Leakage current limit of time domain reflectometry in ultrathin dielectric characterization

Abstract

The accurate characterization of highly leaky dielectrics has been a serious challenge in MOSFET and capacitor studies. We have shown that time domain reflectometry (TDR) can be used to measure the capacitance of ultrathin SiO 2 MOS capacitors even at a leakage current density as high as >3000 A/cm 2 , which is approximately 10 3 times higher than the limit of a conventional impedance analyzer. The extremely short interaction time of the TDR C-V method makes the TDR capacitance measurement more immune to the leakage current. Since the TDR C-V method does not require special high-frequency test structures other than a ground-signal pad pattern, the TDR C-V method is a promising capacitance measurement method for leaky dielectrics.

Extraction of Effective Mobility from nMOSFETs With Leaky Gate Dielectric Using Time Domain Reflectometry

“…Since the split C-V characteristics of scaled MOSFET can be obtained without any complex RF reference test structure by simply changing the connection configuration of the GSGG probes, TDR split C-V method can be useful for in-line measurements of highly leaky MOSFET structures with the gate leakage current density up to ∼3000 A/cm 2 [23]. As for the restriction on device dimension for TDR, the rise time of step pulse determines the minimum capacitance that can be measured by TDR.…”