Self-aligned contact formation for semiconductor devices

Details Self-aligned contact formation for semiconductor devices Self-aligned contact formation for semiconductor devices

1997-08-20

2000-06-27

Powell, William

Semiconductor device manufacturing: process

Chemical etching

Combined with the removal of material by nonchemical means

438737, 438743, H01L 2100

Patent

active

060806729

ABSTRACT:
In accordance with the present invention, there is provided a method for fabricating a contact on an integrated circuit, such as a DRAM. The method includes the following steps. A gate stack is formed on the integrated circuit. A spacer is formed on sidewalls of the gate stack. An insulating film is formed on the integrated circuit. The insulating film is planarized. Finally, a gate contact opening is formed through the planarized insulating film. In one embodiment, the gate contact opening is formed by removing the insulator, spacer and insulating film by etching. In this embodiment, the insulator, spacer and insulating film are etched at substantially similar rates. As a result, the integrated circuit is tolerant of mask misalignments, and does not over-etch field oxide or create silicon nitride slivers. In another embodiment, the planarizing step is performed with chemical mechanical planarization to form a substantially flat topography on the surface of the integrated circuit. Thus, the present invention does not require lithography equipment with a relatively large field of depth. In yet a third embodiment, the method may comprise additional steps, including forming additional dielectric on the integrated circuit. Then, gate and bitline contact openings are formed through the additional dielectric. Finally, gate and bitline contacts are formed in self-alignment to the gate stacks. This embodiment may be implemented by forming the gate and bitline contact openings with an etch that removes the additional dielectric, but does not substantially remove the spacer. As a result, the bitline contact cannot be inadvertently connected to a gate stack that functions as a wordline. This connection might disable the integrated circuit.

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