Atomic force microscopy investigation of surface roughness generated between SiO₂ micro-pits in CHF₃/Ar plasma

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• 作者：Maryam Alsadat Rad^a ; ^{mar09_phy025@student.usm.my} ; ^{maryam.s.rad@gmail.com} ; Kamarulazizi Ibrahim^a ; Khairudin Mohamed^b
• 关键词：Surface roughness ; Reactive ion etching ; Fluorocarbon ; PMMA ; SiO2 ; Micro-pit
• 刊名：Superlattices and Microstructures
• 出版年：2012
• 期刊代码：122_07496036
• 类别：ms
• 出版时间：May, 2012
• 卷：51
• 期：5
• 页码：597-605
• 文件大小：1255 K

摘要

The present paper investigates the surface roughness generated by reactive ion etching (RIE) on the location between silicon dioxide (SiO₂) micro-pits structures. The micro-pit pattern on polymethyl methacrylate (PMMA) mask was created by an electron beam lithography tool. By using PMMA as a polymer resist mask layer for pattern transfer in RIE process, the carbon (C) content in etching process is increased, which leads to decrease of F/C ratio and causes domination of polymerization reactions. This leads to high surface roughness via self-organized nanostructure features generated on SiO₂ surface which was analyzed using atomic force microscopy (AFM) technique. The etching chemistry of CHF₃ plasma on PMMA masking layer and SiO₂ is analyzed to explain the polymerization. The surface root-mean-square (RMS) roughness below 1 nm was achieved by decreasing the RF power to 150 W and process pressure lower than 10 mTorr.