Method of making an antifuse cell with tungsten silicide electrode

Claim 1

A method for manufacturing an antifuse cell comprising: providing a silicon substrate; covering said silicon substrate with a layer of field oxide except where an active region for an antifuse cell is to be located; forming a layer of heavily doped N type silicon, in said silicon substrate, at said active region; thermally oxidizing said heavily doped N type silicon to form a first layer of silicon oxide on its surface; heating said silicon substrate, thereby driving N type dopant into said substrate and growing oxide on said heavily doped N type silicon layer; depositing a first layer of silicon nitride on said first layer of silicon oxide and forming an opening in said silicon nitride layer down to the level of the first layer of silicon oxide; removing said first layer of silicon oxide by etching it in buffered hydrofluoric acid; forming an ONO layer by: growing a second layer of silicon oxide on said heavily doped N type silicon layer, depositing a second layer of silicon nitride, and growing a third layer of silicon oxide on said second layer of silicon nitride; depositing a first layer of N type polysilicon on said third layer of silicon oxide to a thickness between 1,400 and 2,000 Angstroms; depositing a layer of tungsten silicide on said first layer of N type polysilicon to a thickness between 1,200 and 1,700 Angstroms; and forming a polysilicon cap on said layer of tungsten silicide to a thickness between 450 and 650 Angstroms.

Claim 2

A method for manufacturing an antifuse cell comprising: providing a silicon substrate; covering said silicon substrate with a layer of field oxide except where an active region for an antifuse cell is to be located; forming a layer of heavily doped N type silicon, in said silicon substrate, at said active region; thermally oxidizing said heavily doped N type silicon to form a first layer of silicon oxide on its surface; heating said silicon substrate, thereby driving N type dopant into said substrate and growing oxide on said heavily doped N type silicon layer; depositing a first layer of silicon nitride on said first layer of silicon oxide and forming an opening in said silicon nitride layer down to the level of the first layer of silicon oxide; removing said first layer of silicon oxide by etching it in buffered hydrofluoric acid; forming an ONO layer by: growing a second layer of silicon oxide on said heavily doped N type silicon layer, depositing a second layer of silicon nitride, and growing a third layer of silicon oxide on said second layer of silicon nitride; depositing a first layer of N type polysilicon on said third layer of silicon oxide to a thickness between 1,400 and 2,000 Angstroms; depositing a layer of tungsten silicide on said first layer of N type polysilicon to a thickness between 1,200 and 1,700 Angstroms; and forming a polysilicon cap on said layer of tungsten silicide to a thickness between 450 and 650 Angstroms.