Experimental and theoretical investigation of needle contact behavior of wafer level probing

Wafer probing technique is important for testing integrated circuit devices. For the safety of measured chips, the probe card must be examined to verify the performance before online testing as it must avoid the defect of the pad edge excursion and the excessive scrub length. In addition, during wafer testing the oxidized layer of pad has to be pierced to gain the stable testing by the needle, which should have sufficient force. Therefore, a well-designed probing system is significantly important for wafer testing. In this paper, the simple and accurate theoretical method is established, which benefits to design an appropriate probing system rapidly. Moreover, the finite element method is also developed for analyzing the contact behavior between the needle and the aluminum pad during wafer testing. The results, which are determined by using the theoretical analysis, the finite element method and the experiment, are consistent. Finally, the parameters of a well-designed probing system for testing smaller chips are investigated.