A structure includes a semiconductor-on-insulator (SOI) substrate including a semiconductor substrate, a buried insulator layer over the semiconductor substrate, and an SOI layer over the buried insulator layer. The structure also includes a first active device and a second active device. At least one polycrystalline active region fill shape is in the SOI layer. A polycrystalline isolation region is in the semiconductor substrate under the buried insulator layer. The polycrystalline isolation region is under the first active device, but not under the second active device. The polycrystalline isolation region extends to different depths into the semiconductor substrate. The first and second active devices may include monocrystalline active regions, and a third polycrystalline active region may also be in the SOI layer over the polycrystalline isolation region.

A semiconductor on insulator type substrate, comprising at least: a support layer; a semiconductor surface layer; a buried dielectric layer located between the support layer and the semiconductor surface layer; a trap rich layer located between the buried dielectric layer and the support layer, and comprising at least one polycrystalline semiconductor material and/or a phase change material; in which the trap rich layer comprises at least one first region and at least one second region adjacent to each other in the plane of the trap rich layer, the material of the at least one first region being in an at least partially recrystallized state and having an electrical resistivity less than that of the material in the at least one second region.

A semiconductor on insulator type substrate, comprising at least: a support layer; a semiconductor surface layer; a buried dielectric layer located between the support layer and the semiconductor surface layer; a trap rich layer located between the buried dielectric layer and the support layer, and comprising at least one polycrystalline semiconductor material and/or a phase change material; in which the trap rich layer comprises at least one first region and at least one second region adjacent to each other in the plane of the trap rich layer, the material of the at least one first region being in an at least partially recrystallized state and having an electrical resistivity less than that of the material in the at least one second region.

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 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.

Disclosed is a method for manufacturing an isolation structure for LDMOS, the method comprising: forming a first groove on the surface of a wafer; filling the first groove with silicon oxide; removing part of the surface of the silicon oxide within the first groove by means of etching; forming a silicon oxide corner structure at the corner of the top of the first groove by means of thermal oxidation; depositing a nitrogen-containing compound on the surface of the wafer to cover the surface of the silicon oxide within the first groove and the surface of the silicon oxide corner structure; dry-etching the nitrogen-containing compound to remove the nitrogen-containing compound from the surface of the silicon oxide within the first groove, and thereby forming a nitrogen-containing compound side wall residue; with the nitrogen-containing compound side wall residue as a mask, continuing to etch downwards to form a second groove; forming a silicon oxide layer on the side wall and the bottom of the second groove; removing the nitrogen-containing compound side wall residue; and filling the first groove and the second groove with silicon oxide.

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.

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.

The specification relates to a method for manufacturing a structured substrate provided with a trap-rich layer whereon rests a stack consisting of an insulating layer and of a layer of single-crystal material, the method comprising the following steps: a) a step of forming an amorphous silicon layer on a front face of a silicon substrate, b) a step of heat treating intended to convert the amorphous silicon layer into a trap-rich layer made of single-crystal silicon grains, the heat treatment conditions in terms of duration and of temperature being adjusted to limit the grains to a size less than 200 nm, c) a step of forming a stack by overlapping the trap-rich layer, and consisting of an insulating layer and of a layer of single-crystal material.

The specification relates to a method for manufacturing a structured substrate provided with a trap-rich layer whereon rests a stack consisting of an insulating layer and of a layer of single-crystal material, the method comprising the following steps: a) a step of forming an amorphous silicon layer on a front face of a silicon substrate, b) a step of heat treating intended to convert the amorphous silicon layer into a trap-rich layer made of single-crystal silicon grains, the heat treatment conditions in terms of duration and of temperature being adjusted to limit the grains to a size less than 200 nm, c) a step of forming a stack by overlapping the trap-rich layer, and consisting of an insulating layer and of a layer of single-crystal material.