Two-dimensional dopant profiling by electrostatic force microscopy using carbon nanotube modified cantilevers.

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• Accurate dopant profiling is crucial for semiconductor device fabrication and characterization.
• Existing techniques face limitations in resolution and applicability to buried dopant distributions.
• Nanoscale semiconductor devices, such as sub-45 nm complementary metal-oxide-semiconductor (CMOS) field-effect transistors, require advanced characterization methods.

Purpose of the Study:

• To demonstrate a novel two-dimensional (2D) dopant profiling technique.
• To enhance the resolution of electrostatic force microscopy (EFM) for nanoscale dopant analysis.
• To validate the feasibility of the technique for characterizing sub-45 nm CMOS field-effect transistors.

Main Methods:

• Utilizing a modified cantilever probe in EFM with an attached multiwalled carbon nanotube (MWNT).
• Trimming the MWNT tip apex to achieve single-walled carbon nanotube (SWNT) sharpness for ultra-high resolution.
• Applying the carbon nanotube-probed EFM (CNT-probed EFM) to profile 2D buried dopant distribution.

Main Results:

• Achieved dopant feature resolution within 10 nm in air.
• The achieved resolution approaches that of ultra-high vacuum scanning tunnelling microscopy (UHV STM).
• Successfully profiled 2D buried dopant distribution under a nanoscale device structure.

Conclusions:

• The CNT-probed EFM technique offers a viable method for high-resolution 2D dopant profiling.
• This technique is feasible for the characterization of advanced nanoscale semiconductor devices, including sub-45 nm CMOS FETs.
• The ultra-sharp CNT tip significantly enhances the spatial resolution of EFM for dopant analysis.