Quality assurance in an implantation laboratory by high accuracy RBS (original) (raw)

A time series of 5 · 10 15 As/cm 2 100 keV implantations into 100 mm silicon wafers has been analysed by RBS, using the amorphous Si yield to determine the charge solid-angle product for each spectrum. Wafers are also annealed and the resistivity characterised by the four point probe. The implants are demonstrated by four point probe to be uniform at 0.7%. Very high precision down to 0.5% in the determination of implanted average fluence is obtained by analysing the sum of RBS spectra obtained over the whole wafer, with total collected charges of up to about 1 mC. An accurate pileup correction does not contribute significantly to this uncertainty which is dominated by the electronic gain. A full uncertainty budget is presented. The absolute accuracy is still dominated by the uncertainty of the silicon stopping force (2%). The implanted fluence is demonstrated to be consistently within about 3% of nominal. (C. Jeynes).