Materials Science, Zernike Institute for Advanced Materials, University of Groningen, Nijenborg 4, 9747 AG Groningen, The Netherlands.
Nanotechnology. 2013 Aug 30;24(34):345301. doi: 10.1088/0957-4484/24/34/345301. Epub 2013 Jul 30.
The current understanding in the study of focused electron beam induced processing (FEBIP) is that the growth of a deposit is mainly the result of secondary electrons (SEs). This suggests that the growth rate for FEBIP is affected by the SE emission from the support. Our experiments, with membranes thinner than the SE escape depth, confirm this hypothesis. We used membranes of 1.4 and 4.3 nm amorphous carbon as supports. At the very early stage, the growth is support-dominated and the growth rate on a 4.3 nm thick membrane is three times higher than on a 1.4 nm thick membrane. This is consistent with Monte Carlo simulations for SE emission. The results suggest that SEs are dominant in the dissociation of W(CO)6 on thin membranes. The best agreement between simulations and experiment is obtained for SEs with energies between 3 and 6 eV.With this work we revisit earlier experiments, working at a precursor pressure 20 times lower than previously. Then, despite using membranes thinner than the SE escape depth, we did not see an effect on the experimental growth rate. We explain our current results by the fact that very early in the process, the growth becomes dominated by the growing deposit itself.
目前，在聚焦电子束诱导加工（FEBIP）的研究中，人们普遍认为沉积物的生长主要是二次电子（SEs）的结果。这表明 FEBIP 的生长速率受到支撑体中 SE 发射的影响。我们的实验证实了这一假设，所使用的膜厚度小于 SE 逃逸深度。我们使用了 1.4nm 和 4.3nm 厚的非晶碳膜作为支撑体。在非常早期的阶段，生长由支撑体主导，4.3nm 厚的膜的生长速率是 1.4nm 厚的膜的三倍。这与 SE 发射的蒙特卡罗模拟结果一致。结果表明，SE 在 W(CO)6 在薄膜上的离解中起主导作用。对于能量在 3 到 6eV 之间的 SE，模拟和实验之间的吻合度最好。通过这项工作，我们重新审视了早期的实验，在比以前低 20 倍的前体压力下工作。尽管使用的膜厚度小于 SE 逃逸深度，但我们没有看到对实验生长速率的影响。我们用以下事实来解释我们目前的结果：在过程的早期，生长就由不断生长的沉积物本身主导。
