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

用于生产原子氮的主要等离子体源一直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、DO辉光放电、冷阴极枪。然而，这些等离子体源体积小，需要高压和放电电压来产生足够的原子氮通量用于等离子体处理。氮离解的最大截面约为60-130 eV。这意味着当电子能量在最大截面附近时，氮气的离解率就会很高。在本实验中，电子束激励等离子体(EBEP)沉积系统被设计用于产生50-150 eV的电子束能量。首先根据薄膜厚度和晶体结构确定了等离子体参数：放电电流Ib=3.4A，加速电压Va=600V，射频偏压V_2/Ar=8/10sccm。然后改变靶衬底距离，并对所合成的薄膜进行评估，估计该溅射系统的沉积速率约为10 nm/min。这一沉积速率与文献中报道的其他溅射系统相当。俄歇电子能谱分析表明，合成的薄膜是由1：1的硼和氮原子组成的。FTIR成键状态分析表明，在780 cm~(-1)和1370 cm~(-1)处出现峰，表明h-BN薄膜的形成。当靶基间距为50 mm时，硬度为10.3 Gpa，焊接体积为0.013 mm^3。摩擦系数和表面粗糙度与靶基间距无关，分别为4.5 nm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.