The present invention provides a low-profile and light-weight
semiconductor device having improved product reliability and higher
frequency performance. A multi-layer interconnect line structure is
disposed just under circuit devices 410a and 410b. An Interlayer
insulating film 405 that composes a part of the multi-layer interconnect
line structure is formed of a material having a relative dielectric
constant within a range from 1.0 to 3.7, and a dielectric loss tangent
within a range from 0.0001 to 0.02.