原子层沉积技术发展现状

复杂的非平面结构基板形貌对传统的薄膜沉积技术产生了极大的挑战,不同类型的集成电路器件需要不同的生产技术,同时也对薄膜材料提出了不同的要求。为了突破现有材料的性能限制就要求开发具有更高性能的材料。原子层沉积(ALD)是一种可足以应对这些挑战的独特技术,它所沉积的薄膜具有极佳的均匀性、台阶覆盖率和(对薄膜图形的)保形性。介绍了原子层沉积技术原理、新一代逻辑组件所面临的课题、原子气相沉积技术AVD及原子层沉积设备现状。     

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。     

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。     

单原子层沉积原理及其应用

传统的薄膜材料制造方法已不能满足未来元器件和集成电路制造的要求,原子层沉积技术由于具有精确的厚度控制、沉积厚度均匀性和一致性等特点,已成为解决微电子制造相关超薄膜材料制造问题的主要解决方法之一,也将成为新的纳米材料和纳米结构的制造方法之一。综述了原子层沉积技术的原理、技术设备要求和应用。     

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。     

原子层沉积法制备微通道板发射层的性能

随着微通道板的不断发展与完善,通过改善传统工艺提升其性能越来越困难,开发提升微通道板性能的新技术迫在眉睫。纳米薄膜材料的发展及其制备技术的成熟为微通道板的发展提供了契机,利用原子层沉积技术在通道内壁沉积一层氧化铝纳米薄膜,作为二次电子发射功能层,可以增强通道内壁的二次电子发射能力,从而提升微通道板的增益性能。通过优化原子层沉积工艺参数可以在微通道板的通道内壁沉积厚度均匀的氧化铝薄膜。研究结果表明,微通道板增益随沉积氧化铝厚度的变化而变化,在氧化铝厚度为60 cycles时,施加偏压800 V时增益可达56 000,约为正常微通道板增益的12倍。     

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。     

原子层沉积薄膜之激光损伤性能分析

采用目前尚在国内鲜有报道的原子层沉积技术在熔石英和BK7玻璃基片上镀制了TiO2单层膜、AlO3单层膜以及TiO2/Al2O3增透膜,沉积温度在110℃和280℃.利用X射线粉末衍射仪对膜层微观结构进行了分析研究,并在激光损伤平台上进行了抗激光损伤阈值的测量.采用Nomarski微分干涉差显微镜和原子力显微镜对激光损伤...     

原子层沉积法制备高反射率的分布式布拉格反射镜

为提高GaN基发光二极管(LED)的发光强度,制备TiO₂/Al₂O₃分布式布拉格反射器(DBR)来提高其外量子效率是一种有效的方法。原子层沉积(ALD)法所制备的薄膜具有良好的均匀性,适合用来制备反射器材料。同时,TiN薄膜具有良好的类金属性质,且与TiO₂之间具有良好的粘附性,因此在DBR基础上再采用TiN反射层可以将反射率进一步提高。Matlab软件模拟结果表明,3~6周期厚的DBR,其反射率随厚度增加而提高。其中6周期DBR的反射率为95%,加上TiN薄膜后反射率可以得到进一步提高。实验结果与模拟结果吻合,6周期DBR+TiN结构的反射率达到99%。给带有该结构的LED注入50mA电流时,LED光输出功率(LOP)相对没有该结构的器件提升了约68.3%。     

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。     

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。     

Inherently Area-Selective Atomic Layer Deposition of SiO2 Thin Films to Confer Oxide Versus Nitride Selectivity

Area-selective atomic layer deposition (AS-ALD) offers tremendous advantages in comparison with conventional top-down patterning processes that atomic-level selective deposition can achieve in a bottom-up fashion on pre-defined areas in multi-dimensional structures. In this work, a method for exploiting substrate-dependent selectivity of aminosilane precursors for oxides versus nitrides through chemo-selective adsorption is reported. For this purpose, AS-ALD of SiO₂ thin films on SiO₂ substrates rather than on SiN substrates are investigated. Theoretical screening using density functional theory (DFT) calculations are performed to identify Si precursors that maximize adsorption selectivity; results indicate that di(isopropylamino)silane (DIPAS) has the potential to function as a highly chemo-selective precursor. Application of this precursor to SiN and SiO₂ substrates result in inherent deposition selectivity of ≈4 nm without the aid of surface inhibitors. Furthermore, deposition selectivity is enhanced using an ALD-etch supercycle in which an etching step inserts periodically after a certain number of ALD SiO₂ cycles. Thereby, enlarged deposition selectivity greater than ≈10 nm is successfully achieved on both blanket- and SiO₂/SiN-patterned substrates. Finally, area-selective SiO₂ thin films over 4–5 nm are demonstrated inside 3D nanostructure. This approach for performing inherent AS-ALD expands the potential utility of bottom-up nanofabrication techniques for next-generation nanoelectronic applications.     

GaAs衬底上等离子体增强原子层沉积GaN薄膜

采用等离子体增强原子层沉积(PEALD)技术在斜切的砷化镓(GaAs)衬底上低温沉积了氮化镓(GaN)薄膜,对生长过程、表面机制以及界面特性等进行分析,得到GaN在215～270℃的温度窗口内生长速度(Growth-Per-Cycle, GPC)为0.082 nm/cycle,并从表面反应动力学和热力学方面对GPC的变化进行了分析。研究发现,生长的GaN薄膜为多晶,具有六方纤锌矿结构,且出现(103)结晶取向。在GaN/GaAs界面处观察到约1 nm厚的非晶层,这可能与生长前衬底表面活性位点的限制和前驱体的空间位阻效应有关。值得注意的是,在沉积的GaN薄膜中,所有的N皆与Ga以Ga-N键结合生成GaN,但是存在少部分Ga形成了Ga-O键和Ga-Ga键。这种成键方式,可能与GaN薄膜中存在的缺陷和杂质有关。     

Gyroid‐Structured 3D ZnO Networks Made by Atomic Layer Deposition

3D continuous ZnO morphologies with characteristic feature sizes on the 10 nm length scale are attractive for electronic device manufacture. However, their synthesis remains a challenge because of the low crystallization temperature of ZnO. Here, we report a method for the robust and reliable synthesis of fully crystalline 3D mesoporous ZnO networks by means of atomic layer deposition (ALD) of ZnO into a self‐assembled block copolymer template. By carefully optimizing the processing conditions we are able to synthesize several‐micrometer‐thick layers of mesoporous ZnO networks with a strut width of 30 nm. Two 3D mesoporous morphologies are manufactured: a periodic gyroid structure and a random worm‐like morphology. Exploiting the ALD property to conformally coat complex surfaces of high aspect ratio, the channel network of a 3D continuous channel network of a self‐assembled block copolymer is replicated into ZnO. X‐ray photoemission spectroscopy and x‐ray diffraction measurements reveal that the chemical composition of the mesoporous structures is uniform and consists of wurtzite‐ZnO throughout the film. Scanning electron microscopy reveals an average pore dimension of 30 nm. The potential of this material for a hybrid photovoltaic application is demonstrated by the manufacture of a poly(3‐hexylthiophene)/ZnO solar cell.     

Polyphenol‐Sensitized Atomic Layer Deposition for Membrane Interface Hydrophilization

Improvements in energy–water systems will necessitate fabrication of high‐performance separation membranes. To this end, interface engineering is a powerful tool for tailoring properties, and atomic layer deposition (ALD) has recently emerged as a promising and versatile approach. However, most non‐polar polymeric membranes are not amenable to ALD processing due to the absence of nucleation sites. Here, a sensitization strategy for ALD‐coating is presented, illustrated by membrane interface hydrophilization. Facile dip‐coating with polyphenols effectively sensitizes hydrophobic polymer membranes to TiO₂ ALD coating. Tannic acid‐sensitized ALD‐coated membranes exhibit outstanding underwater crude oil repulsion and rigorous mechanical stability through bending and rinsing tests. As a result, these membranes demonstrate outstanding crude oil‐in‐water separation and reusability compared to untreated membranes or those treated with ALD without polyphenol pretreatment. A possible polyphenol‐sensitized ALD mechanism is proposed involving initial island nucleation followed by film intergrowth. This polyphenol sensitization strategy enriches the functionalization toolbox in material science, interface engineering, and environmental science.     

Low Temperature Stabilization of Nanoscale Epitaxial Spinel Ferrite Thin Films by Atomic Layer Deposition

In this work heteroepitaxial stabilization with nanoscale control of the magnetic Co₂FeO₄ phase at 250 °C is reported. Ultrasmooth and pure Co₂FeO₄ thin films (5–25 nm) with no phase segregation are obtained on perovskite SrTiO₃ single crystal (100) and (110) oriented substrates by atomic layer deposition (ALD). High resolution structural and chemical analyses confirm the formation of the Co‐rich spinel metastable phase. The magneto‐crystalline anisotropy of the Co₂FeO₄ phase is not modified by stress anisotropy because the films are fully relaxed. Additionally, high coervice fields, 15 kOe, and high saturation of magnetization, 3.3 μ_B per formula unit (at 10 K), are preserved down to 10 nm. Therefore, the properties of the ALD‐Co₂FeO₄ films offer many possibilities for future applications in sensors, actuators, microelectronics, and spintronics. In addition, these results are promising for the use of ALD compared to the existing thin‐film deposition techniques to stabilize epitaxial multicomponent materials with nanoscale control on a wide variety of substrates for which the processing temperature is a major drawback.     

Tin Dioxide Sensing Layer Grown on Tubular Nanostructures by a Non‐Aqueous Atomic Layer Deposition Process

A new atomic layer deposition (ALD) process for nanocrystalline tin dioxide films is developed and applied for the coating of nanostructured materials. This approach, which is adapted from non‐hydrolytic sol‐gel chemistry, permits the deposition of SnO₂ at temperatures as low as 75 °C. It allows the coating of the inner and outer surface of multiwalled carbon nanotubes with a highly conformal film of controllable thickness. The ALD‐coated tubes are investigated as active components in gas‐sensor devices. Due to the formation of a p‐n heterojunction between the highly conductive support and the SnO₂ thin film an enhancement of the gas sensing response is observed.     

Alumina-Protected,Durable and Photostable Zinc Sulfide Particles from Scalable Atomic Layer Deposition

Zinc sulfide has unique and easily modifiable photophysical properties and is a promising candidate for photocatalysis and optoelectronic devices. However, ZnS suffers from corrosive decomposition during excitation processes like UV irradiation, which drastically limits its field of potential applications. For the first time, complete photostabilization of individual ZnS particles by a dense, durable, and only 3-nm-thick Al₂O₃ layer, produced by rotary atomic layer deposition (ALD) is reported. In contrast to bare ZnS, the coated particles do not suffer from photocorrosive degradation even under long-term or high power UV irradiation. The presence of a protection layer covering the entire ZnS surface is additionally confirmed by microscopic and spectroscopic investigations of particle cross-sections. Further, complete inhibition of the reaction between Ag⁺ ions added as the analyte and the ZnS surface is observed. Durability tests of the as-prepared Al₂O₃ layer upon prolonged exposure to water reveal a significant decrease in the protection capability of the layer, which is ascribed to the hydrolysis of the amorphous Al₂O₃. A calcination step at 1000 °C after the ALD treatment, which leads to crystallization of the amorphous Al₂O₃ layer, successfully suppresses this hydrolysis and produces an insulating, dense, and inert protection layer.