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Families of Volatile Metal Precursors from Roy Gordon’s Group at Harvard University for Use in ALD Applications

Transition metal amidinates for metal, nitride and oxide layer deposition

Atomic Layer Deposition (ALD) is a vapor phase technique capable of producing thin films of a variety of materials.  As device requirements push toward smaller and more spatially demanding structures, ALD has demonstrated potential advantages over alternative deposition methods.  ALD offers exceptional conformity on high-aspect ratio structures, thickness control at the angstrom level, and tunable film composition from metal oxides to noble metals.  ALD has emerged as a powerful tool for many industrial and research applications including ferroelectric memories, switches, radiation detectors, thin-film capacitors and microelectromechanical structures (MEMS).  They also are affording significant improvements in solar cell devices, high-k transistors, solid oxide fuels, protective coatings, fuel cells, lithium ion- batteries and nanogratings.  Reviews of the ALD process and its many applications are currently available from the literature.1-5

ALD procedures feature alternating exposures of chemical precursors to form desired materials, often at significantly lower temperatures then CVD analogs allow.  Typically, ALD processes are conducted at modest temperatures (<350 °C). While the selection of available precursors is impressive, it is not yet possible to grow every material by ALD. The selection is limited, in general, by the availability of reactants that can facilitate the process. The reactants should be volatile enough to enter the gas phase, while not decomposing until they react with the sample surface. The choice of reactants has economic implications, as the synthesis can be time consuming and the starting materials expensive. Unfortunately, there are no perfect set of reagents for all applications, so the choice of reagents involves tradeoffs between cost, availability, safety, volatility and reactivity.

In this regard, amidinates of transition metals have recently arrived on the scene and have proven to be promising reagents for the future.  These products have thermal stability and are reactive.  The benefit of thermal volatility combined with opportunities to develop customized systems for low-temperature deposition, make these attractive precursors.  In addition, their use leads to the elimination of corrosive halogens, and the amidinates are soluble in inert solvents at room temperature.  Furthermore, these compounds are becoming more readily available.  Strem Chemicals is pleased to announce that we are expanding a new line of Roy Gordon amidinate compounds to include cobalt, copper, and iron analogs.  Bis(N,N'-di-i-propylacetamidinato) cobalt (II), min. 98%6 (Catalog # 27-0485), Bis(N,N'-di-sec-butylacetamidinato)dicopper(I), 99%6 (Catalog # 29-7100), and Bis(N,N'-di-t-butylacetamidinato)iron (II), min. 98% (Catalog # 26-0145).

 Roy Gordon

27-0485 is an effective precursor (with metal nitrogen bonds) used in the Atomic Layer Deposition of metals, nitrides, and oxides.  The product sublimes at 50°C (50 mTorr) and has a melting point of 84°C.6  Cobalt oxide (CoO) films have been grown on Si(001) by (ALD) at low temperatures (170–180  °C), using water as a co-reactant with 27-0485.7 Highly conformal CoSi2 films, with low resistivity, are formed using 27-0485 via an annealing of ALD Co thin films,8in addition to CoSi2 nanowires.9 29-7100 has a vapor pressure of 0.1mm at 85°C and serves  as a good precursor (with metal nitrogen bonds)  for use in Atomic Layer Deposition of metals, metal nitrides, and oxides.10-13 26-0145 melts at 107°C and is very useful as an iron amidinate precursor in the deposition of iron, iron carbides and iron nitride thin films.14,15


1. J. Appl. Phys., 2013, 113(2), 021301-1.
2. Coord. Chem. Rev., 2013, 257(23 24), 3222.
3. J. Appl. Phys., 2013, 114, 084901.
4. Semicond. Sci. Tech., 2012, 27(7), 074002.
5. Korean J. of Mater. Res., 2012, 22(4), 202.
6. J. Electrochem. Soc., 2012, 159(5), K146.
7. Nanoscale, 2011, 3(9), 3482.
8. Chem. Mater., 2011, 23, 4411.
9. J. Electrochem. Soc., 2010, 157, D454.
10. Chem. Rev.,2009, 110(1), 111.
11. J. Am. Chem. Soc., 2009, 131, 18159.
12. ECS Transactions, 2009, 25, 181.
13. Appl. Phys. Lett., 2009, 94, 123107/1.
14. Inorg. Chem., 2005, 44, 172.
15. See WO 2004/046417A2


Products mentioned in this blog and related products:

25-0230: Bis(N,N'-di-i-propylpentylamidinato)manganese(II), min. 98%, CAS # 1188406-04-3
26-0145: Bis(N,N'-di-t-butylacetamidinato)iron (II), min. 98%, CAS # 635680-56-7
27-0485: Bis(N,N'-di-i-propylacetamidinato)cobalt(II), min. 98%, CAS # 635680-58-9
28-0045: Bis(N,N'-di-t-butylacetamidinato)nickel(II), (99.999%-Ni) PURATREM, CAS # 940895-79-4
29-7100: Bis(N,N'-di-sec-butylacetamidinato)dicopper(I), 99%, CAS # 695188-31-9
50-1170: Bis(N,N'-di-i-propylacetamidinato)tin(II), 99%, CAS # 1421599-46-3
57-1200: Tris(N,N'-di-i-propylformamidinato)lanthanum(III), (99.999+%-La) PURATREM, CAS #1034537-36-4
70-1000: Tris(N,N'-di-i-propylacetamidinato)ytterbium(III), 99%
71-1050: Tris(N,N'-di-i-propylacetamidinato)lutetium(III), 99%

Visit the link below to view a list of Metal Amidinates on our website:

Metal Amidinates


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