Method of making a variable resistance polysilicon conductor for an SRAM device

A method of manufacture of a semiconductor device on a semiconductor substrate including a SRAM cell with a resistor comprising

• formation of a gate oxide layer on said substrate,
• formation of a first polycrystalline silicon containing layer on said gate oxide layer, said first polycrystalline silicon containing layer having a thickness between about 2,000 .ANG. and about 5,000 .ANG.,
• patterning and etching said first polycrystalline silicon containing layer to form a control gate,
• forming a spacer layer of silicon dioxide over said device and etching said spacer layer to form spacers adjacent to said control gate and said etching etching away portions of said gate oxide layer and etching said substrate to form steps on either side of said control gate,
• formation of a dielectric layer over said substrate with said steps on either side of said control gate and said spacers said dielectric layer having a thickness between about 500 .ANG. and about 3,000 .ANG.,
• formation of a blanket of a second polycrystalline silicon containing layer extending over said dielectric layer including said steps, said second polycrystalline silicon containing layer having a thickness between about 300 .ANG. and about 1,500 .ANG.,
• ion implanting said second polycrystalline silicon containing layer in a blanket implant of a first dose of dopant to form a resistor including ion implanting resistive regions with higher resistivity in regions over said steps because of said steps on either side of said control gate,
• forming a mask over said device with contact openings over flat areas of said second polycrystalline silicon which overlie said substrate and doping dopant into said contact openings to form contacts below said contact openings in said flat areas on both sides of said control gate,
• forming a BPSG layer over said device and forming via openings in said BPSG layer over said contacts, and
• forming metal vias into said via openings.