【作者】 焦庆斌；

【导师】 巴音贺希格；

【作者基本信息】 中国科学院研究生院(长春光学精密机械与物理研究所) ， 光学， 2014， 博士

【摘要】 单晶硅湿法刻蚀技术是指应用化学溶液腐蚀的手段在硅材料上制作微纳结构的技术。为降低硅器件表面粗糙度，超声波作为辅助手段被广泛应用于单晶硅湿法刻蚀工艺中。在单晶硅与腐蚀液反应过程中，超声波特有的空化效应会强化传质过程，从而达到提高反应速率与加速反应进程的目的。在湿法刻蚀工艺中，超声波频率、功率对于溶液传质系数影响的研究目前仍处于定性阶段，缺乏定量分析理论模型，无法指导实际工作。硅中阶梯光栅是利用硅的各向异性制作而成的，该领域是对单晶硅湿法刻蚀技术应用的一种扩展。超声波的引入对硅中阶梯光栅的闪耀面粗糙度有较大影响。利用单晶硅湿法刻蚀工艺制作阶梯形光栅时经常将(111)晶面作为光栅的闪耀面。目前，对于硅中阶梯光栅闪耀面粗糙度的研究相对较少，尤其是在超声波参与条件下对闪耀面粗糙度的影响规律的系统研究尚未开展。鉴于此，本文围绕单晶硅湿法刻蚀过程中的超声强化传质机理与硅中阶梯光栅湿法刻蚀工艺做了较为深入的研究。第一，基于―超声改变流速、流速改变传质‖的建模思想，借助COMSOL Multiphysics软件中声场、层流场及传质场模块，建立了一种新型定量求解传质系数与超声波频率、功率之间关系的模型。通过对超声场、溶液流速以及硅片表面浓度梯度等问题的研究，详细讨论了传质系数随超声波参数的变化规律，解决了此类研究课题无法定量求解传质系数与超声波作用关系的难题。第二，基于反应缩芯理论，给出了单晶硅湿法刻蚀过程中刻蚀速率与传质系数之间的理论关系公式。利用上述超声强化传质模型中所求得的传质系数，可以获得对应的刻蚀速率的数值，进而定量求解刻蚀速率与超声波之间的作用关系，实现对湿法刻蚀工艺实践的指导。第三、基于超声波空化作用及异丙醇增加单晶硅表面润湿性的原理，系统地讨论了超声波震荡法及润湿性增强法对中阶梯光栅闪耀面粗糙度的影响规律。实验结果表明，同时施以超声波震荡法及润湿性增强法可以制备更低粗糙度的硅中阶梯光栅。更多还原

【Abstract】 Silicon wet etching technology is the application that productsmicro-nanostructure on silicon materials by means of chemical solution corrosion. Inorder to reduce the surface roughness of the silicon devices, ultrasonic as theassistant means is widely used in silicon wet etching process. In the reaction processbetween silicon and corrosive liquid, the ultrasonic cavitation will enhance the masstransfer process, which could achieve the goal of improving the reaction rate andaccelerating the reaction process. In the wet etching process, the study of ultrasonicenhancement on mass transfer coefficient is still in the stage of qualitative, whichcauses the lack of quantitative analysis model and failure to guide the practical work.The silicon echelle grating is fabricated using the acisotropic etching behavior ofsingle-crystal silicon, which is an extension of the application of silicon wet etchingtechnique. The introduction of ultrasound has great influence to roughness on theblazed surface. The (111) crystal plane is usually used to be the blazed surface whenfabricating echelon grating by means of silicon wet etching. At present, the study ofroughness on blazed surface is little; especially there is no investigation on theinfluence between ultrasonic parameters and roughness on blazed surface. In view of the conditions mentioned above, the thorough researches of the mechanism ofultrasound to intensity mass transfer process in silicon wet etching and the wetetching technology of silicon echelle grating are maded in this paper. First, a newcomputational model to solve mass transfer coefficient quantitatively is put forwardbased upon the ultrasound field, flow field and mass transfer field module inCOMSOL Multiphysics software, which is including the study of the change ofdistribution of the liquid velocity under ultrasound effect, and the mathematicalrelationship between mass transfer coefficient and the distribution of solutionconcentration affected by liquid velocity. The changing law of mass transfercoefficient with ultrasonic parameters is discussed in detail through the study ofultrasonic field, solution flow rate and concentration gradient of the silicon surface,and the problem of such research cannot be quantitatively calculated mass transfercoefficient and the relationship between ultrasonic actions is solved. Second, thetheoretical formula between etching silicon wet etching process rate and masstransfer coefficient is given based on the theory of shrinking core. The numericalvalue of etching rate can be gotten through solving the mass transfer coefficient bythe model established which could solve quantitatively the relationship betweenultrasound and etching rate and realize the guidance to the wet etching process.Third, based upon the ultrasonic cavitation and wettability enhanced by IPA, theeffects of ultrasonic vibration and wettability enhancement on surface roughness onblaze plane of silicon echelle grating have been discussed systematically. Theexperimental results indicated that the combination of ultrasonic vibration andwettability and optimizing of experimental parameters could fabricate the siliconechelle grating with lower surface roughness.更多还原