Characterization of SiO₂ Etching Profiles in Pulse-Modulated Capacitively Coupled Plasmas

Area of Science:

• Materials Science
• Plasma Physics
• Semiconductor Manufacturing

Background:

• High aspect ratio contact hole etching is crucial for semiconductor manufacturing.
• Pulse-modulated plasma offers solutions to etching challenges but lacks detailed mechanistic understanding.
• Micro-trenching and poor sidewall angle control are persistent issues in SiO2 etching.

Purpose of the Study:

• To elucidate the mechanisms by which pulse-modulated plasma improves SiO2 etching.
• To analyze the impact of various pulsed plasma parameters on etching characteristics.
• To provide insights for optimizing SiO2 etching and developing advanced plasma processing simulators.

Main Methods:

• Investigated SiO2 etching characteristics under diverse pulsed plasma conditions.
• Utilized plasma diagnostics to analyze plasma parameters.
• Correlated plasma parameters (self-bias, radical density, electron density) with etching outcomes.

Main Results:

• Explained micro-trenching disappearance through self-bias modulation.
• Interpreted sidewall angle increase with power off-time via radical species density and self-bias.
• Understood etching-to-deposition transition with decreased peak power via self-bias and electron density.

Conclusions:

• Established clear relationships between pulsed plasma parameters and SiO2 etching behavior.
• Provided a mechanistic understanding of pulse-modulated plasma benefits in high aspect ratio etching.
• This research offers a foundation for optimizing SiO2 etching and enhancing plasma processing simulations.