Uniform critical dimension size pore for pcram application

A method of forming a memory cell, the method comprising:

• forming a plurality of insulating layers over a substrate;
• forming a bottom electrode within at least one of the insulating layers;
• defining a via through at least one of the insulating layers above the bottom electrode, the via and bottom electrode being separated by at least one intermediate insulating layer;
• forming a sacrificial spacer in the via above the intermediate insulating layer, the sacrificial spacer including a channel having a smaller diameter than a diameter of the via;
• defining a pore through the intermediate insulating layer below the sacrificial spacer and above the bottom electrode such that the channel continues through the intermediate insulating layer to the bottom electrode;
• removing the sacrificial spacer;
• depositing phase change material in the pore, the phase change material filling the entire pore;
• and
• forming an upper electrode above the phase change material.