砷化镓0.5μm PHEMT开关标准工艺研究

采用PCM技术对砷化镓0.5μmPHEMT开关工艺关键工艺步骤进行定量严格监控,并对关键工艺节点进行工序能力评价(Cpk),运用统计过程控制(SPC)技术对采集的工艺数据进行分析,实现了开关工艺的稳定受控,工艺水平不断提高,砷化镓单片开关的成品率逐步提升;同时采用REM技术对该工艺制作的PHEMT开关器件、无源元件进行可靠性的预先估计,实现了对该标准工艺的可靠性评估。研究数据表明,砷化镓0.5μmPHEMT开关标准工艺PCM成品率达到90%,开发的单片开关和衰减器成品率不低于80%;砷化镓单片开关在最高工作温度85°C、置信度90%下失效率λ小于400Fit,完全满足产品的使用要求。     

Analysis of Temperature in Phase Change Memory Scaling

We analyze constant-voltage isotropic and non-isotropic scaling issues for phase change memory (PCM) based on electrothermal physics. Various analytical and simulation models of general and typical PCM cells that support the analysis is also provided. The analysis shows that the maximum temperature in the PCM cell, which is a key parameter for PCM operation, is independent of geometrical sizes and depends only on the voltage and material properties. This leads to the minimum programming voltage concept, which is determined by material properties of the phase change material. Constant-voltage scaling, electrothermal modeling, ovonic unified memory (OUM), phase change memory (PCM, phase change random access memory, PRAM), proximity disturbance, thermal disturbance.     

Optimum Weighted PCM for Speech Signals

Weighted digital modulation schemes which provide bit error probabilities matched to the PCM bits with respect to their sensitivity to digital errors are analyzed. The channel is additive, white Gaussian. The PCM system has arbitrary code, companding law and input signal density function. Especially optimum weighted PSK/PCM and QAM/PCM are given for speech signals. The average channel signal to noise ratio is kept constant when schemes are compared. We obtain a channel signal to noise ratio gain in threshold extension of 2 dB for standard 8 bit PCM. The performance of suboptimum schemes, where the number of different bit error probability levels are smaller than the number of PCM bits are also studied. Two levels per 8 bit PCM word yield more than half of the achievable gain (in dB) and 4 levels is almost equal to optimum.     

Yield sensitivity of HEMT circuits to process parameter variations

The authors summarize the use of a graphical tool, yield factor histograms, to study the yield sensitivity of HEMT circuits to process parameter variations. A computer program called SPICENTER is used to incorporate the HEMT statistical physical model with a SPICE circuit model and then to generate the yield factor histograms and yield sensitivities as functions of the process parameters. The authors present the application of these tools to digital and microwave circuits. Two example HEMT circuits, a two-input NOR gate and an inverter chain, illustrate the concepts. Yield sensitivity is presented as yield percent change per parameter percent change     

一个集成电路工艺诊断实例

介绍了一种计算机自动PCM(process control module)工艺参数分析系统,可用于集成电路制造过程中的工艺诊断和分析.在具体处理上应用了主成分分析方法,能够从大量数据中提取其统计特征,根据这一特征可找出造成工艺波动的关键因素.从所给出的具体诊断实例来看,该方法能够得出一般人工诊断所不能得出的诊断结论,效果较好,是实施严格生产控制的有效工具.     

电子元器件相变冷却的数值传热研究

随着电子元器件功率的增大,冷却设计对保证电子元器件正常工作起着非常重要的作用.采用相变冷却技术,即将相变材料引入热沉,研究相变材料-热沉系统在凝固过程中的传热规律.研究结果发现,该系统在有翅片的情况下,凝固过程进行得很迅速,即翅片对凝固过程的传热强化作用非常明显;而且自然对流对此系统凝固过程的影响很大;另外,对不同温度下,相变在热沉内的凝固过程进行了研究,发现外部温度越低,凝固时间越短,在不同的温差下,液态相变材料在热沉内部自然对流的情况也有差异.     

A robust joint source channel coding scheme for image transmission over the ionospheric channel

In this paper, we propose a joint source channel coding (JSCC) scheme to the transmission of fixed images for wireless communication applications. The ionospheric channel which presents some characteristics identical to those found on mobile radio channels, like fading, multipath and Doppler effect is our test channel. As this method based on a wavelet transform, a self-organising map (SOM) vector quantization (VQ) optimally mapped on a QAM digital modulation and an unequal error protection (UEP) strategy, this method is particularly well adapted to low bit-rate applications. The compression process consists in applying a SOM VQ on the discrete wavelet transform coefficients and computing several codebooks depending on the sub-images preserved. An UEP is achieved with a correcting code applied on the most significant data. The JSCC consists of an optimal mapping of the VQ codebook vectors on a high spectral efficiency digital modulation. This feature allows preserving the topological organization of the codebook along the transmission chain while keeping a reduced complexity system. This method applied on grey level images can be used for colour images as well. Several tests of transmission for different images have shown the robustness of this method even for high bit error rate (BER>10⁻²). In order to qualify the quality of the image after transmission, we use a PSNR% (peak signal-to-noise ratio) parameter which is the value of the difference of the PSNR after compression at the transmitter and after reception at the receiver. This parameter clearly shows that 95% of the PSNR is preserved when the BER is less than 10⁻².     

在标准参数测试系统上开发CV分析功能——用于MOS器件参数失效分析

为了及时、直接分析PCM参数异常及电路失效原因,我们在标准参数测试系统(如HP4062,Ag4070系列)上开发了MOSC-V测试分析功能。鉴于目前MOS工艺水平不断提高,硅表面空间电荷区少子产生寿命在数百μs以上,传统C-V分析技术往往不能对参数失效电路进行有效分析。为此我们开发了一个新的C-V分析模式。给出了用此分析模式对CMOS产品的MOSC-V测试分析结果。并简要说明如何利用C-V技术分析PCM参数异常及电路失效的方法。     

The improved gray scale and the coarse-fine PCM systems, two new digital TV bandwidth reduction techniques

Two new digital television bandwidth-reduction techniques are presented with experimental results. Each provides twice the efficiency of a conventional pulse code modulation (PCM) system with similar picture fidelity, and each is simple and feasible for present-day spacecraft Implementation. The Improved Gray Scale PCM system effectively eliminates, by an averaging process, the gray scale contouring effect encountered in low-bit digital TV systems. The Coarse-Fine PCM system is somewhat more complex, but provides a higher fidelity reproduction of the original picture. The basic principles of operation of these two new data-compression techniques are given along with comparative pictorial results.     

Assessing the effectiveness of feature groups in author recognition tasks with the SOM model

The present paper focuses on studying the effectiveness of the self-organizing map (SOM) when applied to the task of categorizing a corpus of texts according to the style of their authors. This task is of particular importance for information retrieval applications using very large databases of documents. The emphasis of this article is to determine the extent to which the SOM possesses the ability to analyze such data, successfully uncovering the stylistic differences among authors in an unsupervised manner. To that end, a variety of feature vectors are studied, each of which either 1) comprises a single category of linguistic features or 2) spans several different categories of linguistic features, in order to determine the effectiveness of each feature category. It is shown that the highest accuracy is achieved when using a vector covering multiple linguistic categories. A comparison of the results obtained to the results of statistical methods indicates the ability of the SOM network to reveal the clustering potential of isolated parameter groups and its effectiveness in handling efficiently high-dimensional data vectors. Potential extensions to related text-organization techniques, such as the WEBSOM, thus become evident.     

印制电路组件三防涂覆工艺研究

对于特殊环境条件下使用的电子产品,三防涂覆可以对印制电路组件进行有效的防护.针对C型聚对二甲苯气相真空沉积涂覆技术,通过印制电路组件三防涂覆工艺研究及测试,验证了涂覆后的绝缘、耐压电性能等指标.结合印制电路组件涂覆后的返修,经过实验对比,确定了去涂覆的工艺方法.     

Fabrication process not limited by the lithography resolution of lateral phase change memory

To improve the performance of phase change memory (PCM) and reduce the cost of fabrication, we propose a new lateral PCM structure based on the technology of angle evaporation to define the critical dimension controllable, not limited by the limitation of lithography resolution. The fabrication process is cost-effective. PCM cells featured 80 nm×100 nm were successfully demonstrated, although the resolution of the aligned used was 1 µm only. Compared with the traditional lateral PCM structure, finite element simulation results show that the new structure has better thermal stability.     

A Per-Channel A/D Converter Having 15-Segment µ-255 Companding

This paper describes a companded analog-to-digital (A/D) converter for voiceband signals that is simple and potentially inexpensive. The converter uses only 18 coarsely spaced analog levels. Fine resolution is obtained by oscillating between these levels at an increased speed and averaging the result over a Nyquist interval. The companding used in the converter is effectively the same as that of μ-255 pulse-code modulation (PCM). In the encoding process a one-bit code is generated at 256 000 samples/s. This 1-bit per sample signal can be transmitted and decoded directly, or a simple digital circuit will produce a 13-bit, 8-kHz linear PCM signal that can be compressed to 8-bit companded PCM format. In this paper the basic operation of the 1-bit coder is described and its performance when connected to a 1-bit decoder is illustrated. Methods for obtaining both linear and compressed PCM are then presented, and the properties of these PCM signals with respect to noise, gain tracking, and harmonic content are described. Relative insensitivity to circuit component variations, absence of analog gates, along with the need to generate only a few analog levels, make the coder especially well suited to integrated circuit realization.     

MOS器件中寄生双极型晶体管模型参数的提取

在晶体管GP模型基础上,采用Silvoca公司的UTMOST模型参数提取程序,得到一种双极型晶体管模型参数的提取方法.用此方法对PCM测试芯片的寄生三极管进行参数提取和模拟,模拟结果与测试结果符合得较好.     

封装有相变材料的热沉结构对电子器件高温保护的传热分析

电子器件在工作过程中有可能由于突增电流而产生大量的热量,利用固液相变潜热存储系统,可以使得电子器件在一定的时间内保持相对平稳的温度,从而达到高温保护的目的。针对一种封装有相变材料的热沉结构在自然对流冷却条件下的传热特性进行了理论分析,得到了热沉、相变材料和空气的平均温度及相变材料的相变过程,并对比分析了同一热沉结构和自然对流冷却条件下,在不同热流密度下高温保护时间以及对流换热特性。     

Annual performance enhancement of building integrated photovoltaic modules by applying phase change materials

The performance of photovoltaic (PV) module outdoors suffers from attained high module temperatures due to irradiation as a result of the negative temperature coefficient of their efficiency. Phase change materials (PCMs) are investigated as an option to regulate photovoltaic module temperature and thereby reduce its electrical efficiency decrease. In this study, a simplified heat balance model is used to calculate the extra energy gain; such a PV/PCM system can bring on an annual basis. With present day commercially available PCM materials, a moderate increase of up to 3% of the total energy output can be expected. When taking into account the additional PCM material cost, a PV/PCM module presently is not economically viable. For an acceptable payback period of 10–20 years to be reached, the heat storage capacity of a PCM would require an increase of about one order of magnitude, which is presently not realistic. Nevertheless, a combination with building climate control in which the PCM plays a double role controlling both the PV temperature as well as the inside climate temperature may be feasible. Copyright © 2011 John Wiley & Sons, Ltd.     

E~2PROM擦/写特性的PCM研究

使用薄隧道氧化层浮栅器件逐渐成为在电可擦除稳定的存储器中一个标准[1]，根据E~2PROM工艺特点，本文着重分析了E／W后学元开启电压和E／W时间。E／W电压、隧道扎面积的关系。给出了开发和研究E~2ROM器件模型的工艺评价用PCM及常规用PCM的测试结果，为E~2PROM的工艺开发和实现提供有力的帮助。根据浮栅E~2PROM的物理模型[2]，建立了存储单元的阈值电压模型，利用该模型研究了存储单元E／W后同值电压与物理尺寸、E／W电压、E／W时间的关系。通过对这一关系更深入的认识，一方面在单元设计上有利于了解不同类型的E~2PROM，为减小器件尺寸以及今后开发业微米的设计规则作准备；另一方面，在工艺上建立一个准确的单元添件参数模型，得到各层次各关键工序的工艺评价参数，为制造高性能高可靠性的存储单元打下坚实基础。     

A fuzzy set approach for yield learning modeling in wafermanufacturing

The yield of semiconductor manufacturing can be improved through a learning process. A learning model is usually used to describe the learning process and to predict future yields. However, in traditional learning models such as Gruber's general yield model, the uncertainty and variation inherent in the learning process are not easy to consider. Also there are many strict assumptions about parameter distributions that need to be made. These result in the unreliability and imprecision of yield prediction. To improve the reliability and precision of yield prediction, expert opinions are consulted to evaluate and modify the learning model in this study. The fuzzy set theory is applied to facilitate this consulting process. At first, fuzzy forecasts are generated to predict future yields. The necessity of specifying strict parameter distributions is thus relaxed. Fuzzy yield forecasts can be defuzzified, or their α-cuts can be considered in capacity planning. The interpretation of such a treatment is also intuitive. Then, experts are requested to evaluate the learning model and express their opinions about the parameters in suitable fuzzy numbers or linguistic terms defined in advance. Two correction functions are designed to incorporate expert opinions in the learning model. Some examples are used for demonstration. The advantages of the proposed method are then discussed     

Multifunction SAG process for high-yield, low-cost GaAs microwaveintegrated circuits

A new fully planar, multifunction refractory self-aligned gate (MSAG) technology suitable for the fabrication of GaAs small-signal and power microwave monolithic integrated circuits (MMICs) is demonstrated in a manufacturing environment. Data on the distribution of DC and RF performance and yield for pilot production of discrete FETs and MMICs are presented. The heart of the MSAG process is a planar, self-aligned gate FET. It uses a refractory TiWN Schottky gate and exhibits high performance for small-signal microwave, power microwave, and digital circuit applications. Lots with good wafer yields have demonstrated average chip yields on PCM good wafers of 45%, 49%, and 36% for 2-10-GHz distributed amplifiers, 1-W C-band power amplifiers, and 4-W power amplifiers, respectively     

A neural-network approach to recognize defect spatial pattern insemiconductor fabrication

Yield enhancement in semiconductor fabrication is important. Even though IC yield loss may be attributed to many problems, the existence of defects on the wafer is one of the main causes. When the defects on the wafer form spatial patterns, it is usually a clue for the identification of equipment problems or process variations. This research intends to develop an intelligent system, which will recognize defect spatial patterns to aid in the diagnosis of failure causes. The neural-network architecture named adaptive resonance theory network 1 (ART1) was adopted for this purpose. Actual data obtained from a semiconductor manufacturing company in Taiwan were used in experiments with the proposed system. Comparison between ART1 and another unsupervised neural network, self-organizing map (SOM), was also conducted. The results show that ART1 architecture can recognize the similar defect spatial patterns more easily and correctly