Process And Mechanism Study On Preparation Of Nanoparticles By Solid Dewetting Of Cu-Ti Composite Layer

In the metal/ceramic brazing,the wetting of the metal on the surface of the substrate is an important property.As a counter-process of wetting phenomenon,dewetting has also received widespread attention in recent years.An extremely thin metal film deposited on a non-wetted inert substrate is usually in a metastable state,which breaks and agglomerates when activated mass transport under certain conditions.This transition from a cracking solid metal film to a coalesced island-like granular,has an inversely performance of wetting process is generally referred to as dewetting.This method is also commonly used in the manufacture of metal nanoparticles on the surface of the substrate,where the nanoparticles produced by the dewetting self-assembly technique have a wide range of applications in catalysis,photoelectric sensors and the like.This paper focuses on the dewetting of Cu-Ti composite metal layer on the surface of Si(100)substrate,and obtain neatly arranged and uniformly sized nanoparticle arrays in a controlled manner provides a basis for functional applications.Besides,molecular dynamics software LAMMPS were used for research in the process and composite.In this paper,the dewetting of the Cu-Ti composite layer was conducted,the nanoparticles were characterized,and localized surface plasmon resonance(LSPR)properties were tested.The Ti and Cu metal layers were sequentially deposited on the surface of the Si substrate by magnetron sputtering,and then kept in a tube furnace in an argon atmosphere containing 5% hydrogen to obtain nanoparticles.As the temperature and holding time increased,the roundness of the nanoparticles increased and the size uniformity increased.As the thickness increased,the lowest critical temperature at which the dewetting of the metal film occurs increased,and when the thickness exceeded a certain value,no dewetting occurred.The nanoparticles were characterized by TEM.It was found that there exist Cu4 Ti,Cu3Ti,Cu Ti and Ti in the phase composition of nanoparticles.The larger the size of nanoparticles,the higher the Cu contented.After that,the LSPR effect of different nanoparticles was measured by a spectrophotometer.The roundness increased to make the full width at half maximum(FWHM)of the resonance peak narrower,and the increase of the surface coverage of the nanoparticles resulted in an increase in the absorption rate.An increase in the size of the nanoparticles causes a red shift in the resonance peaks.Second,the dewetting phenomenon was simulated.The dewetting simulations of multi-layer metal and single-layer metal were performed separately.The results of the dewetting simulation of multi-layer metal were basically consistent with the experimental results,which showed that the experimental results and simulation results are both accurate and reliable.In the dewetting simulation of a single layer of metal,the dewetting mechanism was judged as spinodal dewetting,and explained the multiple changes in the dewetting process.Finally,in order to reduce the precise requirements on the process parameters,the treatment was performed before the dewetting experiment to pattern the surface and increase the orderliness of the surface.The surface of the substrate was patterned using HF+HNO3 to etch portions of the surface,resulting in the appearance of a large number of irregular nanoparticles and low dimensional uniformity.The patterning of the film surface adopts two methods of micro-scratching and nano-indentation,respectively,both of which have improved in the size and arrangement of the nanoparticles,and have obtained one-dimensional and two-dimensional array of nanoparticles.