Evolution of amorphous carbon films into nano-crystalline graphite with increasing growth temperature in plasma-enhanced chemical vapor deposition

Amorphous carbon films (ACFs) have recently emerged as one of the best candidates for etching-resistant hardmask materials in advanced semiconductor manufacturing processes. Etching resistivity of ACFs is known to be improved by controlling the relative abundance between sp² and sp³ bonds. We have investigated the relative abundance between sp² and sp³ bonds in several ACFs, fabricated by plasma-enhanced chemical vapor deposition at different temperatures, which were analyzed by using X-ray photoemission spectroscopy, Raman spectroscopy, and transmission electron microscopy. We found that the relative abundance of sp² bond increased as the growth temperature was raised. Furthermore, the ACFs eventually evolved into nano-crystalline graphite with increasing growth temperature.     

SEM/TEM characterization of periodical novel amorphous/nano-crystalline micro-composites obtained by laser interference structuring: The system HAlO-Al·Al2O3

Layers of the metastable, amorphous HAlO are synthesized by chemical vapor deposition from the molecular compound tert-butoxyalane ([^tBu-O-AlH₂]₂). At temperatures above 500 °C, these layers transform to biphasic Al·Al₂O₃ due to the elimination of di-hydrogen. The interaction of HAlO films with short laser pulses causes partial transformation of amorphous HAlO into nano-crystalline Al·Al₂O₃. Using an interference pattern of two coherent high-power Nd:YAG laser beams produces local and periodic heating, inducing crystallization at equally distant lines in the HAlO layer. Depending on the laser fluence, different morphologies and different amounts of crystalline phases are obtained. In this study, the surface morphology and the distribution of crystalline phases of the structured samples are analyzed using SEM, FIB and TEM. The two-dimensional structures consist of periodic variations of morphology, chemical composition, and phase identity with a well-defined long-range order. When bio-functionalized, the structured samples may be used as carriers for structurally controlled cell-cultivation.