Active solid-state devices (e.g. – transistors – solid-state diode – Responsive to non-electrical signal – Temperature
Reexamination Certificate
1998-04-16
2001-05-22
Whitehead, Jr., Carl (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Responsive to non-electrical signal
Temperature
C257S468000, C257S470000, C257S712000, C257S713000, C257S720000, C257S762000, C257S766000, C257S767000, C257S684000, C257S796000, C257S706000, C257S707000
Reexamination Certificate
active
06236098
ABSTRACT:
RELATED APPLICATIONS
This application is related to copending U.S. Pat. application Ser. No. 09/060,147, entitled “IMPROVED THERMAL SENSING SYSTEM FOR INTEGRATED CIRCUIT AND METHOD” (Attorney's Docket TI-21400).
TECHNICAL FIELD OF THE INVENTION
This invention relates generally to the field of semiconductor devices, and more particularly to an improved heat spreader for an integrated circuit chip and to a method of forming the same.
BACKGROUND OF THE INVENTION
Packaged integrated circuit devices generally contain heat sinks or spreaders. The heat sink may be in the package and include a top layer of plated metal integral to the integrated circuit for efficient dissipation of thermal energy. In general, thermal energy is a function of power generated by an integrated circuit. Accordingly, dissipation of thermal energy is especially important in power integrated circuits, microprocessors, large digital signal processors, large area high component count integrated circuits, and the like.
To dissipate thermal energy an integrated circuit package may include a large heat sink in the form of a copper slug as an integral part of the metal lead frame to which the integrated circuit is mounted. The back of the integrated circuit may be mounted to the metal slug with either epoxy or solder. Thermal energy is transferred from the integrated circuit in the semiconductor material of the chip and then to the metal slug. A surface mounted heat sink and fan may also be used to dissipate thermal energy. Using this scheme, thermal energy is transferred from the semiconductor material up through metal and dielectric layers and ultimately through the plastic packaging to the surface mounted heat sink. A problem with these methods is that they generally require integrated circuits to operate at a relatively high temperature. Such temperatures can significantly degrade performance of the integrated circuits.
SUMMARY OF THE INVENTION
Accordingly, a need has arisen in the art for an improved heat spreader. The present invention provides a heat spreader for localized high temperature regions of an integrated circuit that substantially eliminates or reduces the disadvantages and problems associated with prior heat sinks or spreaders.
In accordance with the present invention, an integrated circuit chip may comprise an integrated circuit formed in a Semiconductor layer. A thermal contact may be formed at a high temperature region of the integrated circuit. A thick plated metal layer may be generally isolated from the integrated circuit. The thick plated metal layer may comprise a base and an exposed surface opposite the base. The base may be coupled to the thermal contact to conduct thermal energy from the high temperature region. The exposed surface may dissipate thermal energy received by the thick plated metal layer.
In accordance with another aspect of the present invention, the integrated circuit chip may comprise a semiconductor layer disposed on an insulation layer and further laterally isolated by dielectrics. In this aspect, the semiconductor and insulation layers may form an SOI system with the semiconductor layer thermally isolated from the bottom and sides by the dielectric layers. An integrated circuit may be formed in the semiconductor layer. A thick plated metal layer may be generally isolated from the semiconductor layer. The thick plated metal layer may comprise a base and an exposed surface opposite the base. In this embodiment, the base may be coupled to the semiconductor layer to receive thermal energy of the integrated circuit. The exposed surface may dissipate thermal energy received by the thick plated metal layer.
Important technical advantages of the present invention include providing a heat spreader capable of selective and localized heat extraction. In particular, low thermal impedance metal paths may extend from an exposed surface of a thick plated metal layer down to a semiconductor layer. Accordingly, heat generated by the integrated circuit may be efficiently transferred to the exposed sur ace and dissipated.
Another technical advantage of the present invention includes providing a heat spreader that can be used as an integral part of the integrated circuit package. In particular, the thick plated metal layer may be protectively capped and exposed from the package for increased thermal dissipation. Accordingly, operating temperatures of a packaged integrated circuit chip may be reduced and operating efficiency thereby increased.
Still another technical advantage of the present invention includes providing thermal pathways that may be used as active electrical leads. In particular, the thick plated metal layer may be connected to localized ground points to provide a ground plane above active lead circuitry. Additionally, the thick plated metal layer may be coupled to a thermal sensor circuit.
Other technical advantages will be readily apparent to one skilled in the art from the following figures, descriptions, and claims.
REFERENCES:
patent: 5468984 (1995-11-01), Elfand et al.
patent: 5691567 (1997-11-01), Lo et al.
patent: 5726481 (1998-03-01), Moody
08/711,138 FWC of 08/333,174, Multiple Transistor Integrated Circuit with Thick Copper Interconnect, Originally filed Nov. 2, 1994, pending.*
08/903,970 FWC of 07/850,601, Method for Ballasting and Busing Over Active Device Area Using a Multi-Level Conductor Process, originally filed Mar. 13, 1992, pending.*
08/864,386, Plated Copper and Plated Copper with Plated Nickel Cap Interconnect Metallization on a Silicon Integrated Circuit, filed May 28, 1997, pending.
Devore Joseph A.
Efland Taylor R.
Summerlin R. Travis
Brady III Wade James
Jr. Carl Whitehead
Telecky , Jr. Frederick J.
Texas Instruments Incorporated
Warren Matthew E.
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