Development for the Synthesis of Very Hard Thin Films by Electron Beam Excited Plasma

生产原子氮的主要等离子体源是传统的等离子体源，包括电子回旋共振（ECR）等离子体、射频（RF）等离子体、辉光放电、冷阴极枪等。然而，这些等离子体源体积小，需要高的压力和放电电压才能产生足够的原子氮通量进行等离子体处理。氮解离的最大截面约为60-130 eV。这意味着当电子能量在最大截面附近时，氮的高解离率可以实现。本实验设计了电子束激发等离子体（EBEP）沉积系统，用于产生50-150 eV的电子束能量。首先，根据镀层厚度和晶体结构，确定了放电电流I_b、加速电压V_a、射频偏置电压V_<dc>和N_2/Ar比值为I_b=3.4A、V_a=120V、V_<dc>=600V和N_2/Ar=8/10 sccm。然后改变目标衬底距离，并对所合成的薄膜进行评价，估计溅射系统的沉积速率约为10nm/min。该沉积速率可与文献报道的其他溅射系统相媲美。在对合成膜的评价中，AES结果表明，合成膜由硼原子和氮原子以1:1的比例组成。FTIR的键合态分析显示，在780cm^<-1>和1370cm^<-1>处的峰值表明h-BN薄膜的形成。当靶基板距离为50mm时，测得硬度为10.3 GPa，战体积为0.013mm^3。摩擦系数和表面粗糙度均与目标衬底距离无关，分别为4.5nm和0.085。

The primary plasma sources for the production of atomic nitrogen has been the conventional plasma sources, including electron cyclotron resonance (ECR) plasma, radio frequency (RF) plasma, do glow discharge, cold cathode gun. These plasma sources however use small volume and need a high pressure and discharge voltage to produce sufficient flux of atomic nitrogen for plasma processing. The maximum cross section for nitrogen dissociation is about 60-130 eV. These means that a high dissociation rate of nitrogen can be achieved if the electron energy were around the maximum cross section In this experiment the electron-beam-excited plasma (EBEP) deposition system used was designed to produce electron beam energy of 50-150 eV. At first, the plasma parameters discharge current I_b, acceleration voltage V_a, rf bias voltage V_<dc> and N_2/Ar ratio were determined in view of the deposit thickness and crystal structure to be I_b=3.4A, V_a=120V V_<dc>=600V and N_2/Ar=8/10 sccm. The target substrate distance was then varied and the synthesized films were evaluated The deposition rate of the sputtering system was estimated to be about 10nm/min. This deposition rate is comparable to other sputtering systems reported in literature. In evaluating the synthesized films, the AES results show the synthesized film was formed out of boron and nitrogen atoms with a 1:1 ratio. The bonding state analysis of the FTIR show peaks at 780cm^<-1> and 1370cm^<-1> indicating formation of h-BN thin film. For target substrate distance of 50mm, the hardness and war volume were measured to be 10.3 GPa and 0.013mm^3, respectively. The friction coefficient and surface roughness were both independent of the target substrate distance with values of 4.5nm and 0.085, respectively.