LEAP-HI: Ultra-Low Power Computing: A Disruptive Approach Through a New Integrated Nanomechanics Framework

现代社会依赖于微电子计算设备。微处理器每秒执行数十亿次计算，使互联网、智能手机、笔记本电脑、云计算和数码相机成为可能。虽然微处理器在快速计算方面非常强大，但它们消耗大量能量。这是因为微处理器中的数十亿个晶体管变得如此之小，以至于它们即使关闭也会泄漏电流。新一代强大的计算硬件将需要更节能的微处理器。晶体管是没有活动部件的固态开关。这项美国繁荣、健康和基础设施（LEAP-HI）领先工程奖支持用纳米机械开关取代固态晶体管的基础研究，纳米机械开关可以打开和关闭，从而产生和断开电接触。这些触点可以以计算机的速度运行，因为它们的体积小得令人难以置信。纳米机械开关触点是在纳米牛顿力的作用下操作的。虽然很小，但实际的接触点——纳米级的凹凸不平——受到高应力和高电流密度的影响，产生了多种降解途径。金属材料被用来制造电触点，但它们最终是焊接在一起的。这项工作的目的是研究是否可以使用硬导电氧化物涂层在金属上克服这种粘附问题。这个项目的智力价值在于在力学、摩擦学和材料开发的交叉点上迎接一个巨大的挑战：开发界面系统，不仅要实现，而且要在数十亿到数万亿次接触循环后保持极低和稳定的粘附和电接触电阻，并且最小的退化。为了实现这一目标，研究团队将进行氧化物传导机制的密度泛函理论计算，以及接触应力的有限元和分子动力学建模。实验上，不同的氧化物将使用原子力显微镜进行测试。有前途的材料系统将被集成到纳米机械开关的原型中，它们的功能将被测试高达数万亿次的循环。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Modern society relies on microelectronic computing devices. Performing billions of calculations per second, microprocessors enable the internet, smart phones, laptop computers, cloud computing and digital cameras. Although microprocessors are extremely powerful when it comes to fast computation, they consume a lot of energy. This is because the billions of transistors in microprocessors have become so small that they leak electrical current even when they are off. New generations of powerful computing hardware will require more energy efficient microprocessors. Transistors are solid state switches with no moving parts. This Leading Engineering for America's Prosperity, Health, and Infrastructure (LEAP-HI) award supports fundamental research to replace solid state transistors with nanomechanical switches that can open and close to make and break an electrical contact. These contacts can operate at the speed of computers because of their incredibly small size. Nanomechanical switch contacts are operated with nanonewton forces applied normal to the interface. Though small, the actual points of contact - nanometer-scale asperities - are subject to both high stress and high current density, creating multiple degradation pathways. Metallic materials have been used to make the electrical contacts, but they eventually weld together. The objective of this work is to investigate whether hard conducting oxide coatings on the metals can be used to overcome this adhesion problem. The intellectual merit of this project is in meeting a grand challenge at the intersection of mechanics, tribology and materials development: to develop interfacial systems that not only achieve but maintain extremely low and stable adhesion and electrical contact resistance after billions to trillions of contact cycles with minimal degradation. To accomplish this, the research team will perform density functional theory calculations of oxide conduction mechanisms, and finite element and molecular dynamics modeling of contact stresses. Experimentally, different oxides will be tested using atomic force microscopy. Promising materials systems will be integrated into prototype nanomechanical switches, and their functionality will be tested up to trillions of cycles.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.