氮气含量对AlCrTaTiZrMoN_x高熵合金氮化物薄膜扩散阻挡性能的影响

Influence of N_2 Content on Diffusion Barrier Property of AlCrTaTiZrMoN_x High-Entropy Alloy Nitride Film

国内对高熵合金的研究主要集中于其优异的力学性能,还未见有关高熵合金扩散阻挡性能的报道。采用直流磁控反应溅射方法在不同N_2流量占比气氛中制备了AlCrTaTiZrMoNx薄膜与Cu/AlCrTaTiZrMoNx/Si复合试样,并对样品真空退火1h。用X射线衍射仪(XRD)、原子力显微镜(AFM)、四探针电阻测试仪(FPP)、场发射扫描电镜(SEM)对退火前后样品的物相结构、表面粗糙度、形貌以及方块电阻进行了分析表征,研究了薄膜的热稳定性和扩散阻挡性能。结果表明:随着N_2流量占比的增加,高熵合金氮化物薄膜表面粗糙度增加,方块电阻也单调增加;N_2流量变化会改变薄膜结构,未通入N_2时,薄膜为非晶结构,当通入N_2后,N原子会与金属原子形成氮化物,使结晶性能得到提高,薄膜结构为面心立方,N_2流量占比为20%时,薄膜结晶较好,晶粒细小;当N_2流量占比为0时,复合试样在700℃退火时失效;N_2流量占比为10%时,复合试样在800℃退火时失效;N_2气流量占比为20%和30%时,复合试样在800℃退火后,其X射线衍射峰没有明显的变化,复合试样表面较为平整,此温度为极限温度;在900℃退火后,复合试样界面发生了相互扩散,生成了高阻态铜硅化合物,表面粗糙度显著升高,表明扩散阻挡层已经彻底失效;可见,随着N_2流量占比的增加,高熵合金涂层的扩散阻挡性能和热稳定性得到提高,但当N_2流量占比大于20%时,其阻挡性能和热稳定性提高不明显。

Two kinds of high-entropy alloy nitride films （AlCrTaTiZrMoN, and Cu/AlCrTaTiZrMoNx/Si） were deposited by DC reactive mag- netron sputtering in N2/N2 ＋Ar ambient with different N2 flow ratios, which were then annealed under 400-900 ℃ for 1 h. Component phase structure, morphology and roughness were characterized by X-ray diffractometer, scanning electron microscopy and atomic force microscopy. Four-point probe （FPP） was used to analyze thermal stability and barrier performance. Results showed that with the N2 flow ratio increasing, surface roughness increased and the sheet resistance monotonically increased as well. The change of N2 content influenced the film structure ： in absence of N2 , the film was amorphous. However, when N2 was added, the nitride of the metals formed and crystallization was improved, as well as the film structure was face-centered cubic. When the Nz flow ratio was 20%, the film had a good ctystallinity and the grains were fine. When N2 flow ratio was 0, the composite failed when annealed at 700 ℃ ; when N2 flow ratio was 10%, the composite failed when annealed at 800 ℃ ; when N2 flow ratio was 20% and 30%, X-ray diffraction peaks had no obvious change and the surface was flat under anne＇fling at 800 ℃. After annealing at 900 ℃, interdiffusion happened at its interface, and high resistivity silicide formed, which indicated the diffusion barrier film failed thoroughly. It was obvious that with the increase of N2 content, the thermal stability and barrier performance were improved as the N2 flow ratio increased. However, when N2 flow ratio was more than 20%, the improvement of thermal stability and barrier performance was not obvious.