each of the upper and lower insulating layers 320 and 310 is relatively thick to allow for later formation of a groove and a via hole therein hereinafter a contact hole is also referred to as a u201c via hole u201d and may be formed for example of organic polymer having a low k dielectric constant alternatively each of the upper and lower insulating layers 320 and 310 may be made of fluorine doped oxide or carbon doped oxide or silicon oxide the organic polymer having a low k dielectric constant includes for example polyallylether group resin polypentafluorostylene polytetrafluorostylene group resin annular fluorine resin siloxane copolymer polyallylether fluoride group resin polypentafluorostylene polytetrafluorostylene group resin polyimide fluoride resin polynaphthalene fluoride and polycide resin the organic polymer having a low k dielectric constant may be formed for example by means of plasma enhanced chemical vapor deposition pecvd high density plasma chemical vapor deposition hdpcvd atmospheric pressure chemical vapor deposition apcvd spin coating and so forth each of the top and bottom hard mask layers 330 and 325 may be formed of a material selected from the group consisting of silicon oxide silicon nitride silicon carbide sic polysilicon metal oxide and metal preferably the etch selectivity of the top.