等离子体刻蚀过程中的FTIR监控技术

采用傅里叶红外光谱仪(FHR)和MCT红外探测器可以构成原位的FTIR测量系统,可应用于在电感耦合等离子体刻蚀机中进行的硅刻蚀工艺.文中对反应腔室腔壁状态对刻蚀过程的影响,以及在硅晶片表面反应层的变化进行了详细的研究.实验表明:采用含F化合物对反应腔室进行清洗会改变反应腔室的状态,在腔室内壁状态达到稳定之前会对刻蚀速率的一致性造成扰动.硅片表面反应层中的化学组成变成了以CF为主的薄膜层,对刻蚀过程的有一定的抑制作用.     

新型相变材料Al1.3Sb3Te使用CF4/Ar等离子体干法刻蚀

对使用CF4/Ar 混合气体刻蚀Al1.3Sb3Te的特性进行了研究。实验控制的参数是：气体流入刻蚀腔的速率,CF4/Ar 比例,O2的加入量,腔内压强以及加在底电极上的入射射频功率。总的气体流量是50sccm ,研究刻蚀速率与CF4/Ar的比例,O2加入量,腔内压强和入射射频功率的关系。最后刻蚀参数被优化。 使用优化的刻蚀参数CF4的浓度4%,功率300W,压强800mTorr,刻蚀速率达到70.8nm/min,刻蚀表面平整     

硅栅干法刻蚀工艺中腔室表面附着物研究

用Cl2,HBr,O2和CF4为反应气体,对多晶硅栅进行了刻蚀试验,并借助X射线能谱仪器En-ergy Dispersive X-ray Spectrometry(EDS)进行试验样品的化学成分测定和数据分析。结果表明,淀积附着物主要是以硅元素为主体,溴、氯和氧次之的聚合物,在淀积的动态过程中,HBr起到了主要的作用,Cl2和O2在一定程度上也促进了淀积过程的进行,在工艺过程中氟元素起到了清除淀积物的作用。最后通过试验得到了反应腔室表面附着物淀积的机理性结论。     

利用CF4等离子体制作高开口率TFT-LCD

为了获得高的开口率,有必要优化设计参数和工艺容差。通常的过孔刻蚀工艺采用SF6基气体进行刻蚀,但是这种方法在金属和钝化层之间的选择性太小,因此,必须增加过孔的尺寸才行。为了克服上述问题,在本研究中用CF4气体代替SF6气体进行刻蚀,结果在FFS 5 .16(2 .03 in)像素结构中,开口率提高了60 %。     

用于圆片级芯片尺寸封装的光敏聚合物的无氧低氟等离子去屑工艺

一种新型的无氧低氟等离子去屑工艺已开发应用于圆片级芯片尺寸封装。这种无氧去屑工艺。使用H2／N2混合气体作为主刻蚀剂，并携带微量含氟气体（CF4＜0.5%）。在H2／N2混合气体中添加CF4可加快BCB刻蚀速度。BCB刻蚀速度随温度上升而线性增加，并能在150℃至240℃的温度范围内作精确调整。已确认，对于BCB聚合物的去屑。这种无氧等离子工艺与传统的含氧离子工艺相比有着显著的优点，其中包括对二氧化硅和氮化硅上的BCB有极大的刻蚀选择率，而对铝、铜合金等金属引线无有害冲击。     

二氟化氙释放牺牲层多晶硅刻蚀速率研究

该文研究了相关工艺参数对二氟化氙(XeF_2)干法释放多晶硅的释放速率的影响。结果表明,对于薄膜体声波谐振器(FBAR)悬臂结构,腔室压力不变时,随着载气N_2流量的增大,刻蚀速率先增加后减少,刻蚀速率最大值为10.3μm/min;载气N2流量不变时,腔室压力越大,工艺腔室参与刻蚀反应的XeF_2气体的浓度增大,刻蚀速率越大。当腔室压力超过1 200Pa时,随着腔室压力的增加,刻蚀速率的增长率逐渐减小。     

ICP刻蚀技术在MEMS器件制作中的应用

简单介绍了ICP刻蚀系统和刻蚀原理。通过实验分析了ICP刻蚀SiO2和Cr时,刻蚀速率随相关工艺参数变化而变化的几点规律。同时给出了用ICP刻蚀出的MEMS传感器Si基腔的表面形貌图和Cr电阻的显微镜照片。     

MEMS/Sensor工艺中无定形碳应用及干法蚀刻研究

提出一套新的无定型碳牺牲层蚀刻工艺,新工艺应用于MEMS和Sensor牺牲材料工艺中,能够很好地解决无定形碳蚀刻工艺中有机副产物问题。在无定形碳蚀刻工艺中添加低浓度的CF4蚀刻气体(1%~5%),有助于去除在蚀刻过程中侧壁形成的有机副产物。在无定形碳蚀刻工艺前添加一步光刻胶硬化步骤,和在无定形碳蚀刻工艺后添加一步有机副产物各项异性蚀刻步骤,有助于去除表面产生的有机副产物。并针对新工艺去除无定形碳蚀刻过程中形成的有机副产物反应机制进行了详尽阐述与讨论。     

准分子激光刻蚀可变焦光路设计研究

为了研究在准分子激光刻蚀聚合物的过程中避免经常往复更换不同大小而形状相同的掩模的实验操作,保证实验的连续性和结果的真实性和可靠性,在实验的加工系统中基于变焦距系统的原理采用引入一个变焦物镜代替原来系统中普通物镜的方法,取得了一个准分子激光刻蚀可变焦光路系统.采用ZEMAX软件设计一个可变焦物镜镜头并分析了它的成像质量.经过ZEMAX软件的模拟,结果表明,此变焦镜头成像质量基本达到要求,缩小倍率在0.15～0.24范围内可连续变化.因此,使用这个变焦物镜,在同样的实验条件下,可以采用同一片掩模而不再往复更换掩模就可蚀刻出大小不同的结构;同时由于不再经常需要中断实验过程,保证了实验结果的真实性.该技术在激光蚀刻中有很大的可行性.     

CVD外延生长SiC薄膜的等离子体图形刻蚀研究

采用等离子体刻蚀工艺 ,以四氟化碳 ( CF4 )和氧气 ( O2 )的混合气体作为刻蚀气体 ,对常压化学气相淀积工艺制备的β- Si C单晶薄膜进行了系统的图形刻蚀研究。结果表明 ,在 Si C薄膜的等离子体图形刻蚀中 ,金属铝 ( Al)是一种很有效的掩模材料 ;可刻蚀出的图形最小条宽为 4μm,图形最小间距为 2μm,并且刻蚀基本为各向同性 ;文中还对影响图形刻蚀质量的一些因素进行了讨论。     

Polymeric arc chamber walls influence on AgW/AgC contact resistance

Contact resistance was measured after arcing for AgW moving against an AgC stationary contact pair in an arc chamber, Contact resistance, measured at five different current levels over the range of 2 kA_p to 22 kA_p, was compared using two different arc chamber wall materials, ceramic and polyester, to determine if gases evolved from the polyester during arcing produced contaminants on the contact surface causing a resistance increase. When compared to results using ceramic walls, polyester walls did not show any statistical difference in contact resistance. However, increased chamber pressure, resulting from ablation of the polyester walls, was measured; scanning electron microscope (SEM) photographs and energy dispersive spectroscopy (EDS) surface mapping measurements showed the change in resistance, for both wall materials, was due to a depletion of silver from the contact surface at mid-range arcing currents and redeposition of silver at higher arcing currents. Discussions include the effect of arc temperature on contact resistance and the various gases, generated by the ablation of the polymer walls, on resistance and arc chamber pressure     

交联剂对聚合物/液晶光栅的影响

利用激光干涉条纹引发预聚物／液晶混合物相分离．形成液晶与聚合物周期交替排列的液晶光栅。研究了组成材料中交联剂N-乙烯基吡咯烷酮（1-vinyl-2-pyrrolidone，NVP）对光栅形貌和衍射效率的影响，通过改变NVP的含量，分析NVP在光栅形成中的作用，确立了NVP的最佳含量。实验结果表明，NVP具有调节混合物系统官能度与体系黏度、交联密度及影响反应速度的作用，在适量的NVP含量下，光栅的衍射效率得到优化。     

Cover Picture: Hierarchically Organized Superstructure Emerging from the Exquisite Association of Inorganic Crystals,Organic Polymers,and Dyes: A Model Approach Towards Suprabiomineral Materials (Adv. Funct. Mater. 9/2005)

Suprabiomineral materials possessing hierarchically organized superstructures are investigated by Imai and Oaki on p. 1407. Inorganic crystals, organic polymers, and functional dyes have assembled via a simple biomimetic route into a superstructure that contains six different tiers, from the macroscale to the nanoscale. The hierarchy originates from the strong interaction between crystals and polymers and the diffusion‐controlled conditions. The versatile role of the polymer is found to be essential for the construction of a superstructure. This approach promises to generate novel types of functional materials with controllable structures and properties. We report a novel hierarchically organized superstructure emerging from an exquisite association of inorganic crystals, organic polymers, and dyes. The resultant K₂SO₄/poly(acrylic acid) composite includes five different tiers from the nanoscopic to the macroscopic. An additional new tier leading to functionality is formed by the incorporation of organic dyes that are organized in a nanospace. The emergent superstructure and properties are designed through changes in polymer concentration. The multiple roles of the polymer realize the generation of the architecture at each size scale. This model approach should be widely applicable to other systems, allowing for the preparation of innovative materials by an appropriate combination of crystals, polymers, and functional molecules.     

Optical diagnostics of plasma chemistries and chamber conditions in gate oxide stack etch

Various kinds of plasma chemistries were used in the study of polysilicon gate stack etch. Different degrees of gate oxide surface roughness were observed. Stable gate oxide thickness and smooth surface were found when using fluorine-based plasma chemistries. In contrast, non-fluorine-based chemistry tends to give uneven gate oxide thickness and rough surface. The stability of the gate oxide thickness can be controlled by chamber seasoning when using non-fluorine-based chemistry. It is also noticed that fluorine-based chemistries always result in thicker remaining gate oxide than the one without fluorine. The type of wafer used for seasoning can also have influence on chamber condition and subsequently the etch rates and gate oxide thickness. From the trends of emission intensity of Si, it is believed that etch byproducts as well as chamber wall polymer have potential impacts on the observed variation of gate oxide surface roughness, thickness, and etch rates.     

Generalized enhancement of charge injection in bottom contact/top gate polymer field-effect transistors with single-walled carbon nanotubes

We investigate the influence of small amounts of dispersed single-walled carbon nanotubes (SWNTs) on the contact resistance and device characteristics of bottom contact/top gate polymer field-effect transistors (FETs). Five conjugated polymers representing different classes of polymer semiconductors with different HOMO/LUMO levels are employed, namely, polythiophenes (P3HT), polyphenylenevinylenes (MDMO-PPV), polyfluorenes (F8T2), naphthalene-bis(dicarboximide) bithiophene copolymers (P(NDI2OD-T2)), and diketopyrrolo-pyrrole-bithiophene copolymers (DPPT-TT). In all cases the presence of dispersed SWNTs reduces non-ohmic contact resistance and lowers threshold and onset voltages for charge transport. In some cases inherent ambipolar charge transport in conjugated polymers (F8T2 and P(NDI2OD-T2)) is revealed. The concentration of the SWNTs within the semiconducting layer remains below the percolation limit and thus the apparent mobilities and on/off ratios are still determined by the polymer and independent of the specific type of the carbon nanotubes (metallic or semiconducting). The degree of enhancement depends both on the energy level offset between the injecting gold electrode and the HOMO/LUMO level (i.e., Schottky barrier) and the charge carrier mobility of the respective polymer. The simplicity of this injection enhancement method and its broad applicability make it a step toward high performance polymer transistors without injection limitations.     

Conducting‐Polymer Microcontainers: Controlled Syntheses and Potential Applications

We have demonstrated the controlled synthesis of conducting‐polymer microcontainers through the electrochemical generation of surfactant (i.e., β‐naphthalenesulfonic acid, β‐NSA)‐stabilized H₂ gas bubbles on the working electrode, followed by electrochemical polymerization of pyrrole around the wall of the “soap‐bubble” template. It was noticed that the density, shape, and wall thickness of the polypyrrole microcontainers thus prepared could be regulated by controlling the electrochemical potential applied for the generation of H₂ gas and the experimental conditions (e.g., the surfactant concentration, number of the cyclic voltammetric scanning) for the electropolymerization of pyrrole. By pre‐patterning the working electrode surface with non‐conducting polymers using microcontact printing (μCP) or plasma patterning, we have also produced conducting‐polymer microcontainers in a patterned fashion. Furthermore, potential applications of the patterned and non‐patterned conducting‐polymer microcontainers have been demonstrated; for example, through the encapsulation of appropriate fluorescence‐labeled molecules (e.g., fluorescein cadaverin) into the conducting‐polymer microcontainers by sealing their opened mouths with sequential electropolymerization of pyrrole. The resulting closed microcontainers could then be used for controlled releases.     

Role of CF2 in the etching of SiO2, Si3N4 and Si in fluorocarbon plasma

The CF2 density and etch rate of SiO2, Si3N4 and Si are investigated as a function of gas pressure and 02 flow rate in fluorocarbon plasma. As the pressure increases, the self-bias voltage decreases whereas the SiO2 etch rate increases. Previous study has shown that SiO2 etch rate is proportional to the self-bias voltage. This result indicates that other etching parameters contribute to the SiO2 etching. Generally, the CF2 radical is considered as a precursor for fluorocarbon layer formation. At a given power, defluorination of fluorocarbon under high-energy ion bombardment is a main source of fluorine for SiO2 etching. When more CF2 radical in plasma, SiO2 etch rate is increased because more fluorine can be provided. In this case, CF2 is considered as a reactant for SiO2 etching. The etch rate of Si3N4 and Si is mainly determined by the polymer thickness formed on its surface which is dominated by the CF2 density in plasma. Etching results obtained by varying O2 flow rate also support the proposition.     

碳氟等离子体中CF2对SiO2，Si3N4和Si刻蚀的作用

The CF2 density and etch rate of SiO2, Si3N4 and Si are investigated as a function of gas pressure and O2 flow rate in fluorocarbon plasma. As the pressure increases, the self-bias voltage decreases whereas the SiO2 etch rate increases. Previous study has shown that SiO2 etch rate is proportional to the self-bias voltage. This result indicates that other etching parameters contribute to the SiO2 etching. Generally, the CF2 radical is considered as a precursor for fluorocarbon layer formation. At a given power, defluorination of fluorocarbon under high-energy ion bombardment is a main source of fluorine for SiO2 etching. When more CF2 radical in plasma, SiO2 etch rate is increased because more fluorine can be provided. In this case, CF2 is considered as a reactant for SiO2 etching. The etch rate of Si3N4 and Si is mainly determined by the polymer thickness formed on its surface which is dominated by the CF2 density in plasma. Etching results obtained by varying O2 flow rate also support the proposition.     

用于聚合物基微流体MEMS的等离子体活性晶圆键合技术

Lab-on-chip或μ-TAS(micro-totalanalysissystems)结合流体处理、检测及数据分析,是一种便携式的低成本高效器件。在微流体应用中,聚合物具有比硅或玻璃器件更明显的优势,它包括:宽泛的材料选择性,成本低、效率高,使用任意性,生物兼容性,抗化学品和工艺灵活性。为了实现采用这类材料制备小型集成化系统,我们发展了新的制备与封装技术。这项工作着眼于运用等离子体活化低温直接键合技术实现纳/微结构聚合物在低温条件下进行封装。由纳米压印光刻制作的纳/微结构的聚合物器件,可能是异质(聚合物与玻璃或硅)或同质(聚合物与聚合物)键合。为了改进键合材料的物理和化学熔合,键合工序通常在接近聚合物的玻璃化转变温度的高温下进行。但遗憾的是,高温损伤了微细图形,特别是对于高深宽比结构。在EVG810LT 等离子体反应室里,我们采用软射频频率等离子体表面处理,来进行聚合物的等离子体活化,它能在不改变聚合物体特性的前提下清洗和活化聚合物顶层。最终结果是,在EVG501晶圆键合机上,两个活化的表面在低温下通过施加一个适中的、均匀的接触压力而连接在一起,保证了空腔密封并防止了小结构的破坏和变形。键合工艺条件为:真空条件为从大气到200~1000Pa、接触压力为2～5kN、温度从室温到80℃。RR