Patent ID: 6946374

Claim:
A manufacturing method of a flash memory semiconductor device comprising: forming a trench in a silicon substrate by forming a photoresist pattern on the silicon substrate and performing an etching process using the photoresist pattern; forming a first sidewall spacer, after removing the photoresist pattern, on the sidewall of the trench; growing a tunneling oxide layer on a portion of the silicon substrate corresponding to bottom surface of the trench; filling up the trench by depositing a floating gate poly silicon layer; forming a floating gate by planarizing the floating gate poly silicon layer to make the height of the floating gate poly silicon layer the same as the silicon substrate; forming a dielectric layer on the floating gate and the silicon substrate; forming a control gate by depositing a control gate poly silicon layer on the dielectric layer; forming a gate by etching the control gate and the dielectric layer together using photolithography and etching processes for gate defining; and performing an oxidation process to the defined gate to perform oxidation of surrounding area of the defined gate, forming a second sidewall spacer on the sidewall of the defined gate, and performing an implanting process for forming a source and a drain.