多重透射反射红外光谱（MTR-IR）测量晶硅薄片碳氧含量和晶硅表面高分子刷图案化

发布时间：2018-07-26 11:28

【摘要】：在CZ直拉法生产硅片的过程中,由于使用了石英(Si02)坩埚和石墨(C)加热部件,所以在熔硅过程中会不同程度地引入氧碳杂质。氧以间隙原子的形式存在于硅晶格中,故称间隙氧(InterstitialOxygen,Oi)。碳在硅晶体中取代硅原子的位置,称为代位碳(Substitutional Carbon,Cs)。间隙氧和代位碳是直拉(CZ)硅中氧碳的最主要存在形式,其含量的高低不仅影响硅材料的本征吸收,而且对材料的物理和导电特性产生影响。氧的不利之处是产生微缺陷,有利之处是对位错的延伸产生钉扎作用,增强硅片强度,其本征吸杂技术可防止生产工艺中缺陷的产生。高碳含量影响氧的成核和沉淀,还会导致器件软化特性和二次击穿。因此,硅中氧碳含量的控制成为改善材料性能的一种手段,然而,要控制氧碳含量首先必须测量准确。利用双嵌段共聚物聚苯乙烯-聚乙烯吡啶(polystyrene-block-poly-(4-vinyl pyridine),PS-b-P4VP;polystyrene-block-poly-(2-vinyl pyridine),PS-b-P2VP)在不同处理条件时发生相分离,产生一定规则图案的特性,把双嵌段共聚物制作成不同形貌的模版,如点状、直线条状、规则指纹状等。然后利用这些模版,通过氢氟酸(Hydroflouricacid,HF)腐蚀、氧等离子刻蚀、反应离子刻蚀(Reactive Ion Etching,RIE)等技术在硅片表面制作出各种由Si-Hx端和SiOx交替间隔组成的图案,然后再在这些图案基础上接种各种高分子刷,从而实现各种不同的功能,如集成电路、生物芯片、微型化学反应器等。本文中,一、我们利用多重透射-反射红外光谱(Multiple Transmission-Re flection Infrared Spectroscopy,MTR-IR)法对太阳能电池用单晶硅片、薄单晶硅片、多晶硅片中代位碳和间隙氧含量进行了红外定量分析和相关理论探讨。二、利用光刻技术和嵌段共聚物刻蚀技术在硅表面组装聚甲基丙烯酸(Polymethacrylic Ac-id,PMAA)、甲基丙烯酸羟乙酯(2-HydroxyethylMethacrylate,HEMA)、聚甲基丙烯酸甲酯(Polymethylmethacrylate,PMMA)、聚N-异丙基丙烯酰胺(N-Iso Propyl acrylamide,PNIPAM)聚合物刷,使之成较规则图案化分布。论文的主要研究内容与结果如下:1、MTR-IR法和IR法测量太阳能电池硅片中间隙氧与代位碳含量的比较研究。我们最近开发了一种多重透射-反射傅立叶变换红外光谱法(MIR-IR)用于测量太阳能电池硅片中间隙氧(Oi)和代位碳(Cs)含量,并和传统的IR(Infrared)法进行了比较,结果发现在1107 cm-1附近的氧吸收峰可以实现信号放大9~10倍,在605 cm-1处碳吸收峰可以实现信号放大7~8倍,从而可以将原有检测限降低一个数量级,提高检出的灵敏度。多次重复测量的结果证实了 MTR-IR法的准确性与重现性。另外,相比较于垂直入射和布儒斯特角单次透射,MTR法可以极大程度地减少薄硅片(厚度≤ 0.3 mm)内部多重反射透射引起的干涉条纹的振幅。并对干涉条纹减少的机理进行了探讨。一是积分球作用(相消干涉)即反射光和透射光的波峰与波谷分别加和抵消;二是布儒斯特角时p偏振光没有反射(硅片内部不产生反射),全部透过,从而减少干涉条纹。并利用p偏振光计算公式对0.1mm、0.2 mm薄硅片中的代位碳、间隙氧含量进行了计算。对s偏振光和p偏振光的薄硅片红外图谱进行了模拟,并解释了 p偏振吸收峰总是比s偏振吸收峰高的原因。对多晶硅中碳氧含量分布情况进行了分析,对1.0 mm多晶硅中间隙氧和代位碳含量进行了测量,并和IR法进行了比较,无论从准确性还是从重现性均优于IR法。2、嵌段共聚物PS-b-P4VP为模版制备高分子刷点阵纳米图案。两亲性嵌段共聚物PS-b-P4VP在甲苯溶液里自组装成胶束,旋涂在硅片上形成PS作基质背景、P4VP形成突出于PS基质背景的50~80nm的圆点,用稀HF溶液腐蚀得到了孔径分布在50～80 nm之间较均匀的圆形纳米坑,腐蚀的机理是因P4VP胶束亲水、而且HF能使P4VP中的吡啶环质子化,故蚀刻选择性地发生在P4VP胶束的下方。先用稀HF溶液腐蚀平面硅得到表面悬挂的Si-Hx键,再通过硅氢化反应共价偶联上末端带叔烷基溴引发基团的单分子膜,末端叔烷基溴能引发表面原子转移自由基聚合反应(Surface-Induced Atom Transfer Rad icalPolymerization,SI-ATRP),使用单体甲基丙烯酸羟乙酯(HEMA)、甲基丙烯酸钠(NaMA)、甲基丙烯酸甲酯(MMA)、N-异丙基丙烯酰胺(NIPAM)在硅表面经 SI-ATRP 组装了多种聚合物刷 Si-g-Poly(HEMA/PMAA/PMMA/PNIPAM),得到了凸出表面的点阵状图案。整个过程用多次透射反射红外光谱(MTR-IR),原子力显微镜(AFM)和扫描电子显微镜(SEM)进行检测,证实了在硅表面聚合物刷图案阵列的形成过程。3、嵌段共聚物PS-b-P2VP为模版制备高分子刷线状或指纹状纳米图案。两亲性嵌段共聚物PS-b-P2VP在甲苯溶液里自组装成胶束,旋涂在硅片上形成PS作基质背景、P2VP形成突出于PS基质背景的20～30 nm的圆点。然后在10:1 THF/H2O溶剂蒸汽密闭环境中室温下放置30～40 h,形成PS-b-P2VP直线条或指纹状图案,然后在Na2PtCl4/HCl溶液中浸泡3～24 h,带正电荷的[P2VP]+和带负电荷的[PtCl4]2-静电吸引结合在一起,用O2等离子体处理除去PS-b-P2VP,同时使Na2PtCl4生成Pt线条。用1:1:4 HF/H2O2/EtOH的阳极辅助溶液腐蚀得到了间距在50～80nm之间,带宽30～50 nm的线状或指纹状条纹,腐蚀的机理是Pt所处位点的原电池反应机理,最后在线状条纹的纳米坑处组装PMAA,得到线条状或指纹状的PMAA图案。图案的形貌用扫描电子显微镜(SEM)和原子力显微镜(AFM)进行观测。
[Abstract]:In the process of producing silicon wafers by CZ direct drawing, because of the use of quartz (Si02) crucible and graphite (C) heating components, oxygen carbon impurities will be introduced to different degrees in the process of melting silicon. Oxygen is in the form of interstitial atoms in the form of interstitial oxygen (InterstitialOxygen, Oi). The position of carbon in silicon crystal is called substitution of silicon atoms. Substitutional Carbon (Cs). Interstitial oxygen and subrogation carbon are the most important forms of oxygen and carbon in Si (CZ) silicon. Their content not only affects the intrinsic absorption of silicon materials, but also influences the physical and electrical properties of the materials. The disadvantage of oxygen is to produce micro defects, and the advantage is to produce pinning effect on the extension of dislocation. In order to enhance the strength of the silicon wafer, its intrinsic impurity absorption technology can prevent the production of defects in the production process. The high carbon content affects the nucleation and precipitation of oxygen, and also leads to the softening and two breakdown of the devices. Therefore, the control of oxygen and carbon content in silicon becomes a means to improve the material performance. However, the control of oxygen carbon content must first be measured accurately. A double block copolymer polystyrene polyvinyl pyridine (polystyrene-block-poly- (4-vinyl pyridine), PS-b-P4VP; polystyrene-block-poly- (2-vinyl pyridine), PS-b-P2VP) is separated at different treatment conditions and produces a certain rule pattern. The double block copolymer is made into a template with different morphologies, such as dot and linear strip. And then using these templates, using Hydroflouricacid (HF) corrosion, oxygen plasma etching, reactive ion etching (Reactive Ion Etching, RIE), and other techniques, such as Reactive Ion Etching, RIE, and other techniques made of alternating intervals of Si-Hx ends and SiOx, and then inoculating various polymer brushes on the basis of these patterns. To achieve various functions, such as integrated circuits, biochips, micro chemical reactors, and so on. In this paper, in this paper, we use Multiple Transmission-Re flection Infrared Spectroscopy (MTR-IR) method for single crystal silicon, thin monocrystalline silicon, and interstitial carbon and interstitial oxygen in solar cells. The content was analyzed by infrared quantitative analysis and related theory. Two, using photolithography and block copolymer etching technology to assemble polymethacrylic acid (Polymethacrylic Ac-id, PMAA), hydroxyethyl methacrylate (2-HydroxyethylMethacrylate, HEMA), Polymethylmethacrylate, PMMA, poly N- isopropyl on the silicon surface N-Iso Propyl acrylamide (PNIPAM) polymer brushes make it more regular patterned. The main contents and results of this paper are as follows: 1, MTR-IR and IR methods for measuring the content of intermediate gap oxygen and subrogation carbon in solar cell silicon wafers. We have recently opened a multiple transmission reflection Fu Liye transform infrared spectroscopy. The method (MIR-IR) is used to measure the content of intermediate gap oxygen (Oi) and subrogation carbon (Cs) in solar cell silicon. Compared with the traditional IR (Infrared) method, it is found that the oxygen absorption peak near 1107 cm-1 can enlarge the 9~10 times of the signal amplification, and the carbon absorption peak at 605 cm-1 can magnify the signal 7~8 times, thus the original detection limit can be reduced. The results of repeated measurements confirm the accuracy and reproducibility of the MTR-IR method. In addition, compared to the vertical incidence and the single transmission of Brewster angle, the MTR method can greatly reduce the amplitude of the interference fringes caused by the multiple reflection and transmission of the thin silicon wafer (thickness less than 0.3 mm). The mechanism of stripe reduction is discussed. One is the integral ball effect (cancellation interference), that is, the wave peak of reflected light and transmitted light is added and offset respectively. Two is that the P polarized light is not reflected in the Brewster angle (no reflection inside the silicon wafer), and all through, thus reducing the dry fringe. And using the P polarized light calculation formula to 0.1mm, 0.2 mm thin. The substitution carbon and the gap oxygen content in the silicon wafer were calculated. The infrared spectra of the thin silicon wafers with S polarized light and P polarized light were simulated, and the reason that the p polarization absorption peak was always higher than the S polarization absorption peak was explained. The distribution of carbon and oxygen content in the polysilicon was analyzed, and the middle gap oxygen and the subrogation carbon content of the 1 mm polysilicon were carried out. The measurements were compared with the IR method. Both the accuracy and the reproducibility were better than the IR.2, and the block copolymer PS-b-P4VP was used as a template to prepare the polymer brush lattice nanoscale pattern. The two amphiphilic block copolymer PS-b-P4VP was self assembled into a micelle in the toluene solution, and PS was formed on the silicon wafer to form a matrix background, and P4VP formed out of the PS matrix back. The circular point of the 50~80nm in the scene is corroded by a dilute HF solution. The corrosion mechanism is that the P4VP micelle is hydrophilic and the HF can make the pyridine rings protonated in P4VP, so the etching selectively occurs under the P4VP micelles. The surface suspended Si-H is obtained by etching the plane silicon with a dilute HF solution. The X bond is covalently coupled to the monolayer of the terminal alkyl bromide initiator by the hydrosilylation reaction, and the terminal TERT alkyl bromide can trigger the surface atom transfer radical polymerization (Surface-Induced Atom Transfer Rad icalPolymerization, SI-ATRP), using the monomer methyl methacrylate (HEMA), sodium methacrylate (NaMA), methyl propyl Methyl enate (MMA) and N- isopropyl acrylamide (NIPAM) have been assembled on the silicon surface by a variety of polymer brushes, Si-g-Poly (HEMA/PMAA/PMMA/PNIPAM), and a lattice pattern on the convex surface is obtained. The whole process is detected by multiple transmission reflectance infrared spectroscopy (MTR-IR), atomic force microscopy (AFM) and scanning electron microscopy (SEM). The formation process of the polymer brush pattern array on the silicon surface.3, the block copolymer PS-b-P2VP is used as a template to prepare the polymer brushed linear or fingerprint like nanoscale pattern. Two Pro block copolymer PS-b-P2VP is self assembled into a micelle in the toluene solution, and PS is formed on the silicon wafer to form a matrix background, and P2VP forms a 20~30 nm that outburst the background of the PS matrix. And then put 30~40 h at room temperature at room temperature in a 10:1 THF/H2O solvent vapor tight environment, forming a PS-b-P2VP straight strip or fingerprint pattern, then soaking 3~24 h in Na2PtCl4/HCl solution, combining positive charge [P2VP]+ with negative charged [PtCl4]2- electrostatic attraction together, removing PS-b-P2VP with O2 plasma treatment, and making Na2 PtCl4 generates Pt lines. Using 1:1:4 HF/H2O2/EtOH anode assisted solution corrosion, the linear or fingerprint stripes between 50 and 80nm and 30~50 nm are obtained. The mechanism of corrosion is the primary cell reaction mechanism at the site of Pt. Finally, the PMAA is assembled at the nanoscale pits at the line stripe. The pattern of line or fingerprint like PMAA pattern is obtained. The morphology was observed by scanning electron microscope (SEM) and atomic force microscope (AFM).
【学位授予单位】：南京大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ127.2

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