Thermomechanical study of AlCu based interconnect under pulsed thermoelectric excitation
Résumé
The thermomechanical behavior of microelectronic interconnect lines under pulsed electric excitation is studied by laser interferometry and reflectometry. An original data processing method and an analytical stationary thermoelastic model are proposed to derive data of interest. The experimental techniques allow one to measure the local transient temperature change at surface and the normal surface displacement produced by Joule heating in the interconnects under normal operating conditions. The proposed data processing method exploits the temporal behavior of the surface temperature change of the interconnects as an “identifying characteristic’’ to analyze the surface displacement. It separates the thermal dilatation which follows “instantaneously’’ the temperature change from the one related to the heat diffusion in the resultant normal surface displacement. After the separation operation, a stationary thermoelastic model for a metallic line bonded to a thick and rigid substrate subject to a uniform temperature change is used to interpret the transient surface displacement measurement. Consequently, the operating temperature, one of the major factors limiting the quality and reliability of the interconnects and other related parameters can be estimated in a simple way.