Patent Publication Number: US-2015066415-A1

Title: Apparatus and Method for Measuring Microelectronic Electromagnetic Emissions to Detect Characteristics

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to U.S. Provisional Patent Application Ser. No. 61/821,965, filed May 10, 2013, entitled “APPARATUS AND METHOD FOR MEASURING MICROELECTRONIC ELECTROMAGNETIC EMISSIONS TO DETECT CHARACTERISTICS,” the disclosure of which is expressly incorporated by reference herein. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     The invention described herein was made in the performance of official duties by employees of the Department of the Navy and may be manufactured, used and licensed by or for the United States Government for any governmental purpose without payment of any royalties thereon. This invention (Navy Case 102,656) is assigned to the United States Government and is available for licensing for commercial purposes. Licensing and technical inquiries may be directed to the Technology Transfer Office, Naval Surface Warfare Center Crane, email: Cran_CTO@navy.mil. 
    
    
     BACKGROUND AND SUMMARY OF THE INVENTION 
     The present invention relates to defect detection through detection of electromagnetic (EM) emission detection. One embodiment of the invention can use EM probes to measure EM emissions, e.g., EM interference (EMI), and to evaluate a device under test (DUT) system&#39;s operational EM characteristics. For example, an embodiment of the invention can incorporate integration of multiple EM probes in an array and in synchronization with DUT stimulation for the purpose of producing device unique EM signatures that can provide a novel approach to solving a variety of problems and meeting a variety of needs. An exemplary stimulus could be applied in such a way as to produce device dependent signatures useful in determining a probability that a device has a defect, improper part installed, or has otherwise experienced an environmental stress of interest. An exemplary EM apparatus in accordance with this disclosure may include a positioning system, switch matrix, power combiner, switch and EMI shielding to minimize stray EMI signals. An exemplary embodiment can also combine various EM probe types, such as E-field, and H-field probes of varying bandwidths, in an integrated manner. 
     Additional features and advantages of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of the illustrative embodiment exemplifying the best mode of carrying out the invention as presently perceived. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The detailed description of the drawings particularly refers to the accompanying figures in which: 
         FIG. 1  shows an exemplary schematic diagram of one aspect of one example embodiment of the invention; and 
         FIG. 2  shows an exemplary processing sequence in accordance with one embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     The embodiments of the invention described herein are not intended to be exhaustive or to limit the invention to precise forms disclosed. Rather, the embodiments selected for description have been chosen to enable one skilled in the art to practice the invention. 
     Referring initially to  FIG. 1 , an exemplary schematic diagram of one example embodiment of the invention is shown. An exemplary DUT testing assembly  1  is shown which includes a support fixture  3  which supports or positions EM sensors, e.g. EM probes,  5  in relation to a DUT  7 . Signal paths  9  connect EM sensors  5  with amplifiers  11 . Amplifiers  11  are coupled with a signal analysis section  15  which can provide signal analysis in a time domain and/or a frequency domain. For example, amplifiers  11  can be coupled with a signal analysis section  15  comprising a signal analyzer  17  and an oscilloscope  19  via a switch matrix  13 . Separate connections (not shown) to the signal analysis section  15  can be used or a summing section  21  can be used which combines output from one or more amplifiers into a composite signal for input into the signal analysis section  15 . A switch  23  can be interposed between the signal analysis section  15  and the summing section  21 . The EM sensors  5  can be adapted to be repositionable or movable to be placed over specific areas of interest of a particular DUT  7 . 
     One embodiment of the invention can include armatures (not shown) for use with an exemplary embodiment, e.g., a  FIG. 1  system, to position an exemplary EM sensor  5  over areas of interest on a DUT  7 . An exemplary embodiment can include servos that can include mechanisms to selectively move the EM sensors  5  over a DUT  7  for repeatable measurements to include multiple different identical DUTs  7  or multiple measurements including measurements in multiple positions relative to a DUT  7 . 
     An exemplary embodiment of a DUT testing assembly  1  can include a multiplexer to permit selection of a single or any combination of EM sensors  5 . A multiplexer can provide an ability to dynamically combine different EM sensors serving as array elements, minimizing signal acquisition time and quantity of data, while maintaining richness of signature information. A multiplexer adapted for use with one embodiment of the invention can also perform a function of a switch matrix  13  such as in  FIG. 1 . 
     A power combiner may be used to perform a function of a summing section  21 . Such a power combiner would enable combination of signals selected by the multiplexer in a desirable manner e.g., to be combined in a manner maintaining 50 ohm impedance. 
     A plurality of EM sensors  5  can be formed into an array configuration to detect particular EM emissions such as a particular EM emission pattern from a particular set of components on a DUT  7  forming an EM signature pattern. 
     An embodiment of the invention can include multiple types of EM sensors. For example, the plurality of EM sensors  5  can include combinations of E-field and H-field sensors of various bandwidths. An embodiment of the invention using an array allows optimizing signal quality for a given technology and acquisition environment. 
     An embodiment of the invention can also include a DUT Control System  25  adapted to input a Known Good (KG) DUT Test Pattern Control Signals (KGDUTTPCS) (not shown) into a KG DUT  7  in order to stimulate the KG DUT  7  to produce signal characteristics to include a First EM Signature Profile (or KG EM Signature Profile (KGEMCSP)) for the KG DUT  7 . At least one KGEMCSP is acquired by the array of EM Sensors  5  which can be positioned in a KG DUT EM Sensors Position (KGDUTEMSP). The KGEMCSP data and related KGDUTEMSP data are stored for later comparison with a second or subsequent DUTs having selected components, structure, and relationships that are the same or substantially similar to the first or KG DUT  7 . The DUT Testing Assembly  1  in the same or other locations can later be configured to receive the subsequent or second DUT  7 ′, including components found in the first or KG DUT  7  having relatively the same or substantially similar physical/component/relational configurations. In particular, the same or a different EM Sensors  5  array in other locations can then be repositioned to substantially match the EM Sensors  5  array&#39;s pattern based on stored KGDUTEMSP associated with the First EM Signal Profile (or KGEMCSP) collected from the KG DUT  7 . 
     In subsequent testing, the DUT Test Assembly  1  and DUT Control System  25  can stimulate the second or subsequent DUT  7 ′ (not shown) using the KGDUTTPCS associated with the KG DUT  7 . The second or subsequent DUT  7 ′ then produces a Second EM Signature Profile or Under-Test (UT) EM Signature Profile (UTEMSP) which is then acquired by the EM sensors array  5  and stored as a second EM Signature Profile (or UTEMSP) data. The First and Second EM Signature Profiles (KGEMCSP and UTEMSP) are then compared and a determination of whether or not the second DUT  7 ′ is an acceptable DUT or unacceptable DUT; an acceptable DUT determination can be made where a substantial match between the First and Second EM Signature Profile indicates the Second DUT  7 ′ is a good DUT and a significant mismatch between the First and Second EM signal profile indicates the second DUT  7 ′ is a defective DUT. 
     The DUT Control System  25  can also include an ability to store KG DUT  7  configuration identification data and associated EM Signature Profiles for KG DUTs (e.g., DUT  7  configuration specifications and First EM and Configuration Signature Profile or KGEMCSP). The configuration specifications can be input by a user or detected by performing testing on said first DUT to determine, for example, operating parameters or specifications of said DUT to include voltage inputs, current, clock speed, or other detectable specifications of the KG DUT  7 . Such DUT configuration identification data can also include non-specification detectable specification data e.g., optically or electrically detectable patterns, which can be associated with a KG DUT  7  and its stored KGEMCSP. EM Sensor array  5  configurations/positions and KGDUTTPC can be used to generate KG DUT&#39;s  7  First EM Signature Profile (or KGEMCSP). 
     An embodiment of the DUT Control System  25  can also be adapted to couple with the Signal Analysis Section  15  to receive outputs of the signal analysis section  15  and also to control EM sensor  5  positions and also to control devices or circuits positioned between EM sensors  5  and the Signal Analysis Section  15 . An embodiment of the DUT Control System  25  can also include a storage medium adapted to store and output a plurality of machine readable instructions adapted to control various aspects of the invention including the DUT Control System  25  and DUT Testing Assembly  1  as well as providing for an output capability including a user interface. 
     An exemplary user interface can include a graphical user interface (GUI) (not shown) which can provide a graphical depiction of circuit behavior, EM Signature Profile comparison or overlays showing differences or no differences in detected EM signature profiles (e.g., comparison between the First and Second EM Signature Profiles (KGEMCSP and UTEMSP)) as well as a graphical indication of portions of the second or subsequent DUT  7 ′ which are producing a non-matching EM Signature. A user interface can also store data structures with selected test information to include EM Signature Profile Data (e.g., KGEMCSP and UTEMSP), mismatch data, and second or subsequent DUT  7 ′ identification. 
     The DUT Control System  25  can also include a plurality of machine implemented processing instructions stored on a digital recording media or other media such as a programmable logic structure to provide additional analytical processing such as a determination of probability of defects associated with a second or subsequent DUT  7 ′. A plurality of inputs can also be provided to the DUT Control System  25  to permit use of a wide variety of KGDUTTPCS and related KGDUTEMSP to generate KGEMCSPs or UTEMSPs to include power signatures, EM signatures, thermal signatures, specific electrical test inputs, initial settings on a second DUT  7 ′, electrostatic discharge (ESD), different input power or signal curves, pulse responses, or specific standard electrical tests. Additional sensors can be added to an embodiment of the invention to include thermal sensors which create a KG thermal sensor pattern which is then matched against a DUT  7 ′ thermal sensor output after application of one or more KGDUTTPCS and data collection via sensors positioned in the KGDUTEMSP. Image recognition software can be included in another embodiment of the invention to permit matching of thermal pictures or images of a KG DUT  7  with a second DUT  7 ′ to determine good or no-good DUT determinations. 
       FIG. 2  shows an exemplary processing sequence in accordance with one embodiment of the invention. At Step  1 : position a test assembly comprising a plurality of EM sensors; At Step  2 : position a known-good DUT relative to the test assembly; At Step  3 : position the plurality of EM sensors at a plurality of locations in relation to DUT in a first sensor configuration (KGDUTEMSP); At Step  4 : selectively energize the DUT to produce a first EM emission pattern from a plurality of sections on the DUT associated with the KGDUTEMSP, wherein said selective energization comprises inputs associated with a test stimulus patterns (e.g., KGDUTTPCS) adapted to enhance or create a detectable EM signature; At Step  5 : acquire the first EM emission pattern (e.g., KGEMCSP) produced from Step  4  by using said plurality of EM sensors; at Step  6 : store the first EM emission pattern (e.g., KGEMCSP); At Step  7  remove the known-good DUT and replace with a second DUT; At Step  8 : position the second DUT relative to the test assembly; At Step  9  position the plurality of EM sensors at the plurality of locations in relation to DUT at the first sensor configuration (e.g., KGDUTEMSP); At Step  10 : selectively energize the second DUT using the test stimulus patterns (e.g., KGDUTTPCS) to produce a second EM emission pattern (e.g., UTEMSP) from a plurality of sections on the second DUT; At Step  11  acquire the second EM emission pattern (e.g., UTEMSP) produced from Step  10  by using said plurality of EM sensors at said first sensor configuration (e.g., KGDUTEMSP); At Step  12 : store the second EM emission pattern (e.g., UTEMSP); At Step  13 : compare the first and second EM emission pattern (e.g., KGEMCSP and UTEMSP); At Step  14 : Determine if the first and second EM emission patterns (e.g., KGEMCSP and UTEMSP) are substantially identical or different; At Step  15 : Identify the second DUT as acceptable if the first and second EM emission patterns match or unacceptable if the first and second EM emission patterns do not match. 
     One advantage of one embodiment of the invention includes providing an ability for users to implement an optimal design for a selected or target technology and permit rapid evaluation by creating a testing assembly, e.g., printed circuit board, with only sensor array elements, position of such elements and signal inputs for a control mechanism needing to be modified. 
     Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the spirit and scope of the invention as described and defined in the following claims.