Semiconductor storage device and manufacturing method thereof

Abstract

In a non-volatile memory in which writing/erasing is performed by changing a total charge amount by injecting electrons and holes into a silicon nitride film serving as a charge accumulation layer, in order to realize a high efficiency of a hole injection from a gate electrode, the gate electrode of a memory cell comprises a laminated structure made of a plurality of polysilicon films with different impurity concentrations, for example, a two-layered structure comprising a p-type polysilicon film with a low impurity concentration and a p | -type polysilicon film with a high impurity concentration deposited thereon.

1 . A semiconductor storage device, comprising: a non-volatile memory having an insulating gate type field-effect transistor causing electric field effect to a surface of a semiconductor substrate from a gate electrode via a gate insulating film formed on a main surface of the semiconductor substrate;
 the gate insulating film including a first insulating film configuring a charge retention layer, a second insulating film formed between the first insulating film and the semiconductor substrate, and a third insulating film formed between the first insulating film and the gate electrode; and   the non-volatile memory using, as retention charges for information storage, holes injected into the charge retention layer from the gate electrode via the third insulating film and electrons injected into the charge retention layer from the semiconductor substrate via the second insulating film at a time of applying a positive voltage to the gate electrode,   wherein the gate electrode includes a first silicon layer formed to be in contact with the gate insulating film and a second silicon layer formed to be separated from the gate insulating film via the first silicon layer and doped with an impurity with a concentration higher than that of the first silicon layer.   
     
     
         2 - 33 . (canceled)