Synthesis and Structures of Bis(2‐dimethylaminoethyl)amine Adducts of Strontium Bis(2,2,6,6‐tetramethylheptane‐3,5‐dionate) and Their Use in the CVD of Cubic Strontium‐Doped Hafnium Dioxides

Monomeric, eight‐coordinate Sr(tmhd)2[HN(CH2CH2NMe2)2](EtOH) (1), where tmhd is 2,2,6,6‐tetramethylheptane‐3,5‐dionato, is synthesized from the reactions of HN(CH2CH2NMe2)2, H‐tmhd, and Sr(OEt)2(EtOH)4. Heating compound 1 at 130 °C dissociates EtOH to form monomeric, seven‐coordinate Sr(tmhd)2[HN(CH2CH2NMe2)2] (2). A combination of thermogravimetric analysis (TGA) and thermal stability tests establishes that compound 2 is stable at temperatures below 220 °C. In a cold‐wall, low‐pressure CVD reactor, 2 is used as a liquid precursor at 115 to 175 °C to deposit high‐κ, dielectric, strontium hafnium oxide films in combination with the use of Hf(OtBu)4. The Sr/(Sr + Hf) atomic ratios of the films range from 0 to 0.83. X‐ray diffraction (XRD) shows that films with low Sr doping, e.g., ≤ 0.15, exhibit a crystalline phase consistent with Sr‐stabilized cubic hafnia, while films with higher Sr contents are amorphous. The dielectric constants of the films increase as the proportion of the cubic phase increases. A maximum value of 25 is obtained for the film with a Sr/(Sr + Hf) ratio of 0.07.