ULSI介质CMP用大粒径硅溶胶纳米研磨料的合成及应用研究

针对超大规模集成电路多层互连结构中介质CMP抛光速率低,急需的大粒径硅溶胶研磨料,本文采用改进的粒径生长控制工艺制备介质CMP用大粒径硅溶胶,并采用TEM、激光粒度分析仪和Zeta电位测试仪等先进手段对其粒径大小、粒径分布和稳定性进行了表征。以低分散度硅溶胶纳米研磨料配制抛光浆料进行了二氧化硅介质的CMP研究,结果表明,平均粒径103．4nm的硅溶胶浆料的去除速率达630nm／min,有效解决了二氧化硅介质CMP低速率的难题。     

扫描电镜测定硅溶胶的粒度

硅溶胶是一种水溶液胶体,它是以SiO_2为基体在水中分散的两相体系。由于硅溶胶的粒径大小及分布对于最终态的物理和化学性质有着严重影响,因此测定其粒度有重要意义。硅溶胶的粒径向来是用透射电镜测定,我所使用扫描电镜观察了硅溶胶粒子形貌并测定其粒度,做到制样简单,重复性好。制样方法:取一滴硅溶胶放在20ml高级醇溶剂中,充分搅匀后取一小滴在负载6×6mm被刻蚀过的盖玻片的样品台座上,真空抽干后立即用离子溅射镀膜仪喷金后待用。采用上述制样方法,用JSM—35c摄制硅溶胶的扫描显微图象,如图1a。由图1a显示了二氧化硅胶团粒子是无定形、密聚的、海绵状的几乎是平均大小的球体形貌。我们选择扫描图象上均匀分散的几百至上千个粒子加以测量,根据平均粒径公式计算,所得统计计算结果如表1。     

集成电路多层铜布线阻挡层CMP技术与材料

以化学机械全局平面化(CMP)动力学过程和机理为基础,在抛光浆料中采用粒径为15～20nm的硅溶胶作为CMP磨料,保证了高的抛光速率(200nm/min),同时可有效降低表面粗糙度,减少损伤层的厚度.     

ULSI硅衬底的化学机械抛光

在分析UL SI中硅衬底CMP的动力学过程基础上,提出了在机械研磨去除产物过程中,适当增强化学作用可显著改善产物的质量传输过程,从而提高抛光效率.在对不同粒径分散度的硅溶胶抛光液进行比较后提出了参与机械研磨的有效粒子数才是机械研磨过程的重要因素,而不是单纯受粒径大小的影响.分析和讨论了CMP工艺中的几个影响因素,如粒径大小与分散度、p H值、温度、流量和浓度等.采用含表面活性剂和螯合剂的清洗液进行抛光后清洗,表面颗粒数优于国际SEMI标准,抛光雾得到了有效控制     

ULSI硅衬底的化学机械抛光

在分析ULSI中硅衬底CMP的动力学过程基础上,提出了在机械研磨去除产物过程中,适当增强化学作用可显著改善产物的质量传输过程,从而提高抛光效率.在对不同粒径分散度的硅溶胶抛光液进行比较后提出了参与机械研磨的有效粒子数才是机械研磨过程的重要因素,而不是单纯受粒径大小的影响.分析和讨论了CMP工艺中的几个影响因素,如粒径大小与分散度、pH值、温度、流量和浓度等.采用含表面活性剂和螯合剂的清洗液进行抛光后清洗,表面颗粒数优于国际SEMI标准,抛光雾得到了有效控制.     

微电子专用硅溶胶的纯化机理探究

首先对微电子工艺中引入杂质的危害进行了阐述,找出现有硅溶胶距实际应用的不足,发掘其纯化工艺,为微电子工艺领域中广泛应用硅溶胶提供前提条件。实验主要是对几种纯化工艺进行对比,由此从中得出,采用阳-阴-阳离子交换的方法最为适宜。然后对实验室制备的或在工业中已有应用的硅溶胶进行纯化,使其纯度达到10^-8级,并探讨了其纯化机理。     

硅衬底超精密CMP中抛光液的研究

针对硅衬底的化学机械抛光,采用自制的大粒径硅溶胶抛光液进行抛光实验,研究了抛光液中主要组分对抛光速率和表面平整度的影响,以提高抛光速率和抛光质量,采用测厚仪、AFM、台阶仪对抛光速率和表面进行了测试和表征.通过优化实验获得了高速率、高平整的抛光表面.去除速率(MRR)达697nm/min,表面粗糙度(RMS)降低至0.4516nm,在提高抛光速率的同时对硅片实现了超精密抛光.     

硅衬底超精密CMP中抛光液的研究

针对硅衬底的化学机械抛光,采用自制的大粒径硅溶胶抛光液进行抛光实验,研究了抛光液中主要组分对抛光速率和表面平整度的影响,以提高抛光速率和抛光质量,采用测厚仪、AFM、台阶仪对抛光速率和表面进行了测试和表征.通过优化实验获得了高速率、高平整的抛光表面.去除速率(MRR)达697nm/min,表面粗糙度(RMS)降低至0.4516nm,在提高抛光速率的同时对硅片实现了超精密抛光.     

基于硅溶胶的Au-SiO2复合溶胶的制备及其性能

对Au-SiO2复合溶胶制备和性能进行了初步研究。通过正交实验设计,分析了相关因素对硅溶胶性能的影响规律,确定了合适配比的硅溶胶。采用透射电子显微镜(TEM)测试结果,对比分析了Au-SiO2复合溶胶与硅溶胶的差异,对Au-SiO2复合溶胶的研究为Au-SiO2复合薄膜的制备奠定了基础。     

乙二醇纳米硅溶胶的制备及应用

将由离子交换法制备的SiO2水溶胶进行溶剂置换,得到了乙二醇纳米硅溶胶。借助纳米粒度分析仪、TGA-DSC、FT-IR对溶胶中粒子的粒度分布、溶胶的热稳定性和化学结构分别进行了表征。结果表明:所制乙二醇纳米硅溶胶的平均粒径为30nm,热稳定性非常好,化学结构为无定形的水合二氧化硅。另外,其含水量低于0.8%,稳定期超过一年半。添加该溶胶到铝电解电容器的工作电解液中,电解液的闪火电压提高了约50V,电导率提高了约90×10–6S/cm。     

微电子用硅溶胶的纯化

对微电子工艺中引入杂质的危害进行了阐述,找出现有硅溶胶距离实际应用的不足,发掘其纯化工艺,为微电子用硅溶胶的广泛应用提供了前提条件.     

Fe~(3+)掺杂TiO_2纳米晶溶胶的制备及性能

采用sol-gel法制备了Fe3+掺杂锐钛矿型TiO2纳米晶溶胶。对溶胶的物相结构和粒度分布进行了分析,并考察了薄膜的UV-Vis吸收光谱及溶胶的光催化性能。结果表明:Fe3+掺杂可提供杂质能级抑制电子与空穴的复合,且对TiO2溶胶粒子具有细化作用,因此TiO2溶胶的光催化活性提高,比未掺杂时最大提高了近30%。但Fe3+掺杂过多可能成为电子与空穴复合的中心,导致TiO2溶胶的光催化活性降低。r(Fe:Ti)的最佳范围为0.25~0.50。     

Multiscale Colloidal Assembly of Silica Nanoparticles into Microspheres with Tunable Mesopores

Colloidal assembly of silica (nano)particles is a powerful method to design functional materials across multiple length scales. Although this method has enabled the fabrication of a wide range of silica‐based materials, attempts to design and synthesize porous materials with a high level of tuneability and control over pore dimensions have remained relatively unsuccessful. Here, the colloidal assembly of silica nanoparticles into mesoporous silica microspheres (MSMs) is reported using a discrete set of silica sols within the confinement of a water‐in‐oil emulsion system. By studying the independent manipulation of different assembly parameters during the sol–gel process, a design strategy is outlined to synthesize MSMs with excellent reproducibility and independent control over pore size and overall porosity, which does not require additional ageing or post‐treatment steps to reach pore sizes as large as 50 nm. The strategy presented here can provide the necessary tools for the microstructural design of the next generation of tailor‐made silica microspheres for use in separation applications and beyond.     

蓝宝石衬底片的抛光研究

本研究对SiO2磨料抛光蓝宝石衬底片进行了研究,结果表明,采用大粒径、高浓度的SiO2磨料抛光可以获得良好的表面状态和较高的去除速率。抛光的适宜的温度及pH值条件为:T=30℃;13.0>pH≥9.0。并且在抛光时应加入适量添加剂,方可获得较为理想的表面状态和较高的去除速率。实验同样证明,这种低成本、高质量的抛光除可以应用在蓝宝石的抛光以外,还可以应用在其它一些硬质材料的抛光工艺中。     

Sub‐20 nm Magnetic Dots with Perpendicular Magnetic Anisotropy

A new and simple method for the preparation of magnetic dot arrays is introduced. Diblock copolymer micelles with a silica core are used as template for the generation of nanostructure arrays. The silica cores are utilized as mask for ion milling preparation. The morphology and size of the silica and magnetic dot arrays are discussed. The magnetic dots are made from Co/Pt multilayer films. Ferromagnetic dots with a diameter well below 20 nm and perpendicular easy axis of magnetization are created. The switching behavior changes from domain wall motion, dominant in the film, to single domain particle switching in the dots. The magneto‐optic saturation signals and the evolution of magnetic anisotropy are discussed.     

Effect of Ag-doped TiO2 thin film passive layers on the performance of photo-anodes for dye-sensitized solar cells

Ag-doped nanocrystalline structures of TiO₂ in the form of colloidal particles are synthesized by using AgNO₃ solution with Acetyl acetone and diacetyl monoxime modified titanium isopropoxide precursor. Thin layers of undoped and Ag-doped TiO₂ sols are deposited on conducting glass substrate by dip coating technique. The thin films are developed by repeated coating of the sols for 5, 10 and 15 times which results the formation of thin layers with different thickness. These layers are annealed at 450 °C so as to use them as bottom/ seed layers of fabricating photoanodes for dye sensitized solar cells. The optical properties of undoped and Ag-doped TiO₂ thin layers are studied in details. Effective mass model is used to find the particle size and peak wavelength relationship for the nanocrystals of TiO₂. Quantum efficiency of dye sensitized solar cells assembled using the fabricated photoanodes with Ag-doped TiO₂ shows increase in efficiency by about 4% in comparison to the undoped TiO₂ layers. The improved performance is attributed to ease of transportation of electron through passivating layer to the external circuit.     

Photoluminescence enhancement of quantum dots with photonic structures

Photoluminescence (PL) of CdSe/ZnS quantum dots (QDs) deposited on Si and photonic crystals with packed silica spheres, are investigated with the purpose of establishing enhancement of PL. Quantum dots with size ～2.4 nm are introduced into the solution containing silica spheres of ～345 nm size. Upon evaporation, QDs are incorporated into the photonic crystals made of close-pack spheres. We found that PL is red- or blue-shifted (from interaction with molecular complexes) with increase of QD-density. The broad PL emission is partly from particle size distribution, but mainly due to the interaction with local molecular complexes with surface quantum size effects. We have also observed enhanced interaction when the emission is close to the photons at the Brillouin zone boundary.