METHOD FOR PRODUCING BIT LINES FOR UCP FLASH MEMORIES

摘要

The invention relates to a method for producing bit lines for UCP flash memories comprising a floating gate arrangement arranged on a substrate and an insulation arranged in the substrate under the floating gate arrangement. Initially, the floating gate is produced, after photolithography, by etching a separated polysilicon layer deposited on the total surface of the substrate. The aim of the invention is to provide a method wherein cell size can be reduced without significantly increasing production costs and wherein the bit lines survive the temperature budget of the sequence process without being damaged. As a result, the bit line (13), embodied as a buried bit line made of a temperature resistant material, is arranged in a silicon substrate (2) or in the insulation (3) of the active area below the floating gate (1) by automatic adjustment therewith (2). The already structured floating gate (1) is used as an etching mask for producing, by etching in insulation (3), a trench (6) which is subsequently filled with a low impedance material.