Laboratorio de Microscopías Avanzadas (LMA)-Instituto de Nanociencia de Aragón (INA), Universidad de Zaragoza, E-50018 Zaragoza, Spain.
Nanotechnology. 2019 Dec 13;30(50):505302. doi: 10.1088/1361-6528/ab423c. Epub 2019 Sep 6.
Focused electron beam induced deposition (FEBID) is a leading nanolithography technique in terms of resolution and the capability for three-dimensional (3D) growth of functional nanostructures. However, FEBID still presents some limitations with respect to the precise control of the dimensions of the grown nano-objects as well as its use on insulating substrates. In the present work, we overcome both limitations by employing electrically-biased metal structures patterned on the surface of insulating substrates. Such patterned metal structures serve for charge dissipation and also allow the application of spatially-dependent electric fields. We demonstrate that such electric fields can dramatically change the dimensions of the growing 3D nanostructures by acting on the primary electron beam and the generated secondary electrons. In the performed experiments, the diameter of Pt-C and W-C vertical nanowires grown on quartz, MgO and amorphous SiO is tuned by application of moderate voltages (up to 200 V) on the patterned metal microstructures during growth, achieving diameters as small as 50 nm. We identify two competing effects arising from the generated electric fields: a slight change in the primary beam focus point and a strong action on the secondary electrons. Beam defocus is exploited to achieve the in situ modulation of the diameter of 3D FEBID structures during growth.
聚焦电子束诱导沉积（FEBID）是一种领先的纳米光刻技术，在分辨率和功能性纳米结构的三维（3D）生长能力方面具有优势。然而，FEBID 在精确控制生长纳米物体的尺寸以及在绝缘衬底上的应用方面仍存在一些局限性。在本工作中，我们通过在绝缘衬底表面上采用偏置金属结构克服了这两个局限性。这种图案化的金属结构用于电荷耗散，并且还允许施加空间相关的电场。我们证明，这种电场可以通过作用于初级电子束和产生的二次电子来显著改变生长的 3D 纳米结构的尺寸。在进行的实验中，通过在生长过程中在图案化的金属微结构上施加中等电压（高达 200V），可以调节在石英、MgO 和非晶 SiO 上生长的 Pt-C 和 W-C 垂直纳米线的直径，达到 50nm 以下的直径。我们确定了由产生的电场引起的两种竞争效应：初级光束焦点的轻微变化和对二次电子的强烈作用。利用束散焦来实现生长过程中 3D FEBID 结构直径的原位调制。
