Methods of manufacturing flash memory semiconductor devices

Abstract

A manufacturing method for fabricating flash memory semiconductor devices is disclosed. According to one example, the manufacturing method may include: forming a trench on a silicon substrate by forming a photoresist pattern on the silicon substrate and performing an etching process using the photoresist pattern; growing a tunneling oxide layer, after removing the photoresist pattern, on a portion of the silicon substrate corresponding to bottom surface of the trench using thermal oxidation process; filling up the trench, after growing the tunneling oxide, by depositing a floating gate poly silicon layer; forming a floating gate, after completion of trench filling, 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, which serves as a substantial electrode, 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; performing an oxidation process to the defined gate, which is remained after the etching, to perform oxidation of surrounding area of the defined gate, forming a sidewall by depositing a silicon nitride layer and etching the silicon nitride layer without a separate photolithography process, and performing an implanting process for forming a source and a drain.