Chemical vapor deposition of ruthenium and osmium thin films using (hexafluoro-2-butyne)tetracarbonylruthenium and -osmium

Synthesis and Characterization of Tris(β‐ketoiminato)ruthenium(III) Complexes: Potential Precursors for CVD of Ru and RuO2 Thin Films

“…Upon selecting H 2 as the carrier gas, no deposition of Ru metal was observed even at a deposition temperature as high as 425 C. This observation is in sharp contrast to the behavior of precursors such as Ru(CO) 5 , [9] Ru 3 (CO) 12 , [17] Ru(CO) 4 (hfb), [18] hfb = hexafluoro-2-butyne, [Ru(CO) 3 (hfpz)] 2 , hfpz = 3,5-bis(trifluoromethyl) pyrazolate, [19] and [Ru(CO) 2 (hfac) 2 ], [20] for which successful metal deposition can be detected at temperatures as low as 300 C. We believe that the notable difference of 1 and 2 may be related to the higher formal oxidation state of the Ru cation observed in the ketoiminate complexes (+3), compared with that of Ru 3 (CO) 12 This +3 oxidation state may require a higher activation barrier to induce in situ metal reduction and deposition, which can account for the greater thermal stability of these source reagents. Of course, another possibility is the greater chemical stability of the ketoiminate ligands under an H 2 atmosphere, due to the bidentate chelate interaction, with the metal.…”

Organometallic Ruthenium Source Reagents for CVD

“…Various ruthenium organometallic complexes have been proposed as CVD source reagents, including ruthenocene [1] and its alkyl substituted derivative complexes such as Ru(C 5 H 4 Et) 2 , [2] and metal carbonyl complexes such as Ru(CO) 3 (C 6 H 8 ), (C 6 H 8 = 1,3-cyclohexadiene), [3] Ru(CO) 4 (hfb), [4] (hfb = hexafluoro-2-butyne), [(C 5 H 5 )Ru(CO) 2 ] 2 , and Ru 3 (CO) 12 ; [5] tris-b-diketonate complexes such as Ru(acac) 3 , Ru(tfac) 3 , and Ru(tmhd) 3 , (tfac = 1,1,1-trifluoro-2,4-pentandionate and tmhd = 2,2,6,6-tetramethyl-3,5-heptanedione); [6] alkenyl and alkene complexes such as bis(2,4-dimethylpentadienyl)-ruthenium, bis(2,4-dimethyloxapentadienyl)ruthenium, [7] (g 6 -C 6 H 6 )Ru(g 4 -C 6 H 8 ), and Ru(C 3 H 5 ) 2 (COD), (COD = 1,4-cyclooctadiene). [8] Although some of these compounds are liquids, or relatively volatile low-melting point solids, which are amenable to sublimation for gas-phase transport into the CVD reactor, most of them possess fairly high melting points, high decomposition temperatures, or are thermally unstable and react with moisture and oxygen when exposed to air, making them difficult to store and handle.…”

Deposition of Conductive Ru and RuO2 Thin Films Employing a Pyrazolate Complex [Ru(CO)3(3,5‐(CF3)2‐pz)]2 as the CVD Source Reagent

“…[5,11] However, other Ru metal CVD source reagents such as ruthenocene and its alkyl substituted derivatives, as well as the tris-b-diketonate complexes, are essentially non-reactive to H 2 , so the Ru deposition is best carried out using a mixture of O 2 and an inert gaseous medium, such as Ar. [30] In the latter case, the precise control of the oxygen partial pressure and accurate tuning of the deposition temperature are extremely important, i.e., if the partial pressure and decomposition temperature are too high, this leads to the formation of a mixed Ru and RuO 2 phase, or even singlephase RuO 2 thin films.…”

“…CVD is a useful method for overcoming these problems, and as a result, several Ru metal-containing organometallic complexes have been examined as potential precursors for CVD. These new source reagents include a) ruthenocene [2] and its alkyl substituted derivatives such as Ru(C 5 H 4 Et) 2 ; [3] b) carbonyl-containing complexes, such as Ru(CO) 3 (C 6 H 8 ), [4] Ru(CO) 4 (hfb), [5] (hfb = hexafluoro-2-butyne), and Ru 3 (CO) 12 ; [6] c) tris-b-diketonate metal complexes, such as Ru(acac) 3 , Ru(tfac) 3 , and Ru(tmhd) 3 (tfac = 1,1,1-trifluoro-2,4-pentandionate and tmhd = 2,2,6,6-tetramethyl-3,5-heptanedionate); [7] and d) alkenyl and alkene complexes of bis(2,4-dimethylpentadienyl)ruthenium, [8] and arene complexes such as (g 6 -C 6 H 6 )Ru(g 4 -C 6 H 8 ) (C 6 H 8 = 1,3-cyclohexadiene), and Ru(C 3 H 5 ) 2 (COD) (COD = 1,4-cyclooctadiene). [9] Most recently, even the considerably less volatile cyclopentadienyl dimer complex [(C 5 H 5 )Ru(CO) 2 ] 2 has proven useful for depositing Ru thin films employing a bench-scale CVD facility.…”

“…Recently, we have established a new program designed to tailor and synthesize novel precursors that may be suitable for the growth of ruthenium and ruthenium oxide thin films. As part of this initiative, we have prepared two b-diketonate complexes, namely Ru(CO) 2 (hfac) 2 and Ru(CO) 2 (tmhd) 2 (hfac = hexafluoro acetylacetonate), of which the hfac compound is as volatile as the carbonyl complex Ru(CO) 5 , but showed considerable improvement in stability in relation to heat and light, making it particularly suitable as a CVD source reagent. [11] We have extended this research program by examining the potential of a new type of ligand system, the 3,5-disubstituted pyrazoles and have synthesized the carbonyl complex [Ru(CO) 3 (3,5-(CF 3 ) 2 -pz)] 2 (1) which possesses bridging pyrazolate ligands.…”