Technological Breakthrough and Prospects of Multi-Pulse Sequence Control in Ion Implantation High-Voltage Power Supplies

Ion implantation technology is a core process in semiconductor manufacturing, material surface modification, and precision device processing. As the heart of ion implantation equipment, high-voltage power supplies directly determine the energy accuracy, distribution uniformity, and process efficiency of implanted ions. The breakthrough in multi-pulse sequence control technology—achieved by dynamically adjusting pulse parameters (e.g., width, frequency, amplitude, and fall time)—has enabled a shift from single-energy to energy-gradient implantation, providing novel solutions for complex industrial demands. 
1. Core Advantages of Multi-Pulse Sequence Control
1. Energy-Gradient Implantation: Traditional single-pulse power supplies deliver fixed-energy ions, while multi-pulse sequences output combinations of pulses with varying parameters in a single process. For example, by adjusting pulse amplitude (80–100 kV) and width (10–50 μs), ions penetrate materials in stepped energy levels, forming gradient-doped layers that enhance surface hardness and fatigue resistance. 
2. Thermal Effect and Defect Suppression: The intermittent nature of high-frequency pulse sequences (30–500 Hz) allows materials to dissipate heat during pulse intervals, avoiding substrate overheating from continuous high voltage. In semiconductor deep-junction implantation, this reduces the heat-affected zone thickness by ~40% and minimizes lattice damage. 
3. Improved Uniformity: Real-time feedback control in multi-pulse sequences dynamically compensates for plasma density fluctuations. For instance, by monitoring load impedance variations, subsequent pulses’ rise time (<2.5 μs) and fall time (<5 μs) are auto-adjusted, ensuring implantation uniformity errors < ±0.1% across large-area substrates. 
2. Technical Challenges and Cutting-Edge Solutions
1. Fall-Time Control Bottleneck: Conventional modulators rely on pull-down resistors to release residual charge from load capacitors, resulting in prolonged fall times (>150 μs) and low-energy ions (24% of total ions), which degrade implantation quality. Solid-State Switching Technology (e.g., IGBT series modules) replaces resistor discharge paths with direct conduction channels for rapid capacitor energy release, compressing fall times to <5 μs. Voltage-balancing circuits (RC networks) ensure dynamic voltage sharing among IGBTs under high voltage (30–100 kV), preventing device breakdown. 
2. Resonant Networks for Pulse Shaping: Flat-top stability is critical for multi-pulse control. LC Resonant Networks (inductance: 1–4 mH; capacitance: 2200–4400 pF) generate ideal square waves through resonance characteristics. Combined with gear-switching mechanisms for pulse width adjustment (10–50 μs in five steps), this design eliminates waveform distortion from rigid modulators, achieving flat-top fluctuations <1% and ripple coefficients <1%. 
3. Timing Synchronization and Energy Efficiency: Microsecond-level timing coordination among switches (charging IGBT, main tube, pull-down IGBT) is essential. A Pulse Delay Circuit enables zero-crossing energy transition via a three-stage trigger: charging switch turn-off → tube driver activation → pull-down switch conduction. This reduces resistive power loss by 90% and boosts system efficiency to >96%. 
3. Future Directions
1. Intelligent Closed-Loop Control: Integrating high-voltage sensors and AI algorithms to analyze pulse deviations (e.g., overshoot, flat-top drop) and dynamically adjust resonant parameters. For example, auto-matching LC values based on load capacitance variations ensures pulse consistency at nanosecond-level delays. 
2. Wide-Bandgap Semiconductor Applications: Silicon carbide (SiC) switches withstand higher di/dt (>10 kA/μs) and voltage ratings (>1200 V), enabling compact power supplies and MHz-level pulses for nano-scale ion implantation. 
3. Multi-Physics Coupling Design: Coupling plasma impedance models, thermal diffusion equations, and control algorithms to quantify relationships between pulse parameters and process outcomes. For instance, predicting implantation depth to derive required pulse sequences will shift processes from experience-driven to model-driven. 
Conclusion
Multi-pulse sequence control technology combines hardware innovations (solid-state switches, resonant networks) and intelligent control (timing synchronization, closed-loop feedback) to address core challenges in ion implantation, including energy precision, thermal management, and uniformity. With the integration of third-generation semiconductor devices and interdisciplinary models, high-voltage power supplies will evolve from energy delivery units into intelligent actuators for ion implantation processes, empowering advanced chip manufacturing and materials science.