In an SOI substrate having a semiconductor substrate serving as a support substrate, an insulating layer on the semiconductor substrate and a semiconductor layer on the insulating layer, an element isolation region which penetrates the semiconductor layer and the insulating layer and whose bottom part reaches the semiconductor substrate is formed, and a gate electrode is formed on the semiconductor layer via a gate insulating film. A divot is formed in the element isolation region at a position adjacent to the semiconductor layer, and a buried insulating film is formed in the divot. The gate electrode includes a part formed on the semiconductor layer via the gate insulating film, a part located on the buried insulating film and a part located on the element isolation region.

This semiconductor device is provided with: a semiconductor film that comprises an oxide semiconductor, and includes a channel region; a first inorganic insulating film formed on the semiconductor film; a first organic insulating film formed on the first inorganic insulating film; and an inorganic film group. The inorganic film group has: a first electrode comprising an inorganic conductive film formed on the first organic insulating film; a second inorganic insulating film formed on the first electrode; and a second electrode that comprises an inorganic conductive film formed on the second inorganic insulating film, and is electrically connected to the semiconductor film via openings formed in such a manner as to penetrate the first inorganic insulating film, the first organic insulating film, the first electrode and the second inorganic insulating film. The first organic insulating film is disposed between the first inorganic insulating film and the inorganic film group.

The present invention belongs to the field of display technology and provides a thin film transistor and a manufacturing method thereof, an array substrate and a display device. The thin film transistor comprises a gate, a source, a drain and a plurality of insulating layers, wherein at least one insulating layer comprises a Group VB metal oxide. Since the insulting layer is formed by using the Group VB metal oxide which has high dielectric constant, the thickness of the insulating layer can be reduced and the thin film transistor can be miniaturized.

A display device includes a buffer layer disposed on a substrate and comprising a first buffer film, and a second buffer film, wherein the first buffer film and the second buffer film are sequentially stacked in a thickness direction of the display device; a semiconductor pattern disposed on the buffer layer; a gate insulating layer disposed on the semiconductor pattern; and a gate electrode disposed on the gate insulating layer, wherein the first buffer film and the second buffer film comprise a same material, and a density of the first buffer film is greater than a density of the second buffer film.

It is an object to provide a highly reliable semiconductor device which includes a thin film transistor having stable electric characteristics. It is another object to manufacture a highly reliable semiconductor device at lower cost with high productivity. In a method for manufacturing a semiconductor device which includes a thin film transistor where a semiconductor layer having a channel formation region, a source region, and a drain region are formed using an oxide semiconductor layer, heat treatment (heat treatment for dehydration or dehydrogenation) is performed so as to improve the purity of the oxide semiconductor layer and reduce impurities such as moisture. Moreover, the oxide semiconductor layer subjected to the heat treatment is slowly cooled under an oxygen atmosphere.

In a transistor having a top-gate structure in which a gate electrode layer overlaps with an oxide semiconductor layer which faints a channel region with a gate insulating layer interposed therebetween, when a large amount of hydrogen is contained in the insulating layer, hydrogen is diffused into the oxide semiconductor layer because the insulating layer is in contact with the oxide semiconductor layer; thus, electric characteristics of the transistor are degraded. An object is to provide a semiconductor device having favorable electric characteristics. An insulating layer in which the concentration of hydrogen is less than 6×10.sup.20 atoms/cm.sup.3 is used for the insulating layer being in contact with oxide semiconductor layer which forms the channel region. Using the insulating layer, diffusion of hydrogen can be prevented and a semiconductor device having favorable electric characteristics can be provided.

According to an aspect of the present inventive concept there is provided a method for forming a first and a second transistor structure, wherein the first and second transistor structures are spaced apart by an insulating wall, and the method comprising: forming on a semiconductor layer of the substrate a first semiconductor layer stack and a second semiconductor layer stack, each layer stack comprising in a bottom-up direction a sacrificial layer and a channel layer, wherein the layer stacks are spaced apart by a trench extending into the semiconductor layer substrate, the trench being filled with an insulating wall material to form the insulating wall; and processing the layer stacks to form the first and second transistor structures in the first and second device regions, respectively, the processing comprising forming source and drain regions and forming gate stacks; the method further comprising, prior to said processing: by etching removing the sacrificial layer of each layer stack to form a respective cavity on either sides of the insulating wall underneath the channel layer of the first and second layer stack, the channel layers being supported by the insulating wall; and depositing a bottom insulating material in said cavities;
wherein, subsequent to said processing, the bottom insulating material forms a bottom insulating layer underneath the source region, the drain region and the channel regions on either side of the insulating wall.

A structure includes a field effect transistor (FET) stack including a plurality of transistors over a buried insulator layer. A polysilicon isolation region is in a substrate below the FET stack and the buried insulator layer. A resistor network is in the polysilicon isolation region, the resistor network having a different resistivity than the polysilicon isolation region. The resistor network may include a resistive wire having a first width and a resistive pad within the resistive wire under each FET in the FET stack. Each resistive pad has a second width larger than the first width of the resistive wire. A length of the resistive wire is different aside each resistive pad to adjust a threshold voltage of an adjacent FET in the FET stack to a predetermined value to compensate for non-linear voltage distribution between an input and an output of the FET stack.

A highly reliable semiconductor device the yield of which can be prevented from decreasing due to electrostatic discharge damage is provided. A semiconductor device is provided which includes a gate electrode layer, a first gate insulating layer over the gate electrode layer, a second gate insulating layer being over the first gate insulating layer and having a smaller thickness than the first gate insulating layer, an oxide semiconductor layer over the second gate insulating layer, and a source electrode layer and a drain electrode layer electrically connected to the oxide semiconductor layer. The first gate insulating layer contains nitrogen and has a spin density of 1×10.sup.17 spins/cm.sup.3 or less corresponding to a signal that appears at a g-factor of 2.003 in electron spin resonance spectroscopy. The second gate insulating layer contains nitrogen and has a lower hydrogen concentration than the first gate insulating layer.

A semiconductor device comprising a first transistor, a second insulating film, a conductive film, and a capacitor is provided. The first transistor comprises a first oxide semiconductor film, a gate insulating film over the first oxide semiconductor film, and a gate electrode over the gate insulating film. The second insulating film is provided over the gate electrode. The conductive film is electrically connected to the first oxide semiconductor film. The capacitor comprises a second oxide semiconductor film, the second insulating film over the second oxide semiconductor film, and the conductive film over the second insulating film. The first oxide semiconductor film comprises a first region and a second region. Each of a carrier density of the second region and a carrier density of the second oxide semiconductor film is higher than a carrier density of the first region.