Study on channel depletion in metal-oxide-semiconductor field effect transistor using top-view imaging through scanning capacitance microscopy

Carrier profiles within the near-surface channel region of n-type metal-oxide-semiconductor field-effect transistors (n-MOSFETs) have been examined using scanning capacitance microscopy (SCM). After the removal of a poly-Si gate electrode, we were able to assess the qualitative local carrier concentration within specified regions of an n-MOSFET using static capacitance (dC/dZ) measurement with its bias dependence (dC/dZ-V spectra). We found that the dC/dZ-signal at the center of the channel region lowers as the gate length is reduced. This result is attributed to the carrier depletion within the channel, which is consistent with the threshold voltage (V-th) characteristics of the device properties. Copyright (C) 2008 John Wiley & Sons, Ltd.