Silicon nitride etch characteristics in SF6/O2 and C3F6O/O2 plasmas and evaluation of their global warming effects

Abstract Effects of process parameters on the etch rate and generation of etch by-product molecules during Si3N4 layer etching in SF6/O2 and C3F6O/O2 plasmas were investigated in a dual-frequency capacitively coupled plasma etcher in order to evaluate the etch characteristics and global warming effects of emitted gases. The effects of the working pressure and gas flow ratio on the Si3N4 etch rate were initially examined for each gas mixture. The Si3N4 etch rates was compared for the SF6/O2 and C3F6O/O2 etch gas mixtures under the same process conditions. The by-product gases generated during etching were analyzed and their concentrations were quantized by Fourier transform infrared spectroscopy. The global warming effects caused by the by-product gases emitted using the SF6 and C3F6O gas mixtures were evaluated by comparing the million metric tons of carbon equivalent (MMTCE) values obtained from the emitted amounts of the by-product gases during the etching of a 1 μm-thick Si3N4 layer. The results showed that the C3F6O/O2 chemistry was superior to the SF6/O2 chemistry in lowering the global warming effects. C3F6O gas could be used as an alternative to replace SF6 gas for future etching processes of flat panel display materials.

[1]  Global warming gas emission during plasma cleaning process of silicon nitride using c-C4F8O/O2 chemistry with additive Ar and N2 , 2004 .

[2]  N. Lee,et al.  Effect of additive gases and injection methods on chemical dry etching of silicon nitride, silicon oxynitride, and silicon oxide layers in F2 remote plasmas , 2007 .

[3]  C. H. Lee,et al.  Effect of high-frequency variation on the etch characteristics of ArF photoresist and silicon nitride layers in dual frequency superimposed capacitively coupled plasma , 2005 .

[4]  N. Lee,et al.  ArF Photoresist Deformation in Dual Frequency Superimposed Capacitively Coupled Plasma (DFS-CCP) with Different Frequency Combinations , 2005 .

[5]  Nae-Eung Lee,et al.  Role of N2 during chemical dry etching of silicon oxide layers using NF3/N2/Ar remote plasmas , 2007 .

[6]  Effects of N2 addition on chemical dry etching of silicon oxide layers in F2∕N2∕Ar remote plasmas , 2006 .

[7]  Tso-Ping Ma,et al.  Electrical properties of high-quality ultrathin nitride/oxide stack dielectrics , 1999 .

[8]  N. Lee,et al.  Ultrahigh Selective Etching of SiO2 Using an Amorphous Carbon Mask in Dual-Frequency Capacitively Coupled C4F8 / CH2F2 / O2/Ar Plasmas , 2010 .

[9]  B. D. Pant,et al.  Etching of Silicon Nitride in CCl2F2, CHF3, SiF4, and SF6 Reactive Plasma: A Comparative Study , 1999 .

[10]  N. Lee,et al.  Infinite Etch Selectivity during Etching of SiON with an Extreme Ultraviolet Resist Pattern in Dual-Frequency Capacitively Coupled Plasmas , 2010 .

[11]  N. Lee,et al.  Highly selective etching of silicon nitride to physical-vapor-deposited a-C mask in dual-frequency capacitively coupled CH2F2∕H2 plasmas , 2010 .

[12]  Characteristics of RIE SF6/O2/Ar Plasmas on n-Silicon Etching , 2006, 2006 IEEE International Conference on Semiconductor Electronics.