Department Events

Events

  • Mar
    12

    Mechanical Engineering- Simpson Lecture: Ares Rosakis

    McCormick - Mechanical Engineering

    3:00 PM L211, Technological Institute

    EVENT DETAILS

    Ares Rosakis, PhD
    Simpson Distinguished Visiting Professor

    Monday, March 12, 2018

    3:00pm - 4:00pm

    Reception following in Cohen Commons

    Got Stress? Visualizing and Inferring Film Stresses in Patterned Wafers

    ABSTRACT:

    The Caltech-developed “Coherent Gradient Sensor (CGS)” method is an optical shearing interferometer sensitive to surface slope changes of plates undergoing deformations and was initially used in conjunction with high-speed photography for the study of dynamic failure of opaque structural materials.
    In the first section of this lecture we describe an entirely different application of CGS of relevance to the microelectronics and opto-electronics industry. Here we present CGS as a unique inspection and reliability tool used for the rapid, full-field, and in-situ measurement of deformation states (slopes and curvature components) in thin film-wafer substrate systems and for the subsequent inference of non- uniform stresses in thin films and thin film structures deposited on such substrates. We also demonstrate the unique ability of CGS to produce curvature maps in large, 300mm patterned wafers during various stages of processing.
    In the second part of the lecture we describe how classical analytical approaches (e.g. the classical Stoney formula), relating local stresses to local curvatures in such systems fail in the presence of misfit stain, temperature and thin film thickness, non-uniformities. To mitigate this we present a series of new analytical models (developed in collaboration with Northwestern colleagues) capable of relating non-uniform curvature components to arbitrarily non-uniform stress states resulting from the presence of geometrical, misfit strain and temperature non-uniformities. A striking outcome of the entire class of such models is that film stresses, in the presence of such non- uniformities, are found to always depend non-locally on system curvatures thus necessitating full field wafer curvature recording rather than point-wise measurements. This remarkable fact makes CGS (a full field rather than a point-wise method of measuring curvatures) a perfect optical technique to be used, in conjunction with the analytical models presented here, for accurate film stress inference and for stress management in realistic cases involving the various processing steps of large, 300mm Wafers.

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    TIME Monday, March 12, 2018 at 3:00 PM - 4:00 PM

    LOCATION L211, Technological Institute    map it

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    CONTACT Theresa Santos    tami.santos@northwestern.edu EMAIL

    CALENDAR McCormick - Mechanical Engineering

  • Sep
    21

    New Student Orientation (Wildcat Welcome)

    University Academic Calendar

    All Day

    EVENT DETAILS

    TIME Friday, September 21, 2018

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    CONTACT Office of the Registrar    nu-registrar@northwestern.edu EMAIL

    CALENDAR University Academic Calendar

  • Sep
    24

    New Graduate Student Fall Registration begins 9 a.m.

    University Academic Calendar

    All Day

    EVENT DETAILS

    TIME Monday, September 24, 2018

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    CONTACT Office of the Registrar    nu-registrar@northwestern.edu EMAIL

    CALENDAR University Academic Calendar

  • Sep
    25

    New Undergraduate Student Fall Registration

    University Academic Calendar

    All Day

    EVENT DETAILS

    TIME Tuesday, September 25, 2018

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    CONTACT Office of the Registrar    nu-registrar@northwestern.edu EMAIL

    CALENDAR University Academic Calendar

  • Sep
    25

    Welcome & Luncheon for New Full-time Graduate Students

    McCormick School of Engineering and Applied Science

    11:30 AM Ryan Family Auditorium, Technological Institute

    EVENT DETAILS

    TIME Tuesday, September 25, 2018 at 11:30 AM - 1:30 PM

    LOCATION Ryan Family Auditorium, Technological Institute    map it

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    CONTACT Northwestern Engineering Events    northwestern-engineering-events@northwestern.edu EMAIL

    CALENDAR McCormick School of Engineering and Applied Science

  • Sep
    27

    Fall classes begin 8 a.m.

    University Academic Calendar

    All Day

    EVENT DETAILS

    TIME Thursday, September 27, 2018

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    CONTACT Office of the Registrar    nu-registrar@northwestern.edu EMAIL

    CALENDAR University Academic Calendar

  • Nov
    12

    Registration for Winter 2019 begins

    University Academic Calendar

    All Day

    EVENT DETAILS

    TIME Monday, November 12, 2018

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    CONTACT Office of the Registrar    nu-registrar@northwestern.edu EMAIL

    CALENDAR University Academic Calendar