高级检索

多孔基底原子层沉积薄膜分布的数值模拟

Numerical Simulation of the Film Distribution During Atomic Layer Deposition within Porous Substrates

  • 摘要: 原子层沉积(ALD)技术能在多孔基底内沉积亚纳米精度的薄膜,从而调节孔道尺寸和界面性质。此类ALD薄膜沉积,同时受到前驱体扩散和反应的影响,这给沉积动力学研究带来了困难。本文对ALD制备ZnO 薄膜过程中前驱体在γ-Al2O3基底外表面沉积和孔道内沉积过程建立了模型,并通过数值模拟对表面和孔道两种模型进行了参数敏感性分析,拟合得到沉积物覆盖率公式。结果表明:在表面沉积过程中,随着吸附速率常数ka、吸附态的二乙基锌(DEZ*)向单乙基锌(MEZ)转化速率常数k1、羟基浓度COH的增大,和脱附速率常数kd的减小,基底表面的薄膜沉积加快;对于孔道内沉积过程,较大的羟基浓度COH和较小的扩散系数DS,驱使薄膜沉积在较浅位置;拟合所得解析式能准确预测多孔基底外表面和孔道内的沉积物覆盖率及其分布。

     

    Abstract: Atomic layer deposition (ALD) technology can deposit thin films on porous substrates with sub-nanometer precision, thereby adjusting the pore size and interface properties. Such ALD processes are affected by the diffusion and reaction of precursors, which causes difficulties in studying the reaction kinetics. In this paper, models were established for the depositions on the outer surface and inside the pores of the γ-Al2O3 substrate where ZnO films were formed via ALD. A sensitivity analysis was carried out for the two models through numerical simulation, which led to the formulas of surface coverage of the deposits. The results show that during the deposition on the outer surface of the substrate, with the increase of adsorption rate constant ka, the conversion rate constant k1 of adsorbed diethyl zinc to monoethyl zinc, the hydroxyl concentration COH, and the decrease of the desorption rate constant kd, the film deposition accelerates. For the deposition inside the pores, higher COH and lower diffusion coefficient DS result in deposit formation in a shallow position. The analytical formulas can accurately predict the deposit coverage and its distribution on the outer surface and inside the pores of porous substrates.

     

/

返回文章
返回