Thermal Desorption and Infrared Studies of Plasma-Enhanced Chemical Vapor Deposited SiO Films with Tetraethylorthosilicate

Thermal desorption and Fourier transform infrared spectroscopies were used to study plasma-enhanced chemical vapor deposited SiO films from tetraethylorthosilicate. Significant water desorption and concomitant structural changes were observed for the films during subsequent heat treatments between 100 and 700°C. The films exhibited three distinct water desorption states. The desorption temperatures were approximately 100-200°C for the first state, 150-300°C for the second state, and 350-650°C for the third state. Air exposure experiments revealed that the first and second states resulted from absorbed water and the third state from constitution water. The first and second desorption states were confirmed to originate from liquid like water and water molecules hydrogen-bonded to Si-OH bonds at macropore sites in the films, respectively. The third desorption state was found to result from Si-OH bonds formed during the film growth. This desorption of constitution water was considered to be accompanied by a microstructural change of the films.