Hole structure and its formation in thin films of hydrolyzed poly(styrene maleic anhydride) alternating copolymers

Maleic anhydride moieties on the backbone chains of poly(styrene maleic anh ydride) alternating copolymer (SMA) hydrolyzed in a THF solution containing water and hydrochloric acid. Well-arrayed holes were obtained in spin-cast thin hydrolyzed SMA films on a single crystal silicon wafer, and the hole diameter and its distribution were measured with AFM data. Results showed t hat the hole size was almost uniform, and was influenced by water content w hen spin speed was kept unchanged. The THF solution with a SMA concentratio n of about 1 g/mL and weight ratio H2O/SMA of 1/3 produced holes having an average diameter of 0.60 mu m and depth of 206.12 nm, when cast at a spin s peed of 1400 rpm. It was noted that the formation of the holes in thin hydr olyzed SMA film was different from the dewetting process in thin homopolyme r films, but was associated with the intrinsic properties of the copolymer forming the films. The surfactant effect of hydrolyzed SMA was suggested to interpret the formation of the holes. The holes were described to be the t races of water droplets that were emulsified by the hydrolyzed SMA during c asting. (C) 2000 John Wiley & Sons, Inc.