A semiconductor device including a magnetic tunnel junction (MTJ) stack, where a cross section of a bottom electrode of the stack includes a hexagonal profile. A semiconductor device including a lower word line, a magnetic tunnel junction (MTJ) stack, where a cross section of a first electrode of the MTJ stack comprises a hexagonal profile. A method including forming a bottom electrode, the bottom electrode includes a side surface including a width at a middle section of the bottom electrode greater than a width at a lower surface of the bottom electrode, and the width at the middle section of the bottom electrode greater than a width at an upper surface of the bottom electrode.

A method of fabricating a nitrogen-vacancy (NV) center quantum sensing device based on electrohydrodynamic (EHD) printing. A nanopipette with an aperture at one end is filled with nanodiamond suspension ink so the ink is present in a meniscus at The aperture, the nanodiamond suspension ink comprises nanodiamonds and solvent. The nanopipette is supported above a substrate having a back electrode. A DC is applied pulse between the nanopipette and the back electrode so as to generate an electrostatic attractive force resulting in the ejection of nano-diamond-laden droplets with sub-attoliter volume. The droplet lands on the substrate and is allowed to dry due to solvent evaporation. Using the method, the control of the number of printed nano-diamonds is at will, attaining single-particle level precision. This printing approach, therefore, enables printing NV center arrays with a controlled number directly on the substrate without any lithographic process.

A method of fabricating a nitrogen-vacancy (NV) center quantum sensing device based on electrohydrodynamic (EHD) printing. A nanopipette with an aperture at one end is filled with nanodiamond suspension ink so the ink is present in a meniscus at The aperture, the nanodiamond suspension ink comprises nanodiamonds and solvent. The nanopipette is supported above a substrate having a back electrode. A DC is applied pulse between the nanopipette and the back electrode so as to generate an electrostatic attractive force resulting in the ejection of nano-diamond-laden droplets with sub-attoliter volume. The droplet lands on the substrate and is allowed to dry due to solvent evaporation. Using the method, the control of the number of printed nano-diamonds is at will, attaining single-particle level precision. This printing approach, therefore, enables printing NV center arrays with a controlled number directly on the substrate without any lithographic process.

A method for fabricating an MRAM device is disclosed. The method includes: depositing a first dielectric layer and a second dielectric layer over a semiconductor substrate; depositing a bottom electrode layer over the second dielectric layer, and forming an MTJ stack and a hard mask layer over the bottom electrode layer; patterning the hard mask layer and forming at least one MTJ pillar by etching the MTJ stack with the patterned hard mask layer serving as a mask; depositing a first ILD layer over a top surface of the hard mask layer and on sidewalls of the hard mask layer and MTJ pillar; performing a first etch-back process on the first ILD layer, such that a surface of the first ILD layer on each side of the hard mask layer and the MTJ pillar forms a slope of 40-70 with respect to a surface of the semiconductor substrate.

A method for fabricating an MRAM device is disclosed. The method includes: depositing a first dielectric layer and a second dielectric layer over a semiconductor substrate; depositing a bottom electrode layer over the second dielectric layer, and forming an MTJ stack and a hard mask layer over the bottom electrode layer; patterning the hard mask layer and forming at least one MTJ pillar by etching the MTJ stack with the patterned hard mask layer serving as a mask; depositing a first ILD layer over a top surface of the hard mask layer and on sidewalls of the hard mask layer and MTJ pillar; performing a first etch-back process on the first ILD layer, such that a surface of the first ILD layer on each side of the hard mask layer and the MTJ pillar forms a slope of 40-70 with respect to a surface of the semiconductor substrate.

A memory device comprising a reference magnetic pattern and a free magnetic pattern sequentially stacked on a substrate; and a tunnel barrier pattern between the reference magnetic pattern and the free magnetic pattern, wherein the reference magnetic pattern includes: a first pinning pattern; a second pinning pattern between the first pinning pattern and the tunnel barrier pattern; and an exchange coupling pattern between the first pinning pattern and the second pinning pattern, the exchange coupling pattern antiferromagnetically coupling the first pinning pattern and the second pinning pattern, wherein the first pinning pattern includes: a first magnetic pattern; and a second magnetic pattern between the first magnetic pattern and the exchange coupling pattern, the first magnetic pattern is a single layer including an alloy of a first ferromagnetic element and a first non-magnetic metal element, and wherein the second magnetic pattern is a single layer including a second ferromagnetic element.

A memory device comprising a reference magnetic pattern and a free magnetic pattern sequentially stacked on a substrate; and a tunnel barrier pattern between the reference magnetic pattern and the free magnetic pattern, wherein the reference magnetic pattern includes: a first pinning pattern; a second pinning pattern between the first pinning pattern and the tunnel barrier pattern; and an exchange coupling pattern between the first pinning pattern and the second pinning pattern, the exchange coupling pattern antiferromagnetically coupling the first pinning pattern and the second pinning pattern, wherein the first pinning pattern includes: a first magnetic pattern; and a second magnetic pattern between the first magnetic pattern and the exchange coupling pattern, the first magnetic pattern is a single layer including an alloy of a first ferromagnetic element and a first non-magnetic metal element, and wherein the second magnetic pattern is a single layer including a second ferromagnetic element.

In an embodiment, a semiconductor device includes a spin orbit torque (SOT) line extending in a first direction; an electrode layer spaced apart from the SOT line in a third direction; and a magnetic tunnel junction structure interposed between the SOT line and the electrode layer, and including a free layer adjacent to the SOT line in the third direction, a pinned layer adjacent to the electrode layer in the third direction, and a tunnel barrier layer interposed between the free layer and the pinned layer, wherein the magnetic tunnel junction structure includes a first portion overlapping the SOT line and a second portion not overlapping the SOT line in a second direction, the electrode layer overlaps at least a portion of the second portion, and a thickness of the free layer in the first portion is greater than a thickness of the free layer in the second portion.

In an embodiment, a semiconductor device includes a spin orbit torque (SOT) line extending in a first direction; an electrode layer spaced apart from the SOT line in a third direction; and a magnetic tunnel junction structure interposed between the SOT line and the electrode layer, and including a free layer adjacent to the SOT line in the third direction, a pinned layer adjacent to the electrode layer in the third direction, and a tunnel barrier layer interposed between the free layer and the pinned layer, wherein the magnetic tunnel junction structure includes a first portion overlapping the SOT line and a second portion not overlapping the SOT line in a second direction, the electrode layer overlaps at least a portion of the second portion, and a thickness of the free layer in the first portion is greater than a thickness of the free layer in the second portion.

A method of controlling a trajectory of a perpendicular magnetization switching of a ferromagnetic layer using spin-orbit torques in the absence of any external magnetic field includes: injecting a charge current J.sub.e through a heavy-metal thin film disposed adjacent to a ferromagnetic layer to produce spin torques which drive a magnetization M out of an equilibrium state towards an in-plane of a nanomagnet; turning the charge current J.sub.e off after t.sub.e seconds, where an effective field experienced by the magnetization of the ferromagnetic layer H.sub.eff is significantly dominated by and in-plane anisotropy H.sub.kx, and where M passes a hard axis by precessing around the H.sub.eff; and passing the hard axis, where H.sub.eff is dominated by a perpendicular-to-the-plane anisotropy H.sub.kz, and where M is pulled towards the new equilibrium state by precessing and damping around H.sub.eff, completing a magnetization switching.