Mechanical Property Measurement of Interconnect Materials by Magnetostrictive Sensors

Abstract

ABSTRACTThis paper reports on the measurement of elastic modulus for some electronic thin film materials used in electronic interconnects by a magnetostrictive sensor. Thin film materials of Au, Sn, In and Au-rich lead free solder (AuSn) were sputter deposited onto well defined strips of Metglas™. This material possesses magnetostrictive properties whereby it deforms when subjected by a magnetic field and generates a magnetic field when deformed. The MetglasTM strip is driven to resonance via a modulated magnetic field generated by a coil. The elastic modulus of the above materials was determined by measuring the resonant frequency of the sensors before and after film deposition and using the frequency shift, two analytical approaches were employed to extract values. The as sputtered films were examined by X-ray Diffraction (XRD) and Scanning Election Microscope (SEM) to characterize their microstructures. The elastic modulus of Au films was determined by employing two mathematical methodologies that resulted in values of 71.2GPa and 75.9GPa, which exhibit less than 5% divergence. Errors in the different measuring methodologies are discussed. Moreover, elastic modulus values of solder materials of AuSn (80/20 wt%), tin and indium films, which were also measured in their as deposited forms, will be discussed. This method represents a potentially new, non-destructive method to determine critical material properties of as deposited materials.