Ein N‐heterocyclischer Carbenkomplex des Silbers für die plasmaunterstützte räumlich getrennte Atomlagenabscheidung dünner Silberschichten bei Atmosphärendruck

Abstract

Ein Silberamidkomplex eines N‐heterocyclischen Carbens, (1,3‐Di‐tert‐butyl‐imidazolin‐2‐yliden)silber(I)‐1,1,1‐trimethyl‐N‐(trimethylsilyl)silanamid [(NHC)Ag(hmds)], wurde synthetisiert, mittels Einkristall‐Röntgenstrukturanalyse, 1H‐ und 13C‐NMR‐Spektroskopie und EI‐Massenspektrometrie analysiert, sowie bezüglich seiner thermischen Eigenschaften untersucht. Diese neue halogen‐ und phosphorfreie Vorstufe für die Atomlagenabscheidung (ALD) wurde in einem plasmaunterstützten räumlich getrennten (APP‐)ALD‐Prozess unter Atmosphärendruck für die Abscheidung dünner Silberschichten genutzt. Besonders reine und elektrisch leitende dünne Silberschichten mit einem geringen Flächenwiderstand von 0.9 Ω/sq (10−5 Ωcm) wurden bei 100 °C abgeschieden und mittels Röntgenphotoelektronenspektroskopie, Rasterelektronenmikroskopie, optischer Transmissionsspektroskopie und Rutherford‐Rückstreuspektrometrie untersucht. Die Carben‐basierte ALD‐Vorstufe und der zugehörige APP‐ALD‐Prozess ermöglichen zukünftige Anwendungen solcher Silberschichten.

Role of Anionic Backbone in NHC‐Stabilized Coinage Metal Complexes: New Precursors for Atomic Layer Deposition**

“…reflected by a shift of most of the datapoints from similar Cu and Ag complexes at around 0.2 Å, irrespective of the second coordinated atom type X and was further confirmed in our previous studies. [31,32] The complexes synthesized in this study feature CÀ M and CÀ O bonds that can be considered on the shorter end compared to literature known CÀ MÀ O bond lengths. Especially for Ag complexes, shorter and thus stronger bonds might be obtained for N-coordinating anionic ligands indicated by a minimum bond length of 1.95 Å for the shortest MÀ N bond length reported in the CSD and thus should leave room for the optimization of the ligand architecture in the respective complexes.…”

“…Especially for Ag complexes, shorter and thus stronger bonds might be obtained for N-coordinating anionic ligands indicated by a minimum bond length of 1.95 Å for the shortest MÀ N bond length reported in the CSD and thus should leave room for the optimization of the ligand architecture in the respective complexes. A comparison between the CÀ MÀ O bond angles in Cu and Ag complexes reveal that the coordination is preferentially linear (180°, e. g., [Cu( tBu NHC)(hmds)]), [30,31,33] orthogonal (90°, e. g., [Cu(hmds)] 4 ) or in-between (135°, multidentate or bridged complexes). [40] For Cu, the bond angles for complexes in this study and complexes found in the literature with CuÀ O bonds at short CÀ Cu bond distances below 1.9 Å are highly localized around 180°and 135°, whereas for the parent Ag complexes the bond angles are more distorted and diffuse especially for CÀ Ag bond distances greater than 2.1 Å.…”

“…[30] The same concept was later adopted in our recent studies for the spatial ALD of Cu and Ag metal films using [Cu( tBu NHC)(hmds)] and [Ag( tBu NHC)(hmds)] and H 2 plasma at low deposition temperatures of 100 and 120 °C, respectively, while also comparing the similarities and differences between the nature, thermal stability and reactivity of the Cu and Ag complexes. [31,32] While Coyle et al investigated cyclic and acyclic carbenes with different substitution patterns for Cu complexes to assess their influence on volatility and thermal stability while keeping the anionic backbone as a constant in the respective complexes, [33] we envisioned to systematically vary the anionic backbone within NHC stabilized complexes of Cu and Ag. This should not only increase the understanding of the influence of the anionic backbone variation on parameters like thermal stability, volatility and reactivity but also possibly eliminate unwanted elements in the ligand sphere that are prone to incorporate into the thin films such as fluorine, phosphorous or silicon which is one of the drawbacks of the most established Cu I and Ag I precursors.…”

Cover Feature: Role of Anionic Backbone in NHC‐Stabilized Coinage Metal Complexes: New Precursors for Atomic Layer Deposition (Chem. Eur. J. 16/2022)

“…reflected by a shift of most of the datapoints from similar Cu and Ag complexes at around 0.2 Å, irrespective of the second coordinated atom type X and was further confirmed in our previous studies. [31,32] The complexes synthesized in this study feature CÀM and CÀO bonds that can be considered on the shorter end compared to literature known CÀMÀO bond lengths. Especially for Ag complexes, shorter and thus stronger bonds might be obtained for N-coordinating anionic ligands indicated by a minimum bond length of 1.95 Å for the shortest MÀN bond length reported in the CSD and thus should leave room for the optimization of the ligand architecture in the respective complexes.…”

“…Especially for Ag complexes, shorter and thus stronger bonds might be obtained for N-coordinating anionic ligands indicated by a minimum bond length of 1.95 Å for the shortest MÀN bond length reported in the CSD and thus should leave room for the optimization of the ligand architecture in the respective complexes. A comparison between the CÀMÀO bond angles in Cu and Ag complexes reveal that the coordination is preferentially linear (180°, e. g., [Cu( tBu NHC)(hmds)]), [30,31,33] orthogonal (90°, e. g., [Cu(hmds)] 4 ) or in-between (135°, multidentate or bridged complexes). [40] For Cu, the bond angles for complexes in this study and complexes found in the literature with CuÀO bonds at short CÀCu bond distances below 1.9 Å are highly localized around 180°and 135°, whereas for the parent Ag complexes the bond angles are more distorted and diffuse especially for CÀAg bond distances greater than 2.1 Å.…”