高温大功率半导体器件的超声辅助纳米银低温快速烧结机理与工艺研究

In order to realize the contradiction of low manufacturing process temperature and high operational temperature for high temperature and power semiconductor power devices, traditional low melting temperature assembly material cannot endure the high operational temperature of high power electronics. Nano silver paste can realize low-temperature sintering, the formation of bulk silver with high melting point can meet the requirements as above. Additionally, with respect to the challenges on low temperature, low pressure and fast sintering process compared with current Ag NPs sintering methods, this project proposes a novel ultrasonic assisted nano silver sintering method based on the characteristics of ultrasonic energy, softening and spreading activation of crystal material. In particular, this proposal will focus on ultrasonic study of ultrasound in ultrasonic hot head / chip / nano silver layer / substrate interface between the efficient transmission model, surface coated silver nanoparticles organic matter removal mechanism of organic residues on silver nanoparticles, interfacial atomic diffusion process of ultrasonic thermo mechanical coupling for nano silver sintering process evolution mechanism, in order to obtain ultrasonic assisted nano silver sintering mechanism and realize low temperature and fast sintering of nano silver and laboratory the prototype of ultrasonic sintering equipment. Above all, this project is dedicated for a feasible packaging technique and process towards the wide application of high power semiconductor devices.

为了实现高温大功率半导体器件的低制造工艺温度和高服役温度的矛盾，传统低熔点焊接材料无法承受器件高服役温度，纳米银可以实现低温烧结，获得高熔点的银结构，满足大功率半导体器件的高温服役要求。另外，针对目前纳米银烧结互连技术在实现低温、低压和快速烧结方面的挑战，根据超声能高效软化效应、激活金属晶体材料原子扩散的特点，本项目提出一种利用超声辅助的纳米银热压烧结方法，研究超声在超声热压头/芯片/纳米银层/基板多接触界面间的高效传播模式、纳米银颗粒表面包裹有机物的超声去除机制，纳米银有机物残留对界面原子扩散过程的影响、超声-热-力耦合作用下纳米银烧结过程的演变机制等，以期获得超声辅助纳米银烧结机理、实现低温快速纳米银烧结新工艺和实验室原型超声烧结装备，最终为大功率半导体器件封装提供可行的技术和工艺方法。

针对传统焊接材料熔点低无法满足大功率半导体器件服役节点温度高的难题，以及目前大功率半导体器件封装的烧结互连技术在实现低温、低压和快速方面的挑战，本项目提出了一种利用超声辅助的纳米银热压烧结方法，获得了纳米银导电浆料的配置方法，实现了热压烧结平台引入超声驱动系统的集成，揭示了超声辅助热压烧结机制，发现了超声能高效软化效应、激活金属晶体材料原子扩散的特点，能够快速实现具有电学性能改善的致密烧结结构，对功率电子器件封装工艺具有借鉴价值。此外，本项目进一步研究了纳米颗粒烧结结构的微区热传输行为，发现了金属薄膜热物性具有显著的尺度效应，同时阐述了微区界面热阻的影响机制，发现了界面的状态、温度、应变状态等对界面热输运能力具有重要的影响，这些结果对含有多材料、多界面的功率电子封装结构热可靠性分析具有价值。