Liquid metal ion source and secondary ion mass spectrometric method and use thereof

Abstract

A liquid metal ion source for use in an ion mass spectrometric analysis method contains, on the one hand, a first metal with an atomic weight ≧190 U and, on the other hand, another metal with an atomic weight ≦90 U. One of the two types of ions are filtered out alternately from the primary ion beam and directed onto the target as a mass-pure primary ion beam.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application is a divisional of U.S. patent application Ser. No. 12 / 739,993, filed May 7, 2010, now pending. This application claims priority from this parent application Ser. No. 12 / 739,993. The invention disclosed and claimed herein is related in subject matter to that disclosed in International Patent Application No. PCT / EP08 / 08781, filed Oct. 16, 2008 and European Patent Application No. 07021097.6, filed Oct. 29, 2007, all of which are incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]The present invention relates to a liquid metal ion source, a secondary ion mass spectrometer, and also a secondary ion mass spectrometric analysis method as well as the use thereof.[0003]Secondary ion mass spectrometry is operated inter alia as so-called “Static Secondary Ion Mass Spectrometry” (SSIMS). An energy-rich primary ion beam is thereby directed onto a substrate surface to be analyzed. When impinging on the substrate, the pri...

AI Technical Summary

Benefits of technology

[0031]Bismuth is used particularly advantageously as first metal with a high atomic weight ≧190 u, advantageously one of a plurality of bismuth ion types, the mass of which is approximately or precisely a multiple of the monoatomic bismuth ion charged once or several times, being filtered out from the primary ion beam, as mass-pure filtered primary ion beam. Manganese has proved to be particularly advantageous as further metal, manganese being available as further metal with a low atomic weight ≦90 u for filtering out the filtered primary ion beam with high fragmentation.

Problems solved by technology

With increasing numbers of primary ion sources and use of different bombardment conditions, the construction of a spectrum library is increasingly more difficult.

The G-SIMS method is in fact held in high regard, but in practical laboratory use, has to date only limited acceptance.

This resides inter alia in the fact that the experimental complexity for this method is very great.

The change between different species of primary ions is however very complex with these gas sources.

Furthermore, these sources deliver only a restricted performance with respect to the achievable lateral resolution and mass resolution.

However, this demands high technical outlay, the achievable performance of such a G-SIMS analysis being limited by the weakest of the sources which are used.

The required spectra can only be acquired here in succession so that the temporal complexity is very great.

However is was quickly shown that the required strong variation in fragmentation with these sources could not be achieved.

The maximum fragmentation in this case is however achieved by the use of the atomic species, the fragmentation being relatively low because of the large mass of the Au or Bi in the monoatomic primary ion beam and the achievable variation in fragmentation between the use of the clusters as primary ion beam and the use of monoatomic primary ions as primary ion beam not being sufficient.

To date, no primary ion sources which would be suitable for successful implementation of the G-SIMS method are therefore known.

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