A newly developed Cu(Rh) alloy film and its characteristics and applications

A new type of copper (Cu)-rhodium (Rh)-alloy, Cu(Rh), films is developed by co-sputtering copper and rhodium onto silicon (Si) substrates under an argon (Ar) atmosphere. The new films are next annealed at 600 and 670 degrees C, or alternatively at 100 and 450 degrees C, for 1 h. Longer annealing to the films, for up to 8 days, is also conducted to explore resistivity variation. The resistivity of the new 300-nm-thick film is 2.19 mu Omega cm after annealing at 670 degrees C for 1 h and drifts to 2.26 and 2.14 mu Omega after annealing at 400 and 450 degrees C, respectively, for 200 h. A 2.7-mu m-thick Sn layer is then thermally evaporated atop the new film for stable flip-chip solder joints; their metal and Cu-Sn intermetallic compound (IMC) growth processes vs. various annealing periods are tested. After annealing at 670 degrees C, the new 300-nm-thick film's adhesive strength reaches 44.2 +/- 0.01 MPa, which is 11 similar to 12-fold that of their pure Cu counterpart. Some key test results of the new film are disclosed herein, including its X-ray diffraction (XRD) patterns, transmission electron microscopy (TEM) images, secondary-ion mass spectrometry (SIMS), time-dependent dielectric-breakdown (TDDB) lifetime curves, and adhesive strength. The new film's antibacterial efficacy arrives at an antibacterial ratio of approximately 100% against Staphylococcus aureus (S. aureus) BCRC 10451 for the 300-nm-thick film and approximately 99.82% for the 8 nm film, far superior to that of a pure Cu film, which is 0 with the same annealing temperature range. The new film, hence, seems to be a remarkable candidate material for various industrial applications, such as ultra-large-scale integrated circuits (ULSIC), micro-electronic circuits, printed circuits, flip-chip technology, medical care concerning antibacteria, and the like.