Secondary ion mass spectrometry
Secondary ion mass spectrometry (SIMS) is the use of mass spectrometry to analyze positive and negative secondary ions produced by sputtering of a target with a certain energy of ion bombardment.
Secondary ion mass spectrometry main features
(1) depth of information for the surface of several atomic layers or even a single layer
(2) The ability to analyze all elements including hydrogen and detect isotopes
(3) The compound can be analyzed to obtain its relative molecular weight and molecular structure information, and is particularly suitable for detecting organic macromolecules that are not easily volatilized and thermally unstable.
(4) The limit of detection of impurities can often reach the order of 10-4% or even 10-7%, which is a high sensitivity in all surface analysis methods.
(5) Image analysis and depth profile analysis of the micro-region composition can be performed, and a certain degree of lattice information can be obtained.
Secondary ion mass spectrometry principle
(1) Stable bombardment is performed on the sample with a focused ion beam. The primary ions may be backscattered by the sample surface (with a small probability) or may penetrate some atomic layers on the surface of the solid sample to a certain depth. Through the process of a series of elastic and inelastic collision. Primary ions transfer some of their energy to the lattice atoms. Part of these atoms move toward the surface and transfer part of the energy to the surface particles for emission. This process is called particle sputtering. There are also other physical and chemical processes that can occur when an ion beam is bombarded with a sample: primary ions enter the lattice, causing the lattice to change; causing a chemical reaction on the surface with the adsorbed layer, and so on. Sputtering particles are mostly neutral atoms and molecules, a small part of positive and negative charge atoms, molecules and molecular fragments;
(2) ionization of secondary particles (sputtering atoms, molecules and atomic groups, etc.) by mass-to-charge ratio to achieve mass spectrometry separation;
(3) Collecting the secondary ions after mass spectrometry, the elemental composition and distribution of the surface and bulk of the sample can be obtained. During the analysis, the mass analyzer can not only provide multi-element analysis data corresponding to the fresh surface at each moment, but also provide a secondary ion image with a certain element distribution on the surface.
Secondary ion mass spectrometry main features
(1) depth of information for the surface of several atomic layers or even a single layer
(2) The ability to analyze all elements including hydrogen and detect isotopes
(3) The compound can be analyzed to obtain its relative molecular weight and molecular structure information, and is particularly suitable for detecting organic macromolecules that are not easily volatilized and thermally unstable.
(4) The limit of detection of impurities can often reach the order of 10-4% or even 10-7%, which is a high sensitivity in all surface analysis methods.
(5) Image analysis and depth profile analysis of the micro-region composition can be performed, and a certain degree of lattice information can be obtained.
Secondary ion mass spectrometry principle
(1) Stable bombardment is performed on the sample with a focused ion beam. The primary ions may be backscattered by the sample surface (with a small probability) or may penetrate some atomic layers on the surface of the solid sample to a certain depth. Through the process of a series of elastic and inelastic collision. Primary ions transfer some of their energy to the lattice atoms. Part of these atoms move toward the surface and transfer part of the energy to the surface particles for emission. This process is called particle sputtering. There are also other physical and chemical processes that can occur when an ion beam is bombarded with a sample: primary ions enter the lattice, causing the lattice to change; causing a chemical reaction on the surface with the adsorbed layer, and so on. Sputtering particles are mostly neutral atoms and molecules, a small part of positive and negative charge atoms, molecules and molecular fragments;
(2) ionization of secondary particles (sputtering atoms, molecules and atomic groups, etc.) by mass-to-charge ratio to achieve mass spectrometry separation;
(3) Collecting the secondary ions after mass spectrometry, the elemental composition and distribution of the surface and bulk of the sample can be obtained. During the analysis, the mass analyzer can not only provide multi-element analysis data corresponding to the fresh surface at each moment, but also provide a secondary ion image with a certain element distribution on the surface.
