Polishing Glass-Ceramics with Ceria

数据存储容量的戏剧性增长改变了我们使用计算机的方式。与当前的铝基技术相比，陶瓷盘片具有显著的优势。它们更坚硬，但仍然很轻，可以更快地旋转，或者简单地移动，而不会增加垂直于盘片的波动，这会导致磁头碰撞和驱动器故障。玻璃盘子现在正在生产中，但微晶玻璃盘子将提供更好的性能。抛光陶瓷盘片是困难的，因为材料是硬的，就微晶玻璃而言，它在化学上是不均匀的。化学机械抛光(CMP)涉及在不造成亚表面损伤的情况下在表面上破碎材料，并使表面平滑，以产生比抛光介质中的颗粒大小平滑100倍的抛光效果。目前，CeO2抛光玻璃的效果最好，不是因为它特别硬，而是因为它提供了硬度和化学成分的最佳组合。众所周知，接触点的化学反应是一个关键因素--CeO2抛光总是涉及到水。抛光微晶玻璃的方法仍在开发中，氧化铈是主要的候选方法。在这个项目中，学生使用尖端技术，包括电子显微镜、原子力显微镜和近原子尺度的光谱学。他们将化学和力学方面的训练应用到当今的关键技术中。事实上，器件制造的许多方面都涉及到制造光滑的平面。例如，在制造多层芯片的同时，化学机械抛光也被用来平面化各层，并为优化互连准备光纤端部。在新的高速硬盘驱动器中，支撑磁存储介质的玻璃盘必须抛光得非常平，以至于在三英寸的磁盘上，凸起的原子高度小于10‘S；这与美国的光滑相提并论，因此没有一座山高于几英寸！抛光已经发展成为一种艺术，但我们现在需要理解科学，并训练学生在艺术和科学方面。我们的计划解决了两个问题：缺乏基本知识，缺乏了解化学机械抛光的艺术和科学的训练有素的科学家。这个项目向材料科学的学生展示了为什么他们需要那些化学、机械工程和电气工程的基础课程，以及这些学科如何在工业环境中结合起来，不仅是为了这个项目，也是为了化学机械加工的许多应用。我们的跨学科研究项目汇集了来自不同学科的不同的研究生和本科生。学生们与我们的工业同行见面，并参观使用这项技术的公司。了解化学机械抛光并能更充分地利用最先进的仪器的熟练科学家是工业工作场所的国家需求。

Dramatic increases in data-storage capacity have changed how we use computers. Ceramic platters offer significant advantages over current Aluminum-based technology. They are more rigid, while still light, and can be rotated faster, or simply moved, without increased fluctuations normal to the platter that would cause a head crash and drive failure. Glass platters are now in production but glass-ceramic platters would offer even greater performance. Polishing ceramic platters is difficult because the material is hard, and in the case of glass-ceramics, it is chemically inhomogeneous. Chemical-mechanical polishing (CMP) involves fracturing the material at the surface while not creating subsurface damage and smoothing the surface to produce a finish that is 100 times smoother than the size of the particles in the polishing medium. Ceria currently give the best results when polishing glass, not because it is particularly hard, but because it gives the best combination of hardness and chemistry. It is known that the chemistry at the point of contact is a critical factor-ceria polishing always involves water. Methods for polishing glass-ceramics are still being developed with ceria being the primary candidate. In this program, students work with cutting-edge techniques including electron microscopy, atomic-force microscopy and spectroscopy at the near-atomic scale. They apply their training in chemistry and mechanics to today's critical technology.Actually, there are many aspects of device fabrication which involve producing a smooth flat surface. For example, CMP is also used to planarize layers while building multilayer chips and to prepare the ends of optical fibers for optimizing interconnections. In the new high-speed hard-drives, the glass platters which support the magnetic storage media must be polished so flat that bumps are less than 10's of atoms high on a three-inch disk; compare this to smoothing the USA so no hill is higher than a few inches! Polishing has developed as an art but we need now to understand the science and to train students in both the art and the science. Our program addresses two problems: a lack of basic knowledge and the shortage of trained scientists who understand the art and science of CMP. This project shows students in materials science why they need those basic courses in chemistry, mechanical engineering and electrical engineering and how these disciplines combine in an industrial setting, not just for this project but for many applications of CMP. Our interdisciplinary research program brings together a diverse group of graduate and undergraduate students from different disciplines. The students meet our industrial colleagues, and visit the companies working with this technology. Skilled scientists who understand CMP and can fuller utilize the state-of-the-art instrumentation are a national need in the industrial workplace.