Preparation Of Semiconductor Passivation Si₃N₄ Thin Films And Charateristic Research

We focused on Thermal-Decompose analysis, which deposited SNTF on silicon substrate while N2, NH3 and SiH4 were used as reaction gas. In our experiment SNTF were synthesized successfully at 800℃ with appropriate reaction condition which the flow velocity of N2, NH3 and SiH4 were controlled as 51 ml/min, 100 ml/min, and 30ml/min respectively. Infrared spectrum was to confirm the components of the result sample. The result revealed that silicon nitride was the mainly component except few silicon dioxides. The surface of SNTF was fit for observation by atomic force microscope (AFM) and the sample surface was continuous without crack. Then thin films were prepared into MIS structure. MIS structure sample was tested by RLC instrument and the result showed a lot of difference compared with ideal flat voltage (-61V). This result ensured that there was a lot of electronic trap in SNTF and silicon substrate interface. The electronic properties of apparatus surface was much affected by these electronic trap result in apparatus instability. So it was important to combine the passivation of silicon nitride with the interface properties of silicon dioxides. We aggraded about 100 angstrom silicon dioxides on the substrate and 1500 angstrom silicon nitride to attain double layered structure. Testing flat voltage was –4V, and there was small deference with ideal model flat voltage. The result showed that Si3N4 thin films with high density interface charges can not be used directly as semiconductor surface passivation, thus dual layers structure passivation thin films not only reduce interface charges but also enhance semiconductor apparatus stability. So dual layers structure is a kind of prospective passivation method.