TW258832B - Process of flash EEPROM - Google Patents

Abstract

A process of flash EEPROM, that is applicable to the first-type semiconductor substrate to implement flash EEPROM, includes the following steps: (1) forming masking material along one first direction on the above semiconductor substrate to confine bit line of the above flash EEPROM; (2) with the above masking material as mask implementing oxidization to form field oxide on the above semiconductor substrate to make the above masking material across on the above field oxide; (3) with the above field oxide as mask implanting the second dopant into the above the first semiconductor substrate through the above masking material to form the above bit line; (4) with the above masking material as mask removing the above field oxide and leave field oxide under the above masking material to form trench reaching to the above semiconductor substrate; (5) removing the above masking material; (6) implementing oxidization, then forming tunnel oxide on semiconductor substrate in the above trench, simultaneously forming separating oxide on the above bit line; (7) forming floating gate on the above tunnel oxide and field oxide; (8) forming gate dielectric layer on the above floating gate; (9) forming control gate along the second direction with preset angle to the above first direction and on the above gate dielectric layer to become bit line of the above flash EEPROM.