MOSFETs reliability: electron trapping in gate dielectric

Trench DMOS interface trap characterization by three-terminal charge pumping measurement

“…Table 1 shows 3T-CP setup parameters. The charge pumping parameters has been determined experimentally to select the appropriate charge pumping values [1,2]. The experimental base level voltage is selected such that the gate potential is swept from deep inversion (gate bias above threshold voltage, V t ) to deep accumulation (gate bias below flat band voltage, V fb ) in order to ensure complete filling (by capture) and emptying (by recombination) of interface states [16,17].…”

“…Charge pumping (CP) measurement technique has been successfully applied in the past years to characterize fast interface traps in MOS transistors [1,2]. It is known to offer a simple, direct and powerful technique of assessing interface quality (interface damage) for planar structures [3].…”

“…Variations in CP technique can quantify the SiO 2 /Si interface states density and the electrical response of this interface to different types of stress [3]. CP has become the most powerful and reliable technique to characterize fast interface properties of MOS devices, specifically the average density of interface traps (D it ), the energy and spatial distribution and even the geometric mean value of the capture cross section for electrons and holes [1,2,4].…”

“…However, the application of CCP is more profound to the planar MOSFET [3,7] with substrate contact since CCP setup needs the four electrical contacts to the gate, drain, source, and substrate where it measures the I CP from the substrate [1][2][3]7,8]. Therefore, a practical three-terminal charge pumping (3T-CP) technique presented by Passmore et al [3,7] for vertical transistor structures is found to be suitable for trench DMOS with the absence of substrate contact.…”

“…The pulse is used to alternate the U-shaped trench-gated Vertical MOSFET (UMOSFET) between accumulation and inversion modes [3,7]. 3T-CP is important to evaluate the effects of hot carrier (HC) [1,2,5,7] and Fowler-Nordheim (FN) stress [1][2][3]7] on nchannel UMOSFET. The numerical CP values are calculated using the formula developed by Groeseneken et al [4].…”