Method for joining wafers at a low temperature and low stress
First Claim
1. A method of joining two dissimilar materials together, comprising:
- a) adding a reactive layer to a first material;
b) adding a hydrophilic layer to a second material;
c) joining said first and second materials together by placing said reactive layer in contact with said hydrophilic layer; and
d) pressing said joined materials tightly for a period of time sufficient for strong bonds to form between said materials.
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Abstract
The method of the present invention is used to join two dissimilar materials together, and particularly to transfer a film to a substrate when the difference in thermal expansion coefficients between the film and the substrate is very big. A hydrophilic surface is created on one material and an atmosphere reactive metal element is deposited on the surface of another material. When the materials are tightly contacted, with the reactive element pressed against the hydrophilic surface, the reactive metal element reacts with the moisture from the hydrophilic surface at room temperature. Strong bonds form during the reaction joining the two materials together. Because the procedure takes place at room temperature, extremely low stress is built in. The film joining is successful even with a big thermal expansion coefficient difference between the materials, such as exist between GaAs and silicon and between silicon and sapphire. The joined materials can sustain typical post-joining device process such as OMCVD growth, wet and dry etching, thin film deposition, and thermal annealing.
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Citations
32 Claims
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1. A method of joining two dissimilar materials together, comprising:
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a) adding a reactive layer to a first material;
b) adding a hydrophilic layer to a second material;
c) joining said first and second materials together by placing said reactive layer in contact with said hydrophilic layer; and
d) pressing said joined materials tightly for a period of time sufficient for strong bonds to form between said materials. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 26, 27, 28, 29, 30, 31)
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25. A method of joining two dissimilar materials together, comprising:
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a) adding an ohmic layer to a first material;
b) adding a reactive layer to said ohmic layer;
c) adding a hydrophilic layer to a second material;
d) joining said first and second materials together by placing said reactive layer in contact with said hydrophilic layer; and
e) pressing said joined materials tightly for a period of time sufficient for strong bonds to form between said materials. - View Dependent Claims (32)
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Specification