Method for improving reliability of high-power laser

Abstract

The invention relates to the technical field of lasers, in particular to a method for improving the reliability of a high-power laser, and the method comprises the following steps: S21, depositing a mask layer with an etched end surface; s22, the end, close to the light emitting face, of the mask layer is etched, the etching depth is not smaller than the thickness of the mask layer, and an etching area is formed; s23, etching the etching region, wherein the bottom of the etched region is lower than the bottom of the active layer; s24, carrying out wet etching through the etching solution; s25, carrying out a regrowth process in the etching region of the buffer layer; by adopting an MOCVD (Metal Organic Chemical Vapor Deposition) butt-joint growth technology, growing a transparent material which is not absorbed by light again in the etching region of the buffer layer to form a passivation layer; and S26, removing the residual mask layer. A cavity surface passivation process of a traditional high-power laser is changed, a transparent material window is directly grown near the cavity surface of a chip, absorption and heating at the cavity surface are reduced, and the damage threshold of the high-power edge-emitting laser is improved.

Description

Technical Field

[0001] The present application relates to the technical field of lasers, and in particular to a method for improving the reliability of high-power lasers. Background Art

[0002] For high-power lasers, improving reliability is crucial. Quantum well (QMW) is the core area of ​​laser photoelectric conversion, and its internal power density is as high as 10 10 W / cm 3 When the laser is running, the power that is not converted into light can cause strong local heating and even physical damage to the laser end face. This failure mode is called catastrophic optical mirror damage (COMD). Summary of the Invention

[0003] In order to reduce catastrophic optical mirror damage, the present application provides a method for improving the reliability of high-power lasers.

[0004] The present application provides a method for improving the reliability of a high-power laser using the following technical solutions: A method for improving the reliability of a high power laser comprises the following steps: S21, depositing a mask layer for end face etching by PECVD; S22, etching the end portion of the mask layer close to the light-emitting surface using a photolithography technique, with the etching depth being no less than the thickness of the mask layer, to form an etching area, transferring the pattern of the area to be etched to the mask layer, and then etching the semiconductor material; S23, etching the etched area by dry etching, wherein the bottom of the etched area is lower than the bottom of the active layer; S24, performing wet etching using an etching solution until the buffer layer is etched; S25, performing a regrowth process in the etched area of ​​the buffer layer; using MOCVD butt-joint growth technology, regrowing a light-non-absorbing transparent material in the etched area of ​​the buffer layer to form a passivation layer; S26, removing the remaining mask layer.

[0005] By adopting the above technical solution, the traditional high-power laser cavity surface passivation process is changed, and a transparent material window is directly grown near the chip cavity surface to reduce absorption and heat generation at the cavity surface and improve the damage threshold of the high-power edge-emitting laser.

[0006] Preferably, in step S22, the distance between the cross section of the etched area and the light emitting surface is 100-200 um.

[0007] By adopting the above technical solution, the etching length is longer, and it is easier to etch and dock and grow new materials.

[0008] Preferably, in step S24, wet etching is performed at a constant temperature of 50°C, and the etching solution is H2SO4:H2O2:H2O.

[0009] By adopting the above technical solution, under the above conditions, the etching depth can be accurately controlled.

[0010] Preferably, in step S25 , the material of the passivation layer is InGaAsP or InGaAs or InP.

[0011] Preferably, step S22 to step S25 are repeated at least twice to form at least two passivation layers, and the two passivation layers are made of different materials.

[0012] By adopting the above technical solution, when one passivation layer fails, the other passivation layer still plays a protective role to prevent external oxygen molecules from oxidizing the cavity surface. The window formed by the multiple passivation layers enhances the protective effect of the cavity surface.

[0013] Preferably, the material of the passivation layer closest to the non-light-emitting surface is InP or InGaAsP, and the material of the passivation layer closest to the light-emitting surface is InGaAs.

[0014] By adopting the above technical solution, InGaAs is not easily oxidized and has a weaker ability to absorb oxygen molecules, thereby isolating the oxygen molecules and improving the protection effect of the cavity surface.

[0015] As a preference, after completing step S25, before repeating step S22, Step S251 , etching the upper end surface of the passivation layer so that the height of the upper end of the passivation layer is lower than the upper end of the mask layer but higher than the lower end of the mask layer, and then depositing a mask layer on the upper end of the passivation layer.

[0016] By adopting the above technical solution, when multiple passivation layers are grown, a mask is deposited on the surface of the previous passivation layer to protect the previous passivation layer, ensuring that the previous passivation layer is not affected during the subsequent etching process.

[0017] Preferably, the material of the mask layer is silicon nitride or silicon oxide.

[0018] In summary, this application includes at least one of the following beneficial technical effects: By changing the traditional high-power laser cavity passivation process, a transparent material window is directly grown near the chip cavity surface to reduce absorption and heat generation at the cavity surface, increase the damage threshold of the high-power edge-emitting laser, further reduce COMD risks, and improve chip reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 11 is a flow chart of forming a passivation layer in an embodiment.

[0020] Description of reference numerals: 1. P-side; 2. Active layer; 3. Mask layer; 4. Passivation layer. DETAILED DESCRIPTION

[0021] The present application is further described in detail below in conjunction with all the accompanying drawings.

[0022] Example

[0023] The present application discloses a method for improving the reliability of a high-power laser. Figure 1 , including the following steps: S1, overlay mark etching, mainly etching the highly doped GaAs cap layer to adjust the current injection area and current injection efficiency; S21. Deposit a mask layer 3 for end face etching on the P surface 1 by using a PECVD method; the material of the mask layer 3 is silicon nitride or silicon oxide.

[0024] S22. Use photolithography technology to etch the end of the mask layer 3 close to the light-emitting surface. The etching depth is not less than the thickness of the mask layer 3 to form an etching area. After transferring the pattern of the area to be etched to the mask layer 3, the semiconductor material is etched. The distance between the cross section of the etched area and the light-emitting surface is 100-200um.

[0025] S23, etching the etched area by dry etching, and the bottom after etching is lower than the bottom of the active layer 2; S24, wet etching is performed using an etching solution until the buffer layer is reached; the wet etching is performed at a constant temperature of 50° C., and the etching solution is H 2 SO 4 : H 2 O 2 : H 2 O.

[0026] S25, performing a regrowth process in the etched area of ​​the buffer layer; using MOCVD butt-joint growth technology, regrow a light-non-absorbing transparent material in the etched area of ​​the buffer layer to form a passivation layer 4; the material of the passivation layer 4 is InGaAsP or InGaAs or InP.

[0027] Step S251 , etching the upper end surface of the passivation layer 4 so that the upper end of the passivation layer 4 is lower than the upper end of the mask layer 3 but higher than the lower end of the mask layer 3 , and then depositing a mask layer 3 on the upper end of the passivation layer 4 .

[0028] Repeat steps S22-S251 2-3 times.

[0029] S26 , removing the remaining mask layer 3 .

[0030] Among the multi-layer passivation layer 4 , the material of the passivation layer 4 closest to the non-light-emitting surface is InP or InGaAsP, and the material of the passivation layer 4 closest to the light-emitting surface is InGaAs.

[0031] S3. Waveguide etching (Ridge etch): First, a ridge pattern is formed through photolithography, and then a certain depth is etched by dry etching or wet etching. It is mainly used to provide lateral refractive index steps and control current injection.

[0032] S4. A SixNy insulating layer is deposited on the basis of the etched Mark and Ridge patterns to serve as a current insulating layer and protect the epitaxial structure.

[0033] S5. A P metal window pattern is formed above the Ridge through photolithography, and then the highly doped GaAs cap layer is leaked through dry etching of SixNy to provide conditions for the subsequent formation of ohmic contact.

[0034] S6. Grow seed gold to provide a conductive path for subsequent electroplated gold deposition, and also form an ohmic contact with the highly doped gallium arsenide cap layer below; form an electroplating pattern through photolithography to deposit the required target thickness of metal.

[0035] S7. Finally, the N-side is thinned and polished, and then the N-side metal is grown. At this point, the entire traditional laser preparation process is completed.

[0036] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A method for improving the reliability of a high-power laser, characterized in that: The following steps are included: S21, depositing a mask layer for end face etching by PECVD; S22, etching the end portion of the mask layer close to the light-emitting surface using a photolithography technique, with the etching depth being no less than the thickness of the mask layer, to form an etching area, transferring the pattern of the area to be etched to the mask layer, and then etching the semiconductor material; S23, etching the etched area by dry etching, wherein the bottom of the etched area is lower than the bottom of the active layer; S24, performing wet etching using an etching solution until the buffer layer is etched; S25, performing a regrowth process in the etched area of ​​the buffer layer; using MOCVD butt-joint growth technology, regrowing a light-non-absorbing transparent material in the etched area of ​​the buffer layer to form a passivation layer; S26, removing the remaining mask layer.

2. The method for improving the reliability of a high-power laser according to claim 1, wherein: In step S22, the distance between the cross section of the etched area and the light emitting surface is 100-200 μm.

3. The method for improving the reliability of a high-power laser according to claim 1, wherein: In step S24, wet etching is performed at a constant temperature of 50° C., and the etching solution is H 2 SO 4 : H 2 O 2 : H 2 O.

4. The method for improving the reliability of a high-power laser according to claim 1, wherein: In step S25 , the material of the passivation layer is InGaAsP, InGaAs, or InP.

5. The method for improving the reliability of a high-power laser according to claim 1, wherein: Steps S22 to S25 are repeated at least twice to form at least two passivation layers, and the two passivation layers are made of different materials.

6. The method for improving the reliability of a high-power laser according to claim 5, wherein: The material of the passivation layer closest to the non-light-emitting surface is InP or InGaAsP, and the material of the passivation layer closest to the light-emitting surface is InGaAs.

7. The method for improving the reliability of a high-power laser according to claim 5, wherein: After completing step S25, repeat step S22 before proceeding. Step S251 , etching the upper end surface of the passivation layer so that the height of the upper end of the passivation layer is lower than the upper end of the mask layer but higher than the lower end of the mask layer, and then depositing a mask layer on the upper end of the passivation layer.

8. The method for improving the reliability of a high-power laser according to claim 1, wherein: The material of the mask layer is silicon nitride or silicon oxide.

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