INTERFACIAL REACTIONS IN AL-ALLOY/TI/SILICON-DIOXIDE-BASED SUBSTRATE STRUCTURES FOR MULTILAYERED INTERCONNECTS

Interfacial reactions in Al-alloy/Ti/borophosphosilicate glass (BPSG)/Si-substrate structures have been investigated up to the annealing temperature of 550 degrees C. The interfacial reaction changes according to the annealing temperature. Below nr 500 degrees C, a reaction between Al alloy and Ti occurs, and the main reaction product is Al3Ti. The underlying BPSG film remains almost inert. At 550 degrees C, the substrate BPSG film is no longer inert and a reaction between Al alloy, Ti and underlying BPSG film takes place. The reaction never occurs without the Ti layer. Reactions in the Al-Ti-Si-O four-component system must be considered in this temperature range. The main reaction product is Ti7Al5Si12 After the Ti layer is consumed for A1(3)Ti formation, Al3Ti and BPSG react to form Ti7Al5Si12, and a lot of Al moves into BPSG film through the Ti7Al5Si12 Reaction retardation by alloying Al with Si also occurs in this temperature range.