O2 plasma treatment in polymer insulation process for through silicon vias

Through silicon via (TSV) technology has been widely applied in CMOS image sensors (CIS). This paper reports the wetting behavior of polymer liquid in the TSV insulation process by spin coating. The O₂ plasma treatment was used to increase the hydrophilicity of the substrate surface in order to reduce the adhesion between the polymer liquid and the via sidewall. This surface treatment was to ensure that the polymer liquid can enter the vias smoothly. Besides, the O₂ plasma treatment to the wafer could also improve the wetting rate and decrease the balanced contact angle. During the course of the present study, different parameters of power and time of O₂ plasma treatment were used to modify the wafer surface and the sidewall of vias. The optimal O₂ plasma treatment condition was determined with the power of 160 W and the processing time of 25 s. It was confirmed that the method of O₂ plasma treatment is beneficial to the wetting in the deposition process of the polymer insulation layer for TSVs.