【作者】 陈智利；

【导师】 刘卫国；

【作者基本信息】 西安电子科技大学 ， 微电子学与固体电子学， 2014， 博士

【摘要】 低能离子束溅射/刻蚀固体表面形成自组织纳米微结构，是一种高效、简便、低成本制造大面积有序纳米结构的方法。该方法具有加工精度高、改变离子束参数可实现纳米微结构的尺寸控制、易于实现自动化等特点。因此，低能离子束刻蚀晶体表面形成自组织纳米结构近年来一直是学术界研究的热点。本文针对单晶硅和蓝宝石材料，研究了不同离子束参数刻蚀形成规则自组织纳米微结构的关键技术，所取得主要研究成果是：1.对离子束刻蚀形成纳米微结构的理论模型进行了分析和仿真。分析了基于sigmund溅射理论的BH模型和MCB模型，通过引入离子束诱导项和非线性项，MCB模型对BH模型不能解释的低温下纳米结构形成及长时间刻蚀饱和的不足进行了改进。本文针对MCB模型进行了详细的分析和仿真，建立了刻蚀项、分散项和扩散项与离子束参数的关系，阐释了纳米自组织结构的形成原因及演变过程。2．建立了样品旋转时自组织纳米点状结构形成的数学模型，确定了不定形层热扩散是单晶硅主要扩散机制，获得了单晶硅的纳米微结构。研究发现：当离子束能量1000eV、束流密度265A cm2、样品不旋转时，离子束小角度（540）刻蚀单晶硅表面可获得条纹状纳米结构；增大入射角度（4050），样品表面趋于光滑；继续增大入射角度到65以后样品表面出现柱状纳米结构。而当样品旋转时，在相同离子束参数作用下，在较小离子入射角度（540）和较大入射角度（6585）都可获得纳米点状结构，尺度约为5085纳米，实验结果验证了模型的正确性。3．获得了蓝宝石纳米结构，针对蓝宝石晶体结构，提出了3+1维数学模型，揭示了离子束刻蚀下蓝宝石表面形貌的演变规律；确定了离子束诱导扩散是蓝宝石表面主要的扩散机理。利用Ar+离子束刻蚀蓝宝石，在离子束能量1200eV、束流密度265、样品不旋转下，在520和3545时，形成了纵向尺度较小的点状纳米结构，有序性较差；在30附近，样品表面趋于光滑，增大入射角度到45，样品表面出现有序的条纹结构，条纹方向与离子束方向垂直，继续增大离子束入射角度，在离子束入射方向出现柱状结构，垂直于离子束方向仍保持规则的有序条纹状结构，且样品表面粗糙度迅速增大。不同于单晶硅，离子束能量在蓝宝石中分布各向异性，蓝宝石表面弛豫主要是离子束诱导机制，利用建立的数学模型对刻蚀结果进行了仿真与分析。4．建立了Ar+离子束能量与刻蚀后蓝宝石表面形貌的关系，揭示了不同表面形貌形成的机理。研究发现相同角度，不同能量刻蚀后蓝宝石样品表面也会出现多种纳米结构。在入射角度65、能量较小(600750eV)时，样品表面出现点状结构，增加能量到900eV，样品表面出现规则的条纹状结构，继续增大能量，样品在离子束入射方向出现柱状结构，垂直方向为有序条纹状结构。渗透深度及能量各向异性分布是纳米结构形貌演变的主要因素。5.提出了使用离子束刻蚀形成的有序纳米结构提高样品透过率的方法。在1100nm2000nm波长范围内，利用Ar+刻蚀单晶硅，当离子束能量1000eV、束流密度265A cm2，在入射角度15、样品不旋转时，表面形成的规则条纹结构可使透过率提高约8%；而在入射角度65、样品旋转时，形成的规则点状结构，可使透射率提高约15%；透过率随纳米结构的有序性及纵向尺寸的增大而提高。引入等效折射率理论解释了样品表面减反射的现象。6.研究了刻蚀时间对单晶硅和蓝宝石刻蚀的影响规律。结果发现增加刻蚀时间，纳米结构形貌未发生变化，但纳米结构纵向尺度增大，有序性增强，长时间刻蚀后趋于饱和，此时模型非线性项起主要作用。更多还原

【Abstract】 Low energy ion beam erosion to generate self-organizing nano-structure on solidsurfaces is a simple, effective, and inexpensive method for production of orderlynano-structure with a large area. This method has the features of higher manufacturingprecision, realization of control over nano-structure dimensions by changing ion beamparameters, and aptness for automation. Therefore, it has been a research focus inEurope and the USA in recent years. This paper researches the critical techniques ofnano-structure formation with various ion beam parameters, for experimental materialsof monocrystalline silicon and sapphire, which makes the major research achievementsas following:1. The analyses and simulations of the theoretical models for nano-strucureformation by ion beam erosion are conducted. BH model and MCB model, both ofwhich are based on Sigmund spurting theory, are analyzed. And the introduction of ionbeam inducing term and non-linear term to MCB model improves the shortcoming ofBH mode, failure to explain nano-structure formation at low temperatures and long-timeerosion saturation. This paper makes the detailed analyses and simulations of MCBmodel, provides erosion term, dispersion term and diffusion term, and accounts for theformation and evolution of self-organizing nano-structure.2. This paper establishes a mathematical model to describe formation ofself-organizing spot nano-structure with sample rotations, confirms that amorphouslayer thermal diffusion is the main diffusion mechanism for monocrystalline silicon andobtains nono-stucture of monocrystalline silicon. When ion flux density is265A/cm2and ion beam energy1000eV, without sample rotations, ribbon pattern nano-structuresappear on the surfaces of samples, spurted by ion beams with a small angle (540).Increase in the incident angle(4050) leads to the tendency to be smoother for thesample surfaces; further increase in the incident angle up to65, columnarnano-structures begin to emerge on sample surfaces. While samples are rotating, withthe identical ion beam parameters, dot nano-structures can be obtained no matter theincident angle is smaller（540） or larger（>65）, with a dimension range of5085nanometer. The erosion results confirm the validity of the mathematical model.3. After obtaining sapphire nano-structure and confirming that ion beam inducingdiffusion is sapphire’s main surface diffusion mechanism, a3+1dimensionmathematical model is established to describe the evolution of sapphire surfacetopographies by ion beam erosion. When Ar+ion beams are employed to erode sapphire, with an ion beam energy of1200eV and an ion flux density of265A cm2, dotnano-structures of smaller vertical dimensions can form, with lower orderliness, at anincident angle of520and3545; if the incident angle lies in30about, samplesurfaces tend to be smother; if the incident angle is up to45, orderly ribbon patternstructures appear on sample surfaces, perpendicular to ion beams; if the incident angle isfurther raised, columnar structures turn up in the incident direction of ion beams andorderly ribbon pattern structures remain in the vertical direction, with a rapidenhancement of sample surface roughness. Different from monocrystalline silicon,sapphire has an anisotropic ion beam energy distribution, and sapphire surfacerelaxation mainly depends on ion beam inducing mechanism. The establishedmathematical model is employed to simulate and analyze the erosion results.4. The relationship is established between surface topographies of erodedsapphire and different Ar+ion beam energies, and the formation mechanism of surfacetopographies is displayed. The experiments find that various energies with the sameincident angles can produce different nano-structures on sapphire surfaces after eroding.At the incident angle of65, lower energy (600750eV) results in dot structures onsample surfaces; higher energy(900eV) produces regular ribbon pattern structures; andeven higher energy(>900eV) generates columnar structures in the incident direction ofion beams and orderly ribbon pattern structures in the vertical direction. Depositiondepth and anisotropic energy distribution are chief causes for evolution ofnano-structures.5. A method is raised to improve sample transmittance with formation of orderlynano-structure by employing ion beam erosion. Within the wavelength range of1100nm2000nm，Ar+ion beams are employed to erode monocrystalline silicon，whenincident angle is at15with ion flux density265A/cm2and ion beam energy1000eV,without samples rotation, ribbon pattern nano-structures appear on the surfaces ofsamples, transmittance of samples increased by8%approximately; when incident angleis at65with the same ion flux density and ion beam energy, with samples rotation, dotpattern nano-structures emerge, transmittance of samples increased by20%approximately. Enhancement of surface orderliness and height of nano-structures resultsin the increase of transmittance, which accounts for sample surface antireflections, withthe introduction of equivalent refractive index theory.6. The effects of eroding time on monocrystalline silicon and sapphire erosions arestudied. The results find that time extension is unable to change nano-struturetopographies, but able to increase the vertical nano-structure dimensions and enhance the orderliness. When saturation is achieved after long-time erosion, non-linear termsof model function principally.更多还原