Embodiments described herein related generally to a semiconductor device and a manufacturing method thereof.
Generally, a semiconductor device adopts a multilayer wiring structure in which wirings and vias are provided in an interlayer insulating film. A bonding metal pad is formed on the upper surface side of the uppermost wiring layer of the multilayer wiring structure, and wire is bonded in an opening window formed in a passivation film of the upper layer.
Recently, in order to solve problems such as signal delay and an increase in power consumption due to an increase in the amount of an inter-wiring capacitance following miniaturization of semiconductor devices, a low-permittivity film (hereinafter “low-k film”) having the relative permittivity equal to or less than 2.5 is used as an interlayer insulating film. Various studies have been made to use an organic polymer material or a porous material as this low-k film to further decrease the permittivity.
However, such a low-k film has a low mechanical strength, and therefore deformation or cracking occurs due to the load upon wire bonding. Therefore, the low-k film absorbs moisture, and there is a problem in that barrier metal film of wirings, vias and the like is oxidized and the reliability of semiconductor devices decreases. Hence, various methods are adopted of preventing deformation or cracking of the low-k film by reinforcing the lower layer of a metal pad.