Preparation method of laser chip and laser projection equipment
By forming a combined structure of copper layer and air layer in the laser chip, the temperature distribution inside the laser chip is regulated, and the problem of low quality of the laser output beam is solved and the imaging quality of the laser projection equipment is improved.
Patent Information
- Application Number
- CN202311341532.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-10-17
- Publication Date
- 2025-04-18
AI Technical Summary
Due to the reduced quality of the beam output by the laser, the imaging quality of the laser projection device is low.
By forming a copper layer with high thermal conductivity and an air layer with low thermal conductivity on the side of the first electrode layer of the laser chip away from the semiconductor substrate, the temperature distribution inside the laser chip is regulated to make it more uniform.
It effectively suppresses the increase in the divergence angle of the light beam on the slow axis, improves the quality of the laser output beam, and thus improves the imaging quality of the laser projection equipment.
Smart Images
Figure CN119852839A_ABST
Abstract
Description
Technical Field
[0001] The embodiments of the present application relate to the field of laser projection technology, and more specifically, to a method for preparing a laser chip and a laser projection device. Background Art
[0002] Laser is one of the important components in laser projection equipment such as laser TV and laser projector, and is used to provide laser light source for laser TV and laser projector. Wide stripe high-power laser diode (WS-HPLD) is used in the field of laser projection technology due to its advantages such as wide output band coverage, high output power, small size and long life. With the continuous expansion of laser projection technology, higher requirements are put forward for the output power and beam quality of WS-HPLD. At present, the output power of WS-HPLD single tube has reached tens of watts. Although the output power of WS-HPLD has been greatly improved, its electro-optical conversion efficiency remains at 50% to 70%, which means that 30% to 50% of the energy is converted into heat energy, which has a serious impact on the performance of HPLD (beam quality, threshold current, output power, output wavelength, electro-optical conversion efficiency, etc.).
[0003] In particular, the heat converted by WS-HPLD will cause the temperature distribution inside it to be high in the center and low at the edge. The active area material of WS-HPLD has a strong refractive index limitation in the vertical direction (fast axis direction), and its beam divergence angle and beam width change little, and the beam quality is relatively stable; while the active area material has a weak refractive index limitation in the horizontal direction (slow axis direction), and its beam divergence angle and beam width are easily affected by temperature changes, resulting in an increase in the slow axis divergence angle of the laser, which leads to low beam quality output by WS-HPLD, and thus low imaging quality of the laser projection equipment. Summary of the invention
[0004] The exemplary embodiments of the present application provide a method for preparing a laser chip and a laser projection device, which are used to solve the problem of low imaging quality of the laser projection device caused by reduced quality of the beam output by the laser.
[0005] The technical solutions provided by the embodiments of this application are as follows:
[0006] In a first aspect, an embodiment of the present application provides a method for preparing a laser chip, wherein the laser chip is applied to a laser projection device, and the method for preparing the laser chip comprises:
[0007] providing a semiconductor substrate;
[0008] Forming a semiconductor epitaxial structure layer on one side of the semiconductor substrate, wherein the semiconductor epitaxial structure layer includes a current injection region and a non-injection region;
[0009] forming a first electrode layer on a side of the semiconductor epitaxial structure layer away from the semiconductor substrate;
[0010] forming a copper layer and an air layer in contact with the first electrode layer on a side of the first electrode layer away from the semiconductor substrate, wherein the copper layer is located in the current injection region, and the air layer is located in the non-injection region;
[0011] A second electrode layer is formed on a side of the semiconductor substrate away from the semiconductor epitaxial structure layer.
[0012] In a second aspect, an embodiment of the present application provides a laser projection device, including: a display control component, a light source driving component, a light source, a light valve, and a lens;
[0013] The display control component is connected to the light source driving component and the light valve respectively, and the light source driving component is also connected to the light source;
[0014] The light source includes at least one laser chip, and the laser chip includes:
[0015] Semiconductor substrate;
[0016] A semiconductor epitaxial structure layer, the semiconductor epitaxial structure layer is located on one side of the semiconductor substrate, and the semiconductor epitaxial structure layer includes a current injection region and a non-injection region;
[0017] a first electrode layer, the first electrode layer being located on a side of the semiconductor epitaxial structure layer away from the semiconductor substrate;
[0018] a thermal conductivity structural layer, the thermal conductivity structural layer being located on a side of the first electrode layer away from the semiconductor substrate and in contact with the first electrode layer, the thermal conductivity structural layer comprising a copper layer located in the current injection region and an air layer located in the non-injection region;
[0019] A second electrode layer, wherein the second electrode layer is located on a side of the semiconductor substrate away from the semiconductor epitaxial structure layer.
[0020] It can be seen from the above technical scheme that the preparation method of the laser chip and the laser projection device provided by the embodiment of the present application form a copper layer and an air layer in contact with the first electrode layer on the side of the first electrode layer away from the semiconductor substrate, and the copper layer is located in the current injection area, and the air layer is located in the non-injection area. Since the material of the copper layer is a high thermal conductivity material, the copper layer is set in the current injection area with a corresponding higher temperature, which can effectively conduct the heat from the center of the laser chip; at the same time, since the material of the air layer is a low thermal conductivity material, the air layer is formed in the non-injection area with a corresponding lower temperature, which can effectively limit the heat from the edge of the laser chip to the outside. In this way, through the mutual cooperation of the copper layer and the air layer, the internal temperature of the laser chip can be regulated, so that the internal center temperature of the laser chip drops rapidly, while the internal edge temperature of the laser chip drops slowly, thereby balancing the internal center temperature and edge temperature of the laser chip, making the internal temperature distribution of the laser chip more uniform, suppressing the increase of the divergence angle of the light beam in the slow axis, thereby improving the quality of the laser output light beam, and thus improving the imaging quality of the laser projection device. In addition, forming a copper layer on the side of the first electrode layer away from the semiconductor substrate can reduce the stress problem caused by high-temperature eutectic during packaging and improve the reliability of the packaged device. Moreover, the copper layer is directly formed on the first electrode layer, and it is easy to align with the current injection area during the formation process (for example, using a photolithography process). Compared with the related technology of improving the beam quality by changing the heat sink structure, this application does not need to be precisely mounted with the heat sink during patch packaging, and patch packaging can be achieved, greatly reducing the process difficulty. In addition, electroplated copper has better thermal conductivity, low material cost, simpler preparation method, and low process complexity, which is conducive to mass production. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] In order to more clearly illustrate the implementation methods in the embodiments of the present application or the related technologies, the following is a brief introduction to the drawings required for use in the embodiments or the related technology descriptions. Obviously, the drawings described below are some embodiments of the present application, and a person skilled in the art can also obtain other drawings based on these drawings.
[0022] Figure 1 A flow chart showing a method for preparing a laser chip in some embodiments;
[0023] Figure 2 A schematic diagram showing the structure of a laser chip for preparing a semiconductor epitaxial structure layer in some embodiments;
[0024] Figure 3 A schematic diagram showing the distribution of current injection areas and non-injection areas in some embodiments;
[0025] Figure 4A schematic diagram showing the structure of a laser chip forming a current injection region in some embodiments;
[0026] Figure 5 A schematic diagram of the structure of a laser chip for preparing a first electrode layer in some embodiments is shown;
[0027] Figure 6 A schematic diagram of the structure of a laser chip with a copper-plated window formed in some embodiments is shown;
[0028] Figure 7 A schematic diagram of the structure of a copper electroplated laser chip in some embodiments is shown;
[0029] Figure 8 A schematic diagram of the structure of a laser chip for preparing a copper layer and an air layer in some embodiments is shown;
[0030] Fig. 9 A schematic diagram showing the structure of a laser chip for preparing a second electrode layer in some embodiments is shown;
[0031] Fig.10 A schematic diagram showing the structure of a laser chip mounted with a heat sink in some embodiments;
[0032] Fig.11 The heat flow and temperature distribution simulation diagrams of the common (existing) laser (N-LD) in some embodiments and the laser (MCAS-LD) provided in the embodiments of the present application are shown;
[0033] Fig.12 The temperature distribution curves of the common (existing) laser (N-LD) in some embodiments and the laser (MCAS-LD) provided in the embodiments of the present application along the slow axis direction in the active region are shown;
[0034] Fig.13 A structural block diagram of a laser projection device in some embodiments is shown. DETAILED DESCRIPTION
[0035] In order to make the purpose and implementation method of the present application clearer, the exemplary implementation method of the present application will be clearly and completely described below in conjunction with the drawings in the exemplary embodiments of the present application. Obviously, the described exemplary embodiments are only part of the embodiments of the present application, rather than all the embodiments.
[0036] It should be noted that the brief description of terms in this application is only for the convenience of understanding the embodiments described below, and is not intended to limit the embodiments of this application. Unless otherwise specified, these terms should be understood according to their common and usual meanings.
[0037] The terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover but not exclude inclusion, for example, a product or device comprising a list of components is not necessarily limited to all the components expressly listed but may include other components not expressly listed or inherent to such product or device.
[0038] In view of the technical problems existing in the related art, the inventor has studied that when the laser is working, as the injection current increases, the probability of non-radiative recombination of carriers in the active area of the laser chip increases, thereby increasing the thermal power of the laser chip. If there is no temperature change inside the chip, the light beams output by the laser are all parallel light emission; and the change in local temperature (usually in a state of high center temperature and low edge temperature) will cause the refractive index distribution of the laser waveguide material to change. When the light beam passes through this position, it will refract to varying degrees, similar to the convergence or divergence effect produced by an optical lens, that is, the "thermal lens effect", which will lead to an increase in the divergence angle of the light beam and a decrease in the quality of the light beam. Therefore, the quality of the laser output light beam is low, which is actually caused by the uneven temperature distribution inside the laser chip. Based on this, the embodiment of the present application adjusts the temperature inside the laser chip by setting a copper layer with high thermal conductivity and an air layer with low thermal conductivity, so that the temperature distribution inside the laser chip is more uniform, improves the quality of the laser output light beam, and thus improves the imaging quality of the laser projection device.
[0039] Specifically, Figure 1 A flow chart of a method for preparing a laser chip in some embodiments is shown. The method for preparing the laser chip is suitable for preparing wide-strip high-power semiconductor laser chips. The laser chip prepared by the method for preparing the laser chip of the present application can be applied to laser projection equipment. Figure 1 As shown, the method for preparing the laser chip includes:
[0040] S110 , providing a semiconductor substrate.
[0041] refer to Figure 2 , provide a semiconductor substrate 10. In some embodiments, the material of the semiconductor substrate 10 includes silicon, gallium arsenide or gallium nitride. In other embodiments, the material of the semiconductor substrate 10 can also be other semiconductor materials, which is not limited in the present application. Exemplarily, the semiconductor substrate 10 is an N-type gallium arsenide substrate.
[0042] S120, forming a semiconductor epitaxial structure layer on one side of the semiconductor substrate, wherein the semiconductor epitaxial structure layer includes a current injection region and a non-injection region.
[0043] refer to Figure 2, a semiconductor epitaxial structure layer 20, i.e., an epitaxial wafer, is grown on one side of the semiconductor substrate 10, and the semiconductor epitaxial structure layer 20 may include an active layer 21. The active layer 21 is used to provide optical gain, and the active layer 21 may include a single-layer or multi-layer quantum well. The material used for the single-layer or multi-layer quantum well may be any active dielectric material, and the gain spectrum peak wavelength range may cover the near-ultraviolet to infrared band. In addition, the semiconductor epitaxial structure layer 20 may also include a lower confinement layer 22, a lower waveguide layer 23, an upper waveguide layer 24, an upper confinement layer 25, and an ohmic contact layer 26. At this time, the lower confinement layer 22, the lower waveguide layer 23, the active layer 21, the upper waveguide layer 24, the upper confinement layer 25, and the ohmic contact layer 26 are stacked in sequence. Accordingly, when preparing the semiconductor epitaxial structure layer, the lower confinement layer 22, the lower waveguide layer 23, the active layer 21, the upper waveguide layer 24, the upper confinement layer 25 and the ohmic contact layer 26 can be deposited in sequence on the semiconductor substrate 10 by metal organic chemical vapor deposition (MOCVD). Among them, the lower confinement layer 22 and the upper confinement layer 25 are used to improve the carrier confinement capability of the semiconductor laser, thereby improving the utilization rate of the carriers; the lower waveguide layer 23 and the upper waveguide layer 24 are used to reduce the waveguide to expand the light spot and reduce the divergence angle of the light beam in the vertical direction. The materials and thicknesses of the lower confinement layer 22, the lower waveguide layer 23, the active layer 21, the upper waveguide layer 24, the upper confinement layer 25 and the ohmic contact layer 26 can be set according to actual needs.
[0044] In addition, refer to Figure 3 , along the slow axis direction of the laser chip, the current injection region 201 is located in the middle region, and the non-injection region 202 is located on both sides of the current injection region 201. The non-injection region 202 has a high resistance characteristic and is used to limit the current injection region of the current, so that it can be ensured that the carriers can only be injected from the current injection region 201 into the active layer 21 to achieve modulated current injection. To form the current injection region 201 and the non-injection region 202 in the semiconductor epitaxial structure layer 20, refer to Figure 4 A photolithography process can be used to form an insulating dielectric layer 27 on a side of the semiconductor epitaxial structure layer 20 away from the semiconductor substrate 10 . The insulating dielectric layer 27 has an injection region window, thereby forming a current injection region 201 and a non-injection region 202 in the semiconductor epitaxial structure layer 20 .
[0045] S130, forming a first electrode layer on a side of the semiconductor epitaxial structure layer away from the semiconductor substrate.
[0046] Among them, the first electrode layer can be a p-type ohmic contact electrode. Specifically, Ti / Pt / Au can be sputtered on the surface of the ohmic contact layer 26 using a magnetron sputtering device to improve the ohmic contact conditions, and then annealed to form a p-type ohmic contact electrode. The first electrode layer in the embodiment of the present application is a p-type ohmic contact electrode, and the p-type ohmic contact electrode is closer to the active layer, so setting the copper layer on the surface of the p-type ohmic contact electrode is more conducive to heat conduction and temperature control inside the chip.
[0047] S140, forming a copper layer and an air layer in contact with the first electrode layer on a side of the first electrode layer away from the semiconductor substrate, wherein the copper layer is located in the current injection region, and the air layer is located in the non-injection region.
[0048] In some embodiments, this step may include: using a photolithography process to form a copper-plated window in an area on a side of the first electrode layer away from the semiconductor substrate and corresponding to the current injection area; placing the laser chip with the copper-plated window in an electrolyte, and plating copper in the current injection area to form a copper layer; removing the photoresist and copper on the non-injection area to form an air layer.
[0049] Specifically, refer to Figure 6 , spin-coat a photoresist 401 on the surface of the first electrode layer 30, and use an ultraviolet photolithography device to form a copper-plated window 402 corresponding to the position of the current injection area on the photoresist 401. Then, clamp the Figure 6 The device is placed in an electrolyte, and copper is plated on the surface of the first electrode layer 30 exposed by the copper plating window 402 and the surface of the photoresist 401 to obtain a device as shown in FIG. Figure 7 Finally, refer to Figure 8 The photoresist 401 is removed by using a stripping solution. At this time, the copper on the surface of the photoresist 401 is also removed, thereby obtaining a copper layer 41 and an air layer 42.
[0050] In some embodiments, copper plating in the current injection area includes: controlling the temperature of the electrolyte to be 20-30° C., and the current density of the DC power supply to be 27-35 mA / cm 2 , the electroplating time is 8 to 20 minutes. In this way, a copper layer 41 with low surface roughness, good flatness, good density and good quality can be obtained. In addition, the electrolyte can be stirred during the electroplating process to obtain a more uniform electroplated layer. In this embodiment, if the current density is less than 27mA / cm 2 , the electroplating speed at the copper plating window 402 is faster, and the electroplating speed at the photoresist 401 is slower, and the electroplating layer will be high in the center and low on both sides, resulting in a rough surface of the plating layer. If the current density is greater than 35mA / cm 2, lateral electroplating will occur on both sides of the copper-plated window 402, widening the width of the copper layer 41 and affecting the improvement effect of the laser chip. Therefore, the current density of the DC power supply is controlled to be 27-35 mA / cm 2 , which can not only reduce the surface roughness of the prepared copper layer, but also ensure the improvement effect of the laser chip.
[0051] In some embodiments, the copper layer has a thickness of 5 to 35 μm.
[0052] In some embodiments, the electrolyte includes at least one of sulfuric acid and chloride ions and copper sulfate pentahydrate; the concentration of copper sulfate pentahydrate is 55-80 g / L; the concentration of sulfuric acid is 170-240 g / L; and the concentration of chloride ions is 25-80 ppm. 2+ And enhance conductivity; sulfuric acid is used to improve conductivity and electroplating uniformity; chloride ions are used to promote anode dissolution and enhance Cu precipitation and crystallization.
[0053] In some embodiments, the electrolyte further comprises a leveling agent, a brightener and a wetting agent; the concentration of the leveling agent is 8 to 27 ml / L; the concentration of the brightener is 0.1 to 0.52 ml / L. The wetting agent works synergistically with the leveling agent and the brightener; the leveling agent is used to improve the flatness of the electroplated layer; the brightener is used to reduce the surface impedance of the electroplated layer and improve the crystal quality and ductility of the electroplated layer.
[0054] In some embodiments, after forming the copper layer and the air layer, it also includes: forming a stacked titanium layer, a platinum layer and a gold layer on the side of the copper layer away from the semiconductor substrate. Specifically, a titanium layer, a platinum layer and a gold layer can be sputtered on the surface of the copper layer in sequence using a magnetron sputtering device to form a Ti / Pt / Au stacked structure. In this way, when welding the laser chip, a welding gap between the copper layer and the AuSn solder is avoided, thereby avoiding affecting the light emitting effect of the laser chip. Optionally, the thickness of the titanium layer is 20 to 32 nm, the thickness of the platinum layer is 20 to 32 nm, and the thickness of the gold layer is 120 to 170 nm.
[0055] S150, forming a second electrode layer on a side of the semiconductor substrate away from the semiconductor epitaxial structure layer.
[0056] Specifically, refer to Fig. 9 The semiconductor substrate 10 may be thinned and polished first, and then a second electrode layer 50 may be prepared on a side of the semiconductor substrate 10 away from the semiconductor epitaxial structure layer 20. The second electrode layer 50 may be an n-type contact electrode. Slicing, cleavage, coating and splitting are then performed to form a semiconductor laser chip.
[0057] In some embodiments, after forming the second electrode layer, the method further includes: attaching a heat sink to a side of the first electrode layer away from the semiconductor substrate. Fig.10 , the heat sink 60 is mounted on the side of the first electrode layer 30 away from the semiconductor substrate 10, and the heat sink 60 is in contact with the copper layer 41, so that the copper layer 41 forms a micro-heat channel for heat conduction from the laser chip to the heat sink 60. In this embodiment, the heat in the central area of the laser chip can be conducted to the heat sink 60 through the copper layer 41, while the heat in the edge area of the laser chip is blocked by the air layer 42 and accumulates in the edge area of the laser chip, making the temperature distribution inside the laser chip more uniform, thereby suppressing the "thermal lens effect" of the laser chip and improving the beam quality of the laser output.
[0058] refer to Fig.11 , (a) is a simulation diagram of the heat flux distribution of an ordinary (existing) laser (N-LD), (b) is a simulation diagram of the heat flux distribution of a laser (MCAS-LD) provided in an embodiment of the present application, (c) is a simulation diagram of the temperature distribution of an ordinary (existing) laser (N-LD), and (d) is a simulation diagram of the temperature distribution of a laser (MCAS-LD) provided in an embodiment of the present application. Exemplarily, the active area strip width of N-LD and MCAS-LD is 100μm, and the laser thermal power is 10W. It can be seen from the simulation results that the heat flux of N-LD is distributed in the active area and on both sides of it, and its internal temperature distribution shows the characteristics of high in the central area and low in the edge area, resulting in uneven temperature distribution, which in turn causes uneven refractive index distribution, forming a "thermal lens effect", affecting the beam quality of the laser output. The heat flow of the MCAS-LD used in this application is basically transmitted from the active area directly below to the heat sink. The air layer on both sides of the active area has a low thermal conductivity due to the material used, which hinders the transmission of the heat flow, forming heat accumulation on both sides of the active area, making the temperature distribution more uniform, thereby suppressing the "thermal lens effect" of the laser and improving the beam quality of the laser. In addition, Fig.12 The temperature distribution curves of the common (existing) laser (N-LD) and the laser (MCAS-LD) provided in the embodiment of the present application along the slow axis direction in the active region are shown. Fig.12(The horizontal axis 0 is the center of the active area) It can be seen that the temperature difference between the center and edge of the N-LD active area is 1.8°C, while the temperature difference between the center and edge of the MCAS-LD active area of the present application is only 0.6°C, and the temperature distribution uniformity is improved by 66.7%, thereby reducing the refractive index change caused by temperature change, improving the focal length of the thermal lens, and then reducing the slow axis divergence angle of the laser chip, and improving the beam quality. According to the simulation results, through theoretical calculations, the equivalent thermal lens focal length of N-LD is about 242.5μm, and the slow axis divergence angle is about 11.65°, while the equivalent thermal lens focal length of the MCAS-LD of the present application is about 550.6μm, and the slow axis divergence angle is only 5.19°, which is an increase of about 55.5%. Its slow axis far-field divergence angle characteristics are better and the beam quality is better.
[0059] The preparation method of the laser chip provided in the embodiment of the present application is to form a copper layer and an air layer in contact with the first electrode layer on the side of the first electrode layer away from the semiconductor substrate, and the copper layer is located in the current injection area, and the air layer is located in the non-injection area. Since the material of the copper layer is a high thermal conductivity material, the copper layer is set in the current injection area with a corresponding higher temperature, which can effectively conduct the heat from the center of the laser chip; at the same time, since the material of the air layer is a low thermal conductivity material, the air layer is formed in the non-injection area with a corresponding lower temperature, which can effectively limit the heat from the edge of the laser chip to the outside. In this way, through the mutual cooperation of the copper layer and the air layer, the internal temperature of the laser chip can be regulated, so that the internal center temperature of the laser chip drops rapidly, while the internal edge temperature of the laser chip drops slowly, thereby balancing the internal center temperature and edge temperature of the laser chip, making the internal temperature distribution of the laser chip more uniform, suppressing the increase of the divergence angle of the light beam in the slow axis, thereby improving the quality of the laser output light beam, and further improving the imaging quality of the laser projection device. In addition, forming a copper layer on the side of the first electrode layer away from the semiconductor substrate can reduce the stress problem caused by high temperature eutectic during packaging and improve the reliability of the packaged device. Moreover, the copper layer is directly formed on the first electrode layer, and it is easy to align with the current injection area during the formation process (for example, using a photolithography process). Compared with the related technology of improving the beam quality by changing the heat sink structure, this application can achieve patch packaging without the need for precise mounting with the heat sink during patch packaging, greatly reducing the process difficulty. In addition, electroplated copper has better thermal conductivity, low material cost, simpler preparation method, and low process complexity, which is conducive to mass production.
[0060] In addition, the embodiment of the present application also provides a laser projection device, Fig.13 FIG. 4 shows a block diagram of a laser projection device in some embodiments. Fig.13As shown, the laser projection device includes: a display control component 1, a light source driving component 2, a light source 3, a light valve 4 and a lens 5; the display control component 1 is connected to the light source driving component 2 and the light valve 4 respectively, and the light source driving component 2 is also connected to the light source 3;
[0061] The light source includes at least one laser chip, and the laser chip includes:
[0062] Semiconductor substrate;
[0063] A semiconductor epitaxial structure layer, the semiconductor epitaxial structure layer is located on one side of the semiconductor substrate, and the semiconductor epitaxial structure layer includes a current injection region and a non-injection region;
[0064] A first electrode layer, the first electrode layer is located on a side of the semiconductor epitaxial structure layer away from the semiconductor substrate;
[0065] A thermal conductivity structure layer, the thermal conductivity structure layer is located on a side of the first electrode layer away from the semiconductor substrate and in contact with the first electrode layer, the thermal conductivity structure layer comprising a copper layer located in a current injection region and an air layer located in a non-injection region;
[0066] The second electrode layer is located on a side of the semiconductor substrate away from the semiconductor epitaxial structure layer.
[0067] The laser chip in the laser projection device provided in this embodiment is a laser chip prepared by the laser chip preparation method provided in the embodiment of the present application, and the related structure and function are not described in detail here.
[0068] The laser projection device provided in this embodiment has a laser chip prepared by the laser chip preparation method provided in the embodiment of the present application, because it can improve the imaging quality of laser projection.
[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.
[0070] For the convenience of explanation, the above description has been made in conjunction with specific embodiments. However, the above exemplary discussion is not intended to be exhaustive or limit the embodiments to the specific forms disclosed above. Based on the above teachings, various modifications and variations can be obtained. The selection and description of the above embodiments are to better explain the principles and practical applications, so that those skilled in the art can better use the embodiments and various different variations of the embodiments suitable for specific use considerations.
Claims
1. A method for preparing a laser chip, characterized in that: The laser chip is applied to a laser projection device, and the preparation method of the laser chip comprises: providing a semiconductor substrate; Forming a semiconductor epitaxial structure layer on one side of the semiconductor substrate, wherein the semiconductor epitaxial structure layer includes a current injection region and a non-injection region; forming a first electrode layer on a side of the semiconductor epitaxial structure layer away from the semiconductor substrate; forming a copper layer and an air layer in contact with the first electrode layer on a side of the first electrode layer away from the semiconductor substrate, wherein the copper layer is located in the current injection region, and the air layer is located in the non-injection region; A second electrode layer is formed on a side of the semiconductor substrate away from the semiconductor epitaxial structure layer.
2. The method for preparing a laser chip according to claim 1, characterized in that: A copper layer and an air layer in contact with the first electrode layer are formed on a side of the first electrode layer away from the semiconductor substrate, comprising: Using a photolithography process, a copper-plated window is formed in a region of the first electrode layer that is away from the semiconductor substrate and corresponds to the current injection region; Placing the laser chip with the copper-plated window in an electrolyte and plating copper in the current injection area to form the copper layer; The photoresist and copper on the non-implantation area are removed to form the air layer.
3. The method for preparing a laser chip according to claim 2, characterized in that: Plating copper in the current injection area comprises: The temperature of the electrolyte is controlled to be 20-30°C, and the current density of the DC power supply is 27-35 mA / cm 2 , the electroplating time is 8 to 20 minutes.
4. The method for preparing a laser chip according to claim 2, characterized in that: The copper layer has a thickness of 5 to 35 μm.
5. The method for preparing a laser chip according to claim 2, characterized in that: The electrolyte includes at least one of sulfuric acid and chloride ions and copper sulfate pentahydrate; The concentration of the copper sulfate pentahydrate is 55-80 g / L; The concentration of the sulfuric acid is 170-240 g / L; The concentration of the chloride ions is 25 to 80 ppm.
6. The method for preparing a laser chip according to claim 5, characterized in that: The electrolyte also includes a leveling agent, a brightener and a wetting agent; The concentration of the leveling agent is 8-27 ml / L; The concentration of the brightener is 0.1-0.52 ml / L.
7. The method for preparing a laser chip according to claim 1, characterized in that: After forming the copper layer and the air layer, the method further comprises: A stacked titanium layer, a platinum layer and a gold layer are formed on a side of the copper layer away from the semiconductor substrate.
8. The method for preparing a laser chip according to claim 7, characterized in that: The thickness of the titanium layer is 20-32 nm, the thickness of the platinum layer is 20-32 nm, and the thickness of the gold layer is 120-170 nm.
9. The method for preparing a laser chip according to claim 1, characterized in that: After forming the second electrode layer, the method further includes: A heat sink is mounted on a side of the first electrode layer away from the semiconductor substrate.
10. A laser projection device, characterized in that: include: Display control assembly, light source driving assembly, light source, light valve and lens; The display control component is connected to the light source driving component and the light valve respectively, and the light source driving component is also connected to the light source; The light source includes at least one laser chip, and the laser chip includes: Semiconductor substrate; A semiconductor epitaxial structure layer, the semiconductor epitaxial structure layer is located on one side of the semiconductor substrate, and the semiconductor epitaxial structure layer includes a current injection region and a non-injection region; a first electrode layer, the first electrode layer being located on a side of the semiconductor epitaxial structure layer away from the semiconductor substrate; a thermal conductivity structural layer, the thermal conductivity structural layer being located on a side of the first electrode layer away from the semiconductor substrate and in contact with the first electrode layer, the thermal conductivity structural layer comprising a copper layer located in the current injection region and an air layer located in the non-injection region; A second electrode layer, wherein the second electrode layer is located on a side of the semiconductor substrate away from the semiconductor epitaxial structure layer.