MEMS based tile assemblies and methods of fabrication

Details MEMS based tile assemblies and methods of fabrication MEMS based tile assemblies and methods of fabrication

1998-12-23

2001-02-06

Gaffin, Jeffrey (Department: 2841)

Electricity: electrical systems and devices

Housing or mounting assemblies with diverse electrical...

For electronic systems and devices

C361S760000, C361S762000, C361S783000, C257S773000, C257S774000, C257S778000, C174S256000, C174S260000, C174S261000, C174S262000, C174S266000, C228S180220

Reexamination Certificate

active

06185107

ABSTRACT:

BACKGROUND
The present invention generally relates to MEMS-based tile assemblies and methods of fabricating same, and more particularly, to MEMS-based tile assemblies wherein vertical alignment of and electrical interconnection of MEMS tiles is achieved using metallized elastic spheres and precision pyramid shaped pits etched on the surface of silicon substrates. Such MEMS-based tile assemblies may be used to produce large area, multi-tile (substrate), transmit/receive subsystems for use in large area micro-machined phased arrays.
Alignment registration between vertically stacked, conventional high thermal conductivity substrates such as aluminum nitride or beryllium oxide with vertical vias is limited by the accuracy and repeatability of via hole fabrication processes. Replacement of high thermal conductivity, ceramic based substrates with high resistivity, single crystal silicon will allow the fabrication of large area tile array systems, because precision, micron-accuracy, vertical vias can be fabricated with microelectronics based MEMS techniques. Furthermore, large size, precision, flat, silicon wafers and high volume manufacturing techniques are readily available. Replacement of the traditional face-up MMIC/aluminum nitride tile assembly with flip-chip/MEMS based technology will lead to a 3-to-5 fold in subarray cost reduction, enabling fabrication of large area sub-arrays containing on the order of 100 transceiver elements.
Aluminum nitride is the favored dielectric substrate material for high power active radar tile subarray because of its high thermal conductivity and its nontoxic property. However, precision circuitry with vertical via cannot be batch fabricated using conventional techniques because of shrinkage associated with firing the ceramic material. Consequently, via holes must be individually drilled. Maintaining precision aligrnment registration of the vertical via electrical connections from tile to tile is the cost driver of microwave subarray assemblies. Availability of large area, aluminum nitride substrate with built-in multilayer interconnect circuitry and precision vertical via limits the maximum number of transceiver element contained in a subarray.
Accordingly, it is an objective of the present invention to provide for MEMS based tile assemblies and methods of fabricating such tile assemblies. It is a further objective of the present invention to provide for MEMS based tile assemblies and methods of fabricating such tile assemblies that may be used to produce large area, multi-tile (substrate), transmit/receive subsystems for use in large area micro-machined phased arrays.
SUMMARY OF THE INVENTION
To meet the above and other objectives, the present invention provides for the vertical alignment of and electrical interconnection of MEMS tiles using metallized elastic spheres and precision pyramid shaped pits etched on surfaces of silicon substrates. An exemplary method of manufacturing MEMS based tile assemblies, comprises the following steps.
Lower and upper silicon substrates are provided that have metallization patterns formed on adjacent surfaces thereof. Flip chip MMIC devices are connected to the metallization patterns to produce lower and upper MEMS based tile assemblies. Vertical via hole electrical interconnects are formed that interconnect the tile assemblies. The interconnects are formed by providing one or more silicon frames, forming pyramid shaped etched pits in the silicon frames, forming via holes through the silicon frames interconnecting the pyramid shaped etched pits, and forming V-shaped, etched grooves in the silicon substrates. Inner surfaces of the pyramid shaped etched pits, V-shaped, etched grooves and via holes are metallized to form metallized vias. Conducting elastic spheres are disposed in the metallized vias to form the vertical electrical interconnects.
The present invention permits the fabrication of large area, multi-tile (substrate), phased array antenna transmit/receive subsystems, and the like. The present invention also provides for a method of fabricating large area, multi-tile structures, such as transmit/receive subsystems for use in large area micro-machined phased arrays. The large area, multi-tile transmit/receive subsystems comprise precision, vertical electrical (DC and RF) interconnects between tiles, and frames stacked on top of one another.
Metallized, back-to-back, inverted pyramid shaped, vertical vias are fabricated on high resistivity silicon tiles using micro-electronics mechanical system (MEMS) techniques. Slightly oversize, metallized, elastic spheres are squeezed between two inverted pyramid-shaped indentations to provide electrical conduction and accurate alignment between the vertical vias of two substrates. Such tile array architectures may be advantageously use in low-cost, advanced, airborne, active array radar systems, and the like.


REFERENCES:
patent: 5371654 (1994-12-01), Beaman et al.
patent: 5432681 (1995-07-01), Lindeerman
patent: 5510655 (1996-04-01), Tanielian
patent: 5544017 (1996-08-01), Beilin et al.
patent: 5574561 (1996-11-01), Boudreau et al.
patent: 6052287 (2000-04-01), Palmer et al.

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