Valentina Spampinato oral presentation (SN3-Thu4-2-5)
Self-focusing SIMS: a novel metrology for area-selective deposition
1 IMEC, Kapeldreef 75 – Belgium, 3001 Leuven, Belgium
2 Instituut voor Kern- en Stralingsfysics, K.U. Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium
The downscaling required for the target technology generations calls for adapted and innovative characterization techniques. In fact, the micro- and nano-electronics is more and more oriented to confined and 3D structures and heterogeneous materials for which the standard characterization techniques, such as X-Ray Photoelectron Spectroscopy (XPS) or Secondary Ions Mass Spectrometry (SIMS), seem to be no longer applicable. This is mostly related to a non-compatible spatial resolution. In order to overcome the poor lateral resolution, the physics behind the SIMS concept can be exploited thanks to a novel method called self-focusing SIMS (SF-SIMS) . By this method, it is possible to determine the composition of a specific compound considering cluster ions made of the constituents of the compound of interest. In fact, the formation of these clusters can only occur if their constituents are emitted from the same collision cascade and, therefore, are in close proximity on the surface. Since the obtained information is related to an area where all the constituents are present and close to each other, the information is then confined and for this reason can be defined as self-focused.
In this work, the SF-SIMS concept is applied to the area-selective atomic layer deposition (ALD) on a patterned and heterogeneous device, where the ALD growth is required only on specific areas. For this purpose, a self-assembled monolayer (SAM) is used to prevent the ALD growth on the undesired areas, relying on the selectivity of the SAM formation. In this study, we describe the use of a thiol as blocking layer to prevent the subsequent ALD growth on a structured device with pitch size of 90 nm, composed by copper and a low k material. The characterization of such a sample would imply a lateral resolution better than 45 nm to assess the selective deposition. With the application of the SF-SIMS, an ensemble measurement to obtain the desired information can be carried out by considering the cluster ions of interest, without losing sensitivity due to localized analysis areas. In particular, the formation of copper-sulphur cluster ions allow the assessment of the blocking layer deposition on copper, while potential reaction with the low k is checked by looking at silicon-sulphur cluster ions. In the same way, to assess the ALD growth of aluminum on the low k, silicon-aluminum clusters are considered, while the detection of possible copper-aluminum clusters would give an idea of the efficiency of the SAM as blocking layer.
Acknowledgment: We acknowledge the 3DAM Project, that has received funding from the Electronic Component Systems for European Leadership Joint Undertaking under grant agreement No 692527. This Joint Undertaking receives support from the European Union’s Horizon 2020 research and innovation programme and Netherlands, Belgium, France, Hungary, Ireland, Denmark, Israel
 A. Franquet, B. Douhard, D. Melkonyan, P. Favia, T. Conard, W. Vandervorst, Applied Surface Science 365, 2016, 143–152.