Method for making cusp-free anti-fuse structures

A method for making an anti-fuse structure, the method comprising the steps of:

• forming a conductive base layer having at least one substantially planar surface portion;
• forming an anti-fuse layer over at least said planar surface portion of said conductive base layer such that a lower surface portion of said anti-fuse layer that is in contact with said planar surface portion of said conductive base layer is also substantially planar;
• patterning said anti-fuse layer to form an anti-fuse island including said lower surface portion, such that said lower surface portion of said anti-fuse island contacts essentially only said substantially planar surface portion of said conductive base layer;
• forming an insulating layer over said anti-fuse island;
• forming a via hole through said insulating layer to said anti-fuse island;
• forming a conductive connection layer over said insulating layer and within said via hole;
• and
• patterning said conductive connection layer to form a conductive contact to said anti-fuse island through said via hole;
• whereby said anti-fuse island comprises a substantially cusp-free anti-fuse structure within said via hole.