Method of forming first level of metallization in dram chips

Abstract

There is disclosed a method of forming contacts and metal lands onto a semiconductor structure at the first level of metallization (M ). The initial structure is a silicon substrate having diffusion regions formed therein and a plurality of gate conductor stacks formed thereon. The structure is passivated by an insulating layer. Contact holes of a first type are etched in the insulating layer to expose some diffusion regions, then filled with doped polysilicon to form conductive studs substantially coplanar with the insulating layer surface. A first mask (M ) is formed at the surface of the structure to expose M land recess locations including above said studs. The masked structure is anisotropically dry etched to create M land recesses. Next, the M mask is removed. A second mask (CS) is formed at the surface of the structure to expose desired contact hole locations of a second type. The masked structure is again anisotropically dry etched to expose the diffusion regions and the top of gate conductor stacks. The CS mask is removed. Finally, said M land recesses and contact holes are filled with a metal, so that the metal and the insulating material top surface are substantially coplanar.