Method for manufacturing laser based on docking growth process and laser

Abstract

The present invention relates to the field of optical communication technologies, and provides a method for manufacturing a laser based on a butt-joint growth process, including the following steps: S1, growing an epitaxial structure on a substrate; S2, sequentially growing an InGaAsP layer, a first InP layer, and a barrier layer on the epitaxial structure; S3, growing a mask layer on the barrier layer and performing etching to etch the unmasked area into the InGaAsP layer; S4, etching the InGaAsP layer with a sulfuric acid-based anisotropic etching solution, then removing the sidewall oxide layer with diluted hydrofluoric acid, and retaining the mask layer on the surface; S5, then using a butt-joint process to butt-joint and grow an AlGaInAs layer; S6, after the butt-joint growth is completed, removing the mask layer with hydrofluoric acid; S7, then removing the barrier layer and then epitaxially growing and fabricating a finishing structure to complete the fabrication of the laser. A laser is also provided, which is obtained by using the above growth method. The present invention adopts a butt-joint growth process. When an AlGaInAs layer is butt-joint grown on an InGaAsP layer, the AlGaInAs layer grows under the barrier layer, avoiding the undercut phenomenon caused by the reaction of hydrofluoric acid with aluminum.

Description

Technical Field

[0001] The present invention relates to the technical field of optical communication, and particularly to a method for manufacturing a laser based on a butt-joint growth process and a laser. Background Art

[0002] With the development of high-speed optical communication, higher requirements are put forward for communication lasers. In order to achieve high-speed modulation of high-performance devices, integration technologies and new materials have been applied. For example, an EML laser (modulation laser) integrating an LD light source and an EAM modulator. In terms of integration technology, existing solutions for integrating LD and EAM include: a homogeneous layer scheme, a selective area growth scheme, etc. The EML laser of the homogeneous layer scheme grows the structures of LD and EAM simultaneously through a single epitaxial growth, and adjusts the wavelength detuning of the LD to make the absorption of the EAM meet the application requirements. However, the structures of LD and EAM cannot be optimized separately, and it is impossible to take into account the light output effect of the LD and the extinction ratio of the EAM. In addition, the selective area growth scheme is to design a mask, and the epitaxial deposition rate is different in the areas between the masks, so as to obtain structures with different thicknesses. In this way, an EAM different from the LD structure can be grown. Although the EAM structure can be optimized separately, the SAG (Selective Area Growth controllable quantum dot crystal material epitaxial growth technology) technology has high requirements for epitaxial growth equipment and processes. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for manufacturing a laser based on a butt-joint growth process and a laser, which can at least solve some defects in the prior art.

[0004] To achieve the above purpose, an embodiment of the present invention provides the following technical solution: A method for manufacturing a laser based on a butt-joint growth process, comprising the following steps:

[0005] S1, growing an epitaxial structure on a substrate;

[0006] S2, successively growing an InGaAsP layer, a first InP layer, and a blocking layer on the epitaxial structure;

[0007] S3, growing a mask layer on the blocking layer and performing etching to etch the non-masked area into the InGaAsP layer;

[0008] S4, etching the InGaAsP layer with a sulfuric acid-based anisotropic etching solution, then removing the sidewall oxide layer with diluted hydrofluoric acid, and retaining the mask layer on the surface;

[0009] S5, then growing an AlGaInAs layer by butt-joint growth;

[0010] S6, after the butt-joint growth is completed, removing the mask layer with hydrofluoric acid;

[0011] At S7, after removing the blocking layer, epitaxial growth is then carried out and a termination structure is fabricated to complete the fabrication of the laser.

[0012] Further, in the S5 step, the butt-joint growth specifically is: a second InP layer, an AlGaInAs layer, and an InP cover layer are sequentially grown at the etched notch. The growth height of the AlGaInAs layer does not exceed that of the blocking layer, and the growth height of the InP cover layer is the same as that of the blocking layer.

[0013] Further, when removing the blocking layer, part of the InP cover layer is removed together.

[0014] Further, a mixed solution of hydrochloric acid and phosphoric acid is used to remove the blocking layer.

[0015] Further, the blocking layer is made of InAs material, InP material, or InGaP material.

[0016] Further, in the S7 step, the epitaxial growth after removing the blocking layer specifically is: a cap layer and a contact layer are continuously grown in sequence.

[0017] Further, in the S7 step, the fabrication of the termination structure specifically includes: fabricating a waveguide, an isolation region, an electrical injection window, and an electrode, then thinning the sputtered alloy, and finally dicing and separating to complete the fabrication of the laser.

[0018] Further, the InGaAsP layer includes upper and lower waveguide layers and an active layer in the middle, and the thickness of the blocking layer is between 5 and 200 nm.

[0019] Further, in the S1 step, the growth of the epitaxial structure specifically is: a buffer layer and a grating layer are sequentially grown on the substrate, a grating is fabricated on the surface of the grating layer, and then a grating buried layer is grown to fill the grooves on the grating surface to make the surface flat.

[0020] Another technical solution is provided in an embodiment of the present invention: a laser fabricated by using the above growth method.

[0021] Compared with the prior art, the beneficial effects of the present invention are: by adopting the butt-joint growth process, the laser LD and the electro-absorption modulator EAM are respectively designed, so that the light output efficiency of the LD and the absorption performance of the EAM can be respectively optimized to obtain a higher-performance EML. At the same time, by using the AlGaInAs / InP material system, a high-temperature-resistant product can be obtained, and by improving the traditional butt-joint growth process, through the combination of epitaxy and anisotropic etching, the blocking layer under the mask layer is retained. When the AlGaInAs layer is butt-joint grown on the InGaAsP layer, the AlGaInAs layer grows under the blocking layer to avoid the undercut phenomenon caused by the reaction of hydrofluoric acid with aluminum. Description of the Drawings

[0022] Figure 1 It is a schematic structural diagram of the InGaAsP layer grown epitaxially after grating burying in a method for fabricating a laser based on the butt-joint growth process provided by an embodiment of the present invention;

[0023] Figure 2 It is a schematic structural diagram after dry etching in a method for fabricating a laser based on the butt-joint growth process provided by an embodiment of the present invention;

[0024] Figure 3 It is a schematic structural diagram after wet etching in a method for fabricating a laser based on the butt-joint growth process provided by an embodiment of the present invention;

[0025] Figure 4 It is a schematic structural diagram of the butt-joint growth of AlGaInAs on a traditional InGaAsP layer;

[0026] Figure 5 It is a schematic diagram of the undercutting of the mask layer removed by hydrofluoric acid in the butt-joint growth of AlGaInAs on a traditional InGaAsP layer;

[0027] Figure 6 It is a schematic structural diagram of an epitaxial structure with an InGaP barrier layer and an InGaAsP active layer in a method for fabricating a laser based on the butt-joint growth process provided by an embodiment of the present invention;

[0028] Figure 7 It is a schematic structural diagram after wet etching of an InGaP barrier layer in a method for fabricating a laser based on the butt-joint growth process provided by an embodiment of the present invention;

[0029] Figure 8 It is a schematic structural diagram of an InGaP barrier layer and the butt-joint growth of an AlGaInAs layer on an InGaAsP layer in a method for fabricating a laser based on the butt-joint growth process provided by an embodiment of the present invention;

[0030] Figure 9 It is a schematic structural diagram of an InGaP barrier layer and the removal of the mask layer by hydrofluoric acid in a method for fabricating a laser based on the butt-joint growth process provided by an embodiment of the present invention;

[0031] Figure 10 It is a schematic structural diagram of an InGaP barrier layer and the removal of the barrier layer in a method for fabricating a laser based on the butt-joint growth process provided by an embodiment of the present invention;

[0032] Figure 11 It is a schematic structural diagram of an InGaP barrier layer, and the structure after the growth of the cap layer and the contact layer in a method for fabricating a laser based on the butt-joint growth process provided by an embodiment of the present invention;

[0033] Figure 12 It is a top view of a laser chip after preparation by a method for fabricating a laser based on a butt-joint growth process provided by an embodiment of the present invention;

[0034] Figure 13 It is a cross-sectional view of a laser chip after preparation by a method for fabricating a laser based on a butt-joint growth process provided by an embodiment of the present invention along the A-A direction;

[0035] In the attached drawing reference numerals: 1 - substrate; 2 - InP buffer layer; 3 - grating layer; 4 - grating buried layer; 5 - InGaAsP layer; 6 - first InP layer; 7 - mask layer; 8 - InP layer; 9 - AlGaInAs layer; 10 - InP capping layer; 11 - etching position; 12 - second InP layer; 13 - AlGaInAs layer; 14 - InP capping layer; 15 - cover layer; 16 - contact layer; 17 - passivation layer; 18 - isolation region; 19 - electrode; 20 - barrier layer. Detailed implementation manners

[0036] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0037] For Figures 1 to 13 , where Figure 1 is a schematic structural diagram of epitaxial growth of an InGaAsP layer after grating burial, including a substrate 1, an InP buffer layer 2, a grating layer 3, a grating buried layer 4, an InGaAsP layer 5, and a first InP layer 6. Figure 2 It is a schematic structural diagram after dry etching, including a substrate 1, an InP buffer layer 2, a grating layer 3, a grating buried layer 4, an InGaAsP layer 5, a first InP layer 6, and a mask layer 7. Figure 3 It is a schematic structural diagram after wet etching, including an InP buffer layer 2, a grating layer 3, a grating buried layer 4, an InGaAsP layer 5, a first InP layer 6, and a mask layer 7. Figure 4 Schematic structural diagram of traditional InGaAsP layer butt-joint growth of AlGaInAs, including a grating buried layer 4, an InGaAsP layer 5, a first InP layer 6, a mask layer 7, a butt-joint growth InP layer 8, a butt-joint growth AlGaInAs layer 9, and an InP capping layer 10. Figure 5It is a schematic diagram of the etching of the traditional InGaAsP layer for butt-joint growth of AlGaInAs and the removal of the masking layer by hydrofluoric acid, including a grating buried layer 4, an InGaAsP layer 5, a first InP layer 6, a butt-joint growth InP layer 8, a butt-joint growth AlGaInAs layer 9, an InP covering layer 10, and a hydrofluoric acid etching position 11. Figure 6 It is a schematic diagram of an epitaxial structure with an InGaP barrier layer and an InGaAsP active layer, including a substrate 1, an InP buffer layer 2, a grating layer 3, a grating buried layer 4, an InGaAsP layer 5, a first InP layer 6, and a barrier layer 20. Figure 7 It is a schematic diagram of the structure after wet etching of the InGaP barrier layer, including an InP buffer layer 2, a grating layer 3, a grating buried layer 4, an InGaAsP layer 5, a first InP layer 6, and a barrier layer 20. Figure 8 It is a schematic diagram of the structure of butt-joint growth of an AlGaInAs layer on an InGaAsP layer with an InGaP barrier layer, including a grating buried layer 4, an InGaAsP layer 5, a first InP layer 6, a masking layer 7, a butt-joint growth second InP layer 12, a butt-joint growth AlGaInAs layer 13, an InP covering layer 14, and a barrier layer 20. Figure 9 It is a schematic diagram of the structure of removing the masking layer by hydrofluoric acid with an InGaP barrier layer, including a grating buried layer 4, an InGaAsP layer 5, a first InP layer 6, a butt-joint growth second InP layer 12, a butt-joint growth AlGaInAs layer 13, an InP covering layer 14, and a barrier layer 20. Figure 10 It is a schematic diagram of removing the barrier layer with an InGaP barrier layer, including a grating buried layer 4, an InGaAsP layer 5, a first InP layer 6, a butt-joint growth second InP layer 12, a butt-joint growth AlGaInAs layer 13, and a partial InP covering layer 14. Figure 11 It is a schematic diagram of the structure after growth of the covering layer and the contact layer with an InGaP barrier layer, including a grating buried layer 4, an InGaAsP layer 5, a first InP layer 6, a butt-joint growth second InP layer 12, a butt-joint growth AlGaInAs layer 13, a partial InP covering layer 14, a covering layer 15, and a contact layer 16. Figure 12 It is a top view of the laser chip, including a passivation layer 17 and an electrode 19. Figure 13 It is a cross-sectional view of the laser along the A-A direction, including a grating buried layer 4, an InGaAsP layer 5, a first InP layer 6, a butt-joint growth second InP layer 12, a butt-joint growth AlGaInAs layer 13, a partial InP covering layer 14, a covering layer 15, a contact layer 16, a passivation layer 17, an isolation region 18, and an electrode 19.

[0038] Please refer to Figure 1 、 Figure 2 、 Figure 3 、 Figures 6 to 13, an embodiment of the present invention provides a method for manufacturing a laser based on a butt-joint growth process, including the following steps: S1, growing an epitaxial structure on a substrate 1; S2, sequentially growing an InGaAsP layer 5, a first InP layer 6, and a barrier layer 20 on the epitaxial structure; S3, growing a mask layer 7 on the barrier layer 20 and performing etching to etch the unmasked area into the InGaAsP layer 5; S4, etching the InGaAsP layer 5 with a sulfuric acid-based anisotropic etching solution, then removing the sidewall oxide layer with diluted hydrofluoric acid, and retaining the mask layer on the surface; S5, then using a butt-joint process to butt-joint and grow an AlGaInAs layer 12; S6, after the butt-joint growth is completed, removing the mask layer 7 with hydrofluoric acid; S7, then removing the barrier layer 20 and then epitaxially growing and fabricating a finishing structure to complete the fabrication of the laser. In this embodiment, the butt-joint growth process is adopted to separately design a laser diode (LD) and an electro-absorption modulator (EAM). In this way, the light output efficiency of the LD and the absorption performance of the EAM can be optimized respectively, and a higher-performance electro-absorption modulated laser (EML) can be obtained. At the same time, the AlGaInAs / InP material system can obtain a high-temperature-resistant product. By improving the traditional butt-joint growth process, through the combination of epitaxy and anisotropic etching, and retaining the barrier layer under the mask layer, when the AlGaInAs layer 13 is butt-joint grown on the InGaAsP layer 5, the AlGaInAs layer 13 grows under the barrier layer 20, avoiding the undercutting phenomenon caused by the direct reaction of hydrofluoric acid with aluminum. Specifically, the undercutting phenomenon is that when hydrofluoric acid contacts an aluminum-containing material and reacts, the reaction product is carried away by the solution, resulting in holes being formed in the reaction area. As the hydrofluoric acid solution continues to contact the aluminum-containing material, the holes become larger, forming the undercutting phenomenon. Specifically, in order to overcome the defects existing in the prior art, the present invention adopts a butt-joint growth scheme to separately design a laser diode (LD) and an electro-absorption modulator (EAM), so that the light output efficiency of the LD and the absorption performance of the EAM can be optimized respectively, and a higher-performance electro-absorption modulated laser (EML) can be obtained. In terms of materials, compared with the traditional InGaAsP / InP material system, the AlGaInAs / InP material system has obvious advantages in high-temperature performance. However, through experiments, it is found that aluminum in AlGaInAs has a high reaction ability, and aluminum reacts violently with oxygen in the air, resulting in the oxidation of the AlGaInAs surface. If an InGaAsP material is butt-joint grown on the oxidized AlGaInAs layer, many defects will be generated at the butt-joint growth interface, affecting the performance and lifespan of the EML. We found that if an AlGaInAs is butt-joint grown on the InGaAsP layer, such defects can be avoided. However, aluminum is reactive and can react with hydrofluoric acid. When removing the mask layer with hydrofluoric acid, it is easy to react with the aluminum under the mask layer to produce undercutting, as Figures 1 to 5As shown, it causes yield loss and even scrapping. Therefore, in this embodiment, by adopting a barrier layer, the etching phenomenon caused by the reaction between the InGaAsP layer and aluminum during the removal of the mask layer with hydrofluoric acid can be ingeniously solved. Preferably, the mask layer is sio 2 / sin x mask layer. The dilution concentration of the diluted hydrofluoric acid is controlled to only etch the oxide layer on the sidewalls, but not remove the surface mask layer.

[0039] As an optimized solution of the embodiment of the present invention, please refer to Figure 1 、 Figure 2 、 Figure 3 、 Figures 6 to 13 In the S5 step, the butt-joint growth is specifically as follows: a second InP layer 12, an AlGaInAs layer 13, and an InP covering layer 14 are sequentially grown at the etched notch. The growth height of the AlGaInAs layer 13 does not exceed that of the barrier layer 20, and the growth height of the InP covering layer 14 is the same as that of the barrier layer 20. Preferably, when removing the barrier layer 20, part of the InP covering layer 14 is removed together.

[0040] As an optimized solution of the embodiment of the present invention, please refer to Figure 1 、 Figure 2 、 Figure 3 、 Figures 6 to 13 The barrier layer 20 can be removed by using a mixed solution of hydrochloric acid and phosphoric acid. This mixed solution of hydrochloric acid and phosphoric acid also removes part of the InP covering layer 14.

[0041] As an optimized solution of the embodiment of the present invention, please refer to Figure 1 、 Figure 2 、 Figure 3 、 Figures 6 to 13 The barrier layer 20 is made of InAs material, InP material, or InGaP material. When the barrier layer is made of InAs and InP materials, the InGaAsP layer is etched with a sulfuric acid-based anisotropic etching solution, the sidewall oxide layer is removed with diluted hydrofluoric acid, after the butt-joint growth is completed, the mask layer is removed with hydrofluoric acid, and then the barrier layer is removed with a mixed solution of hydrochloric acid and phosphoric acid; when the barrier layer is InGaP, the InGaAsP layer is etched with a sulfuric acid-based anisotropic etching solution, the sidewall oxide layer is removed with diluted hydrofluoric acid, after the butt-joint growth is completed, the mask layer is removed with hydrofluoric acid, and then the barrier layer is removed with a mixed solution of hydrochloric acid and phosphoric acid.

[0042] As an optimized solution of the embodiment of the present invention, please refer to Figure 1 、 Figure 2 、 Figure 3 、 Figures 6 to 13, the InGaAsP layer 5 includes upper and lower waveguide layers and an intermediate active layer, and the thickness of the blocking layer 20 is between 5 and 200 nm.

[0043] So far, the manufacturing method has been refined. The following is the complete manufacturing method when the blocking layer uses InGaP material:

[0044] Use MOCVD to sequentially grow an InP buffer layer 2 and a grating layer 3 on the substrate 1;

[0045] Use holographic / electron beam technology to fabricate a grating on the surface of the grating layer 3, use a combination of dry and wet etching to etch out the grating morphology, and then use MOCVD to grow a grating buried layer 4 to fill the grooves on the grating surface to make the surface flat; then epitaxially grow an InGaAsP layer 5, a first InP layer 6, and a blocking layer InGaP 20, as shown in Figure 6 ;

[0046] Grow a SiO 2 mask layer 7, use photolithography and etching processes to retain the mask layer 7, and dry-etch the non-mask area into the InGaAsP layer 5;

[0047] Use a sulfuric acid-based anisotropic etching solution to etch the InGaAsP layer 5 to ensure that the bottom InGaAsP material is etched clean, and then use diluted hydrofluoric acid to remove the sidewall oxide layer, as shown in Figure 7 , where the sulfuric acid-based solution and the diluted hydrofluoric acid solution hardly react with the InGaP blocking layer 20 to ensure the integrity of the morphology of the InGaP blocking layer 20 under the mask layer;

[0048] Use MOCVD to grow a second InP layer 12, AlGaInAs 13, and an InP cover layer 14, where AlGaInAs 13 is grown under the InGaP blocking layer 20, and the InP cover layer 14 is connected to the InGaP blocking layer 20, as shown in Figure 8 ;

[0049] Use hydrofluoric acid to remove the mask layer 7. Since AlGaInAs 13 is covered by the InGaP blocking layer 20, the phenomenon of undercutting caused by the reaction of hydrofluoric acid with aluminum is avoided, as shown in Figure 9 ;

[0050] Use a mixed solution of hydrochloric acid and phosphoric acid to remove the InGaP blocking layer 20 and part of the InP cover layer 14, as shown in Figure 10 ;

[0051] Use MOCVD to grow an InP cap layer 15 and a contact layer 16 again, as shown in Figure 11 ;

[0052] Then grow a mask layer and fabricate waveguides, isolation regions, electrical injection windows, and electrodes;

[0053] Subsequently, the sputtered alloy is thinned, and finally, scribing and separation are performed to complete the fabrication of the laser, as Figure 12 and Figure 13 shown. It can be seen that DFB and EA are fabricated. The passivation layer 17, isolation region 18, and electrode 19 of the laser can also be seen in Figure 13 .

[0054] The core of the present invention is to retain the barrier layer under the mask layer, ensure that the butt-jointed grown AlGaInAs layer is under the barrier layer, and avoid etching due to reaction with hydrofluoric acid. At the same time, this technology is simple to operate and easy to industrialize and mass-produce.

[0055] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for manufacturing a laser based on a butt-jointed growth process, characterized in that: The steps include: S1, growing an epitaxial structure on a substrate; S2, continuing to sequentially grow an InGaAsP layer, a first InP layer and a barrier layer on the epitaxial structure; S3, growing a mask layer on the barrier layer and performing etching to etch the unmasked area into the InGaAsP layer; S4, etching the InGaAsP layer with a sulfuric acid-based anisotropic etching solution, and then removing the sidewall oxide layer with diluted hydrofluoric acid, while retaining the mask layer on the surface; S5, then growing an AlGaInAs layer by butt-jointing process, wherein the growth height of the AlGaInAs layer does not exceed the barrier layer; S6, after the butt-jointed growth is completed, removing the mask layer using hydrofluoric acid; S7, then using a mixed solution of hydrochloric acid and phosphoric acid to remove the barrier layer, and then epitaxially grow and make a finishing structure to complete the production of the laser.

2. A method for manufacturing a laser based on a butt-jointed growth process as claimed in claim 1, characterized in that: In the step S5, the butt-jointed growth specifically includes: growing a second InP layer, an AlGaInAs layer and an InP capping layer in sequence at the corrosion notch, and the growth height of the InP capping layer is consistent with the growth height of the barrier layer.

3. A method for manufacturing a laser based on a butt-jointed growth process as claimed in claim 2, characterized in that: When removing the barrier layer, part of the InP capping layer is removed together.

4. The method for manufacturing a laser based on a butt-joint growth process as claimed in claim 1, characterized in that: The barrier layer is made of InAs material, InP material or InGaP material.

5. The method for manufacturing a laser based on a butt-joint growth process as claimed in claim 1, characterized in that: In the step S7, the epitaxial growth after removing the barrier layer specifically includes: continuing to grow a cap layer and a contact layer in sequence.

6. The method for manufacturing a laser based on a butt-joint growth process according to claim 1, characterized in that: In the step S7, the production of the finishing structure specifically includes: producing a waveguide, an isolation region, an electrical injection window and an electrode, then thinning the sputtered alloy, and finally stripping and debonding to complete the production of the laser.

7. The method for manufacturing a laser based on a butt-joint growth process according to claim 1, characterized in that: The InGaAsP layer includes upper and lower waveguide layers and an active layer in the middle, and the thickness of the barrier layer is between 5 and 200 nm.

8. The method for manufacturing a laser based on a butt-joint growth process as claimed in claim 1, characterized in that: In the step S1, the growth of the epitaxial structure is specifically as follows: a buffer layer and a grating layer are grown on the substrate in sequence, a grating is made on the surface of the grating layer, and a grating buried layer is grown to fill the grooves on the grating surface to make the surface flat.

9. A laser, characterized in that: The method is prepared according to any one of claims 1 to 8.

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