Development and Plasma Characteristics Measurement of Planar-Type Magnetic Neutral Loop Discharge Etcher
Development and Plasma Characteristics Measurement of Planar-Type Magnetic Neutral Loop Discharge Etcher
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平面型磁中性环放电刻蚀机的研制及等离子体特性测量
DOI：
10.1143/jjap.37.4572
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发表时间：
1998
影响因子：
1.5
通讯作者：
Yasuhiro Horiike Yasuhiro Horiike
中科院分区：
文献类型：
--
作者：
Y. Shindo;Ryohei Itatani Ryohei Itatani;Takanori Ichiki Takanori Ichiki;Yasuhiro Horiike Yasuhiro Horiike
一种低压高密度等离子体源，称为平面型磁中性环放电（NLD），已被开发用于单晶片刻蚀工艺，采用一对永磁环和单匝RF天线的石英板。首先，平面型NLD的等离子体特性进行了比较与平面型电感耦合等离子体（ICP）使用的原型蚀刻机与一个大的磁中性环（MNL）的直径为230毫米。在Ar等离子体中的探针测量的结果表明，平面型NLD可以在0.1-10 mTorr的低压力下维持，具有比平面型ICP更高的等离子体密度和更低的电子能量。通过电子能量分布函数（EEDF）和发射光谱的直接测量，揭示了NLD中高能电子的耗尽现象。接着，为了产生均匀且大直径的NLD，研究了磁场强度和天线与晶片台之间的差距对等离子体均匀性的影响。通过降低抑制等离子体扩散的磁场强度，在下游Ar等离子体中在240 mm直径上获得了±2.5%的离子电流均匀性和13 mA/cm 2的高离子电流密度。对于C4 F8 +90%Ar等离子体，由于相对较低的电子能量，获得了用于高选择性SiO2/Si刻蚀的离子和中性物种的较好气相化学，并且在240 mm的直径上也获得了±2%的均匀性。
A low-pressure and high-density plasma source, called a planar-type magnetic neutral loop discharge (NLD), has been developed for a single-wafer etching process, employing a pair of permanent magnet rings and a single-turn RF antenna on the quartz plate. First, the plasma characteristics of planar-type NLD were compared with those of a planar-type inductively coupled plasma (ICP) using the prototype etcher with a large magnetic neutral loop (MNL) of 230 mm diameter. The results of probe measurements in Ar plasmas have revealed that a planar-type NLD can be sustained at low pressures of 0.1–10 mTorr with higher plasma density and lower electron energy than a planar-type ICP. The depletion of high-energy electrons in NLD was revealed by the direct measurement of electron energy distribution function (EEDF) and optical emission spectroscopy. Next, for the purpose of uniform and large-diameter NLD generation, effects of magnetic field strength and the gap between an antenna and a wafer stage on the plasma uniformity have been investigated. By reducing the magnetic field strength that suppresses plasma diffusion, an ion current uniformity within ±2.5% and a high ion current density of 13 mA/cm2 was obtained over a 240 mm diameter in the downstream Ar plasma. As for C4F8+90%Ar plasmas, preferable gas phase chemistry of ion and neutral species for highly selective SiO2/Si etching was attained due to relatively low electron energy, and a uniformity within ±2% was also achieved over a diameter of 240 mm.