Comprehensive Study of Inversion Capacitance in Metal-Insulator-Semiconductor Capacitor With Existing Oxide Charges

The impact of oxide charges on the metal-insulator-semiconductor (MIS) device's capacitance (C) and conductance (G) was studied in this work. A model to calculate MIS device's C and G under the considerations of oxide charges, doping concentration, device dimension, and AC signal frequency (omega) was proposed. A relation of C - C-D proportional to omega(-0.5) was found, where C-D is the depletion capacitance under the electrode. The relation is examined by the experimental and the TCAD simulation. The capacitance of a MIS device with oxide charges can be calculated according to the proposed model and is well-matched with the TCAD simulation under light to moderate doping concentration. For heavily doped substrates, the modeling deviates from the simulation results because of quantum confinement and concentration-dependent mobility. However, the trend of the capacitance value is still able to be estimated by our modeling. From the modeling, it was found that for Q(ox)/q = 7.5 x 10(10)( )cm(-2), the MIS capacitor with substrate doping concentration N-A = 1 x 10(15) cm(-3) exhibits a long lateral AC signal decay length of 52 mu m at 1 kHz under the inversion region. The findings of this work are fundamental and are helpful for device engineering.

Automated summary

This study investigated the influence of oxide charges on the capacitance and conductance of metal-insulator-semiconductor (MIS) devices, proposing a model that takes into account various factors. Experimental and TCAD simulation results confirmed the model's accuracy in calculating capacitance for MIS devices with oxide charges. While heavily doped substrates may deviate from the model due to quantum effects, the overall trend of capacitance values can still be estimated using this approach.