氮掺杂对氟化非晶碳薄膜微观结构的影响

Effects of Nitrogen Doping on Microstructure of Fluorinated Amorphous Carbon Thin Films

以CH4,CF4,N2为源气体,用RF-PECVD法,通过改变N2流量制备了一批掺氮氟化非晶碳(a-C∶F∶N)薄膜样品。分析了氮掺杂对薄膜微观结构的影响。研究发现:掺氮后薄膜表面更均匀致密,均方粗糙度(RMS)由未掺氮的2.553 nm降为1.406 nm。FTIR测试表明掺氮后薄膜中出现了C=N及C≡N,随着氮流量的增加,1 620 cm-1附近吸收峰往高频移动,CFx基团含量下降,C=C基团含量上升。Raman光谱分析表明:随着氮流量的增加,D峰与G峰强度之比由未掺氮时的1.461增加到了掺氮后的2.545,薄膜内sp2键态含量增加,即芳香环式结构比例上升。结果表明:掺氮能有效增强a-C∶F薄膜交联结构,从而提高薄膜热稳定性。

Nitrogen doped fluorinated amorphous carbon（a-C ： F） thin films were prepared with RF-PECVD by using CH4, CF4 and N2 as the source gases at various N2 gas flow rates. The results reveal that the surface of the films with nitrogen doped became more homogeneous, the RMS roughness of the films was reduced from 2.553 nm to 1.406 nm after nitrogen incorporation. The FTIR spectra show that the nitrogen-doped films contain C=N and C≡N bonds, the absorption peaks around 1 620 cm^-1 shifted to high frequency, the contents of C：C bonds increased with the increase ofnitrogen gas flow rate while the contents of CFx radicals decreased. Raman spectra shows the intensity ratio ID/IG of Raman bands of disordered graphite （D-band） and graphite（G-band） of a-C ： F films increased from 1. 461 to 2. 545 after nitrogen incorporation, which indicates an increase of the fraction of aromatic ring. Based on these results, it is suggested that nitrogen doping is a feasible way to strength the cross-linked structure of a-C ： F films, thus to improve the thermal stability of films.