NOVELTY - Forming a layer transfer structure (101) involves processing a carrier substrate (100) to create a porous region (120) with a tuned porosity in combination with an implanted species defining a separation plane in the substrate.    USE - For forming a layer transfer structure useful for forming a three dimensional integrated structure (claimed), e.g. silicon on insulator wafer, semiconductor device such as thin-film crystalline solar cells.    ADVANTAGE - The method allows a controlled way to achieve layer transfer by defining a separation plane in the porous region through implantation of dopant and/or non-dopant ion into silicon-containing substrate. The method provides various porosities, the anodization process does not have to be altered, i.e., the whole anodization process is performed at the same conditions (one anodization step). The method is well controlled tunability of the process that is accomplished by varying the amount, i.e., dose and the position, i.e., depth of the implanted ions, providing needed stability of this bi-layer during further decal processing, but at the same time, enabling easy separation when release process is required. This well controlled tunability is essential to enable the structure to withstand the various processing steps required for the formation of the device, interconnect and packaging structures in the decal layer while it is still supported on the carrier substrate. The method creates the optimum porous region having a porous bi-layer with graded porosity, and is strong enough to withstand various complementary metal oxide semiconductor-related processing steps, and at the same time, weak enough to allow easy separation of decal from carrier substrate semiconductor components fabricated in the transfer layer. By using the porous silicon based carrier, an epitaxial silicon layer is easily grown on the top of porous layer. The method allows formation of high quality of epitaxial layer, allowing high performance applications. The method provides an effective supporting structure for an integrated three dimensional integrated circuit for high frequency and high speed computing applications. The porous-silicon based transfer technology can be utilized to form a complete, high-density interconnect structure with integrated functional components. Thus, the process cost effectively produces the three dimensional structure.    DETAILED DESCRIPTION - Forming a layer transfer structure (101), involves providing a carrier substrate (100); and processing the carrier substrate to create a porous legion with a tuned porosity in combination with an implanted species defining a separation plane in the substrate. The processing step further comprises implanting a first species comprising boron; and implanting a second different species. The porous region is implanted with a gas comprising hydrogen gas. The regrown epitaxial layer is processed to form a device layer having a specific resistivity using dopants containing ambient during the regrowth process. The regrown epitaxial layer is processed to form a device layer having a specific resistivity by ion implantation. The regrown epitaxial layer is used in the creation of n-metal oxide semiconductor (nMOS) or pMOS devices on different layers. An INDEPENDENT CLAIM is included for forming a three dimensional integrated structure, involving bonding a decal structure comprising a transfer layer on a carrier substrate substrate having a porous region (120) with a tuned porosity in combination with an implanted species defining a separation plane, to a receiver structure; and separating the transfer layer from the substrate at the separation plane in the porous region.    DESCRIPTION OF DRAWING(S) - The figure shows a technique for forming a decal layer containing semiconducting components having a release layer.    carrier substrate (100)    transfer layer (101)    base-substrate (102)    semiconductor component layer (103)    porous region (120)    interface of layers. (121, 122)