环扫电镜表征影响因素及芯片失效分析应用

对环境扫描电镜(ESEM)表征影响因素进行试验研究,根据半导体芯片的结构,进行成像参数优化,试验结果表明较为适合的优化参数为:腔室气压40Pa~80Pa,加速电压10kV~20kV.研究了裙散效应对能谱分析的影响,结果表明非分析区域元素含量与离能谱分析点的距离呈幂函数衰减,应证了文献报道的理论计算,对于能谱分析排除干扰元素有一定的参考意义.针对破坏性物理分析(DPA)试验中发现的塑封器件腐蚀缺陷,利用ESEM在优化参数下进行机理分析,结果表明玻璃钝化层裂纹是导致铝金属条被腐蚀的原因,而玻璃钝化层裂纹是由于器件材料性质不匹配,在热载荷条件下产生热应力而引起.这种表层缺陷极有可能因为镀膜而被掩盖,因此,利用ESEM检测半导体器件具有一定的必要性.

Influencing factors of environmental scanning electron microscopy characterization and application of chip failure analysis

Influencing factors of ESEM characterization were studied by testing. Imaging parameters were optimized on the basis of the structure of semiconductor chip, and the results showed that the suitable chamber pressure and acceleration voltage respectively were 40~80 Pa and 10~20 kV, respectively. Skirting effect on energy disperse spectrum analysis was studied. The results showed that content of elements in non-analyzed areas decreased by the power function related to distance with center of electron beam spot, which was areference for distinguishing interferential elements and confirmed the theory of some other researches. Corrosion defects of plastic packaging devices was tested by destructive physics analysis( DPA) , and the mechanism of defects was analyzed by optimizing parameters of ESEM. The results showed that cracks of glassivation layer, which resulted from thermal stress in thermal loading for mismatch between property of different materials, was the reason of corrosion of Al metal layer. Defects of surface layer are easy to be covered by coating, so it is necessary to use ESEM to test semiconductor devices.