Structure and formation method of semiconductor device structure

A semiconductor device structure, comprising:

• a semiconductor substrate;
• a conductive feature over the semiconductor substrate;
• and
• a dielectric layer over the semiconductor substrate and surrounding the conductive feature, wherein the dielectric layer has a first portion and a second portion, the first portion is separated from the conductive feature by a gap, the conductive feature is between the gap and the second portion, and the second portion has a greater dielectric constant than that of the first portion.

A semiconductor device structure, comprising:

• a semiconductor substrate;
• a dielectric layer over the semiconductor substrate;
• and
• a conductive feature in the dielectric layer, wherein a first sidewall of the conductive feature is separated from a first portion of the dielectric layer by a gap, a second sidewall of the conductive feature is in direct contact with a second portion of the dielectric layer, and the second portion has a greater dielectric constant than that of the first portion.