Low dielectric constant SiOC(-H) films were deposited on p-type Si(100) substrates by plasma-enhanced chemical vapor deposition (PECVD) using dimethyldimethoxysilane (DMDMOS, C4H12O2Si) and oxygen gas as precursors. We studied the detailed electrical characterization of SiOC(-H)/p-Si(100) interfaces using different experimental parameters for using the multilevel interconnections in ultra large-scale integrated circuits (ULSI). To improve the SiOC(-H)/p-Si(100) interface, the wafer was cleaned using the RCA process and rinsed with deionized water. The deposited SiOC(-H) films were annealed at different temperatures ranging from 250 to 450 °C in a vacuum. The interface properties of the SiOC(-H)/p-Si(100) with Cu/SiOC(-H)/p-Si(100)/Al metal-insulator-semiconductor (MIS) structures were investigated by capacitance-voltage (C-V) measurement with a flat band shift by electric field stress. Trapped charge, fixed oxide charge, and the interface trap density of SiOC(-H) films were related to the dielectric breakdown and leakage current density at the SiOC(-H)/p-Si(100) interface. From these analyses, detailed electrical properties defining the interface states of the MIS structures were reported. © 2010 Elsevier B.V. All rights reserved.