In a semiconductor substrate having a surface including a first surface region at a first level, a second surface region at a second level lower than the first level, and a step side region linking the first surface region and the second surface region together, a channel region has a triple structure....http://www.google.de/patents/US6184553?utm_source=gb-gplus-sharePatent US6184553 - Nonvolatile semiconductor memory device and method for fabricating the same, and semiconductor integrated circuit device
