Method of fabricating a device with a concentration gradient and the corresponding device

A method comprising:

• forming a trench in a layer of a first material;
• filling the trench with an alloy material comprising a combination of the first material and a second material, the second material being present in the alloy material with a heavier concentration than the first material;
• performing heat drive-in to stimulate lateral diffusion of the second material from the alloy material filling the trench and into the first material in the layer within which the trench is formed so as to form a non-uniform composition in a direction substantially perpendicular to a depth of the trench;
• and
• etching a top surface of the deposited layers which fill the trench.

A method for fabricating a semiconductive device with a concentration gradient, the method comprising:

• forming a cavity in a protective layer and a silicon layer above an etch stop layer and a substrate of the semiconductive device;
• filling of the cavity with an alloy;
• and
• performing a drive-in diffusion to form, in a portion of the silicon layer adjacent to the cavity, a gradient of a material from the alloy extending in a direction substantially perpendicular to the thickness of the semiconductive device.

A semiconductive device comprising:

• a substrate;
• an insulating etch stop layer over the substrate;
• a silicon layer over the insulating etch stop layer, wherein the silicon layer has a cavity filled with an alloy;
• a first region of the alloy and a second region in the silicon layer laterally adjacent to the first region;
• and
• wherein the second region includes a gradient of material driven from the alloy in the cavity to diffuse into the second region extending in a direction substantially perpendicular to the thickness of the semiconductive device.