CN103469157B - Amorphous-based B-C-Mg ternary film and preparation method thereof - Google Patents

Abstract

The invention discloses an amorphous-based B-C-Mg ternary film and a preparation method of the ternary film, and belongs to the field of novel materials. Under the instruction of the cluster of a stable amorphous structure and a connection atom model, the factors of enthalpy of mixing, cluster structure and the like are taken into consideration, and the amorphous-based film with good comprehensive performance can be obtained when the atom percentages (at.%) of the ingredients of the film are determined as follows: 75-90% of B, 5-12.5% of C, and 5-12.5% of Mg. The performance indexes of the material are as follows: the hardness of the film: H=24-34GPa; the Young modulus: E=240-325GPa; the fracture toughness: KIC=1.2-3MPa*m1/2; and the coefficient of friction: COF=0.05-0.3. The preparation method disclosed by the invention has the following effects and beneficial effects that the amorphous film material which is uniform in structure, isotropous, high in hardness, high in toughness, and low in friction coefficient can be prepared within quite large range of ingredient tolerance, and the film can be used as an ideal material for a protective coating, and has potential application prospect in the industries of micro electro mechanical systems, blade molds, or surface treatment.

Description

A kind of amorphous base B-C-Mg ternary film and preparation method thereof

Technical field

The invention belongs to new material technology field, relate to a kind of amorphous base B-C-Mg ternary film with high rigidity, high tenacity and low-friction coefficient and preparation method thereof, this ternary film take B as main component, and equal proportion adds appropriate alloy element C, Mg simultaneously.

Background technology

In MEMS MEMS (micro electro mechanical system), LIGA(photoetching, electroforming and injection moulding) be the important technology manufacturing high-aspect-ratio micro element.To meet in LIGA technology production process the severe environment such as Lingao contact stress, high temperature, corrosion, most of LIGA microdevice is manufactured by Ni, Cu, Fe or other alloys, their performance will significantly reduce in these ambiances, even complete failure.Recent research finds [T.M.Mayer, J.W.Elam, S.M.George, P.G.Kotula, and R.S.Goeke, Appl.Phys.Lett.82, (2003) 2883] surface coated treatment technology is considered to a kind of effective ways relaxing these serious problems and then extend LIGA microdevice work-ing life.Desirable LIGA micro element manufacturing technology supercoat needs to possess the character such as high rigidity, high tenacity, low-friction coefficient, unreactiveness and high-temperature stable.Therefore develop the simple and supercoat with good over-all properties of preparation method and become a problem in science urgently to be resolved hurrily.Be simple and easy to like this system and the coating of excellent performance not only can be used for a MEMS (micro electro mechanical system), also can widen it and apply to other field, as knife mold surface, workpiece surface protection.

Before Two decades years, TiN is for coated material.TiN high rigidity, the excellent mechanical performances such as wear-resisting are its important factors as supercoat material application, but more inherent reason to be TiN material composition tolerance very large, there is wider process window.The hard TiN coating of B1 phase can both be prepared in very large Ti and N proportional band.The thermostability of TiN coating is poor, is easy to oxidation under high temperature, which has limited its utilization in micro electronmechanical industry or knife mold industry.Other a lot of materials are as DLC film, hydrophobic polymer coating, c-BN, TiN-SiN _x, C _xn _1-x, although there is high rigidity, wear-resisting, crystal condition be harsh owing to being formed, little between Composition Region, can only prepare in laboratory environments, be difficult to quantize to produce.In industrial production, situation is more complicated, and the ganoine thin film how preparation technology's window is large becomes a valuable problem.DLC film is developed the application for this aspect, but its residual compressive stress up to several GPa can cause the thick delamination reaching more than 100nm of film.More notably, DLC film can instability cause it at high temperature to apply after temperature is more than 723K.The hydrophobic polymer coating of low surface energy is expected to minimize stiction and frictional force, but makes it cannot improve the resistance to abrasion of LIGA micro element due to its relatively low hardness value, and when temperature slightly higher than ambient temperature they will lose efficacy.Little between c-BN Composition Region, formation condition is harsh, be difficult to prepare Emission in Cubic structure.Although the TiN-SiN of nano composite structure _xhardness can reach adamantine hardness, but it is very harsh to structural requirement, and need ratio and the configuration of accuracy controlling crystal phase and amorphous, just can reach the effect of structure hardening, the repetition rate of this material is very low in addition, is not suitable for large-scale industry and uses.Also have CN material, its theoretic calculating hardness exceedes adamantine hardness.Although experimentally also do not prepare this kind of material at present, in research process, prepare the CN non-crystalline material of excellent performance.The formation condition of non-crystalline material is relatively simple, has very large tolerance between Composition Region.If element contained by film is combined by strong interatomic force, excellent in mechanical performance can be prepared and the supercoat of process window large (wide between Composition Region).In addition, Structure of amorphous material is even, isotropy, can be used for complex-shaped micro element surface protection.Therefore, non-crystalline material becomes a kind of ideal chose of micro equipment supercoat in MEMS (micro electro mechanical system) or knife mold, workpiece surface protection film.

Select boride as research system, reason is that boron is a kind of electron deficiency non-metallic element, there is complicated one-tenth key environment, the material that various structures complexity, performance are special can be formed, high-abrasive material as hard in height, semi-conductor, superconductor, thermoelectric material, hydrogen storage material etc.As superhard material, the research of boron-rich boride crystal phase starts the concern being subject to people gradually.U.S. AMS tests the AlMgB of preparation ₁₄there is the features such as high rigidity, low-friction coefficient, unreactiveness.Its appearance excites the upsurge that boride is studied as mechanically resistant material more.The people such as Cook [Y.Tian, A.F.Bastawros, C.C.H.Lo, A.P.Constant, A.M.Russell, and B.A.Cook, Appl.Phys.Lett., 83 (2003) 2781] research finds that boride prepared by vacuum coating film equipment mostly is non-crystalline state further, and first proposes amorphous AlMgB ₁₄film applies to MEMS (micro electro mechanical system) as supercoat, opens the utilization field of boron amorphous compound new film.Recent first-principles calculations work shows, in a series of isospace group Imma boron rich compounds, and B ₁₂c ₂the theoretical hardness of Mg crystal phase has exceeded AlMgB ₁₄the theoretical hardness of crystal phase.Boron, carbon are all interacted by covalent linkage, and Cheng Jian is comparatively strong, is easily prepared into mechanically resistant material, and therefore amorphous B-C-Mg probably becomes another kind of desirable supercoat material.

The Forming ability of non-crystalline material there are differences, and reason is because its atomic arrangement exists ad hoc structure.Can be there is the high one-tenth branch of some Forming ability in amorphous, under this composition, structure is relatively stable, and performance goes out the features such as high rigidity, high strength, good tribological property, and has larger process window." cluster add connect atom " model is a kind of model utilizing the ideal composition point of accurate brilliant, the amorphous of the feature structure cluster design in amorphous.Utilize the desirable amorphous component point of this pattern layout B-C-Mg thin-film material, the excellent and large supercoat of process window of processability.

Summary of the invention

The object of this invention is to provide a kind of even structure, isotropy and there is the composition proportion of favorable comprehensive mechanical property ternary amorphous base B-C-Mg film, and provide the preparation technology of this film, solve the problem of micro element, knife mold and workpiece surface protective coating preparation difficulty.

Technical scheme of the present invention is: a kind of amorphous base B-C-Mg ternary film with high rigidity, high tenacity and low-friction coefficient, and it comprises B, C, Mg, the atomic percent of its thin film composition is (at.%), B:75-90; C:5-12.5; Mg:5-12.5.

The design realizing technique scheme is: select C, Mg be alloy element, reason be its crystal series rich B compound crystal mutually in there is the highest Theoretical Calculation hardness.And Structure of amorphous material is even, isotropy, and have on composition between larger forming region.If B-C-Mg material can be made non-crystal structure, so compared with obtaining isotropic uniform texture and excellent mechanical property in great achievement by stages simultaneously, and then the supercoat material with good over-all properties can be prepared.Have difficulties owing to directly studying non-crystal structure, people study non-crystal structure by the special nearest neighbour coordination polyhedron that can represent the local short-range order of amorphous usually." cluster adds and connects atom " model is the one in current many non-crystal structure descriptive models.This model thinks that any structure is made up of, with [cluster] (connecting atom) nearest neighbour coordination polyhedron and these two parts of connection atom of being present in cluster gap digit _xthe cluster formula of Unified Form describes [C.Dong, Q.Wang, J.B.Qiang, Y.M.Wang, N.Jiang, G.Han, Y.H.Li, J.Wu and J.H.Xia, Journal of Physics D:Applied Physics40 (15), R273-R291 (2007)].Cluster adds and connects atomic model by research crystal phase B ₇mg and B ₁₂c ₂short-range order structure in Mg carrys out approximate description non-crystal structure.By covalent bonds between B-C, form stable Cluster Structures [B-(B _6-x/2c _x/2)] (x≤2), add with the Mg of the atomic percent such as C and appropriate B after, thin film composition represents [B-(B to be formed as follows _6-x/2c _x/2)] (B _1-x/2mg _x/2) (x≤2), this composition is desirable amorphous component, has rational atomic configuration and stable electronic structure unit.Exist between Structure and Properties and be closely connected; stable structure often corresponds to excellent performance; therefore expect that in this larger Composition Region, (x≤2) preparation has the film of stable amorphous structure; and film has good over-all properties, can use as micro electro mechanical device coating for surface protection.

The described preparation method with high rigidity, high tenacity and low-friction coefficient amorphous base B-C-Mg ternary film adopts the following step, when case is implemented with laboratory conventional substrate material---silicon chip is for substrate material, in practical application, substrate manufactures the conventional Ni of LIGA micro element, Cu, Fe alloy or other alloy materials:

1. substrate cleaning: select Si substrate to be embodiment substrate material, by substrate first through acetone, alcohol and deionized water ultrasonic cleaning, the HF then putting into 5% soaks 1-2 minute, employing puts into vacuum chamber after blowing up a balloon and drying up;

2. magnetron sputtering equipment extracting vacuum: select purity be 99.9% graphite, purity be 99.9% magnesium and purity be that the boron amorphous of 99.9% is as sputtering target material, after target and substrate all put into vacuum chamber, mechanical pump is slightly evacuated to below 5Pa, then adopt molecular pump to carry out essence to vacuumize, vacuum tightness is evacuated to 8.0 × 10 ^-4pa;

3. after vacuum tightness reaches required high vacuum, be filled with argon gas and hydrogen gas mixture to proper pressure, allow target build-up of luminance, then regulate argon flow amount to 4.0sccm, hydrogen flowing quantity is to 4.0sccm, and operating air pressure is adjusted to 0.5Pa, boron target is radio-frequency sputtering, and power is 300-600W, and carbon target is also radio-frequency sputtering, power is 100-120W, magnesium target is d.c. sputtering, and power is 10-15W, and target-substrate distance is 8-12cm, the pre-sputtering time is 20 minutes, to remove target material surface oxide compound and other impurity;

4., after pre-sputtering, stop passing into hydrogen, argon flow amount is adjusted to 8.0sccm, and remove sputtering baffle plate, start sputter-deposited thin films, sputtering time is 120min, after sputtering, apparatus cools, to 30-60 DEG C, prepares required B-C-Mg ternary amorphous base film sample.

Effect of the present invention and benefit are: 1. the selection of B compound thin film alloys element and addition carry out under theoretical direction, consider the factors such as first-principles calculations, enthalpy of mixing and Cluster Structures, devise the boride film composition with desirable non-crystal structure; 2. in comparatively great achievement by stages, prepared B compound amorphous base film, comprised B, C, Mg, the atomic percent of its thin film composition is (at.%), B:75-90; C:5-12.5; Mg:5-12.5; 3. film has good over-all properties, and hardness is H=24-34GPa; Young's modulus is E=240-325GPa; Fracture toughness property K _iC=1.2-3MPa*m ^1/2; Frictional coefficient is COF=0.05-0.3; Surface roughness Ra=1-4nm, can use as micro electro mechanical device surface, the surperficial or workpiece surface supercoat of knife mold.

Embodiment

Specific embodiments of the invention are described in detail, still with the substrate material of traditional silicon substrate as embodiment below in conjunction with technical scheme.

Embodiment 1B _76.9c _11.7mg _11.4(at.%) film, composition comes from cluster formula [B-B ₅c] Mg

Step one, silicon substrate (Si) clean:

By monocrystalline silicon piece first through acetone, alcohol and deionized water ultrasonic cleaning, the HF then putting into 5% soaks 1-2 minute, and employing puts into vacuum chamber after blowing up a balloon and drying up.

Step 2, magnetron sputtering equipment extracting vacuum

Select purity be 99.9% graphite, purity be 99.9% magnesium and purity be that the boron amorphous of 99.9% is as sputtering target material, after target and substrate all put into vacuum chamber, mechanical pump is slightly evacuated to below 5Pa, and then adopt molecular pump to carry out essence and vacuumize, vacuum tightness is evacuated to 8.0 × 10 ^-4pa.

Step 3, pre-sputtering film

After vacuum tightness reaches required high vacuum, be filled with argon gas and hydrogen gas mixture to proper pressure, allow target build-up of luminance, then regulate argon flow amount to 4.0sccm, hydrogen flowing quantity is to 4.0sccm, and operating air pressure is adjusted to 0.5Pa, boron target is radio-frequency sputtering, power is 350W, and carbon target is also radio-frequency sputtering, and power is 120W, magnesium target is d.c. sputtering, power is 14.4W, and target-substrate distance is 10cm, and the pre-sputtering time is 20 minutes;

Step 4, sputtered film

After pre-sputtering, stop passing into hydrogen, argon flow amount is adjusted to 8.0sccm, and removes sputtering baffle plate, start sputter-deposited thin films, sputtering time is 120min.

Step 5, cooling

After sputtering, apparatus cools, to 30-60 DEG C, takes out ternary B film sample.

Step 6, analysis

ESCALAB250Xi type x-ray photoelectron power spectrum characterizes chemical composition and becomes key environment.In film, the existence of C-Mg key confirms cluster formula [B-(B _6-x/2c _x/2)] (B _1-x/2mg _x/2) reasonableness of (x≤2) atomic configuration.The atomic percent of B, C, Mg tri-kinds of elements is respectively 76.9at.%, 11.7at.%, 11.4at.%.Be non-crystal structure in conjunction with X-ray diffraction (Discover D8) and transmission electron microscope (JEM-100CX II) characterized by techniques membrane structure.MTS-XP Nanoindentation characterizes hardness and the elasticity of film, ensures that depth of indentation is less than 15% of thickness to ensure to eliminate matrix effect in measurement.Test result is hardness is H=24GPa; Young's modulus is E=240GPa.Frictional coefficient is by the test of CETR UMT-2 type frictiograph, and experiment condition is cut test under 30 ~ 32GPa silicon nitride abrading-ball 5N load, and recording film friction coefficient is COF=0.05.Toughness is characterized indirectly by impression behavior under research Vickers' hardness, its fracture toughness property (K _{i C}) relevant to radial cracking length (c):

$K_{\mathrm{IC}}=\mathrm{\δ}{\left(\frac{E}{H}\right)}^{1/2}\left(\frac{P}{c^{3/2}}\right)$

Here P is indentation load, and E, H are respectively Young's modulus and the hardness of film, and δ is the empirical constant (δ of standard diamond Vickers indenter is 0.016) relevant to impression.Fracture toughness property test result is 1.2MPa*m ^1/2.New View-5022 (Zygo, USA) characterizes the surfaceness of film, Ra=2nm.

Embodiment 2B _85.1c _8.7mg _6.2(at.%) film, composition comes from cluster formula [B-B _5.5c _0.5] B _0.5mg _0.5

Step one, silicon substrate (Si) clean:

The cleaning of Si substrate is consistent with the step one in embodiment 1.

Step 2, magnetron sputtering equipment extracting vacuum

Magnetron sputtering equipment extracting vacuum is consistent with the step 2 in embodiment 1.

Step 3, pre-sputtering film

Boron target power is set to 600W, and other pre-sputtering thin-film process are consistent with step 3 in enforcement 1.

Step 4, sputtered film

Sputtered film process is consistent with the step 4 in embodiment 1.

Step 5, cooling

Cooling step is consistent with the step 5 in embodiment 1.

Step 6, analysis

With implementing step 6 in 1, in film, the atomic percent of B, C, Mg tri-kinds of elements is respectively 85.1at.%, 8.7at.%, 6.2at.%.Membrane structure is amorphous/nanocrystalline composite structure, and nanocrystal phase diameter is about 5nm, a small amount of Dispersed precipitate.H=34GPa、E=350GPa；COF=0.3；KIC=3.0MPa*m ^1/2；Ra=3nm。

By above-mentioned analysis, meet desirable amorphous component cluster formula [B-(B _6-x/2c _x/2)] (B _1-x/2mg _x/2) (x≤2) time, even structure, isotropic desirable amorphous based film material can be prepared.Film performance is relevant to Boron contents, under the prerequisite keeping C/Mg ratio ≈ 1, regulates film performance, obtain the supercoat material with good over-all properties by the content changing B element in film.

Claims (2)

1. an amorphous base B-C-Mg ternary film, is characterized in that: it comprises B, C, Mg, the atomic percent of its thin film composition is (at.%), B:75-90; C:5-12.5; Mg:5-12.5.

2. a preparation method for amorphous base B-C-Mg ternary film, is characterized in that the following step:

1. substrate cleaning: select Si substrate to be embodiment substrate material, by substrate first through acetone, alcohol and deionized water ultrasonic cleaning, the HF then putting into 5% soaks 1-2 minute, employing puts into vacuum chamber after blowing up a balloon and drying up;

2. magnetron sputtering equipment extracting vacuum: select purity be 99.9% graphite, purity be 99.9% magnesium and purity be that the boron amorphous of 99.9% is as sputtering target material, after target and substrate all put into vacuum chamber, mechanical pump is slightly evacuated to below 5Pa, then adopt molecular pump to carry out essence to vacuumize, vacuum tightness is evacuated to 8.0 × 10 ^-4pa;

3. after vacuum tightness reaches required high vacuum, be filled with argon gas and hydrogen gas mixture to proper pressure, allow target build-up of luminance, then regulate argon flow amount to 4.0sccm, hydrogen flowing quantity is to 4.0sccm, and operating air pressure is adjusted to 0.5Pa, boron target is radio-frequency sputtering, power is 300-600W, and carbon target is also radio-frequency sputtering, and power is 100-120W, magnesium target is d.c. sputtering, power is 10-15W, and target-substrate distance is 8-12cm, and the pre-sputtering time is 20 minutes;

4. after pre-sputtering, stop passing into hydrogen, argon flow amount is adjusted to 8.0sccm, and removes sputtering baffle plate, start sputter-deposited thin films, sputtering time is 120min, and after sputtering, apparatus cools, to 30-60 DEG C, takes out B-C-Mg ternary film sample.