Gadolinium nitride films deposited using a PEALD based process

Abstract

Gadolinium nitride films have been deposited on Si(100) using a plasma-enhanced ALD (PEALD) based process. The deposition was carried out using tris(methylcyclopentadienyl)gadolinium {Gd(MeCp)(3)} and remote nitrogen plasma, separated by argon pulses. Films were deposited at temperatures between 150 and 300 C and capped with tantalum nitride to prevent post-deposition oxidation. Film composition was initially assessed using EDX and selected samples were subsequently depth profiled using medium energy ion scattering (MEIS) or AES. X-ray diffraction appears to show that the films are effectively amorphous. Films deposited at 200 degrees C were found to have a Gd:N ratio close to 1:1 and a low oxygen incorporation (similar to 5%). Although the growth was affected by partial thermal decomposition of the Gd(MeCp)3, it was still possible to obtain smooth (Ra.=similar to 0.7 nm) films with good thickness uniformity (97%). Less successful attempts to deposit gadolinium nitride using thermal ALD with ammonia or mono-methyl-hydrazine are also reported.