| Titanium nitride has face-centered cubic structure,good wear resistance,good thermal stability,corrosion resistance and oxidation resistance,so it is often deposited on the surface of die steel as a coating material in physical vapor deposition,so as to effectively improve the surface hardness,wear resistance and service life of die steel.Limited by current experimental instruments,there are few studies on the microstructure growth and deposition mechanism of TiN thin films.It is of great significance to study the interaction between deposited particles and substrate on atomic scale and reveal the microscopic process and deposition law of the film at the initial growth stage,which can predict the deposition behavior of the film,improve the mechanical properties of the film,reduce the residual stress of the film,adjust the production process of the film and improve the production quality of the film.With the development of computer theory and technology,molecular dynamics method has been used more and more to simulate the interaction between atoms and molecules in various systems,and the micro information such as kinetic energy,potential energy and interaction of particles can be extracted from the simulation results,which is difficult to obtain under the existing experimental conditions.Therefore,the application of molecular dynamics in the simulation of thin film deposition process can better describe the microscopic process and structural evolution of thin film growth at the atomic scale,feeding back experimental research and theoretical exploration,and forming a mutually reinforcing virtuous cycle.In order to reveal the particle deposition behavior and microscopic growth process of TiN film in PVD process,molecular dynamics simulation method was used to establish TiN deposition model and carry out the simulation of TiN film deposition process.Firstly,the deposition of single atoms on TiN(001)substrate is simulated,the interaction between incident particles and substrate is analyzed,and the effects of substrate temperature and incident energy on the adsorption,reflection and sputtering behaviors of incident particles are studied.At the same time,the kinetic and potential energy evolution of particles in the deposition process was tracked,and the adsorption behavior of incident atoms was further analyzed from the perspective of energy,which expanded the understanding of TiN film growth mechanism.Secondly,the deposition process of Ti and N atoms on TiN(001)was simulated,and the growth pattern of TiN film was studied.The effects of different deposition parameters on film coverage,surface quality,density and film stress were investigated.Finally,the deposition of TiN on H13 steel was simulated,and the growth pattern,surface roughness and residual stress of the film were analyzed.At the same time,the physical vapor deposition experiment of TiN on H13 steel was carried out,and the experimental results were compared with the simulation results,which further verified the accuracy of the simulation results.The main results are as follows:(1)In the simulation of monatomic deposition process,four different collision sites are defined,namely top site,bridge site,valley site and general site.The adsorption behavior of incident N atomic bomb mainly occurs at the top and bridge sites.When the incident energy is 1-4 eV,the adsorption capacity of incident N atom decreases gradually with the increase of incident energy.When the incident energy increases to 4 eV,the adsorption capacity of the deposited N atom tends to be stable,and the initial adsorption coefficient is about 0.4.In the range of simulated incident energy and four different collision sites of the substrate,the incident Ti atoms are mainly adsorbed,and almost no reflection and sputtering behavior.This is because the sum of the initial kinetic energy and potential energy of the incident atom is less than the osmotic barrier of the atoms on the surface of the base,and the kinetic energy is dissipated by the base atoms in the incident process and eventually absorbed.When the incident energy is greater than 1 eV,the maximum kinetic energy increment of incident Ti atom is close to a fixed value at the four different collision sites.(2)In the simulation of TiN/TiN(001)film deposition process,the effects of incident energy,incident Angle and deposition rate on the growth mode of TiN film were firstly studied.It was found that the growth mode of TiN film was largely determined by incident energy,and was basically not affected by the deposition rate and incidence Angle.When the incident energy is low,the deposited atoms have weak mobility after momentum transfer with the substrate and cannot fill the vacancy of TiN film,and TiN film eventually grows in an island shape.When the incident energy is increased,the vibration of atoms on the deposited surface is intensified and some atoms on the surface of the film jump,forming non-thermal diffusion,reducing the defects of TiN film,making the film continuous and complete,and finally presenting a lamellar growth.Then,the effects of different deposition parameters on the surface roughness and density of TiN film were studied.With the increase of incident energy and deposition rate,the surface roughness of TiN film decreased continuously.When the incident energy was 10 eV and the deposition rate was 4 Atom/Ps,the surface roughness of TiN film was 5.97 A,and the maximum decrease was 67.33%.The film density also increases with the increase of incident energy,and the maximum increase is 9.47%when the incident energy is 10 eV.(3)In order to deposit TiN film with high surface quality on the surface of H13 die steel and ensure the lamellar growth of TiN film,the deposition process of TiN on H13 steel was simulated by selecting higher incident energy.After TiN film is deposited,residual compressive stress is formed on the surface.With the increase of incident energy,the residual stress of TiN film decreases first and then increases.The surface roughness of TiN film decreases with the increase of incident energy.When the atomic incident energy is 10 eV,the surface roughness of TiN film is 9.01 A,and the maximum decrease is 5.77%.Finally,the magnetron sputtering experiment of TiN on H13 steel was carried out,and the accuracy of the above molecular dynamics model was verified by comparing the experiment and simulation. |
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