the P-type reflective layer; etching a groove from the first anti-reflection film layer to the N-type contact layer; extending an oxidation structure into the P-type reflective layer through the sidewall of the groove, and forming a second anti-reflection film layer on the first anti-reflection film layer to cover the groove; etching the second anti-reflection film layer from the groove to expose the N-type contact layer, and forming an N-pole metal electrode on the exposed N-type contact layer; etching the first anti-reflection film layer and the second anti-reflection film layer to expose the P-pole metal electrode; connecting a P electrode through the P-pole metal electrode, and connecting an N electrode through the N-pole metal electrode.

[0005] Optionally, the forming a P-pole metal electrode on the P-type reflective layer and forming a first anti-reflection film layer on the P-pole metal electrode to cover the P-type reflective layer includes: evaporating and depositing the P-pole metal electrode on the P-type reflective layer.

[0006] Optionally, the etching a groove from the first anti-reflection film layer to the N-type contact layer includes: etching the groove, and the groove forms an inverted trapezoidal groove.

[0007] Optionally, etching the trench from the first anti-reflection film layer to the N-type contact layer includes: etching the trench such that an angle is formed between the trench wall and the horizontal plane, and the angle is between 60° and 80°. Optionally, extending an oxidation structure into the P-type reflective layer through the sidewall of the trench and forming a second anti-reflection film layer on the first anti-reflection film layer to cover the trench includes: forming the oxidation structure through a wet oxidation process.

[0008] On the other hand, an embodiment of the present application provides a vertical cavity surface emitting laser, prepared by using the preparation method of the vertical cavity surface emitting laser described above, including an epitaxial structure, a P-pole metal electrode, a first anti-reflection film layer, and a second anti-reflection film layer stacked in sequence. The P-pole metal electrode is located on the P-type reflective layer of the epitaxial structure; it further includes a trench extending from the second anti-reflection film layer to the N-type contact layer of the epitaxial structure. An N-pole metal electrode is disposed on the N-type contact layer at the bottom of the trench. An oxidation structure is further disposed in the P-type reflective layer of the epitaxial structure, and the oxidation structure extends into the P-type reflective layer from the sidewall of the trench.

[0009] Optionally, the epitaxial structure includes a substrate, the N-type contact layer, an N-type reflective layer, a quantum well layer, and the P-type reflective layer stacked in sequence, and the P-pole metal electrode is disposed on the P-type reflective layer.

[0010] Optionally, the trench is a trapezoidal trench with an angle between the trench wall and the horizontal plane, and the angle is between 60° and 80°.

[0011] Optionally, the number of the trenches is multiple, and the multiple trenches are evenly distributed on the epitaxial structure, and a gap aperture is formed between the oxidation structures formed by the multiple trenches.

[0012] Optionally, both the first anti-reflection film layer and the second anti-reflection film layer include silicon oxynitride or silicon nitride.

[0013] The vertical cavity surface emitting laser and its preparation method provided by the embodiments of the present application, compared with the prior art, directly form an oxidation structure through the trench, and at the same time form an N-pole metal electrode by using the trench, without using a PI filling platform to etch the trench, reducing the process flow; moreover, after not using the PI filling platform to etch the trench, the parasitic capacitance effect can be reduced, and the device characteristics can be improved; on the other hand, since the oxidation structure can be formed by using the trench, the structure of the PI filling platform for etching the trench is omitted, reducing the size of the device and increasing the production capacity. In addition, compared with the three anti-reflection film layers in the prior art, the present application can achieve the required functions by using two anti-reflection film layers, reducing the coating process of one anti-reflection film layer. Description of the Drawings

[0014] To more clearly illustrate the technical solutions of the embodiments of the present application, the accompanying drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following accompanying drawings only show some embodiments of the present application and should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related accompanying drawings can also be obtained based on these drawings.

[0015] Figure 1 It is one of the process diagrams of the method for fabricating a vertical cavity surface emitting laser provided in this embodiment;

[0016] Figure 2 It is the second of the process diagrams of the method for fabricating a vertical cavity surface emitting laser provided in this embodiment;

[0017] Figure 3 It is the third of the process diagrams of the method for fabricating a vertical cavity surface emitting laser provided in this embodiment;

[0018] Figure 4 It is the fourth of the process diagrams of the method for fabricating a vertical cavity surface emitting laser provided in this embodiment;

[0019] Figure 5 It is the fifth of the process diagrams of the method for fabricating a vertical cavity surface emitting laser provided in this embodiment;

[0020] Figure 6 It is the sixth of the process diagrams of the method for fabricating a vertical cavity surface emitting laser provided in this embodiment;

[0021] Figure 7 It is the first of the structural diagrams of the method for fabricating a vertical cavity surface emitting laser provided in this embodiment;

[0022] Figure 8 It is the second of the structural diagrams of the method for fabricating a vertical cavity surface emitting laser provided in this embodiment.

[0023] Icon: 101 - Substrate; 102 - N-type contact layer; 103 - N-type reflective layer; 104 - Quantum well layer; 105 - P-type reflective layer; 105a - Oxidation structure; 105b - Gap aperture; 106 - P-pole metal electrode; 106a - P electrode; 107 - First anti-reflection film layer; 107a - Groove; 108 - Second anti-reflection film layer; 109 - N-pole metal electrode; 109a - N electrode; a - Included angle. Detailed implementation manners

[0024] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application.

[0025] In the description of the present application, it should be noted that the orientation or positional relationship indicated by terms such as "inner" and "outer" is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of this application is usually placed during use. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application. In addition, terms such as "first" and "second" are only used for distinguishing descriptions and cannot be construed as indicating or implying relative importance.

[0026] It should also be noted that unless otherwise clearly specified and defined, the terms "arrangement" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, and can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0027] When preparing the existing vertical cavity surface emitting laser, when forming an oxide layer in the P-type reflective layer 105, two PI (polymer material) platform grooves are etched on the device to the P-type reflective layer 105, and the oxide layer is formed in the P-type reflective layer 105 by the two PI platform grooves respectively. After formation, the two PI platform grooves are filled completely, so as to prepare the vertical cavity surface emitting laser device. When preparing the device by the above method, the preparation process is cumbersome. It is necessary to etch the PI platform grooves and then fill them, which will increase the parasitic capacitance effect and affect the characteristics of the vertical cavity surface emitting laser device. Moreover, three anti-reflection layer coatings need to be formed on the electrode to achieve the required functions, which increases the process flow and limits the product size, production capacity and cost.

[0028] In view of this, the embodiments of the present application provide a vertical cavity surface emitting laser and a preparation method thereof. By directly forming an oxide layer using the groove 107a of the N-pole metal electrode 109, the process flow of etching the PI platform grooves is reduced, and there is no need to refill the PI platform grooves, thereby effectively reducing the parasitic capacitance effect and improving the characteristics of the vertical cavity surface emitting laser device.

[0029] Specifically, the embodiments of the present application provide a preparation method of a vertical cavity surface emitting laser, and the method includes:

[0030] Please refer to Figure 1 as shown, S100: Provide an epitaxial structure, and the epitaxial structure includes a substrate 101, an N-type contact layer 102, an N-type reflective layer 103, a quantum well layer 104, and a P-type reflective layer 105 stacked in sequence.

[0031] An N-type contact layer 102, an N-type reflective layer 103, a quantum well layer 104, and a P-type reflective layer 105 are sequentially formed on a substrate 101 of an epitaxial structure. Among them, the substrate 101 can be a gallium arsenide substrate 101.

[0032] As Figure 2 shown, S110: A P-pole metal electrode 106 is formed on the P-type reflective layer 105, and a first anti-reflection film layer 107 is formed on the P-pole metal electrode 106 to cover the P-type reflective layer 105.

[0033] The P-pole metal electrode 106 partially covers the P-type reflective layer 105, and the first anti-reflection film layer 107 completely covers the P-type reflective layer 105 and the P-pole metal electrode 106.

[0034] In addition, the P-pole metal electrode 106 is formed on the P-type reflective layer 105 by evaporation coating. Compared with the existing cumbersome electroplating gold process, the evaporation coating method is simple to operate and easy to implement, and an E-gun machine can be directly used to evaporate the metal electrode.

[0035] Furthermore, the first anti-reflection film layer is prepared from silicon oxynitride (SiO x N y ) or silicon nitride (SiN) materials.

[0036] As Figure 3 shown, S120: A groove 107a is etched from the first anti-reflection film layer 107 to the N-type contact layer 102.

[0037] The groove 107a is etched downward from the first anti-reflection film layer 107, and the bottom of the groove 107a reaches the N-type contact layer 102. The groove 107a is an inverted trapezoidal groove 107a, and the inverted trapezoidal groove 107a can be directly etched in one step. Compared with the stepped groove 107a, one etching process of the step platform can be reduced, and the preparation efficiency can be improved. The groove 107a in the prior art is a stepped groove 107a, and there is a step surface and a bottom surface in the existing groove 107a. In this way, when etching, it is necessary to etch twice to form the stepped groove 107a. When the inverted trapezoidal groove 107a is used in this application, it only needs to be etched to the bottom of the groove 107a once, reducing the etching process.

[0038] In addition, there is an angle a between the groove wall of the groove 107a and the horizontal plane, and the angle a is between 60° and 80°. Such a setting is beneficial to subsequent metal climbing. Further, the angle a is preferably between 75° and 80°.

[0039] As Figure 4 shown, S130: An oxidation structure 105a is extended into the P-type reflective layer 105 through the side wall of the groove 107a, and a second anti-reflection film layer 108 is formed on the first anti-reflection film layer 107 to cover the groove 107a.

[0040] By forming the oxidation structure 105a, the current density can be reduced and the light-emitting effect can be improved. The oxidation structure 105a is formed by a wet oxidation process, specifically by diffusing into the P-type reflective layer 105 from the sidewalls of the trench 107a to form the oxidation structure 105a. The oxidation structure 105a formed by the wet oxidation method has a fast growth rate.

[0041] The second anti-reflection film layer 108 and the first anti-reflection film layer 107 are made of the same material, both being silicon oxynitride (SiO x N y N) or silicon nitride (SiN) materials.

[0042] As Figure 5 shown, S140: Etch the second anti-reflection film layer 108 from the trench 107a to expose the N-type contact layer 102, and form the N-pole metal electrode 109 on the exposed N-type contact layer 102.

[0043] Etch the second anti-reflection film layer 108 at the bottom position of the trench 107a to expose the N-type contact layer 102 in the bottom area of the trench 107a, and then form the N-pole metal electrode 109 on the exposed N-type contact layer 102 to facilitate the connection of the N-pole.

[0044] As Figure 6 shown, S150: Etch the first anti-reflection film layer 107 and the second anti-reflection film layer 108 to expose the P-pole metal electrode 106.

[0045] Etch the first anti-reflection film layer 107 and the second anti-reflection film layer 108 at the position of the P-pole metal electrode 106 until the P-pole metal electrode 106 is exposed to facilitate the connection of the P-pole.

[0046] As Figure 7 shown, S160: Adopt the method of metal evaporation to connect out the P electrode 106a from the P-pole metal electrode 106 and connect out the N electrode 109a from the N-pole metal electrode 109. Exemplarily, the distribution of its P-pole and N-pole is as Figure 8 shown. The P electrode 106a is circumferentially arranged, which can effectively increase the area of the P electrode 106a, reduce the contact resistance, reduce the current density, and improve the energy conversion efficiency; the N electrode 109a is correspondingly arranged, which will not be elaborated here.

[0047] In summary, compared with the prior art, the method for preparing a vertical cavity surface emitting laser provided by the embodiments of the present application directly forms the oxidation structure 105a through the trench 107a, and at the same time forms the N-pole metal electrode 109 by using the trench 107a, without using PI to fill the trench 107a of the platform etching, reducing the process flow; moreover, after not using PI to fill the trench 107a of the platform etching, the parasitic capacitance effect can be reduced, and the device characteristics can be improved; on the other hand, since the oxidation structure 105a can be formed by using the trench 107a, the structure of using PI to fill the trench 107a of the platform etching is omitted, the size of the device is reduced, and the production capacity is increased. In addition, compared with the three-layer antireflection film layer in the prior art, the present application can achieve the required functions by using two-layer antireflection film layers, reducing the coating process of one antireflection film layer.

[0048] In addition, the method for preparing a vertical cavity surface emitting laser provided by the embodiments of the present application is provided with two-layer antireflection film layers, namely a first antireflection film layer 107 and a second antireflection film layer 108, and the required functions can be achieved by using two-layer antireflection film layers; the prior art needs to use three-layer antireflection film layers. In comparison, the present application reduces the plating of one antireflection film layer and reduces the process flow.

[0049] On the other hand, as Figure 7 and Figure 8 shown, the embodiments of the present application also disclose a vertical cavity surface emitting laser prepared by using the above method for preparing a vertical cavity surface emitting laser, which specifically includes an epitaxial structure, a P-pole metal electrode 106, a first antireflection film layer 107, and a second antireflection film layer 108 that are sequentially stacked. The P-pole metal electrode 106 is located on the P-type reflection layer 105 of the epitaxial structure; it also includes a trench 107a extending from the second antireflection film layer 108 to the N-type contact layer 102 of the epitaxial structure. An N-pole metal electrode 109 is provided on the N-type contact layer 102 at the bottom of the trench 107a. An oxidation structure 105a is also provided in the P-type reflection layer 105 of the epitaxial structure, and the oxidation structure 105a extends from the side wall of the trench 107a into the P-type reflection layer 105.

[0050] The epitaxial structure of the vertical cavity surface emitting laser includes a substrate 101, an N-type contact layer 102, an N-type reflection layer 103, a quantum well layer 104, and a P-type reflection layer 105. The P-pole metal electrode 106 is provided on the P-type reflection layer 105. The substrate 101 is a gallium arsenide substrate 101. Both the first antireflection film layer 107 and the second antireflection film layer 108 can be prepared by using silicon oxynitride or silicon nitride. The antireflection film layer prepared by using silicon oxynitride or silicon nitride has a good effect, can reduce the reflectivity of light, and thus reduce the light loss.

[0051] Furthermore, the groove 107a is an inverted trapezoidal groove 107a, and there is an included angle a between the groove wall of the groove 107a and the horizontal plane, and the included angle a is between 60° and 80°, which is beneficial to subsequent metal creepage. When the included angle a is between 75° and 80°, the creepage effect is better.

[0052] In an embodiment of the present application, the appearance of the formed vertical cavity surface emitting laser is as Figure 8 shown as a rectangle. The number of grooves 107a in the present application is multiple, and the multiple grooves 107a are evenly distributed on the epitaxial structure. An N-pole metal electrode 109 is formed in each groove 107a, and the distribution forms of the multiple N-pole metal electrodes 109 and the P-pole metal electrode 106 are as Figure 8 shown.

[0053] Exemplarily, taking three grooves 107a in the present application as an example, a gap aperture 105b is formed between the oxidation structures 105a formed by the three grooves 107a. Each groove 107a can form its own oxidation structure 105a through a wet oxidation process. In this way, the three grooves 107a correspondingly form three oxidation structures 105a at the same level, and the three oxidation structures 105a are not continuous with each other to form a gap aperture 105b. The P-pole metal electrode 106 injects current through the gap aperture 105b, and the gap aperture 105b is also used for laser light output. Figure 7 In the arrow marked O direction in is the laser light output direction, and the arrow marked I direction is the current injection direction.

[0054] Of course, the appearance of the above-mentioned vertical cavity surface emitting laser, as well as the number of grooves 107a and the distribution forms of the N-pole metal electrode 109 and the P-pole metal electrode 106 are only an example of the present application, and there can be other setting forms, which are not limited to the above.

[0055] This vertical cavity surface emitting laser includes the same structure and beneficial effects as those of the preparation method of the vertical cavity surface emitting laser in the foregoing embodiment. The structure and beneficial effects of the preparation method of the vertical cavity surface emitting laser have been described in detail in the foregoing embodiment, and will not be repeated here.

[0056] The above description is only for the embodiments of the present application and is not intended to limit the protection scope of the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for fabricating a vertical cavity surface emitting laser, characterized in that, it includes: providing an epitaxial structure, which includes a substrate, an N-type contact layer, an N-type reflective layer, a quantum well layer, and a P-type reflective layer stacked in sequence; forming a P-pole metal electrode on the P-type reflective layer, and forming a first anti-reflection film layer on the P-pole metal electrode to cover the P-type reflective layer; etching a trench from the first anti-reflection film layer to the N-type contact layer; extending an oxidation structure from the sidewall of the trench into the P-type reflective layer, and forming a second anti-reflection film layer on the first anti-reflection film layer to cover the trench; wherein, the number of the trenches is multiple, the multiple trenches are evenly distributed on the epitaxial structure, and a gap aperture is formed between the oxidation structures formed by the multiple trenches; etching the second anti-reflection film layer by the trench to expose the N-type contact layer, and forming an N-pole metal electrode on the exposed N-type contact layer; etching the first anti-reflection film layer and the second anti-reflection film layer to expose the P-pole metal electrode; leading out a P electrode through the P-pole metal electrode, and leading out an N electrode through the N-pole metal electrode.

2. The method for fabricating a vertical cavity surface emitting laser according to claim 1, characterized in that, the forming a P-pole metal electrode on the P-type reflective layer, and forming a first anti-reflection film layer on the P-pole metal electrode to cover the P-type reflective layer includes: evaporating and depositing to form the P-pole metal electrode on the P-type reflective layer.

3. The method for fabricating a vertical cavity surface emitting laser according to claim 1, characterized in that, the etching a trench from the first anti-reflection film layer to the N-type contact layer includes: etching the trench, and the trench forms an inverted trapezoidal trench.

4. The method for fabricating a vertical cavity surface emitting laser according to claim 3, characterized in that, the etching a trench from the first anti-reflection film layer to the N-type contact layer includes: etching the trench so that an included angle between the trench wall and the horizontal plane is formed, and the included angle is between 60° and 80°.

5. The method for fabricating a vertical cavity surface emitting laser according to claim 1, characterized in that, the extending an oxidation structure from the sidewall of the trench into the P-type reflective layer, and forming a second anti-reflection film layer on the first anti-reflection film layer to cover the trench includes: forming the oxidation structure by a wet oxidation process.

6. A vertical cavity surface emitting laser fabricated by using the method for fabricating a vertical cavity surface emitting laser according to any one of claims 1-5, characterized in that, it includes an epitaxial structure, a P-pole metal electrode, a first anti-reflection film layer, and a second anti-reflection film layer stacked in sequence, and the P-pole metal electrode is located on the P-type reflective layer of the epitaxial structure; it further includes a trench extending from the second anti-reflection film layer to the N-type contact layer of the epitaxial structure, an N-pole metal electrode is arranged on the N-type contact layer at the bottom of the trench, and an oxidation structure is further arranged in the P-type reflective layer of the epitaxial structure, and the oxidation structure extends from the sidewall of the trench into the P-type reflective layer.

7. The vertical cavity surface emitting laser according to claim 6, wherein, the epitaxial structure includes a substrate, the N-type contact layer, an N-type reflective layer, a quantum well layer, and the P-type reflective layer which are sequentially stacked, and the P-pole metal electrode is disposed on the P-type reflective layer.

8. The vertical cavity surface emitting laser according to claim 6, wherein, the groove is an inverted trapezoidal groove, and an included angle exists between the groove wall of the groove and the horizontal plane, and the included angle is between 60° and 80°.

9. The vertical cavity surface emitting laser according to claim 6, wherein, both the first antireflection film layer and the second antireflection film layer include silicon oxynitride or silicon nitride.

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