Park Systems Application Note

Tuesday, September 24, 2019 - 13:00
Image: Park NX-Hivac AFM.
Park Systems NX-Hivac allows failure analysis engineers and researchers to improve the sensitivity and resolution of their measurements through high vacuum scanning spreading resistance microscopy (SSRM).
Because high vacuum scanning offers greater accuracy and better repeatability than ambient or dry N2 conditions, users can measure a wide range of dopant concentrations and signal response in failure analysis applications.
The high vacuum scanning spreading resistance microscopy (SSRM), available on Park NX-Hivac, enables 2D carrier profiling of next generation devices and measures the high resolution SSRM image under high vacuum conditions to improve production yield. 
The high vacuum SSRM measurements show much higher accuracy and resolution than in ambient condition.
Due to the very high sensitivity and responsiveness to the current signal, SSRM ensures accurate measurements and repeatability, providing a high-level tool for semiconductor failure analysis.
In addition, the integration of a new operational AFM mode called PinPoint with SSRM enables acquiring topography, electrical and mechanical property data simultaneously.
Furthermore, operating in an approach-retract manner greatly reduces friction and tip wear compared to standard SSRM.
SSRM in Air vs. High Vacuum
SSRM enables:
  • higher sensitivity and resolution in high vacuum compared to the ambient conditions
  • higher accuracy and repeatability of the measurements
  • acquisition of multiple properties simultaneously (electrical, mechanical, topography)
  • longer tip lifetime and reduced sample damage when performed in PinPointTM mode
  • frictionless imaging when performed in PinPointTM mode
Also conductive AFM (C-AFM) performed in High Vacuum significantly improves material analysis.
C-AFM simultaneously measures topography and electrical properties (conductivity) of samples by using the AFM tip as a nanometer-scale electrical probe.
SSRM of Li ion battery electrode.
More specifically, it monitors the current flow between the conductive tip and sample, and when the bias is applied.
At the same time, it records the cantilever deflection as the tip scans over the sample surface.
The measurements can be performed in contact mode, tapping mode, or PinPoint™ mode.
The latter one operates in an approach-retract manner, ensuring a frictionless operation which eliminates the lateral force caused by continuous tip-sample contact. 
Performing C-AFM measurements in High Vacuum (HV) improves the quality of the image significantly.
In particular, the measured current increases by three orders of magnitude in comparison to ambient conditions and features high homogeneity.
The current maps taken in HV also show remarkably more details than taken in air.
C-AFM in Air vs. High Vacuum: C-AFM from the same 3-4 layered MoS2 sample showing the increased current level and sensitivity under high vacuum. (a) and (b) Topography (c) current images in air at 5 V bias and (d) current images taken immediately after pumping to high vacuum at 0.5 V bias. The data taken in air and high vacuum was acquired using identical parameters: same probe with spring constant k of 7 N/m, set point of 10 nN, and 1 Hz scan rate. Scale bar is 500 nm. Image courtesy: IMEC, Leuven, Belgium, +49 621-490-896-50
Website developed by S8080 Digital Media