Investigation into SiO₂ Etching Characteristics Using Fluorocarbon Capacitively Coupled Plasmas: Etching with...

Area of Science:

• Materials Science
• Plasma Physics
• Chemical Engineering

Background:

• Silicon dioxide (SiO2) is a critical material in semiconductor manufacturing.
• Plasma etching is a key process for patterning SiO2 films.
• Understanding plasma-etching mechanisms is vital for process optimization.

Purpose of the Study:

• To investigate SiO2 etching characteristics using pulsed radio-frequency capacitively coupled plasma.
• To identify an optimal etching process window based on radical flux.
• To analyze the effect of pulse-off time on SiO2 etch depth and profile.

Main Methods:

• Etching of patterned SiO2 using argon and fluorocarbon gas mixtures in a pulsed plasma.
• Plasma diagnostics to measure radical density, electron density, and self-bias voltage.
• Systematic variation of pulse-off time at different radical flux levels.

Main Results:

• An etching process window was identified where etch depth correlates with radical flux.
• Increasing pulse-off time enhanced etch depth at low radical flux.
• Increasing pulse-off time reduced etch depth at high radical flux.
• Opposing trends attributed to the neutral to ion flux ratio.

Conclusions:

• Pulse-off time is a critical parameter for controlling SiO2 etch depth in pulsed plasmas.
• The neutral to ion flux ratio plays a key role in determining etching outcomes.
• Tailoring pulse-off time enables precise control over SiO2 etching processes.