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US 4,377,605 AGranted
Method for forming an insulating layer on a polycrystalline silicon layer of a semiconductor device using a two-step thermal oxidation technique
AssigneeFujitsu Limited
InventorTakashi Yamamoto
Life of this patent
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Abstract
When an insulating layer is formed on a polycrystalline silicon layer by thermally oxidizing the polycrystalline silicon layer, ambient gas to be used as an oxidizing gas comprises an oxygen gas and an inert gas. It is preferable that the ratio of oxygen partial pressure of the ambient gas is up to 0.35.
Claims9
A method for forming an insulating layer on a polycrystalline silicon layer in a semiconductor device, comprising the steps of:
- a. heating the polycrystalline silicon layer at a first temperature in an ambient gas, including an oxidizing gas comprising oxygen and an inert gas, for a first predetermined period of time to effect initial oxidation of the polycrystalline silicon layer;
- b. heating the polycrystalline silicon layer at a second temperature which is greater than the first temperature, in the ambient gas for a second predetermined period of time to further oxidize the polycrystalline silicon layer, so that the insulating layer is formed;
- and
- c. cooling the formed insulating layer to the first temperature in the inert gas.
1 more element
A method for forming an insulating layer on a polycrystalline silicon layer within a semiconductor device, comprising the steps of:
- a. heating the polycrystalline silicon layer at a temperature less than or equal to 950.degree. C. in a gas mixture, comprising an oxygen gas and an inert gas, for a first predetermined period of time to effect initial oxidation of the polycrystalline silicon layer;
- and
- b. heating the polycrystalline silicon layer at a temperature of from 1050.degree. C. to 1200.degree. C. in the gas mixture for a second predetermined period of time to further oxidize the polycrystalline silicon layer, so that an insulating layer of silicon dioxide having a breakdown voltage greater than or equal to 5 MV/cm is formed.
Dependencies are inferred from the claim text.