| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor device which can increase its writing speed, and also to provide a method for manufacturing the device. SOLUTION: The method for manufacturing a semiconductor device having a nonvolatile memory transistor includes steps of (a) forming a first insulating layer 20 functioning as a gate insulating layer on a semiconductor substrate 10, (b) forming a floating gate 22 on the first insulating layer 20, (c) forming a second insulating layer 26 (26a) contacted at least partly with the floating gate 22 and functioning as a tunnel insulating layer, (d) re-forming the second insulating layer 26, that is, making thicker the second insulating layer 26 at a lower edge of the gate 22 than that before the step (d), (e) forming a control gate 28 on the second insulating film 26, and (f) forming an impurity diffusion layer as a source or drain region 14 or 16 in the substrate 10.
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