CN106884141A - A kind of Ti2The preparation method of AlC MAX phase films - Google Patents

Abstract

The invention belongs to new material technology preparation field, specially Ti₂The preparation method of AlC MAX phase films.Using rf magnetron sputtering by the way of, sputtering element ti and Al targets are solid composition target to the present invention, and the area ratio of solid target is adjusted by calculating elements sputtering raste and the film chemical element ratio that measures, so as to obtain preferable chemical element ratio in film；Using the hydride C of C₂H₂Gas improves the activity of C element as C element target, the gas Ar gas and C being passed through by control₂H₂The uninterrupted and ratio of gas, make the final element ratio in film reach close to Ti₂The chemical element ratio of AlC.The present invention by changing substrate temperature, the parameter such as sedimentation time and sputtering power, can more accurately adjustment prepares the thickness of film, crystallite dimension, so as to obtain thickness and the controllable pure phase high-quality polycrystal film of crystallite dimension.

Description

A kind of Ti2The preparation method of AlC MAX phase films

Technical field

The invention belongs to new material technology preparation field, and in particular to a kind of preparation of composite ceramic material MAX phase materials Method.

Background technology

Nanometer laminated structure hexagonal crystal system novel composite ceramic material MAX phase materials（M_n+1AX_nAbbreviation, M be element week The low period zones transition metal of phase table, A is the 3rd or the 4th major element, and X is carbon or nitrogen）, due to same in crystal structure When exist class ceramics phase structure MX phases and the MA metal phases of metalloid phase structure, it is had concurrently as a kind of new ceramic material Many excellent properties of ceramics and metal, such as heat-resisting quantity, good electrical and thermal conductivity performance, corrosion-resistant and excellent machinery Processing characteristics, simultaneously because this new material has intrinsic nano lamellar crystal structure, this layer structure can make material With a kind of anisotropic conductive characteristic, this causes that MAX phase materials are possible to be used in special microelectronics system. In recent years, find that this material can be with the neutron irradiation of resistance to ion, with extremely strong injury repair ability, it is considered to be forth generation again Fission pair and the candidate structure material of following controllable nuclear fusion reactor.In view of many excellent characteristics of MAX phase materials and wide Wealthy application prospect, at present in the world it is numerous country and mechanisms（Including China, the U.S., Australia is Japanese, Sweden etc.）Accumulate Pole conducts a research.

Ti₂AlC is representative a member in MAX phase material Ti-Al-C systems, its have it is more excellent anti-oxidant, Corrosion-resistant and radiation-resistant property.Ti₂AlC is typically to come synthesizing block material, such as pressureless sintering method, hot pressing by block synthetic method Method and reactive hot isostatic pressing (RHIP) method etc..But the synthesis of block materials cannot almost obtain pure phase, the often band in the material for preparing There is inevitable Ti₃AlC₂Phase and metal carbides（TiC_x）Or other some alloys（TiAl）Dephasign, while also existing The uneven phenomenon of crystallite dimension.The synthesis of block materials needs harsh reaction condition, such as high temperature（More than 1400 °C）And height Pressure（5-50MPa）.Because this kind of advanced composite material (ACM) is general good and bad (mutually pure to evaluate it with grain size with the purity of phase constituent Degree is higher, and the quality of the more big then material of crystal grain is higher), meanwhile, the presence of impurities phase is given to material Quality Research band in material Come unfavorable, therefore body material does not reach expected goal in research to a certain extent.Since two thousand two, MAX phase materials are got over Prepare in the form of a film to study its potential some application come more being attempted（Such as inoxidizability and lubrication are protected Shield coating etc.）And it is rapid to be in progress.Some high-purity monocrystalline Ti can be prepared at present₂AlC phases film and continuous Improvement preparation method and process conditions with seek simpler efficient approach prepares high quality thin film.

MAX phase thin-film material preparation methods mainly have chemical vapour deposition technique and magnetron sputtering deposition method.Because magnetic control splashes Penetrating coating method can obtain that adhesive force is strong under conditions of far below body materials synthesis temperature, and thickness and crystallite dimension are controllable , the high quality thin film of densification, thus the method as most MAX phase film preparations are applied at present.For Ti₂For AlC, The use of more sputtering methods is at present in Al₂O₃（0001）Using the discrete target of solid or the d.c. sputtering of composition target on substrate. To obtain high-quality single crystal epitaxial film, it is necessary to grow one layer of thin Seed Layer, such as Ti or TiC on sapphire substrates_x（There is text Chapter shows it can also is TiN_x）, then epitaxial growth goes out monocrystal thin films on the seed layer.Although this method can obtain higher The monocrystal thin films of quality, but on the one hand it is subsequently in the X-ray diffraction measurement of film crystal quality that the problem for existing is Cannot be by TiC that may be present in Seed Layer and film_xImpurity is distinguished, and this will lead to not judge whether crystal is pure phase, separately On the one hand it is that Seed Layer can be to other properties such as resistance of film, the measurement of thermal conductivity brings influence, and this method needs are right Substrate adds temperature higher（Typically at 900 DEG C or so）.In view of commercial Application aspect, one layer of Seed Layer and deposition high are grown Temperature can undoubtedly increase technology difficulty and cost, but if not using this pattern of the above, under same experiment condition for example Directly on substrate（Sapphire or MgO）Magnetron sputtering deposition film or the method using other chemical vapor depositions, obtain Film often contain dephasign such as TiC and TiAl alloy, the quality of crystal is very poor, crystal grain also very little.It is anti-using radio frequency at present The method of magnetron sputtering is answered to prepare the pure phase Ti of high-quality₂The technical method of AlC films is still near barren state.

The content of the invention

Research background and film preparing technology based on the above, can be more accurate it is an object of the invention to provide one kind Control thickness, the Ti of crystallite dimension of MAX phase thin-film materials₂The preparation method of AlC MAX phase films.

The Ti that the present invention is provided₂The preparation method of AlC MAX phase films, using radiofrequency magnetron sputtering technology, uses reaction gas Body C₂H₂As C element target, can be in lower temperature（600℃-710℃）MgO（100）High-quality pure phase is grown on matrix Polycrystalline Ti₂AlC films.Comprise the following steps that：

First, sputtering target and substrate are equipped

The present invention uses the mode of rf magnetron sputtering, and sputtering element ti and Al targets are solid composition target, and combination is In disc high-purity Ti target（99.99%）Upper uniform placement 4-5 pieces press 15 ± 1 ° of fan-shaped high-purity Al pieces（99.99%）.It is this solid The advantageous combination of bluk recombination target is simple assembling, and constituent content is convenient to be adjusted.It is anti-in order to improve C element participation sputter deposition process Ti should be generated₂The chemism of AlC, the present invention uses the hydride acetylene of C（C₂H₂）As C element target.Only needed in deposition process By high-purity C₂H₂Gas（99.99%）It is passed through in working vacuum chamber.Because H element at relatively high temperatures will be from adsorption material Discharged quickly in material, therefore the film containing H element will not be deposited under the substrate temperature higher than 600 DEG C.Similarly, since C₂H₂Reactivity is big, is control C element ratio in the film,（By flowmeter）The working gas Ar gas that is passed through of control and Reacting gas C₂H₂Flow-rate ratio（About 200：（1-3））.Substrate is magnesia MgO（100）, it is equipped in directly over sputtering target, the back of the body Heater strip is pressed close in face；

2nd, working chamber is vacuumized

Base vacuum should be less than 3*10^-5Pa；

3rd, pre-sputtering

Start build-up of luminance sputtering under the pressure of 5 ± 0.5Pa after being passed through working gas, glow discharge sputtering starts rear operating pressure scope drop It is 0.1-0.2Pa, keeps operating power pre-sputtering 10-30 minutes, removes target surface oxide layer；

4th, sputtering sedimentation plated film

Deposition power is 70-80W, and substrate adds back bias voltage 40-60V.Substrate heating temperature scope is 600-710 DEG C.The thickness of film Degree is different according to sedimentation time difference.The film for finally giving its each element content should be reached close to Ti₂The desirable chemical of AlC Element ratio.

Brief description of the drawings

Fig. 1 is substrate temperature for 600 DEG C, 615 DEG C, 630 DEG C, 665 DEG C and 710 DEG C of film omits incident X-ray diffraction figure Spectrum.

Fig. 2 is for substrate temperature（a）615 DEG C,（b）630 DEG C,（c）665 DEG C and（d）Film surface electronics at 710 DEG C is swept Face microscope photograph.

Fig. 3 substrate temperatures be 710 DEG C under the conditions of thickness be（a）（b）700nm, (c)（d）The surface of 1000nm and section SEM Figure.

Specific embodiment

By MgO substrates before experiment（Size is 1cm × 1cm, thickness 1mm）It is put into the beaker for fill absolute ethyl alcohol with ultrasound Ripple is cleaned 10 minutes, substrate is taken out and is wiped its shiny surface and is dried up with high-purity compressed air so that the clean nothing of substrate shiny surface Pollution.Afterwards rapidly by substrate fixed placement in the vacuum chamber heater strip lower section.Heater strip can be heated to substrate, leaned on Nearly substrate position is placed with thermocouple sensor and carrys out real-time monitoring and regulate and control substrate heating temperature by temperature controller.Work When, substrate is -52 (± 5) V added with the back bias voltage relative to ground.Solid composition target is placed in radio-frequency electrode, and substrate distance It is 60mm.The vacuum in vacuum chamber is extracted into less than 3 × 10 by mechanical pump and turbomolecular pump^-5 Pa.Inhaled in vacuum chamber wall With hydrone, constantly can be desorbed out during vacuumizing, the O atom in hydrone in film deposition process will Deposition in the film, influence is produced on film, in order to reduce the introducing of foreign atom in film and improve the vacuum of chamber, Need to toast chamber during vacuumizing, usually 200^oToasted 2 hours under C.

During sputter coating, the working gas Ar being passed through（99.99%）The flow of gas is 15.0 ± 0.01 sccm, C₂H₂ （99.99%）Gas flow is 0.075 ± 0.002sccm, appropriate to close molecule pump valve, operating pressure control 0.20 ± 0.02Pa.Due to C₂H₂The flow of gas is relative to the poor hundred times of Ar gas phases, it is therefore desirable to which high-precision flowmeter comes to C₂H₂Gas Body flow carries out accuracy controlling, and the otherwise influence to the C element in film can be larger.By change sputtering power can control it is thin The sedimentation rate of film, but too small sputtering power can cause that the quiet time increases, and excessive sedimentation rate can cause the temperature of target Rise too fast, aluminium flake can occur certain thawing, and with the change of the energy, ratio for sputtering Elements Atom, by further shadow Ring film chemical component.Eventually through a series of experiments, the suitable sputtering power that we select is 70 ~ 80W.By changing base The heating-up temperature of piece, can obtain under different temperatures the film of corresponding difference qualities and can study Radiofrequency muti-hook probe Method depositing Ti₂The minimum temperature of AlC films.Sedimentation time increase can increase the thickness of film and the size of crystal grain（Mainly expand The time of dissipating is abundant）, the film of different-thickness and different grain sizes is can obtain by changing the quiet time.

The chemical composition analysis for preparing film use rutherford back scattering analysis（RBS）, phase constituent in film is divided Analysis and the observation of crystal quality use slightly incident X-ray diffraction analysis（GIXRD）, the direct observation to film microscopic appearance We use SEM（SEM）Method.

For example, we have obtained the quiet time for 60 minutes by changing the heating-up temperature of substrate from 600 DEG C to 710 DEG C Under crystal phase constituent and quality variation relation such as table 1 and Fig. 1.The summary incident X-ray diffraction collection of illustrative plates of film shows in Fig. 1, Under 600 DEG C of substrate temperature, only there are two very weak Ti in diffracting spectrum₂The peak of AlC phases, illustrates base of the film at 600 DEG C Ti is just initially formed under temperature₂AlC phases, but this temperature can't make deposition and atomic, and especially Al atoms overcome potential barrier And lattice position is fully diffused to, the result thus brought is crystal quality not high（It is mostly in solid solution state）.With Substrate temperature raise, from 615 DEG C to 710 DEG C sample Ti₂AlC phase diffraction peak intensities are significantly improved, and are occurred in that almost complete The peak corresponding with standard powder diffraction in portion, and the diffraction maximum relative intensity change of different temperatures is not notable, and this is just illustrated The good polycrystalline Ti of crystallinity can be prepared more than 615 DEG C₂AlC films.By the observation to film surface and section, such as Fig. 2, we can see that sample thin film is substantially all the pattern that dense multicrystalline is presented, the direction of growth of crystal grain is relative matrix method Mixed and disorderly distribution on line incline direction（This point is in routineθ-2θDo not occur the diffraction relative to base plane in XRD spectrum The phenomenon at peak can determine）.With the rising of substrate temperature, the boundary dimensions of crystal grain is significantly increased, and illustrates that higher temperature can be with Increase is splashed to the diffusion free energy of matrix surface particle and then promotes further growing up for crystal grain.Sample at 630 DEG C and 710 DEG C A unknown faint peak is respectively occurred in that in product X ray diffracting spectrum, is compareed with the sample component table of table 1, can be construed to due to The deviation of chemical constituent and the impurity that brings.GIXRD collection of illustrative plates at a temperature of other does not occur the diffraction maximum of other phases, and Its component all meets standard Ti₂AlC chemical constituents ratio, illustrates pure phase Ti₂The preparation of AlC films needs its component proportion to meet mark The condition of quasi- stoicheiometry.

By changing sedimentation time, the film of different-thickness can be obtained.Fig. 3 for sedimentation time be respectively 120 minutes and Under 180 minutes substrate temperature be 710 DEG C of Sample Scan electron microscope pictures.With sedimentation time for 60 minutes samples compare, It can be seen that the grain boundary size that sedimentation time is the sample of 120 minutes and 180 minutes is significantly increased, sedimentation time is illustrated Increase can bring further growing up for crystal grain.It can be seen that grain shape is in obvious six sides layer structure from SEM figures, and The direction of growth of crystal grain is mostly in a certain angle with matrix normal, and this inclined growth pattern can be regarded as crystal film and be A kind of result of common epitaxial growth is reached, the generally this direction for inclining growth is the metal carbides being initially formed by deposition （Namely Seed Layer）Come what is determined, another reason is can to reach minimum interface freedom by inclining the pattern of growth Can, it is easier to the growth of film.

Generally speaking, Ti is prepared using the method for this reaction magnetocontrol sputtering₂AlC MAX phase films, by changing matrix The parameters such as temperature, sedimentation time and sputtering power, can more accurately adjustment prepares the thickness of film, crystallite dimension so that Controllable to thickness, the controllable pure phase high-quality polycrystal film of crystallite dimension, this preparation and flow of research to MAX phase films is right Following Ti₂The further research and application of AlC phases are significant.

Film chemical component and thickness under the different deposition temperatures of table 1（Error does not include cross-section error）

。

Claims (2)

1. a kind of Ti₂The preparation method of AlC MAX phase films, it is characterised in that use radiofrequency magnetron sputtering technology, use reaction gas Body C₂H₂As C element target, in the MgO that temperature is 600 DEG C -710 DEG C（100）Pure phase polycrystalline Ti is grown on matrix₂AlC films； Comprise the following steps that：

Step one, equipment sputtering target and substrate

It is solid composition target to sputter element ti and Al targets, combination is the uniform placement 4-5 pieces on disc high-purity Ti target By 15 ± 1 ° of fan-shaped high-purity Al pieces, using C₂H₂As C element target；By high-purity C during deposition₂H₂Gas is passed through working vacuum chamber In room；Working gas Ar gas and reacting gas C that control is passed through₂H₂Flow-rate ratio be 200：（1-3）, substrate is magnesia MgO （100）, it is equipped in directly over sputtering target, heater strip is pressed close at the back side；

Step 2, working chamber are vacuumized

Base vacuum should be less than 3*10^-5Pa；

Step 3, pre-sputtering

Start build-up of luminance sputtering under the pressure of 5 ± 0.5 Pa after being passed through working gas Ar gas, glow discharge sputtering starts rear operating pressure Scope is reduced to 0.1-0.2Pa, keeps operating power pre-sputtering 10-30 minutes, removes target surface oxide layer；

Step 4, sputtering sedimentation plated film

Deposition power is 70-80W, and substrate adds back bias voltage 40-60V；Substrate heating temperature scope is 600-710 DEG C；The thickness of film Depending on degree is according to sedimentation time；Each element content should be reached close to Ti in finally making film₂The desirable chemical element ratio of AlC.

2. Ti according to claim 1₂The preparation method of AlC MAX phase films, it is characterised in that sputtering sedimentation plated film When, the flow of the working gas Ar gas being passed through is 15.0 ± 0.01 sccm, C₂H₂Gas flow is 0.075 ± 0.002sccm, is fitted When molecule pump valve is closed, operating pressure is controlled in 0.20 ± 0.02Pa.