Semiconductor laser and method for manufacturing the same

Abstract

The present invention provides a method for manufacturing a semiconductor laser and a semiconductor laser obtained by using the manufacturing method. The manufacturing method forms an intrinsic InP covering layer with a thickness not exceeding 5 nanometers on a grating at a reaction temperature of 540 degrees Celsius or more and not higher than 600 degrees Celsius and a reaction pressure of 3 kilopascals to 7 kilopascals, and controls the growth rate of the intrinsic InP covering layer to be 10 nanometers / minute to 15 nanometers / minute, and forms a P-type low-doped InP covering layer and a P-type high-doped InP covering layer in sequence at a growth rate of 10 nanometers / minute to 15 nanometers / minute on the intrinsic InP covering layer at a reaction temperature of 590 degrees Celsius or more and not higher than 600 degrees Celsius and the aforementioned reaction pressure, thereby reducing or avoiding the decomposition deformation of the grating and the growth defects of particle accumulation.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices, and in particular to a semiconductor laser and a manufacturing method thereof. Background Art

[0002] Distributed Feedback (DFB) lasers have built-in gratings, on which various functional layers including grating cover layer, barrier gradient layer and ohmic contact layer are formed. After the current is injected from the top surface of the DFB, the electrons and holes in the active region recombine and radiate photons of corresponding energy. These photons will be Bragg reflected by each grating on the surface of the active layer, realizing dynamic single longitudinal mode operation.

[0003] In the process of forming a grating cladding layer on an InGaAsP grating in the prior art, a higher process temperature helps to reduce growth defects and improve the quality of the grating cladding layer. However, high temperature easily causes the precipitation of P in the InGaAsP grating, which makes the InGaAsP grating easy to decompose and deform, thereby affecting the light output efficiency and light output power of the laser. If a lower process temperature is used, the grating cladding layer is prone to significant growth defects, such as concentrated and widely distributed byproduct particle aggregation, which will affect the function of the DFB. Summary of the invention

[0004] The object of the present invention is to provide a method for manufacturing a semiconductor laser and a semiconductor laser obtained by using the manufacturing method, which can continuously grow a grating cover layer on an InGaAsP grating at a faster growth rate at a temperature not higher than 600 degrees Celsius, thereby reducing or avoiding the decomposition deformation of the InGaAsP grating and the growth defects of particle accumulation.

[0005] To achieve the above object, the method for manufacturing a semiconductor laser provided by the present invention comprises the following steps:

[0006] S0: providing a reaction chamber and an original device located in the reaction chamber, wherein the original device comprises an n-type InP substrate, and a lower light field limiting layer, an active layer, an upper light field limiting layer and a grating which are sequentially arranged from bottom to top on the n-type InP substrate, wherein the grating is an InGaAsP grating;

[0007] S1: controlling the reaction temperature in the reaction chamber to be above 540 degrees Celsius and not higher than 600 degrees Celsius and the reaction pressure to be 3 kPa to 7 kPa, providing a phosphorus source and an indium source into the reaction chamber to form an intrinsic InP capping layer having a thickness not exceeding 5 nanometers on the grating at a growth rate of 10 nanometers / minute to 15 nanometers / minute;

[0008] S2: controlling the reaction temperature and the reaction pressure in the reaction chamber to be above 590 degrees Celsius and not higher than 600 degrees Celsius, providing the phosphorus source, the indium source and the zinc source into the reaction chamber, so as to sequentially form a P-type low-doped InP covering layer and a P-type highly-doped InP covering layer on the intrinsic InP covering layer at a growth rate of 10 nanometers / minute to 15 nanometers / minute and bury the grating;

[0009] S3: sequentially forming a P-type doped barrier gradient layer and a P-type doped ohmic contact layer on the P-type highly doped InP covering layer, or sequentially forming an etching stop layer, the P-type doped barrier gradient layer and the P-type doped ohmic contact layer on the P-type highly doped InP covering layer.

[0010] The manufacturing method of the semiconductor laser of the present invention has the beneficial effect that: through the step S1, at a reaction temperature of more than 540 degrees Celsius and not more than 600 degrees Celsius and a reaction pressure of 3 kilopascals to 7 kilopascals in the reaction chamber, an intrinsic InP covering layer with a thickness not exceeding 5 nanometers is formed on the grating, and the growth rate of the intrinsic InP covering layer is controlled to be 10 nanometers / minute to 15 nanometers / minute, and through the step S2, the reaction temperature in the reaction chamber is controlled to be more than 590 degrees Celsius and not more than 600 degrees Celsius and the aforementioned reaction pressure, a P-type low-doped InP covering layer and a P-type high-doped InP covering layer are sequentially formed on the intrinsic InP covering layer at a growth rate of 10 nanometers / minute to 15 nanometers / minute, thereby reducing or avoiding the decomposition deformation of the InGaAsP grating and the growth defects of particle accumulation.

[0011] Optionally, during the execution of step S1, step S2 and step S3, the original device is controlled to rotate around the axis of the grating.

[0012] Optionally, the original device is controlled to rotate at a speed of 400 rpm to 700 rpm.

[0013] Optionally, before executing step S1, the temperature in the reaction chamber is controlled to be a processing temperature higher than 100 degrees Celsius and lower than 500 degrees Celsius, and the pressure in the reaction chamber is the reaction pressure, and the phosphorus source is provided in the reaction chamber to perform a water and oxygen removal treatment on the original device for not less than 6 minutes.

[0014] Optionally, after the deoxygenation step is completed, the temperature in the reaction chamber is controlled to rise to no more than 540 degrees Celsius at a rate of 0.9 degrees Celsius / second to 2.5 degrees Celsius / second, the indium source is supplemented into the reaction chamber, and then the temperature in the reaction chamber is controlled to rise to the reaction temperature, and then step S1 is executed.

[0015] Optionally, the treatment temperature is above 450 degrees Celsius and below 500 degrees Celsius, and the time for the water removal and oxygen removal treatment is 6-10 minutes.

[0016] Optionally, in step S1, the step of providing a phosphorus source and an indium source into the reaction chamber includes controlling the flow rates of the phosphorus source and the indium source to be 1000 sccm to 1800 sccm and 1000 sccm to 2000 sccm, respectively, and the V / III ratio of the reaction mixture composed of the phosphorus source and the indium source is greater than 150 and less than 300.

[0017] Optionally, in step S2, the thickness of the P-type low-doped InP covering layer does not exceed 5 nanometers, and the sum of the thicknesses of the intrinsic InP covering layer, the P-type low-doped InP covering layer and the P-type high-doped InP covering layer is 10-40 nanometers thicker than the thickness of the grating.

[0018] Optionally, in step S2, the step of providing the phosphorus source, the indium source and the zinc source into the reaction chamber comprises:

[0019] S21: controlling the flow rates of the phosphorus source, the indium source and the zinc source to be 1000 sccm to 1800 sccm, 1000 sccm to 1500 sccm and 30 sccm to 90 sccm respectively, and the V / III ratio of the reaction mixture composed of the phosphorus source and the indium source is greater than 150 and less than 300 until the P-type low-doped InP capping layer is formed;

[0020] S22: Control the flow rates of the phosphorus source and the indium source to remain unchanged, and control the flow rate of the zinc source to be 30 sccm to 120 sccm until the P-type highly doped InP capping layer is formed.

[0021] Optionally, the step S21 further includes controlling the flow rate of the zinc source to increase at a rate of 30 sccm to 90 sccm, and the step S22 further includes controlling the flow rate of the zinc source to increase at a rate of 30 sccm to 120 sccm.

[0022] Optionally, in step S3, the P-type doped barrier gradient layer includes a P-type doped InP layer and a P-type doped InGaAsP layer which are sequentially layered.

[0023] Optionally, the doping concentration of the P-type doped InP layer is 2×10 17 / cubic centimeter ~ 1×10 18 / cubic centimeter, with a thickness of 70 nanometers to 2 micrometers, and the doping concentration of the P-type doped InGaAsP layer is 5×10 17 / cubic centimeter ~ 2.5×10 18 / cubic centimeter, thickness is 20 nanometers to 45 nanometers.

[0024] Optionally, in step S3, the step of forming the barrier gradient layer and the ohmic contact layer includes:

[0025] S31: forming an intrinsic InP layer, an intrinsic InGaAsP layer and an intrinsic ohmic contact layer;

[0026] S32: after providing a protective medium into the reaction chamber and controlling the temperature in the reaction chamber to be 500 degrees Celsius to 540 degrees Celsius and the pressure to be 10 kPa to 40 kPa, providing the zinc source with a flow rate of 90 sccm to 540 sccm to the top surface of the intrinsic ohmic contact layer and controlling the depth of zinc diffusion to not exceed the sum of the thicknesses of the intrinsic InP layer, the intrinsic InGaAsP layer and the intrinsic ohmic contact layer;

[0027] S33: after controlling the flow rate of the protective medium to be higher than the flow rate of the zinc source and the temperature in the reaction chamber to be 150 degrees Celsius to 400 degrees Celsius, switching the protective medium to an inert medium and providing it into the reaction chamber, and controlling the flow rate of the inert medium to be equivalent to the flow rate of the zinc source;

[0028] S34: Rapidly adjust the temperature in the reaction chamber to below 150 degrees Celsius.

[0029] Optionally, in step S34, the temperature in the reaction chamber is controlled to rise to 420 degrees Celsius to 450 degrees Celsius at a rate of 0.9 to 2.5 degrees Celsius per second and maintained for 5 to 10 minutes, and then the temperature in the reaction chamber is controlled to drop to below 150 degrees Celsius at a rate of 0.7 to 1.5 degrees Celsius per second.

[0030] Optionally, the protective medium is an arsenic source or hydrogen, the arsenic source contains arsenic-containing gas, and the inert medium is at least one of nitrogen, helium, neon, argon, krypton, xenon, and radon.

[0031] Optionally, the phosphorus source includes a phosphorus-containing gas, the indium source includes an indium-containing metal organic compound, and the zinc source includes a zinc-containing metal organic compound.

[0032] Optionally, the reaction chamber is provided with a carrying device for carrying the original device, and an injection device, and the injection device is arranged opposite to the carrying device, so that the substance provided into the reaction chamber by the injection device flows along the axial direction of the reaction chamber toward the grating.

[0033] The semiconductor laser of the present invention is manufactured by the aforementioned semiconductor laser manufacturing method, and the semiconductor laser comprises an n-type InP substrate, and a lower light field limiting layer, an active layer, an upper light field limiting layer, a grating, an intrinsic InP covering layer, a P-type low-doped InP covering layer and a P-type high-doped InP covering layer which are sequentially arranged from bottom to top on the n-type InP substrate; the grating is an InGaAsP grating; and the height of the intrinsic InP covering layer does not exceed 5 nanometers. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic structural diagram of a semiconductor laser according to a first embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of the structure of the reaction chamber of the MOCVD equipment according to the second embodiment of the present invention;

[0036] Figure 3 This is a flow chart of a process of forming an intrinsic InP capping layer, a P-type low-doped InP capping layer and a P-type highly-doped InP capping layer on a grating of an original device in a second embodiment of the present invention;

[0037] Figure 4 This is a transmission electron microscope photograph of the top of the device obtained after step S21 is completed in Example 2 of the present invention;

[0038] Figure 5 This is a transmission electron microscope photograph of the top of the device obtained after step S21 is completed in comparative example 1 of the present invention;

[0039] Figure 6 This is a transmission electron microscope photograph of the top of the device obtained after step S21 is completed in comparative example 2 of the present invention;

[0040] Figure 7 This is a flow chart of forming a P-type doped first barrier gradient layer, a P-type doped second barrier gradient layer and a P-type doped ohmic contact layer by a zinc diffusion method in accordance with the third embodiment of the present invention;

[0041] Figure 8 This is a corresponding relationship diagram between the relative emission intensity and the main wavelength obtained by performing an electroluminescence test on the obtained semiconductor laser in Example 3 of the present invention. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be understood by people with general skills in the field to which the present invention belongs. "Including" and similar words used in this article mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0043] The embodiment of the present invention provides a semiconductor laser and a manufacturing method thereof, which can continuously grow a grating cover layer on an InGaAsP grating at a faster growth rate at a temperature not higher than 600 degrees Celsius, thereby reducing or avoiding decomposition deformation of the InGaAsP grating and growth defects of particle accumulation.

[0044] Embodiment 1

[0045] This embodiment provides a semiconductor laser, such as Figure 1 As shown, it includes: an original device consisting of an n-type InP substrate 11, and a lower optical field limiting layer 12, an active layer 13, an upper optical field limiting layer 14 and a grating 15 sequentially arranged from bottom to top on the n-type InP substrate 11, an intrinsic InP capping layer 21 with a height not exceeding 5 nanometers and covering the exposed surface of the grating 15, a P-type low-doped InP capping layer 22 covering the top surface of the intrinsic InP capping layer 21, and a P-type highly-doped InP capping layer 23 covering the top surface of the P-type low-doped InP capping layer 22 and embedding the grating 15. The intrinsic InP capping layer 21, the P-type low-doped InP capping layer 22 and the P-type highly-doped InP capping layer 23 constitute the grating capping layer 2. The P-type low-doped InP covering layer 22 and the P-type highly-doped InP covering layer 23 constitute a P-type doped InP covering layer. The P-type doped InP covering layer changes the valence band top in the material and provides a small amount of electrons. These electrons will occupy the space above the original valence band top to form a new valence band top. At the same time, P-type doping can also lower the energy level of the conduction band, making it easier for electrons to jump from the valence band to the conduction band, thereby forming an electric current.

[0046] In this embodiment, the size of the n-type InP substrate 11 is 3 inches. In some embodiments, the size of the n-type InP substrate 11 can be adaptively adjusted according to the design requirements of the semiconductor laser, for example, it can be 6 inches, 8 inches, etc.

[0047] In this embodiment, the grating 15 is an InGaAsP grating. The lower optical field limiting layer 12 is composed of an InP buffer layer and an InAlGaAs layer stacked from bottom to top, with thicknesses of 400 nanometers and 80 nanometers respectively; the active layer 13 is an InAlGaAs layer with a thickness of 5 nanometers; the upper optical field limiting layer 14 is an InP etch stop layer with a thickness of 30 nanometers. The grating 15 covers the top surface of the InP etch stop layer. In some embodiments, the InP etch stop layer is composed of three InP etch stop layers with thicknesses of 3 nanometers, 7 nanometers and 20 nanometers respectively.

[0048] In this embodiment, the manufacturing methods of the lower light field limiting layer 12, the active layer 13, the upper light field limiting layer 14 and the grating 15 are conventional technical means of those skilled in the art and will not be elaborated herein.

[0049] In this embodiment, the height of the grating 15 is 40 nanometers and the period is 220 nanometers. In some embodiments, the height and period of the grating 15 can be adaptively adjusted according to the design requirements of the semiconductor laser.

[0050] In some embodiments, the sum of the heights of the intrinsic InP cover layer 21, the P-type low-doped InP cover layer 22, and the P-type high-doped InP cover layer 23, that is, the height of the grating cover layer 2 is 10-40 nanometers higher than the height of the grating 15. If the height of the grating cover layer 2 is too low, the effect of the grating cannot be fully utilized, and the light output power is reduced. If it is too high, the effect of DFB dynamic single longitudinal mode frequency selection cannot be fully realized, resulting in the light generated by carrier recombination being scattered along the grating cover layer 2 outside the grating 15, and the light output power will also be reduced.

[0051] In this embodiment, the thickness of the grating cover layer 2 is 80 nanometers.

[0052] In some embodiments, the height of the intrinsic InP covering layer 21 does not exceed 5 nanometers. Controlling the thickness of the intrinsic InP covering layer 21 to be no more than 5 nanometers can reconstruct the surface state of the grating 15 material and improve the crystal quality. If the thickness of this layer is too thin, it is impossible to effectively cover the top of the grating 15, which is not conducive to the subsequent deposition of high-quality functional films on the grating 15, such as epitaxial growth of a grating covering layer on the grating 15. If the thickness of this layer is too thick, the contact resistance of the semiconductor laser will be increased, affecting its electrical performance. In addition, since the P-type low-doped InP covering layer 22 is obtained at a growth temperature not exceeding 600 degrees Celsius, if the P-type low-doped InP covering layer 22 is grown directly on the grating 15 by an epitaxial process, it is easy to form significant impurity particles (for example, when the dopant contains zinc, zinc phosphide particles will be formed) due to the low growth temperature, causing defects.

[0053] In this embodiment, the thickness of the intrinsic InP capping layer 21 is 5 nanometers. In some embodiments, the thickness of the intrinsic InP capping layer 21 is 2 to 5 nanometers.

[0054] In some embodiments, the height of the P-type low-doped InP capping layer 22 does not exceed 5 nanometers. Since the P-type low-doped InP capping layer 22 is obtained at a growth temperature not exceeding 600 degrees Celsius, the P-type low-doped InP capping layer grown at a reaction temperature not exceeding 600 degrees Celsius and a reaction pressure of 3 kPa to 7 kPa is prone to forming impurity particles (for example, when the dopant is a zinc source, zinc phosphide particles are formed) to cause defects, and reasonable control of the height of the P-type low-doped InP capping layer 22 is conducive to reducing the impact of impurity particle defects during the epitaxial process.

[0055] In this embodiment, the thickness of the P-type low-doped InP capping layer 22 is 5 nanometers. In some embodiments, the thickness of the P-type low-doped InP capping layer 22 is 2 to 5 nanometers.

[0056] In some embodiments, the doping concentration of the P-type low-doped InP capping layer 22 is 5×10 17 / cubic centimeter ~ 2×10 18 / cubic centimeter. If the doping concentration is too low, the resistance of the layer will be too large and it will be unfavorable for the formation of current; if the doping concentration is too high, on the one hand, it is not easy to achieve saturated doping in the process, and too high a doping concentration will also easily deteriorate the quality of the epitaxial crystal of the layer.

[0057] In this embodiment, the doping concentration of the P-type low-doped InP capping layer 22 is 7×10 17 / cubic centimeter, and the doping concentration gradually increases from the bottom surface to the top surface.

[0058] In some embodiments, the doping concentration of the P-type highly doped InP capping layer 23 is 1×10 18 / cubic centimeter ~ 2×10 18 / cubic centimeter. If the doping concentration is too low, the resistance of the layer will be too large and it will be unfavorable for the formation of current; if the doping concentration is too high, on the one hand, it is not easy to achieve saturated doping in the process, and too high a doping concentration will also easily deteriorate the quality of the epitaxial crystal of the layer.

[0059] In this embodiment, the doping concentration of the P-type highly doped InP capping layer 23 is 1×10 18 / cubic centimeter, and the doping concentration gradually increases from the bottom surface to the top surface.

[0060] The doping concentration variation trend of the P-type low-doped InP covering layer 22 and the doping concentration variation trend of the P-type highly-doped InP covering layer 23 can be adaptively adjusted according to the process requirements of the semiconductor laser. In some embodiments, the doping concentration of the P-type highly-doped InP covering layer 23 decreases from its bottom surface to the top surface. In some embodiments, the doping concentration of the P-type doped InP layer composed of the P-type low-doped InP covering layer 22 and the P-type highly-doped InP covering layer 23 is a uniform concentration.

[0061] In this embodiment, refer to Figure 1 The semiconductor laser shown also includes an etching stop layer 3, a barrier gradient layer 4 composed of a first barrier gradient layer 41 and a second barrier gradient layer 42, and an ohmic contact layer 5, which are sequentially layered from the top surface of the P-type highly doped InP cap layer 23. If a wet etching process is required for subsequent device processing, the etching stop layer 3 is provided. The etching stop layer 3 is an InGaAsP layer. The first barrier gradient layer 41 is a P-type doped InP layer, the second barrier gradient layer 42 is a P-type doped first InGaAsP layer, and the ohmic contact layer 5 is a P-type doped second InGaAsP layer. The ohmic contact layer 5 is a P-type doped InGaAsP layer. The barrier gradient layer 4 is set to be a P-type doped InP layer and a P-type doped first InGaAsP layer stacked in sequence, and the doping concentration of the ohmic contact layer 5 is higher than the doping concentration of the first barrier gradient layer 41, and also higher than the doping concentration of the second barrier gradient layer 42, so that the barrier changes smoothly during the change from the P-type highly doped InP cap layer 23 to the ohmic contact layer 5, which is beneficial to improving the device bandwidth. In some embodiments, the first barrier gradient layer 41 can also be used as a waveguide layer to make the electric field strength change smoothly from the active layer to the contact layer.

[0062] In some embodiments, the doping concentration of the first barrier gradient layer 41 is 2×10 17 / cubic centimeter ~ 1×10 18 / cubic centimeter. The doping concentration of the second barrier gradient layer 41 is 5×10 17 / cubic centimeter ~ 2.5×10 18 / cubic centimeter. The doping concentration of the ohmic contact layer 5 is 1.5×10 19 / cubic centimeter ~ 3×10 19 / cubic centimeter.

[0063] In this embodiment, the doping concentration of the first barrier gradient layer 41 is 7×10 17 / cubic centimeter. The doping concentration of the second barrier gradient layer 41 is 2×10 18 / cubic centimeter. The doping concentration of the ohmic contact layer 5 is 2.5×1019 / cubic centimeter.

[0064] The thickness and material of the etching stop layer 3 can be adaptively adjusted according to the requirements of the subsequent wet process. In some embodiments, the thickness of the etching stop layer 3 is 15 nanometers to 30 nanometers. In this embodiment, the thickness of the etching stop layer 3 is 20 nanometers.

[0065] In some embodiments, if a wet etching process is not involved subsequently, the semiconductor laser may not contain the corrosion stop layer 3, but instead a barrier gradient layer 4 consisting of a first barrier gradient layer 41 and a second barrier gradient layer 42 and an ohmic contact layer 5 are sequentially layered starting from the top surface of the P-type highly doped InP cap layer 23.

[0066] In some embodiments, the ohmic contact layer 5 is a P-type doped InGaAs layer.

[0067] In some embodiments, the thickness of the first barrier gradient layer 41 is 70 nanometers to 2 micrometers. If the thickness is too low, an electric field of sufficient strength cannot be generated to effectively recombine carriers, and if the thickness is too high, the carrier recombination path is too long, affecting the carrier recombination efficiency.

[0068] In some embodiments, the thickness of the second barrier gradient layer 42 is 20 nm to 45 nm. If the thickness is too low, an electric field of sufficient intensity cannot be generated to effectively recombine carriers, and if the thickness is too high, the carrier recombination path is increased, which has an adverse effect on factors such as the device's optical output power and bandwidth.

[0069] The function of the ohmic contact layer 5 is to facilitate the input and output of current, and its thickness and doping concentration can be adaptively adjusted according to the use requirements of the device. In some embodiments, the thickness of the ohmic contact layer 5 is 50 nanometers to 200 nanometers.

[0070] In this embodiment, the thickness of the first barrier gradient layer 41 is 1600 nanometers, the thickness of the second barrier gradient layer 42 is 45 nanometers, and the thickness of the ohmic contact layer 5 is 50 nanometers.

[0071] Embodiment 2

[0072] The reaction chamber used in this embodiment is a MOCVD equipment reaction chamber. This embodiment provides a method for sequentially epitaxially growing the intrinsic InP capping layer, the P-type low-doped InP capping layer and the P-type highly-doped InP capping layer of the first embodiment on the original device of the first embodiment.

[0073] The cross section of the MOCVD device of this embodiment is generally a circular or quasi-circular structure, or may be a rectangular structure or other structures known to those skilled in the art, which will not be described in detail here. Figure 2The MOCVD equipment reaction chamber shown in the figure includes an injection device 61 located at the top, and the injection device 61 and the carrier device 62 are arranged opposite to each other along the axial direction of the reaction chamber, so that the material provided by the injection device into the reaction chamber flows toward the grating along the axial direction of the reaction chamber. Figure 2 The injection device 61 is shown to be located above the carrier device 62. The top surface of the carrier device 62 is provided with a sheet groove (not shown in the figure), and the sheet groove (not shown in the figure) contains the original device (not shown in the figure) of Example 1. The injection device 61 provides a process medium (such as a phosphorus source, a zinc source, an indium source, etc. as a reaction medium, or other medium for auxiliary purging or carrying) to the top surface of the carrier device 62 according to the process requirements to sequentially grow the intrinsic InP capping layer, the P-type low-doped InP capping layer and the P-type high-doped InP capping layer. Figure 2 The bottom heating device 64 of the reaction chamber of the MOCVD equipment shown is arranged below the carrier 62, and provides heat to the carrier 62 to transfer heat to the original device (not shown in the figure) to achieve the reaction temperature required by the process.

[0074] In this embodiment, the injection device 61 is a gas injection device, and the process medium provided to the reaction chamber is a gaseous medium. It should be noted that the process medium provided by the injection device 61, such as a reaction medium, an auxiliary medium, etc., can be in a gaseous state or a liquid state, and can be adaptively adjusted according to different growth process requirements.

[0075] In some embodiments, the phosphorus source is a phosphorus-containing gas, such as phosphine PH 3。

[0076] In some embodiments, the indium source includes an indium-containing metal organic compound, such as an indium alkyl compound. In some embodiments, the indium alkyl compound may be trimethylindium TMIn.

[0077] In some embodiments, the zinc source comprises a zinc-containing metal organic compound, such as a zinc alkyl compound. In some embodiments, the zinc alkyl compound may be diethyl zinc DEZn.

[0078] In this embodiment, the carrier 62 is driven to rotate by the rotating device 63 during the process to facilitate the uniform mixing of the reaction medium above the original device (not shown in the figure) and to facilitate the uniformity of film formation. Figure 2 The axis of the reaction chamber shown rotates.

[0079] In some embodiments, in order to further ensure that the reaction medium reaches the required temperature above the original device so that the process proceeds smoothly, a side wall heating device may be provided along the circumference of the side wall of the reaction chamber, so as to reduce or even avoid pre-reaction of the reaction medium before reaching the original device, while ensuring that the reaction medium reaches the required temperature above the original device so that the process proceeds smoothly.

[0080] The MOCVD equipment of this embodiment is also provided with a vacuum system connected to the reaction chamber outside the reaction chamber to adjust the pressure in the reaction chamber according to the process requirements. In addition, an exhaust device is also provided at the bottom of the reaction chamber to exhaust the tail gas from the reaction chamber during the process to ensure the pressure in the reaction chamber.

[0081] The semiconductor laser manufacturing method of this embodiment refers to Figure 3 ,include:

[0082] S1: controlling the reaction temperature in the reaction chamber to be above 540 degrees Celsius and not higher than 600 degrees Celsius and the reaction pressure to be 3 kilopascals to 7 kilopascals, providing a phosphorus source and an indium source into the reaction chamber, thereby forming an intrinsic InP capping layer having a thickness not exceeding 5 nanometers on the grating at a growth rate of 10 nanometers / minute to 15 nanometers / minute;

[0083] S2: Control the reaction temperature and the reaction pressure in the reaction chamber to be above 590 degrees Celsius and not higher than 600 degrees Celsius, and provide the phosphorus source, the indium source and the zinc source into the reaction chamber, so as to sequentially form a P-type low-doped InP covering layer and a P-type highly-doped InP covering layer on the intrinsic InP covering layer at a growth rate of 10 nanometers / minute to 15 nanometers / minute and bury the grating.

[0084] Step S1 and step S2 are described in detail below.

[0085] In the step S1 of the present embodiment, the bottom heating device 64 is controlled to make the reaction temperature at 550 degrees Celsius, and the pressure in the reaction chamber is controlled at 5 kPa by the vacuum system. The carrier device is controlled to drive the original device to rotate around the axis of the reaction chamber at 700 rpm, and a phosphorus source with a flow rate of 1400 sccm and an indium source with a flow rate of 1500 sccm are injected into the reaction chamber through the injection device 61 to form an intrinsic InP covering layer with a thickness of no more than 5 nanometers on the grating of the original device to cover the exposed surface of the grating, and the growth rate of the intrinsic InP covering layer is controlled to be 10 nanometers / minute to 15 nanometers / minute until the intrinsic InP covering layer reaches the thickness required by the process. Specifically, the phosphorus source provided into the reaction chamber by the injection device 61 uses hydrogen as a carrier gas and contains the reaction gas phosphine PH3, and the indium source uses hydrogen as a carrier gas and contains the reaction gas trimethyl indium TMIn, and the V / III ratio in the reaction mixture composed of the phosphorus source and the indium source is greater than 150 and less than 300.

[0086] The V / III ratio of the reaction gas in each embodiment of the present invention is defined as the ratio of the molar amount of the phosphorus source reaction gas to the molar amount of the indium source reaction gas in the reactant mixture).

[0087] In step S1 of some embodiments, the reaction temperature is controlled to be above 540 degrees Celsius and not higher than 600 degrees Celsius, the reaction pressure is controlled to be 3 kPa to 7 kPa, the supporting device is controlled to drive the original device to rotate around the axis of the reaction chamber at 400 to 700 rpm, a phosphorus source with a flow rate of 1000 sccm to 1800 sccm and an indium source with a flow rate of 1000 sccm to 2000 sccm are provided into the reaction chamber, and the V / III ratio of the reaction gas is controlled to be greater than 150 and less than 300, so that the growth rate of the intrinsic InP covering layer is 10 nm / min to 15 nm / min. Since the InGaAsP grating will be deformed due to phosphorus precipitation at a reaction temperature of 540 degrees Celsius or more and not more than 600 degrees Celsius and a reaction pressure of 3 kPa to 7 kPa, the growth rate of the intrinsic InP capping layer is controlled to 10 nanometers per minute to 15 nanometers per minute by controlling the reaction temperature, reaction pressure, phosphorus source flow rate, indium source flow rate and the V / III ratio of the reaction mixture, so as to ensure the good epitaxial quality of the intrinsic InP capping layer while minimizing or even avoiding the deformation of the grating due to phosphorus precipitation. If the growth rate of the intrinsic InP capping layer is too low, the reaction time will be long and the grating will be easily deformed due to phosphorus precipitation; if the growth rate of the intrinsic InP capping layer is too high, the good epitaxial quality cannot be guaranteed.

[0088] The step S2 of this embodiment includes step S21: controlling the flow rates of the phosphorus source, the indium source and the zinc source to be 1000sccm-1800sccm, 1000sccm-1500sccm and 30sccm-90sccm respectively, the V / III ratio of the reaction mixture composed of the phosphorus source and the indium source is greater than 150 and less than 300 until the P-type low-doped InP capping layer is formed, wherein the flow rate of the zinc source is controlled to increase at a rate of 30sccm-90sccm. Specifically, the bottom heating device 64 is controlled to make the reaction temperature at 590 degrees Celsius, and the pressure in the reaction chamber is controlled by the vacuum system to be maintained at 5 kPa. A phosphorus source with a flow rate of 1500 sccm, an indium source with a flow rate of 1500 sccm, and a zinc source with a flow rate of 30 sccm are injected into the reaction chamber by the injection device 61, and the flow rate of the zinc source is controlled to gradually increase at a rate of 30 sccm until a P-type low-doped InP covering layer is epitaxially grown on the top surface of the intrinsic InP covering layer to cover the exposed surface of the intrinsic InP covering layer, so as to control the growth rate of the P-type low-doped InP covering layer to be 10 nanometers / minute to 15 nanometers / minute until the P-type low-doped InP covering layer reaches the thickness required by the process. Specifically, the phosphorus source is provided into the reaction chamber by the injection device 61 with hydrogen as a carrier gas and containing the reaction gas phosphine PH3, the indium source is provided with hydrogen as a carrier gas and containing the reaction gas trimethyl indium TMIn, and the zinc source is provided with hydrogen as a carrier gas and containing the doping gas diethyl zinc DEZn, and the V / III ratio in the reaction mixture composed of the phosphorus source and the indium source is greater than 150 and less than 300.

[0089] In the step S21 of some embodiments, the reaction temperature of the reaction chamber is controlled to be above 590 degrees Celsius and not higher than 600 degrees Celsius, the reaction pressure is 3 kPa to 7 kPa, the phosphorus source flow rate provided to the reaction chamber is 1000 sccm to 1800 sccm, the indium source flow rate is 1000 sccm-1500 sccm, the zinc source flow rate is 30 sccm-90 sccm, and the zinc source flow rate is gradually increased in increments of 30 sccm-90 sccm. Although the aforementioned reaction temperature and reaction pressure are process conditions for good epitaxial growth of InP and can reduce or even avoid grating deformation, under this process condition, it is inevitable that the zinc source participates in the reaction to produce byproducts (such as zinc phosphide), so it is necessary to further control the growth rate of the P-type low-doped InP capping layer, so as to ensure the good doping and growth quality of the P-type low-doped InP capping layer while minimizing or even avoiding the deformation of the grating due to phosphorus precipitation, and reducing the generation of impurity (such as zinc phosphide) particles. If the growth rate of the P-type low-doped InP capping layer is too low, the reaction time will be long and the grating will be easily deformed due to phosphorus precipitation; if the growth rate of the P-type low-doped InP capping layer is too high, the impurity particles will be widely distributed and too concentrated, and good epitaxial doping quality cannot be guaranteed. In addition, controlling the flow rate of the zinc source in a suitable increment is conducive to forming a concentration gradient that gradually increases from the bottom surface of the layer to the top surface to meet the design requirements of the device. On the other hand, a suitable flow increment is also conducive to good doping and growth quality.

[0090] The present invention also provides a comparative example 1, wherein step S1 of the comparative example 1 is the same as that of the present embodiment, and the difference between step S21 of the comparative example 1 and step S21 of the present embodiment is that the phosphorus source flow rate provided to the reaction chamber is controlled to be 1000 sccm, the indium source flow rate is 1800 sccm, and the zinc source flow rate is 46 sccm to control the growth rate of the P-type low-doped InP capping layer to be 28 nanometers / minute. After step S21 of the present embodiment is completed, a transmission electron microscope photograph of the structure along the radial section is obtained as shown in FIG. Figure 4 After step S21 of comparative example 1 is completed, a transmission electron microscope photograph of the structure along the radial section is obtained. Figure 5 ,from Figure 4 and Figure 5 From the comparison, it can be seen that even if the phosphorus source flow rate is controlled at 1000sccm~1800sccm and the zinc source flow rate is controlled at 30sccm~90sccm in Comparative Example 1, the growth rate of the P-type low-doped InP covering layer is too fast due to the excessively high indium source flow rate, and the number and aggregation degree of impurity particles in its structure are significantly higher than those in this embodiment.

[0091] In order to investigate the effect of too low growth rate of P-type low-doped InP covering layer on grating structure, this embodiment also provides comparative example 2. In order to observe the deformation of grating more clearly, the difference between the original device of comparative example 2 and the original device of this embodiment is that the height of grating is higher (75nm), and part of grating is covered with photolithography plate so that the original grating structure can still be observed on the obtained device for comparison. Step S1 of comparative example 2 is the same as that of this embodiment. The difference between its step S21 and step S21 of this embodiment is that the flow rate of phosphorus source provided to the reaction chamber is controlled to be 1000sccm, the flow rate of indium source is 900sccm, and the flow rate of zinc source doping gas is 46sccm to control the growth rate of P-type low-doped InP covering layer to be 8 nanometers / minute. After step S21, the central area of ​​the original device was longitudinally sectioned by scanning electron microscopy to obtain Figure 6 .from Figure 6 It can be seen that even if the phosphorus source flow rate is controlled at 1000 sccm-1800 sccm and the zinc source flow rate is controlled at 30 sccm-90 sccm in Comparative Example 2, the growth rate of the P-type low-doped InP covering layer is too low due to the low indium source flow rate, resulting in serious grating deformation.

[0092] After the step S21 of this embodiment is completed, step S22 is performed: under the process conditions of step S1, the zinc source flow rate is increased to 120 sccm to epitaxially grow the P-type high-doped InP capping layer on the top surface of the P-type low-doped InP capping layer until the P-type high-doped InP capping layer reaches the required controlled thickness. The zinc source flow rate is controlled to increase gradually at a rate of 30 sccm.

[0093] In step S22 of some embodiments, the flow rate of the zinc source is increased to 30 sccm-120 sccm and increases at a rate of 30-120 sccm. Controlling the flow rate of the zinc source with a suitable increment is beneficial to forming a concentration gradient gradually increasing from the bottom surface of the layer to the top surface to meet the requirements of device design. On the other hand, a suitable flow increment is also beneficial to good growth quality during the doping process.

[0094] Before executing step S1, this embodiment further performs a water and oxygen removal process on the original device.

[0095] In some embodiments, during the process of making the original device, a wet process is used to remove the mask after the grating processing is completed, such as using BOE or HF solution for immersion removal and then drying the original device. The obtained wet original device needs to be further dehydrated and oxygenated to ensure good subsequent epitaxial growth quality.

[0096] In this embodiment, the process of preparing the original device and the process of using BOE solution for soaking and removal followed by drying are both conventional technical means in the field and will not be described in detail here.

[0097] In some embodiments, the dehydration and oxygen removal treatment is performed in a treatment chamber, which is connected to the reaction chamber of the MOCVD equipment of Example 2, and a switch device is provided between the two to control the connection between the two. Specifically, before executing step S1 of Example 2, after controlling the reaction chamber and the treatment chamber to be disconnected from each other, a phosphorus source is provided to the treatment chamber, and the temperature and pressure in the treatment chamber are controlled until the temperature in the treatment chamber is above 450 degrees Celsius and below 500 degrees Celsius, and the pressure is the reaction pressure of step S1 of Example 2, and then the treatment temperature and pressure are maintained for 6-10 minutes. After the dehydration and oxygen removal treatment is completed, the original device is transferred to the reaction chamber.

[0098] In this embodiment, the dehydration and oxygen treatment is carried out in the reaction chamber. Specifically, the original device is placed on the wafer carrier, the pressure in the reaction chamber is controlled to be the reaction pressure of step S1 in embodiment 2, and after the temperature is raised to 450 degrees Celsius, the phosphorus source used in embodiment 2 is provided to the reaction chamber and the treatment time is continued for 10 minutes to complete the dehydration and oxygen treatment. In this embodiment, the dehydration and oxygen treatment is carried out in the reaction chamber, and the phosphorus source is provided to the reaction chamber during the dehydration and oxygen treatment, and the treatment pressure is controlled to be equivalent to the reaction pressure of step S1 in embodiment 2. On the one hand, the transportation time of the original device and the reaction chamber pressure adjustment time are saved to improve the production efficiency. On the other hand, providing the phosphorus source and controlling the aforementioned temperature and pressure are conducive to effectively removing water and oxygen while avoiding deformation of the grating due to phosphorus precipitation or even failure of the device due to leakage breakdown.

[0099] In some embodiments, a phosphorus source is provided to the reaction chamber and the temperature in the treatment chamber is controlled to be higher than 100 degrees Celsius and lower than 500 degrees Celsius, the pressure is 3 kPa to 7 kPa, and the treatment time is not less than 6 minutes. In some embodiments, the treatment temperature is above 450 degrees Celsius and lower than 500 degrees Celsius, and the time of the water removal and oxygen treatment is 6-10 minutes. The specific temperature and treatment time are adaptively adjusted according to the water and oxygen content of the original device after drying. If the water and oxygen content of the original device after drying is low, the water removal and oxygen treatment can be carried out at a relatively low temperature for a long time, such as 20 minutes of water removal and oxygen treatment at 150 degrees Celsius, or at a relatively high temperature for a short time, such as 10 minutes of water removal and oxygen treatment at 450 degrees Celsius; if the water and oxygen content of the original device after drying is high, a relatively low temperature for a long time of water removal and oxygen treatment will bring high energy consumption, and it is inclined to be carried out at a relatively high temperature for a short time of water removal and oxygen treatment.

[0100] After the dehydration and oxygen removal treatment of this embodiment is completed, the phosphorus source is maintained to be introduced into the reaction chamber, and the temperature in the reaction chamber is controlled to rise to 540 degrees Celsius at a heating rate of 1.5 degrees Celsius / second. Then, the indium source reaction gas used in Example 2 is provided to the reaction chamber, and then the reaction chamber is continued to be heated to the reaction temperature in step S1 of Example 2.

[0101] In some embodiments, the temperature rise rate in the reaction chamber is controlled to be 0.9 degrees Celsius per second to 2.5 degrees Celsius per second. After the water and oxygen removal treatment is completed, the temperature rise rate is controlled to be slow, and the surface temperature of the original device is uniform to improve the epitaxial quality.

[0102] Embodiment 3

[0103] After step S2 of embodiment 2 is completed, step S3 is performed to form the semiconductor laser of embodiment 1, that is, the etching stop layer, the P-type doped first barrier gradient layer, the P-type doped second barrier gradient layer and the P-type doped ohmic contact layer of embodiment 1 are formed by epitaxial growth on the top surface of the P-type highly doped InP cap layer. The carrier device is controlled to drive the original device to rotate around the axis of the reaction chamber at 400 to 700 revolutions per minute.

[0104] In step S3 of this embodiment, a P-type doped first barrier gradient layer, a P-type doped second barrier gradient layer and a P-type doped ohmic contact layer are formed by a zinc diffusion method. Figure 7 ,include:

[0105] S31: forming an intrinsic InP layer, an intrinsic InGaAsP layer and an intrinsic ohmic contact layer;

[0106] S32: after providing a protective medium into the reaction chamber and controlling the temperature in the reaction chamber to be 500 degrees Celsius to 540 degrees Celsius and the pressure to be 10 kPa to 40 kPa, injecting the zinc source into the top surface of the intrinsic ohmic contact layer and controlling the depth of zinc diffusion to not exceed the sum of the thicknesses of the intrinsic InP layer, the intrinsic InGaAsP layer and the intrinsic ohmic contact layer;

[0107] S33: controlling the flow rate of the protective medium to be higher than the flow rate of the zinc source, and after cooling the temperature in the reaction chamber to no more than 400 degrees Celsius, switching the protective medium to an inert medium and providing it into the reaction chamber, and controlling the flow rate of the inert medium to be equal to the flow rate of the zinc source;

[0108] S34: Rapidly adjust the temperature in the reaction chamber to below 150 degrees Celsius.

[0109] Compared with the method of forming each P-type doped first barrier gradient layer, second barrier gradient layer and ohmic contact layer in steps, the present embodiment forms each intrinsic layer first through step S31, and then forms the P-type doped first barrier gradient layer, P-type doped second barrier gradient layer and P-type doped ohmic contact layer at one time by zinc diffusion at 500 degrees Celsius to 540 degrees Celsius and a pressure of 10 kPa to 40 kPa through step S32, which simplifies the process control, not only meets the device requirement of gradually increasing the doping concentration from the bottom surface of the first barrier gradient layer in the direction pointing to the top surface of the ohmic contact layer, but also makes it easier to control the doping concentration gradient. Further, since the H-Zn bond is formed in the zinc diffusion process of step S32, it is not conducive to the stability of subsequent device use, and the annealing process performed in the above step S33 and the rapid adjustment process performed in step S34 can break the H-Zn bond without negatively affecting the doping effect, which is conducive to the stability of subsequent device use.

[0110] In some embodiments, the protective medium is an arsenic source or hydrogen, the arsenic source includes an arsenic-containing gas, and the inert medium is at least one of nitrogen, helium, neon, argon, krypton, xenon, and radon.

[0111] In step S32 of some embodiments, the flow rate of the zinc source is 90 sccm to 540 sccm.

[0112] In step S34 of some embodiments, the temperature in the reaction chamber is controlled to rise to 420°C to 450°C at a rate of 0.9°C to 2.5°C / second and maintained for 5 to 10 minutes, and then the temperature in the reaction chamber is controlled to drop to below 150°C at a rate of 0.7°C to 1.5°C / second.

[0113] Before executing step S31 in this embodiment, the pressure of the reaction chamber is maintained at the reaction pressure of step S22 in embodiment 2, the reaction temperature is 600-630°C, the phosphorus source used in embodiment 2 is introduced into the reaction chamber with a flow rate of 600sccm, the indium source, gallium source and arsenic source used in embodiment 2 are introduced into the reaction chamber with flow rates of 1000sccm, 520sccm and 600sccm respectively to form an etching stop layer until a predetermined thickness is reached.

[0114] In the embodiment of the present invention, the gallium source uses hydrogen as a carrier gas and contains trimethylgallium (TMGa) as a reaction gas. The arsenic source uses hydrogen as a carrier gas and contains arsine (AsH3) as a reaction gas.

[0115] In some embodiments, the gallium source includes a gallium-containing metal organic compound, such as a gallium-containing alkyl compound.

[0116] In some embodiments, the arsenic source is an arsenic-containing gas.

[0117] In some embodiments, before executing step S31 , the step of forming an etching stop layer may not be performed according to the manufacturing requirements of the semiconductor device.

[0118] In step S31 of this embodiment, the pressure of the reaction chamber is maintained consistent with step S22 of embodiment 2, the reaction temperature in the reaction chamber is controlled to be 580-600° C., PH3 and TMIn with hydrogen as carrier gas and a flow rate of 330 sccm are controlled to be introduced into the reaction chamber to epitaxially grow an intrinsic InP layer on the top surface of the etching stop layer until a predetermined thickness is reached; the aforementioned reaction temperature and reaction pressure are maintained unchanged, and T is controlled to be introduced into the reaction chamber with hydrogen as carrier gas and a flow rate of 290 sccm, 160 sccm, 85 sccm and 800 sccm respectively. MIn, TMGa, AsH3 and PH3 are used to epitaxially grow a first intrinsic InGaAsP layer of a predetermined thickness on the top surface of the intrinsic InP layer; the reaction pressure is maintained unchanged, the reaction temperature is controlled to be 560-590°C, TMIn, TMGa, AsH3 and DEZn with hydrogen as a carrier gas are introduced into the reaction chamber and the flow rates are controlled to be 1000sccm, 520sccm, 600sccm and 520sccm in sequence to epitaxially grow a second intrinsic InGaAsP layer on the first intrinsic InGaAsP layer until a predetermined thickness is reached.

[0119] In step S32 of this embodiment, hydrogen is introduced into the reaction chamber as a protective medium, and the reaction temperature is controlled to be 540 degrees Celsius and the reaction pressure is controlled to be 30 kPa. Then, the zinc source used in Example 2 is injected into the top surface of the second intrinsic InGaAsP in the reaction chamber and the flow rate is controlled to be 520 sccm. The depth of zinc diffusion is controlled not to exceed the sum of the thicknesses of the intrinsic InP, the first intrinsic InGaAsP layer and the second intrinsic InGaAsP layer.

[0120] In step S33 of this embodiment, the hydrogen flow rate is controlled to be 150% of the zinc source flow rate, and after the temperature in the reaction chamber is controlled to drop to 300 degrees Celsius, the hydrogen is switched to nitrogen to be introduced into the reaction chamber and the nitrogen flow rate is controlled to be equivalent to the zinc source flow rate.

[0121] In step S34 of this embodiment, the temperature in the reaction chamber is rapidly heated to 420°C to 450°C at a heating rate of 2.5°C / sec and maintained for 5 to 10 minutes, and then rapidly cooled to below 150°C at a cooling rate of 1.5°C / sec.

[0122] The semiconductor laser obtained in this embodiment was tested for electroluminescence on a MaxMile RobotⅡsystem electroluminescence and photoluminescence test system, and the following results were obtained: Figure 8The relative emission intensity and the main wavelength are shown in the figure. It can be seen from the figure that the semiconductor laser has a significant peak and the central wavelength is located at 1308 nanometers, which meets the design requirements of the device.

[0123] Although the embodiments of the present invention are described in detail above, it is obvious to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as described. Moreover, the present invention described herein may have other embodiments and may be implemented or realized in a variety of ways.

Claims

1. A method for manufacturing a semiconductor laser, characterized in that: The following steps are involved: Step S0: providing a reaction chamber and an original device located in the reaction chamber, wherein the original device comprises an n-type InP substrate, and a lower light field limiting layer, an active layer, an upper light field limiting layer and a grating which are sequentially arranged from bottom to top on the n-type InP substrate, wherein the grating is an InGaAsP grating; Step S1: controlling the reaction temperature in the reaction chamber to be above 540 degrees Celsius and not higher than 600 degrees Celsius and the reaction pressure to be 3 kPa to 7 kPa, providing a phosphorus source and an indium source into the reaction chamber, thereby forming an intrinsic InP capping layer having a thickness not exceeding 5 nanometers on the grating at a growth rate of 10 nanometers / minute to 15 nanometers / minute; Step S2: controlling the reaction temperature and the reaction pressure in the reaction chamber to be above 590 degrees Celsius and not higher than 600 degrees Celsius, providing the phosphorus source, the indium source and the zinc source into the reaction chamber, thereby sequentially forming a P-type low-doped InP covering layer and a P-type highly-doped InP covering layer on the intrinsic InP covering layer at a growth rate of 10 nanometers / minute to 15 nanometers / minute and embedding the grating; Step S3: sequentially forming a P-type doped barrier gradient layer and a P-type doped ohmic contact layer on the P-type highly doped InP covering layer, or sequentially forming an etching stop layer, the P-type doped barrier gradient layer and the P-type doped ohmic contact layer on the P-type highly doped InP covering layer.

2. The method for manufacturing a semiconductor laser according to claim 1, characterized in that: During the execution of step S1, step S2 and step S3, the original device is controlled to rotate around the axis of the grating.

3. The method for manufacturing a semiconductor laser according to claim 2, characterized in that: The original device is controlled to rotate at a speed of 400 to 700 rpm.

4. The method for manufacturing a semiconductor laser according to claim 1, wherein: Before executing the step S1, the temperature in the reaction chamber is controlled to be a processing temperature higher than 100 degrees Celsius and lower than 500 degrees Celsius, and the pressure in the reaction chamber is the reaction pressure, and the phosphorus source is provided in the reaction chamber to perform a water and oxygen removal treatment on the original device for not less than 6 minutes.

5. The method for manufacturing a semiconductor laser according to claim 4, characterized in that: After the deoxygenation step is completed, the temperature in the reaction chamber is controlled to rise to no higher than 540 degrees Celsius at a rate of 0.9 degrees Celsius / second to 2.5 degrees Celsius / second, the indium source is supplemented into the reaction chamber, and then the temperature in the reaction chamber is controlled to rise to the reaction temperature, and then step S1 is performed.

6. The method for manufacturing a semiconductor laser according to claim 4, characterized in that: The treatment temperature is above 450 degrees Celsius and below 500 degrees Celsius, and the time for the water and oxygen removal treatment is 6-10 minutes.

7. The method for manufacturing a semiconductor laser according to claim 1, characterized in that: In the step S1, the step of providing a phosphorus source and an indium source into the reaction chamber includes controlling the flow rates of the phosphorus source and the indium source to be 1000 sccm-1800 sccm and 1000 sccm-2000 sccm respectively, and the V / III ratio of the reaction mixture composed of the phosphorus source and the indium source is greater than 150 and less than 300, wherein the V / III ratio is defined as the ratio of the molar amount of the phosphorus source reaction gas to the molar amount of the indium source reaction gas in the reaction mixture.

8. The method for manufacturing a semiconductor laser according to claim 1, characterized in that: In step S2, the thickness of the P-type low-doped InP covering layer does not exceed 5 nanometers, and the sum of the thicknesses of the intrinsic InP covering layer, the P-type low-doped InP covering layer and the P-type high-doped InP covering layer is 10-40 nanometers thicker than the thickness of the grating.

9. The method for manufacturing a semiconductor laser according to claim 1, characterized in that: In the step S2, the step of providing the phosphorus source, the indium source and the zinc source into the reaction chamber comprises: Step S21: controlling the flow rates of the phosphorus source, the indium source and the zinc source to be 1000sccm-1800sccm, 1000sccm-1500sccm and 30sccm-90sccm respectively, and the V / III ratio of the reaction mixture composed of the phosphorus source and the indium source is greater than 150 and less than 300 until the P-type low-doped InP capping layer is formed, wherein the V / III ratio is defined as the ratio of the molar amount of the phosphorus source reaction gas to the molar amount of the indium source reaction gas in the reaction mixture; Step S22: controlling the flow rates of the phosphorus source and the indium source to remain unchanged, and controlling the flow rate of the zinc source to be 30 sccm-120 sccm until the P-type highly doped InP capping layer is formed.

10. The method for manufacturing a semiconductor laser according to claim 9, characterized in that: The step S21 further includes controlling the flow rate of the zinc source to increase at a rate of 30 sccm-90 sccm, and the step S22 further includes controlling the flow rate of the zinc source to increase at a rate of 30 sccm-120 sccm.

11. The method for manufacturing a semiconductor laser according to claim 1, characterized in that: In the step S3, the doping concentration of the P-type doped ohmic contact layer is higher than the doping concentration of the P-type doped barrier gradient layer, and the P-type doped barrier gradient layer includes a P-type doped InP layer and a P-type doped InGaAsP layer which are sequentially layered.

12. The method for manufacturing a semiconductor laser according to claim 11, characterized in that: The doping concentration of the P-type doped InP layer is 2×10 17 / cubic centimeter ~ 1×10 18 / cubic centimeter, with a thickness of 70 nanometers to 2 micrometers. The doping concentration of the P-type doped InGaAsP layer is 5×10 17 / cubic centimeter ~ 2.5 × 10 18 / cubic centimeter, the thickness is 20 nanometers to 45 nanometers, and the doping concentration of the P-type doped ohmic contact layer is 1.5×10 19 / cubic centimeter ~ 3×10 19 / cubic centimeter.

13. The method for manufacturing a semiconductor laser according to claim 1, characterized in that: In the step S3, the step of forming the barrier gradient layer and the ohmic contact layer comprises: Step S31: forming an intrinsic InP layer, an intrinsic InGaAsP layer and an intrinsic ohmic contact layer; Step S32: after providing a protective medium into the reaction chamber and controlling the temperature in the reaction chamber to be 500 degrees Celsius to 540 degrees Celsius and the pressure to be 10 kPa to 40 kPa, injecting the zinc source into the top surface of the intrinsic ohmic contact layer and controlling the depth of zinc diffusion to not exceed the sum of the thicknesses of the intrinsic InP layer, the intrinsic InGaAsP layer and the intrinsic ohmic contact layer; Step S33: controlling the flow rate of the protective medium to be higher than the flow rate of the zinc source, and after cooling the temperature in the reaction chamber to no more than 400 degrees Celsius, switching the protective medium to an inert medium and providing it into the reaction chamber, and controlling the flow rate of the inert medium to be equivalent to the flow rate of the zinc source; Step S34: quickly adjusting the temperature in the reaction chamber to below 150 degrees Celsius.

14. The method for manufacturing a semiconductor laser according to claim 13, characterized in that: In the step S32, the flow rate of the zinc source is 90 sccm to 540 sccm.

15. The method for manufacturing a semiconductor laser according to claim 13, characterized in that: In step S34, the temperature in the reaction chamber is controlled to rise to 420°C to 450°C at a rate of 0.9°C to 2.5°C / second and maintained for 5 to 10 minutes, and then the temperature in the reaction chamber is controlled to drop to below 150°C at a rate of 0.7°C to 1.5°C / second.

16. The method for manufacturing a semiconductor laser according to claim 13, characterized in that: The protective medium is an arsenic source or hydrogen, the arsenic source includes an arsenic-containing gas, and the inert medium is at least one of nitrogen, helium, neon, argon, krypton, xenon, and radon.

17. The method for manufacturing a semiconductor laser according to claim 1, characterized in that: The phosphorus source includes a phosphorus-containing gas, the indium source includes an indium-containing metal organic compound, and the zinc source includes a zinc-containing metal organic compound.

18. The method for manufacturing a semiconductor laser according to claim 1, characterized in that: The reaction chamber is provided with a carrying device for carrying the original device, and an injection device, wherein the injection device is arranged opposite to the carrying device so that the substance provided into the reaction chamber by the injection device flows along the axial direction of the reaction chamber toward the grating.

19. A semiconductor laser, characterized in that: The semiconductor laser is manufactured by the manufacturing method of any one of claims 1 to 18, wherein the semiconductor laser comprises an n-type InP substrate, and a lower optical field confinement layer, an active layer, an upper optical field confinement layer, a grating, an intrinsic InP cover layer, a P-type low-doped InP cover layer and a P-type high-doped InP cover layer are sequentially arranged on the n-type InP substrate from bottom to top; The grating is an InGaAsP grating; The height of the intrinsic InP capping layer does not exceed 5 nanometers.

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