Disclosed herein are methods for forming MOSFETs. In some embodiments, a method may include providing a device structure including a plurality of trenches, and forming a mask over the device structure including within each of the plurality of trenches and over a top surface of the device structure. The method may further include removing the mask from within the trenches, wherein the mask remains along the top surface of the device structure, and implanting the device structure to form a treated layer along a bottom of the trenches. In some embodiments, the method may further include forming a gate oxide layer along a sidewall of each of the trenches and along the bottom of the trenches, wherein a thickness of the oxide along the bottom of the trenches is greater than a thickness of the oxide along the sidewall of each of the trenches.

A method for fabricating a semiconductor device includes forming a fin extending along a first direction on a semiconductor substrate and forming a sacrificial gate electrode structure extending along a second direction substantially perpendicular to the first direction over the fin. The sacrificial gate electrode structure comprises a sacrificial gate dielectric layer and a sacrificial gate electrode layer disposed over the sacrificial gate dielectric layer. Opposing gate sidewall spacers are formed extending along the second direction, on opposing sides of the sacrificial gate electrode layer. The sacrificial gate electrode layer is removed to form a gate space. Fluorine is implanted into the gate sidewall spacers after removing the gate electrode layer by performing a first fluorine implantation. The sacrificial gate dielectric layer is removed and a high-k gate dielectric layer is formed in the gate space. Fluorine is implanted into the gate sidewall spacers and the fin after forming the high-k gate dielectric layer by performing a second fluorine implantation.

A semiconductor structure includes a substrate, a buried oxide layer formed in the substrate and near a surface of the substrate, a gate dielectric layer formed on the substrate and covering the buried oxide layer, a gate structure formed on the gate dielectric layer and overlapping the buried oxide layer, and a source region and a drain region formed in the substrate and at two sides of the gate structure.

A semiconductor device includes a field-effect transistor, a first back-end-of-line (BEOL) metallization level and a second BEOL metallization level disposed above the first BEOL metallization level. A portion of the field-effect transistor includes lithium therein, and the field-effect transistor is integrated between the first and second BEOL metallization levels. The portion of the field-effect transistor including the lithium therein can be a channel layer, or a source and/or drain region.

The present disclosure provides a transistor, a transistor forming method thereof, and a semiconductor device. The transistor forming method comprises providing a substrate, the substrate comprising a first region for forming a source region and a second region for forming a drain region; forming a gate groove in the substrate to separate the first region and the second region, a part of the substrate along the bottom of the gate groove being used for constituting an embedded channel region of a transistor; forming a gate dielectric layer on the gate groove of the substrate to cover the embedded channel region and to extend to cover a side of the first region and a side of the second region in the gate groove; and forming a gate conductive layer on the gate dielectric layer of the substrate and in the gate groove.

The semiconductor device includes a well region disposed in a surface layer of a semiconductor substrate, a source region and a drain region arranged separated from each other in a surface layer of the well region, a channel region disposed between the source region and the drain region, and a gate electrode disposed on the channel region via a gate insulating film containing fluorine, in which concentration of fluorine existing in a first interface, the first interface being an interface of the gate insulating film with the gate electrode, and concentration of fluorine existing in a second interface, the second interface being an interface of the gate insulating film with the channel region, are higher than concentration of fluorine existing in a middle region in the depth direction of the gate insulating film, and fluorine concentration in the first interface is higher than fluorine concentration in the second interface.

A method for forming a gate oxide film of a transistor device includes: step 1: forming a hard mask layer on the surface of a semiconductor substrate, etching the hard mask layer and the semiconductor substrate to form shallow trenches; step 2: performing an tilt-angle ion implantation to the upper area of the side surfaces of each shallow trench to form an upper doped region; step 3: filling a field oxide layer into the shallow trenches and removing the hard mask layer; and step 4: performing thermal oxidation to form a gate oxide film on the surface of an active region. The method can improve the morphology of the gate oxide film, thus increase the breakdown voltage threshold and reliability of the device.

A method for forming a gate oxide film of a transistor device includes: step 1: forming a hard mask layer on the surface of a semiconductor substrate, etching the hard mask layer and the semiconductor substrate to form shallow trenches; step 2: performing an tilt-angle ion implantation to the upper area of the side surfaces of each shallow trench to form an upper doped region; step 3: filling a field oxide layer into the shallow trenches and removing the hard mask layer; and step 4: performing thermal oxidation to form a gate oxide film on the surface of an active region. The method can improve the morphology of the gate oxide film, thus increase the breakdown voltage threshold and reliability of the device.

A method is provided for operating a semiconductor device which includes an IGBT having a desaturation semiconductor structure connected to a first electrode terminal and a gate electrode terminal for controlling a desaturation channel. The method includes: applying a first gate voltage to the gate electrode terminal so that current flows through the IGBT between the first electrode terminal and a second electrode terminal and current flow through the desaturation channel is substantially blocked; applying a different second gate voltage to the gate electrode terminal so that current flows through the IGBT between the first and second electrode terminals and charge carriers flow as a desaturating current through the desaturation channel to the first electrode terminal; and applying a different third gate voltage to the gate electrode terminal so that current flow through the IGBT between the first and second electrode terminals is substantially blocked.

A method for fabricating a semiconductor device includes forming a fin extending along a first direction on a semiconductor substrate and forming a sacrificial gate electrode structure extending along a second direction substantially perpendicular to the first direction over the fin. The sacrificial gate electrode structure comprises a sacrificial gate dielectric layer and a sacrificial gate electrode layer disposed over the sacrificial gate dielectric layer. Opposing gate sidewall spacers are formed extending along the second direction, on opposing sides of the sacrificial gate electrode layer. The sacrificial gate electrode layer is removed to form a gate space. Fluorine is implanted into the gate sidewall spacers after removing the gate electrode layer by performing a first fluorine implantation. The sacrificial gate dielectric layer is removed and a high-k gate dielectric layer is formed in the gate space. Fluorine is implanted into the gate sidewall spacers and the fin after forming the high-k gate dielectric layer by performing a second fluorine implantation.