A method includes: providing a layer of porous silicon carbide supported by a silicon carbide substrate; providing a layer of epitaxial silicon carbide on the layer of porous silicon carbide; forming semiconductor devices in the layer of epitaxial silicon carbide; and separating the silicon carbide substrate from the layer of epitaxial silicon carbide at the layer of porous silicon carbide. The layer of porous silicon carbide includes dopants defining a resistivity of the layer of porous silicon carbide. The resistivity of the layer of porous silicon carbide is different from a resistivity of the silicon carbide substrate. Additional methods are described.

A method includes: providing a layer of porous silicon carbide supported by a silicon carbide substrate; providing a layer of epitaxial silicon carbide on the layer of porous silicon carbide; forming semiconductor devices in the layer of epitaxial silicon carbide; and separating the silicon carbide substrate from the layer of epitaxial silicon carbide at the layer of porous silicon carbide. The layer of porous silicon carbide includes dopants that define a resistivity of the layer of porous silicon carbide. The resistivity of the layer of porous silicon carbide is different from a resistivity of the silicon carbide substrate. Additional methods are described.

Semiconductor devices and their manufacturing methods are disclosed herein, and more particularly to semiconductor devices including a transistor having gate all around (GAA) transistor structures and manufacturing methods thereof. Different thickness in an epi-growth scheme is adopted to create different sheet thicknesses within the same device channel regions for use in manufacturing vertically stacked nanostructure (e.g., nanosheet, nanowire, or the like) GAA devices. A GAA device may be formed with a vertical stack of nanostructures in a channel region with a topmost nanostructure of the vertical stack being thicker than the other nanostructures of the vertical stack. Furthermore, an LDD portion of the topmost nanostructure may be formed as the thickest of the nanostructures in the vertical stack.

Semiconductor devices and their manufacturing methods are disclosed herein, and more particularly to semiconductor devices including a transistor having gate all around (GAA) transistor structures and manufacturing methods thereof. Different thickness in an epi-growth scheme is adopted to create different sheet thicknesses within the same device channel regions for use in manufacturing vertically stacked nanostructure (e.g., nanosheet, nanowire, or the like) GAA devices. A GAA device may be formed with a vertical stack of nanostructures in a channel region with a topmost nanostructure of the vertical stack being thicker than the other nanostructures of the vertical stack. Furthermore, an LDD portion of the topmost nanostructure may be formed as the thickest of the nanostructures in the vertical stack.