Synthesis and structure characterization of low dielectric constant MSQ films by using octamethyl cyclotetrasiloxane (D4) as a porosity promotion agent

•The MSQ was prepared at room temperature. It is very good to commercialize.•D4 liquid was network structure and was used as a porosity promotion agent.•Anneal can change the dielectrics of thin films.

Low dielectric methylsilsesquioxane (MSQ) film can be synthesized by spin-coating on P–Si (100) wafer. Octamethyl cyclotetrasiloxane (D4) was used as a porosity promotion agent to MSQ film. Seven samples with different treatment were prepared. The dielectric constants of these MSQ films significantly lowered from 3.0 to 2.1. Fourier transform infrared spectroscopy was used to identify the Si–O–Si network structure, Si–O–Si cage structure and other bonds. The change of structure resulted in significant lowering of the dielectric constant (k). The capacitance–voltage (C–V) characteristic by HP4294A was used to determine the dielectric constant. Current–voltage (I–V) measurement by Keithley6517A was used to determine the breakdown electric field.