Analysis of Heat Transfer Process of Plug Formation for VLSI by Laser Radiation

为提高超大规模集成电路激光辐射成塞的可靠性，对激光熔化金属和熔融金属流动凝固两个过程进行了理论分析和实验研究。得到了以下结果：作为第一个过程的模型，开顶式矩形凹坑中的冰(辐射能量的半透明材料)在上方热源的辐射下融化，凹坑的尺寸足够大，可以忽略表面张力的影响。并对该模型进行了分析和实验。通过分析结果与实验结果的比较，验证了本文分析方法的有效性。分析了热源黑体温度、基板材料、冰中气泡和基板热状态对第一种工艺的影响。第二种工艺以具有微小孔洞的纯金属为模型，用激光从上方熔化，熔体进入孔洞后凝固，孔洞尺寸很小，需要考虑金属熔体的表面张力。并对该模型进行了分析和实验。分析结果与实验结果的对比表明，本文的分析方法可以定性地模拟第二个过程。此外，对实际孔洞尺寸和时间尺度的分析结果显示了金属从熔化到凝固的瞬时行为。结果表明，金属熔体流入微孔的主要原因是表面张力。

In order to get basic Knowledge for improving reliability of plug formation for VLSI by a Laser radiation, the two processes that a metal was melted by the laser radiation, and the molten metal flowed and solidified, were investigated analytically and experimentally. The following results were obtained.As a model of the first process, ice (semitransparent material for radiation energy) in an open-top rectangular dimple in a substrate was melted by radiation of a heat source from above, where the size of the dimple was large enough to neglect the effect of surface tension. The analysis and the experiment for the model were made. From the comparison of analytical results with experimental results, the effectiveness of the present analysis was shown. Besides, the influences of blackbody temperature of heat source, the material of the substrate, air bubbles in ice and thermal condition of the substrate on the first process were clarified.As a model of the second process, a pure metal with a microscopic hole was melted by laser radiation from above and the molten metal flowed into the hole and then solidified, where the size of the hole was so small that the surface tension of the molten metal had to be considered. The analysis and experiment for the model were made. From the comparison of analytical results with experimental results, it was clarified that the present analysis could qualitatively simulate the second process. Besides, the results of the analysis performed for the practical hole size and time scale, showed transient behavior of metal from melting to solidification. It was clarified that surface tension mainly governed the phenomenon that molten metal flowed into the microscopic hole.