Active solid-state devices (e.g. – transistors – solid-state diode – Test or calibration structure
Reexamination Certificate
2003-01-27
2003-12-30
Potter, Roy (Department: 2822)
Active solid-state devices (e.g., transistors, solid-state diode
Test or calibration structure
C257S737000
Reexamination Certificate
active
06670634
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to semiconductor manufacture and specifically to an improved interconnect for electrically engaging semiconductor components such as dice, packages, wafers, panels, boards, and electronic assemblies containing dice or packages.
BACKGROUND OF THE INVENTION
Different types of semiconductor components include terminal contacts which provide electrical connection points for applying electronic signals to the integrated circuits contained on the components. For example, bare dice and semiconductor wafers typically include bond pads which function as terminal contacts. Chip scale packages typically include solder balls, which function as terminal contacts. Electronic assemblies, such as circuit boards and field emission displays, can include pads, solder balls or pins which function as terminal contacts.
Typically, an interconnect must be provided for making electrical connections to the terminal contacts on the contacts. For example, semiconductor test systems include an interconnect that makes temporary electrical connections with the terminal contacts on the components. Depending on the system, the interconnect can be die sized, or wafer sized. U.S. Pat. No. 5,686,317 entitled “Method For Forming An Interconnect Having A Penetration Limited Contact Structure For Establishing A Temporary Electrical Connection With A Semiconductor Die”, describes a die level interconnect configured for use with a carrier. U.S. Pat. No. 5,869,974 entitled “Micromachined Probe Card Having Compliant Contact Members For Testing Semiconductor Wafers”, describes a wafer level interconnect configured for use with a wafer prober.
Interconnects are also used to provide permanent electrical connections to a semiconductor component for various electronic assemblies. For example, U.S. Pat. No. 5,578,526 entitled “Method For Forming A Multi Chip Module”, and U.S. Pat. No. 5,789,278 entitled “Method For Fabricating Chip Modules”, describe multi chip modules having interconnects which form permanent electrical connections to the terminal contacts on components.
One material that can be used to fabricate interconnects is silicon. Silicon can be used as a substrate material, and also to form contacts for the interconnect. With silicon, a coefficient of thermal expansion (CTE) of the interconnect matches the CTE of the component. In test systems, the matching CTEs minimize thermal stresses during test procedures, such as burn-in, which are conducted at elevated temperatures. In electronic assemblies, the matching CTEs minimize thermal stresses due to heat generated by the semiconductor component, or by the operating environment.
One aspect of silicon is that it is a semiconductor material, and does not have sufficient electrical conductivity to permit signal transmission. Accordingly, the silicon must be coated with electrically conductive materials to form contacts, conductive traces and bond pads for the interconnect. The conductive materials can include metals, such as copper and aluminum, or metal silicides, such as TiSi
2
.
Some of the conductive materials used in interconnects do not possess sufficient strength to resist deformation during fabrication or use of electronic assemblies. For example, in test systems, some conductive materials, such as metals, are prone to wear and oxidation with continued usage. Also, some conductive materials, such as metal silicides, do not possess a thermal conductivity which permits efficient heat dissipation from the component.
SUMMARY OF THE INVENTION
In accordance with the present invention, an improved interconnect for semiconductor components, and a method for fabricating the interconnect are provided. The interconnect comprises a substrate, and a pattern of interconnect contacts on the substrate configured to electrically engage component contacts on the components.
In an illustrative embodiment, the substrate comprises silicon, and the interconnect contacts comprise silicon projections, or alternately indentations in the substrate, at least partially covered with silicon carbide (SiC) layers. The interconnect also includes a pattern of conductors (conductive traces) in electrical communication with the silicon carbide layers, and a pattern of terminal contacts, such as bonding pads, in electrical communication with the silicon carbide layers. The conductors provide electrical paths for signal transmission to and from the interconnect contacts. The terminal contacts provide an electrical connections points for external circuitry, such as test circuitry to the interconnect.
As silicon carbide has a mechanical hardness similar to diamond, the silicon carbide layers provide a wear-resistant surface for the interconnect contacts. The wear resistant surface makes the interconnect particularly suitable to testing applications wherein the interconnect contacts are used to perform multiple test procedures on many different components. The silicon carbide layer also has a relatively high strength and a high maximum working temperature, such that the interconnect contacts can resist deformation at temperature.
In addition, as silicon carbide has a high thermal conductivity, the silicon carbide layers provide efficient heat transfer from the component contacts to the interconnect contacts, and better temperature control at the interface of the interconnect contacts with the component contacts. Further, the silicon carbide layers can be configured to substantially cover the area on the substrate between the interconnect contacts to provide a large surface area for dissipating heat generated by the component.
Although silicon carbide has a relatively low electrical conductivity, a sufficient electrical conductivity can be provided by doping a silicon carbide layer with selected dopants having either a P-type, or a N-type conductivity. Doping can be accomplished during CVD deposition of silicon carbide, or following deposition by implanting the dopants (e.g., ion implantation) and then annealing to activate the dopant. Electrical conductivity can also be provided by oxidation of the silicon carbide conductive layers using localized thermal heating. One method for performing the localized thermal heating is with a focused laser beam. Using a doping or oxidation process, the interconnect contacts can have an electrical conductivity similar to contacts covered with a metal.
Preferably, the conductors on the interconnect are fabricated from a highly conductive metal, such as aluminum or copper, to provide low resistance signal paths for the interconnect contacts. In addition, conductive vias and backside contacts can be formed on the substrate in electrical contact with the conductors, or directly with the silicon carbide conductive layers.
Alternately, rather than forming the conductors of a separate metal, a blanket deposited silicon carbide layer can be patterned to provide the silicon carbide conductive layers, as well as the conductors for the interconnect contacts. In this case a circuit side surface of the interconnect is substantially covered with silicon carbide, such that the interconnect possesses improved heat dissipation characteristics. As another alternative, a blanket deposited silicon carbide layer can be selectively doped to form the silicon carbide conductive layers, and a separate metallization process can be used to form conductors on the blanket deposited silicon carbide layer.
The interconnect can be configured for die level testing of discrete components, such as bare dice or chip scale packages, or alternately for wafer level testing of multiple components contained on a common substrate, such as a wafer, a panel, a circuit board, or an electronic assembly. In addition, the interconnect contacts can be configured to electrically engage either planar component contacts (e.g., bond pads, test pads, land pads), or bumped component contacts (e.g., solder balls, metal bumps, conductive polymer bumps). For engaging planar component contacts, the interconnect contacts can comprise etched members with projections fo
Akram Salman
Wood Alan G.
Gratton Stephen A.
Micro)n Technology, Inc.
Potter Roy
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