接著透過調整預鍍參數大幅縮短產出高品質之超薄鈍化薄膜之準備時間。最後透過堆疊10nm磷化氫摻雜薄膜與5nm本質鈍化薄膜，達到場效鈍化lifetime1900µs之水準。驗證本自行開發之PECVD系統之製程能力。 ;In this study, using hardware equipment as the starting point, the in situ plasma diagnostic systems of optical emission spectrometry (OES) and quadrupole mass spectrometry (QMS) was used to improve the hardware and process of PECVD machine, and a complete PECVD system was constructed from scratch.
In terms of hardware testing, firstly, by monitoring the change of angle of the pressure control valve under different flow rates and pressures, the corresponding lower limit of the process flow and pressure is confirmed. Then use OES to perform an Ar plasma discharge test to understand the change trend of the electrode spacing of the machine to the RF power absorption. Finally, the development of target process window of the PECVD system is defined by the operation interval of the plasma diagnostic tool.
In terms of process development, in the process of optimizing the process reproducibility of the ~5nm ultra-thin intrinsic passivation layer, after plasma diagnosis and thin film analysis, it was found that the cross-contamination phenomenon of the previous process residue and the residual moisture of the chamber wall are the main factors affecting the reproducibility of the ultra-thin intrinsic passivation layer. According to the analysis results, the OES intensity of the clear process (F*/O*=0.9~1.4) is taken as the standard for the end-point of the chamber cleaning process, and the chamber coating thickness of the predeposition process needs to reach 1800 nm or above. A method for stably producing high-quality 5nm ultra-thin passivation film (minority carrier lifetime stable up to ~800us) was established for use by the research team.Then, by adjusting the predeposition parameters, the preparation time for producing a high-quality ultra-thin passivation film is greatly shortened. Finally, by stacking a 10 nm phosphide doped film and a 5 nm intrinsic passivation film, the field effect passivation lifetime 1900μs is achieved. Verify the process capability of this self-developed PECVD system.
