Nonvolatile semiconductor memory device
US8022460B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 20, 2007 |
| Grant date | Sep 20, 2011 |
| Priority date | — |
| Expiry date | Jan 4, 2028 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10D30/683
Abstract
An object is to provide a nonvolatile semiconductor memory device which is superior in writing property and charge holding property. A semiconductor substrate in which a channel formation region is formed between a pair of impurity regions is provided, and a first insulating layer, a floating gate electrode, a second insulating layer, and a control gate electrode are provided over the semiconductor substrate. The floating gate electrode includes at least two layers. It is preferable that a band gap of a first floating gate electrode, which is in contact with the first insulating layer, be smaller than that of the semiconductor substrate. It is also preferable that a second floating gate electrode be formed of a metal material, an alloy material, or a metal compound material. This is because, by lowering the bottom energy level of a conduction band of the floating gate electrode than that of the channel formation region in the semiconductor substrate, a carrier injecting property and a charge holding property can be improved.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.