In a flash memory EEPROM, a memory cell MC is formed in a P-type semiconductor substrate. A peripheral transistor TR is formed in an N-type well. Another peripheral transistor TR is formed in a P-type well. The P-type well is by turn formed an N-type well and electrically insulated from the substrate....http://www.google.com/patents/US6529414?utm_source=gb-gplus-sharePatent US6529414 - Nonvolatile semiconductor memory device including a circuit for providing a boosted potential
