Metal Line Structure and Method

A device comprising:

• a first metal line in a metallization layer over a semiconductor substrate;
• a second metal line in the metallization layer, wherein a first portion of a top surface of the second metal line is level with a top surface of the first metal line;
• a first air gap between the first metal line and the second metal line, wherein at least a portion of the first metal line and at least a portion of the second metal line extend over the first air gap;
• a third metal line in the metallization layer, wherein:
• a top surface of the third metal line is higher than the top surface of the first portion of the second metal line;
• the top surface of the third metal line is level with a top surface of a second portion of the second metal line;
• and
• a bottom surface of the third metal line is level with a bottom surface of the second metal line;
• and
• a second air gap between the second metal line and the third metal line, where at least a portion of the second metal line and at least a portion of the third metal line extend over the second air gap.

A semiconductor device comprising:

• a first conductive line over a substrate, the first conductive line extending in a first direction, the first conductive line comprising a first portion and a second portion, wherein sidewalls and a top surface of the first portion and sidewalls of the second portion are linear in a cross-sectional view, wherein a top surface of the second portion is curved in the cross-sectional view;
• a second conductive line over the substrate, the second conductive line extending in the first direction, wherein sidewalls of the second conductive line are linear in the cross-sectional view and a top surface of the second conductive line is curved in the cross-sectional view;
• and
• a first air gap extending in the first direction between the first conductive line and the second conductive line, wherein at least a portion of the first conductive line and at least a portion of the second conductive line extend over the first air gap.