Semiconductor devices and methods of forming the same are provided. An exemplary semiconductor device according to the present disclosure includes a first gate structure disposed over a first backside dielectric feature, a second gate structure disposed over a second backside dielectric feature, and a gate cut feature extending continuously from laterally between the first gate structure and the second gate structure to laterally between the first backside dielectric feature and the second backside dielectric feature. The gate cut feature includes an air gap laterally between the first gate structure and the second gate structure.

Methods form transistor structures that include, among other components, a substrate having an active region bordered by an isolation region, a gate insulator on the substrate, and a gate conductor on the gate insulator. First and second sections of the gate conductor are within the active region of the substrate, while a third section is in the isolation region of the substrate. The second section of the gate conductor tapers from the width of the first section to the width of the wider third section. The first section and the second section of the gate conductor have undercut regions where the corner of the gate conductor contacts the substrate. The third section of the gate conductor lacks the undercut regions. The gate insulator is relatively thicker in the undercut regions and is relatively thinner where the corner of the gate conductor lacks the undercut regions in the isolation region.

The present disclosure relates to an etchant, a method of making an etchant, an etching method and a method of fabricating a semiconductor device using the same. The etching method includes supplying an etchant on an etch-target layer to etch the etch-target layer in a wet etch manner. The etchant contains a basic compound and a sugar alcohol, and the basic compound contains ammonium hydroxide or tetraalkyl ammonium hydroxide. In the etchant, the sugar alcohol has 0.1 to 10 parts by weight for every 100 parts by weight of the basic compound.

A method of fabricating a replacement gate stack for a semiconductor device includes the following steps after removal of a dummy gate: growing a high-k dielectric layer over the area vacated by the dummy gate; depositing a thin metal layer over the high-k dielectric layer; depositing a sacrificial layer over the thin metal layer; performing a first rapid thermal anneal; removing the sacrificial layer; and depositing a metal layer of low resistivity metal for gap fill.

Embodiments are directed to a method of forming a stacked nanosheet and resulting structures having equal thickness work function metal layers. A nanosheet stack is formed on a substrate. The nanosheet stack includes a first sacrificial layer formed on a first nanosheet. A hard mask is formed on the first sacrificial layer and the first sacrificial layer is removed to form a cavity between the hard mask and the first nanosheet. A work function layer is formed to fill the cavity between the hard mask and the first nanosheet.

A method of fabricating a replacement gate stack for a semiconductor device includes the following steps after removal of a dummy gate: growing a high-k dielectric layer over the area vacated by the dummy gate; depositing a thin metal layer over the high-k dielectric layer; depositing a sacrificial layer over the thin metal layer; performing a first rapid thermal anneal; removing the sacrificial layer; and depositing a metal layer of low resistivity metal for gap fill.

A semiconductor device includes a semiconductor substrate, a gate insulator provided on a surface of the semiconductor substrate, a bonding film, including silicon or aluminum, provided on the gate insulator, and a gate pad layer provided above the bonding film, wherein the gate pad layer includes titanium in at least a region in contact with the bonding film.

An electrical contact structure (an MIS contact) includes one or more conductors (M-Layer), a semiconductor (S-Layer), and an interfacial dielectric layer (I-Layer) of less than 4 nm thickness disposed between and in contact with both the M-Layer and the S-Layer. The I-Layer is an oxide of a metal or a semiconductor. The conductor of the M-Layer that is adjacent to and in direct contact with the I-Layer is a metal oxide that is electrically conductive, chemically stable and unreactive at its interface with the I-Layer at temperatures up to 450 C. The electrical contact structure has a specific contact resistivity of less than or equal to approximately 10.sup.5-10.sup.7 -cm.sup.2 when the doping in the semiconductor adjacent the MIS contact is greater than approximately 210.sup.19 cm.sup.3 and less than approximately 10.sup.8 -cm.sup.2 when the doping in the semiconductor adjacent the MIS contact is greater than approximately 10.sup.20 cm.sup.3.

The reliability of a semiconductor device is improved. In a manufacturing method, a film to be processed is formed over a circular semiconductor substrate, and a resist layer whose surface has a water-repellent property is formed thereover. Subsequently, the water-repellent property of the resist layer in the outer peripheral region of the circular semiconductor substrate is lowered by selectively performing first wafer edge exposure on the outer peripheral region of the semiconductor substrate, and then liquid immersion exposure is performed on the resist layer. Subsequently, second wafer edge exposure is performed on the outer peripheral region of the circular semiconductor substrate, and then the resist layer, on which the first wafer edge exposure, the liquid immersion exposure, and the second wafer edge exposure have been performed, is developed, so that the film to be processed is etched by using the developed resist layer.

If an optical path length of an optical system is reduced and a length of a laser light on an irradiation surface is increased, there occurs curvature of field which is a phenomenon that a convergent position deviates depending on an incident angle or incident position of a laser light with respect to a lens. To avoid this phenomenon, an optical element having a negative power such as a concave lens or a concave cylindrical lens is inserted to regulate the optical path length of the laser light and a convergent position is made coincident with a irradiation surface to form an image on the irradiation surface.