Expanding Process Windows in Etching Equipment: High-Voltage Power Supply Innovations

In semiconductor manufacturing, plasma etching is a core process determining the precision of microstructures, where the process window (i.e., the allowable parameter fluctuation range) directly impacts device yield and performance. As the energy source for plasma generation, innovations in high-voltage power supply technology play a decisive role in expanding this window. By optimizing power output characteristics, enhancing plasma stability, and enabling multi-parameter协同控制, high-voltage power supplies are pushing etching processes toward broader and more stable operating regimes. 
1. Power Supply Innovations for Process Window Expansion
• Resonant Conversion & High-Efficiency Energy Transfer 
  Traditional power supplies struggle with complex process demands due to low efficiency, large size, and slow dynamic response. Modern high-voltage power supplies adopt LCC series-parallel resonant circuits and multi-stage voltage multiplier rectification, achieving 90% conversion efficiency at 8 kW while reducing volume by over 60%. Resonant soft-switching technology minimizes switching losses, supporting high-frequency (>100 kHz) plasma generation and ensuring stable energy delivery—laying the foundation for process window expansion. 
• Adaptive Dual-Mode Control 
  Combining pulse-width modulation (PWM) and pulse-frequency modulation (PFM), power supplies dynamically switch modes under varying loads: 
  • Mode 1 (stable load): Fixed frequency with adjustable pulse width to maintain plasma density; 
  • Mode 0 (sudden load changes): Fixed minimum pulse width (60°) with adjustable frequency, enabling zero-voltage switching (ZVS) to suppress arc discharge. 
  This dual-mode approach increases process tolerance by 30%, e.g., reducing reflected power fluctuations to ±0.5% during diamond etching. 
2. Plasma Stability Control Technologies
• Dual-Frequency Coupling & Ion Energy Regulation 
  High/low-frequency hybrid architectures (e.g., 60 MHz/2 MHz) independently control ion energy (Ei) and ion flux (Γi): 
  • High-frequency source (>27 MHz): Modulates plasma density and radical generation efficiency; 
  Low-frequency source (1–2 MHz): Precisely adjusts ion bombardment energy via bias voltage. 
  Dynamic compensation for uneven radical distribution improves etching uniformity by 25%, achieving sidewall verticality errors below ±2°. 
• Wide-Bandgap Semiconductor Applications 
  Third-generation materials like silicon carbide (SiC) MOSFETs reduce switching losses by 70%, enabling peak efficiency of 96.5%. Their high-temperature tolerance ensures thermal stability in 11 kW-class power supplies during sustained pulsing, eliminating plasma drift-induced process variations. 
3. Synergistic Process Parameter Optimization
• Gas Chemistry-Power Supply Matching 
  Material-specific power parameters are critical: 
  • Silicon etching: High bias power (150–250 W) with SF₆ enhances ion bombardment for anisotropy; 
  SiO₂ etching: CHF₃/SF₆ mixtures require lower ion energy to maintain selectivity (>20:1). 
  Adaptive pressure control (0.1–2.0 Pa) and dynamic temperature systems expand the process window by 40%, minimizing etch rate deviations caused by environmental fluctuations. 
• Pulsed Plasma Technology 
  Nanosecond high-voltage pulse modulation narrows ion energy distribution bandwidth to ±5 eV, reducing sidewall erosion from low-energy ions. For β-Ga₂O₃ film etching, optimized pulse duty cycles achieve aspect ratios up to 50:1 while lowering mask damage rates by 15%. 
4. Future Trends and Challenges
• AI-Driven Optimization Platforms 
  Machine learning-based real-time process sensors train predictive models using plasma emission spectroscopy data to dynamically recommend power parameters. Real-time RF matching network adjustments, for instance, expand process windows to 1.8× traditional methods. 
• High-Aspect-Ratio Structure Challenges 
  For structures exceeding 100:1 aspect ratios, nonlinear sheath oscillations in ultra-narrow trenches require advanced solutions. Future developments will focus on transient field协同 control algorithms, 3D power topologies, and pulsed modulation-magnetic confinement integration to push process limits. 
Conclusion
High-voltage power supply technologies—spanning efficient energy conversion, adaptive control, and multi-physics optimization—significantly expand etching process windows, enabling sub-3 nm node manufacturing. As AI and wide-bandgap semiconductors converge, these power systems will drive atomic-scale precision and ultra-low-damage etching, solidifying their role as the cornerstone of advanced semiconductor fabrication.