Backside Etching at the Interface to Diluted Medium with Nanometer Etch Rates
Backside Etching at the Interface to Diluted Medium with Nanometer Etch Rates
复制标题
以纳米蚀刻速率在稀释介质界面进行背面蚀刻
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
B. Rauschenbach
中科院分区：
文献类型：
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作者：
R. Böhme;K. Zimmer;D. Ruthe;B. Rauschenbach
利用表面吸附层(LESAL)进行激光刻蚀是一种新的、有前途的透明材料刻蚀方法，如熔融二氧化硅。蚀刻过程基于激光照射透明固体和形成吸附层的稀释(蒸发)背面介质之间的界面。利用脉冲宽度为25 ns的KrF准分子激光器(λ=2 48 nm)研究了熔融二氧化硅的激光致发光谱。以甲苯为吸附物的LESAL具有突出的特性，例如，低阈值通量(<；1J/cm2)，在宽通量区域内几乎恒定的刻蚀速率约为1 nm/脉冲，以及非常低的、接近光学级的表面粗糙度(~1 nm RMS)。作为LESAL的机理，讨论了改性表面层的热烧蚀。这种修饰主要是由有机分子光解的分解产物沉积引起的。使用卤化吸附的氟苯(C6H5F)、二氟苯(C6H4F2)、氯苯(C6H5Cl)和二氯苯(C6H4Cl2)作为稀释背面介质，显著降低了刻蚀阈值，并产生了额外的特征注量区，具有Angstrom/Pulse刻蚀速率和均匀而光滑的表面形貌。由于溶剂的分解而在加热表面附近产生的卤素自由基似乎是熔融二氧化硅表面化学侵蚀的最可能的机制。
The laser etching using a surface adsorbed layer (LESAL) is a new and promising method for precise etching of transparent materials such as fused silica. The etching process is based on the laser irradiation of the interface between a transparent solid and a diluted (vaporized) backside medium that forms an adsorbed layer. A KrF excimer laser (λ = 248 nm) with pulse duration of 25 ns is employed to study LESAL of fused silica. LESAL by means of toluene as adsorbate features outstanding attributes, e.g., low threshold fluences (< 1 J/cm²), an almost constant etch rate on the order of 1 nm/pulse over a wide fluence region, and very low, nearly optical grade surface roughness (~ 1 nm rms). As LESAL mechanism, the thermal ablation of a modified surface layer is discussed. The modification is caused chiefly by the deposition of decomposition products from organic molecules photolysis. The usage of halogenated adsorbate fluorobenzene (C6H5F), difluorobenzene (C6H4F2), chlorobenzene (C6H5Cl), and dichlorobenzene (C6H4Cl2) as diluted backside media reduces significantly the etching threshold and causes an additional characteristic fluence region with Angstrom/pulse etch rate and homogenous and smooth surface topography. The generation of halogen radicals close to the heated surface due to the decomposition of the solvent seems to be the most probably mechanism for a chemical erosion of the fused silica surface.