D'Alessandro & Ritchie
Integrated two-terminal fuse-antifuse and fuse and integrated two-terminal fuse-antifuse structures incorporating an air gap
A two-terminal fuse-antifuse structure comprises a horizontal B-fuse portion and a vertical A-fuse portion disposed between two metallization layers of an integrated circuit device. The two-terminal fuse-antifuse can be programmed with a relatively high current applied across the two terminals to blow the B-fuse, or with a high voltage applied across the two terminals to program the A-fuse. Such a device, connected between two circuit nodes, initially does not provide an electrical connection between the two circuit nodes. It may then be programmed with a relatively high voltage to blow the A-fuse, causing it to conduct between the two circuit nodes. Then, upon application of a relatively high current between the two circuit nodes, the B-fuse will blow, making the device permanently non-conductive. An improvement permitting higher current programming of B-fuses either alone or as part of Ab-fuse structures, incorporates an air gap which provides a pocket of space either above, below or both above and below the B-fuse portion of the device. This air gap provides a place for material disrupted (melted or vaporized) by a fuse or Ab-fuse programming event to go, eliminates direct contact between the dielectric material and the fuse-portion of the device, and also thermally isolates the melted fuse material from the dielectric, thus reducing the physical stress within the dielectric itself associated with high current programming and avoiding undesired collateral damage normally associated with high current programming events. The creation of an air gap around the fuse neck is accomplished by the removal of a sacrificial layer of an oxidizable polymer material in a gaseous and/or plasma state through a small hole in the dielectric referred to as a sacrificial via opening or just "sacrificial via". After removal of the oxidizable polymer material through the sacrificial via, the sacrificial via is sealed with a passivation layer formed of a polymeric material to prevent damage to the underlying structure. The integration of the air gap and sacrificial via sealing into the current fuse process manufacturing requires the following additional processing steps: (1) Air gap definition; (2) Air gap evacuation with oxygen plasma; (3) the application of the sealing polymer; and (4) the curing of the sealing polymer.
Aptix Corporation
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inventional additional inventional inventional
Alan E. Michael David Chun-Mai Yu-Lin Ralph Scott
Comer La Fleur Liu Lee Whitten Graham