High spatial resolution secondary ion mass spectrometry with parallel detection system

Abstract

High-resolution secondary ion mass spectrometry is constructed by combining focused liquid metal ion beam and simultaneous detection mass spectrometer. A beam diameter on the sample is estimated to be less than 0.1 μm with the current of 100 pA, when the accelerating voltage is 35 kV. The detector is composed of a microchannel plate, and a multianode–multiamplifier–multicounter system controlled by a personal computer. The prototype multichannel detector covers the 1:2 mass range of m/e dispersion with a 120-channel parallel counting system. By using a multichannel parallel detection scheme, a spectral data acquisition rate several tens of times larger than that of the single-channel scheme was achieved. An ion-induced secondary electron image, a total secondary ion image, and mass-analyzed ion images (element maps) were obtained. In the individual analysis of a small particle, rapid and distinctive intensity changes for multiple elements were observed. This indicates that our detecting system is suitable for the accurate analysis of small-volume samples.