a-SiN_x∶H薄膜退火前后微结构的Raman谱研究

Micro-Raman Spectroscopy Studies of As-deposited and Furnace annealed a-SiN_x ∶H Films

采用微区Raman谱 ,并结合红外透射测量研究了等离子体增强化学气相沉积方法制备的不同氮含量的a SiNx∶H样品退火前后TO模及TA模与样品微结构的关系。结果表明 ,氮的引入主要影响了第二近邻以外的中等程序的有序度 ,因而随N含量增加 ,TA模相对于TO模的强度增加且频率有较大的蓝移 ,TO模的频率及半高宽则变化较小。N的引入使得样品在750℃ (高于a Si∶H的晶化温度 )退火时不能结晶。退火引起大量H的逸出 ,使得样品的缺陷态密度大大增加 ,导致TO模和TA模均有大的红移 ,TO模的半高宽也急剧增加 ,并且在 492cm- 1 出现了退火前较难观察到的代表Si3

Microstructures of a SiN x ∶H films with different N contents prepared by plasma enhanced chemical vapor deposition(PECVD) were studied by Raman and infrared measurements.The results show that the introduction of N atoms significantly influences the structural order on a medium range scale,but weakly affects the short range structural order.The frequency and width of TO peak in Raman spectra are slightly modified by Si—N bonds while the frequency and intensity of TA peak correlate closely with the N contents.The crystallization of a SiN x ∶H is prevented by the N atoms in the film when they are annealed even at 750 ℃(much higher than the crystallization temperature of a Si∶H).The increasing of density of dangling bonds due to the release of H after annealing results in large redshift of both TO peak and TA peak and a broadening of their width,besides,the 492 cm -1 feature which originates from Si 3 N breathing mode is enhanced after annealing.