An object is to provide a semiconductor device of which a manufacturing process is not complicated and by which cost can be suppressed, by forming a thin film transistor using an oxide semiconductor film typified by zinc oxide, and a manufacturing method thereof. For the semiconductor device, a gate electrode is formed over a substrate; a gate insulating film is formed covering the gate electrode; an oxide semiconductor film is formed over the gate insulating film; and a first conductive film and a second conductive film are formed over the oxide semiconductor film. The oxide semiconductor film has at least a crystallized region in a channel region.

Semiconductor device, and manufacturing method thereof

Various embodiments provide systems and methods capable of facilitating interaction with handheld electronics devices based on sensing rotational rate around at least three axes and linear acceleration along at least three axes. In one aspect, a handheld electronic device includes a subsystem providing display capability, a set of motion sensors sensing rotational rate around at least three axes and linear acceleration along at least three axes, and a subsystem which, based on motion data derived from at least one of the motion sensors, is capable of facilitating interaction with the device.

Controlling and accessing content using motion processing on mobile devices

Recent success with the fabrication of high-performance GaN-on-Si high-voltage HFETs has made this technology a contender for power electronic applications. This paper discusses the properties of GaN that make it an attractive alternative to established silicon and emerging SiC power devices. Progress in development of vertical power devices from bulk GaN is reviewed followed by analysis of the prospects for GaN-on-Si HFET structures. Challenges and innovative solutions to creating enhancement-mode power switches are reviewed.

https://iopscience.iop.org/article/10.1088/0268-1242/28/7/074011/pdf

Gallium nitride devices for power electronic applications

In this paper, GaN power transistors on Si substrates for power switching application are reported. GaN heterojunction field-effect transistor (HFET) structure on Si is an important configuration in order to realize a low loss and high power devices as well as one of the cost-effective solutions. Current collapse phenomena are discussed for GaN-HFETs on Si substrate, resulting in suppression of the current collapse due to using the conducting Si substrate. Furthermore, attempts for normally off GaN-FETs were examined. A hybrid metal-oxide-semiconductor HFET structure is a promising candidate for obtaining devices with a lower on-resistance (Ron) and a high breakdown voltage (Vb).

GaN Power Transistors on Si Substrates for Switching Applications

In this paper, GaN power transistors on Si substrates for power switching application are reported. GaN heterojunction field-effect transistor (HFET) structure on Si is an important configuration in order to realize a low loss and high power devices as well as one of the cost-effective solutions. Current collapse phenomena are discussed for GaN-HFETs on Si substrate, resulting in suppression of the current collapse due to using the conducting Si substrate. Furthermore, attempts for normally off GaN-FETs were exam- ined. A hybrid metal-oxide-semiconductor HFET structure is a promising candidate for obtaining devices with a lower on-resistance ðRonÞ and a high breakdown voltage ðVbÞ.

GaN Power Transistors on Si Substrates for Switching Applications Hybrid MOS-FET transistor devices with low on-resistance, high hold-voltages and high breakdown voltage promise to provide high-power, low-loss operation for switching applications.

A novel method for fabricating trench structures on GaN was developed. A smooth non-polar (1100) plane was obtained by wet etching using tetramethylammonium hydroxide (TMAH) as the etchant. A U-shape trench with the (1100) plane side walls was formed with dry etching and the TMAH wet etching. A U-shape trench gate metal oxide semiconductor field-effect transistor (MOSFET) was also fabricated using the novel etching technology. This device has the excellent normally-off operation of drain current–gate voltage characteristics with the threshold voltage of 10 V. The drain breakdown voltage of 180 V was obtained. The results indicate that the trench gate structure can be applied to GaN-based transistors.

https://iopscience.iop.org/article/10.1143/APEX.1.021104/pdf

GaN-Based Trench Gate Metal Oxide Semiconductor Field-Effect Transistor Fabricated with Novel Wet Etching

We fabricated a vertical insulated gate AlGaN/GaN heterojunction field-effect transistor (HFET), using a free-standing GaN substrate. This HFET has apertures through which the electron current vertically flows. These apertures were formed by dry etching the p-GaN layer below the gate electrodes and regrowing n--GaN layer without mask. The HFET exhibited a specific on-resistance of as low as 2.6 mΩ·cm2 with a threshold voltage of -16 V. This HFET would be a prototype of a GaN-based high-power switching device.

https://iopscience.iop.org/article/10.1143/JJAP.46.L503/pdf

A Vertical Insulated Gate AlGaN/GaN Heterojunction Field-Effect Transistor

The semiconductor device has a stacked structure in which a p-GaN layer 32, an SI-GaN layer 62, and an AlGaN layer 34 are stacked, and has a gate electrode 44 that is formed at a top surface side of the AlGaN layer 34. A band gap of the AlGaN layer 34 is wider than a band gap of the p-GaN layer 32 and the SI-GaN layer 62. Moreover, impurity concentration of the SI-GaN layer 62 is less than 1x1017cm-3. The semiconductor devices comprising III-V semiconductors that have a stable normally-off operation are realized.

Iii-v hemt devices

We carried out nondestructive measurements of the depth profile of etching-induced damage in p-type gallium nitride (p-GaN), in particular surface band bending, using Hard X-ray Photoelectron Spectroscopy (HAX-PES). HAX-PES at different take-off angles of photoelectrons made it clear that etching by inductively coupled plasma (ICP) introduced donor-like states in a surface layer of GaN. We were able to quantitatively analyze band bending and charge distribution in an etched p-GaN. The analysis results indicated the existence of deep donors with a concentration of 1―2 x 10 20 cm ―3 in a surface layer whose thickness increased with increasing a bias power of ICP.

Study of etching-induced damage in GaN by hard X-ray photoelectron spectroscopy

A semiconductor device is provided with a drain electrode 22, a semiconductor base plate 32, an electric current regulation layer 42 covering a part of a surface of the semiconductor base plate 32 and leaving a non-covered surface 55 at the surface of the semiconductor base plate 32, a semiconductor layer 50 covering a surface of the electric current regulation layer 42, and a source electrode 62 formed at a surface of the semiconductor layer 50. A drift region 56, a channel forming region 54, and a source region 52 are formed within the semiconductor layer 50. The drain electrode 22 is connected to a first terminal of a power source, and the source electrode 62 is connected to a second terminal of the power source. With this semiconductor layer 50, it is possible to increase withstand voltage or reduce the occurrence of current leakage.

Masahiro Sugimoto

Papers

GaN-Based Trench Gate Metal Oxide Semiconductor Field-Effect Transistor Fabricated with Novel Wet Etching

A Vertical Insulated Gate AlGaN/GaN Heterojunction Field-Effect Transistor

Iii-v hemt devices

Study of etching-induced damage in GaN by hard X-ray photoelectron spectroscopy

Semiconductor devices and method of manufacturing them