Physical vapor deposition of an amorphous silicon liner to eliminate resist poisoning

A method of forming a trench and via hole, comprising:

• providing a substrate;
• forming a conducting electrode in said substrate;
• forming a layer of dielectric etch stop or metal diffusion barrier on said substrate wherein said layer of dielectric etch stop or metal diffusion barrier covers said conducting electrode;
• forming a layer of dielectric on said layer of dielectric etch stop or metal diffusion barrier wherein said layer of dielectric has a top surface and a first plane, wherein said first plane is a first distance below said top surface of said layer of dielectric;
• etching a via hole having sidewalls in said in said layer of dielectric and said layer of dielectric etch stop or said metal diffusion barrier thereby exposing a part of said conducting electrode;
• depositing a layer of amorphous silicon on said layer of dielectric, said sidewalls of said via hole, and said exposed part of said conducting electrode;
• forming a layer of resist on said layer of amorphous silicon thereby filling said via hole with resist;
• patterning said layer of resist thereby forming a trench pattern in said layer of resist and leaving resist in that part of said via hole below said first plane, wherein said via hole lies within said trench pattern;
• etching a trench in that part of said layer of dielectric above said first plane using said patterned layer of resist as a mask by etching away that part of said amorphous silicon and that part of said dielectric not covered by said trench pattern and above said first plane;
• removing said patterned layer of resist and said resist in said via hole below said first plane;
• depositing a layer of barrier metal on said layer of dielectric, said sidewalls of said trench, and that part of said layer of amorphous silicon below said first plane, after removing said patterned layer of resist;
• depositing a layer of conducting material on said layer of barrier metal thereby filling said trench and said via hole with conducting material;
• and
• removing that part of said layer of conducting material, that part of said layer of barrier metal, and that part of said layer of amorphous silicon above said top surface of said layer of dielectric.