Structure and Method for Interconnection with Self-Alignment

A method of forming an integrated circuit structure, comprising:

• patterning a hard mask and a first metal layer disposed on a substrate, thereby forming first metal features capped by the hard mask;
• depositing a dielectric layer of a first dielectric material on the first metal features and in gaps among the first metal features;
• recessing evenly both the dielectric layer and the hard mask;
• removing the hard mask, thereby having portions of the dielectric layer extruded above the first metal features;
• forming an inter-layer dielectric (ILD) layer of a second dielectric material different from the first dielectric material;
• patterning the ILD layer to form openings that expose the first metal features;
• and
• forming second metal features in the openings of the ILD layer, wherein the second metal features are constrained to be self-aligned with the first metal features by the extruded portions of the dielectric layer and are landing on the first metal features.

A method of forming an integrated circuit structure, comprising:

• depositing a first metal layer on a semiconductor substrate;
• depositing a hard mask layer on the first metal layer;
• forming a first mandrel material layer on the hard mask layer;
• forming a spacer layer on sidewalls of the first mandrel material layer;
• forming a second mandrel material layer to fill in gaps defined by the spacer layer and the first mandrel material layer;
• performing an etching process to selectively remove the spacer layer, thereby forming first openings defined by the first and second mandrel material layers;
• transferring the first openings to the hard mask layer, thereby forming a patterned hard mask;
• patterning the first metal layer to form first metal features using the patterned hard mask as an etch mask;
• depositing a dielectric layer of a first dielectric material on the first metal features and in gaps among the first metal features;
• recessing evenly both the dielectric layer and the patterned hard mask;
• and
• removing the patterned hard mask, thereby having portions of the dielectric layer extruded above the first metal features.