Atomic Layer Deposition of Intermetallic Co₃Sn₂ and Ni₃Sn₂ Thin Films

Intermetallics form a versatile group of materials that possess unique properties ranging from superconductivity to giant magnetoresistance. The intermetallic Co–Sn and Ni–Sn compounds are promising materials for magnetic applications as well as for anodes in lithium‐ and sodium‐ion batteries. Herein, a method is presented for the preparation of Co 3 Sn 2 and Ni 3 Sn 2 thin films using diamine adducts of cobalt(II) and nickel(II) chlorides, CoCl 2 (TMEDA) and NiCl 2 (TMPDA) (TMEDA = N , N , N ′, N ′‐tetramethylethylenediamine, TMPDA = N , N , N ′, N ′‐tetramethyl‐1,3‐propanediamine) combined with tributyltin hydride. The films are grown by atomic layer deposition (ALD), a technique that enables conformal film deposition with sub‐nanometer thickness control. The Co 3 Sn 2 process fulfills the typical ALD qualifications, such as self‐limiting growth, excellent film uniformity, and conformal coverage of a trench structure. X‐ray diffraction (XRD) shows reflections characteristic to the hexagonal Co 3 Sn 2 phase, which confirms that the films are, indeed, intermetallic instead of being mere alloys of Co and Sn. The films are extremely pure with impurity levels each below 1.0 at.%. Ni 3 Sn 2 films similarly exhibit the expected XRD reflections for the intermetallic phase and are of high purity. The Co 3 Sn 2 film show magnetic hysteresis with high coercivity values exceeding 500 Oe, indicating great potential in terms of applicability of the films.