AVS 47th International Symposium
    Material Characterization Thursday Sessions
       Session MC-ThA

Paper MC-ThA5
Dopant-Induced Contrast of Si Devices in PEEM

Thursday, October 5, 2000, 3:20 pm, Room 207

Session: Evolving Technologies in Surface Analysis
Presenter: V.W. Ballarotto, University of Maryland
Authors: V.W. Ballarotto, University of Maryland
K. Siegrist, University of Maryland
R.J. Phaneuf, University of Maryland
E.D. Williams, University of Maryland
Correspondent: Click to Email
Spatial variation of doping, such as in a pn junction, produces contrast in photoelectron emission microscopy (PEEM) that may be useful for dopant profiling, failure analysis, or as a processing diagnostic of Si. The contrast mechanism arises from reduction of the effective photothreshold when Si is heavily to degenerately doped. We report on a quantitative investigation of doping-induced contrast in PEEM images of Si devices. The calibration samples consist of p-type (B) stripes of different dopant concentrations and line separations, written on n-type (N@sub d@=10@super 14@ cm@super -3@) Si(001) substrates. Using a near-threshold light source, we find that the signal intensity increases monotonically with B concentration over a range of doping from 1x10@super 18@ to 6x10@super 20@ cm@super -3@. The measured intensity ratios are in good agreement with a calculation based on photoemission from the valence band. In addition, PEEM images of memory chip devices acquired through a 2000 Å SiO@sub 2@ layer and showing clear doping contrast will be shown. This depth sensitivity and the potential for improved doping contrast will be discussed in terms of the incident photon energy above threshold. This work is supported by Advance Research Development Activity (ARDA) grant number: 97-C-3048.