Controllable optical emission spectroscopy diagnostic system for analysis of process chemistries

Area of Science:

• Plasma Physics
• Materials Science
• Process Engineering

Background:

• Optical emission spectroscopy (OES) is a standard technique for plasma etch end point detection.
• Newer plasma systems present challenges due to low optical emission or limited optical access, hindering traditional OES effectiveness.

Purpose of the Study:

• To develop and present a novel OES diagnostic system utilizing a variable electron beam (e-beam) to overcome limitations in plasma etch end point detection.
• To demonstrate the feasibility and advantages of this e-beam enhanced OES system through initial experimental results.

Main Methods:

• Development of a new OES diagnostic system incorporating a variable electron beam.
• Experimental testing to evaluate the system's performance and data acquisition capabilities.
• Analysis of the correlation between optical emission intensity and e-beam current.

Main Results:

• A strong correlation was observed between optical emission intensity and e-beam current, a measurable electrical parameter.
• The observed correlation provides a method for normalizing optical signals and enabling feedback control of the plasma source.
• Different spectral lines showed measurable responses based on electron energy, indicating a new diagnostic parameter.

Conclusions:

• The developed variable e-beam OES system effectively addresses limitations of traditional OES in challenging plasma environments.
• The correlation between optical emission and e-beam current allows for robust signal normalization and closed-loop plasma process control.
• The energy-dependent response of spectral lines offers enhanced analytical capabilities for precise end point determination in plasma etching.