Semiconductor devices and methods of manufacture thereof

A method of fabricating a semiconductor device, the method comprising:

• providing a workpiece;
• forming a barrier layer over the workpiece;
• before forming the barrier layer over the workpiece, forming a layer of oxide over the workpiece, and exposing the layer of oxide to nitrogen to form an oxynitride layer;
• forming a rare earth element-containing insulating material layer over the barrier layer, wherein at least the barrier layer and the rare earth element-containing insulating material layer comprise a dielectric material;
• and
• forming a gettering layer over the rare earth element-containing insulating material layer, wherein forming the gettering layer comprises causing at least a portion of oxygen of the oxynitride layer to move through the barrier layer and the rare earth element-containing insulating material and combine with a material of the gettering layer.