| 摘要 |
A process for forming a SAC opening, in a composite insulator layer, to expose an active device region in a semiconductor substrate, has been developed. The process features a RIE procedure, used to selectively define a first portion of the SAC opening, in a thick silicon oxide layer, with the RIE procedure terminating at the appearance of a polymer material, formed on the surface of an underlying, thin silicon nitride stop layer, at the conclusion of thick silicon oxide, dry etching procedure. A critical wet etch procedure, performed in a dilute hydrofluoric acid solution, is then employed to remove the polymer material, allowing selective removal of the thin silicon nitride stop layer to be accomplished, resulting in the desired SAC opening. A buffered hydrofluoric acid dip, is then used to remove a thin silicon oxide layer, located at the bottom of the SAC opening, followed by the formation of a self-aligned contact structure, in the SAC opening, overlying, and contacting, an active device region, in the semiconductor substrate, located at the bottom of the SAC opening.
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