复合脉冲磁控溅射放电特性及数值仿真研究

发布时间：2018-03-07 14:57

本文选题：磁控溅射　切入点：复合脉冲　出处：《哈尔滨工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：高功率磁控溅射技术是一种优质的镀膜方法,具有离化率高、瞬时功率大以及膜层性能良好等优点,受到科研及工业领域的广泛关注。然而由于高功率磁控溅射平均功率小,膜层沉积速率低,在工业应用中受到了限制。针对高功率磁控溅射沉积速率低的问题,本文提出了一种复合脉冲磁控溅射新方法,该方法采取两路脉冲耦合的方式,使用电压高脉宽小的引燃脉冲离化气体,电压低脉宽长的工作脉冲维持等离子体放电,从而在获得高密度等离子体的同时,维持较高的平均功率。使用Particle-in-Cell/Monte Carlo模型对复合脉冲放电过程进行数值仿真,研究放电过程等离子体动力学及放电波形形成机制。结果表明,等离子体分布受到空间电磁场的共同作用,空间等离子体的不均匀分布又会对空间电场造成影响。在磁控溅射放电过程中,空间电势逐渐升高,出现电势梯度较大的阴极鞘层区域和等离子体浓度较大的离化区域。靶材电压越高,离化气体能力越强,产生等离子体数目越多,离子能量越高,靶材电流也越大。对于复合脉冲,空间电势与等离子体浓度分布于单脉冲相似,引燃脉冲关断后一段时间内工作脉冲能够有效维持较高的等离子体浓度和电流密度,而空间离子能量则会随着电压的降低而降低。使用FPGA作为核心控制器,触摸屏作为人机交互,研制了复合脉冲电源。两路脉冲电压、脉宽和频率可独立调节,相对相位关系可灵活设定,并具备过流保护降电压的功能,保护电源在真空室安全工作,具有参数设定灵活、操作界面友好的特点。使用水负载对电源功能进行测试,设定不同脉冲参数,采集电压电流波形,验证电源不同波形的实现,并获得电源电压电流输出特性。结果表明水负载中,电流和电压成正比例对应关系。对复合脉冲电源在真空室使用Cr靶进行放电测试,与水负载中电流电压线性相关不同,由于真空室内等离子体负载非线性的特征,电流波形较为复杂。当电压为方波时,电流波形接近三角形或扇形。对于复合脉冲,在引燃脉冲阶段电流迅速上升,峰值电流与电压和脉宽相关,引燃脉冲关断后电流下降,下降速率与工作脉冲电压相关。结果表明,使用复合脉冲模式,在引燃脉冲阶段能够获得较高峰值电流,在工作脉冲阶段维持放电电流,与单脉冲相比平均电流明显提高。
[Abstract]:High power magnetron sputtering is a kind of high quality coating method, which has many advantages such as high ionization rate, high instantaneous power and good coating performance, and has attracted wide attention in scientific research and industry. However, the average power of high power magnetron sputtering is small. The deposition rate of film is low, which is limited in industrial application. In order to solve the problem of low deposition rate of high power magnetron sputtering, a new method of composite pulse magnetron sputtering is proposed in this paper, in which two pulses are coupled. The plasma discharge is maintained by using the ionization gas with high voltage and small pulse width, and the working pulse with low voltage and low pulse width, so that the high density plasma can be obtained at the same time. To maintain high average power, the Particle-in-Cell/Monte Carlo model is used to simulate the discharge process of composite pulse, and the plasma dynamics and the formation mechanism of discharge waveform are studied. The results show that, The plasma distribution is affected by the space electromagnetic field, and the non-uniform distribution of the space plasma will affect the space electric field. During the discharge of magnetron sputtering, the space potential increases gradually. The higher the voltage of the target, the stronger the ability of ionizing gas, the more the number of plasma, the higher the ion energy. The larger the target current is, for the composite pulse, the spatial potential is similar to the plasma concentration, and the working pulse can maintain the high plasma concentration and current density effectively within a period of time after the ignition pulse is off. Using FPGA as core controller and touch screen as man-machine interaction, a compound pulse power supply is developed. Two pulse voltages, pulse width and frequency can be adjusted independently. The relative phase relation can be set flexibly and has the function of overcurrent protection and voltage drop. The protection power supply works safely in the vacuum chamber. It has the characteristics of flexible parameter setting and friendly operation interface. The function of power supply is tested by water load. Setting different pulse parameters, collecting voltage and current waveforms, verifying the realization of different waveforms of power supply, and obtaining the output characteristics of power supply voltage and current. The discharge test of composite pulse power supply using Cr target in vacuum chamber is different from the linear correlation between current and voltage in water load. Because of the nonlinear characteristics of plasma load in vacuum chamber, the current and voltage are proportional to each other. The current waveform is complex. When the voltage is square wave, the current waveform is close to triangle or sector. For the compound pulse, the current increases rapidly in the ignition pulse, the peak current is related to the voltage and pulse width, and the current decreases after the ignition pulse is off. The results show that the peak current can be obtained in the ignition pulse phase and the discharge current is maintained at the working pulse stage, and the average current is significantly higher than that of the single pulse.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB306

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