ELECTRICAL CHARACTERIZATION OF TIN TISI2 AND WN/TISI2 CU-DIFFUSION BARRIERS USING SCHOTTKY DIODES/

For application of copper in contact level metallization, diffusion ba rriers between Cu and Si are indispensable. As copper can cause seriou s deterioration to device performance when diffusion through the barri er occurs, characterization of barrier stability requires extremely se nsitive methods for detection of copper. For that purpose, reactively sputtered TiN and WN barriers on SALICIDE TiSi2 contacts were intensiv ely investigated using capacitance-voltage (C-V) and current-voltage ( I-V) measurement on Schottky diode test structures. The results are co mpared to simultaneously fabricated nip junction test structures. It i s shown that Schottky diode test structures provide early and simple d etection of barrier failure, by alteration of the electrical barrier h eight and by additional diode capacitances. The determined failure tem peratures are 600-700 degrees C for TiN/TiSi2 and 600-800 degrees C fo r WN/TiSi2, depending on the test structure applied. Lower failure tem peratures always refer to Schottky diode test structures. The addition al capacitances which appear along with barrier failure are significan tly frequency and temperature dependent.