Study on the Measurement Method of Interface Resistance in HBM-DRAM: Novel Monitoring Method for Bump Contact Resistance

In order to guarantee the quality of HBM-DRAM at the customer's system-level, the abnormalities of interface resistance between metal pad and u-bump in a buffer-die must be pre-screened before assembling with an interposer-die. However, failures involved with interface problems are hard to find in the HBM-DRAM fabrication site since these failures cannot be detected until combined with a substrate in the customer's assembly site. We propose a practical but very effective method for pre-screening of these interface failures in mass production with the idea of small changes in BEOL layout. This testing method can be used to test the interfacial resistance for micro bump on buffer die, and it can be an essential quality monitoring item for buffer die.