Properties of silicon dioxide films prepared by low-pressure chemical vapor deposition from tetraethylorthosilicate

Abstract

The 20 to 100-nm thick tetraethylorthosilicate (TEOS)-derived SiO2 films were deposited on silicon substrates in the 650–780 °C temperature range by low-pressure chemical vapor deposition. The main properties of the as-deposited and annealed films such as refractive index, etch rate, stress, step coverage, and density are reported. Infrared (IR) spectra and the electrical properties were studied as a function of process parameters including temperature, pressure, oxygen, and TEOS flow. These studies have shown that TEOS-SiO2 films have very good thickness uniformity and conformal step coverage which can be controlled by adjusting the process pressure. IR spectra show that TEOS-SiO2 films are deposited as stoichiometric oxides. Annealing results in the removal of absorbed water and Si–OH groups, and in an increase of the number of Si–O–Si bonds. The electrical characteristics, such as breakdown field strength for films deposited on POCl3 -doped polysilicon, are comparable to those of SiO2 films thermally grown at 1100 °C in dry O2 atmosphere.