Method for manufacturing a magnetic device

Abstract

A method of manufacturing a magnetic device, the method comprising: Forming a stack structure (40; 50; 250), wherein the stack structure (40; 50; 250) comprises a non-volatile metal layer; and Etching the stack structure (40; 50; 250) comprising the non-volatile metal layer with an etching gas containing at least 80% by volume of H2 gas, wherein the method further comprises exposing a region of the stack structure (40; 50; 250) to a hydrogen plasma prior to etching the stack structure (40; 50; 250).

Description

BACKGROUNDField of the invention

[0001] The inventive concept relates to a method for manufacturing a magnetic device. More specifically, the inventive concept relates to a method for manufacturing a magnetic device comprising a non-volatile magnetic layer. State of the art

[0002] Many research projects have been conducted on electronic devices that utilize the magnetoresistive characteristics of magnetic tunnel junctions (MTJs). In particular, as an MTJ cell of a highly integrated magnetic random access memory (MRAM) device is being miniaturized, spin transfer torque (STT) MRAM has attracted attention. This device stores information by utilizing a physical phenomenon called STT, i.e., by directly applying voltage to the MTJ cell and inducing magnetization reversal. A very small MTJ structure must be fabricated to implement a highly integrated STT MRAM.

[0003] From the document JP 2005-277 249 A a plasma processing method is known in which, after the film containing the magnetic material (magnetized free layer) has been subjected to the etching process, a processing for exposing the film containing the magnetic material that has been subjected to the etching process to the plasma atmosphere of a gas mixture with a hydrogen gas or gas containing at least hydrogen atoms and with oxygen gas or nitrogen gas is carried out.

[0004] According to JP 2000-332020 A, a TiN film is formed as a diffusion barrier base film in an MOCVD chamber by an MOCVD method using tetrakisdialkylaminotitanium (TDATT) as a source gas. Furthermore, in a CVD chamber, a Cu interconnect film is formed on the TiN film, which is the barrier film, by a CVD method using a material such as an organic metal complex. To establish electrical connection with the Cu interconnect film, a via hole formed in an interlayer insulating film has a base film present on its underside, which has been removed by sputter etching based on a plasma process using argon, nitrogen, and / or hydrogen gases in a sputter etching chamber.

[0005] US 2004 / 0 095 801 A1 discloses a method and structure for a non-volatile magnetic random access memory (MRAM) device comprising a stable magnetic electrode, an oxide layer adjacent to the stable magnetic electrode, and a free magnetic electrode. The oxide layer is located between the stable magnetic electrode and the free magnetic electrode. A conductor is connected to a stable magnetic electrode. The oxide layer has a resistance value that allows sufficient power dissipation to reduce the anisotropy of the free magnetic electrode through current-induced heating. Current-induced heating is used in combination with spin-transfer torque or a magnetic field to switch the free magnetic electrode.

[0006] The task is to develop an etching technology that can quickly implement a reliable MTJ cell once the MTJ structure is fabricated with a very small size.

[0007] The problem is solved by the methods according to patent claims 1 and 10. Further embodiments emerge from the dependent patent claims. SUMMARY

[0008] The inventive concept provides a method of manufacturing a magnetic device having a non-volatile magnetic layer via an etching process to produce a highly integrated, high-density magnetic device.

[0009] The inventive concept also provides a magnetic device for use in a highly integrated, high-density magnetic device comprising a magnetic pattern having a high aspect ratio.

[0010] According to one aspect of the inventive concept, a method of manufacturing a magnetic device is provided, the method comprising forming a stack structure, the stack structure comprising a non-volatile metal layer; and etching the stack structure comprising the non-volatile metal layer with an etching gas containing at least 80 vol% H2 gas, the method further comprising exposing a region of the stack structure to a hydrogen plasma prior to etching the stack structure.

[0011] The stack structure may include a magnetic layer.

[0012] Etching the stack structure may comprise using an etching gas containing H2 gas and an additional gas, wherein the additional gas contains an inert gas and / or NH3 gas.

[0013] The inert gas in the additional gas may contain at least one of N2, Ne, Ar, Kr, and Xe.

[0014] Etching the stack structure may include using a non-halogen etching gas.

[0015] The formation of the stack structure may include using at least one of Co / Pd, Co / Pt, Co / Ni, Fe / Pd, Fe / Pt, MgO, PtMn, IrMn, a CoFe alloy, and a CoFeB alloy.

[0016] Etching the stack structure may include performing a plasma etching process.

[0017] Etching the stack structure may comprise using a plasma etching apparatus comprising a source current output unit for applying a source current and an operating point current output unit for applying an operating point current, and repeatedly performing an operation in which at least one of the source current and the operating point current changes between an on-state and an off-state.

[0018] Forming the stacked structure may include forming the magnetic layer between an upper electrode and a lower electrode, the upper and lower electrodes being opposite to each other, and etching the stacked structure may include etching the upper electrode, the lower electrode, and the magnetic layer by using the etching gas.

[0019] According to another aspect of the inventive concept, a manufacturing method of a magnetic device is provided, the method comprising forming a stack structure, the stack structure comprising a lower magnetic layer, a tunnel barrier layer, and an upper magnetic layer stacked sequentially from bottom to top, forming a mask pattern on the stack structure such that a portion of the stack structure is covered, performing a first etch through the mask pattern to etch a first portion of the stack structure, the first portion comprising at least the upper magnetic layer and the tunnel barrier layer, and wherein the first etch comprises using a first etching gas containing at least 80% by volume of H2 gas and a first additional gas, and performing a second etch through the mask pattern to etch a second portion of the stack structure,wherein the second portion comprises the lower magnetic layer of the stack structure, and wherein the second etching is performed in a different etching atmosphere than the first etching.,

[0020] The second etching may comprise using a second etching gas containing at least 80% by volume of H2 gas and a second additional gas, wherein the second additional gas contains a different component than the first additional gas.

[0021] Each of the first additional gas and the second additional gas may contain an inert gas or NH3 gas.

[0022] Each of the first additional gas and the second additional gas may contain at least one of N2, NH3, Ne, Ar, Kr or Xe.

[0023] The first additional gas may contain at least one of N2, Ne, Ar, Kr or Xe and the second additional gas contains NH3.

[0024] Forming the stacked structure may further comprise forming a lower electrode layer and an upper electrode layer, the lower magnetic layer, the tunnel barrier layer, and the upper magnetic layer disposed between the lower electrode layer and the upper electrode layer, performing the first etching may comprise etching a portion of the upper electrode layer by using the first etching gas so that the upper electrode layer is divided into a plurality of upper electrodes, and performing the second etching may comprise etching a portion of the lower electrode layer by using the second etching gas so that the lower electrode layer is divided into a plurality of lower electrodes.

[0025] Performing each of the first etching and the second etching may include using a plasma etching process.

[0026] Performing each of the first etching and the second etching may comprise using a plasma etching apparatus having a source current output unit for applying a source current and an operating point current output unit for applying an operating point current, and at least one of the first etching and the second etching may comprise repeatedly performing an operation in which the source or operating point current alternates between an off state and an on state.

[0027] The first etching may comprise applying the bias current in a constant wave mode and the second etching may comprise repeatedly performing an operation in which the bias current alternates between an on state and an off state.

[0028] The method may further comprise exposing an upper surface of the stack structure to a hydrogen plasma after forming the mask pattern and before performing the first etching.

[0029] Forming the stack structure may include using a first material and a second material, wherein the first material is at least one of Co / Pd, Co / Pt, Co / Ni, Fe / Pd, Fe / Pt, MgO, PtMn, IrMn, a CoFe alloy, and a CoFeB alloy, and wherein the second material is at least one of Ti, TiN, Ta, TaN, Ru, and W. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The features will become apparent by describing in detail exemplary embodiments with reference to the attached drawings in which: Fig. 1 illustrates a flowchart of a manufacturing method of a magnetic device according to an exemplary embodiment of the inventive concept; Fig. 2 illustrates a flowchart of a manufacturing method of a magnetic device according to another exemplary embodiment of the inventive concept; Fig. 3 shows a gas supply pulse graph of a gas supply workflow in a pretreatment process and an etching process of the manufacturing processes of a magnetic device used in Fig. 1 and Fig. 2 are shown; Fig. 4 illustrates a cross-sectional view of an exemplary stack structure used in a manufacturing method of a magnetic device according to an embodiment of the inventive concept; Fig. 5 illustrates a cross-sectional view of another exemplary stack structure used in a manufacturing method of a magnetic device according to an embodiment of the inventive concept; Fig. 6 illustrates a schematic view of an exemplary plasma etching apparatus used in a manufacturing method of a magnetic device according to an embodiment of the inventive concept; Fig. 7A is a graph showing a source current output in a constant wave mode in the plasma etching apparatus used in Fig. 6, as a function of time; Fig. 7B is a graph showing a working point current output in a constant wave mode in the plasma etching apparatus shown in Fig. 6, as a function of time; Fig. 7C is a graph showing a duty cycle of a source current output in a pulsed mode in the plasma etching apparatus shown in Fig. 6 as a function of duty cycle time; Fig. 7D is a graph illustrating a duty cycle of a duty point current output in a pulsed mode in the plasma etching apparatus shown in Fig. 6 as a function of time; Fig. 7E is a graph showing a duty cycle of a source current and a bias current delivered in a pulsed mode as a function of time for an etching process using synchronous pulse plasma etching of the plasma etching apparatus shown in Fig. 6; Fig. 8A to 8C illustrate cross-sectional views of steps in a manufacturing method of a magnetic device according to another exemplary embodiment of the inventive concept; Fig. 9A to 9C illustrate cross-sectional views of steps in a manufacturing method of a magnetic device according to another exemplary embodiment of the inventive concept; Fig. 10A is a cross-sectional view of moving paths of ions while a stack structure is etched under a condition that a source current and an operating point current output are each in constant wave modes; Fig. 10B is a cross-sectional view of ion movement paths in a synchronous pulse plasma etching process; Fig. 11 illustrates a flowchart of a manufacturing method of a magnetic device according to another exemplary embodiment of the inventive concept; Fig. 12A to 12H illustrate cross-sectional views of steps in a manufacturing method of a magnetic device according to another exemplary embodiment of the inventive concept; Fig. 13 is a graph showing a dependence of etching and redeposition rates on the concentration of H2 gas in an etching gas; Fig. 14 illustrates virtual scanning electron microscope (VSEM) photographs of etched stack structures corresponding to different concentrations of H2 gas in an etching gas according to an embodiment of the inventive concept; Fig. 15 is a VSEM photograph showing a resultant structure formed by etching a stacked structure including a magnetic layer using a manufacturing method of a magnetic device according to an embodiment of the inventive concept; Fig. 16 illustrates VSEM photographs of etched stack structures corresponding to different ratios and concentrations of H2 gas in an etching gas used on a stack structure including a magnetic layer according to an embodiment of the inventive concept; Fig. 17A and Fig. 17B are VSEM photographs illustrating a resultant structure formed by estimating the effect when a pulsed bias current is applied while etching a stacked structure including a magnetic layer using a manufacturing method of a magnetic device according to an embodiment of the inventive concept; Fig. 18 illustrates a schematic cross-sectional view of a magnetic device that can be implemented using a magnetic device manufacturing method according to an embodiment of the inventive concept; Fig. 19 illustrates a system that can be implemented using a method of manufacturing a magnetic device according to an embodiment of the inventive concept; and Fig. 20 illustrates a memory card that can be implemented using a magnetic device manufacturing method according to an embodiment of the inventive concept. DETAILED DESCRIPTION

[0031] Exemplary embodiments will now be described in greater detail with reference to the accompanying drawings; however, these may be embodied in different forms and should not be construed as limited to the embodiments set forth herein.

[0032] In the drawn figures, the dimensions of layers and regions may be exaggerated for clarity of illustration. It should be understood that when a layer or element is referred to as being "on" another layer or substrate, it may be directly on the other layer or substrate, or intervening layers may also be present. In addition, it should be understood that when a layer is referred to as being between two layers, it may be the only layer between two layers, or one or more intervening layers may also be present. Like reference numbers refer to like elements throughout.

[0033] The term "and / or," as used herein, includes any and all combinations of one or more of the associated listed items. Expressions such as "at least one of," when preceded by a list of items, modify the entire list of items and do not modify the individual items of the list.

[0034] Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers, and / or sections, it should be understood that these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms refer to a particular order, rank, or parenthood and are used only to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Therefore, a first element, component, region, layer, or section discussed below could be referred to as a second element, component, region, layer, or section without departing from the teachings of the example embodiment.For example, a first element may be referred to as a second element and similarly a second element may be referred to as a first element.

[0035] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by someone of ordinary skill in the art to which the exemplary embodiments belong. Furthermore, it is to be understood that terms, such as those defined in commonly used dictionaries, should be interpreted to have a meaning consistent with their meaning in the context of the prior art and should not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0036] If an embodiment is implemented otherwise, a particular method may be performed out of the order described. For example, two continuously described methods may be performed substantially concurrently or in an order opposite to the described order.

[0037] For example, shapes depicted in the drawings may be deformed according to manufacturing technology and / or tolerance. Therefore, the exemplary embodiments of the present invention are not limited to the specific shapes depicted in the present description and may include modifications of shapes caused by the manufacturing process.

[0038] Fig. 1 is a flowchart illustrating a manufacturing method of a magnetic device according to an exemplary embodiment of the inventive concept.

[0039] In workflow 12 after Fig. 1, a stack structure comprising at least one magnetic layer is etched using an etching gas comprising at least 80% by volume of H2 gas.

[0040] In some embodiments, the etching of the stack structure is performed using a plasma etching process. For example, the etching process of operation 12 may be performed using a plasma etching apparatus comprising a source current delivery unit for applying a source current and a bias current delivery unit for applying a bias current. A plasma etching apparatus 60, as shown in Fig. 6, for example, can be used as the plasma etching device. In the etching method of operation 12, a current applied in the pulsed mode to output at least one of the source current and the operating point current in a pulsed mode can be maintained in an off state for a predetermined period of time. The source current in the pulsed mode and the operating point current in the pulsed mode are described below with reference to Fig. 6 and 7A to 7E are described in more detail.

[0041] In some embodiments, the etching process of operation 12 may be performed at temperatures from about (-10)°C to about 65°C under a pressure of about 0.00267 mBar (2 mTorr) to about 0.00667 mBar (5 mTorr).

[0042] The etching gas in the etching process of operation 12 does not include a halogen-containing gas. In a dry etching process, such as a plasma etching process, using a halogen-containing etching gas, such as that used in a conventional magnetic layer etching process, non-volatile etching byproducts may be redeposited on the sidewalls of a pattern formed as an etching-resultant structure. Furthermore, halogen-containing etching residues, which degrade the magnetization characteristics of a magnetic layer, may remain on the surface of the pattern formed as an etching-resultant structure, thereby degrading the characteristics of a magnetoresistive device.

[0043] In particular, the dry etching process for forming a magnetic resistance device involves etching a magnetic tunnel junction (MTJ) structure that drives the magnetic resistance device. The MTJ structure includes a free layer, a tunnel barrier layer, and a pinning layer. The tunnel barrier layer in the MTJ structure comprises a ferromagnetic material, such as CoFeB or the like, and magnesium oxide (MgO). The ferromagnetic material and magnesium oxide can be damaged during a dry etching process using a halogen-containing gas, such as chlorine (Cl)-based plasma etching, thereby causing damage to the tunnel barrier layer and corrosion in the MTJ structure.

[0044] On the other hand, in a manufacturing method of a magnetic device according to the inventive concept, a stacked structure including a magnetic layer can be etched using an etching gas containing at least 80% by volume of H2 and no halogen-containing elements, thereby solving the problems of a conventional method.

[0045] Fig. 2 is a flowchart illustrating a manufacturing method of a magnetic device according to another exemplary embodiment of the inventive concept.

[0046] In workflow 22 after Fig. 2, a region to be etched of a stack structure comprising at least one magnetic layer is exposed to a hydrogen plasma, thereby performing a pretreatment on the stack structure.

[0047] In some embodiments, to perform the pretreatment process of operation 22, the stacked structure is loaded into a plasma etching chamber, and only H2 gas is supplied to the chamber, thereby generating a hydrogen plasma. Accelerated reactive hydrogen ions can be supplied to the region of the stacked structure to be etched by the pretreatment process, and a chemical reaction between the region to be etched and the hydrogen ions can occur at the surface of the region to be etched. As a result, when the hydrogen gas ions collide with the region to be etched in the pretreatment process, subsequent chemical and physical etching processes can be easily performed, and an etching rate can be accelerated.

[0048] In some embodiments, the pretreatment process of operation 22 may be performed for approximately 10 seconds to approximately 10 minutes. The pretreatment process of operation 22 may be performed at a temperature of approximately (-10)°C to approximately 65°C under a pressure of approximately 0.00267 mBar (2 mTorr) to approximately 0.00667 mBar (5 mTorr). If necessary, the pretreatment process of operation 22 may be omitted.

[0049] In operation 24, after the pretreatment process, the region to be etched in the stack structure may be etched using an etching gas containing at least 80% by volume of H2 gas. The remaining 20% by volume or less of the etching gas may contain an additional gas, for example, a gas other than hydrogen.

[0050] In some embodiments, the etching of the stacked structure may be performed using a plasma etching process. In some embodiments, the additional gas may include at least one of an inert gas and NH3 gas. For example, the additional gas may include at least one of N2, NH3, Ne, Ar, Kr, and Xe.

[0051] The etching process of operation 24 may be performed after the pretreatment process of operation 22 and in the same chamber. The etching process of operation 24 may be performed at a temperature of approximately (-10)°C to approximately 65°C under a pressure of approximately 0.00267 mBar (2 mTorr) to approximately 0.00667 mBar (5 mTorr).

[0052] When the etching process is performed according to operation 24, accelerated reactive hydrogen ions can be supplied together with accelerated ions of the auxiliary gas to the region of the stack structure to be etched. In the region to be etched, physical etching can be performed by the accelerated ions, simultaneously with a chemical reaction with the accelerated hydrogen ions reaching the surface of the region to be etched. The auxiliary gas contains atoms having a larger atomic weight than that of hydrogen atoms. Therefore, the ions generated from the auxiliary gas collide more strongly with the stack structure to be etched than the hydrogen atoms. As a result, a relatively large physical force is applied to the region of the stack structure to be etched, so that physical etching of the stack structure can be easily performed.

[0053] Fig. 3 is a gas supply pulse graph showing a gas supply workflow in the pretreatment process of Workflow 22, which is shown in Fig. 2, and the etching process from workflow 24, which is shown in Fig. 2. For example, as shown in Fig. 3, ions of the hydrogen gas continuously in the pretreatment process and the etching steps, ie operations 22 and 24 after Fig. 2, while the additional gas, for example N2 gas, can only be supplied during etching.

[0054] In the etching process from workflow 12 according to Fig. 1 and the etching process from workflow 24 according to Fig. 2, the stacked structure having a layer to be etched may comprise various types of magnetic layers. In some embodiments, the stacked structure comprises at least one non-volatile magnetic layer. For example, the stacked structure may comprise a magnetic layer formed from at least one of Co / Pd, Co / Pt, Co / Ni, Fe / Pd, Fe / Pt, MgO, PtMn, IrMn, a CoFe alloy, or a CoFeB alloy.

[0055] The etching process from workflow 12 according to Fig. 1 and the etching process from workflow 24 according to Fig. 2 can be carried out using a plasma generated by an inductively coupled plasma (ICP) source, a capacitively coupled plasma (CCP) source, a cyclotron resonance (ECR) plasma source, a helicon-wave excited plasma (HWEP) source or an adaptively coupled plasma (ACP) source.

[0056] Fig. 4 and Fig. 5 are cross-sectional views of stacked structures 40 and 50 that can be etched using an etching gas containing at least 80% by volume of H2 gas, according to embodiments of the inventive concept. For clarity, repeated description thereof is omitted.

[0057] In more detail, as in Fig. 4, the stacked structure 40 may include a bottom electrode layer 42, a bottom magnetic layer 44, a tunnel barrier layer 45, an top magnetic layer 46, and an top electrode layer 48 stacked sequentially from bottom to top.

[0058] The bottom electrode layer 42 may comprise at least one of, for example, Ti, Ta, Ru, TiN, TaN, or W. In some embodiments, the bottom electrode layer 42 may have a bilayer structure, for example, Ti\Ru, Ta\Ru, TiN\Ru, TaN\Ru, and TiN\Ru. In some embodiments, the bottom electrode layer 42 may have a thickness of approximately 2.0 to 5.0 nm.

[0059] The lower magnetic layer 44 may comprise at least one of, for example, Fe, Co, Ni, Pd, and Pt. In some embodiments, the lower magnetic layer 44 may be formed from a Co-M1 alloy (where M1 is at least one metal selected from the group consisting of Pt, Pd, and Ni) or from an Fe-M2 alloy (where M2 is at least one metal selected from the group consisting of Pt, Pd, and Ni). In some embodiments, the lower magnetic layer 44 may further comprise at least one of C, Cu, Ag, Au, or Cr. In some embodiments, the lower magnetic layer 44 has a thickness of about 1.0 nm to about 5.0 nm.

[0060] The upper magnetic layer 46 may comprise at least one of, for example, Co, a Co-M1 alloy (where M1 is at least one metal selected from the group consisting of Pt, Pd, or Ni), an Fe-M2 alloy (where M2 is at least one metal selected from Pt, Pd, or Ni), Ru, Ta, Cr, and Cu. In some embodiments, the upper magnetic layer 46 has a thickness of approximately 3.0 nm to 20.0 nm.

[0061] In some embodiments, at least one of the lower magnetic layer 44 and the upper magnetic layer 46 comprises a perpendicular magnetic anisotropy (PMA) material. In some embodiments, at least one of the lower magnetic layer 44 and the upper magnetic layer 46 comprises a synthetic antiferromagnet (SAF) structure. The SAF structure is formed by inserting a Ru interlayer into a ferromagnetic stack structure. For example, the SAF structure may comprise a multilayer structure of CoFeB / Ta / (Co / Pt)m / Ru / (Co / Pd)n (where m and n are natural numbers). The SAF structure that can be used in the inventive concept is not limited thereto, and various modified structures can be used.

[0062] The tunnel barrier layer 45, which is disposed between the lower magnetic layer 44 and the upper magnetic layer 46, may be formed from, for example, MgO, Al2O3, B2O3, and / or SiO2. In some embodiments, the tunnel barrier layer 45 has a thickness of approximately 0.5 nm to approximately 3.0 nm.

[0063] The top electrode layer 48 may comprise at least one of, for example, Ti, Ta, Ru, TiN, TaN, and / or W. In some embodiments, the top electrode layer 48 may have a bilayer structure of, for example, T\Ru, Ta\Ru, TiN\Ru, TaN\Ru, or TiN\Ru. In some embodiments, the top electrode layer 48 may have a thickness of about 2.0 nm to about 5.0 nm.

[0064] The lower magnetic layer 44 and the upper magnetic layer 46 of the stacked structure 40 are not limited to the above description and can be modified in various ways. For example, the description of the lower magnetic layer 44 can be applied to the upper magnetic layer 46, and vice versa.

[0065] In some embodiments, the stack structure 40 may be used in the implementation of an MTJ device that uses perpendicular magnetization.

[0066] As in Fig. 5, the stacked structure 50 may include a bottom electrode layer 42, a bottom magnetic layer 44, a tunnel barrier layer 45, an upper magnetic layer 56, and an upper electrode layer 48 stacked sequentially from bottom to top.

[0067] The upper magnetic layer 56 may include a pinned layer 56A and a pinning layer 56B sequentially stacked on the tunnel barrier layer 45. The pinned layer 56A may include at least one ferromagnetic material selected from the group consisting of Co, Fe, Pt, and Pd. The pinned layer 56A may have a SAF structure described in Fig. 4. In some embodiments, the pinned layer 56A may have a thickness of about 3.0 nm to about 5.0 nm.

[0068] The pinning layer 56B may comprise an antiferromagnetic material. In some embodiments, the pinning layer 56B may comprise at least one of, for example, PtMn, IrMn, NiMn, FeMn, MnO, MnS, MnTe, MnF2, FeCl2, FeO, CoCl2, CoO, NiCl2, NiO, or Ni. In some embodiments, the pinning layer 56B has a thickness of approximately 5.0 to 15.0 nm.

[0069] In some embodiments, the stack structure 50 may be used in the implementation of an MTJ device that uses horizontal magnetization.

[0070] Fig. 6 illustrates a schematic view of a plasma etching apparatus 60 that can perform a plasma etching process of a magnetic device manufacturing method according to an embodiment of the inventive concept.

[0071] With reference to Fig. 6, the plasma etching apparatus 60 may include a chamber 62, a source electrode 63, and a bias electrode 64. The bias electrode 64 serves as a holding device for supporting a substrate W. The source electrode 63 may have a helical structure, with the chamber 62 being wound multiple times.

[0072] A radio frequency (RF) source current may be applied to source electrode 63, and an RF bias current may be applied to bias electrode 64. An etching gas used in plasma etching flows into chamber 62 via gas inlet 65. Unreacted etching gas and reaction byproducts remaining after etching are discharged from chamber 62 using a turbomolecular pump (TMP).

[0073] In a plasma etching apparatus using a CCP method, a flat type electrode arranged in the chamber 62 near the gas inlet 65 may be used instead of the source electrode 63.

[0074] The plasma etching apparatus 60 may further include a source current output unit 66 and a bias current output unit 68. The source current output unit 66 and the bias current output unit 68 may each output a source current and a bias current in a mode suitable for performing a synchronous pulse plasma etching process.

[0075] The source current delivery unit 66 may include a source balancing network 66A, a source mixer 66B, a source controller 66C, and a source RF generator 66B. The bias current delivery unit 68 may include a bias balancing network 68A, a bias mixer 68B, a bias controller 68C, and a bias RF generator 68D.

[0076] The source current output from the source current output unit 66 is applied to the source electrode 63. The source electrode 63 serves to generate plasma in the chamber 62. The bias current output from the bias current output unit 68 is applied to the bias electrode 64. The bias electrode 64 serves to adjust the ion energy entering the substrate W.

[0077] The source controller 66C of the source current output unit 66 can output a pulse-modulated RF source current having a first frequency and a first duty cycle, and can output a control signal to the RF bias current output unit 68, including information regarding a phase of the RF source current. The source mixer 66B receives a source RF signal output from the source RF generator 66D and a source pulse signal output from the source controller 66C and mixes them, thereby outputting a pulse-modulated RF source current.

[0078] The bias current output unit 68 outputs an RF bias current to the bias electrode 64 in response to the control signal output from the source current output unit 66, said RF bias current having a second frequency and a second duty cycle.

[0079] In some embodiments, the RF bias current is applied to the bias electrode from the bias current delivery unit 68 so that ions of the plasma formed on the substrate W in the chamber 62 have a directional characteristic.

[0080] A heater (not shown) for heating the substrate W supported on the operating point electrode 64 and a temperature sensor (not shown) for controlling the internal temperature of the chamber 62 may additionally be arranged on the underside of the operating point electrode 64 or in the operating point electrode 64.

[0081] In some embodiments, the source current output unit 66 and the bias current output unit 68 can each be controlled to selectively output current in a constant wave mode or current in a pulsed mode, as needed. To this end, the source current output unit 66 and the bias current output unit 68 can each function to control the interactive conversion of an on-state and an off-state of the power output. For example, the on-state and off-state of each of the source current output unit 66 and the bias current output unit 68 can be controlled such that a source current in the pulsed mode and an bias current in the pulsed mode can be output by the source current output unit 66 and the bias current output unit 68, respectively.

[0082] Fig. 7A is a graph of source current output in a constant wave mode in the plasma etching apparatus 60 as a function of time. Fig. 7B is a graph of operating point current output in the constant wave mode in the plasma etcher 60 as a function of time. Fig. 7C is a graph of a duty cycle D of a source current output in a pulsed mode in the plasma etching apparatus 60 as a function of time. Fig. 7D is a graph of a duty cycle D of a pulsed mode operating point current output in the plasma etching apparatus 60 as a function of time.

[0083] In Fig. 7C and Fig. 7D, an on-state time T1 and an off-state time T2 may be set in different ways. The on-state time T1 and the off-state time T2 may or may not be the same. The on-state time T1 and the off-state time T2 may be arbitrarily selected according to the quality and thickness of the layer to be etched, an etching atmosphere, or the like. In some embodiments, the on-state time T1 and the off-state time T2 may be set to vary as the process time elapses.

[0084] Fig. 7E is a graph showing a duty cycle D of a source current and a bias current as a function of time, which are output in a pulsed mode to perform an etching process using synchronous pulse plasma etching of the plasma etcher 60.

[0085] Fig. 8 to 8C are cross-sectional views of steps in a manufacturing process of a magnetic device 80 (see Fig. 8C) according to another embodiment of the inventive concept. In the present embodiment, the manufacturing method of the magnetic device 80 including a method of etching the stack structure 40 is Fig. 4 described.

[0086] With reference to Fig. 8A, the stack structure 40, which with reference to Fig. 4, may be formed on a lower structure, ie, a structure including an interlayer insulating layer 82 and a lower electrode contact 84 formed by the interlayer insulating layer 82. Then, a mask pattern 86 for exposing a portion of the upper surface of the upper electrode layer 84 may be formed on the stacked structure 40.

[0087] The mask pattern 86 may be formed on the stacked structure 40 on the same axis as the bottom electrode contact 84. For example, the mask pattern 86 may be parallel and overlapping with respect to the bottom electrode contact 84. In some embodiments, the mask pattern 86 may comprise at least one of, for example, Ru, W, TiN, TaN, Ti, and Ta. In some embodiments, the mask pattern 86 may have a two-layer structure, for example, Ru\TiN or TiN\W, and have a thickness of approximately 30.0 nm to approximately 80.0 nm.

[0088] With reference to Fig. 8B, the resulting structure can be seen from Fig. 8A into the plasma etching chamber. For example, the resulting structure can be Fig. 8A onto the working point electrode 64 in the chamber 62 of the plasma etching device 60.

[0089] Next, similar to workflow 22, Fig. 2, the exposed region of the upper electrode layer 84 of the stacked structure 40 is exposed to a hydrogen plasma 88 in the chamber 62, thereby performing the pretreatment of the stacked structure 40. The pretreatment process using the hydrogen plasma 88 may be omitted if necessary.

[0090] With reference to Fig. 8C, similar to workflow 24 after Fig. 2, the pre-processed stack structure 40 may be anisotropically etched using an etching gas containing at least 80% by volume of H2 gas and a remaining additional gas, and using the mask pattern 86 as an etching mask.

[0091] The etching of the stacked structure 40 may be performed by a plasma etching method. As a structure of the stacked structure 40 resulting from the etching, a plurality of magnetic devices 80 may be formed, each comprising a lower electrode 42A, a lower magnetic layer pattern 44A, a tunnel barrier layer 45A, an upper magnetic layer pattern 46A, an upper electrode 48A, and the remaining mask pattern portion 86, which are stacked sequentially from bottom to top. In each of the plurality of magnetic devices 80, the remaining mask pattern portion 86 and the upper electrode 48A serve as an electrode. Each of the plurality of magnetic devices 80 may be electrically connected to the lower electrode contact 84. While the stacked structure 40 is being etched, a portion of the stacked structure 40 may be consumed by etching from an upper surface of the mask pattern 86, i.e.,a total thickness of the pattern portion 86 after the anisotropic etching may be reduced in relation to the total thickness before the anisotropic etching.

[0092] For example, the etching gas may contain about 80% to about 95% by volume of H2 gas and about 5% to about 20% by volume of additional gas. In some embodiments, the additional gas may contain, for example, at least one of N2, NH3, Ne, Ar, Kr, and Xe.

[0093] The etching process of the stack structure 40 can be carried out in the same chamber as, for example, and subsequent to the pretreatment process according to Fig. 8B. In some embodiments, the etching of the stack structure 40 may be performed in an atmosphere in which a relatively high ion energy and a relatively low plasma density are maintained. For example, when the stack structure 40 is etched, an ion energy higher than approximately 500 eV and a plasma density lower than approximately 1 × 10 11 cm -3 , be maintained. The etching process of the stack structure 40 can be carried out at a temperature of approximately (-10)°C to approximately 65°C under a pressure of approximately 0.00267 mBar (2 mTorr) to approximately 0.00667 mBar (5 mTorr).

[0094] Fig. 9A to 9C are cross-sectional views of steps in a manufacturing method of a magnetic device 90 (see Fig. 9C) according to another exemplary embodiment of the inventive concept. In the present embodiment, the manufacturing method of the magnetic device 90 including the method of etching the stack structure 50 is Fig. 5 described.

[0095] With reference to Fig. 9A, the stack structure 50, ie as described with reference to Fig. 5, may be formed on the lower structure including the interlayer insulating layer 82 and the lower electrode contact 84. A mask pattern 96 for exposing a portion of the upper surface of the upper electrode layer 48 may be formed on the stacked structure 50.

[0096] The mask pattern 96 may be formed on the stacked structure 50 on the same axis as the bottom electrode contact 84. In some embodiments, the mask pattern 96 may include at least one of, for example, Ru, W, TiN, TaN, Ti, and Ta. In some embodiments, the mask pattern 96 may have a two-layer structure, for example, Ru\TiN or TiN\W. The mask pattern 96 may have a thickness of approximately 30.0 nm to approximately 80.0 nm.

[0097] With reference to Fig. 9B, the resulting structure can be Fig. 9A into a plasma etching chamber. For example, the resulting structure comprising the mask pattern 96 can be applied to the operating point electrode 64 in the chamber 62 of the plasma etching apparatus 60 according to Fig. 6 can be loaded.

[0098] Next, the exposed region in the upper electrode layer 48 in the stack structure 50, as in operation 22 after Fig. 2, are exposed to the hydrogen plasma 98 in the chamber 62, whereby the pretreatment of the stack structure 50 is carried out.

[0099] With reference to Fig. 9C, the stack structure 50 pre-processed in a plasma state of the etching gas may be anisotropically etched using the mask pattern 96 as an etching mask and using the etching gas containing at least 80% by volume of H2 gas and the remaining additional gas, as in operation 24 after Fig. 2 described.

[0100] The etching of the stacked structure 50 may be performed by a plasma etching method. As a structure of the stacked structure 50 resulting from the etching, a plurality of magnetic devices 90 may be formed, each including a lower electrode 42A, a lower magnetic layer pattern 44A, a tunnel barrier layer 45A, an upper magnetic layer pattern 56P, an upper electrode 48A, and the remaining mask pattern portion 96, which are stacked sequentially from bottom to top. In each of the plurality of magnetic devices 90, the remaining mask pattern portion 96 and the upper electrode 48A serve as an electrode. Each of the plurality of magnetic devices 90 is electrically connected to the lower electrode contact 84. While the stacked structure 50 is being etched, a portion of the stacked structure 50 from an upper surface of the mask pattern 96 may be consumed by etching.

[0101] For example, the etching gas may contain about 80% to about 95% by volume of H2 gas and about 5% to about 20% by volume of an additional gas. In some embodiments, the additional gas may contain at least one of, for example, N2, NH3, Ne, Ar, Kr, or Xe.

[0102] The etching process of the stack structure 50 can be carried out in the same chamber as the pretreatment process according to Fig. 9B and subsequent to the pretreatment process. In some embodiments, the etching of the stack structure 50 may be performed in an atmosphere in which a relatively high ion energy and a relatively low plasma density are maintained. For example, when the stack structure 50 is etched, an ion energy higher than approximately 500 eV and a plasma density lower than approximately 1 × 10 11 cm -3, be maintained. The etching process of the stack structure 50 can be carried out at a temperature of approximately (-10)°C to approximately 65°C under a pressure of approximately 0.00267 mBar (2 mTorr) to approximately 0.00667 mBar (5 mTorr).

[0103] In the manufacturing process of the magnetic device 80 shown in Fig. 8A to 8C, and the manufacturing process of the magnetic device 90 shown in Fig. 9A to 9C, the plasma etching device 60 can be Fig. 6 can be used to carry out the etching process of the stack structure 40 or 50. In the plasma etching device 60, a source current and a working point current can be delivered in a constant wave mode, as in Fig. 7A and Fig. 7B, respectively, while the stack structure 40 or 50 is being etched. In some embodiments, while the stack structure 40 or 50 is being etched, the source current in the pulsed mode or the bias current in the pulsed mode in which the source or bias current alternates between an on-state and an off-state, as in Fig. 7C or Fig. 7D. In some embodiments, while the stack structure 40 or 50 is being etched, a synchronous pulse plasma etching process, as shown in Fig. 7E, the source current in the pulsed mode and the operating point current in the pulsed mode are applied simultaneously.

[0104] Each of the stack structures 40 and 50 may include a non-volatile material layer, e.g., a layer of Pt, Pd, Co, Mg, Fe, Ir, and / or the like, which cannot be easily etched by a conventional method. Since the saturation vapor pressure of a reaction material generated during an etching process of a non-volatile material is very low compared to other etching materials, e.g., compared to volatile materials, the non-volatile materials may have very low etch rates during the etching process. Accordingly, reaction products, e.g., etching byproducts of the non-volatile materials, may be redeposited during the etching process on the sidewalls of a pattern formed after the etching.If etching byproducts are redeposited on the sidewalls of the pattern in this way, the sidewall profile of the final pattern formed as a result of etching may be steeply sloped, making it difficult to control a critical dimension (CD). Additionally, if reaction byproducts of a non-volatile metal are redeposited on the sidewalls of the pattern, an electrical short circuit may occur between the bottom electrode and a top electrode, which in turn may degrade the MTJ.

[0105] On the other hand, in the manufacturing method of a magnetic device according to the inventive concept, when the stacked structure 40 or 50 comprising a non-volatile magnetic layer is etched, the stacked structure 40 or 50 is etched using an etching gas comprising at least 80% by volume of H2 gas and a remainder of an additional gas. In this regard, the stacked structure 40 or 50 can be etched in a single step from the upper electrode layer 48 to the lower electrode layer 42 and divided into the plurality of magnetic devices 80 or 90. As a result of etching the stacked structure 40 or 50 using the etching gas comprising at least 80% by volume of H2 gas and a remainder of an additional gas, etching byproducts can be prevented from redepositing on each etched surface, i.e.Side walls 80S of the plurality of magnetic devices 80 or side walls 90S of the plurality of magnetic devices 90 in the respective . Fig. 8C and Fig. 9C, and a magnetic device may have vertical sidewall profiles, ie, a sidewall extending along a normal to the surface on which the magnetic devices 80 or 90 are supported.

[0106] Fig. 10A represents moving paths 10A of ions A+ / - while the stack structure 40 is etched under a condition that a source current and a bias current are respectively output in constant wave modes.

[0107] In detail, Fig. 10A shows movement paths 10A of accelerated ions A+ / generated from the etching gas while the stack structure 40 is being formed by the method described with reference to Fig. 8C, is etched using the plasma etching apparatus 60 under the condition that the source current and the operating point current are respectively in constant wave modes as shown in Fig. 7A and Fig. 7B.

[0108] Fig. Figure 10B illustrates movement paths 10B of ions A+ / - generated from the etching gas in a synchronous pulse plasma etching process.

[0109] In detail, Fig. 10B illustrates the movement paths 10B of accelerated ions A+ / - generated from the etching gas when the stack structure 40 is formed using the method described with reference to Fig. 8C, is etched using a plasma etching apparatus 60 under a condition that the source current and the operating point current are each in the pulsed mode described in Fig. 7E, thereby performing the synchronous pulse plasma etching process.

[0110] As from Fig. 10A and Fig. 10B, the range of motion of the accelerated ions A+ / - increases when the synchronous pulse plasma etching process is carried out ( Fig. 10B) compared to the use of constant wave modes by the source current and the operating point current ( Fig. 10A). Therefore, the movement range in which the accelerated ions A+ / - are distributed increases. Furthermore, even if byproducts are redeposited on the sidewalls 80S, due to the large number of accelerated ions A+ / - that are moved in the increased movement range, the redeposited byproducts can be removed. Such an effect also relates to the etching process of the stack structure 50, which is described with reference to Fig. 9C. Therefore, even when a stacked structure including a plurality of magnetic layers is etched to manufacture the magnetic device 80 or 90 having a very fine thickness of several tens of nm, e.g., approximately 20 nm, the stacked structure including a plurality of magnetic layers can be etched using the magnetic device manufacturing method according to the inventive concept, so that miniaturized magnetic devices all having vertical sidewall profiles can be easily manufactured due to the highly anisotropic etching that can be performed without redepositing the etching byproducts.

[0111] Fig. 11 is a flowchart of a manufacturing method of a magnetic device according to another exemplary embodiment of the inventive concept.

[0112] In workflow 112 after Fig. 11, a mask pattern may be formed on a stacked structure including a lower magnetic layer, a tunnel barrier layer, and an upper magnetic layer stacked sequentially from bottom to top to cover a portion of the stacked structure.

[0113] In some embodiments, the stack structure may further comprise a lower electrode layer and an upper electrode layer formed under the lower magnetic layer, the tunnel barrier layer, and the upper magnetic layer disposed between the lower electrode layer and the upper electrode layer. The stack structure may comprise a magnetic layer formed of, for example, at least one of Co / Pd, Co / Pt, Co / Ni, Fe / Pd, Fe / Pt, MgO, PtMn, IrMn, a CoFe alloy, and a CoFeB alloy. For example, the stack structure may comprise the stack structure 40 or 50 according to Fig. 4 or Fig. 5 include.

[0114] The mask pattern may comprise at least one selected from, for example, Ru, W, TiN, TaN, Ti, and Ta. In some embodiments, the mask pattern may comprise a two-layer structure of, for example, Ru\TiN or TiN\W.

[0115] In operation 114, an upper surface of a resulting structure, i.e., a stacked structure, from operation 112 may be exposed to a hydrogen plasma to perform a pretreatment of the stacked structure. In some embodiments, to perform the pretreatment process using hydrogen plasma, a structure comprising the stacked structure may be loaded into the chamber 62 of the plasma etching apparatus 60, and hydrogen plasma is generated by supplying only H2 gas into the chamber 62. A more detailed description of the pretreatment process in operation 114 is substantially the same as the pretreatment process described in operation 22 after Fig. 2. Therefore, a detailed description of it has been omitted. If necessary, workflow 114 can be omitted.

[0116] In operation 116, a first etching process may be performed for etching a first portion, including at least the upper magnetic layer and the tunnel barrier layer, from the exposed upper surface of the stacked structure using a first etching gas containing at least 80% by volume of H2 gas and a remainder of a first additional gas and using the mask pattern formed in operation 112 as an etching mask.

[0117] In operation 116, the first etching process may be performed using a plasma etching process. To perform the first etching process, the plasma etching device 60 shown in Fig. 6. The first etching process may be performed in the same chamber 62 and subsequent to the pretreatment process according to operation 114.

[0118] The first additional gas may, for example, contain at least one of inert gas and NH3 gas. For example, the first additional gas may contain at least one of N2, Ne, Ar, Kr, or Xe.

[0119] While the first etching process is being performed in operation 116, a source current and a bias current may each be delivered in constant modes, as shown in Fig. 7A and Fig. 7B. In some embodiments, while the first etching process is being performed, a source current or a bias current may be delivered in a pulsed mode in which the source or bias current alternates between an on-state and an off-state, as shown in Fig. 7C or Fig. 7D. In some embodiments, while the first etching process is being performed, a synchronous pulse plasma etching process, as in Fig. 7E, the source current in the pulsed mode and the bias current in the pulsed mode may be output simultaneously or with a predetermined time difference. The first etching process of operation 116 may be performed at a temperature of approximately (-10)°C to approximately 65°C under a pressure of approximately 0.00267 mBar (2 mTorr) to approximately 0.00667 mBar (5 mTorr).

[0120] If the stack structure 40 after Fig. 4 is etched in operation 116, after the first etching process is performed, the upper electrode 48, the upper magnetic layer 46 and the tunnel barrier layer 45 are respectively divided into a plurality of upper electrodes of a plurality of upper magnetic patterns and a plurality of tunnel barriers.

[0121] In operation 118, a second etching process is performed for etching a second portion comprising the lower magnetic layer of the stacked structure using a second etching gas containing at least 80% by volume of H2 gas and a remainder of a second additional gas, and using the mask pattern as an etching mask. When the stacked structure 40 is Fig. 4 is etched in operation 118, after the second etching process, the lower magnetic layer 44 and the lower electrode layer 42 are divided into a plurality of lower magnetic patterns and a plurality of lower electrodes.

[0122] The second etching process in operation 118 may be performed using a plasma etching process. To perform the second etching process, the plasma etching device 60 shown in Fig. 6. The second etching process may be performed in the same chamber 62 as and subsequent to the first etching process from operation 116.

[0123] The second additional gas may include, for example, at least one of inert gas and NH3 gas. The second additional gas may include, for example, at least one of N2, Ne, Ar, Kr, or Xe. In some embodiments, the second additional gas may include a gas that is different from the first additional gas used in operation 116. For example, N2 gas may be used as the first additional gas in operation 116, and NH3 gas may be used as the second additional gas in operation 118.

[0124] While the second etching process is being performed in operation 118, in the plasma etching apparatus 60, a source current and a bias current may be output in constant wave modes, respectively, as shown in Fig. 7A and Fig. 7B. In some embodiments, while the second etching process is being performed, a source current or a bias current may be applied in a pulsed mode in which the source or bias current alternates between an on-state or an off-state, as shown in Fig. 7C or Fig. 7D. In some embodiments, while the second etching process is performed to perform a synchronous pulse plasma etching process, the source current in the pulsed mode and the bias current in the pulsed mode may be as shown in Fig. 7E, simultaneously or with a predetermined time difference. The second etching process of operation 118 may be performed at temperatures from about (-10)°C to about 65°C under a pressure from about 0.00267 mBar (2 mTorr) to about 0.00667 mBar (5 mTorr).

[0125] In some embodiments, a delivery mode of each of the source current and the bias current for the second etching process according to operation 118 may be set differently than a delivery mode of each of the source current and the bias current for the first etching process according to operation 116. For example, when the first etching process is performed in operation 116, the source current and the bias current may be delivered in the constant-wave modes, respectively, as shown in Fig. 7A and Fig. 7B, and when the second etching process is performed in operation 118, the source current in the pulsed mode and the bias current in the pulsed mode may be as shown in Fig. 7E, so that the synchronous pulse plasma etching process is carried out.

[0126] The second etching process of operation 118 may be performed under the synchronous pulse plasma etching process condition, so that accelerated ions generated from the etching gas are moved in the enlarged movement range and collide with the region to be etched. In the region of the stacked structure to be etched, a chemical reaction is carried out with accelerated hydrogen ions reaching the surface of the region. At the same time, physical etching by the accelerated ions obtained from the second additional gas can be uniformly carried out in the region to be etched. Therefore, the hydrogen ions and the accelerated ions generated from the second additional etching gas can be more effectively used in performing highly anisotropic etching of a layer to be etched and removing a redeposited layer.As a result, fine magnetic resistance devices can be easily formed, each having a vertical sidewall profile, and byproducts can be prevented from redepositing on the sidewalls of the pattern obtained after etching. Therefore, an additional cleaning process or post-treatment process for removing the redeposited etching byproducts is not performed.

[0127] Fig. 12A to 12H are cross-sectional views of steps in a manufacturing method of a magnetic device 200 (see Fig. 12H) according to another exemplary embodiment of the inventive concept. The present embodiment illustrates a manufacturing method of a spin transfer torque magnetoresistive random access memory (STT-MRAM) device as a method for manufacturing the magnetic device 200.

[0128] With reference to Fig. 12A, an insulating layer 204 may be formed on a substrate 202 to define an active region 206. At least one transistor 210 may be formed in the active region 206.

[0129] In some embodiments, the substrate 202 may be a semiconductor wafer. In at least one embodiment, the substrate 202 may comprise, for example, silicon (Si). In some embodiments, the substrate 202 may comprise a semiconductor element, for example, Ge, or a compound semiconductor, for example, SiC, GaAs, or InP. In at least one embodiment, the substrate 202 may have a silicon-on-insulator (SOI) structure. For example, the substrate 202 may comprise a buried-oxide (BOX) layer. In some embodiments, the substrate 202 may include a conductive region, for example, an impurity-doped recess or an impurity-doped structure. The insulation layer 204 may have a shallow-trench-isolation (STI) structure.

[0130] Transistor 210 may include a gate insulation layer 212, a gate electrode 214, a source region 216, and a drain region 218. Gate electrode 214 may be shaped such that a top surface and both sidewalls of gate electrode 214 are each insulated by an insulating cap layer 220 and an insulating spacer 222.

[0131] Next, a planarized first interlayer insulating layer 230 for covering the transistor 210, a plurality of first contact plugs 232 penetrating the first interlayer insulating layer 230 and electrically connected to the source region 216, and a plurality of second contact plugs electrically connected to the drain region 218 may be sequentially formed on the substrate 202. After a conductive layer is formed on the first interlayer insulating layer 230, the second conductive layer may be patterned, thereby forming a plurality of source lines 236 electrically connected to the source region 216 via the plurality of first contact plugs 232 and a plurality of conductive patterns 238 electrically connected to the drain region 218 via the plurality of second contact plugs 234 on both sides of the source lines 236.

[0132] Next, a second interlayer insulating layer 240 may be formed on the first interlayer insulating layer 230 to cover the source lines 236 and the conductive patterns 238. By using a photolithographic process, a portion of the second interlayer insulating layer 240 may be removed to expose a top surface of the conductive patterns 238, thereby forming a bottom electrode contact recess 240H. By filling a conductive material into the bottom electrode contact recess 240H and polishing the conductive material to expose a top surface of the second interlayer insulating layer 240, a bottom electrode contact plug 242 may be formed in the bottom electrode contact recess 240H. In some embodiments, the bottom electrode contact plug 242 may comprise, for example, at least one of TiN, Ti, TaN, Ta, or W.

[0133] With reference to Fig. 12B, a stacked structure 250 in which a lower electrode layer 252, a lower magnetic layer 254, a tunnel barrier layer 255, an upper magnetic layer 256, and an upper electrode layer 258 are sequentially stacked from bottom to top may be formed on the second interlayer insulating layer 240 and the lower electron contact plug 242.

[0134] The stack structure 250 may replace the stack structure 40 or 50 after Fig. 4 or Fig. 5. However, aspects of the inventive concept are not limited thereto, and different types of layers may be added or replaced according to the desired characteristics of a magnetic device to be formed.

[0135] With reference to Fig. 12C, a plurality of conductive mask patterns 260 are formed on the stacked structure 250 to cover a portion of a top surface of the stacked structure 250. The plurality of conductive mask patterns 260 may comprise a metal or metal nitride. In some embodiments, the plurality of conductive mask patterns 260 may comprise, for example, at least one of Ru, W, TiN, TaN, Ti, and Ta. For example, the conductive mask patterns may have a two-layer structure of Ru\TiN or TiN\W. The conductive mask patterns 260 may be formed on the same axis as that of the bottom electrode contact plugs 242. For example, the conductive mask patterns 260 may be aligned with the bottom electrode contact plugs 242 along a vertical axis normal to the substrate 202.

[0136] In some embodiments, to form the plurality of conductive mask patterns 260, a conductive mask layer may first be formed on the stacked structure 250, and a plurality of hard mask patterns (not shown) may be formed on the conductive mask layer. The conductive mask layer may be etched using the plurality of hard mask patterns as an etch mask, so that the plurality of conductive mask patterns 260 may remain on the stacked structure 250.

[0137] With reference to Fig. 12D, an exposed upper surface of the stack structure 250 may be exposed to the hydrogen plasma 262 through the conductive mask pattern 260 to perform the pretreatment of the exposed upper surface of the stack structure 250. The pretreatment process using the hydrogen plasma 262 is the same as workflow 22 according to Fig. 2 and the pretreatment process using hydrogen plasma as described with reference to Fig. 8B and Fig. 9B. The pretreatment process using the hydrogen plasma 262 may be omitted if necessary.

[0138] With reference to Fig. 12E, a first etching process for etching the upper electrode layer 258, the upper magnetic layer 256, and the tunnel barrier layer 255 may be performed using a plasma etching process using a first etching gas containing at least 80% by volume of H2 gas and a remainder of a first additional gas, and using the conductive mask patterns 260 as an etching mask. As a result, a plurality of upper electrodes 258A, a plurality of upper magnetic layer patterns 256A, and a plurality of tunnel barrier layers 255A may be formed. The first etching process according to Fig. 12E is essentially the same as workflow 116 according to Fig. 11. While the first etching process is being performed, a portion of the plurality of conductive mask patterns 260 may be consumed from their surfaces due to an etching atmosphere of the first etching process.

[0139] While the first etching process is being performed, the lower magnetic layer 254, which is exposed after the plurality of tunnel barrier layers 255A are formed, may be further etched from its upper surface to a predetermined thickness, thereby completing the first etching process. In some embodiments, atomic emission spectrometry may be used to determine an end point of the first etching process. To perform the first etching process with the lower magnetic layer 254 set as the end point, the first etching process may be performed until an emission wavelength of one of the elements of the lower magnetic layer 254 is detected in the atomic emission spectrometry.

[0140] In some embodiments, the first etching process may be carried out in a state in which a source current and a bias current applied to generate the etching atmosphere of the first etching process are respectively in the constant wave modes shown in Fig. 7A and Fig. 7B are shown.

[0141] With reference to Fig. 12F, a second etching process for etching the lower magnetic layer 254 exposed between the plurality of conductive mask patterns 260 and the lower electrode layer 252 under the lower magnetic layer 254 of the stacked structure 250 (see Fig. 12B) using a second etching gas containing at least 80% by volume of H2 gas and a remainder of a second additional gas, and using the conductive mask pattern 260 as an etching mask. As a result, a plurality of lower magnetic layer patterns 254A and a plurality of lower electrodes 252A can be formed. The second etching process according to Fig. 12F is essentially the same as workflow 118 according to Fig. 11.

[0142] In some embodiments, approximately 80% by volume to approximately 95% by volume of H2 gas and approximately 5% by volume to approximately 20% by volume of the second additional gas may be used as the second etching gas. For example, the second additional gas may include at least one of N2, NH3, Ne, Ar, Kr, or Xe. In some embodiments, the second additional gas includes a gas that is different from the first additional gas. For example, when N2 is used as the first additional gas, NH3 may be used as the second additional gas.

[0143] The second etching process may be carried out in an atmosphere having an ion energy higher than about 500 eV and a plasma density lower than about 1 × 10 11 cm -3, can be maintained. The second etching process may be performed at a temperature of approximately (-10)°C to approximately 65°C under a pressure of approximately 0.00267 mBar (2 mTorr) to approximately 0.00667 mBar (5 mTorr). While the second etching process is being performed, a portion of the plurality of conductive mask patterns 260 may be consumed from their upper surfaces due to an etching atmosphere of the second etching process. Although not shown, the second interlayer insulating film 240, which is exposed after the plurality of lower electrodes 252A are formed when the second etching process is performed, may be etched from its upper surface by a predetermined thickness.

[0144] As a result of the second etching process, a plurality of magnetic resistance devices 270 are formed on the plurality of lower electrode plugs 242, including the lower electrodes 252A, the lower magnetic layer patterns 254A, the tunnel barrier layers 255A, the upper magnetic layer patterns 256A, the upper electrodes 258A, and the remaining conductive mask pattern portions 260. In the plurality of magnetic resistance devices 270, the remaining conductive mask pattern portions 260 and the upper electrodes 258A serve as one electrode.

[0145] The plurality of magnetic resistance devices 270 can be formed by performing the first etching process according to Fig. 12E and the second etching process according to Fig. 12F, each using the etching gas containing at least 80% by volume of H2 gas. The plurality of magnetic resistance devices 270 may have sidewalls 270S with a substantially vertical sidewall profile, i.e., the sidewalls 270 may extend substantially along a normal to the substrate 202 without inclinations, e.g., rises, or byproduct deposits thereon. Thus, during the first etching process according to Fig. 12E and the second etching process according to Fig. 12F, etching residues, e.g., non-volatile materials, can be prevented from redepositing on the sidewalls 270S of the magnetic resistance devices 270. This can prevent deterioration of the characteristics of the magnetic resistance devices 270 by byproducts redeposited on the sidewalls 270S, and eliminate an additional cleaning process or post-treatment process for removing redeposited byproducts from the sidewalls 270S, thereby simplifying the manufacturing process of the magnetic resistance devices 270.

[0146] In addition, even when a width W of each of the plurality of magnetic resistance devices 270 has a very fine size of several tens of nm, for example, approximately 20 nm, highly anisotropic etching can be performed on the stacked structure 250 without redeposition of etching byproducts. Therefore, fine magnetic devices with a high aspect ratio, each having a vertical sidewall profile, can be easily manufactured.

[0147] In some embodiments, a height H of each magnetic device 270 is at least 1.5 times a width W of the magnetic resistance device 270. For example, the height H of the magnetic resistance device 270 may be about 1.5 to about 3.5 times the width W of the magnetic resistance device 270. In some embodiments, a width of the tunnel barrier layer 255A may be given as a basis for the width W of the magnetic resistance device 270. In this regard, the height H of the magnetic resistance device 270 may be at least 1.5 times the width of the tunnel barrier layer 255A.

[0148] With reference to Fig. 12G, a planarized third interlayer insulating layer 280 may be formed to cover the plurality of magnetic resistance devices 270, and a portion of the third interlayer insulating layer 280 may be removed by etching to form a plurality of bitline contact recesses 280A exposing a top surface of the conductive mask patterns 260 of each of the magnetic resistance devices 270. Next, after a conductive layer for filling the plurality of bitline contact recesses 280H is formed, the conductive layer may be polished or etched until a top surface of the third interlayer insulating layer 280 is exposed, thereby forming a plurality of bitline contact plugs 282 in each of the plurality of bitline contact recesses 280H.

[0149] With reference to Fig. 12H, a conductive layer may be formed and patterned on the third interlayer insulating layer 280 and the plurality of bit line contact plugs 282, thereby forming bit lines 290 having, for example, a linear shape and each electrically connected to the plurality of bit line contact plugs 282 to form the magnetic device 200.

[0150] Fig. 13 is a graph showing an estimation result of the etching and redeposition rates of a stacked structure including a magnetic layer according to embodiments as a function of the H2 concentration in the etching gas according to an embodiment of the inventive concept.

[0151] For the assessment of Fig. 13, a stack structure made of Ti (2.0 nm) \Ru 2.0 nm) \Ta (0.4 nm) \CoFeB (1.1 nm) \MgO (1.0 nm) \CoFeB (1.2 nm) \Ta (0.4 nm) \Co (0.5 nm) \Pt (1.0 nm) \ [Co (0.25 nm) \Pd (1.0 nm)]×3\Co (0.5 nm) \Ru (0.8 nm) \Co (0.5 nm) \ [Pd (1.0 nm) \Co (0.25 nm)]×7\Pd (1.0 nm) \Ti (1.0 nm) \Ru (5.0 nm) stacked sequentially from bottom to top are used. To etch the stacked structure, conductive mask patterns comprising a structure of Ru (50.0 nm)\TiN (60.0 nm) were formed on the stacked structure, and the stacked structure was etched using the conductive mask patterns as an etching mask. Samples for evaluation were etched using an etching gas under various conditions described in Fig. 13. A process temperature, a process pressure, a source current, and a bias current for etching were set to 230°C, 0.00267 mBar (2 mTorr), 500 W, and 350 W, respectively. As shown in Fig. As seen in Figure 13, the redeposition rate of by-products on the sidewalls decreased as a concentration of H2 gas in the etching gas increased.

[0152] Fig. 14 illustrates virtual scanning electron microscope (VSEM) photographs of an estimation result of the dependence of a stack structure including a magnetic layer according to embodiments on an H2 gas concentration in the etching gas according to an embodiment of the inventive concept.

[0153] For the assessment of Fig. 14, the stack structure and conductive mask patterns were used, which were used in the assessment of Fig. 13, and the same etching atmosphere condition was used. Fig. Figure 14 shows resulting structures formed by etching the stacked structure from its top surface to a MgO layer, i.e., a tunnel barrier layer, under the etching condition as described above. As in Fig. As seen in Figure 14, the sidewalls of an etched pattern had a vertical profile and the redeposition of by-products was prevented when the concentration of H2 gas in the etching gas was 80% by volume or more.

[0154] Fig. 15 illustrates a VSEM photograph of a structure formed by etching a stacked structure including a magnetic layer using a manufacturing method of a magnetic device according to an embodiment of the inventive concept.

[0155] For the assessment of Fig. 15, a stacked structure of Ti (2.0 nm) \Ru (2.0 nm) \Ta (0.4 nm) \CoFeB (1.1 nm) \MgO (1.0 nm) \CoFeB (1.2 nm) \Ta (0.4 nm) \Co (0.5 nm) \Pt (1.0 nm) \ [Co (0.25 nm) \Pd (1.0 nm)]×3\Ru (0.8 nm) \CoPt (8.0 nm) \Ru (5.0 nm), stacked sequentially from bottom to top, was used. To etch the stacked structure, conductive mask patterns having a structure of TiN (10.0 nm) \W (60.0 nm) were formed on the stacked structure, and the stacked structure was etched using the conductive mask patterns as an etching mask.

[0156] To etch the stacked structure, a first etching process was performed from the Ru layer, i.e., an upper electrode, to the MgO layer, i.e., the tunnel barrier layer, using the plasma obtained from a first etching gas containing 90% by volume of H2 gas and 10% by volume of N2 gas. A process temperature, a process pressure, a source current, and a bias current for the first etching process were 60°C, 0.00267 mBar (2 mTorr), 350 W, and 600 W, respectively. In the first etching process, a bias current was applied in a constant-wave mode. Next, a second etching process was performed from the CoFeB layer to a Ti layer, which is a lower electrode, using a plasma obtained from a second etching gas containing 80% by volume of H2 gas and 20% by volume of NH3 gas.A process temperature, a process pressure, a source current, and a bias current for the second etching process were 60°C, 0.00267 mBar (2 mTorr), 750 W, and 350 W, respectively. In the second etching process, a bias current was applied in a pulsed mode. As a result, a variety of MTJ devices were fabricated. Fig. 15 are shown.

[0157] In the photograph from Fig. 15, reference numerals 412 and 414 respectively denote a TiN layer and a W layer, each of which is used as an etching mask, and reference numeral 416 denotes an MgO layer which is a tunnel barrier layer, and reference numeral 418 denotes an interlayer insulating layer. Among the plurality of MTJ devices shown in the VSEM photograph of Fig. 15 obtained by the first etching process and the second etching process, a ratio of an average height with respect to an average width was approximately 1:1.5.

[0158] Fig. 16 illustrates VSEM photographs showing an evaluation result of stacked structures with respect to different concentrations of H2 gas in the etching gas used on the stacked structure including the magnetic layer according to an embodiment of the inventive concept.

[0159] For the assessment of Fig. 16, a stack structure of Ti (2.0 nm) \Ru (2.0 nm) \Ta (0.4 nm) \CoFeB (1.1 nm) \MgO (1.0 nm) \CoFeB (1.2 nm) \Ta (0.4 nm) \Co (0.5 nm) \Pt (1.0 nm) \ [Co (0.25 nm) \Pd (1.0 nm)]×3\Ru (0.8 nm) \ [Co (0.25 nm) \Pd (1.0 nm)]×7\Ru (5.0 nm) stacked sequentially from bottom to top are used. To etch the stacked structure, conductive mask patterns having a structure of Ru (50.0 nm) \TiN (60.0 nm) were formed on the stacked structure, and a plurality of MTJ devices were fabricated by etching the stacked structure using the conductive mask patterns as an etching mask.

[0160] Samples for assessment were prepared using plasma consisting of an etching gas containing different compositions found in Fig. 16 was anisotropically etched. While the stacked structure was etched, a composition and a composition ratio of the etching gas were the same, and a process temperature, a process pressure, a source current, and a bias current for etching were set to 60°C, 0.00267 mBar (2 mTorr), 350 W, and 600 W, respectively.

[0161] In Fig. Fig. 16: (1) is a photograph showing the stacked structure before it is etched after the conductive mask patterns having the structure of Ru (50.0 nm)\TiN (60.0 nm) are formed on the stacked structure. (2) is a photograph showing a resultant structure in which the stacked structure is not etched as a result of etching the stacked structure using plasma obtained from an etching gas containing 100% H2 gas. (3) is a photograph showing a resultant structure formed by etching the stacked structure using plasma obtained from an etching gas containing 95% by volume of H2 gas and 5% by volume of N2 gas. (4) is a photograph showing a resultant structure obtained by etching the stacked structure using plasma obtained from an etching gas containing 90% by volume of H2 gas and 10% by volume of N2 gas.(5) is a photograph showing a resulting structure formed by etching the stacked structure using plasma obtained from an etching gas containing 90% by volume of H2 gas and 10% by volume of Ar gas.

[0162] In the photographs (3), (4) and (5) from Fig. 16, the stacked structure was etched highly anisotropically without redeposition of etching byproducts. Compare photograph (2), where the stacked structure is etched using only H2 gas, with photographs (3), (4), and (5), where the stacked structure is etched using an etching gas containing added N2 gas or Ar gas, which is a non-volatile gas. H2 gas is used in the etching gas to chemically etch the stacked structure. In addition, comparing photographs (4) and (5), a profile of the resulting MTJ devices is similar. Thus, the N2 gas used as an additional gas in photograph (4) and the Ar gas used as an additional gas in photograph (5) perform the same operation.

[0163] In each MTJ device shown in the VSEM photograph (3) from Fig. 16, a ratio of a height with respect to the width was 1 : 4. In each MTJ device shown in the VSEM photograph (4) from Fig. 16, the ratio of height to width was 1 : 3.5.

[0164] Fig. 17A and Fig. 17B are VSEM photographs showing a resultant structure formed by estimating the effect when a pulsed bias current is applied when a stacked structure including a magnetic layer is etched using a manufacturing method of a magnetic device according to an embodiment of the inventive concept.

[0165] For the assessment of Fig. 17A and Fig. 17B, the stack structure and the mask pattern structure were used, which were used in the assessment according to Fig. 15 were used, and the same etching atmosphere condition was used.

[0166] Fig. 17A is a photograph showing a result of performing a first etching process of etching the stacked structure from a Ru layer 512, which is an upper electrode, to a MgO layer 514, which is a tunnel barrier layer, by applying an operating point current in a constant wave mode. Fig. 17B is a photograph showing a result of performing a second etching process of etching a stacked structure from a CoFeB layer, which is a lower structure of the MgO layer 514, to a Ti layer, which is a lower electrode, while applying a bias current in a pulsed mode. Fig. 17A and Fig. 17B, reference numerals 516 and 518 denote a TiN layer and a W layer, respectively, used as etching masks.

[0167] In the photograph from Fig. 17A, i.e., illustrating the case that the first etching process is carried out up to the MgO layer 514, when the operating point current is applied in the constant wave mode, a small amount of etching residues 520 was deposited on the sidewalls of the MgO layer 514 exposed after the first etching process. In the photograph from Fig. 17E, ie the result of performing the second etching process on the resulting structure from Fig. 17A, applying a bias current in the pulsed mode, the etch residues 520 were removed from the sidewalls of the MgO layer 514 and the sidewalls of the MgO layer 514 were completely exposed. In the plurality of MTJ devices shown in the VSEM photographs of Fig. 17B, that is, obtained by the second etching process, a ratio of an average height with respect to an average width was approximately 1:1.5.

[0168] Fig. 18 is a schematic cross-sectional view of a magnetic device 600 formed using a magnetic device manufacturing method according to an embodiment of the inventive concept. With reference to Fig. 18, the magnetic device 600 may include a hard disk drive (HDD) recording head 610. The recording head 610 may include an MTJ device 612.

[0169] Data is recorded in each domain 622 of a recording medium 620 due to perpendicular magnetic polarization, as indicated by arrows. The recording head 610 can record data on the recording medium 620 or read recorded data from the recording medium 620. The manufacturing method of a magnetic device according to the inventive concept can be applicable to forming the MTJ device 612 of the recording head 610.

[0170] Fig. 19 illustrates a system 700 that may be implemented using a magnetic device manufacturing method according to an embodiment of the inventive concept. With reference to Fig. 19, the system 700 may include a controller 710, an input / output device 720, a storage device 730, and an interface 740. The system 700 may be a mobile system or a system for sending and receiving information. In some embodiments, the mobile system is, for example, a personal digital assistant (PDA), a portable computer, a web tablet, a cordless phone, a mobile phone, a digital music player, or a memory card. The controller 710 controls an execution program in the system 700 and may include, for example, a microprocessor, a digital signal processor, a microcontroller, or the like. The input / output device 720 may be used to input or output data from or to the system 700. The system 700 may be connected to an external device, e.g.,a personal computer (PC) or network using input / output device 720, and it can exchange data with the external device. The input / output device 720 can be, for example, a keypad, a keyboard, or a display.

[0171] The storage device 730 may store code and / or data for an operation on the controller 710, or it may store data processed by the controller 710. The storage device 730 may comprise a magnetic device manufactured according to a magnetic device manufacturing method according to at least one embodiment of the inventive concept.

[0172] Interface 740 may be a data transmission path between system 700 and another external device (not shown). Controller 710, input / output device 720, storage device 730, and interface 740 may communicate with each other via bus 750. System 700 may be used in, for example, a mobile phone, an MP3 player, a navigation device, a portable multimedia player (PMP), a solid-state drive (SSD), or household appliances.

[0173] Fig. 20 illustrates a memory card 800 that can be implemented using a magnetic device manufacturing method according to an embodiment of the inventive concept. With reference to Fig. 20, the memory card 800 may include a memory device 810 and a memory controller 820.

[0174] The storage device 810 can store data. In some embodiments, the storage device 810 has non-volatile characteristics, so that stored data can be retained even when a power supply is stopped. The storage device 810 includes a magnetic device manufactured according to a magnetic device manufacturing method according to at least one embodiment of the inventive concept.

[0175] The memory controller 820 may read stored data from the memory device 810 or may store data in the memory device 810 in response to a read / write request from a host 830.

Claims

[1] A method of manufacturing a magnetic device, the method comprising: Forming a stack structure (40; 50; 250), wherein the stack structure (40; 50; 250) comprises a non-volatile metal layer; and Etching the stack structure (40; 50; 250) comprising the non-volatile metal layer with an etching gas containing at least 80% by volume of H2 gas, wherein the method further comprises exposing a region of the stack structure (40; 50; 250) to a hydrogen plasma prior to etching the stack structure (40; 50; 250). [2] The method of claim 1, wherein the stack structure (40; 50; 250) comprises a magnetic layer. [3] The method of claim 1 or 2, wherein etching the stack structure (40; 50; 250) comprises using an etching gas containing H2 gas and an additional gas, wherein the additional gas contains an inert gas and / or NH3 gas. [4] The method according to claim 3, wherein the inert gas in the additional gas contains at least one of N2, Ne, Ar, Kr and Xe. [5] The method of claim 2, wherein etching the stack structure (40; 50; 250) comprises using an etching gas without halogens. [6] The method of claim 2, wherein forming the stack structure (40; 50; 250) comprises using at least one selected from Co / Pd, Co / Pt, Co / Ni, Fe / Pd, Fe / Pt, MgO, PtMn, IrMn, a CoFe alloy, and a Co-FeB alloy. [7] The method of claim 1 or 2, wherein etching the stack structure (40; 50; 250) comprises performing a plasma etching process. [8] The method of claim 2, wherein etching the stack structure (40; 50; 250) comprises: Using a plasma etching device (60) comprising a source current output unit (66) for applying a source current and an operating point current output unit (68) for applying an operating point current, and repeatedly executing an operation sequence in which at least one current selected from the source current and the operating point current changes between an on state and an off state. [9] The method of claim 2, wherein: forming the stack structure (40; 50; 250) comprises forming the magnetic layer between an upper electrode (48) and a lower electrode (42), the upper and lower electrodes (48, 42) being opposite each other, and etching the stack structure (40; 50; 250) comprises etching the upper electrode (48), the lower electrode (42) and the magnetic layer by using the etching gas. [10] A method of manufacturing a magnetic device, the method comprising: Forming a stacked structure (40; 50), the stacked structure (40; 50) comprising a lower magnetic layer (44), a tunnel barrier layer (45) and an upper magnetic layer (46; 56) stacked sequentially from bottom to top; Forming a mask pattern (86) on the stack structure (40; 50) such that a portion of the stack structure (40; 50) is covered; Performing a first etch through the mask pattern (86) to etch a first portion of the stack structure (40; 50), wherein the first portion comprises at least the upper magnetic layer (46; 56) and the tunnel barrier layer (45), and wherein the first etch comprises using a first etch gas containing at least 80 volume % H2 gas and a first additional gas; and Performing a second etch through the mask pattern (86) to etch a second portion of the stack structure (40; 50), the second portion comprising the lower magnetic layer (44) of the stack structure (40; 50), and wherein the second etching is carried out in a different etching atmosphere than the first etching. [11] The method of claim 10, wherein the second etching comprises using a second etching gas containing at least 80 volume % H2 gas and a second additional gas, wherein the second additional gas contains a different component than the first additional gas. [12] The method of claim 11, wherein each of the first additional gas and the second additional gas contains an inert gas or NH3 gas. [13] The method of claim 11, wherein each of the first additional gas and the second additional gas contains at least one of N2, NH3, Ne, Ar, Kr or Xe. [14] The method of claim 11, wherein the first additional gas contains at least one of N2, Ne, Ar, Kr or Xe and wherein the second additional gas contains NH3. [15] The method of claim 10, wherein: forming the stack structure (40; 50) further comprises forming a lower electrode layer (42) and an upper electrode layer (48), the lower magnetic layer (44), the tunnel barrier layer (45) and the upper magnetic layer (46; 56) arranged between the lower electrode layer (42) and the upper electrode layer (48), performing the first etching comprises etching a portion of the upper electrode layer (48) by using the first etching gas such that the upper electrode layer (48) is divided into a plurality of upper electrodes (48A), and performing the second etching comprises etching a portion of the lower electrode layer (42) by using the second etching gas such that that the lower electrode layer (42) is divided into a plurality of lower electrodes (42A). [16] The method of claim 10, wherein performing each of the first etching and the second etching comprises using a plasma etching process. [17] The method of claim 16, wherein: performing each of the first etching and the second etching comprises using a plasma etching apparatus (60) having a source current output unit (66) for applying a source current and an operating point current output unit (68) for applying an operating point current, and at least one of the first etching and the second etching comprises repeatedly performing an operation in which the source or bias current alternates between an off state and an on state. [18] The method of claim 17, wherein the first etching comprises applying the bias current in a constant wave mode and the second etching comprises repeatedly performing an operation in which the bias current alternates between an on state and an off state. [19] The method of claim 10, further comprising exposing a top surface of the stack structure (40; 50) to a hydrogen plasma after forming the mask pattern (86) and before performing the first etch. [20] The method of claim 10, wherein forming the stack structure (40; 50) comprises using a first material and a second material, wherein the first material is at least one of Co / Pd, Co / Pt, Co / Ni, Fe / Pd, Fe / Pt, MgO, PtMn, IrMn, a CoFe alloy, and a CoFeB alloy, and wherein the second material is at least one of Ti, TiN, Ta, TaN, Ru, and W.

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