A method for manufacturing of a waveguide for guiding an electro-magnetic wave, said method comprising: forming a first waveguide layer, a sacrificial layer and a protection layer on a first wafer, the sacrificial layer being formed so as to provide a constant thickness of the sacrificial layer on the entire wafer; patterning the first waveguide layer, the sacrificial layer and the protection layer so as to define a pattern of a first waveguide part in the first waveguide layer, the sacrificial layer and the protection layer to form a lateral spacing between the pattern of the first waveguide part and a supporting structure in the first waveguide layer; selectively removing protection layer material from the pattern of the first waveguide part using a mask and then selectively etching the protection layer on the entire wafer to expose the sacrificial layer on the pattern of the first waveguide part while the protection layer still covers the sacrificial layer on the supporting structure; removing the sacrificial layer on the pattern of the first waveguide part; removing the protection layer; bonding a second wafer on the first wafer, the second wafer comprising a second waveguide part in a second waveguide layer, wherein the first and the second wafers (500, 510) are bonded by bonding the second wafer to the sacrificial layer of the first wafer such that the second waveguide part is supported by the supporting structure and a gap corresponding to the thickness of the sacrificial layer is formed between the first waveguide part and the second waveguide part and the first and second waveguide parts (102, 104) unitely form a single waveguide for guiding the electro-magnetic wave. forming a first waveguide layer, a sacrificial layer and a protection layer on a first wafer, the sacrificial layer being formed so as to provide a constant thickness of the sacrificial layer on the entire wafer; patterning the first waveguide layer, the sacrificial layer and the protection layer so as to define a pattern of a first waveguide part in the first waveguide layer, the sacrificial layer and the protection layer to form a lateral spacing between the pattern of the first waveguide part and a supporting structure in the first waveguide layer; selectively removing protection layer material from the pattern of the first waveguide part using a mask and then selectively etching the protection layer on the entire wafer to expose the sacrificial layer on the pattern of the first waveguide part while the protection layer still covers the sacrificial layer on the supporting structure; removing the sacrificial layer on the pattern of the first waveguide part; removing the protection layer; bonding a second wafer on the first wafer, the second wafer comprising a second waveguide part in a second waveguide layer, wherein the first and the second wafers (500, 510) are bonded by bonding the second wafer to the sacrificial layer of the first wafer such that the second waveguide part is supported by the supporting structure and a gap corresponding to the thickness of the sacrificial layer is formed between the first waveguide part and the second waveguide part and the first and second waveguide parts (102, 104) unitely form a single waveguide for guiding the electro-magnetic wave.