Damascene T-gate using a relacs flow

A method for fabricating a T-gate structure comprising the steps of:

• providing a silicon layer having a gate oxide layer, a polysilicon layer over the gate oxide layer and an insulating layer over the polysilicon layer;
• forming a photoresist layer over the insulating layer;
• etching an opening in the photoresist layer exposing a portion of the insulating layer;
• etching partially the exposed portion of the insulating layer to extend the opening partially into the insulating layer, the opening in the insulating layer extending from a top surface of the insulating layer to a first depth;
• swelling the photoresist layer to reduce the size of the opening in the photoresist layer;
• etching the opening in the insulating layer from the first depth to a second depth wherein the opening is wider from the top surface of the insulating layer to the first depth than the opening is from the first depth to the second depth;
• filling the opening with a conductive material;
• and
• removing the insulating layer and the gate oxide and polysilicon layer not underlying the conductive material.

A method for fabricating a T-gate structure comprising the steps of:

• providing a silicon layer having a gate oxide layer, a polysilicon layer over the gate oxide layer and an insulating layer over the gate oxide layer;
• forming a photoresist layer over the insulating layer, the photoresist layer having a thickness within the range of about 1000 to 15000;
• etching an opening in the photoresist layer exposing a portion of the insulating layer, the etching being highly selective to the photoresist layer over the underlying insulating layer;
• etching the exposed portion of the insulating layer to extend the opening partially into the insulating layer, the opening in the insulating layer extending from a top surface of the insulating layer to a first depth, the etching being highly selective to the insulating layer over the photoresist layer;
• swelling the photoresist layer to reduce the size of the opening in the photoresist layer by wetting the photoresist layer with a solvent;
• etching the opening in the insulating layer from the first depth to the polysilicon layer wherein the opening is wider from the top surface of the insulating layer to the first depth than the opening is from the first depth to the polysilicon layer;
• filling the opening with a conductive material;
• and
• removing the insulating layer and the gate oxide and polysilicon layer not underlying the conductive material.