Investigation of silicon oxide thin films prepared by atomic layer deposition using SiH2Cl2 and O-3 as the precursors

Abstract

Silicon dioxide thin films were deposited on p-type Si (100) substrates by atomic layer deposition (ALD) by alternating SiH2Cl2 and O-3(1.5 at%)/O-2 exposures at 300degreesC. O-3 was generated by corona discharge inside the delivery line of O-2. The oxide film was deposited mainly from O-3, not from O-2, because we could not observe the deposited film on the substrate without corona discharge under the same process condition. The growth rate of the deposited films increased linearly with increasing amount of simultaneous SiH2O2 and O-3 exposures, and was saturated at approximately 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. When the amount of O-3/O-2 exposure was varied at a fixed SiH2Cl2 exposure of 1.2 x 10(9) L, the growth rate of oxide film increased with O-3 exposure and was saturated at approximately 0.28 nm/cycle with O-3/O-2 exposure of more than 2.4 x 10(9) L. The composition of the deposited film also varied with O-3/O-2 exposure. The Si/O ratio gradually decreased to 0.5 with increasing amount of O-3/O-2 exposure. Finally, we also compared the characteristics of the ALD films with those of the films deposited by conventional chemical vapor deposition (CVD) methods. The silicon oxide film prepared by the ALD method at 300degreesC showed stoichiometry, wet etch rate and average surface roughness comparable to those of the films deposited by low-pressure CVD (LPCVD) and atmospheric-pressure CVD (APCVD) at deposition temperatures ranging from 400 to 800degreesC.