Memory device and methods of fabricating the same

A method of fabricating a memory device, comprising:

• forming an active area and a shallow trench isolation (STI) region adjacent to the active area;
• forming a first word line nitride layer on the active area and the STI region;
• forming a word line mask layer on the first word line nitride layer;
• forming a plurality of word line trenches that extend through the word line mask layer into the active area and the STI region;
• forming a word line metal layer and a second word line nitride layer in the word line trenches to form a plurality of word lines, wherein the second word line nitride layer comprises a first portion above a top surface of the first word line nitride layer and a second portion between the first portion and the word line metal layer;
• removing the word line mask layer to form a plurality of trenches between the word lines;
• extending the trenches into the active area and the STI region;
• forming a bit line contact and a capacitor contact in the trenches;
• filling the trenches with a word line filling layer;
• forming a bit line on the bit line contact through the word line filling layer;
• and
• forming a contact plug on the capacitor contact.