Direct evidence of gate oxide thickness increase in tungsten polycide processes

The increase of the effective gate oxide thickness for W-polycide processes is studied. The samples with as-deposited and annealed W polycide were analyzed by secondary ion mass spectrometry, transmission electron microscopy (TEM), and high-frequency CV measurements. The TEM cross section shows that the gate oxide thicknesses are approximately 244 and approximately 285 AA for as-deposited and 1000 degrees C annealed samples, respectively. The TEM results agree with those from CV measurements. The TEM analyses provide direct physical evidence of an additional oxide thickness ( approximately 41 AA) during the W-polycide annealing.>