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以Cu膜为例 ,用Monte Carlo算法模拟了薄膜生长的随机过程 ,并提出了更加完善的模型 .在合理选择原子间相互作用计算方法的基础上 ,考虑了原子的吸附、在生长表面的迁移及迁移所引起的近邻原子连带效应、从生长表面的脱附等过程 .模拟计算了薄膜的早期成核情况以及表面粗糙度和相对密度 .结果表明 ,随着衬底温度的升高或入射率的降低 ,沉积在衬底上的原子逐步由离散型分布向聚集状态过渡形成一些岛核 ,并且逐步由二维岛核向三维岛核过渡 .在一定的原子入射率下 ,存在三个优化温度 ,成核率最高时的最大成核温度Tn、薄膜的表面粗糙度最低时的生长转变温度Tr,相对密度趋近于 1时的相对密度饱和温度Td.三者均随入射率的对数形式近似线性增大 ,并且基本重合 .同时发现 ,随着入射率的增大相对密度不断减小 ,但是在不同温度区域入射率对早期成核率和表面粗糙度的影响不同 .当温度较低时 ,随着入射率的增大最大成核率基本不变 ,表面粗糙度不断增大 ;当温度较高时 ,随着入射率的增大最大成核率不断增大 ,但表面粗糙度不断减小 .
Taking Cu film as an example, the random process of film growth was simulated by Monte Carlo algorithm and a more complete model was proposed.On the basis of reasonable calculation of the interaction between atoms, the adsorption of atoms, the migration on the growth surface As well as the desorption process of adjacent atoms caused by migration and the desorption process from the growth surface.The early nucleation and the surface roughness and relative density of the films were simulated.The results show that with the increase of the substrate temperature or the incident rate , The atoms deposited on the substrate gradually transition from the discrete distribution to the aggregated state to form some island nuclei and gradually transition from the two-dimensional island nuclei to the three-dimensional island nuclei. At a certain atomic incident rate, there are three optimum temperatures , The maximum nucleation temperature Tn at the highest nucleation rate, the growth transition temperature Tr at the lowest surface roughness of the film, and the relative density saturation temperature Td at a relative density close to 1. All of these are related to the logarithm of the incident rate Approximately linear increase, and the basic coincidence.At the same time, with the increasing of the incident rate, the relative density decreases, but in different temperature regions, the incidence of early nucleation rate Which is different from that of the surface roughness.When the temperature is low, the maximum nucleation rate does not change with the increase of the incident rate, and the surface roughness increases continuously. When the temperature is higher, the maximum nucleation rate increases with the increase of the incident rate The nucleation rate is increasing, but the surface roughness is decreasing.