【摘要】 室温下在3.45eV的激光激发下,对950℃温度下淀积的LPCVD富硅的SiNx薄膜中,观测到5个高强度的可见荧光的发射。其峰位位置分别为2.7,2.69,2.4,2.3,2.1eV。通过TEM、IR、XPS等的分析研究表明,该样品为纳米硅镶嵌结构的a SiNx∶H复合膜,分析了其微结构的成因及其与膜内应力之间的相互关系。经过1000～1200℃快速退火(RTA)处理,原PL谱蓝移并只出现了峰位为3.0,2.8eV的两个紫蓝色荧光的发射,用能隙态模型对此结果做了初步的分析和讨论。认为薄膜中纳米硅团簇的密度、尺寸的变化和亚稳态缺陷态对其PL峰以及膜应力起着十分重要的作用。更多还原

【Abstract】 Silicon nitride has better high temperature capabilities than most metals combining retention of high strength and creep resistance with oxidation resistance. In addition, its low thermal expansion coefficient gives good thermal shock resistance compared with most ceramic materials. Silicon nitride is widely used in semiconductor process and micro-electromechanical systems （MEMS） for its advanced material properties. The silicon nitride thin films prepared by low pressure chemical vapor deposition （LPVCD） technique at the deposition temperature of 950 ℃ shows strong greenish-blue visible photoluminescence （PL） emission with five separate peaks at 2.7, 2.69, 2.4, 2.3 and 2.1 eV, respectively, by the 3.45 eV laser excitation, at room temperature. The results of TEM, IR and X-ray photoelectron spectroscopy（XPS） show that the N/Si （ratio） of the films is 0.75,which means the film is silicon-rich, and the film is constructed with mosaic crystal （silicon） nanoclusters embedded in silicon nitride solid, the dimension of which is about tens nanometer. To find out the luminescence property of as-deposited thin films, a series of LPCVD SiN_x films was treated by rapid thermal annealing （RTA） for 15 s in N₂ at 1 000,1 100 and 1 200℃, and we analyzed the changes in PL spectra, composition and microstructure caused by the RTA process. We found after RTA, the relative intensity of some peaks changed, and two new photoluminescence peaks appears at 3.0 eV and 2.8 eV.We believe the peaks at 2.7,2.3,2.1 eV is separately caused by the electronic transition of ≡Si⁰→N—Si—O , ≡Si⁰→N^-, E_c→≡Si^-, the peaks at 2.69 and 2.4 eV is caused by the electronic transition of ≡Si⁰→Si—O—Si, E_c→≡Si⁰.Those peaks will change after RTA, for the thin film’s composition and defect state density can be changed by RTA process. And we also found the nano-silicon microstructure can greatly decreased the stress of SiN_x film （to 10⁷ Pa）, which can help us to prepare high quality silicon nitride films.更多还原