Microelectronic structures embodying the present invention include a field effect transistor (FET) having highly conductive source/drain extensions. Formation of such highly conductive source/drain extensions includes forming a passivated recess which is back filled by epitaxial deposition of doped material to form the source/drain junctions. The recesses include a laterally extending region that underlies a portion of the gate structure. Such a lateral extension may underlie a sidewall spacer adjacent to the vertical sidewalls of the gate electrode, or may extend further into the channel portion of a FET such that the lateral recess underlies the gate electrode portion of the gate structure. In one embodiment the recess is back filled by an in-situ epitaxial deposition of a bilayer of oppositely doped material. In this way, a very abrupt junction is achieved that provides a relatively low resistance source/drain extension and further provides good off-state subthreshold leakage characteristics. Alternative embodiments can be implemented with a back filled recess of a single conductivity type.

A semiconductor device is provided with: a first conductivity type contact region; a second conductivity type body region; a first conductivity type drift region of; a trench formed through the contact region and body region from a front surface of the semiconductor substrate, wherein a bottom of the trench is positioned in the drift region; an insulating film covering an inner surface of the trench; a gate electrode accommodated in the trench in a state covered with the insulating film; and a second conductivity type floating region formed at a position deeper than the bottom of the trench, and adjacent to the bottom of the trench. The floating region includes a first layer adjacent to the bottom of the trench and a second layer formed at a position deeper than the first layer, wherein a width of the first layer is broader than a width of the second layer.

Some structures and methods to reduce power consumption in devices can be implemented largely by reusing existing bulk CMOS process flows and manufacturing technology, allowing the semiconductor industry as well as the broader electronics industry to avoid a costly and risky switch to alternative technologies. Some of the structures and methods relate to a Deeply Depleted Channel (DDC) design, allowing CMOS based devices to have a reduced V.sub.T compared to conventional bulk CMOS and can allow the threshold voltage V.sub.T of FETs having dopants in the channel region to be set much more precisely. The DDC design also can have a strong body effect compared to conventional bulk CMOS transistors, which can allow for significant dynamic control of power consumption in DDC transistors. Additional structures, configurations, and methods presented herein can be used alone or in conjunction with the DDC to yield additional and different benefits.

A method of forming field effect transistors (FETs) and on Integrated Circuit (IC) chips with the FETs. Channel placeholders at FET locations are undercut at each end of FET channels. Source/drain regions adjacent to each channel placeholder extend into and fill the undercut. The channel placeholder is opened to expose channel surface under each channel placeholder. Source/drain extensions are formed under each channel placeholder, adjacent to each source/drain region. After removing the channel placeholders metal gates are formed over each said FET channel.

A method includes providing a gate structure over a semiconductor substrate and forming a source/drain region associated with the gate structure by etching an opening in the semiconductor substrate, performing a first epitaxial growth process while an entirety of a sidewall of the opening is exposed to grow a first epitaxy material in the opening. The first epitaxial growth process is free of a first dopant impurity. A second epitaxial growth process is performed after first epitaxial growth process to grow a second epitaxy material on the first epitaxy material. The second epitaxy material has the first dopant impurity at a first concentration. Further, a third epitaxial growth process is performed after the second epitaxial growth process that includes introducing the first dopant impurity at a second concentration, the second concentration greater than the first concentration.

Field-Effect Transistor (FET) devices employing an adjacent asymmetric active gate/dummy gate width layout are disclosed. In an exemplary aspect, a FET cell is provided that includes a FET device having an active gate, a source region, and a drain region. The FET cell also includes an isolation structure comprising a dummy gate over a diffusion break located adjacent to one of the source region and the drain region. The FET cell has an asymmetric active gate/dummy gate width layout in that a width of the active gate is larger than a width of the adjacent dummy gate. The increased width of the active gate provides increased gate control and the decreased width of the dummy gate increases isolation from the dummy gate, thus reducing sub-threshold leakage through the dummy gate.

A method for manufacturing a semiconductor device with epitaxial structure includes following steps: A substrate including a plurality of gate structures formed thereon is provided, and a spacer is respectively formed on sidewalls of each gate structure. Next, a first etching process is performed to form a first recess respectively at two sides of the gate structures and followed by performing an ion implantation to the first recesses. After the ion implantation, a second etching process is performed to widen the first recesses to form widened first recesses and to form a second recess respectively at a bottom of each widened first recess. Then, an epitaxial structure is respectively formed in the widened first recesses and the second recesses.

Semiconductor devices including a stressor in a recess and methods of forming the semiconductor devices are provided. The methods may include forming a fast etching region comprising phosphorous in an active region and forming a first trench in the active region by recessing the fast etching region. The methods may also include forming a second trench in the active region by enlarging the first trench using a directional etch process and forming a stressor in the second trench. The second trench may include a notched portion of the active region.

A metal-oxide-semiconductor transistor includes a substrate, a gate insulating layer disposed on the surface of the substrate layer, a metal gate disposed on the gate insulating layer and having at least one plug hole, at least one dielectric plug disposed in the plug hole, and two diffusion regions disposed at two sides of the metal gate in the substrate. The metal gate is configured to operate under an operation voltage greater than 5 v.

Present embodiments provide for a CMOS structure and a fabrication method thereof. While the source-drain epitaxial material formed in each of the PMOS device region and the NMOS device region, deuterium gas is used as the carrier gas to store the deuterium atoms in the interstice of the source-drain epitaxial material as an impurity. Since the source-drain epitaxial material is used as a source-drain, which is quite near the gate, the deuterium atoms can diffuse out from the source-drain epitaxial material during the process of forming the gate dielectric layer and covalently bound to the dangling bonds at the interface between the gate dielectric layer and the substrate, so as to obtain more stable structure, avoid penetration of the carriers, and eliminate hot carrier effects, such that performance and resilience of the device are increased.