Exceptional thermal stability and high volatility in mid to late first row transition metal complexes containing carbohydrazide ligands

• Published in: Polyhedron Vol. 52; pp. 820 - 830
• Main Authors: Karunarathne, Mahesh C., Knisley, Thomas J., Tunstull, Gabriel S., Heeg, Mary Jane, Winter, Charles H.
• Format: Journal Article
• Language: English
• Published: OXFORD Elsevier Ltd 22.03.2013; Elsevier
• Subjects: Atomic layer deposition; Chemistry; Chemistry, Inorganic & Nuclear; Chromium; Cobalt; Coordination compound; Copper; Crystallography; Film growth precursor; Iron; Manganese; Nickel; Physical Sciences; Science & Technology; Film growth precursor; Coordination compound; Atomic layer deposition; Chromium; Nickel; Iron; Copper; Cobalt; Manganese; CHEMICAL-VAPOR-DEPOSITION; PLASMA ALD METHOD; COPPER-FILMS; ATOMIC-LAYER DEPOSITION; COBALT THIN-FILMS; TUNGSTEN-NITRIDE; DIFFUSION BARRIER; HEXACOORDINATE SILICON; CU-MN ALLOY; SILYL CATIONS
• ISSN: 0277-5387
• DOI: 10.1016/j.poly.2012.07.034

A series of Cu(II), Ni(II), Co(II), Fe(II), Mn(II), and Cr(II) complexes containing carbohydrazide ligands has been prepared and characterized. The Cu, Ni, and Co complexes have excellent properties for application as atomic layer deposition precursors to Cu, Ni, and Co metal films. Treatment of metal(II) halides (metal=Cu, Ni, Co, Fe, Mn, Cr) with the potassium salts of carbohydrazides L1–L6 afforded Cu(L1)2 (75%), Cu(L2)2 (51%), Cu(L3)2 (23%), Co(L1)2 (57%), Cr(L1)2 (62%), Ni(L1)2 (76%), Ni(L2)2 (62%), Ni(L3)2 (62%), Ni(L4)2 (13%), Ni(L5)2 (11%), Ni(L6)2 (29%), [Fe(L1)2]2 (28%), and [Mn(L1)2]2 (12%) as crystalline solids, where L1=Me2NNC(tBu)O−, L2=Me2NNC(iPr)O−, L3=Me2NNC(Me)O−, L4=(CH2)5NNC(tBu)O−, L5=(CH2)5NNC(iPr)O−, and L6=(CH2)5NNC(Me)O−. These complexes were characterized by spectral and analytical techniques, and by X-ray crystal structure determinations for Cu(L1)2, Co(L1)2, Cr(L1)2, Ni(L1)2, and [Fe(L1)2]2. Cu(L1)2, Co(L1)2, Cr(L1)2, and Ni(L1)2 exist as square planar, monomeric complexes, whereas [Fe(L1)2]2 is a dimer. A combination of sublimation studies, thermal decomposition temperature determinations, and thermogravimetric/differential thermal analysis demonstrate that the Cu, Co, and Ni complexes Cu(L1)2, Cu(L2)2, Co(L1)2, Ni(L1)2, and Ni(L2)2 have the lowest sublimation temperatures and highest decomposition temperatures among the series. Additionally, these compounds have higher volatilities and thermal stabilities than commonly used ALD and CVD precursors. Hence, these new complexes have excellent properties for application as ALD precursors to Cu, Co, and Ni metal films.