ALD原子层沉积技术的应用

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The high conformalБайду номын сангаасty of ALD films has been one of the main
drivers to investigate and adapt ALD for semiconductor memory applications. Cylinder/stack architecture or deep trenches, with aspect ratios of 50:1 or more, are easily coated with ALD dielectrics. ALD has now been used for dynamic random access memory (DRAM) production since 2005, and is enabling further scaling down to smaller feature size and trenches with a 100:1 aspect ratio.
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ALD 原子层沉积应用
吴运祥 2017年7月26日
概述
The main industrial application of ALD is in the manufacture of semiconductor devices, both memory devices and microprocessors. TFEL displays have been manufactured for over 20 years using ALD technology. The read heads of hard disk drives are enabled by ALD. The silver jewelry industry has selected ALD coatings as a way of preventing tarnishing of silver products. In addition to its established industrial uses, ALD is being
The semiconductor industry recognized the importance of ALD technology for semiconductor applications at Semicon Europe 2004, when the European SEMI Award 2004 was awarded to Dr Tuomo Suntola for the development of ALD technology for semiconductor applications.
million TFEL displays have been produced to date. In addition to the active dielectric–phosphor–dielectric stack (Below Figure), ALD technology is used to deposit a pinhole-free ion barrier layer on a soda lime glass substrate and as a passivation layer on top of the device structure. Production is based on efficient batch-mode ALD systems.
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Figure：汽车应用的透明汽车仪表盘
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Because of the high precision of ultrathin films, and the low defect density and extreme conformality of ALD films, ALD has been adapted by semiconductor companies in the manufacture of IC products. Development work on semiconductor memory and microprocessor applications started in the 1990s, and ALD is now an established thin film coating technology in the semiconductor industry. The development of new material solutions for semiconductor applications is a demanding task. In addition to the materials themselves, surface pretreatments, interfaces, impurities, and postprocessing conditions all have roles.
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Scaling down of the thickness of SiO2-based gate oxides and feature sizes has enabled the semiconductor industry to follow Moore’s law, that the number of transistors on a chip will double about every two years. Semiconductor industry has kept this pace for nearly 40 years. In the 1990s semiconductor companies started the search for new materials and processes to replace the SiO2-based gate oxide with a high-k material. ALD technology was also introduced in the Sematech roadmap for the first time in 1999. After extensive work and evaluation of several different materials and material combinations, Hf-oxide-based gate oxides made with ALD were introduced into production for the first time, and products at 45 nm node were produced by Intel at the end of 2007.
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Figure：薄膜电致发光(TFEL)显示屏
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Since the end of 1990s, ALD technology has been used in Japan by Denso Corporation to produce transparent TFEL displays for automotive and other applications (Below Figure). The high quality and yield of ALD oxide materials over large areas, as well as high conformality, are key advantages when considering and investigating ALD technology for TFT (Thin Film Electroluminescent) liquid crystal display (LCD) applications, as well as for microelectromechanical (MEMS)based display applications. Several research centers are investigating the use of an ALD barrier and passivation layers in the development of flexible organic light-emitting device (OLED) displays. ALD films enhance the barrier properties of plastic substrates at thickness levels of only tens of nanometers. ALD coatings can also be used to enhance the properties of barriers made with other coating methods, such as plasma-enhanced chemical vapor deposition (PECVD).
硬盘
Smaller critical dimensions and more challenging topographies of magnetic recording heads have led to a need to replace conventional physical vapor deposition (PVD) coating technology with a more conformal coating method. ALD was selected as a new method to enable further scaling down. An additional benefit of ALD was the high quality of ultrathin insulating layers with low pinhole density. ALD AlOx has been used in read heads for several years, and ALD thin films and nanolaminates are being investigated for other applications in the read/write head process flow, such as trench filling, tunneling barriers, and encapsulation.
In addition to the mainstream use of ALD for memory cell and transistor manufacturing, ALD is being widely investigated for back-end processes. Examples are ALD-based barrier, e.g. TaN, and copper seed layer, e.g. Ru, materials to meet the requirements of shrinking interconnection dimensions. An additional challenge is matching of the barrier and seed layer processes with the low-k processes and materials.
ALD is a powerful technology for this development work, as surface chemistry has an important role in the selection and optimization of materials, processes, and process conditions for electronic devices.
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Production ALD systems for front-end semiconductor manufacture are typically either 300mm single-wafer systems or 300mm wafer semi-batch systems.
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ALD technology was developed initially to enable TFEL display production.
Production started in Finland in the mid-1980s and several