Fabrication of a hard mask for InP based photonic crystals:: Increasing the plasma-etch selectivity of poly(methyl methacrylate) versus SiO2 and SiNx
Fabrication of a hard mask for InP based photonic crystals:: Increasing the plasma-etch selectivity of poly(methyl methacrylate) versus SiO2 and SiNx
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DOI：
10.1116/1.2062567
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发表时间：
2005-11-01
影响因子：
1.4
通讯作者：
Jäckel, H
中科院分区：
文献类型：
--
作者：
Wüest, R;Strasser, P;Jäckel, H
我们介绍了SiO2和SiNx硬掩模的循环反应离子蚀刻工艺，其中氟基蚀刻步骤与N-2冲洗步骤交错，以提高对电子束抗蚀剂的选择性。对于SiO2蚀刻的蚀刻步骤持续时间为30秒，导致在SiO2和聚（甲基丙烯酸甲酯）（PMMA）之间的几乎4：1的选择性加倍，由于减少的热负荷。对于200 nm直径的孔，我们建立了从200 nm厚的PMMA抗蚀剂到600 nm厚的SiO2层的图案转移。对于SiNx蚀刻，我们证明了改善的侧壁垂直度，增强的蚀刻速率，并抑制再沉积的蚀刻副产物的循环过程。通过使用额外的30 nm钛中间层，我们显示出SiNx和PMMA之间几乎为5：1的优异的总体选择性。该工艺被应用于在初始PMMA层厚度为220 nm的InP基平板波导中制造具有3.5 μ m深孔的平面光子晶体器件。(c)2005年美国真空学会。
We introduce cyclic reactive ion etching processes for SiO2 and SiNx hard masks where the fluorine-based etch steps are interleaved with N-2 flushing steps in order to improve the selectivity to electron-beam resists. For SiO2 etching an etch-step duration of 30 s resulted in a doubled selectivity of almost 4:1 between SiO2 and poly(methyl methacrylate) (PMMA) due to a reduced thermal load. We established the pattern transfer from a 200 nm thick PMMA resist into a 600 nm thick SiO2 layer for 200 nm diameter holes. For SiNx etching we demonstrate improved sidewall verticality, an enhanced etch rate, and suppressed redeposition of etch byproducts for a cyclic process. With the use of an additional 30 nm titanium intermediate layer we show an excellent overall selectivity between SiNx and PMMA of almost 5: 1. This process is applied to the fabrication of planar photonic-crystal devices with 3.5 mu m deep holes in an InP based slab waveguide with an initial PMMA layer thickness of 220 nm. (c) 2005 American Vacuum Society.