Abstract:
A timer including a sensor and a radiation source is used to prevent counterfeiting of integrated circuits. The timer confirms the date code of the integrated circuit resulting in a more secure supply chain.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 61/909,478 filed Nov. 27, 2013, which is incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The invention relates generally to integrated circuit (IC) chips. More specifically, the invention relates to a timer device for use in IC chips to prevent counterfeiting. 
     BACKGROUND OF THE INVENTION 
     Integrated circuit (IC) chips are used in a variety of applications including security functions, government defense purposes, electronic devices and systems such as cellular telephones and gaming to name a few. Counterfeit IC chips may result in failures that are more than just inconvenient or a minor loss of money. 
     Counterfeiting of integrated circuit chips has become a major problem. Nearly every industry that relies on electronics for data communication, data management, and data processing has encountered counterfeit integrated circuits. A counterfeit IC chip may include an unauthorized copy, fails to conform to the original component manufacturer (OCM), or has incorrect or false identifying marks or documentation. 
     Counterfeit IC chips results in supply chain vulnerabilities. For example, counterfeit IC chips include those that are recycled and remarked, defective or out of specification, and cloned. 
     In certain circumstances, counterfeit IC chips may include additional logic capable of routing data including secure information such as credit card numbers, account numbers, and passwords from the IC chips into the the hands of an adverse party. 
     In order to counterfeit an IC chip, it is typically reverse engineered by processes such as delamination or delayering. The authentic IC chip is delayered one layer at a time and the circuit configuration of that particular layer is copied as a new schematic layout which can be used for manufacturing the counterfeit IC chip. Other reverse engineering techniques include the use of scanning electron microscopes (SEMs) and backside imaging. 
     Anti-counterfeiting detection methods exist in efforts to detect counterfeiting of IC chips and include, for example, X-ray, scanning electronic or imaging, or DNA marking. However, these anti-counterfeiting detection methods are complicated and time-consuming 
     Thus, there is a need to prevent IC chip counterfeiting along with a simple and easy anti-counterfeiting detection method. The invention satisfies this need. 
     SUMMARY OF THE INVENTION 
     The invention prevents an integrated circuit (IC) chip from being counterfeited utilizing a timer device. The timer device comprises a radiation source component and a sensor component. For purposes of this application, the term integrated circuit chip includes microprocessors, memory chips including digital memory chips and application-specific integrated circuits (ASICs). 
     The timer device is integrated within the IC chip and configured to count down over time regardless of interference occurring outside the timer device. Using an independent timer device according to the invention, the date code stamped on the integrated circuit chip can be verified internally and any discrepancies noted. 
     In one embodiment, the device according to the invention is assembled within an integrated circuit chip. For example, the radiation source component and the sensor component may be laminated to one another and then covered with a radiation-proof shield to prevent spoofing by external sources. The timer device may be interfaced via a spare pin on the integrated circuit chip. 
     An advantage of the invention is that the timer device requires no moving parts. Furthermore, the radiation source component and the sensor component of the timer device are housed within a tamperproof case. Thus, the timer device is fully solid-state in that it is immune to shock and vibration. 
     Another advantage is that the timer device is easy to use in terms of anti-counterfeiting detection. According to the invention, complicated electrical testing or DNA sequencing is not necessary. The IC chip may be simply attached to a counter or a multimeter or voltmeter in order to read the voltage or counts, respectively, of the integrated circuit chip. 
     Yet another advantage is that the timer device does not require any external power. 
     The invention and its attributes and advantages will be further understood and appreciated with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The preferred embodiments of the invention will be described in conjunction with the appended drawings provided to illustrate and not to the limit the invention, where like designations denote like elements, and in which: 
         FIG. 1  illustrates a block diagram of an exemplary embodiment of the timer device according to the invention. 
         FIG. 2  illustrates a block diagram of an exemplary embodiment of an integrated circuit chip including timer device according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a block diagram of an exemplary embodiment of the timer device  100  according to the invention. The timer device  100  includes a radiation source component  110  and a sensor component  120 . As shown in  FIG. 1 , the radiation source component  110  and the sensor component  120  are encased by a radiation-proof shield  130 . The timer device  100  is assembled within an integrated circuit chip  200  as shown in  FIG. 2 . 
       FIG. 2  illustrates a block diagram of an exemplary embodiment of an integrated circuit chip  200 . For exemplary purposes, the integrated circuit chip  200  is shown with a plurality of pins  211 ,  212 ,  213 ,  214 ,  215 ,  216 ,  217 ,  218 . Specifically, a non-inverting input is applied to pin  212 . An inverting input is applied to pin  213 . Pin  214  is a ground power supply pin. Pin  215  is a positive power supply voltage pin. Pin  216  provides gain control. Pin  217  provides output—the difference between inputs of pin  212  and pin  213 —amplified by an operational amplifier  222 . As shown in  FIG. 2 , the integrated circuit chip  200  may include a logic gate  223  that controls the input of pin  212  based on the signal monitor of pin  218 . The timer device  100  is interfaced via a spare pin ( 211 ) on the integrated circuit chip  200  to be protected against counterfeiting. Specifically, pin  211  provides the radiation count to the timer device  100 . 
     In one embodiment, the radiation source component  110  and the sensor component  120  of the timer device  100  are laminated to one another and then covered with a radiation-proof shield  130  to prevent spoofing by external sources. 
     The radiation source component includes a radioactive substance with a known half-life. The radioactive substance is inserted into each integrated circuit chip during fabrication or packaging. More specifically, the radioactive substance may be an isotope such as a sodium isotope. In one embodiment the radioactive substance is sodium isotope  22 Na, however any radioactive substance with a known half-life is contemplated. 
     In certain embodiment of the invention, an industry-standard activity level may be established such that an amount of an isotope with that level of activity is added to the IC chip on its date of packaging. For example, the activity level may be 1 microcurie (μCi). 
     The sensor component  120  is positioned next to the radiation source component  110  and detects radiation on the IC chip. In one embodiment, the sensor component  120  may be a biased conductor/insulator junction. In other embodiments, the sensor component  120  may be a silicon-carbide (SiC) diode. 
     The half-life of the radioactive substance is linked to the lifetime of the integrated circuit chip, such that if the sensor component  120  detects an activity level falling below a predetermined percentage of the standard level, the IC chip is determined “bad”. For example, a bad IC chip may only be used in non-critical applications. 
     While the disclosure is susceptible to various modifications and alternative forms, specific exemplary embodiments of the invention have been shown by way of example in the drawings and have been described in detail. It should be understood, however, that there is no intent to limit the disclosure to the particular embodiments disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure as defined by the appended claims.