JP7208767B2 - Manufacturing method and manufacturing apparatus for magnetoresistive element - Google Patents

Description

DETAILED DESCRIPTION Exemplary embodiments of the present disclosure relate to methods and apparatus for manufacturing magnetoresistive elements.

A technique related to etching of a magnetoresistive element is described in Patent Document 1, for example. The document discloses a manufacturing method using titanium nitride as an etching mask layer.

JP 2011-14881 A

A manufacturing method and manufacturing apparatus for a magnetoresistive element capable of reducing variation in device shape after etching is expected.

In one exemplary embodiment, an apparatus for manufacturing a magnetoresistive element includes a controller that controls film formation on a substrate, and the controller performs the following steps. That is, in one process, a multi-layered film including a metal layer and a magnetic layer is formed on a substrate. In one step, an underlayer is formed over the multilayer film. In one step, an etching mask layer having the same crystal structure as the underlying layer is formed on the underlying layer. The underlying layer is a magnesium oxide layer and the etching mask layer is a titanium nitride layer.

According to the method and apparatus for manufacturing a magnetoresistive element according to an exemplary embodiment, variations in device shape after etching can be reduced.

It is a figure which shows the longitudinal cross-sectional structure of the magnetoresistive element (intermediate) which concerns on one exemplary embodiment. It is a figure which shows the longitudinal cross-sectional structure of the magnetoresistive element (intermediate) which concerns on one exemplary embodiment. 4 is a graph showing the relationship between the thickness T (nm) of the MgO layer and the TiN residue density D _N (pieces/μm ² ). 4 is a graph showing the relationship between the thickness T (nm) of the MgO layer and the magnetoresistance ratio (MR ratio) MR (%). 4 is a graph showing the relationship between the thickness T (nm) of the MgO layer and the surface resistance RA (Ω·μm ² ). 1 is a diagram showing the configuration of a magnetoresistive element manufacturing apparatus according to an exemplary embodiment; FIG. 4 is a flowchart illustrating a method of manufacturing a magnetoresistive element according to one exemplary embodiment; It is a figure which shows the longitudinal cross-section SEM photograph of a magnetoresistive element (T= 0 nm). It is a figure which shows the longitudinal cross-section SEM photograph of a magnetoresistive element (T= 0.2 nm). It is a figure which shows the longitudinal cross-section SEM photograph of a magnetoresistive element (T= 0.3 nm). It is a figure which shows the longitudinal cross-section SEM photograph of a magnetoresistive element (T= 0.4 nm).

Various exemplary embodiments are described below.

In one exemplary embodiment, a method of manufacturing a magnetoresistive element includes the following steps. That is, in one process, a multi-layered film including a metal layer and a magnetic layer is formed on a substrate. In one step, an underlayer is formed over the multilayer film. In one step, an etching mask layer having the same crystal structure as the underlying layer is formed on the underlying layer. When an underlying layer having the same crystal structure as that of the etching mask layer is formed on the multilayer film, the crystallinity of the etching mask layer is improved.

Moreover, when the etching mask layer is patterned by etching, the residue of the etching mask layer is reduced. Since the residue affects the shape of the device, this etching mask layer can be used to reduce variations in the shape of the device after etching the multilayer film.

In one exemplary embodiment, the underlayer can be a magnesium oxide layer and the etch mask layer can be a titanium nitride layer. Magnesium oxide (MgO) has a cubic sodium chloride-type crystal structure. Titanium nitride (TiN) also has a crystal structure of the sodium chloride type structure. MgO has a lattice constant of 0.421 nm, and TiN has a lattice constant of 0.424 nm. Their lattice constants are close and the lattice match between MgO and TiN is high. Therefore, the crystallinity of the etching mask layer is improved and the residue can be reduced.

In one exemplary embodiment, the thickness of the magnesium oxide layer can be 0.3 nm or greater. In this case, the density of residues in the etching mask layer can be significantly reduced.

In one exemplary embodiment, the thickness of the magnesium oxide layer can be 1.6 nm or less. In this case, the number of electrons that can tunnel through the magnesium oxide layer increases, sufficiently increasing the MR ratio.

In one exemplary embodiment, a method of manufacturing a magnetoresistive element can include the steps of patterning an etching mask layer and etching a multilayer film using the patterned etching mask layer as a mask. Since the crystallinity of the etching mask layer is improved, the residue after etching is reduced, and variations in the device shape after etching the multilayer film can be reduced.

In one exemplary embodiment, a magnetoresistive device manufacturing apparatus includes a controller that controls deposition on a substrate. The controller can perform the steps described above and have similar effects.

Various exemplary embodiments are described in detail below with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations are omitted.

1 and 2 are diagrams showing longitudinal cross-sectional configurations of magnetoresistive elements (intermediate bodies) according to one exemplary embodiment. A magnetoresistive element 10 (intermediate body) shown in FIG. 1 includes a plurality of magnetoresistive elements, which are separated by etching to form one magnetoresistive element. FIG. 2 shows the state immediately after etching the upper electrode layer 7, which also functions as an etching mask layer. Using the upper electrode layer 7 as an etching mask layer, when the region directly under the opening is etched to the surface of the substrate 1, two magnetoresistive elements are arranged side by side on the substrate.

The magnetoresistive element includes a lower electrode layer 2 , a fixed layer 3 , a tunnel barrier layer 4 , a free layer 5 , an underlying layer 6 and an upper electrode layer 7 which are sequentially laminated on a substrate 1 . When the magnetization directions of the fixed layer 3 and the free layer 5 are parallel, the resistance of the magnetoresistive element is low. When the magnetization directions of the fixed layer 3 and the free layer 5 are antiparallel, the resistance of the magnetoresistive element increases. The fixed layer 3 and the free layer 5 are made of a ferromagnetic material, but the magnetization direction of the free layer 5 changes more easily than the fixed layer 3 does. To fix the direction of magnetization of the pinned layer 3, the thickness thereof is made larger than the thickness of the free layer 5, the method of exchange coupling an antiferromagnetic layer, and the method of sandwiching a nonmagnetic layer between ferromagnetic layers and performing exchange coupling. There is

The tunnel barrier layer 4 is composed of an insulating layer and is set to have a thickness that allows electrons to pass through due to the tunnel effect.

The lower electrode layer 2 and the upper electrode layer 7 are made of a conductor such as metal. The substrate 1 is made of a semiconductor. Here, the underlying layer 6 is arranged directly below the upper electrode layer 7 . A conductive adhesive layer AD is interposed between the base layer 6 and the free layer 5 to bond the free layer 5 and the base layer 6 together. A metal such as Ru can be used for the adhesive layer AD. Ru belongs to the platinum group elements (Ru, Rh, Pd, Os, Ir, Pt). are similar in nature. Therefore, although Ru is preferable as the adhesive layer AD, other metal elements can also be used.

Examples of materials for the magnetoresistive element are as follows.

(Example 1)
・Upper electrode layer 7: TiN (conductor): thickness 90 nm
- Underlying layer 6: MgO (insulator): thickness 0.2 nm to 2 nm
Adhesion layer AD: Ru (conductor): thickness 10 nm
Free layer 5: layer structure containing CoFe (ferromagnetic material): total thickness 4.9 nm
・Tunnel barrier layer 4: MgO (insulator): thickness 1 nm
Fixed layer 3: Layer structure including CoPt (ferromagnetic)/Ru/CoPt: total thickness 13.1 nm
- Lower electrode layer 2: electrode layer containing Ta (conductor): thickness 63 nm
Substrate 1: Si (with _SiO2 layer on the surface)
The multilayer film positioned between the adhesive layer AD and the substrate 1 is the main body of the magnetoresistive element, but Example 1 is merely an example, and there are countless layer structures of combinations of multilayer films. Moreover, it is considered that the structure of the multilayer film hardly affects the etching effect of the upper electrode layer 7 .

(Comparative example)
The structure of the comparative example is a structure in which the underlying layer 6 is removed from the structure of Example 1, and the upper electrode layer 7 is arranged directly on the adhesive layer AD.

When patterning the upper electrode layer 7, a BARC layer 8 (antireflection film) and a resist layer 9 are formed thereon in sequence (see FIG. 2). After patterning the resist layer 9, using this as a mask, the BARC layer 8 is dry-etched, and further the upper electrode layer 7 is dry-etched. At this stage, the etched portions were observed with an electron microscope.

In the structure of the comparative example, numerous TiN residues were observed on the adhesive layer AD (see FIG. 8). On the other hand, in the structure of Example 1, the density of the residue R on the underlying layer 6 was significantly lower than that of the structure of the comparative example (see FIG. 9). That is, it was found that the density of the residue was reduced by providing the underlayer 6 . This is probably because the use of the underlying layer 6 improves the crystallinity of the upper electrode layer 7 . This is because if the crystallinity of the upper electrode layer 7 is significantly poor, the etching becomes non-uniform and the residue tends to increase. As the thickness T of the MgO forming the underlying layer 6 increases, the residue decreases, but when the thickness T exceeds 1.2 nm, the MR ratio begins to decrease. When the thickness T exceeds 1.6 nm, the MR ratio significantly decreases. This is probably because electrons cannot pass through the tunnel barrier formed by MgO. Along with this, when the thickness T exceeds 1.6 nm, the surface resistance RA (Ω·μm ² ) of the magnetoresistive element significantly increases.

The structure of the multilayer film of Example 1 is considered to have little effect on the etching effect of the upper electrode layer 7. Specifically, the layer structure below the free layer is They are as follows. CoFeB 25 is CoFe with a boron content of 25%, and the MgO layer located in the upper free layer 5 is a cap layer. Also, the laminated structure of the Co layer and the Pt layer can function as a CoPt layer.

(Specific example of layer structure of Example 1)
- Free layer 5:
・ CoFeB25: thickness 1 nm
・MgO: thickness 1 nm (cap layer)
・ CoFeB25: thickness 1 nm
・W: thickness 0.5 nm
・CoFeB25: thickness 1.4 nm
・Tunnel barrier layer 4
・MgO: thickness 1 nm
・Fixed layer 3
・CoFeB25: thickness 1.2 nm
・W: thickness 0.5 nm
· Co: thickness 0.5 nm
・Pt: thickness 0.3 nm
· Co: thickness 0.5 nm
・Pt: thickness 0.3 nm
· Co: thickness 0.5 nm
・Ru: thickness 1 nm
· Co: thickness 0.5 nm
・Pt: thickness 0.3 nm
· Co: thickness 0.5 nm
・Pt: thickness 0.3 nm
· Co: thickness 0.5 nm
・Pt: thickness 0.3 nm
· Co: thickness 0.5 nm
・Pt: thickness 0.3 nm
· Co: thickness 0.5 nm
・Pt: thickness 0.3 nm
· Co: thickness 0.5 nm
・Pt: thickness 0.3 nm
· Co: thickness 0.5 nm
・Pt: thickness 3 nm
- Lower electrode layer 2:
・TaN: thickness 10 nm
・Ru: thickness 20 nm
・TaN: thickness 10 nm
・Ru: thickness 20 nm
・Ta: thickness 3 nm
FIG. 3 is a graph showing the relationship between the thickness T (nm) of the MgO layer and the TiN residue density D _N (pieces/μm ² ). 8, 9, 10, and 11 are longitudinal cross-sectional SEM photographs of magnetoresistive elements when T=0, T=0.2 nm, T=0.3 nm, and T=0.4 nm, respectively. FIG. 4 is a diagram showing;

In the comparative example without the MgO underlayer 6, the residue density D _N was 285 (pieces/μm ² ) ₍ see FIG. 8). Diminished. When the thickness T of the underlying layer 6 is 0.2 (nm), D _N =65 (pieces/μm ² ) ₍ see ^FIG . 9). ) (see FIG. 10). D _N =0 (pieces/μm ² ) at thickness T=0.4 (nm) (see FIG. 11). That is, D _N =0 (pieces/μm ² ) when the thickness T≧0.3 (nm).

From the viewpoint of residue reduction, 0 (nm)<T is preferable. Furthermore, 0.2 (nm)<T is preferable. Furthermore, 0.3 (nm)<T is preferable.

FIG. 4 is a graph showing the relationship between the thickness T (nm) of the MgO layer and the magnetoresistance ratio (MR ratio) MR (%).

In the comparative example that does not use the MgO underlayer 6, the MR ratio value MR=153 (%), but in Example 1 that uses the underlayer 6, the MR ratio increases and the thickness T of the underlayer 6 increases. = 0.4 (nm), MR was 160 (%). When the thickness T of the underlying layer 6 was 0.8 (nm), the MR was further increased to 163 (%). When the thickness T of the underlying layer 6 is 1.2 (nm), the MR is further increased to 164 (%). When the thickness T of the underlying layer 6 is 1.6 (nm), the MR is 138 (%), and although there is an effect of reducing the residue, the MR ratio is slightly lowered. When the thickness T of the underlying layer 6>1.2 (nm), the MR ratio begins to decrease, and when the thickness T>1.6 (nm) of the underlying layer 6, the MR ratio begins to significantly decrease.

From the viewpoint of the MR ratio, 0 (nm)<T≦1.6 (nm) is preferable. Furthermore, 0 (nm)<T≦1.2 (nm) is preferable. Furthermore, 0.4 (nm) ≤ T ≤ 1.2 (nm) is preferable. Furthermore, 0.4 (nm) ≤ T ≤ 1.2 (nm) is preferable. Furthermore, 0.8 (nm) ≤ T ≤ 1.2 (nm) is preferable.

FIG. 5 is a graph showing the relationship between the thickness T (nm) of the MgO layer and the surface resistance RA (Ω·μm ² ).

From the viewpoint of the surface resistance of the magnetoresistive element, it is preferable that T≦1.6 nm. This is because when the thickness T exceeds 1.6 nm, the sheet resistance begins to increase sharply.

As a related experiment, the thickness T of the MgO layer (100) as the underlayer in Example 1 was changed to T=0 nm, T=1 nm, and T=3 nm. When the thickness of the MgO layer is increased, according to the X-ray diffraction measurement results, the height of the peak of TiN(200) formed on the underlayer increases with increasing MgO thickness, and the half-value width also narrowed. The peak value of TiN(200) at T=0 nm was 302, the peak value at T=1 nm was 465, and the peak value at T=3 nm was 801. From this, it can be seen that the crystallinity of the TiN layer is improved by using the MgO layer as the underlayer.

(Production method)
Each layer described above can be formed by a film forming apparatus. A chemical vapor deposition (CVD) method as well as a sputtering method can be used for film formation. In a magnetron sputtering apparatus, a noble gas such as Ar or Kr is plasmatized and used to sputter a target containing the material of interest, depositing the sputtered atoms onto the substrate 1 . In forming the oxide layer, oxygen gas may be introduced during sputtering. In forming the nitride layer, nitrogen gas may be introduced during sputtering.

In the formation of the layered structure of Example 1, first. A Si substrate is prepared as the substrate 1 and its surface is thermally oxidized to form a SiO ₂ layer. Next, the layer structures described above are formed in order from the bottom. The method for forming each layer is as follows.

Ta layer: Ta is used as a sputtering target to form a Ta layer. The gas that generates plasma for sputtering is Kr.

Ru layer: Ru is used as a sputtering target to form a Ru layer. The gas that generates plasma for sputtering is Ar.

TaN layer: A TaN layer is formed by using Ta as a sputtering target and introducing a nitrogen gas into the processing container during Ta sputtering. The gases that generate plasma for sputtering are Ar and _N2 .

Co layer: Co is used as a sputtering target to form a Co layer. The gas that generates plasma for sputtering is Kr.

Pt layer: Pt is used as a sputtering target to form a Pt layer. The gas that generates plasma for sputtering is Kr.

• W layer: W is used as a sputtering target to form a W layer. The gas that generates plasma for sputtering is Kr.

CoFeB25 layer: CoFeB25 is used as a sputtering target to form a CoFeB25 layer. The gas that generates plasma for sputtering is Ar.

MgO layer: Mg is used as a sputtering target, and after the Mg layer is formed, O2 gas is introduced to oxidize the Mg to form MgO. The gas that generates plasma for Mg sputtering is Ar. The surface of the formed MgO layer is the MgO (100) plane.

As described above, the above-described layered structure can be formed if there are seven types of targets for sputtering: Ta, Ru, Co, Pt, W, CoFeB25, and Mg.

FIG. 6 is a diagram showing the configuration of a magnetoresistive element manufacturing apparatus according to an exemplary embodiment. A Si wafer as the substrate 1 is transferred to the transfer chamber 15 via the load lock chamber 16 . When forming a film on the substrate 1, the substrate 1 is transferred from the transfer chamber 15 onto the stage S1 of the film forming chamber P1 as a plasma processing apparatus. When etching the substrate 1, the substrate 1 is transferred from the transfer chamber 15 onto the stage S2 of the etching chamber P2 as a plasma processing apparatus. The transfer is performed by a transfer robot (robot arm) arranged in the transfer chamber.

A processing gas is supplied from a gas supply source 11 to the deposition chamber P1 via a flow control device 12 . Processing gases are Ar and Kr for generating plasma, and O ₂ and N ₂ for oxidation and nitridation. An etching gas is supplied to the etching chamber P2 from a gas supply source 11 via a flow control device 12 .

The film forming chamber P1 is an RF magnetron sputtering apparatus containing a plurality of targets TG, and a high frequency voltage (13.56 MHz) is applied from a high frequency power supply 14 between the stage S1 and the targets TG. The transfer chamber 15, the load lock chamber 16, the film formation chamber P1, and the etching chamber P2 are each connected to a plurality of exhaust devices 17, and the internal gas is exhausted as necessary. In addition, in FIG. 1, there is one block of the exhaust device 17, but it means a plurality of exhaust devices. When the treatment gas is introduced into the deposition chamber P1 and the internal pressure is reduced, power is supplied from the high-frequency power supply 14 to the specified target TG to generate plasma in the chamber. The gas of this plasma sputters the target TG, thereby depositing the target material on the substrate.

In the figure, three targets TG are shown, but it is also possible to arrange seven types of targets (Ta, Ru, Co, Pt, W, CoFeB25, Mg) in the deposition chamber. be. The number of target TGs can be changed as needed, and the targets themselves can be replaced.

The etching chamber P2 is a plasma etching device, and generally a parallel plate type plasma etching device can be used, but other etching devices can also be used. In this case, a high frequency voltage (13.56 MHz) is applied from the high frequency power supply 14 between the stage S2 and the upper electrode. When power is supplied from the high frequency power supply 14 to the upper electrode, plasma is generated in the chamber. When this plasma gas reaches the substrate, the layer on the substrate surface is etched. A gas introduced during dry etching is a mixed gas of CO and O ₂ or the like.

The controller 13 controls the film forming chamber P1, the etching chamber P2, and the transfer robots of the transfer chamber 15 to form the above-described laminated structure and to form the magnetoresistive element.

FIG. 7 is a flowchart illustrating a method of manufacturing a magnetoresistive element according to one exemplary embodiment. It is assumed that the layers below the free layer 5 have already been formed on the substrate 1 as the main body of the magnetoresistive element. The layers below the free layer 5 can be formed by selecting targets for materials constituting each layer in the order of lamination and introducing the corresponding processing gas into the film formation chamber P1. Under the conditions of Example 1 above, after the formation of the free layer 5, a CoFeB25 layer is formed on the outermost surface. In this example, the substrate on which the free layer 5 is formed is placed on the stage S1 of the deposition chamber P1, and as shown in the structure of FIG. is formed on the free layer 5 by the method (S11). Next, a base layer 6 made of an MgO layer is formed on the adhesive layer AD by sputtering (S12). Subsequently, the upper electrode layer 7 as a hard mask layer made of a TiN layer is formed on the base layer 6 by sputtering (S13).

Next, the hard mask layer is patterned. First, the transfer robot in the transfer chamber 15 is controlled to transfer the wafer (substrate) to the load lock chamber 16 and take out the wafer from the load lock chamber 16 . A BARC layer 8 (antireflection film) is formed on the upper electrode layer 7, and a resist layer 9 is sequentially formed (S14: see FIG. 2). The material of the BARC layer 8 is _SiO2 , and the formation method is spin coating. The resist layer 9 is formed by applying a commercially available photoresist by spin coating. After pre-baking the resist layer 9, the wafer is transported to an exposure apparatus, and the resist layer 9 is exposed with a desired pattern (S15). Next, the resist layer 9 is transported to a developing device, and the resist layer 9 is developed using a developer to pattern the resist layer 9 (S16). After that, the resist layer 9 is post-baked.

Next, the wafer is introduced into the load lock chamber 16, and the transfer robot in the transfer chamber 15 is controlled to transfer the wafer from the load lock chamber 16 to the etching chamber P2. Thereafter, using the resist layer 9 as a mask, the BARC layer is plasma dry etched (S17). The dry etching gas introduced into the etching chamber P2 is a fluorine-based gas, specifically CHF ₃ and CF ₄ .

Subsequently, using the resist layer 9 and the BARC layer 8 as a mask, the upper electrode layer 7 (hard mask layer) is subjected to plasma dry etching (S18). The dry etching gas introduced into the etching chamber P2 is a chlorine-based gas, specifically Cl _{2 and} BCl ₄ . Thereby, the upper electrode layer 7 is patterned and the surface of the underlying layer 6 is exposed.

Next, the transfer robot in the transfer chamber 15 is controlled to transfer the wafer (substrate) to the load lock chamber 16 and take out the wafer from the load lock chamber 16 . Next, the resist layer 9 is removed by O ₂ plasma ashing (S19). Note that the BARC layer 8 can be left as it is.

Next, using the upper electrode layer 7 as a mask, the layers below the upper electrode layer 7 are dry-etched. Accordingly, the wafer is introduced into the load lock chamber 16, and the transfer robot in the transfer chamber 15 is controlled to transfer the wafer from the load lock chamber 16 to the etching chamber P2. Thereafter, using the upper electrode layer 7 (hard mask layer) as a mask, the underlying layer 6, the adhesive layer AD, the free layer 5, the tunnel barrier layer 4, the fixed layer 3, and the lower electrode layer 2 are etched with a plasmatized etching gas. Dry etching is performed (S20). The dry etching gas introduced into the etching chamber P2 is a gas containing oxygen, specifically CO and _O2 . Etching is stopped when the surface of the substrate 1 is exposed. The magnetoresistive element shown in FIG. 2 is separated in two to complete two magnetoresistive elements.

As described above, the above-described method for manufacturing a magnetoresistive element includes the following steps. That is, in one step, a multilayer film ML including a metal layer (lower electrode layer 2) and magnetic layers (a fixed layer 3 and a free layer 5 including a Co layer, a Pt layer, a CoPt layer, and a CoFe layer) is formed on a substrate 1. (lower electrode layer 2, fixed layer 3, tunnel barrier layer 4, free layer 5) are formed. In one step, an underlayer 6 is formed on the multilayer film. In one step, an etching mask layer (upper electrode layer 7 ) having the same crystal structure as the underlying layer 6 is formed on the underlying layer 6 . When an underlying layer (MgO) having the same crystal structure as the etching mask layer (TiN) is formed on the multilayer film, the crystallinity of the etching mask layer is improved.

Moreover, when the etching mask layer (upper electrode layer 7) is patterned by etching, the residue of the etching mask layer is reduced. Since the residue affects the shape of the device, this etching mask layer can be used to reduce variations in the shape of the device after etching the multilayer film.

In one exemplary embodiment, the underlayer 6 can be a magnesium oxide layer and the etching mask layer can be a titanium nitride layer. Magnesium oxide (MgO) has a cubic sodium chloride-type crystal structure. Titanium nitride (TiN) also has a crystal structure of the sodium chloride type structure. MgO has a lattice constant of 0.421 nm, and TiN has a lattice constant of 0.424 nm. Their lattice constants are close and the lattice match between MgO and TiN is high. Therefore, the crystallinity of the etching mask layer is improved and the residue can be reduced.

In one exemplary embodiment, the thickness T of the magnesium oxide layer can be 0.3 nm or more (0.3≦T). In this case, the density of residues in the etching mask layer can be significantly reduced.

In one exemplary embodiment, the thickness of the magnesium oxide layer can be 1.6 nm or less (T≦1.6). In this case, the number of electrons that can tunnel through the magnesium oxide layer increases, sufficiently increasing the MR ratio.

In one exemplary embodiment, a method for manufacturing a magnetoresistive element includes a step of patterning an etching mask layer (upper electrode layer) (S18) and a step of etching a multilayer film using the patterned etching mask layer as a mask ( S20). Since the crystallinity of the etching mask layer is improved, the residue after etching is reduced, and variations in device shape after etching the multilayer film can be reduced.

In one exemplary embodiment, the apparatus for manufacturing a magnetoresistive element Z comprises a controller 13 for controlling film deposition on the substrate (see FIG. 6). A controller 13 can control and carry out all the steps described above. In the magnetoresistive element manufactured by the above-described method, the underlying layer 6 improves the crystallinity of the upper electrode layer 7, suppresses variations, and preferably maintains electrical characteristics and throughput.

Although MgO is preferable as the material for the underlayer 6, the crystallinity of TiN is improved even if CaO, CdO, MnS, PbS, or the like is used as a crystal having the same NaCl structure as that of TiN, in addition to MgO. is thought to decrease.

The structure of the multilayer film forming the main body of the magnetoresistive element is such that a CoFe layer is used as the free layer, and a ferromagnetic layer (CoFe) and an antiferromagnetic layer (PtMn) are combined as the fixed layer. Various layer structures are conceivable, such as using In addition, it is considered that the effect of reducing the residue described above can be obtained without depending on the structure of the multilayer film.

DESCRIPTION OF SYMBOLS 1... Substrate 2... Lower electrode layer (metal layer) 3... Fixed layer (magnetic layer) 4... Tunnel barrier layer 5... Free layer (magnetic layer) AD... Adhesive layer 6... Base layer 7... Upper electrode layer (hard mask layer, etching mask layer), 8... BARC layer, 9... resist layer, 10... magnetoresistive element, 11... gas supply source, 12... flow control device, 13... controller, 14... high frequency power supply, DESCRIPTION OF SYMBOLS 15... Transfer chamber, 16... Load lock chamber, 17... Exhaust apparatus, P1... Film formation chamber, P2... Etching chamber, S1... Stage, ML... Multilayer film.

Claims (4)

An apparatus for manufacturing a magnetoresistive element,
Equipped with a controller that controls film formation on the substrate,
The controller is
forming a multilayer film including a metal layer and a magnetic layer on the substrate;
forming an underlying layer on the multilayer film;
forming an etching mask layer having the same crystal structure as the underlying layer on the underlying layer;
and run
The underlying layer is a magnesium oxide layer,
the etching mask layer is a titanium nitride layer;
Manufacturing equipment for magnetoresistive elements. The magnesium oxide layer has a thickness of 0.3 nm or more.
2. The apparatus for manufacturing a magnetoresistive element according to claim 1 . The magnesium oxide layer has a thickness of 1.6 nm or less.
3. The apparatus for manufacturing a magnetoresistive element according to claim 1 . The controller is
patterning the etching mask layer;
etching the multilayer film using the patterned etching mask layer as a mask;
run the
The apparatus for manufacturing a magnetoresistive element according to any one of claims 1 to 3 .

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