??? for fine pitch solder ball and flip-chip package method using the UBM

摘要

Aflip-chip package for implementing a fine solder ball, and a flip-chip packaging method using the same. The flip-chip package includes a first wafer (100) having a first electrode and a first under bump metal (111,112) (UBM) formed on the first electrode and electrically connected to the first electrode; and second wafer (200) opposing the first wafer and having a second electrode located in a position corresponding to the first electrode, and a second UBM (211,212) formed of the second electrode and electrically connected to the second electrode. The first wafer (100) has a depression formed on one or more areas adjacent to the first UBM (111,112), which depression partly receives a solder ball (133a,134a) that connects the first (111,112) and the second UBMs (211,212) upon flip-chip bonding of the first (100) and second (200) wafers. Since the UBM is formed as an embossing pattern, a fine solder ball can be implemented. Additionally, the reliability of the package can be improved. IMAGE