UHV cluster tool for deposition of phase change materials, dielectrics, and metals

在明斯特大学新成立的协作研究中心(CRC)1459“智能物质”中，物理学家、化学家、生物学家和计算机科学家研究对刺激做出反应和适应并显示记忆能力的物质。除了开关分子和软物质外，还探索了固态材料。在这里，所谓的相变材料(PCM)尤为重要。相变材料通常含有Ge、Sb、Te，通常还有其他化学元素。这些合金在非晶态和晶态之间的电学和光学性质上表现出明显的反差。由于这些状态之间的光或电诱导转换可以非常快，即在纳秒内完成，因此PCM是应用于电子和光子硬件的新兴存储器的极佳候选者。然而，它们在设备中的集成是具有挑战性的。PCM必须存放在清洁的条件下，因为外来物种的污染会显著改变它们的性质。此外，PCM薄膜一旦沉积，必须用介电盖层保护，以防止氧化并在运行过程中提供机械支撑。在上述集成光子元件的研究项目中，也需要使用电介质作为钝化材料。理想情况下，沉积的介电层具有最佳的性能，如低光学损耗、低应变、高密度和机械坚固性。与磁控溅射相比，离子束沉积允许在较低的气压下沉积，并独立调整离子能量和通量等工艺参数。因此，该方法被广泛用于高质量的光学涂层，并且是用于所述应用的理想技术。电子束光刻的器件电极、电波导管、触点焊盘和标记结构都需要金属。在电子相变设备中，高熔点的金属，如铂，特别是钨，是有用的，因为它们不会与相变材料混合。对于电子束蒸发钨来说，需要高功率和冷却腔壁。特高压组合工具具有用于相变材料、电介质和金属的专用沉积室，每个沉积室都具有最合适的沉积技术，可以将材料组合用于各种目的，而不会影响工艺和相应结果的清洁度。由于该沉积系统将在明斯特纳米加工设施(MNF)的框架内运行，因此它将在CRC1459“智能物质”和更高的范围内提供给大量用户。

In the newly established collaborative research center (CRC) 1459 “Intelligent Matter” at the University of Münster, physicists, chemists, biologists, and computer scientists investigate matter that responds and adapts to stimuli and shows memory capabilities. Besides switching molecules and soft matter also solid-state materials are explored. Here, so-called phase-change materials (PCMs) are of particular importance. PCMs usually contain germanium, antimony, tellurium, and often additional chemical elements. Those alloys exhibit a pronounced contrast in their electrical and optical properties between their amorphous and crystalline states. As optically or electrically induced transitions between these states can be extremely fast, i.e. completed within nanoseconds, PCMs are excellent candidates for emerging memories applicable in electronic and photonic hardware. However, their integration in devices is challenging. PCMs must be deposited under clean conditions because contamination with foreign species significantly alters their properties. In addition, thin films of PCM once deposited must be protected by a dielectric capping layer to prevent oxidation and to provide mechanical support during operation. Dielectrics are also required in the mentioned research projects for integrated photonic components and as passivation. Ideally, the deposited dielectric layers exhibit optimal properties such as low optical loss, low strain, high density, and mechanical robustness. Compared to magnetron sputtering, ion beam deposition allows deposition at lower pressures with independent tuning of process parameters like ion energy and flux. The method is therefore widely used for high-quality optical coatings and an ideal technique for the described applications. Metals are required for device electrodes, electrical waveguides, contact pads, and marker structures for electron-beam lithography. In electrical phase change devices, high-melting metals such as platinum and especially tungsten are useful, because they are resistant against mixing with the PCM. For electron-beam evaporation of tungsten, high power and cooling of the chamber walls is necessary. A UHV cluster tool with dedicated deposition chambers for phase-change materials, dielectrics, and metals, each with the most suitable deposition technique, will allow the combination of materials for a variety of purposes without compromising the cleanliness of the processes and the according outcome. As this deposition system will be operated in the framework of the Muenster Nanofabrication Facility (MNF), it will be available to a large number of users within the CRC 1459 “Intelligent Matter” and beyond.