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

现在，在制造小于0.1μm的器件时，含氯和含溴的等离子体对于硅、金属和金属氧化物(高介电常数/高k材料)的刻蚀是必不可少的。我们开发了一个粒子输运和表面反应的原子尺度模型，用于模拟在含氯和含溴的等离子体中刻蚀过程中特征轮廓的演变，以纳米尺度控制轮廓和临界尺寸。在该模型中，衬底被视为由大量小的(或原子尺度的)单胞或晶格组成，并使用单胞去除方法对演化的界面进行建模。该模型考虑了离子和中性物质在微结构中的传输，以及离子增强腐蚀、化学腐蚀、离子的表面反射和渗透、中性物质的表面再发射、表面氧化、腐蚀产物和副产物的沉积以及溅射…去除氧化和沉积表面的表面反应。更多的戒指。基于离子与衬底原子连续两体弹性碰撞的动量守恒和能量守恒，用蒙特卡罗方法分析了离子在特征表面和衬底中的运动轨迹。用“高斯”量子化学方法计算了Cl-Si和BrSi体系的相互作用势。数值结果表明，对于刻蚀轮廓的纳米尺度控制，很大程度上依赖于刻蚀产物/副产物的沉积和表面氧化过程中表面钝化层的竞争形成，以及在刻蚀过程中特征表面上离子反射和钝化层形成的竞争。此外，我们还开发了等离子体刻蚀过程中气相和衬底表面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)吸收光谱和四重质谱仪(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k栅材料Si、HfO_2、Pt和Tan在含氯和含溴等离子体中的刻蚀，以更好地了解有关的刻蚀机理。在数值分析和诊断的基础上，我们发现了一种在没有射频偏置或在低离子能量条件下对HfO2在硅上进行高选择性刻蚀的工艺。计算和实验结果表明，表面腐蚀和沉积之间的竞争，以及气相中表面缓蚀剂的形成和猝灭之间的竞争，是造成观察到的现象的原因。较少

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