Plasma processing device, plasma processing method and method of manufacturing element including substrate to be processed

The present invention provides a plasma processing device and a plasma processing method that can easily adjust plasma density distribution while making the plasma density uniform, and a method of manufacturing an element including a substrate to be processed. In an embodiment of the present invention, the inside of a vacuum vessel (1) is divided by a grid (4) having communication holes into a plasma generation chamber (2) and a plasma processing chamber (5). On the upper wall (26) of the plasma generation chamber (2), magnetic coils (12) are arranged such that magnetic field lines within the vacuum vessel (1) point from the center of the vacuum vessel (1) to a side wall (27), and, outside the side wall (27) of the plasma generation chamber (2), ring-shaped permanent magnets (13) are arranged such that a polarity pointing to the inside of the vacuum vessel (1) is a north pole and a polarity pointing to the outside of the vacuum vessel (1) is a south pole.

TECHNICAL FIELD

The present invention relates to a plasma processing device, a plasma processing method and a method of manufacturing an element including a substrate to be processed. More particularly, the present invention relates to a plasma processing device and a plasma processing method that process a substrate with a plasma such as by utilizing the plasma to form a thin film on the surface of the substrate to be processed or etching the surface of the substrate to be processed, and a method of manufacturing an element including a substrate to be processed.

BACKGROUND ART

Conventionally, for example, in etching devices, a magnetron type plasma generation device using a magnet, an ECR discharge type plasma generation device using electron cyclotron resonance and a helicon type plasma generation device using a helicon wave have been mainly used.

As a plasma generation device, patent document 1 discloses a device in which a plurality of permanent magnets magnetized along a ring-shaped center axis is concentrically arranged on the upper wall of a plasma generation chamber so as to have alternate polarities, and in which a magnetic coil is further arranged outside the side wall of the plasma generation chamber. In the device, a coil magnetic field is generated such that magnetic field lines are pointed to the side of a substrate by the magnetic coil arranged on the side wall, and thus a plasma generated in the vicinity of the upper wall of the plasma generation chamber is widely diffused by the coil magnetic field.

Moreover, patent document 2 discloses a device in which a substrate holder connected to a self-bias generation high frequency power supply is arranged sufficiently away from a plasma generation high frequency electrode, and in which magnetic coils are arranged both outside a vacuum vessel between the high frequency electrode and the substrate holder and on the back surface of the high frequency electrode, respectively. The device freely controls the self bias and performs stable plasma processing without damaging an item to be processed.

Another method of realizing the uniformity of plasma is to concentrically and triply arrange cylindrical permanent magnets that are magnetized in the direction of the center axis of the cylinder (in the longitudinal direction of the cylinder) so as to have alternate polarities. In this case, a boundary surface (separatrix) formed between magnetic field lines formed by two cylindrical permanent magnets (permanent magnets in the center and the outermost side) arranged outside and magnetic field lines formed by two cylindrical permanent magnets (permanent magnets in the center and the innermost side) arranged inside is produced within a vacuum vessel. Since the plasma expands in the inside surrounded by the separatrix, strength of the permanent magnet is optimized and thus it is possible to control the diffusion region of the plasma and adjust the uniformity. This type of magnetic field generation device is proposed, and is applied to a planar type ECR device and the like (see patent document 3).

RELATED ART DOCUMENTS

Patent Documents

SUMMARY OF INVENTION

As a substrate to be processed that is used for manufacturing a semiconductor device, a substrate having a diameter of about 30 cm has been mainly used in recent years, and it is necessary to uniformly perform processing on the entire surface of the substrate.

However, in the device disclosed in patent document 1, in order to make the generated plasma diffuse and become uniform, it is necessary for charged particles generated by the plasma to fly a longer distance within the coil magnetic field as the substrate to be processed becomes larger, and thus it is disadvantageously difficult to reduce the size of the device.

Furthermore, another embodiment of patent document 1 discloses, as shown inFIGS. 5A and 5B, a plasma processing device configured to form uniform plasma by a permanent magnet52arranged on the upper wall of a plasma generation device51and permanent magnets53ato53harranged on the side wall of the plasma generation device51. As shown inFIG. 5B, the permanent magnets53ato53hare arranged apart from each other on the side wall of the plasma generation device51along the outer circumference of the side wall so as to have alternate polarities. Hence, as shown inFIG. 5B, a plasma P1generated within the plasma generation device51is returned by respective magnetic fields B1generated by the permanent magnets53ato53hin directions A indicated by arrows.

However, in the configuration shown inFIGS. 5A and 5B, the plasma becomes disadvantageously nonuniform between the portion of the side wall of the plasma generation device51where the permanent magnets53ato53hare arranged and the portion where they are not arranged. Furthermore, in order to adjust the plasma density distribution, it is disadvantageously necessary to replace the permanent magnet52and the permanent magnets53ato53heach time.FIG. 5Bis a cross-sectional view taken along line VB-VB ofFIG. 5A.

In the device configuration using only the magnetic coil, disclosed in patent document 2, stable discharge can be obtained but it is impossible to prevent the behavior of the charged particles escaping to the wall of the vacuum vessel, and thus it is disadvantageously difficult to uniformly generate a high-density plasma.

In particular, in the plasma etching device disclosed in patent document 2, as shown inFIG. 6, a region where the plasma density distribution can be adjusted by a coil61is limited to a region on the upper side of the coil61. Hence, it is disadvantageously difficult to adjust the plasma density distribution between the lower side of the coil61and a substrate62. InFIG. 6, reference numeral63represents a plasma generation high-frequency electrode, and reference numeral64represents a magnetic coil arranged on the back surface of the high-frequency electrode63.

In the device disclosed in patent document 3, three cylindrical permanent magnets which are magnetized such that adjacent polarities in the axial direction of the cylinders are opposite to each other are concentrically arranged. In the distribution of magnetic field lines formed by this magnetic circuit, a boundary surface (separatrix) is formed between magnetic field lines formed by two cylindrical permanent magnets located outside and magnetic field lines formed by two cylindrical permanent magnets located inside. It has been proved that the position of the separatrix corresponds to the position of a local minimal value of a plasma floating potential and that the uniformity of the plasma density is satisfactory in the inside surrounded by the floating potential local minimal portion. Thus, in order to increase the size of the portion having the satisfactory uniformity of the plasma density, it is effective to configure the magnetic circuit such that the separatrix expands outward toward the side of the substrate from the arrangement position of the three magnets described above.

However, in the device that utilizes the permanent magnets for generating the separatrix as disclosed in patent document 3, it is necessary for the adjustment of separatrix shape to replace the permanent magnets, and thus it is disadvantageously difficult to perform the adjustment to achieve uniform plasma distribution.

An object of the present invention is to provide a plasma processing device that can solve at least one of the problems described above. Specifically, the object of the present invention is to provide a plasma processing device and a plasma processing method that can easily adjust plasma density distribution while making the plasma density uniform, and a method of manufacturing an element including a substrate to be processed.

Another object of the present invention is to provide a plasma processing device and a plasma processing method that can easily adjust the shape of a separatrix and that can easily make uniform the plasma distribution of a large area, and a method of manufacturing an element including a substrate to be processed.

To achieve the above objects, according to the present invention, there is provided a plasma processing device including: a vacuum vessel; a plasma generation mechanism for generating a plasma within the vacuum vessel; a substrate holder that is arranged within the vacuum vessel and for holding a substrate to be processed; and a magnetic circuit for generating a magnetic field within the vacuum vessel, wherein the magnetic circuit includes: a first magnetic field generation means that is provided on an upper wall of the vacuum vessel opposite the substrate holder, that can adjust the generated magnetic field by an applied current, and that is arranged such that one magnetic pole of a north pole and a south pole points to an inside of the vacuum vessel and the other magnetic pole points to an outside of the vacuum vessel; and a second magnetic field generation means that is provided on a side wall of the vacuum vessel and that is arranged such that the one magnetic pole points to the inside of the vacuum vessel and the other magnetic pole points to the outside of the vacuum vessel.

According to the present invention, there is provided a plasma processing method including: a step of arranging a substrate to be processed on a substrate holder provided within a vacuum vessel; a step of generating a plasma within the vacuum vessel; and a step of forming a separatrix expanding from an upper wall to the substrate holder by a magnetic field line generated by applying a current to a first magnetic field generation means that is provided on the upper wall of the vacuum vessel opposite the substrate holder and that can adjust a generated magnetic field by an applied current and a magnetic field line generated by a second magnetic field generation means provided on a side wall of the vacuum vessel, wherein, in the step of forming the separatrix, the shape of the separatrix can be adjusted by adjusting the current applied to the first magnetic field generation means.

According to the present invention, there is provided a method of manufacturing an element including a substrate to be processed, the method including: a step of arranging the substrate to be processed on a substrate holder provided within a vacuum vessel for performing predetermined plasma processing; a step of generating a plasma within the vacuum vessel; and a step of forming a separatrix expanding from an upper wall to the substrate holder by a magnetic field line generated by applying a current to a first magnetic field generation means that is provided on the upper wall of the vacuum vessel opposite the substrate holder and that can adjust a generated magnetic field by an applied current and a magnetic field line generated by a second magnetic field generation means provided on a side wall of the vacuum vessel, and of performing the predetermined plasma processing, wherein, the step of performing the plasma processing can adjust the shape of the separatrix by adjusting the current applied to the first magnetic field generation means.

According to the present invention, the configuration of the magnetic circuit that applies a magnetic field to the plasma generation chamber is well devised, and thus it is possible to freely control a satisfactory range of uniformity of a plasma. In order to generate a desired magnetic field, it is possible to perform minute adjustment on the shape of a separatrix by changing a current flowing through the magnetic coil which is a component of the magnetic field. Thus, for example, it is possible to form a magnetic field with the separatrix expanded and to uniformly diffuse the plasma generated within the plasma generation chamber in a short distance. If the separatrix is narrowed near the area where the plasma is generated, high-density plasma can be utilized for processing the substrate, and thus it is possible to perform surface processing at a high processing speed.

DESCRIPTION OF EMBODIMENTS

Some preferred embodiments of the present invention will be described below with reference to accompanying drawings. In the drawings described below, parts having the same function are identified with the same reference numerals, and their description will not repeated.

First Embodiment

FIG. 1is a cross-sectional view schematically showing the configuration of an inductively-coupled plasma processing device that is a preferred embodiment of a plasma generation device according to the present invention;FIG. 2is a cross-sectional view taken along line II-II ofFIG. 1; andFIG. 3is a diagram showing the distribution of magnetic field lines generated in the device of the present embodiment.

In the plasma processing device ofFIG. 1, a vacuum vessel1is divided by a bulkhead plate (grid)4, which has communication holes, into a plasma generation chamber2and a plasma processing chamber5. The plasma generation chamber2includes a plasma generation mechanism such as an SLA (single loop antenna)11and a magnetic circuit3having magnetic coils12and permanent magnets13, and the magnetic circuit3generates a magnetic field within the vacuum vessel1. The plasma processing chamber5includes a substrate holding mechanism6. The vacuum vessel1includes: a gas supply mechanism (not shown) connected to a gas supply port7for introducing a gas used for the generation of a plasma; and a gas discharge mechanism (not shown) for bringing the inside of the vacuum vessel1into a required reduced-pressure state. The gas supply mechanism and the gas discharge mechanism are generally well-known, and hence their detailed illustration is omitted.

As the plasma generation mechanism, it is not always necessary to use the SLA; as long as a plasma can be generated, a flat plate electrode or an antenna of another shape may be used instead. When the flat plate electrode is used, it is preferably arranged within the vacuum vessel1so as to face a substrate to be processed23, which will be described later.

In the present embodiment, the magnetic circuit3includes the magnetic coils12and the permanent magnets13. The magnetic coils12are arranged outside the upper wall of the vacuum vessel1, that is, outside the upper wall26of the plasma generation chamber2; its center axis is arranged to coincide with the center axis of the plasma generation chamber2. One magnetic coil12is provided or a plurality of the magnetic coils12is provided concentrically, and is fixed to the side of the atmosphere of the plasma generation chamber2(the outside of the plasma generation chamber2). A DC power supply25is connected to the magnetic coils12; a current for generation of a magnetic field is supplied from the DC power supply25, and thus the magnetic coils12generate the magnetic field. The DC power supply25is configured to be capable of adjusting the value of an output current; the current value can be controlled by an unillustrated control device. The current through the magnetic coils12is applied such that magnetic field lines within the vacuum vessel1point from the center of the vacuum vessel1to the side wall27of the vacuum vessel1. Specifically, the magnetic coils12provided on the upper wall26of the plasma generation chamber2(the vacuum vessel1) opposite a substrate holder21, which will be described later, are configured to generate magnetic field lines that point from the upper wall26toward the side wall27(the magnetic coils12are arranged such that the north pole thereof points to the side of the vacuum vessel1and the south pole points to the side of the atmosphere (the opposite side of the vacuum vessel1)).

The permanent magnets13are fixed to the side wall27of the vacuum vessel1. Specifically, as shown inFIG. 2, outside the side wall27of the plasma generation chamber2, the permanent magnets13that are magnetized in the direction of the center axis of the plasma generation chamber2are arranged concentrically with respect to the center axis of the plasma generation chamber2so as to have a ring shape. If the ring-shaped permanent magnets13cannot be magnetized in the direction of the center of the ring, the ring of the permanent magnets may be produced by arranging thin magnet strips that can obtain a necessary magnetic field with the magnetization direction directed to the center axis of the plasma generation chamber2(the vacuum vessel1) (for example, with the north poles directed to the center axis) so as to have a ring shape.

An applied current to all the magnetic coils12is set such that the magnetic field lines within the plasma generation chamber2point from the center of the vacuum vessel1to the side wall.

The permanent magnets13are arranged to be magnetized such that the polarity toward the inside of the vacuum vessel1in the direction of the center axis of the ring is the north pole and the polarity toward the outside of the vacuum vessel1is the south pole. As long as the permanent magnets13in which the polarity in the direction of the center axis of the vacuum vessel1is the north pole are ring-shaped and are arranged on the side wall27of the vacuum vessel1, the number of rings can freely be determined.

The diameter and the cross-sectional shape of the magnetic coils12are not particularly limited. As long as the magnetic coils12are arranged on the upper wall26of the plasma generation chamber2, the number of the magnetic coils12is not limited. InFIG. 3, in order to form the separatrices8to have the largest possible diameter, the magnetic field lines are generated in a wide region of the upper wall26, and the magnetic coils12each are doubly arranged around the end of the upper wall26and around the center of the upper wall26such that the end of the separatrices8reach not only the upper wall26but also the side wall27.

The current applied to the permanent magnets13and the magnetic coils12is experimentally determined in consideration of applicable process conditions each time.

In order to perform processing on the substrate in the plasma processing device ofFIG. 1, air within the vacuum vessel1is first discharged so as to have a predetermined pressure with an unillustrated discharge mechanism (vacuum pump or the like), and then gas is introduced so as to have a predetermined pressure with an unillustrated gas supply mechanism.

The substrate holding mechanism6includes the substrate holder21for placing the substrate to be processed23; for example, the substrate holder21is arranged by a fixed shaft22within the vacuum vessel1. The substrate holder21and the fixed shaft22are grounded; in order to apply to the substrate23a bias voltage such as high-frequency waves, it is also possible to set the substrate holding mechanism6at a floating potential by inserting an insulator or the like between the vacuum vessel1and the fixed shaft22. It is also possible to provide a mechanism for cooling or heating the substrate23within the substrate holder21and the fixed shaft22.

The substrate to be processed23is arranged on the substrate holder21. The surface of the substrate23to be processed faces the antenna of the plasma generation chamber2or the electrode. When, as in the present embodiment, the SLA 11 is arranged outside the side wall27of the plasma generation chamber2, the surface of the substrate23to be processed is arranged to face the plasma generation chamber2. When a flat plate-shaped electrode is used, the electrode is arranged below the upper wall of the plasma generation chamber2, and the electrode is arranged opposite the surface of the substrate23to be processed through the grid4. Then, RF power is applied from a RF power supply24to the antenna11or the RF power and DC power are applied to the electrode, and thus a plasma is produced within the plasma generation chamber2. A bias voltage is applied to the substrate23or a bias voltage is applied to the entire plasma generation chamber2, to increase a plasma level higher than the ground, and thus it is possible to perform, on the surface of the substrate23, predetermined processing such as ion etching. The illustration of a mechanism for carrying in or out the substrate23is omitted.

The configuration shown inFIG. 1is conceptual; any structure equivalent in function to the structures of a specific plasma generation mechanism and a specific magnetic circuit can be employed.

FIG. 3shows an example of magnetic field lines14and15generated by the magnetic circuit3shown inFIG. 1. The magnetic field lines are diffused vertically from an area where the magnetic field line14generated by the magnetic coils12collides with the magnetic field line15generated by the permanent magnets13, and are then spread toward the side wall27. The separatrices8are also generated along the magnetic field lines and diffused toward the side wall27. The distribution of the separatrices8can be controlled by the current through the magnetic coils12; the current applied to the magnetic coils12is increased, and thereby it is possible to further displace the collision areas16of the magnetic field lines14and15and the position of the separatrices8toward the side wall27of the plasma generation chamber2. By contrast, the current applied to the magnetic coils12is decreased, and thereby it is possible to displace the collision areas16of the magnetic field lines and the position of the separatrices8toward the center axis of the magnetic coils12. In other words, by adjusting the current to the magnetic coils12, it is possible to control a satisfactorily uniform range while preventing or reducing the diffusion of the plasma. For example, the control device controls the DC power supply25, and thereby it is possible to control the current to the magnetic coils12. Alternatively, an operator may directly set an output value of the DC power supply25.

For example,FIG. 4Ashows an example of the result of calculation of the distribution of magnetic field lines generated in the same magnetic circuit as inFIG. 1;FIG. 4Bshows the distribution of magnetic field lines when the current applied to the magnetic coils12is increased; andFIG. 4Cshows the distribution of magnetic field lines when the current applied to the magnetic coils12is decreased. Consequently, it is possible to see how the collision areas16of the magnetic field lines shown inFIG. 4Aare moved by controlling the current applied to the magnetic coils12. It is also possible to see how the separatrices8are moved by controlling the current applied to the magnetic coils12.

FIG. 4Dshows the result of calculation of the distribution of magnetic field lines when the permanent magnets13of the magnetic circuit3are replaced with magnetic coils41in the present invention (the same arrangement as that of the magnetic circuit of patent document 2). In other words,FIG. 4Dis a diagram showing the distribution of magnetic field lines when the permanent magnets13are replaced with the magnetic coils41which are arranged along the outer circumference of the side wall27such that the inner circumference of the magnetic coils contacts it. InFIG. 4D, the direction in which current is applied to the magnetic coils41coincides with the direction in which the current is applied to the magnetic coils12. Hence, the direction of magnetization of the magnetic coils41coincides with that of magnetization of the magnetic coils12. It is apparent fromFIG. 4Dthat there is no collision area of the magnetic field lines generated by the two magnetic coils.FIG. 4Eshows the result of calculation of the distribution of magnetic field lines when the current through the magnetic coils on the side of the side wall27of the vacuum vessel1ofFIG. 4Dis reversed (when the direction of magnetization of the magnetic coils12and that of magnetization of the magnetic coils41are reversed). As is apparent fromFIG. 4E, the collision areas16of the magnetic field lines appear but it is impossible to adjust the position thereof in this structure, and it is difficult to effectively adjust the uniformity of the plasma.

According to the present invention, it is possible to generate a plasma having satisfactory uniformity in a wider area than in a conventional case. An example of an effective method of determining the structure of the magnetic circuit3is to calculate the magnetic field lines. It is possible to easily perform this calculation using, for example, the finite element method. The inventors of patent document 3 have already verified that the result of the calculation closely agrees with the distribution of density of the actual plasma; in order to experimentally check the result, it is effective to use a plasma density measurement method such as a Langmuir probe.

As described above, the structure of the magnetic circuit3is devised, and thus a range having satisfactory uniformity of the plasma is expanded, and thus it is possible to process a large-area substrate more easily than in a conventional method. Moreover, the current through the magnetic coils12is varied depending on usage conditions, and thereby it is possible to perform fine adjustment on the region having satisfactory uniformity of the plasma.

As is apparent from the above description, according to the present invention, one or a plurality of magnetic coils12is concentrically arranged on the side of the atmosphere of the plasma generation chamber2opposite the substrate to be processed23, and the permanent magnets13are arranged in a ring shape on the side wall27of the plasma generation device. Current is caused to flow through the magnetic coils12in a direction so as to generate magnetic field lines downward from the center axis of the coils (the magnetic coils12are arranged such that the north poles of the magnetic coils12are positioned on the side of the vacuum vessel), and the permanent magnets13are arranged such that the north poles point to the direction of the center of the ring shape. In such a magnetic circuit structure, the current through the magnetic coils12is adjusted, and thereby it is possible to adjust the separatrices8to be formed into a desired shape, to adjust the range of the uniformity of plasma density and to realize uniform processing on the large-area substrate. The use of the magnetic coils12allows the adjustment range to be finely set, and it is possible to realize a plasma processing device that can easily and optimally adjust the range of the uniformity of plasma density.

That is, in the present embodiment, on the upper wall26of the vacuum vessel1that is the surface opposite the substrate holder21on which the substrate to be processed23is placed, the magnetic coils12in which the distribution of magnetic field lines can be adjusted by the applied current are arranged such that the north poles of the magnetic coils12point to the side of the vacuum vessel1(the inside of the vacuum vessel1) and the south poles point to the side (the outside of the vacuum vessel1) opposite the vacuum vessel1, and the permanent magnets13are arranged on the side wall27of the vacuum vessel1such that the north poles point to the side of the vacuum vessel1(the inside of the vacuum vessel1) and the south poles point to the side (the outside of the vacuum vessel1) opposite the vacuum vessel1. Therefore, the separatrices8that are generated by the magnetic field lines generated from the magnetic coils12and the magnetic field lines generated from the permanent magnets13can be formed so as to expand from the side of the magnetic coils12(the upper wall26) toward the substrate holder21.

Here, by controlling the current that is applied to the magnetic coils12, it is possible to control the shape of the separatrices8without changing the magnets for forming the separatrices8. Hence, although, in patent document 3, when the shape of separatrices8is changed, magnets for forming the separatrices8are needed to be changed as necessary, in the present embodiment, it is possible to easily adjust the shape of the separatrices8only by adjusting the value of a current applied to the magnetic coils12without changing the configuration of the magnetic circuit3. In other words, in the present embodiment, the magnetic circuit3is configured such that the shape of the magnetic field lines formed by the magnetic circuit3is the shape shown inFIGS. 4A to 4C, and one of the components of the magnetic circuit3is arranged as the magnetic coils12on the side opposite the substrate holder21. Therefore, the current that is applied to the magnetic coils12is controlled, and thereby it is possible to adjust the shape of the separatrices8that is formed so as to expand from the side of the upper wall26(the magnetic coils12) of the vacuum vessel1to the side of the substrate holder21.

Examples of the plasma processing device according to the present invention include a plasma etching device, a sputtering deposition device, a plasma CVD device and an ashing device.

In particular, in the plasma etching device, the plasma processing device is applicable to an ion beam etching device that performs microfabrication processing on an element such as MRAM containing a magnetic material such as a CoFeB/CoFe multilayer film.

FIG. 7shows an example of an ion beam etching device to which the present embodiment is applied. It is possible to obtain an ion beam having a widely uniform ion density by extracting the ion beam from the plasma generated widely and uniformly according to the present embodiment through an ion beam lens system formed with a plurality of grids4. The extracted ion beam is incident on the substrate to be processed23arranged on the substrate holder21, and thus it is possible to perform physical etching by the ion impact. Specifically, inFIG. 7, three grids (a first grid, a second grid and a third grid) are arranged vertically 2 to 3 mm apart from each other. Preferably, the diameter of the hole of the first grid is 4 mm; the diameter of the hole of the second grid is 5 mm; and the diameter of the hole of the third grid is 6 mm.

A mechanism for adjusting the angle at which the substrate is inclined is incorporated in the substrate holding mechanism6, and thus it is possible to make the ion beam obliquely incident on the substrate to be processed23, and this is effective in correcting the shape of the element.

In a semiconductor element such as an MRAM element in particular, when a chemical etching such as an RIE, which is conventionally used, is used, an unpredictable reactive layer is formed on the side surface of the element at the time of etching processing, and this may reduce the property of the element; however, the substrate inclination angle adjustment mechanism described above is utilized, and thus it is possible to remove the reactive layer.

A description will now be given of a case where the ion beam etching device of the present embodiment is used in a process of applying an ion beam.

As a multilayer magnetic film constituting a magnetoresistance effect element, for example, there is one which is one type of multilayer magnetic film (MR layer) and in which a lower electrode is formed on the substrate and a seven-layer multilayer film constituting the magnetoresistance effect element is formed thereon. In this case, as the seven-layer multilayer film, for example, there is one in which a Ta layer that is a base layer is formed on the lowest side, and, on the Ta layer, a PtMn layer that is an antiferromagnetic layer, a magnetization fixed layer (pinned layer, Ru, pinned layer), an insulation layer (barrier layer) and a free layer are stacked in this order, and a hard mask layer is stacked thereon.

The process of irradiating with an ion beam a multilayer magnetic film on which a reactive ion etching has been performed is a process of removing, with the ion beam irradiation, a damaged layer formed on the multilayer magnetic film when the reactive ion etching is performed. In this way, the layer damaged by oxidation when the reactive ion etching has been performed is removed, and thus it is possible to form a high quality multilayer magnetic film (MR layer).

In the process of applying the ion beam, the ion beam is preferably incident on a lamination plane of the multilayer magnetic film at an incident angle of 5 to 90 degrees. The reason is that the incident angle within the above range prevents or reduces the adherence of atoms and molecules of the damaged layer that has been removed by the ion beam etching mainly back to the side wall surface of the multilayer magnetic film after the removal.

Furthermore, the process of applying the ion beam is preferably performed under a condition that an accelerating voltage of the ion beam is set at 50 to 600 volts. The reason is that the above range reduces the impact of the ion beam on the multilayer magnetic film. In the view of the foregoing, the accelerating voltage of the ion beam is more preferably 50 to 200 volts.

The process of applying the ion beam is also preferably performed while the multilayer magnetic film is being rotated. The reason is that the applying of the ion beam while the multilayer magnetic film is being rotated prevents or reduces the adherence of atoms and molecules of the damaged layer that has been removed by the ion beam etching mainly back to the side wall surface of the multilayer magnetic film after the removal.

The present invention will now be described in more details with reference to accompanying drawings.

FIG. 8Ais a flowchart showing an example of a method for manufacturing the magnetoresistance effect element according to the present embodiment;FIG. 8Bis a diagram illustrating a cross-sectional structure of a pre-processing element80corresponding to the flowchart shown inFIG. 8A.

InFIG. 8B, a portion represented by reference numeral81is the multilayer magnetic film (MR layer). Examples of this multilayer magnetic film (MR layer)81includes: a TMR (tunnel magnetoresistance effect) multilayer body; a GMR (giant magnetoresistance effect) multilayer body of a CPP (current perpendicular to plane) structure; a TMR laminated body including a bias layer specifying a magnetization direction of the free layer or a GMR laminated body of the CPP structure; a GMR multilayer body of the CPP structure having an antiferromagnetic coupling multilayer film; a GMR multilayer body of the CPP structure having a specular type spin-valve magnetic multilayer film; and a GMR multilayer body of the CPP structure having a dual spin-valve type magnetic multilayer film.

As the multilayer magnetic film (MR layer)81, for example, as shown inFIG. 11, a multilayer magnetic film in which a lower electrode is formed on a substrate, and, on the lower electrode, a multilayer film constituting a magnetoresistance effect element is formed is used. In the example shown inFIG. 11, the multilayer film is formed with seven layers in which a Ta layer that is a base layer is formed on the lowest side, and, on the Ta layer, a PtMn layer that is an antiferromagnetic layer, a magnetization fixed layer (pinned layer, Ru, pinned layer), an insulation layer (barrier layer) and a free layer are stacked in this order, and a hard mask layer is stacked thereon.

A portion represented by reference numeral82inFIG. 8Bis a hard mask layer; the hard mask layer can be a mask material formed with a single layer film or a laminated film of any of single elements that are Ta (tantalum), Ti (titanium), Al (aluminum) and Si (silicon), or a mask layer formed with a single layer film or a laminated film of an oxide or a nitride of any of Ta, Ti, Al and Si.

FIG. 9is a configuration diagram illustrating an example of a manufacturing device90of the pre-processing element80of the magnetoresistance effect element according to the present embodiment.

InFIG. 9, reference numeral91represents a vacuum transport chamber; to this vacuum transport chamber91, a first reactive ion etching chamber92, a second reactive ion etching chamber93, an ion beam etching chamber94and a film formation chamber95are connected so as to communicate with the vacuum transport chamber91through a blocking means (not shown) such as a gate valve.

The vacuum transport chamber91is further provided with a wafer loader96; through this wafer loader96, the pre-processing element80can be loaded into the vacuum transport chamber91, and the element after the completion of the processing can be unloaded.

An unillustrated transport means is arranged within the vacuum transport chamber91; the pre-processing element80loaded can be sequentially transported, as indicated by arrows97,98,99,100and101, to the first reactive ion etching chamber92, then from the first reactive ion etching chamber92to the second reactive ion etching chamber93, from the second reactive ion etching chamber93to the ion beam etching chamber94and then from the ion beam etching chamber94to the film formation chamber95.

The transport of the pre-processing element80indicated by the arrows97,98,99,100and101inFIG. 9is consistently performed through the vacuum transport chamber91in a vacuum state without breaking the vacuum. The element transported from the film formation chamber95after the completion of the processing as indicated by an arrow101is unloaded from the vacuum transport chamber91to the outside through the wafer loader96.

As described above, with the manufacturing device90, the pre-processing element80is processed according to the flowchart shown inFIG. 8A.

The pre-processing element80loaded into the vacuum transport chamber91is first transported to the first reactive ion etching chamber92, where the hard mask layer82is etched with a photoresist layer83formed on the upper surface of the pre-processing element80being used as a PR mask84(step101).

Then, the pre-processing element80is transported from the first reactive ion etching chamber92to the second reactive ion etching chamber93with the vacuum state maintained. Then, by reactive ion etching using, as an etching gas, an alcohol having at least one hydroxyl group such as methanol, the multilayer magnetic film (MR layer)81is etched with the hard mask layer82used as a mask, that is, the multilayer magnetic film (MR layer)81is microfabricated (step102).

As the etching gas, an alcohol having at least one hydroxyl group is used, and this produces the effect of increasing, as compared with a conventional case where a carbon monoxide gas to which ammonia gas is added is used, the speed of etching and reducing a damaged layer (a layer degraded mainly by oxidation). For example, as the etching gas, an alcohol having at least one hydroxyl group is used, and thus it is possible to reduce the thickness of the layer degraded by oxidation to about a few tens of angstroms.

By the processing performed in the second reactive ion etching chamber93, the damaged layer85degraded mainly by oxidation is formed, as shown in the illustration of the third place from above inFIG. 8B, on the side wall and the upper surface of the multilayer magnetic film (MR layer)81or on the side wall of the multilayer magnetic film (MR layer)81and the side wall and the upper surface of the hard mask layer82whose part is left on the upper surface of the multilayer magnetic film (MR layer)81.

The pre-processing element80after the completion of the processing performed in the second reactive ion etching chamber93is then transported to the ion beam etching chamber94of the present embodiment with the vacuum state maintained. Then, in the ion beam etching chamber94, the damaged layer85is removed (step103).

The ion beam etching chamber94is a processing chamber in which the damaged layer85is remove by ion beam etching using an inert gas such as Ar (argon), Kr (krypton), Xe (xenon) or the like.

As described above, even in the reactive ion etching processing that uses an alcohol having at least one hydroxyl group and that is little damaged, the damaged layer85may be formed. Hence, this thin damaged layer85is removed by the ion beam etching processing, and thus a higher quality magnetic thin film (MR layer)81can be obtained.

In the ion beam etching performed in the ion beam etching chamber94, unlike plasma cleaning, by irradiating with a directional ion beam the laminated plane of the multilayer magnetic film at a predetermined incident angle, it is possible to prevent or reduce the re-adherence of part of atoms and molecules of the damaged layer85that has been separated by the impact of the ion beam back to the side of the multilayer magnetic film (MR layer)81.

Hence, the incident angle (an angle represented by θ with respect to the laminated plane of the multilayer magnetic film81) of the ion beam in the ion beam etching chamber94can be preferably changed to a desired angle.

The ion beam irradiation at an incident angle of 5 to 90 degrees produces the effect of preventing the re-adherence of part of atoms and molecules of the damaged layer85that has been separated by the impact of the ion beam back to the side of the multilayer magnetic film (MR layer)81.

In the ion beam etching performed in the ion beam etching chamber94, by irradiating with the ion beam the pre-processing element80while rotating it, it is possible to prevent or reduce the re-adherence of part of atoms and molecules of the damaged layer85that has been separated by the impact of the ion beam back to the side of the multilayer magnetic film (MR layer)81. Hence, for example, a support stage (not shown) that is included in the ion beam etching chamber94and that supports the pre-processing element80is preferably a rotatable support stage while the ion beam is being applied.

The damaged layer85that is formed by the reactive ion etching processing which is performed in the second reactive ion etching chamber93and which uses, as an etching gas, an alcohol having at least one hydroxyl group has a thickness of about a few tens of angstroms at most. Hence, the ion beam etching processing performed in the ion beam etching chamber94can also be performed at such a low power as not to produce new damage such as crystal damage, and does not reduce a throughput that is the amount of production per unit time in the production efficiency.

Since the damaged layer85formed when the reactive ion etching is performed in the second reactive ion etching chamber93is thinner than a damaged layer formed when the reactive ion etching using carbon monoxide gas to which a conventional ammonia gas is added is performed, it is possible to remove the damaged layer by then applying the ion beam, within a time period during which the reactive ion etching governing the production efficiency of the manufacturing device is performed. Thus, according to the method of manufacturing the magnetoresistance effect element and the manufacturing device80of the present embodiment, the throughput that is the amount of production per unit time in the production efficiency is prevented from being reduced.

The pre-processing element80after the completion of the removal of the damaged layer85is then transported, with the vacuum state maintained, to the film formation chamber95, where a protective film86is formed (step104). The multilayer magnetic film (MR layer)81that has been cleaned after the removal of the damaged layer85is covered by the protective film86, and thereby it is possible to keep the multilayer magnetic film (MR layer)81in a clean state.

One example of the protective film86is a film that is formed with, for example, aluminum oxide (Al2O3), aluminum nitride (AlN), a silicon oxide film (SiO2), a silicon nitride film (SiN) and a hafnium oxide (HfOx) or a hafnium silicon oxide (SiHfOx). The method of forming the protective film86is not particularly limited; the protective film86can be formed by PVD (physical vapor deposition) such as sputtering or CVD (chemical vapor deposition).

The method of manufacturing the magnetoresistance effect element with the manufacturing device described above will be described with reference toFIG. 10; for example, the method will be performed as follows. The pre-processing element80that has been produced as described above is carried into the manufacturing device110of the magnetoresistance effect element shown inFIG. 10.

Etching processing is performed on the pre-processing element80that is transported into the manufacturing device110of the magnetoresistance effect element by reactive ion etching means111including a hard mask layer etching means112and a multilayer magnetic film etching means113. For example, the hard mask layer is etched by the etching means112(the reactive ion etching device) that performs, with the reactive ion etching, the etching of the hard mask layer using the photoresist layer of the multilayer magnetic film as the PR mask (step S301).

Then, the multilayer magnetic film is etched by the etching means112(the reactive ion etching device) that performs, with the reactive ion etching, the etching of the multilayer magnetic film constituting the magnetoresistance effect element.

Then, the damage layer formed by the processing performed by the reactive ion etching means111is removed by ion beam application means114(ion beam etching device) (step303). The plasma processing device according to the present embodiment is preferably applied to the ion beam application means114.

Then, the multilayer magnetic film (MR layer) that has been cleaned after the removal of the damaged layer is covered with a protective film by protective film formation means115for forming a protective film (step304), is kept in a clean state and is carried out.

These processes are performed by a vacuum chamber117and a vacuum pump118constituting vacuum maintaining means116in a state in which the vacuum is maintained.

Even in this kind of in-line type manufacturing device, since the method of manufacturing the magnetoresistance effect element according to the present invention is performed and thus the damaged layer of the multilayer magnetic film (MR layer) inevitably produced by the reactive ion etching is removed by the application of the ion beam, it is possible to manufacture a high quality magnetoresistance effect element. Moreover, since yields can be improved by enhancing the magnetic characteristic, it is possible to enhance the production efficiency.

Furthermore, the application of the ion beam to remove the damage layer produced in the manufacturing of the magnetoresistance effect element is performed in the plasma processing device according to the present embodiment, and thus it is possible to apply an ion beam with a uniform plasma density and remove the damaged layer with a high quality.

Second Embodiment

Although, in the first embodiment, the magnetic circuit3includes the magnetic coils12arranged on the upper wall26such that the north pole points to the inside of the vacuum vessel1and the south pole points to the outside of the vacuum vessel1and the permanent magnets13arranged on the side wall27such that the north pole points to the inside of the vacuum vessel1and the south pole points to the outside of the vacuum vessel1, in the present embodiment, the configuration of the magnetic circuit3is not limited to this configuration.

In the present invention, as long as the magnetic circuit3in which the magnetic coils12are arranged on the side (the upper wall26) of the vacuum vessel1opposite the substrate holder21is used and thus it is possible to form the separatrices8expanding from the opposite side toward the substrate holder21, the magnetic circuit3may be freely configured.

For example, in the configuration shown inFIG. 1, the direction of the current applied to the magnetic coils12and the direction of magnetization of the permanent magnets13may be reversed such that these directions are opposite from those of the first embodiment. Specifically, the magnetic coils12may be configured such that magnetic field lines are formed to expand from the side of the side wall27toward the side of the upper wall26(the south pole of the magnetic coils points toward the inside of the vacuum vessel1and the north pole points to the outside of the vacuum vessel1), and the permanent magnets13may be arranged such that magnetic field lines are formed to expand from the outside of the side wall27toward the inside of the upper wall26(the south pole points to the inside of the vacuum vessel1and the north pole points to the outside of the vacuum vessel1).

The magnets arranged on the side wall27are not limited to permanent magnets; as long as a magnetic field can be generated, any component such as a magnetic coil or an electromagnet may be used. When, as described above, magnetic field generation means other than a permanent magnet such as a magnetic coil is used, the magnetic field generation means is arranged on the side wall27such that magnetic field lines are formed to expand from the position of the arrangement on the side wall27toward the outside or magnetic field lines are formed to expand from the outside of the position of the arrangement toward the position of the arrangement. In other words, the magnetic generation means is preferably provided such that one of the magnetic poles of the magnetic field generation means points to the inside of the vacuum vessel1and the other points to the outside of the vacuum vessel1.

The direction of magnetization of the magnetic field generation means correlates with the direction of magnetization of the magnetic coils12. In other words, it is necessary that the magnetic pole pointing to the inside of the vacuum vessel of the magnetic field generation means agree with the magnetic pole pointing toward the inside of the magnetic coils12. When, as in the first embodiment, the magnetic pole of the magnetic coils12pointing to the inside of the vacuum vessel1is a north pole, the magnetic pole of the magnetic field generation means pointing to the inside of the vacuum vessel1is a north pole. On the other hand, when the magnetic pole of the magnetic coils12pointing to the inside of the vacuum vessel1is a south pole, the magnetic pole of the magnetic field generation means pointing to the inside of the vacuum vessel1is a south pole. With this configuration, it is possible to form the separatrices8that expand from the upper wall26toward the substrate holder21.

For example, when the magnetic field generation means is magnetic coils, a plurality of magnetic coils is arranged along the outer circumference of the side wall27and the magnetic pole of the magnetic coils pointing to the inside of the vacuum vessel1agrees with the magnetic pole of the magnetic coils12pointing to the inside of the vacuum vessel1. Hence, when the magnetic pole of the magnetic coils12pointing to the inside of the vacuum vessel1is a north pole, the magnetic coils provided on the side wall27are arranged on the side wall27such that the magnetic pole pointing to the inside of the vacuum vessel1is a north pole, and the magnetic pole pointing to the outside of the vacuum vessel1is a south pole.

Although, in the above embodiments, the magnetic coils12arranged on the upper wall26are described as the configuration of a function of adjusting the shape of the separatrices8, the present invention is not limited to this configuration.

As is apparent from the above description, in the present invention, it is important that the shape of the separatrices8expanding from the upper wall26toward the substrate holder21can be adjusted without replacement of the magnetic field generation means such as a magnet. Hence, in the present invention, it is essentially important that the magnetic field generation means which can change the generated magnetic field (that is, the shape of the generated magnetic field lines) is provided. Therefore, in the present invention, as long as magnetic field generation means can adjust the generated magnetic field by a current applied thereto, the magnetic field generation means is not limited to the magnetic coils12, and any such as an electromagnet may be used.