Stress Evolution Of Sol-gel-derived Silica Coatings During Heating: The Effects Of The Chain Length Of Alcohols As Solvents

摘要

The effects of the solvent on in-plane stress evolution were studied on sol-gel-derived silica gei coatings during heating. Si(OC_2H_5)_4-H_2O-HNO_3-ROH {ROH = CH_3OH, C_2H_5OH, n-C_3H_7OH, and n-C_4H_9OH) solutions were prepared where the mole ratio Si(OC_2H_5)_4:H_2O:HNO_3 = 1:8:0.01 and the volume ratio Si(OC_2H_5)_4: R0H = 1:1.1. Silica gel films were deposited by spin coating on Si (100) wafers 4 in. in diameter, and heated at 5 ℃/min up to 500 ℃, where in situ stress measurement was conducted by measuring the substrate curvature. The stress was tensile and increased with increasing temperature. The stress was found to be identical below 200 ℃ between the films prepared with different alcohols while the stress above 200 ℃ was larger in the order, n-C_4H_9OH< n-C_3H_7OH = C_2H_5OH