Applications of total reflection X-ray fluorescence to analysis of VLSI micro contamination

This paper demonstrates the microcontamination analysis on wafers after they have been through the conventional ULSI processing steps, by using the vapor phase decomposition/total reflection X-ray fluorescence (VPD/TXRF) technique. It was found that the wafer location in the holding cassette during the chemical cleaning step affected the cleanness of the wafer, and the class 1 environment was not enough to keep the wafer to a contamination level below 5/spl times/10/sup 9/ atoms/cm/sup 2/ for three days storing. The breakdown characteristic of a gate oxide was shown to be closely related with the cleanness of the surface of the oxide.