Multilayer structure for reducing film roughness in magnetic devices

A device, comprising:

• a bottom electrode;
• a seed layer stack disposed on and directly contacting the bottom electrode, wherein the seed layer stack includes:
• a smoothing layer structure that includes at least one sub-smoothing layer and at least one amorphous sub-smoothing layer alternately stacked on the bottom electrode, wherein:
• one of the at least one sub-smoothing layer forms a bottom of the smoothing layer structure and is disposed on and directly contacting the bottom electrode;
• one of the at least one an amorphous sub-smoothing layer forms a top of the smoothing layer structure;
• and
• the at least one sub-smoothing layer is made of a first material having a first bond energy and a first weight, the at least one amorphous sub-smoothing layer is made of a second material having a second bond energy and a second weight, the second bond energy is greater than the first bond energy, and the second weight is greater than the first weight, and
• a template layer disposed on and directly contacting the one of at least one amorphous sub-smoothing layer, wherein the template layer is made of a third material, wherein the first material, the second material, and the third material are different;
• a reference layer that includes a synthetic antiparallel (SyAP) stack, wherein the synthetic antiparallel (SyAP) stack includes a first perpendicular magnetic anisotropy (PMA) layer disposed on and directly contacting the template layer of the seed layer stack, an anti-ferromagnetic coupling layer disposed on and directly contacting the first PMA layer, and a second PMA layer disposed on and directly contacting the anti-ferromagnetic coupling layer;
• a tunnel barrier layer disposed on and directly contacting the reference layer;
• a free layer disposed on and directly contacting the tunnel barrier layer;
• and a top electrode disposed over the free layer.

A device, comprising:

• a seed layer stack that includes:
• a buffer layer having a top surface with a first top surface roughness;
• a smoothing layer structure that includes a pair of smoothing layers, wherein the pair of smoothing layers includes:
• a sub-smoothing layer having a first bond energy, and
• an amorphous sub-smoothing layer disposed on and directly contacting the sub-smoothing layer, wherein the amorphous sub-smoothing layer has a second bond energy that is greater than the first bond energy;
• wherein the sub-smoothing layer of the smoothing layer structure is disposed on and directly contacting the buffer layer;
• and
• a template layer disposed on and directly contacting the amorphous sub-smoothing layer of the smoothing layer structure, wherein the template layer has a second top surface roughness that is less than the first top surface roughness.