等离子体刻蚀工艺的物理基础

介绍了等离子体刻蚀工艺背景以及有关等离子体刻蚀机理的研究进展,综述了等离子体刻蚀机理的研究方法,着重阐述了电容耦合放电和电感耦合放电等离子体物理特性,特别是双频电容耦合放电等离子体和等离子体鞘层研究中的关键问题.     

CHF3双频电容耦合放电等离子体特性研究

研究了用于SiCOH 低介电常数薄膜刻蚀的CHF₃气体在1356 MHz/2 MHz,2712 MHz/2 MHz和60 MHz/2 MHz双频电容耦合放电时的等离子体性质.发现2 MHz低频源功率的增大主要导致F基团密度的增大;而高频频率从1356,2712增大到60 MHz,导致CF₂基团的密度增大和电极之间F基团密度的轴向空间不均匀性增加.根据电子温度的分布规律及离子能量随高频源频率的变化关系,提出CF₂基团的产生主要通过电子-中性气体碰撞,而F基团的产生是离子-中性气体碰撞的结果. 关键词： 双频电容耦合放电 3等离子体')" href="#">CHF₃等离子体     

双频容性耦合等离子体相分辨发射光谱诊断

采用相分辨发射光谱法, 对双频容性耦合纯Ar和不同含O₂量的Ar-O₂混合气体放电等离子体的鞘层激发模式进行了探究. 在射频耦合电源上极板的鞘层区域处观察到两种电子激发模式: 鞘层扩张引起的电子碰撞激发模式和二次电子引起的电子碰撞激发模式; 并发现这两种激发模式均受到低频射频电源周期的调制. 在纯Ar放电等离子体中, 两种激发模式的激发轮廓相似; 而在Ar-O₂混合气放电等离子体中, 随着含O₂量的增加, 二次电子的激发轮廓变弱. 此外, 利用相分辨发射光谱法对不同含O₂量的Ar-O₂混合气放电下Ar的 750.4 nm谱线的平均低频电源周期轴向分布进行了研究, 得到了距耦合电源上极板约3.8 mm处为双频容性耦合射频等离子体的鞘层边界. 关键词： 双频容性耦合等离子体 等离子体鞘层 发射光谱     

离子刻蚀用的大面积射频离子束源

离子束技术已广泛应用于电子、材料、光学、医学和生物等多种领域，并取得了可观的技术效果与经济效益，尤其是在光学领域中采用此项技术可制造大刻划面积的全息离子刻蚀光栅，对提高高精度光谱分析仪器的性能具有十分重要的意义。随着技术的发展，对离子束源也提出了更高的要求，诸如：离子束流要求大，要有良好的均匀性，且要有好的离子束的光学品质等。本文介绍的离子束源是由电感耦合等离子体源及其引出系统构成。下面主要介绍电感耦合等离子体源及其引出系统，以及大面积均匀性离子束源的应用前景及其需要解决的关键问题。     

未来制造业和加工业中的等离子体

从两组元或三线元等离子体的一些基本性质出发，分析了等离子体在超大规模集成电路生产，扁平显示器技术，光导纤维生产和未来光计算机芯片制造，废物处理，新材料制备等中十分诱人的应用前景。     

微波等离子体离子束刻蚀技术

自行设计研制了一台微波电子回旋共振等离子体刻蚀系统。该系统采用微波直接通过石英窗口产生右旋圆极化波，由Nd—Fe—B永磁磁钢形成高强磁场，通过共振磁场区域内的电子回旋共振效应产生均匀的高密度等离子体。利用该系统，结合光刻技术和反应离子束刻蚀技术，在以碳氢（CH）等元素为主要组成的有机聚合物（PMMA）表面制备出线宽3-4μm的光栅形图形。原子力显微镜（AFM）测试结果表明，所得图形线条清晰，侧边比较陡直。     

光刻与等离子体刻蚀技术

介绍了光刻与等离子体刻蚀技术的特点与进展,阐述了等离子体刻蚀的物理机制与前沿问题。     

等离子体刻蚀工艺中的光学发射光谱仪数据的模型研究

原位光学发射光谱仪（OES）已经成为等离子体刻蚀工艺控制过程中的一种非常有潜力的在线传感器系统。采用光谱仪实时采集高密度等离子体刻蚀机中的OES光谱数据，利用BP神经网络算法对特定波长的OES数据进行分析及建模，以便对等离子体刻蚀工艺过程进行反馈控制。由刻蚀产物SiCl发出的405nm谱线被选为特征谱线来确定刻蚀工艺过程的终点。     

CHF3双频电容耦合放电等离子体特性研究

研究了用于SiCOH 低介电常数薄膜刻蚀的CHF₃气体在1356 MHz/2 MHz,2712 MHz/2 MHz和60 MHz/2 MHz双频电容耦合放电时的等离子体性质.发现2 MHz低频源功率的增大主要导致F基团密度的增大;而高频频率从1356,2712增大到60 MHz,导致CF₂基团的密度增大和电极之间F基团密度的轴向空间不均匀性增加.根据电子温度的分布规律及离子能量随高频源频率的变化关系,提出CF₂基团的产生主要通过电子-中性气体碰撞,而F基团的产生是离子-中性气体碰撞的结果.     

射频电感性耦合等离子体调谐基片自偏压特性

采用调节射频电感性耦合等离子体中基片电极与地之间的外部电路阻抗的方法,控制基片电极的射频自偏压。研究了调谐基片自偏压随外部调谐电容值的变化特征,得到了调谐基片射频自偏压随射频放电功率、气压的变化曲线。在一定放电参数区域内,调谐基片射频自偏压随调谐电容的变化曲线呈现跳变、双稳、迟滞现象。     

氧等离子体刻蚀CVD金刚石膜的影响机理

采用电子回旋共振（ECR）等离子体在不同的磁场位形和工作气压下刻蚀化学气相沉积（CVD）金刚石膜,运用双探针和离子灵敏探针法对等离子体进行了诊断,研究了等离子体参数对刻蚀效果的影响。结果表明：磁场由发散场向收敛场转变时,离子温度、电子温度和等离子体密度都随之增大,刻蚀效果逐渐增强;当工作气压由低气压向高气压变化时,等离子体参数先增大后减小,CVD金刚石膜表面粗糙度降低程度也出现了相同的趋势。     

氧等离子体刻蚀CVD金刚石膜的影响机理

采用电子回旋共振(ECR)等离子体在不同的磁场位形和工作气压下刻蚀化学气相沉积(CVD)金刚石膜,运用双探针和离子灵敏探针法对等离子体进行了诊断,研究了等离子体参数对刻蚀效果的影响。结果表明:磁场由发散场向收敛场转变时,离子温度、电子温度和等离子体密度都随之增大,刻蚀效果逐渐增强;当工作气压由低气压向高气压变化时,等离子体参数先增大后减小,CVD金刚石膜表面粗糙度降低程度也出现了相同的趋势。     

Characteristics of a dual‐radio‐frequency cylindrical inductively coupled plasma

The plasma parameters such as electron density, effective electron temperature, plasma potential, and uniformity are investigated in a new dual‐frequency cylindrical inductively coupled plasma (ICP) source operating at two frequencies (2 and 13.56 MHz) and two antennas (a two‐turn high‐frequency antenna and a six‐turn low‐frequency (LF) antenna). It is found that the electron density increases with 2 MHz power, whereas the electron temperature and plasma potential decrease with 2 MHz power at a fixed 13.56 MHz power. Moreover, the plasma uniformity can be improved by adjusting the LF power. These results indicate that a dual‐frequency synergistic discharge in a cylindrical ICP can produce a high‐density, low‐potential, low‐effective‐electron‐temperature, and uniform plasma.     

Nanometer-scale etching of CoFeB thin films using pulse-modulated high density plasma

Pulse-modulated inductively coupled plasma reactive ion etching of nanometer-scale patterned CoFeB thin films was performed in CH₄/O₂/Ar gas mixture. As the pulse on-off duty ratio decreased, the etch selectivity of CoFeB/TiN slightly increased and the etch profiles were improved. Moreover, the etch selectivity of the CoFeB films and the etch profiles were improved with the increase in the pulse frequency of the plasma. X-ray photoelectron spectroscopy revealed that during the pulse-modulated etching in the CH₄/O₂/Ar gas mixture, some polymeric layers were formed on the CoFeB films, which helped prevent the lateral etching and increased the etch selectivity. Consequently, nanometer-scale etching of CoFeB thin films patterned with TiN hard masks could be achieved using pulsed-modulated plasma in CH₄/O₂/Ar gas mixture.     

非对称磁镜场电子回旋共振氧等离子体刻蚀化学气相沉积金刚石膜

分别应用郎缪尔双探针和离子灵敏探针对非对称磁镜场电子回旋共振氧等离子体的电子参数、空间分布和离子参数进行了测量,分析了气压对等离子体参数及空间分布的影响。利用该等离子体在优化的气压条件下对化学气相沉积金刚石膜进行了刻蚀,并研究了刻蚀机理。结果表明:电子温度为5~10 eV,离子温度为1 eV左右,而等离子体数密度在1010cm-3数量级。随气压的升高,电子和离子温度降低,而电子数密度先增大后减小。在低气压下等离子体数密度空间分布更均匀,优化的刻蚀气压为0.1 Pa。刻蚀过程中,离子的回旋运动特性得到了加强,有利于平行于金刚石膜表面的刻蚀,有效地保护了金刚石膜的晶界和缺陷。     

Characteristics of SiO2 etching by using pulse-time modulation in 60 MHz/2 MHz dual-frequency capacitive coupled plasma

60 MHz pulsed radio frequency (rf) source power and 2 MHz continuous wave rf bias power, were used for SiO₂ etching masked with an amorphous carbon layer (ACL) in an Ar/C₄F₈/O₂ gas mixture, and the effects of the frequency and duty ratio of the 60 MHz pulse rf power on the SiO₂ etch characteristics were investigated. With decreasing duty ratio of the 60 MHz pulse rf power, not only the etch rate of SiO₂ but also the etch rate of ACL was decreased, however, the etch selectivity of SiO₂ over ACL was improved with decreasing the duty ratio. On the other hand, when the pulse frequency was varied at a constant duty ratio, no significant change in the etch rate and etch selectivity of both materials could be observed. The variation of the etch characteristics was believed to be related to the change in the gas dissociation characteristics caused by the change in the average electron temperature for different pulsing conditions. The improvement in the etch selectivity with the decrease of duty ratio, therefore, was related to the decreased gas dissociation of C₄F₈ by the decrease of average electron temperature and, which resulted in a change in composition of the fluorocarbon polymer on the etched materials surface from C–C rich to CF₂ rich. With decreasing the duty ratio, not only the etch selectivity but also the improvement in the SiO₂ etch profile could be observed.     

蒙特卡罗模拟在辉光放电鞘层离子输运研究中的应用

利用蒙特卡罗方法模拟氩气直流辉光放电鞘层内离子的运动过程.模拟基于离子与中性原子的电荷转移和弹性散射两种主要的散射过程，考虑了碰撞截面与能量相关和不相关两种情况，在弹性散射中采用了势场相互作用模型和刚性球碰撞两种模型.通过模拟得到不同气压和不同放电电压下离子入射阴极的能量分布和角度分布，并对几种模型的模拟结果进行了比较和讨论. 关键词： 辉光放电 等离子体鞘层 蒙特卡罗模拟     

气体放电等离子体特性测量I-V曲线不对称性的研究

利用气体放电双探针法研究了等离子体的I-V曲线中的电流I相对于电压V轴交点的不对称性,并提出2种可能的解释:一认为是由于两探针表面积不同引起的;二认为是由于探针所在处等离子体电位不等引起的.本文利用仪器的工艺误差和调换放电管电压的方法,对提出的2种可能原因分别进行验证,并指出第二种解释的合理性,并对其进行了理论分析.     

Optimization of inductively coupled plasma deep etching of GaN and etching damage analysis

Inductively coupled plasma (ICP) etching of GaN with an etching depth up to 4 μm is systemically studied by varying ICP power, RF power and chamber pressure, respectively, which results in etch rates ranging from ∼370 nm/min to 900 nm/min. The surface morphology and damages of the etched surface are characterized by optical microscope, scanning electron microscope, atomic force microscopy, cathodoluminescence mapping and photoluminescence (PL) spectroscopy. Sub-micrometer-scale hexagonal pits and pillars originating from part of the structural defects within the original GaN layer are observed on the etched surface. The density of these surface features varies with etching conditions. Considerable reduction of PL band-edge emission from the etched GaN surface indicates that high-density non-radiative recombination centers are created by ICP etching. The density of these non-radiative recombination centers is found largely dependent on the degree of physical bombardments, which is a strong function of the RF power applied. Finally, a low-surface-damage etch recipe with high ICP power, low RF power, high chamber pressure is suggested.