Piezoresistive sensors for scanning probe microscopy

Area of Science:

• Materials Science
• Nanotechnology
• Sensor Technology

Background:

• Scanning probe microscopy (SPM) demands highly sensitive and versatile sensors for nanoscale measurements.
• Piezoresistive sensors offer a promising platform for SPM applications due to their fabrication compatibility and signal transduction mechanism.

Purpose of the Study:

• To develop a family of piezoresistive sensors for various SPM techniques using a unified fabrication approach.
• To demonstrate the capability of these sensors for high-resolution surface topography, capacitance, friction, and thermal measurements.

Main Methods:

• Advanced silicon micromachining and standard CMOS processing were employed for sensor fabrication.
• A common piezoresistive detection scheme was adapted for different SPM applications.
• Finite Element Method (FEM) simulations guided the design optimization for specific sensor functionalities.

Main Results:

• A piezoresistive cantilever achieved 0.1 nm resolution for atomic force microscopy topography measurements.
• A microprobe enabled scanning capacitance and tunneling microscopy with capacitance measurements down to 10⁻²² F.
• A multipurpose sensor achieved 1 nN resolution for lateral force microscopy friction measurements.
• A femtocalorimeter detected heat energy in the range of 50 pJ.

Conclusions:

• A single fabrication strategy based on silicon micromachining and CMOS processing can yield a diverse range of high-performance piezoresistive sensors for SPM.
• The developed sensor family significantly expands the capabilities of SPM for nanoscale material characterization.
• This work highlights the potential of piezoresistive technology for advancing nanoscale metrology and sensing.