A praseodymium adduct, Pr͑hfa) 3 •diglyme ͓(H-hfa ϭ 1,1,1,5,5,5-hexafluoro-2,4-pentandione, diglyme ϭ CH 3 O͑CH 2 CH 2 O) 2 CH 3 )] has been synthesized. It has been applied as a Pr source for the metallorganic chemical vapor deposition ͑MOCVD͒ of praseodymium containing films on silicon substrate and compared with Pr͑tmhd) 3 ͓(H-tmhd ϭ 2,2,6,6-tetramethyl-3,5-heptandione)͔ precursor. Physical and thermal properties of both Pr͑hfa) 3 •diglyme and Pr͑tmhd) 3 precursors have been fully analyzed and their efficacy as MOCVD precursors for the growth of praseodymium oxide films have been fully tested. Depending on the oxygen partial pressure (p O 2 ), different praseodymium oxide phases have been obtained.Complementary metal-oxide-semiconductor large-scale integrated circuits ͑CMOS LSIs͒ are the most popular devices for electronics. High-performance devices, require, however, downsizing of components such as metal-oxide-semiconductor field effect transistors ͑MOSFETs͒. Today, SiO 2 is the major material for MOSFET gate insulator applications. In the near future, equivalent oxide thickness ͑ETO͒ should reach 1 nm and it will become hard to use SiO 2 because of the unacceptable leakage current due to the direct tunneling and consequently higher power consumption. 1 A possible solution to the problem is the replacement of the ultrathin SiO 2 layer with a thicker film of an alternative insulator having higher dielectric constant. 2,3 Rare earth oxides are potential candidates to replace the SiO 2 layer. 4,5 Among the rare earth oxides, praseodymium oxide, Pr 2 O 3 , has not been studied for microelectronic applications so far, despite its high dielectric constant ( ϭ 26-30) 6 and middle bandgap ͑3.9 eV͒. 7 To date, few reports on molecular beam epitaxial ͑MBE͒ growth and pulsed laser deposition of PrO 2 and/or Pr 2 O 3 films on silicon substrates have appeared in the literature. 8-10 Nevertheless the greater complexities of surface topographies and device structures, such as in 3D trench technology, 11,12 require conforming deposition methods, such as metallorganic chemical vapor deposition ͑MOCVD͒, to maintain a high uniform and conformal coverage. Large-scale film growth by MOCVD takes advantages of simpler, less costly equipment, ready scalability, and higher throughput as compared to conventional physical vapor deposition ͑PVD͒ techniques. [13][14][15] Recently, we reported on the MOCVD growth of high quality Pr 2 O 3 films. 16,17 The success of an MOCVD process depends critically on the availability of volatile, thermally stable precursors that exhibit high and constant vapor pressures, because poor performance affects the film properties. Therefore, an accurate knowledge of the physical properties and thermal behavior of precursors is of fundamental relevance for the optimization of processes in the perspective of achieving uniform and reproducible MOCVD film growth.In the present work, we have synthesized and investigated the mass transport properties of a new praseodymium precursor, Pr͑hfa) 3 •diglyme ͓(H-hfa ϭ 1,...