VCSEL chip metal etching method

Abstract

The invention discloses a VCSEL chip metal etching method, and relates to the technical field of etching, in order to avoid the roughness problem after dry etching, the VCSEL chip metal etching method is improved, firstly, positive photoresist is used as a mask for a VCSEL chip epitaxial wafer, after the surface of the VCSEL chip epitaxial wafer is exposed, the surface of the VCSEL chip epitaxial wafer is exposed, and then the surface of the VCSEL chip epitaxial wafer is exposed; according to the method, the surface of an epitaxial wafer is preliminarily etched through dry etching, during dry etching, BCl2 and Cl2 are used as etching gases, nitrogen is added to induce generation of a passivation layer and prevent generation of transverse etching, and on the basis, etching liquid is used to etch and level the VCSEL chip epitaxial wafer, so that the surface of the VCSEL chip is smooth. According to the method, the etching of phosphoric acid is facilitated after potassium permanganate is utilized to oxidize the uneven etching area, and in order to avoid the defect of oxidation spots caused by too strong oxidability, the content of potassium permanganate is strictly limited, so that the flattening treatment of the VCSEL chip epitaxial wafer after dry etching is realized, and the etching quality of the VCSEL chip is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of etching, in particular to a VCSEL chip metal etching method. Background Art

[0002] Due to their unique properties, GaAs-based materials are widely used in a variety of fields, including semiconductor lasers, photodetectors, and aerospace components. They play a particularly crucial role in semiconductor laser manufacturing. GaAs-based VCSELs (Vertical Cavity Surface-Emitting Lasers) have been widely used in fields such as 3D imaging, autonomous driving, the Internet of Things, and data communications. They also demonstrate significant potential and applications in advanced technologies such as optoelectronic warfare, LiDAR, and aerospace. Etching technology is a crucial step in the fabrication of GaAs-based VCSELs, and the etching process is closely aligned with photolithography. The choice of etching process significantly impacts the quality of the photolithography mask, which in turn significantly affects the quality of the GaAs surface after etching, ultimately directly impacting the device's performance. Currently, VCSEL etching is primarily performed using wet and dry etching methods. Dry etching involves etching unprotected wafers through plasma bombardment or corrosive gases. Due to its advantages, such as high precision, good controllability, suitability for mass production, and high process cleanliness, dry etching is generally used for GaAs-based VCSELs to ensure precise morphology control. However, GaAs-based VCSELs suffer from surface roughness after dry etching, necessitating further improvements to the etching process. Summary of the Invention

[0003] The object of the present invention is to provide a VCSEL chip metal etching method to solve the problems raised in the prior art.

[0004] To achieve the above object, the present invention provides the following technical solution: a VCSEL chip metal etching method, comprising the following steps: S1. After ultrasonic cleaning of the epitaxial wafer, its surface was dried to dryness, and a photoresist was spin-coated on its surface and dried at 100-110 ° C for 10 minutes. After cooling to room temperature, the surface was exposed and developed, and then heated to 100-110 ° C again, and the film was dried for 10 minutes and set aside. Wherein, the preparation method of the photoresist is: After mixing n-butyl acrylate and phenolic resin, solvent and leveling agent are added, and the mixture is continued for 10-15 minutes, and then vacuum degassing is performed. Then, diazonaphthoquinone sensitizer is added again, and the mixture is continued for 5-10 minutes, and then vacuum degassing is performed to obtain a photoresist. S2. The developed epitaxial wafer is placed in a plasma chamber, filled with an etching gas, and the surface of the epitaxial wafer is etched once; S3. The potassium permanganate phosphate etching solution was cooled to 0-2 ° C, and the epitaxial wafer after the primary etching was added thereto, ultrasonically shaken, and treated for 150-200 seconds. The epitaxial wafer was removed and rinsed with deionized water, and then placed in anhydrous acetone again, ultrasonically shaken and cleaned for 10 minutes, and then ultrasonically cleaned with anhydrous ethanol for 10-20 minutes and set aside; S4. Remove the photoresist on the surface of the epitaxial wafer after the treatment in step S3, wash it again with acetone and anhydrous ethanol for 10-15 minutes respectively, heat it to 100-110°C, dry it for 5-10 minutes, and complete the etching.

[0005] Furthermore, in step S1, when cleaning the epitaxial wafer, acetone, deionized water and anhydrous ethanol at a temperature of 45-55° C. are used to wash the surface for 10-20 minutes respectively.

[0006] Furthermore, in step S1, the photoresist is composed of 2.4-5 parts of n-butyl acrylate, 10-15 parts of phenolic resin, 20-60 parts of solvent, 0.05-0.15 parts of leveling agent and 2-4 parts of diazonaphthoquinone sensitizer, in parts by weight; Wherein, the solvent is at least one of acetone and butyl acetate; and the leveling agent is vinyltriethoxysilane.

[0007] Furthermore, in step S2, the etching gas is composed of BCl3, Cl2, and N2 in a volume ratio of (1-1.5):1:1.

[0008] Furthermore, in step S2, the total gas flow rate of the etching gas is 80-200 sccm.

[0009] Furthermore, in step S2, during etching, the bias power is set to 200-300W and the inductively coupled plasma power is set to 300-800W.

[0010] Furthermore, in step S3, the potassium permanganate phosphate etching solution is prepared as follows: After nitrogen is passed through deionized water for 15-30 minutes, phosphoric acid is added thereto, and ultrasonic vibration is carried out for 30-60 minutes. Potassium permanganate is added again, and ultrasonic vibration is continued for 10-30 minutes to obtain a phosphoric acid and potassium permanganate etching solution.

[0011] Furthermore, in step S3, the ratio of phosphoric acid: potassium permanganate: deionized water in the potassium permanganate phosphate etching solution is 70-95 g: 3-7 g: 1 L.

[0012] Compared with the prior art, the present invention has the following beneficial effects: In order to avoid the roughness problem after dry etching, the present invention improves the metal etching method of VCSEL chip; The two-step method first uses a photoresist as a mask for a VCSEL chip epitaxial wafer. The photoresist prepared by the present invention is a diazonaphthoquinone photoresist using a positive photosensitizer, which has high precision and can better protect the VCSEL chip epitaxial wafer. After the surface is exposed, the epitaxial wafer surface is preliminarily etched by dry etching. During the dry etching, the present invention uses BCl2 and Cl2 as etching gases, and nitrogen is added thereto to induce the formation of a passivation layer, thereby preventing the generation of lateral etching that affects the quality of the VCSEL chip. On this basis, the present invention also uses an etching liquid to etch and smooth the VCSEL chip epitaxial wafer. The present invention uses phosphoric acid as a hydrogen ion donor in the etching liquid and uses potassium permanganate with strong oxidizing properties as a raw material. After the uneven etched area is oxidized by potassium permanganate, it is easy to etch with phosphoric acid. In order to avoid the defect of oxidation spots in the etched area caused by excessive oxidizing properties, the present invention also strictly limits the potassium permanganate content. By controlling the potassium permanganate content, the VCSEL chip epitaxial wafer after dry etching is smoothed, which effectively improves the etching quality of the VCSEL chip, thereby improving the consistency and reliability of the device, and fully ensuring the subsequent interlayer bonding, optical performance and laser efficiency. DETAILED DESCRIPTION

[0013] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

[0014] The preparation method of the photoresist used in the examples of this application is: After mixing 4 parts of n-butyl acrylate resin and 12 parts of phenolic resin by weight, 45 parts of butyl acetate solvent and 0.1 parts of vinyltriethoxysilane were added, and the mixture was continued for 15 minutes, and then vacuum-defoamed. 3 parts of diazonaphthoquinone sensitizer were added again, and the mixture was continued for 8 minutes. After vacuum-defoamed, a photoresist was obtained; The phenolic resin used in this application is commercially available SH-3088 linear phenolic resin.

[0015] Example 1. A VCSEL chip metal etching method comprising the following steps: S1. Place a GaAs-based VCSEL epitaxial wafer in acetone, deionized water, and anhydrous ethanol at 50±2°C, respectively. Ultrasonic clean the surface for 10 minutes in each of the following conditions. After drying, spin-coat the surface with AZ5214 photoresist, heat to 100°C, and dry for 10 minutes. After cooling to room temperature, expose and develop the surface using an ABM Inc. UV exposure system at a wavelength of 365nm. After exposure and development, heat the surface again to 110°C and dry for 10 minutes before setting aside. S2. The developed epitaxial wafer is placed in a plasma chamber, which is filled with an etching gas composed of BCl3, Cl2, and N2 in a volume ratio of 1:1:1. The total gas flow rate of the etching gas is controlled to 100 sccm, the bias power is set to 200W, the inductively coupled plasma power is 400W, and the surface of the epitaxial wafer is etched once; S3. The potassium permanganate phosphate etching solution was cooled to 0-2°C, and the epitaxial wafer after the primary etching was added thereto, ultrasonically shaken, and treated for 150 seconds. The epitaxial wafer was removed and rinsed with deionized water, and then placed in anhydrous acetone again, ultrasonically shaken and cleaned for 10 minutes, and then ultrasonically cleaned again with anhydrous ethanol for 20 minutes, and then set aside; Wherein, the configuration method of the potassium permanganate phosphate etching solution is: After nitrogen was passed through deionized water for 18 minutes, phosphoric acid was added thereto, and after ultrasonic vibration treatment for 30 minutes, potassium permanganate was added again, and ultrasonic vibration treatment was continued for 25 minutes to obtain a potassium permanganate phosphate etching solution, wherein the ratio of phosphoric acid: potassium permanganate: deionized water in the potassium permanganate phosphate etching solution was 70g:3g:1L; S4. Remove the photoresist on the surface of the epitaxial wafer after the treatment in step S3, wash it again with acetone and anhydrous ethanol for 10 minutes respectively, heat it to 110°C, dry it for 8 minutes, and then complete the etching.

[0016] Example 2. A VCSEL chip metal etching method comprising the following steps: Compared with Example 1, this embodiment increases the proportion of BCl3 in step S2; S1. Place a GaAs-based VCSEL epitaxial wafer in acetone, deionized water, and anhydrous ethanol at 50±2°C, respectively. Ultrasonic clean the surface for 10 minutes in each of the following conditions. After drying, spin-coat the surface with AZ5214 photoresist, heat to 100°C, and dry for 10 minutes. After cooling to room temperature, expose and develop the surface using an ABM Inc. UV exposure system at a wavelength of 365nm. After exposure and development, heat the surface again to 110°C and dry for 10 minutes before setting aside. S2. The developed epitaxial wafer is placed in a plasma chamber, which is filled with an etching gas composed of BCl3, Cl2, and N2 in a volume ratio of 1.2:1:1. The total gas flow rate of the etching gas is controlled to 100 sccm, the bias power is set to 200W, the inductively coupled plasma power is 400W, and the surface of the epitaxial wafer is etched once; S3. The potassium permanganate phosphate etching solution was cooled to 0-2°C, and the epitaxial wafer after the primary etching was added thereto, ultrasonically shaken, and treated for 150 seconds. The epitaxial wafer was removed and rinsed with deionized water, and then placed in anhydrous acetone again, ultrasonically shaken and cleaned for 10 minutes, and then ultrasonically cleaned again with anhydrous ethanol for 20 minutes, and then set aside; Wherein, the configuration method of the potassium permanganate phosphate etching solution is: After nitrogen was passed through deionized water for 18 minutes, phosphoric acid was added thereto, and after ultrasonic vibration treatment for 30 minutes, potassium permanganate was added again, and ultrasonic vibration treatment was continued for 25 minutes to obtain a potassium permanganate phosphate etching solution, wherein the ratio of phosphoric acid: potassium permanganate: deionized water in the potassium permanganate phosphate etching solution was 70g:3g:1L; S4. Remove the photoresist on the surface of the epitaxial wafer after the treatment in step S3, wash it again with acetone and anhydrous ethanol for 10 minutes respectively, heat it to 110°C, dry it for 8 minutes, and then complete the etching.

[0017] Example 3. A VCSEL chip metal etching method comprising the following steps: Compared with Example 1, this embodiment increases the proportion of BCl3 in step S2. S1. Place a GaAs-based VCSEL epitaxial wafer in acetone, deionized water, and anhydrous ethanol at 50±2°C, respectively. Ultrasonic clean the surface for 10 minutes in each of the following conditions. After drying, spin-coat the surface with AZ5214 photoresist, heat to 100°C, and dry for 10 minutes. After cooling to room temperature, expose and develop the surface using an ABM Inc. UV exposure system at a wavelength of 365nm. After exposure and development, heat the surface again to 110°C and dry for 10 minutes before setting aside. S2. The developed epitaxial wafer is placed in a plasma chamber, which is filled with an etching gas composed of BCl3, Cl2, and N2 in a volume ratio of 1.5:1:1. The total gas flow rate of the etching gas is controlled to be 100 sccm, the bias power is set to 200W, the inductively coupled plasma power is 400W, and the surface of the epitaxial wafer is etched once; S3. The potassium permanganate phosphate etching solution was cooled to 0-2°C, and the epitaxial wafer after the primary etching was added thereto, ultrasonically shaken, and treated for 150 seconds. The epitaxial wafer was removed and rinsed with deionized water, and then placed in anhydrous acetone again, ultrasonically shaken and cleaned for 10 minutes, and then ultrasonically cleaned again with anhydrous ethanol for 20 minutes, and then set aside; Wherein, the configuration method of the potassium permanganate phosphate etching solution is: After nitrogen was passed through deionized water for 18 minutes, phosphoric acid was added thereto, and after ultrasonic vibration treatment for 30 minutes, potassium permanganate was added again, and ultrasonic vibration treatment was continued for 25 minutes to obtain a potassium permanganate phosphate etching solution, wherein the ratio of phosphoric acid: potassium permanganate: deionized water in the potassium permanganate phosphate etching solution was 70g:3g:1L; S4. Remove the photoresist on the surface of the epitaxial wafer after the treatment in step S3, wash it again with acetone and anhydrous ethanol for 10 minutes respectively, heat it to 110°C, dry it for 8 minutes, and then complete the etching.

[0018] Example 4. A VCSEL chip metal etching method comprising the following steps: Compared with Example 1, this embodiment increases the etching time in step S3; S1. Place a GaAs-based VCSEL epitaxial wafer in acetone, deionized water, and anhydrous ethanol at 50±2°C, respectively. Ultrasonic clean the surface for 10 minutes in each of the following conditions. After drying, spin-coat the surface with AZ5214 photoresist, heat to 100°C, and dry for 10 minutes. After cooling to room temperature, expose and develop the surface using an ABM Inc. UV exposure system at a wavelength of 365nm. After exposure and development, heat the surface again to 110°C and dry for 10 minutes before setting aside. S2. The developed epitaxial wafer is placed in a plasma chamber, which is filled with an etching gas composed of BCl3, Cl2, and N2 in a volume ratio of 1:1:1. The total gas flow rate of the etching gas is controlled to 100 sccm, the bias power is set to 200W, the inductively coupled plasma power is 400W, and the surface of the epitaxial wafer is etched once; S3. The potassium permanganate phosphate etching solution was cooled to 0-2°C, and the epitaxial wafer after the primary etching was added thereto, ultrasonically shaken, and treated for 180 seconds. The epitaxial wafer was removed and rinsed with deionized water, and then placed in anhydrous acetone again, ultrasonically shaken and cleaned for 10 minutes, and then ultrasonically cleaned again with anhydrous ethanol for 20 minutes, and then set aside; Wherein, the configuration method of the potassium permanganate phosphate etching solution is: After nitrogen was passed through deionized water for 18 minutes, phosphoric acid was added thereto, and after ultrasonic vibration treatment for 30 minutes, potassium permanganate was added again, and ultrasonic vibration treatment was continued for 25 minutes to obtain a potassium permanganate phosphate etching solution, wherein the ratio of phosphoric acid: potassium permanganate: deionized water in the potassium permanganate phosphate etching solution was 70g:3g:1L; S4. Remove the photoresist on the surface of the epitaxial wafer after the treatment in step S3, wash it again with acetone and anhydrous ethanol for 10 minutes respectively, heat it to 110°C, dry it for 8 minutes, and then complete the etching.

[0019] Example 5. A VCSEL chip metal etching method comprising the following steps: Compared with Example 1, this embodiment increases the etching time in step S3; S1. Place a GaAs-based VCSEL epitaxial wafer in acetone, deionized water, and anhydrous ethanol at 50±2°C, respectively. Ultrasonic clean the surface for 10 minutes in each of the following conditions. After drying, spin-coat the surface with AZ5214 photoresist, heat to 100°C, and dry for 10 minutes. After cooling to room temperature, expose and develop the surface using an ABM Inc. UV exposure system at a wavelength of 365nm. After exposure and development, heat the surface again to 110°C and dry for 10 minutes before setting aside. S2. The developed epitaxial wafer is placed in a plasma chamber, which is filled with an etching gas composed of BCl3, Cl2, and N2 in a volume ratio of 1:1:1. The total gas flow rate of the etching gas is controlled to 100 sccm, the bias power is set to 200W, the inductively coupled plasma power is 400W, and the surface of the epitaxial wafer is etched once; S3. The potassium permanganate phosphate etching solution was cooled to 0-2 ° C, and the epitaxial wafer after the primary etching treatment was added thereto, ultrasonically shaken, and treated for 200 seconds. The epitaxial wafer was removed and rinsed with deionized water, and then placed in anhydrous acetone again, ultrasonically shaken and cleaned for 10 minutes, and then ultrasonically cleaned again with anhydrous ethanol for 20 minutes and set aside; Wherein, the configuration method of the potassium permanganate phosphate etching solution is: After nitrogen was passed through deionized water for 18 minutes, phosphoric acid was added thereto, and after ultrasonic vibration treatment for 30 minutes, potassium permanganate was added again, and ultrasonic vibration treatment was continued for 25 minutes to obtain a potassium permanganate phosphate etching solution, wherein the ratio of phosphoric acid: potassium permanganate: deionized water in the potassium permanganate phosphate etching solution was 70g:3g:1L; S4. Remove the photoresist on the surface of the epitaxial wafer after the treatment in step S3, wash it again with acetone and anhydrous ethanol for 10 minutes respectively, heat it to 110°C, dry it for 8 minutes, and then complete the etching.

[0020] Example 6. A VCSEL chip metal etching method comprising the following steps: Compared with Example 1, this embodiment increases the amount of potassium permanganate added in step S3; S1. Place a GaAs-based VCSEL epitaxial wafer in acetone, deionized water, and anhydrous ethanol at 50±2°C, respectively. Ultrasonic clean the surface for 10 minutes in each of the following conditions. After drying, spin-coat the surface with AZ5214 photoresist, heat to 100°C, and dry for 10 minutes. After cooling to room temperature, expose and develop the surface using an ABM Inc. UV exposure system at a wavelength of 365nm. After exposure and development, heat the surface again to 110°C and dry for 10 minutes before setting aside. S2. The developed epitaxial wafer is placed in a plasma chamber, which is filled with an etching gas composed of BCl3, Cl2, and N2 in a volume ratio of 1.2:1:1. The total gas flow rate of the etching gas is controlled to 100 sccm, the bias power is set to 200W, the inductively coupled plasma power is 400W, and the surface of the epitaxial wafer is etched once; S3. The potassium permanganate phosphate etching solution was cooled to 0-2°C, and the epitaxial wafer after the primary etching was added thereto, ultrasonically shaken, and treated for 150 seconds. The epitaxial wafer was removed and rinsed with deionized water, and then placed in anhydrous acetone again, ultrasonically shaken and cleaned for 10 minutes, and then ultrasonically cleaned again with anhydrous ethanol for 20 minutes, and then set aside; Wherein, the configuration method of the potassium permanganate phosphate etching solution is: After nitrogen was passed through deionized water for 18 minutes, phosphoric acid was added thereto, and after ultrasonic vibration treatment for 30 minutes, potassium permanganate was added again, and ultrasonic vibration treatment was continued for 25 minutes to obtain a potassium permanganate phosphate etching solution, wherein the ratio of phosphoric acid: potassium permanganate: deionized water in the potassium permanganate phosphate etching solution was 70g:5g:1L; S4. Remove the photoresist on the surface of the epitaxial wafer after the treatment in step S3, wash it again with acetone and anhydrous ethanol for 10 minutes respectively, heat it to 110°C, dry it for 8 minutes, and then complete the etching.

[0021] Example 7. A VCSEL chip metal etching method comprising the following steps: Compared with Example 1, this embodiment increases the proportion of potassium permanganate in step S3; S1. Place a GaAs-based VCSEL epitaxial wafer in acetone, deionized water, and anhydrous ethanol at 50±2°C, respectively. Ultrasonic clean the surface for 10 minutes in each of the following conditions. After drying, spin-coat the surface with AZ5214 photoresist, heat to 100°C, and dry for 10 minutes. After cooling to room temperature, expose and develop the surface using an ABM Inc. UV exposure system at a wavelength of 365nm. After exposure and development, heat the surface again to 110°C and dry for 10 minutes before setting aside. S2. The developed epitaxial wafer is placed in a plasma chamber, which is filled with an etching gas composed of BCl3, Cl2, and N2 in a volume ratio of 1:1:1. The total gas flow rate of the etching gas is controlled to 100 sccm, the bias power is set to 200W, the inductively coupled plasma power is 400W, and the surface of the epitaxial wafer is etched once; S3. Cool the potassium permanganate phosphate etching solution to 0-2°C, add the etched epitaxial wafer, and ultrasonically vibrate for 150 seconds. Then, remove the epitaxial wafer and rinse it with deionized water. Then, place it in anhydrous acetone and ultrasonically clean it for 10 minutes. Then, ultrasonically clean it again with anhydrous ethanol for 20 minutes and set aside. Wherein, the configuration method of the potassium permanganate phosphate etching solution is: After nitrogen was passed through deionized water for 18 minutes, phosphoric acid was added thereto, and after ultrasonic vibration treatment for 30 minutes, potassium permanganate was added again, and ultrasonic vibration treatment was continued for 25 minutes to obtain a potassium permanganate phosphate etching solution, wherein the ratio of phosphoric acid: potassium permanganate: deionized water in the potassium permanganate phosphate etching solution was 70g:6g:1L; S4. Remove the photoresist on the surface of the epitaxial wafer after the treatment in step S3, wash it again with acetone and anhydrous ethanol for 10 minutes respectively, heat it to 110°C, dry it for 8 minutes, and then complete the etching.

[0022] Comparative Example 1. A VCSEL chip metal etching method comprising the following steps: Compared with Example 1, this comparative example did not perform the original S3 step treatment; S1. Place the GaAs-based VCSEL epitaxial wafer in acetone, deionized water, and anhydrous ethanol at 50±2°C, ultrasonically clean the surface for 10 minutes each. After drying, spin-coat AZ5214 photoresist on the surface. Heat the wafer to 100°C and dry for 10 minutes. After cooling to room temperature, expose and develop the wafer using an ABM Inc. UV exposure system at a wavelength of 365nm. After exposure and development, heat the wafer to 110°C again and dry the film for 10 minutes before setting aside. S2. The developed epitaxial wafer is placed in a plasma chamber and filled with an etching gas composed of BCl3, Cl2, and N2 in a volume ratio of 1:1:1. The total etching gas flow rate is controlled to 100 sccm, the bias power is set to 200 W, and the inductively coupled plasma power is set to 400 W. The epitaxial wafer surface is etched once. S3. Remove the photoresist from the epitaxial wafer surface, wash again with acetone and anhydrous ethanol for 10 minutes each, heat to 110°C, and dry for 8 minutes to complete the etching.

[0023] Comparative Example 2. A VCSEL chip metal etching method comprising the following steps: Compared with Example 1, this comparative example did not perform the original step S2 treatment; S1. Place the GaAs-based VCSEL epitaxial wafer in acetone, deionized water, and anhydrous ethanol at 50±2°C, ultrasonically clean the surface for 10 minutes each. After drying, spin-coat AZ5214 photoresist on the surface. Heat the wafer to 100°C and dry for 10 minutes. After cooling to room temperature, expose and develop the wafer using an ABM Inc. UV exposure system at a wavelength of 365nm. After exposure and development, heat the wafer to 110°C again and dry the film for 10 minutes before setting aside. S2. Cool the potassium permanganate phosphate etching solution to 0-2°C, add the epitaxial wafer, and ultrasonically vibrate for 150 seconds. Then, remove the epitaxial wafer and rinse it with deionized water. Then, place it in anhydrous acetone and ultrasonically clean it for 10 minutes. Then, ultrasonically clean it again with anhydrous ethanol for 20 minutes and set aside. Wherein, the configuration method of the potassium permanganate phosphate etching solution is: After nitrogen was passed through deionized water for 18 minutes, phosphoric acid was added thereto, and after ultrasonic vibration treatment for 30 minutes, potassium permanganate was added again, and ultrasonic vibration treatment was continued for 25 minutes to obtain a potassium permanganate phosphate etching solution, wherein the ratio of phosphoric acid: potassium permanganate: deionized water in the potassium permanganate phosphate etching solution was 70g:3g:1L; S3. Remove the photoresist on the epitaxial wafer surface treated in step S2, wash again with acetone and anhydrous ethanol for 10 minutes, heat to 110°C, dry for 8 minutes, and complete the etching.

[0024] Testing: The surface roughness of Examples 1-7 and Comparative Example 2 was measured using a step profiler. The test results are shown in the table below.

[0025] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A VCSEL chip metal etching method, characterized in that: The following steps are involved: S1. After ultrasonic cleaning of the epitaxial wafer, the surface is dried to dryness, the surface is spin-coated with photoresist, and the temperature is raised to 100-110 ° C and dried for 10 minutes, then cooled to room temperature and exposed to light and developed, and the temperature is again raised to 100-110 ° C, and the hard film is dried for 10 minutes and set aside; Wherein, the preparation method of the photoresist is: After mixing n-butyl acrylate and phenolic resin, solvent and leveling agent are added, and the mixture is continued for 10-15 minutes, and then vacuum degassing is performed. Then, diazonaphthoquinone sensitizer is added again, and the mixture is continued for 5-10 minutes, and then vacuum degassing is performed to obtain a photoresist. S2. The developed epitaxial wafer is placed in a plasma chamber, into which an etching gas is filled, and the surface of the epitaxial wafer is etched once; S3. Cool the potassium permanganate phosphate etching solution to 0-2°C, add the etched epitaxial wafer, ultrasonically shake it, and treat it for 150-200 seconds. Then, remove the epitaxial wafer and rinse it with deionized water. Then, place it in anhydrous acetone and ultrasonically shake it for 10 minutes. After that, ultrasonically wash it again with anhydrous ethanol for 10-20 minutes and set aside. S4. Remove the photoresist on the epitaxial wafer surface treated in step S3, wash again with acetone and anhydrous ethanol for 10-15 minutes respectively, heat to 100-110°C, dry for 5-10 minutes, and complete the etching.

2. A VCSEL chip metal etching method according to claim 1, characterized in that: In step S1, when cleaning the epitaxial wafer, acetone, deionized water and anhydrous ethanol at a temperature of 45-55° C. are used to wash the surface for 10-20 minutes respectively.

3. A VCSEL chip metal etching method according to claim 1, characterized in that: In step S1, the photoresist is composed of 2.4-5 parts of n-butyl acrylate, 10-15 parts of phenolic resin, 20-60 parts of solvent, 0.05-0.15 parts of leveling agent and 2-4 parts of diazonaphthoquinone sensitizer, in parts by weight; Wherein, the solvent is at least one of acetone and butyl acetate; and the leveling agent is vinyltriethoxysilane.

4. A VCSEL chip metal etching method according to claim 1, characterized in that: In step S2, the etching gas is composed of BCl3, Cl2, and N2 in a volume ratio of (1-1.5):1:

1.

5. A VCSEL chip metal etching method according to claim 1, characterized in that: In step S2, the total gas flow rate of the etching gas is 80-200 sccm.

6. A VCSEL chip metal etching method according to claim 1, characterized in that: In step S2, during etching, the bias power is set to 200-300W and the inductively coupled plasma power is set to 300-800W.

7. A VCSEL chip metal etching method according to claim 1, characterized in that: In step S3, the potassium permanganate phosphate etching solution is prepared as follows: After nitrogen is passed through deionized water for 15-30 minutes, phosphoric acid is added thereto, and ultrasonic vibration is carried out for 30-60 minutes. Potassium permanganate is added again, and ultrasonic vibration is continued for 10-30 minutes to obtain a phosphoric acid and potassium permanganate etching solution.

8. A VCSEL chip metal etching method according to claim 1, characterized in that: In step S3, the ratio of phosphoric acid: potassium permanganate: deionized water in the potassium permanganate phosphate etching solution is 70-95 g: 3-7 g: 1 L.

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