Overview of dual damascene integration schemes in Cu BEOL integration

An overview of different dual damascene approaches is given. Three approaches – trench first, trench first with metal hardmask, and via first – are described in detail. Trench first is the easiest approach but due to its limitation only suitable for wide ground rules with moderate aspect ratios. Via first is capable to run fine pitches and/or higher aspect ratios but has many problems to reach a proper transition between trench and via. With respect to this transition the trench first with metal hardmask concept seems to be advantageous, but it has its own challenges and problems. This article describes our solutions to these problems.