Encapsulated metal structures for semiconductor devices and MIM capacitors including the same

A method of fabricating an encapsulated metal structure in a feature formed in a substrate having a top surface, the feature having sidewalls and a bottom, the method comprising the steps of:

• depositing a first barrier layer on the top surface of the substrate and on the sidewalls and bottom of the feature;
• filling the feature with metal;
• forming a recess in the metal, so that a top surface of the metal is lower than the top surface of the substrate;
• depositing a second barrier layer on the top surface of the metal;
• and
• planarizing the first barrier layer and the second barrier layer so that the top surface of the substrate is exposed and the metal is encapsulated by the first barrier layer and the second barrier layer.

A method of fabricating an encapsulated metal structure in a feature formed in a substrate having a top surface, the feature having sidewalls and a bottom, the method comprising the steps of:

• depositing a first barrier layer on the top surface of the substrate and on the sidewalls and bottom of the feature;
• filling the feature with metal;
• forming a first recess in the metal, so that a top surface of the metal is lower than the top surface of the substrate;
• depositing a second barrier layer on the top surface of the metal;
• and
• planarizing the first barrier layer and the second barrier layer so that the top surface of the substrate is exposed, a remaining portion of the second barrier layer is on the top surface of the metal and a portion of the top surface of the metal is exposed;
• forming a second recess in the metal at the exposed portion thereof;
• depositing a third barrier layer on the top surface of the metal and on the remaining portion of the second barrier layer, thereby filling the second recess in the metal;
• and
• planarizing the third barrier layer so that the top surface of the substrate is exposed and the metal is encapsulated by the first barrier layer, the second barrier layer and the third barrier layer.

A method of fabricating a metal-insulator-metal (MIM) capacitor, the method comprising the steps of:

• providing a first substrate layer with a feature formed therein, the first substrate layer having a top surface, the feature having sidewalls and a bottom;
• forming an encapsulated metal structure in the feature, where the sidewalls and bottom of the feature are covered by a first barrier layer and the feature is filled with metal covered by an additional barrier layer in contact with the first barrier layer;
• depositing a second substrate layer on the top surface of the first substrate layer and overlying the encapsulated metal structure;
• forming an opening in the second substrate layer to expose the encapsulated metal structure;
• depositing a dielectric layer on the second substrate layer, covering sidewalls of the opening and the exposed encapsulated metal structure at a bottom of the opening;
• depositing an additional layer to cover the dielectric layer on the sidewalls and on the bottom of the opening and to fill the opening;
• and
• planarizing the dielectric layer and the additional layer.

An encapsulated metal structure formed in a feature of a substrate, the substrate having a top surface, the feature having sidewalls and a bottom, the structure comprising:

• a first barrier layer covering the sidewalls and bottom of the feature;
• metal filling the feature and having a recess formed therein, so that a top surface of the metal is lower than the top surface of the substrate;
• and
• an additional barrier layer covering the top surface of the metal and contacting the first barrier layer so as to encapsulate the metal, the additional barrier layer being planarized so that the top surface of the substrate is exposed.

A metal-insulator-metal (MIM) capacitor structure, comprising:

• a first substrate layer with a feature formed therein, the first substrate layer having a top surface, the feature having sidewalls and a bottom;
• an encapsulated metal structure in the feature, where the sidewalls and bottom of the feature are covered by a first barrier layer and the feature is filled with metal covered by an additional barrier layer in contact with the first barrier layer, to form a lower plate of the capacitor structure;
• a second substrate layer on the top surface of the first substrate layer, the second substrate layer having an opening formed therein overlying the encapsulated metal structure;
• a dielectric layer covering sidewalls of the opening and a portion of the encapsulated metal structure at a bottom of the opening;
• and
• an additional layer covering the dielectric layer on the sidewalls and on the bottom of the opening and filling the opening, to form an upper plate of the capacitor structure,
• wherein the dielectric layer and the additional layer are planarized so that the top surface of the second substrate layer is exposed.