The Boeing Company

Rockwell International Corporation

Boeing North American, Inc.

Honeywell G.m.b.h.

Drs Sensors & Targeting Systems, Inc.

Kenneth Maxwell Hays

Eugene Coleman Whitcomb

Eugene Timothy Fitzgibbons

Alan Glenn Bisignano

Christopher Alan Day

Jeffrey Jacob Brown

Bradley Leonard Halleck

A method and system of using a common set of coils to provide at least two of magnetic flux, heat and degaussing in a mobile platform are provided. In accordance with one embodiment, the method involves oscillation of current in the coils at a frequency higher than a defined pointing requirement to provide heat. In accordance with another aspect, the coil functions as a degausser by energizing the coil with an oscillating current that decreases in amplitude over time.

Multi-purpose electrical coil as a magnetic flux generator, heater or degauss coil

A wire-based heating element is provided having first and second portions twisted about each other such that magnetic flux emitted from one portion is substantially cancelled by magnetic flux emitted from the other portion. A bonding material that fixedly connects the two portions of the heating element and restricts their movement relative to each other to thereby maximize the cancellation of magnetic flux. A substrate-based heating element is also provided having traces on opposed sides of a substrate and overlying each other to cancel magnetic flux. Electrical connection pads are located on the same side of the substrate, and the second trace extends passed the first trace to connect to the second connection pad. A lead connected to the first connection pad overlies the portion of the second trace that extends to the second connection pad to thereby cancel magnetic flux emissions from this portion of the second trace.

Heating elements with reduced stray magnetic field emissions

The present invention provides a sealed-cavity miscrostructure and an associated method for manufacturing the microstructure. Specifically, the microstructure of the present invention includes first and second wafers that are positioned relative to one another so as to form a cavity between the wafers. The microstructure further includes a seal between the first and second wafers and surrounding the cavity to create a pressure seal for the cavity. This seal allows the cavity of the microstructure to be maintained at a predetermined pressure different from that of the atmosphere outside the cavity. Importantly, the microstructure of the present invention further includes a structrual bond between the first and second wafers that structurally intergrates the first and second wafers. The structural bond renders the microstructure more rugged such that the microstructure can withstand expansion, vibrational, and shock stresses experienced by the microstructure during subsequent manufacturing and use. In one additional embodiment, the microstructure is a microbolometer that includes in addition to the seal and structural bond, a radiation detector suspended in the cavity.

Method for fabricating a sealed-cavity microstructure

A method is provided for fabricating a MEMS structure from a silicon-on insulator (SOI) wafer that has been bonded to a support substrate, such as a glass substrate, in order to form silicon components that can be both precisely and repeatedly formed. The SOI wafer includes a handle wafer, an insulating layer disposed on the handle wafer and a silicon layer disposed on the insulating layer. At least one trench is etched through the silicon layer by reactive ion etching. By utilizing the reactive ion etching, the trenches can be precisely defined, such as to within a tolerance of 0.1 to 0.2 microns of a predetermined width. After bonding the support substrate to the silicon layer, the handle wafer is removed, such as by reactive ion etching. Thereafter, the insulating layer is selectively removed, again typically by reactive ion etching, to form the resulting MEMS structure that has a very precise and repeatable size and shape, such as to within a fraction of a micron. As such, a MEMS structure is also provided according to the present invention in which a plurality of silicon components that vary in size by no more than 0.2 microns are bonded to a support substrate, such as to form an array having a plurality of MEMS elements that have the same or substantially similar performance characteristics.

Precisely defined microelectromechanical structures and associated fabrication methods

A sealed-cavity microstructure and an associated method for manufacturing the microstructure. Specifically, the microstructure includes first and second wafers that are positioned relative to one another so as to form a cavity between the wafers. The microstructure further includes a seal between the first and second wafers and surrounding the cavity to create a pressure seal for the cavity. This seal allows the cavity of the microstructure to be maintained at a predetermined pressure different from that of the atmosphere outside the cavity. Importantly, the microstructure further includes a structural bond between the first and second wafers that structurally integrates the first and second wafers. The structural bond renders the microstructure more rugged such that the microstructure can withstand expansion, vibrational, and shock stresses experienced by the microstructure during subsequent manufacturing and use. In one additional embodiment, the microstructure is a microbolometer that includes in addition to the seal and structural bond, a radiation detector suspended in the cavity.

Sealed-cavity microstructure and microbolometer and associated fabrication methods

A process is provided for protecting, containing, and/or completing fragile microelectronic and microelectromechanical (MEM) structures on a low conductivity substrate during anodic wafer bonding of a covering wafer. The wafer includes raised areas that contact the substrate at selected bonding regions to support the wafer as a covering structure over the substrate. The covering wafer includes additional raised areas, such as pillars or posts, that contact selected electric circuit lines on the substrate to form temporary shorts through the wafer. During anodic bonding of the wafer to the substrate, the temporary shorts maintain the connected circuit lines and microstructures at nearly the same electric potential to prevent unwanted arcing and electrostatic forces that could damage the fragile structures. The pillars or posts can be formed at the same time as the raised bonding areas, but on unwanted and otherwise unused portions of the covering wafer. Anodic bonding produces only weak bonds between the wafer posts and the metallic conductor material of the circuit lines. After anodic bonding, the unwanted portions of the covering wafer can be removed to leave covering structures over the selected microstructures. Because of the weak bonds, removal of the unwanted portions of the wafer also removes the posts and eliminates the temporary shorts, with no additional processing needed to electrically separate the circuit lines on the substrate.

Method of anodic wafer bonding

Micromachining a microelectromechanical structure requires one or more heavily doped silicon layers. Intricately patterned structures are created in a heavily doped surface layer on a relatively undoped substrate. The substrate is subsequently dissolved in a selective etch. The doping prevents the patterned structures from dissolving. In this invention, a doped layer is grown epitaxially onto the first substrate rather than by diffusing a dopant into the substrate. This produces additional planarity, thickness control, and dopant profile control. The structure may then be placed into a larger device, such as an infrared sensor, an accelerometer, or an angular rate sensor.

Epitaxial layer for dissolved wafer micromachining process

A dissolved wafer process is modified by providing an etch control seal around the perimeter of an etch resistant microstructure, such as a micromechanical or microelectromechanical device, formed on a first substrate. The microstructure is defined and shaped by a surrounding trench in the first substrate. Selected areas of the microstructure and the first substrate are bonded to an etch resistant second substrate. The selected bonding areas may comprise raised areas of the first substrate, or raised areas of the second substrate corresponding to the selected bonding areas of the first substrate. A bonded area forming a ring extending around the perimeter of the microstructure and its defining trench forms an etch control seal. The first substrate of the bonded assembly is dissolved in a selective etch so that the etch resistant microstructure remains attached to the second substrate only at the bonded areas. The etch control seal reduces exposure of the microstructure to the etch by preventing the etch from contacting the microstructure until the etch leaks through the dissolving floor of the trench. This occurs only during the final stages of the wafer dissolution step, thus minimizing exposure of the microstructure to the damaging effects of the etch.

Etch control seal for dissolved wafer process

A dissolved wafer micromachining process is modified by providing an etch control seal around the perimeter of a heavily doped micromechanical structure formed on a substrate. The micromechanical structure is fabricated on a wafer using conventional methods including the formation of a trench that surrounds and defines the shape of the micromechanical structure in the substrate. The etch control seal comprises a portion of the substrate in the form of a raised ring extending around the perimeter of the micromechanical structure and its defining trench. Selected raised areas of the heavily doped micromechanical structure and the top of the raised etch control seal are bonded to a second substrate. A selective etch is then used to dissolve the first substrate so that the heavily doped micromechanical structure remains attached to the second substrate only at the bonded areas. The etch control seal reduces exposure of the micromechanical structure and bonded areas to the etch by preventing the etch from contacting the heavily doped structure until the etch leaks through the dissolving floor of the trench. This occurs only during the final stages of the substrate dissolution step, thus minimizing exposure of the micromechanical structure and bonded areas to the damaging effects of the etch. Use of an etch control seal increases design flexibility and improves micromechanical device yield and quality in a dissolved wafer fabrication process.

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Santa Ana, CA, United States of America

Kenneth Maxwell Hays