单晶硅低温连接的表面预共晶法研究

Low Temperature Joining Single-Crystal Silicon by Pre-Eutectic Joining

摘要:

用共晶连接与表面预共晶法连接相比较的方法，对单晶硅连接进行了实验研究和理论分析。结果表明，在保温30 min的条件下，共晶连接与表面预共晶法实现可靠连接的最低温度分别为600与430 ℃。热力学分析表明，共晶连接过程中，连接界面区域Au、Si向Au或Si基过饱和固溶体转变是共晶液相形成的主要阻力；表面预共晶法连接前，单晶硅待连接面上预制了Au-Si共晶熔敷层，且熔敷层内及其与单晶硅界面区域存在因Au、Si相分离不完全而产生的过饱和固溶体，因此，连接过程中Au-Si的二次共晶液化不存在上述阻力，且获得了过饱和固溶体向共晶液相转变时体系吉布斯自由能减小的动力，所以，二次共晶液相更易产生，连接温度有效降低。

Abstract:

An experimental and theoretical study of single-crystal silicon joining was undertaken by the comparison of two joining methods of eutectic joining and pre-eutectic joining. The results indicate that when holding for 30 min, the lowest joining temperatures for eutectic and pre-eutectic joining are 600 oC and 430 oC, respectively. Thermodynamic analysis shows that during the eutectic joining, the main resistance to the eutectic liquid formation is the transformation from Au and Si to Au or Si base supersaturated solid solutions (SSS). However, cladding of Au-Si eutectic layer is prefabricated in the surface to be joined by pre-eutectic joining. Since separation between Au and Si is insufficient during the cladding cooling, the supersaturate solid solution (SSS) exists inside the cladding and around the cladding/substrate interface. As a result, the re-eutectic of Au-Si during the pre-eutectic joining process is not impeded by the above-mentioned resistance, but promoted by the Gibbs free energy decrease induced by the transformation from the SSS to eutectic liquid. Therefore, the re-eutectic liquid is more prone to appear, and the joining temperature is observably reduced.