Appeal No. 2006-2832
Application No. 09/833,953
14. A method comprising steps of:
depositing a polycrystalline silicon layer on a chip, said polycrystalline
silicon layer including a gate region and a resistor region, said gate region being
situated over a well and said resistor region not being situated over said well,
wherein said field oxide region and said well are situated in a substrate;
forming a doping barrier above said polycrystalline silicon layer after said
step of depositing said polycrystalline silicon layer so as to prevent doping of said
resistor region of said polycrystalline silicon layer;
doping said polycrystalline silicon layer with a first dose of a first dopant
after said step of forming said doping barrier, wherein said dose of said first dopant
is a dosage greater than required to result in said layer over said gate region having
transistor gate electrical properties, wherein said first dopant has a first
conductivity type;
removing said doping barrier after said step of doping said polycrystalline
silicon layer with said first dose of said first dopant;
doping said polycrystalline silicon layer with a second dose of a second
dopant after said step of removing said doping barrier so as to form a high
resistivity resistor in said resistor region of said polycrystalline silicon, wherein
said second dopant has a second conductivity type, wherein said first dose of said
first dopant is higher than said second dose of said second dopant such that said
transistor gate electrical properties are unaffected by said second dose of said
second dopant;
forming a silicide blocking oxide layer over an inner portion of said
polycrystalline silicon layer over said field oxide region after said step of doping
said polycrystalline silicon layer with said second dose of said second dopant;
doping an outer portion of said resistor region of said polycrystalline silicon
layer with a third dopant after said step of forming said silicide blocking oxide
layer
4
Page: Previous 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Next
Last modified: September 9, 2013