|
CHALLENGES AND TRENDS IN COPPER PLATING TECHNOLOGY FOR 90 nm AND BEYOND Axel Preusse AMD Fab 36 LLC & Co. KG, MS F36 / I 22 - CM Wilschdorfer Landstraße 101, D 01109 Dresden E-mail: axel.preusse@amd.com |
|
After a couple years the challenge shifts from the simple filling task to more sophisticated control over chemical and physical properties of the deposited layer, however filling performance must not be compromised. The plating technology developed by AMD was aimed at best conductor properties for the deposited copper as well as enhanced electromigration properties over the common aluminum technology.
Methods used to characterize film and material properties include EBSD (Electron Back Scattering Diffraction) as well as TOF SIMS (Time of Flight - Secondary Ion Mass Spectroscopy) and XRD (X-Ray diffraction) along with other specialty tailored measurement techniques. There are several process parameters influencing the as deposited film properties.
The influence of the plating regime as well as the composition of the bath will influence chemical and physical behavior of a deposited layer. While one paramter may determine the contamination of the deposit another might have more influence on the texture of the material. Texture (grain size distribution) and composition will determine conductivity of the deposited layer.
That in context with demands arising from ever-shrinking feature size together with the scaled down barrier and seed thickness provides additional challenges. Engineers have to master the terminal effect as well as tasks associated with non-homogeneous micro throwing power depending on the layout as well as hurdles provided by inconsistent or marginal seed coverage in particular features.
The aim is in finding the sweet spot between filling requirements and desired mechanical and chemical properties addressing the needs associated with the upcoming 65 nm technology and beyond.