Structure of a mask rom device

Abstract

A mask ROM device is described. The mask ROM device includes a substrate, a gate, a double diffused source/drain region that comprises a first doped region and a second doped region, a channel region, a coding region, a dielectric layer and a word line. The gate is disposed on the substrate. The double diffused source/drain region is positioned beside the sides of the gate in the substrate, wherein the second doped region is located at the periphery of the first doped region in the substrate. The channel region is located between the double diffused source/drain region in the substrate. The coding region is disposed in the substrate at the intersection between the sides of the channel region and the double diffused source/drain region. The dielectric layer is disposed above the double diffused source/drain region, while the word line is disposed above the dielectric layer and the gate.