Preparation Process Of Diamond Nano Structure Arrays By MPCVD

Diamond nanostructure arrays have attracted more and more attention due to its special physical and chemical properties and low dimensional effect under the nano scale.They have deep application prospects in microelectronics,machinery,electrochemistry,bionics and so on.In this paper,the preparation of diamond nanostructure arrays is carried out,and nanocrystalline diamond(NCD)films are deposited on silicon and titanium substrates by microwave plasma chemical vapor deposition(MPCVD)device.Then nanostructures are fabricated by reactive ion etching(RIE)technology,and the effect of process parameters on nanostructures on the surface of films is studied.The main work and achievements of this paper are as follows:(1)The sputtering rate of carbon atoms in diamond films when suffering from Ar ions bombardment was simulated by SRIM software,results showed the increase of Ar ions energy lead to the increase of incident depth of ions and frequence of collision cascade.So,the sputtering rate of diamond carbon atom increased and the sputtering rate reached maximum when Ar ions energy reached 250 eV.Also,the sputtering rate followed the same trend with the increase of the incident angle and when the angle rose to about 70~75° the sputtering rate reached maximum.While continued to increase the incident angle,the sputtering rate dropped off reversely.(2)The NCD films were deposited on silicon substrate and the titanium substrate respectively by MPCVD technology.It was found that the NCD film on silicon substrate exhibited cluster morphology and grew densely which was a high quality NCD film.But the NCD film on titanium substrate exhibited "cauliflower-like" clusters,formed from large agglomerates.The film grew compactly with high quality.(3)The RIE processes of NCD films deposited on silicon substrates with maskless and mask were carried out.In the etching process with maskless,the effect of etching time,proportion of argon and substrate bias on the nanostructures was studied,the results showed the density and size of nanocones on surface of films increased and the integrity also improved with the etching time,proportion of argon and substrate bias increasing.However,if the proportion of argon was too high,no regular nanostructures formed.The results of the etching process with mask showed that the higher the concentration of diamond micro powders,the denser the distribution of nanocones and the more the agglomeration,finally regular nanostructures hardly formed.As the size of micro powders increased,nanostructures on surface became larger and evolved from nanocones into micron convex plates.Even nanocones appeared on the upper surface of the convex plate.With the prolongation of the gold spraying time,nanocones on films gradually became disordered convex,and even nanostructures disappeared.(4)The RIE technique was used to systematically study the etching process of NCD films deposited on titanium substrates,which included the substrate bias,gas pressure and gold spraying time.It’s found that with low substrate bias high density small nanocone arrays were prepared,while high density large nanocone arrays were gotten with high bias voltage.High quality nanocone arrays formed at low gas pressure.The higher the gas pressure,the smaller the size and the worse the consistency of nanocones.Even gas pressure was excessive,surface morphology of films became irregular.When the gold spraying time is short,high aspect ratio nanocones formed under the action of small gold masks.While the gold spraying time was more than 10 s,uniformly distributed convex plates with a size of about 500 nm formed.