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

Power semiconductor devices are key components in power conversion systems. Silicon carbide (SiC) has received increasing attention as a wide-bandgap semiconductor suitable for high-voltage and low-loss power devices. Through recent progress in the crystal growth and process technology of SiC, the production of medium-voltage (600?1700 V) SiC Schottky barrier diodes (SBDs) and power metal?oxide?semiconductor field-effect transistors (MOSFETs) has started. However, basic understanding of the material properties, defect electronics, and the reliability of SiC devices is still poor. In this review paper, the features and present status of SiC power devices are briefly described. Then, several important aspects of the material science and device physics of SiC, such as impurity doping, extended and point defects, and the impact of such defects on device performance and reliability, are reviewed. Fundamental issues regarding SiC SBDs and power MOSFETs are also discussed.

https://iopscience.iop.org/article/10.7567/JJAP.54.040103/pdf

Material science and device physics in SiC technology for high-voltage power devices

SiC electronic device technology has made rapid progress during the past decade In this paper, we review the evolution of SiC power MOSFETs between 1992 and the present, discuss the current status of device development, identify the critical fabrication issues, and assess the prospects for continued progress and eventual commercialization

Status and prospects for SiC power MOSFETs

Silicon carbide (SiC) offers significant advantages for power-switching devices because the critical field for avalanche breakdown is about ten times higher than in silicon. SiC power devices have made remarkable progress in the past five years, demonstrating currents in excess of 100 A and blocking voltages in excess of 19000 V. In this paper we describe the latest progress in three classes of SiC devices: diodes (p-i-n and Schottky), transistors (junction field-effect transistor, metal-oxide-semiconductor field-effect transistor, and bipolar junction transistor), and thyristors (gate turn-off).

SiC power-switching devices-the second electronics revolution?

A dramatic improvement of inversion channel mobility in 4H-SiC MOSFETs was successfully achieved by utilizing the (112~0) face: 17 times higher (95.9 cm/sup 2//Vs) than that on the conventional (0001) Si-face (5.59 cm/sup 2//Vs). A low threshold voltage of MOSFETs on the (112~0) face indicates that the (112~0) MOS interface has fewer negative charges than the (0001) MOS interface. Small anisotropy of channel mobility in 4H-SiC MOSFETs (/spl mu//sub (11~00)///spl mu//sub (0001)/=0.85) reflects the small anisotropy in bulk electron mobility.

High channel mobility in inversion layers of 4H-SiC MOSFETs by utilizing (112~0) face

A novel silicon carbide UMOSFET structure is reported. This device incorporates two new features: a self-aligned p-type implantation in the bottom of the trench that reduces the electric field in the trench oxide, and an n-type epilayer under the p-base to promote lateral current spreading into the drift region. This UMOS structure is capable of supporting the full blocking voltage of the pn junction while keeping the electric field in the gate oxide below 4 MV/cm. An accumulation channel is formed on the sidewalls of the trench by epigrowth, and the gate oxide is produced by a polysilicon oxidation process, resulting in a uniform oxide thickness over both the sidewalls and bottom of the trench. The fabricated 4H-SiC devices have a blocking voltage of 1400 V (10 /spl mu/m drift region), a specific on-resistance of 15.7 m/spl Omega/-cm/sup 2/ at room temperature, and a gate oxide field of 3 MV/cm.

J.A. Cooper

Papers

High-voltage accumulation-layer UMOSFET's in 4H-SiC