Depth profiling of a Co-implanted silicon wafer by total-reflection X-ray fluorescence analysis after repeated oxidation and HF-etching

A new method of depth profiling has been developed and applied to a Go-impl anted Si-wafer. A square section of only some cm(2) was chosen, a thin near -surface sublayer oxidized by an oxygen plasma and the oxidized sublayer pr ecisely etched by a solution of hydrofluoric acid. The mass of Si Oxidation within the sublayer was determined via differential weighing of the wafer piece and the mass of Co determined by TXRF (total reflection X-ray fluores cence) of the loaded acidic solution. These steps were repeated time and ag ain in order to record a total depth profile showing the relative concentra tion of Co dependent on the depth within the wafer. The integration of this profile gave a total dose of 1.13 x 10(17) ions cm(-2) with high accuracy. The depth resolution of the new method might be in the order of a few nn, the detection limit about 0.01% or 5 x 10(18) atoms cm(-3) of Co.