Chemistry of Ruthenium Diketonate Atomic Layer Deposition (ALD) Precursors on Metal Surfaces

Abstract

The thermal chemistry of tris(2,2,6,6-tetramethyl-3,5-heptanedionato)ruthenium(III) (Ru(tmhd) 3 ), a potential precursor for the chemical deposition of ruthenium -containing films, on Ni(110) single-crystal surfaces was characterized by using a combination of temperatureprogrammed desorption (TPD), X-ray photoelectron spectroscopy (XPS), and reflection−absorption infrared spectroscopy (RAIRS). Additional characterization of the surface chemistry of the protonated ligand, Htmhd, was evaluated as well for reference. It was found that the molecularly adsorbed ruthenium compound reacts readily by approximately 310 K, loosing its ligands to both the gas phase and the surface as the central ion is reduced to its Ru 0 metallic state. The diketonate ligand, now bonded to the nickel surface, starts to decompose at around 400 K, and generates gas-phase carbon monoxide and molecular hydrogen in TPD peaks at 435 K. More extensive decomposition is seen at 535 K, yielding 2,2-dimethyl-3oxopentanal, isobutene, ketene, and carbon monoxide, and also carbon dioxide and molecular hydrogen at slightly higher temperatures. The XPS data corroborate the early reduction of the metal center and the losses of carbon-and oxygen-containing adsorbates to the gas phase, and the RAIRS traces show similar chemistry followed by the Ru complex and the free ligand, both converting via an initial decarbonylation step and a subsequent loss of the terminal tert-butyl groups. The early decomposition of the ligand on the metal surface points to potential problems with the clean deposition of metal films using diketonate complexes, but the ease with which those ligands are displaced from the central ion suggests that there is a potential for low-temperature film deposition chemistry under specific circumstances.

Thermal Chemistry of Metal Organic Compounds Adsorbed on Oxide Surfaces

“…Our past surface-science studies on the thermal reactivity of Cu(acac) 2 22,85 and Ru(III)-tris(2,2,6,6-tetramethyl-3,5-heptanedionate) (Ru(tmhd) 3 , Compound 4) 86 on Ni (110) and Cu (110) single-crystal surfaces have shown desorption of the protonated ligand (Hacac), extensive fragmentation to produce ketones, ketenes, olefins, molecular hydrogen, and/or carbon monoxide, and an earlier reduction of the metal ion. Similar early protonation of ligands and the formation of a surfacebound Cu(I) intermediate have been reported with Cu(acac) 2 and Cu(hfac) 2 on hydrogen-terminated Si(111) surfaces.…”

“…The data for the diketonates were acquired in a second two-tier UHV chamber. , The main level of that chamber is equipped with a UTI quadrupole mass spectrometer, used for the TPD experiments, a concentric hemispherical electron and ion energy analyzer (VG 100AX) and an Al Kα/Mg Kα dual-anode X-ray source, used for XPS data acquisition, and a Kratos rasterable ion gun, used for sample cleaning. The RAIRS experiments are carried out in the second tier, in an arrangement similar to that used by us to study catalytic systems, employing a Bruker Tensor 27 Fourier-transform infrared (FTIR) spectrometer equipped with an MCT detector.…”

Mixed Films Based on MgO for Secondary Electron Emission Application: General Trends and MOCVD Prospects

“…This gas medium, as almost free from oxygen, generates the Fs defects in MgO, which are the strong basic sites and active donors of electrons [14]. Addition of another precursor such as Zr(thd) 4 changes of the gas medium through the formation of quite stable CH x , C(CH x ) gas species [59][60][61][62] that are converted to CO 2 and H 2 O molecules during MOCVD process increasing the amounts of undesired carbon dioxide species. These molecules adsorb easily firstly on very active morphological sites, and then, on the Fs defects, when the first sites are already occupied.…”

Recent advances in mechanism investigation of atomic layer deposition by <italic>in situ</italic> photoelectron spectroscopy

“…[77~80] 通过结合原位XPS与程序升 温脱附质谱(TPD)技术, 研究了N,N′-二仲丁基乙脒基 铜(I) (Cu(amd)) [77] 、乙酰丙酮铜(II) (Cu(acac) 2 ) [78] 、三 (2,2,6,6-四甲基-3,5庚二酮基)钌(III) (Ru(tmhd) 3 ) [79] 、 三羰基(甲基环戊二烯基)锰(I) [80] 等多种ALD前驱体的 表面热解过程, 发现前驱体的化学吸附过程往往包含 了多种复杂的化学反应路径, 对ALD前驱体的选择和…”