Barrier layer for ferroelectric capacitor integrated on silicon
AssigneeBell Communications Research, Inc.
InventorRamamoorthy Ramesh
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Abstract
A ferroelectric cell in which a ferroelectric stack of a perovskite ferroelectric sandwiched by cubic perovskite metal-oxide conductive electrodes are formed over a silicon body, such as a polysilicon plug penetrating a field oxide over a silicon transistor. According to the invention, an oxidation barrier is placed between the lower metal-oxide electrode and the polysilicon. The oxidation barrier may be: (1) a refractory metal sandwiched between two platinum layer which forms a refractory oxide in a platinum matrix; (2) an intermetallic barrier beneath a platinum electrode, e.g., of NiAl; or (3) a combination of Ru and SrRuO.sub.3 or similar materials. Thereby, the polysilicon plug is protected from oxidation.
Claims17
A multi-layer ferroelectric cell comprising:
- a) a substrate providing a silicon surface;
- b) an electrically-conductive barrier formed on said substrate surface for preventing the migration of oxygen to said surface, said barrier comprising a layer of a composition selected from the group consisting of
- 1) metallic compositions comprising a metallic matrix having metal oxide islands formed therein,
- 2) metallic compositions comprising an electrically-conductive intermetallic alloy comprising a first element selected from the group consisting of Ni, Co, Fe, and Mn and a second element selected from the group consisting of Al, Ga, Ti, and Cr, and
- 3) metallic compositions comprising a composite layer comprising a first metal having a conductive perovskite of said first metal formed thereon;
- c) a lower electrode formed on said barrier and comprising an electrically-conductive, chemically-templating perovskite layer;
- d) a ferroelectric layer formed on and templated to said chemically-templating layer;
- and
- e) an upper electrode formed on said ferroelectric layer.
A perovskite electronic heterostructure comprising:
- a) a silicon substrate with a conductive silicon surface;
- b) an electrically-conductive barrier formed on said substrate surface for preventing the migration of oxygen to said surface, said barrier comprising a layer of metallic composition selected from the group consisting of
- 1) compositions comprising a composite layer comprising platinum overlaid by a matrix comprising platinum having a metal oxide included therein,
- 2) compositions comprising an intermetallic alloy comprising a first element selected from the group consisting of Ni, Co, Fe, and Mn and a second element selected from the group consisting of Al, Ga, Ti, and Cr, and
- 3) compositions comprising a composite layer comprising Ru overlaid by a metallic oxide comprising Sr, Ru, and O;
- c) a lower electrode of a conductive cubic perovskite formed on said barrier;
- d) a substantially non-conductive layer of a perovskite formed on said lower electrode;
- and
- e) an upper electrode of said cubic perovskite formed on said non-conductive layer.
Dependencies are inferred from the claim text.