不同氮流量比制备纳米Ta-N薄膜及其性能

Properties of Ta-N thin-films fabricated with different N_2 flow ratio

超大规模集成电路Cu互连中的核心技术之一是制备性能优异的扩散阻挡层。本文采用直流磁控反应溅射在N2/Ar气氛中制备了不同组分比的Ta-N薄膜,并原位制备了Cu/Ta-N/基底复合结构,对部分样品在N2保护下进行了快速热处理(RTA),采用台阶仪、四探针测试仪、原子力显微镜(AFM)、扫描电镜、X射线衍射(XRD)对薄膜形貌结构进行了表征。结果表明,随着N2流量比的增加,薄膜沉积速率下降,表面趋于平滑,Ta-N薄膜热稳定性能及阻挡性能随之提高,而电阻率则上升。氮流量比为0.3制备的厚度为100nm的Ta-N薄膜经600℃/5m in RTA后,仍可保持对Cu的有效阻挡;在更高温度下退火,Cu将穿过阻挡层与Si发生反应,导致阻挡层失效。

One of the urgent research topics in Cu interconnection for ULSI is to fabricate suitable barrier to prevent Cu diffusion. In this paper, Ta - N thin - films were fabricated by DC magnetron reactive sputtering in N2/Ar ambient with different N2 flow ratio, then Cu/Ta - N/substrate multi - structures were prepared without broken the vacuum, some specimens were rapid thermally treated（RTA） in N2 ambient. Alpha- Step IQ Profiler, fourpoint probe sheet resistance measurer, atomic force microscope（ AFM）, scanning electron microscope （SEM） and X - ray diffraction （XRD） were used to characterize the surface morphology and structure of the specimens. The research indicates that with the N2 flow ratio increasing, the deposition rate decreases, the surface tends to become smooth and the thermal stability and diffusion barrier property are improved, while the sheet resistance increases. Ta- N barrier（ 100nm thickness）can effectively against Cu diffusion after 600℃ annealing for 5 minutes with the N2 flow ratio of 0.3, Cu can diffuse through the barrier and react with Si after annealing at higher temperature.