Semiconductor device manufacturing: process – Chemical etching – Liquid phase etching
Reexamination Certificate
2000-04-11
2001-05-15
Dang, Trung (Department: 2823)
Semiconductor device manufacturing: process
Chemical etching
Liquid phase etching
C438S585000, C438S745000, C438S753000, C438S591000
Reexamination Certificate
active
06232241
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The invention relates to a method of reducing leakage current in the fabrication of integrated circuits, and more particularly, to a method of reducing leakage current of ultra-thin gate oxide by a novel pre-oxidation cleaning sequence in the manufacture of integrated circuits.
(2) Description of the Prior Art
For deep sub-micron CMOS technology, gate oxide has been scaled down aggressively toward the direct tunnelling current region. The thickness of the silicon dioxide layer is projected to be around 15 to 20 Angstroms for the coming 0.13 &mgr;m technology. For such ultra-thin gate oxide, leakage current will increase tremendously as compared to previous technologies. Accordingly, this will cause standby power consumption of devices to rise significantly, making products commercially unacceptable. The leakage current of ultra-thin gate oxides must be reduced.
U.S. Pat. No. 5,393,686 to Yeh et al discloses cleaning a gate oxide layer using ammonia and hydroxide fluid. U.S. Pat. No. 5,709,755 to Kuo et al teaches an APM rinse of the front and back sides of a wafer following CMP. U.S. Pat. No. 5,849,104 to Mohindra et al shows a multi-step cleaning process which can be used as a pre-gate oxide clean. U.S. Pat. No. 5,704,986 to Chen et al teaches a dry cleaning of a semiconductor substrate. U.S. Pat. No. 5,878,760 to Mohindra et al teaches a substrate cleaning process.
SUMMARY OF THE INVENTION
A principal object of the present invention is to provide an effective and very manufacturable method of pre-oxidation cleaning of a substrate surface.
A further object of the invention is to provide a method for pre-oxidation cleaning of a substrate surface that results in an initial chemical oxide layer on the substrate.
In accordance with the objects of this invention a new method of pre-oxidation cleaning of a substrate surface is achieved. The surface of a semiconductor substrate of a wafer is cleaned using a multiple step cleaning process wherein the final step of the cleaning process comprises cleaning with a solution of H
2
SO
4
and H
2
O
2
whereby a chemical oxide initial layer is formed on the surface of the wafer. Thereafter, the surface of the wafer is oxidized to form a thermal oxide layer wherein the chemical oxide layer and the thermal oxide layer together form a gate oxide layer in the fabrication of an integrated circuit.
REFERENCES:
patent: 5393686 (1995-02-01), Yeh et al.
patent: 5646074 (1997-07-01), Chen et al.
patent: 5681397 (1997-10-01), Li
patent: 5704986 (1998-01-01), Chen et al.
patent: 5709755 (1998-01-01), Kuo et al.
patent: 5849104 (1998-12-01), Mohindra et al.
patent: 5858106 (1999-01-01), Ohmi et al.
patent: 5878760 (1999-03-01), Mohindra et al.
patent: 5904574 (1999-05-01), Nishijima
Yu Chen-Hua
Yu Mo-Chiun
Ackerman Stephen B.
Dang Trung
Pike Rosemary L. S.
Saile George O.
Taiwan Semiconductor Manufacturing Company
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