Published online by Cambridge University Press: 25 February 2011
Contamination level of chemically cleaned (100) GaAs wafer surfaces were measured by Total reflection X-Ray Fluorescence (TXRF). Cu and Zn were detected as major metallic Impurities on GaAs surfaces. The Cu contamination level was in the range of 1011 atoms/cm2 on wafers treated with NH4 OH/H2O2 /H2O (80:1:400) mixture. On the other hand, Cu could be reduced to less than 5×1010 atoms/cm2 and Zn could be controlled below the detection limit by treating with a choline/H2O2 /H20/Na5P3O10 or SEMICO-CLEAN 23/H2O2 /Na5P3O10 solution. Surface cleanliness depended on the H2O2 concentration and whether or not Na5P3O10 was present in the organic base solutions.