AVS 45th International Symposium
    Nanometer-scale Science and Technology Division Thursday Sessions
       Session NS-ThP

Paper NS-ThP5
Use of Phase Imaging Tapping Mode AFM to Spatially Resolve Areas of Different Doping Densities on Patterned Si Wafers

Thursday, November 5, 1998, 5:30 pm, Room Hall A

Session: Nanometer-Scale Science and Technology Division Poster Session
Presenter: M.W. Nelson, Colorado State University
Authors: M.W. Nelson, Colorado State University
P.G. Schroeder, Colorado State University
R. Schlaf, Colorado State University
B.A. Parkinson, Colorado State University
Correspondent: Click to Email
The continuously shrinking dimensions of integrated circuits demand new methods for spatially resolved characterization of doping profiles in patterned semiconductor structures. Scanning probe microscopies offer the lateral resolution required to characterize structures down to atomic dimensions. Among these methods atomic force microscopy (AFM) has the advantage that the imaging process does not depend on the conductivity of the sample surface which offers easy characterization of oxidized samples in ambient conditions. In our experiments we demonstrate the use of tapping mode AFM (TMAFM) with additionally applied bias to spatially resolve areas of different doping densities and types on Si wafers. We observed changes in the phase contrast in regions of different doping densities as a function of the applied bias. Additional measurements on metallic substrates revealed that the cantilever phase and resonance frequency are strongly influenced by the bias induced Coulomb force between cantilever and sample. This allowed the discussion of the observed phase contrast variations in terms of semiconductor surface potential changes depending on the applied bias and the doping type of the various areas.