原子层沉积制备氮化钛薄膜及其表征北大核心

宽禁带半导体TiN作为扩散阻挡层以及场效应管的门电极在集成电路中发挥重要作用。通过原子层沉积（atomic layer deposition,ALD）技术沉积不同循环次数TiN薄膜,采用四探针测试仪、台阶仪、扫描电子显微镜（SEM）、原子力显微镜（AFM）对薄膜进行了表征,确定了薄膜电阻率、生长速率、表面粗糙度与工艺条件的依赖关系。实验结果表明,ALD可实现膜厚精确控制、大面积均匀性优异、电阻率较小的薄膜制造,沉积薄膜的最小粗糙度为0．101nm,电阻率为5μΩ·cm,薄膜稳定生长速率为0．025nm／cycle。     

原子层沉积制备ZnO薄膜研究进展

随着半导体技术的发展,ZnO作为第三代半导体材料,具有禁带宽度大、载流子漂移饱和速度高和介电常数小等优点,更适合制作蓝光和紫外光的发光器件。与传统的薄膜制备技术相比,原子层沉积技术(ALD)在膜生长方面具有生长温度低、厚度高度可控、保形性好和均匀性高等优点,逐渐成为制备ZnO薄膜的主流方法。综述了ALD制备ZnO薄膜的反应机制、生长机制和掺杂方面的研究进展,针对当前ZnO薄膜p型掺杂的难点,指出了V族元素中的大半径原子(磷和砷等)掺杂有可能成为制备高质量、可重复和稳定的p型ZnO的潜力研究点,最后总结和展望了ALD制备ZnO薄膜的应用前景和研究趋势。     

原子层沉积技术生长单质钨薄膜

采用热型原子层沉积(ALD)技术在单晶硅基底上成功制备了单质钨薄膜。利用场发射扫描电子显微镜(FESEM)、掠入射X射线衍射仪(GIXRD)、X射线光电子能谱仪(XPS)、四探针测试仪对样品的生长速率、晶体结构、薄膜成分以及电阻率进行了表征和分析。结果表明,热型原子层沉积技术生长单质钨薄膜的温度窗口为200～250℃,生长的薄膜呈多晶态,由较小粒径的颗粒组成,具有(210)晶面择优取向。XPS测试表明薄膜中W 4f_7/2、W 4f_5/2及W 5p_3/2的特征峰分别位于31.5～31.6、33.5～33.7及36.9～37.1 eV结合能位置处,主要含有W、C、O等元素。生长的单质钨薄膜为β相钨,电阻率为1.6×10^-4～3.0×10^-4Ω·cm。     

原子层沉积技术研究及其应用进展

原子层沉积(ALD)技术是制备复杂纳米结构材料以及材料表面改性的关键技术,该技术已得到了国内外学术界的大量研究。简单介绍了ALD技术、沉积过程、该技术的优点以及该技术可以沉积的薄膜材料,重点论述了ALD技术的应用进展,主要包括半导体方面(如IC互连技术、电容器、太阳电池晶体硅表面钝化)以及纳米结构材料方面(如催化剂与燃料电池、光催化、太阳电池、分离膜)。最后,指出了目前ALD在材料制备和生产工艺方面所面临的挑战,并对其未来发展进行了展望。     

等离子体增强原子层沉积制备压电AlN薄膜

采用等离子体增强原子层沉积(PEALD)技术在单晶硅衬底上成功制备了具有(002)晶面择优取向的氮化铝(AlN)晶态薄膜,为设计新型压电功能器件提供了思路.利用椭圆偏振光谱仪(SE)、原子力显微镜(AFM)、X射线衍射仪(XRD)、X射线光电子能谱仪(XPS)对.样品的生长速率、表面形貌、晶体结构、薄膜成分进行了表征和分析.结果 表明,在250℃沉积温度下,以N2H2和Ar的混合气体的等离子体作为共反应物,在相同工艺条件下仅增加前驱体三甲基铝(TMA)脉冲注入之后的氮气吹扫时间(tp1),制备的AlN薄膜的(002)晶面择优取向趋于显著,说明tp1的增加可以促进Al和N原子的有序排列,并促进(002)晶面择优取向形成.实验中,tp1为30 s且循环次数为1150时,PEALD制备的AlN薄膜表面平整光滑,均方根表面粗糙度为0.885 nm,(002)晶面衍射峰最明显,薄膜中氧原子数分数为11.04％,氧原子在AlN薄膜中形成氧缺陷并形成一种稳定的基于八面体配位铝的新型氧缺陷相,XPS结果证明了N-O-Al键的形成.     

前驱体通气时间对原子层沉积氧化锌薄膜的影响

建立了反应腔室模型,模拟分析了原子层沉积(ALD)过程中前驱体质量分数随其通气时间的变化趋势.采用ALD法制备了ZnO薄膜,采用原子力显微镜(AFM)与扫描电子显微镜(SEM)对薄膜进行了表征,研究了不同二乙基锌通气时间下ZnO薄膜的表面形貌和厚度均匀性.模拟结果表明,前驱体通气时间越长,前驱体在整个反应腔室内的分布越...     

硫化锌薄膜的原子层沉积生长及表征

为满足硫化锌(ZnS)薄膜在光学薄膜领域进一步应用的要求,基于原子层沉积(Atomic Layer Deposition, ALD)技术在130℃温度下以二乙基锌(DEZ)和硫化氢(H2S)为反应源,在砷化镓(GaAs)衬底表面沉积了ZnS薄膜。用扫描电子显微镜(Scanning Electron Microscope, SEM)分析了样品的表面形貌和膜界面特性,用X射线衍射仪(X-ray Diffraction, XRD)分析了薄膜的结构特性,并通过X射线光电子能谱(X-ray Photoelectron Spectroscopy, XPS)分析了薄膜的化学成分。研究了厚度对薄膜结构和形貌的影响。结果表明,得到的ZnS薄膜为多晶结构,薄膜的厚度随循环数线性增加,速率为1.45 ?/cycle。对在75℃温度下烘烤48 h后的薄膜进行了XPS分析,得出的Zn/S比为1.07:1,表明烘烤除去了薄膜中残存的H2S。以较短生长时间得到的较薄的薄膜具有更好的表面平整度和更致密的结构。     

3D MIM电容器原子层沉积可控生长及电学性能

为提高电容器的比电容,设计了基于三维(3D)结构的金属-绝缘体-金属(MIM)电容器.采用原子层沉积(ALD)技术制备电容器功能薄膜层,通过建立3D结构原子层沉积理论模型,拟舍得到了原子层沉积过程中薄膜覆盖率与3D结构之间的依赖关系.基于该模型优化了工艺参数,制备了不同介质层厚度的电容器,并对器件进行了C-V和I-V特性测试,得到电容器击穿场强和介电常数均值分别为6.68 MV/cm和7.95.同时,制备的3D MIM电容器的比电容达到212.5 fF/μm2,相比常规平面电容器,其电容密度提高了一个数量级.且该电容器击穿场强和介电常数与薄膜厚度之间具有良好的线性关系,表明理论模型合理,实现了基于3D结构的原子层沉积薄膜可控生长.     

Deposition Characteristics of AlN Thin Film Prepared by the Dual Ion Beam Sputtering System

In this experiment, a radio frequency dual ion beam sputtering (DIBS) system was used to prepare aluminum nitride (AlN) films with a bottom Al electrode on a Si (100) substrate. After systematic testing of the processing variables, a high-quality film with preferred c-axis orientation was grown successfully on the Si (100) substrate with an Al target under 700 eV energy flux, N₂/(N₂ + Ar) ratio of 55%, and 4 × 10⁻⁴ torr in vacuum. The characteristics of the deposited AlN thin films were studied by x-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), secondary ion mass spectrometry (SIMS), and electronic spectroscopy for chemical analysis (ESCA). The surface roughness was also measured. It was found that AlN films prepared by DIBS at room temperature are better than those prepared at 300°C, and those prepared with an Al target are better than those prepared with an AlN target. The inferiority of AlN films prepared with AlN targets is due to the AlN bond being broken down by the ion beam source.     

等离子体增强原子层沉积原理与应用

等离子体增强原子层沉积(PEALD)是一种低温制备高质量超薄薄膜的有效手段,近年来正受到工业界和学术界广泛的关注。简要介绍了PEALD的发展历史和生长原理。描述了PEALD常见的三种设备构造:自由基增强原子层沉积、直接等离子体沉积和远程等离子体沉积,比较了它们的优缺点。着重评述了PEALD的特点,主要具有沉积温度低、前驱体和生长材料种类广、工艺控制灵活、薄膜性能优异等优势,但也面临着薄膜三维贴合性下降和等离子体损伤等挑战。列举了PEALD的一些重要应用,如在金属薄膜制备、铜互连阻挡层、高介电常数材料、薄膜封裹等领域的应用。最后展望了PEALD的发展前景。     

热原子层沉积技术制备TiAlCN薄膜的特性

在Si和SiO2基底上,采用热原子层沉积技术,以四(二甲基氨基)钛(Ti(N (CH3)2)4)和三甲基铝(Al (CH3)3)为前驱体,制备TiAlCN薄膜.测试结果表明,随着基底温度的升高,膜层的沉积速率升高,电阻率降低,光学带隙由3.45 eV降低到2.00 eV,并在基底温度为300和350℃时出现了双吸收边;基底温度为350℃时,Al (CH3)3分解,使Al进入膜层与TiN和TiC形成TiAlN和TiAlC;膜层中TiN和TiC的形成,可以有效抑制膜层的自然氧化;基底温度为250和300℃时,薄膜为无定型结构,当基底温度为350℃时,有TiN晶体产生;膜层的表面粗糙度随着基底温度的升高先降低后升高,表面粗糙度的升高可能是因为在基底温度为350℃时前驱体材料的分解,使C-H键进入膜层所导致的.     

使用溅射AlN成核层实现大规模生产深紫外LED

高质量AlN薄膜对制造高性能深紫外器件非常重要,但是目前还很难使用大型工业MOCVD生长出高质量的AlN薄膜.采用磁控溅射制备了不同厚度的用作成核层的AlN薄膜,使用大型工业MOCVD直接在成核层上高温生长AlN外延层,研究了不同成核层对AlN外延层质量的影响.通过扫描电子显微镜和原子力显微镜对成核层AlN薄膜的表面形貌进行表征;使用高分辨X射线衍射仪对AlN外延层晶体质量进行表征,结果表明:在溅射成核层上生长的AlN外延层的晶体质量有显著提高.使用大型工业MOCVD在蓝宝石衬底上成功制备出中心波长为282 nm的可商用深紫外LED,在注入电流为20 mA时,单颗深紫外LED芯片的光输出功率达到了1.65 mW,对应的外量子效率为1.87%,饱和光输出功率达到4.31 mW.     

Efficient Charge Injection in Organic Field‐Effect Transistors Enabled by Low‐Temperature Atomic Layer Deposition of Ultrathin VOx Interlayer

Charge injection at metal/organic interface is a critical issue for organic electronic devices in general as poor charge injection would cause high contact resistance and severely limit the performance of organic devices. In this work, a new approach is presented to enhance the charge injection by using atomic layer deposition (ALD) to prepare an ultrathin vanadium oxide (VO_x) layer as an efficient hole injection interlayer for organic field‐effect transistors (OFETs). Since organic materials are generally delicate, a gentle low‐temperature ALD process is necessary for compatibility. Therefore, a new low‐temperature ALD process is developed for VO_x at 50 °C using a highly volatile vanadium precursor of tetrakis(dimethylamino)vanadium and non‐oxidizing water as the oxygen source. The process is able to prepare highly smooth, uniform, and conformal VO_x thin films with precise control of film thickness. With this ALD process, it is further demonstrated that the ALD VO_x interlayer is able to remarkably reduce the interface contact resistance, and, therefore, significantly enhance the device performance of OFETs. Multiple combinations of the metal/VO_x/organic interface (i.e., Cu/VO_x/pentacene, Au/VO_x/pentacene, and Au/VO_x/BOPAnt) are examined, and the results uniformly show the effectiveness of reducing the contact resistance in all cases, which, therefore, highlights the broad promise of this ALD approach for organic devices applications in general.     

High‐Performance,Transparent Thin Film Hydrogen Gas Sensor Using 2D Electron Gas at Interface of Oxide Thin Film Heterostructure Grown by Atomic Layer Deposition

A high‐performance, transparent, and extremely thin (<15 nm) hydrogen (H₂) gas sensor is developed using 2D electron gas (2DEG) at the interface of an Al₂O₃/TiO₂ thin film heterostructure grown by atomic layer deposition (ALD), without using an epitaxial layer or a single crystalline substrate. Palladium nanoparticles (≈2 nm in thickness) are used on the surface of the Al₂O₃/TiO₂ thin film heterostructure to detect H₂. This extremely thin gas sensor can be fabricated on general substrates such as a quartz, enabling its practical application. Interestingly, the electron density of the Al₂O₃/TiO₂ thin film heterostructure can be tailored using ALD process temperature in contrast to 2DEG at the epitaxial interfaces of the oxide heterostructures such as LaAlO₃/SrTiO₃. This tunability provides the optimal electron density for H₂ detection. The Pd/Al₂O₃/TiO₂ sensor detects H₂ gas quickly with a short response time of <30 s at 300 K which outperforms conventional H₂ gas sensors, indicating that heating modules are not required for the rapid detection of H₂. A wide bandgap (>3.2 eV) with the extremely thin film thickness allows for a transparent sensor (transmittance of 83% in the visible spectrum) and this fabrication scheme enables the development of flexible gas sensors.     

原子层淀积技术应用于太阳电池的研究进展

原子层淀积(ALD)是一种先进的纳米级薄膜生长技术,在微电子和光电子领域有着广泛的应用前景,尤其在提高太阳电池的光电转换效率方面正发挥越来越大的作用,很可能成为下一代太阳电池工艺中的重要方法。文章综述了近年来ALD技术在太阳电池领域的应用研究进展,详细介绍了ALD技术应用在不同类型太阳电池的最新研究成果和存在的问题,并对其发展趋势进行了展望。     

离子束增强沉积AlN薄膜的研究

利用离子束增强沉积9IBED）法成功地在Si(100）衬底上合成了大面积均匀的非晶AlN薄膜。XRD和XPS测试结果证实该薄膜为非晶且无单质Al和N2存在,随着Al蒸发速率的提高,N/Al下降,在0.05nm/s及0.10nm/s的蒸发速率下制得的薄膜N／Al分别为0.402:1和0.250:1。SRP测试结果表明,随着Al蒸发速率的提高,表面电阻下降,并助在0.05nm/s的速率下制得的薄均匀致密,表面电阻高于10^8Ω,性能良好,而当蒸发速率≥0.25nm/s时,薄膜绝缘性能迅速下降。AFM分析显示薄膜呈岛状分布,且0.05nm/s制取的样品表面呈鹅卵石密堆积,颗粒均匀,表面比0.10nm/s样品起伏平缓、光滑,薄膜的生长机制可能是三维岛状生长。     

Ultra Thin Film Encapsulation of Organic Light Emitting Diode on a Plastic Substrate

We have carried out the fabrications of a barrier layer on a polyethersulfon (PES) film and organic light emitting diode (OLED) based on a plastic substrate by means of atomic layer deposition (ALD). Simultaneous deposition of 30 nm AlO_x film on both sides of the PES film gave a water vapor transition rate (WVTR) of 0.062 g/m²/day (@38°C, 100% R.H.). Further, the double layer of 200 nm SiNx film deposited by plasma enhanced chemical vapor deposition (PECVD) and 20 nm AlOx film by ALD resulted in a WVTR value lower than the detection limit of MOCON. We have investigated the OLED encapsulation performance of the double layer using the OLED structure of ITO / MTDATA (20 nm) / NPD (40 nm) / AlQ (60 nm) / LiF (1 nm) / Al (75 nm) on a plastic substrate. The preliminary life time to reach 91% of the initial luminance (1300 cd/m²) was 260 hours for the OLED encapsulated with 100 nm of PECVD‐deposited SiNx and 30 nm of ALD‐deposited AlO_x.