高k栅介质材料制备技术研究进展

随着半导体器件特征尺寸的不断减小,传统SiO2栅介质减薄到1nm以下时会导致栅极漏电流增大、器件可靠性下降等诸多问题,已无法满足CMOS技术长远发展要求。因此,寻求替代SiO2的新型栅介质材料,减少器件的隧穿电流,提升可靠性成为CMOS技术的发展方向。如何制备化学性质稳定、性能优异的栅介质薄膜成为高k栅介质材料亟待解决的问题。论述了理想高k栅介质材料的基本要求,重点介绍了高k栅介质材料制备技术的研究进展,并分析指出了高k栅介质材料制备技术的未来发展趋势。     

一种称为SIMOS的新型n沟道单管EAROM单元技术

本文描述一种新的非易失性电荷存储器件的结构和工艺。叠栅注入MOS(SIMOS)器件是一种控制栅叠在浮动栅上的n沟道MOS晶体管。在编制程序方式中,用沟道漂移电场加速电子使其能量大到足以克服Si-SiO_2界面的势垒高度,电子就注入到浮动栅。由于程序编制用沟道注入机构来完成,故要求沟道长度小于4μm。用自对准工艺能把这个条件同叠栅概念结合起来,自对准工艺用一道光刻工序确定两个多晶硅栅。用自对准工艺可以实现单管的EPROM单元和单管的EAROM单元。二种不同型式的单管存储单元的基本结构分别为SIMOS晶体管和SIMOS四极管。本文详细地描述了这二种不同的SIMOS器件的工艺并报导了有关电荷积累、清除及电荷保持的实验结果。     

采用浮动栅单管单元的8192位电改写ROM

本文介绍一种采用双层n沟道多晶硅栅工艺的全译码(与TTL相容)电改写8K位MOS ROM。存储单元由叠栅结构的单管组成,其浮动栅只盖住沟道的一部分,并扩展到沟道外的源扩散区的清除复盖层上。通过热电子从短沟道(3.5μm)注入到浮动栅来编码,典型的为100ms/字。通过电子从浮动栅的Fowler-Nordheim 发射完成成组清除。在清除期间,为了避免雪崩击穿电流过大,在清除复盖层加了40nm～50nm 的氧化层并采用了斜坡电压。存储器在读、编码和清除操作中用标准电压(±5V,+12V),编码用一个高压单脉冲(+26V),斜坡清除电压最大值为+35V。典型的读出时间为250ns。从存储实验数据外推法(Extrapolation of storage data)(在125℃,400小时)可以予示,90%以上的存储电荷可望保持100年以上。每个存储单元允许写入次数在10000次以上。面积为19.7mm~2的芯片装在24引线双列直插式封装中。     

短沟道SOI中的阈值电压下降问题的研究

运用电荷分享模型推导出背界面处于耗尽状态的单栅和双栅薄膜SOIMOSFET中短沟道效应引起的闽值电压下降的理论模型。利用MatLab进行了数值模拟计算．并比较了单栅和双栅器件的结果。同时分析了沟道区掺杂浓度、硅膜厚度、栅氧化层厚度对阈值电压下降的影响。结果表明．薄膜器件有利于减小短沟道效应．而双栅器件短沟道效应比单栅器件减小4倍。另外．对于薄膜器件来说,改变器件结构要比改变器件参数对短沟道效应的抑制作用好得多。     

PHEMT电离辐照效应研究

对PHEMT的电离辐照效应进行了研究,通过测量辐照前后器件的I-V特性和低频噪声,发现辐照对PHEMT的性能影响并不明显.分析了PHEMT漏电流退化的机理以及其低频噪声的来源,发现异质结界面态是引起漏电流退化和产生较大低频噪声的主要原因,但辐照不会在异质结界面处引入大量的界面态,从而在微观上解释了实验结果.     

n沟道SIMOS单管单元电可清除和可编码的只读存储器

叠栅注入MOS晶体管,在读、编码和清除时,利用叠在浮动栅上的控制栅来选择单元。编码是通过由沟道向浮动栅注入热电子来完成的,这就导致了开启电压一个很大的向上漂移。在两种状态下,都是以增强型工作的。电清除能够通过在源-衬底结处雪崩击穿注入热空穴和通过Fowler-Nordheim电子注入来完成。因为在清除时,浮动栅能够被充正电,而且沟道的一部份不被浮动栅覆盖,这样,在清除以后,SIMOS晶体管保证是增强型。在矩阵阵列中,存储单元只由SIMOS晶体管组成。译码器、读出放大器、等等,能够集成在同样的衬度上。清除能成组进行,或一个字一个字地进行。讨论了在编码和清除时,存储单元所受到的不同打扰效应。SIMOS存储器的单元面积是850μm~2。给出了全译码8192位SIMOS存储器芯片的照片。     

化学场效应管氨气传感器的制备及特性研究

采用化学氧化聚合法制备了3,4-聚乙撑二氧噻吩(简称PEDT),并运用SEM和红外吸收光谱对其薄膜进行表征;同时将其沉积在N沟道耗尽型无金属栅场效应管上,形成以PEDT膜取代MOSFET栅金属的化学场效应管(ChemFET)气体传感器,研究了其对氨气和温度的敏感特性.研究表明在氨气浓度低于54ppm的情况下,ChemFET的漏电流随着氨气浓度的增加而减小,其变化量(ΔIDS)随氨气浓度的变化呈线性关系;同时漏电流随着负的衬底电压的增加而减小,随着温度的升高而降低.     

VMOS—一种新的MOS集成电路工艺

叙述了一种新的V型槽MOS集成电路工艺(VMOS)。这种工艺是利用硅的选择蚀刻原理来确定MOS晶体管的沟道。整个制作过程包括三次或四次掩蔽工序,并且利用这种工艺能够形成硅栅或者普通金属栅晶体管。这种工艺在要求不高的对准误差条件下,产生非常短的沟道。除了沟道短而外,VMOS晶体管的输出电导要比普通MOS晶体管小,而击穿电压更高。 介绍了VMOS晶体管的一阶理论,并对不同沟道长度的器件进行了测量。也介绍了运用这种工艺制作的某些集成电路,其中包括R—S触发器和27级戽斗式移位寄存器。讨论了在这些应用中VMOS的优点。     

新型双栅薄膜晶体管研究取得进步

双栅薄膜晶体管由于其具有可控的阈值电压调节特性,在湿度传感、pH值传感、病毒生物分子探测等领域应用广泛。然而,传统的双栅晶体管都是基于一种典型的三明治结构,半导体沟道被两层栅介质夹在中间,其实质上可以看做是一个底栅晶体管和项栅晶体管的共用沟道复合晶体管,制备这些器件需要多步的薄膜沉积工艺以及精准的对准光刻技术。因此,设计和开发一种具有简单器件工艺的高性能双侧栅晶体管具有重大的研究意义和潜在的应用价值。     

IBM尝试将双层石墨烯FET用作逻辑LSI的开关元件

2010年12月,美国IBM宣布找到了一种方法,可提高用于沟道的双层石墨烯FET的导通／截止比。用半导体材料制作源电极和漏电极,代替原来的金属源漏极,由此抑制截止状态下由漏电极流向源电极的泄漏电流,以这种方法构造的栅长为20nm的双层石墨烯FET,有望实现10^4左右的导通／截止比以及110mV／dec的S因子。     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

基于QTE的蒙古文显示机制研究与实现

蒙古语言是中国蒙古族使用的通用语言,由于蒙古文区别于其他文字的书写方式和其自身变形机制等特点,在很多通用的文字处理引擎中都不被支持。在嵌入式产品开发与应用领域中Linux加QTE已经成为流行方式。该文给出了一种在QTE环境上实现基于标准Unicode的蒙古文点阵显示和变形算法, 并自定义了支持蒙古文的QTE组件,扩展了QTE功能,为在Linux加QTE方式的嵌入式体系结构中处理蒙古文提供了一种解决方法。