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

在明斯特大学新成立的合作研究中心（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响应和适应刺激并显示记忆能力的物质。除了开关分子和软物质，固态材料也在探索中。在这里，所谓的相变材料（PCM）特别重要。PCM通常含有锗、锑、碲，并且通常含有额外的化学元素。这些合金在其非晶态和晶态之间的电学和光学性质上表现出明显的对比。由于这些状态之间的光或电诱导跃迁可以非常快，即在纳秒内完成，PCM是适用于电子和光子硬件的新兴存储器的优秀候选者。然而，它们在设备中的集成具有挑战性。PCM必须在清洁的条件下沉积，因为外来物种的污染会显著改变它们的特性。此外，PCM薄膜一旦沉积就必须由电介质覆盖层保护，以防止氧化并在操作期间提供机械支撑。 在上述研究项目中，还需要介电体用于集成光子元件和作为钝化。理想地，沉积的介电层表现出最佳的性质，例如低光损耗、低应变、高密度和机械鲁棒性。与磁控溅射相比，离子束沉积允许在较低的压力下沉积，并独立调整工艺参数，如离子能量和通量。因此，该方法被广泛用于高质量的光学涂层和所述应用的理想技术。电子束光刻的器件电极、电波导、接触垫和标记结构都需要金属。在电相变装置中，高熔点金属如铂和特别是钨是有用的，因为它们抵抗与PCM的混合。对于钨的电子束蒸发，高功率和腔室壁的冷却是必要的。具有用于相变材料、金属和金属的专用沉积室的UHV集群工具，每个沉积室都具有最合适的沉积技术，将允许用于各种目的的材料组合，而不会损害工艺的清洁度和相应的结果。由于该沉积系统将在明斯特纳米工厂（MNF）的框架内运行，因此将可供CRC 1459“智能物质”及其他领域的大量用户使用。

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.