膜厚对多晶硅纳米薄膜压阻温度特性的影响

重掺杂多晶硅纳米薄膜具有良好的压阻温度特性,用它制作高温压阻式传感器灵敏度高、成本低,具有广阔的应用前景.为优化多晶硅纳米薄膜的压阻温度特性,本文采用低压化学气相淀积(LPCVD)技术制作了不同膜厚(30～250 nm)的多晶硅薄膜,分别测试了应变系数、薄膜电阻率与工作温度的关系.利用扫描电镜(SEM)和X射线衍射实验(XRD)对薄膜进行了表征,在此基础上结合隧道压阻模型分析了膜厚对多晶硅薄膜压阻温度特性的影响,结果表明,对于淀积温度620℃、掺杂浓度2.3×1020 cm-3的多晶硅纳米薄膜,膜厚的最佳值在80 nm厚左右.     

多晶硅纳米薄膜压阻和电学修正特性

本文制备了不同掺杂浓度的多晶硅纳米薄膜,研究了掺杂浓度对多晶硅纳米薄膜压阻和电学修正特性的影响。利用低压化学气相淀积法制备了不同掺杂浓度的多晶硅纳米薄膜,掺杂浓度分别为1.0*10^20cm-3、2.0*10^20cm-3、4.1*10^20cm-3和7.1*10^20cm-3。利用应变系数测量装置对不同掺杂浓度多晶硅纳米薄膜的应变系数进行了测量,利用恒流源和万用表测量 不同掺杂浓度多晶硅纳米薄膜的电学修正特性。实验结果表明:多晶硅纳米薄膜的应变系数与掺杂浓度有关,应变系数范围:33.38~38.41,利用电学方法能够修正多晶硅纳米薄膜的电阻,最大修正范围可达15.4%,多晶硅纳米薄膜具有较高的应变系数,适用于制作压阻式传感器,电学修正可用来调整多晶硅纳米薄膜的电阻,进而降低传感器的失调。     

多晶硅薄膜制备方法与压阻特性的研究

对磁控溅射和低压化学气相淀积(LPCVD)2种方法制备的多晶硅薄膜的电学和压阻特性进行了研究,并讨论了结晶化工艺对磁控溅射薄膜性质的影响。实验表明:LPCVD薄膜稳定性、重复性较好,应变系数可达到20以上;磁控溅射薄膜经适当结晶化工艺处理具有纳晶硅的结构特征,应变系数可达到80以上。利用扫描电镜(SEM)图片结合电阻率和应变系数的测试结果,讨论了2种方法制备出的多晶硅薄膜应用于压阻式力学量传感器的可行性。     

多晶硅纳米薄膜电学特性的实验研究

用低压化学气相淀积(LPCVD)法淀积了膜厚为60～250nm的多晶硅纳米薄膜,研究了膜厚和掺杂浓度对多晶硅纳米薄膜电学特性的影响。结合扫描电镜(SEM)图片,在电阻率与电阻率温度系数测试结果的基础上,分析了膜厚和掺杂浓度对薄膜电学特性的影响。结果表明:重掺杂多晶硅纳米薄膜具有良好的温度特性,电阻率温度系数可达到1×10-4～3×10-4/℃的水平。     

多晶硅高温压力传感器

一、前言 现代航空、汽车发动机以及石油化工领域常常需要对200℃以上高温范围的压力进行检测。200℃以上温度工作的高温压力传感器一般可采用SOS或绝缘衬底上多晶硅结构制作,因为多晶硅薄膜压阻元件可淀积在各种低成本衬底上,而且工艺简     

微米纳米学会推荐-基于电学修正多晶硅纳米薄膜的压力传感器

为了进一步提高多晶硅纳米薄膜压力传感器的性能,本文使用80nm厚度的多晶硅纳米薄膜作为压力传感器的压敏电阻,设计制作了一款压力传感器。压力传感器制备封装完毕后,利用电学修正技术使多晶硅纳米薄膜压敏电阻更精确地匹配。本文对压力传感器的制备流程进行了完整描述,在25℃至200℃的温度范围内,测试了压力传感器的性能。压力传感器的满量程为0.6MPa,在25℃和200℃时,灵敏度分别为22.19mV/V/MPa和18.30mV/V/MPa;在没有外界补偿的情况下,灵敏度的温度系数约为?0.10%/℃。在25℃和200℃时,失调分别是1.653mV和1.615mV, 失调的温度系数约为?0.013%/℃. 由于电学修正多晶硅纳米薄膜具有良好的压阻特性和温度稳定性,压力传感器表现出较好的性能。     

多晶硅薄膜的结构与电学特性关系的研究

多晶硅薄膜的性质与膜的结构有密切关系。界面结构主要指晶粒尺寸、择优取向及其结构。多晶硅薄膜的结构主要由沉积条件、膜厚、掺杂条件和后来的退火温度和退火时间所决定。本文讨论了用常规低压化学汽相淀积（ＬＰＣＶＤ）方法制备的多晶硅薄膜的结构特性，初步获得了提高多晶硅压力传感器灵敏度及其温度稳定性的条件。     

《低压化学气相淀积(LPCVD)硅膜的磷掺杂》

低压CVD生成的多晶硅膜的导电性已作过测定并与常压下淀积的硅膜进行了比较。低压硅膜是在580℃和620℃下淀积的,用离子注入进行磷掺杂。620℃下淀积的是多晶硅膜,而580℃下淀积的是非晶体,但很容易在进一步的热处理中变为晶体。我们用两种磷剂量的低压硅膜就退火温度对电阻率的影响进行了研究,发现电阻率随退火温度的增加而减小。退火后580℃下淀积的硅膜的电阻率总是低于620℃下淀积的硅膜。退火温度较低时这种差別更为显著。在第二组试验中,磷注入在很宽的掺杂范围进行。相当于2×10~(15)-2×10(20)/Cm~3的平均杂质浓度。在小于6×10~(16)/Cm~3和大于2×10~(18)/Cm~3时,电阻率仅随杂质浓度缓慢变化,但在中间范围内,轻微的浓度变化就能使电阻率发生剧烈改变。同前面叙述的一样,580℃下淀积的硅膜的电阻率总是最低的,尤其是在中间掺杂范围内。经测定发现霍耳迁移率在杂质浓度为6×10~(18)/Cm~3左右为最大,并且在杂质浓度降低时迅速减小。这种观察到的性能与含有大量载流子陷阱的晶粒边界所包围的小微晶组成的硅膜中得到的结果相一致。在集成电路工艺中,多晶硅有许多重要的应用。在硅栅集成电路中,重掺杂的多晶硅膜用来作栅极(1),轻掺杂多晶硅膜通常在静态存储器中作高阻值电阻(2)。不久以前这些薄膜还是在大气压下放在凉内壁反应器中进行淀积的。硅衬底平放在反应器中一个由外部加热的基座上。已有许多研究人员对这种薄膜的电学性能作过报告。(4—8)近几年来,发展起一种低压化学气相淀积(LPCVD)系统(9)。这些系统的高容量和低成本使它们很快为集成电路制造厂家所采纳。由于这种反应器中的淀积速率、温度和压力与通常的显著不同,有必要对这种LPCVD反应器中淀积材料的电学性能作一研究。尤其重要的是这种薄膜在杂质浓度大范围变化时的电阻率情况和它在温度变化时的稳定性。斯坦福大学正在对这种低压下淀积的多晶硅的性能进行探讨研究。其研究的第一部分,报告了低压(系统)的结构、多晶硅膜及其在进一步热处理中的稳定性(10),本文将讨论磷注入低压多晶硅的电学性能并与那些常压下淀积的薄膜进行比较。不同退火温度对电阻率的影响也将加以报告。     

多晶硅横向压阻灵敏度的统计分析

本文用统计方法对择优生长的多晶硅横向压阻进行了分析:计算了<100>、<110>、<111>、<211>、<221>、<311>、<331>等低指数晶向择优生长的P型和N型多晶硅横向平均晶粒压阻系数;采用全空间统计平均的方法,计算得到了晶向完全随机的多晶硅横向平均晶粒压阻系数;从欧姆定律和多晶硅晶粒特性出发,推导了多晶硅横向压阻灵敏度的表达式。通过实验测量了多晶硅横向压阻器件的灵敏度及其与角度的关系,证实多晶硅横向压阻灵敏度与器件倾角α符合sin2α的关系。将实验结果与理论分析的结果相比较后,得到了多晶硅的杨氏模量,这些结果表明多晶硅横向压力传感器具有实用价值,并为器件提供了优化的设计方案。     

多晶硅薄膜内应力的SEM测定法

多晶硅膜内应力的存在影响传感器的性能.本文介绍了内应力的SEM测定法和减小应力的途径.1 多晶硅微结构多晶硅膜采用LPCVD方法淀积,淀积温度为650℃,低压约为133Pa,微结构如图1所示.改变多晶硅微结构的长、宽及膜的厚度,得到不同的微结构.供SEM观察用,具体尺寸见表1.     

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。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.