An Investigation of Wafer Probe Needles Mechanical Properties and Contact Resistance Changing Under Multiprobing Process

In the semiconductor industry, fabrication defects in integrated circuit chips are generally identified using a needle probe card. Ideally, the probe needles should have a high elastic modulus and should maintain a low contact resistance even following repeated surface contacts. Using a high-precision microforce tensile tester, this study commences by investigating the thermo-mechanical properties of tungsten (W), tungsten-rhenium (ReW), and beryllium-copper (BeCu) probe needles. The tensile tests are conducted at temperatures ranging from room temperature to 150 degC at a loading rate of approximately 4 mm/min. Stress-strain curves are constructed to examine the temperature dependence of the elastic modulus, yield stress, and fracture strain of each needle. The experimental data are then employed to develop an empirical formula to predict the stress-strain response of the three needles. Subsequently, a single-contact probing test is performed to investigate the effect of the overdrive displacement on the scrub mark length, contact force, and contact resistance for each type of needle. Finally, a multicontact probing test is performed to evaluate the effect on the contact resistance of surface particle accumulation on the probe tip following repeated surface contacts.