Patent ID: 6242308
Filing Date: 2001-06-05
Classification: H01L

Abstract:
A method of forming a poly tip to improve the speed of a split-gate flash memory cell comprising the steps of:providing a silicon substrate having a plurality of active and field regions defined;forming a gate oxide layer over said substrate;forming a first polysilicon layer over said gate oxide layer;forming a top-CVD oxide layer over said first polysilicon layer;forming a photoresist mask over said top-CVD oxide layer to define a floating gate pattern for said memory cell;etching said top-CVD oxide layer, said first polysilicon layer and said gate oxide layer through said photoresist mask to form a floating gate structure;forming an interpoly oxide layer over said substrate including said floating gate structure having top-CVD oxidelayer, wherein a sharp poly tip profile is shaped into said first polysilicon layer of said floating gate;forming a second polysilicon layer over said interpoly oxide and patterning said second polysilicon layer to form control gate structure of said split-gate flash memory cell.