A study of plasma-deposited amorphous SiO2 films using infrared absorptiontechniques

Amorphous SiO2 (a-SiO2) films were prepared at 300 degreesC by means of pla sma-enhanced chemical vapor deposition (PE-CVD) using a SiH4-O-2 mixture. T he properties of infrared (IR) absorption for Si-O bonds have been investig ated as a function of film thickness, d. It was found that the apparent abs orbances, alpha (app), for both 800 and 1050 cm(-1) bands, arising from Si- O bending and stretching modes, respectively, were proportional to d as alp ha (app) = k X d. The proportionality constants k for 800 and 1050 cm(-1) b ands 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 nondes tructively using IR absorption techniques. However, the integrated absorpti on intensity for the 1050 cm(-1) bands increased with increasing d. In cont rast, the integrated absorption intensity for 800 cm(-1) band was independe nt of d. The properties of infrared absorption for both Si-O stretching and bending modes are discussed. (C) 2001 Elsevier Science B.V. All rights res erved.