Accurate calibration of TXRF using microdroplet samples

Abstract

TXRF has been applied in combination with VPD to the analysis of trace impurities in the native oxide layer of Si wafer surfaces down to the range of 10(8) atoms. cm(-2). Proper quantification of VPD/TXRF data requires calibration with microdroplet standard reference wafers. The precision of calibration function has been evaluated and found to allow quantification at a high level of 3 sigma confidence with microdroplet standard reference.

Automated nanoliter solution deposition for total reflection X-ray fluorescence analysis of semiconductor samples

“…Recent reports in the literature suggest that saturation of the TXRF signal can under-report the true value of the contamination in analyses where the contamination in the residue is greater than 3 ng [5,6], thus limiting the linear dynamic range of the technique. It has also been shown that control of the effects of the dried VPD residue's morphology on the TXRF signal is of critical importance affecting reproducibility and accuracy when matching a sample to a standard [7][8][9][10][11]. The advances in nanoliter quantity dispensing instrumentation that include rapid droplet drying time [12] and programmable dispensing patterns make it worth investigating as a novel approach for drying VPD residue on the wafer to improve the accuracy and precision of VPD-TXRF measurements.…”

Quantification of metal trace contaminants on Si wafer surfaces by Laser-SNMS and TOF-SIMS using sputter deposited submonolayer standards

“…A further lowering of detection limits of trace metals on wafer surfaces may be achieved by the combination of TOF-SIMS and Laser-SNMS with the technique of vapor phase decomposition ͑VPD͒ as it is done with TXRF. 22 …”

Trends in total reflection X-ray fluorescence spectrometry for metallic contamination control in semiconductor nanotechnology

“…A micro-droplet residue calibration sample is prepared by the deposition of a droplet (1-100 μL) of a diluted AAS or ICPMS standard solution on a clean and hydrophobic (HF or Si treated) wafer surface, which is dried into a residue [74]. The metal content is known from the concentration of the standard solution and the dilution procedure.…”