光电耦合器件低频噪声特性与可靠性老化研究

在宽的输入偏置电流范围条件下,开展了光电耦合器件低频噪声特性测试与功率老化和高温老化的可靠性试验研究。结果表明,光电耦合器件的低频噪声主要是内部光敏晶体管1/f噪声,并随输入偏置电流的增大呈现先增大后减小的规律,这与器件的工作状态密切相关。功率老化试验后,高输入偏置电流条件下的低频噪声有所增大,这归因于电应力诱发的有源区缺陷。高温老化试验后,整个器件线性工作区条件下的低频噪声都明显增大,说明温度应力能够更多地激发器件内部的缺陷。相对于1/f噪声幅度参量,低频噪声宽带噪声电压参量可以更灵敏准确地进行器件可靠性表征。     

Improved mobility of AIGaN channel heterojunction material using an AIGaN/GaN composite buffer layer

The quality of an A1GaN channel heterojunction on a sapphire substrate is massively improved by using an A1- GaN/GaN composite buffer layer. We demonstrate an A10.4Gao.6N/AI0.18Ga0.82N heterojunction with a state-of-the-art mobility of 815 cm2/（V.s） and a sheet resistance of 890Ω/口 under room temperature. The crystalline quality and the electrical properties of the A1GaN heterojunction material are analyzed by atomic force microscopy, high-resolution X-ray diffraction, and van der Pauw Hall and capacitance-voltage （C-V） measurements. The results indicate that the improved electrical properties should derive from the reduced surface roughness and low dislocation density.     

Superior material qualities and transport properties of InGaN channel heterostructure grown by pulsed metal organic chemical vapor deposition

Pulsed metal organic chemical vapor deposition is introduced into the growth of In Ga N channel heterostructure for improving material qualities and transport properties. High-resolution transmission electron microscopy imaging shows the phase separation free In Ga N channel with smooth and abrupt interface. A very high two-dimensional electron gas density of approximately 1.85 × 1013cm-2is obtained due to the superior carrier confinement. In addition, the Hall mobility reaches 967 cm2/V·s, owing to the suppression of interface roughness scattering. Furthermore, temperature-dependent Hall measurement results show that In Ga N channel heterostructure possesses a steady two-dimensional electron gas density over the tested temperature range, and has superior transport properties at elevated temperatures compared with the traditional Ga N channel heterostructure. The gratifying results imply that In Ga N channel heterostructure grown by pulsed metal organic chemical vapor deposition is a promising candidate for microwave power devices.     

MLCC产业现状及质量分析

随着多层陶瓷电容器（MLCC）制造工艺和技术的不断发展,MLCC对质量可靠性的要求也在不断地提高。随着5G、新能源汽车和通信等行业对集成电路的需求的增大,MLCC的市场规模将会进一步地提升,技术发展也会更加的多元和多样化。对目前MLCC存在的主要失效模式、失效机理和质量问题进行了梳理,对今后提高MLCC的可靠性和质量具有重要的意义。     

Improved mobility of AlGaN channel heterojunction material using an AlGaN/GaN composite buffer layer

The quality of an AlGaN channel heterojunction on a sapphire substrate is massively improved by using an AlGaN/GaN composite buffer layer. We demonstrate an Al0.4Ga0.6N/Al0.18Ga0.82N heterojunction with a state-of-the-art mobility of 815 cm2/(V·s) and a sheet resistance of 890Ω/ under room temperature. The crystalline quality and the electrical properties of the AlGaN heterojunction material are analyzed by atomic force microscopy, high-resolution X-ray diffraction, and van der Pauw Hall and capacitance–voltage(C–V) measurements. The results indicate that the improved electrical properties should derive from the reduced surface roughness and low dislocation density.     

微型化器件中多晶Cu晶向排布对其受压力学特性的影响仿真研究

为系统研究多晶Cu材料晶向排布对其受压力学特性的影响,通过采用晶体塑性有限元的方法模拟了不同晶向Cu的纳米压痕试验过程。仿真结果表明,从受力变形特点来看,当载荷为几何对称压入时,对称于压入面的两对滑移系呈现对称滑移,对应于各个方向的滑移系产生的塑性变形也呈现对称分布;当压入模式为非对称压入时,不同滑移面的各个滑移系产生的塑性应变均不对称;从受力响应来看,压入方向越趋向于垂直于密排面{111},压入载荷水平越高,在压入深度从100 nm增加至500 nm过程中,伴随压入方向与密排面夹角从0°增加至54.732°,压入载荷从5.090 mN增加至5.674 mN。上述结论对Cu晶向择优和微互连设计具有重要的指导意义,有利于微互连结构可靠性的提升。     

电子产品可靠性评价与物理模型应用探讨

该文以电子产品的故障为出发点,从集成电路-封装、集成电路-芯片、电路板(或线路板)、电子元件、系统和多系统的角度论述了不同任务环境下电子器件的故障机理特点。系统论述了故障模式、影响及危害性分析(FMECA)和故障模式、机理与影响分析(FMMEA)两种故障机理分析方法,同时结合低周疲劳、高周疲劳、裂纹萌生、反应论模型、芯片失效等失效机理对故障物理元模型进行分类讨论,对电子产品可靠性评价与物理模型应用进行了系统的探讨,为电子产品可靠性评价及失效物理评估模型的选取提供了依据。     

固态微波器件防自激测试夹具研究北大核心CSCD

固态微波器件能够实现微波功率的发射、放大、控制和接收,在移动通讯、雷达等领域有着重要的应用。但是固态微波器件在实际测试中易发生自激振荡,影响其正常工作,甚至会造成永久性的损坏。而良好的测试夹具设计可以有效防止自激振荡现象的发生。因此本文通过分析固态微波器件自激振荡的产生机理,研究制定自激振荡的有效消除措施,提出了固态微波器件防自激测试夹具设计准则,并选取典型GaN微波功率晶体管开展夹具研制加以验证。器件多次重复测试均未发生自激振荡,而且测试结果一致性较好,表明形成的固态微波器件防自激测试夹具设计准则合理可行,能够有助于实现固态微波器件性能参数的精确测试,支撑研制单位的工艺改进和质量提升。