Cu/Sn等温凝固芯片键合工艺研究

Study of die bonding technology for Cu /Sn isothermal solidification

研究了Cu/Sn等温凝固芯片键合工艺,对等离子体处理、键合气氛、压力以及Sn层厚度等因素对焊层的键合强度的影响进行了分析和优化。实验表明,等离子体处理过程的引入是保证键合质量的重要因素,在功率500W、时间200s的处理条件下,得到了最大的键合强度;而键合气氛对键合质量有显著的影响,在真空环境下,能得到最佳的键合质量;压力对键合质量的影响较小,施加较小的压力(0.05MPa)即能得到较大的剪切强度;而Sn层厚度对键合质量的影响极小,而较薄的厚度能够缩短键合时间。在最优化条件下,得到的键合强度值全部达到了美军标规定的6.25MPa的强度要求(对于2mm×2mm芯片)。

A new die bonding technique based on Cu /Sn isothermal solidification wa s studied.The pro -cess and materials parameters such a s plasma treatment,bonding environ ment,load and thickness of the Sn layer were evaluated.Plasma treatm ent is the key of the whole process.Af ter optimization,the power of plasma treatment was set at 500W and t he dwell time was fixed to 200s.The bonding environment plays an important role and the results show u nder vacuum environment the bonding strength of the sample is larger than those under other environments.The bonding strength is competitiv e under the load of 0.05MPa.The samples with the thickness of 2μm and 4μm show nearly the same performance under the shear test.With the optimized condition,the bonds can pass the shear strength test s pecified by MIL STD 883E.Method 2019.5which requests 6.25MP a as minimum strength for the chip of 2mm ×2mm.