Development of cubic Boron Nitride (cBN) Thin Film Formation Process by Pulsed Laser Ablation

研究了脉冲Nd: YAG （532nm）和KrF （248nm）激光烧蚀合成立方氮化硼（cBN）薄膜的方法。BN薄膜沉积在硅（100）衬底上。激光束聚焦在六边形BN靶上。氮化硼薄膜的组成取决于氮气压力。在此条件下制备了化学计量BN薄膜；激光通量为3.8 J/cm^2，衬底温度为650℃，氮气压力为10.0Pa。将氩气与反应物氮气混合，并在衬底上施加射频功率，以产生负直流自偏置，首次增强了cBN相的合成。FT-IR吸收光谱分析表明，射频偏压下的氩离子轰击对cBN薄膜的形成起着重要作用。通过测量光发射光谱来估计加工等离子体的状态。俄歇电子能谱分析表明，N/B的组成比取决于氮的混合比和B^+ (345.1nm)的反应发射强度。532 nm激光制备的薄膜表面形貌粗糙，颗粒较多，而248 nm激光制备的薄膜表面光滑，颗粒较少，颗粒较小。采用脉冲激光烧蚀法制备了碳化钨（WC）和氮化碳（CN）薄膜。

A method of synthesizing cubic boron nitride (cBN) films using pulsed Nd : YAG (532nm) and KrF (248nm) laser ablation is investigated. BN films are deposited on silicon (100) substrates. The laser beam is focused on the hexagonal BN targets. The composition of the BN film depends on the nitrogen gas pressure. The stoichiometric BN films are obtained under the conditions ; a laser fluence of 3.8 J/cm^2 and the substrate temperature of 650ﾟC and the nitrogen gas pressure of 10.0Pa. Argon gas is mixed with the reactant nitrogen gas and an RF power is applied to the substrate in order to generate a negative DC self-bias and enhance the synthesis of cBN phase for the first time. FT-IR absorption spectroscopy shows that the argon ion bombardment by RF bias plays an important role in the formation of cBN films. Measurements of the optical emission spectrum are performed to estimate the processing plasma state. Auger Electron Spectroscopy shows that the N/B composition ratio depends on the mixture ratio of nitrogen and the reactive emission intensity of B^+ (345.1nm). The surface morphology of the films prepared by the 532 nm laser is rough with lager particulates, whereas much smoother surfaces with fewer and smaller particulates, are obtained with the 248 nm laser. We also prepared tungsten carbide (WC) and carbon nitride (CN) films by pulsed laser ablation method.