Image analysis – Applications – Personnel identification
Reexamination Certificate
1997-07-24
2001-05-29
Jones, Deborah (Department: 1775)
Image analysis
Applications
Personnel identification
C382S312000, C361S283100, C428S332000, C428S450000, C428S472000, C428S698000, C428S701000, C428S702000, C257S415000, C257S417000
Reexamination Certificate
active
06240199
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to electronic devices including integrated circuit sensors, imagers and other sensing devices. More particularly, the invention relates to improved scratch and mechanical resistance for integrated circuit devices including integrated circuit sensors, other sensing devices and other electronic devices.
2. Description of the Related Art
Sensing devices including integrated circuit (IC) devices such as those used for capacitive sensors desire scratch resistant surfaces to protect the integrated circuit from repeated contact by external elements. For example, in capacitive sensors such as fingerprint sensors, the ridges and valleys on the finger tip making contact with the surface of the sensor (e.g., a CMOS chip) form variations in capacitance across a dielectric material in the chip that can be measured by an array of sensing elements arranged within the chip. The capacitance variations are then output by the sensor and used to form an image of the fingerprint.
Conventional sensors of this kind typically provide one or more layers including mechanically firm dielectric materials, e.g., silicon nitride (Si
3
N
4
), silicon dioxide (SiO
2
), and aluminum oxide (Al
2
O
3
). Also, the sensing elements and interconnect wires, which typically are formed on top of, within or below the dielectric region, typically are made of aluminum, copper, chromium, alloys of these metals, or multi-layers of these metals, because of their relatively low resistivities. For example, see the capacitive sensors disclosed in U.S. Pat. No. 4,353,056, issued to Tsikos, and U.S. Pat. No. 5,325,442, issued to Knapp.
However, sensors including integrated circuit sensors having such arrangements are still susceptible to scratches from the stress of repeated touch and from sharp, pointed external elements (e.g., fingernails and writing instruments). Such scratches and mechanical stress effects degrade the performance and/or functionality of the device and often lead to the complete failure of the device. Therefore, it is desirable to provide a sensor in general and an integrated circuit sensing device in particular having an improved scratch resistance and mechanical resistance over existing devices.
SUMMARY OF THE INVENTION
The invention is embodied in a sensor such as a capacitive sensor with improved scratch resistance. The sensor has a substrate and a layer of sensing elements formed thereon that are formed from materials having a greater mechanical firmness than conventional aluminum or other soft metal materials. Sensor interconnects also are made of such materials. The increased mechanical firmness of the sensing elements and interconnects improves the scratch and mechanical resistance thereof by reducing scratches, mechanical stress and cracks by reducing the deformation and consequently the bridge and/or gap effects of the sensing element material. Such effects plague conventional electronic devices, integrated circuits and sensors. Alternatively, the inventive sensor includes, e.g., a dielectric region operably coupled to the sensing elements and interconnects, thus forming a capacitive sensor or other electronic devices. The sensing elements and interconnects are formed beneath, within or on top of the dielectric region, and their improved mechanical firmness improves the scratch and mechanical resistance of the dielectric region or other material region formed thereon.
REFERENCES:
patent: 4353056 (1982-10-01), Tsikos
patent: 5262354 (1993-11-01), Cote
patent: 5325442 (1994-06-01), Knapp
patent: 5373181 (1994-12-01), Scheiter et al.
patent: 5426330 (1995-06-01), Joshi et al.
patent: 5446616 (1995-08-01), Warren
patent: 5828773 (1998-10-01), Setlak et al.
patent: 5844287 (1998-12-01), Hassan et al.
patent: 5862248 (1999-01-01), Salatino et al.
patent: 5907627 (1999-03-01), Borza
patent: 5910022 (1999-06-01), Weling
Manchanda Lalita
Martin, Jr. Edward Paul
Weber Gary Robert
Agere Systems Guardian Corp.
Harman John M.
Jones Deborah
Stein Stephen
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