流化床CVD淀积过程中铝膜微结构及表面形貌的研究

Microstructure and Surface Topography of Aluminum Films Deposited on Glass Microspheres in a Fluidized Bed CVD Reactor

考察了在常压流化床 CVD反应器中利用三异丁基铝的热分解反应在高折射率玻璃微珠表面淀积铝膜时 ,淀积温度和时间对铝膜微结构和表面形貌的影响 .SEM谱的表面形貌分析表明 ,提高淀积温度时 ,铝膜经过三维岛状→孔洞结构→连续致密膜的变化 ;延长淀积时间 ,铝膜的晶粒会变粗变大 .AES谱的表面化学组成分析表明 ,在较高的淀积温度下铝膜中碳的残留并不明显 ,但发生了玻璃微珠基材中 Ti,Ba等元素向铝膜中的扩散 .

In this paper, we investigate the influences of deposition temperature and time on microstructure and surface topography of the aluminum films deposited on glass microspheres of higher refractive index by thermal decomposition of tri isobutyl aluminum in a fluidized bed CVD reactor at atmospheric pressure. SEM examination of surface topography of the films shows that under the same conditions, the increase of deposition temperature causes the aluminum films to change from 3 dimensional hillock formation to non specular, rough structure with steep peeks and valleys to uniform and smooth surface; and while extending the deposition time at certain temperatures, the grains become larger and surface roughness becomes distinct. The results demonstrate that by means of thermal activation at appropriately elevated temperatures(350~390 ℃) for a certain period of time(about 30 min), it is possible to provide smooth and uniform aluminum films on the surface of glass microspheres which may approximately conform with the requirements of retro reflective materials. Auger spectra for examining the surface chemical composition reveal that the preferred higher temperature used to obtain smooth topography does not introduce obvious contamination by carbon residues, but diffusion of Ti and Ba from substrates toward aluminum film occurs to some extent, which may be another factor to cause the activation of the substrate and to obtain smooth and uniform aluminum film on glass microspheres in this study. In order to further improve and control microstructure and surface topography of the aluminum films, it is necessary to adopt other appropriate activation process combined with thermal activation.