General review of issues and perspectives for advanced copper interconnections using air gap as ultra-low K material

The present paper deals with the different techniques investigated in the whole microelectronics community to integrate air cavities, usually known as air gaps, in-between copper lines for advanced interconnects. The different integration processes were split into two categories, i.e. (i) using a non-conformal CVD deposition inside patterned trenches and (ii) by removing a sacrificial material using a specific technological operation. Advantages and drawbacks of the different approaches will be discussed, including integration issues, manufacturability, and electrical performances. The aim of the paper is to sensitize the BEOL community on these specific approaches that now appear attractive considering the electrical performances required for 45 nm and below technological nodes.