Method of manufacturing self-aligned contact hole

Abstract

A method of manufacturing a self-aligned contact hole. Gate patterns are formed on a semiconductor substrate with an interposing gate insulating layer, and a first insulating pattern for filling a gap between the gate patterns is provided. A portion of the first insulating pattern is etched by self-aligned contact etching to form a first contact hole. A spacer is formed on a side wall of the first contact hole, and a first plug layer of conductive silicon fills the first contact hole. Partial etchback is performed to etch the first plug and gate pattern to a predetermined thickness, such that the top portion of the spacer projects higher than the surface of the first plug and gate pattern. A second plug layer of conductive silicon fills a gap between the projected spacers, and a thickness of the second plug layer at a portion filling the gap between the spacers is greater than that at a portion deposited on the gate pattern. The second plug layer is then etched back to a uniform thickness to expose the sides of the spacer and the first insulating pattern adjacent to the gate pattern, thereby forming a second plug connected to the first plug. A capping protective layer covers and protects the gate pattern while exposing the top surface of the second plug. A second insulating pattern is formed on the capping protective pattern, which has a second contact hole exposing at least the top surface of the second plug.