功率半导体器件的发展和市场

功率半导体器件的全球销售额每年以约１５％的速率增长,而传统器件如ＳＣＲ和ＧＴＲ等的年增长率远小于新型器件。以Ｓｍａｒｔ Ｐｏｗｅｒ为代表的新型功率器件集功率、控制和信息于一体,是今后发展的重点。     

Recovery of negative bias temperature instability induced degradation of p-MOSFETs with SiON gate dielectric

This paper investigates the recovery property of p-MOSFETs with an ultra-thin SiON gate dielectric which are degraded by negative bias temperature instability (NBTI). The experimental results indicate that the recovery of the NBTI degradation occurs through an electrical neutralization of the NBTI-induced positive charges at the SiON/Si interface and in the gate dielectric. The neutralization of interface charges was a fast process occurring just after the device returned to the recovery state. The neutralization of positive charges in the gate dielectric was a slow process associated with the electron injection into the gate dielectric. Below the gate voltage for strong accumulation, the amount of recovery increased with an increase of the gate voltage. A further increase of gate voltage did not affect the amount of recovery. These experimental results indicate that the major cause of the recovery is a neutralization of the NBTI-induced positive charges by electrons instead of a hydrogen passivation of the NBTI-induced defect sites.     

Reliability of reverse properties of power semiconductor devices:: Influence of surface dielectric layer and its experimental verification

Reliability of reverse properties of power semiconductor devices is an important condition for their practical application. Usual standard tests do not reveal total information concerning the technological genetic aspects of devices production. These aspects can be linked with individual technological operations, most frequently with preparation of semiconductor surface and its protection by dielectric layers. Properties of dielectric layers influence the time stability of reverse currents by means of a change of dielectric permittivity. This article analyses some physical causes of the time-instable behaviour of devices and also presents a special method and equipment for reliable tests.     

Thermal characterisation of power devices during transient operation

An experimental infrared method for the thermal characterisation of semiconductor devices during fast transient operation, in the range from a few microseconds and up to some milliseconds, is presented. The features which make it suitable and convenient, particularly for use with power electronics applications are pointed out; its time and space resolution are illustrated by means of properly chosen examples. The considered solution qualifies as a very versatile and powerful tool in many diverse lines of investigation.     

Implications of thermal instability on HBT power amplifier reliability

Thermal stability is one of several important performance requirements for RF power amplifier modules used for cellular applications. In this work, the conditions for thermal instability in an HBT array for shared and individual ballast configurations are evaluated using experimental results from RF biased life test (RFHTOL) and ADS simulations. The instability is modest under nominal operating conditions, but becomes more severe at elevated temperatures which are frequently used in accelerated reliability tests such as RFHTOL. Thermally unstable power cells exhibit current crowding where one or two cells hog most of the current, resulting in localized hot spots from increased power dissipation density. This paper discusses the link between reliability failures during RFHTOL reliability testing and the thermal stability of HBT arrays used in a power amplifier. Shared ballast arrays are shown to be less thermally stable than individually ballasted arrays and thus have more failures during RFHTOL testing. Electro-thermal results indicate the layout aspects of power amplifier module also play an important role in determining junction temperatures for various stages.     

Performance comparison of wide bandgap semiconductor rf power devices

Impressive radio frequency power performance has been demonstrated by three radically different wide bandgap semiconductor power devices, SiC metal semiconductor field effect transistors (MESFETs), SiC static induction transistors (SITs), and AlGaN heterojunction field effect transistors (HFETs). AlGaN HFETs have achieved the highest f_max of 97 GHz. 4H-SiC MESFETs have achieved the highest power densities, 3.3 W/mm at 850 MHz (CW) and at 10 GHz (pulsed). 4H-SiC SITs have achieved the highest output power, 450 W (pulsed) at 600 MHz and 38 W (pulsed) at 3 GHz. Moreover, a one kilowatt, 600 MHz SiC power module containing four multi-cell SITs with a total source periphery of 94.5 cm has been demonstrated.     

Space and time resolved surface temperature distributions in Si power diodes operating under self-heating conditions

In order to optimize and improve the design of power devices with improved surge current safe operating area it is necessary to obtain a good correlation between measured and simulated space and time resolved temperature distributions. Therefore, an IR microscope capable of measuring the space and time resolved surface temperature distributions in Si power diodes operating under self-heating conditions has been developed. The minimum detectable spot size is 15 μm, while the signal rise time is detector limited to about 1 μs. The lower temperature detectivity limit is about 10°C over room temperature.

Using this instrument dynamic thermal phenomena in fast recovery 3.3 kV Si power diodes having radiation-induced recombination centers [Proceedings of the 7th EPE, Trondheim, 1997] subjected to 1.2 ms 400–2000 A/cm² and 0.3–2 ms 2000 A/cm² current pulses have been studied. The experimental results have been compared to results from 2D device simulations including surface recombination and carrier lifetime temperature dependence. The agreement between experimental and device simulation results (i.e. dynamic IV characteristics and time and space resolved temperature distributions) is very good up to a peak current density of 1500 A/cm², and a reasonable good one for peak current densities up to 2000 A/cm² (1.2 ms current pulses).     

覆有BST膜的半导体功率器件结终端研究

通过一系列的工艺步骤,在半导体功率器件含有场限环(FLR)的结终端上覆盖了一层300 nm厚、介电常数高的钛酸锶钡( BST)膜.对该新型结终端和无BST膜的传统FLR结终端的结构与性能进行了研究比较.结果表明,在覆盖BST膜后,FRL结终端的结构击穿电压提高了50％.这证明BST膜能够提高器件的击穿电压.     

高压大功率IGBT元器件开关特性的分析研究

自从IGBT器件出现之后,大量的研究人员对IGBT器件的开关特性进行了大量的研究,以便准确地预测和改善器件的开关瞬态特性.在实际应用中,IGBT器件的开关特性不仅和其物理结构、制作工艺以及工作的原理有着密切的关系,同时和其工作的环境也具有密切的关系.在IGBT器件工作的时候,常常受到驱动电压和电阻以及工作电压、集电极电流等的影响.因此研究工作环境对IGBT器件开关特性的影响,不断地改善其设计来优化其性能,成为研究的重点.论文详尽研究分析了功率器件IGBT的开关特性,对IGBT及其系统的理解、应用具有一定的指导意义.     

Time-dependent degradation due to negative bias temperature instability of p-MOSFET with an ultra-thin SiON gate dielectric

This paper presents the time-dependence of the negative bias temperature instability (NBTI) degradation of p-MOSFETs with an ultra-thin silicon oxynitride gate dielectric. The concentrations of nitrogen in the gate dielectric were approximately 3% and 10%. The device with 10% nitrogen concentration had unique time-dependent degradation characteristics due to the nitrogen enhanced NBTI effect. It degraded significantly just after application of an NBTI stress. After this initial degradation, a fast and slow degradation followed in sequence. The initial, fast, and slow degradations appear to be associated with the deep donor effect of nitrogen, the diffusion of ionic and neutral hydrogen combined with Si-H bond breaking, and the diffusion of neutral hydrogen combined with O-H bond breaking, respectively. Owing to the slow down of the NBTI degradation after the initial and fast degradations, the lifetime for the device with 10% nitrogen concentration was three times longer than that with 3% nitrogen concentration.     

MCM热分析和热设计技术

多芯式组件以及其它高功率器件的热分析和热设计技术，是微电子设备可靠性设计的主要技术，文中论述了多芯片组件热分析和热设计的方法，并介绍了这一领域的最新发展动态。     

温度场监控下高功率半导体激光熔敷钴基合金涂层

采用3.5 kW半导体激光器在42CrMo4表面熔覆了钴基合金(Stellite 6)涂层,利用光学显微镜和显微硬度仪表征了涂层的微观组织和硬度分布,研究了监控熔覆过程中的熔池温度场对涂层的微观结构和显微硬度的影响.结果表明:基于熔池温度场拍摄并调整激光器输出功率的熔池大小闭环监控的工艺可实现对钴基合金涂层的稀释率以及结构与性能的调控:当送粉量为22.6 g/min、熔覆速率为1 m/min时,基于熔池温度场监控的工艺调整实现了近零稀释率的钴基合金涂层的熔覆,所需激光功率仅为1.5 kW;涂层与基体形成良好的冶金结合,组织致密,主要由平面晶、胞状晶、树枝晶和等轴晶构成,晶粒细小,显微硬度达到HV600.     

Dynamic surface temperature measurements in SiC epitaxial power diodes performed under single-pulse self-heating conditions

Semiconductor devices development, design and optimization require the use of computer simulation tools able to predict the entire device safe operating area (SOA), something that it is not always possible due to limitations in some of the physical models in predicting certain properties of device operation under extreme conditions (i.e. high carrier injection levels and high temperature). In order to improve our understanding of device operation under these extreme conditions experimental data of the dynamic IV characteristics and temperature time evolution and space distribution are required. The experimental data obtained are then used in the development of improved physical models and simulation tools.

In this work, dynamic surface temperature measurements as a function of current pulse peak density and length were performed on SiC-PiN epitaxial power diodes. The measurements were carried out using an infrared (IR) microscope developed in our lab capable of measuring space and time surface temperature distributions in semiconductor devices operating under self-heating conditions [Solid State Electron 2001;45(12):2057]. The minimum detected spot size is 15 μm, while the signal raising time is detector limited to about 1 μs. The lowest detectable temperature increment is at least 10 °C over room temperature.

Using this instrument, dynamic thermal phenomena in 4.5 kV SiC-PiN epitaxial power diodes [Mater Sci Forum 2001;353–356:727] subjected to 1 ms long 100–6000 A/cm² and 0.1–5 ms long 3000 A/cm² current pulses have been studied. The possibility of obtaining dynamic surface temperature information from SiC electronic devices operating under self-heating conditions with time constants in the order of ms is demonstrated.     

Reliability and optical properties of LED lens plates under high temperature stress

In this investigation the thermal degradation mechanisms of Bisphenol A Polycarbonate (BPA-PC) plates at the temperature range 100–140 °C are studied. The BPA-PC plates are currently used both in light conversion carriers in LED modules and optical lenses in LED-based products. In this study BPA-PC plates are aged at elevated temperature of 100–140 °C for a period up to 3000 h. Optical and chemical properties of the thermally-aged plates were studied using UV–Vis spectrophotometer, FTIR–ATR spectrometer, and integrated sphere. The results show that increasing the thermal ageing time leads to yellowing, loss of optical properties, and decrease of the light transmission and of the relative radiant power value of BPA-PC plates. The results also depict that there is not much discoloration within the first 1500 h of thermal ageing. The rate of yellowing significantly increases at the end of this induction period. Formation of oxidation products is identified as the main mechanism of yellowing. An exponential-based reliability model is also presented to calculate the rate of degradation reaction and to predict the life-time of BPA-PC plates.     

新型功率MOS器件的结构与性能特点

电力电子器件的结构决定其性能,而器件的性能又决定电路的性能。根据此原理,分析比较了近十年来10种实用的具有新结构的功率MOS器件的结构与性能特点。     

Thermal resistance degradation of surface mounted power devices during thermal cycling

Backside scanning acoustic tomography (SCAT) images have been correlated to alloy morphology (cross-section) and composition data (stoichiometry) to model the Θ_JC degradation for surface mounted device packaged power ICs as a function of the temperature cycling range. We find that an appropriate setting of the die attach process can suppress needle-shaped Cu₃Sn in favor of roughly spheroid Cu₆Sn₅. We derived, from the degradation of the Θ_JC during thermal cycling stress tests with different temperature swings, an acceleration factor with the use of the Coffin–Manson law. The fit parameter q in this formula is 9.3 for the new improved setting of the die attach process when the high SO power (HSOP) package is used. The moisture sensitivity level has no significant influence. Finally, a maximum Θ_JC degradation of 0.33 K/W based on the normal distribution approach results in a minimum lifetime of 12 years. When a customer requires a maximum Θ_JC of 2.0 K/W at the end of life, 50 years can be guaranteed.     

Design,development and reliability testing of a low power bridge-type micromachined hotplate

In this paper, the development and reliability of a platinum-based microheater with low power consumption are demonstrated. The microheater is fabricated on a thin SiO₂ bridge-type suspended membrane supported by four arms. The structure consists of a 0.6 μm-thick SiO₂ membrane of size 50 μm × 50 μm over which a platinum resistor is laid out. The simulation of the structure was carried out using MEMS-CAD Tool COVENTORWARE. The platinum resistor of 31.0 Ω is fabricated on SiO₂ membrane using lift-off technique. The bulk micromachining technique is used to create the suspended SiO₂ membrane. The temperature coefficient of resistance (TCR) of platinum used for temperature estimation of the hotplate is measured and found to be 2.2 × 10⁻³/°C. The test results indicate that the microhotplate consumes only 11.8 mW when heated up to 400 °C. For reliability testing, the hotplate is continuously operated at higher temperatures. It was found that at 404 °C, 508 °C and 595 °C, the microhotplate continuously operated up to 16.5 h, 4.3 h and 4 min respectively without degrading its performance. It can sustain at least 53 cycles pulse-mode of operation at 540 °C with ultra-low resistance and temperature drifts. The structure has maximum current capability of 19.06 mA and it can also sustain the ultrasonic vibration at least for 30 min without any damage.     

探究电力电子器件及其应用的现状和发展

电力电子器件随着我国经济的发展与社会的进步已经在众多领域中进行了应用.本文主要就电力电子器件应用的现状、应用中存在的问题、未来发展的趋势三个方面的内容进行论述.     

谐波对电能计量的影响及计量装置的探究

本文分析了电力系统中谐波的产生原因对电能计量的影响,重点就感应式和电子式两种计量装置的电能计量结构、计量原理以及计量误差进行了对比分析和研究。     

脉冲功率电源中浪涌电流与电压的分析及抑制

针对功率脉冲电路放电过程中存在的电流和电压冲击问题,建立了电路的分布参数模型和二极管的PSPICE模型。分析了放电过程中的浪涌电流和电压的产生的机理,采用PSPICE软件对电路放电的瞬态过程进行了仿真,提出了抑制浪涌电流和电压冲击的方法。仿真结果表明:适当增加二极管回路的阻尼电阻,可以降低或消除浪涌电流;在二极管两端并上适当的电阻,可以降低浪涌电压。