Study on step coverage and (111) preferred orientation of aluminum film deposited by a new switching bias sputtering method

Abstract

A new switching bias sputtering method capable of improving both the step coverage at the small contact holes and the quality of aluminum film has been developed for the formation of reliable interconnection of very large scale integrated circuits. The method features alternating operation of standard and bias sputtering in 5×10−4 Torr of argon. Aluminum film deposited using this method is seen to have seven times higher (111) orientation and four times higher electromigration resistance than simple bias-sputtered aluminum film. Additionally, the step coverage is raised to 50% for a perpendicular step with 1 μm depth and 1 μm width.