Dfb laser and method for manufacturing the same
Patent Information
- Application Number
- CN202610985453.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-03
- Publication Date
- 2026-08-04
Smart Images
Figure CN122512221A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the technical field of laser fabrication, and in particular to a DFB laser and its fabrication method. Background Technology
[0002] During the fabrication of DFB lasers, the ridge waveguide structure is easily damaged by external contact objects such as grommets or nozzles. Mechanical protection can be provided by forming support units on both sides of the ridge waveguide structure to improve product yield.
[0003] However, in actual fabrication, after etching to form the ridge waveguide structure and before depositing the support layer, the epitaxial wafer surface is simultaneously exposed with multiple different semiconductor materials. Specifically, the top of the ridge waveguide structure is a contact layer, the sidewalls of the ridge waveguide structure are InP cladding and contact layers, the bottom of the trench is an etch stop layer, and the sidewalls of the mesa are InP cladding and contact layers. When using plasma-enhanced chemical vapor deposition to deposit a silicon nitride support layer on a non-planar structure with different exposed semiconductor materials, due to the inherent differences in the surface state density and secondary electron emission coefficient of the InP cladding, contact layer, and etch stop layer, the local electric field intensity distribution near the surfaces of different materials is uneven in the radio frequency plasma environment, especially at the interlayer boundaries of the semiconductor materials. Driven by the local electric field, charged active groups in the plasma are preferentially attracted to the boundary to participate in the reaction, resulting in abnormally preferential growth of silicon nitride at the semiconductor material boundary, forming nanoscale whisker-like protrusions extending along the boundary. Whisker-like protrusions are closely attached to the sidewalls of the ridge waveguide structure and the sidewalls of the mesa, and their structure is loose, with lower density and hardness than the normally deposited support layer.
[0004] Therefore, when removing the support layer in the trench area and part of the mesa area using an etching process to define the support units on the mesa, the following problems arise:
[0005] The support layer on the sidewalls needs to be completely removed during etching to expose the underlying semiconductor material surface. However, the etching gas has a higher etching rate for whisker-like protrusions, and the etching front advances unevenly at these protrusions. This results in uneven plasma exposure time and intensity on the semiconductor material surface during exposure, creating microscopic surface irregularities at the material boundaries where the whisker-like protrusions previously existed. The roughness of the sidewalls of the ridge waveguide structure increases the scattering loss of the optical waveguide, leading to an increase in the laser threshold current and a decrease in slope efficiency. Simultaneously, the local thinning of the InP cladding in the uneven areas of the ridge waveguide structure weakens the transverse confinement of carriers, increases leakage current, reduces internal quantum efficiency, and affects the mode stability of the laser. Summary of the Invention
[0006] Therefore, the purpose of this invention is to: form support units on the mesa on both sides of the ridge waveguide structure to protect the ridge waveguide structure, while avoiding the introduction of uneven defects on the sidewalls of the ridge waveguide structure, which would affect the photoelectric performance of the laser; and to propose a DFB laser and its fabrication method, which forms a passivation oxide layer with uniform surface potential through immersion treatment, avoids the growth of whisker-like protrusions during the deposition of the support layer, and makes the sidewalls of the ridge waveguide structure flat after etching, thereby simultaneously achieving mechanical protection and low waveguide scattering loss, and improving the device fabrication yield.
[0007] To address the aforementioned technical problems, this invention provides a method for fabricating a DFB laser, characterized in that, after epitaxial growth of a first intermediate device on a substrate and before the formation of electrodes, the fabrication method includes:
[0008] The first intermediate device is immersed in a liquid phase treatment solution to form a passivation oxide layer on the surface of the first intermediate device, thereby obtaining a second intermediate device; wherein the liquid phase treatment solution is a mixed solution of hydrofluoric acid, isopropanol and deionized water.
[0009] A support layer is deposited on the second intermediate device;
[0010] The support layer and the passivation oxide layer are etched in stages to define the region, thereby forming a support unit on the mesa of the second intermediate device to obtain a third intermediate device; wherein the horizontal height of the support unit is higher than the preset horizontal height of the upper electrode.
[0011] Preferably, the staged etching includes a first stage, which includes:
[0012] Under the first etching conditions, the support layer in the defined region is etched using a first etching gas to reduce the thickness of the support layer in the defined region to 80% to 90% of its original thickness;
[0013] The first etching conditions include: an inductively coupled plasma source power of 400W to 600W and a substrate bias power of 100W to 150W; the first etching gas includes argon gas with a flow rate of 50sccm to 80sccm; the defined region includes a trench region and a partial mesa region, the trench region including the top of the ridge waveguide structure, the sidewall of the ridge waveguide structure, the sidewall of the mesa, and the bottom of the trench; the partial mesa region includes the edge region on the mesa near the side of the ridge waveguide structure.
[0014] Preferably, the etching endpoint of the first stage includes: the remaining thickness of the support layer within the defined region is 150 nm to 400 nm.
[0015] Preferably, the staged etching further includes a second stage performed after the first stage, the second stage comprising:
[0016] Under the second etching conditions, the remaining support layer and passivation oxide layer in the defined area are etched using the second etching gas. After detecting the characteristic spectral line of In element, etching continues for a set time of 10% to 15% to remove the remaining support layer and passivation oxide layer in the defined area and expose the underlying semiconductor material to obtain the third intermediate device.
[0017] The second etching gas includes CHF3 and O2, with a CHF3 flow rate of 40 sccm and an O2 flow rate of 5 sccm. The second etching conditions include a substrate bias power of 50 W to 80 W. The set time is from the moment when etching begins using the second etching gas until the moment when the characteristic spectral line of In element is first detected.
[0018] Preferably, the thickness of the support layer is 1.5 μm to 2 μm, and the deposition method of the support layer is plasma-enhanced chemical vapor deposition (PECVD). The process parameters of the PECVD include:
[0019] Radio frequency power ranges from 100W to 200W;
[0020] The reaction chamber pressure is 80 Pa to 150 Pa;
[0021] The temperature of the second intermediate device during deposition is 200°C to 350°C;
[0022] The reaction source includes a mixed gas, NH3, and He; wherein the gas flow rate of NH3 is 10 sccm to 30 sccm; the gas flow rate of He is 200 sccm to 400 sccm; the gas flow rate of the mixed gas is 280 sccm to 360 sccm; the mixed gas includes SiH4 and N2, wherein the volume percentage of SiH4 in the mixed gas is 3% to 10%, and the gas flow rate ratio of SiH4 to NH3 in the mixed gas is 1:1 to 1:2.
[0023] Preferably, the method for preparing the liquid phase treatment solution includes:
[0024] 0.5 wt% hydrofluoric acid, isopropanol and deionized water are mixed and stirred evenly in a volume ratio of 1:1:20 to obtain the liquid phase treatment solution.
[0025] Preferably, the soaking conditions include: a system temperature of 20°C to 25°C; and a soaking time of 90s to 120s.
[0026] The thickness of the passivation oxide layer is 1 nm to 2 nm.
[0027] Preferably, the first intermediate device, the second intermediate device, and the third intermediate device each include:
[0028] A ridge waveguide assembly, comprising one or more ridge waveguide structures arranged in parallel, with a third groove provided between adjacent ridge waveguide structures;
[0029] A first platform and a second platform are located on both sides of the ridge waveguide assembly. A first groove is provided between the first platform and the ridge waveguide assembly; a second groove is provided between the second platform and the ridge waveguide assembly.
[0030] In this device, the trench regions of the first and third intermediate devices both expose semiconductor material; the trench regions of the second intermediate device both expose a passivation oxide layer.
[0031] Preferably, the distance between the edge of the support unit and the edge of the platform facing the ridge waveguide structure is 5 μm to 20 μm; and the nanoindentation hardness of the support unit is 15 GPa to 25 GPa.
[0032] On the other hand, the present invention provides a DFB laser, including a support unit;
[0033] The support unit includes a support layer, which is a silicon nitride layer, and the horizontal height of the silicon nitride layer is higher than the preset horizontal height of the upper electrode;
[0034] The support unit includes: a first support unit and a second support unit; wherein the first support unit is disposed on a first platform and the second support unit is disposed on a second platform.
[0035] Compared with the prior art, the above-described technical solution of the present invention has the following advantages:
[0036] The fabrication method of the DFB laser described in this invention can form support units protecting the ridge waveguide structure on the mesa on both sides of the ridge waveguide structure, while avoiding the introduction of uneven defects on the sidewalls of the ridge waveguide structure, which would affect the photoelectric performance of the laser. Specifically:
[0037] Before depositing the support layer, the first intermediate device, after etching to form the ridge waveguide structure, is immersed in a mixed solution of hydrofluoric acid, isopropanol, and deionized water. This forms a passivation oxide layer on all exposed semiconductor material surfaces, homogenizing the surface potential of different semiconductor materials. This prevents the growth of whisker-like protrusions caused by localized electric field concentration at the semiconductor material interfaces during support layer deposition. Therefore, during subsequent staged etching of the support layer and passivation oxide layer within the defined area to form the support units on the mesa, uneven defects will not occur on the sidewalls of the ridge waveguide structure due to preferential over-etching of whisker-like protrusions, ensuring the flatness of the optical waveguide sidewalls.
[0038] In addition, the edges of the support unit are smooth due to the absence of whisker protrusions that cause uneven sidewalls during etching. This prevents stress concentration and cracking when subjected to mechanical pressure from the strip or nozzle. It also provides physical protection for the ridge waveguide structure at a height higher than the upper electrode, thereby improving product yield. Attached Figure Description
[0039] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.
[0040] Figure 1 This is a schematic flowchart of a method for fabricating a DFB laser in an embodiment of the present invention.
[0041] Figure 2 This is a schematic diagram of a staged etching process in an embodiment of the present invention.
[0042] Figure 3 This is a schematic diagram of the structure of the first intermediate device in an embodiment of the present invention.
[0043] Figure 4 This is a schematic diagram of a support layer structure in an embodiment of the present invention.
[0044] Figure 5 This is a schematic diagram of a third intermediate device in an embodiment of the present invention.
[0045] Explanation of reference numerals in the accompanying drawings: 11, First intermediate device; 12, Second intermediate device; 13, Third intermediate device; 21, First mesa; 22, Second mesa; 23, Sidewall of the mesa; 3, Ridge waveguide structure; 31, Sidewall of the ridge waveguide structure; 41, Second trench; 42, Third trench; 43, First trench; 5, Passivation oxide layer; 6, Support layer; 71, First support unit; 72, Second support unit. Detailed Implementation
[0046] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.
[0047] In order to form support units on the platforms on both sides of the ridge waveguide structure 3 to protect the ridge waveguide structure 3, while avoiding the introduction of uneven defects on the sidewalls 31 of the ridge waveguide structure that would affect the photoelectric performance of the laser, this application introduces a DFB laser and its fabrication method.
[0048] In application, the DFB laser obtained by the aforementioned fabrication method includes a support unit. The support unit includes a support layer 6, which is a silicon nitride layer, and the horizontal height of the silicon nitride layer is higher than a predetermined horizontal height of the upper electrode. Further, the support unit includes a passivation oxide layer 5 and a support layer 6 stacked sequentially. Even further, the support unit includes a first support unit 71 and a second support unit 72. The first support unit 71 is disposed on a first platform 21, and the second support unit 72 is disposed on a second platform 22.
[0049] In practical applications, the support unit is only located in a portion of the platform, with a gap between it and the ridge waveguide structure 3. The distance between the edge of the support unit and the edge of the platform facing the ridge waveguide structure 3 is 5 μm to 20 μm; and the nanoindentation hardness of the support unit is 15 GPa to 25 GPa.
[0050] Example 1: This example introduces a method for fabricating a DFB laser.
[0051] In application, the fabrication method of the DFB laser in this embodiment mainly focuses on the formation process of the support unit.
[0052] In practical applications, after the first intermediate device 11 is epitaxially grown on the substrate and before the electrodes are formed, the fabrication method of this embodiment includes steps SS1 to SS3, as described above. Figure 1 .
[0053] Step SS1: Immerse the first intermediate device 11 in a liquid phase treatment solution to form a passivation oxide layer 5 on the surface of the first intermediate device 11, thereby obtaining the second intermediate device 12.
[0054] In application, the liquid phase treatment solution is a mixed solution of hydrofluoric acid, isopropanol and deionized water.
[0055] In practical applications, before depositing the support layer 6, the first intermediate device 11, after being etched to form the ridge waveguide structure 3, is immersed in a liquid treatment solution composed of hydrofluoric acid, isopropanol, and deionized water. With the wetting assistance of isopropanol, the hydrofluoric acid in the liquid treatment solution can penetrate into the high aspect ratio trenches, chemically oxidizing the exposed semiconductor material surfaces to form a passivation oxide layer 5 with a thickness of 1 nm to 2 nm.
[0056] Step SS2: Deposit a support layer 6 on the second intermediate device 12.
[0057] In application, a support layer 6 is formed by plasma-enhanced chemical vapor deposition, and the support layer 6 is a silicon nitride layer.
[0058] In practical applications, the presence of the passivation oxide layer 5 homogenizes the surface potentials of different semiconductor materials such as the InP cladding layer, contact layer, and etch stop layer. This ensures a more consistent attraction of charged active groups in the plasma, eliminating localized electric field concentrations and suppressing the abnormal preferential growth of silicon nitride at semiconductor material interfaces, thus preventing the formation of whisker-like protrusions. The contact layer can be an InGaAs layer, and the etch stop layer can be an InGaAsP layer.
[0059] Step SS3: Etch the support layer 6 and the passivation oxide layer 5 in stages to form a support unit on the mesa of the second intermediate device 12 to obtain the third intermediate device 13.
[0060] In application, the defined area includes a trench region and a partial mesa region. The trench region includes the top of the ridge waveguide structure 3, the sidewall 31 of the ridge waveguide structure, the sidewall 23 of the mesa, and the bottom of the trench. The partial mesa region includes the edge region on the mesa near the ridge waveguide structure 3, reserving an area for forming the upper electrode. During the staged etching of the support layer 6, the support layer 6 and the passivation oxide layer 5 on the sidewall 31 of the ridge waveguide structure are uniformly etched away. The semiconductor material surface is exposed to the etching plasma at the same time, experiencing consistent plasma exposure duration. This prevents localized depressions caused by preferential over-etching of whisker-like protrusions, ensuring the flatness of the sidewall 31 of the ridge waveguide structure.
[0061] Furthermore, since the liquid phase surface treatment step can eliminate the generation of whisker-like protrusions, the edge of the support unit facing the ridge waveguide structure 3 is flat, and there are no longer structural discontinuities caused by whisker-like protrusions, thus ensuring mechanical strength. When the support unit is subjected to local compressive stress applied by the bar strip or nozzle in the subsequent bar strip separation and testing and sorting processes, it can effectively withstand mechanical loads and is not prone to cracking.
[0062] In practical applications, the nanoindentation hardness of the support unit is 15 GPa to 25 GPa, which is much higher than that of the ridge waveguide structure 3. Furthermore, the horizontal height of the support unit is higher than the preset horizontal height of the upper electrode. During the bar separation process, the bar first contacts the support unit, not the ridge waveguide structure 3. In the testing and sorting process, the nozzle can only contact the support unit, thus preventing external mechanical stress from impacting the ridge waveguide structure 3.
[0063] In actual implementation, refer to Figures 3 to 5 In this embodiment, the first intermediate device 11, the second intermediate device 12, and the third intermediate device 13 each include: a ridge waveguide assembly and a first platform 21 and a second platform 22 located on both sides of the ridge waveguide assembly.
[0064] The ridge waveguide assembly includes one or more ridge waveguide structures 3 arranged in parallel, with a third groove 42 between adjacent ridge waveguide structures 3. A first groove 43 is provided between the first platform 21 and the ridge waveguide assembly; a second groove 41 is provided between the second platform 22 and the ridge waveguide assembly.
[0065] It is worth noting that the trench regions of the first intermediate device 11 and the third intermediate device 13 both expose semiconductor material, specifically the contact layer; the trench regions of the second intermediate device 12 both expose the passivation oxide layer 5. The trench regions include: the top of the ridge waveguide structure 3, the sidewall 31 of the ridge waveguide structure, the sidewall 23 of the mesa, and the bottom of the trench. Further, the sidewall 23 of the mesa comprises the sidewall 31 of the first mesa 21 facing the ridge waveguide structure, and the sidewall 31 of the second mesa 22 facing the ridge waveguide structure.
[0066] The ridge waveguide structure 3 of the first intermediate device 11 and the third intermediate device 13 includes sequentially stacked InP cladding and contact layers. The ridge waveguide structure 3 of the second intermediate device 12 includes sequentially stacked InP cladding, contact layers, and passivation oxide layers 5. Further, the exposed semiconductor materials on the sidewalls 31 and mesa sidewalls 23 of the ridge waveguide structures of the first intermediate device 11 and the third intermediate device 13 are both InP cladding and contact layers; the exposed semiconductor material on the top of the ridge waveguide structures 3 of the first intermediate device 11 and the third intermediate device 13 is both contact layers; and the exposed semiconductor material at the bottom of the trenches of the first intermediate device 11 and the third intermediate device 13 is both etch stop layers. Even further, the exposed materials on the top, sidewalls 31, mesa sidewalls 23, and bottom of the trenches of the ridge waveguide structure 3 of the second intermediate device 12 are all passivation oxide layers 5.
[0067] In some embodiments, the method for forming the first intermediate device 11 includes: sequentially growing a lower confinement layer, a lower waveguide layer, an active layer, an upper waveguide layer, an upper confinement layer, a grating layer, an etch stop layer, an InP cladding layer, and a contact layer on an InP substrate to form an epitaxial wafer. Two or more trenches are etched on the epitaxial wafer using photolithography and dry / wet etching processes to form a ridge waveguide structure 3 and a first mesa 21 and a second mesa 22 located on both sides of the ridge waveguide structure 3, thereby obtaining the first intermediate device 11.
[0068] In some embodiments, after depositing a passivation layer on the third intermediate device 13, an opening is made at the top of the ridge waveguide structure 3 to expose the contact layer, and then an upper electrode layer and a lower electrode layer are formed. Furthermore, the upper electrode layer is electrically connected to the contact layer. Even further, the upper electrode layer covers the trench region and part of the mesa region, and the horizontal height of the upper electrode layer is lower than the horizontal height of the support unit.
[0069] Example 2: Based on Example 1, this example details a method for fabricating a DFB laser.
[0070] In application, the fabrication method of the DFB laser in this embodiment mainly focuses on the formation process of the support unit.
[0071] In practical applications, refer to Figure 1 After the first intermediate device 11 is obtained by epitaxial growth on the substrate and before the electrode is formed, the preparation method of this embodiment includes steps SS1 to SS3.
[0072] Step SS1: Immerse the first intermediate device 11 in a liquid phase treatment solution to form a passivation oxide layer 5 on the surface of the first intermediate device 11, thereby obtaining the second intermediate device 12.
[0073] In application, the liquid phase treatment solution is a mixed solution of hydrofluoric acid, isopropanol, and deionized water. Specifically, the preparation method of the liquid phase treatment solution includes: mixing 0.5 wt% hydrofluoric acid, isopropanol, and deionized water in a volume ratio of 1:1:20 and stirring until homogeneous to obtain the liquid phase treatment solution. The isopropanol used is analytical grade isopropanol.
[0074] In practical applications, the soaking conditions include: a system temperature of 20°C to 25°C; and a soaking time of 90s to 120s.
[0075] In actual implementation, the first intermediate device 11 is immersed in a liquid phase treatment solution and soaked at a constant temperature of 20°C to 25°C for 90s to 120s. Then it is taken out and rinsed with deionized water and dried with nitrogen to obtain a passivation oxide layer 5 with a thickness of 1nm to 2nm. The passivation oxide layer 5 covers the exposed semiconductor material of the first intermediate device 11.
[0076] Step SS2: Deposit a support layer 6 on the second intermediate device 12.
[0077] In application, the support layer 6 is deposited using plasma-enhanced chemical vapor deposition (PECVD), specifically, a support layer 6 with a thickness of 1.5 μm to 2 μm is deposited on the second intermediate device 12 using PECVD. Specifically, the process parameters for PECVD include: radio frequency power of 100 W to 200 W; reaction chamber pressure of 80 Pa to 150 Pa; temperature of the second intermediate device 12 during deposition of 200 °C to 350 °C; and reaction sources including a mixed gas, NH3, and He.
[0078] In practical applications, the gas flow rate of NH3 is 10 sccm to 30 sccm; the gas flow rate of He is 200 sccm to 400 sccm; and the gas flow rate of the mixed gas is 280 sccm to 360 sccm.
[0079] In actual implementation, the mixed gas includes SiH4 and N2, the volume percentage of SiH4 in the mixed gas is 3% to 10%, and the gas flow rate ratio of SiH4 to NH3 in the mixed gas is 1:1 to 1:2.
[0080] Step SS3: Etch the support layer 6 and the passivation oxide layer 5 in stages to form a support unit on the mesa of the second intermediate device 12 to obtain the third intermediate device 13.
[0081] In application, the horizontal height of the support unit is higher than the preset horizontal height of the upper electrode.
[0082] In practical applications, refer to Figure 2 The staged etching includes a first stage and a second stage performed after the first stage.
[0083] The first stage includes: under a first etching condition, using a first etching gas to etch the support layer 6 in the defined region to reduce the thickness of the support layer 6 in the defined region to 80% to 90% of its original thickness. Further, the etching endpoint of the first stage includes: the remaining thickness of the support layer 6 in the defined region being 150 nm to 400 nm.
[0084] The first etching conditions include: an inductively coupled plasma source power of 400W to 600W and a substrate bias power of 100W to 150W; the first etching gas includes argon gas with a flow rate of 50sccm to 80sccm.
[0085] The second stage includes: under the second etching conditions, using a second etching gas to etch the remaining support layer 6 and passivation oxide layer 5 in the defined region. Further, the etching endpoint of the second stage includes: after detecting the characteristic spectral lines of In element, continuing etching for a set time of 10% to 15% to remove all remaining support layers 6 and passivation oxide layers 5 within the defined region, exposing the underlying semiconductor material to obtain the third intermediate device 13.
[0086] The second etching gas comprises CHF3 and O2, with a CHF3 flow rate of 40 sccm and an O2 flow rate of 5 sccm. The second etching conditions include a substrate bias power of 50 W to 80 W. The set time is from the start of etching using the second etching gas until the first detection of the In element characteristic spectral line.
[0087] In actual implementation, the distance between the edge of the support unit and the edge of the platform facing the ridge waveguide structure 3 is 5μm to 20μm; and the nanoindentation hardness of the support unit is 15GPa to 25GPa.
[0088] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.
Claims
1. A method for fabricating a DFB laser, characterized in that, After epitaxial growth of a first intermediate device on a substrate, and before the formation of electrodes; the fabrication method includes: The first intermediate device is immersed in a liquid phase treatment solution to form a passivation oxide layer on the surface of the first intermediate device, thereby obtaining a second intermediate device; wherein the liquid phase treatment solution is a mixed solution of hydrofluoric acid, isopropanol and deionized water. A support layer is deposited on the second intermediate device; The support layer and the passivation oxide layer are etched in stages to define the region, thereby forming a support unit on the mesa of the second intermediate device to obtain a third intermediate device; wherein the horizontal height of the support unit is higher than the preset horizontal height of the upper electrode.
2. The method for fabricating a DFB laser according to claim 1, characterized in that, The staged etching includes a first stage, which includes: Under the first etching conditions, the support layer in the defined region is etched using a first etching gas to reduce the thickness of the support layer in the defined region to 80% to 90% of its original thickness; The first etching conditions include: an inductively coupled plasma source power of 400W to 600W and a substrate bias power of 100W to 150W; the first etching gas includes argon gas with a flow rate of 50sccm to 80sccm; the defined region includes a trench region and a partial mesa region, the trench region including the top of the ridge waveguide structure, the sidewall of the ridge waveguide structure, the sidewall of the mesa, and the bottom of the trench; the partial mesa region includes the edge region on the mesa near the side of the ridge waveguide structure.
3. The method for fabricating a DFB laser according to claim 2, characterized in that, The etching endpoint of the first stage includes: the remaining thickness of the support layer within the defined region is 150 nm to 400 nm.
4. The method for fabricating a DFB laser according to claim 2, characterized in that, The staged etching also includes a second stage performed after the first stage, the second stage comprising: Under the second etching conditions, the remaining support layer and passivation oxide layer in the defined area are etched using the second etching gas. After detecting the characteristic spectral line of In element, etching continues for a set time of 10% to 15% to remove the remaining support layer and passivation oxide layer in the defined area and expose the underlying semiconductor material to obtain the third intermediate device. The second etching gas includes CHF3 and O2, with a CHF3 flow rate of 40 sccm and an O2 flow rate of 5 sccm. The second etching conditions include a substrate bias power of 50 W to 80 W. The set time is from the moment when etching begins using the second etching gas until the moment when the characteristic spectral line of In element is first detected.
5. The method for fabricating a DFB laser according to claim 1, characterized in that, The thickness of the support layer is 1.5 μm to 2 μm, and the deposition method of the support layer is plasma-enhanced chemical vapor deposition (PECVD). The process parameters of the PECVD include: Radio frequency power ranges from 100W to 200W; The reaction chamber pressure is 80 Pa to 150 Pa; The temperature of the second intermediate device during deposition is 200°C to 350°C; The reaction source includes a mixed gas, NH3, and He; wherein the gas flow rate of NH3 is 10 sccm to 30 sccm; the gas flow rate of He is 200 sccm to 400 sccm; the gas flow rate of the mixed gas is 280 sccm to 360 sccm; the mixed gas includes SiH4 and N2, wherein the volume percentage of SiH4 in the mixed gas is 3% to 10%, and the gas flow rate ratio of SiH4 to NH3 in the mixed gas is 1:1 to 1:
2.
6. The method for fabricating a DFB laser according to claim 1, characterized in that, The preparation method of the liquid phase treatment solution includes: 0.5 wt% hydrofluoric acid, isopropanol and deionized water are mixed and stirred evenly in a volume ratio of 1:1:20 to obtain the liquid phase treatment solution.
7. The method for fabricating a DFB laser according to claim 1, characterized in that, The soaking conditions include: a system temperature of 20°C to 25°C; and a soaking time of 90 to 120 seconds. The thickness of the passivation oxide layer is 1 nm to 2 nm.
8. The method for fabricating a DFB laser according to claim 1, characterized in that, The first intermediate device, the second intermediate device, and the third intermediate device all include: A ridge waveguide assembly, comprising one or more ridge waveguide structures arranged in parallel, with a third groove provided between adjacent ridge waveguide structures; A first platform and a second platform are located on both sides of the ridge waveguide assembly. A first groove is provided between the first platform and the ridge waveguide assembly; a second groove is provided between the second platform and the ridge waveguide assembly. In this device, the trench regions of the first and third intermediate devices both expose semiconductor material; the trench regions of the second intermediate device both expose a passivation oxide layer.
9. The method for fabricating a DFB laser according to claim 8, characterized in that, The distance between the edge of the support unit and the edge of the platform facing the ridge waveguide structure is 5 μm to 20 μm; and the nanoindentation hardness of the support unit is 15 GPa to 25 GPa.
10. A DFB laser obtained by the fabrication method of the DFB laser according to any one of claims 1 to 9, characterized in that, Includes support units; The support unit includes a support layer, which is a silicon nitride layer, and the horizontal height of the silicon nitride layer is higher than the preset horizontal height of the upper electrode; The support unit includes: a first support unit and a second support unit; wherein the first support unit is disposed on a first platform and the second support unit is disposed on a second platform.