Localized Corrosion of Sputtered Aluminum and Al-0.5%Cu Alloy Thin Films in Aqueous HF Solutions - Part I: Corrosion Phenomena.

It has been observed in the device development laboratories (5216 and 5211) that aluminum metallizations on integrated circuits are sometimes pitted at their edges after etching in ethylene-glycol/hydrofluoric-acid solution and then rinsing in DI water. It has also been observed that pitting is reduced or eliminated by bubbling CO sub 2 through the rinse water. Although these pits have not been a serious problem for devices with metallization line width greater than 1micron, their impact will increase at submicron dimensions. To understand this phenomenon, so that the required processing conditions and controls may be based on fundamental understanding, we first studied the pitting of aluminum and Al-0.5%Cu alloy thin film metallizations in dilute HF solutions, as discussed in this Technical Memorandum.