Capacitive Measurements of SiO₂ Films of Different Thicknesses Using a MOSFET-Based SPM Probe

Area of Science:

• Materials Science
• Electrical Engineering
• Nanotechnology

Background:

• Conventional probes struggle with thick oxide films due to low capacitance.
• Analyzing passivation layers in integrated circuits is crucial for device reliability.
• Subsurface imaging of dielectric materials requires advanced techniques.

Purpose of the Study:

• To develop and validate a scanning probe microscopy (SPM) technique for imaging thick dielectric layers.
• To assess the feasibility of using MOSFET-based SPM for analyzing integrated circuit passivation layers.
• To investigate the electrical characteristics and frequency response of the SPM system.

Main Methods:

• Utilized scanning probe microscopy (SPM) based on a metal-oxide-silicon field-effect transistor (MOSFET).
• Imaged interdigitated electrodes coated with silicon dioxide films (400-500 nm thick).
• Performed linearity and frequency response measurements to characterize the system.

Main Results:

• The SPM signal intensity correlated with the thickness of the silicon dioxide film.
• The frequency response measurements accurately reflected the electrical properties of the MOSFET, tip, and sample.
• Demonstrated successful imaging of thick dielectric layers, overcoming limitations of conventional probes.

Conclusions:

• MOSFET-based SPM is a viable technique for analyzing thick dielectric layers, including passivation layers in integrated circuits.
• The method offers potential for subsurface imaging of various dielectric materials.
• This approach enhances the analysis capabilities for back-end-of-line (BEOL) processes.