- MODIFIED RECESSED LOCOS ISOLATION PROCESS FOR DEEP SUB-MICRON DEVICE PROCESSES

摘要

Through the silicon oxide of the substrate to etch a trench in the silicon substrate is coated with an oxide / nitride stack, and then the trench is partly filled with a field oxide layer is grown. The oxide encroachment into the active areas of the nitride layer is reduced due to the lower part of the field oxide growth. Oxide layer is to deposit a double oxide layer over substantially the upper surface of the oxide layer and the oxide / nitride stack of the field so as to form a planar topology by filling the remainder of the trench. The etching back the double oxide layer and then through the chemical mechanical polishing to a nitride layer, leaving the field isolation region. After removal of the oxide / nitride stack, thereby growing a gate oxide layer. Since the trench is already mostly filled with the field oxide layer and to fill the trench because of shallow depth of the trench is a very small amount of oxide is desired. As a result, the dishing is generated by the micro-etch-back step. Moreover, the field oxide layer to round the corner between the trench and the active region, there is a need for a thin oxide liner in the trench is removed.