Parameter self-regulating type laser-assisted maskless micro-pattern electrodeposition process

Abstract

This invention relates to the fields of microelectronics manufacturing and precision surface engineering, comprising: a laser unit for generating and controlling a laser beam, an electrodeposition unit for providing an electric field, a detection unit for real-time online monitoring of coating thickness and edge contour, and a control unit for dynamically adjusting laser and electrochemical parameters based on monitoring data. The process steps include: substrate pretreatment, plating solution preparation, intelligent matching of initial parameters based on the target linewidth, adaptive closed-loop deposition, and post-processing. During deposition, by real-time detection of coating thickness and edge overflow, the control unit dynamically adjusts the laser single-pulse energy, scanning speed, and current density to compensate for process disturbances. This invention solves the problems of low pattern accuracy, poor edge localization, and weak process adaptability in existing technologies, achieving high-precision micro-pattern fabrication with linewidth accuracy controlled within ±1% and edge overflow ≤0.5μm, thus improving process stability and product yield.

Description

Technical Field

[0001] This invention relates to the fields of microelectronics manufacturing and precision surface engineering, and in particular to a parameter-self-adjustable laser-assisted maskless micropattern electrodeposition process. Background Technology

[0002] Laser-assisted electrodeposition is a composite processing technology that combines high-energy-density laser beams with electrochemical deposition technology. It utilizes the local thermal and photochemical effects induced by the laser at the cathode-solution interface to significantly improve the reduction rate of metal ions, achieve selective deposition of micro-areas, and directly prepare metal micro-patterns on the substrate surface without the need for traditional photolithography masks. This provides an efficient technical path for rapid prototyping and defect repair of microelectronic devices.

[0003] However, existing laser-assisted maskless electrodeposition technology still faces the following unresolved technical bottlenecks in practical industrial applications, especially in microelectronics manufacturing scenarios requiring submicron precision:

[0004] First, the open-loop process has poor stability. Existing technologies usually use preset fixed process parameters for processing. However, the electrodeposition process is affected by a variety of factors such as the composition of the plating solution, temperature, pH fluctuations, laser energy stability, and substrate surface condition. It is a typical dynamic time-varying process. Fixed parameters cannot adapt to the dynamic disturbances in the process, resulting in fluctuations in deposition rate and uneven coating thickness. In the end, the deviation of the pattern linewidth generally exceeds ±5%, which cannot meet the requirements of high-precision manufacturing.

[0005] Second, the deposition localization is insufficient and the edge quality is poor. The thermal diffusion effect of the laser and the concentration effect of the electric field at the edge of the microstructure can easily cause the deposited metal to exceed the preset pattern boundary, forming overflow or burrs. This not only reduces the pattern resolution, but also affects the electrical performance and long-term reliability of the microcircuit. Existing technologies cannot achieve real-time suppression of overflow.

[0006] Third, the process adaptability is weak and the debugging cycle is long. For processing scenarios with different line widths, different substrate materials and different functional requirements, a large number of process experiments need to be carried out manually to debug the appropriate parameter combination. It lacks intelligent parameter self-adaptation capability, resulting in low process development efficiency and inability to adapt to the manufacturing needs of flexibility, multiple varieties and small batches. Summary of the Invention

[0007] The purpose of this invention is to provide a parameter-self-adjustable laser-assisted maskless micropattern electrodeposition process to solve the problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A parameter-self-adjustable laser-assisted maskless micropattern electrodeposition process includes a laser unit, an electrodeposition unit, a real-time detection unit, and a control unit.

[0010] The laser unit is used to generate and control a laser beam acting on a predetermined area of ​​the workpiece surface. Specifically, the laser unit uses a nanosecond pulse laser with an output wavelength of 1064nm and a pulse width of less than 100ns. It is equipped with a beam expander, a two-dimensional high-speed galvanometer, and a dynamic focusing lens. The laser single pulse energy, repetition frequency, scanning speed, and spot diameter can all be adjusted in real time through external analog or digital signals.

[0011] The electrodeposition unit provides an electric field to the workpiece for electrochemical deposition on its surface. Specifically, the electrodeposition unit includes a pulse power supply, an electrode system, a miniature open electroplating tank, and a precision electrically controlled stage. The pulse power supply can adjust the output pulse current density, frequency, and pulse width in real time. The electrode system includes a miniature platinum or platinum-iridium anode and a cathode clamp reliably electrically connected to the workpiece. The miniature open electroplating tank adopts a liftable design or a side-jet design to achieve stable supply of plating solution and waste liquid recovery. The precision electrically controlled stage has multi-degree-of-freedom adjustment capabilities (X, Y, Z, θ) and a positioning accuracy better than ±0.1μm, used to support the workpiece and complete preset trajectory movements.

[0012] The real-time detection unit is used to monitor the coating thickness and edge contour of the deposition pattern on the workpiece surface online during the deposition process, and output corresponding thickness signals and contour image signals. Specifically, the real-time detection unit includes a laser interferometric thickness gauge or a confocal laser displacement sensor, a high-resolution microscopic imaging system, and an image processing module; the laser interferometric thickness gauge or confocal laser displacement sensor is used to non-contactly measure the coating thickness at a frequency higher than 100Hz; the high-resolution microscopic imaging system is used to capture a top-view image of the deposition area at a frame rate higher than 50Hz; the image processing module is used to perform real-time edge detection and analysis on the top-view image and calculate the edge overflow amount.

[0013] The control unit is communicatively connected to the real-time detection unit, the laser unit, and the electrodeposition unit. It receives thickness signals and contour image signals, determines the edge overflow amount based on the contour image signal, and generates a first adjustment command according to a preset control strategy to adjust the parameters of the laser unit. It determines the coating growth rate based on the thickness signal and generates a second adjustment command according to the preset control strategy to adjust the parameters of the electrodeposition unit. The laser unit and the electrodeposition unit adjust their operating parameters in real time according to the received adjustment commands to form an adaptive closed-loop control system.

[0014] Furthermore, the control unit pre-stores a process database containing initial laser parameters and initial electrodeposition parameters corresponding to different target linewidths, as well as an adaptive control algorithm based on fuzzy logic control or model predictive control. Based on the received target linewidth information, the control unit automatically retrieves the matching initial parameter set from the process database and sends it to the laser unit and the electrodeposition unit.

[0015] Furthermore, the first adjustment instruction includes an instruction to control the laser unit to increase the single pulse energy and / or decrease the scanning speed when the edge overflow amount is detected to exceed a first threshold; the second adjustment instruction includes an instruction to control the electrodeposition unit to adjust the pulse current density when the coating thickness growth rate is detected to deviate from the expected value by more than a second threshold.

[0016] Meanwhile, the present invention also provides a parameter-self-tunable laser-assisted maskless micro-pattern electrodeposition process, applied to the above-mentioned parameter-self-tunable laser-assisted maskless micro-pattern electrodeposition device, comprising the following steps:

[0017] S1. Perform cleaning and surface activation pretreatment on the workpiece substrate. Specifically, for semiconductor silicon wafers or glass substrates, the RCA standard cleaning process is used; for polymer substrates such as polyimide, ultrasonic cleaning is performed sequentially with acetone and ethanol, followed by oxygen plasma treatment to activate the surface; the pretreated substrate is fixed on a precision electronically controlled worktable for positioning calibration.

[0018] S2. Prepare the electrodeposition plating solution and supply it to the electrodeposition unit. Specifically, the electrodeposition plating solution adopts an acidic copper sulfate system, containing 220±20 g / L CuSO4・5H2O, 60±10 g / L H2SO4, 80±20 mg / L Cl⁻ ion source, and 0.01 to 0.03 g / L polyethylene glycol; the temperature of the plating solution is controlled at 25±0.5℃ by a constant temperature bath, and an inert gas is continuously introduced for stirring. The plating solution is stably supplied to the deposition area through a micro open electroplating tank.

[0019] S3. Based on the linewidth of the target pattern, the control unit sets the initial laser parameters and initial electrodeposition parameters. Specifically, the operator inputs the minimum linewidth of the target pattern, and the control unit automatically retrieves the matching initial parameter set from the process database to complete the parameter setting. The linewidth of the target pattern is in the range of 5μm to 50μm, and the spot diameter generated by the laser unit is dynamically adjusted to 0.7 to 0.9 times the target linewidth. The initial laser parameters include a single pulse energy of 0.05-0.20mJ and a scanning speed of 1000-3000mm / s. The initial electrodeposition parameters include a pulse current density of 20-50mA / cm², a pulse frequency of 1-3MHz, and a pulse width of 30-100ns.

[0020] S4. Start the laser unit and electrodeposition unit to deposit metal according to the preset pattern trajectory, while the real-time detection unit monitors the coating thickness and edge contour online. Specifically, the laser unit scans according to the preset pattern trajectory, and the electrodeposition unit is started simultaneously to apply a pulsed electric field to begin metal deposition. During the deposition process, the real-time detection unit continuously collects coating thickness data and top-view images of the deposition area, calculates the coating growth rate and edge overflow in real time, and transmits the data to the control unit in real time.

[0021] S5. The control unit dynamically adjusts at least one of the following based on real-time monitoring results: laser single-pulse energy, scanning speed, and pulse current density. Specifically, the dynamic adjustment strategy is as follows: when the real-time monitored edge overflow is greater than 0.5 μm, the laser single-pulse energy is increased by 10% to 20%, while the scanning speed is decreased by 10% to 20%; when the real-time monitored coating thickness growth rate deviates from the model prediction value by more than ±5%, the pulse current density is adjusted within the range of ±5 mA / cm².

[0022] S6. After deposition is complete, the workpiece is cleaned and dried. Specifically, after the preset pattern deposition is completed, the pulsed electric field of the electrodeposition unit and the laser beam of the laser unit are turned off in sequence, the workpiece is removed from the plating solution, and immediately sprayed with ultrapure water to clean it, and then dried with high-purity nitrogen to complete the entire deposition process.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] 1. This invention improves the precision and edge quality of micro-pattern deposition. Through real-time edge monitoring and dynamic control of laser parameters, this invention effectively suppresses edge overflow, controlling the amount of edge overflow to below 0.5μm. Simultaneously, it improves the pattern linewidth control precision from the traditional ±5% to within ±1%, meeting the precision requirements of high-end semiconductor integrated circuit manufacturing.

[0025] 2. This invention improves the stability and repeatability of the process. The dual-dimensional closed-loop control system constructed in this invention can automatically compensate for process disturbances such as fluctuations in plating solution composition, laser power drift, and changes in ambient temperature, thereby improving the uniformity of coating thickness within and between batches by more than 50% and increasing the overall product qualification rate by more than 40%, significantly reducing the reliance on manual operation experience.

[0026] 3. This invention enhances the adaptability and flexible manufacturing capabilities of the process. The built-in process database and intelligent parameter matching engine of this invention can quickly match the optimal initial parameters for different linewidths and substrate materials within the range of 5μm to 50μm, eliminating the need for extensive manual process debugging, significantly shortening the process development cycle, and flexibly adapting to the flexible manufacturing needs of multiple varieties and small batches.

[0027] 4. This invention enhances the integration and automation level of the device. It deeply integrates high-precision machining, multi-modal online detection, and intelligent closed-loop control, enabling one-click fully automated machining from graphic file input to finished metal microstructure output, significantly improving production efficiency and machining reliability.

[0028] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it according to the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Specific embodiments of the present invention are given in detail below with reference to the accompanying drawings. Attached Figure Description

[0029] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0030] Figure 1 This is a schematic diagram of the overall system architecture of the adaptive laser-assisted maskless micro-pattern electrodeposition device provided in an embodiment of the present invention;

[0031] Figure 2 This is a detailed flowchart of the real-time detection and adaptive control logic in the process of this invention;

[0032] Figure 3 This is a curve showing the change of the total coating thickness over time during the deposition process in an embodiment of the present invention. Detailed Implementation

[0033] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. The invention is described more specifically in the following paragraphs by way of example with reference to the accompanying drawings. It should be noted that the drawings are in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0034] Example 1: Online repair of 20μm wide copper interconnects on silicon-based integrated circuits:

[0035] The application scenario of this embodiment is the repair of defects in copper interconnects on silicon wafers. The copper interconnect to be repaired has a design width of 20μm and a partial open circuit due to manufacturing defects, with a gap length of 50μm.

[0036] This embodiment employs the parameter-self-adjustable laser-assisted maskless micro-pattern electrodeposition device described in this invention. The specific implementation steps are as follows:

[0037] S1. Substrate pretreatment and clamping: Fix the silicon wafer to be repaired on the precision electronic control worktable of the device, and perform standard ultrasonic cleaning on the wafer in sequence with acetone, isopropanol and deionized water. After cleaning, dry it with high-purity nitrogen gas and complete the positioning calibration.

[0038] S2. Plating solution preparation and supply: Prepare an acidic copper sulfate plating solution with the following components: 220 g / L CuSO4・5H2O, 60 g / L H2SO4, 80 mg / L HCl, 0.02 g / L polyethylene glycol, and 3 mg / L sodium polydisulfide dipropane sulfonate. Control the temperature of the plating solution at 25 ± 0.5℃ using a constant temperature bath, continuously introduce nitrogen gas for stirring, and supply the plating solution to the area to be repaired through a micro open electroplating tank.

[0039] S3. Initial parameter setting: Input the target repair line width of 20μm in the control software. The control unit automatically retrieves the matching initial parameters from the process database: laser single pulse energy 0.12mJ, scanning speed 2000mm / s, spot diameter 15μm; pulse current density 35mA / cm², pulse frequency 2.0MHz, pulse width 80ns; at the same time, the real-time detection unit is started to scan and calibrate the initial surface of the wafer to establish the thickness and morphology measurement benchmark.

[0040] S4. Adaptive Closed-Loop Deposition: The deposition program is initiated, and the laser unit scans along the preset repair path. Simultaneously, the pulsed power supply applies an electric field to begin deposition and repair. During deposition, the confocal laser displacement sensor acquires coating thickness data in real time at a frequency of 200Hz and calculates the coating growth rate. The high-resolution microscopic imaging system captures a top-view image of the deposition area at a frame rate of 100Hz and calculates the edge overflow in real time. All data is transmitted to the control unit in real time.

[0041] In the initial stage of deposition, the real-time detection unit detected that the overflow amount at the initial deposition edge was 0.7 μm, which exceeded the threshold of 0.5 μm. The control unit immediately generated an adjustment command, increasing the laser single pulse energy to 0.14 mJ and reducing the scanning speed to 1700 mm / s. After 2 seconds of adjustment, the overflow amount detected in real time dropped to below 0.3 μm, which met the control requirements.

[0042] During the middle stage of deposition, the thickness detection unit detected that the coating thickness growth rate was 6.2% higher than the model prediction value, exceeding the threshold of ±5%. The control unit immediately generated an adjustment command to reduce the pulse current density to 32mA / cm². After adjustment, the coating growth rate returned to the expected range, and the deviation was controlled within ±2%.

[0043] Throughout the deposition process, the control unit continuously fine-tunes the process parameters based on real-time monitoring data to ensure the stability of the deposition process.

[0044] S5. Post-processing and inspection: After the deposition of the area to be repaired is completed, turn off the pulse power supply and laser in sequence, remove the wafer from the plating solution, immediately clean it with ultrapure water spray, and then dry it with high-purity nitrogen.

[0045] The repaired interconnects were inspected using a scanning electron microscope and a probe station. The results showed that the actual width of the lines in the repaired area was 20.15 μm, with a line width accuracy of +0.75%, which was within ±1%. The edge overflow was 0.3 μm, which met the requirement of ≤0.5 μm. The edge roughness Ra was 0.12 μm. The resistance value of the repaired line was consistent with that of the adjacent intact line, and all electrical function tests were passed.

[0046] Example 2: Fabrication of multi-linewidth antenna patterns on a polyimide flexible substrate:

[0047] The application scenario of this embodiment is the direct writing of antenna patterns for flexible electronic devices. The substrate is a 100μm thick polyimide film, and the antenna pattern to be prepared includes a 5μm wide fine feed line and a 50μm wide radiating patch.

[0048] This embodiment employs the parameter-self-adjustable laser-assisted maskless micro-pattern electrodeposition device described in this invention. The specific implementation steps are as follows:

[0049] S1. Substrate pretreatment and clamping: Fix the polyimide film on a precision electronically controlled worktable, and perform ultrasonic cleaning with acetone and ethanol in sequence. After cleaning, treat with oxygen plasma for 3 minutes to activate the film surface and improve the adhesion of the coating.

[0050] S2. Plating solution preparation and supply: Prepare the same acidic copper sulfate plating solution as in Example 1, control the temperature at 25±0.5℃, continuously introduce nitrogen gas for stirring, and stably supply it to the deposition area.

[0051] S3. Initial Parameter Setting: Input the target linewidths of 5μm and 50μm respectively in the control software. The control unit automatically retrieves the matching initial parameters from the process database. For the feeder area with a linewidth of 5μm, the initial parameters are: laser single pulse energy 0.06mJ, scanning speed 2500mm / s, spot diameter 4μm, and pulse current density 25mA / cm². For the radiation patch area with a linewidth of 50μm, the initial parameters are: laser single pulse energy 0.18mJ, scanning speed 1200mm / s, spot diameter 45μm, and pulse current density 45mA / cm².

[0052] S4. Adaptive Closed-Loop Deposition: The deposition program is initiated, and the device processes the feed line area and the radiating patch area sequentially according to the preset pattern path. When processing the 5μm feed line area, the real-time detection unit detects the risk of overflow due to thermal diffusion. The control unit automatically increases the scanning speed to 2800mm / s, effectively suppressing overflow. The final overflow amount at the feed line edge is controlled within 0.25μm. When processing the 50μm radiating patch area, to ensure the flatness of the coating filling, the control unit periodically adjusts the laser single-pulse energy by ±5% during the scanning process, generating a gentle convection stirring effect. The final coating thickness uniformity deviation in the patch area is less than ±3%.

[0053] S5. Post-processing and Inspection: After deposition, the polyimide film was cleaned and dried, and inspected using a laser confocal microscope and impedance analyzer. Results showed that the actual width of the 5μm feed line was 5.03μm, with a linewidth accuracy of +0.6%; the actual width of the 50μm radial patch was 50.2μm, with a linewidth accuracy of +0.4%, both controlled within ±1%. The pattern exhibited good conductivity; after 1000 bending tests, the resistance change rate was less than 2%, demonstrating excellent adhesion and flexible reliability.

[0054] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Those skilled in the art can readily implement the present invention based on the description and drawings above. However, any modifications, alterations, and variations made by those skilled in the art without departing from the scope of the present invention using the disclosed technical content are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A parameter-self-adjustable laser-assisted maskless micro-pattern electrodeposition device, characterized in that, The system includes a laser unit, an electrodeposition unit, a real-time detection unit, and a control unit. The laser unit generates and controls a laser beam that acts on a predetermined area of ​​the workpiece surface. The electrodeposition unit provides an electric field to the workpiece for electrochemical deposition on its surface. The real-time detection unit monitors the coating thickness and edge contour of the deposition pattern on the workpiece surface online during the deposition process and outputs corresponding thickness and contour image signals. The control unit is communicatively connected to the real-time detection unit, the laser unit, and the electrodeposition unit. It receives the thickness and contour image signals, determines the edge overflow based on the contour image signal, and generates a first adjustment command according to a preset control strategy to adjust the parameters of the laser unit. It also determines the coating growth rate based on the thickness signal and generates a second adjustment command according to a preset control strategy to adjust the parameters of the electrodeposition unit. The laser unit and the electrodeposition unit adjust their operating parameters in real time according to the received adjustment commands, forming an adaptive closed-loop control system.

2. The parameter-self-adjustable laser-assisted maskless micro-pattern electrodeposition device according to claim 1, characterized in that, The real-time detection unit includes a laser interferometric thickness gauge or a confocal laser displacement sensor, a high-resolution microscopic imaging system, and an image processing module. The laser interferometric thickness gauge or confocal laser displacement sensor is used to non-contactly measure the coating thickness at a frequency higher than 100Hz. The high-resolution microscopic imaging system is used to capture a top-view image of the deposition area at a frame rate higher than 50Hz. The image processing module is used to perform real-time edge detection and analysis on the top-view image and calculate the edge overflow amount.

3. The parameter-self-adjustable laser-assisted maskless micro-pattern electrodeposition device according to claim 2, characterized in that, The control unit has a pre-stored process database containing initial laser parameters and initial electrodeposition parameters corresponding to different target linewidths, as well as an adaptive control algorithm based on fuzzy logic control or model predictive control.

4. The parameter-self-adjustable laser-assisted maskless micro-pattern electrodeposition device according to claim 3, characterized in that, The control unit automatically retrieves the matching initial parameter set from the process database based on the received target linewidth information and sends it to the laser unit and the electrodeposition unit.

5. The parameter-self-adjustable laser-assisted maskless micro-pattern electrodeposition device according to claim 1, characterized in that, The first adjustment instruction includes an instruction to control the laser unit to increase the single pulse energy and / or decrease the scanning speed when the edge overflow amount is detected to exceed a first threshold; the second adjustment instruction includes an instruction to control the electrodeposition unit to adjust the pulse current density when the coating thickness growth rate is detected to deviate from the expected value by more than a second threshold.

6. A parameter-self-adjustable laser-assisted maskless micropattern electrodeposition process, applied to the parameter-self-adjustable laser-assisted maskless micropattern electrodeposition apparatus according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Clean and surface-activate the workpiece substrate; S2. Prepare the electrodeposition plating solution and supply it to the electrodeposition unit; S3. Based on the line width of the target pattern, the control unit sets the initial laser parameters and initial electrodeposition parameters; S4. Start the laser unit and electrodeposition unit, and deposit according to the preset pattern trajectory. At the same time, the real-time detection unit monitors the coating thickness and edge contour online. S5. The control unit dynamically adjusts at least one of the laser single pulse energy, scanning speed, and pulse current density based on real-time monitoring results; S6. After deposition is completed, the workpiece is cleaned and dried.

7. The parameter-self-adjustable laser-assisted maskless micropattern electrodeposition process according to claim 6, characterized in that, In step S5, the specific strategy for dynamic adjustment is as follows: when the edge overflow amount monitored in real time is greater than 0.5μm, the laser single pulse energy is increased by 10% to 20%, while the scanning speed is reduced by 10% to 20%; when the deviation between the coating thickness growth rate monitored in real time and the model prediction value exceeds ±5%, the pulse current density is adjusted within the range of ±5mA / cm².

8. The parameter-self-adjustable laser-assisted maskless micropattern electrodeposition process according to claim 6, characterized in that, The electrodeposition plating solution is an acidic copper sulfate system, containing 220±20 g / L CuSO4·5H2O, 60±10 g / L H2SO4, 80±20 mg / L Cl⁻ ion source, and 0.01 to 0.03 g / L polyethylene glycol.

9. The parameter-self-adjustable laser-assisted maskless micro-pattern electrodeposition process according to claim 6, characterized in that, The linewidth of the target pattern is in the range of 5μm to 50μm, and the diameter of the spot generated by the laser unit is dynamically adjusted to 0.7 to 0.9 times the target linewidth.

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