Semiconductor devices and methods of manufacture thereof

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

• forming an etch stop layer comprising AlON over a workpiece;
• forming an insulating material layer over the etch stop layer;
• patterning an upper portion of the insulating material layer with a conductive line pattern;
• forming a masking material over the patterned insulating material layer;
• patterning the masking material with a via pattern;
• and
• transferring the via pattern of the masking material to a lower portion of the insulating material layer.

A method, comprising:

• depositing over a substrate an insulating layer having a planar top surface and a planar bottom surface;
• forming in the insulating layer a trench extending from the top surface of the insulating layer and having a trench bottom above the bottom surface of the insulating layer;
• lining the trench with an etch stop layer;
• filling the lined trench with a fill material;
• etching the fill material and the etch stop layer to form a via pattern;
• transferring the via pattern into the insulating layer to form a via extending from the trench bottom to the bottom surface of the insulating layer;
• removing the etch stop layer;
• and
• filling the trench and the via with a conductor.