Abstract: A method for making a polycide-to-polysilicon capacitor, which has a reduced IPO thickness and low voltage coefficient, is described. A first layer of doped polysilicon is formed over a silicon substrate. A silicide layer is formed over the first layer of doped polysilicon. The first layer of doped polysilicon and the silicide layer are patterned to form a polycide bottom plate of the capacitor. An oxide layer is formed over the bottom plate. The oxide layer is densified. A second layer of doped polysilicon is formed over the oxide layer. The second layer of polysilicon is patterned to form a top plate of the capacitor. The oxide layer is removed except under the top plate of the capacitor, where it acts as a capacitor dielectric, and, finally, the bottom plate is annealed.

Abstract: A new method of simultaneously forming differential gate oxide for both 3 and 5 V transistors is described. A sacrificial silicon oxide layer is formed on the surface of a semiconductor substrate. Ions are implanted through the sacrificial silicon oxide layer into the planned 3 V transistor area of the semiconductor substrate wherein the implanted ions depress the oxidation rate of the semiconductor substrate. Alternatively, ions are implanted through the sacrificial silicon oxide layer into the planned 5 V transistor area of the semiconductor substrate wherein the implanted ions increase the oxidation rate of the semiconductor substrate. The sacrificial silicon oxide layer is removed and a layer of gate silicon oxide is grown on the surface of the semiconductor substrate.