Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package – With contact or lead
Reexamination Certificate
1999-06-03
2001-05-01
Lee, Eddie C. (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Housing or package
With contact or lead
C257S703000, C257S700000, C257S693000, C361S795000
Reexamination Certificate
active
06225692
ABSTRACT:
BACKGROUND OF THE PREFERRED EMBODIMENT(S)
1. Field of the Preferred Embodiment(s)
This invention generally relates to ceramic electronic packaging. Specifically, there is a multilayered ceramic package having a cavity that is bonded to a micromachined semiconductor device.
2. Description of the Related Art
Various devices and techniques are used for packaging of micromachined semiconductor devices. Typically, a micromachined semiconductor die is fabricated with wirebond pads and a sealing structure. A silicon lid has a cavity etched therein using a strong acid such as hydrofluoric. The micromachined semiconductor needs space within the package to allow the moving surfaces of the device to function properly. The silicon lid can be attached to the semiconductor die by an adhesive. The die and lid assembly is placed on a hybrid ceramic where the bond pads on the die are wirebonded to bond pads on the hybrid ceramic. The hybrid ceramic is then encapsulated within a hermetic package. This package has several problems. First, wire bonds are fragile and are subject to being torn away during mechanical assembly of the package. Second, the ceramic hybrid is expensive to produce. Third, if one of the parts in the hybrid circuit is defective, the whole circuit has to be thrown away. Previous attempts at packaging micromachined semiconductor devices have encountered difficulties in producing reliable electrical connections and hermetic seals that will survive environmental stress and be economically manufactured.
Typical micro-machined semiconductor structures contain metal elements on their surfaces which cannot be passivated through traditional glass passivation processes, however they still must be hermetically sealed. Current techniques include “attaching” a silicon lid, which has a cavity etched into its underside to clear the micro-machined structure, to the surface of the die exposing only the bonding pads. This configuration accomplishes the hermetic seal but will not allow for flip chip processes to be used as the die I/O pads cannot be brought to the surface.
Despite the advantages of the prior art designs, none have combined a highly reliable package with a design that is readily manufacturable at a low cost.
DESCRIPTION OF RELATED ART
Examples of patents related to the present invention follow; wherein each patent is herein incorporated by reference for related and supporting teachings:
U.S. Pat. No. 5,721,162, is an all silicon monolithic motion sensor with integrated conditioning circuit.
U.S. Pat. No. 5,369,057, is a method of making and sealing a semiconductor device having an air path therethrough.
U.S. Pat. No. 5,831,162, is a silicon micromachined motion sensor.
The foregoing patents reflects the state of the art of which the applicant is aware and are tendered with the view toward discharging applicants' acknowledged duty of candor in disclosing information that may be pertinent in the examination of this application. It is respectfully stipulated, however, that these patents do not teach or render obvious, singly or when considered in combination, applicants' claimed invention.
SUMMARY OF THE PREFERRED EMBODIMENT(S)
It is a feature of the invention to provide a hermetic multilayered ceramic package having a cavity that is bonded to a micromachined semiconductor device.
A further feature of the invention is to provide a semiconductor package for containing a micromachined semiconductor device, including a first substrate having a cavity located therein. The micromachined semiconductor device located adjacent the first substrate. A second substrate is located adjacent to the first substrate. A third substrate located adjacent the second substrate. Several vias extend through the first, second and third substrates. Several conductor lines are located on the first and second substrate and are electrically connected to the vias. An electrical connection mechanism is located between the vias and the micromachined semiconductor device, for electrically connecting the vias to the semiconductor device. A hermetic sealing mechanism is located between the micromachined semiconductor device and the first substrate for hermetically sealing the micromachined semiconductor device. The electrical connection mechanism has several bond pads that are located on the micromachined semiconductor and several solder joints that are connected between the bond pads and the vias.
A further feature of the invention is to provide a semiconductor package for containing micromachined semiconductor devices, including a low temperature co-fired ceramic assembly that has a cavity and a top and bottom surface. Several vias extend between the top and bottom surfaces and several solder spheres are located on the top surface and are electrically connected to the vias. A micromachined semiconductor device abuts the bottom surface and covers the cavity such that a movable portion of the micromachined semiconductor device is unconstrained to move within the cavity. An electrical connection mechanism is located between the vias and the micromachined semiconductor device, for electrically connecting the vias to the semiconductor device. A seal ring is located between the micromachined semiconductor device and the first substrate assembly for hermetically sealing the micromachined semiconductor device.
The invention resides not in any one of these features per se, but rather in the particular combination of all of them herein disclosed and claimed. Those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. Further, the abstract is neither intended to define the invention of the application, which is measured by the claims, neither is it intended to be limiting as to the scope of the invention in any way.
REFERENCES:
patent: 5369057 (1994-11-01), Lee
patent: 5585675 (1996-12-01), Knopf
patent: 5663596 (1997-09-01), Little
patent: 5721162 (1998-02-01), Schubert
patent: 5831162 (1998-11-01), Sparks
patent: 5907187 (1999-05-01), Koiwa et al.
patent: 6087203 (2000-07-01), Eng et al.
Borgman Mark W.
Bourgeois Mark P.
Clark Jhihan B
CTS Corporation
Lee Eddie C.
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