Amorphous SiO2 (a-SiO2) films were prepared at 300 degreesC by means of plasma-enhanced chemical vapor deposition (PE-CVD) using a SiH4-O-2 mixture. The properties of infrared (IR) absorption for Si-O bonds have been investigated as a function of film thickness, d. It was found that the apparent absorbances, alpha (app), for both 800 and 1050 cm(-1) bands, arising from Si-O bending and stretching modes, respectively, were proportional to d as alpha (app) = k X d. The proportionality constants k for 800 and 1050 cm(-1) bands are estimated to be 3.2 x 10(3) and 2.9 x 10(4) cm(-1), respectively. Consequently, the film thickness for PE-CVD a-SiO2 can be determined nondestructively using IR absorption techniques. However, the integrated absorption intensity for the 1050 cm(-1) bands increased with increasing d. In contrast, the integrated absorption intensity for 800 cm(-1) band was independent of d. The properties of infrared absorption for both Si-O stretching and bending modes are discussed.