Investigation of dielectric film thickness nununiformity using plasma enhanced chemical vapor depsotion for 28nm technology

The plasma enhanced chemical vapor deposition (PECVD) was widely applied to deposit dielectric film such as low k, porous ultra low k (p-ULK), SiCN (nitrogen doping silicon carbon), SiN (nitrogen silicon), and oxide. However, the dielectric film thickness nununiformity became very challenge with of device decreasing 28nm technology and wafer size increasing to 300mm. RF (radio freqency) indicated that the intensity of RF power in center higher than that of wafer edge. The deposited dielectric film indicated that the thickness of film in wafer center was lower than that in wafer edge. Furthermore, the pore number of gas distribution plate in edge, and the dielectric film thickness nununiformity was changed from 3.7 to 20%. This indicated that the pore design of gas distribution plate played the very important role for the dielectric film thickness nununiformity. Finally, the model of the dielectric film thickness nununiformity was put forwarded, giving direction of re-design for the gas distribution plate.