原子层沉积方法制备低温多层Al2O3/TiO2复合封装薄膜的研究

原子层沉积(ALD)方法可以制备出高质量薄膜,被认为是可应用于柔性有机电致发光器件(OLED)最有发展前景的薄膜封装技术之一。本文采用原子层沉积(ALD)技术,在低温(80℃)下,研究了Al₂O₃及TiO₂薄膜的生长规律,通过钙膜水汽透过率(WVTR)、薄膜接触角测试等手段,研究了不同堆叠结构的多层Al₂O₃/TiO₂复合封装薄膜的水汽阻隔特性,其中5 nm/5 nm×8 dyads(重复堆叠次数)的Al₂O₃/TiO₂叠层结构薄膜的WVTR达到2.1×10^-5 g/m²/day。采用优化后的Al₂O₃/TiO₂叠层结构薄膜对OLED器件进行封装,实验发现封装后的OLED器件在高温高湿条件下展现了较好的寿命特性。     

有机电致发光器件的新型薄膜封装技术研究

针对有机电致发光器件(OLED)在空气中水汽和O2作用下寿命下降的问题,提出一种对OLED进行薄膜封装方法。封装薄膜由电子束蒸镀Al2O3薄膜和原子层沉积(ALD,atomic layer deposition)Al2O3薄膜相结合形成。利用Ca薄膜电学测试方法测定封装薄膜的水汽透过率(WVTR)。具体实现方法是,采用玻璃作为衬底,在100nm的Al电极上蒸镀200nm的Ca膜,然后对整个系统进行薄膜封装,只留出Al电极的一部分作为探针接触电极。实验发现,采用电子束蒸镀结合ALD的Al2O3薄膜封装,Ca薄膜变成透明的时间比未封装或采用单一结构封装得到了延长。为了检验薄膜封装效果,制作了一组绿光OLED,器件结构为ITO/MoOX(5nm)/mMTDATA(20nm)/NPB(30nm)/Alq3(50nm)/LiF(1nm)/Al,实验结果表明,本文提出的薄膜封装方法对器件进行封装,器件的寿命得到了延长。     

利用ICPCVD方法在GaN上沉积氧化硅薄膜的特性

使用感应耦合等离子体化学气相沉积(Inductively coupled plasma chemical vapor deposition,ICPCVD)方法在GaN上沉积SiOx薄膜,生长参数中采用不同RF功率,研究RF功率对薄膜物理性能和电学性能的影响.结果发现,随着RF功率增大,薄膜应力增大,表面粗糙度减小,薄膜致密度增大.选择最优的RF功率参数,制作了SiOx/nGaN金属-绝缘体-半导体(metal-insulator-semiconductor,MIS)器件,结果得到薄膜漏电流密度在外加偏压为90V时小于1×10-7A/cm2,SiOx/n-GaN界面态密度为2.4×1010eV-1cm-2.表明利用ICPCVD低温沉积的SiOx-GaN界面态密度低,薄膜绝缘性能良好.     

基于ALD技术的高性能光电探测器研究进展

采用原子层沉积(ALD)技术制备的薄膜具有致密性高、保形性高、平滑性好、缺陷密度低、厚度可精准调控等优势,被广泛应用于各类光电器件中.利用ALD技术制备的功能薄膜可以明显改善光电探测器的暗电流、探测率和线性动态范围等性能.以基于ALD技术的高性能光电探测器为主题,首先详细介绍了热ALD生长薄膜的基本原理,同时简要介绍了等离子体增强ALD技术生长薄膜的基本原理.然后依据光电探测器中薄膜的功能不同,依次总结了基于ALD技术制作的活性层、钝化层、界面层、电荷传输层等实现高性能光电探测器的研究进展.最后对ALD技术在光电探测器领域的发展趋势和挑战进行了展望.     

无氨氮化硅薄膜在MEMS硅腐蚀中的应用

研究了等离子体增强化学汽相淀积(PECVD)生长的无氨氮化硅薄膜作为掩蔽层在MEMS硅腐蚀工艺中的应用。比较了PECVD不同工艺条件(衬底温度和功率)以及不同四甲基氢氧化铵(TMAH)硅腐蚀液温度对无氨氮化硅薄膜硅腐蚀掩蔽效果的影响。通过优化无氨氮化硅薄膜生长条件和硅腐蚀液温度,得到了高质量的氮化硅薄膜,颗粒以及针孔密度较少,0.2μm以上颗粒度小于100,提高了硅腐蚀掩蔽选择比。实验结果显示优化生长条件的氮化硅薄膜(衬底温度350℃,功率30 W),在85℃的TMAH硅腐蚀液中,硅的腐蚀速率为68μm/h,氮化硅薄膜腐蚀速率为33.2 nm/h,硅与氮化硅的腐蚀选择比为2 048,满足MEMS体硅腐蚀工艺对于掩膜特性的要求。     

化合物半导体

0003573气相沉积法分子筛封装 SnO_2纳米半导体材料的研究[刊]/张义华//功能材料.—1999,30(6).—651～652,662(C)0003574SnO_2/Fe_2O_3纳米复合粉的制备与表征[刊]/潘登余//功能材料与器件学报.—1999.5(4).—323～326(C)0003575正交实验方法研究 PECVD 碳化硅薄膜的防水汽扩散性质[刊]/姜利军//功能材料与器件学报.—1999,5(4).—318～322(C)0003576     

PECVD SiON膜的性质及其在双层互连工艺中的应用

我们在研制和生产双层布线的 3μm CMOS LSI器件时,采用了 PECVD SiON(等离子增强化学气相沉积的氮氧化硅)膜作金属层之间的绝缘层.这种薄膜具有很小的压应力,很低的针孔密度,良好的台阶覆盖性等优点.这种绝缘膜是采用PECVD沉积工艺,以氮冲稀的低浓度SiH_4(3％)和N_2O气体为原料制得的. 本文着重介绍 PECVD SiON膜的性质及其在双层互连工艺中的应用.     

晶体硅太阳电池减反射膜的研究

在太阳电池表面形成一层减反射薄膜是提高太阳电池的光电转换效率比较可行且降低成本的方法。应用PECVD（等离子体增强化学气相沉积）系统,采用SiH4和NH3气源以制备氮化硅薄膜。研究探索了PECVD生长氮化硅薄膜的基本物化性质以及在沉积过程中反应压强、反应温度、硅烷氨气流量比和微波功率对薄膜性质的影响。通过大量实验,分析了氮化硅薄膜的相对最佳沉积参数,并得出制作减反射膜的优化工艺。     

原子层沉积技术制备金属材料的进展与挑战

原子层沉积(ALD)技术是一种三维共形沉积金属薄膜或金属纳米结构的有效手段。简要介绍了ALD技术的基本原理和特点,着重阐述和比较了ALD生长贵金属、过渡金属和活泼金属的不同工艺条件、化学过程和反应生长机理,如贵金属的燃烧反应与成核孕育期、过渡金属铜互连的前驱体与表面平整性以及活泼金属的能量辅助沉积,探讨了前驱体、成核等对金属沉积和质量的重要影响,说明了原位监控手段在生长中的作用。最后简述了ALD沉积金属面临的瓶颈,由于一些重要金属前驱体的匮乏,新的反应路径和生长机理亟待发现,并展望了其未来发展和应用前景。     

快速热处理对PECVD氮化硅薄膜性能的影响

利用PECVD在硅片上沉积了氮化硅(SiNx)薄膜,将沉积膜后的样品放在N2气氛中进行快速热处理(RTP),研究了不同快速热处理对PECVD氮化硅薄膜件能的影响.采用原子力显微镜(AFM)检测薄膜的表面形貌,利用椭圆偏振仪测量样品膜厚和折射率,利用准稳态光电导衰减法(QSSPCD)测鼋样品的少子寿命.实验结果表明随着RTP温度的升高,薄膜厚度迅速减小,折射率迅速增大;低于500℃热处理时,少子寿命基本不变;高于500℃热处理时,随着温度的升高,少子寿命急剧下降.氮化硅薄膜经热处理后反射率基本不变.     

Thermal Conductivity and Phonon Scattering Processes of ALD Grown PbTe–PbSe Thermoelectric Thin Films

This work studies the thermal conductivity and phonon scattering processes in a series of n‐type lead telluride‐lead selenide (PbTe–PbSe) nanostructured thin films grown by atomic layer deposition (ALD). The ALD growth of the PbTe–PbSe samples in this work results in nonepitaxial films grown directly on native oxide/Si substrates, where the Volmer–Weber mode of growth promotes grains with a preferred columnar orientation. The ALD growth of these lead‐rich PbTe, PbSe, and PbTe–PbSe thin films results in secondary oxide phases, along with an increase microstructural quality with increased film thickness. The compositional variation and resulting point and planar defects in the PbTe–PbSe nanostructures give rise to additional phonon scattering events that reduce the thermal conductivity below that of the corresponding ALD‐grown control PbTe and PbSe films. Temperature‐dependent thermal conductivity measurements show that the phonon scattering in these ALD‐grown PbTe–PbSe nanostructured materials, along with ALD‐grown PbTe and PbSe thin films, are driven by extrinsic defect scattering processes as opposed to phonon–phonon scattering processes intrinsic to the PbTe or PbSe phonon spectra. The implication of this work is that polycrystalline, nanostructured ALD composites of thermoelectric PbTe–PbSe films are effective in reducing the phonon thermal conductivity, and represent a pathway for further improvement of the figure of merit (ZT), enhancing their thermoelectric application potential.     

TEOS-based PECVD of silicon dioxide for VLSI applications

Silicon dioxide films deposited from tetraethylorthosilicate (TEOS) using plasma-enhanced chemical vapour deposition (PECVD) are reviewed. The effect of the presence of oxygen on the film deposition rate and mechanism and the physical properties of the films, particularly the step coverage properties (conformality), are discussed in detail. Structural characterisation of the films has been carried out via etch rate measurements, infrared transmission spectroscopy, X-ray photoelectron spectroscopy (XPS) and Auger and secondary ion mass spectroscopy (SIMS) analysis. Electrical properties, i.e. resistivity, breakdown strength, fixed oxide charge density, interface state density and trapping behaviour, have been evaluated using metal-oxide-semiconductor (MOS) structures fabricated using the deposited oxides. Films deposited by microwave plasma-enhanced decomposition of TEOS in the presence of oxygen have been found to be comparable with standard silane-based low-pressure chemical vapour deposition (LPCVD) and PECVD oxides. It has been shown that films deposited on thin native oxides grown by either in situ plasma oxidation or low-temperature thermal oxidation exhibit excellent electrical properties.     

PECVD制备SiOx-SiNx薄膜的研究

首先使用工业型Direct-PECVD设备,采用SiH4和N2O制备了SiOx薄膜.针对Si太阳电池的应用,比较了SiOx薄膜在不同射频功率、气压、气体流量比和温度下的沉积特性,得出了最佳的沉积条件,这些沉积特性包括沉积速率、折射率和腐蚀速率.在该条件下沉积的SiOx膜均匀性良好、结构致密、沉积速率稳定,其性能满足了现阶段Si太阳电池对减反钝化层的光学和电学性能方面的要求.然后制备了SiOx-SiNx叠层减反钝化膜,并比较了SiO2与SiNx单层膜的减反和钝化效果,结果显示SiOx-SiNx叠层膜在不增加反射率的同时显著提高了Si片的钝化效果.     

Modeling the growth of PECVD silicon nitride films for solar cellapplications using neural networks

Silicon nitride films grown by plasma-enhanced chemical vapor deposition (PECVD) are useful for a variety of applications, including anti-reflection coatings in solar cells, passivation layers, dielectric layers in metal/insulator structures, and diffusion masks, PECVD nitride films are known to contain hydrogen, and defect passivation by hydrogenation enhances efficiency in polycrystalline silicon solar cells. PECVD systems are controlled by many operating variables, including RF power, pressure, gas flow rate, reactant composition, and substrate temperature. The wide variety of processing conditions, as well as the complex nature of particle dynamics within a plasma, makes tailoring Si₃N₄ film properties very challenging, since it is difficult to determine the exact relationship between desired film properties and controllable deposition conditions. In this study, silicon nitride PECVD modeling using neural networks has been investigated. The deposition of Si₃N₄ was characterized via a central composite experimental design, and data from this experiment was used to train optimized feed-forward neural networks using the back-propagation algorithm. From these neural process models, the effect of deposition conditions on film properties has been studied. It was found that the process parameters critical to increasing hydrogenation and therefore enhancing carrier lifetime in polysilicon solar cells are temperature, silane, and ammonia flow rate. The deposition experiments were carried out in a Plasma Therm 700 series PECVD system     

Electrical characteristics of very thin SiO2deposited at low substrate temperatures

Very thin (≲ 100-Å) films of SiO2have been deposited by a modified plasma-enhanced chemical-vapor deposition (PECVD) process at very low substrate temperatures (≲ 350°C). Low flow rates of reactive gases and a high flow of inert carrier gas were used to lower the deposition rate, ensuring improved dielectric properties and good control over film thickness. Measurements made on MOS capacitors of current-voltage characteristics, electrical breakdown, interface trap density, and mobile ion drift indicate that these very thin PECVD films are approaching thermally grown SiO2in quality and may be suitable as gate dielectrics in device applications.     

ZnO for application in photocatalysis: From thin films to nanostructures

In this research work, we report the photocatalytic properties of ZnO synthesized in several forms: ZnO thin films deposited by atomic layer deposition (ALD), ZnO nanofibers synthesized by electrospinnig, and ZnO nanorods realized by chemical bath deposition onto ZnO thin films grown by ALD. The methylene blue was employed as a representative dye pollutant to evaluate the photocatalytic activity of the samples. All the nanostructured materials showed an enhancement of the photocatalytic activity with respect to the thin films. It was found that ZnO nanorods deposited onto 3 nm thin film showed the best photocatalytic activity. The relevance of the results is discussed, opening the route for the application of ZnO in photocatalysis.     

Recent Advances in ZnO Films Prepared by Pulsed Laser Deposition

Pulsed laser deposition （PLD） is emerging as the most rapid and efficient technique for fabricating the many compound films. ZnO thin films can be prepared under various deposition conditions by PLD. The effects of various substrate temperature, oxygen partial pressure, annealing temperature, substrate, buffer layers thickness and film thickness on micro-structural, optical and electrical properties of ZnO films grown by PLD technology are reviewed. ZnO films with special function can grow under proper conditions by PLD.     

用MOCVD方法在GaAs衬底上低温生长ZnO薄膜

采用二乙基锌(DEZn)和水(H2O)作为生长源,利用金属有机化学气相沉积(MOCVD)的方法,在100～400℃低温范围内,在GaAs(001)衬底上制备了ZnO薄膜.利用X射线衍射(XRD),室温PL,AFM,SEM研究了薄膜的晶体结构特性、发光特性及表面形貌特性.XRD分析表明ZnO薄膜具有很强的c轴取向,(002)峰的FWHM平均值为0.3°.当生长温度达到400℃时从SEM测量结果可以观察到薄膜表面呈六角状结晶.随着生长温度的升高,薄膜的晶粒尺寸变大,结晶质量得到提高但同时表面变粗糙.室温PL测量显示薄膜在370nm附近有强的近带边发射,没有观测到深能级发射峰.     

等离子增强化学汽相淀积a-SiC:H簿膜的AES研究

用俄歇电子能谱(AES)对等离子增强化学汽相淀积(PECVD)氢化非晶碳化硅(a-SiC∶H)薄膜进行了组分的深度剖析、半定量分析以及化学分析.俄歇深度剖析曲线表明PECVD淀积的薄膜均匀性非常好;用俄歇半定量结果比较了薄膜成分同淀积工艺参量之间的一些关系;根据实验获得的Si LVV和CKLL俄歇谱比较和讨论了不同[Si]/[C]浓度比薄膜的化学特征.     

Thickness dependent glass transition temperature of PECVD low-k dielectric thin films: effect of deposition methods

Low-k dielectric carbon-doped silicon dioxide films created by Plasma Enhanced Chemical Vapor Deposition (PECVD) using a six-station sequential deposition system exhibit different glass transition behavior from films created by PECVD in a single deposition station. The enhanced glass transition temperature (T_g) for the PECVD thin films of a layer consisting of six sub-layer deposited in a six-station sequential deposition system to the T_g for films of a single layer deposited in a single deposition system is traced back to the introduced film interface effect inherent to the different deposition methods. Both types of PECVD thin films range in thickness from 50 to 1255 nm and show an increasing T_g with decreasing film thickness. The observed glass transition behavior for films with six sub-layers can be well explained by a theoretical model of thickness dependent T_g for multiple sub-layers obtained by modifying the currently existing theoretical model for the single layer thickness dependent T_g behavior, which explains the observed thickness dependent T_g for single layer PECVD thin films.