Patent ID: 8686488
Filing Date: 2014-04-01
Classification: H01L

Abstract:
1. A nonvolatile semiconductor memory device comprising: a semiconductor substrate; a gate insulating film formed on the semiconductor substrate; a floating gate electrode formed on the gate insulating film, made of polysilicon containing a p-type impurity as a group 13 element, and having a lower film and an upper film stacked on the lower film; an inter electrode insulating film formed on the floating gate electrode; and a control gate electrode formed on the inter electrode insulating film, wherein one of a concentration and an activation concentration of the p-type impurity in the upper film is higher than one of a concentration and an activation concentration of the p-type impurity in the lower film, the floating gate electrode has a peak of the one of the concentration and the activation concentration of the p-type impurity in an upper surface and a side surface of the upper film, and the one of the concentration and the activation concentration of the p-type impurity in the upper film is substantially constant in the upper surface and the side surface of the upper film.