| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an EEPROM cell in which threshold voltage distribution can be improved by increasing the effective channel length, and to provide a method of manufacturing the cell. SOLUTION: A nonvolatile memory element contains a gate insulating film which is formed on a semiconductor substrate and contains a tunnel insulating film, a memory transistor gate formed on the gate insulating film containing the tunnel insulating film, and a select transistor gate formed on the gate insulating film, separate from the memory transistor gate. The memory element also contains a first impurity region, which is formed in the substrate under the tunnel insulating film and has a fixed junction depth; a second impurity range which is formed in the substrate separately from the first impurity region and forms a source region in a state where its fixed portion is overlapped by the memory transistor gate; and a third impurity region which is formed in the substrate separately from the first impurity region, forms a drain region in a state where its fixed portion is overlapped by the select transistor gate, and has a fixed junction depth. The second impurity region is constituted of a low-concentration impurity region and a high-concentration impurity region and has a shallower junction depth than those of the firsts and third impurity regions.</p> |
