CN116914558B

CN116914558B - Semiconductor laser contact electrode and preparation method thereof

Info

Publication number: CN116914558B
Application number: CN202311176626.3A
Authority: CN
Inventors: 杨文帆; 王俊; 李泉灵; 郭路安; 李波; 闵大勇; 贺章
Original assignee: Suzhou Everbright Photonics Co Ltd; Suzhou Everbright Semiconductor Laser Innovation Research Institute Co Ltd
Current assignee: Suzhou Everbright Photonics Co Ltd; Suzhou Everbright Semiconductor Laser Innovation Research Institute Co Ltd
Priority date: 2023-09-13
Filing date: 2023-09-13
Publication date: 2023-12-19
Anticipated expiration: 2043-09-13
Also published as: CN116914558A

Abstract

The invention relates to the technical field of semiconductors, and discloses a semiconductor laser contact electrode and a preparation method thereof, wherein the semiconductor laser contact electrode comprises the following components: a substrate layer; a contact layer located on one side surface of the substrate layer; the diffusion barrier layer is positioned on one side surface of the contact layer, which is away from the substrate layer; the upper cover layer is positioned on one side surface of the diffusion barrier layer, which is away from the substrate layer; wherein the material of the diffusion barrier layer comprises a compound formed by bonding metal and a first element, and the component content of the first element in the diffusion barrier layer gradually increases from the contact layer to the upper cover layer; alternatively, the material of the diffusion barrier layer includes a solid solution formed of a bonding metal and a second element, and the content of the second element in the diffusion barrier layer gradually increases from the contact layer to the capping layer. The semiconductor laser contact electrode provided by the invention has low resistance while meeting high temperature resistance because no heterogeneous interface is formed in the diffusion barrier layer.

Description

Semiconductor laser contact electrode and preparation method thereof

Technical Field

The invention relates to the technical field of semiconductors, in particular to a semiconductor laser contact electrode and a preparation method thereof.

Background

Semiconductor lasers, also known as laser diodes, are lasers that use semiconductor materials as the working substance. Compared with other types of lasers, semiconductor lasers have the advantages of small size, high electro-optical conversion efficiency, wide wavelength selection, long service life and low cost, and due to the advantages, semiconductor diode lasers are widely applied in laser communication, optical storage, optical gyro, laser printing, ranging, radar and the like.

As a power device of high current density, a semiconductor laser is very sensitive to ohmic contact characteristics. In general, when a laser fails, it is largely due to contact electrode problems. However, for high power semiconductor lasers, the fabrication process mostly involves a high temperature environment. Under the high-temperature environment, the diffusion rate of metal atoms in the contact electrode is obviously increased, and film layers in the contact electrode are mutually mixed, so that the whole device is invalid.

In order to improve the high temperature resistance of the contact electrode, most of the prior art schemes are to introduce a lamination of multiple metals to construct a diffusion barrier layer. However, as the number of stacks increases, the number of heterogeneous interfaces in the diffusion barrier increases. Accordingly, the scattering of carriers by the entire diffusion barrier layer is enhanced, and the resistance of the contact electrode is increased, resulting in the performance degradation of the semiconductor laser, which needs to be solved.

Disclosure of Invention

Therefore, the invention aims to solve the technical problem that the contact electrode of the semiconductor laser in the prior art cannot meet the high temperature resistance and simultaneously cannot meet the low resistance, thereby providing the contact electrode of the semiconductor laser and the preparation method thereof.

The invention provides a semiconductor laser contact electrode, comprising: a substrate layer; a contact layer located on one side surface of the substrate layer; the diffusion barrier layer is positioned on one side surface of the contact layer, which is away from the substrate layer; the upper cover layer is positioned on one side surface of the diffusion barrier layer, which is away from the substrate layer; wherein the material of the diffusion barrier layer comprises a compound formed by bonding metal and a first element, and the component content of the first element in the diffusion barrier layer gradually increases from the contact layer to the upper cover layer; alternatively, the material of the diffusion barrier layer includes a solid solution formed of a bonding metal and a second element, and the content of the second element in the diffusion barrier layer gradually increases from the contact layer to the capping layer.

Optionally, the component content of the first element in the diffusion barrier increases by a gradient of less than 0.1at.% per nm and the component content of the second element in the diffusion barrier increases by a gradient of less than 0.1at.% per nm in a direction from the contact layer to the capping layer.

Optionally, the lattice parameter of the diffusion barrier layer increases gradually from the contact layer to the capping layer, the gradient of the increase in lattice parameter of the diffusion barrier layer being less than 0.1%/nm.

Optionally, the diffusion barrier layer includes a first sub diffusion barrier region to an nth sub diffusion barrier region in a direction from the contact layer to the capping layer, N being an integer equal to or greater than 2; the first element in the first sub-diffusion barrier region has a composition content of 3at.% to 5at.%, and the first element in the nth sub-diffusion barrier region has a composition content of 16at.% to 20at.%; the composition content of the second element in the first sub-diffusion barrier region is 3at.% to 5at.%, and the composition content of the second element in the nth sub-diffusion barrier region is 6at.% to 10at.%.

Optionally, the bonding metal comprises: titanium or nickel, the first element comprising nitrogen and the second element comprising any one of tungsten, niobium or chromium.

Optionally, the compound formed by the bonding metal and the first element has a melting point of 1500 ℃ to 2500 ℃; the melting point of the solid solution formed by the binding metal and the second element is 1500-2000 ℃.

Optionally, the diffusion barrier layer has a thickness of 100nm to 500nm.

Optionally, the contact layer includes a first sub-contact layer, a second sub-contact layer, and a third sub-contact layer sequentially stacked from the substrate layer to the diffusion barrier layer.

Optionally, the material of the first sub-contact layer includes any one of nickel, platinum or palladium, the material of the second sub-contact layer includes germanium, and the material of the third sub-contact layer includes gold.

Optionally, the ratio of the thickness of the first sub-contact layer to the thickness of the second sub-contact layer is 1:1.8-1:2.2, the ratio of the thickness of the first sub-contact layer to the thickness of the third sub-contact layer is 1:1.8-1:2.2.

optionally, the first sub-contact layer has a thickness of 38nm to 42nm, the second sub-contact layer has a thickness of 78nm to 82nm, and the third sub-contact layer has a thickness of 78nm to 82nm.

The invention also provides a preparation method of the semiconductor laser contact electrode, which comprises the following steps: providing a substrate layer; forming a contact layer on one side surface of the substrate layer; forming a diffusion barrier layer on the surface of one side of the contact layer, which is away from the substrate layer; forming an upper cover layer on the surface of one side of the diffusion barrier layer, which is away from the substrate layer; wherein the material of the diffusion barrier layer comprises a compound formed by bonding metal and a first element, and the component content of the first element in the diffusion barrier layer gradually increases from the contact layer to the upper cover layer; alternatively, the material of the diffusion barrier layer includes a solid solution formed of a bonding metal and a second element, and the content of the second element in the diffusion barrier layer gradually increases from the contact layer toward the capping layer.

Optionally, the step of forming a diffusion barrier layer on a surface of the contact layer facing away from the substrate layer includes: sputtering bonding metal on the surface of one side of the contact layer, which is far away from the substrate layer, by adopting a magnetron sputtering process, introducing gas of a first element in the process of sputtering the bonding metal, wherein the power of the sputtering bonding metal is fixed and the flow rate of the gas of the first element is gradually increased in the process of forming the diffusion barrier layer.

Optionally, during the forming of the diffusion barrier layer, the initial flow rate of the gas of the first element is 1.8sccm to 2.2sccm, and the flow rate of the gas of the first element is increased at a rate of 0.48sccm/min to 0.52sccm/min.

Optionally, the step of forming a diffusion barrier layer on a surface of the contact layer facing away from the substrate layer includes: and sputtering a target material of bonding metal and a second element on the surface of one side of the contact layer, which is away from the substrate layer, by adopting a magnetron sputtering process, wherein the power of the target material of the sputtering bonding metal is fixed and the power of the target material of the sputtering second element is gradually increased in the process of forming the diffusion barrier layer.

Optionally, during the formation of the diffusion barrier layer, the initial power of the sputtered second element target is 0W to 0.1W, and the rate of increase of the power of the sputtered atoms of the second element is 4.8W/min to 5.2W/min.

Optionally, the step of forming a contact layer on a side surface of the substrate layer includes: sequentially forming a first sub-contact layer, a second sub-contact layer and a third sub-contact layer which are stacked on one side surface of the substrate layer; the process for forming the contact layer comprises the following steps: electron beam evaporation process.

Optionally, annealing the contact layer is further included before forming the diffusion barrier layer.

Optionally, the contact layer is annealed at a temperature of 360-380 ℃ for 18-22 minutes.

Optionally, the process of forming the capping layer on a surface of the diffusion barrier layer on a side facing away from the substrate layer includes a magnetron sputtering process.

The technical scheme of the invention has the following beneficial effects:

in the technical scheme of the invention, the semiconductor laser contact electrode is arranged on one side surface of the contact layer, which is away from the substrate layer, of the diffusion barrier layer, and the upper cover layer is arranged on one side surface of the diffusion barrier layer, which is away from the substrate layer; the material of the diffusion barrier layer comprises a compound formed by bonding metal and a first element, and the component content of the first element in the diffusion barrier layer gradually increases from the contact layer to the upper cover layer; alternatively, the material of the diffusion barrier layer includes a solid solution formed of a bonding metal and a second element, and the content of the second element in the diffusion barrier layer gradually increases from the contact layer to the capping layer. On the one hand, the component content of the first element in the diffusion barrier layer is gradually increased in the direction from the contact layer to the upper cover layer, or the component content of the second element in the diffusion barrier layer is gradually increased, so that the component content of the bonding metal in the diffusion barrier layer connected with the contact layer is higher, the diffusion barrier layer connected with the contact layer shows the adhesiveness characteristic of the bonding metal, and the bonding of the diffusion barrier layer and the contact layer can be promoted; the diffusion barrier layer connected with the upper cover layer has higher component content of the first element or the second element, so that the diffusion barrier layer connected with the upper cover layer shows high heat stability of refractory compounds or solid solutions, atoms in the partial region are difficult to diffuse with other metal atoms at high temperature, therefore, the diffusion of the upper cover layer and the metal atoms in the contact layer can be prevented, the high temperature resistance of the contact electrode of the semiconductor laser is improved through effective inhibition of the diffusion of the metal atoms, the alloying of the contact electrode of the semiconductor laser due to high temperature in the preparation process of the semiconductor laser is avoided, and the production efficiency and yield of the semiconductor laser are improved; on the other hand, since the diffusion barrier layer at the portion connected to the contact layer and the diffusion barrier layer at the portion connected to the upper cap layer have the same crystal structure, no hetero interface is generated in the diffusion barrier layer, and the entire diffusion barrier layer has a single-layer rather than a multi-layer structure. Therefore, when current is transmitted inside the semiconductor laser contact electrode, electrons can smoothly pass through the diffusion barrier layer, and the diffusion barrier layer does not cause a large increase in the resistance of the semiconductor laser contact electrode. In conclusion, the contact electrode of the semiconductor laser meets the high temperature resistance and has low resistance.

Further, the gradient of the increase in the component content of the first element in the diffusion barrier layer is less than 0.1at.% per nm and the gradient of the increase in the component content of the second element in the diffusion barrier layer is less than 0.1at.% per nm in the direction from the contact layer to the capping layer. Under the gradient of increasing the component content of the first element and the second element in the current diffusion barrier layer, a heterogeneous interface is not generated in the diffusion barrier layer, so that electrons can smoothly pass through the diffusion barrier layer when current is transmitted inside the semiconductor laser contact electrode, and therefore, the diffusion barrier layer does not cause the great increase of the resistance of the semiconductor laser contact electrode, and the resistance of the semiconductor laser contact electrode is reduced.

Further, the lattice parameter of the diffusion barrier layer gradually increases from the contact layer to the capping layer, and the gradient of the increase of the lattice parameter of the diffusion barrier layer is less than 0.1%/nm. The maximum proportion of the increase of the lattice parameter in the whole diffusion barrier layer is smaller than 10%, a heterogeneous interface can be prevented from being generated in the diffusion barrier layer, so that electrons can smoothly pass through the diffusion barrier layer when current is transmitted inside the contact electrode of the semiconductor laser, the diffusion barrier layer cannot cause the resistance of the contact electrode of the semiconductor laser to be greatly increased, and the resistance of the contact electrode of the semiconductor laser is reduced.

Further, the diffusion barrier layer comprises a first sub diffusion barrier region to an N sub diffusion barrier region from the contact layer to the upper cover layer, wherein N is an integer equal to or more than 2; the first element in the first sub-diffusion barrier region has a composition content of 3at.% to 5at.%, and the first element in the nth sub-diffusion barrier region has a composition content of 16at.% to 20at.%; the composition content of the second element in the first sub-diffusion barrier region is 3at.% to 5at.%, and the composition content of the second element in the nth sub-diffusion barrier region is 6at.% to 10at.%. The component content of the first element in the first sub-diffusion barrier region or the component content of the second element in the first sub-diffusion barrier region is low, so that the first sub-diffusion barrier region connected with the contact layer is favorable for showing the adhesion property of bonding metal, and the bonding of the diffusion barrier layer and the contact layer can be promoted; the N-th sub-diffusion barrier region has a high component content of the first element or a high component content of the second element, which is advantageous in that the N-th sub-diffusion barrier region connected to the upper cap layer exhibits high thermal stability characteristics of a compound or solid solution, and atoms in the N-th sub-diffusion barrier region are difficult to interdiffuse with other metal atoms at high temperature, thereby being capable of blocking diffusion of the metal atoms in the upper cap layer and the contact layer, and thus being capable of avoiding failure of the semiconductor laser.

Further, the melting point of the compound formed by the bonding metal and the first element is 1500-2500 ℃; the melting point of the solid solution formed by the bonding metal and the second element is 1500-2000 ℃, the melting point of the compound formed by the bonding metal and the first element is high, the melting point of the solid solution formed by the bonding metal and the second element is high, the component content of the first element in the diffusion barrier layer is gradually increased or the component content of the second element in the diffusion barrier layer is gradually increased in the direction from the contact layer to the upper cover layer, so that the diffusion barrier layer connected with the upper cover layer shows the high heat stability characteristic of refractory compound or solid solution, atoms in the partial region are difficult to mutually diffuse with other metal atoms at high temperature, the diffusion of the upper cover layer and the metal atoms in the contact layer can be prevented, the high temperature resistance of the contact electrode of the semiconductor laser is improved through the effective inhibition of the diffusion of the metal atoms, the high temperature resistance of the contact electrode of the semiconductor laser is avoided, and the production efficiency and the yield of the semiconductor laser are improved.

Further, the thickness of the diffusion barrier layer is 100nm-500nm; the thickness of the diffusion barrier layer is within the range, so that the thickness of the whole structure of the contact electrode of the semiconductor laser is not increased, the diffusion barrier layer is beneficial to meeting the gradient of the increase of the component content of the first element or the second element so as to ensure the high temperature resistance, low resistance and low stress of the diffusion barrier layer, and the diffusion of metal atoms is also beneficial to being blocked.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic structural diagram of a contact electrode of a semiconductor laser according to an embodiment of the present invention;

FIG. 2 is a flow chart of a method for fabricating a contact electrode of a semiconductor laser according to an embodiment of the present invention;

FIG. 3 is a transmission electron microscope micro morphology of a diffusion barrier layer in a semiconductor laser contact electrode prepared by the preparation method of the semiconductor laser contact electrode provided in example 2;

FIG. 4 is an energy spectrum scanning result of a diffusion barrier layer in a semiconductor laser contact electrode prepared by the preparation method of the semiconductor laser contact electrode provided in example 2 along the arrow direction in FIG. 3;

fig. 5 is a morphology of a semiconductor laser contact electrode prepared by the preparation method of the semiconductor laser contact electrode provided in example 2 after annealing treatment for 30 minutes at 300 ℃;

Fig. 6 is a morphology of a semiconductor laser contact electrode prepared by the preparation method of a semiconductor laser contact electrode provided in example 2 after annealing treatment for 30 minutes at 450 ℃;

FIG. 7 is a graph showing the specific contact resistivity of the semiconductor laser contact electrode prepared by the method for preparing a semiconductor laser contact electrode provided in example 2;

fig. 8 is a morphology of a semiconductor laser contact electrode prepared by the preparation method of a semiconductor laser contact electrode provided in example 3 after annealing treatment for 30 minutes at 300 ℃;

fig. 9 is a morphology of a semiconductor laser contact electrode prepared by the preparation method of a semiconductor laser contact electrode provided in example 3 after annealing treatment for 30 minutes at 450 ℃;

fig. 10 is a specific contact resistivity of a semiconductor laser contact electrode prepared by the method for preparing a semiconductor laser contact electrode provided in example 3.

Detailed Description

The invention is described in further detail below with reference to the drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting thereof. It should be further noted that, for convenience of description, only some, but not all of the structures related to the present invention are shown in the drawings.

In the following description, descriptions of well-known structures and techniques are omitted so as not to unnecessarily obscure the concepts of the present invention. Various structural schematic diagrams according to embodiments of the present invention are shown in the accompanying drawings. The figures are not drawn to scale, wherein certain details are exaggerated for clarity of presentation and may have been omitted. The shapes of the various regions, layers and relative sizes, positional relationships between them shown in the drawings are merely exemplary, may in practice deviate due to manufacturing tolerances or technical limitations, and one skilled in the art may additionally design regions/layers having different shapes, sizes, relative positions as actually required. In the context of the present invention, when a layer/element is referred to as being "on" another layer/element, it can be directly on the other layer/element or intervening layers/elements may be present therebetween. In addition, if one layer/element is located "on" another layer/element in one orientation, that layer/element may be located "under" the other layer/element when the orientation is turned.

In addition, the technical features of the different embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.

Example 1

The present invention provides a semiconductor laser contact electrode, referring to fig. 1, comprising:

a substrate layer 1;

a contact layer 2 located on one side surface of the substrate layer 1;

a diffusion barrier layer 3 located on a side surface of the contact layer 2 facing away from the substrate layer 1;

an upper cover layer 4 on a surface of the diffusion barrier layer 3 facing away from the substrate layer 1;

wherein the material of the diffusion barrier layer 3 comprises a compound formed by bonding metal and a first element, and the component content of the first element in the diffusion barrier layer gradually increases from the contact layer to the upper cover layer;

alternatively, the material of the diffusion barrier layer 3 includes a solid solution formed of a bonding metal and a second element, and the content of the second element in the diffusion barrier layer gradually increases from the contact layer to the capping layer.

In the semiconductor laser contact electrode provided in this embodiment, on one hand, since the component content of the first element in the diffusion barrier layer 3 gradually increases in the direction from the contact layer 2 to the upper cover layer 4, or the component content of the second element in the diffusion barrier layer 3 gradually increases, the component content of the bonding metal in the diffusion barrier layer 3 connected to the contact layer 2 is higher, so that the diffusion barrier layer 3 connected to the contact layer 2 exhibits the adhesion property of the bonding metal, and the bonding between the diffusion barrier layer 3 and the contact layer 2 can be promoted; the diffusion barrier layer 3 connected with the upper cover layer 4 has higher component content of the first element or the second element, so that the diffusion barrier layer 3 connected with the upper cover layer 4 shows high heat stability characteristics of refractory compounds or solid solutions, atoms in the partial region are difficult to diffuse mutually with other metal atoms at high temperature, thereby being capable of preventing the upper cover layer 4 from diffusing with the metal atoms in the contact layer 2, improving the high temperature resistance of the contact electrode of the semiconductor laser through effective inhibition of the diffusion of the metal atoms, avoiding alloying of the contact electrode of the semiconductor laser due to high temperature in the preparation process of the semiconductor laser, and improving the production efficiency and yield of the semiconductor laser; on the other hand, since the diffusion barrier layer 3 at the portion connected to the contact layer 2 and the diffusion barrier layer 3 at the portion connected to the upper cap layer 4 have the same crystal structure, no hetero interface is generated in the diffusion barrier layer 3, and the entire diffusion barrier layer 3 has a single-layer rather than multi-layer structure. Therefore, when a current is transmitted inside the semiconductor laser contact electrode, electrons can smoothly pass through the diffusion barrier layer 3, and the diffusion barrier layer 3 does not cause a significant increase in the resistance of the semiconductor laser contact electrode. In conclusion, the contact electrode of the semiconductor laser meets the high temperature resistance and has low resistance.

In one embodiment, the material of the substrate layer 1 comprises gallium arsenide and the substrate layer is an N-type semiconductor.

In one embodiment, the gradient of the increase in the component content of the first element in the diffusion barrier layer 3 in the direction from the contact layer 2 to the upper cap layer 4 is less than 0.1at.% per nm, for example the gradient of the increase in the component content of the first element in the diffusion barrier layer is 0.01at.% per nm, 0.02at.% per nm, 0.05at.% per nm, 0.08at.% per nm or 0.09at.% per nm. The gradient of the increase of the component content of the first element in the diffusion barrier layer 3 is small, so that a heterogeneous interface can be prevented from being generated in the diffusion barrier layer 3, and electrons can smoothly pass through the diffusion barrier layer when current is transmitted inside the contact electrode of the semiconductor laser, and therefore, the diffusion barrier layer does not cause the great increase of the resistance of the contact electrode of the semiconductor laser, and the resistance of the contact electrode of the semiconductor laser is reduced.

In one embodiment, the gradient of the increase in the component content of the second element in the diffusion barrier layer 3 in the direction from the contact layer 2 to the upper cap layer 4 is less than 0.1at.% per nm, for example the gradient of the increase in the component content of the second element in the diffusion barrier layer is 0.01at.% per nm, 0.02at.% per nm, 0.05at.% per nm, 0.08at.% per nm or 0.09at.% per nm. The gradient of the increase of the component content of the second element in the diffusion barrier layer is small, so that a heterogeneous interface can be prevented from being generated in the diffusion barrier layer, electrons can smoothly pass through the diffusion barrier layer when current is transmitted inside the semiconductor laser contact electrode, and therefore the diffusion barrier layer does not cause the great increase of the resistance of the semiconductor laser contact electrode, and the resistance of the semiconductor laser contact electrode is reduced.

In one embodiment, the lattice parameter of the diffusion barrier layer 3 increases gradually from the contact layer 2 to the capping layer 4 with a gradient of less than 0.1%/nm, e.g. the lattice parameter of the diffusion barrier layer 3 increases with a gradient of 0.02%/nm, 0.03%/nm, 0.04%/nm, 0.05%/nm, 0.06%/nm, 0.08%/nm. The gradient of the increase of the lattice parameter of the diffusion barrier layer 3 is smaller, so that a heterogeneous interface can be prevented from being generated in the diffusion barrier layer, electrons can smoothly pass through the diffusion barrier layer when current is transmitted inside the contact electrode of the semiconductor laser, and therefore the diffusion barrier layer cannot cause the resistance of the contact electrode of the semiconductor laser to be greatly increased, and the resistance of the contact electrode of the semiconductor laser is reduced.

In one embodiment, the diffusion barrier layer 3 includes a first sub diffusion barrier region to an nth sub diffusion barrier region in a direction from the contact layer 2 to the capping layer 4, N being an integer equal to or greater than 2; n may take 10, 20, 30, 50, 100, and in other embodiments N may take other integers.

In one embodiment, the first element in the first sub-diffusion barrier region has a composition content of 3at.% to 5at.%, e.g., 3.5at.%, 4.5at.%, or 4.7at.%; the component content of the first element in the nth sub-diffusion barrier region is 16at.% to 20at.%, e.g., 16.5at.%, 17at.%, 17.5at.%, 18.5at.%, or 19.5at.%; the first sub-diffusion barrier region has a low component content of the first element, which is favorable for the first sub-diffusion barrier region connected with the contact layer to exhibit an adhesion property of bonding metal, can promote the bonding of the diffusion barrier layer and the contact layer, and the N sub-diffusion barrier region has a high component content of the first element or the second element, which is favorable for the N sub-diffusion barrier region connected with the upper cover layer to exhibit a high thermal stability property of a compound or solid solution, and the atoms in the N sub-diffusion barrier region are difficult to interdiffuse with other metal atoms at a high temperature, thereby being capable of blocking the diffusion of the metal atoms in the upper cover layer and the contact layer, so that the failure of the semiconductor laser can be avoided.

In one embodiment, the composition content of the second element in the first sub-diffusion barrier region is 3at.% to 5at.%, e.g., 3.5at.%, 4.5at.%, or 4.7at.%; the component content of the second element in the nth sub-diffusion barrier region is 6at.% to 10at.%, e.g., 6.5at.%, 7at.%, 7.5at.%, 8.5at.%, or 9.5at.%; the first sub-diffusion barrier region has a low component content of the first element, which is favorable for the first sub-diffusion barrier region connected with the contact layer to exhibit an adhesion property of bonding metal, can promote the bonding of the diffusion barrier layer and the contact layer, and the N sub-diffusion barrier region has a high component content of the first element or the second element, which is favorable for the N sub-diffusion barrier region connected with the upper cover layer to exhibit a high thermal stability property of a compound or solid solution, and the atoms in the N sub-diffusion barrier region are difficult to interdiffuse with other metal atoms at a high temperature, thereby being capable of blocking the diffusion of the metal atoms in the upper cover layer and the contact layer, so that the failure of the semiconductor laser can be avoided.

In one embodiment, the bonding metal comprises: titanium or nickel, the first element comprising nitrogen and the second element comprising any one of tungsten, niobium or chromium; in other embodiments, the bonding metal may also include other metals having adhesion properties.

In one embodiment, the compound formed by the bonding metal and the first element comprises titanium nitride, and the compound formed by the bonding metal and the first element has excellent thermal stability and electrical conductivity; the solid solution formed by the bonding metal and the second element comprises titanium tungsten alloy, nickel niobium alloy or titanium chromium alloy, and the solid solution formed by the bonding metal and the second element is a refractory metal solid solution.

In one embodiment, the compound formed by the bonding metal and the first element has a melting point of 1500 ℃ to 2500 ℃, such as 1600 ℃, 1800 ℃, 2000 ℃, or 2200 ℃; the melting point of the solid solution formed by the binding metal and the second element is 1500 ℃ to 2000 ℃, such as 1600 ℃, 1700 ℃, 1800 ℃ or 1900 ℃; the compound formed by the bonding metal and the first element has a high melting point, and the solid solution formed by the bonding metal and the second element has a high melting point, so that the component content of the first element in the diffusion barrier layer is gradually increased or the component content of the second element in the diffusion barrier layer is gradually increased in the direction from the contact layer to the upper cover layer, the diffusion barrier layer connected with the upper cover layer shows the high heat stability characteristic of refractory compound or solid solution, atoms in the partial region are difficult to mutually diffuse with other metal atoms at high temperature, the diffusion of the upper cover layer and the metal atoms in the contact layer can be prevented, the high temperature resistance of the contact electrode of the semiconductor laser is improved through the effective inhibition of the diffusion of the metal atoms, the alloying of the contact electrode of the semiconductor laser due to high temperature in the preparation process of the semiconductor laser is avoided, and the production efficiency and the yield of the semiconductor laser are improved.

In one embodiment, the diffusion barrier layer 3 has a thickness of 100nm-500nm, such as 150nm, 200nm, 250nm, 350nm or 450nm. The thickness of the diffusion barrier layer is within the range, so that the thickness of the whole structure of the contact electrode of the semiconductor laser is not increased, the diffusion barrier layer is beneficial to meeting the gradient of the increase of the component content of the first element or the second element, the high temperature resistance, the low resistance and the low stress of the diffusion barrier layer are ensured, and the mutual diffusion of the contact layer and the metal atoms of the upper cover layer is also beneficial to being blocked.

In one embodiment, the contact layer 2 includes a first sub-contact layer, a second sub-contact layer, and a third sub-contact layer stacked in this order from the substrate layer 1 to the diffusion barrier layer 3. The contact layer facilitates a good ohmic contact with the substrate layer.

In one embodiment, the material of the first sub-contact layer comprises any one of nickel, platinum or palladium, the material of the second sub-contact layer comprises germanium, and the material of the third sub-contact layer comprises gold. The second sub-contact layer and the third sub-contact layer can form a eutectic structure, so that diffusion of germanium to the substrate layer is promoted, and ohmic contact is formed. The first sub-contact layer can promote the combination of the contact layer and the substrate, and the stability of ohmic contact is enhanced. In one embodiment, the ratio of the thickness of the first sub-contact layer to the thickness of the second sub-contact layer is 1:1.8-1:2.2, e.g. 1:2; the ratio of the thickness of the first sub-contact layer to the thickness of the third sub-contact layer is 1:1.8-1:2.2, e.g. 1:2.

In one embodiment, the first subcontact layer has a thickness of 38nm to 42nm, for example 40nm; the thickness of the second sub-contact layer is 78nm-82nm, for example 80nm; the thickness of the third subcontact layer is 78nm-82nm, for example 80nm.

In one embodiment, the material of the upper cover layer 4 comprises gold. The upper cap layer 4 facilitates better bonding of the semiconductor laser contact electrode to the gold wire.

In one embodiment, the thickness of the upper cap layer 4 is 100nm-200nm, for example 120nm, 150nm or 180nm.

Example 2

The embodiment provides a method for preparing a contact electrode of a semiconductor laser, referring to fig. 2, comprising the following steps:

step S1: providing a substrate layer;

step S2: forming a contact layer on one side surface of the substrate layer;

step S3: forming a diffusion barrier layer on the surface of one side of the contact layer, which is away from the substrate layer;

step S4: forming an upper cover layer on the surface of one side of the diffusion barrier layer, which is away from the substrate layer;

wherein the material of the diffusion barrier layer comprises a compound formed by bonding metal and a first element, and the component content of the first element in the diffusion barrier layer gradually increases from the contact layer to the upper cover layer;

alternatively, the material of the diffusion barrier layer includes a solid solution formed of a bonding metal and a second element, and the content of the second element in the diffusion barrier layer gradually increases from the contact layer toward the capping layer.

The method for manufacturing the semiconductor laser contact electrode provided in this embodiment is described in detail below with reference to fig. 1.

Referring to fig. 1, a substrate layer 1 is provided, which in one embodiment further comprises subjecting the substrate layer 1 to a cleaning process.

With continued reference to fig. 1, a contact layer 2 is formed on one side surface of a substrate layer 1; the step of forming the contact layer 2 on one side surface of the substrate layer 1 includes: a first sub-contact layer, a second sub-contact layer, and a third sub-contact layer are sequentially formed on one side surface of the substrate layer 1.

In this embodiment, the material of the first sub-contact layer includes nickel, the material of the second sub-contact layer includes germanium, the material of the third sub-contact layer includes gold, the thickness of the first sub-contact layer is 40nm, the thickness of the second sub-contact layer is 80nm, and the thickness of the third sub-contact layer is 80nm.

In one embodiment, the process of forming the contact layer 2 includes: electron beam evaporation process.

With continued reference to fig. 1, the step of forming a diffusion barrier layer 3 on a side surface of the contact layer 2 facing away from the substrate layer 1, and forming the diffusion barrier layer 3 on a side surface of the contact layer 2 facing away from the substrate layer 1 comprises: sputtering bonding metal on the surface of one side of the contact layer, which is far away from the substrate layer, by adopting a magnetron sputtering process, introducing gas of a first element in the process of sputtering the bonding metal, wherein the power of the sputtering bonding metal is fixed and the flow rate of the gas of the first element is gradually increased in the process of forming the diffusion barrier layer.

In this embodiment, the bonding metal comprises titanium and the gas of the first element comprises nitrogen.

In one embodiment, during the formation of the diffusion barrier layer 3, the initial flow rate of the gas of the first element is 1.8sccm to 2.2sccm, for example, 2sccm, and the initial flow rate of the gas of the first element is low, within which the diffusion barrier layer region connected to the contact layer is facilitated to exhibit adhesion characteristics of the bonding metal, which can promote bonding of the diffusion barrier layer to the contact layer. In one embodiment, the flow rate of the gas of the first element increases at a rate of 0.48sccm/min to 0.52sccm/min, for example 0.5sccm/min; the rate of increase of the flow rate of the gas of the first element is within the range, so that no heterogeneous interface is generated in the diffusion barrier layer, the whole diffusion barrier layer is of a single-layer structure rather than a multi-layer structure, electrons can smoothly pass through the diffusion barrier layer when current is transmitted inside the contact electrode of the semiconductor laser, and the diffusion barrier layer cannot cause the resistance of the contact electrode of the semiconductor laser to be greatly increased.

In this embodiment, the thickness of the diffusion barrier layer 3 is 200nm.

In one embodiment, annealing the contact layer 2 is further included before forming the diffusion barrier layer 3. The annealing treatment facilitates alloying of the contact layer and ohmic contact with the substrate layer.

In one embodiment, the temperature of the annealing treatment of the contact layer 2 is 360-380 ℃, such as 375 ℃, and if the temperature of the annealing treatment of the contact layer is less than 360 ℃, the effect of causing the contact layer to alloy and form an ohmic contact with the substrate layer is not obvious, the annealing treatment time is 18-22 minutes, such as 20 minutes, and if the time of the annealing treatment of the contact layer is less than 18 minutes, the effect of causing the contact layer to alloy and form an ohmic contact with the substrate layer is not obvious.

In one embodiment, before annealing the contact layer 2, the method further comprises heating the contact layer to a temperature of 23-26 ℃, wherein the temperature range is room temperature, and the final temperature of the heating is 360-380 ℃, such as 375 ℃; the time for the temperature-raising treatment is 18 minutes to 22 minutes, for example, 20 minutes. The temperature rise rate of the contact layer is 13 ℃ per minute to 16 ℃ per minute, for example 15 ℃ per minute, and the temperature rise rate of the contact layer is slow when the contact layer is subjected to the temperature rise treatment, so that the increase of the thermal stress of the wafer caused by the mismatching of the thermal expansion coefficients of the contact layer and the substrate layer can be avoided, and the risk of wafer fracture is reduced.

In one embodiment, after annealing the contact layer 2, the method further comprises cooling the contact layer, wherein the final temperature of the cooling treatment is 23-26 ℃, and the temperature range is room temperature; the temperature reduction treatment is carried out for 48 minutes to 52 minutes, for example, 50 minutes. The temperature reduction rate of the contact layer is 6 ℃/min-8 ℃/min, such as 7 ℃/min, and the temperature reduction rate of the contact layer is slow when the contact layer is subjected to cooling treatment, so that the increase of the thermal stress of the wafer caused by the mismatching of the thermal expansion coefficients of the contact layer and the substrate layer can be avoided, and the risk of wafer fragmentation is reduced.

With continued reference to fig. 1, the process of forming the capping layer 4 on the surface of the diffusion barrier layer 3 on the side facing away from the substrate layer 1 includes a magnetron sputtering process.

In this embodiment, the thickness of the upper cap layer 4 is 200nm.

Referring to fig. 3, fig. 3 is a transmission electron microscope micro-morphology of a semiconductor laser contact electrode prepared by the preparation method provided in this embodiment.

Referring to fig. 4, fig. 4 is an energy spectrum scanning result of a diffusion barrier layer in a contact electrode of a semiconductor laser along an arrow direction in fig. 3, which is prepared by using the preparation method provided in this embodiment, in fig. 4, an ordinate is a count of signal pulses, a unit is a count of thousands of scanning points, and an abscissa is a unit is a count of line scanning points in the arrow direction.

Test example 1

The semiconductor laser contact electrode prepared in example 2 was subjected to an annealing treatment for the purpose of creating a high temperature condition for the semiconductor laser contact electrode to evaluate the temperature resistance characteristics of the semiconductor laser contact electrode.

In one test example, the semiconductor laser contact electrode prepared in example 2 was annealed at 300℃for 30 minutes, and the surface morphology of the semiconductor laser contact electrode was observed with reference to FIG. 5, the scale in FIG. 5 being 200. Mu.m, and it was found that no alloy spot was formed on the surface of the semiconductor laser contact electrode prepared in example 2.

In another test example, the semiconductor laser contact electrode prepared in example 2 was annealed at 450 ℃ for 30 min, and the surface morphology of the semiconductor laser contact electrode was observed with reference to fig. 6, which is a scale of 200 μm in fig. 6, and it was found that only a few alloy spots were present on the surface of the semiconductor laser contact electrode prepared in example 2, and the circled portion in fig. 6 illustrates a part of the alloy spots, so that no overalloying of the metal film layer mixed in a large range occurred.

In the growth process of the diffusion barrier layer, the deposition rate of the bonding metal and the deposition rate of the gas of the first element are relatively small, and the growth process of the diffusion barrier layer is close to the thermodynamic equilibrium process, so that the growth surfaces of titanium nitride in the diffusion barrier layer of embodiment 2 are close-packed surfaces of respective crystal structures, the crystal structures of titanium nitride are face-centered cubes, the growth surfaces of the corresponding titanium nitride are (111) crystal planes, the concentration of nitrogen atoms in the titanium nitride diffusion barrier layer is gradually increased along with the gradual increase of the nitrogen flow, the lattice constant of titanium nitride is also gradually increased along with the gradual increase of the nitrogen flow, and the gradient of the nitrogen atom concentration along the direction from the contact layer to the upper layer in the diffusion barrier layer is less than 0.1 at%/nm, and therefore, the lattice parameter change of titanium nitride of adjacent atomic planes in the diffusion barrier layer is less than 1%, namely, adjacent (111) in the titanium nitride can be matched without forming a heterogeneous interface, and meanwhile, the diffusion barrier layer connected with the upper layer part has the characteristic of a high-melting point high-heat-stability metal compound due to the high nitrogen atom concentration, the high-melting point high-stability metal compound can effectively block the high-temperature-resistant semiconductor crystal plane in the upper layer, and the high-temperature-atomic-contact-resistant semiconductor electrode can be effectively improved. Finally, since the diffusion barrier layer and the contact layer thin film are grown separately, the part of the diffusion barrier layer connected to the contact layer exhibits the property of bonding metallic titanium due to having a low nitrogen atom concentration, and the bonding of the diffusion barrier layer and the contact layer can be promoted.

By the method for manufacturing the semiconductor laser contact electrode provided in example 2, 6 sets of semiconductor laser contact electrode rings having the same inner diameter and different outer diameters were manufactured. Then, the specific contact resistivity of the semiconductor laser contact electrode provided in this embodiment was detected by the four-probe method, referring to fig. 7, the abscissa represents the natural logarithm of the ratio of the semiconductor laser contact electrode outer diameter to the semiconductor laser contact electrode inner diameter, the ordinate represents the ratio of voltage to current, the solid point in the figure represents the data point corresponding to the detection result, the black line represents the connecting line of the data points, the gray line represents the straight line after the linear fitting of the detection result, and the specific contact resistivity of the semiconductor laser contact electrode was finally calculated to be. Since the material of the diffusion barrier layer is titanium nitride and is a high-conductivity metal compound, current can be efficiently transmitted therein, and furthermore, no heterogeneous interface exists in the diffusion barrier layer, and no severe scattering of carriers occurs during current transmission therein. Therefore, the specific contact resistivity of the semiconductor laser contact electrode prepared by the preparation method of the semiconductor laser contact electrode provided in example 2 is not significantly increased.

Example 3

The difference between the preparation method of the semiconductor laser contact electrode provided in this embodiment and the preparation method of the semiconductor laser contact electrode provided in embodiment 2 is that: the step of forming a diffusion barrier layer on a surface of the contact layer facing away from the substrate layer comprises: and sputtering the bonding metal and the second element target material on the surface of one side of the contact layer, which is far away from the substrate layer, by adopting a magnetron sputtering process, wherein the power of the sputtering bonding metal target material is fixed and the power of the sputtering second element target material is gradually increased in the process of forming the diffusion barrier layer.

In this embodiment, the bonding metal comprises titanium and the atoms of the second element comprise tungsten.

In this embodiment, the thickness of the diffusion barrier layer is 100nm.

In one embodiment, during the formation of the diffusion barrier layer, the initial power of the second element target is 0W to 0.1W, for example 0W or 0.01W, the initial power of the second element target is low, and the initial power of the second element target is within the range, so that the diffusion barrier layer connected with the contact layer is beneficial to show the adhesion property of bonding metal, and the bonding of the diffusion barrier layer and the contact layer can be promoted.

In one embodiment, the sputter second elemental target has a power increase rate of 4.8W/min to 5.2W/min, for example 5W/min; the power increasing rate of the sputtering second element target is in the range, so that no heterogeneous interface is generated in the diffusion barrier layer, the whole diffusion barrier layer is of a single-layer structure rather than a multi-layer structure, electrons can smoothly pass through the diffusion barrier layer when current is transmitted in the contact electrode of the semiconductor laser, and the diffusion barrier layer cannot cause the resistance of the contact electrode of the semiconductor laser to be greatly increased.

The same parts as those of embodiment 2 will not be described in detail with respect to this embodiment.

Test example 2

In one test example, the semiconductor laser contact electrode prepared in example 3 was annealed at 300℃for 30 minutes, and the surface morphology of the semiconductor laser contact electrode was observed with reference to FIG. 8, which shows that no alloy spot was formed on the surface of the semiconductor laser contact electrode prepared in example 3, with reference to FIG. 8, which shows a scale of 200. Mu.m.

In another test example, the semiconductor laser contact electrode prepared in example 3 was annealed at 450 ℃ for 30 min, and with reference to fig. 9, the scale in fig. 9 was 200 μm, and by observing the surface morphology of the semiconductor laser contact electrode, it was found that only a few alloy spots appeared on the surface of the semiconductor laser contact electrode prepared in example 3, and the circled portion in fig. 9 indicated some alloy spots, so that no overalloying of the metal film layer mixed in a large scale occurred.

Since the deposition rate of the bonding metal atoms and the deposition rate of the second elemental atoms are relatively small in the growth process of the diffusion barrier layer, the growth surface of the diffusion barrier layer of example 3 is an atomic close-packed surface thereof, and since the maximum solid solubility of the hetero-atomic tungsten atoms in the diffusion barrier layer is 10 at%, the crystal structure of the titanium-tungsten alloy solid solution therein is the same as that of the titanium metal. The crystal structure of titanium is close-packed hexagonal, so that the crystal structure of the titanium-tungsten alloy solid solution is also close-packed hexagonal, and the growth surface of the corresponding titanium-tungsten alloy is a (0001) crystal face. As the sputtering power of tungsten atoms increases, the solid solubility of tungsten atoms in the diffusion barrier increases, and the lattice constant of titanium-tungsten alloy increases. Because the increase rate of the sputtering power of the atoms of the second element is low, the concentration gradient of tungsten atoms in the diffusion barrier layer is less than 0.1 at percent/nm from the contact layer to the upper cover layer, so that the lattice parameter change rate of the adjacent atomic planes of the tungsten alloy in the diffusion barrier layer is less than 1 percent, namely the (0001) crystal planes of the titanium-tungsten alloy in the adjacent areas can be matched without forming a heterogeneous interface. Meanwhile, the diffusion barrier layer connected with the upper cover layer has the characteristic of a high-melting-point high-thermal-stability metal compound due to high tungsten atom concentration, and can effectively block the diffusion of gold atoms in the upper cover layer, so that the high-temperature resistance of the contact electrode of the whole semiconductor laser is improved. Finally, since the diffusion barrier layer and the contact layer thin film are grown separately, the part of the diffusion barrier layer connected to the contact layer exhibits the property of bonding metallic titanium due to having a low tungsten atom concentration, and the bonding of the diffusion barrier layer and the contact layer can be promoted.

Preparation of semiconductor laser contact electrode provided by example 3By the method, 6 groups of semiconductor laser contact electrode rings with the same inner diameter and different outer diameters are prepared. Then, the specific contact resistivity of the semiconductor laser contact electrode provided in this embodiment was detected by the four-probe method, referring to fig. 10, the abscissa represents the natural logarithm of the ratio of the semiconductor laser contact electrode outer diameter to the semiconductor laser contact electrode inner diameter, the ordinate represents the ratio of voltage to current, the solid point in the figure represents the data point corresponding to the detection result, the black line represents the connecting line of the data points, the gray line represents the straight line after the linear fitting of the detection result, and the specific contact resistivity of the semiconductor laser contact electrode was finally calculated to be. Since the material of the diffusion barrier layer is titanium tungsten alloy and is a high-conductivity metal solid solution, current can be efficiently transmitted in the diffusion barrier layer, and moreover, no heterogeneous interface exists in the diffusion barrier layer, so that the current cannot be subjected to severe scattering of carriers during the transmission in the diffusion barrier layer. Therefore, the specific contact resistivity of the semiconductor laser contact electrode prepared by the preparation method of the semiconductor laser contact electrode provided in example 3 did not increase significantly.

It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the invention.

Claims

1. A semiconductor laser contact electrode, comprising:

a substrate layer;

the contact layer is positioned on one side surface of the substrate layer;

a diffusion barrier layer positioned on a surface of the contact layer on a side facing away from the substrate layer;

an upper cover layer positioned on the surface of one side of the diffusion barrier layer away from the substrate layer;

wherein the material of the diffusion barrier layer comprises a compound formed by a bonding metal and a first element, and the component content of the first element in the diffusion barrier layer gradually increases in the direction from the contact layer to the upper cover layer;

alternatively, the material of the diffusion barrier layer includes a solid solution formed of a bonding metal and a second element, and the component content of the second element in the diffusion barrier layer gradually increases in a direction from the contact layer to the upper cover layer;

The bonding metal includes: titanium or nickel;

the first element comprises nitrogen;

the second element includes any one of tungsten, niobium, or chromium.

2. The semiconductor laser contact electrode according to claim 1, wherein the component content of the first element in the diffusion barrier layer increases with a gradient of less than 0.1at.% per nm and the component content of the second element in the diffusion barrier layer increases with a gradient of less than 0.1at.% per nm in a direction from the contact layer to the upper cap layer.

3. The semiconductor laser contact electrode according to claim 1 or 2, wherein the lattice parameter of the diffusion barrier layer increases gradually in a direction from the contact layer to the upper cap layer, the gradient of the increase in lattice parameter of the diffusion barrier layer being less than 0.1%/nm.

4. The semiconductor laser contact electrode of claim 1, wherein the direction of the diffusion barrier layer from the contact layer to the cap layer comprises a first sub-diffusion barrier region to an nth sub-diffusion barrier region, N being an integer equal to or greater than 2;

the first element in the first sub-diffusion barrier region has a composition content of 3at.% to 5at.%, and the first element in the nth sub-diffusion barrier region has a composition content of 16at.% to 20at.%;

The composition content of the second element in the first sub-diffusion barrier region is 3at.% to 5at.%, and the composition content of the second element in the nth sub-diffusion barrier region is 6at.% to 10at.%.

5. The semiconductor laser contact electrode of claim 1, wherein the compound formed by the bonding metal and the first element has a melting point of 1500 ℃ to 2500 ℃; the melting point of the solid solution formed by the binding metal and the second element is 1500-2000 ℃.

6. The semiconductor laser contact electrode of claim 1, wherein the diffusion barrier layer has a thickness of 100nm to 500nm.

7. The semiconductor laser contact electrode of claim 1, wherein the contact layer comprises a first sub-contact layer, a second sub-contact layer, and a third sub-contact layer stacked in that order in a direction from the substrate layer to the diffusion barrier layer.

8. The semiconductor laser contact electrode of claim 7, wherein the material of the first sub-contact layer comprises any one of nickel, platinum, or palladium, the material of the second sub-contact layer comprises germanium, and the material of the third sub-contact layer comprises gold.

9. The semiconductor laser contact electrode of claim 7, wherein a ratio of a thickness of the first sub-contact layer to a thickness of the second sub-contact layer is 1:1.8-1:2.2, the ratio of the thickness of the first sub-contact layer to the thickness of the third sub-contact layer is 1:1.8-1:2.2.

10. The semiconductor laser contact electrode of claim 7, wherein the first sub-contact layer has a thickness of 38nm to 42nm, the second sub-contact layer has a thickness of 78nm to 82nm, and the third sub-contact layer has a thickness of 78nm to 82nm.

11. A method for preparing a contact electrode of a semiconductor laser, comprising:

providing a substrate layer;

forming a contact layer on one side surface of the substrate layer;

forming a diffusion barrier layer on the surface of one side of the contact layer, which is away from the substrate layer;

forming an upper cover layer on the surface of one side of the diffusion barrier layer, which faces away from the substrate layer;

the material of the diffusion barrier layer comprises a compound formed by bonding metal and a first element, and the component content of the first element in the diffusion barrier layer gradually increases from the contact layer to the upper cover layer;

alternatively, the material of the diffusion barrier layer includes a solid solution formed of a bonding metal and a second element, and the component content of the second element in the diffusion barrier layer gradually increases from the contact layer to the upper cap layer;

the bonding metal includes: titanium or nickel;

the first element comprises nitrogen;

The second element includes any one of tungsten, niobium, or chromium.

12. The method of claim 11, wherein forming a diffusion barrier layer on a surface of the contact layer on a side facing away from the substrate layer comprises: sputtering bonding metal on the surface of one side of the contact layer, which is far away from the substrate layer, by adopting a magnetron sputtering process, introducing gas of a first element in the process of sputtering the bonding metal, wherein the power of the sputtering bonding metal is fixed and the flow rate of the gas of the first element is gradually increased in the process of forming a diffusion barrier layer.

13. The method for manufacturing a semiconductor laser contact electrode according to claim 12, wherein an initial flow rate of the gas of the first element is 1.8sccm to 2.2sccm and a flow rate of the gas of the first element is increased at a rate of 0.48sccm/min to 0.52sccm/min in forming the diffusion barrier layer.

14. The method of claim 11, wherein forming a diffusion barrier layer on a surface of the contact layer on a side facing away from the substrate layer comprises: and sputtering atoms of bonding metal and the second element on the surface of one side of the contact layer, which is away from the substrate layer, by adopting a magnetron sputtering process, wherein the power of the sputtering atoms of the bonding metal is fixed and the power of the sputtering atoms of the second element is gradually increased in the process of forming the diffusion barrier layer.

15. The method for manufacturing a semiconductor laser contact electrode according to claim 14, wherein in forming the diffusion barrier layer, an initial power of atoms of the sputtered second element is 0W to 0.1W, and a rate of increase of the power of atoms of the sputtered second element is 4.8W/min to 5.2W/min.

16. The method of manufacturing a contact electrode for a semiconductor laser as claimed in claim 11, wherein the step of forming a contact layer on one side surface of the substrate layer comprises: sequentially forming a first sub-contact layer, a second sub-contact layer and a third sub-contact layer which are stacked on one side surface of the substrate layer;

the process for forming the contact layer comprises the following steps: electron beam evaporation process.

17. The method of claim 11, further comprising annealing the contact layer prior to forming the diffusion barrier layer.

18. The method for manufacturing a contact electrode of a semiconductor laser according to claim 17, wherein the contact layer is annealed at a temperature of 360 ℃ to 380 ℃ for 18 minutes to 22 minutes.

19. The method of claim 11, wherein forming an upper cap layer on a surface of the diffusion barrier layer on a side facing away from the substrate layer comprises a magnetron sputtering process.