Collaborative Research: GOALI: Nonlinear Coupling in Pulsed Electronegative Plasmas: Multiple-sources, Multiple-frequencies, Multiple-time scales

合作研究：GOALI：脉冲电负性等离子体中的非线性耦合：多源、多频率、多时间尺度

• 批准号: 2010558
• 负责人: Walter Gekelman
• 金额: $ 49.73万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2010558&HistoricalAwards=false
• 关键词: Collaborative; Research; GOALI; Nonlinear; Coupling

Society critically depends on computers, cell phones and a myriad of specialized electrical circuits in nearly every technological product we use, from cars to door openers. What is not widely known is that these electrical circuits are largely contained in small semiconductor chips, that the dimensions of components of those circuits are approaching the size of atoms, and that the circuits are produced in machines containing the fourth state of matter – plasma. Plasmas are ionized gases that can produce chemically reactive environments, and are composed of a mix of positive ions, negative ions, electrons and neutral atoms and molecules. Low pressure plasmas are essential to the fabrication of microelectronics devices by delivering fluxes of radicals and ions to a semiconductor wafer. These radicals and ions then etch (remove material), deposit (add material) and passivate (change surface composition) the wafer surface through many fabrication steps to create the devices. A voltage is also applied to the substrate holding the wafer to accelerate ions to high energies in order to activate these on-wafer processes. An important type of plasma used in microelectronics fabrication is an electronegative plasma in which the density of negative ions is much larger than electrons. These plasmas are very sensitive to operating conditions (such as power, pressure and gas mixture), with instabilities often. The quality of the devices being fabricated are sensitive to these instabilities and so tighter control of the plasma process is becoming more important. Pulsing the plasma (turning the power on-and-off) and pulsing the acceleration voltage results in higher precision components with smaller dimensions, whiich translates into more powerful electronics devices. Although pulsing provides many advantages, pulsing also produces instabilities. In order to optimize the plasma processes that are used to manufacture microelectronics devices, these instabilities in electronegative plasmas must be understood, controlled and, if possible, prevented.In this project, experimental and computational investigations of pulsed electronegative plasmas are being conducted for the type of inductively coupled plasmas (ICPs) that are used for microelectronics fabrication. The goal is to quantify the interactions between the pulsed sources that produce the plasma and the pulsed biases that accelerate ions into the wafer, the onset of instabilities, and methods to control those instabilities. This investigation is being conducted in collaboration with our GOALI partner Lam Research Corp. We are making 3-dimensional, time dependent measurements of electron density, temperature, plasma potential, current density, magnetic fields and ion energy distributions using laser and electrical probe diagnostics. First principles modeling is being used to investigate fundamental plasma transport during pulsed transients, electrostatic-to-electromagnetic (E-H) transitions and interactions of pulsed sources and biases. The end result will be a greatly improved understanding of pulsed electronegative plasmas of the type used for materials processing, with this understanding being rapidly translated to practice by our GOALI partner.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.

从汽车到开门器，我们使用的几乎所有科技产品都离不开电脑、手机和无数专门的电路。不为人所知的是，这些电路大部分是装在小型半导体芯片里的，这些电路元件的尺寸接近原子的大小，而且这些电路是在含有第四种物质状态——等离子体的机器里生产的。等离子体是可以产生化学反应环境的电离气体，由正离子、负离子、电子和中性原子和分子的混合物组成。低压等离子体是制造微电子器件必不可少的，通过向半导体晶圆提供自由基和离子的通量。然后这些自由基和离子通过许多制造步骤蚀刻（去除材料）、沉积（添加材料）和钝化（改变表面成分）晶圆表面来制造器件。在保持晶圆的衬底上施加电压，将离子加速到高能量，以激活这些晶圆上的过程。用于微电子制造的一种重要等离子体是电负性等离子体，其中负离子的密度远远大于电子。这些等离子体对操作条件（如功率、压力和气体混合物）非常敏感，经常不稳定。正在制造的器件的质量对这些不稳定性很敏感，因此对等离子体过程的严格控制变得更加重要。脉冲等离子体（打开和关闭电源）和脉冲加速电压产生精度更高、尺寸更小的组件，从而转化为更强大的电子设备。虽然脉冲提供了许多优点，但脉冲也产生了不稳定性。为了优化用于制造微电子器件的等离子体过程，必须了解、控制并在可能的情况下预防电负性等离子体中的这些不稳定性。在这个项目中，脉冲电负性等离子体的实验和计算研究正在为用于微电子制造的电感耦合等离子体（icp）类型进行。目标是量化产生等离子体的脉冲源和加速离子进入晶圆的脉冲偏差之间的相互作用，不稳定性的开始，以及控制这些不稳定性的方法。这项研究是与我们的GOALI合作伙伴Lam Research Corp.合作进行的。我们正在使用激光和电探针诊断技术对电子密度、温度、等离子体势、电流密度、磁场和离子能量分布进行三维、时间相关的测量。第一性原理建模被用于研究脉冲瞬变过程中的基本等离子体输运、静电到电磁（E-H）跃迁以及脉冲源和偏置的相互作用。最终结果将大大提高对用于材料加工的脉冲电负性等离子体的理解，这种理解将迅速转化为我们的GOALI合作伙伴的实践。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。