Investigation of methods to enhance the secondary ion yields in TOF-SIMS of organic samples

Heile A, Lipinsky D, Wehbe N, Delcorte A, Bertrand P, Felten A, Houssiau L, Pireaux JJ, De Mondt R, Van Royen P, Van Vaeck L, Arlinghaus HF

Zusammenfassung

In addition to structural information, detailed knowledge of the local chemical environment proves to be of ever greater importance, for example for the development of new types of materials as well as for specific modifications of surfaces and interfaces in multiple fields of materials science, or various biomedical and chemical applications. But the ongoing miniaturization, and therefore, reduction of the amount of material available for analysis constitute a challenge to the detection limits of analytical methods. In the case of time-of-flight secondary ion mass spectrometry (TOF-SIMS), several methods of secondaryion yield enhancement have been proposed. This article focuses on the investigation of the effects of two of these methods, metal-assisted SIMS and polyatomic primary ion (PI) bombardment. For this purpose, thicker layers of organic molecules (polymers and dyes), both pristine, and metallized with different amounts of gold, were analyzed using monoatomic (Ar+, Ga+, Xe+, Bi+) and polyatomic (SF5+, Bi-3(+), C-60(+)) Pis. It was found that polyatomic ions generally induce a significant increase of the secondary ion yield. On the other hand, with gold deposition, a yield enhancement can only be detected for monoatomic ion bombardment. Copyright (c) 2008 John Wiley & Sons, Ltd.