A method includes providing a first semiconductor layer at a frontside of a structure; implanting first dopants of a first conductivity-type into the first semiconductor layer, resulting in a doped layer in the first semiconductor layer; forming a stack of semiconductor layers over the first semiconductor layer; patterning the stack of semiconductor layers and the first semiconductor layer into fins; forming an isolation structure adjacent to a lower portion of the fins; etching the stack of semiconductor layers to form a source/drain trench over the first semiconductor layer; forming a source/drain feature in the source/drain trench, wherein the source/drain feature is doped with second dopants of a second conductivity-type opposite to the first conductivity-type; forming a contact hole at a backside of the structure, wherein the contact hole exposes the doped layer in the first semiconductor layer; and forming a first contact structure in the contact hole.

A method for fabricating p-type field effect transistor (FET) includes the steps of first providing a substrate, forming a pad layer on the substrate, forming a well in the substrate, performing an ion implantation process to implant germanium ions into the substrate to form a channel region, and then conducting an anneal process to divide the channel region into a top portion and a bottom portion. After removing the pad layer, a gate structure is formed on the substrate and a lightly doped drain (LDD) is formed adjacent to two sides of the gate structure.

A semiconductor structure and a method for forming a semiconductor structure are provided. In some embodiments, a method is provided. The method includes following operations. A sacrificial gate structure is formed over a fin structure. The sacrificial gate structure includes a sacrificial gate layer and a sacrificial dielectric layer. The sacrificial gate layer is removed to form a gate trench exposing the sacrificial dielectric layer. A doped region is formed in the fi structure covered by the sacrificial dielectric layer. The sacrificial dielectric layer, a portion of the doped region and a portion of the fin structure are removed from the gate trench. An interfacial layer is formed over the fin structure in the gate trench.

A method of forming a semiconductor device structure is provided. The method includes forming an insulating layer over a semiconductor substrate including a conductive feature, forming an insulating layer with a trench over the semiconductor substrate to expose the conductive feature, and forming a sacrificial liner layer over two opposite sidewalls and a bottom of the trench. Ions are implanted into the conductive feature covered by the sacrificial liner layer, so that a doping region is formed in the conductive feature and has two opposite side edges respectively separated from the two opposite sidewalls of the trench. The sacrificial liner layer is removed after forming the doping region, and a conductive connecting structure is formed in the trench. The two opposite sidewalls of the conductive connecting structure are respectively separated from the two corresponding opposite sidewalls of the trench by an air spacer.

A method includes forming an ion-implanted capping layer in a first epitaxial layer disposed on a silicon substrate. The ion-implanted capping layer is doped with a second dopant of a same conductivity type as a first dopant in the silicon substrate. The second dopant has a lower diffusivity than the diffusivity of the first dopant. The ion-implanted capping layer has a thickness configured to contain up-diffusion of the first dopant from the silicon wafer in the first epitaxial layer in thermal processes for fabricating a vertical MOSFET device in the substrate. The ion-implanted capping layer is configured to limit up-diffusion of the first dopant from the silicon wafer through the ion-implanted capping layer into a second epitaxial layer such that a concentration of the first dopant in the second epitaxial layer is lower than a concentration of the first dopant in the first epitaxial layer.

The invention provides a semiconductor structure, the semiconductor structure includes a substrate, two shallow trench isolation structures are located in the substrate, a first region, a second region and a third region are defined between the two shallow trench isolation structures, the second region is located between the first region and the third region. Two thick oxide layers are respectively located in the first region and the third region and directly contact the two shallow trench isolation structures respectively, and a thin oxide layer is located in the second region, the thickness of the thick oxide layer in the first region is greater than that of the thin oxide layer in the second region.

A method of forming a semiconductor device structure is provided. The method includes forming an insulating layer over a semiconductor substrate including a conductive feature, forming an insulating layer with a trench over the semiconductor substrate to expose the conductive feature, and forming a sacrificial liner layer over two opposite sidewalls and a bottom of the trench. Ions are implanted into the conductive feature covered by the sacrificial liner layer, so that a doping region is formed in the conductive feature and has two opposite side edges respectively separated from the two opposite sidewalls of the trench. The sacrificial liner layer is removed after forming the doping region, and a conductive connecting structure is formed in the trench. The two opposite sidewalls of the conductive connecting structure are respectively separated from the two corresponding opposite sidewalls of the trench by an air spacer.

In an SOI substrate having a semiconductor substrate serving as a support substrate, an insulating layer on the semiconductor substrate and a semiconductor layer on the insulating layer, an element isolation region which penetrates the semiconductor layer and the insulating layer and whose bottom part reaches the semiconductor substrate is formed, and a gate electrode is formed on the semiconductor layer via a gate insulating film. A divot is formed in the element isolation region at a position adjacent to the semiconductor layer, and a buried insulating film is formed in the divot. The gate electrode includes a part formed on the semiconductor layer via the gate insulating film, a part located on the buried insulating film and a part located on the element isolation region.

A gate electrode is formed in a trench reaching a drain region so as to leave a concave portion on the top of the trench. A first insulating film is formed, which fills the concave portion and of which the thickness increases as the distance from an end of the trench increases on the substrate surface on both sides of the trench. First and second source regions are formed in a self-alignment manner by introduction of impurities through the first insulating film.

A method of forming a semiconductor arrangement includes forming a gate dielectric layer over a semiconductor layer. A gate electrode layer is formed over the gate dielectric layer. A first gate mask is formed over the gate electrode layer. The gate electrode layer is etched using the first gate mask as an etch template to form a first gate electrode. A first dopant is implanted into the semiconductor layer using the first gate mask and the first gate electrode as an implantation template to form a first doped region in the semiconductor layer.