AVS 59th Annual International Symposium and Exhibition
    Helium Ion Microscopy Focus Topic Thursday Sessions
       Session HI+AS+BI+NS-ThM

Invited Paper HI+AS+BI+NS-ThM9
Dopant Contrast in Helium Ion Microscopy

Thursday, November 1, 2012, 10:40 am, Room 19

Session: Imaging and Lithography with the Helium Ion Microscope
Presenter: D. Fox, Trinity College, Ireland
Authors: Y. Chen, Trinity College, Ireland
H. Zhang, Trinity College, Ireland
D. Fox, Trinity College, Ireland
C.C. Faulkner, Trinity College, Ireland
J. Wang, Trinity College, Ireland
J. Boland, Trinity College, Ireland
J. Donegan, Trinity College, Ireland
Correspondent: Click to Email
Innovation in metrology is crucial to the future of semiconductor industry, since the miniaturization of transistors demands novel characterization technologies at and beyond the nanometre scale. Recent research has demonstrated that dopant contrast in the Helium-ion Microscope (HIM) is plausible and the HIM is a competitive platform for quantitative secondary-electron (SE) dopant mapping in terms of throughput, sensitivity, and resolution. However, the contrast mechanism of SE imaging is still debatable and it hinders further development of the technique. In this research, quantitative HIM dopant contrast of gallium-doped silicon samples has been investigated and compared with the contrast observed in a scanning electron microscope (SEM). Beam-sample interaction, signal general, as well as detection configuration have been considered via using a range of detectors in the two microscopes. It has been found that the Everhart-Thornley (E-T) secondary electron detector attached to HIM provides similar contrast to the images acquired from the InLens detector attached to SEM, while contrast reversal is observed with the SEM E-T detector. The contrast reversal also depends on the Dwell time. We have confirmed that the HIM is more sensitive to type-I SEs and a capacitance model based on charging effect has been proposed to explain the contrast reversal. Our results indicate that quantitative dopant contrast in the HIM is promising, while charging effect and imaging conditions must be carefully considered.