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采用60 MHz/2 MHz双频率驱动的容性耦合放电等离子体技术,以C2F6/O2/Ar为刻蚀气体,开展了SiCOH低k介质中刻蚀低表面粗糙度沟道的研究。主要研究了O2/C2F6流量比对与SiCOH低k薄膜之间的刻蚀选择性的影响,以及O2/C2F6流量比、下电极功率对沟道刻蚀特性的影响。发现在O2/C2F6流量比为0.1以下时,光致抗蚀剂掩膜层与SiCOH低k薄膜之间具有较好的刻蚀选择性。对于沟道刻蚀,在O2/C2F6流量比为0.1时,下电极功率对沟道的表面粗糙度和剖面结构具有明显的影响。在下电极功率为30 W时,刻蚀的沟道底部平坦、沟道壁陡直,槽形完好,沟道底面的平均表面粗糙度降低至3.32 nm,因此,可以在SiCOH低k薄膜中刻蚀剖面结构完整的低表面粗糙度沟道。
A low-surface-roughness channel etched in SiCOH low-k is studied by capacitively coupled discharge plasma with 60 MHz / 2 MHz dual-frequency drive and C2F6 / O2 / Ar as etching gas. The effects of O2 / C2F6 flow ratio on etching selectivity with low-k SiCOH films and the influence of O2 / C2F6 flow ratio and lower electrode power on the channel etching properties were investigated. It is found that there is a good etching selectivity between the photoresist mask and the SiCOH low-k film when the O2 / C2F6 flow ratio is below 0.1. For channel etching, the bottom electrode power has a significant effect on the channel surface roughness and cross-sectional structure at a O2 / C2F6 flow ratio of 0.1. At a lower electrode power of 30 W, the bottom of the etched trench is flat with a straight trench wall with intact trenches and an average surface roughness on the bottom of the trench of 3.32 nm, allowing etching in SiCOH low-k films Profile structure of a complete low surface roughness channel.