Atomic and Electronic Design ob Ceramic/Metal Interfaces

采用基于密度泛函理论的第一性原理分子动力学方法研究了金属-陶瓷界面的粘接能和原子/电子结构。这项调查是在大内教授和小山博士的密切合作下进行的。本研究最重要的发现是，在SiC（110）和SiC（100）与Al成键的情况下，在键界面中存在很强的吸引C-Al相互作用，同时具有离子和共价特征，这被认为对SiC与Al之间的粘附起着有利的作用。这些理论结果被suga教授的成键实验所证实。利用表面活化键合方法，成功地在室温下完成了陶瓷-金属体系的键合。从去年开始对结合界面的微观结构进行的TEM研究表明，这种陶瓷-金属界面的直接结合实际上只有在这种清洁表面之间的接触才能形成。然而，利用高分辨率透射电镜对Al2O3和Al之间的键合界面进行了更仔细的观察，发现存在一个几纳米厚的强畸变区，该区域具有不同于Al2O3和Al的另一种结构。这种薄中间层的形成可以解释为接触界面的强烈变形导致晶格失配补偿的结果。这些结果已被分析和汇编，以供界面工程的进一步发展，并在几个国际会议上发表。此外，这些发现的可能性在包装技术的应用，在不久的将来已经讨论了相当好的期望。

Adhesive energies and atomic/electronic structure of metal to ceramic interfaces have been investigated by using the first principle molecular dynamics method based on the density-function theory. This investigation have been conducted through the tight collaboration between Prof.Ohuchi and Dr.Kohyama. The most important finding of the research was that in case of SiC (110) and SiC (100) and Al bonding, there is a strong attractive C-Al interactions with both ionic and covalent characters in the bonded interface, which are considered to play a favorable role in adhesion between SiC and Al. These theoretical results are confirmed by the bonding experiments conducted by Prof.Suga. By means of the surface activated bonding method, he has succeeded in bonding ceramic-metal system at room temperature. TEM study on the microstructure of the bonded interfaces, which has been continued since the last year, showed that a direct bonding of such ceramic-metal interface is formed actually only by contact between such clean surfaces. However, a closer observation of the bonded interface between Al2O3 and Al using the high resolution TEM showed that there is a strong distorted region of several nm thickness which possesses another structure which is different from both Al2O3 and Al. Formtion of such thin intermediate layr was interpreted as a result of strong deformation of the interfaces in contac that would lead to compensate the lattice mismatch. There results have been analyzed and complied for further development of interface engineering, and published in several international conferences. Also possibilities of these findings in application of the packaging technology in the near future has been discussed with fairly good expectations.