In situ measurement of plasma charging on SiO2 hole bottoms and reduction by negative charge injection during etching
In situ measurement of plasma charging on SiO2 hole bottoms and reduction by negative charge injection during etching
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DOI：
10.1016/j.apsusc.2007.10.070
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发表时间：
2008-04
影响因子：
6.7
通讯作者：
T. Ohmori;T. Makabe
中科院分区：
文献类型：
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作者：
T. Ohmori;T. Makabe
微纳电子器件制造中的充电损伤是等离子体蚀刻期间的电损伤之一，并且基本上由正离子和电子之间朝向待处理晶片的通量速度分布的巨大差异引起。在蚀刻期间，束状正离子累积在小型化结构的底部上。随着工艺节点的演进，由于等离子体暴露时间的增加、退火温度的降低和工艺窗口的变窄等因素，充电损伤将增加，这是由于金属层数量的增加和引入新材料如低k和高k代替SiO2而引起的。自上而下的纳米技术的发展依赖于等离子体对低能级元素损伤的原位诊断技术的发展和无电荷等离子体工艺的发展。本文首次演示了使用测试芯片进行原位充电测量以及通过光学计算机断层扫描向晶片注入负电荷的方法。其次，讨论了双频电容耦合等离子体（2f-CCP）刻蚀SiO2孔底时的充电电位特性，并参考了在靠近硅片的人工双层结构下，利用负电荷加速到孔底来降低正电位的过程。此外，还讨论了充电对孔的长径比和天线比的影响。
Charging damage in the fabrication of a micro- and nanoelectronic device is one of the electrical damages during plasma etching and caused basically by a huge difference of the flux velocity distribution between positive ions and electrons toward the wafer to be processed. Beam-like positive ions are accumulated on the bottom of a miniaturized structure during etching. With the evolution of the technology node, charging damage will increase due to several factors, increase of plasma exposure time, decrease of annealing temperature, and narrow process window, etc., caused by the increase of the number of metal layers and the introduction of new materials such as low-k and high-k instead of SiO2. The progress of a top-down nanotechnology depends on the development of in situ diagnostics regarding plasma damage to lower-level elements and on the development of charging-free plasma process. In this paper, in situ charging measurements by using a test chip and negative charge injection to the wafer by optical computerized tomography are first demonstrated. Second, we discuss the characteristics of the charging potential on the bottom of SiO2holes during etching in a two-frequency capacitively coupled plasma (2f-CCP), and refer to the procedure to reduce the positive potential by utilizing the negative charge acceleration to the hole bottom under the artificial formation of a double-layer close to the wafer. In addition, the charging’s effect on the aspect ratio of the hole and the antenna ratio are discussed.