Fast and Accurate in-Line Monitor of Boron Implantation Energy and Dose by Spectroscopic Ellipsometry
In this work, a single look-up optical model is created to monitor the damaged layer. The look-up components relate to implanted dose behavior, the thickness of the damage layer to the implanted depth (energy) behavior.
Secondary Ion Mass Spectrometer (SIMS) is used as a reference tool. Excellent correlation (R2> 0.99) can be achieved between SE results and SIMS (Figure 2). The damaged layer thickness correlates to SIMS depth (Rp); and the look-up model components correlate to SIMS dose.
Q-time limitation must be considered to achieve stable implantation monitoring before annealing. The implanted surface is unstable and damaged depth and implanted dose decay rapidly within a few hours. Q-time correlation formula is used to compensate the implanted decay behavior (Figure 3).
As a result, 1.64% depth and 0.43% dose range variation can be achieved after Q-time correlation is applied. This research also shows that SE metrology is sensitive to other species used for source-drain implantation and can be extended to control NMOS implant process using Arsenic (As) species.