A device includes integrated circuit chips mounted on one another. At least one component for protecting elements of a first one of the chips is formed in a second one of the chips. Preferably, the chips are of SOI type, the second chip includes an SOI layer having a first thickness sufficient to support the component for protecting elements. The first chip also includes an SOI layer but having a second thickness smaller than the first thickness that is insufficient to support the component for protecting elements. The SOI layer of the second chip may be an optical waveguide layer.