ALD & CVD Metal Manganese Precursors from Canada

The other day we had a paper by Barry Lab on how to make your own gold ALD precursor and now here another hot topic in ALD & CVD of Metal Manganese and for sure also this paper is from Canada as well! Manganese is being evaluated by Intel, Imec and others for sub 10 nm Cu barrier in BEOL metallization. Even if those barriers are just a couple of nano meters thin it is big business since the potential in BEOL is huge if the processes were to be used for a multiple wafer passes of the BEOL Cu metallization. Recently at 20/14 nm. It will be interesting to follow if Manganese will put up a fight against Cobalt or the slugger Ruthenium for future interconnect barriers and Cu caps.

Base-Free and Bisphosphine Ligand Dialkylmanganese(II) Complexes as Precursors for Manganese Metal Deposition

Jeffrey S. Price, Preeti Chadha, and David J. H. Emslie
Organometallics, Article ASAP, DOI: 10.1021/acs.organomet.5b00907
Publication Date (Web): December 30, 2015

 

 

Graphical abstract

 

The solid-state structures and the physical, solution magnetic, solid-state magnetic, and spectroscopic (NMR and UV/vis) properties of a range of oxygen- and nitrogen-free dialkylmanganese(II) complexes are reported, and the solution reactivity of these complexes toward H₂ and ZnEt₂ is described. The compounds investigated are [{Mn(μ-CH₂SiMe₃)₂}_∞] (1), [{Mn(CH₂CMe₃)(μ-CH₂CMe₃)₂}₂{Mn(μ-CH₂CMe₃)₂Mn}] (2), [Mn(CH₂SiMe₃)₂(dmpe)] (3; dmpe = 1,2-bis(dimethylphosphino)ethane), [{Mn(CH₂CMe₃)₂(μ-dmpe)}₂] (4), [{Mn(CH₂SiMe₃)(μ-CH₂SiMe₃)}₂(μ-dmpe)] (5), [{Mn(CH₂CMe₃)(μ-CH₂CMe₃)}₂(μ-dmpe)] (6), [{Mn(CH₂SiMe₃)(μ-CH₂SiMe₃)}₂(μ-dmpm)] (7; dmpm = bis(dimethylphosphino)methane), and [{Mn(CH₂CMe₃)(μ-CH₂CMe₃)}₂(μ-dmpm)] (8). Syntheses for 1–4 have previously been reported, but the solid-state structures and most properties of 2–4 had not been described. Compounds 5 and 6, with a 1:2 dmpe/Mn ratio, were prepared by reaction of 3 and 4 with base-free 1 and 2, respectively. Compounds 7 and 8 were accessed by reaction of 1 and 2 with 0.5 equiv or more of dmpm per manganese atom. An X-ray structure of 2 revealed a tetrametallic structure with two terminal and six bridging alkyl groups. In the solid state, bisphosphine-coordinated 3–8 adopted three distinct structural types: (a) monometallic [LMnR₂], (b) dimetallic [R₂Mn(μ-L)₂MnR₂], and (c) dimetallic [{RMn(μ-R)}₂(μ-L)] (L = dmpe, dmpm). Compound 3 exhibited particularly desirable properties for an ALD or CVD precursor, melting at 62–63 °C, subliming at 60 °C (5 mTorr), and showing negligible decomposition after 24 h at 120 °C. Comparison of variable-temperature solution and solid-state magnetic data provided insight into the solution structures of 2–8. Solution reactions of 1-8 with H₂ yielded manganese metal, demonstrating the thermodynamic feasibility of the key reaction steps required for manganese(II) dialkyl complexes to serve, in combination with H₂, as precursors for metal ALD or pulsed CVD. In contrast, the solution reactions of 1–8 with ZnEt₂ yielded a zinc–manganese alloy with an approximate 1:1 Zn/Mn ratio.