A semiconductor device manufacturing method includes forming a first film containing a first device on a first substrate, forming a second film containing a semiconductor layer on a second substrate, and changing the semiconductor layer into a porous layer. The method further includes forming a third film containing a second device on the second film, and bonding the first substrate and the second substrate to sandwich the first film, the third film, and the second film therebetween. The method further includes separating the first substrate and the second substrate from each other at a position of the second film.

A semiconductor substrate comprising a first epitaxial silicon carbide layer and a second silicon carbide epitaxial layer. At least one semiconductor device is formed in or on the second silicon carbide epitaxial layer. The semiconductor substrate is formed overlying a silicon carbide substrate having a surface comprising silicon carbide and carbon. An exfoliation process is used to remove the semiconductor substrate from the silicon carbide substrate. The carbon on the surface of the silicon carbide substrate supports separation. A portion of the silicon carbide substrate on the semiconductor substrate is removed after the exfoliation process. The surface of the silicon carbide substrate is prepared for reuse in subsequent formation of semiconductor substrates.

An epitaxial silicon carbide substrate comprises a first epitaxial silicon carbide layer and at least a second silicon carbide epitaxial layer. A plurality of devices are formed in or overlying the second silicon carbide epitaxial layer. The epitaxial silicon carbide substrate is formed overlying a reuseable silicon carbide substrate. An exfoliation layer is at or underlies a surface of the reuseable silicon carbide substrate. The exfoliation layer comprises silicon carbide and carbon. In one embodiment a plurality of trenches is formed in the surface of the reuseable silicon carbide substrate. The layer of carbon is formed in or below the plurality of trenches. An exfoliation process comprises thermal or mechanical processes to separate the reuseable silicon carbide substrate from the epitaxial silicon carbide substrate. The surface of the reuseable silicon carbide substrate is prepared so the reuseable silicon carbide substrate can be reused.

A semiconductor structure is provided. The semiconductor structure includes a lead frame and a sub-substrate disposed on the lead frame, wherein the thickness of the sub-substrate is between 0 and 0.5 m. The semiconductor structure also includes an epitaxial layer disposed on the sub-substrate. The epitaxial layer includes a buffer layer, a channel layer and a barrier layer. The buffer layer is disposed between the sub-substrate and the channel layer. The channel layer is disposed between the buffer layer and the barrier layer. The semiconductor structure further includes a device layer disposed on the barrier layer and an interconnector structure electrically connected to the epitaxial layer and/or the device layer by a through hole.

A lift-off method includes joining a transfer substrate to a face side of an optical device layer of an optical device wafer with a joining member interposed therebetween, thereby making up a composite substrate, applying a pulsed laser beam having a wavelength transmittable through the epitaxy substrate and absorbable by a buffer layer, from a reverse side of the epitaxy substrate of the optical device wafer, thereby breaking the buffer layer, and an optical device layer transferring step of peeling off the epitaxy substrate from the optical device layer and transferring the optical device layer to the transfer substrate. The optical device layer transferring step includes the step of applying a bending moment to an area of the composite substrate that includes an outer peripheral portion thereof while holding an area of the composite substrate that includes a central portion thereof.