Plasma enhanced atomic layer deposition of silicon nitride using neopentasilane

Abstract

Progress in transistor scaling has increased the demands on the material properties of silicon nitride (SiNx) thin films used in device fabrication and at the same time placed stringent restrictions on the deposition conditions employed. Recently, low temperature plasma enhanced atomic layer deposition has emerged as a viable technique for depositing these films with a thermal budget compatible with semiconductor processing at sub-32 nm technology nodes. For these depositions, it is desirable to use precursors that are free from carbon and halogens that can incorporate into the film. Beyond this, it is necessary to develop processing schemes that minimize the wet etch rate of the film as it will be subjected to wet chemical processing in subsequent fabrication steps. In this work, the authors introduce low temperature deposition of SiNx using neopentasilane [NPS, (SiH3)4Si] in a plasma enhanced atomic layer deposition process with a direct N2 plasma. The growth with NPS is compared to a more common precursor, trisilylamine [TSA, (SiH3)3 N] at identical process conditions. The wet etch rates of the films deposited with NPS are characterized at different plasma conditions and the impact of ion energy is discussed.