A method of fabricating a semiconductor device includes preparing a substrate including a first region and a second region, sequentially forming a first semiconductor layer and a second semiconductor layer on the first and second regions, patterning the first and second semiconductor layers to form a lower semiconductor pattern and an upper semiconductor pattern on each of the first and second regions, selectively removing the lower semiconductor pattern on the second region to form a gap region, and forming gate electrodes at the first and second regions, respectively.

A transistor device includes a gate structure disposed over a channel region of a semiconductor substrate. A source/drain recess is arranged in the semiconductor substrate alongside the gate structure. A doped silicon-germanium (SiGe) region is disposed within the source/drain recess and has a doping type which is opposite to that of the channel. An un-doped SiGe region is also disposed within the source/drain recess. The un-doped SiGe region underlies the doped SiGe region and comprises different germanium concentrations at different locations within the source/drain recess.

A method provides a substrate having a top surface; forming a first semiconductor layer on the top surface, the first semiconductor layer having a first unit cell geometry; epitaxially depositing a layer of a metal-containing oxide on the first semiconductor layer, the layer of metal-containing oxide having a second unit cell geometry that differs from the first unit cell geometry; ion implanting the first semiconductor layer through the layer of metal-containing oxide; annealing the ion implanted first semiconductor layer; and forming a second semiconductor layer on the layer of metal-containing oxide, the second semiconductor layer having the first unit cell geometry. The layer of metal-containing oxide functions to inhibit propagation of misfit dislocations from the first semiconductor layer into the second semiconductor layer. A structure formed by the method is also disclosed.

A semiconductor structure and a method of fabricating the semiconductor structure are disclosed herein. The semiconductor structure includes a substrate, a strain-inducing layer and an epitaxy structure. The strain-inducing layer is disposed on the substrate, and the epitaxy structure is embedded in the strain-inducing layer and not in contact with the substrate.

A method includes providing a semiconductor substrate having first and second regions that are doped with first and second dopants respectively. The first and second dopants are of opposite types. The method further includes epitaxially growing a first semiconductor layer that is doped with a third dopant. The first and third dopants are of opposite types. The method further includes depositing a dielectric hard mask (HM) layer over the first semiconductor layer; patterning the dielectric HM layer to have an opening over the first region; extending the opening towards the semiconductor substrate; and epitaxially growing a second semiconductor layer in the opening. The second semiconductor layer is doped with a fourth dopant. The first and fourth dopants are of a same type. The method further includes removing the dielectric HM layer; and performing a first CMP process to planarize both the first and second semiconductor layers.

An embodiment of a method for forming a transistor that includes providing a semiconductor substrate having a source/drain region is provided where a first SiGe layer is formed over the source/drain region. A thermal oxidation is performed to convert a top portion of the first SiGe layer to an oxide layer and a bottom portion of the first SiGe layer to a second SiGe layer. A thermal diffusion process is performed after the thermal oxidation is performed to form a SiGe area from the second SiGe layer. The SiGe area has a higher Ge concentration than the first SiGe layer.

A method for fabricating a fin field-effect transistor (FinFET) device includes forming a first dielectric layer over a substrate and then etching the first dielectric layer and the substrate to form a first fin and a second fin. A second dielectric layer is formed along sidewalls of the first fin and the second fin. A protection layer is deposited over the first fin and the second fin. A portion of the protection layer and the first dielectric layer on the second fin is removed and the second fin is then recessed to form a trench. A semiconductor material layer is epitaxially grown in the trench. The protection layer is removed to reveal the first fin and the second fin.

A semiconductor device preferably includes a substrate, a fin-shaped structure on the substrate, a buffer layer on the fin-shaped structure, and an epitaxial layer on the buffer layer. Preferably, the buffer layer is made of silicon germanium and including three or more than three elements. The buffer layer also includes dopants selected from the group consisting of P, As, Sb, Bi, C, and F.

A method for forming a semiconductor device comprises forming a first buffer layer with a first melting point on a substrate. A second buffer layer is formed on the first buffer layer. The second buffer layer has a second melting point that is greater than the first melting point. Annealing process is performed that increases a temperature of the first buffer layer such that the first buffer layer partially liquefies and causes a strain in the second buffer layer to be substantially reduced.

A method for forming a semiconductor device comprises forming a first buffer layer with a first melting point on a substrate. A second buffer layer is formed on the first buffer layer. The second buffer layer has a second melting point that is greater than the first melting point. Annealing process is performed that increases a temperature of the first buffer layer such that the first buffer layer partially liquefies and causes a strain in the second buffer layer to be substantially reduced.