Sequential modeling of via formation in photosensitive dielectricmaterials for MCM-D applications

Multichip module (MCM) technology is considered a strategic solution in electronics packaging because this approach offers significant advantages in electrical and thermal performance and reliability. However, manufacturing cost is a critical issue for mass production of high-performance MCM packages. To realize low-cost manufacturing technology, process modeling, optimization, and control techniques are required. In this paper, a modeling approach for via formation in MCM dielectric layers composed of photosensitive benzocyclobutene (BCB) is presented. A series of designed experiments are used to characterize the via formation workcell (which consists of the spin coat, soft bake, expose, develop, cure, and plasma descum unit process steps). The output characteristics considered are film thickness, refractive index, uniformity, film retention, and via yield. Sequential neural network process models are constructed to characterize the entire process. In the sequential scheme, each workcell subprocess is modeled individually, and each subprocess model is linked to previous subprocess outputs and subsequent subprocess inputs. This modeling scheme is compared with both the global and unit process modeling approaches to evaluate model prediction capability. The sequential method shows superior capability, with an average rms prediction error of 6.40% over all responses, compared to a 11.61% rmse for the global model and a 12.05% error for the unit process models     

Time series modeling of photosensitive polymer development rate for via formation applications

Via formation is a critical process in multichip module (MCM) manufacturing, as it greatly impacts yield, density, and reliability. For via formation using photosensitive polymers such as benzocyclobutene (BCB), development is an extremely important step, and insuring adequate time for the completion of polymer dissolution is the key to defining the desired via pattern. To simultaneously optimize via yield and process throughput, the proper development time needs to be identified. However, it is difficult to determine the development endpoint because it is very sensitive to several process and material conditions. In this paper, a neural network-based time series modeling scheme is developed and applied to determine the optimal endpoint for photosensitive BCB development. The Lithacon 808 Process Analyzer, which is typical of this type of system, is used to demonstrate the approach. To characterize the development step, exposure dose energy and time series data consisting of previous film thickness measurements are used to model expected film thicknesses at future times. Model prediction results are compared with experimental results, and it is shown that the neural time series model can effectively characterize the effects of changes in exposure dose energy on development endpoint.     

Optimization of via formation in photosensitive dielectric layersusing neural networks and genetic algorithms

Via formation using photosensitive polymer technology can reduce process cost by reducing process complexity and is hence of great interest in electronics packaging substrate fabrication. However, to overcome technical difficulties and to facilitate low-cost manufacturing, process modeling, optimization and control are required. In this paper, a process optimization approach for via formation in dielectric layers composed of photosensitive benzocyclobutene (BCB) for high density interconnect (HDI) in MCM-L/D substrates is presented. A series of designed experiments are used to characterize the via formation workcell (which consists of the spin coat, soft bake, expose, develop, cure, and plasma de-scum unit process steps). Neural network process models are then constructed to characterize via yield and geometry, as well as film thickness, retention, and uniformity. These models are used for process optimization using genetic algorithms (GA's) and hybrid combinations of GA's with the Powell algorithm and with the simplex algorithm. The optimized process recipes are verified experimentally. Comparison of the three approaches reveals that the hybrid GA/simplex method yields superior recipes     

合理占用空间的智能数模转换控制系统

提出一种节省印制电路板空间的智能数模转换控制方法，系统以AT89C51为主体构成控制电路，通过MAX232芯片接收上位机发送的命令，控制串行数模转换器MAX517输出模拟量，以便控制设备。着重介绍了8位串行数模转换器MAX517的特性，并详细说明了AT89C51单片机与MAXS17和MAX232的硬件连接与软件编程方法。     

Versatile threshold voltage control of OTFTs via discontinuous pn-heterojunction formation

We demonstrate the versatility of the threshold voltage control for organic thin-film transistors (OTFTs) based on formation of discontinuous pn-heterojunction on the active channel layer. By depositing n-type dioctyl perylene tetracarboxylic diimide molecules discontinuously onto base p-type pentacene thin films (the formation of the discontinuous pn-heterojunction), a positive shift of the threshold voltage was attained which enabled realizing a depletion-mode transistor from an original enhancement-mode pristine pentacene transistor. Careful control of the threshold voltage based on this method led assembling a depletion-load inverter comprising a depletion-mode transistor and an enhancement-mode transistor connected in series that yielded tunable signal inversion voltage approaching 0 V. In addition, the tunability could be applied to improve the program/erase signal ratio for non-volatile transistor memories by more than 4 orders of magnitude compared to reference memory devices made of pristine pentacene transistors.     

Intelligent bounds on modeling uncertainty: applications to sliding mode control

Robust control techniques such as sliding mode control (SMC) require a dynamic model of the plant and bounds on modeling uncertainty to formulate control laws with guaranteed stability. Although techniques for modeling dynamic systems and estimating model parameters are well established, very few procedures exist for estimating uncertainty bounds. In the case of SMC design, a conservative global bound is usually chosen to ensure closed-loop stability over the entire operating space. The primary drawbacks of this conservative, "hard computing" approach are excessive control activity and reduced performance, particularly in regions of the operating space where the model is accurate. In this paper, a novel approach to estimating uncertainty bounds for dynamic systems is introduced. This "soft computing" approach uses a unique artificial neural network, the 2-Sigma network, to bound modeling uncertainty adaptively. This fusion of intelligent uncertainty bound estimation with traditional SMC results in a control algorithm that is both robust and adaptive. Simulations and experimental demonstrations conducted on a magnetic levitation system confirm these capabilities and reveal excellent tracking performance without excessive control activity.     

基于模糊逻辑的智能群体编队移动控制方法

针对群体移动过程中,各个智能体因受力波动较 大,而导致群体运动振荡的问题,提 出了一种基于分布式人工势场法与模糊控制相结合的控制算法。通过分析群体运动过程中单 智能体的受力情况,建立耗散力对移动中振荡进行优化,减小群体移动中的振荡负面影响, 提高群体运动的一致性。建立保持力对编队稳定和保持进行优化,提高编队的稳定性。将优 化过后的合力作为模糊控制器的输入,通过强化学习适应环境变化,调节参数控制输出,实 现群体跟随移动控制。此外,给出了可自动调整大小的多种编队控制生成模型,实现群体编 队移动控制。仿真结果表明能 稳定、有效控制群体跟随移动,编队移动中能有效避障,可使 编队提升移动效率和保持拓扑稳定性。     

基于CPCI总线的智能A／D，D／A模块设计

A/D和D/A接口在工业控制应用中普遍存在,这就促使了基于各种接口的A/D,D/A模块的诞生.基于CPCI总线的A/D,D/A模块通过CPCI总线与主机通信,通过A/D接口采集电压信号,经过伺服控制软件处理.输出模拟量驱动执行机构.该模块使用DSP芯片对数据进行实时处理,通过CPCI总线进行快速的数据传输.在实际应用中得到了可靠性、实时性等方面验证.     

BCB/SiO_2双导芯层叠ARROW结构压力传感器设计

针对传统ARROW压力传感器耦合长度长以及耦合效率低,提出了BCB/SiO2双导芯层叠ARROW结构压力传感器。在外力作用下,弹性薄膜上的BCB/SiO2双导芯层叠ARROW结构,会因光弹效应致使BCB和SiO2两个导芯折射率变化产生输出相位差。通过有限元方法(FEM)研究硅弹性薄膜上导芯折射率的变化与应力分布关系,确定传感器的结构设计参数。使用束传播法(BPM)分析耦合结构以及压力与输出之间的关系。结果表明,该传感器无需弯曲波导即可降低器件尺寸,并实现了灵敏度为5.2×10-2/kPa压力检测。     

D/A conversion interface design for DMT-ADSL applications

For high-speed internet access, high-performance analog front-ends are needed, and data converters are one of the crucial building blocks in these bent-ends. In this article we will report on the modeling and design of a D/A conversion interface for a DMT (discrete multi tone)-based ADSL system that could be integrated into a complete CMOS analog front-end. We will discuss the DMT transmit spectrum and its impacts on data converters, we will focus on modeling and simulating of the whole D/A interface, and we will describe a test chip implemented in a 0.6 μm CMOS process     

Study of the Fabrication of BCB Waveguide Devices by Ultraviolet Pulsed-Laser Illumination

Benzocyclobutene directional couplers and 1times2 multimode interference (MMI) power splitters fabricated by ultraviolet (UV) pulsed-laser illumination are presented. With an accurate control of the fabrication process, the measured coupling lengths of the directional couplers are in good agreement with those simulated by the beam propagation method. In particular, accurate power splitting ratios of the directional couplers can be achieved by controlling the number of laser shots to obtain the required index changes. Moreover, MMI power splitters with accurate interference lengths and low imbalances can be successfully fabricated. All those reveal that UV pulsed-laser illumination is an accurate and controllable technique for the device fabrication.     

Intelligent control of quadruped gallops

In this paper, a new intelligent control approach for high-speed quadruped bounding and galloping gaits is presented. The controller is capable of learning the leg touchdown angles and leg thrusts required to track the desired running height and velocity of a quadruped in only one stride. Training of the controller is accomplished not with a mathematical model, but with simple rules based on a heuristic knowledge of the quadruped mechanics. The result is a controller that produces better velocity and height tracking characteristics than a Raibert-based controller and is robust to modeling errors. Additionally, by making use of the natural dynamics of the system, gait characteristics comparable to biological quadrupeds result. The status of a legged machine being constructed for demonstration of the control approach and further study of the characteristics of galloping is also presented.     

XtremePCB在数模混合PCB设计中的应用

针对现代电子产品对PCB设计的需求,重点介绍了XtremePCB协同布局布线工具在数模混合电路中的设计流程和应用。通过多人的协同合作应用,可以大大提高设计效率,缩短PCB的设计周期,保证项目的进度。     

QoS control by means of COPS to support SIP-based applications

The COPS protocol has been designed to enable communication on the interface between the policy decision administrator and the policy enforcement devices in a policy-based networking environment. It can be recognized that on the same interface there is the need to transfer information related to the request of resource by QoS clients and for the allocation of resources by resource allocation servers (e.g., bandwidth broker) in a DiffServ network. Hence, it is sensible to add this resource allocation functionality in the COPS framework. In particular, there are at least two cases where it is sensible to use COPS. The first case is on the interface between an edge node and a resource control node for handling resource allocation in a network provider domain. The second case is on the interface between a customer (client of a QoS enabled network) and the network provider: here COPS can be used as a protocol to signal dynamic admission control requests. In this article we present the definition of a new COPS client type to support the above-mentioned functionality, then describe an application scenario where SIP-based IP telephony applications can use Diffserv-based QoS networks. Simple backward-compatible enhancements to SIP are needed to interact with COPS/Diffserv QoS. A testbed implementation of the proposed solutions is finally described     

光敏杂化溶胶-凝胶法研制多模干涉波导分束器

采用有机/无机杂化溶胶-凝胶方法制备高质量的SiO2薄膜和光敏性薄膜材料;利用三维FD-BPM(finitedifference beam propagation method)研究了掩埋式和暴露式矩形波导结构多模干涉(MMI)型光功率分束器的主要性能,理论模拟发现,掩埋式矩形波导结构分束器的长度、宽度和厚度容差性都优于暴露式矩形波导结构的MMI型分束器,并且具有更宽的带宽特性。通过简单的紫外曝光、显影工艺制备了1×4 MMI型波导分束器,分束器在1 550 nm波长附近的插入损耗为8.1～8.8 dB,功率分束不均匀性小于1 dB。     

基于BCB的薄膜多层基板在毫米波T/R组件中的应用

基于BCB的薄膜多层基板具有优异的高频特性,是毫米波频段多芯片组件集成封装的重要途径。研究了BCB薄膜多层基板在Ka波段相控阵雷达T/R组件中应用的可行性,首先与LTCC基板对比验证了BCB微带线的传输特性,然后研制了功率分配/合成器、穿墙过渡等关键微波无源电路,最后设计了八通道的无源组件进行微波性能测试评估,结果表明基于BCB的薄膜多层基板能够满足应用需要。     

A fast latching current comparator for 12-bit A/D applications

Describes a novel monolithic high-speed comparator which senses the polarity of the input current rather than voltage. The new approach greatly reduces overall system conversion time for a successive approximation 12-bit A/D converter. The circuit features a single input pin for polarity discrimination, dual complementary outputs, and fast response time of 72 ns to 0.5 LSB overdrive (500 nA). The sum of the total error due to the comparator is 0.2 LSB with respect to the input. The comparator is manufactured on a bipolar, ion-implanted base, 9 /spl mu/m epi, junction-isolated process.     

A fast, latching comparator for 12 bit A/D applications

High-speed, 12 bit accurate successive approximation A/D converters demand a comparator with both excellent input specifications and fast response time. The author describes a voltage comparator with 50 ns response time to 1/2 LSB overdrive (1.2 mV) and 0.1 LSB (250 /spl mu/V) total input error. Unique features of the circuit include a super-/spl beta/ input stage, a fast buried-zener level-shift, a fully differential output stage, a floating-zener biasing scheme, and a fast latch circuit which does not interfere with input accuracy. The comparator is manufactured on a bipolar, double-implanted, thin epi, junction-isolated process.