Method of manufacturing semiconductor memory device

A method of manufacturing a semiconductor memory device comprising:

• providing a substrate;
• forming a plurality of gate structures and a plurality of dielectric caps, wherein the gate structures are formed on the substrate and each gate structure comprise a first gate and a first gate dielectric layer, the first gate dielectric layer disposed between the first gate and the substrate, and the dielectric caps are formed atop the gate structures respectively;
• forming a first dielectric layer covering the dielectric caps and a plurality of sidewalls of the gate structures;
• forming a second dielectric layer covering the first dielectric layer, wherein materials of both the first dielectric layer and the second dielectric layer are different;
• partially removing the second dielectric layer to reveal a plurality of top parts of the first dielectric layer and to form a plurality of first spacing films;
• forming a plurality of second gates on the substrate, wherein the second gates covering and contacting the first dielectric layer and a top edge of the first spacing film;
• removing the dielectric caps to reveal the first gates;
• and
• forming a plurality of drains and a plurality of sources in the substrate.