Emerging trends in wide band gap semiconductors (SiC and GaN) technology for power devices

A sustainable energy future requires power electronics that can enable significantly higher efficiencies in the generation, distribution, and usage of electrical energy. Silicon carbide (4H-SiC) is one of the most technologically advanced wide bandgap semiconductor that can outperform conventional silicon in terms of power handling, maximum operating temperature, and power conversion efficiency in power modules. While SiC Schottky diode is a mature technology, SiC power Metal Oxide Semiconductor Field Effect Transistors are relatively novel and there is large room for performance improvement. Specifically, major initiatives are under way to improve the inversion channel mobility and gate oxide stability in order to further reduce the on-resistance and enhance the gate reliability. Both problems relate to the defects near the SiO2/SiC interface, which have been the focus of intensive studies for more than a decade. Here we review research on the SiC MOS physics and technology, including its brief history, the state-of-art, and the latest progress in this field. We focus on the two main scientific problems, namely, low channel mobility and bias temperature instability. The possible mechanisms behind these issues are discussed at the device physics level as well as the atomic scale, with the support of published physical analysis and theoretical studies results. Some of the most exciting recent progress in interface engineering for improving the channel mobility and fundamental understanding of channel transport is reviewed.

Silicon carbide: A unique platform for metal-oxide-semiconductor physics

The higher voltage blocking capability and faster switching speed of silicon-carbide (SiC) mosfet s have the potential to replace Si insulated gate bipolar transistors (IGBTs) in medium-/low-voltage and high-power applications. In this paper, a state-of-the-art commercially available 325 A, 1700 V SiC mosfet module has been fully characterized under various load currents, bus voltages, and gate resistors to reveal their switching capability. Meanwhile, Si IGBT modules with similar power ratings are also tested under the same conditions. From the test results, several interesting points have been obtained: different to the Si IGBT module, the over-shoot current of the SiC mosfet module increases linearly with the increase of the load current and it has been explained by a model of the over-shoot current proposed in this paper; the induced negative gate voltage due to the complementary device turn- off (crosstalk effect) is more harmful to the SiC mosfet module than the induced positive gate voltage during turn- on when the gate off-voltage is –6 V; the maximum dv / dt and di / dt (electromagnetic interference) during switching transients of the SiC mosfet module are close to those of the Si IGBT module when the gate resistance is larger than 8 Ω but the switching loss of the SiC mosfet module is much smaller; the switching losses of the Si IGBT module are greater than those of the SiC mosfet module even when the gate resistance of the former is reduced to zero. An accurate power loss model, which is suitable for a three-phase two-level converter based on SiC mosfet modules considering the power loss of the parasitic capacitance, has been presented and verified in this paper. From the model, a 96.2% efficiency can be achieved at the switching frequency of 80 kHz and the power of 100 kW.

Performance Evaluation of High-Power SiC MOSFET Modules in Comparison to Si IGBT Modules

Wide bandgap (WBG) device-based power electronics converters are more efficient and lightweight than silicon-based converters. WBG devices are an enabling technology for many motor drive applications and new classes of compact and efficient motors. This paper reviews the potential applications and advances enabled by WBG devices in ac motor drives. Industrial motor drive products using WBG devices are reviewed, and the benefits are highlighted. This paper also discusses the technical challenges, converter design considerations, and design tradeoffs in realizing the full potential of WBG devices in motor drives. There is a tradeoff between high switching frequency and other issues such as high dv/dt and electromagnetic interference. The problems of high common mode currents and bearing and insulation damage, which are caused by high dv/dt , and the reliability of WBG devices are discussed.

Wide Bandgap Devices in AC Electric Drives: Opportunities and Challenges

This silicon-carbide semiconductor device (101) has a silicon-carbide substrate (10), a main electrode (52), a first barrier layer (70a), and a wiring layer (60). The main electrode (52) is provided directly on top of the silicon-carbide substrate (10). The first barrier layer (70a) is provided on top of the main electrode (52) and is made from a conductive material that does not contain aluminum. The wiring layer (60) is provided on top of the first barrier layer (70a), is isolated from the main electrode (52) by the first barrier layer (70a), and is made from a material that does contain aluminum.

Silicon carbide semiconductor device

A semiconductor device includes a semiconductor body and an insulated gate contact on a surface of the semiconductor body over an active channel in the semiconductor device. The insulated gate contact includes a channel mobility enhancement layer on the surface of the semiconductor body, a diffusion barrier layer over the channel mobility enhancement layer, and a dielectric layer over the diffusion barrier layer. By using the channel mobility enhancement layer in the insulated gate contact, the mobility of the semiconductor device is improved. Further, by using the diffusion barrier layer, the integrity of the gate oxide is retained, resulting in a robust semiconductor device with a low on-state resistance.

Semiconductor device with improved insulated gate

반도체 디바이스들은 넓은 밴드갭 반도체 재료를 포함하는 드리프트 영역을 포함하는 반도체 층 구조체를 포함한다. 드리프트 영역 중 하나에 대향하는 전도형의 차폐 패턴은 디바이스의 능동 영역 내의 드리프트 영역의 상부 부분 내에 제공되고 드리프트 영역 중 하나에 대향하는 전도형의 종단 구조체는 디바이스의 종단 영역 내의 드리프트 영역의 상부 부분 내에 제공된다. 게이트 트렌치는 반도체 층 구조체의 상부 표면 내로 연장된다. 반도체 층 구조체는 종단 구조체 위에 연장되고 종단 구조체를 적어도 부분적으로 커버하는 반도체 층을 포함한다.

게이트 트렌치들 및 매립된 종단 구조체들을 갖는 전력 반도체 디바이스들 및 관련 방법들

Embodiments of a semiconductor device having increased channel mobility and methods of manufacturing thereof are disclosed. In one embodiment, the semiconductor device includes a substrate including a channel region and a gate stack on the substrate over the channel region. The gate stack includes an alkaline earth metal. The alkaline earth metal results in a substantial improvement of the channel mobility of the semiconductor device.

Silicon carbide semiconductor device with increased channel mobility

Power semiconductor devices include multi-layer inter-metal dielectric patterns that include at least one reflowed dielectric material pattern and at least one non-reflowable dielectric material pattern. In other embodiments, power semiconductor devices include reflowed inter-metal dielectric patterns that are formed using sacrificial structures such as dams to limit the lateral spread of the reflowable dielectric material of the inter-metal dielectric pattern during the reflow process. The inter-metal dielectric patterns may have improved shapes and performance.

Power semiconductor devices having reflowed inter-metal dielectric layers

Semiconductor devices include a semiconductor layer structure, comprising a drift region that includes a wide band-gap semiconductor material. A shielding pattern of a conductivity type opposite to the one of the drift region is provided in an upper portion of the drift region in an active region of the device and a termination structure of a conductivity type opposite to the one of the drift region is provided in the upper portion of the drift region in a termination region of the device. A gate trench extends into an upper surface of the semiconductor layer structure. The semiconductor layerstructure includes a semiconductor layer that extends above and at least partially covers the termination structure.

Daniel J. Lichtenwalner

Papers

Semiconductor device with improved insulated gate

게이트 트렌치들 및 매립된 종단 구조체들을 갖는 전력 반도체 디바이스들 및 관련 방법들

Silicon carbide semiconductor device with increased channel mobility

Power semiconductor devices having reflowed inter-metal dielectric layers

Power semiconductor devices having gate trenches and buried termination structures and related methods