SONOS MEMORY DEVICE HAVING MEMORY NODE LAYER WITH NANO-CRYSTALLINE LAYER

摘要

PURPOSE: An SONOS(Silicon-Oxide-Nitride-Oxide-Silicon) memory device is provided to improve substantially the degree of integration within the same design rules by writing more data in the same than a conventional unit cell using memory node layers with a nano-crystalline layer. CONSTITUTION: A memory device includes a memory type transistor with a gate(48) of an SONOS structure. The gate is formed on a semiconductor substrate(40). The gate is composed of a tunneling oxide layer(48a), a plurality of node layers(48c,48d,48f) on the tunneling oxide layer, and a gate electrode(48g) on the uppermost node layer. A crystalline layer(48b,48e) is selectively formed in the plurality of node layers. The crystalline layer is made of a plurality of nano-sized crystals for trapping the charges passed through the tunneling oxide layer, wherein the nano-sized crystals are spaced apart from each other.