Interfacial reaction between aluminum metal and boron-doped polysilicon in a planar type antifuse device

The interfacial reaction between Al metal and boron-doped polysilicon was investigated to understand the mechanism of link formation in the planar type antifuse with a polysilicon pad and two Al electrodes. In the antifuse, the Si-Al alloy filament with a low resistance was formed only on the boron-doped polysilicon pad, not on the phosphorus-doped or undoped polysilicon pads. After annealing Al/boron-doped polysilicon at 400°C for 20 min, an Al-B compound (AlB₂) was found by the reaction between Al metal and solute borons at the grain boundaries of polysilicon using Auger electron spectroscopy, X-ray diffractometer, and X-ray photoelectron spectroscopy. In the planar type antifuse device, the formation of AlB₂ at the grain boundaries might act as a seed for the conductive filament formation by supplying Al from the positive electrode. After forming a low resistance Si-Al alloy filament, it grows toward the negative electrode by the reaction between supplied Al and highly reactive solute borons segregated at the grain boundaries.