Molecular depth profiling by wedged crater beveling.

Area of Science:

• Materials Science
• Surface Science
• Analytical Chemistry

Background:

• Molecular depth profiling is crucial for analyzing thin films and interfaces.
• Characterizing organic materials requires precise depth resolution and understanding surface topography.
• Previous methods lacked consistent depth resolution across varying depths.

Purpose of the Study:

• To investigate the effectiveness of wedge-crater analysis for molecular depth profiling.
• To determine the influence of temperature and ion beam parameters on erosion rate and surface roughness.
• To achieve sub-10 nm depth resolution for organic films.

Main Methods:

• Time-of-flight secondary ion mass spectrometry (TOF-SIMS) for chemical analysis.
• Atomic force microscopy (AFM) for surface topography and roughness measurements.
• Creation of wedge-shaped craters using a 40-keV C(60)(+) cluster ion beam.

Main Results:

• Constant erosion rate and reduced surface roughness observed at liquid nitrogen temperature.
• Erosion rate decreased by ~1/3 and roughness increased at room temperature.
• Sub-10 nm depth resolution achieved routinely under optimized conditions (glancing angles, lower beam energy).

Conclusions:

• Wedge-crater beveling is an effective tool for optimizing molecular depth profiling.
• Temperature significantly impacts erosion rate and surface roughness during analysis.
• Optimized TOF-SIMS and AFM parameters enable high-resolution depth profiling of organic materials.