Patent ID: 7622764

Claim:
A semiconductor device comprising: a gate electrode on a trench in a semiconductor substrate; a second gate oxide layer in the trench between the gate electrode and the semiconductor substrate; sidewall floating gates on the lower part of the lateral faces of the gate electrode; a first gate oxide layer formed in the trench between the sidewall floating gates and a portion of the semiconductor substrate along the bottom of the trench; a second block oxide layer between the gate electrode and the sidewall floating gates; source and drain regions around a portion of the sidewall floating gates in the trench, wherein the source region is provided at one side of the trench and the drain region is provided along the same horizontal plane at the opposite side of the trench, and wherein the source region is elevated to the same level as the drain region; a channel formed below a bottom of the trench; spacers on a portion of the lateral faces of the sidewall floating gates above the trench and on the lateral faces of the gate electrode; and a first block oxide layer formed on lateral sides of the trench between the sidewall floating gates and the semiconductor substrate and extending along the lateral sides of the sidewall floating gates between the spacers and the sidewall floating gates.