Devices having improved capacitance and methods of their fabrication

A method for forming a dielectric layer, comprising:

• forming a metal layer of a first material overlying electrically isolated portions of a first conductive layer of a second material formed upon a starting substrate;
• contacting the metal layer with an electrolytic solution;
• applying a potential across the electrolytic solution and the metal layer, thereby oxidizing at least a portion of the metal layer to form an oxidized layer that forms a portion of the dielectric layer, with non-oxidized portions of the metal layer and the electrically isolated portions of the first conductive layer forming first capacitor plates;
• monitoring a current in the electrolytic solution;
• adjusting the potential across the electrolytic solution to maintain a desired current in the electrolytic solution;
• planarizing the oxidized layer;
• and forming a second capacitor plate overlying the planarized oxidized layer.

A method of forming a capacitor dielectric on a semiconductor substrate assembly, comprising:

• providing said semiconductor substrate assembly;
• forming a metal capacitor plate on said substrate assembly;
• forming a metal layer overlying the semiconductor substrate assembly;
• applying a potential across the metal layer;
• oxidizing a portion of said metal layer to form an oxidized layer that constitutes at least a portion of the capacitor dielectric;
• mechanically planarizing the oxidized layer;
• and
• forming a second conductive layer to serve as a second capacitor plate over the planarized oxidized layer.

A method for forming a dielectric layer, comprising:

• forming a plurality of field oxide regions, a plurality of wordlines, and a first conductive layer overlying a starting substrate;
• selectively removing portions of the first conductive layer to form first capacitor plates;
• forming a metal layer overlying the first conductive layer;
• contacting the metal layer with an electrolytic solution;
• applying a potential across the electrolytic solution and the metal layer, thereby oxidizing at least a portion of the metal layer to form an oxidized layer that forms a portion of the dielectric layer, with non-oxidized portions of the metal layer forming portions of the first capacitor plates;
• monitoring a current in the electrolytic solution;
• adjusting the potential across the electrolytic solution to maintain a desired current in the electrolytic solution;
• and
• forming a second capacitor plate overlying the oxidized layer.

A method for forming a capacitor dielectric on a semiconductor substrate assembly, comprising:

• providing said semiconductor substrate assembly;
• forming a metal capacitor plate of a first material on the substrate assembly;
• forming a metal layer of a second material overlying the semiconductor substrate assembly;
• applying a potential across the metal layer;
• and
• oxidizing a portion of said metal layer to form at least a portion of the capacitor dielectric, wherein the second material is titanium.

A method for forming capacitors on a semiconductor substrate assembly, comprising:

• providing said semiconductor substrate assembly;
• forming a conductive layer atop the semiconductor substrate assembly;
• selectively removing portions of the conductive layer to form a plurality of first metal capacitor plates;
• forming a metal layer overlying the semiconductor substrate assembly to cover the first metal capacitor plates;
• applying a potential across the metal layer;
• oxidizing a portion of said metal layer to form a capacitor dielectric for each capacitor;
• and
• forming a second metal capacitor plate over each capacitor dielectric,
• wherein the metal layer is titanium.

A method for forming a capacitor dielectric, comprising:

• providing a semiconductor substrate assembly;
• forming a metal capacitor plate on said substrate assembly;
• forming a metal layer overlying the semiconductor substrate assembly;
• contacting the metal layer with an electrolytic solution;
• applying a potential across the metal layer and the electrolytic solution;
• and
• oxidizing a portion of said metal layer to form an oxide layer to form at least a portion of the capacitor dielectric, wherein the metal capacitor plate comprises polysilicon and the metal layer comprises titanium.