gt crystallographic orientation is used thick field oxide regions 2 fox are formed for isolation purposes the fox regions are formed by patterning a composite insulator oxidation mask composed of an overlying silicon nitride layer and an underlying silicon dioxide layer patterning is accomplished via conventional photolithographic and reactive ion etching rie procedures after photoresist removal performed via plasma oxygen ashing followed by careful wet cleans a thick fox insulator is grown in the silicon regions not covered with the composite insulator oxidation mask the fox insulator is obtained via thermal oxidation in an oxygen steam ambient at a temperature between about 850 u00b0 to 1050 u00b0 c grown to a thickness between about 4000 to 6000 angstroms after removal of the insulator composite oxidation mask using hot phosphoric acid for the silicon nitride layer and a buffered hydrofluoric acid solution for the underlying silicon dioxide layer a thin silicon dioxide gate insulator 3 is grown in an oxygen steam ambient at a temperature between about 800 u00b0 to 1000 u00b0 c to a thickness between about 50 to 300 angstroms a polysilicon layer is next deposited using low pressure chemical vapor deposition lpcvd processing at a temperature between about 500 u00b0 to 700 u00b0 c to a thickness between about 1500 to 4000 angstroms the polysilicon can be grown using insitu doping techniques via the addition of either phosphine or arsine to a silane ambient the polysilicon can also be deposited intrinsically and doped via ion implantation of either phosphorous or arsenic at an energy between about 50 to 100 kev at a dose between about 1e15 to 1e16 atoms cm 2 conventional photolithographic and rie procedures using cl 2 as an etchant are used to create polysilicon gate structure 4 shown schematically in fig1 after photoresist removal via.