硅基宏孔光辅助电化学快速腐蚀机理研究

项目名称： 硅基宏孔光辅助电化学快速腐蚀机理研究

项目编号： No.60876079

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 金属学与金属工艺

项目作者： 焦继伟

作者单位： 中国科学院上海微系统与信息技术研究所

项目金额： 33万元

中文摘要： 面向MEMS及3D集成应用，开展了光辅助下硅基宏孔快速腐蚀技术及其机理和模型研究。在强氧化剂、高HF浓度和大电流密度条件下，实现了N型硅上快速宏孔腐蚀，达到1800μh；以DMF为有机溶剂，实现了P型硅上快速宏孔腐蚀，达到1900μh，为现有报道最快。提取了典型PSi快速孔腐蚀过程的关键参数，通过阻抗谱方法分析了赫尔姆兹双电层电势降等因素的影响，对SCR传统模型进行了修正。提出一种部分氧化衬底（POPS）上二次电化学腐蚀方法制作自定位纳米尺度孔阵列的技术，并以"第次耗尽"模型解释随深度纳米孔阵列的"瓶颈"限制效应的机理及与传统模型SCR的差异。分析了HF 电解液中双氧水、DMF等添加剂的氧化力、钝化力以及硅溶解价、硅-电解液界面等因素的影响，通过调制电流密度，实现了同一衬底上三种不同类型孔结构（宏、介、微）及其组合的多层结构的制备。提出一种新型的利用外加压力改变电场分布抑制PSi宏孔边缘效应的方法。基于PSi宏孔快速腐蚀方法成功制作了一系列高深宽比微纳结构；实现了4"衬底上的PSi宏孔制作。尝试利用HCl基电解液在锗上成功制出了100nm量级、深宽比50的多孔。

中文关键词： 多孔硅；宏孔；快速成孔；光辅助电化学腐蚀；阻抗谱

英文摘要： In this project, we report the results of the study on the technology, mechanism and model of the fast formation of porous silicon(PSi) macropores based on light-assisted electrochemical etching for MEMS and 3D integration applications. By using stronge oxidizer, high HF concentration and/or high current density, the etching rates of PSi macropores on N- and P-type Si substrate were achieved at 1800um/h and 1900um/h, respectively. The latter is reported the highest to our knowledge. Impedance spectroscopy analysis approach was taken to investigate the impact of Helmholtz layer potential drop on the etching behavior, based on which the conventional SCR model was modified. Self-aligned nano pores was formed on POPS. A novel "step depletion" model is proposed to explain the "bottelneck limit effect" on pore dimension and the deviation from SCR model. We investigated the oxidization and passivation power of the surfactants, such as H2O2, DMF in HF-based electrolyte, the impacts of Si/electrolyte interface, dissolvent value. We successfully fabricated macro-, meso and micro PSi and the multi-layer combinations on the same substrate by adjusting current density. And a novel approach was proposed to suppress the PSi boundry effect by applying extra tension. A series of high aspect ratio micro/nano structures were achieved by using PSi etching. On other semiconductor Ge substrate, nano pores with 100nm diameter and aspect ratio of 50 were achieved successfully using HCl-based electrolyte.

英文关键词： Porous Silicon;macropore;fast formation;light-assited electrochemical etching; impedance spectroscopy