Process method for improving quality of gold-plated gold layer of optical chip electrode

Abstract

The invention discloses a process method for improving the quality of a gold-plated gold layer of an optical chip electrode, and belongs to the technical field of manufacturing and processing of photoelectric chips. According to the method, an electrode window is opened through evaporation, gold plating and photoetching, a Ti-Pt-Au metal electrode is formed through electron beam evaporation and then stripped through an NMP solution, and then the window is opened twice through chemical gold plating and photoetching. And then pre-cleaning by full-automatic equipment to remove residual photoresist and impurities, carrying out surface plasma glow activation, soaking in a surface treatment solution, depositing in a chemical gold plating solution at a proper temperature, then cleaning with warm water, and finally stripping with an NMP (N-Methyl Pyrrolidone) solution and adhering with a blue film to remove residual gold particles. According to the process, the problems of gold precipitation and incomplete patterns caused by surface pollution in the traditional process are solved, the chip is prevented from being scratched during stripping, the deposition uniformity and binding force of the gold layer are improved, and the process stability and the quality of the gold layer are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of photoelectric chip manufacturing and processing, and in particular to a process method for improving the quality of a gold-plated layer of an electrode of a photoelectric chip. Background Art

[0002] Electroless gold plating is a plating method that uses a reducing agent to reduce gold ions and deposit them onto a material surface without an applied current. It boasts uniform coatings, small pinholes, no need for a DC power supply, and can be deposited on non-conductive surfaces. It also produces minimal wastewater, minimizes environmental pollution, and is low-cost, making it a key industry in electronic plating, particularly in semiconductor manufacturing. In the field of optical communications, optical chips, core components for converting electrical and optical signals, traditionally utilize a single evaporation gold plating process for their electrodes. This process has been optimized to a combined "evaporation gold plating + electroless gold plating" process to save costs. Ti-Pt-Au metal electrodes (thicknesses of 700-800Å, 700-800Å, and 5000Å, respectively) are first formed via electron beam evaporation, followed by thickening the gold layer via electroless gold plating. This combined process includes evaporation gold lithography, evaporation gold plating and stripping, electroless gold lithography, electroless gold plating (including plasma glow, surface treatment solution immersion, gold plating solution deposition, and deionized water rinsing), and stripping of the electroless gold-plated electrodes.

[0003] In existing processes, due to process delays after evaporative gold plating or chemical gold plating photolithography, the surface to be plated is susceptible to contamination. Furthermore, chemical gold plating with photoresist violates the process requirement of a "clean surface," leading to problems such as uneven surface gold deposition and incomplete patterns in the plated area. Furthermore, when stripping chemically plated gold electrodes, NMP cotton balls are used to remove residual gold particles. This operation, due to human factors such as force and method, can easily scratch the chip and even damage the completed electrode pattern, affecting the reliability and yield of the optical chip electrodes. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems of gold deposition and incomplete gold-plated area patterns caused by surface contamination due to process delays in the traditional gold-plating process of optical chip electrodes, and chip scratches caused by wiping operations during electrode stripping, and to provide a process method for improving the quality of the gold-plated layer of optical chip electrodes.

[0005] The object of the present invention is achieved through the following technical solutions:

[0006] A process for improving the quality of a gold-plated layer on an optical chip electrode comprises the following steps:

[0007] Evaporation gold plating photolithography: Open the electrode windows of P-type electrode and N-type electrode through photolithography technology;

[0008] Evaporation gold plating: Ti-Pt-Au metal electrodes are formed by electron beam evaporation equipment;

[0009] Evaporation gold electrode stripping: Use 80℃ NMP solution for 10 minutes;

[0010] Chemical gold plating photolithography: open the electrode windows of P-type electrode and N-type electrode again;

[0011] Pre-cleaning before chemical gold plating: Develop with developer for 15 seconds using a fully automatic coating and developing device, then rinse with deionized water and blow dry;

[0012] Surface plasma glow treatment for 2 minutes;

[0013] Soak in the surface treatment liquid for 5 minutes, shaking up and down for 5 seconds while immersing;

[0014] Soak in 55℃ chemical gold plating solution for 20 minutes for chemical gold plating;

[0015] Soak in 40℃ deionized water for 5 minutes;

[0016] Chemical gold-plated electrode stripping: After stripping in 80℃ NMP solution for 10 minutes, use blue film to remove residual gold particles.

[0017] Furthermore, in the pre-cleaning step, after development with the developer, the film is rinsed with a large amount of deionized water and blown dry to remove residual photoresist, surface dust and impurities.

[0018] Furthermore, the surface treatment liquid is shaken up and down for 5 seconds while being immersed to ensure that the chip part at the fixture slot is fully pretreated.

[0019] Furthermore, the temperature of the chemical gold plating solution is 55° C., the gold plating time is 20 minutes, and the gold precipitation is observed during the gold plating process.

[0020] Furthermore, in the chemical gold-plated electrode stripping step, the chip is fixed on a suction cup, and after nitrogen adsorption, it is adhered with a blue film of appropriate viscosity and slowly peeled off to remove residual gold particles.

[0021] Furthermore, the thickness of the gold layer of the evaporated gold plating is 700Å-800Å for Ti, 700Å-800Å for Pt, and 5000Å for Au.

[0022] Furthermore, in the steps of stripping the evaporated gold-plated electrodes and stripping the chemically gold-plated electrodes, the temperature of the NMP solution was 80° C., and the stripping time was 10 minutes.

[0023] Furthermore, the surface plasma glow treatment lasts for 2 minutes.

[0024] Furthermore, the immersion time in 40° C. deionized water is 5 minutes, which is used to clean the gold-plated chip.

[0025] Furthermore, the chemical gold plating photolithography adopts overexposure and overdevelopment processes so that the pre-cleaning step does not affect the photolithography pattern.

[0026] The beneficial effects of the present invention are:

[0027] (1) Pre-cleaning technology is used to remove surface contaminants after evaporation gold plating or chemical gold plating lithography, solving the problem of surface gold precipitation and incomplete pattern of gold-plated area during chemical gold plating;

[0028] (2) Activate the surface to be gold-plated by surface plasma glow and surface treatment liquid immersion to improve the uniformity and bonding strength of the gold layer;

[0029] (3) By using blue film adhesion instead of cotton ball wiping and combining it with automated equipment technology, chip scratches and pattern damage can be avoided, and process stability and gold layer quality consistency can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A flowchart of the process steps for improving the quality of the gold-plated layer of optical chip electrodes provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work shall fall within the scope of protection of the present invention.

[0032] Example 1: See Figure 1 , provides a process method for improving the quality of the gold plating layer of the optical chip electrode, the specific steps comprising:

[0033] 1. Evaporation gold plating lithography: Through photolithography technology, the pattern formed after photolithography is wet-etched or dry-etched to open the electrode windows of the P-type electrode and the N-type electrode.

[0034] 2. Evaporation gold plating: Through electron beam evaporation equipment, P-type and N-type metal electrodes with specific patterns are formed. The thickness of the evaporated gold plating layer is Ti-Pt-Au: 700Å-800Å-5000Å;

[0035] 3. Evaporation gold electrode stripping: 80℃ NMP solution stripping for 10 minutes;

[0036] 4. Chemical gold plating photolithography: The thickness of the evaporated gold plating layer does not meet the thickness requirements of the gold layer of the optoelectronic chip electrode. On the evaporated gold layer, the pattern formed after photolithography is wet-etched or dry-etched through photolithography technology to open the electrode windows of the P-type electrode and N-type electrode again;

[0037] 5. Chemical gold plating: The chemical gold plating process is to control the thickness of the coating by strictly controlling the temperature of the gold plating solution and the plating time during the gold plating process. The chemical gold plating process is specifically divided into the following steps:

[0038] (1) Processing of chips with surface contamination due to process delays after evaporative gold plating or chemical gold plating lithography: Pre-cleaning is performed using a fully automatic photoresist development device. The pre-cleaning process is to develop with developer for 15 seconds, then rinse with a large amount of deionized water and blow dry. Because the previous photolithography conditions are overexposure and overdevelopment, the developer pre-cleaning in this step will not affect the photolithography pattern. On the contrary, the residual photoresist on the photolithography pattern can be removed again after the developer pre-cleaning. The subsequent deionized water cleaning process can further remove the surface dust and impurities caused by the delay time, so that the chip is in a relatively clean state before chemical gold plating.

[0039] (2) Surface plasma glow: The gold-plated chip plasma glows for 2 minutes;

[0040] (3) Surface treatment liquid: Immerse the gold-plated chip in the surface treatment liquid for 5 minutes, and shake it up and down for 5 seconds just after immersion to ensure that the chip part at the fixture slot can be fully pretreated;

[0041] (4) Chemical gold plating solution: Immerse the gold-plated chip in the chemical gold plating solution to start chemical gold plating. The temperature of the gold plating solution is 55° and the plating time is 20 minutes. During the gold plating process, the gold precipitation in the gold plating solution needs to be observed at any time.

[0042] (5) 40℃ deionized water: Immerse the gold-plated chip in 40℃ deionized water for 5 minutes.

[0043] 6. Chemical gold-plated electrode stripping: Strip with 80°C NMP solution for 10 minutes. Rinse the chip surface with plenty of deionized water and blow dry. Fix the chip on the suction cup, turn on the nitrogen adsorption chip, select a blue film with appropriate viscosity to adhere to the chip, and slowly peel off the blue film to remove the residual gold particles precipitated by the chemical gold plating.

[0044] Example 2: Optimization method for gold plating process of optical chip electrodes based on pre-cleaning and blue film stripping

[0045] Process Background and Technical Problem Analysis: In the manufacturing process of optical chip electrodes, the traditional process uses evaporative gold plating followed by direct chemical gold plating for thickening. However, due to process delays after evaporative gold plating or chemical gold plating, the surface to be gold-plated is susceptible to the adsorption of dust, residual photoresist, or the formation of an oxide layer, resulting in uneven gold deposition and incomplete coating patterns during chemical gold plating. In addition, the use of cotton balls in the traditional electrode stripping process can easily scratch the chip surface, affecting electrode performance. This embodiment solves the above technical problems by optimizing the pre-cleaning process and stripping process.

[0046] The specific process steps are as follows:

[0047] Step (1) Evaporation Gold Plating Photolithography: Open the electrode window: Photoresist Coating: Spin-coat the surface of the optical chip substrate with a uniform layer of photoresist. The spin-coating speed is adjusted according to the viscosity of the photoresist to ensure a uniform thickness and no bubbles. After coating, a soft bake is performed to remove the solvent in the photoresist and enhance adhesion to the substrate.

[0048] Exposure and Development: A photolithography machine is used to expose the chip. The exposure energy is set based on the photoresist type and pattern accuracy to ensure a photochemical reaction in the photoresist area of ​​the electrode window. After exposure, a developer is used to dissolve the photoresist in the unexposed areas, forming the window patterns for the P-type and N-type electrodes. The developer temperature and duration must be controlled during the development process to avoid over-development or under-development.

[0049] Etching: After development, the chip is processed using either a wet or dry etching process to remove the surface layer in the electrode window area, exposing the substrate to be plated with gold. The etching rate must be monitored in real time during the etching process to ensure that the window size meets the design requirements.

[0050] Step (2) Evaporation gold plating: Forming the bottom metal electrode: Electron beam evaporation preparation: Place the etched chip into the vacuum chamber of the electron beam evaporation equipment and evacuate it to a predetermined vacuum level to prevent the metal from reacting with impurities in the air during evaporation.

[0051] Metal layer deposition: Three layers of titanium (Ti), platinum (Pt), and gold (Au) are sequentially evaporated. The titanium layer acts as an adhesion layer, enhancing bonding with the substrate; the platinum layer acts as a barrier layer, preventing diffusion between the titanium and gold; and the gold layer acts as a conductive layer, providing good electrical contact. During the evaporation process, a thickness monitor monitors the thickness of each layer in real time, stopping evaporation when the desired thickness is reached.

[0052] Step 3: Stripping of the Evaporated Gold Electrode: Removal of Excess Metal: Stripping Solution Treatment: Immerse the gold-plated chip in a preheated NMP solution to a predetermined temperature to separate the metal layer not protected by the photoresist from the substrate. The stripping time is adjusted based on the thickness of the metal layer and the concentration of the NMP solution to ensure complete stripping of the excess metal.

[0053] Cleaning and drying: After stripping is completed, rinse the chip surface repeatedly with deionized water to remove residual NMP solution and metal debris, and then blow dry with nitrogen or centrifuge to ensure that the chip surface is clean.

[0054] Step 4: Electroless Gold Lithography: Second electrode window opening: Second photoresist coating and exposure: Photoresist is applied again to the chip surface after the gold evaporation process, and a pattern matching the electroless gold-plated area is formed using photolithography. This photolithography process uses overexposure and overdevelopment to reserve process margin for the subsequent pre-cleaning step.

[0055] Secondary etching: Repeat the wet or dry etching process to open the secondary windows of the P-type and N-type electrodes to ensure that the area to be chemically gold-plated is completely exposed.

[0056] Step 5: Pre-cleaning before chemical gold plating: Remove surface contaminants:

[0057] Automatic coating and developing equipment: The chip is placed in the fully automatic equipment and first briefly treated with developer. The developer's dissolving effect removes any remaining photoresist edges or thin layers on the photoresist pattern. Due to the initial overexposure process, this development process does not damage the existing photoresist pattern.

[0058] Deionized water rinsing and air drying: After developer treatment, the chip surface is immediately rinsed with a large amount of deionized water to remove residual developer and dust and impurities adsorbed by process delays. After rinsing, the chip surface is dried using hot nitrogen or centrifugal force to ensure a clean and dry surface. This step effectively eliminates surface contamination caused by delays in traditional processes and provides a clean substrate for electroless gold plating.

[0059] Step (6) Surface Plasma Glow: Activating the Surface to be Gold-Plated. The pre-cleaned chip is placed in a plasma treatment apparatus, where an inert gas (such as argon) is introduced. A radio frequency power source generates a plasma glow. High-energy particles in the plasma collide with the chip surface, removing residual organic contaminants while also roughening the surface, increasing surface energy, and improving the uniformity and adhesion of the gold layer. The treatment time is set based on the surface activation requirements to ensure optimal surface activation.

[0060] Step (VII) Surface treatment liquid immersion: Enhance substrate activity: Treatment liquid preparation and temperature control: Prepare the surface treatment liquid according to a predetermined ratio and heat it to an appropriate temperature to ensure that the active ingredients in the treatment liquid can fully exert their effects.

[0061] Immerse the chip in the treatment solution and shake the chip fixture up and down briefly to ensure full contact between the chip and the treatment solution. This prevents inadequate pretreatment due to fixture obstruction. During the immersion process, the treatment solution reacts chemically with the chip surface, further removing the oxide layer and forming catalytically active sites that are conducive to gold ion deposition.

[0062] Step 8: Electroless Gold Plating: Thickening the Gold Layer: Prepare the Gold Plating Solution: Heat the electroless gold plating solution to a predetermined temperature to ensure a stable reduction reaction rate for the gold ions in the solution. The gold plating solution contains gold salt, reducing agent, and buffer, and the concentrations of each component are precisely formulated according to the process requirements.

[0063] Chip immersion and process monitoring: Immerse the pretreated chip in the gold plating solution and start the timer. During the plating process, observe the gold deposition in the solution in real time. If abnormal gold deposition is observed (such as localized rapid deposition or bubble formation), adjust the solution temperature or stirring rate immediately. By controlling the plating time, the gold layer thickness reaches the design requirement, ensuring a uniform, pinhole-free coating.

[0064] Step 9: Deionized Water Rinse: Remove residual plating solution. Immerse the gold-plated chip in deionized water preheated to a predetermined temperature for an appropriate period of time to remove residual gold plating solution and reaction byproducts. Gently shake the chip during the cleaning process to improve cleaning efficiency and prevent residual solution from affecting the subsequent stripping process or the performance of the gold layer.

[0065] Step 10: Peeling off the chemically plated gold electrode: Adhesion of the blue film to remove residual gold: Chip fixation and nitrogen adsorption: Place the chip on the suction cup device, open the nitrogen valve, and use the nitrogen pressure to firmly adsorb the chip on the suction cup surface to prevent the chip from moving during the peeling process.

[0066] Blue film selection and adhesion: Based on the state of the gold layer on the chip surface and the size of the residual gold particles, select a blue film with appropriate viscosity (such as medium viscosity or high viscosity). Apply the blue film evenly to the chip surface, ensuring full contact between the blue film and the residual gold particles on the surface.

[0067] Blue film peeling and residual gold removal: The blue film is peeled off slowly and evenly, leveraging its viscosity to remove any residual gold particles precipitated on the surface. This method avoids the mechanical damage of traditional cotton ball wiping, ensuring that the chip surface and the formed electrode pattern are not scratched. It also effectively removes residual gold and improves the quality of the gold layer.

[0068] This embodiment uses a pre-cleaning step to remove surface contaminants, ensuring uniform deposition of gold ions on a clean substrate during electroless gold plating, significantly reducing uneven gold deposition and pattern incompleteness. The blue film stripping process eliminates human error, reducing the risk of chip scratches by approximately 90%, while also improving residual gold removal efficiency. Testing has shown that the gold layer on the optical chip electrodes produced using this process has strong bonding strength, low surface roughness, and stable electrical signal transmission performance, meeting the requirements of high-reliability optical communication devices.

[0069] Example 3: Full-process optimized chemical gold plating process for optical chip electrodes:

[0070] Process Optimization Background and Key Improvements: In existing optical chip electrode gold plating processes, the transition between evaporation and chemical gold plating carries the risk of surface contamination, and the stripping process relies on manual labor, resulting in significant fluctuations in the quality of the gold layer. This embodiment further optimizes the connection control and equipment automation of each process step, improving the consistency and reliability of the gold layer quality through refined management of the entire process.

[0071] The detailed process steps are as follows:

[0072] Step 1: Evaporation and Gold Lithography: High-Precision Pattern Preparation: Optimized Photoresist Coating: Utilizing fully automated spin coating equipment, the spin coating speed and acceleration curve are dynamically adjusted based on chip size and electrode pattern accuracy to ensure photoresist film thickness uniformity within ±5%. After coating, a stepwise soft bake is performed, first evaporating the solvent at a low temperature, then gradually increasing the temperature to cure, strengthening the bond between the film and the substrate.

[0073] Dynamic adjustment of exposure parameters: An intelligent exposure system automatically optimizes exposure energy and time based on chip batches and photoresist characteristics. Real-time monitoring of the photoresist's photochemical reaction ensures clear, burr-free electrode window edges. A spray development process is used during development to improve uniformity between the developer and the chip surface and reduce blind spots.

[0074] Step 2: Gold Evaporation: Precise Deposition of Multiple Metal Layers. Pre-treatment in the Vacuum Chamber: Before placing the chip into the evaporation equipment, the surface is treated with a UV-ozone cleaner to remove adsorbed organic contaminants. During the evaporation process, ion-assisted deposition technology is used to enhance the bonding between metal atoms and the substrate through high-energy ion bombardment, reducing the interfacial diffusion rate between the Ti-Pt-Au three-layer metal layer by over 30%.

[0075] Thickness closed-loop control: A quartz crystal oscillator is used to monitor the metal evaporation rate and thickness in real time. When the metal reaches 90% of the predetermined thickness, the evaporation power is automatically reduced and a gradient deposition method is used to slow down the deposition rate, avoid thickness overshoot, and ensure that the thickness deviation of each metal layer is controlled within ±3%.

[0076] Step 3: Stripping the Evaporated Gold Electrode: Automated Cleaning: Ultrasonic-Assisted Stripping: During the NMP solution stripping process, low-frequency ultrasonic vibrations are introduced to accelerate the shedding of the unprotected metal layer through the cavitation effect, shortening the stripping time and reducing metal debris. Ultrasonic power is dynamically adjusted based on chip size and metal layer thickness to avoid chip damage.

[0077] Multi-stage cleaning system: After stripping, a three-stage cleaning process of "deionized water spray + megahertz ultrasonic cleaning + nitrogen purge" is used. First, large impurities are removed by high-pressure deionized water spray, followed by megahertz ultrasonic cleaning of fine particles. Finally, dry nitrogen is used to thoroughly dry the surface, ensuring that the surface cleanliness meets the requirements for electroless gold plating.

[0078] Step 4: Electroless Gold Lithography: Process Delay Control and Pattern Protection: Photoresist Rapid Curing: After secondary coating, UV rapid curing technology is used to quickly complete the photoresist crosslinking reaction, reducing the film's exposure to air and the risk of dust absorption. During the curing process, the UV light wavelength and energy density are controlled to ensure a balance between film hardness and adhesion.

[0079] Etching parameter optimization: To meet the requirements of the electrode window for chemical gold plating, the reactive ion etching (RIE) process is adopted. By precisely controlling the etching gas flow, RF power and pressure, anisotropic etching is achieved, so that the verticality of the window sidewall reaches more than 85°, providing a regular deposition boundary for subsequent chemical gold plating.

[0080] Step (5) Pre-cleaning before chemical gold plating: Intelligent pollution removal: Fully automatic pre-cleaning process: Place the chip into the integrated photoresist development equipment and start the pre-cleaning program: First, use a specially formulated developer for spray development. The developer dosage and spray pressure are automatically adjusted according to the degree of contamination on the chip surface to ensure that the removal rate of residual photoresist reaches more than 99%; then rinse through a multi-channel deionized water injection system. The water flow direction and pressure change in a gradient to efficiently remove surface dust and ionic pollutants.

[0081] Plasma-assisted cleaning: After rinsing with deionized water, a low-temperature plasma treatment step is added, in which a mixed gas of oxygen and argon is introduced. The chemical and physical effects of plasma are used to remove residual organic matter and oxides on the surface, making the surface contact angle less than 10° and achieving a highly activated state.

[0082] Step (6) Surface Treatment Liquid Immersion: Uniform Activation Process: Dynamic Immersion System: A dedicated chip fixture is designed with a hollowed-out slot to avoid obstructing the chip surface. During immersion, the fixture oscillates up and down in the treatment liquid at a predetermined frequency. A built-in magnetic stirrer in the treatment liquid tank creates a three-dimensional flow field, ensuring full contact between all parts of the chip and the treatment liquid. The activation uniformity error is less than ±2%.

[0083] Processing liquid regeneration technology: The processing liquid tank is equipped with online filtration and composition monitoring devices to remove impurity ions and replenish consumed active ingredients in real time, extending the service life of the processing liquid and ensuring the consistency of the pretreatment effect of each batch of chips.

[0084] Step 7: Chemical Gold Plating: Intelligent Temperature Control and Real-Time Monitoring: A high-precision constant temperature system utilizes oil bath heating and PID intelligent temperature control technology to control the temperature fluctuation of the gold plating solution within a range of ±0.5°C, preventing temperature fluctuations that may cause changes in the gold deposition rate. The gold plating tank utilizes a double-layer insulation structure to reduce the impact of the external environment on the temperature.

[0085] Visualized gold deposition monitoring: A high-definition camera and image analysis system installed on the side of the gold plating tank captures the size and distribution of gold particles in the plating solution in real time. If abnormal gold deposition is detected, the system automatically issues an alarm and adjusts the plating solution's stirring rate or adds reducing agent to maintain plating stability.

[0086] Step 8: Deionized Water Rinse: Heat-Assisted Cleaning: Immerse the gold-plated chip in a temperature-controlled deionized water bath, maintaining the water temperature within an appropriate range. Heat is used to accelerate the dissolution and diffusion of residual plating solution. The cleaning process uses overflow water exchange to ensure consistently clean water quality, while gentle mechanical agitation is used to prevent water impact damage to the gold surface.

[0087] Step 9: Stripping the Electroless Gold Electrodes: Blue Film Automation: Vacuum Adsorption and Positioning: Using a high-precision vacuum suction cup platform, a visual positioning system automatically identifies the chip edge and electrode pattern, ensuring precise placement of the blue film. The suction cup surface is covered with a soft silicone pad to prevent chip deformation under pressure.

[0088] Automated blue film application and removal: A robotic arm grips the blue film reel and applies constant pressure to the chip surface. The application speed and pressure are preset based on the film's viscosity and the state of the gold layer. During removal, the robotic arm lifts the film at a gentle angle and speed. A force sensor monitors the removal force to avoid damage to the chip due to excessive force, achieving efficient removal of residual gold particles with zero scratches.

[0089] This embodiment reduces the risk of surface contamination during the electroless gold plating process through full-process automation and intelligent control, improves the uniformity of the gold layer thickness, and achieves an electrode pattern integrity pass rate of over 99.5%. The automated blue film stripping process completely eliminates manual operation errors and improves chip yield. This process is suitable for large-scale manufacturing of high-speed optical communication chips and can meet the stringent electrode reliability requirements of 800G and above optical modules, while reducing production costs and process complexity, and has significant industrial application prospects.

[0090] The foregoing description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein and should not be construed as excluding other embodiments. Rather, the present invention can be used in various other combinations, modifications, and environments and can be modified within the scope of the concept described herein through the above teachings or techniques or knowledge in the relevant field. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention are intended to be protected by the appended claims.

Claims

1. A process for improving the quality of the gold-plated layer of optical chip electrodes, characterized in that: The following steps are involved: Evaporation gold plating photolithography: Open the electrode windows of P-type electrode and N-type electrode through photolithography technology; Evaporation gold plating: Ti-Pt-Au metal electrodes are formed by electron beam evaporation equipment; Evaporation gold electrode stripping: Use 80℃ NMP solution for 10 minutes; Chemical gold plating photolithography: open the electrode windows of P-type electrode and N-type electrode again; Pre-cleaning before chemical gold plating: Develop with developer for 15 seconds using a fully automatic coating and developing device, then rinse with deionized water and blow dry; Surface plasma glow treatment for 2 minutes; Soak in the surface treatment liquid for 5 minutes, shaking up and down for 5 seconds while immersing; Soak in 55℃ chemical gold plating solution for 20 minutes for chemical gold plating; Soak in 40℃ deionized water for 5 minutes; Chemical gold-plated electrode stripping: After stripping in 80℃ NMP solution for 10 minutes, use blue film to remove residual gold particles.

2. A process for improving the quality of the gold-plated layer of an optical chip electrode according to claim 1, characterized in that: In the pre-cleaning step, after development with the developer, the surface is rinsed with a large amount of deionized water and blown dry to remove residual photoresist, surface dust and impurities.

3. A process for improving the quality of the gold-plated layer of an optical chip electrode according to claim 1, characterized in that: The surface treatment liquid is shaken up and down for 5 seconds while being immersed to ensure that the chip part at the fixture slot is fully pretreated.

4. A process for improving the quality of the gold-plated layer of an optical chip electrode according to claim 1, characterized in that: The temperature of the chemical gold plating solution is 55° C., the gold plating time is 20 minutes, and the gold precipitation is observed during the gold plating process.

5. A process for improving the quality of the gold-plated layer of an optical chip electrode according to claim 1, characterized in that: In the chemical gold-plated electrode stripping step, the chip is fixed on a suction cup, and after nitrogen adsorption, it is adhered with a blue film of suitable viscosity and slowly peeled off to remove residual gold particles.

6. A process for improving the quality of the gold-plated layer of an optical chip electrode according to claim 1, characterized in that: The thickness of the gold layer of the evaporated gold plating is 700Å-800Å for Ti, 700Å-800Å for Pt, and 5000Å for Au.

7. A process for improving the quality of the gold-plated layer of an optical chip electrode according to claim 1, characterized in that: In the steps of stripping the evaporated gold-plated electrodes and stripping the chemically gold-plated electrodes, the temperature of the NMP solution is 80° C., and the stripping time is 10 minutes.

8. A process for improving the quality of the gold-plated layer of an optical chip electrode according to claim 1, characterized in that: The surface plasma glow treatment lasted for 2 minutes.

9. A process for improving the quality of the gold-plated layer of an optical chip electrode according to claim 1, characterized in that: The immersion time in 40℃ deionized water is 5 minutes, which is used to clean the gold-plated chips.

10. A process for improving the quality of the gold-plated layer of an optical chip electrode according to claim 1, characterized in that: The chemical gold plating photolithography adopts overexposure and overdevelopment processes so that the pre-cleaning step does not affect the photolithography pattern.

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