A novel Al-reflow process using surface modification by the ECR plasma treatment and its application to the 256 Mbit DRAM

A novel Al-reflow process with the electron cyclotron resonance (ECR) plasma treatment for the modification of underlayers was developed in a vacuum isolated sputtering equipment. The key feature of this technology is the introduction of the in-situ ECR plasma treatment for the modification of the surface characteristics such as surface morphology and stoichiometry of the TiN wetting/barrier layer. High wettability of the Al film was obtained on the ECR-treated TiN surface, producing a conformal Al film on the sidewall of the contact hole before the reflow process. Consequently, complete filling of contact holes with Al was achieved in deep sub-micron contact holes with a high aspect ratio. This study has demonstrated that the Al-reflow process can be extended to the process of the devices of 256 Mbit DRAM generation and beyond.<>