In-line AFM characterization of STI profile at the 65 nm node with advanced carbon probes

Abstract

The present paper shows the characterization of the shallow trench isolation (STI) profile of 65 nm node ULSI logic products done with an automated AFM system and high-density carbon tips. The combined utilisation of special tips and dedicated analysis algorithms has allowed the precise measurement of both the step height between the isolation oxide and the silicon active area, and the depth of the divot that is generally formed at the isolation oxide's sidewalls. Moreover, the robustness of this methodology has been assessed by evaluating the maximum number measurement runs before the appearance of relevant artifacts due to tips' apex modifications. Finally, TEM cross-sections were run in order to determine the accuracy of the measurements.