Thickness determination of ultrathin metal films using the X-ray fluorescence technique

The X-ray fluorescence technique was used to determine the thickness of single-layered, double-layered and triple-layered films of copper, bismuth and gold on mylar substrates. An annular ¹⁰⁹Cd X-ray source of 5 mCi was used to excite hte characteristic X-rays. The background was much lower as well as flat in the present study in comparison with our earlier results an ²⁴¹Am exciter source. This resulted in a downward extension of the lower limit of thickness measurement of thin films coupled with an improved accuracy.