New insights into laser ablation processes of heterogeneous samples: Towards analysis of Through-Silicon-Vias

Moreno-García, Pavel; Grimaudo, Valentine; Riedo, Andreas; Cedeño López, Alena; Wiesendanger, Reto; Tulej, Marek; Gruber, Cynthia; Lörtscher, Emanuel; Wurz, Peter; Broekmann, Peter (2018). New insights into laser ablation processes of heterogeneous samples: Towards analysis of Through-Silicon-Vias. Analytical chemistry, 90(11), pp. 6666-6674. American Chemical Society 10.1021/acs.analchem.8b00492

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State-of-the-art three-dimensional very large-scale integration (3D-VLSI) relies, among other factors, on the purity of high-aspect-ratio Cu interconnects such as through-silicon-vias (TSVs). Accurate spatial chemical analysis of electroplated TSV structures has been proven to be challenging due to their large aspect ratios and their multi-material composition (Cu and Si) with distinct physical properties. Here, we demonstrate that these structures can be accurately analyzed by femto-second (fs) laser beam ablation techniques in combination with ionization mass spectrometry (LIMS). We specifically report on novel preparation approaches for the post-ablation analysis of craters formed upon TSV depth profiling. The novel TSV sample preparation is based on deep and material-selective reactive-ion etching of the Si matrix surrounding the Cu interconnects thus facilitating systematic focusedion- beam (FIB) investigations of the high-aspect-ratio TSV structures upon ablation. The particular structure of the TSV analyte combined with the ∅beam > ∅Cu-TSV condition allowed for an in-depth investigation of fundamental laser ablation processes, particularly focusing on the re-deposition of ablated material at the inner side-walls of the LIMS craters formed. This phenomenon is of imminent importance for the ultimate quantification in any laser ablation-based depth profiling. In addition, we have developed a new method which allows the unambiguous determination of the crossing-point of the Si/Cu║bare Si interface upon Cu-TSV depth profiling which is based on pronounced, depth-dependent changes in the mass-spectrometric detection of those Six y+species formed upon the LIMS depth erosion.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Departement of Chemistry and Biochemistry
08 Faculty of Science > Physics Institute > Space Research and Planetary Sciences
08 Faculty of Science > Physics Institute

UniBE Contributor:

Riedo, Andreas; Wiesendanger, Reto; Tulej, Marek; Wurz, Peter and Broekmann, Peter

Subjects:

500 Science > 570 Life sciences; biology
500 Science > 540 Chemistry
500 Science > 520 Astronomy
600 Technology > 620 Engineering
500 Science > 530 Physics

ISSN:

0003-2700

Publisher:

American Chemical Society

Language:

English

Submitter:

Dora Ursula Zimmerer

Date Deposited:

15 May 2018 09:48

Last Modified:

23 Oct 2019 18:36

Publisher DOI:

10.1021/acs.analchem.8b00492

BORIS DOI:

10.7892/boris.116505

URI:

https://boris.unibe.ch/id/eprint/116505

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