The lithographic method of TiAlN thin filmTechnical field
The present invention relates to semiconductor device processing technology field, in particular to a kind of lithographic method of TiAlN thin film.
Background technique
To meet the requirement that dimensions of semiconductor devices in IC manufacturing constantly reduces in proportion, that is, technology nodeDesired size constantly reduces.Into after 20nm technology node, process complexity degree is improved, for each technical processHigher requirement is needed, the accurate control of technological parameter is needed in most of techniques, the essence in manufacturing process can be metDegree control.
In wet-etching technology, the concentration precision of chemical liquids is required to improve.It can when chemical concentrations inaccuracyFilm can be caused to remove unclean or overetch.In workfunction layers (WFM), the etching technics of TiN is usually adoptedUse wet etching.For example, it is desired to remove the TiAlN thin film in NMOS area, if because of the change under special ratios needed in etching technicsLearn liquid concentration abnormality, then will lead to can not effectively remove TiAlN thin film, then can yield to subsequent technique and final reliability haveSignificant impact.
As shown in fig.1, in the prior art, after TiAlN thin film preparation, there is TiAlN thin film layer 02 on silicon layer 01.It is placed in crystalline substanceNext station is transferred in boat box to carry out wet etching, transmission process P1 needs to spend waiting time Tq.With the waiting timePassage, TiAlN thin film 02 reacted with the oxygen in air cause surface formed TiON oxide layer 03.And in previous process(transmission of Fig. 1 waits before P1), does not almost there is native oxide generation.The prior art, using semiconductor wet etching apparatusSpray head 04 spray SC1 solution (main component is NH4OH:H2O2: H2O=1:1:5 it) is cleaned, due to there are oxide layer 03,Decline so as to cause the etching of TiN layer 02.
Since the oxygen binding ability of Ti in TiN layer 02 is very strong, even if waiting time TqIt is small again, it also will form one layer of oxidationLayer 03, leads to the generation of the above problem.
Moreover, etch rate is technical parameter important in wet etching, and directly control the skill of device machining accuracyArt parameter.SC1 solution is different to the etch rate of oxide layer 03 with TiAlN thin film layer 02, is easy so that this technology of etch rateParameter generates concussion, to affect the observing and controlling to the parameter.
Therefore, how a kind of 02 method of etching TiN layer is provided, influence of the oxide layer 03 to etch rate, energy can be eliminatedIt is enough that etch rate is monitored in etching process, and etching speed can be adjusted by adjusting related process parametersRate can finally produce the device for meeting required precision.
Summary of the invention
The technical problem to be solved by the application is to provide a kind of etching side's methods of film, can be in etching processIn etch rate is monitored, and can by adjust related process parameters adjust etch rate, can finally produceMeet the device of required precision.
In order to solve the above technical problems, the present invention provides a kind of lithographic method of TiAlN thin film, its object is to can incite somebody to actionThe parameter of etch rate in TiAlN thin film etching technics extremely can monitoring state --- in this, as feedback, and combine related workThe adjusting of skill parameter, can be by wet etching TiAlN thin film precision improvement, and reduces the adverse effect to subsequent technique accordingly, mostThe device for meeting required precision is produced eventually.
In order to achieve the above object, the present invention provides a kind of lithographic method of TiAlN thin film, the TiAlN thin film includes oneOxide layer；
The lithographic method includes:
Step S1, pre-treatment step under the first cleaning solution temperature, clean the first scavenging period using the first cleaning solution；
Step S2, main process task step under the second cleaning solution temperature, clean the second scavenging period using the second cleaning solution.
Preferably, the oxide layer is in transport process, and TiAlN thin film outer surface TiN adsorbs oxygen and generates TiON layers.
Preferably, transhipment time is greater than 1 hour, the oxide layer to being saturated, after saturation the oxide layer with a thickness of 7~10 Ethylmercurichlorendimides.
Preferably, first cleaning solution is dilute hydrofluoric acid.
Preferably, first cleaning solution temperature is 25~30 DEG C.
Preferably, first scavenging period, 60~240s.
Preferably, the flow of first cleaning solution is 1000~2000 ml/mins.
Preferably, second cleaning solution is ammonium hydroxide aqueous hydrogen peroxide solution, parts by weight meter, NH4OH:H2O2: H2O=1:1:5。
Preferably, second cleaning solution temperature is 40~60 DEG C.
Preferably, second scavenging period, 60~120s.
Preferably, the flow of second cleaning solution is 1000~2000 ml/mins.
Preferably, the lithographic method uses in-situ process；
It is intracavitary in same cleaning, after having carried out the step S1, continuously carry out the step S2.
Preferably, the step S2 further includes,
Step S21 monitors the etch rate of TiAlN thin film；
Step S22 adjusts cleaning parameters according to the requirement etched in technique.
Preferably, cleaning parameters described in the step S22 include the scavenging period of the second cleaning solution, cleaning solution flow,Cleaning solution temperature or concentration of lotion.
Preferably, this method is applied to 28 nanometers of technology node or less, 22 nanometers or less, 20 nanometers or less or 16 nanometersFollowing processing procedure.
Compared with prior art, the present invention provides a kind of lithographic method of TiAlN thin film, and the TiAlN thin film includes an oxidationLayer；The lithographic method includes: step S1, and pre-treatment step under the first cleaning solution temperature, is cleaned using the first cleaning solutionFirst scavenging period；Step S2, main process task step, using the second cleaning solution, under the second cleaning solution temperature, the second cleaning of cleaningTime.Can be intracavitary in same cleaning, after having carried out the step S1, continuously carry out the step S2.Accordingly, according to instituteLithographic method is stated, after capable of first removing the oxide layer on TiAlN thin film surface, TiAlN thin film is carried out immediately, eliminates oxidation at this timeThe influence of layer, the etch rate of TiAlN thin film can't generate fluctuation because of the etching between different materials, so as to etchingRate is monitored, and etch process parameters are adjusted accordingly, so that the craft precision of the wet etching is promoted, is reducedAdverse effect to subsequent technique finally produces the device for meeting required precision.
Detailed description of the invention
Fig. 1 is to use wet-etching technology schematic diagram after the TiAlN thin film of the prior art generates oxide layer.
Fig. 2 is the lithographic method process schematic representation of TiAlN thin film of the invention.
Description of symbols
01 silicon layer, 02 TiAlN thin film layer
03 TiON oxide layer, 04 spray head
P1 transmission process TqWaiting time
11 silicon layer, 12 TiAlN thin film layer
13 TiON oxide layer, 21 first spray head
22 second spray heads 30 clean chamber
S1 pre-treatment step S2 main process task step
P2 in-situ process Tq1Work step time interval
Specific embodiment
It elaborates with reference to the accompanying drawing to a preferred embodiment of the present invention.It is to be appreciated that the present invention not officeIt is limited to above-mentioned particular implementation, devices and structures not described in detail herein should be understood as with the common side in this fieldFormula is practiced；Anyone skilled in the art, it is without departing from the scope of the technical proposal of the invention, all availableThe methods and technical content of the disclosure above makes many possible changes and modifications to technical solution of the present invention, or is revised as equivalentThe equivalent embodiment of variation, this is not affected the essence of the present invention.
As shown in fig.2, usually TiAlN thin film refers to there is a TiAlN thin film layer 12 on Si layer 11.Due to TiAlN thin film layerThe oxygen activity of Ti in 12 is strong, so, although TiAlN thin film is without native oxide under normal circumstances, when TiAlN thin film is exposed toA period of time, then can generate an oxide layer 13 on TiAlN thin film layer in air.The oxide layer 13 is the TiN in transport process12 outer surface TiN of film layer adsorbs oxygen and generates TiON layer 13.
Under normal conditions, after transhipment time reaches 1 hour, the oxide layer 13 to saturation, the oxide layer after saturationWith a thickness of 7~10 Ethylmercurichlorendimides (Ethylmercurichlorendimide, i.e.,Equal to 10-10M, i.e., 0.1 nanometer).Even if transhipment time is short again also to generate instituteState oxide layer 13.
As shown in fig.2, the TiAlN thin film includes an oxide layer the present invention provides a kind of lithographic method of TiAlN thin film13；The lithographic method includes: step S1, and pre-treatment step under the first cleaning solution temperature, is cleaned using the first cleaning solutionFirst scavenging period；Step S2, main process task step, using the second cleaning solution, under the second cleaning solution temperature, the second cleaning of cleaningTime.
TiON layer 13 and TiN layer 12 need to perform etching using different cleaning solutions.
A specific embodiment of step S1 is provided.For TiON layer 13, need using dilute hydrofluoric acid (DHF) as firstCleaning solution performs etching.In order to reach preferable etching effect, the temperature of dilute hydrofluoric acid (DHF) is 25~30 DEG C；Cleaning60~240s of time；The flow of cleaning solution is 1000~2000 ml/mins.The purpose of step S1 is, as far as possible fastly will be describedThe all etching removals of TiON layer 13.
A specific embodiment of step S2 is provided.For TiAlN thin film layer 12, need using the conduct of ammonium hydroxide aqueous hydrogen peroxide solutionSecond cleaning solution performs etching.In order to reach preferable etching effect, the temperature of ammonium hydroxide aqueous hydrogen peroxide solution is 40~60 DEG C；60~120s of scavenging period；The flow of cleaning solution is 1000~2000 ml/mins.The purpose of step S1 is, sudden and violent in TiN layer 12Wet etching is carried out after dew as early as possible, and the etching rate of TiN layer 12 can be precisely controlled.
First cleaning solution and second cleaning solution, can be supplied to first spray head 21 and second spray head from two pipelines22, each pipeline can be controlled separately, and can control and sprays first cleaning solution or second cleaning solution.
Shown in Fig. 2, the lithographic method uses in-situ process (IN-SITU Process) P2；I.e. in same cleaning chamberIn 30, after having carried out the step S1, the step S2 is continuously carried out.It is, need after having carried out step S1,After etching whole TiON layer 13 (dotted line frame at S2), the exposed first time of TiN layer 12, in other words, pre-treatment stepRapid S1 to work step time interval T between main process task step S2q1It is intended to 0 as far as possible.It is exposed to oxygen in addition, also to reduce to the greatest extentIn.If having transport process between pre-treatment step S1 and main process task step S2, even if very thin TiON layer 13 and TiNLayer 12 combines, then, because the second cleaning solution needs to etch two kinds of materials at this time, and may also have non-uniform cross-distribution,Can then concussion be generated to etching rate.In order to avoid foregoing problems, then there generally can not be transhipment, need using in-situ process, completeAt (i.e. the original position) immediately carries out step S2 in same cleaning chamber 30 after step S1, such second cleaning solution just etches listOne material --- TiN layer 12.
In the etching technics of TiAlN thin film, main purpose is etching removal TiN layer 12, moreover, the thickness of TiN layer 12 is halfThe structural parameters for needing to control in conductor device structure.Therefore, the dimensional accuracy of control device in order to be more accurate, in this hairIn technique provided by bright, it is only necessary to carry out stringent monitoring and control (it is, not for pre-treatment step S1 to step S2It needs to carry out real-time monitoring).After the completion of preamble technique, TiN layer 12 has an original depth, which can monitor, thanSuch as ultrasonic measurement.The present invention provides the embodiment of a controllable step S2: the step S2 further includes step S21, monitors TiNThe etch rate of film；Step S22 adjusts cleaning parameters according to the requirement etched in technique.Firstly, etch rate is no longer bigAmplitude wave is dynamic or etch rate has not been normal (only being performed etching with a kind of cleaning solution) after preceding spy is small, therefore, the quarterLosing rate is that can measure and can be used as feedback to carry out relevant control.Secondly, etch rate can be by cleaning parametersAdjusting change, accordingly it is also possible to controlled according to feedback.
Preferably, cleaning parameters described in the step S22 include the scavenging period of the second cleaning solution, cleaning solution flow,Cleaning solution temperature or concentration of lotion.
The control of scavenging period is exactly the opening time for controlling the pipeline switch valve of the second cleaning solution, be exactly the T1 moment fromThe dynamic connection for stirring solenoid valve to pipeline to a second spray head 22 is open-minded, and in T2 moment automatic poking moving electromagnetic valve to anotherPosition pipeline to second spray head 22 connection closed.
The control of cleaning solution flow is exactly the pump being arranged in control piper, and control pump pumps out flow to required numerical value modelIt encloses.
The control of cleaning solution temperature is exactly to control heating-cooling system temperature of liquid container.
The control of concentration of lotion can control the flow of three kinds of ingredients (ammonium hydroxide, hydrogen peroxide, water) corresponding each pumpSystem is imported to an intermediate receptacle (mixing chamber), or adjusts the flow that water is added.
Accordingly, the observing and controlling of the etching rate to TiN layer 12 may be implemented.
Preferably, this method is applied to 28 nanometers of technology node or less, 22 nanometers or less, 20 nanometers or less or 16 nanometersFollowing processing procedure.The requirement of phase closing precision can be reached.
Compared with prior art, the present invention provides a kind of lithographic method of TiAlN thin film, and the TiAlN thin film includes an oxidationLayer；The lithographic method includes: step S1, and pre-treatment step under the first cleaning solution temperature, is cleaned using the first cleaning solutionFirst scavenging period；Step S2, main process task step, using the second cleaning solution, under the second cleaning solution temperature, the second cleaning of cleaningTime.Can be intracavitary in same cleaning, after having carried out the step S1, continuously carry out the step S2.Also, it monitorsThe etch rate of TiAlN thin film；According to the requirement etched in technique, cleaning parameters are adjusted.To realize the etching of TiN layer 12The observing and controlling of rate.Accordingly, TiN is carried out after capable of first removing the oxide layer on TiAlN thin film surface according to the lithographic method immediatelyFilm, eliminates the influence of oxide layer at this time, and the etch rate of TiAlN thin film can't be produced because of the etching between different materialsRaw fluctuation, so as to be monitored to etch rate, and is accordingly adjusted etch process parameters, so that the wet process is carvedThe craft precision of erosion is promoted, and is reduced the adverse effect to subsequent technique, is finally produced the device for meeting required precision.
The above is only a preferred embodiment of the present invention, is not intended to limit the present invention.Come for those skilled in the artIt says, the invention may be variously modified and varied.All within the spirits and principles of the present invention, made any modification, equivalentReplacement, improvement etc., should all be included in the protection scope of the present invention.