Scandium oxide deposited by high-pressure sputtering for memory devices: Physical and interfacial properties

Abstract

Scandium oxide (ScO(x)) thin layers are deposited by high-pressure sputtering (HPS) for physical and electrical characterization. Different substrates are used for comparison of several ScO(x)/Si interfaces. These substrates are chemical silicon oxide (SiO(x)), H-terminated silicon surface and silicon nitride (SiN(x)), obtained by either electron-cyclotron-resonance chemical vapor deposition or plasma enhanced nitridation of the Si surface. Transmission electron microscopy images show that a 1.7 nm thick SiO(x) layer grows when ScO(x) is deposited on H-terminated silicon surface. We demonstrate that interfacial SiN(x) has some advantages over SiO(x) used in this work: its permittivity is higher and it presents better interface quality. It also avoids Si oxidation. An improvement of one order of magnitude in the minimum of interface trap density is found for SiN(x) with respect to the SiO(x), reaching values below 2 x 10(11) cm(-2) eV(-1). HPS deposited ScO(x) films are polycrystalline with no preferential growth direction for the used deposition conditions and their properties do not depend on the substrate. This material could be a candidate for high-k material in flash memory applications.