Electronic Structures and the Mechanical Stability of Ultra-thin Metal Films on the Semiconductor Surface and the Effect of Internal Stress on Them

用分子束方法和溅射方法在Si(111)晶面、碳片和玻璃的非晶面沉积了厚度为1~10纳米的铟(In)、铅(Pb)和银(Ag)薄膜，用反射高能电子衍射(RHEED)和电子能量损失谱(ELS)研究了薄膜的二维晶体结构和电子态。在晶体表面上，建立了In和Pb的厚度与温度的相图。在损耗谱中，外延生长的薄膜中可以观察到一定的价电子或核心电子的跃迁，但随着结晶度的降低，这些相图变得不明确。金属薄膜在半导体表面有以岛状生长的趋势，用电子显微照片分析了薄膜的尺寸和岛间分布。在溅射沉积的薄膜中观察到了明显的动力学效应和荷电效应，通过内应力和划痕实验测量了薄膜在实际条件下的耐久性，考察了薄膜/衬底的不同组合和制备条件对薄膜耐久性的影响。内应力对粘接强度没有直接影响，但由于表面污染和粗糙度，观测强度的离散性变得很大。对衬底施加正偏压会导致温度升高，岛状结构与真空沉积得到的岛状结构接近。当施加负偏压时，岛状结构变得细小但均匀。建立了一种通过在衬底上施加适当的电压来控制微晶结构取向的技术。

Thin films of indium (In), lead (Pb) and silver (Ag) whose thickness ranges from 1 to 10 nanometers, have been deposited on crystalline surface of Si(111), amorphous surfaces of carbon and glass by using molecular beam methods and sputtering.Reflection high energy electron diffraction (RHEED) and electron energy loss spectroscopy (ELS) were employed to study the two-dimensional crystalline structure and the electron states. On the crystalline surface phase diagrams of In and Pb have been established concerning the thickness and the temperature.In the loss spectrum, definite transitions from valence or core electrons could be observed in films growing epitaxially but they became ambiguous as crystallinity decreased. Metal films have a tendency to grow in island form on the semiconductor surface, the size and interisland distributions were analyzed on the electron microphotographs. The kinetic effects and the effect of charge up were observed clearly in the sputter deposited thin films.The durability of thin films under the practical condition was measured from the internal stress and the scratch test.Various combinations of films/substrate and the effect of the preparation conditions were examined. Internal stress does not effect directly on the adhesion strength but the scatter of observed strength becomes great due to surface contamination and roughness. Applying positive bias to the substrate results in a temperature rise and the island structure is close to those obtained by vacuum deposition. When negative bias is applied, island structure becomes small but uniform. A technique to control the orientation of the craystallite structure by applying a proper voltage to substrate has been established.