Method for manufacturing semiconductor laser and semiconductor laser

Abstract

The application discloses a preparation method of a semiconductor laser, comprising the following steps: providing an initial epitaxial structure, including an initial epitaxial layer, a sacrificial layer with a target component ratio, and a mask layer with a window, and partially exposing the sacrificial layer; providing a corrosion solution with a target volume ratio and corroding the initial epitaxial structure, partially corroding the sacrificial layer, partially forming a suspended roof structure of the mask layer, and partially corroding the initial epitaxial layer to form a final mesa; the roof structure has a target roof width, the target component ratio and the target volume ratio are cooperatively configured according to the target roof width, and when the target roof width is in a wide roof range, the target component ratio is configured as a first component ratio; when the target component ratio changes in a range of the first component ratio, a change value of the target roof width is less than or equal to a fluctuation platform value; wet processing is performed for a preset reaction time until the final mesa reaches a preset height; a buried layer is grown on the final mesa; and the target roof width is accurately adjusted.

Description

Technical Field

[0001] This invention relates to the field of semiconductor optoelectronic device manufacturing, and in particular to a method for preparing a semiconductor laser and a semiconductor laser. Background Technology

[0002] Buried heterojunction lasers are widely used in high-speed fiber optic communication, optical interconnects, and photonic integration due to their excellent current-confining and optical field-confining characteristics. Their core structure involves burying the light-emitting active layer from all sides using a wide-bandgap material through secondary epitaxial growth to achieve efficient carrier injection and recombination.

[0003] A typical BH laser fabrication process includes: first, epitaxially growing a multilayer structure containing an active layer and a sacrificial layer on a substrate; then, forming mesas through etching; next, selectively laterally etching the sacrificial layer using a wet chemical etching solution to form a suspended roof structure above the mesas sidewalls; finally, performing secondary epitaxial growth on this structure to complete the embedding process.

[0004] In existing technologies, the dimensions of the eaves structure, especially its lateral width, are difficult to control precisely, flexibly, and stably. The eaves dimensions primarily depend on the control of etching time; inaccurate dimensional control can lead to device performance issues. If the eaves are too narrow, they cannot completely cover the mesa sidewalls, easily generating lattice defects at the subsequent secondary epitaxial interface, becoming non-radiative recombination centers and leakage current channels, resulting in an increase in the laser's threshold current. If the eaves are too wide, excessively rapid lateral etching or morphological deterioration, such as the appearance of voids or polycrystalline structures, can introduce additional leakage paths and parasitic capacitances, affecting device reliability and high-frequency performance. Summary of the Invention

[0005] One of the objectives of this invention is to provide a method for fabricating a semiconductor laser, in order to solve the technical problem that the eaves dimensions are difficult to actively and precisely control in the prior art.

[0006] One of the objectives of this invention is to provide a semiconductor laser.

[0007] To achieve one of the above-mentioned objectives, one embodiment of the present invention provides a method for fabricating a semiconductor laser, comprising the steps of:

[0008] An initial epitaxial structure is provided, comprising an initial epitaxial layer, a sacrificial layer, and a mask layer in sequence; the sacrificial layer has a preset target composition ratio, and the mask layer has a window, with a portion of the sacrificial layer exposed through the window; An etching solution is provided and the initial epitaxial structure is wet-treated. The etching solution has a preset target volume ratio, and at least a portion of the initial epitaxial structure is etched by the etching solution. Among them, a portion of the sacrificial layer is etched, causing a portion of the mask layer to form a suspended eaves structure, and a portion of the initial epitaxial layer is etched to form a final platform. The eaves structure has a target eaves width, the target component ratio and the target volume ratio are configured collaboratively based on the target eaves width, and when the target eaves width is within the wide eaves range, the target component ratio is configured to any value within the first component ratio range; when the target component ratio changes within the first component ratio range, the change in the target eaves width is less than or equal to a fluctuation plateau value. The wet treatment continues for a preset reaction time until the final tabletop reaches a preset height. A buried layer is grown, which is formed on the final platform.

[0009] As a further improvement to one embodiment of the present invention, Providing an initial epitaxial structure includes the steps of: creating a window in the mask layer, removing a portion of the sacrificial layer and a portion of the initial epitaxial layer through the window; wherein, the portion of the initial epitaxial layer is removed to form an initial mesa, and the sidewalls of the sacrificial layer are exposed on the side of the initial mesa facing the mask layer; The wet processing includes the step of immersing the initial epitaxial structure in the etching solution.

[0010] As a further improvement to one embodiment of the present invention, an epitaxial structure is provided comprising: an initial epitaxial layer comprising an InP layer, and a sacrificial layer located between the InP layer and a mask layer, the sacrificial layer comprising InP... 1-x Ga x As y P 1-y Where x is the mole fraction of Ga and y is the mole fraction of As, and x and y have a preset ratio, which is configured such that the lattice constant of the sacrificial layer matches the lattice constant of InP.

[0011] As a further improvement of one embodiment of the present invention, the sacrificial layer includes In 1-x Ga x As y P 1-y Where x is the mole fraction of Ga, y is the mole fraction of As, and the target component ratio is configured as y; When the target eaves width is within the narrow eaves range, y is configured as any value within the range of the third component ratio; when y varies within the range of the third component ratio, the target eaves width and the third component ratio are positively correlated. The target eaves width is within the transition eaves range, and y is configured as any value within the range of the second component ratio; when y changes within the range of the second component ratio, the target eaves width and the second component ratio are positively correlated. Among them, the wide eaves range, the transition eaves range, and the narrow eaves range are continuous and decrease sequentially, and y in the first component ratio, the second component ratio, and the third component ratio decreases sequentially.

[0012] As a further improvement of one embodiment of the present invention, the wide eaves range from 0.3μm to 0.48μm, the y in the first component ratio is greater than or equal to 0.4 and less than or equal to 1.0, and the fluctuation platform value is less than or equal to 0.05μm; the transition eaves range from 0.25μm to 0.3μm, the y in the second component ratio is greater than 0.1 and less than 0.4; the narrow eaves range is less than 0.25μm, and the y in the third component ratio is less than or equal to 0.1.

[0013] As a further improvement of one embodiment of the present invention, the corrosive solution includes HBr, H2O2 and H2O; When the wide eaves range is within a first width range, the corrosive solution is configured at a first volume ratio, where the first volume ratio is the base concentration; When the wide eaves range is within the second width range, the corrosive solution is configured with a second volume ratio; when the second width range is greater than the first width range, the second volume ratio is configured to increase the proportion of HBr in the corrosive solution based on the first volume ratio. When the wide eaves range is within the third width range, the corrosive solution is configured with a third volume ratio; when the third width range is smaller than the first width range, the third volume ratio is configured to increase the proportion of H2O2 in the corrosive solution based on the first volume ratio.

[0014] As a further improvement of one embodiment of the present invention, the first width ranges from 0.38μm to 0.43μm, the second width ranges from 0.43μm to 0.48μm, and the third width ranges from 0.3μm to 0.38μm. And / or, the method for preparing the semiconductor laser includes the steps of: controlling the reaction temperature of the wet treatment to 0~5°C and controlling the use of the etching solution within half an hour after preparation, so as to suppress the generation of bromine gas when the etching solution and the sacrificial layer react.

[0015] As a further improvement of one embodiment of the present invention, when the narrow eaves range is within the fourth width range, the fourth width range is smaller than the third width range, and the corrosive solution is configured with a second volume ratio; When the narrow eaves range is within the fifth width range, and the fifth width range is smaller than the fourth width range, the corrosive solution is configured with a first volume ratio, a second volume ratio, or a third volume ratio. And / or, when the target eaves width is within the transition eaves range, the corrosive solution is configured with a first volume ratio, a second volume ratio, or a third volume ratio.

[0016] As a further improvement of one embodiment of the present invention, the fourth width ranges from 0.2μm to 0.25μm, and the fifth width ranges from less than or equal to 0.2μm.

[0017] To achieve one of the above-mentioned objectives, one embodiment of the present invention provides a semiconductor laser, which is prepared according to the semiconductor laser preparation method of any of the above technical solutions, wherein the semiconductor laser includes the initial epitaxial layer and the buried layer.

[0018] Compared with existing technologies, this invention provides a method for fabricating a semiconductor laser, which synergistically configures the sacrificial layer to a preset target component ratio and the etching solution to a preset target volume ratio, thereby achieving precise control over the dimensions of the semiconductor laser's roof structure. When the target roof width is within a wide roof range, the target component ratio is configured to any value within a first component ratio range, and when the target component ratio changes within the first component ratio range, the change in the target roof width is less than or equal to a fluctuation plateau value, demonstrating insensitivity to changes in the first component ratio. This reduces the requirements for the growth precision of the sacrificial layer and improves batch-to-batch and intra-wafer uniformity. The buried layer is used to restrict current laterally during semiconductor laser operation to prevent current leakage. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a semiconductor laser according to one embodiment of the present invention.

[0020] Figure 2 This is a schematic diagram of the initial epitaxial structure in one embodiment of the present invention.

[0021] Figure 3 This is a schematic diagram of an initial epitaxial structure provided in one embodiment of the present invention, wherein, Figure 3 The diagrams 3A, 3B, 3C, 3D, 3E, and 3F in the diagrams specifically illustrate the steps involved in creating the window opening and the initial countertop.

[0022] Figure 4 This is a schematic diagram of a roof structure fabricated using a semiconductor laser according to one embodiment of the present invention.

[0023] Figure 5 This is a graph showing the target eaves width under the influence of the component ratio of the sacrificial layer and the volume ratio of the corrosive solution in one embodiment of the present invention. Detailed Implementation

[0024] The present invention will now be described in detail with reference to the specific embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, methodological, or functional modifications made by those skilled in the art based on these embodiments are included within the scope of protection of the present invention.

[0025] It should be noted that the term "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Furthermore, the terms "first," "second," "third," "fourth," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] The terms “connection,” “connected to,” or any other variations are intended to encompass various relative positions where a connection exists, including both direct and indirect connections. A direct connection can be formed through a pneumatic conduit, while an indirect connection can be formed through devices such as valves or sensors, through pneumatic components such as brake control units, or through any other medium such as air.

[0027] Please see Figure 1 This is a schematic diagram of the structure of a semiconductor laser provided in an embodiment of the present invention, which is prepared using the semiconductor laser 1 preparation method.

[0028] The method for fabricating semiconductor laser 1 includes the following steps: An initial epitaxial structure 10 is provided, comprising an initial epitaxial layer 100, a sacrificial layer 17, and a mask layer 18 in sequence; the sacrificial layer 17 has a preset target composition ratio, and the mask layer 18 has a window 180, with a portion of the sacrificial layer 17 exposed to the window 180. An etching solution is provided and the initial epitaxial structure 10 is wet-treated. The etching solution has a preset target volume ratio, and at least a portion of the initial epitaxial structure 10 is etched by the etching solution. Among them, a portion of the sacrificial layer 17 is etched, so that a portion of the mask layer 18 forms a suspended eaves structure 20, and a portion of the initial epitaxial layer 100 is etched to form a final platform 102. The eaves structure 20 has a target eaves width d. The target component ratio and the target volume ratio are configured collaboratively based on the target eaves width. When the target eaves width is within the wide eaves range, the target component ratio is configured to any value within the first component ratio range. When the target component ratio changes within the first component ratio range, the change in the target eaves width d is less than or equal to a fluctuation platform value. The wet treatment continues for a preset reaction time until the final tabletop 102 reaches a preset height w. A buried layer 30 is grown on the final mesa 102; the buried layer 30 is used to limit the current in the lateral direction when the semiconductor laser 1 is operating, to prevent current leakage.

[0029] The above describes how the sacrificial layer 17 is configured with a preset target component ratio and the etching solution is configured with a preset target volume ratio to achieve precise control of the size of the semiconductor laser roof structure 20. When the target roof width d is within the wide roof range, the target component ratio is configured to any value within the first component ratio range. When the target component ratio changes within the first component ratio range, the change in the target roof width d is less than or equal to a fluctuation plateau value, which shows that it is not sensitive to the change in the first component ratio, reduces the requirements for the growth accuracy of the sacrificial layer 17, and improves batch-to-batch and intra-wafer uniformity.

[0030] It should be noted that the target eaves width d in this application refers to the lateral width value of the eaves structure that is predetermined and expected to be formed in the final structure, based on the semiconductor laser design requirements, such as the expected threshold current, slope efficiency, or leakage current suppression degree.

[0031] In order to obtain the desired target eaves width d, the target component ratio of the sacrificial layer and the target volume ratio of the corrosion solution are pre-configured. In this application, under the preset corrosion reaction conditions, it is assumed that the actual eaves width is basically consistent with the target eaves width. In other words, the deviation between the actual eaves width and the target eaves width is within an acceptable error range, for example, no more than ±0.01μm. Therefore, it can be understood as basically consistent.

[0032] Similarly, under the preset corrosion reaction conditions, the height of the final platform formed is basically the same as the preset height. In other words, the deviation between the height of the final platform formed and the preset height is within an acceptable error range, for example, no more than ±0.01μm.

[0033] The component ratio of the sacrificial layer 17 and the volume ratio of the etch solution are two independent parameters that can be flexibly adjusted. After obtaining the required target eaves width based on the device performance of the semiconductor laser 1, the component ratio of the sacrificial layer and the volume ratio of the etch solution are configured in a coordinated manner according to the target eaves width. This enables precise and active control of the eaves size, eliminating the need to redesign the epitaxial structure based on different target eaves widths. This improves process flexibility and tolerance, shortens the process cycle, and reduces process costs.

[0034] In one embodiment, providing the initial epitaxial structure 10 includes the steps of: creating a window 180 in the mask layer 18, and removing a portion of the sacrificial layer 17 and a portion of the initial epitaxial layer 100 through the window 180; wherein, the portion of the initial epitaxial layer 100 is removed to form an initial mesa 101, and the sidewalls of the sacrificial layer 17 are exposed on the side of the initial mesa 101 facing the mask layer 18. The wet process includes the following steps: immersing the initial epitaxial structure 10 into an etching solution; thus, the etching solution enters the interior of the initial epitaxial structure 10 and etches the sacrificial layer 17 in the transverse direction and the initial epitaxial layer 100 in the longitudinal direction; the longitudinal direction is the thickness direction of the initial epitaxial structure 10, and the transverse direction is the direction parallel to the surface of the initial epitaxial structure 10, and the transverse and longitudinal directions are perpendicular to each other.

[0035] Combination Figure 2 , Figure 3 As shown in 3A, an initial epitaxial structure 10 is grown. Specifically, a substrate 11 is provided, and an n-type InP layer 12, an active layer 13, a p-type InP layer 14, a grating layer 15, an InP layer 16, a sacrificial layer 17, and a mask layer 18 are sequentially grown on the substrate 11. In a specific embodiment, the mask layer 18 may be a silicon dioxide layer with a thickness of 300 nm. It is understood that the newly grown initial epitaxial structure 10 does not yet have a window 180 and an initial mesa 101, and the newly grown initial epitaxial structure 10 cannot be directly subjected to wet processing.

[0036] Next, combined Figure 3 In steps 3B and 3C, photoresist 300 is coated on the surface of the mask layer 18 of the newly grown initial epitaxial structure 10. A photoresist mask 310 is prepared, and the photoresist 300 is exposed and developed, so that part of the surface of the mask layer 18 is exposed.

[0037] Combination Figure 3 As shown in 3D and 3E, the exposed surface of the mask layer 18 is dry-etched to form a window 180, and then the photoresist 300 is removed. At this time, part of the surface of the sacrificial layer 17 is exposed to the window 180.

[0038] Combination Figure 3 As shown in 3F, dry etching is performed on the sacrificial layer 17 and the initial epitaxial layer 100 through a window 180. In a specific embodiment, etching can be performed for another 300 nm along the thickness direction. In this way, at least part of the sacrificial layer 17 and the initial epitaxial layer 100 are removed, thereby forming an initial mesa 101 where the initial epitaxial layer 100 is removed. The sidewalls of the sacrificial layer 17 are exposed above the initial mesa 101, which facilitates the etching solution to etch the sacrificial layer 17 laterally and continue to etch the initial epitaxial layer 100 longitudinally.

[0039] It is understood that in other embodiments, the sacrificial layer 17 and the initial epitaxial layer 100 can be considered to have jointly formed an initial mesa 101 after removal. The initial mesa 101 includes the sidewalls of the sacrificial layer 17 and the sidewalls of the initial epitaxial layer 100. The initial mesa 101 is exposed to the opening 180, and thus, the sidewalls of the sacrificial layer 17 are also exposed to the opening 180. All of the above is sufficient as long as the exposure of the sidewalls of the sacrificial layer 17 after etching allows the etching solution to enter.

[0040] The corrosion reaction continues for a preset reaction time until a preset corrosion depth is reached. The corrosion depth usually refers to the degree of corrosion of the initial epitaxial layer 100 along the longitudinal direction. It can be understood that the preset corrosion depth along the longitudinal direction represents the preset height w of the final mesa. In other words, the preset corrosion depth value is equal to the preset height value of the final mesa. The preset height value of the final mesa is controlled by controlling the preset reaction time.

[0041] Specifically, based on the semiconductor laser design, the target eaves width and the preset height of the final platform are determined. After coordinating the target component ratio of the sacrificial layer 17 and the target volume ratio of the etching solution according to the target eaves width, the preset reaction time is confirmed based on the volume ratio of the etching solution and the preset height. When the wet treatment process continues for the preset reaction time, it is equivalent to the etching reaching the preset height value of the final platform.

[0042] In one specific embodiment, combined with Figure 1 As shown, the n-type InP layer 12 is at least an n-type doped semiconductor layer, and electrons in the n-type InP layer 12 are injected into the active layer 13 for recombination with holes injected into the p-type doped semiconductor layer to emit light.

[0043] The active layer 13 is the core region for stimulated emission of the laser. It typically employs a multi-quantum-well structure, which includes periodically alternating well layers and barrier layers. Electrons from the n-type semiconductor layer and holes from the p-type semiconductor layer are injected into the active layer 13. The electrons and holes are confined in the well layers and recombine radiatively to form a laser.

[0044] The p-type semiconductor layer includes a p-type InP layer 14 adjacent to the active layer 13, a grating layer 15, and an InP layer 16 located on the grating layer 15. The InP layer 16 is also p-type doped and is formed as a grating mask layer.

[0045] During the wet processing, the etching solution acts simultaneously on the initial epitaxial structure 10 in both the transverse and longitudinal directions. The sacrificial layer 17 is etched and hollowed out in the transverse direction, leaving part of the mask layer 18 suspended to form the eaves structure 20. In the longitudinal direction, the InP layer 16, grating layer 15, p-type InP layer 14, active layer 13, and n-type InP layer 12 below the sacrificial layer 17 are also partially etched, thus forming the final platform 102. The preset height extends at least to the n-type InP layer 12 in the longitudinal direction. By controlling the etching reaction time, the preset height w is controlled. In a specific embodiment, the preset height w is controlled to reach a value between 0.7-1.5 μm, at which point the etching reaction stops, and the eaves structure 20 is obtained with the target eaves width d.

[0046] After the final mesa 102 is fabricated, a secondary buried layer 30 is grown on the final mesa 102. The height of the final mesa 102 is equivalent to the height of the buried layer 30. The etched initial epitaxial layer 100 is buried inside the buried layer 30. The buried layer 30 laterally confines the charge carriers, so that the charge carriers recombine and emit light only within the active layer 13 defined by the buried layer 30.

[0047] The method for fabricating a semiconductor laser also includes the step of: after growing the buried layer 30, removing the mask layer 18 and the remaining sacrificial layer 17 to facilitate subsequent processes, such as fabricating an ohmic electrode layer.

[0048] The method for preparing a semiconductor laser includes the following steps: controlling the reaction temperature of the wet treatment at 0-5℃ and controlling the use of the etching solution within half an hour after preparation, so as to suppress the generation of bromine gas when the etching solution reacts with the sacrificial layer 17, ensuring the repeatability of the etching process and the controllability of the target eaves width. At this time, the etching solution is a mixed solution of HBr, H2O2 and H2O.

[0049] The initial epitaxial layer 100 includes an InP layer 16, and the sacrificial layer 17 is located between the InP layer 16 and the mask layer 18. The sacrificial layer 17 includes InP layers. 1-x Ga x As y P 1-y Where x is the mole fraction of Ga and y is the mole fraction of As, x and y have a preset ratio, which is configured such that the lattice constant of the sacrificial layer 17 matches the lattice constant of InP, thereby reducing the lattice mismatch between the sacrificial layer 17 and the InP layer 16.

[0050] Combination Figure 2As shown, the sacrificial layer 17 is a quaternary compound formed above the InP layer 16. If the lattice constant of the sacrificial layer 17 is mismatched with that of the InP layer 16, it will affect the crystal quality. Matching the lattice constant of the sacrificial layer 17 with that of InP means that the lattice constant of the sacrificial layer 17 is approximately close to that of InP. When the thickness of the sacrificial layer 17 is relatively thin, for example, when the thickness of the sacrificial layer 17 is 0.03 micrometers, a small mismatch of less than 0.5% is generally allowed.

[0051] Specifically, the lattice constant of InP is approximately 5.8687 Å. By configuring the ratio of x to y, the lattice constant of the sacrificial layer 17 is made close to 5.8687 Å, for example, configured so that x is approximately equal to 0.47y.

[0052] Sacrificial layer 17 includes In 1-x Ga x As y P 1-y Let x be the mole fraction of Ga and y be the mole fraction of As, and let y be the target component ratio. x and y have a preset ratio. Adjusting the y value in the sacrificial layer 17 under the condition that x and y have a preset ratio is equivalent to adjusting the component ratio of the sacrificial layer 17.

[0053] When the target eaves width d is within the narrow eaves range, y is configured to any value within the range of the third component ratio; when y varies within the range of the third component ratio, the target eaves width and the third component ratio are positively correlated. When the target eaves width is within the transition eaves range, y is configured to any value within the range of the second component ratio; when y varies within the range of the second component ratio, the target eaves width and the second component ratio are positively correlated. Among them, the wide eaves range, the transition eaves range, and the narrow eaves range are continuous and decrease in sequence, and y decreases in sequence in the first component ratio, the second component ratio, and the third component ratio.

[0054] Thus, different component ratios of the sacrificial layer 17 can be configured to obtain different target eave widths d. In actual processes, the target component ratio of the sacrificial layer 17 can be determined first based on the eave range of the required target eave width d.

[0055] More specifically, the wide eaves range from 0.3μm to 0.48μm, with y in the first component ratio being greater than or equal to 0.4 and less than or equal to 1.0, and the fluctuation platform value being less than or equal to 0.05μm; the transition eaves range from 0.25μm to 0.3μm, with y in the second component ratio being greater than 0.1 and less than 0.4; and the narrow eaves range is less than 0.25μm, with y in the third component ratio being less than or equal to 0.1, thus achieving continuous adjustment of the target eaves width d within a width range of less than or equal to 0.48μm.

[0056] In this application, the fluctuation plateau value indicates the fluctuation of the actual measured value of the target eaves width in the experimental measurement data. The fluctuation plateau value can be understood as the fluctuation amplitude of the target eaves width when the volume ratio of the corrosive solution is fixed and the first component ratio takes different values. A fluctuation plateau value less than or equal to 0.05 μm is equivalent to a fluctuation amplitude less than or equal to 0.05 μm. In other words, the target eaves width d can remain stable within a plateau width range under different values ​​of the first component ratio.

[0057] It should be noted that in theoretical chemical reactions, the theoretical fluctuation plateau value is 0. Specifically, under ideal conditions, for example, if the initial epitaxial structure 10 has ideal structural parameters and the corrosive solution has an ideal fixed volume ratio, the target eaves width d does not change with the change of y when y takes different values ​​of the first component ratio. In other words, theoretically, the target eaves width remains constant when y changes with the first component ratio.

[0058] However, in actual experiments, the process parameters of the epitaxial layer affect its structural parameters, the concentration error of the etching solution, and the actual measurement error all lead to changes in the target eaves width, causing the target eaves width to fluctuate within a certain range. It is understandable that the change in the target eaves width caused by such measurement error or other errors is small. Therefore, the fluctuation range of the target eaves width is less than or equal to 0.05 μm.

[0059] The chemical reaction mechanism of this application will be described in detail below using an embodiment in which the corrosive solution includes HBr, H2O2, and H2O: The corrosion solution and the sacrificial layer 17 undergo a chemical reaction. First, the corrosion solution and the sacrificial layer 17 undergo an oxidation reaction. H2O2 is a strong oxidizing agent, which oxidizes the In, Ga, As and P atoms on the surface of the sacrificial layer 17 into corresponding oxides, such as In2O3, Ga2O3, As2O3 and P2O5. These oxides are usually insoluble in water and will form an oxide film on the surface of the sacrificial layer 17.

[0060] Next, HBr, an acidic complexing agent, reacts with the aforementioned oxides to form water-soluble bromide complexes, such as InBr3, GaBr3, and AsBr3, thereby peeling off the oxide film and exposing a fresh surface for further oxidation. Simultaneously, the acidic environment provided by HBr also promotes the dissolution of the oxides. The arsenic and phosphorus byproducts from the reaction enter the aqueous solution as arsenic acid (H3AsO4) and phosphoric acid (H3PO4).

[0061] Understandably, in the above reactions, As atoms are relatively reactive and readily oxidized by H₂O₂ to form As₂O₃, or dissolved in acid to form arsenic acid. The reaction rate of As₂O₃ with HBr to form AsBr₃ is also very fast. Therefore, when the sacrificial layer 17 has a high As atom component, i.e., when the y component is high, both the oxidation and dissolution chemical steps are relatively rapid, and the surface of the sacrificial layer 17 remains fresh for oxidation and dissolution.

[0062] As the sacrificial layer 17 reacts rapidly, the oxidant H2O2 is consumed as soon as it diffuses to the surface of the sacrificial layer 17. Therefore, the overall corrosion rate depends on the rate at which H2O2 diffuses to the surface of the sacrificial layer 17. Under diffusion control, as long as the surface reactivity of the sacrificial layer 17 is strong enough, i.e., y exceeds a threshold, such as 0.4, the corrosion rate is mainly determined by the diffusion flux and is independent of the specific As content on the surface. Therefore, theoretically, once y exceeds a threshold, such as 0.4, the target eaves width can remain constant.

[0063] Under conditions of a fixed longitudinal corrosion height w and a fixed volume ratio of the corrosion solution, for example, w is 0.7 μm, and the corrosion solution has a base concentration, once diffusion control is implemented, the reaction time is fixed, the transverse corrosion rate is essentially constant, the transverse corrosion path length is essentially stable, and the actual measured target eaves width can be stabilized within the platform width range. This target eaves width includes errors caused by measurement errors or other factors.

[0064] Table 1

[0065] Referring to Table 1, the y-value was controlled as the only variable to obtain different target eaves widths d, the longitudinal corrosion depth w was controlled to be 0.7 μm, the corrosion solution HBr:H2O2:H2O=5:1:80, and other process parameters were kept consistent.

[0066] It is understood that in the specific embodiment, the basic concentration of the corrosion solution is HBr:H2O2:H2O=5:1:80. In other embodiments, the basic concentration can also be adjusted according to different application scenarios.

[0067] Experimental data show that, with other parameters remaining constant, the target eaves width d remains stable within the platform width range for different values ​​of y greater than or equal to 0.4, specifically between 0.40 μm and 0.42 μm in the experimental data. In other words, when y takes any value greater than or equal to 0.4, the change in the target eaves width d is less than or equal to 0.02 μm. In the specific embodiment, the fluctuation platform value is as low as 0.02 μm, and the target eaves width d remains stable within the platform width range of 0.40 μm to 0.42 μm. This demonstrates that the actually measured target eaves width d is not sensitive to changes in composition. The change in the target eaves width d is mainly due to measurement errors, errors in epitaxial structure parameters, or errors in the concentration of the corrosive solution.

[0068] It is understandable that the platform width range refers to the sub-range within which the target eaves width d falls under a fixed volume ratio and the first component ratio. The wide eaves range, on the other hand, includes the union of multiple platform width ranges corresponding to different volume ratios of the same corrosive solution. The platform width range and the wide eaves range are not entirely equivalent; the platform width range is a sub-range within the wide eaves range at a certain fixed volume ratio.

[0069] The target eaves width d is insensitive to changes in composition; more specifically, referring to... Figure 5 As shown in the graph, when the corrosive solution has any volume ratio, the change in the target eaves width is less than or equal to 0.05 μm when y varies within the range of the first component ratio, and the change in the target eaves width is less than or equal to 0.1 when y varies within the range of the first component ratio.

[0070] Understandable, Figure 5 The middle platform area corresponds to the wide eaves range, and the width variation of the target eaves width d is very small, not sensitive to changes in the component ratio y. The variation is mainly due to process errors. The transition area corresponds to the transition width range, and the low window area corresponds to the narrow eaves range. The width variation values ​​are all large, and the target eaves width d also shows a basic increasing trend under the condition that y increases.

[0071] In the above reaction, as the value of y gradually decreases, it is equivalent to the P content becoming higher, the oxidation reaction becoming slower, and the oxidation mainly produces P2O5 and In2O3. The dissolution rate of P2O5 and In2O3 in HBr solution is relatively slow, and they easily form a dense and continuous protective oxide layer. This In / P rich protective oxide layer hinders the contact between H2O2 and the fresh surface below the sacrificial layer 17.

[0072] Due to the presence of the protective oxide layer, H2O2 must penetrate this layer to continue the reaction. However, this penetration process is slow. At this point, the chemical reactions on the surface of the sacrificial layer 17, such as the formation and dissolution of the oxide layer, become crucial in determining the corrosion rate; that is, the corrosion reaction enters reaction-controlled mode. Under reaction control, the corrosion rate is sensitive to changes in the component ratio. The smaller the y value (more P), the denser the protective layer, and the slower the corrosion rate. Conversely, the larger the y value (more As), the faster the corrosion rate.

[0073] Due to the slow reaction rate, the protective oxide layer restricts the longitudinal and lateral diffusion of the oxidant. Within the preset reaction time (when the longitudinal eaves height reaches 0.7 μm), lateral corrosion cannot widen. In other words, the target eaves width is limited to a narrow range, typically less than 0.25 μm. Referring to Table 1, experiments show that when y is 0.02, the target eaves width d can be as low as 0.10 μm.

[0074] It can be seen that when the sacrificial layer 17 is configured with the first component ratio y greater than or equal to 0.4, the obtained target eaves width corresponds to a stable range of platform width (wide eaves range), which shows that it is not sensitive to changes in composition. Specifically, it is between 0.3μm and 0.48μm, and can be finely adjusted by adjusting the volume ratio of the corrosion solution as described below.

[0075] When the sacrificial layer 17 is configured with a third component ratio y less than or equal to 0.1, the obtained target eaves width corresponds to a narrow eaves range. With a smaller y value, lateral corrosion is difficult to widen, specifically between 0.08 μm and 0.25 μm. This can be finely adjusted by changing the volume ratio of the corrosion solution as described below. Under the same volume ratio of the corrosion solution, the target eaves width is positively correlated with the third component ratio; the target eaves width increases with increasing y.

[0076] Sacrificial layer 17 is configured with the second component ratio, where y is greater than 0.1 and less than 0.4. When the target eaves width is within the corresponding transition eaves range, specifically between 0.25 and 0.3 μm, it can be fine-tuned by adjusting the volume ratio of the etching solution as described below. Under the same volume ratio of the etching solution, the target eaves width is positively correlated with the second component ratio; the target eaves width increases with increasing y. Besides the difference in width range, the transition eaves range and the narrow eaves range also differ in that, under the third component ratio condition, the narrow eaves range is more sensitive to changes in the component ratio.

[0077] In one specific embodiment, when the wide eaves range is within a first width range, the corrosive solution is configured with a first volume ratio C1, where the first volume ratio C1 is the base concentration. When the width of the eaves is within the second width range, the corrosion solution is configured with a second volume ratio C2; when the second width range is greater than the first width range, the second volume ratio C2 is configured by increasing the proportion of HBr in the corrosion solution based on the first volume ratio C1. When the width of the eaves is within the third width range, the corrosion solution is configured with a third volume ratio C3; when the third width range is smaller than the first width range, the third volume ratio C3 is configured by increasing the proportion of H2O2 in the corrosion solution based on the first volume ratio C1.

[0078] Based on the basic width framework with a relatively wide target eaves width d, the corresponding sacrificial layer 17 is first configured as the first component ratio. Then, by finely adjusting the volume ratio of the corrosion solution, the target eaves width d can be continuously and precisely adjusted within the wide eaves range, thereby expanding the control range of the target eaves width d and increasing the control accuracy of the target eaves width d.

[0079] Specifically, the first width range is 0.38μm to 0.43μm, the second width range is 0.43μm to 0.48μm, and the third width range is 0.3μm to 0.38μm. In this way, within the wide eaves range, it is further subdivided into three width ranges to achieve more precise width control.

[0080] In one specific embodiment, when the narrow eaves range is within the fourth width range, the fourth width range is smaller than the third width range, and the corrosion solution is configured with a second volume ratio C2; when the narrow eaves range is within the fifth width range, the fifth width range is smaller than the fourth width range, and the corrosion solution is configured with a first volume ratio C1, a second volume ratio C2, or a third volume ratio C3.

[0081] Based on the basic width framework with a relatively narrow target eaves width d, the corresponding sacrificial layer is first configured as the third component ratio. Then, by finely adjusting the volume ratio of the corrosion solution, the target eaves width d can be continuously and precisely adjusted within the narrow eaves range, thereby expanding the control range of the target eaves width d and increasing the control accuracy of the target eaves width d.

[0082] Specifically, the fourth width range is between 0.2μm and 0.25μm, and the fifth width range is less than or equal to 0.2μm. Thus, within the narrow eaves range, it is further subdivided into two width ranges to achieve more precise width control.

[0083] Table 2

[0084] Referring to Table 2, the fourth volume ratio C4 is a highly diluted corrosive solution, meaning it has a high H2O content. Under the fourth volume ratio condition, y is greater than or equal to 0.3, and the target eaves width is stable within the platform width range. This method is rarely used in actual processes.

[0085] Under the first volume ratio condition, when y is greater than or equal to 0.4, the target eaves width is stable within the platform width range, while when y is less than or equal to 0.1, the narrow eaves range is less than 0.2 μm; under the second volume ratio condition, when y is greater than or equal to 0.3, the target eaves width is stable within the platform width range, while when y is less than or equal to 0.1, the narrow eaves range is less than 0.25 μm; under the third volume ratio condition, when y is greater than or equal to 0.6, the target eaves width is stable within the platform width range, while when y is less than or equal to 0.1, the narrow eaves range is less than 0.15 μm.

[0086] Theoretically, under different volume ratios, y needs to take different ranges of values ​​to ensure that the target eaves width remains stable within the corresponding platform width range. In practical applications, this is combined with... Figure 5 As shown, when y is greater than or equal to 0.4, the target eaves width can still be kept relatively stable under the third volume ratio condition. Therefore, in practical applications, regardless of the volume ratio of the corrosive solution, as long as the desired target eaves width falls within the platform width range, a sacrificial layer 17 with y greater than or equal to 0.4 is configured.

[0087] Under the second volume ratio condition, the range of platform width and the range of narrow eaves are larger than those under the first volume ratio condition, while under the third volume ratio condition, the range of platform width and the range of narrow eaves are smaller than those under the first volume ratio condition. It is understandable that increasing the HBr content is beneficial for increasing the eaves width, while increasing the H2O2 content is beneficial for reducing the eaves width.

[0088] Referring to Table 3 below, the composition ratio of sacrificial layer 17 or the volume ratio of the corrosive solution needs to be controlled as the sole variable in the experiment. For example, by controlling the longitudinal corrosion depth w to 0.7 μm, the corrosive solution to a first volume ratio, and keeping other process parameters consistent, the y value can be adjusted to obtain different target eaves widths. Alternatively, by controlling the longitudinal corrosion depth w to 0.7 μm, the composition ratio of sacrificial layer 17 to a fixed value, and keeping other process parameters consistent, the volume ratio of the corrosive solution can be adjusted to obtain different target eaves widths.

[0089] In the specific experimental data, the first volume ratio C1 of the corrosive solution is HBr:H2O2:H2O=5:1:80, the second volume ratio C2 is based on the first volume ratio C1 with an increased HBr content, and the third volume ratio C3 is based on the first volume ratio with an increased H2O2 content.

[0090] Table 3

[0091] It is known that, for a target eaves width greater than 0.3 μm, preferably, the component ratio y of the sacrificial layer 17 is greater than or equal to 0.4. When y is greater than or equal to 0.4, the eaves width enters the plateau region, becoming less sensitive to component changes and making it easier to ensure accuracy. For example, if a target eaves width of 0.35 μm is required, then configuring y to be greater than or equal to 0.4 is sufficient, without needing to control y to be between 0.4 and 0.5. Then, configuring the etching solution as the third volume ratio, with the synergistic configuration of the first component ratio and the third volume ratio, the target eaves width can be stably maintained within the plateau width range, such as 0.34 μm to 0.35 μm, resulting in high accuracy and low process cost.

[0092] For example, to obtain a target eaves width of 0.42 μm, y is configured to be greater than or equal to 0.4, and the etching solution is configured as the first volume ratio. Under the synergistic configuration of the first component ratio and the first volume ratio, the target eaves width can be stabilized within the platform width range, such as 0.41 μm-0.42 μm, with high accuracy and low process cost.

[0093] For example, to obtain a target eaves width of 0.48 μm, y is configured to be greater than or equal to 0.4, and the etching solution is configured as the second volume ratio. Under the synergistic configuration of the first component ratio and the second volume ratio, the target eaves width can be stabilized within the platform width range, such as 0.47 μm-0.48 μm, with high accuracy and low process cost.

[0094] In the above, when the sacrificial layer 17 is configured with the first component ratio, and the corrosion solution is configured with the first volume ratio, the fluctuation of the target eaves width is basically stable at 0.01 μm. In other words, the fluctuation plateau value is as low as 0.01 μm.

[0095] While a target eave width greater than 0.3 μm can be achieved with a y value between 0.2 and 0.3, this method is relatively sensitive to composition, leading to decreased accuracy. For example, to obtain a target eave width of 0.35 μm, y needs to be accurately configured to around 0.2, increasing the process complexity. Furthermore, the etching solution needs to be configured as the second volume ratio. Deviations in the y composition can cause deviations in the final target eave width, making it difficult to accurately obtain a target eave width of around 0.35 μm.

[0096] In other embodiments, when the desired target eaves width falls between 0.25 μm and 0.3 μm, it can also be adjusted by configuring the sacrificial layer 17 to a second component ratio and configuring the corrosion solution to a first volume ratio, a second volume ratio, or a third volume ratio.

[0097] When the target eave width is less than 0.25 μm, preferably, the composition ratio y of the sacrificial layer 17 is less than or equal to 0.1, which facilitates process control and makes it easier to obtain a narrow eave structure. Due to reaction limitations, even if the target eave width is sensitive to composition, lateral corrosion is difficult to expand under the condition that y is less than or equal to 0.1, making it difficult to obtain a wide eave.

[0098] In summary, the composition ratio of the sacrificial layer 17 determines the basic framework of the eaves structure 20, while the volume ratio of the etched solution is finely modulated within the basic framework. The composition ratio of the sacrificial layer 17 and the volume ratio of the etched solution work together to cover the continuous adjustment of the target eaves width from 0.08μm to 0.48μm, meeting the needs of conventional devices and ultra-low leakage current devices.

[0099] Table 4

[0100] As shown in Table 4, when applied to the actual preparation method, when the target eaves width d is about 0.4 μm, the first volume ratio of the etching solution is C1, and the sacrificial layer 17 is configured as the first component ratio; when the target eaves width d is about 0.45 μm, the second volume ratio of the etching solution is configured, and the sacrificial layer 17 is configured as the first component ratio; when the target eaves width d is about 0.35 μm, the third volume ratio of the etching solution is configured, and the sacrificial layer 17 is configured as the first component ratio.

[0101] Under the condition that other parameters are the same, increasing the HBr content is beneficial to increasing the eaves width, while increasing the H2O2 content is beneficial to reducing the eaves width.

[0102] With the sacrificial layer 17 configured as the first component ratio, the target eaves width increases with the increase of the y-value. The volume ratio of the etching solution can be flexibly configured according to the actual y-value. For example, if the y-value is relatively small (0.02) and a target eaves structure of about 0.15 μm is required, the etching solution can be configured with either the first or second volume ratio. Similarly, if the y-value is relatively large (0.08) and a target eaves structure of about 0.15 μm is required, the etching solution can also be configured with either the first or second volume ratio.

[0103] When the target eaves width d is around 0.25 μm, it is preferable to configure the sacrificial layer 17 with the second component ratio and the corrosion solution with the first volume ratio.

[0104] This application also protects a semiconductor laser 1, which is fabricated using the semiconductor laser fabrication method according to any of the above-mentioned technical solutions. The semiconductor laser 1 includes an initial epitaxial structure 10 and a buried layer 30. The buried layer 30 prevents current leakage and improves the recombination efficiency of electrons and holes.

[0105] Combination Figure 1 As shown, the semiconductor laser 1 sequentially includes a substrate 11, an n-type InP layer 12, an active layer 13, a p-type semiconductor layer and a buried layer 30. The p-type semiconductor layer sequentially includes a p-type InP layer 14, a grating layer 15 and an InP layer 16. It is understood that in the final product, the sacrificial layer 17 and the mask layer 18 are preferably removed.

[0106] The beneficial effects of this invention are as follows: After obtaining the required target eaves width d based on the device performance of the semiconductor laser, the component ratio of the sacrificial layer 17 and the volume ratio of the etching solution are coordinated according to the target eaves width d. This enables precise and active control of the eaves size, eliminating the need to redesign the epitaxial structure based on different target eaves widths d, thereby improving process flexibility and tolerance, shortening the process cycle, and reducing process costs. When the target eaves width d is within a wide eaves range, the target component ratio is configured to any value within the first component ratio range. Furthermore, when the target component ratio changes within the first component ratio range, the change in the target eaves width d is less than or equal to a fluctuation plateau value, indicating insensitivity to changes in the first component ratio. This reduces the requirements for the growth accuracy of the sacrificial layer and improves batch-to-batch and intra-wafer uniformity.

[0107] This can be formed by referring to any of the technical solutions provided above, and will not be elaborated here.

[0108] It should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0109] The detailed descriptions listed above are merely specific descriptions of feasible embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for fabricating a semiconductor laser, characterized in that, Including the following steps: An initial epitaxial structure is provided, comprising an initial epitaxial layer, a sacrificial layer, and a mask layer in sequence; the sacrificial layer has a preset target composition ratio, and the mask layer has a window, with a portion of the sacrificial layer exposed through the window; An etching solution is provided and the initial epitaxial structure is wet-treated. The etching solution has a preset target volume ratio, and at least a portion of the initial epitaxial structure is etched by the etching solution. Among them, a portion of the sacrificial layer is etched, causing a portion of the mask layer to form a suspended eaves structure, and a portion of the initial epitaxial layer is etched to form a final platform. The eaves structure has a target eaves width, the target component ratio and the target volume ratio are configured collaboratively based on the target eaves width, and when the target eaves width is within the wide eaves range, the target component ratio is configured to any value within the first component ratio range; when the target component ratio changes within the first component ratio range, the change in the target eaves width is less than or equal to a fluctuation plateau value. The wet processing continues for a preset reaction time until the final platform reaches a preset height along the thickness direction of the initial epitaxial structure. A buried layer is grown, the buried layer being formed on the final platform; The corrosive solution includes HBr, H2O2, and H2O; The initial epitaxial layer includes an InP layer, and the sacrificial layer is located between the InP layer and the mask layer. The sacrificial layer includes InP. 1-x Ga x As y P 1-y Where x is the mole fraction of Ga and y is the mole fraction of As, x and y have a preset ratio, the preset ratio is configured such that the lattice constant of the sacrificial layer matches the lattice constant of InP, the target component ratio is configured as y; the fluctuation plateau value is the fluctuation amplitude of the target eaves width when the corrosion solution has a fixed volume ratio and y takes different values ​​in the first component ratio. The wide eaves range from 0.3 μm to 0.48 μm, the first component ratio y is greater than or equal to 0.4 and less than or equal to 1.0, and the fluctuation platform value is less than or equal to 0.05 μm.

2. The method for fabricating a semiconductor laser according to claim 1, characterized in that, Providing an initial epitaxial structure includes the steps of: creating a window in the mask layer, removing a portion of the sacrificial layer and a portion of the initial epitaxial layer through the window; wherein, the portion of the initial epitaxial layer is removed to form an initial mesa, and the sidewalls of the sacrificial layer are exposed on the side of the initial mesa facing the mask layer; The wet processing includes the step of immersing the initial epitaxial structure in the etching solution.

3. The method for fabricating a semiconductor laser according to claim 2, characterized in that, Before creating the window in the mask layer, the steps include: providing a substrate, and sequentially growing an n-type InP layer, an active layer, a p-type InP layer, a grating layer, an InP layer, a sacrificial layer, and a mask layer on the substrate; the initial epitaxial layer includes the substrate, the n-type InP layer, the active layer, the p-type InP layer, the grating layer, and the InP layer.

4. The method for fabricating a semiconductor laser according to claim 1, characterized in that, When the wide eaves range is within a first width range, the corrosive solution is configured at a first volume ratio, where the first volume ratio is the base concentration; When the wide eaves range is within the second width range, the corrosive solution is configured with a second volume ratio; when the second width range is greater than the first width range, the second volume ratio is configured to increase the proportion of HBr in the corrosive solution based on the first volume ratio. When the wide eaves range is within the third width range, the corrosive solution is configured with a third volume ratio; when the third width range is smaller than the first width range, the third volume ratio is configured to increase the proportion of H2O2 in the corrosive solution based on the first volume ratio.

5. The method for fabricating a semiconductor laser according to claim 4, characterized in that, The first width ranges from 0.38μm to 0.43μm, the second width ranges from 0.43μm to 0.48μm, and the third width ranges from 0.3μm to 0.38μm.

6. The method for fabricating a semiconductor laser according to claim 1, characterized in that, The method for preparing the semiconductor laser includes the steps of: controlling the reaction temperature of the wet treatment to 0~5℃ and controlling the use of the etching solution within half an hour after preparation, so as to suppress the generation of bromine gas when the etching solution and the sacrificial layer react.

7. The method for fabricating a semiconductor laser according to claim 1, characterized in that, The process includes, after growing the buried layer, the step of removing the mask layer and the remaining sacrificial layer.

8. The method for fabricating a semiconductor laser according to claim 1, characterized in that, The preset height is 0.7-1.5μm.

9. A semiconductor laser, fabricated using the method for fabricating a semiconductor laser according to any one of claims 1-8, characterized in that, The semiconductor laser includes the initial epitaxial layer and the buried layer.

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