Structure and formation method of semiconductor device structure with nanowires

A semiconductor device structure, comprising:

• a substrate having a first fin portion in an input-output region and a second fin portion in a core region;
• a first nanowire over the first fin portion in the input-output region;
• a second nanowire over the second fin portion in the core region;
• a dielectric layer surrounding the first nanowire;
• a first gate structure surrounding the dielectric layer and the first nanowire;
• a first source/drain portion adjacent to the first gate structure;
• a second gate structure surrounding the second nanowire;
• and
• a second source/drain portion adjacent to the second gate structure.

A semiconductor device structure, comprising:

• a substrate having a fin portion in an input-output region;
• a nanowire over the fin portion in the input-output region;
• a gate structure surrounding the nanowire and having opposite sides;
• two spacer elements adjacent to the opposite sides of the gate structure;
• a dielectric layer between the spacer elements and the gate structure;
• and
• two source/drain portions adjacent to the two spacer elements respectively.