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Preferential Application Of Glass Bonding Material

IP.com Disclosure Number: IPCOM000050206D
Original Publication Date: 1982-Sep-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Yogi, T: AUTHOR

Abstract

In the bonding of three-dimensional microstructures, such as the microcircuit boards used in Josephson packaging, schott glass is often used as a bonding material. For example, silicon wafers can be bonded by a layer of schott glass located between the wafers. When the silicon wafers have cavities in them, it is desirable that the schott glass not be present in the cavities, but only on the surfaces which are to be in contact for bonding. A technique is provided for preferential application and removal of schott glass so that it will be present only on surfaces where bonding is intended.

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Preferential Application Of Glass Bonding Material

In the bonding of three-dimensional microstructures, such as the microcircuit boards used in Josephson packaging, schott glass is often used as a bonding material. For example, silicon wafers can be bonded by a layer of schott glass located between the wafers. When the silicon wafers have cavities in them, it is desirable that the schott glass not be present in the cavities, but only on the surfaces which are to be in contact for bonding. A technique is provided for preferential application and removal of schott glass so that it will be present only on surfaces where bonding is intended.

It has been found that the chemical etch rate of schott glass varies as a function of the substrate angle during vapor deposition of the schott glass. This is illustrated by Fig. 1, which plots the relative etch rate of schott glass in buffered HF versus the angle of deposition of the schott glass, the angle being measured from the normal to the substrate.

Figs. 2A-2D illustrate the process. A silicon wafer 10 is anisotropically etched to produce half of the desired microsocket cavities 12. The lower surface 14 is the surface which will be bonded to anothe silicon wafer. The cavity surfaces are of a truncated pyramidal shape, and make an angle of about 54.7 degrees to the wafer face.

In Fig. 2B, a layer of schott glass 16 is evaporated on the silicon wafer 10. The glass layer will bond to the flat surface 14, as well as on the sl...