A method for producing a semiconductor device comprising a plurality of groups consisting of a source, drain and gate contact, wherein the respective types of contact of said groups are interconnected to a common gate, drain and source contact, said method comprising the step of: - providing a first substrate, comprising on its front side a semiconductor layer (2,3), and on top of that layer (2,3), i.e. on the front side of said layer, a plurality of gate contacts, each gate contact lying in between source and drain ohmic contacts, characterized in that the method further comprises the steps of: - providing a second substrate provided with an adhesive layer, - attaching the first substrate to the second, by attaching the front side of said first substrate, including said gate/source/drain, to said adhesive layer of the second substrate, - after the step of attaching the first substrate, removing the first substrate from the semiconductor layer (2,3), to expose the backside of the semiconductor layer (2,3), - after the step of removing the first substrate, etching vias through the backside of said semiconductor layer, wherein vias are produced directly on top of each contact of at least one type, to thereby expose said contacts, - after the step of producing vias, producing on the backside of said semiconductor layer an interconnecting contact layer to provide an interconnect between said source-gate-drain groups to form a common gate, drain and source output contact respectively, this resulting in a semiconductor device on the second substrate, - providing a third substrate (22a,22b) provided with a bonding layer, - attaching the second substrate to the third substrate, by attaching the side of the second substrate, including said semiconductor device, to said bonding layer on the third substrate, - removing the second substrate and the adhesive layer, this resulting in a semiconductor device on the third substrate. - providing a first substrate, comprising on its front side a semiconductor layer (2,3), and on top of that layer (2,3), i.e. on the front side of said layer, a plurality of gate contacts, each gate contact lying in between source and drain ohmic contacts, - providing a second substrate provided with an adhesive layer, - attaching the first substrate to the second, by attaching the front side of said first substrate, including said gate/source/drain, to said adhesive layer of the second substrate, - after the step of attaching the first substrate, removing the first substrate from the semiconductor layer (2,3), to expose the backside of the semiconductor layer (2,3), - after the step of removing the first substrate, etching vias through the backside of said semiconductor layer, wherein vias are produced directly on top of each contact of at least one type, to thereby expose said contacts, - after the step of producing vias, producing on the backside of said semiconductor layer an interconnecting contact layer to provide an interconnect between said source-gate-drain groups to form a common gate, drain and source output contact respectively, this resulting in a semiconductor device on the second substrate, - providing a third substrate (22a,22b) provided with a bonding layer, - attaching the second substrate to the third substrate, by attaching the side of the second substrate, including said semiconductor device, to said bonding layer on the third substrate, - removing the second substrate and the adhesive layer, this resulting in a semiconductor device on the third substrate.