Background technology
Reactive sputtering method is a kind of conventional method preparing metal compound film, its operation principle beCertain density reacting gas it is passed through so that metal ion is during sputtering and reacts during sputteringGas reaction, thus the compound required for obtaining.
Traditional reaction sputtering system structure includes: vacuum chamber, shielding power supply, vacuum pump group system, crystalline substanceCircle transmission system, gas circuit and control system etc..Wafer carrier it is provided with sputtered for placing in vacuum chamberWafer.Be provided with target device at the top of vacuum chamber, this target device include place target pedestal,The strong magnet array of the rotation required for the cathode targets being connected on pedestal and magnetic control sputtering system.SputteringTechnique is carried out under certain vacuum environment, when being passed through a certain amount of argon in vacuum chamber, and at negative electrode andPlus voltage between anode, then can produce gas self-excited discharge, this charged gas ion adding at electric fieldThe lower bombarding cathode target of speed so that target metal ionization to be deposited on anode by electric field acceleration (to be sputteredWafer) on.If period is passed through reacting gas such as O2、N2Deng, these gases will be at plasmaBecome ion under bombardment, thus react with metal ion, wafer is formed required metal compoundThing thin film.The composition of the metal compound film that reactive sputtering is generated is divided by the reacting gas in vacuum chamberPressure (i.e. the concentration of reacting gas) determines, especially some is had the metallic compound of multiple valence state, itsTopmost valence state is dependent on being passed through the uninterrupted of reacting gas.
There is a problem the biggest in existing this reaction sputtering system, it may be assumed that for some electric conductivity ratiosPoor compound-material, along with the increase of reacting gas, on a part of compound meeting backwash to target, shapeBecome the thin film that one layer of electric conductivity is poor, this reduce sputtering current, reduce sputtering rate.Sputtering electricityThe reduction of stream promotes reacting gas dividing potential drop to increase further, thus the compound that result in more conduction difference is thinFilm is formed on target, so that sputtering current reduces further, forms vicious cycle, ultimately results in sputteringTechnique stops.So using traditional reaction sputtering system to have sizable limitation, even cannot obtainThe thin film of required metal state composition.
Below to prepare vanadium dioxide (VO2) further illustrate as a example by thin film and use tradition reaction sputtering systemLimitation.Generally target uses pure vanadium metal target, utilizes argon (Ar) as carrier gas, then is passed through O2MakeFor reacting gas.At certain temperature and plasma sputtering environment, reacting gas O2Vanadium with ionic stateIn conjunction with, the oxide forming vanadium is deposited on wafer.Tetravalent oxide vanadium dioxide (the VO of vanadium2) in room temperatureUnder there is higher resistance coefficient (Temperature Coefficient ofResistivity is called for short TCR) and relativelyLow resistivity, is a kind of splendid material making micrometer bolometer, so the main mesh of usual techniqueBe obtain highly purified VO2Thin film.
Fig. 1 illustrates and above-mentioned prepares vanadium dioxide (VO2) schematic diagram of an experimental result of thin film.ExperimentIn, according to certain time interval, inject different reaction gas flows in the different time respectively.Just openThe time begun, reacting gas is zero, and the corresponding material sputtered out is pure vanadium metal, corresponding chemical valencePosition is 0 valency；After 10th second, change reaction gas flow, sputter out for monovalence barium oxide, insteadShould result stablize；After 20th second, again changing reaction gas flow, sputter out aoxidizes for bivalent vanadiumThing, reaction result is stable；By that analogy；But after the 40th second, change reaction gas flow, sputteringResult is the most stable, and time initial, chemical composition is tetravalent vanadium compound, increases over time, several seconds withRear compound just becomes the pentavalent oxide of vanadium, i.e. vanadic anhydride.As can be seen here, traditional sputtering is usedMethod can not obtain high-quality tetravalence barium oxide, i.e. VO2Thin film.Therefore, tradition reactive sputtering workThe sputtered film Composition Control difficulty of skill, the even thin film of some special component cannot sputter.
Summary of the invention
The present invention is directed to the problems referred to above, it is provided that a kind of reaction sputtering system controlled based on vibrating type reacting gas,This reaction sputtering system can sputter the metal compound film of stable components.
According to technical scheme: a kind of reaction sputtering system controlled based on vibrating type reacting gas,The reaction gas pipeline including vacuum chamber and being connected with described vacuum chamber respectively and gas-carrier pipeline, describedRelative anode wafer carrier and cathode targets it is provided with in vacuum chamber；Described reaction sputtering system also includesGas Flowrate Control System, described gas Flowrate Control System includes computer, flow controller, reaction gasWeight effusion meter and carrier gas mass flowmenter, described reacting gas mass flowmenter and described carrier gas quality streamGauge is separately positioned in described reaction gas pipeline and described gas-carrier pipeline, described reacting gas mass flowMeter and described carrier gas mass flowmenter are connected with described flow controller respectively, and described flow controller is with describedComputer is connected；Described computer controls described reacting gas mass flowmenter by described flow controller,Making the reaction gas flow entering described vacuum chamber from described reaction gas pipeline is periodically concussion flow.
Described anode wafer carrier is arranged at the bottom of described vacuum chamber, and described cathode targets is arranged at describedThe top of vacuum chamber, described reaction gas pipeline and described gas-carrier pipeline are respectively arranged at described vacuum chamberSidewall on.
The exit position of described reaction gas pipeline is corresponding with described cathode targets, going out of described gas-carrier pipelineMouth position is corresponding with described anode wafer carrier.
Described reacting gas is oxygen, and described carrier gas is argon, and described cathode targets is 5N pure vanadium target.
The method have technical effect that: the present invention is provided with gas Flowrate Control System, make entrance vacuumThe reaction gas flow of chamber is periodically to shake flow, so that whole sputter procedure achieves dynamicallyStable, and and then stablize the metallic compound composition required for obtaining.
Detailed description of the invention
Below in conjunction with the accompanying drawings the detailed description of the invention of the present invention is further described.
In Fig. 2, including vacuum chamber 1, shielding power supply 2, cathode targets 3, anode wafer carrier 4, anti-Answer gas piping 5, gas-carrier pipeline 6, computer 7, flow controller 8, reacting gas mass flowmenter 9,Carrier gas mass flowmenter 10 etc..
As in figure 2 it is shown, the present invention is a kind of reaction sputtering system controlled based on vibrating type reacting gas, bagInclude vacuum chamber 1 and gas Flowrate Control System.
Relative anode wafer carrier 4 and cathode targets 3 it is provided with in vacuum chamber 1.Anode wafer carrier 4Being arranged at the bottom of vacuum chamber 1, cathode targets 3 is arranged at the top of vacuum chamber 1, cathode targets 3It is connected with shielding power supply 2.
Coupled logical reaction gas pipeline 5 and gas-carrier pipeline it is respectively arranged with on the sidewall of vacuum chamber 16.The exit position of reaction gas pipeline 5 is corresponding with cathode targets 3, the exit position of gas-carrier pipeline 6 withAnode wafer carrier 4 is corresponding.
Gas Flowrate Control System include computer 7, flow controller 8, reacting gas mass flowmenter 9 andCarrier gas mass flowmenter 10.Reacting gas mass flowmenter 9 and carrier gas mass flowmenter 10 are separately positioned on insteadAnswer in gas piping 5 and gas-carrier pipeline 6, reacting gas mass flowmenter 9 and carrier gas mass flowmenter 10 pointsNot being connected with flow controller 8, flow controller 8 is connected with computer 7.Computer 7 is by flow controlDevice 8 processed controls reacting gas mass flowmenter 9, makes to enter the reaction of vacuum chamber 1 from reaction gas pipeline 5Gas flow is periodically to shake flow.
Prepare vanadium dioxide (VO2) thin film time, reacting gas is oxygen, and carrier gas is argon, cathode targets 3For 5N pure vanadium target.
The technological process that the employing present invention carries out reactive sputtering is as follows:
1, vacuum chamber 1 is first extracted into required base vacuum by vacuum system, such as 10E-7Torr.
2, computer 7 controls carrier gas mass flowmenter 10 by flow controller 8, is passed through the load of certain flowGas, such as the argon of 35sccm, and makes the vacuum of vacuum chamber 1 reach required vacuum, as5E-3Torr。
3, computer 7 controls reacting gas mass flowmenter 9 by flow controller 8, the reaction gas being passed throughBody flow is not a definite value, but at flow F1 and F2 set according to regular hour periodic vibrationValue.The control process of whole reacting gas is as it is shown on figure 3, be described as follows: in the T0 time by reacting gas streamAmount is set to F1, in the T1 time, reaction gas flow is set to F2, then is set by reaction gas flow in the T2 timeFor F1, by that analogy.Wherein the T0-T1 time is initial time, for TBegin；The T1-T2 time is TF2, tableIt it is now time during F2 flow；The T2-T3 time is TF1, show as time during F1 flow, by that analogy,Form concussion.
4, shielding power supply 2 is opened in the T1 time, until it reaches the film thickness of needs.
One important difference of the present invention and traditional reaction sputtering system is the stream of the reacting gas of the present inventionAmount is a flow periodically shaken, and unconventional firm discharge.The present invention can solve the problem that tradition is fixingThe instability problem that reaction gas flow brings, its principles illustrated contained is as follows: when reaction gas flow isF1, owing to partial reaction thing backwash causes reactant valence state to increase, reactive state tends to unstable；But it is the shortestIn time, gas flow becomes F2, causes reactant valence state to reduce.The conversion of this high-frequency flow makes on the contraryObtain whole sputter procedure and achieve dynamic stable.This is just as the wheelbarrow of acrobatics, if wheelbarrowMotionless, performance people is difficult to maintain and balances: if but perform people and do not stop the most quickly to move, just it is easy toRealize the balance of wheelbarrow.
Use the present invention reaction sputtering system, by adjust reacting gas two preset value F1 and F2 withAnd conversion time cycle TF1And TF2, it becomes possible in reactive sputtering process, stablize the metallization required for obtainingPolymer component.
It it is below comparative experimental example
Use the Endura5500 model vacuum sputtering system of Applied Materials (Applied Materials) companyDuring system sputtered film, as a example by sputtering power DC600W.The target used in experiment is 5N pure vanadium target,Carrier gas is Ar, flow 35sccm, and reacting gas is oxygen, and target product is tetravalence barium oxide VO2。When oxygen flow is less than critical point 5.5sccm when, such as during 5.4sccm, the thin film composition sputtered outPredominantly two valency barium oxide VO.After tested, its thin film specific insulation is of about 0.001 Ω cm.Work as oxygenWhen throughput equals or exceeds critical point 5.5sccm, even if oxygen flow is highly stable, sputtering current also can be anxiousFalling sharply low, the thin film specific insulation finally sputtered out is more than 1000 Ω cm, through material composition analysis, itsIt is mainly composed of V2O5.Test result indicate that, if this vacuum sputter system is not transformed, be to sputterGo out the oxide VO of the vanadium of+4 valencys2, volume resistance is the thin film of 1 Ω about cm.
According to the present invention, the vacuum sputter system of this Endura5500 model is transformed, adds thisThe gas Flowrate Control System of the cuff computer in bright.By computer programming, reaction gas flow is setSwitch between 7.0sccm and 1.5sccm, cycle TF1And TF2It is respectively 1 second and 1.4 seconds, sputtering powerFor 600W, total time is 400 seconds.Through measuring, its sputtering thickness isSpeed is substantiallyIt is mainly composed of VO2, specific insulation, at 1.53 Ω cm, at room temperature has a TCR that comparison is high, and about-2.0%(negative sign represents that its resistivity increases with temperature and diminishes), property of thin film reaches to use requirement.