厚膜混合集成电路的激光修调技术

本文从厚膜混合集成电路用激光调阻系统、切割图形、调阻工艺参数等方面介绍激光调阻技术的现状及发展。     

厚膜混合集成电路用的激光调阻系统

介绍厚膜混合集成电路用的激光调阻系统的机理，结构，切割图形及工艺参数。     

激光调阻预置式变速光刻控制

全自动激光调阻机是各种薄、厚膜片式电阻的工业化专用生产设备,提高调阻性能是提升设备生产力,降低生产成本,节能增效的主要途径.因此,在原系统基础上对激光调阻中光束定向控制系统进行改进设计,以先验知识为基础,构造预置、简单变速、实时变速等光刻控制模型,得到预置式变速光刻控制方法.它能根据不同的精度、速度要求和片阻初值偏差进行优化决策,实现在激光粗调电阻时,采用快速光刻;在激光精调电阻时,采用慢速光刻.这样不仅动态改变了片阻的光刻阻值变化率,提高了调阻精度,而且缩短了粗调光刻时间,提高了调阻速度,从整体上提高了激光调阻性能.     

激光调阻L型切割的仿真分析

激光调阻具有高效率、高精度,是目前制备高精度印刷电阻的通用方法,广泛应用于厚膜集成电路、厚膜传感器等。L型切割精度高,阻值稳定性好,是最常用的调阻切割路径。对不同L型切割尺寸切割后的电阻进行仿真,分析电阻上的电流密度和发热功率分布,得到的结果与实际经验吻合很好,对L型切割路径参数设置具有指导意义。     

用YAG声光调Q激光进行电阻调整

本文综述了用YAG声光调Q激光对薄、厚膜电路进行微调的原理、器件和光学系统。叙述了激光调阻的优点、工艺及影响激光调阻精度的几个参数。给出了激光调阻的二个实例。     

激光调阻工艺参数对调阻精度的影响分析

激光调阻的工艺参数主要包括光斑重叠率、激光功率、调Q频率和调阻速度 ,它们选择的合适与否直接影响激光调阻精度 ,如何确定激光调阻工艺参数是激光调阻控制中的重要问题。文中从理论分析和实验数据分析两个方面研究了激光调阻工艺参数对激光调阻精度的影响 ,并给出了激光调阻工艺参数之间的函数关系式和实际应用 ,为激光调阻工艺参数的选择提供了必要依据。     

片式电阻激光微调过程中的调阻精度控制

提出了一种基于激光刻蚀路径的修调电阻精度控制方法。该方法通过动态确定L型调阻图形的横、纵向切割长度实现对调阻精度的控制。存保证阻值测量精度的条件下,应用该法在0．1Ω～100MΩ的薄膜电阻阻值进行修调,调阻精度可达到1％。     

厚膜导体材料实现高精度功率电阻研究

由于高精度功率电阻的特殊要求，使用厚膜电阻浆料进行设计和加工往往比较困难。文中介绍一种使用厚膜导体材料，通过栅形导带和阶段性调阻等手段，使电阻满足功率和精度的要求，从而实现高精度功率电阻的方法。     

同一基片上制作两种薄膜方阻的电阻研究

薄膜混合集成电路与厚膜混合集成电路相比，其方阻的单一性影响了其更广泛的应用。本文介绍了在同一个薄膜基片上，用Cr-SiO材料制作高方阻电阻，用NiCr、Cr-SiO并联的方法制作小方阻电阻。通过实验及可靠性考核，制出了高精度、高可靠性的具有双方阻结构的混合集成电路薄膜电阻成膜基片。     

RuO_2基厚膜电阻电脉冲调阻工艺研究

用厚膜法制备了RuO2基厚膜电阻,研究了电阻值变化与脉冲电压的关系,分析了调阻工艺的特点;测量了电阻的可调整极限,目标值、偏差与初始电阻的特性,最佳阻值调整范围;研究了二次烧结对调整电阻值的影响规律。     

A Random Trimming Approach for Obtaining High-Precision Embedded Resistors

Embedded resistors will potentially allow electronic applications to cost less and perform better. However, it is difficult to fabricate embedded resistors to the correct resistance value, so embedded resistors are often fabricated with a lower value and then trimmed to raise the resistance to the desired value. A computer simulation for the trimming process of an embedded resistor has been developed that has been verified and calibrated against experimental results. A study of embedded resistors containing random voids of varying size has been performed. A new trimming strategy in which the trims are made randomly (rather than conventional L-shaped trims) is proposed and the results of the analysis demonstrate that single-dive trimming combined with random trimming allows higher precision embedded resistors to be obtained than conventional trimming patterns.     

An approach to ensure stability of precision laser trimmed thick film resistors

In view of its complete automation, very high throughput, least in process variation, etc., laser trimming has been an industry standard in thick film technology. Random variations in print thickness, uncertainty of sheet resistivity in a paste lot and other process variations in a production line make it difficult to ensure a reasonably good yield for high precision resistors, where the tolerances under consideration are of the order of ±0.30%. Special attention has to be given to the resistor configuration type of laser cut and post trim processing. The studies were performed on samples drawn from a regular production line which contained two resistor—one with AR (L/W) > 1 where an L cut/Vernier cut combination was used for trimming and the other with AR < 1 where a P cut/Vernier cut combination was used. The post trim resistors' performance was studied under two conditions—one at room temperature and the other after baking at 150°C for 100hr and then maintained at room temperature. These studies lead to the conclusion that for high precision resistors the resistors should be so designed that the L cut/Vernier cut combination can be adopted for trimming. Secondly the trimmed resistor should be stored at 150°C for a period of 100 hr to make the post trim behaviour more predictable and also to achieve better yield.     

Quantitative Analysis of Resistance Variations in Nickel-Phosphorus (NiP) Resistors

Embedded resistors can be fabricated by plating resistive Nickel-Phosphorus (NiP) alloy to form resistors on circuit boards. As-deposited NiP alloy resistors typically have poor resistance tolerances and require tuning by costly laser trimming to meet specifications. The cost of the resistors can be reduced if the tolerances can be reduced without laser trimming. In this study, a group of parameters affecting patterning accuracies, plating and sheet resistivities were varied to evaluate their effects on the resistance tolerances of electroless-plated NiP resistors. The effect of the substrate on sheet resistivity variations was also characterized. Design guidelines to obtain NiP resistors with low tolerance without laser trimming arc discussed.     

Polysilicon resistor trimming by laser link making

A technique for laser trimming of polysilicon resistors has been developed. In this scheme an undoped polysilicon film is patterned lithographically, and then photoresist patterns are used to prevent doping of certain narrow areas of each resistor during the impurity implant; thus, the protected areas remain insulating after wafer processing. Subsequent laser scanning of the undoped regions can produce precise reductions in resistance by lateral diffusion of dopant impurities. Trimming can be accomplished by changing either the laser power or the position. Q-switched Nd:YAG (1.06-μm wavelength) and second-harmonic (0.53-μm wavelength) radiations have produced successful results. The process was applied to passivated resistors with negligible (perhaps zero) post-trim drift, and the temperature coefficients of resistivity (TCRs) of trimmed resistors can be matched to the TCRs of untrimmed resistors in the same film     

A finite-mesh technique for laser trimming of thin-film resistors

A laser trimming technique in which a finite number of links are cut in a regular mesh of identical-valued resistors is described. The method eliminates long-term resistance drift due to slow annealing in the `heat-affected-zone' adjacent to the laser kerf. It is shown that the precision and resolution can be comparable to those achieved with conventional methods, and that quite wide ranges (up to 4:1) of absolute values can be obtained with small meshes. A computational method for constructing a lookup table of resistor values for different cut patterns is described     

应用无掩膜印刷术埋嵌微型聚合物厚膜电阻

Optomec公司开发了一种名为M3DTM的新型印刷技术,用于沉积高精度PTF(Polymer Thick Film)电阻。这种新方法生产出的电阻,面积小到0.05mm2,阻值范围达到100Ω-10000Ω,阻值公差能够保持在10%以内。M3DTM技术可以直接利用CAD文件决定电阻的位置以及阻值大小,而不需要制作掩膜模版,也不需要事后对阻值进行微调,是一种印刷埋嵌电阻的高性价比解决方案。     

一种片后数字修调技术及其应用

介绍了一种片后数字修调(Trim)技术。传统的修调技术一般是利用熔吹、激光或E2PROM对电路进行修正。该技术提出了一种可反复的修调方案,并可对电阻、电容等各种元器件进行调整,可广泛应用于一些要求出色动态特性的场合。设计中,将其应用于一个收发芯片的有源滤波器电路,实现了对滤波器截止频率的片后调整。     

Trimless high precision ratioed resistors in D/A and A/D converters

Investigations into realization of high precision ratioed resistors in standard CMOS and BiCMOS processes have been carried out. The results indicate that the layout of the resistors can be optimized with respect to area and matching requirements to yield relative accuracy better than 0.25%. Using an intermeshed ladder architecture, fast converters with resolution up to 10 b are realizable without trimming     

不用激光修调的高速12位D／A转换器

传统的集成12位D/A转换器要求用精密的薄膜电阻网络和电阻的激光修调技术。本文介绍的分段设计技术只需要采用常规的高速双极数字IC工艺,采用扩散电阻方法,不需要微调技术,就能保证其D/A的单调性。它比用激光修调的R—2R薄膜电阻网络结构的12位D/A转换器具有更均匀的台阶尺寸,其电阻的精度要求也比后者放宽了8倍;由于内部采用了ECL电路的结构形式,工作速度快,其建立时间在80～100ns。