微小等离子体反应器的制作及性能测试

Machining and functional testing of microplasma reactors

设计了基于并行探针驱动的扫描刻蚀加工系统,用于微纳米尺度的刻蚀加工。研究了系统的核心器件-微小等离子体反应器的电学特性和发射光谱特性,以了解反应器中产生的反应等离子体性能的变化规律。基于微机电系统(MEMS)加工工艺制备了中间带有倒金字塔形状微型空腔的金属-绝缘体-金属3层结构的微小等离子体反应器。搭建了可测量等离子体伏安特性和发射光谱特性的实验系统,对放电气体为SF6,工作气压在5～12kPa,直流驱动模式下的微小等离子体反应器的电学和光谱特性进行了测试。实验结果表明,放电电流随着放电电压的增加而近似线性递增,放电电流由5kPa时的2.1～2.82μA递增到12kPa时的3.6～4.2μA,表明所产生的微小等离子体处于异常辉光放电模态。当器件特征尺寸由150μm减小至30μm时,微小等离子体发射光谱中氟原子特征谱线(703.7nm)峰值增大了约56%,表明微小等离子体的浓度随尺度缩小而增强。实验结果表明,设计的微小等离子体反应器基本满足扫描刻蚀加工所需的高浓度等离子体源的性能要求。

A scanning plasma etching system based on parallel probe actuation was developed to realize micro-and nano-scale etching.The electrical and optical emission spectra of a micro plasma reactor which was a key device in the system were measured to explore the characteristics of the plasma in the reactor.First,a metal-dielectric-metal structure microplasma reactor with an inverted pyramidal hollow cathode was fabricated based on Micro-electric-mechanic System（MEMS） technology.Then,a testing system was set up to measure the V-I curve and optical emission spectra of the microplasma generated at a SF_6 gas pressure of 5-12 kPa and drived by a DC mode.Experimental result shows that the discharge current is increased in linearity with the discharge voltage.When the gas pressure increases from 5 kPa to 12 kPa,the discharge current is increased from 2.1~2.82 μA to 3.6~4.2 μA,which means that the microplasma is at an abnormal discharge mode.When the feature size of the reactor decreases from 150 μm to 30 μm,the characteristic line of fluorine（703.7 nm） is increased about 56%,which demonstrates that the plasma density is increased with reducing device sizes.The measurement result of electrical and optical emission spectra of microplasma indicates that the microplasam reactor is suitable for the scanning plasma etching of silicon.