Method of forming multiple gate oxide thicknesses using high density plasma nitridation
First Claim
1. A method of forming a dielectric layer having at least two effective thicknesses, comprising the steps of:
- forming a masking layer over a structure, said masking layer covering a first area of said structure;
subjecting said structure with said masking layer to a high density plasma nitridation having a plasma density in the range of 1010 to 1012 cm-3 ;
removing said masking layer;
oxidizing said structure.
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Abstract
A method for forming integrated circuits having multiple gate oxide thicknesses. A high density plasma is used for selective plasma nitridation to reduce the effective gate dielectric thickness in selected areas only. In one embodiment, a pattern (12) is formed over a substrate (10) and a high density plasma nitridation is used to form a thin nitride or oxynitride layer (18) on the surface of the substrate (10) . The pattern (12) is removed and oxidation takes place. The nitride (or oxynitride) layer (18) retards oxidation (20b), whereas, in the areas (20a) where the nitride (or oxynitride) layer (18) is not present, oxidation is not retarded. In another embodiment, a thermal oxide is grown. A pattern is then placed that exposes areas where a thinner effective gate oxide is desired. The high density plasma nitridation is performed converting a portion of the gate oxide to nitride or oxynitride. The effective thickness of the combined gate dielectric is reduced.
121 Citations
15 Claims
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1. A method of forming a dielectric layer having at least two effective thicknesses, comprising the steps of:
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forming a masking layer over a structure, said masking layer covering a first area of said structure; subjecting said structure with said masking layer to a high density plasma nitridation having a plasma density in the range of 1010 to 1012 cm-3 ; removing said masking layer; oxidizing said structure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 12)
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8. A method of manufacturing a gate dielectric having at least two effective thicknesses, comprising the steps of:
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forming a dielectric layer over a structure; forming a masking layer over said dielectric, said masking layer exposing a portion of said dielectric layer; subjecting said exposed portion of said dielectric layer to a high density nitrogen-containing plasma having a plasma density in the range of 1010 to 1012 cm-3 ; removing said masking layer. - View Dependent Claims (9, 10, 11, 13, 14, 15)
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Specification