Materials Synthesis and Processing: Experimental and Theoretical Studies on Titanium Nitride Synthesis by Laser Assisted Processes

激光在世界范围内引起了广泛的兴趣，因为它作为一种工具在许多科学和工程应用中，如材料的加工和合成。在激光的各种应用中，激光化学气相沉积(LCVD)和激光物理气相沉积(LPVD)技术可以用来合成具有精确空间控制的薄层材料。尽管激光诱导沉积(LID)工艺作为一种制备薄膜的优越技术的潜力已经被证明，但对这种工艺的基本原理的了解还很少。为此，我们开展了氮化钛(TiN)等化合物在盖子过程中成膜过程的实验研究和数学模型的研究，以了解这种过程的机理，并为激光辅助材料加工奠定科学基础。LPVP和LCVD的锡镀层的形态和化学计量将是一个主要的兴趣。由于锡在微电子、光电子、工具和航空航天等行业中的广泛应用，因此被选为研究的模型材料。TiN薄膜作为硅和铝(用于VLSI)之间的扩散阻挡层的应用经常被观察到。实验研究包括LID形成的TiN薄膜的光学和电学性质的测定和各种电子光学技术的表征。还将确定沉积点附近的表面温度和化学成分。这些结果将被用来获得关于薄膜中表面分解分数和团簇大小的信息。化学动力学数据将有助于揭示LPVD过程中气相和气固界面的反应速率规律，以及LID过程中反应速率的提高问题。随着实验工作的进行，数学研究将通过考虑高环境压力下沉积的连续介质力学，以及使用蒙特卡罗(MC)模拟或分子动力学(MD)技术在低环境压力(超高真空)下沉积来模拟LID过程中的粒子输运和化学反应。MC或MD模拟也可以用来预测团簇的大小及其对薄膜质量的影响。这些模型将有助于确定重要的工艺参数，预测LID系统的性能，设计和优化具有最优控制的LID系统。这项研究工作可能会改进控制激光薄膜沉积工艺，用于半导体加工和耐磨涂层的生产。

Lasers have attracted considerable interest world wide because of their versatility as a tool for many scientific and engineering applications such as processing and synthesis of materials. Among various applications of laser, Laser Chemical Vapor Deposition (LCVD) and Laser Physical Vapor Deposition (LPVD) techniques can be used to synthesize thin layers of materials with precise spatial control. Although the potential of Laser Induced Deposition (LID) processes as a superior technique to produce thin films has been demonstrated, little has been done to understand the fundamentals of such processes. For this reason, a research project encompassing experimental studies and development of mathematical models for the film forming process during LID for a compound such as Titanium Nitride (TIN) is researched in order to understand the mechanism of such processes, and to develop a science base for laser-aided materials processing. Morphology and stoichiometry of TiN deposits for both LPVP and LCVD will be a major interest. TiN is chosen as the model material for the study for its wide application in various industries such as microelectronics, opto electronics, tool and aerospace industries. Applications of TiN thin films as a diffusion barrier between Si and Al (for VLSI) is often observed. The experimental studies include the determination of optical and electronic properties and characterization by various electron-optical techniques for TiN films formed by LID. The surface temperature and chemical composition near the point of deposition will also be determined. These results will be used to obtain information about the surface-decomposition fraction and the cluster size in the film. The chemical kinetic data will shed light on the reaction rate law in the vapor phase during LPVD and at the gas-solid interface during LCVD, and on the question of enhanced reaction rate during LID. Along with the experimental works, mathematical studies will be carried out by considering continuum mechanics for deposition at a high ambient pressure, and by using the Monte Carlo (MC) simulation or molecular dynamics (MD) technique for deposition at a low ambient pressure (Ultra High Vacuum, UHV) to model particle transport with chemical reaction during LID. MC or MD simulation can also be utilized to predict the cluster size, and its effect on the film quality. Such models will be useful to determine the important process parameters, to predict the performance of the LID systems, to design and optimum LID system with optimum control. The researched work may allow the improved control laser- based thin film deposition processes for semiconductor processing and the production of wear-resistant coatings.