Semiconductor device structure and method for forming the same

A semiconductor device structure, comprising:

• a substrate having a base and a fin structure over the base, wherein the fin structure has sidewalls;
• a passivation layer over the sidewalls and the base, wherein the passivation layer comprises dopants, the dopants comprise tin or lead, the dopants and the substrate are made of different materials, and the passivation layer extends from the base onto top portions of the sidewalls;
• an isolation layer over the base and surrounding the fin structure and the passivation layer, wherein a first upper portion of the fin structure and a second upper portion of the passivation layer protrude from the isolation layer;
• and
• a gate electrode over the first upper portion of the fin structure and the second upper portion of the passivation layer, wherein the passivation layer is between the gate electrode and the fin structure, and the second upper portion is between the top portions of the sidewalls and the gate electrode.

A semiconductor device structure, comprising:

• a substrate having a base and a fin structure over the base, wherein the fin structure has a first top surface and sidewalls, and the base has a second top surface;
• a passivation layer covering the sidewalls and the second top surface, wherein the passivation layer comprises dopants, the dopants comprise at least one element selected from group 4A elements, the dopants and the substrate are made of different materials, a first top portion of the passivation layer covers second top portions of the sidewalls, and a third top surface of the passivation layer is partially and directly below the first top surface of the fin structure;
• an isolation layer over the base and surrounding the fin structure and the passivation layer;
• and
• a gate electrode over the fin structure, the passivation layer, and the isolation layer, wherein the first top portion is between the second top portions of the sidewalls and the gate electrode.