CN108242503A - A kind of method for optimizing magnetic tunnel junction - Google Patents

A kind of method for optimizing magnetic tunnel junction Download PDF

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Publication number
CN108242503A
CN108242503A CN201611229902.8A CN201611229902A CN108242503A CN 108242503 A CN108242503 A CN 108242503A CN 201611229902 A CN201611229902 A CN 201611229902A CN 108242503 A CN108242503 A CN 108242503A
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tunnel junction
magnetic tunnel
ion beam
etching
chemically assisted
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CN108242503B (en
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张云森
肖荣福
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Shanghai Ciyu Information Technologies Co Ltd
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Shanghai Ciyu Information Technologies Co Ltd
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N50/00—Galvanomagnetic devices
    • H10N50/01—Manufacture or treatment

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  • Manufacturing & Machinery (AREA)
  • Mram Or Spin Memory Techniques (AREA)
  • Hall/Mr Elements (AREA)

Abstract

The present invention provides a kind of methods that chemically assisted ion beam etching optimizes the magnetic tunnel junction after etching, it is related to magnetic RAM manufacturing technology field, volatile metal complex is generated since the chemically reactive gas in method can react with damage/sedimentary, simultaneously, the inert gas ion beam radiation of low-angle can enhance complex reaction, so as to effectively remove the damage/sedimentary for being covered in side wall, it is very beneficial for magnetic RAM magnetics, the promotion of electric property and the improvement of yield.

Description

A kind of method for optimizing magnetic tunnel junction
Technical field
The present invention relates to magnetic RAM manufacturing technology field more particularly to a kind of optimization sides of magnetic tunnel junction Method, it is specially a kind of using chemically assisted ion beam etching (CAIBE, Chemically Assisted Ion Beam Etching) optimize the method for magnetic tunnel junction.
Background technology
In recent years, using the magnetic RAM of magnetic tunnel junction (MTJ, Magnetic Tunnel Junction) (MRAM, Magnetic Radom Access Memory) is by it is believed that be following solid state non-volatile memory body, it has There is the characteristics of high-speed read-write, large capacity and low energy consumption.Ferromagnetism MTJ is usually sandwich structure, wherein the memory layer that is magnetic, It can change the direction of magnetization to record different data；Positioned at the tunnel barrier layer of intermediate insulation；Magnetic reference layer is located at The opposite side of tunnel barrier layer, its direction of magnetization are constant.
For information can be recorded in this magnetoresistive element, it is proposed that using based on spin momentum transfer or spin-transfer torque The write method of (STT, Spin Transfer Torque) switch technology, such MRAM are known as STT-MRAM.According to magnetic polarization The difference in direction, STT-MRAM are divided into as STT-MRAM in face and vertical STT-MRAM (i.e. pSTT-MRAM), and the latter has preferably Performance.Method according to this, you can by providing spin polarized current to magnetoresistive element come the intensity of magnetization of inverting magnetization memory layer Direction.In addition, the reduction of the volume with Magnetic memory layer, write or spin polarized current that conversion operation need to be injected is also smaller. Therefore, this write method can be achieved at the same time device miniaturization and reduce electric current.
Meanwhile in view of switching electric current required when reducing MTJ element size can also reduce, so the pSTT- in terms of scale MRAM can be very good mutually to agree with state-of-the-art technology node.Therefore, it is desirable to it is that pSTT-MRAM elements are made into minimum ruler It is very little, and with extraordinary uniformity and the influence to MTJ magnetism is minimized, used preparation method can also be real Show high good and the bad rate, pinpoint accuracy, high reliability, low energy consumption and remain adapted to the temperature coefficient that data well preserve.Meanwhile Write operation is changed based on resistance state in nonvolatile memory, so as to need control thus caused to mtj memory device lifetime Destruction and shortening.However, the fluctuation of MTJ resistance may be increased by preparing a small-sized MTJ element so that pSTT-MRAM's Larger fluctuation can also be had therewith by writing voltage or electric current, can damage the performance of MRAM in this way.
In existing MRAM manufacturing process, two kinds of etching technics of generally use to carry out magnetic tunnel junction it is miniature, the One kind is ion beam etching (IBE, Ion Beam Etching), and second is reactive ion etching (RIE, Reactive Ion Etching).This two kinds of etching technics respectively have advantage and disadvantage, such as：IBE has very excellent anisotropic etching performance, but It is, due to ion beam (Ar+Deng) itself do not chemically reacted with the material that is etched, it will there is excessively poor etching selection ratio With more sputter deposition；RIE then has extraordinary etching selection ratio, and still, anisotropic etching performance will be by To influence.In current manufacture craft, due to the deposition again of physical sputtering or chemical etching by-product, in general, in magnetic Property tunnel knot etching after, side wall can form one layer of damaging layer/sedimentary, this will influence the magnetism and electricity of magnetic tunnel junction Performance, What is more, it will the short circuit from reference layer to memory layer is directly resulted in, so as to be unfavorable for carrying for magnetic storage yield It is high.
In recent years, chemically assisted ion beam etching (CAIBE) due to good directionality and chemical etching selection ratio, It is widely used in semiconductor etching field, common apparatus is as shown in Figure 1；Its principle is：First, make to be passed through by nozzle 120 Inert gas, such as：He, Ne, Ar, Kr or Xe etc., ionization generation cation, then, lazy in ion generates cavity 110 Property cation by accelerator 130 be accelerated to etching needed for energy, then, the good inertia cation of directionality is in process cavity It is moved in a straight line in 160 until 180 surface of substrate that is etched, reaction gas is such as：O2、N2、CO2、NF3、SF6、CF4、Cl2、BCl3、 HBr、CHF3、CO、SO2Or CH2F2Deng, by the entrance process cavity 160 of valve 170, cation and chemically reactive molecule/original Son carries out physical-chemical reaction with the material that is etched, and finally, etch by-products are by the turbomolecular pump 190 of access process cavity 160 It takes away.Averager 140 is housed generally in process cavity 160 in order to discharge excessive positive charge；In order to in etching process, work In skill cavity the variation of chemical element do in real time monitoring generally in process cavity 160 equipped with ion microprobe (SIMS, Second Ion Mass Spectroscopy)150；In order to obtain better etching performance and side wall be trimmed, generally Deflection and rotating speed of the wafer console 180 to ion beam can be controlled.
Therefore, those skilled in the art is dedicated to developing a kind of damage/sedimentary for effectively removing and being covered in side wall Method, improves magnetics, the electric property of magnetic RAM, and improves its yield.
Invention content
The present invention provides a kind of method for optimizing magnetic tunnel junction, using chemically assisted ion beam etching (CAIBE) method Magnetic tunnel junction after etching is trimmed.
Further, this method includes the following steps：
Form magnetic tunnel junction multilayer film and mask layer；
Pattern the mask layer；
Etch magnetic tunnel junction；
The magnetic tunnel junction is trimmed using chemically assisted ion beam etching (CAIBE) method.
Further, the magnetic tunnel junction is etched using reactive ion etching and/or the method for ion beam etching.
Further, during the chemically assisted ion beam etching, the ion source of the ion beam is inert gas.
Further, during the chemically assisted ion beam etching, the reaction gas as chemistry auxiliary is PF3、NO、 One or several kinds in gas with carbonyl or hydroxy functional group.
Further, the gas with carbonyl or hydroxy functional group is HCOOH, CH3OH、CH3COOH、C2H5OH、 COF2Or CO/NH3.Three key of carbon oxygen in wherein CO containing a C=O bond and a coordinate bond, it will also be appreciated that be containing The compound of carbonyl functional group.
Further, the total flow of the reaction gas is 20-500sccm.
Further, ion beam described in the chemically assisted ion beam etching method is incident using low-angle.
Further, during the chemically assisted ion beam etching, the ion source flux of the ion beam is 10- 200sccm, the radio-frequency power supply power for generating and maintaining plasma are 100-3000watt, and ion beam accelerating voltage is 50- 1000V, the speed of wafer console rotation is 0-60rpm.
Further, during the chemically assisted ion beam etching, the incident direction angle of ion beam remain fixed or Change between multiple angle values.
Technique effect
A kind of use chemically assisted ion beam etching (CAIBE) method provided by the invention is to the magnetic tunnel after etching The method that knot side wall optimizes.Since the chemically reactive gas in method can react generation easily with damage/sedimentary Metal phosphorizing complex compound (Metal phosphine complex), the metal nitrosyl base complex (Metal of volatilization Nitrosyl complex) or Metal carbonyl complex (Metal carbonyl complex)；Meanwhile the indifferent gas of low-angle Body ion beam irradiation can enhance complex reaction.Therefore, which, which can effectively remove, is covered in the damage of side wall/heavy Lamination is very beneficial for magnetic RAM magnetics, the promotion of electric property and the improvement of yield.
The technique effect of the design of the present invention, concrete structure and generation is described further below with reference to attached drawing, with It is fully understood from the purpose of the present invention, feature and effect.
Description of the drawings
Fig. 1 is the process unit structure diagram of chemically assisted ion beam etching of the present invention (CAIBE).
Fig. 2 is that magnetic tunnel junction and the process flow chart trimmed are prepared in the preferred embodiment of the present invention.
Fig. 3 is in Fig. 2 embodiments, provides the hearth electrode substrate of chemically mechanical polishing, and sequentially form magnetic tunnel on it Schematic diagram after road knot multilayer film and hard mask film layer.
Fig. 4 is the schematic diagram after being performed etching to magnetic tunnel junction in Fig. 2 embodiments.
Fig. 5 is the schematic diagram trimmed using CAIBE to the side wall of magnetic tunnel junction in Fig. 2 embodiments.
Fig. 6 is the schematic diagram after being trimmed using CAIBE to the side wall of magnetic tunnel junction in Fig. 2 embodiments.
Drawing reference numeral：100- chemically assisted ion beam etchings (CAIBE) process unit, 110- ions generate cavity, 120- Nozzle, 130- accelerators, 140- averagers, 150- ion microprobes, 160- process cavities, 170- valves, 180- wafer controls Platform processed, 190- turbomolecular pumps, 210- hearth electrode substrates, 220- magnetic tunnel junction multilayer films, 230- hard masks film layer and 240- Sidewall damage/sedimentary.
Specific embodiment
In order to make the foregoing objectives, features and advantages of the present invention clearer and more comprehensible, below in conjunction with the accompanying drawings to the present invention Specific embodiment be described in detail.It should be noted that attached drawing of the present invention uses using the form of simplification and non-essence Accurate ratio, only for the purpose of facilitating and clarifying the purpose of the embodiments of the invention.
A kind of chemically assisted ion beam etching (CAIBE) provided by the invention to the magnetic tunnel junction side wall after etching into The process of row optimization, by using He, Ne, Ar, Kr or Xe as ion source, using PF3, NO and with carbonyl or hydroxyl Functional group gas (such as：HCOOH、CH3OH、CH3COOH、C2H5OH、COF2Or CO/NH3Deng) etc. in one or several kinds As reaction gas, low-angle ion beam trimming is carried out to magnetic tunnel junction side wall after etching.Since the chemistry in technique is living Property gas, can react volatile metal phosphorizing complex compound (the Metal phosphine of generation with damage/sedimentary ), complex metal nitrosyl base complex (Metal nitrosyl complex) or Metal carbonyl complex (Metal Carbonyl complex), meanwhile, He, Ne, Ar, Kr or Xe ion beam irradiation of low-angle can enhance complex reaction.Tool Body implementation steps are as shown in Figure 2：
Step 1：Hearth electrode substrate 210, and deposited magnetic tunnel knot multilayer film 220 and hard mask film in substrate are provided Layer 230, as shown in Figure 3；
Wherein, the overall thickness of magnetic tunnel junction (MTJ) multilayer film 220 is 15nm-40nm, can be by reference layer, potential barrier The Bottom Pinned structures being superimposed upwards successively of layer and memory layer either by memory layer, barrier layer and reference layer according to The secondary Top Pinned structures being superimposed upwards.
Reference layer has magnetic polarization invariance, is face inner mold (iSTT-MRAM) or vertical (pSTT-MRAM) structure according to it It is different.The reference layer of face inner mold (iSTT-MRAM) generally has (IrMn or PtMn)/CoFe/Ru/CoFe structures, excellent It is 10-30nm to select overall thickness；The reference layer of vertical-type (pSTT-MRAM) generally has TbCoFe or [Co/Pt]nCo/Ru/ [CoPt]mSuperlattice multilayer film structure, preferred overall thickness are 8-20nm.
Barrier layer is nonmagnetic metal oxide, preferably MgO, MgZnO or Al2O3, thickness 0.5-3nm.
Remember layer have variable magnetic polarize, according to its be face inner mold (iSTT-MRAM) or vertically (pSTT-MRAM) structure again Institute is different.The memory layer of face inner mold iSTT-MRAM is generally CoFe/CoFeB or CoFe/NiFe, preferred thickness 2nm- 6nm, vertical-type pSTT-MRAM memory layer be generally CoFeB, CoFe/CoFeB, Fe/CoFeB, CoFeB (Ta, W, Mo)/ CoFeB, preferred thickness 0.8nm-2nm.
The thickness of hard mask layer 230 is 20-100nm, selects Ta, TaN, W or WN etc. to be obtained more in halogen plasma-based Carve profile well.
Step 2：220 pattern of graphic definition magnetic tunnel junction etches magnetic tunnel junction 220, as shown in Figure 4；The step The following steps can be divided into：
(1) 220 pattern of graphic definition magnetic tunnel junction, and pattern is shifted to the top of magnetic tunnel junction 220；It crosses herein Cheng Zhong, using a photoetching once etch (LE, lithography-etching) or Twi-lithography twice etching (LELE, Lithography-etching-lithography-etching method) is completed the definition to magnetic tunnel junction 220 and is covered firmly Reactive ion (RIE) etching of mold layer 230, and remaining polymer is removed using RIE techniques simultaneously, so that pattern is transferred to magnetic The top of property tunnel knot 220.
(2) magnetic tunnel junction 220 is performed etching；
Wherein, etching technics may be used reactive ion etching (RIE, Reactive Ion Etching) and/or from Beamlet etches (IBE, Ion Beam Etching).IBE is mainly used as ion source using Ar, Kr or Xe etc.；RIE is mainly used CH3OH、C2H5OH、CH3OH/Ar、CH4/ Ar or CO/NH3Deng as main etching gas；And use emission spectrometer (OES, Optical Emission Spectroscopy) or ion microprobe (SIMS, Second Ion Mass Spectroscopy) judge etching terminal signal.
Step 3：Chemically assisted ion beam etching (CAIBE) trims magnetic tunnel junction side wall to remove side wall damage Wound/sedimentary 240, as illustrated in Figures 5 and 6；In the present invention, by using He, Ne, Ar, Kr or Xe as ion source, use PF3, NO and with carbonyl or hydroxy functional group gas (such as：HCOOH、CH3OH、CH3COOH、C2H5OH、COF2Or CO/NH3 Deng) etc. in one or several kinds as reaction gas, low-angle ion beam is carried out to magnetic tunnel junction side wall after etching and is repaiied It cuts.Due to the chemically reactive gas in technique, the volatile metal phosphorizing complexing of the generation that can react with damage/sedimentary Object (Metal phosphine complex), metal nitrosyl base complex (Metal nitrosyl complex) or metal Carbonyl complex (Metal carbonyl complex), meanwhile, He, Ne, Ar, Kr or Xe ion beam irradiation energy of low-angle Enough enhance complex reaction.
Preferably, the flow of ion source He, Ne, Ar, Kr or Xe are 10-200sccm, the radio frequency electricals such as generate and maintain The power in source is 100-3000watt, and ion beam accelerating voltage is differed for 50-1000V；Keep the deflection of ion beam for 0 ° or Person changes the deflection that ion beam is varied multiple times, such as：2 °, 4 ° or 6 ° etc., the speed of wafer console rotation is 0-60rpm, Such as：0rpm, 30rpm or 60rpm etc..
Preferably, reactivity chemical gas PF3, NO and/or with carbonyl or hydroxy functional group gas (such as： HCOOH、CH3OH、CH3COOH、C2H5OH、COF2Or CO/NH3Deng) total flow differ for 20-500sccm.
The preferred embodiment of the present invention described in detail above.It should be appreciated that those of ordinary skill in the art without Creative work is needed according to the present invention can to conceive and makes many modifications and variations.Therefore, all technologies in the art Personnel are available by logical analysis, reasoning, or a limited experiment on the basis of existing technology under this invention's idea Technical solution, all should be in the protection domain being defined in the patent claims.

Claims (10)

  1. A kind of 1. method for optimizing magnetic tunnel junction, which is characterized in that using chemically assisted ion beam etching method to etching it Magnetic tunnel junction afterwards is trimmed.
  2. 2. the method for optimization magnetic tunnel junction as claimed in claim 1, which is characterized in that include the following steps：
    Form magnetic tunnel junction multilayer film and mask layer；
    Pattern the mask layer；
    Etch magnetic tunnel junction；
    The magnetic tunnel junction is trimmed using chemically assisted ion beam etching method.
  3. 3. the method for optimization magnetic tunnel junction as claimed in claim 2, which is characterized in that using reactive ion etching and/or ion The method of beam etching etches the magnetic tunnel junction.
  4. 4. the method for optimization magnetic tunnel junction as claimed in claim 1, which is characterized in that the chemically assisted ion beam etching process In, reaction gas PF3, NO, the one or several kinds in the gas with carbonyl or hydroxy functional group.
  5. 5. the method for optimization magnetic tunnel junction as claimed in claim 4, which is characterized in that the gas with carbonyl or hydroxy functional group Body is HCOOH, CH3OH、CH3COOH、C2H5OH、COF2Or CO/NH3One or more of.
  6. 6. the method for optimization magnetic tunnel junction as claimed in claim 1, which is characterized in that the chemically assisted ion beam etching process In, the total flow of reaction gas is 20-500sccm.
  7. 7. the method for optimization magnetic tunnel junction as claimed in claim 1, which is characterized in that the chemically assisted ion beam etching process In, the ion source of ion beam is inert gas.
  8. 8. the method for optimization magnetic tunnel junction as claimed in claim 1, which is characterized in that the chemically assisted ion beam etching process In, ion beam is incident using low-angle.
  9. 9. the method for optimization magnetic tunnel junction as claimed in claim 1, which is characterized in that the chemically assisted ion beam etching process In, the ion source flux of ion beam is 10-200sccm, and the radio-frequency power supply power for generating and maintaining plasma is 100- 3000watt, ion beam accelerating voltage are 50-1000V, and the speed of wafer console rotation is 0-60rpm.
  10. 10. the method for optimization magnetic tunnel junction as claimed in claim 1, which is characterized in that the chemically assisted ion beam etching mistake Cheng Zhong, the incident direction angle of ion beam remain fixed or change between multiple angle values.
CN201611229902.8A 2016-12-27 2016-12-27 Method for optimizing magnetic tunnel junction Active CN108242503B (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2020087917A1 (en) * 2018-11-02 2020-05-07 江苏鲁汶仪器有限公司 Method for manufacturing magnetic tunnel junction

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013012546A (en) * 2011-06-28 2013-01-17 Toshiba Corp Manufacturing method of nonvolatile storage device
CN106159081A (en) * 2015-05-15 2016-11-23 三星电子株式会社 Form the method for pattern, magnetic memory device and manufacture method thereof

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013012546A (en) * 2011-06-28 2013-01-17 Toshiba Corp Manufacturing method of nonvolatile storage device
CN106159081A (en) * 2015-05-15 2016-11-23 三星电子株式会社 Form the method for pattern, magnetic memory device and manufacture method thereof

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2020087917A1 (en) * 2018-11-02 2020-05-07 江苏鲁汶仪器有限公司 Method for manufacturing magnetic tunnel junction

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