Characterization of Flexible Low-k Dielectric SiCOH Films Prepared by Plasma-Enhanced Chemical Vapor Deposition of Tetrakis(trimethylsilyloxy)Silane Precursor.

Abstract

SiCOH thin films were deposited on rigid silicon (Si) wafers and flexible ITO/PEN substrates via plasma-enhanced chemical vapor deposition at room temperature using a tetrakis(trimethylsilyloxy)silane (TTMSS) precursor. Different chemical compositions of hydrocarbon and Si-O bondings were obtained depending on substrate types and deposition conditions. The main chemical compositions of the as-deposited films were observed as C-Hx (x = 2, 3) stretching, Si-CH₃ bending, Si-O-Si stretching, and H-Si-O bending/Si-CH₃ stretching modes. With regard to the as-deposited films, the dielectric constant increased from 1.83 to 3.45 when the plasma power increased from 20 to 80 W and the lowest leakage current of 1.76×10-4 A/cm² was obtained at the plasma power of 80 W. After bending tests with 1000, 5000, and 10000 bending cycles, the dielectric constants of the SiCOH films increased and leakage currents decreased. The structures of the SiCOH films after the bending tests were highly complicated with a variety of chemical bonding combinations. Higher peak intensity and peak area of main chemical bonding were obtained with the increased bending cycles, resulting in the increase in dielectric constants. It should be noted that the film with small changes in peak area fractions of the bending and stretching modes showed good electrical and mechanical stabilities after bending tests.