Patent ID: 8283717

Claim:
A non-volatile semiconductor storage device comprising: a semiconductor substrate; a semiconductor layer disposed on the semiconductor substrate; device isolation/insulation films disposed in the semiconductor layer along a first direction as its longitudinal direction; device formation regions configured to separate the semiconductor layer with the device isolation/insulation films along the first direction as its longitudinal direction; a memory string including a plurality of memory transistors connected in series and disposed on each of the device formation regions; a select gate transistor having one end connected to the memory string, the select gate transistor being disposed on each of the device formation regions; a contact diffusion region connected to the other end of the select gate transistor; and a contact contacting with the contact diffusion region; and the device isolation/insulation films each having a first height within a first area and a second height higher than the first height within a second area, at least the device isolation/insulation films adjacent to the contact diffusion region existing in the second area, the device isolation/insulation films adjacent to the memory transistors existing in the first area, the device isolation/insulation films being implanted with an impurity of a first conductivity type, the device formation regions each having a diffusion region of the first conductivity type, and an impurity concentration of the impurity of the first conductivity type in the device formation regions adjacent to the device isolation/insulation films in the second area being lower than an impurity concentration of a first impurity in the diffusion regions of the first conductivity type formed in the device formation regions adjacent to the device isolation/insulation films in the first area.