Superconformal Growth of Thin Films by Two-Component CVD

非技术描述：集成电路需要晶体管的多级微观布线，即，需要十层或更多层垂直列和水平行的铜来将所有晶体管互连到功能芯片中。对于每一层，需要先进的图案化和蚀刻方法来创建尺寸远低于1微米的圆柱形和沟槽形开口。在更小的尺寸尺度上制造这种精致的结构，而没有任何被困的空隙空间或沿中心线沿着的低密度材料的“接缝”，是一个重大的挑战。该项目探索了一种完成填充步骤的新方法：在特殊条件下使用两种化学物质从气相沉积材料，导致开口底部的生长速率比顶部快，称为超共形生长。在填充过程中，沉积的材料形成V形轮廓，顶点从底部向上移动，以提供完美的填充结构。该研究项目与各种教育活动相结合：让研究生参与研究的各个方面，监督本科生的高级项目，并将研究成果传播给科学和技术界。技术说明：该研究项目开发了一种创新的方法，可以在衬底中的沟槽和过孔等高深宽比（深度：宽度）开口内以超共形方式存款薄膜材料，从而实现完全无空隙填充。这种超共形生长是各种纳米级制造工艺所需要的。在这个项目中，生长过程是在相对较低的温度下，通常低于300摄氏度，使用两种反应物进行化学气相沉积。存在一个动力学制度，物种运输和表面反应速率的竞争导致超共形增长。该项目的任务包括：（1）演示和评估各种材料和各种开口的超保形填充方法;（2）创建一个可以预测一般超保形生长条件的效果的数学模型;（3）确定结构内需要什么样的化学物质分布来消除低密度材料的生长。这些实验生成详细的动力学数据，这些数据针对基于扩散的模型进行测试。该过程的原子尺度机制是确定使用原位分析的膜表面，详细计算的颗粒传输和填充的配置文件，和反应副产物的作用的关键检查。

Non-Technical Description: Integrated circuits require multi-level microscopic wiring of transistors, i.e., ten or more layers of vertical columns and horizontal rows of copper are needed to interconnect all the transistors into a functional chip. For each layer, advanced patterning and etching methods are required to create cylindrical and trench-shaped openings with dimensions well below one micrometer. Fabricating this exquisite structure on ever-smaller size scales, without any trapped void space or "seam" of low-density material along the centerline, is a significant challenge. This project explores a new method to accomplish the filling step: a material is deposited from the gas phase using two chemical species under special conditions that cause the growth rate to be faster at the bottom of the opening than at the top, termed as superconformal growth. During the filling process, the deposited material forms a V-shaped profile and the apex moves up from the bottom to afford a perfectly filled structure. The research project is integrated with various educational activities: involving graduate students in every aspect of the research, supervising undergraduate students on senior projects, and disseminating the research findings to the scientific and technical communities. Technical Description: This research project develops an innovative approach to deposit thin film materials in a superconformal fashion inside of high aspect ratio (depth : width) openings such as trenches and vias in a substrate, leading to complete and void-free filling. Such superconformal growth is needed for a wide variety of nanoscale fabrication processes. In this project, growth proceeds by chemical vapor deposition using two reactants at a relatively low temperature, generally below 300 degrees C. A kinetic regime exists where the competitions in species transport and surface reaction rates lead to the superconformal growth. The project tasks include (1) to demonstrate and evaluate the superconformal filling method for a variety of materials and in various openings; (2) to create a mathematical model of the effect that can predict superconformal growth conditions in general; and (3) to determine what distribution of chemical species within the structure is needed to eliminate the growth of low-density material. These experiments generate detailed kinetic data that are tested against a diffusion-based model. The atomic-scale mechanisms of the process are determined using in-situ analyses of the film surface, detailed calculations of particle transport and filling profiles, and a critical examination of the role of reaction byproducts.