Interconnect structure and manufacturing method for the same

An interconnect structure, comprising:

• a first metal line;
• a second metal line spaced away from the first metal line;
• a conductive contact over the first metal line, wherein at least a portion of the first metal line and at least a portion of the second metal line are under a coverage of a vertical projection area of the conductive contact, the conductive contact comprises:
• a first portion;
• a second portion over the first portion, wherein a bottom width of the second portion is greater than a top width of the first portion;
• and
• a third portion over the second portion, wherein a bottom width of the third portion is greater than a top width of the second portion, the entire first portion and the entire second portion are under a coverage of a vertical projection area of the third portion;
• a first layer, wherein a first portion of the first layer is under a coverage of a vertical projection area of the first portion of the conductive contact;
• a second layer over the first layer, wherein a portion of the second layer sandwiched between a bottom of the second portion of the conductive contact and the first layer has a uniformed thickness;
• a dielectric layer over atop surf ace of the second layer, and comprises a first portion under a coverage of a vertical projection area of the third portion of the conductive contact;
• and
• a seed layer, conformally formed on the first metal line, the first layer, the second layer and the dielectric layer, wherein the third portion of the conductive contact is in direct contact with a horizontal portion of the seed layer, and the seed layer is in direct contact with the portion of the second layer having the uniformed thickness profile.

An interconnect structure, comprising:

• a first metal line;
• a second metal line spaced away from the first metal line along a first direction;
• a conductive contact over the first metal line, comprising:
• a first portion;
• a second portion over the first portion, wherein a bottom width of the second portion is greater than a top width of the first portion;
• and
• a third portion over the second portion, wherein a bottom width of the third portion is greater than a top width of the second portion, the entire first portion and the entire second portion are under a coverage of a vertical projection area of the third portion;
• a first layer, wherein a first portion of the first layer is under a coverage of a vertical projection area of the first portion of the conductive contact;
• a second layer over the first layer, wherein
• a first portion of the second layer is under a coverage of a vertical projection area of the first portion of the conductive contact,
• a portion of the first layer is free from being covered by the second layer,
• wherein the second layer has a second portion between a bottom of the second portion of the conductive contact and the first layer, the second portion of the second layer having a uniform thickness,
• the entire second layer is below the bottom of the second portion of the conductive contact;
• and
• a dielectric layer over a top surface of the second layer, and the dielectric layer comprises:
• a first portion under a coverage of a vertical projection area of the third portion of the conductive contact;
• and
• a second portion at least laterally surrounding the third portion of the conductive contact, wherein:
• the first portion of the dielectric layer extends along the first direction and in direct contact with the second portion of the dielectric layer;
• and
• a seed layer, conformally formed on the first metal line, the first layer, the second layer and the dielectric layer, wherein the third portion of the conductive contact is in direct contact with a horizontal portion of the seed layer, and the seed layer extends horizontally over a top surface of the second layer.