Enhancing the Etch Rate at Backside Etching of Fused Silica
Enhancing the Etch Rate at Backside Etching of Fused Silica
复制标题
提高熔融石英背面蚀刻的蚀刻速率
DOI：
10.2961/jlmn.2006.03.0027
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发表时间：
2006
影响因子：
1.1
通讯作者：
B. Rauschenbach
中科院分区：
文献类型：
--
作者：
K. Zimmer;R. Böhme;B. Rauschenbach
激光诱导背面湿法蚀刻（LIBWE）技术允许直接蚀刻透明材料，如熔融石英与纳秒紫外激光在低激光能量密度。烃类液体经常用于LIBWE，但只有中等的吸收系数，蚀刻过程受到孵化的影响。从一个简单的模型的界面温度的估计表明，高的吸收系数提高了激光能量的利用率，并可能导致更高的温度超过熔点。因此，研究了利用纳秒紫外激光辐射（λ = 248 nm，25 ns脉冲，10 Hz）通过液体镓对熔融石英的背面蚀刻。估计阈值通量约为1.5 J/cm²，测量的蚀刻速率接近1 µm/脉冲。正方形的蚀坑具有轮廓分明的边缘和光滑的底部。由于边界处的热损失，在较小的斑点尺寸处蚀刻速率降低。蚀刻工艺涉及界面附近的镓的激光加热、近表面区域中的熔融石英的熔融以及通过激光蚀刻中涉及的热机械工艺对熔融层的蚀刻。
The laser-induced backside wet etching (LIBWE) technique allows straightforward etching of transparent materials such as fused silica with nanosecond UV lasers at low laser fluences. Hydrocarbon liquids are regularly exploited for LIBWE but have only moderate absorption coefficients and the etching process is affected from incubation. The estimation of the interface temperature from a simple model shows that high absorption coefficients improve the utilization of the laser energy and can result in higher temperatures exceeding the melting point. Therefore the backside etching of fused silica by means of liquid gallium using nanosecond UV laser radiation (λ = 248 nm, 25 ns pulses, 10 Hz) is investigated. A threshold fluence of about 1.5 J/cm² was estimated and etch rates close to 1 µm/pulse were measured. The square etch pits feature welldefined edges and a smooth bottom. The etch rate decreases at smaller spot size due to the thermal losses at the boundaries. The etch process involves the laser heating of gallium near the interface, the melting of the fused silica in a near surface region, and the etching of the molten layer by thermo-mechanical processes involved in laser etching.