Magnetic memory device and method of manufacturing the same

1. A method of manufacturing a magnetic memory device, comprising:

forming an insulation layer on a substrate;

forming a lower electrode on the insulation layer;

forming a magneto-resistive film on an upper surface of the lower electrode, the magneto-resistive film including an insulation barrier layer and a plurality of magnetic films stacked on both sides of the insulation barrier layer;

stacking a mask layer on the magneto-resistive film; and

performing ion etching on the magneto-resistive film, using the mask layer as a mask, thereby forming a magneto-resistive element, such that a center of distribution of sputter substance dispersed by an ion beam is located away from a side surface of the magneto-resistive element,

wherein at the time of the ion etching, a taper is formed on the side surface of the magneto-resistive element such that an angle of the side surface of the magneto-resistive element to a bottom surface of the magneto-resistive element is about 60° or less.

2. A method of manufacturing a magnetic memory device, comprising:

forming an insulation layer on a substrate;

forming a lower electrode on the insulation layer;

forming a magneto-resistive film on an upper surface of the lower electrode, the magneto-resistive film including an insulation barrier layer and a plurality of magnetic films stacked on both sides of the insulation barrier layer;

stacking a mask layer on the magneto-resistive film; and

performing ion etching on the magneto-resistive film, using the mask layer as a mask, thereby forming a magneto-resistive element, such that a center of distribution of sputter substance dispersed by an ion beam is located away from a side surface of the magneto-resistive element,

wherein an incidence angle θ of the ion beam is set to satisfy the equation,

θ=θ t−θm

where θm is the ion beam incidence angle at which a maximum sputtering efficiency of the mask is obtained,

θt is the taper angle of a side surface of the mask, and

θ is the incidence angle of the ion beam to a normal line of the substrate.

3. The method of manufacturing a magnetic memory device, according to claim 1 , wherein an incidence angle θ of the ion beam is set to satisfy the equation,

θ=θ t−θm

where θm is the ion beam incidence angle at which a maximum sputtering efficiency of the mask is obtained,

θt is the taper angle of a side surface of the mask, and

θ is the incidence angle of the ion beam to a normal line of the substrate.

4. The method of manufacturing a magnetic memory device, according to claim 1 , wherein the magneto-resistive element is formed in a self-alignment manner, relative to the mask.

5. The method of manufacturing a magnetic memory device, according to claim 1 , further comprising a cleaning step of cleaning the side surface of the magneto-resistive element, after forming the magneto-resistive element by performing the ion etching on the magneto-resistive film.

6. The method of manufacturing a magnetic memory device, according to claim 5 , wherein the cleaning step includes a step of applying an ion beam to the side surface of the magneto-resistive element.

7. The method of manufacturing a magnetic memory device, according to claim 1 , wherein the ion etching uses argon ions.

8. The method of manufacturing a magnetic memory device, according to claim 1 , wherein the ion etching is effected by RIE.

9. The method of manufacturing a magnetic memory device, according to claim 1 , wherein a positional relationship between an ion source for the ion etching and the substrate is varied such that all side surfaces of the magneto-resistive element are directed to the ion source.

10. A method of manufacturing a magnetic memory device, comprising:

forming an insulation layer on a substrate;

forming a lower electrode on the insulation layer;

forming a magneto-resistive film on an upper surface of the lower electrode, the magneto-resistive film including an insulation barrier layer and a plurality of magnetic films stacked on both sides of the insulation barrier layer;

stacking a mask layer on the magneto-resistive film;

performing ion etching on the magneto-resistive film, using the mask layer as a mask, thereby forming a magneto-resistive element;

forming an insulation film on upper surfaces of the mask, the magneto-resistive element and the lower electrode; and

etching the insulation film with an ion beam such that a side surface of the magneto-resistive element is exposed.

11. A method of manufacturing a magnetic memory device, comprising:

forming an insulation layer on a substrate;

forming a lower electrode on the insulation layer;

forming a magneto-resistive film on an upper surface of the lower electrode, the magneto-resistive film including an insulation barrier layer and a plurality of magnetic films stacked on both sides of the insulation barrier layer;

stacking a mask layer on the magneto-resistive film;

performing ion etching on the magneto-resistive film, using the mask layer as a mask, thereby forming a magneto-resistive element, and also over-etching an upper part of the lower electrode, thereby forming a recess at the upper part of the lower electrode;

forming an insulation film on upper surfaces of the mask, the magneto-resistive element and the lower electrode including the recess; and

etching the insulation film with an ion beam such that a side surface of the magneto-resistive element is exposed and the insulation film remains on the lower electrode.

12. The method of manufacturing a magnetic memory device, according to claim 11 , wherein the insulation film is formed of a material that is more easily oxidizable than the lower electrode.

13. The method of manufacturing a magnetic memory device, according to claim 11 , wherein the insulation film is formed of an oxygen-free material.

14. The method of manufacturing a magnetic memory device, according to claim 10 , wherein when the magneto-resistive element is formed, an etched substance, which is dispersed and attached at the time of the ion beam etching, is removed from the side surface of the magneto-resistive element by the ion beam.

15. The method of manufacturing a magnetic memory device, according to claim 11 , wherein when the magneto-resistive element is formed, an etched substance, which is dispersed and attached at the time of the ion beam etching, is removed from the side surface of the magneto-resistive element by the ion beam.

16. The method of manufacturing a magnetic memory device, according to claim 10 , wherein the following equation is satisfied:

t=d *( ER (θ mtj −θ)− ER (θ)) /( ER (θ mtj −θ)* ER (θ))

where θmtj is a taper angle of the side surface of the magneto-resistive element,

ER (θmtj) is an etching rate of the magneto-resistive element as a function of θmtj,

ER(θ) is an etching rate of the insulation film formed on the magneto-resistive element as a function of an incidence angle θ of an ion beam at the time of etching,

d is the thickness of the insulation film, and

t is a time at which only the side surface of the magneto-resistive element is exposed by the ion etching.

17. The method of manufacturing a magnetic memory device, according to claim 11 , wherein the following equation is satisfied:

t=d *( ER (θ mtj −θ)− ER (θ)) /( ER (θ mtj −θ)* ER (θ))

where θmtj is a taper angle of the side surface of the magneto-resistive element,

ER(θmtj) is an etching rate of the magneto-resistive element as a function of θmtj,

ER(θ) is an etching rate of the insulation film formed on the magneto-resistive element as a function of an incidence angle θ of an ion beam at the time of etching,

d is the thickness of the insulation film, and

t is a time at which only the side surface of the magneto-resistive element is exposed by the ion etching.

18. The method of manufacturing a magnetic memory device, according to claim 10 , wherein a taper is formed on at least the side surface of the magneto-resistive element with respect to a bottom surface of the magneto-resistive element and an incident angle of the ion beam is normal to a bottom surface of the magneto-resistive element.

19. The method of manufacturing a magneto memory device, according to claim 18 , wherein the side surface of the magneto-resistive element to the bottom surface thereof is about 60° or less.