Development of Removal Technology Using Ozone Microbubble With a Venturi Tube

The removal technology of single-wafer processing using ozone is proposed on photoresist stripping in the semiconductor manufacturing in order not to generate residual sulfate group after stripping. It is revealed that Disk-shaped nozzle proposed by the authors forms a vortex structure between the disks which is considered to cause the reduction of photoresist stripping rate. This study proposes a disk-shaped convex nozzle. In order to investigate the effects on the flow caused by the presence or absence of the convex, visualization using a high-speed video-camera and numerical simulation of the flow between the disks were conducted. Also, the stripping experiments were conducted to investigate the effects on the photoresist stripping rate caused by the presence or absence of the convex. As a result, the vortex structure that was observed in the disk-shaped nozzle has been disappeared in the disk-shaped convex nozzle. In addition, it is revealed that disk-shaped convex nozzle has the higher stripping ability than disk-shaped nozzle in the convex part. Next, as a stripping method that is different from the conventional, we suggest the ozone microbubble with a venturi tube. To obtaining knowledge about the performance of the photoresist stripping with the ozone microbubbles, first, the generation of ozone microbubbles is observed in the venturi tube via a high speed video camera. Next, to clarify the effect of the superficial liquid and gas velocities on the ozone water concentration and the photoresist stripping rate, ozone water concentration measurement and photoresist stripping experiments were conducted. As a result, the ozone water concentration with increasing superficial velocity increase and the remaining photoresist thickness reduce. In addition, compared with the existing study, it is suggested that the superficial liquid and gas velocities and ozone water concentration affect the photoresist stripping rate.