Electrical Investigation of Cu Pumping in Through-Silicon Vias for BEOL Reliability in 3D Integration

Abstract

It is crucial for Cu TSV to be reliable at the back-end-of--line (BEOL) procedure particularly at high temperature process step. Any unreliable Cu TSV may cause residual from thermal stress due to the mismatch of the coefficient of thermal expansion. Therefore, it is important to investigate on the behavior of Cu pumping whether it will affect the electrical performance in BEOL integration. Two sets of Cu pumping with pitch 30 mu m and 40 mu m were annealed to measure their resistance at the temperature lower than 250 degrees C. Based on the results, the narrow pitch of 30 mu m can be applied in post via last process below 250 degrees C for BEOL procedure in 3D integration.