WO2017029720A1 - Magnetic sensor and method for manufacturing same - Google Patents

Abstract

For the purpose of providing a technique that enables easy control of the magnetic anisotropy magnetic field of a device that utilizes a TMR effect, a magnetic sensor according to the present invention comprises: a magnetic sensor unit 204 which comprises a first ferromagnetic layer 201 having a fixed magnetization direction, a second ferromagnetic layer 203 having a variable magnetization direction, and a barrier layer 202 arranged between the ferromagnetic layers, and wherein the anisotropy field is more than 0 mT but 10 mT or less; an electrode 210 which fills a contact hole and is connected to the second ferromagnetic layer 203; a hydrogen stopper layer 208 which is formed on a side wall of the electrode 210; and a side wall film 212 which is formed on a side wall of the magnetic sensor unit 204 and is formed of a metal oxide or a metal nitride.

Description

Magnetic sensor and manufacturing method thereof

The present invention relates to a magnetic sensor and a manufacturing method thereof.

As a magnetic sensor for detecting a magnetic field or a current sensor for detecting a magnetic field generated by a current, there are types such as a Hall element, a magnetoresistive (MR) sensor, a SQUID (Superconducting Quantum Interference Device), and an optical pumping. Among them, the MR sensor is attracting attention because it has features such as being able to operate at room temperature and expecting high sensitivity. Among MR sensors, a magnetic sensor using a barrier layer is called a TMR sensor because it detects a magnetic field using a tunnel magnetoresistance (TMR) effect.
The basic structure of the TMR sensor is a three-layer structure in which a first ferromagnetic layer, a first barrier layer, and a second ferromagnetic layer are stacked. The characteristic is that the resistance of the TMR sensor measured along the stacking direction changes according to the relative angle of magnetization of the first ferromagnetic layer and the second ferromagnetic layer. For example, if the magnetization direction of the first ferromagnetic layer is fixed (fixed layer) and the magnetization direction of the second ferromagnetic layer is variable (detection layer), the direction and strength of the external magnetic field Accordingly, the magnetization direction of the second ferromagnetic layer changes. It is possible to detect an external magnetic field by measuring the resistance at this time. The TMR effect can also be applied to a magnetic memory (MRAM) or spin wave device. For example, Patent Documents 1 and 2 and Non-Patent Document 1 disclose TMR sensors.

JP 2013-201343 A JP 2012-119684 A

One factor that determines the performance of the TMR sensor is the magnetic anisotropy field of the detection layer. A magnetic anisotropy field is the magnitude of a magnetic field that attempts to keep magnetization in a certain direction. In order to realize a high-sensitivity TMR sensor, it is required that the magnetization of the detection layer reacts with a minute external magnetic field and the magnetization direction changes. Therefore, it is necessary to design the magnetic anisotropic magnetic field to be small. is there. On the other hand, when expanding the sensitivity region of the TMR sensor, the magnetic anisotropy magnetic field is designed to be large.

However, when manufacturing a TMR sensor, it is necessary to process the CoFeB layer and the MgO layer into a fine size (for example, several tens of nm). In order to finely process such a material, for example, reactive ion etching (RIE) using a mixed gas of CO and NH ₃ is used. However, when processing is performed using RIE, it becomes difficult to control the magnetic anisotropic magnetic field.

In MRAM, the thermal stability constant generally needs to be set to 70 or more in order to realize a sufficient recording retention time, which is a feature of the MRAM, and a magnetic anisotropic magnetic field is set so that this value can be realized. However, Patent Documents 1 and 2 do not describe the problem of magnetic anisotropy magnetic field during processing using RIE.

Also, it is desirable that the spin wave device is designed so that the magnetic anisotropy magnetic field in a part of the waveguide is larger than the other part in order to improve calculation accuracy. Originally, the magnetic anisotropy magnetic field is a value peculiar to the material, so that it was necessary to develop a material corresponding to the product and device performance. However, as described in Non-Patent Document 1, in a laminated film using CoFeB and MgO, it has become clear that the magnetic anisotropy magnetic field can be controlled by changing the CoFeB film thickness. This technique has a problem in controllability of magnetic anisotropy because it is necessary to control the film thickness at the atomic layer level.

An object of the present invention is to provide a technique capable of easily controlling the magnetic anisotropic magnetic field of a device using the TMR effect.

As an embodiment for achieving the above object, the magnetization direction including at least one of Fe or Co, the first layer having a fixed magnetization direction including at least one of Fe or Co, the MgO layer, and the magnetization direction including at least one of Fe or Co is variable. A magnetic sensor unit laminated with a second layer and having an anisotropic magnetic field of more than 0 and 10 mT or less;
An electrode that is electrically connected to the magnetic sensor unit and filled in a contact hole provided in an upper portion of the magnetic sensor unit;
A first sidewall film made of at least one of metal oxide or metal nitride formed on the sidewall of the electrode;
A second side wall film made of at least one of metal oxide or metal nitride formed on the side wall of the magnetic sensor unit;
It is set as a magnetic sensor characterized by having.

A plurality of bit lines arranged in parallel to each other;
A plurality of source lines arranged in parallel to each other and parallel to the bit lines;
A plurality of word lines arranged in parallel to each other in a direction intersecting the bit lines;
A magnetic recording element having the same structure as the magnetic sensor disposed at each intersection of the bit line and the word line;
A selection transistor connected to the magnetic recording element,
The bit line and the upper electrode of the magnetic recording element are electrically connected;
A lower electrode of the magnetic recording element and a drain electrode of the selection transistor are electrically connected;
The source line and the source electrode of the selection transistor are electrically connected;
The magnetic memory includes a memory cell in which the word line and the gate electrode of the selection transistor are electrically connected.

In addition, a first ferromagnetic layer having a fixed magnetization direction including at least one of Fe or Co, a first barrier layer, and a second ferromagnetic layer having a variable magnetization direction including at least one of Fe or Co. A spin wave waveguide in which layers are stacked;
A hydrogen stopper layer stacked above the end of the spin wave waveguide;
An upper electrode electrically connected to a part of the spin wave waveguide, spatially separated from an end of the spin wave waveguide, and filled in a contact hole provided at an upper portion of the spin wave waveguide;
A sidewall layer made of at least one of metal oxide or metal nitride formed on the sidewall of the spin wave waveguide;
The spin wave device is characterized in that an anisotropic magnetic field in the spin wave waveguide in which the hydrogen stopper layer is formed is more than 0 and 10 mT or less.

In the method for manufacturing the magnetic sensor,
On the substrate, at least the first layer in which the magnetization direction including at least one of Fe or Co is fixed, the MgO layer, and the magnetization direction including at least one of Fe or Co is variable. A first step of sequentially laminating the magnetic sensor unit laminated with a layer and a hydrogen stopper layer made of at least one of metal oxide or metal nitride;
A second step of leaving a first region of the hydrogen stopper layer and etching away a second region;
A third step of leaving the first region of the magnetic sensor unit in a gas atmosphere containing at least hydrogen and removing the second region by reactive etching;
A fourth step of oxidizing or nitriding deposits adhering to the side wall of the first region of the magnetic sensor unit by the third step;
A fifth step of forming an opening in the hydrogen stopper layer of the first region and forming the first sidewall film;
And a sixth step of filling the electrode into the opening.

In the method for manufacturing the magnetic memory,
On the substrate, at least the first layer in which the magnetization direction including at least one of Fe or Co is fixed, the MgO layer, and the magnetization direction including at least one of Fe or Co is variable. A first step of sequentially laminating the magnetic sensor unit laminated with a layer and a hydrogen stopper layer made of at least one of metal oxide or metal nitride;
A second step of leaving a first region of the hydrogen stopper layer and etching away a second region;
A third step of leaving the first region of the magnetic sensor unit in a gas atmosphere containing at least hydrogen and removing the second region by reactive etching;
A fourth step of oxidizing or nitriding deposits adhering to the side wall of the first region of the magnetic sensor unit by the third step;
A fifth step of forming an opening in the hydrogen stopper layer of the first region and forming the first sidewall film;
A sixth step of filling the opening with an electrode;
Thereafter, a seventh step of ashing in an atmosphere containing hydrogen;
A method for manufacturing a magnetic memory, comprising:

In the method for manufacturing the spin wave device,
On the substrate, at least the first layer in which the magnetization direction including at least one of Fe or Co is fixed, the MgO layer, and the magnetization direction including at least one of Fe or Co is variable. A first step of sequentially laminating a laminated film to be the spin waveguide laminated with a layer, and the hydrogen stopper layer;
A second step of leaving the hydrogen stopper layer on the end of the spin waveguide and etching away the hydrogen stopper layer in another region;
A third step of removing the laminated film by reactive etching so as to leave a region to be the spin waveguide in a gas atmosphere containing at least hydrogen;
A fourth step of oxidizing or nitriding deposits attached to the side wall of the spin waveguide by the third step;
Thereafter, a fifth step of ashing in an atmosphere containing hydrogen;
A method of manufacturing a spin wave device characterized by comprising:

In addition, a magnetic layer in which a first layer including a magnetization direction including at least one of Fe or Co is fixed, a MgO layer, and a second layer including a variable magnetization direction including at least one of Fe or Co are stacked. A sensor unit;
An electrode that is electrically connected to the magnetic sensor unit and filled in a contact hole provided in an upper portion of the magnetic sensor unit;
A first sidewall film made of at least one of metal oxide or metal nitride formed on the sidewall of the electrode;
A second side wall film formed on the side wall of the magnetic sensor portion, made of at least one of a metal oxide or a metal nitride and having a thicker film in the lower part than in the upper part;
It is set as a magnetic sensor characterized by having.

According to the present invention, it is possible to provide a technique capable of easily controlling the magnetic anisotropy magnetic field of a device using the TMR effect. Specifically, it is possible to provide a high-sensitivity TMR sensor, a wide-sensitivity region TMR sensor, an MRAM, and a spin wave device capable of high-accuracy calculation in which the magnetic anisotropic magnetic field is controlled with high accuracy. Further, it is possible to provide a method for manufacturing a TMR sensor structure capable of controlling the magnetic anisotropic magnetic field with high accuracy.

It is a graph for demonstrating the relationship between magnetic anisotropy and interface oxygen concentration. 1 is a schematic cross-sectional view of a TMR sensor according to a first embodiment of the present invention. It is a graph for demonstrating the external magnetic field dependence of resistance in the TMR sensor shown in FIG. It is sectional drawing for demonstrating the manufacturing process of the TMR sensor shown in FIG. 2, and shows the state by which various laminated films were formed on the board | substrate. It is sectional drawing for demonstrating the manufacturing process of the TMR sensor shown in FIG. 2, and the state in which the mask 209 and the hydrogen stopper layer 208 were processed is shown. FIG. 3 is a cross-sectional view for explaining a manufacturing process of the TMR sensor shown in FIG. 2 and shows a state in which an upper electrode 207 is processed halfway using a mask 209. It is sectional drawing for demonstrating the manufacturing process of the TMR sensor shown in FIG. 2, and shows the state oxidized after the upper electrode was processed halfway. It is sectional drawing for demonstrating the manufacturing process of the TMR sensor shown in FIG. 2, and shows the state by which the 2nd ferromagnetic layer 203 was processed halfway using the mask. It is sectional drawing for demonstrating the manufacturing process of the TMR sensor shown in FIG. 2, and shows the state oxidized after processing the 2nd ferromagnetic layer to the middle. It is sectional drawing for demonstrating the manufacturing process of the TMR sensor shown in FIG. 2, and shows the state by which the lower electrode 206 was processed halfway using the mask. It is sectional drawing for demonstrating the manufacturing process of the TMR sensor shown in FIG. 2, and shows the state oxidized after the lower electrode was processed halfway. FIG. 3 is a cross-sectional view for explaining a manufacturing process of the TMR sensor shown in FIG. 2 and shows a state in which an interlayer insulating film 213 is formed on an oxidized substrate. FIG. 3 is a cross-sectional view for explaining a manufacturing process of the TMR sensor shown in FIG. 2 and shows a state where a lower electrode 206 is processed. FIG. 5 is a cross-sectional view for explaining a manufacturing process of the TMR sensor shown in FIG. FIG. 5 is a cross-sectional view for explaining a manufacturing process of the TMR sensor shown in FIG. 2 and shows a state in which a contact hole 220 to the upper electrode 207 is formed. It is a flowchart of the manufacturing process of the TMR sensor shown in FIG. It is a cross-sectional schematic diagram of the TMR sensor which concerns on the 2nd Example of this invention. It is a flowchart of the manufacturing process of the TMR sensor shown in FIG. It is a flowchart which shows an example of the manufacturing process of the TMR sensor which concerns on the 3rd Example of this invention. It is a flowchart which shows the other example of the manufacturing process of the TMR sensor which concerns on the 3rd Example of this invention. It is a schematic diagram of the memory cell in MRAM based on the 5th Example of this invention. It is a plane schematic diagram of the spin wave device (2 inputs) which concerns on the 6th Example of this invention. It is a cross-sectional schematic diagram of the spin wave device shown in FIG. It is sectional drawing for demonstrating the manufacturing process of the spin wave device shown in FIG. 12, and shows the state by which the various laminated films containing the processed hydrogen stopper layer 208 were formed on the board | substrate. It is sectional drawing for demonstrating the manufacturing process of the spin wave device shown in FIG. 12, and shows the state by which the mask 209 containing the processed hydrogen stopper layer was processed. FIG. 13 is a cross-sectional view for explaining a manufacturing process of the spin wave device shown in FIG. 12 and shows a state in which the upper electrode 207 is processed halfway using a mask 209. It is sectional drawing for demonstrating the manufacturing process of the spin wave device shown in FIG. 12, and shows the state oxidized after the upper electrode was processed halfway. It is sectional drawing for demonstrating the manufacturing process of the spin wave device shown in FIG. 12, and shows the state by which the 2nd ferromagnetic layer 203 was processed halfway using the mask. It is sectional drawing for demonstrating the manufacturing process of the spin wave device shown in FIG. 12, and shows the state oxidized after processing the 2nd ferromagnetic layer to the middle. It is sectional drawing for demonstrating the manufacturing process of the spin wave device shown in FIG. 12, and shows the state by which the lower electrode 206 was processed halfway using the mask. It is sectional drawing for demonstrating the manufacturing process of the spin wave device shown in FIG. 12, and shows the state oxidized after the lower electrode was processed halfway. It is sectional drawing for demonstrating the manufacturing process of the spin wave device shown in FIG. 12, and shows the state by which the interlayer insulation film 213 was formed on the oxidized board | substrate. It is sectional drawing for demonstrating the manufacturing process of the spin wave device shown in FIG. 12, and shows the state by which the lower electrode 206 was processed. It is sectional drawing for demonstrating the manufacturing process of the spin wave device shown in FIG. 12, and shows the state by which the interlayer insulation film 213 was formed on the board | substrate with which the lower electrode was processed. FIG. 13 is a cross-sectional view for explaining a manufacturing process of the spin wave device shown in FIG. 12 and shows a state in which a contact hole 220 to the upper electrode 207 is formed.

Embodiments of the present invention will be described below by taking as an example the case where CoFeB is applied to the first and second ferromagnetic layers and MgO is applied to the first barrier layer.

At the laminated interface between the CoFeB layer and the MgO layer, the structure in which Fe and O are bonded one-to-one is stable. At this time, a bond orbit of iron (Fe) and oxygen (O) is formed at the laminated interface, and as a result, the magnetic anisotropy field increases. Therefore, as shown in FIG. 1, the magnetic anisotropy field becomes maximum when the ratio of Fe to O is 1: 1, and the magnetic anisotropy field decreases as O increases with respect to Fe.

On the other hand, when reactive ion etching (RIE) using a mixed gas of CO and NH _{3 or} the like is used for processing a magnetic material, hydrogen (hydrogen radicals, hydrogen ions) is generated in the processing chamber during etching and a reducing atmosphere is formed. . For this reason, the reduction reaction proceeds during the RIE process at the CoFeB / MgO laminated interface, and the magnetic anisotropy field decreases because the oxygen concentration at the interface decreases (the reaction proceeds to the right in FIG. 1). Since this reduction reaction occurs incidentally during etching, it is difficult to control. On the other hand, increasing the magnetic anisotropy magnetic field again by applying an oxidation treatment after RIE processing is less efficient than hydrogen. This is because it is difficult for oxygen having an atomic radius larger than hydrogen to reach the interface as compared with hydrogen. Therefore, here, by applying a structure for suppressing the reduction reaction during etching, the magnetic anisotropy magnetic field is kept in the region 1 in FIG. 1, and the magnetic anisotropy magnetic field is gently applied by hydrogen reduction after the etching. It was decided to control. For example, in the case of a high-sensitivity magnetic sensor, hydrogen reduction processing is performed with the region 2 as a target value.

As a structure for suppressing the reduction reaction during etching, a hydrogen stopper layer stacked above the magnetic sensor unit is applied. The hydrogen stopper layer plays a role of preventing hydrogen from entering the magnetic sensor unit from above the magnetic sensor unit during etching. The hydrogen stopper layer is preferably a metal oxide from the viewpoint of preventing hydrogen from entering. When the metal oxide is an insulator, it is necessary to process a contact hole that penetrates the metal oxide to form an electrode that is electrically connected to the upper part of the magnetic sensor portion after etching. When the metal oxide is a conductor, it is not necessary to penetrate the metal oxide. It is also conceivable to use the hydrogen stopper layer as a hard mask for etching. If the hydrogen stopper layer is not used as a hard mask, a separate hard mask is prepared. The hydrogen stopper layer after the contact hole is formed becomes the first sidewall layer remaining on the sidewall of the upper electrode.

Another structure for suppressing the reduction reaction during etching is a second side wall layer provided on the side wall of the magnetic sensor unit. After patterning the hydrogen stopper layer (and hard mask layer) to form a mask, the magnetic sensor portion is processed by RIE. At this time, the removed first ferromagnetic layer, first barrier layer, and second ferromagnetic layer (which may include a part of the upper electrode and the lower electrode) are the side walls of the magnetic sensor section after processing. Laminate as a re-attachment on the processing surface. In order to prevent hydrogen from entering the magnetic sensor portion from the side and the reduction reaction proceeding, the side wall re-adhered material is oxidized to form side wall oxide. This sidewall oxide layer is the second sidewall layer. In order to efficiently suppress the entry of hydrogen, a method of repeating the RIE process and the redeposition oxidation process is desirable. In the case where the RIE process and the redeposition material oxidation process are performed in one processing chamber, exhaust of the gas used for RIE after the RIE process and exhaust of oxygen after the oxidation process are essential. When the oxidation chamber is prepared separately from the processing chamber, RIE and oxidation can be repeated without considering the exhaust time if there is a transfer system for transferring the wafer.

The TMR sensor that has undergone the above steps includes a hydrogen stopper layer on the top and a first side wall layer and a second side wall layer on the side surface, and the reduction reaction due to hydrogen is suppressed, so that the magnetic anisotropy is high. 1 remains in region 1. Here, a contact hole is opened in the upper hydrogen stopper layer, or the hydrogen stopper layer is removed by CMP or the like. This allows hydrogen to enter from the top surface. Thereafter, it is possible to gradually adjust the magnetic anisotropy (region 2 in FIG. 1) by slowly applying a hydrogen reduction treatment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. This example does not limit the present invention. In addition, the same code | symbol shows the same component.

FIG. 2 is a schematic sectional view of the TMR sensor according to the first embodiment of the present invention. This TMR sensor was produced for the purpose of increasing the sensitivity (region 2 in FIG. 1). As shown in the schematic cross-sectional view of FIG. 2, the first ferromagnetic layer 201, the barrier layer 202, and the second ferromagnetic layer 203 are laminated in this order to form the magnetic sensor unit 204. The magnetic sensor unit 204 has a pillar shape and is disposed on the lower electrode 206 stacked on the substrate 205. An upper electrode 207 is stacked above the magnetic sensor unit, and a hydrogen stopper layer 208 and a hard mask layer 209 are stacked above the upper electrode 207. The upper electrode 207, the hydrogen stopper layer 208, and the hard mask layer 209 have a pillar shape similar to the magnetic sensor unit 204. Contact holes are formed in the hydrogen stopper layer 208 and the hard mask layer 209, and the wiring layer 210 is connected to the upper electrode 207 through the contact holes. For this reason, the hydrogen stopper layer 208 and the hard mask layer 209 are the side walls of the wiring layer 210, and this is the first side wall layer 211. A magnetic sensor portion 204 processed into a pillar shape and an oxidized second sidewall layer 212 are formed. Further, the TMR sensor is covered with the interlayer insulating film 213, and the upper electrode 207 and the lower electrode 206 are connected via the magnetic sensor unit 204. The stacking order of the hydrogen stopper layer 208 and the hard mask layer 209 may be reversed.

In this TMR sensor, CoFeB was adopted as the material of the first ferromagnetic layer 201, and the film thickness was 0.9 nm. MgO was used as the barrier layer 202, and the film thickness was 1.0 nm. CoFeB was adopted as the second ferromagnetic layer 203, and the film thickness was 1.6 nm. The difference in film thickness between the first ferromagnetic layer 201 and the second ferromagnetic layer 203 is to make a difference in the coercive force of the respective layers. The ferromagnetic layer 203 operates as a detection layer. In order to increase the coercive force difference, a Co / Pt multilayer film or the like may be added instead of using two CoFeB layers as single ferromagnetic layers. The hydrogen stopper layer 208 is made of MgO and has a thickness of 20 nm. The hard mask layer 209 is made of Ta and has a thickness of 100 nm.

FIG. 3 shows the external magnetic field dependence of the resistance in this TMR sensor. The magnetic anisotropy magnetic field of the second ferromagnetic layer 203 as the detection layer is controlled to 2 mT.

Next, the manufacturing method of this TMR sensor is demonstrated using FIG. 4A thru | or FIG. 4L. This TMR sensor was manufactured through the following steps.
<First Step>: From the substrate surface, the lower electrode 206, the first ferromagnetic layer 201, the barrier layer 202, the second ferromagnetic layer 203, the upper electrode layer 207, the hydrogen stopper layer 208, and the Ta hard mask layer 209 Are stacked in this order (FIG. 4A).
<Second Step>: A pillar type resist mask is formed on the Ta hard mask layer 209, and the hydrogen stopper layer 208 and the Ta hard mask layer 209 are processed into a pillar type (FIG. 4B).
<Third Step>: Using the hydrogen stopper layer 208 and the Ta hard mask layer 209 as a mask, the upper electrode 207 and the magnetic sensor unit are etched for 2 minutes by RIE using a mixed gas of CO and NH ₃ (FIG. 4C).
<Fourth Step>: The substrate is transferred from the processing chamber for performing RIE to the oxidation chamber and oxidized (FIG. 4D).
The substrate is returned to the processing chamber again, and the third and fourth steps are repeated, and etching by RIE is advanced to the vicinity of the surface of the lower electrode 206 (FIGS. 4E to 4H).
<Fifth Step>: The interlayer insulating film 213 is stacked (FIG. 4I), and the lower electrode 206 is manufactured (FIG. 4J).
<Sixth Step>: The lower electrode 206 is again protected by the interlayer insulating film 213 (FIG. 4K), and a contact hole 220 is opened in the hydrogen stopper layer 208 and the Ta hard mask 209 (FIG. 4L).
<Seventh Step>: The wiring layer 210 is produced (FIG. 2). In the wiring layer, a portion formed in the contact hole may be referred to as an electrode.

After passing through the seventh step, the substrate on which the TMR sensor was manufactured was subjected to ashing with a H ₂ / He mixed gas containing 10% H ₂ for 180 seconds, and the magnetic anisotropy was adjusted so as to be a region 2 in FIG. .

These steps are summarized in the flowchart of FIG. S501 corresponds to the first step, S502 corresponds to the second step, S503 corresponds to the third step, S504 corresponds to the fourth step, S505 corresponds to the fifth step and the sixth step, and S506 corresponds to the seventh step. When the magnetic sensor unit 204 is processed in the third step (S503), the processed material is reattached to the pillar side wall and the surface to be etched. In the fourth step (S504), these redeposits are oxidized. The hydrogen stopper layer 208 and the oxidized second sidewall layer 212 can prevent hydrogen from entering the magnetic sensor portion. As a result, the composition ratio of Fe and O at the interface is considered to be a ratio close to 1: 1.

Thereafter, the TMR sensor on the substrate was subjected to hydrogen reduction treatment (S507). In this TMR sensor, ashing with a H ₂ / He mixed gas containing 10% H ₂ was performed for 180 seconds. As a result, hydrogen enters the magnetic sensor portion through the contact hole, and the oxygen concentration at the interface gradually decreases. In the case of the present TMR sensor, the magnetic anisotropy field was about 10 mT before ashing with the H ₂ / He mixed gas, but decreased to 2 mT as shown in FIG. At this time, it is considered that the composition ratio of Fe and O is reduced to about 1/5 of that before ashing with the H ₂ / He mixed gas. The composition ratio of Fe and O in the vicinity of the interface can be examined by a composition analysis using a transmission electron microscope (TEM). According to the present embodiment, the magnetic anisotropy magnetic field can be controlled to exceed 0 and not more than 10 mT. Further, the interface between the MgO barrier layer and the second ferromagnetic layer is preferably more Fe than O, and more preferably Fe is 1/10 or more and 1/2 or less than O.

As described above, according to the present embodiment, it is possible to provide a technique capable of easily controlling the magnetic anisotropic magnetic field of a device using the TMR effect. In addition, a highly sensitive TMR sensor can be provided.

A second embodiment of the present invention will be described. Note that the matters described in the first embodiment but not described in the present embodiment can be applied to the present embodiment as long as there is no particular circumstance.

In Example 1, the example using the hard mask layer 209 has been described. When the hard mask layer 209 is not used, the hydrogen stopper layer 208 can be used as a mask. In Example 2, the hard mask layer 209 was not used, MgO was used for the hydrogen stopper layer 208, and the film thickness was 100 nm. FIG. 6 is a schematic cross-sectional view of a TMR sensor according to the second embodiment. In Example 2, since the hard mask layer 209 is not used, the structure is simple. However, since the selection ratio at the time of etching by RIE is small, the processing is somewhat difficult as compared with Example 1.

In the present TMR sensor, in order to electrically connect the upper electrode 207 and the wiring layer 210 in the sixth step, the hydrogen stopper layer 208 is removed using chemical mechanical polishing (CMP) to expose the upper electrode 207. Then, the wiring layer 210 was produced. Further, after passing through the seventh step, it was divided for each TMR sensor produced on the substrate, and thereafter ashing with a H ₂ / He mixed gas was performed. By dividing for each TMR sensor, the ashing time can be changed for each TMR sensor, so that different characteristics can be produced. This TMR sensor when the ashing time was 180 seconds had a magnetic anisotropic magnetic field of about 2 mT, and showed the same performance as the TMR sensor described in Example 1. The manufacturing steps of this TMR sensor are summarized in the flowchart of FIG.

As described above, according to the present embodiment, the same effects as those of the first embodiment can be obtained. Compared to the first embodiment, the structure can be simplified.

A third embodiment of the present invention will be described. Note that matters described in the first or second embodiment but not described in the present embodiment can also be applied to the present embodiment unless there are special circumstances.

Examples of production steps different from the production steps of the TMR sensor shown in FIG. 5 described in Example 1 and FIG. 7 described in Example 2 are summarized in the flowcharts of FIGS.

8 and 5 are different from each other. (1) In FIG. 5, the hydrogen stopper layer and the hard mask are processed in step S502, but the corresponding step S802 includes only the hydrogen stopper layer. Further, (2) in FIG. 5, the oxidation is performed in step S504, but the corresponding S804 includes not only the oxidation but also the nitridation.

9 differs from FIG. 7 in that (1) in FIG. 7, the hydrogen stopper layer is processed in step S702, but the corresponding step S902 includes processing of the hydrogen stopper layer and the hard mask layer. It is out. (2) In FIG. 7, oxidation is performed in step S704, but the corresponding S804 includes not only oxidation but also nitridation. The same performance as in Examples 1 and 2 was obtained for the TMR elements manufactured by these methods.

As described above, according to the present embodiment, the same effects as those of the first embodiment can be obtained. Compared to the first embodiment, the structure can be simplified.

A fourth embodiment of the present invention will be described. Note that matters described in any of the first to third embodiments but not described in the present embodiment can also be applied to the present embodiment unless there are special circumstances.

The TMR sensors of Examples 1 to 3 were intended for high sensitivity, and the magnetic anisotropy magnetic field was a small value of about 2 mT. On the other hand, if the magnetic anisotropy magnetic field is small, the magnetization of the detection layer is saturated by a minute magnetic field, so that the TMR sensor cannot react even when a magnetic field higher than that is applied. For this reason, when it is assumed that the TMR resistance change rate is the same, the high sensitivity and the wide sensitivity region have a trade-off relationship. Therefore, it is necessary to increase the magnetic anisotropy in order to expand the sensitivity region of the TMR sensor.

The cross-sectional schematic diagram of the TMR sensor described in this example is basically the same as the TMR element described in Example 1 (FIG. 2), and includes a hydrogen stopper layer 208, a first sidewall layer 211, and a second sidewall. A TMR sensor structure including a layer 212. The change is that the film thickness of the second ferromagnetic layer 203 is set to 1.4 nm (1.6 nm in Example 1). The purpose of this change is to increase the magnetic anisotropy magnetic field of the second ferromagnetic layer 203 at the time immediately after the first step (step S501).

The TMR sensor manufacturing method described in Example 4 is different from the TMR sensor manufacturing method described in Example 1 except that the film thickness of the second ferromagnetic layer 203 is different from that of H ₂ / He. The ashing time by mixed gas is different. Ashing with a H ₂ / He mixed gas was performed for 30 seconds (180 seconds in Example 1). The magnetic anisotropic magnetic field of the TMR sensor was 150 mT, and the TMR sensor had a sensitivity region 75 times that of the TMR sensor described in Example 1. Further, by adjusting the ashing time with the H ₂ / He mixed gas, the magnitude of the magnetic anisotropic magnetic field can be controlled, so that a TMR sensor having a desired sensitivity region can be manufactured.

The TMR sensor manufacturing method described in Example 2 and Example 3 can be applied to the TMR sensor described in Example 4. Also in this case, the film thickness of the second ferromagnetic layer 103 and the ashing time by the H ₂ / He mixed gas are different.

As described above, according to this embodiment, it is possible to provide a technique capable of controlling the magnetic anisotropy magnetic field of a device using the TMR effect. In addition, a TMR sensor having a wide sensitivity region can be provided.

A fifth embodiment of the present invention will be described. Note that the matters described in any one of the first to fourth embodiments but not described in the present embodiment can be applied to the present embodiment unless there are special circumstances.

In this embodiment, an MRAM using the TMR effect will be described. The manufacturing steps of the TMR sensor described in the first to fourth embodiments can be applied not only to the TMR sensor but also to a part of the manufacturing process of the MRAM. MRAM, which is a non-volatile memory, has a feature that keeps recording even when power is cut off. The recording retention time depends on the thermal stability constant of the TMR element which is an MRAM recording element. In order to realize a recording retention time of 10 years, a thermal stability constant of 40 or more is required for one recording element. When considering the entire MRAM, a thermal stability constant of about 70 is generally required, although it depends on the capacity of the MRAM.

熱 The thermal stability constant depends on the magnetic anisotropy field, and the recording retention time becomes longer if the magnetic anisotropy field is larger. On the other hand, the writing of information in the MRAM uses magnetization reversal by spin-transfer “torque” that occurs when a current flows through the TMR element. The condition for operating the MRAM is that the write current is equal to or less than the drive current of the selection transistor. Similarly, since the write current depends on the magnetic anisotropy magnetic field, the MRAM cannot operate if the magnetic anisotropy is too high from the viewpoint of the write current. Therefore, the magnetic anisotropic magnetic field needs to be controlled to a constant value even in the MRAM.

FIG. 10 is a schematic diagram of a memory cell of a magnetic memory (MRAM) using a TMR element having the same structure as that of the magnetic sensor described in the first embodiment (the same structure as FIG. 2) as a recording element. The MRAM includes a plurality of memory cells, and each memory cell includes a combination of a TMR element 1001 and a select transistor 1002. The drain electrode of the selection transistor 1002 fabricated on the substrate and the lower electrode 206 of the TMR element are electrically connected. The source electrode of the selection transistor 1002 is connected to the source line 1003, and the gate electrode is connected to the word line 1004. In this MRAM, a plurality of source lines are arranged in parallel to each other, and a plurality of word lines are arranged in parallel to each other in a direction intersecting the source lines. Each bit line connected to the wiring layer 210 of each TMR element is arranged in parallel with the source line and in parallel with each other. Note that the names of the source, the drain, and the like are for convenience, and when one is a source, the other can be called a drain. In the memory cell described in the fifth embodiment, a process of manufacturing a TMR element is continued on a substrate that has undergone a CMOS process of manufacturing a transistor. The process for manufacturing the TMR element is the first to seventh steps described in the first embodiment. After producing the wiring layer of the seventh step, the magnetic anisotropic magnetic field is adjusted to an optimum value for the MRAM by ashing with a H ₂ / He mixed gas. When ashing with a H ₂ / He mixed gas was performed for 30 seconds, the thermal stability constant Δ was 70, and the write current I _c was 130 μA. The thermal stability constant Δ was 34 and the write current I _c was 63 μA when ashing with a H ₂ / He mixed gas was performed for 300 seconds. When these two conditions are compared, the ashing with the H ₂ / He mixed gas is preferably 30 seconds. These conditions also need to be adjusted depending on the size of the TMR element that differs for each MRAM technology generation.

As described above, according to the present embodiment, it is possible to provide a technique capable of easily controlling the magnetic anisotropic magnetic field of a device using the TMR effect. In addition, an MRAM having a high thermal stability constant can be provided.

The present invention is also applicable to known spin wave devices. A spin wave is a collective motion of a magnetic moment in a ferromagnetic layer and propagates as a wave in the ferromagnetic layer. In the propagation of the spin wave, for example, the phase 0 and π of the spin wave can be applied to the bit information. This bit information propagates through the ferromagnetic layer and can be detected at a location separated from the space. In addition, it is possible to perform a logical operation using the spin wave interference phenomenon. FIG. 11 is a schematic plan view of a two-input spin wave device according to the present embodiment. The two spin waves input by the excitation unit 1101 in FIG. 11 propagate through the waveguide 1102 and interfere with each other by the arithmetic unit 1103 to reach the detection unit 1104 and be detected as one spin wave. When the interference phenomenon is used as a logical operation, the phase detection accuracy in the detection unit affects the calculation accuracy.

However, since the spin wave is reflected at the spin wave waveguide end 1105 ahead of the detection unit 1104, the calculation accuracy may be lowered. This is because when the reflected wave reaches the detection unit 1104 again, it interferes with the calculated output wave again, and erroneous detection occurs in the detection unit 1104. In order to suppress the influence of the reflected wave, the motion of the magnetic moment may be suppressed at the spin wave waveguide end 1105. For this reason, it is desirable that the magnetic anisotropy of the spin wave waveguide end 1105 be relatively large. On the other hand, when the magnetic anisotropy magnetic field is small, the amplitude of the spin wave becomes large. Therefore, it is desirable that the magnetic anisotropy magnetic field is small in the portion other than the spin wave waveguide end 1105. For this reason, the spin wave device needs to be designed so that only the magnetic anisotropic magnetic field of the spin wave waveguide end 1105 is larger than the other parts.

A schematic cross-sectional view of the spin wave device described in Example 6 is shown in FIG. A feature of the spin wave device described in the sixth embodiment is that the stopper layer 208 is formed only at the end portion 1105 of the spin wave waveguide. Hereinafter, the manufacturing method of the spin wave device will be described with reference to FIGS. 13A to 13L.
<First Step>: A lower electrode 206, a first ferromagnetic layer 201, a barrier layer 202, a second ferromagnetic layer 203, an upper electrode layer 207, and a hydrogen stopper layer 208 are stacked in this order from the substrate surface. Next, the hydrogen stopper layer 208 is removed leaving only the portion directly above the waveguide end 1105. Thereafter, a Ta hard mask layer 209 is stacked (FIG. 13A).
<Second Step>: A waveguide type resist mask is formed on the Ta hard mask mask layer 209, and the Ta hard mask layer 209 is processed into a waveguide type (FIG. 13B).
<Third Step>: Using the Ta hard mask layer 209 as a mask, the magnetic sensor part is etched by RIE using a mixed gas of CO and NH ₃ for 2 minutes (FIG. 13C).
<Fourth Step>: The substrate is transferred from the processing chamber in which RIE is performed to the oxidation chamber and is oxidized (FIG. 13D).
The substrate is returned to the processing chamber again, and the third and fourth steps are repeated, and the etching by RIE is advanced to the vicinity of the surface of the lower electrode 206 (FIGS. 13E to 13H).
<Fifth Step>: The interlayer insulating film 213 is stacked (FIG. 13I), and the lower electrode 206 is manufactured (FIG. 13J).
<Sixth Step>: The lower electrode 206 is protected again by the interlayer insulating film 213 (FIG. 13K), and a contact hole 220 is opened in the Ta hard mask 209 (FIG. 13L).
<Seventh Step>: The wiring layer 210 is produced (FIG. 12). In the wiring layer, a portion formed in the contact hole may be referred to as an electrode.
After the seventh step, the substrate on which the TMR sensor was manufactured was subjected to ashing with a H ₂ / He mixed gas for 180 seconds to adjust the magnetic anisotropic magnetic field.

Through the above steps, the magnetic anisotropy magnetic field of the spin wave waveguide end 1105 was increased about five times as compared with other portions. Thereby, the influence of the reflected wave can be suppressed and good characteristics can be obtained.

Although the contact hole opening process is adopted in the sixth step, CMP can also be used. Further, the waveguide 1102 other than the detection unit 1104 can operate even if the second ferromagnetic layer 203 is removed by etching.

As described above, according to the present embodiment, it is possible to provide a technique capable of easily controlling the magnetic anisotropic magnetic field of a device using the TMR effect. In addition, a spin wave device with high calculation accuracy can be provided.

In addition, this invention is not limited to the above-mentioned Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of a certain embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of a certain embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

The present invention includes the following embodiments.
(1) A first layer having a fixed magnetization direction including at least one of Fe or Co, an MgO layer, and a second layer having a variable magnetization direction including at least one of Fe or Co are stacked. A magnetic sensor unit having an anisotropic magnetic field of more than 0 and 10 mT or less;
Wiring electrically connected to the magnetic sensor unit;
A sidewall film formed of at least one of metal oxide or metal nitride formed on the sidewall of the magnetic sensor unit;
A magnetic sensor comprising:
(2) In the method for manufacturing the magnetic sensor,
On the substrate, at least the first layer in which the magnetization direction including at least one of Fe or Co is fixed, the MgO layer, and the magnetization direction including at least one of Fe or Co is variable. A first step of sequentially laminating the magnetic sensor unit laminated with a layer and a hydrogen stopper layer made of at least one of metal oxide or metal nitride;
A second step of leaving a first region of the hydrogen stopper layer and etching away a second region;
A third step of leaving the first region of the magnetic sensor unit in a gas atmosphere containing at least hydrogen and removing the second region by reactive etching;
A fourth step of oxidizing or nitriding deposits adhering to the side wall of the first region of the magnetic sensor unit by the third step;
A fifth step of removing the hydrogen stopper layer in the first region by CMP;
A sixth step of forming the wiring in the magnetic sensor portion exposed in the fifth step;
A method of manufacturing a magnetic sensor, comprising:

DESCRIPTION OF SYMBOLS 201 ... 1st ferromagnetic layer, 202 ... Barrier layer, 203 ... 2nd ferromagnetic layer, 204 ... Magnetic sensor part, 205 ... Substrate, 206 ... Lower electrode, 207 ... Upper electrode, 208 ... Hydrogen stopper layer, 209 DESCRIPTION OF SYMBOLS ... Hard mask layer, 210 ... Wiring layer, 211 ... First sidewall layer, 212 ... Second sidewall layer, 213 ... Interlayer insulating film, 220 ... Contact hole, 1001 ... TMR element, 1002 ... Selection transistor, 1003 ... Source Line 1004 ... Word line 1101 ... Excitation part 1102 ... Waveguide 1103 ... Operation part 1104 ... Detection part 1105 ... Spin wave waveguide end part.

Claims (15)

1. A first layer having a fixed magnetization direction including at least one of Fe or Co, an MgO layer, and a second layer having a variable magnetization direction including at least one of Fe or Co are laminated, and anisotropy A magnetic sensor having a magnetic field exceeding 0 and 10 mT or less;
   An electrode that is electrically connected to the magnetic sensor unit and filled in a contact hole provided in an upper portion of the magnetic sensor unit;
   A first sidewall film made of at least one of metal oxide or metal nitride formed on the sidewall of the electrode;
   A second side wall film made of at least one of metal oxide or metal nitride formed on the side wall of the magnetic sensor unit;
   A magnetic sensor comprising:
2. The magnetic sensor according to claim 1,
   The magnetic sensor according to claim 1, wherein a film thickness in the height direction of the first side wall film is larger than a film thickness in the lateral direction of the second side wall film.
3. The magnetic sensor according to claim 1,
   The magnetic sensor according to claim 1, wherein the first sidewall film has a thickness in the height direction of 10 nm or more.
4. The magnetic sensor according to claim 1,
   The magnetic sensor according to claim 1, wherein the second sidewall film is an oxide and / or a nitride of a metal material constituting the magnetic sensor unit.
5. The magnetic sensor according to claim 1,
   The magnetic sensor, wherein the interface between the MgO layer and the second layer has more Fe than O.
6. The magnetic sensor according to claim 5, wherein
   The interface of the MgO layer and the second layer is characterized in that Fe is more than 1/10 and 1/2 or less than O.
7. A plurality of bit lines arranged in parallel to each other;
   A plurality of source lines arranged in parallel to each other and parallel to the bit lines;
   A plurality of word lines arranged in parallel to each other in a direction intersecting the bit lines;
   A magnetic recording element having the same structure as the magnetic sensor according to claim 1 disposed at each intersection of the bit line and the word line;
   A selection transistor connected to the magnetic recording element,
   The bit line and the upper electrode of the magnetic recording element are electrically connected;
   A lower electrode of the magnetic recording element and a drain electrode of the selection transistor are electrically connected;
   The source line and the source electrode of the selection transistor are electrically connected;
   A magnetic memory comprising a memory cell in which the word line and the gate electrode of the selection transistor are electrically connected.
8. A first ferromagnetic layer having a fixed magnetization direction including at least one of Fe or Co, a first barrier layer, and a second ferromagnetic layer having a variable magnetization direction including at least one of Fe or Co; A spin wave waveguide laminated with
   A hydrogen stopper layer stacked above the end of the spin wave waveguide;
   An upper electrode electrically connected to a part of the spin wave waveguide, spatially separated from an end of the spin wave waveguide, and filled in a contact hole provided at an upper portion of the spin wave waveguide;
   A sidewall layer made of at least one of metal oxide or metal nitride formed on the sidewall of the spin wave waveguide;
   The spin wave device, wherein an anisotropic magnetic field in the spin wave waveguide in which the hydrogen stopper layer is formed is more than 0 and 10 mT or less.
9. A magnetic sensor unit in which a first layer including a magnetization direction including at least one of Fe or Co is fixed, a MgO layer, and a second layer including a variable magnetization direction including at least one of Fe or Co. When,
   An electrode that is electrically connected to the magnetic sensor unit and filled in a contact hole provided in an upper portion of the magnetic sensor unit;
   A first sidewall film made of at least one of metal oxide or metal nitride formed on the sidewall of the electrode;
   A second side wall film formed on the side wall of the magnetic sensor portion, made of at least one of a metal oxide or a metal nitride and having a thicker film in the lower part than in the upper part;
   A magnetic sensor comprising:
10. In the manufacturing method of the magnetic sensor of Claim 1,
    On the substrate, at least the first layer in which the magnetization direction including at least one of Fe or Co is fixed, the MgO layer, and the magnetization direction including at least one of Fe or Co is variable. A first step of sequentially laminating the magnetic sensor unit laminated with a layer and a hydrogen stopper layer made of at least one of metal oxide or metal nitride;
    A second step of leaving a first region of the hydrogen stopper layer and etching away a second region;
    A third step of leaving the first region of the magnetic sensor unit in a gas atmosphere containing at least hydrogen and removing the second region by reactive etching;
    A fourth step of oxidizing or nitriding deposits adhering to the side wall of the first region of the magnetic sensor unit by the third step;
    A fifth step of forming an opening in the hydrogen stopper layer of the first region and forming the first sidewall film;
    And a sixth step of filling the opening with an electrode.
11. In the manufacturing method of the magnetic sensor according to claim 10,
    The method of manufacturing a magnetic sensor, wherein the third step and the fourth step are repeated.
12. In the manufacturing method of the magnetic sensor according to claim 10,
    An ashing process is performed in an atmosphere containing hydrogen after the fifth step.
13. In the manufacturing method of the magnetic sensor according to claim 10,
    Forming a hard mask layer between the magnetic sensor portion and the hydrogen stopper layer in the first step;
    A method of manufacturing a magnetic sensor, wherein the hard mask layer is etched away between the second step and the third step using the first region of the hydrogen stopper layer as a mask.
14. The method of manufacturing a magnetic memory according to claim 7.
    On the substrate, at least the first layer in which the magnetization direction including at least one of Fe or Co is fixed, the MgO layer, and the magnetization direction including at least one of Fe or Co is variable. A first step of sequentially laminating the magnetic sensor unit laminated with a layer and a hydrogen stopper layer made of at least one of metal oxide or metal nitride;
    A second step of leaving a first region of the hydrogen stopper layer and etching away a second region;
    A third step of leaving the first region of the magnetic sensor unit in a gas atmosphere containing at least hydrogen and removing the second region by reactive etching;
    A fourth step of oxidizing or nitriding deposits adhering to the side wall of the first region of the magnetic sensor unit by the third step;
    A fifth step of forming an opening in the hydrogen stopper layer of the first region and forming the first sidewall film;
    A sixth step of filling the opening with an electrode;
    Thereafter, a seventh step of ashing in an atmosphere containing hydrogen;
    A method of manufacturing a magnetic memory, comprising:
15. In the manufacturing method of the spin wave device according to claim 8,
    On the substrate, at least the first layer in which the magnetization direction including at least one of Fe or Co is fixed, the MgO layer, and the magnetization direction including at least one of Fe or Co is variable. A first step of sequentially laminating a laminated film to be the spin waveguide laminated with a layer, and the hydrogen stopper layer;
    A second step of leaving the hydrogen stopper layer on the end of the spin waveguide and etching away the hydrogen stopper layer in another region;
    A third step of removing the laminated film by reactive etching so as to leave a region to be the spin waveguide in a gas atmosphere containing at least hydrogen;
    A fourth step of oxidizing or nitriding deposits attached to the side wall of the spin waveguide by the third step;
    Thereafter, a fifth step of ashing in an atmosphere containing hydrogen;
    A method of manufacturing a spin wave device, comprising:

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