Surface treatment process using photoemission-assisted plasma for achievement of atomic scale flattened surface

光电子发射辅助等离子体(PAP)离子源已被开发出来，用于将金属衬底的表面形貌平整到原子尺度的粗糙度。在本研究中，用朗缪尔探针测量了离子撞击表面的动能，得到0.1-30 eV的PAP的动能。在低能量(~lt；30 eV)和改变离子注量(~lt；1018 cm-2)的条件下，对Ra(0)为~13 nm的铜沉积硅衬底进行了PAP辐照。原子力显微镜表面分析表明，与Ra(0)相比，表面粗糙度降低了15~70%。然而，由于高离子注量的辐照，表面会形成突起，导致表面粗糙度增加。从离子能量和离子通量两个方面揭示了控制表面形貌变化的实验条件。根据观察结果，我们认为低Ek的PAP对表面原子的表面迁移增强对表面形貌的变化起着至关重要的作用。

Photoemission-assisted plasma (PAP) ion source has been developed for flattening surface morphology of metal substrates down to an atomic-scale roughness. In this study, ion kinetic energy (Ek) of impinging on surface was estimated by Langmuir probe measurement, resulting in Ek of PAP with 0.1-30 eV. PAP irradiations to Cu-deposited Si substrates with Ra(0) of ~13 nm were conducted in low energy (< 30 eV) and changing ion fluence (< 1018 cm-2) regime. From the surface analysis by atomic force microscopy, surface roughness were reduced down to 15~70% compared of Ra(0). However, protrusions formed on the surfaces due to high ion fluence irradiation, which caused increase of surface roughness. The experiment conditions that control the surface morphology changes are revealed from the aspect from ion energy and ion fluence. Based on the observations, it is considered that surface migration enhancement of surface atoms induced by low Ek of PAP plays a vital role for the morphology changes.