Double layer electrode and barrier system on hemispherical grain silicon for use with high dielectric constant materials and methods for fabricating the same

摘要

A high surface area capacitor comprising a double metal layer of an electrode metal and a barrier material deposited on hemispherical grain (HSG) silicon and a high dielectric constant (HDC) material deposited over the double metal layer. An upper cell plate electrode is deposited over the HDC material. The double metal layer preferably comprises one noble metal for the electrode metal and an oxidizable metal for the barrier material. The noble metal alone would normally allow oxygen to diffuse into and oxidize any adhesion layer and/or undesirably oxidize any silicon-containing material during the deposition of the HDC material. The barrier metal is used to form a conducting oxide layer or a conducting layer which stops the oxygen diffusion. The HSG polysilicon provides a surface roughness that boosts cell capacitance. The HDC material is also used to boost cell capacitance.