Oxford Instruments and das-nano demonstrate non-destructive wafer based thickness and resistivity metrology for PEALD TiN.
Commonly titanium nitride (TiN) thickness and resistivity wafer fab in-line metrology is based on ellipsometry and 4-point probe resistivity mapping. Alternative and relatively slower or more complex methods are X-ray photoelectron spectroscopy (XPS), X-ray reflectivity (XRR) and X-ray fluorescence (XRFS). TiN thin films are highly conductive and lose transparency for thicker layers which can make it challenging to accurately measure the thickness by ellipsometry above 10-20 nm. At about 50 nm layer thickness TiN is non-transparent and has a bronze color changing to gold for even thicker layers. In the case of resistivity mapping, 4-point probe is a destructive method leaving scratches from the needles that penetrates the TiN layer and possibly also damages the underlying layers and devices.