ミニ突起法によるSIMSの深さ方向濃度分布測定精度の向上

抄録

A mini-projection technique to be applied to the practical depth profiling in secondary ion mass spectrometry (SIMS) has been developed. This new method is combination of a sample pretreatment and a high acceptance (sensitive) technique for secondary ion optics. The sample pretreatment makes it possible to removes the interfering secondary ions that originate at the periphery of the ion beam etched crater so that high depth resolution can be attained. In this high acceptance technique the least confusion circle (crossover point) of the secondary ion beam is placed at the entrance slit of a double-focussing mass spectrometer so as to obtain high sensitivity in depth profile measurements. To evaluate the detection limit and depth resolution of the mini-projection method, αSi: H thin films deposited on Si wafer and on B-implanted Si wafer were measured in the depth analysis mode. As result, the depth resolution of the O and C atoms included in the αSi thin films increased as indicated by the steepness of the concentration gradient (ΔY was reduced by one-thirds compared to the value obtained by the conventional method). The detection limit for B in this proposed method is also reduced to about 40% of that in the conventional method.