Method of forming oxide film on an SOI layer and method of fabricating a bonded wafer
First Claim
1. A method of fabricating a bonded wafer, comprising the steps of:
- forming an oxide film on the surface of at least one of two mirror-polished silicon wafers;
superposing the two silicon wafers such that the mirror-polished surfaces come into close contact with each other;
heat-treating the wafers in order to join the wafers together firmly;
reducing the thickness of one of the wafers so as to yield a thin film;
polishing the surface of the thin film;
performing vapor-phase etching in order to make the thickness of the thin film uniform;
subjecting the surface of the bonded wafer to thermal oxidation to form an oxide film on the surface; and
removing the oxide film formed on the surface of the bonded wafer, wherein the thickness of the oxide film formed on the surface of the bonded wafer is made not greater than 50 nm.
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Accused Products
Abstract
In a method of fabricating a bonded wafer, an oxide film is first formed on the surface of at least one of two mirror-polished silicon wafers. The two silicon wafers are superposed such that the mirror-polished surfaces come into close contact with each other, and heat treatment is performed in order to join the wafers together firmly. Subsequently, the thickness of one of the wafers is reduced so as to yield a thin film, the surface of which is then polished and subjected to vapor-phase etching in order to make the thickness of the thin film uniform. Optionally, the vapor-phase-etched surface is then mirror-polished. The surface of the bonded wafer is oxidized, and the generated surface oxide film is then removed. In the method, the thickness of the oxide film formed on the surface of the bonded wafer is made not greater than 50 nm. The method reliably eliminates damage and crystal defects generated during etching in accordance with PACE method or subsequent mirror polishing, and thereby enables relatively simple and low cost manufacture of bonded wafers having a very thin SOI layer that has good thickness uniformity and excellent crystallinity.
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Citations
10 Claims
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1. A method of fabricating a bonded wafer, comprising the steps of:
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forming an oxide film on the surface of at least one of two mirror-polished silicon wafers;
superposing the two silicon wafers such that the mirror-polished surfaces come into close contact with each other;
heat-treating the wafers in order to join the wafers together firmly;
reducing the thickness of one of the wafers so as to yield a thin film;
polishing the surface of the thin film;
performing vapor-phase etching in order to make the thickness of the thin film uniform;
subjecting the surface of the bonded wafer to thermal oxidation to form an oxide film on the surface; and
removing the oxide film formed on the surface of the bonded wafer, wherein the thickness of the oxide film formed on the surface of the bonded wafer is made not greater than 50 nm. - View Dependent Claims (2, 3, 4, 5)
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6. A method of fabricating a bonded wafer, comprising the steps of:
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forming an oxide film on the surface of at least one of two mirror-polished silicon wafers;
superposing the two silicon wafers such that the mirror-polished surfaces come into close contact with each other;
heat-treating the wafers in order to join the wafers together firmly;
reducing the thickness of one of the wafers so as to yield a thin film;
polishing the surface of the thin film;
performing vapor-phase etching in order to make the thickness of the thin film uniform;
mirror-polishing the vapor-phase-etched surface;
subjecting the surface of the bonded wafer to thermal oxidation to form an oxide film on the surface; and
removing the oxide film formed on the surface of the bonded wafer, wherein the thickness of the oxide film formed on the surface of the bonded wafer is made not greater than 50 nm. - View Dependent Claims (7, 8, 9, 10)
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Specification