3D Patterning of Si by Contact Etching With Nanoporous Metals
3D Patterning of Si by Contact Etching With Nanoporous Metals
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DOI：
10.3389/fchem.2019.00256
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发表时间：
2019-04-25
影响因子：
5.5
通讯作者：
Vilcot, Jean-Pierre
中科院分区：
文献类型：
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作者：
Bastide, Stephane;Torralba, Encarnacion;Vilcot, Jean-Pierre
纳米多孔金和铂电极被用来图案化n型硅接触蚀刻在宏观尺度。这种类型的电极具有如在经典金属辅助化学蚀刻中在硅、金属和电解质之间形成纳米接触的优点，同时确保电解质通过电极输送到界面和从界面输送。具有两种类型的纳米结构的纳米多孔金电极，精细和粗糙（平均韧带宽度分别为30和100 nm）已详细说明和测试。通过电化学和化学（HF-H 2 O 2）接触蚀刻压印由正方形金字塔（10 × 10 μ m（2）底× 7 μ m高）和U形线（2、5和10 μ m宽× 10 μ m高× 4 μ m间距）的网络组成的图案。一个完整的图案转移的金字塔实现与粗纳米多孔金在两种接触蚀刻模式，在类似于0.35 μ m/min（-1）的速率。在相同的蚀刻条件下，U形线只被部分压印。压印后的表面状态呈现出各种缺陷，如凹坑、孔隙或多孔硅。由于粗糙金纳米结构的细节的压印，有时获得小的壁。我们建立了np-Au电极可以变成“np-Pt”电极通过简单地溅射一个薄的铂层（5 nm）的蚀刻（催化）侧的电极。用np Au/Pt压印略微提高了图案转移分辨率。对Au/Si/电解质界面的价带调制进行了二维数值模拟，以解释n型硅与金和铂的接触刻蚀的局部化方面以及图案化后获得的不同表面状态。他们表明，与金或铂接触的n型硅处于反转状态，金属下方有空穴（3 nm以内）。在中等阳极极化下的蚀刻对应于在相邻金属和电解质接触之间的反型层中的几纳米上的准2D空穴转移，并且因此在金属接触周围非常局部化。
Nanoporous gold and platinum electrodes are used to pattern n-type silicon by contact etching at the macroscopic scale. This type of electrode has the advantage of forming nanocontacts between silicon, the metal and the electrolyte as in classical metal assisted chemical etching while ensuring electrolyte transport to and from the interface through the electrode. Nanoporous gold electrodes with two types of nanostructures, fine and coarse (average ligament widths of similar to 30 and 100 nm, respectively) have been elaborated and tested. Patterns consisting in networks of square-based pyramids (10 x 10 mu m(2) base x 7 mu m height) and U-shaped lines (2, 5, and 10 mu m width x 10 mu m height x 4 mu m interspacing) are imprinted by both electrochemical and chemical (HF-H2O2) contact etching. A complete pattern transfer of pyramids is achieved with coarse nanoporous gold in both contact etching modes, at a rate of similar to 0.35 mu m min(-1). Under the same etching conditions, U-shaped line were only partially imprinted. The surface state after imprinting presents various defects such as craters, pores or porous silicon. Small walls are sometimes obtained due to imprinting of the details of the coarse gold nanostructure. We establish that np-Au electrodes can be turned into "np-Pt" electrodes by simply sputtering a thin platinum layer (5 nm) on the etching (catalytic) side of the electrode. Imprinting with np Au/Pt slightly improves the pattern transfer resolution. 2D numerical simulations of the valence band modulation at the Au/Si/electrolyte interfaces are carried out to explain the localized aspect of contact etching of n-type silicon with gold and platinum and the different surface state obtained after patterning. They show that n-type silicon in contact with gold or platinum is in inversion regime, with holes under the metal (within 3 nm). Etching under moderate anodic polarization corresponds to a quasi 2D hole transfer over a few nanometers in the inversion layer between adjacent metal and electrolyte contacts and is therefore very localized around metal contacts.