等离子体密度课件

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,内 容,一、等离子体刻蚀技术的发展趋势及存在的问题,二、几种有代表性的等离子体源,三、描述,DF-CCP,物理过程的,解析模型,四、描述,DF-CCP,物理过程的,混合模型,五、直流偏压效应,六、有关实验工作进展,内 容,一、等离子体刻蚀技术的发展趋势及问题,低温等离子体刻蚀技术,在微纳制造工艺中得到广泛地应,用，如超大规模集成电路、微机械系统、微光学系统的制,备。,1,）半导体芯片加工,2,）微电机系统（,MEMS),加工,3,）平板显示器的加工,4,）衍射光栅的制备,微齿轮,微结构,一、等离子体刻蚀技术的发展趋势及问题1）半导体芯片加工微齿轮,集成电路发展趋势,:,加工晶圆的面积更大,特征尺寸越来越小,集成度越来越高,对等离子体源的要求,:,高的刻蚀率,高度的均匀性,高度的各向异性,高度的选择性,较低的介质损伤,等离子体刻蚀工艺的趋势,集成电路发展趋势:对等离子体源的要求:等离子体刻蚀工艺的趋势,均匀性,刻蚀的均匀性包含两层意思：,1,）宏观的不均匀性,：在晶片的径向上造成的刻蚀率和刻蚀剖 面的不均匀性。,2,）微观不均匀性：,在每个微槽的底部和侧面造成的刻蚀不均匀性。,等离子体密度,0,R, 均匀性等离子体密度0R,为了适应纳电子器件的制备工艺，必须要：,1,）,提出大面积、高密度、均匀等离子体的新方法；,2,）,提出优化刻蚀工艺的新方法。,实验,(,或工艺,),研究,计算机仿真模拟,为了适应纳电子器件的制备工艺，必须要： 实验 (或工艺) 研,1,、平板式是射频容性耦合等离子体,(CCP),源,plasma,RF power,13.56MHz,进气,抽气,介质,电极,开始于上个世纪,70,年代，主要用于反应性等离子体刻蚀工艺。,单频,CCP,源的主要优点：,1.,工作气压比较低（,mTorr),2.,能够产生比较均匀的,plasma,3.,结构简单，造价低,.,二、几种有代表性的等离子体刻蚀源,1、平板式是射频容性耦合等离子体(CCP)源plasmaRF,根据熟知的定标关系可知：等离子体密度正比于驱动电源频率的平方和施加的偏压，即,当电源频率,w,一定时,要提高等离子体密度，唯一的途径是增加施加偏压。但增加施加的射频偏压时，轰击到晶片上的离子能量也随着增加。太高的离子能量，将对晶片造成不必要的介质损伤。,早期使用的都是单一频率射频电源（,13.56MHz),驱动放电的,CCP,源，很难实现对等离子体密度（正比于刻蚀率）和入射到晶片上离子的能量分布的独立控制。,根据熟知的定标关系可知：等离子体密度正比于驱动电源频率的,2,、微波电子回旋共振,(ECR)/RF,偏压等离子体刻蚀源,2、微波电子回旋共振(ECR)/RF偏压等离子体刻蚀源,等离子体密度课件,3,、射频感应耦合等离子体,( ICP)/RF,偏压刻蚀源,3、射频感应耦合等离子体( ICP)/RF偏压刻蚀源,RF biased electrode,wafer,coil,Insulating plate,平面线圈感应耦合等离子体源,主电源（连接在线圈）控制等离子体的状态；,偏压电源（施加在芯片台上）控制离子轰击晶片上的能,量分布。,RF biased electrodewafercoilIn,感应耦合等离子体,(ICP),源的特点,特点,解决的问题,工作气压低,( d.,x=0,x=d,LF,HF,One-dimensional model When the,Influence of HF-power frequency on plasma density,P = 100mTorr, V,h,= 200V, V,l,=400V,f,l,= 2MHz, f,h,= 20, 30, 60MHz,Influence of HF-power frequenc,P=50 mTorr, V,h,=50 V, V,l,=100V,f,h,=60 MHz, f,l,=2,5, 10, 13.56 MHz,Influence of LF-power frequency on plasma density,P=50 mTorr, Vh=50 V, Vl=100V,P = 100mTorr, V,h,= 200V, V,l,=400V,f,l,= 2MHz, f,h,= 20, 30, 60MHz,Influence of HF-power frequency on sheath voltage drop,平均鞘层电位降：,与解析模型的比较,P = 100mTorr, Vh = 200V, Vl,f,h,= 30MHz, P =50mTorr,V,h,= 200V, V,l,= 400V,f,l,= 2MHz,P = 100mTorr,V,h,= 200V, V,l,= 400V,离子入射到电极上的能量分布,fh = 30MHz, P =50mTorr, fl = 2,HF power,LF power,H,2R,D,Schematic diagram of DF-CCP,H= 2.45cm,2R=43.18cm,D=6.35cm,Two-dimensional model,HF powerLF power H 2R,I.,Influence of,high frequency,f,H,averaged electron density:,27MHz,40MHz,60MHz,V,HF,=50V,V,LF,=100V,f,L,=2,MHz, p=100,mTorr,The electron density increases,significantly,as increasing values of,f,L,.,I. Influence of high frequenc,averaged electron temperature:,27MHz,40MHz,60MHz,V,HF,=50V,V,LF,=100V,f,L,=2,MHz, p=100,mTorr,The electron density increases,slightly,as increasing values of,f,L,., averaged electron temperatu,II. influence of low frequency,12MHz,With the increase of low frequency, two sources become from decoupling to coupling, and the electron density increases significantly when two sources coupling.,2MHz,6MHz,averaged electron density:,V,HF,=50V,V,LF,=100V,f,H,=60,MHz, p=100,mTorr,II. influence of low frequency,Averaged electron temperature:,2MHz,With the increase of low frequency, the temperature of electrons increases,slightly,.,6MHz,12MHz,V,HF,=50V,V,LF,=100V,f,H,=60,MHz, p=100,mTorr, Averaged electron temperatur,E,z,in a LF period:,V,HF,= 50V,V,LF,= 100V,f,LF,= 2MHz,f,HF,= 60MHz,p,= 100mTorr,Ez in a LF period:VHF = 50V,E,r,in a LF period:,V,HF,= 50V,V,LF,= 100V,f,LF,= 2MHz,f,HF,= 60MHz,p,= 100mTorr,Er in a LF period:VHF = 50V,Fluid simulations for CF,4,plasmas,(1D),Basic model,CF,4,plasma is an,electronegative,discharge, i.e., there,are no negative ions in the discharge. The plasma is,composed of neutrals (atoms and molecules), electrons,positive ions, and,negative ions,.,Fluid simulations for CF4 plas,There are more than 30 reaction equations in the discharge.,There are more than 30 reactio,For simplification, we consider only four reaction processes, i.e.,Ionization: CF,4,+e, CF,3,+,+F+2e,Attachment:,CF,4,+e, CF,3,+F,-,Recombination: CF,3,+,+ e CF,3,Dissociation: CF,4,+e CF,3,+F + e,and four species of particles:,electrons, CF,4, CF,3,+, F,-,For simplification, we consid,Plasma Physics Model (,electrons and ions,):,K,i,ionization rate,K,a,attachment rate,K,rec,recombination rate,Plasma Physics Model (electron,f,L,= 2MHz,f,H,= 60MHz,V,L,= 2000V,V,H,= 1000V, D,dielectric,=0.5mm,Numerical results,Influence of the discharge pressure on charged particle densities,fL = 2MHz, fH = 60MHz, VL = 20,Influence of the HF voltage on charged particle densities,f,L,= 2MHz,f,H,= 60MHz,V,L,= 1000V, p=100 mTorr, D,dielectric,=0.5mm,Influence of the HF voltage on,五、直流偏压效应,Local electric field within micro trough,Positive charged accumulated on dielectric,Side etching,E,五、直流偏压效应 Local electric field,plasma,LF,DC,HF,抑制正电荷积累的方法,:,DF-CCP/DC,协同放电,plasma LFDCHF抑制正电荷积累的方法: DF-C,等离子体密度课件,1D PIC/MC simulations for Ar discharges,1D PIC/MC simulations for Ar d,等离子体密度课件,等离子体密度课件,等离子体密度课件,等离子体密度课件,Our recent publications about simulations of DF-CCP,1. Z. Q. Guan, Z. L. Dai and Y. N. Wang,“Simulations of dual rf-biased sheaths and ion energy distributions arriving at a dual rf-biased electrode ”, PHYSICS OF PLASMAS,12, 123502 (2005),2. Z. L. Dai, X. Xu and Y. N. Wang,“A self-consistent hybrid model of a dual frequency sheath: Ion energy and angular distributions , Phys. Plasmas,14, 013507(2007),3. W. Jiang, M. Mao and Y. N. Wang,“A time-dependent analytical sheath model for dual-frequency capacitively coupled plasma ”, Phys. Plasmas,13, 113502(2006),4. S. Wang, X. Xu and Y. N. Wang,“Numerical investigation of ion energy distribution and ion angle,distribution in a dual-frequency capacitively couple plasma with a hybrid model”,be published in Physics of Plasmas,Our recent publications about,Improving hybrid simulations, including, 1D simulations for CF,4,or CF,4,/Ar discharges, 2D simulations for CF,4,or CF,4,/Ar discharges,Interesting quantities:,Energy,distribution functions of different species ions ( such as Ar,+, CF,3,+,) at substrates;,Angle,distribution functions of different species ions ( such as Ar,+, CF,3,+,) at substrates;,Energy and angle distributions of radicals at substrates.,Radial variations,Next plan for our simulations,Interesting quantities:Radial,Self-consistent study for the standing-wave effects,in HF-CCP,2D fluid model,2D Maxwell equations,Self-consistent study for the,六、 有关实验研究工作进展,1,、大连理工大学,DF-CCP,放电装置及诊断系统的研制,完成人：,陆文琪、徐勇、朱爱民、 王友年等,目前已完成双频条件下的实验调试，正在进行实,验诊断系统的安装和调试,六、 有关实验研究工作进展 1、大连理工大学,质谱仪,探针,特点：,1,）高、低频电源可以接在同一电极或不同的 电极上；,2,）两个电极的距离可调：,15mm-30mm;3,）配有,Langmuir,探针、衰荡光谱、质谱诊,断系统,光谱仪,（,1,）双频电源（从日本购置）,（,2,）反应室（沈阳科学仪器厂）,（,3,）离子能量,-,质量分析器（英国,Hiden,公司）,（,4,）射频探针、衰荡光谱系统（自行研制）,质谱仪探针特点： 光谱仪 （1）双频电源（从日本购,DF-CCP,装置,DF-CCP装置,2,、苏州大学,DF-CCP,放电装置及诊断系统的研制,高频：,60MHz,低频：,2MHz,、,13.6MHz,完成人：,辛煜、宁兆元等,目前已开展双频条件下的实验诊断研究，如测量,双频条件下的等离子体密度、电子能量分布的测,量。,2、苏州大学,双频容性耦合等离子体装置,苏州大学,双频容性耦合等离子体装置苏州大学,HF: 50W,E (eV),高频,( 60 MHz ),放电情况下电子的能量分布,E (eV),Pressure: 2Pa,辛煜等（苏州大学）,实验结果显示：,EEDF,为三温、单温分布等,HF: 50W E (eV)高频 ( 60 MH,PIC/MC,模拟结果,模拟结果也显示：,EEDF,为单温分布,PIC/MC模拟结果模拟结果也显示：EEDF为单温分布,60MHz/13.56MHz,条件下的电子密度,60MHz/13.56MHz条件下的电子密度,下一步工作计划是：,1,）,系统研究双频条件下的,Ar,等离子体状态参数的量,主,要是观察双频的调制效应；,2,）,研究反应性气体或混合气体,(,如,Ar/CF,4,),的在双频条,件下的放电行为；,3,）,低频调制下离子入射到基片上的能量分布。,4,）,合作开展数值模拟与实验测试比较的研究工作,。,下一步工作计划是：,Thanks for your attention!,Thanks for your attention!,