An improved SGT MOSFET having low on-resistance is disclosed in this invention by adding a current spreading region under body region and a method to manufacture the same. With a doping concentration higher than the drift region, the inventive current spreading region can help reducing on-resistance while remaining a target breakdown voltage. Meanwhile, the present invention also features a method of formation of a new MSO structure with LOCOS technique for further improving on-resistance.

The present invention provides a nitride semiconductor device, including an insulating substrate, a substrate over the first surface of the insulating substrate, a first lateral transistor over a first region of the substrate, wherein the first lateral transistor includes a first nitride semiconductor layer formed over the substrate, and a first gate electrode, a first source electrode and a first drain electrode formed over the first nitride semiconductor layer, and a second lateral transistor over a second region of the substrate, wherein the second lateral transistor includes a second nitride semiconductor layer formed over the substrate, and a second gate electrode, a second source electrode and a second drain electrode formed over the second nitride semiconductor layer, and a separation trench formed over a third region, wherein the third region is between the first region and the second region.

The present invention provides a nitride semiconductor device capable of forming a half-bridge circuit and suppressing changes in current collapse characteristics. A first transistor of the present invention includes a first nitride semiconductor layer, and a first gate electrode, a first source electrode and a first drain electrode formed thereon. The second transistor includes a second nitride semiconductor layer, and a second gate electrode, a second source electrode and a second drain electrode formed thereon. The source electrode is electrically connected to a lower region of a first region on the substrate, the second source electrode is electrically connected to a lower region of a second region on the substrate, and a first insulating region is disposed between a portion corresponding to the first region on the substrate and a portion corresponding to the second region on the substrate.

A method for forming a semiconductor structure includes the following steps: providing a substrate having a trench in a surface; forming an isolation layer on the surface of the substrate, the isolation layer covering a side wall and a bottom wall of the trench; pretreating the isolation layer such that an initial oxide layer is formed on a surface of the isolation layer; forming an advanced oxide layer on a surface of the initial oxide layer with an atomic layer deposition process; and forming a dielectric layer on a surface of the advanced oxide layer with a spin-on dielectrics (SOD) process such that the dielectric layer fills the trench.

A method of manufacturing a trench type semiconductor device includes the following steps. First, an epitaxial layer is formed on a substrate, then a trench is formed in the epitaxial layer, and a gate structure is formed in the trench. The gate structure includes an upper gate and a lower gate, and an intermediate insulating portion, and the intermediate insulating portion is located in the upper gate.

The present disclosure describes a fabrication method that can form air-gaps in shallow trench isolation structures (STI) structures. For example, the method includes patterning a semiconductor layer over a substrate to form semiconductor islands and oxidizing the sidewall surfaces of the semiconductor islands to form first liners on the sidewall surfaces. Further, the method includes depositing a second liner over the first liners and the substrate and depositing a first dielectric layer between the semiconductor islands. The second liner between the first dielectric layer and the first liners is removed to form openings between the first dielectric layer and the first liners. A second dielectric layer is deposited over the first dielectric layer to enclose the openings and form air-gaps between the first dielectric layer and the first liners so that the gaps are positioned along the first liners.

A semiconductor device structure comprises a region of semiconductor material comprising a first conductivity type, a first major surface, and a second major surface opposite to the first major surface. A first trench gate structure includes a first trench extending from the first major surface into the region of semiconductor material, a first dielectric structure is over sidewall surfaces and a portion of a lower surface of the first trench, wherein the first dielectric structure comprises a first opening adjacent to the lower surface of the first trench, a first recessed contact extends through the first opening, and a first contact region is over the first recessed contact within the first trench, wherein the first recessed contact and the first contact region comprise different materials. A first doped region comprising a second dopant conductivity type opposite to the first conductivity type is in the region of semiconductor material and is spaced apart from the first major surface and below the first trench. A gate contact region is in the region of semiconductor material and is electrically connected to the first doped region.

A terrace insulating film (SL) to be overridden by a gate electrode (G) of an nLDMOS device is configured by LOCOS, and a device isolation portion (SS) is configured by STI. Furthermore, on an outermost periphery of an active region where a plurality of nLDMOS devices are formed, a guard ring having the same potential as that of a drain region (D) is provided. And, via this guard ring, the device isolation portion (SS) is formed in a periphery of the active region, thereby not connecting but isolating the terrace insulating film (SL) and the device isolation portion (SS) from each other.

A semiconductor device includes: a metal-oxide semiconductor (MOS) transistor on a substrate; a deep trench isolation structure in the substrate and around the MOS transistor; and a trap rich isolation structure in the substrate and surrounding the deep trench isolation structure. Preferably, the deep trench isolation structure includes a liner in the substrate and an insulating layer on the liner, in which the top surfaces of the liner and the insulating layer are coplanar. The trap rich isolation structure is made of undoped polysilicon and the trap rich isolation structure includes a ring surrounding the deep trench isolation structure according to a top view.

A method for fabricating semiconductor device comprising the steps of: forming a first trench and a second trench in a substrate; forming a liner in the first trench and the second trench; forming a first patterned mask on the substrate to cover the second trench; removing the liner in the first trench; removing the first patterned mask; and forming an insulating layer in the first trench and the second trench to form a trap rich isolation structure in the first trench and a deep trench isolation structure in the second trench.