A compound semiconductor device includes: a compound semiconductor region having a surface in which a step is formed; a first electrode formed so as to overlie the upper surface of the step, the upper surface being a non-polar face; and a second electrode formed along a side surface of the step so as to be spaced apart from the first electrode in a vertical direction, the side surface being a polar face.

A semiconductor integrated circuit device may include a standard cell region on a surface of a substrate and a first active region on the surface of the substrate in the standard cell region, wherein the first active region has a length in a first direction. A second active region may be on the surface of the substrate in the standard cell region, the second active region may have a length in the first direction, the length of the second active region may be greater than the length of the first active region, and an axis in a second direction may intersect centers of the first and second active regions so that the first and second active regions are symmetric about the axis in the second direction. A first gate electrode may extend across the first active region in the first direction, and a second gate electrode may extend across the second active region in the first direction.

A semiconductor device structure and method for forming the same are provided. The semiconductor device structure includes a substrate and a gate stack structure formed on the substrate. The semiconductor device structure also includes gate spacers formed on the sidewall of the gate stack structure, and the gate spacers include a top portion and a bottom portion adjoined to the top portion, and the bottom portion slopes to a top surface of the substrate. The semiconductor device structure further includes an epitaxial structure formed adjacent to the gate spacers, and the epitaxial structure is formed below the gate spacers.

Nanowire-based gate all-around transistor devices having one or more active nanowires and one or more inactive nanowires are described herein. Methods to fabricate such devices are also described. One or more embodiments of the present invention are directed at approaches for varying the gate width of a transistor structure comprising a nanowire stack having a distinct number of nanowires. The approaches include rendering a certain number of nanowires inactive (i.e. so that current does not flow through the nanowire), by severing the channel region, burying the source and drain regions, or both. Overall, the gate width of nanowire-based structures having a plurality of nanowires may be varied by rendering a certain number of nanowires inactive, while maintaining other nanowires as active.

An interconnect fabrication method is disclosed herein that utilizes a disposable etch stop hard mask over a gate structure during source/drain contact formation and replaces the disposable etch stop hard mask with a dielectric feature (in some embodiments, dielectric layers having a lower dielectric constant than a dielectric constant of dielectric layers of the disposable etch stop hard mask) before gate contact formation. An exemplary device includes a contact etch stop layer (CESL) having a first sidewall CESL portion and a second sidewall CESL portion separated by a spacing and a dielectric feature disposed over a gate structure, where the dielectric feature and the gate structure fill the spacing between the first sidewall CESL portion and the second sidewall CESL portion. The dielectric feature includes a bulk dielectric over a dielectric liner. The dielectric liner separates the bulk dielectric from the gate structure and the CESL.

A semiconductor device includes first and second external dummy areas, and a circuit area between the first and second external dummy areas. The circuit area includes circuit active regions and circuit gate lines. Each external dummy area includes an external dummy active region and external dummy gate lines overlapping the external dummy active region and spaced apart from the circuit gate lines. The external dummy active region has a linear shape extending in a first horizontal direction or a shape including active portions isolated from direct contact with each other and extending sequentially in the first horizontal direction. The circuit active regions are between the first and second external dummy active regions and include a first plurality of circuit active regions extending sequentially in the first horizontal direction and a second plurality of circuit active regions extending sequentially in a second horizontal direction perpendicular to the first horizontal direction.

A method for fabricating a semiconductor device includes the steps of forming a metal gate on a substrate, a contact etch stop layer (CESL) adjacent to the metal gate, and an interlayer dielectric (ILD) layer around the gate structure, performing a first etching process to remove the ILD layer, performing a second etching process to remove the CESL for forming a first contact hole, and then forming a first contact plug in the first contact hole. Preferably, a width of the first contact plug adjacent to the CESL is less than a width of the first contact plug under the CESL.

A nitride semiconductor device includes: a nitride semiconductor layer; a gate electrode finger having at least one end portion, and extending along a surface of the nitride semiconductor layer; and a drain electrode finger having at least one end portion on the same side as that of the one end portion of the gate electrode finger, and extending along the gate electrode finger, wherein the one end portion of the drain electrode finger protrudes relative to the one end portion of the gate electrode finger.

Silicon fins are formed in a bulk silicon substrate and thereafter trench isolation regions are formed between each silicon fin. The silicon fins in nFET and pFET device regions are then recessed. A relaxed silicon germanium alloy fin portion is formed on a topmost surface of each recessed silicon fin portion or on exposed surface of the substrate. A compressively strained silicon germanium alloy fin portion is formed on each relaxed silicon germanium alloy fin portion within the pFET device region, and a strained silicon-containing fin portion is formed on each relaxed silicon germanium alloy fin portion within the nFET device region. Sidewall surfaces of each compressively strained silicon-containing germanium alloy fin portion and each tensile strained silicon-containing fin portion are then exposed. A functional gate structure is provided on the exposed sidewall surfaces of each compressively strained silicon-containing germanium alloy fin portion and each tensile strained silicon-containing fin portion.

Semiconductor devices that each include a channel region and a gate stack are disclosed. The gate stack includes a gate insulator, a pair of spaced apart first metal gate layers, and a second metal gate layer. The gate insulator extends along the length of the channel region. The first metal gate layers have a first workfunction and extend from the gate insulator. The second metal gate layer is disposed between the first metal gate layers, has a second workfunction different from the first workfunction, and extends from the gate insulator. Methods of fabricating the gate stack are also disclosed.