Patent Application
20060109120
During the manufacturing process for integrated circuits, many copies of a circuit are typically fabricated on a wafer, which is then separated into individual dies, and each die is packaged to form an individual integrated circuit. Any automated tracking that is done of the wafer, individual dies, or individual integrated circuits, is typically done by either placing the object in a container that is then tracked, or by applying a bar code label to the object that can then be read with a bar code reader. However, bar codes labels are rather large compared to the size of a die or integrated circuit, and may be impractical for this purpose, while the attachment of anything to a wafer before processing might introduce unacceptable contamination and also be otherwise impractical. In addition, bar code readers require line-of-sight proximity to the bar code label, a fact that may require special handling of the objects to be read.
Passive radio frequency identification (RFID) technology can also be used to identify individual objects and does not require line of sight proximity to the tags for operation. However, RFID tags are typically manufactured and sold as discrete devices with a circuit and an antenna, and each such discrete device is later attached to whatever object is to be identified by an RFID reader. Such attachment is not feasible during much of the integrated circuit fabrication process.
The invention may be understood by referring to the following description and accompanying drawings that are used to illustrate embodiments of the invention. In the drawings:
In the following description, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known circuits, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.
References to “one embodiment”, “an embodiment”, “example embodiment”, “various embodiments”, etc., indicate that the embodiment(s) of the invention so described may include a particular feature, structure, or characteristic, but not every embodiment necessarily includes the particular feature, structure, or characteristic. Further, the different embodiments described my have some, all, or none of the features described for other embodiments.
In the following description and claims, the terms “coupled” and “connected,” along with their derivatives, may be used. It should be understood that these terms are not intended as synonyms for each other. Rather, in particular embodiments, “connected” may be used to indicate that two or more elements are in direct physical or electrical contact with each other. “Coupled” may mean that two or more elements co-operate or interact with each other, but they may or may not be in direct physical or electrical contact.
The term “processor” may refer to any device or portion of a device that processes electronic data from registers and/or memory to transform that electronic data into other electronic data that may be stored in registers and/or memory. A “computing platform” may comprise one or more processors.
The term “wireless” and its derivatives may be used to describe circuits, devices, systems, methods, techniques, communications channels, etc., that may communicate data through the use of modulated electromagnetic radiation through a non-solid medium. The term does not imply that the associated devices do not contain any wires, although in some embodiments they might not.
As used herein, unless otherwise specified the use of the ordinal adjectives “first”, “second”, “third”, etc., to describe a common object, merely indicate that different instances of like objects are being referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner.
Various embodiments of the invention may be implemented in one or a combination of hardware, firmware, and software. The invention may also be implemented as instructions stored on a machine-readable medium, which may be read and executed by a computing platform to perform the operations described herein. A machine-readable medium may include any mechanism for storing, transmitting, or receiving information in a form readable by a machine (e.g., a computer). For example, a machine-readable medium may include read only memory (ROM); random access memory (RAM); magnetic disk storage media; optical storage media; flash memory devices; electrical, optical, acoustical or other form of propagated signals (e.g., carrier waves, infrared signals, digital signals, the interfaces and/or antennas that transmit and/or receive those signals, etc.), and others.
This document may use terms that may have slightly different meanings in various other documents, depending on the writer or intended audience. However, within the context of this document, the following terms shall have the following meanings:
Substrate—a planar object suitable for fabricating circuitry within the object or on the surface of the object. In particular, a substrate may be any of: 1) a wafer on which multiple integrated circuits (ICs) may be fabricated, 2) a die (a portion of the wafer which has been separated from the wafer to form an individual IC), or 3) a package substrate (to which a die is physically and electrically attached to form an IC package).
Fabrication—the formation of a circuit on a substrate through such techniques as deposition, etching, and implantation. Physically attaching a pre-manufactured solid element to a substrate is not considered fabrication in this document, although it may be performed in addition to fabrication.
Single-die area—the area of a wafer that is devoted to the fabrication of a single die.
Die fabrication area—the area of a wafer that is devoted to the fabrication of multiple dice. The die fabrication area may include numerous single-die areas.
Scribe line—a real or imaginary line that marks the separation point between physically adjacent dice on a wafer. The scribe lines may be partially or completely destroyed when the wafer is cut into multiple dice.
RFID antenna—the antenna for an RFID tag for receiving radiated electromagnetic energy and sending a response.
RFID tag circuit—the circuitry, exclusive of antenna, that permits an RFID device to generate a modulated identifying signal in response to radiated electromagnetic energy received through the RFID antenna. The RFID tag circuit may be powered by the electromagnetic energy received through the RFID antenna.
RFID tag—the combination of an RFID tag circuit coupled to an RFID antenna.
Various embodiments of the invention may relate to RFID tags (or alternately just the RFID antennas for those tags) that are fabricated onto substrates in various ways. In some embodiments the RFID tags may be fabricated on a wafer and become operational before fabrication of other circuits on the wafer have been completed. Some such RFID tags may be located in individual single-die areas, for possible use before and/or after the fabrication operations have been completed, while other such RFID tags may be located on the wafer external to the die fabrication area, to be used to identify the wafer.
Although the illustrated embodiment shows them, in different embodiments, circuit area 140 and/or RFID tag circuit 120 may not be present on substrate 110. The antenna elements 150, 151 that form the RFID antenna are shown as two separate antenna elements that are near the periphery of the substrate, but other embodiments are also possible. One, three, or more RFID antenna elements may be present. The path followed by the antenna element(s) may also follow routes other than the one shown.
Each single-die area may have an RFID tag fabricated therein, which after it is operational, may be used to identify the individual die or single-die area. Another RFID tag 320 may be fabricated outside the die fabrication area to identify the wafer as a whole without respect to individual single-die areas. In some embodiments each RFID tag on the wafer may have a unique identifying number, for separate identification of the respective tagged areas. In other embodiments, multiple RFID tags may have the same identifying number to simply associate them with a group, such as but not limited to a manufacturing lot number.
Antenna elements 450A and 451A may be an alternative antenna configuration to antenna elements 450B and 451B. Although both are shown in
At 520, an RFID reader may direct electromagnetic radiation having the proper characteristics towards the wafer, and read the identification numbers of the RFID tags that are now operational on the wafer. In some embodiments each RFID tag will respond with a unique identification number, so that each single-die area will have an associated unique RFID identifier. Because RFID tags can be operated without a directly-connected power source, and because RFID technology does not require line-of-sight operation, this operation may be performed while the wafer is still in a processing chamber or other fabrication enclosure, by an RFID reader that is external to the chamber or enclosure.
After reading the RFID tags at 520, additional levels of fabrication may be performed at 530. In some embodiments these additional levels may complete the fabrication of the circuits. The RFID tags may be operated again at 540 for any feasible purpose, such as but not limited to storing intermediate fabrication status. Such operations may be performed as many times as needed, before and/or after completion of the additional fabrication operations of 530. Following completion of the fabrication operations, the wafer may be cut into individual dice at 550, with each die including an operational RFID tag.
Once separated, the individual dice might no longer maintain the orderly physical arrangement that they had while part of a wafer. But another reading operation at 560 may allow the individual dice to identify themselves again to an RFID reader, either one at a time or in groups. The identification operations performed at 520 and 560 may be used for any feasible purpose. Subsequent readings may also allow identification of individual dice during subsequent manufacturing, assembly, and distribution operations.
The foregoing description is intended to be illustrative and not limiting. Variations will occur to those of skill in the art. Those variations are intended to be included in the various embodiments of the invention, which are limited only by the spirit and scope of the appended claims.
