The present disclosure relates to semiconductor structures and, more particularly, to metal-oxide semiconductor transistors and methods of manufacture. The structure includes: a substrate comprising a drift region and a body region; a gate structure between the drift region and the body region; an insulator material over the gate structure, the drift region and the body region; and an air gap within the insulator material and extending into the drift region.

The present disclosure describes a structure with a conductive plate and a method for forming the structure. The structure includes a gate structure disposed on a diffusion region of a substrate, a protective layer in contact with the diffusion region and covering a sidewall of the gate structure and a portion of a top surface of the gate structure, and a first insulating layer in contact with the gate structure and the protective layer. The structure further includes a conductive plate in contact with the first insulating layer, where a first portion of the conductive plate laterally extends over a horizontal portion of the protective layer, and where a second portion of the conductive plate extends over a sidewall portion of the protective layer covering the sidewall of the gate structure. The structure further includes a second insulating layer in contact with the conductive plate.

A high voltage semiconductor device includes a semiconductor substrate, an isolation structure, a gate oxide layer, and a gate structure. The semiconductor substrate includes a channel region, and at least a part of the isolation structure is disposed in the semiconductor substrate and surrounds the channel region. The gate oxide layer is disposed on the semiconductor substrate, and the gate oxide layer includes a first portion and a second portion. The second portion is disposed at two opposite sides of the first portion in a horizontal direction, and a thickness of the first portion is greater than a thickness of the second portion. The gate structure is disposed on the gate oxide layer and the isolation structure.

A semiconductor device includes an isolation structure in a substrate. The semiconductor device further includes a gate structure over a first region of the substrate, wherein the isolation structure surrounds the first region, the gate structure comprising a first section and a second section. The semiconductor device further includes a conductive field plate over the substrate, the conductive field plate extending between the first section and the second section and overlapping an edge of the first region, wherein the conductive field plate comprises a dielectric layer having a variable thickness. The semiconductor device further includes a first well in the substrate, wherein the first well overlaps the edge of the first region, and the first well extends underneath the isolation structure, and the conductive field plate extends beyond an outer-most edge of the first well.

A lateral diffused semiconductor device is disclosed, including: a substrate; a first isolation and a second isolation comprising at least portions disposed in the substrate to define an active area; a first drift region and a second drift region disposed in the active area, wherein the first drift region is disposed in the second drift region; a gate structure on the substrate; a source region in the first drift region; a drain region in the second drift region; and a ring-shaped field plate on the substrate, wherein the ring-shaped field plate surrounds at least one of the source and the drain region.

A semiconductor device includes: a substrate, a gate structure on the substrate, and a spacer adjacent to the gate structure, in which the spacer extends to a top surface of the gate structure, a top surface of the spacer includes a planar surface, the spacer encloses an air gap, and the spacer is composed of a single material. The gate structure includes a high-k dielectric layer, a work function metal layer, and a low resistance metal layer, in which the high-k dielectric layer is U-shaped. The semiconductor device also includes an interlayer dielectric (ILD) layer around the gate structure and a hard mask on the spacer, in which the top surface of the hard mask is even with the top surface of the ILD layer.

High voltage devices and methods for forming a high voltage device are disclosed. The method includes providing a substrate having top and bottom surfaces. The substrate is defined with a device region and a recessed region disposed within the device region. The recessed region includes a recessed surface disposed lower than the top surface of the substrate. A transistor is formed over the substrate. Forming the transistor includes forming a gate at least over the recessed surface and forming a source region adjacent to a first side of the gate below the recessed surface. Forming the transistor also includes forming a drain region displaced away from a second side of the gate. First and second device wells are formed in the substrate within the device region. The first device well encompasses the drain region and the second device well encompasses the source region.

Disclosed are methods that employ a mask with openings arranged in a pattern of elongated trenches and holes of varying widths to achieve a linearly graded conductivity level. These methods can be used to form a lateral double-diffused metal oxide semiconductor field effect transistor (LDMOSFET) with a drain drift region having an appropriate type conductivity at a level that increases essentially linearly from the body region to the drain region. Furthermore, these methods also provide for improve manufacturability in that multiple instances of this same pattern can be used during a single dopant implant process to implant a first dopant with a first type (e.g., N-type) conductivity into the drain drift regions of both first and second type LDMOSFETs (e.g., N and P-type LDMOSFETs, respectively). In this case, the drain drift region of a second type LDMOSFET can subsequently be uniformly counter-doped. Also disclosed are the resulting semiconductor structures.

The semiconductor device including: a semiconductor layer extending in a first direction, the semiconductor layer including a pair of source/drain regions and a channel region, a gate extending on the semiconductor layer to cover the channel region, and a gate dielectric layer interposed between the channel region and the gate, a corner insulating spacer having a first surface and a second surface, the first surface extending in the second direction along a side wall of the gate, the first surface covering from a side portion of the gate dielectric layer to at least a portion of the side wall of the gate, and the second surface covering a portion of the semiconductor layer, and an outer portion insulating spacer covering the side wall of the gate above the corner insulating spacer, the outer portion insulating spacer having a smaller dielectric constant than the corner insulating spacer, may be provided.

Using an STI insulating film in a high breakdown voltage MOSFET leads to deterioration in reliability due to impact ionization near the bottom corner of a drain isolation insulating film.

The invention provides a method of manufacturing a semiconductor integrated circuit device including forming a hard mask film, an opening therein, and a sidewall insulating film on the side surface thereof; forming a shallow trench in the opening with the hard mask film as a mask and oxidizing at least an exposed portion; filling the trench with an insulating film and then removing it so as to leave it outside the trench in the opening and thereby forming a drain offset STI insulating film inside and outside the trench; and forming a gate electrode extending from the upper portion of a gate insulating film in an active region contiguous thereto to the upper portion of the drain offset insulating film.