Ofer Adan

MSc Graduate - 2002



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Current occupation: R&D Physicist and a senior applications development engineer at a semiconductor industry leader of process diagnostics and control. Inventor of patent in electron optics engineering, and an active publishing author on semiconductor process diagnostics and control topics.




The research (Sep 99 April 02 ):

(Co-supervision of Prof. Zohar Yosibash with Prof. Roni Schneck from Material Eng Dept.)

      Thermo-Elastic Failure Investigation of Electronic Components, using Stress Check - Funded project:



The objectives of Ofer Adans study were to investigate and prevent thermo-mechanical failures occurring in microelectronic VLSI devices during the manufacturing process. A mismatch of the elastic constants and thermal expansion coefficients between aluminum interconnects and Si3N4 passivation layers causes initiation of mechanical failure in passivation layers. This is due to thermo elastic loading while cooling of the devices from the passivation deposition chamber. Cracks initiate at re-entrant corners, the dimensions of which are of micron size, and propagate into the interconnect layers, where they may be detrimental to the device operation.

A criterion for failure initiation at a tip-notch is proposed, based on the elastic strain energy density (SED) in the vicinity of the tip-notch; A multilevel parametric model of such a device (according to manufacturers nomenclature) has been prepared and the stresses and SED had been found by the finite element method (FEM). A promising conformance between crack locations and the location of maximum tangential stresses at the tip of the passivation notches (Key-hole geometries due to nonconformal step coverage of the passivation over neighboring aluminum line interconnects) has been found. Validation of the model was necessary in order to enable the determination by calculation of the critical SED providing a quantitative failure criterion with applicability for a variety of situations. Thus an experiment has been designed and accomplished to find the failure envelope by full-scale wafer production at extreme fabrication conditions. The results enable us to correlate and determine the (SED)cr failure criterion so to predict and prevent failures in the manufacturing process of VLSI structures.


Last Update: June, 6, 2003