| Iron-,cobalt-,and nickel-based nano-thin film materials mainly include pure metal,oxide,nitride,sulfide,carbide,and other alloy materials.These materials have important applications in fields of information storage,metal oxide semiconductor,chemical sensors,and catalysis owing to their excellent magnetic,electronic,and catalytic performance.In recent years,with the increasing demand of film performance,chemical vapor deposition(CVD)and atomic layer deposition(ALD)have became preferable selections for preparation of nano-thin films materials owing to their obvious advantages in film uniformity,compactness,and conformality.Based on the deposition principle of CVD and ALD technology,the precursors play a crucial role in the deposition processes,and therefore begin to attract more and more attention.So far,various type precursors mainly including traditional precursors(metal halides,metal nitrates,and metal actates)and new-type precursors(metal-organic complexes)have been used to prepare iron-,cobalt-,and nickel-based nano-thin film materials.Among these precursors,the low volatility of traditional precursors and corrosivity of metal halides have limited their large scale application;and various drawbacks exist in the majority of reported new-type precursors,such as easy decomposition,high cost,high toxicity,low purity of the deposited films,high deposition temperature of the applied CVD process,and low growth rate of the applied ALD process etc.Moreover,the reported precursors are not enough in kinds and amounts,especially for the lack of liquid ALD precursors.All these situations can’t meet the requirements for the further development of related fields.Based on these backgrounds,searching for new-type precursors for CVD or ALD is of particular importance,not only because the above mentioned drawbacks exist in the reported precursors but also because different structures of precursors greatly affect their physical and chemical properties which strongly affect the growth characteristic and performance of the film produced.In addition,the drawbacks of related fields can be effectively improved by employing precursors with suitable structure,and resulting in relatively low deposition temperature and high film-forming purity of CVD process,high growth rate of ALD process,and available liquid ALD-precursors.On the basic of these studies,herein,this paper carried out a series of research work.Detailed research contents are as follows:(1)Iron,cobalt,and nickel guanidinate complexes were synthesized and characterized.The thermal properties of complexes(including volatility,thermal stability,and vapour pressure)were studied through thermogravimetry analysis(TGA),and their potential as CVD precursors were evaluated through deposition experiments.The results demonstrated that the synthesized complexes possessed excellent volatility and suitable thermal stability,which satisfy the requirements for CVD process.Furthermore,all the corresponding CVD processes were accomplished at relatively low deposition temperatures(below 300 ~oC),and the deposited films exhibited relatively high purity.(2)A series of liquid or low melt point metal amidinate complexes were synthesized through introduction of flexible group(sec-butyl)based on the amidinate ligands,and their structures were characterized.The thermal properties of complexes were studied through TGA,and their potential as ALD precursors were evaluated through deposition experiments.The results demonstrated that the synthesized amidinate type complexes possessed excellent volatility,thermal stability,and reactivity,which satisfy the requirements for ALD process.This work effectively solved the shortage of liquid precursors for ALD.Moreover,the relation patterns between complexes’structure and phase states were preliminarily summarized,which suggests the future strategy for the design of new amidinate type liquid precursors.(3)According to the deposition principle of transition-metal-ALD process,the Ni complexes with electron-rich structure were designed as ALD precursors by introducing N(P)-containing netural ligands on nickel acetylacetonate complex.The thermal properties and adsorption behavior on nickel metal surface of selected complexes were studied through TGA and attenuated total internal reflectance fourier transform infrared spectroscopy(ATR-FTIR),respectively,and their film-forming properties were studied by ALD.The results demonstrated that electron-rich Ni complexes exhibited better volatility,thermal stability,and stronger adsorbility than nickel acetylacetonate.A high film growth rate(2.1?/cycle)of the corresponding ALD process was achieved by usages of strong adsorbility of electron-rich Ni precursor on Ni metal surface,and the deposited films exhibited high purity,low resistivity,and smooth surfaces.(4)According to the deposition principle of metal-oxide-ALD process,theβ-diketonate Ni complexes with organic bases(N,N,N’,N’-tetramethylethylenediamine)were developed as ALD precursors.The thermal properties of selected complexes were studied through TGA,and their film-forming properties were studied through ALD.The results demonstrated that the selected complexes exhibited excellent volatility and thermal stability.Owing to more hydroxyl radical could be produced from ozone under alkaline conditions than the other conditions in the surface reaction system through applying organic bases-containing Ni precursor,the higher reactivity of hydroxyl radical than ozone might have contributed to the high growth rate(2.01?/cycle)of corresponding ALD process.Meanwhile,the deposited films exhibited high purity and smooth surfaces. |
