(Ba, Sr)TiO_3 Thin Film Preparation by Liquid Source Chemical Vapor Deposition.

采用液源化学气相沉积（LSCVD）方法，设计了一种用于介质材料薄膜制备的化学气相沉积（CVD）反应器。用数值模拟的方法从实验和理论上研究了成膜机理。我们澄清了以下结果。实验方法1)设计了最高工作温度为800℃的单晶片CVD反应器，并测量了反应器的温度分布和压力。2)在硅片上制备了二氧化钛（TiO_2）、钛酸钡（BaTiO_3）和钛酸锶钡（BST）等介电膜。利用场发射扫描电镜（FE-SEM）和电感耦合等离子体原子发射光谱（ICP-AES）分别测量了膜厚、表面形貌和化学成分随径向的变化规律。采用x射线衍射（XRD）和透射电镜对晶体结构进行了分析。3)因此，研究了前驱体流量、操作温度和压力等操作条件对薄膜沉积速率、表面形貌的化学成分和晶体结构的影响。理论方法1)采用数值模拟的方法研究了石英管反应器中能量传质、扩散、化学反应等因素对成膜机理和成膜速率的影响。并将建议的Ba、Sr和Ti源薄膜沉积速率与实验结果进行了比较。2)所提出的化学反应动力学和反应速率常数也可以反映单晶片式CVD反应器中的膜沉积速率。

We designed a chemical vapor deposition (CVD) reactor for film preparation of dielectric materials by a liquid source chemical vapor deposition (LSCVD) method. A film formation mechanism has been investigated experimentally and theoretically using a numerical simulation. We clarified following results.Experimental approach1) We designed a singie wafer CVD reactor with maximum operating temperature of 800℃ and measured temperature profiles and pressures of the reactor.2) Dielectric films such as titanium dioxide (TiO_2), barium titanate (BaTiO_3), and barium strontium titanate (BST) were prepared on silicon wafers. Their film thicknesses and surface morphologies and chemical compositions as a function of radial direction were measured by a field emission scanning electron microscopy (FE-SEM) and inductively coupled plasma atomic emission spectroscopy (ICP-AES), respectively. Crystalline structures were analyzed by x-ray diffraction (XRD) and transmission electron microscopy.3) Thus, the effects of operating conditions, such as precursor flow rates, operating temperatures, and pressures on the film deposition rate, chemical compositions of the surface morphology, and crystalline structures were investigated.Theoretical approach1) The film formation mechanisms and film deposition rate were demonstrated by the numerical simulation considering energy and mass transfer, diffusion, chemical reactions in a quartz tubular reactor. The suggested film deposition rates of Ba, Sr, and Ti sources were compared to the experimental results.2) The suggested chemical reaction kinetics and the reaction rate constants can demonstrate the film deposition rate in the single wafer type CVD reactor as well.