JPS6257193A - Magnetic bubble element - Google Patents

Abstract

PURPOSE:To eliminate the variance of an in-plane magnetized layer and to realize a stable element characteristic, and further, to improve reproducibility and reliability by forming a transferring path making ion implantation in a crystal orientation having a channeling by hydrogen ion. CONSTITUTION:Hydrogen ion is implanted deeply in a bubble film in crystal orientation having channeling effect. Then, the second ion is implanted to desired depth in the surface area of the bubble film making the channeling effect off and a uniform flat damage layer (curve 5) is formed. Further, hydrogen is thermally diffused toward the film surface by using annealing process. At this time, hydrogen is trapped by the damage layer (empty bond in a crystal) formed beforehand, and an ion implanted layer (curve 6) in which uniform flat strain and hydrogen are distributed simultaneously is formed. Accordingly, this layer functions as an in-plane magnetized layer for bubble transferring.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention provides a method for forming a strained layer with large in-plane magnetization in a magnetic bubble element that forms a shivering transfer path by ion implantation. The present invention relates to hydrogen ion implantation, and particularly to bubble transfer path formation using an ion implantation method suitable for producing bubble transfer paths with high thermal stability and good reproducibility.

[Background of the invention]

In the ion implantation bubble transfer path, after forming a mask pattern on the magnetic bubble film, H2''IHf!, Ne
Ions such as + are implanted into the bubble membrane surface to create a bubble transfer path.

Conventional devices use hydrogen ion implantation, in which the in-plane magnetization of the strained layer increases approximately in proportion to the ion implantation strain, to a desired depth of the bubble film.During the ion implantation, the crystal orientation produces a channeling effect depending on the ion incidence angle. I've been doing this with it turned off. The depth of the strained layer, that is, the in-plane magnetization layer, necessary to obtain good transfer characteristics is preferably about 1/3 of the bubble film thickness from the surface. Therefore, the distribution of hydrogen 1 on with the channeling effect turned off is:
Compared to this strain distribution, the strain is distributed at a slightly deeper position as shown in FIG. That is, in the conventional element, the distribution position of hydrogen ions is originally in a shallow surface layer immediately after ion implantation.

On the other hand, in conventional devices using this hydrogen ion implantation,
As described in Japanese Patent Application No. 56-69441, it is known that hydrogen is volatilized from the film surface by thermal diffusion during a later annealing treatment for stabilizing device characteristics. In order to prevent this volatilization, a protective film (for example, an insulating layer such as 5jCh) is provided on the bubble film.

However, as mentioned above, in conventional devices, hydrogen ions are implanted in a crystal orientation with channeling turned off.
Hydrogen ions are at a distance where they can easily diffuse to the surface by annealing. Therefore, even if the surface is covered with a protective film or the like, hydrogen ions are diffused and distributed near the interface between the bubble film and the protective film in a short time due to annealing at about 400C. These hydrogen ions are greatly influenced by the surface condition of the protective film, the state of adhesion between the protective film and the puzzle film at the interface, and the quality of the protective film. As a result, the characteristics of the transfer path vary greatly due to slight variations in the device fabrication process during the formation of the ion implantation transfer path, and the reproducibility is significantly impaired.

[Purpose of the invention]

It is an object of the present invention to provide a hydrogen ion implantation transfer path formation method that overcomes the drawbacks of the above-mentioned known techniques, that is, has high thermal stability and good reproducibility.

[Summary of the invention]

The present invention compares hydrogen ions with a damaged layer (this means one formed by the hydrogen ions themselves and, in some cases, one formed by a second ion) in the well-known hydrogen ion implantation. Using a channeling effect or high-energy implantation, the bubble is distributed at a deep position (region) from the surface of the film. After that, hydrogen ions are thermally diffused toward the film surface using an annealing process, and hydrogen is adsorbed into the damaged layer (strained layer) formed in advance at a desired depth (due to the damage, the bonds in the crystal become vacant, e.g. By trapping hydrogen in dangling bonds, a highly reliable in-plane magnetic layer, that is, an ion implantation transfer path, which is thermally extremely stable compared to conventional elements is formed.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

Figure 1 shows the distribution of ions formed in the film (curve 1) when ion implantation is performed at an implantation angle off from the crystal orientation, which has the well-known channeling effect.
and the distribution (curve 2) of the strained layer (damage layer). As shown in the figure, the damage layer is generally formed by the collision between incident ions and atoms in the film, and the ion distribution position where the ions eventually lose energy and stop is distributed at a shallow position somewhat close to the surface. It is known.

Example 1 Figure 2 shows a case where, as an example of the present invention, hydrogen ions are implanted into a bubble film in a crystal orientation that has a channeling effect, that is, at an implant incident angle that causes channeling. ° Distribution of ions in the membrane (curve 3)
and damage distribution (curve 4). As shown,
In the case of hydrogen ions implanted in a crystal orientation that has a channeling effect, when the ions enter the film and pass through the film, the probability of collision with the constituent atoms in the film is extremely small, so the final The position where the hydrogen ions lose energy and stop, that is, the distribution, is located deeper in the membrane compared to when channeling is turned off. .

Further, in this case, the damage layer is widely distributed with small damage because the ions collide with the constituent atoms little by little with a small collision probability.

Embodiment 2 FIG. 3 is an embodiment for explaining the principle and structure of the present invention. First, as in FIG. 2, hydrogen ions are deeply implanted into the bubble film in a crystal orientation that has a channeling effect. Next, it is known that the desired depth of the surface region of the bubble film is a depth at which the transfer characteristics are good, which is generally about 1/3 of the bubble film thickness. ) with the channeling effect turned off to form a uniformly flat damaged layer (curve 5). In this case, since the second ions are used only to form a damaged layer, the type of ions (eg, H2'', Ne'', etc.) does not matter.

Next, an annealing process is used to thermally diffuse hydrogen toward the film surface. At this time, hydrogen is trapped in the pre-formed damaged layer (vacant bonds in the crystal), resulting in an ion-implanted layer with uniform flat strain and hydrogen simultaneously distributed as shown in the figure (curved line). 6) In other words, an in-plane magnetization layer can be formed due to bubble transfer. Since this ion-implanted layer is formed by hydrogen itself, its in-plane magnetization has a larger value than that of conventional elements, making it suitable as a bubble-driving layer. In addition, the annealing conditions for actually stabilizing the device characteristics are as follows:
It is known that annealing at 350 to 400 C for about 30 minutes is suitable. However, in contrast to such annealing conditions, in the hydrogen ion implantation layer of the present invention, hydrogen is deposited at a deep position immediately after the initial ion implantation. Because of this distribution, compared to the conventional case where hydrogen is distributed near the surface, there is no problem such as hydrogen volatilization from the surface of the Shibapur film, where the diffusion time is longer. In addition, the wide damage layer in the hydrogen ion implantation layer that was initially formed due to channeling is recovered by the above annealing treatment because the degree of damage is small, so it may affect the distribution of the strained layer after the annealing treatment. There isn't.

Conventionally, when ions other than hydrogen are used as the second ions mentioned above, large in-plane magnetization formed by hydrogen and small in-plane magnetization formed by ions other than hydrogen exist in the same strained layer. However, according to the device configuration of the present invention, hydrogen trapped by thermal diffusion becomes a direct carrier of in-plane magnetization over the entire region of the strained layer. Therefore, variations in the magnetic properties of the ion implantation layer are extremely small. Therefore, stable device characteristics can be achieved.

In addition, because hydrogen is distributed throughout the strained layer through heat treatment, the ion implantation transfer path exhibits extremely high thermal stability, and furthermore, it is resistant to process fluctuations in the protective film laminated on the bubble film surface. Shows extremely high margin. That is, it becomes possible to realize an element configuration with extremely high reproducibility and reliability.

Embodiment 3 FIG. 4 is a schematic diagram of an ion-implanted layer illustrating another embodiment using the principles of the present invention.

In this case, the hydrogen ion implantation for constructing the desired large in-plane magnetization is as follows with respect to the above-mentioned second ion implantation:
It doesn't matter before or after that hit. However, it is essential that the hydrogen ions be implanted at a deep position with extremely high energy compared to the depth of the strained layer ultimately required as the bubble driving layer. In this case as well, the magnetic properties of the ion implantation layer shown after the annealing process are similar to those shown in Figure 3, and the thermal stability also shows similar effects, with extremely high reproducibility and reliability. It becomes possible to form an ion implantation transfer path.

〔Effect of the invention〕

According to the present invention, it is possible to form an ion implantation transfer path in which uniform and flat strain and hydrogen ions are simultaneously distributed, which is suitable for puzzle transfer. Therefore, variations in the in-plane magnetization layer that conventionally occur due to the coexistence of hydrogen and other ions in the strained layer are completely eliminated, and extremely stable device characteristics can be achieved.

However, in the present invention, hydrogen is thermally diffused from a deep position in the bubble film to the surface layer by annealing, and is trapped here in a desired strained layer (damage layer) formed in advance. The problem of volatilization from the film surface and variations in device characteristics has been completely resolved. As a result, in addition to establishing stable device characteristics, it has become possible to realize a device configuration with extremely high thermal stability and extremely high reproducibility and reliability.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing the distribution of ions and strain in the ion implantation layer in the depth direction. Figure 2 is a distribution diagram when hydrogen ions are implanted in a crystal orientation that has a channeling effect.
The figure is a schematic diagram of a preliminary ion implantation layer showing the principle and structure of the present invention, and FIG. 4 is a schematic diagram of an ion implantation layer for explaining another embodiment of the invention. 1...Ion distribution, 2...Distortion or damage distribution, 3...Channeling hydrogen ion distribution, 4.
...Strain distribution caused by channeling hydrogen ions, 5
... Second damaged layer, 6... Distribution of hydrogen and strain after annealing treatment, 7... Distribution of hydrogen ions irradiated with high energy, 8... Hydrogen straw irradiated with high energy
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Claims (1)

[Claims] 1. An ion implantation type magnetic bubble memory element in which a mask pattern is formed on a magnetic bubble film capable of holding magnetic bubbles, and then ions are implanted into the magnetic bubble film to form a transfer path, The magnetic bubble element is characterized in that the transfer path is formed by ion implantation in a crystal orientation that has channeling (effect) using hydrogen ions. 2. The magnetic bubble element according to claim 1, wherein after the hydrogen ion implantation, ion implantation is performed in a crystal orientation with channeling turned off to form a damaged layer and constitute a transfer path. . 3. Before or after forming the damaged layer by the ion implantation, hydrogen ions are added to a position deeper than the damaged layer (
2. The magnetic bubble element according to claim 1, wherein the magnetic bubble element is distributed in a region). 4. The magnetic bubble element according to claims 1, 2, and 3, wherein an annealing treatment is performed after the ion implantation.