摘要 |
The data retention characteristics of a nonvolatile memory circuit are improved. In a memory cell array on a main surface of a semiconductor substrate, a floating gate electrode for accumulating charges for information is arranged. The floating gate electrode is covered with a cap insulating film and a pattern of an insulating film 4a formed thereon. Further, over the entire main surface of the semiconductor substrate, an insulating film 2a is deposited so that it covers the pattern of the insulating film 4a and a gate electrode. The insulating film 2a is formed by a silicon nitride film formed by the plasma CVD method. The insulating film 4a is formed by a silicon nitride film formed by the low-pressure CVD method. By the provision of such an insulating film 4a, it is possible to suppress or prevent water or hydrogen ions from diffusing to the floating gate electrode, and therefore, the data retention characteristics of a flash memory can be improved.
|