Hermetic sealing of silicon
First Claim
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1. A method of forming a hermetic seal between a first silicon wafer and a second silicon wafer including the steps of:
- forming opposing troughs in each of said two silicon wafers;
forming an isolation layer suitable for forming a barrier between silicon and metal during heating;
forming a diffusion barrier suitable for limiting diffusion of gold;
forming a tub of polysilicon in the cavity lined by the diffusion barrier;
forming a gold strip on one of the polysilicon tubs;
positioning the two silicon wafers adjacent each other so that the gold strip on one polysilicon tub aligns with the polysilicon tub of the other wafer; and
heating the adjacent silicon wafers in a thermal gradient so as to form a silicon gold eutectic which migrates to the diffusion barrier of the silicon wafer which do not have gold film on the polysilicon tub.
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Abstract
A method of forming a hermetic seal between two silicon wafers includes forming opposing troughs in each of the two wafers. In each trough are formed an isolation layer, a diffusion barrier and a tub of polysilicon. A gold strip is put on one polysilicon tub and the two silicon wafers are brought together and heated in a thermal gradient oven. A silicon gold eutectic is formed which migrates to the diffusion barrier of the silicon wafer.
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Citations
11 Claims
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1. A method of forming a hermetic seal between a first silicon wafer and a second silicon wafer including the steps of:
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forming opposing troughs in each of said two silicon wafers; forming an isolation layer suitable for forming a barrier between silicon and metal during heating; forming a diffusion barrier suitable for limiting diffusion of gold; forming a tub of polysilicon in the cavity lined by the diffusion barrier; forming a gold strip on one of the polysilicon tubs; positioning the two silicon wafers adjacent each other so that the gold strip on one polysilicon tub aligns with the polysilicon tub of the other wafer; and heating the adjacent silicon wafers in a thermal gradient so as to form a silicon gold eutectic which migrates to the diffusion barrier of the silicon wafer which do not have gold film on the polysilicon tub. - View Dependent Claims (2, 3, 4, 5, 6)
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- 7. A method of joining two silicon wafers including the step of migrating a gold silicon eutectic across the interface between the two wafers to form a bond.
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