Semiconductor memory device having an alloy metal gate electrode and method of manufacturing the same

A method of fabricating a semiconductor memory device, comprising:

• sequentially forming a tunneling layer, a charge trapping layer and a blocking layer on a semiconductor substrate;
• forming an alloy gate electrode layer of a first metal and a second metal on the blocking layer, where the first metal is a noble metal and the second metal includes a transition or post-transition metal selected from at least one of aluminum (Al), titanium (Ti), gallium (Ga), indium (In), tin (Sb), thallium (Tl), bismuth (Bi) and lead (Pb);
• exposing at least one edge surface of the semiconductor substrate by etching at least one side surface of the tunneling layer, the charge trapping layer, the blocking layer and the alloy gate electrode layer;
• and
• forming a first impurity region and a second impurity region by doping the at least one exposed edge surface of the semiconductor substrate.