SiC功率器件先进互连工艺研究

Research on advanced interconnection processes for SiC power device

针对SiC功率器件封装的高性能和高可靠性要求,文章研究了芯片双面银烧结技术与粗铜线超声键合技术的高可靠性先进互连工艺。通过系列质量评估与测试方法对比分析了不同烧结工艺对芯片双面银烧结层和芯片剪切强度的影响,分析了衬板表面材料对铜线键合强度的影响,最后对试制样品进行温度冲击测试,讨论了温度冲击对银烧结显微组织及其剪切强度的影响,以及对铜线键合强度的影响。试验结果表明:一次烧结工艺与分次烧结工艺的芯片剪切强度均达到了工业生产要求的标准值,但分次烧结工艺的银烧结效果在组织结构和芯片剪切强度上都要优于一次烧结工艺;温度冲击测试后烧结银显微组织的烧结颈增大,孔隙增大,并且2种烧结工艺的芯片剪切强度都明显增大。衬板材质对铜线超声键合强度有很大影响,在裸铜活性金属钎焊(Active Metal Braze,AMB)上的键合性能表现出更好的力学性能,温度冲击后裸铜AMB上的键合点力学性能会退化,但镀银AMB上的力学性能反而会增强;结合拉力测试后第二键合点的断裂模式,温度冲击使裸铜AMB上键合点的断裂模式从100%颈部断裂转向焊点脱落,而使镀银AMB上的焊点脱落逐渐减少。

To meet the high requirements for performance and reliability in packaging silicon carbide(SiC)power devices,this paper focused on studying relevant advanced interconnection processes,specifically double-side silver sintering technology for chip and thick copper wire ultrasonic bonding technology.Through a series of quality evaluations and tests,a comparative analysis was conducted regarding the influence of different sintering processes on double-side silver sintering layers for chip and chip shear strength,and the effect of lining plate surface materials on copper wire bonding strength.In addition,temperature shock tests were conducted on the samples,to investigate the influence of temperature shock on silver sintering in terms of microstructure and shear strength,as well as the copper wire bonding strength.The experimental results show that both the single-sintering process and multiple-sintering process achieve chip shear strength standard values that meet industrial production requirements,but the multiple-sintering process exhibits superior silver sintering effects in terms of structure and chip shear strength.Under temperature shock conditions,the sintering silver displays expanded necks and pores in the microstructure,and both sintering processes produce a significant increase in chip shear strength.Moreover,the choice of lining plate material significantly influences the copper wire ultrasonic bonding strength.Although bonds on bare copper active metal braze(AMB)exhibit better mechanical properties compared to silver-plated AMB,the former deteriorates in mechanical properties under the effect of temperature shock,while the mechanical properties of the latter are enhanced.Taking into account the fracture modes shown at the second bond after the pull test,temperature shock contributes to shifting the fracture mode of bonds on bare copper AMB from 100%neck fracture to welding spot drop,while a gradual decrease in welding spot drop for silver-plated AMB.