硅的各向异性湿法腐蚀工艺及其在微纳结构中的应用研究

国防科学技术大学 硕士学位论文 硅的各向异性湿法腐蚀工艺及其在微纳结构中的应用研究 姓名：陈骄 申请学位级别：硕士 专业：机械工程 指导教师：吴学忠 2010-11
国防科学技术大学研究生院硕士学位论文
摘 要
硅的各向异性湿法腐蚀是硅片微机械加工的重要技术之一，它被广泛地应用 于在硅衬底上加工各种各样的微结构，如膜结构、凹槽结构、悬臂梁等，近年来 也被用于很多纳米结构的制造。 本文以{110}、{111}和{100}三种类型硅的各向异性湿法腐蚀为研究对象，对 腐蚀结构及其变化规律、腐蚀速率、腐蚀形貌和粗糙度等特性进行了研究，并制 作了相应的微结构和纳米孔腔结构阵列。具体内容如下： 1．详细介绍了单晶硅的晶体结构和硅的各向异性湿法腐蚀工艺，根据各种腐 蚀剂的特性，选择 TMAH 溶液作为本文的各向异性湿法腐蚀剂。介绍了几种典型 的湿法腐蚀模型，探讨了各向异性湿法腐蚀机理，并以此为基础设计了实验流程 和方案。 2．通过不同形状掩膜窗口的湿法腐蚀实验对比，经实验结果和理论分析，分 别得出三种晶向硅的腐蚀结构变化规律，这为不同形貌的纳米硅腔阵列的制作打 下了基础。通过在 TMAH 溶液中加入添加剂（过硫酸铵或 IPA 等）的对比实验， 研究了硅的腐蚀速率、腐蚀形貌特征和粗糙度等特性，表明了过硫酸铵和 IPA 都 能显著改善硅腐蚀表面的质量，且都会不同程度地降低腐蚀速率。探讨了硅的预 腐蚀技术，它可以用来制作更多形貌的硅腔结构。 3．根据{110}硅湿法腐蚀可得到 70.5°角的倾斜结构和垂直侧壁的特性，初 步研究了一种基于{110}硅的音叉式微机械陀螺的湿法腐蚀，分析结构误差并提出 修正方案； 根据{111}和{100}硅湿法腐蚀可分别得到八面体型腐蚀腔和倒金字塔型 腐蚀腔的特性， 分别制作了基于{111}硅的八面体型纳米孔腔结构阵列和基于{100} 硅的倒金字塔型纳米孔腔结构阵列，这为金属纳米结构阵列的制造提供了有效的 模版。 主题词：各向异性湿法腐蚀 {110}硅 {100}硅 硅微机械加工 TMAH 腐蚀特性 {111} 硅 纳米孔腔结构阵列
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国防科学技术大学研究生院硕士学位论文
ABSTRACT
Anisotropic wet etching of silicon is one of the most important techniques in silicon micromachining, which has been extensively employed to fabricate a wide variety of micro-structures including membranes, grooves, suspended beams, etc, and also utilized as one of the effective approachs in the fabrication of nano-structures in recent years. In this dissertation, anisotropic wet etching of {110}, {111} and {100} silicon are studied systematically, including the etched structures and their changing laws, etching rates, etching morphology and surface roughness. The corresponding micro-structure and nanopore cavity arrays have been made. The research results are shown as follows: 1. The crystal structure and anisotropic wet etching technology of the monocrystalline silicon are introduced. According to the properties of different etchants, TMAH is selected as the main etchant in this work. By three typical etching models, the mechanism of anisotropic wet etching of silicon is analyzed. On the basis of the mechanism and the crystallographic properties, the experimental process and program are designed. 2. By comparative experiments under etching mask windows of different shapes in TMAH solutions, the changing laws of etched structures are obtained respectively by experimental results and theoretical analysis, which lay a foundation for the fabrication of nanopore cavity arrays. The etching characteristics in TMAH solution with different surfactants (ammonium persulfate, IPA, etc.) are also discussed in detail, and it is found that ammonium persulfate and IPA can improve the quality of the etched surface remarkably while etching rates decrease to a certian extent. Then the pre-etching techniques are briefly discussed, which provide a way to make more special etched cavities. 3. Based on available tilted structures with the inclining angle of 70.5° and vertical walls by anisotropic wet etching of {110} silicon, a novel micromachined tuning fork gyroscope is preliminarily studied, and after analyzing the structural error, a correction scheme is proposed. And based on the available octahedral cavity by etching of {111} silicon and the inverted pyramidal cavity by {100} silicon, two corresponding nanopore cavity arrays are fabricated separately, which provide effective templates for the fabrication of metallic nanostructure arrays. Key Words ： Anisotropic wet etching Silicon micromachining TMAH Etching characteristics {111} silicon {110} silicon {100} silicon Nanopore cavity array
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国防科学技术大学研究生院硕士学位论文
图 ห้องสมุดไป่ตู้ 录
图 1. 1 图 1. 2 图 1. 3 图 1. 4 图 1. 6 图 1. 7 图 1. 8 图 1. 9 腐蚀速率与 KOH 腐蚀剂浓度的关系 ............................................................ 1 Kenji Tokoro 等人的腐蚀实验装置 ................................................................ 2 O.Tabata 等人的硅湿法腐蚀实验结果 ........................................................... 2 Werasak Sonphao 等人的腐蚀实验结果 ......................................................... 3 A. Merlos 和 M. C. Acero 等人的腐蚀实验结果 ............................................ 4 贾翠萍和董玮等人的腐蚀实验研究 ............................................................... 4 司俊杰等人的腐蚀实验结果 ........................................................................... 5 电容式微机械麦克风的结构图 ....................................................................... 6
图 1. 5 Yi Wei Xu、Aron Michel 等人的腐蚀实验结果 ............................................ 3
图 1. 10 高深宽比的梳状微致动器 ............................................................................... 6 图 1. 11 V 型槽硅微通道冷却器主要部件示意图 ....................................................... 6 图 1. 12 扫描探针显微镜的探针阵列 ........................................................................... 7 图 1. 13 Chih-Hung Sun 和 Nicholas C. Linn 等人制作的纳米结构阵列 ................... 8 图 1. 14 湿法腐蚀可制备的几种结构特征的金属纳米结构阵列 ............................... 9 图 2. 1 图 2. 2 图 2. 3 图 2. 4 图 2. 5 图 2. 6 图 2. 7 图 2. 8 图 2. 9 硅的面心立方晶系中的一些重要的晶面及密勒指数 ................................. 11 单晶硅的常见晶面 ......................................................................................... 12 硅片的主、次定位面 ..................................................................................... 13 (a)硅晶体的单元结构 (b)硅的晶体结构 ...................................................... 13 硅晶体沿典型方向的晶格截面 ..................................................................... 14 硅晶体三个主要晶面的原子排列示意图 ..................................................... 14 硅晶体三个主要晶面的硅原子化学键示意图 ............................................. 14 硅的各向同性与各向异性湿法腐蚀截面示意图 ......................................... 15 硅/电解液界面的能带模型[5]（上图为 p 型硅，下图为 n 型硅） ............. 19