PECVD Synthesis of Polysiloxane-Like Thin Films with Very Low Contact Angle Hysteresis

This work deals with the control of the contact angle hysteresis on surfaces of thin films grown by RF-PECVD from octamethylcyclotetrasiloxane. Two growth modes are obtained, depending on the ratio W/Fp of the plasma power to the precursor flow rate. At high ratio, fragmentation and dissociation prevail, otherwise oligomerization dominates. There is a continuous evolution of the film conformation. Surface energy depends linearly on W/Fp, whereas the chemical composition hardly varies. The contact angle hysteresis only depends on the growth mode in the oligomerization domain. Preserving the cyclic character of the precursor favours the decrease of the triple line anchorage—Δθ < 3°—in wettability test.