BST薄膜的磁增强反应离子刻蚀研究

分别以CF4/Ar和CF4/Ar/O2作为刻蚀气体,采用磁增强反应离子刻蚀(MERIE)技术对sol-gel法制备的BST薄膜进行刻蚀。结果表明,刻蚀速率与刻蚀气体的混合比率呈现非单调特性。当CF4/Ar的气体流量比R(CF4:Ar)为10:40时,刻蚀速率达到极大值。当CF4/Ar/O2的气体流量比R(CF4:Ar:O2)为9:36:5时,刻蚀速率达到最大值,最大刻蚀速率为8.47nm/min。原子力显微镜(AFM)分析表明,刻蚀后的薄膜表面粗糙度变大。对刻蚀后的薄膜再进行适当的热处理,可以去除部分残留物。     

刻蚀小尺寸CCD接触孔工艺研究

采用CF4,CHF3,Ar三种工艺气体进行小尺寸CCD接触孔刻蚀实验,研究了不同气体配比、不同射频功率对刻蚀速率、选择比、条宽控制、侧壁形貌等参数的影响。通过优化工艺参数,比较刻蚀结果,最终获得了适合于刻蚀CCD小孔的工艺条件。     

IGZO-TFT钝化层三元复合结构过孔刻蚀

IGZO-TFT钝化层设计三元复合过孔结构,出现了20%过孔相关不良。本文以CF4/O2为反应气体,采用控制变量法,从功率、气体成分和比例、压力等方面对氧化物TFT钝化层的电感耦合等离子体刻蚀机理进行研究。当钝化层为SiO2或SiNx单组分时,氧气可以促进刻蚀反应;随着CF4/O2比例增加,刻蚀速率先增大后趋于稳定,并且当CF4/O2=15/8时,刻蚀速率和均一性达到最优;与源功率相比,提高偏压功率在提升刻蚀速率中起主导作用,同时均一性控制在15%以内;当压力在4Pa以内时,刻蚀速率随着压力的降低而增加。据此分析,对复合结构SiNx/SiO2、SiO2/SiNx、SiNx/SiO2/SiNx的刻蚀过程进行优化,得到了形貌规整、无残留物的过孔,过孔相关不良得到100%改善。     

氮化硅的ECCP刻蚀特性研究

本文对氮化硅的增强电容耦合等离子刻蚀进行研究,为氮化硅刻蚀工艺的优化提供参考。针对SF_6+O_2气体体系,通过设计实验考察了功率、压强、气体比、氦气等对刻蚀速率和均一性的影响,并对结果进行机理分析和讨论。实验结果表明:功率越大,刻蚀速率越大,与源极射频电力相比,偏置射频电力对刻蚀速率的影响更为显著;压强增大,刻蚀速率增大,但压强增大到一定程度后,刻蚀速率基本不变,刻蚀均匀性随着压强增大而变差;在保证SF_6/O_2总流量保持不变下,O_2的比例增大,刻蚀速率先增大后减小,刻蚀均匀性逐步变好;He的添加可以改善刻蚀均匀性,但He的添加量过多时,会造成刻蚀速率降低。     

RIE工艺参数对4H-SiC刻蚀速率和表面粗糙度的影响

基于4H-SiC材料的微机电系统(MEMS)器件(如压力传感器、微波功率半导体器件等)在制造过程中,需要利用干法刻蚀技术对4H-SiC材料进行微加工.增加刻蚀速率可以提高加工效率,但是调节刻蚀工艺参数在改变4H-SiC材料刻蚀速率的同时,也会对刻蚀表面粗糙度产生影响,进而影响器件的性能.为了提高SiC材料的刻蚀速率并降低刻蚀表面粗糙度,满足4H-SiC MEMS器件研制的需求,本文通过优化光刻工艺参数(曝光模式、曝光时间、显影时间)获得了良好的光刻图形形貌,改善了刻蚀掩模的剥离效果.实验中采用SF6和O2作为刻蚀气体,镍作为刻蚀掩模,分析了4H-SiC反应离子刻蚀工艺参数(刻蚀气体含量、腔体压强、射频功率)对4H-SiC刻蚀速率和表面粗糙度的影响.实验结果表明,通过优化干法刻蚀工艺参数可以获得原子级平整的刻蚀表面.当SF6的流量为330 mL/min,O2流量为30 mL/min,腔体压强为4 Pa,射频功率为300 W时,4H-SiC材料的刻蚀速率可达到292.3 nm/min,表面均方根粗糙度为0.56 nm.采用优化的刻蚀工艺参数可以实现4H-SiC材料的高速率、高表面质量加工.     

PZT薄膜的深槽反应离子刻蚀研究

研究了锆钛酸铅(PZT)薄膜的深槽反应离子刻蚀(DRIE)技术。首先,对比了3种工艺气氛条件下(SF6/Ar、CF4/Ar和CHF3/Ar)刻蚀PZT的效果。实验结果表明,3种工艺气氛下,刻蚀速率都随功率的增加而增加。相同功率下,SF6/Ar的刻蚀速率最高;而CHF3/Ar刻蚀PZT的图形形貌最好,对光刻胶的选择比也最好。最后得出了优化的工艺条件为采用CHF3/Ar,射频(RF)功率为160 W,气体流量比为3∶4(CHF3∶Ar=30 cm3/min:40 cm3/min)时,PZT薄膜的刻蚀速率为9 nm/min,光刻胶的选择比为7。     

用于垂直腔面发射激光器的GaAs/AlGaAs的ICP刻蚀工艺研究

采用电感耦合等离子体(ICP)刻蚀设备对应用于垂直腔面发射激光器的GaAs/AlGaAs材料进行刻蚀工艺研究。该刻蚀实验采用光刻胶作为刻蚀掩模,Cl2/BCl3作为刻蚀工艺气体,通过实验分析总结了ICP源功率、射频偏压功率和腔体压强对GaAs/AlGaAs材料和掩模刻蚀速率的影响。利用扫描电子显微镜观察不同参数条件对样品侧壁垂直度和底部平坦度的影响。最终在保证高刻蚀速率的前提下,通过调整优化各工艺参数,得到了侧壁光滑、底部平坦的圆台结构。     

Cl2/Ar感应耦合等离子体刻蚀Si工艺研究

采用Cl2/Ar感应耦合等离子体（ICP）对单晶硅进行了刻蚀,工艺中用光刻胶作掩膜。研究了气体组分、ICP功率和RF功率等工艺参数对硅刻蚀速率和硅与光刻胶刻蚀选择比的影响,同时还研究了不同工艺条件对侧壁形貌的影响。结果表明,由于物理刻蚀机制和化学刻蚀机制的相对强度受到混合气体中Cl2和Ar比例的影响,硅刻蚀速率随着Ar组分的增加而降低,同时选择比也随之降低。硅刻蚀速率随着ICP功率的增大先增大继而减小,选择比则成上升趋势。硅刻蚀速率和选择比均随RF功率的增大单调增大。在Cl2/Ar混合气体的刻蚀过程中,离子辅助溅射是决定硅刻蚀效果的重要因素。同时,文中还研究分析了刻蚀工艺对于微槽效应和刻蚀侧壁形貌的影响,结果表明,通过提高ICP功率可以有效减小微槽和平滑侧壁。进一步研究了SiO2掩膜下,压强改变对于硅刻蚀形貌的影响,发现通过降低压强,可以明显地抑制杂草的产生。     

面向异质集成应用的BCB通孔刻蚀研究

针对基于外延层转移技术的InP HBT与Si COMS异质集成工艺中的器件互连问题,本文系统性地开展了ICP干法刻蚀BCB(苯并环丁烯)工艺研究.重点研究了射频功率、腔室压强和刻蚀气体SF6/O2体积比等条件对刻蚀速率、刻蚀通孔洁净度和通孔侧壁形貌的影响.在此基础上通过相关刻蚀工艺的合理优化,实现了孔深5μm、深宽比1...     

Cl_2/BCl_3ICP刻蚀GaN基LED的规律研究

研究了用Cl2/BCl3刻蚀GaN基LED中,工艺参数对GaN刻蚀速率、刻蚀侧壁和GaN与SiO2刻蚀选择比的影响。研究结果表明,刻蚀速率随着ICP功率和压强的增大先增大继而减小,随RF功率的增大单调增大;刻蚀选择比随ICP功率增大单调减小,随压强增大而增大。还研究了刻蚀速率和选择比与气体比例变化的关系。刻蚀SEM图表明,压强和RF功率增大会使刻蚀垂直度增大。     

用于非易失性相变存储器中Si2Sb2Te5在CF4/Ar等离子体下的反应离子刻蚀

Phase change random access memory（PCRAM） is one of the best candidates for next generation nonvolatile memory,and phase change Si₂Sb₂Te₅ material is expected to be a promising material for PCRAM.In the fabrication of phase change random access memories,the etching process is a critical step.In this paper,the etching characteristics of Si₂Sb₂Te₅ films were studied with a CF₄/Ar gas mixture using a reactive ion etching system.We observed a monotonic decrease in etch rate with decreasing CF4 concentration,meanwhile,Ar concentration went up and smoother etched surfaces were obtained.It proves that CF4 determines the etch rate while Ar plays an important role in defining the smoothness of the etched surface and sidewall edge acuity.Compared with Ge₂Sb₂Te₅, it is found that Si₂Sb₂Te₅ has a greater etch rate.Etching characteristics of Si₂Sb₂Te₅ as a function of power and pressure were also studied.The smoothest surfaces and most vertical sidewalls were achieved using a CF₄/Ar gas mixture ratio of 10/40,a background pressure of 40 mTorr,and power of 200 W.     

Reactive-ion etching of Ge2Sb2Te5 in CF4/Ar plasma for non-volatile phase-change memories

Etching of Ge₂Sb₂Te₅ (GST) is a critical step in the fabrication of chalcogenide random access memories. In this paper, the etch characteristics of GST films were studied with a CF₄/Ar gas mixture using a reactive-ion etching system. We observed a monotonic decrease in etch rate with decreasing CF₄ concentration indicating its importance in defining the material removal rate. Argon, on the other hand, plays an important role in defining the smoothness of the etched surface and sidewall edge acuity. We have studied the importance of gas mixture and RF power on the quality of the etched film. The smoothest surfaces and most vertical sidewalls were achieved using a CF₄/Ar gas mixture ratio of 10/40, a background pressure of 80 mTorr, and power of 200 W.     

Reactive ion etching of gallium nitride films

Reactive ion etching (RIE) was performed on gallium nitride (GaN) films grown by electron cyclotron resonance (ECR) plasma assisted molecular beam epitaxy (MBE). Etching was carried out using trifluoromethane (CHF₃) and chloropentafluoroethane (C₂ClF₅) plasmas with Ar gas. A conventional rf plasma discharge RIE system without ECR or Ar ion gun was used. The effects of chamber pressure, plasma power, and gas flow rate on the etch rates were investigated. The etch rate increased linearly with the ratio of plasma power to chamber pressure. The etching rate varied between 60 and 500Å/min, with plasma power of 100 to 500W, chamber pressure of 60 to 300 mTorr, and gas flow rate of 20 to 50 seem. Single crystalline GaN films on sapphire showed a slightly lower etch rate than domain-structured GaN films on GaAs. The surface morphology quality after etching was examined by atomic force microscopy and scanning electron microscopy.     

Effect of gas mixing ratio on etch behaviors of Ba2Ti9O20 (BTO) and Pt thin films in Cl2/Ar inductively coupled plasma

An investigation of the Ba₂Ti₉O₂₀ (BTO) and Pt thin films etch mechanism in the Cl₂/Ar inductively coupled plasma was carried out. It was found that an increase in Ar mixing ratio at fixed gas pressure and input power causes a fast decrease in the BTO etch rate (26.9-1.2 nm/min for 0-100% Ar) while the Pt etch rate increases slightly from 17.4-23.0 nm/min. Langmuir probe diagnostics and zero-dimensional plasma modeling provided the data on plasma parameters, steady-state composition and fluxes of active species on the etched surface. From the model-based analysis of etch kinetics, it was shown that the behavior of the BTO etch rate corresponds to the reaction-rate-limited etch regime, where the etch rate is limited neither by physical sputtering of the main material nor by the ion-stimulated desorption of low-volatile reaction products. The etch process of Pt appears in the transitional regime and is controlled by the neutral and ion fluxes together.     

Characterization of reactive ion etching of benzocyclobutente in SF6/O2 plasmas

This paper reports the reactive ion etching (RIE) characteristics of benzocyclobutene (BCB) in sulfur hexafluoride/oxygen (SF₆/O₂) plasmas. The dependence of etching rate and etch anisotropy on the processing parameters, including RF power, chamber pressure, and SF₆ concentration, are investigated comprehensively ranging from 50 to 200 W, 22.5 to 270 mTorr, and 0% to 80%, respectively. The BCB etching rate increases with chamber pressure and RF power in spite of nonlinearity, but decreases with the increase in SF₆ concentration. Anisotropic etching can be achieved using low chamber pressure, large RF power, and high SF₆ concentration. To avoid grass-like residue that happens at low pressure and large power fluorine-poor conditions, processing parameters with respect to residue-free etching are recommended. The etching mechanisms of the dependence of the etching characteristics on the processing parameters are discussed. Optimal processing parameters are presented as a guideline for isotropic etching of BCB as sacrificial layers to release structures and for anisotropic etching of BCB to precisely control etching dimensions and profiles.     

Etch damage evaluation on (Bi4−xLax)Ti3O12 thin films during the etch process using inductively coupled plasma sources

The etching mechanism of (Bi_4−xLa_x)Ti₃O₁₂ (BLT) thin films in Ar/Cl₂ inductively coupled plasma (ICP) and plasma-induced damages at the etched surfaces were investigated as a function of gas-mixing ratios. The maximum etch rate of BLT thin films was 50.8 nm/min of 80% Ar/20% Cl₂. From various experimental data, amorphous phases on the etched surface existed on both chemically and physically etched films, but the amorphous phase was thicker after the 80% Ar/20% Cl₂ process. Moreover, crystalline “breaking” appeared during the etching in Cl₂-containing plasma. Also the remnant polarization and fatigue resistances decreased more for the 80% Ar/20% Cl₂ etch than for pure Ar plasma etch.     

Dry etching characteristics of In1-x-y Ga x Al y as alloys in CCl2F2:Ar and CH4:H2:Ar discharges

The etching characteristics of InGaAlAs alloys lattice-matched to InP were investigated using low pressure (1 mTorr) electron cyclotron resonance CH₄:H₂:Ar or CCl₂F₂:Ar discharges with additional radiofrequency biasing of the samples. Using CCl₂F₂:Ar discharges with ≥250V negative bias it is possible to obtain equi-rate etching of the material for all compositions between In_0.53Ga_0.47As and In_0.52Al_0.48As. At lower bias values, formation of A1F₃ on the surface leads to an inhibition of the etch rates. By making use of the differential etch rates of InGaAlAs layers of different compositions in CH₄:H₂:Ar mixtures, it is possible to choose dc bias values that allow one to stop the etching at a pre-selected depth in a multi-layer structure. For example, for -150 V bias, one can etch through In_0.53Ga_0.47As, In_0.53Ga_0.40Al_0.07As and Ino.53Ga_0.30Al_0.17As layers, and stop at an underlying layer with composition In_0.53Ga_0.20Al_0.27As.     

SOI planar photonic crystal fabrication: Etching through SiO2/Si/SiO2 layer systems using fluorocarbon plasmas

Dry plasma etching of sub-micron structures in a SiO₂/Si/SiO₂ layer system using Cr as a mask was performed in a fluorocarbon plasma. It was determined that the best anisotropy could be achieved in the most electropositive plasma. A gas composition yielding the desired SOI planar photonic crystal structures was optimized from the available process gases, Ar, He, O₂, SF₆, CF₄, c-C₄F₈, CHF₃, using DC bias data sets. Application of the c-C₄F₈/(noble gas) chemistry allowed fabrication of the desired SOI planar photonic crystal. The average etching rates for the pores and ridge waveguide regions were about 71 and 97 nm/min, respectively, while the average SiO₂/Si/SiO₂ to Cr etching selectivity for the ridge waveguide region was about 33:1 in case of the c-C₄F₈/90%Ar plasma with optimized parameters.     

Characterization of the CH4/H2/Ar high density plasma etching process for HgCdTe

High density plasma etching of mercury cadmium telluride using CH₄/H₂/Ar plasma chemistries is investigated. Mass spectrometry is used to identify and monitor etch products evolving from the surface during plasma etching. The identifiable primary etch products are elemental Hg, TeH₂, and Cd(CH₃)₂. Their relative concentrations are monitored as ion and neutral fluxes (both in intensity and composition), ion energy and substrate temperature are varied. General insights are made into surface chemistry mechanisms of the etch process. These insights are evaluated by examining etch anisotropy and damage to the remaining semiconductor material. Regions of process parameter space best suited to moderate rate, anisotropic, low damage etching of HgCdTe are identified.