ICP刻蚀在GaAs p-i-n工艺中的应用

基于GaAs p-i-n器件的制造工艺,介绍了器件制造过程中关键工艺步骤p-i层的去除方法,并总结分析了在p-i层去除过程中不同的方法对工艺结果造成的影响。分别采用了湿法腐蚀和干法刻蚀的方法制作了器件,结果表明采用湿法腐蚀的方法去除p-i层时,由于腐蚀的各项异性造成的影响无法消除,会影响器件的性能。阐述了影响干法刻蚀的设备因素和工艺因素,讨论分析了不同的气体、腔体的真空度以及不同的功率对最终结果的影响。最终得到刻蚀均匀、稳定的干法刻蚀条件,将ICP干法刻蚀工艺引入GaAs p-i-n器件制造。     

Inductively coupled plasma etching of HgCdTe

The high-density inductively coupled plasma (ICP) etching technique has been applied to HgCdTe. The HgCdTe etch rate was studied as a function of key process variables commonly used in high-density plasma etching: chamber pressure, direct current (DC) bias, and ICP-source power. Mesa profiles were characterized using scanning electron microscopy (SEM), and the profiles for the process conditions used were found to be compatible with fabrication procedures for HgCdTe infrared focal-plane arrays (FPAs). The etch uniformity was measured to be better than 5% over a diameter of 6-in.     

蚀刻腔条件对刻蚀工艺的影响研究

在ULSI制造中蚀刻腔条件的变化是导致刻蚀工艺重复性差的一个重要原因.在刻蚀过程中,一层聚合物会淀积在蚀刻腔壁上.通过XPS分析得知,聚合物的主要成分为(CF2)n.实验过程发现不同的聚合物量会影响等离子体中CF2基团的浓度.聚合物越多,CF2浓度越高;反之,聚合物越少,CF2 浓度就越低.在这种情况下,蚀刻腔上的聚合物被认为是等离子中CF2基团的一个源.CF2浓度的变化又导致最终刻蚀特性(CD,蚀刻率)的变化和工艺漂移.     

基于电感耦合等离子体刻蚀的LNOI脊形微结构制备

铌酸锂(LiNbO₃,LN)是一种广泛使用的介电材料,由于其电光系数大,透明范围大,本征带宽宽,因而在集成和非线性光学器件中极为重要。但绝缘体上铌酸锂薄膜(LNOI)的化学稳定性好,刻蚀速率慢,其微结构参数难以控制。针对以上问题,该文开展了基于电感耦合等离子体刻蚀(ICP-RIE)的LNOI脊形微结构的制备工艺研究,分析了腔室压强、气体总流量及刻蚀功率等参数对刻蚀速率、刻蚀倾角和表面粗糙度(RMS)的影响。研究表明,在优化的工艺条件下,LNOI薄膜的刻蚀速率达到24.9 nm/min,制备出刻蚀深度249 nm、刻蚀倾角76°、表面粗糙度(RMS)0.716 nm的LNOI脊形微结构。该文通过对刻蚀工艺与微观结构参数的研究,建立了基于ICP的LNOI微结构刻蚀方法,为控制LNOI脊形光波导和提升性能提供了工艺支撑。     

Novel Single-Wafer Single-Chamber Dry and Wet Hybrid System for Stripping and In Situ Cleaning of High-Dose Ion-Implanted Photoresists

There is increasing demand for moving from batch immersion tools to single-wafer spin tools for silicon wafer cleaning, etching, and photoresist/residue removal in advanced semiconductor manufacturing. However, high-dodse ion-implanted photoresist removal using a conventional single-wafer spin tool is very difficult. We have developed a novel single-wafer single-chamber dry and wet hybrid system in combination with dry ashing and moderate-temperature wet-cleaning treatments by implementing an atmospheric-pressure plasma unit into a conventional single-wafer spin cleaning tool. This compact single-wafer single-chamber system can completely remove the hardened photoresist due to high-dose ion-implantation by an atmospheric-pressure plasma ashing process followed by an in situ wet chemical process in the same single chamber within 2 min. This single-wafer single-chamber dry/wet hybrid system offers less than 1/3 smaller footprint, less than 1/4 shorter cycle time (for 50 wafer processing), and potentially better process control and less contamination risk, as well as lower equipment cost, compared to the conventional combination of two separate dry- and wet-processing systems.      

等离子体刻蚀过程的APC技术研究进展

先进过程控制(APC)是一个多层次的控制系统,其包含了实时的设备及工艺控制和非实时的RtR控制.APC引入等离子体刻蚀过程控制可极大提高刻蚀机的使用效率.针对等离子体刻蚀过程,本文分别从实时控制和RtR控制两个不同层次展开了论述,概述了RtR控制器中所使用的线性回归模型和神经网络模型.最后,讨论了APC技术的发展趋势.     

α—Si TFT矩阵等离子体刻蚀技术的研究

本文介绍了α-Si TFT有源矩阵的CF_4等离子体刻蚀技术。分析了CF_4等离子体刻蚀α-Si:H和α-SiN_x的机理,对α-Si TFT的有源层与绝缘层之间刻蚀选择性和均匀性进行了研究,讨论了等离子体刻蚀速率与射频功率、反应室压力及衬底温度的依赖关系。根据实验结果总结了CF_4等离子体刻蚀速率随射频功率、反应室压力和衬底温度的增加而增大的规律,通过控制合适的工艺条件,成功地实现了选择性刻蚀并改善了刻蚀的均匀性。     

等离子蚀刻挠性PI基材制作悬空引线及其参数优化

悬空引线的制作是挠性印制线路板制作的难点之一,需要在基材的某些区域蚀刻掉PI（聚酰亚胺）基材来满足设计的要求。目前采用的在基材上开窗口的方法有机械冲切、数控铣、化学试剂蚀刻法和等离子蚀刻法等。其中,等离子蚀刻法加工精度高、操作简便、清洁环保,但由于运行成本相对较高使其生产应用受到了限制。本文通过正交设计试验优化等离子蚀刻PI的参数,以达到充分利用气体、缩短等离子蚀刻时间的目的,从而大大降低等离子蚀刻过程的成本。并最终完成悬空引线的制作。     

Statistical feedback control of a plasma etch process

This paper presents the methodology developed for the automatic feedback control of a silicon nitride plasma etch process. The methodology provides an augmented level of control for semiconductor manufacturing processes, to the level that the operator inputs the required process quality characteristics (e.g. etch rate and uniformity values) instead of the desired process conditions (e.g., specific RF power, pressure, gas flows). The optimal equipment settings are determined from previously generated process/equipment models. The control algorithm is driven by the in-situ measurements, using in-line sensors monitoring each wafer. The sensor data is subjected to Statistical Quality Control (SQC) to determine if deviations from the required process observable values can be attributed to noise in the system or are due to a sustained anomalous behavior of the equipment. Once a change in equipment behavior is detected, the process/equipment models are adjusted to match the new state of the equipment. The updated models are used to run subsequent wafers until a new SQC failure is observed. The algorithms developed have been implemented and tested, and are currently being used to control the etching of wafers under standard manufacturing conditions     

全固态高效率射频电源

射频电源作为微电子设备如刻蚀机、溅射台和PECVD等的核心部件,其性能的好坏直接关系到整个设备的性能。固态射频电源采用E类MOSFET功率放大器,通过适当的阻抗匹配网络,最终的射频电源在500 W的额定功率下,功率转换效率可以达到84%,微电子设备真空腔室内的等离子体启辉时,其阻抗变化范围很大且速度很快。目前匹配速度最快的MKS的自动匹配器(在允许匹配范围内匹配到50Ω时用时3~5 s)也很难实时跟上,所以固态射频电源必须能够承受500 W功率的反射至少3~5 s。经过实验后,本固态射频电源完全可以承受500 W功率的全反射30 s左右。     

Equipment modelling of CVD and etching

This paper presents results of equipment simulation giving applications of the fluid-dynamic solution to three commonly used reactors in the semiconductor industry — Tungsten CVD, Aluminum plasma etching, and Poly LPCVD. The results obtained include the determination of three-dimensional profiles for pressure, temperature, velocity, concentration of different chemical species, etch rates, deposition rates and uniformity over the wafer. This simulation technique is an important tool for equipment and process optimization by both the equipment suppliers and process engineers, because it allows a better visualization of the variables that control the process and allows a fast estimation of how changes on the process parameters or hardware configuration influence the results.     

等离子体刻蚀工艺中的OES监控技术

采用光学发射光谱(OES)原位检测技术,对等离子体刻蚀机中的等离子体状态进行实时监控,讨论了其在故障诊断、分类、刻蚀终点的判断及控制方面的应用。实验平台为在新研发的高密度等离子体刻蚀机,采用化学气体HBr/Cl₂为刻蚀气体进行多晶硅刻蚀工艺实验,实验过程中所采集的OES数据通过PCA法进行分析,得到与刻蚀过程相关的特征谱线。实验结果表明：OES技术适合于深亚微米等离子体刻蚀工艺过程的终点检测及故障诊断。最后就OES技术未来发展面临的挑战进行了讨论。     

SiC ICP背面通孔刻蚀研究

介绍了利用ICP设备,使用SF6基气体对4H-SiC衬底进行背面通孔刻蚀的技术。研究了金属刻蚀掩模、刻蚀气体中O2含量的变化、反应室压力、RF功率和ICP功率等各种条件对刻蚀结果产生的影响,重点对刻蚀气体中O2含量和反应室压力两个条件进行了优化。通过对刻蚀结果的分析,得出了适合当前实际工艺的优化条件,实现了厚度为100μm、直径为70μm的SiC衬底GaN HEMT和单片电路的背面通孔刻蚀,刻蚀速率达700nm/min,SiC和金属刻蚀选择比达到60∶1。通过对工艺条件的优化,刻蚀出倾角为75°～90°的通孔。     

ICP腔体压力对直流偏压的影响

基于GaAs器件干法刻蚀工艺,介绍感应耦合等离子(ICP)的刻蚀原理,以Cl2和BCl3为刻蚀气体,研究分析了在GaAs表面刻蚀工艺中不同的腔体压力下设备直流偏压的变化情况.发现在各种不同的功率下都存在一个特定的腔体压力,当低于该腔体压力时直流偏压会随腔体压力的增大而增加,当高于该腔体压力后直流偏压会随着腔体压力的增加而缓慢减小.讨论了产生这种现象的原因,揭示了其中的物理机理,以该方法作为参考,通过一组对比实验在工艺中得到验证,给出了GaAs刻蚀的工艺条件,为刻蚀工艺条件的优化提供了一个参考.     

高密度RF等离子体刻蚀工艺直流自我偏压的研究

直流自我偏压作为高密度射频(RF)等离子体刻蚀工艺中的重要电学参数,反映出具有高能量的离子对待刻蚀晶片的轰击效果,后者决定了刻蚀工艺的各向异性、刻蚀速率、选择比及形貌特征等工艺结果。该文以HBr作为刻蚀气体,采用电感耦合等离子体(ICP)金属刻蚀系统针对刻蚀工艺中的直流自我偏压进行研究。研究中分别改变离子源功率、衬底偏压功率、刻蚀压力及HBr气体流量,观察直流自我偏压及其峰值的相应变化规律。实验结果表明,随着离子源功率的升高,直流自我偏压将会轻度降低;升高偏压功率则会显著提升直流自我偏压。刻蚀压力与直流自我偏压呈正比例关系,HBr气体流量的变化及待刻蚀晶片的材质对直流自我偏压无显著影响。     

Effect of High-Density Plasma Process Parameters on Carrier Transport Properties in <Emphasis Type="Italic">p</Emphasis>-to-<Emphasis Type="Italic">n</Emphasis> Type Converted Hg<Subscript>0.7</Subscript>Cd<Subscript>0.3</Subscript>Te Layer

Exposure of p-type HgCdTe material to Ar/H₂-based plasma is known to result in p-to-n conductivity-type conversion. While this phenomenon is generally undesirable when aiming to perform physical etching for device delineation and electrical isolation, it can be used in a novel process for formation of n-on-p junctions. The properties of this n-type converted material are dependent on the condition of the plasma to which it is exposed. This paper investigates the effect of varying the plasma process parameters in an inductively coupled plasma reactive ion etching (ICPRIE) tool on the carrier transport properties of the p-to-n type converted material. Quantitative mobility spectrum analysis of variable-field Hall and resistivity data has been used to extract the carrier transport properties. In the parameter space investigated, the n-type converted layer carrier transport properties and depth have been found to be most sensitive to the plasma process pressure and temperature. The levels of both RIE and ICP power have also been found to have a significant influence.     

Plasma impedance monitoring for real time endpoint detection of bulk materials etched in ICP tool

Plasma impedance monitoring (PIM) based on electrical measurements is successfully used as an alternative to determine real time detection endpoint during plasma etching of structured bulk materials. In this paper we present the results with this technique for the endpoint detection during the etching of various materials.The endpoint conditions are tested in the sixth harmonic components of the electrical plasma parameters with an RF sensor. The endpoint is determined when an electrical parameter transition is observed. This transition corresponds to the change of the total reactor impedance, and allows the etching of the doped layer to stop on the bulk substrate.Using a Smith chart we determine the best harmonics/electrical monitoring couple parameters for processes on various materials. Resistivity measurements are used before and after etching in order to confirm the usefulness of the PIM method.In this paper, we also demonstrate how to monitor a real time control of non-uniformity during the reactive ion etching (RIE) process in the case of gallium arsenide etching.     

多晶硅清洗设备研究

介绍了多晶硅清洗设备,即：硅块、硅棒／硅芯清洗设备。并对其结构设计进行阐述。对设备关键部件-工艺槽、机械臂的设计进行了详细的说明。该设备满足了大规模生产的需要,能够保证产品的品质及生产效率。     

腔室状态对图形化蓝宝石衬底刻蚀工艺的影响

图形化蓝宝石衬底是近年来针对高度发光二极管的应用要求发展起来的一种新技术。通过利用自主研制的工业化感性耦合等离子体刻蚀机对图形化蓝宝石衬底的刻蚀工艺进行了研究。采用光学发射光谱仪和扫描电镜研究了PSS生产过程中腔室状态的变化对蓝宝石的刻蚀速率、选择比和图形形貌的影响。研究结果表明:随着反应腔累积放电时间的增加,刻蚀速率呈现下降趋势,选择比呈先上升然后下降的趋势。该趋势由反应腔室内表面上的沉积物所引起。     

Reactive Ion Etching of ITO Transparent Electrode of TFT—AMLCD in Ar／CF4 Plasma

Ｔhe pattern of ITO transparent electrode of pixel cells in TFTAMLCD is a critical step in the manufacturing process of flat panel display devices,the development of suitable plasma reactive ion etching is necessary to achieve high resolution display.In this work we investigated the Ar/CF4 plasma etching of ITO as function of different parameters.We demonstrated the ability of this plasma to etch ITO and achieved an etching rate of about 3.73nm/min,which is expected to increase for long pumping down period,and also through addition of hydrogen in the plasma.Furthermore we described the ITO etching mechanism in Ar/CF4 plasma.The investigation of selectivity showed to be very low over silicon nitride and silicon dioxide but very high over aluminum.