Precision high-value MOS capacitors

Claim 1

A method for forming a capacitor on an integrated circuit structure comprising : forming a first polycrystalline silicon layer; implanting n-conductivity type ions into the first polycrystalline silicon layer at an implant energy between approximately 80 and 100 keV: oxidizing the surface of the polycrystalline silicon layer to form an interpoly oxide layer, the oxidation being at a temperature which, for the implant dosage of the n-conductivity type ions, will make the interpoly oxide layer between approximately 770 and 2000 Angstroms thick; and forming a second polycrystalline silicon layer over said interpoly oxide layer.

Claim 2

A method for forming a capacitor on an integrated circuit structure comprising : forming a first polycrystalline silicon layer; implanting n-conductivity type ions into the first polycrystalline silicon layer at an implant energy between approximately 80 and 100 keV: oxidizing the surface of the polycrystalline silicon layer to form an interpoly oxide layer, the oxidation being at a temperature which, for the implant dosage of the n-conductivity type ions, will make the interpoly oxide layer between approximately 770 and 2000 Angstroms thick; and forming a second polycrystalline silicon layer over said interpoly oxide layer.

Claim 6

The method of any one of claims 2 to 4 wherein the n-conductivity type ions comprise one of phosphorus or arsenic.

Claim 7

The method of any one of claims 2 to 5 wherein the first polycrystalline silicon layer is formed at a temperature of approximately 600°C.

Claim 8

The method of any one of claims 2 to 6 wherein said oxidizing step comprises: inserting the integrated circuit structure into a diffusion furnace containing N 2 and 0 2 at standard pressure and a flow rate of approximately 300 cubic centimeters per minute at approximately 850°C; increasing the temperature inside the diffusion furnace from approximately 850°C to approximately 1000°C at a rate of approximately 8°C per minute; replacing the N 2 and 0 2 with 0 2 at standard pressure and a flow rate of approximately 3000 cubic centimeters per minute for approximately 20 minutes; replacing the O 2 with a mixture of approximately 3% HC1 and 97% O 2 for approximately 21 minutes; replacing the O 2 and HC1 with N 2 at standard pressure and a flow rate of approximately 5000 cubic centimeters per minute; increasing the temperature inside the diffusion furnace to approximately 1100°C over approximately a 20 minute period; replacing the N 2 with a mixture of approximately 95.4% N 2 , 3.4% 0 2 and 1.2% HC1 for approximately 60 minutes; replacing the mixture with N 2 at standard pressure and a flow rate of approximately 5000 cubic centimeters per minute: decreasing the temperature inside the diffusion furnace to approximately 850°C over a period of approximately 60 minutes; and removing the integrated circuit structure from the diffusion furnace.