GOALI: Shear thickening and defect formation in chemical mechanical polishing slurries

0968042 -解放者化学机械抛光（CMP）工艺是一项关键技术，可持续缩小半导体的特征尺寸，同时提高特征密度。CMP又是微处理器速度和功率持续增加的主要贡献者，同时持续降低性能成本，通常称为摩尔定律。半导体芯片上特征尺寸的持续减小使得近来引入低介电常数材料作为连接器之间的绝缘体成为必要。这些低介电常数（低k）材料通常是易碎的，并且比传统的二氧化硅材料更容易受到应力引起的损坏。这种应力引起的损坏可能严重到足以破坏损坏事件附近的绝缘能力，导致半导体器件的短路和故障。因此，合作努力寻求获得对CMP浆料的高剪切流变学以及抛光浆料中的颗粒的暂时和永久变化的详细理解，包括颗粒尺寸分布变化和产生的任何新颗粒附聚物的结构。 三个目标将测试的假设，即剪切稠化的浓缩浆料可能会导致固体一样的行为在抛光过程中，这可能会导致缺陷的形成时，抛光介电晶片表面，特别是新引入的低介电常数绝缘材料。目标是：1.在存在和不存在剪切增稠的情况下，在工艺相关剪切速率下，使用流变光学测量对CMP浆料进行同步结构和流变学研究。使用场流分级（FFF）分离量化浆料中颗粒尺寸的暂时和永久变化，因为CMP浆料的剪切增稠可能由非常小部分的过大颗粒引起。3.将剪切响应和颗粒尺寸与抛光条件相关联，导致介电晶片表面上形成表面缺陷。智力优势：评估剪切增稠是否是化学机械抛光中缺陷形成的合理假设。证明或反驳该假设对浆料设计、制造和使用具有直接影响，以使得未来能够开发具有更小特征尺寸的半导体。此外，这项工作将扩展的基本理解剪切增稠高固体胶体分散体的分散体组成的颗粒与自己的分形结构。更广泛的影响：这里提出的三管齐下的方法将提供重要的洞察力的潜力和限制的胶体性质的CMP。这将提高浆料生产商和半导体制造商优化配方和工艺参数的能力，从而使未来的半导体生产能够快速发展。这项研究将影响其他利用大面积硅技术的行业，例如，平板显示器和太阳能电池，并与科罗拉多矿业学院、NSF材料研究科学与工程中心的可再生能源有关。此外，这项研究将有助于教育流变学和颗粒表征领域的研究生和本科生，因为他们适用于真实的工业利益的问题。高级工业科学家将花时间在学术环境中教学，而学生将在工业环境中居住数月。

0968042 - LiberatoreThe Chemical Mechanical Polishing (CMP) process is a critical piece of technology enabling the continued reduction in feature size in semiconductors, with the concomitant increase in feature density. CMP in turn is a major contributor to continuing increases in microprocessor speed and power with continuing reductions in cost to performance measures, often referred to as Moore's Law. Continued reduction of feature sizes on semiconductor chips has necessitated the recent introduction of low dielectric constant materials as the insulator between connectors. These low dielectric constant (low k) materials are generally fragile and much more prone to stress induced damage than the traditional silicon dioxide material. This stress induced damage can be severe enough to destroy the insulating capability in the vicinity of the damage event, leading to a short circuit and failure of the semiconductor device. Thus, a collaborative effort seeks to obtain detailed understanding of the high shear rheology of CMP slurries and both temporary and permanent changes to the particles in the polishing slurry, including both particle size distribution changes and the structure of any new particle agglomerates produced. Three objectives will test the hypothesis that shear thickening of concentrated slurries can cause solid like behavior during polishing, which can lead to defect formation when polishing dielectric wafer surfaces, particularly the newly introduced low dielectric constant insulating materials. The objectives are:1. Integrate simultaneous structure and rheology studies using rheo-optic measurements on CMP slurries at process relevant shear rates in the presence and absence of shear thickening.2. Quantify temporary and permanent changes to the particle sizes in the slurry using field flow fractionation (FFF) separation as the shear thickening of CMP slurries may be caused by a very small fraction of oversized particles.3. Correlate shear response and particle size to polishing conditions causing surface defect formation on dielectric wafer surfaces.Intellectual Merit:Evaluate whether shear thickening is a reasonable hypothesis for defect formation in chemical mechanical polishing. Proving or disproving the hypothesis has immediate implications for slurry design, manufacture and use to enable future development of semiconductors with smaller feature sizes. Also, this work will extend the basic understanding of shear thickening in high solids colloidal dispersions to dispersions composed of particles with their own fractal structure.Broader Impact:The three pronged approach proposed here will provide important insights on the potential and limitations of the colloidal nature of CMP. This will enhance the ability of slurry producers and semiconductor manufacturers to optimize both the formulations and the processing parameters, thereby enabling rapid progress in future semiconductor production. The research will impact other industries that utilize large area silicon technology, e.g., flat panel displays and solar cells and tie into the Colorado School of Mines, NSF Materials Research Science and Engineering Center on renewable energy. In addition, this research will help educate graduate and undergraduate students in the fields of rheology and particle characterization as they apply to problems of real industrial interest. A senior industrial scientist will spend time teaching in the academic environment while students will spend months in residence in the industrial setting.