Scanning Microwave Impedance Microscopy (sMIM)

Affordable solution for Nanoscale Mapping of electrical measurements

Introduction

Scanning Microwave Impedance Microscopy (sMIM) is a new mode of imaging using  AFM microscope. This mode measures the electrical properties of materials at length scales from 10’s of nanometers to microns. sMIM modules produce high quality images of local electrical properties with better than 50 nm resolution.The core of our technical approach is to utilize microwave reflections from a nm scale region of the sample directly under the sMIM probe. The magnitude and phase of these reflections is dominated by the local electrical properties. The sMIM measures these reflections as a function of position to create images of variations in dielectric constant and conductivity.The sMIM system provides two channels as output to the host AFM that can then be viewed as images in the AFM software. The two channels represent the permittivity (ε) and the conductivity (σ) of the imaged area. If the sample is a doped semiconductor (a non-linear) material, sMIM can provide the dC/dV amplitude (carrier concentration) and phase (carrier type: n or p) as well as the dR/dV amplitude.

Technology

sMIM Probes

This method is compatible with a wide range of materials: dielectrics, insulators, semiconductors, and metals. Unlike other conventional electrical modes for AFM, sMIM can simultaneously image these different materials classes without multiple setings or measurements.The typical imaging method for sMIM is contact mode, but it is also possible to image using non-contact scanning, tapping mode, and none-resonant scanning modes such as force curves and similar imaging techniques.The sMIM  system’s optimized electronics couple 3GHz frequency microwaves to a shielded probe. The microwaves generate a strong electromagnetic field in a very small spatial region at the probe tip. The sample interacts with this EM-field and the electronics detect the response. The sample response is determined by the local sample properties: ε,σ,& μ. The probes are batch fabricated MEMS devices (micro electrical mechanical systems) with a shielded front and backside and center transmission line.The probe shielding reduces stray coupling from the environment and  the cantilever. The probe radius is nominally 50nm to optimize signal strength and lateral resolution.The probe sample interface use a resistor and capacitor in parallel. This “leaky capacitor” presents an impedance mismatch to the 50 ohm system electronics, creating a reflection.

As the sMIM probe is moved across the sample surface there is a change in the impedance of this leaky capacitor and the resulting change in the real and imaginary parts of the reflected wave are output as two signal from the ScanWave electronics. These signals are digitized by the AFM to produce the sMIM-C and sMIM-R images synchronized with  the topography images.

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System Advantages

Benefits

sMIM is a non-destructive, fast, and direct way of measuring a material’s electrical properties.

  • Best Signal to noiseThe  ScanWave electronics and shielded probes produce the best signal-to-noise in the industry enabling more measurement sensitivity and lower noise floor for smaller signal measurements and allowing faster scanning.
  • Proprietary  Shielded ProbesThe integration of shielded probes reduces the stray capacitance and decouples the electrical information from the topography information.
  • System Flexibility
    • • Measure any material  –  insulator, conductor, or semiconductor without special sample prep.
    • • Image electrical  information and topography simultaneously.
    • • Ease   of use means fastertime to data
    • • dC/dV  and dR/dV  are standard system capabilities on the ScanWave system
  • • Easy to use
  • • High resolution
  • • Upgradeable
  • • Versatile

Applications

  • • Micro-electronics
  • • Nano-materials
  • • Doping profiles
  • • Biomedical
  • • Green Energy
  • • Photonic materials and devices

 

sMIM combined with Resiscope & HD-KFM = the best AFM electrical measurements package !

The integration of the sMIM system onto ResiScope & HD-KFM package provides the highest performance solution to measure high-resolution electrical properties.

ResiScope : The world’s greatest performance for AFM electrical characterization HD-KFM : High Definition KFM, much higher sensitivity & resolution
More information about ResiScope More information about HD-KFM