LPCVD掺氧多晶硅电学特性研究

本文通过测量电导率特性对LPCVD掺氧多晶硅(SIPOS)的电学特性进行了研究。结果表明,SIPOS的电学特性与其含氧量和退火温度有关。SIPOS的含氧量增加,其电导率下降;在退火过程中,随退火温度的不同,SIPOS的电导率的变化存在两个不同过程:低温退火过程中,电导率的变化与SIPOS中的Si-O键的分布和作用有关;而在高温退火过程中,电导率的变化则是SIPOS薄膜再结晶的结果。本文对SIPOS的掺杂效应也进行了研究。结果表明,SIPOS掺杂后电导率明显提高;而含氧量对掺杂后的SIPOS的电导率的提高具有明显的抑制作用。     

多晶硅薄膜高温退火特性研究分析

利用原子力显微镜、二次离子质谱分析仪和探针,对多晶硅薄膜的高温退火特性进行了实验研究。研究结果表明,多晶硅薄膜退火时出现的第二次反退火阶段,其物理起因是由于注入杂质在薄膜中的再分布;而在更高退火温度下,多晶硅薄膜会出现晶粒再结晶和再结晶弛豫过程,这些过程都会影响多晶硅薄膜的薄层电阻。     

用Raman光谱研究掺氧多晶硅的微结构

本文用Raman谱特征和Raman峰强度的变化,揭示掺氧多晶硅(SIPOS)的微结构:对于各种氧含量(从8％到38％)的SIPOS生长膜是一种无序结构,其中元素Si呈无定形相.高温(T>900℃)热退火后,薄膜经历了一个再结晶过程,并出现了微晶区,Si微晶尺寸随退火温度的提高而增大.膜中氧浓度增加对微晶生长有抑制作用,故膜中氧含量增加将使Si晶粒度减小,或者相应的使薄膜再结晶的温度提高.     

一类新型的薄膜多晶硅材料与器件的制备方法及其研究现状

本文介绍一类新型的薄膜多晶硅材料及器件的制备方法－后续退火方法并对其研究现状进行评述。对制备过程中初始材料的沉积条件，后续退火条件、以及后氢化处理等诸多环节对薄膜多晶硅材料的性能的影响进行了讨论。最后介绍了用后续退火方法制备薄膜多晶硅太阳电池及多晶硅薄膜场效应管的研究结果。     

快速光热退火法制备多晶硅薄膜的研究

为了制备应用于太阳电池的优质多晶硅薄膜,研究了非晶硅薄膜的快速光热退火技术。先利用 PECVD 设备沉积非晶硅薄膜,然后放入快速光热退火炉中进行退火。退火前后的薄膜利用 X 射线衍射仪(XRD)和扫描电子显微镜(SEM)测试其晶体结构及表面形貌,用电导率设备测试其暗电导率。研究表明退火温度、退火时间对非晶硅薄膜的晶化都有很大的影响,光热退火前先用常规高温炉预热有助于增大多晶硅薄膜的晶粒尺寸和暗电导率。     

多晶硅电学特性研究之Ⅵ:高阻多晶硅的电学性质

对砷离子注入的轻掺杂多晶硅进行了系统的实验,研究了高阻多晶硅电学特性与薄膜淀积温度,注入剂量,退火温度,退火时间和热处理周期等处理条件的关系。结果表明淀积系统的温度梯度分布使薄膜的电参数均匀性差;高阻多晶硅的电阻率对注入剂量的变化十分敏感,高温下长时间退火将使电阻率增加;轻掺杂多晶硅中的“杂质分凝”是不可逆的。高值电阻电参数调整实验也取得了较好的结果。这项工作揭示了高阻多晶硅一些未见指道过的重要性质,我们提出的晶界中的氧俘获态模型成功地解释了这些现象。     

微波退火非晶硅薄膜低温晶化研究

多晶硅薄膜晶体管以及其独特的优点在液晶显示领域中起着重要的作用。为了满足在普通玻璃衬底上制备多晶硅薄膜晶体管有源矩阵液晶显示器,低温制备（＜600℃高质量多晶硅薄膜已成为研究热点。文章研究了一种低温制备多晶硅薄膜的新工艺;微波退火非晶硅薄膜固相晶化法,利用X射线衍射、拉曼光谱和扫描电镜分析了微波退火工艺对非晶硅薄膜固相晶化的影响,成功实现了低温制备多晶硅薄膜。     

溅射GaAs SOI电子束退火再结晶及MBE GaAs SOI高频感应石墨棒热退火再结晶

本文首次报道了溅射GaAs SOI电子束退火再结晶以及MBE GaAs SOI高频感应石墨棒热退火再结晶.对实验所得SOI样品,用ED和TEM分析GaAs 薄膜的结晶性,用X-射线衍射测量薄膜表面的择优取向,用霍耳效应测量定出载流子浓度和迁移率.     

快速热处理引起的硅化钨薄膜电导率的变化

在VLSI里,多晶硅栅的一些局限性异致了可替换多晶硅的难熔金属硅化物/多晶硅材料的发展。近来,我们研究了适合用来对这种多晶硅难熔金属硅化物(Polycide,以下简称多晶硅化物),薄膜进行退火的快速热处理技术。我们这里所报道的是CVD硅化钨薄膜在快速热退火过程中电异率的变化。研究表明,电阻率开始增加是因为Si/W比的变化。后来大约下降到初始值的十分之一,由此提出了降低用作VLSI互连线的硅化钨膜的电阻率所需要的最短热处理时间和功率。     

微波退火法低温制备多晶硅薄膜晶体管

多晶硅薄膜晶体管以其独特的优点在液晶显示领域中有着重要位置。为了满足在普通玻璃衬底上制备多晶硅薄膜晶体管有源矩阵液晶显示器,低温制备（小于600℃）高质量多晶硅薄膜已成为研究热点,文章利用微波加热技术,采用非晶硅薄膜微波退火固相晶化法低温制备出多晶硅薄膜晶体管,研究了微波退火工艺对多晶硅薄膜晶体管电学性能的影响。     

Effects of oxygen on crystallization of amorphous silicon films and polysilicon TFT characteristics

Oxygen ions were implanted into the amorphous silicon film deposited at 540°C in order to study the effects of oxygen on the solid phase crystallization of silicon films. The resulting films were investigated using transmission electron microscopy, x-ray diffraction (XRD), and also by measuring the electrical characteristics of polycrystalline silicon thin film transistors (TFTs) fabricated in the crystallized films. The development of {111} texture as a function of annealing time is similar to films implanted with Si, with higher oxygen samples showing more texture. Transmission electron microscopy shows that the grain size of completely crystallized films varies little with oxygen concentration. The electrical performances of TFTs are found to degrade with increasing oxygen dose. The trap state density increases from 5.6 × 10¹²/cm² to 9.5 × 10¹²/cm² with increasing oxygen dose. It is concluded that for a high performance TFT, oxygen incorporation in the Si film should be kept to 10¹⁹/cm³ or less.     

离子束增强沉积法制备二氧化铪薄膜

利用离子束增强沉积(IBED)技术在硅衬底上沉积得到50nm的二氧化铪薄膜.卢瑟福背散射(RBS)的结果指出样品表面有过量氧元素存在.X射线光电子能谱(XPS)显示退火前后薄膜内部化学键没有变化.透射电子显微镜(TEM)表明界面处有非晶铪氧硅化合物生成.电子衍射(ED)显示所制备的二氧化铪薄膜呈现长程无序、区域有序的多晶态.实验为HfO2作为高k电介质在集成电路制造中的应用提供了一种简单有效的方法.     

Infrared spectroscopy and transmission electron microscopy of polycrystalline silicon carbide

The polycrystalline structure of silicon carbide was investigated by infrared spectroscopy and transmission electron microscopy (TEM). The films were obtained by annealing in the temperature range 950–1250°C of amorphous silicon carbide films deposited on a silicon substrate by PECVD. The broad absorption band at around 750 cm⁻¹ in the infrared spectrum of amorphous material after annealing at high temperature changes from a Gaussian to a Lorentzian shape, corresponding to the transition from an amorphous to a polycrystalline phase. The SiC peak becomes sharper with increasing the annealing temperature, this effect being related to the growth of crystalline grains. TEM microscopy indicates that the crystallisation occurs homogeneously in the films and the diffraction pattern shows that the film crystallises into cubic 3C–SiC. The distribution of polycrystalline grains as determined by TEM evidences an increase of the grain size with increasing the annealing temperature. A correlation between infrared peak width and mean grain radius has been found.     

Annealing effects on the formation of semiconducting Mg2Si film using magnetron sputtering deposition

Semiconducting Mg2Si films were synthesized on silicon (11 1) substrates by magnetron sputtering deposition and subsequent annealing in an annealing furnace filled with argon gas,and the effects of heat treatment on the formation and microstructure of Mg2Si films were investigated.The structural and morphological properties were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM),respectively.The results show that the crystal quality of Mg2Si films depends strongly on the annealing temperature,the annealing time and the deposited magnesium film thickness.Annealing at 400 ℃ for 5 h is optimal for the preparation of Mg2Si film.XRD and SEM results show that magnesium silicide film with various orientations is formed on the silicon surface because of the interdiffusion and reaction of magnesium with substrate silicon atoms,and the evolution of surface features on growing films is very dependent on the annealing temperature and time.     

Role of impurities in the formation of silicyne (long-chain silicon): Theory and experiment

The short-range order structure of amorphous silicon prepared by various methods is investigated by electron diffraction analysis. The influence of impurities in the as-prepared films and those irradiated with neon, oxygen, and carbon ions at doses up to 1×10¹⁶ cm⁻² on the character of structural transformations and the formation of interatomic silicon multiple bonds during annealing are investigated. The structure of films annealed at 500 °C is found to depend on the type of impurities and the nature of their chemical bond with silicon atoms. In particular, oxygen (>0.2 at. %), unlike hydrogen and carbon, acts as an inhibitor for the formation of silicyne. Good agreement is also noted between the experimentally determined short-range order parameters and those calculated by the nonempirical Hartree-Fock method. Fiz. Tekh. Poluprovodn. 33, 1253–1259 (October 1999)     

Effects of annealing temperature and surface preparation on the formation of cobalt silicide interconnects

Cobalt silicide films have been prepared by rapid thermal annealing of cobalt layers sputter deposited on silicon substrates. We report on the evolution of silicide phases, surface and interface roughness as a function of the annealing temperature and silicon surface preparation. The characterizations are carried out by atomic force microscopy, X-ray diffraction, X-ray reflectivity, Raman spectroscopy, and transmission electron microscopy. The cleaning procedure of the silicon substrate affects the interface roughness and the silicide thickness, whereas little effects are found on the surface. On the other hand, surface roughness increases with annealing temperature.     

Preliminary study on pyroelectric lithium tantalite by a novel electrostatic spray pyrolysis technique

In this paper, we report the first results obtained for pyroelectric LiTaO₃ thin films prepared on silicon substrates by electrostatic spray pyrolysis (ESP), a simple, low cost and efficient technique not widely used for LiTaO₃ deposition, using lithium acetylacetonate and tantalum ethoxide in a mixture of methanol. The effect of the growth and annealing temperature on the structural and optical properties has been investigated. X-ray diffraction measurements have shown that LiTaO₃ thin films became preferentially oriented in the (0,1,2) plane after annealing treatment in an oxygen environment using the rapid thermal processing. On the other hand, a thermal stress's modeling is performed to observe the effect of growth temperature on the as-deposited films and the substrates. The SEM images have shown that the film heat-treated at 600 °C became more homogeneous and smoother than that before annealing. The optical phonon modes of the LiTaO₃ thin films have been also investigated using infrared reflectivity (FTIR) and Raman spectroscopy.     

（英）退火温度对电子束蒸发沉积硅薄膜结构和光学性能的影响

系统研究了退火温度对硅薄膜结构和光学性能的影响。通过电子束蒸发工艺制备硅薄膜,然后在氮气保护下对薄膜样品在200~500°C范围内进行退火处理。使用XRD、拉曼光谱、电子自旋共振和透射光谱测量等方法对薄膜样品进行了表征。结果显示,随着退火温度的升高,非晶硅薄膜结构有序度在短程和中程范围内得到改善,同时缺陷密度显著降低-。当样品在400°C退火后,消光系数k由6.14×10^-3下降到最小值1.02×10~3(1000 nm),这是由于此时硅薄膜缺陷密度也降到最低,约为沉积态薄膜的五分之一。试验结果表明,硅薄膜在适当的温度下退火可以有效地降低近红外区膜层的光学吸收,这对硅薄膜在光学薄膜器件研制中具有重要应用。     

离子束增强沉积氮化硅薄膜生长及其性能研究

用离子束增强沉积技术合成了氮化硅薄膜并研究了薄膜的组分、性能和结构.结果表明,离子束增强沉积生长的氮化硅薄膜的组分比,可借助于调节氮离子和硅原子到达率之比加以控制.在合适条件下生长的氮化硅薄膜,其红外吸收特征峰在波数为840cm~(-1)附近,光折射率在2.2到2.6之间,其组分为Si_3N_4用RBS、AES、TEM、SEM、ED及扩展电阻,测量和观察生成的氮化硅薄膜的组分深度分布及结构.发现,离子束增强沉积制备的氮化硅薄膜,存在着表面富硅层、氮化硅沉积层及混合过渡层这样的多层结构.薄膜呈球状或方块状堆积.基本上是无定形相,但局部可观察到单晶相的存在.离子束增强沉积制备的氮化硅薄膜中的含氧量比不用离子束辅助沉积的显著减少.     

Investigation into Texture,Preferential Orientation,and Optical Properties of Zinc Oxide Nanopolycrystalline Thin Films Deposited by the Sol–Gel Technique on Different Substrates

ZnO nanopolycrystalline thin films were deposited by the sol–gel technique on glass and silicon, and compared systematically via atomic force microscopy, scanning electron microscopy, x-ray diffraction, UV–Vis spectrophotometry, and fluorescence spectrophotometry. The thickness of the ZnO films was measured by ellipsometric microscopy. A higher preheating temperature was needed to obtain films with a strong preferential orientation. The optimal annealing temperatures for c-axis films on glass and silicon substrates were 525°C and 750°C, respectively. The relative intensity of the blue–green emission peak tends to increase with the annealing temperature. When the film is annealed in N₂, the transmittance of the film reduces while the intensity of the blue–green emission increases.