Defect free zero oxide encroachment process for semiconductor fabrication

A method for producing a semiconductor structure comprising the steps of:

• forming a first layer of material on the surface of a semiconductor substrate;
• forming a second layer of material over said first layer;
• selectively covering a region of said underlying substrate with a mask;
• removing said first and second layers not covered by said mask;
• removing a portion of said substrate not covered by said mask to form a mesa-like shape with a flat top in the same plane as said substrate, said mesa being surrounded by a trench region in said substrate;
• removing said mask;
• forming a third layer of material on the surface of said substrate not covered by said second layer;
• forming a fourth layer of material over said first, second and third layers;
• forming a fifth layer of material over said fourth layer;
• removing all of said fifth, fourth, and third layers which are essentially parallel to said substrate so that a coating of layers remains over the top and sides of said mesa, and extending into said trench region at least to a width substantially equal to the total thickness of said third, fourth, and fifth layers;
• removing the remainder of said fifth layer;
• forming a sixth layer of material on said substrate;
• removing the remainder of said second and fourth layers;
• forming a seventh layer of material over said first, third, and sixth layer to create a surface which is essentially flat and parallel to said substrate;
• and
• removing portions of said seventh, sixth, third, and first layers exposing the upper surface of said mesa and creating a flat surface in the same plane as said upper surface of said mesa.

A method for producing a semiconductor structure comprising the steps of:

• forming a first layer of material on the surface of a semiconductor substrate;
• forming a second layer of material over said first layer;
• selectively covering a region of said underlying substrate with a mask;
• removing said first and second layers not covered by said mask;
• removing a portion of said substrate not covered by said mask to form a mesa-like shape with a flat top in the same plane as said substrate, said mesa being surrounded by a trench region in said substrate;
• removing said mask;
• forming a third layer of material on the surface of said substrate not covered by said second layer;
• forming a fourth layer of material over said first, second and third layers;
• forming a fifth layer of material over said fourth layer;
• removing all of said fifth, fourth, and third layers which are essentially parallel to said substrate so that a coating of layers remains over the top and sides of said mesa, and extending into said trench region at least to a width substantially equal to the total thickness of said third, fourth, and fifth layers;
• forming a sixth layer of material on said substrate;
• and
• removing portions of said sixth, fifth, fourth, third, and first layers exposing the upper surface of said mesa and creating an essentially flat surface in the same plane as said top of said mesa.