Magnetoresistive memory device and method of manufacturing magnetoresistive memory device
According to an embodiment, a magnetoresistive memory device includes a layer stack. The layer stack includes a first ferromagnet, an insulator on the first ferromagnet, and a second ferromagnet on the insulator. A nonmagnet is provided above the layer stack. A first conductor is provided on the nonmagnet. A hard mask is provided above the first conductor. The nonmagnet includes a material that is removed at a first etching rate against a first ion beam. The first conductor includes a material that is removed at a second etching rate against the first ion beam. The first etching rate is lower than the second etching rate.
1. A method of manufacturing a magnetoresistive memory device, the method comprising:
forming a first layer stack above a substrate, the first layer stack comprising a first ferromagnet, an insulator above the first ferromagnet, a second ferromagnet above the insulator, a nonmagnet above the second ferromagnet, and a first conductor above the nonmagnet;
forming a hard mask having an opening on the first layer stack;
irradiating, through the opening, the first layer stack with a first ion beam traveling at a first angle with respect to a normal to the substrate, the nonmagnet being etched at a first etching rate by the first ion beam, the first conductor being etched at a second etching rate by the first ion beam, and the first etching rate being lower than the second etching rate; and
irradiating, through the opening, the first layer stack with a second ion beam traveling at a second angle with respect to the normal to the substrate, the second angle being smaller than the first angle.
2. The method according to claim 1 , wherein:
the nonmagnet comprises one boride of tantalum, tungsten, hafnium, iron, cobalt, aluminum, and molybdenum.
3. The method according to claim 1 , wherein:
the nonmagnet comprises one of tantalum, tungsten, hafnium, iron, cobalt, aluminum, and molybdenum.
4. The method according to claim 3 , wherein:
the first conductor comprises one of platinum, tungsten, tantalum, and ruthenium.
5. The method according to claim 3 , wherein:
the first conductor comprises one of platinum, tungsten, tantalum, and ruthenium.