MOCVD-Processed Ni Films from Nickelocene. Part II: Carbon Content of the Deposits

Abstract

In this study, results are reported on the composition and the electrical and magnetic properties of thin films of nickel deposited by metal-organic CVD (MOCVD) from nickelocene. It was found that the films contain carbon, whose content decreases with increasing deposition pressure and hydrogen flow rate and with decreasing molar fraction of the precursor. Ferromagnetic properties, namely saturation magnetization, Curie temperature, and also electrical conductivity of the films decrease with increasing carbon content. The evolution of the saturation magnetization M s of the films with measurement temperature follows Bloch's law. Carbon is found in the films in different forms, namely carbidic (interstitial), aliphatic, or cyclic. Deposition of these forms is discussed and is correlated with the variations of the properties of the films.

New Insights into Plasma‐Assisted Dissociation of Organometallic Vapors for Gas‐Phase Synthesis of Metal Nanoparticles

“…The availability of these precursors enables a wide‐range of metal and alloyed nanoparticles to be produced. A potential drawback of organometallic chemistry is the organic components which can serve as a source of contamination 39–41. This is especially true for plasma‐based processes where the energy of the electrons (or ions) are more than sufficient to break the organic bonds.…”

Hot-wire-assisted atomic layer deposition of a high quality cobalt film using cobaltocene: Elementary reaction analysis on NHx radical formation

“…[12][13][14][15][16][17] The carbon-metal bond in metallocenes is relatively more stable than that in other metalorganic compounds, making it difficult to form high quality metallic films. [13][14][15] Ruthenium films formed from (C 5 H 5 ) 2 Ru need oxygen as a reactant. [13][14][15] Ruthenium films formed from (C 5 H 5 ) 2 Ru need oxygen as a reactant.…”

Novel Nickel Precursors for Chemical Vapor Deposition

“…From its very first attempt the focus of chemical vapor deposition (CVD) of nickel has been to replace the very toxic nickel tetracarbonyl, Ni(CO) 4 , with a precursor that is less toxic . Ni(cyclopentadienyl) 2 , Ni(methylcyclopentadienyl) 2 , Ni(ethylenediamine)(hexafluoroacetylacetatonate) 2 , Ni(acetylacetonate) 2 , Ni(hexafluoroacetylacetonate) 2 , and Ni(diethylglyoximate) 2 have been proposed as alternative precursors to deposit Ni with hydrogen as a reducing agent. − Unfortunately, the Ni films deposited from these precursors often exhibited significant incorporation of impurities such as oxygen and carbon, even when hydrogen was employed as a reducing agent. Although it was reported that Ni(diethylglyoximate) 2 decomposed to produce pure nickel at a substrate temperature of 400 °C without H 2 , the breakdown of the ligands involved in thermal decomposition of the precursor is inherently prone to incorporating impurities in the deposited films.…”

“…Although it was reported that Ni(diethylglyoximate) 2 decomposed to produce pure nickel at a substrate temperature of 400 °C without H 2 , the breakdown of the ligands involved in thermal decomposition of the precursor is inherently prone to incorporating impurities in the deposited films. Due to its desirable properties, the nickelocene, Ni(cyclopentadienyl) 2 , has attracted much attention; however, the Ni films deposited from it exhibited high carbon contamination, limiting its use as a CVD precursor for deposition of high-quality Ni films. − …”

“…Since hydrogen was essential to reduce the carbon incorporation in the Ni films produced from the conventional precursors such as nickel acetylacetonates or nickelocenes, it is remarkable that pure Ni films could be deposited from the present precursors in the absence of hydrogen. Indeed, it was reported that carbon incorporation in the Ni films deposited from nickelocene increased with a decrease in the hydrogen flow rate whereas nickel deposition was not possible at temperatures lower than 550 °C in the absence of hydrogen. ,− To study the decomposition behavior of the precursors during the deposition process, the exhaust gas from the CVD reactor was collected for each precursor in a liquid nitrogen trap and analyzed by 1 H NMR. This analysis indicated that the exhaust was the corresponding trialkyl phosphite ligand liberated from the precursor molecule intact, which lends support to the high purity of the deposited Ni films.…”