硅应力非均匀氧化影响因素及其在纳米孔制作中的应用  

Influence Factors of the Stress-Dependent Nonuniform Silicon Oxidation and Its Application to Nano-Aperture Fabrication

作　　者：向伟玮[1] 文莉[1] 刘勇[1] 张秋萍[1] 何利文[1] 褚家如[1] 

机构地区：[1]中国科学技术大学精密机械与精密仪器系,合肥230027

出　　处：《纳米技术与精密工程》2011年第4期316-321,共6页Nanotechnology and Precision Engineering

基　　金：国家自然科学基金资助项目(50605061);中央高校基本科研业务费专项资金资助项目

摘　　要：在微等离子体无掩模加工研究中,单晶硅在分布应力作用下的非均匀氧化现象决定了采用各向同性刻蚀得到氧化硅空心针尖纳米孔的可行性和可靠性.以V型槽为对象,研究了单晶硅在槽尖端的非均匀氧化现象.利用高温下氧化硅的黏弹性特性,建立了硅在几何约束导致的分布应力作用下的热氧化模型.该模型表明,应力通过抑制氧元素在氧化硅层中的扩散和氧化反应速率来抑制氧化进行,从而非均匀的应力分布造成了非均匀的氧化层厚度.实验证明,硅在应力作用和几何约束下的热氧化,当氧化层厚度仅为160 nm时,不同温度下的厚度非均匀性基本一致,为72%左右;而当氧化厚度增长为1.1μm时,低温与高温下的厚度非均匀性差距显著增大,分别为42%和100%.分析表明,氧化层厚度非均匀性是应力生成与应力释放过程的综合作用结果,受到氧化温度和氧化时间两个可控因素的共同影响.在此基础上,利用硅在950℃下10 h的应力非均匀氧化及后续稀释氢氟酸的各向同性刻蚀成功制作出空心针尖阵列尖端直径为50 nm^200 nm的纳米孔.In microplasma maskless etching,the nonuniform silicon oxidation under the distributed stress determines the feasibility and reliability of the nano-aperture at the apexes of the hollow pyramid tips of SiO2 obtained by isotropic wet etching.The research on nonuniform silicon oxidation at the apex of a V-shape trench was presented.The silicon thermal oxidation model under distributed stress caused by geometric constraint was built according to the viscoelastic characteristics of SiO2 at high temperature.This model indicates that oxidant diffusion in SiO2 and oxidation reaction are retarded by intrinsic stress in oxidation layer and the nonuniform stress distribution leads to the nonuniform oxidation layer thickness,which is experimentally proved that the nonuniformity of the oxidation layer thickness at different temperatures is nearly the same with the value of 72% when the oxidation layer thickness is about 160 nm during the silicon thermal oxidation under stress and geometric constraint.However,when the oxidation layer thickness grows to 1.1 μm,the nonuniformities of the oxidation layer thickness at low temperature and high temperature are obviously different,with the values of 42% and 100%,respectively.The nonuniformity of the oxidation layer thickness is a result of stress generation and stress relaxation,which can be controlled by oxidation temperature and oxidation time.Based on the experimental results,nano-apertures with the diameter of 50 nm—200 nm were fabricated at the apexes of the hollow pyramid tips after a 10 h nonuniform oxidation at 950 ℃ and the following water-diluted HF isotropic etching.

关 键 词：硅 应力 非均匀氧化 纳米孔 

分 类 号：TN305.5[电子电信—物理电子学]