A Study of Plasma Chemistry in the Gas Phase and on Surfaces during Plasma Etching in Chlorine-and Bromine-Containing Plasmas

含氯和溴的等离子体现在在制造低于0.1 μm的器件时，对于硅、金属和金属氧化物（高介电常数/高k材料）的蚀刻是必不可少的。我们开发了粒子传输和表面反应的原子尺度模型，以模拟在含氯和含溴等离子体中蚀刻过程中纳米尺度的轮廓和关键尺寸控制的特征轮廓演变。在该模型中，衬底由大量小的（或原子尺度的）细胞或晶格组成，并且使用细胞去除方法来模拟不断变化的界面。该模型考虑了微结构中离子和中性离子的输运，以及离子增强蚀刻、化学蚀刻、离子的表面反射和穿透、中性离子的表面再发射、表面氧化、蚀刻产物和副产物的沉积以及溅射去除氧化和沉积表面等表面反应。基于入射离子与衬底原子连续两体弹性碰撞的动量和能量守恒，采用蒙特卡罗计算方法分析了离子在特征表面和衬底中的运动轨迹。用“高斯”量子化学格式计算了Cl-Si和Br-Si体系的相互作用势。结果表明，纳米尺度上蚀刻轮廓的控制主要依赖于蚀刻产物/副产物沉积和表面氧化形成的表面钝化层，以及蚀刻过程中特征表面离子反射和钝化层形成之间的竞争。此外，我们已经开发了在等离子体蚀刻过程中气相和衬底表面的反应物和反应产物的原位诊断，包括激光诱导荧光（LIF），傅里叶变换红外（FTIR）吸收光谱，四重质谱（QMS），以及光学发射光谱（OES）和拉格缪尔探针测量。然后我们研究了高钾栅极材料Si， HfO_2， Pt和TaN在含氯和含溴等离子体中的刻蚀，以更好地了解相关刻蚀机制。在数值分析和诊断的基础上，我们发现了在低离子能量条件下，HfO_2在Si上的高选择性蚀刻工艺，无射频偏压。数值和实验结果表明，表面蚀刻和沉积之间的竞争以及表面抑制剂在气相中的形成和淬火之间的竞争是观察到的现象的原因。少

Chlorine-and Bromine-containing plasmas are now indispensable for the etching of silicon, metals, and metal oxides (high dielectric constant / high-k materials) in the fabrication of sub-0.1 μm devices. We have developed an atomic-scale model of the particle transport and surface reactions, to simulate the feature profile evolution for nanometer-scale control of the profile and critical dimensions during etching in chlorine-and bromine-containing plasmas. In the model, the substrates are taken to consist of a large number of small (or atomic-scale) cells or lattices, and the evolving interfaces are modeled by using the cell removal method. The model takes into account the transport of ions and neutrals in microstructures, along with surface reactions of ion-enhanced etching, chemical etching, surface reflection and penetration of ions, surface reemission of neutrals, surface oxidation, deposition of etch products and by-products, and removal of oxidized and deposited surfaces by sputte … More ring. The trajectory of ions on feature surfaces and in substrates is analyzed by the Monte Carlo calculation, based on the momentum and energy conservation for an incident ion through successive two-body elastic collisions with substrate atoms. The interaction potential is calculated using the quantum chemical scheme "Gaussian" for the Cl-Si and Br-Si system. The numerical results indicated that for the nanometer-scale control of etched profiles relies largely on a competitive formation of surface passivation layers through deposition of etch products/by-products and surface oxidation, and on a competition between the ion reflection and passivation layer formation on feature surfaces during etching.Moreover, we have developed in situ diagnostics of reactants and reaction products in the gas phase and on substrate surfaces during plasma etching, including laser-induced fluorescence (LIF), Fourier transform infrared (FTIR) absorption spectroscopy, and quadruple mass spectrometry (QMS), in addition to optical emission spectroscopy (OES) and Lagmuir probe measurement. We then investigated the etching of high-k gate materials Si, HfO_2, Pt and TaN in chlorine and bromine-containing plasmas, to gain a better understanding of the etching mechanisms concerned. Based on the numerical analysis and diagnostics, we found a highly selective etching process for HfO_2 over Si, without rf biasing or under low ion energy conditions. The numerical and experimental results implied that a competition between the etching and deposition on surfaces, together with a competition between the formation and quenching of surface inhibitors in the gas phase, is responsible for the phenomena observed. Less