METHODS OF FORMING A PRAM HAVING A PHASE-CHANGE LAYER PATTERN CONFINED IN A NODE ISOLATING LAYER PATTERN

摘要

Methods of forming a phase-change random access memory (PRAM) include forming a lower electrode layer and a node insulating layer on an active region of a semiconductor substrate. A photoresist pattern is formed on the node insulating layer that includes an opening therein. A polymer layer is formed on the photoresist pattern and the node insulating layer. The polymer layer is etched using the photoresist pattern as an etching mask to expose the node insulating layer while leaving a portion of the polymer layer after etching on a top surface of the exposed node insulating layer and on a sidewall of the opening of the photoresist pattern. The node insulating layer is etched using the photoresist pattern and the polymer layer as an etching mask to form a confined contact hole extending through the node insulating layer to contact the lower electrode layer while forming a polymer layer on a sidewall of the confined contact hole as a byproduct of etching the node insulating layer. The photoresist pattern, the portion of the polymer layer and the polymer layer on the sidewall of the confined contact hole are removed from the semiconductor substrate and a phase-change layer is formed on the node insulating layer to substantially fill the confined contact hole.