An investigation of silicon oxide thin film by atomic layer deposition

SiO2 thin films were prepared on p-type Si (100) substrates by atoirric layer deposition (ALD) using SiH2Cl2 and O-3(1.5 at.%)/O-2 as precursors at 300degreesC. The growth rate of the deposited films increased linearly with increasing amount of simultaneous SiH2Cl2 and O-3 exposures, and was saturated at about 0.35 nm/cycle with the reactant exposures of more than 3.6 x 10(9) L. A larger amount Of O-3/O-2 than that of SiH2Cl2 was required to obtain a saturated deposition reaction. The composition of the deposited film also varied with O-3/O-2 exposure at a fixed SiH2Cl2 exposure. The Si/O ratio gradually decreased to 0.5 with increasing amount Of O-3/O-2 exposure. Finally, we also compared the physical and electrical characteristics of the ALD films with those of the films deposited by conventional chemical vapor deposition (CVD) methods. In spite of low process temperature, the SiO2 film prepared by the ALD method was in wet etch rate, surface roughness, leakage current and breakdown voltage superior to that by other several CVD methods.