碳化硅薄膜的ICP浅刻蚀工艺研究

选用SF6/O2 混合气体对等离子体增强化学气相淀积( PECVD)法制备的碳化硅( SiC)薄膜进行了浅槽刻蚀,并通过正交试验设计方法,研究了感应耦合等离子体( ICP)刻蚀技术中反应室压强、偏压射频( BRF)功率、O2 比例三个工艺参数对碳化硅薄膜刻蚀速率的影响及其显著性.实验结果表明:BRF功率对于刻蚀速率的影响具有高度显著性,各因素对刻蚀速率的影响程度依次为BRF功率>反应室压强>O2 比例,并讨论了所选因素对碳化硅薄膜刻蚀速率的影响机理.     

一种优化等离子体刻蚀工艺去静电步骤的方式

该文研究并优化了等离子体刻蚀后、去静电过程中等离子体辅助晶片去静电的工艺步骤。通 过数据模拟和实验设计,研究了极板间距、反应室压力、射频电源功率和射频电源关闭方式对晶片残存电荷的影响。首先,采用基于蒙特卡罗随机数方法的应用软件 Pegasus 对去静电过程中反应室内的等离子体分布进行了模拟,研究了等离子体能量分布图并分析了极板间距与等离子体分布均一性的关系,得到最佳极板间距范围。其次,以反应室压力、射频电源功率与极板间距为实验变量,通过实验设计得到残余电荷量最少的实验组。最后,以该实验组为基础,对射频电源的关闭方式进行优化,通 过检测晶片脱离吸附装置时的电势差,得到最优射频电源关闭方式。该文研究结果可用于优化晶片去静电步骤,进而提高工艺可靠性和产品良率。     

辉光放电等离子体灭菌技术的研究

讨论了低气压空气下气压对辉光放电现象、气体放电起始电压和放电电流等的影响.实验结果表明,随气压升高辉光放电现象的扩散性和极板间辉光的颜色均发生了比较大的变化,气压升高后放电时极板间辉光发生了持续的震荡.在一定范围气压内,放电起始电压和放电电流随着气压的升高而增大;等离子体等效电路的参数随着反应气体压强的变化而发生了变化.利用空气放电生成的等离子体进行灭菌实验.取得了良好的灭菌效果.     

4H-SiC ICP深刻蚀工艺研究

SiC是一种新型的半导体材料,由于化学性质十分稳定,目前还未发现有哪种酸或碱能在室温下对其起腐蚀作用,因此,在SiC的加工工艺中常采用干法刻蚀。采用GSE 200plus刻蚀机对SiC进行刻蚀,研究了刻蚀气体、源功率RF1、射频功率RF2及腔室压强对刻蚀结果的影响,并对产生的结果进行了相关分析。提出了一种SiC ICP深刻蚀方法,对SiC深刻蚀技术具有重要的指导意义。     

等离子体和反应离子刻蚀硅的各向异性 及均匀性实验研究

在反应离子刻蚀(RIE)及等离子体刻蚀(PE)设备中,分别采用CF_4,SF_6,NF_3和C_7F_(14),腐蚀剂气体,对(100)Si进行刻蚀.研究了工艺条件对刻蚀各向异性及均匀性的影响.结果表明,RIE的各向异性与均匀性均优于PE.RIE的各向异性值A与刻蚀气体中的添加剂成份有关,添加20%Ar时A最大值为5.4;添加20%C_2F_5Cl时,A值可高达10以上.在RIE中,CF_4和NF_3,的刻蚀均匀性优于SF_6,最佳刻蚀均匀性平均值优于5%,添加剂对刻蚀均匀性没有明显的影响.而PE显示各向同性的刻蚀特征,均匀性约为16.5%.并对各向异性及均匀性的起因作了解释.     

Pyrex玻璃的ICP刻蚀技术研究

以SF6/Ar为刻蚀气体,采用感应耦合等离子体(ICP)刻蚀Pyrex玻璃,研究气体流量、射频功率对刻蚀速率及刻蚀面粗糙度的影响.采用正交实验方法找出优化的实验参数,得到Pyrex玻璃刻蚀速率为106.8 nm/min,表面粗糙度为Ra=5.483 nm,实验发现增加自偏压是提高刻蚀速率、减小刻蚀面粗糙度的有效方法.     

ICP工艺参数对刻蚀Pyrex玻璃影响的实验研究

影响ICP刻蚀的工艺参数包括反应室压力,偏置射频功率,氩气流量比率。通过正交试验的方法,以CHF3和Ar的混合物作为反应气体,利用电感耦合等离子体技术刻蚀Pyrex玻璃。并采用回归分析方法建立了二次回归方程模型描述腐蚀速率和三个因素之间的关系。实验结果表明,氩气的流量比率（总气体流量（CHF3+Ar）是恒定的）对刻蚀速率的影响最大,影响程度的主次顺序为氩气的流量比率,反应室压力,偏置射频功率。腐蚀速率和三个因素之间的数学表达式为：腐蚀速率=532.6800+2.0556×Ar+0.0127×（偏置射频功率）-0.9641×压力-0.0655×Ar2-0.0067×Ar×（偏置射频功率）+0.0217×（偏置射频功率）×压力-0.0504×（压力）2,实验结果证明数学拟合结果良好。     

小型化离子漏斗设计与仿真

离子漏斗是一种新型的离子传输装置,可在高气压下聚焦离子,大幅提高离子的传输效率。针对经典离子漏斗几何尺寸较大的问题,设计了一种小型化离子漏斗。通过优化电极间距等几何参数对其离子传输性能进行优化,采用电场模拟软件SIMION和离子轨迹仿真软件AXSIM,对具有不同几何参数的小型化离子漏斗进行了模拟。模拟结果表明:在离子漏斗电极厚度为0.5 mm的情况下,当电极间距为1.6 mm时,离子的传输效率达到最高。进一步研究了电参数对小型化离子漏斗性能的影响。结果表明:在射频频率为0.5 MHz、射频电压为100 V且直流电压梯度为9.1 V/cm时,该漏斗对于质荷比大于100 Da的离子传输效率达到95%。经优化后的小型化离子漏斗总体外形为圆柱结构,其长度和径向直径均小于36 mm,可用于小型化质谱仪的开发。     

微机械陀螺的刻蚀误差特性分析

微陀螺仪结构上的腐蚀凹槽或腐蚀腔可以由深层反应离子刻蚀技术得到,加工过程中存在的刻蚀误差对微陀螺的固有频率、输出精度和稳定性有重要的影响.采用有限元分析软件ANSYS建立了一种梳状微机械陀螺的有限元分析模型,采用解析的方法并通过Matlab数学软件进行仿真,研究了由于加工误差导致微梁过度刻蚀对微陀螺驱动模态、检测模态、固有频率、带宽、灵敏度的影响.结果表明,微梁刚度和微陀螺固有频率随着刻蚀角度的增大而增大;最大过度刻蚀角度为±2度时,其驱动模态和检测模态的固有频率的变化率均超过了14%;刻蚀误差会导致微陀螺工作模态降阶,以及干扰模态介于与驱动和检测模态之间且与驱动模态频率相近,这会严重影响微陀螺的输出精度;带宽随过度刻蚀夹角增大而减小,灵敏度随过度刻蚀夹角的变化而发生不规律变化;当刻蚀角度介于0°~1.5°时,微陀螺的灵敏度将高于无刻蚀误差时微陀螺的灵敏度.     

ICP刻蚀硅形貌控制研究

硅的刻蚀形貌控制是MEMS器件加工中的关键技术之一,形貌控制是硅表面刻蚀和钝化反应取得平衡的结果,任何影响刻蚀和钝化反应的因素都会影响到刻蚀形貌.采用中科院微电子研发中心研制的基于化学平衡原理的ICP-98A等离子刻蚀机,对ICP刻蚀当中影响形貌的关键工艺参数进行了研究和分析,研究了源功率RF1、射频功率RF2及气体(...     

Investigation of fused silica glass etching using C4F8/Ar inductively coupled plasmas for through glass via (TGV) applications

Through glass via (TGV) technology is considered to be a cost effective enabler for the integration of micro electromechanical systems and radio frequency devices. Inductively coupled plasma and Bosch etching process comprise one of the most pervasive methods for through silicon via (TSV) formation. Unfortunately an equivalent process for glass etching remains elusive. In this paper, the influence of plasma etching for fused silica glass were investigated to find the best tradeoff between etch rate and profile of TGVs. The process parameters including bias power, gas flow rate, ratio of etching gases and reaction chamber pressure using Ar/C₄F₈ inductively coupled plasmas were studied. The etching results show that all these three parameters have a significant impact on the etch rate. Furthermore, the adjustment including total flow rate and ratio of Ar/C₄F₈ and chamber pressure can be used to control the via profile. Constant fused silica glass etch rate greater than 1 μm/min was obtained when chiller temperature was 40 °C with etching time of 60 min. The profile angle of TGVs with nearly 90° was also achieved.     

Real-time virtual metrology and control for plasma etch

Plasma etch is a semiconductor manufacturing process during which material is removed from the surface of semiconducting wafers, typically made of silicon, using gases in plasma form. A host of chemical and electrical complexities make the etch process notoriously difficult to model and troublesome to control. This work demonstrates the use of a real-time model predictive control scheme to control plasma electron density and plasma etch rate in the presence of disturbances to the ground path of the chamber. Virtual metrology (VM) models, using plasma impedance measurements, are used to estimate the plasma electron density and plasma etch rate in real time for control, eliminating the requirement for invasive measurements. The virtual metrology and control schemes exhibit fast set-point tracking and disturbance rejection capabilities. Etch rate can be controlled to within 1% of the desired value. Such control represents a significant improvement over open-loop operation of etch tools, where variances in etch rate of up to 5% can be observed during production processes due to disturbances in tool state and material properties.     

Regulation of plasma discharge using fuzzy logic and an in-situ plasma sensor

A new strategy for regulating a plasma discharge is presented. This is accomplished by using a fuzzy logic and a non-invasive in-situ plasma sensor. Using the sensor, fundamental plasma characteristics were collected and these characteristics include plasma density, ion flux, and electron temperature. For the collected data, fuzzy logic was used to identify the relationship between the process parameters and plasma characteristics. The process parameters of concern include a radio frequency source power, SiH₄ flow rate, and N₂ flow rate. For each of the plasma characteristics, a fuzzy logic model was developed. Another fuzzy controller was then applied to regulate the plasma characteristics as a function of the process parameters. Evaluation of the presented control model shows an error of less than 3% in most of the plasma characteristics. The performance of the plasma regulator under noisy environments provided information useful for regulator design, such as the existence of a minimum level of noises and the high sensitivity of fuzzy logic models to noises in a regulation system with high regulation errors.     

一种基于MEMS技术的压电微泵的研究

介绍了一种基于MEMS技术的压电微泵。该微泵利用聚二甲基硅氧烷(PDMS)作为泵膜,使用了一个主动阀和一个被动阀,并利用压电双晶片作为驱动部件。压电双晶片和PDMS泵膜的组合可以产生较大的泵腔体积改变和压缩比,显著降低了加工成本,并提高了成品率。对压电微泵的输出流量进行了测试,结果显示:电压、频率以及背压对流量均有显著影响。在100 V,25Hz的方波驱动下,该压电微泵的最大输出流量为458μL/m in,最大输出压力为6 kPa。     

Dynamic characteristics of a piezoelectric driven inkjet printhead fabricated using MEMS technology

To understand the residual vibration of the piezoelectric diaphragm in a piezo (PZT) driven inkjet printhead fabricated on silicon wafers by MEMS manufacturing process, the transfer function of the piezo velocity to sinusoidal input voltage is obtained in the experiments. The piezo velocity can be predicted using the obtained velocity transfer function with discrete Fourier transform of a trapezoidal waveform. In the low amplitude of voltage waveform, the spectrum shows a good agreement between the predicted and measured velocities of the piezo diaphragm. However, when the drop is ejected from the nozzle orifice with actual amplitude of the voltage waveform, the spectrum of the piezo velocity shows more complicated frequency components due to the reflected pressure waves and fluid motion inside the chamber. In this study it has been attempted to obtain the transfer function of the piezo velocity to the voltage input when the drops are fired. The simulated results of the piezo displacement with the various durations of the voltage waveform show a good agreement with the drop volume and velocity measured in experiments. In addition, it was found that suppressing the residual oscillations was closely related to eliminating the satellite drop formation, which was confirmed with the strobe stand drop visualization.     

基于SIMION仿真的高场非对称波形离子迁移谱谱图峰辨识

高场非对称波形离子迁移谱仪FAIMS(High-Field Asymmetric Waveform Ion Mobility Spectrometry)由于工作在敞开大气压条件下,易受空气中杂质干扰,因而在实际样品分析过程中通常会检测到不止一个峰,这对要观察的目标样品离子的辨识造成一定困难,目前多采用FAIMS和质谱仪联用的方式予以辨识。为解决上述FAIMS和质谱仪联用结构复杂的问题,本研究通过分析丙酮样品在紫外灯电离源下产生的几种主要离子,对比SIMION仿真和实验FAIMS谱图中各离子峰对应补偿电压(Compensation Voltage)随射频(Radio Frequency)RF电压幅值的变化曲线,根据其平行关系初步推断出FAIMS谱图中对应的3种主要离子:丙酮单体离子[M+H]+、丙酮二聚体离子[2M+H]+和水合质子(H2O)nH+。并通过理论分析了仿真和实验补偿电压曲线近似平行的原因。理论分析和仿真结果相吻合,证明了该方法的正确性。     

Radio‐frequency plasma‐display cell

Abstract— This paper demonstrates that it is possible to improve the basic parameters of plasma displays (efficiency, primarily) using AC voltages with frequencies so high that the amplitude of the electron‐drift oscillations is smaller than the inter‐electrode gap. In this case, the voltage drop on sheaths is much smaller than that in the low frequency or DC discharge and, correspondingly, the energy losses in ion heating are also small. Electron losses in the RF discharge are of the diffusion character and sufficiently lower than the losses in a typical AC plasma‐display panel (AC PDP), in which the electron drift to the electrodes is predominant. Hence, the energy cost of gas ionization in the cells of radio‐frequency PDPs (RF PDPs) is also rather low. In the long run, about 80% of the energy absorbed in the RF discharge goes into excitation of the energy level of a Xe atom, yielding UV radiation. The experiments performed show that efficiency of a RF PDP is five times higher than the efficiency of existing AC PDPs and DC PDPs and can exceed 5 lm/W.     

Vertical Thermopiles Embedded in a Polyimide-Based Flexible Printed Circuit Board

A fabrication process for vertical thermopiles embedded in a 75-mum-thick polyimide foil has been developed for flexible printed circuit boards (flex PCBs). The vertical connections consist of electrodeposited antimony-and nickel-plated through-hole vias. The plated through-hole vias consist of multiple wires, with a total metal content that is 1% of the total via volume. The via fabrication technique is similar to standard flex PCB wet etch and metallization processes. The main difference is that the foils are pretreated with ion irradiation to induce highly selective vertical etch rates. The thermopiles were characterized by measuring their voltage response to an applied temperature difference across the foil thickness.