| 摘要 |
<p>PROBLEM TO BE SOLVED: To perform preprogramming without generating a high temperature electron group in a channel by forming a P-well in an n-type deep N-well and feeding electrons to a floating gate biasing the P-well forward. SOLUTION: A P-well 210 constituting a flash memory cell array are formed in an n-type deep N-well 220. Under a state where a drain 270 and a source 260 are biased with a voltage Vcc, the P-well 210 is biased forward from the n-type deep N-well 220. At that time, a floating gate 255 is biased positively with a voltage Vpp (8.5-9.0 V). Since the P-well 210, the n-type deep N-well 220, the drain 270 and the source 260 serve, respectively, as the base, emitter and collector to constitute a bipolar transistor, an electron is injected from the N-well 220 into the floating gate 255 through the P-well 210.</p> |
