Mapping of electrostatic potential in deep submicron CMOS devices by electron holography

Area of Science:

• Materials Science
• Semiconductor Physics
• Nanotechnology

Background:

• Accurate characterization of electrostatic potential is crucial for understanding dopant diffusion in advanced semiconductor devices.
• Traditional methods face limitations in spatial resolution and quantitative analysis for nanoscale structures.

Purpose of the Study:

• To demonstrate the effectiveness of off-axis electron holography for quantitative 2D electrostatic potential mapping.
• To validate the accuracy of electron holography against established techniques like secondary ion mass spectroscopy and process simulation.
• To assess the suitability of electron holography for analyzing dopant diffusion in deep-submicron devices.

Main Methods:

• Quantitative two-dimensional mapping of electrostatic potential using off-axis electron holography.
• Achieving a spatial resolution of 6 nm and a sensitivity of 0.17 V.
• Comparison of electron holography results with process simulation and secondary ion mass spectroscopy for junction depth and potential variation.

Main Results:

• Electron holography successfully generated quantitative 2D electrostatic potential maps.
• Estimates of junction depth and electrostatic potential variation showed close agreement between electron holography, process simulation, and secondary ion mass spectroscopy.
• Measurement artifacts from sample charging and surface dead layers were found to be negligible with proper sample preparation.

Conclusions:

• Off-axis electron holography is a viable and effective method for quantitative 2D analysis of electrostatic potential.
• This technique shows significant promise for detailed studies of dopant diffusion in deep-submicron semiconductor devices.
• Electron holography offers a powerful tool for nanoscale device characterization and process development.