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Si-rich Silicon Nitride Thin Film Prepared By Hot Wire Chemical Vapor Deposition And Performance Analysis

Posted on:2016-08-06Degree:MasterType:Thesis
Country:ChinaCandidate:N ZhangFull Text:PDF
GTID:2191330464966320Subject:Optics
Abstract/Summary:PDF Full Text Request
As a kind of important functional film material, silicon nitride film has become a hot spot in domestic and foreign research. Because of its good insulation, compactness, stability and resistance to water vapor penetration ability, and can effectively prevent B, P, Na impurity diffusion, being used as the passivation film, the insulating layer or the diffusion mask of Microelectronic Materials and devices. In recent years, with the strong visible light induced luminescence of porous silicon at room temperature found, what breaks through the previous forbidden region bulk silicon has an indirect band gap can not effective emit. Another application of silicon nitride thin film is recognized. At present, there has been a lot of reports that nano Si clusters embedded in the silicon oxide or silicon nitride can obtain a stable and effective luminescence. As the embedding matrix material, silicon oxide has a wide band gap,9.0eV, silicon nitride with a band gap of 5.4ev, tunneling barrier is low, is more benefical to the carrier injection, is the most excellent embed matrix material for silicon nanoclusters.The rich silicon nitride is the necessary condition for the formation of silicon quantum dots, and the methods on preparation of the rich silicon nitride films has a lot, common methods like low pressure chemical vapor deposition (LPCVD), plasma chemical vapor deposition (PECVD) and magnetron sputtering method, and many other kinds of methods with post annealing treatment. Hot filament chemical vapor phase deposition (HWCVD) is a relatively new deposition technology. It is widely used in the study of microcrystalline silicon and poly crystalline silicon thin film, but very rare in silicon nitride thin films. Hot filament chemical vapor deposition method has a lower substrate temperature, high deposition rate, easy to crystallization and the film without ion bombardment effect, making the technology of silicon quantum dots preparation also has great prospects.The experiment based on hot wire chemical vapor deposition (HWCVD) fabricated the silicon rich silicon nitride films. Three sets of experimental datas were achieved by different gas sources reacting with SiH4, like the N2, NH3and combine NH3 with H2. properties of silicon rich silicon nitride were investigated by changing the N2 flow rate and NH3 flow rate, hot filament temperature. The main conclusions are follows:(1)Using SiH4 and N2 as reaction gases, N2 is not easy to decompoud in the hot filament, chemical vapor deposition. Nitrogen content of prepared samples is not high, The structure of thin films mainly exists in the form of amorphous silicon, sample is easily oxidized, has many defect states, film quality is bad.(2)Using NH3, SiH4 and H2 as reaction gas, adjust the NH3/SiH4 ratio to observe change of silicon rich silicon nitride characteristic. With increase of the ratio of gas, film band gaps also slowly widen, give full play to the filament advantages, realize the good control of the film from the silicon-rich to nitrogen-rich. At the same time, with the increase of N atoms, the order degree of the film increases, the refractive index decreases and changes obviously. Displayed by the Fourier transform infrared absorption spectrum (FTIR):the number of Si-N bond, N-H bond increase with the flow rate increases, while the Si-H bond on the contrary. With the N atoms increase, defect state increases obviously.(3)With NH3> SiH4 and H2 as reaction source, it was found that the filament temperature had an obvious effect on N and H content that in the films, and appeared non monotonic changes, primarily attributed to different gas decomposition temperature. Scanning electron microscope observation, it is found that at 1500℃ the size about 1.5um silicon grains appeared in the film, concluded that the hydrogen content of the many directly affect the film crystallization.
Keywords/Search Tags:hot filament chemical vapor deposition, SiNx:H thin films, photoluminescence, bonding structure
PDF Full Text Request
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