SC1 Cleaning Thermal Oxide Film Process Optimization Based on Box-Behnken Response Surface Method

With the continuous progress of integrated circuit manufacturing processes, higher and higher requirements are placed on the surface quality of wafers after wet cleaning to ensure product yield. To mitigate the thermal oxide film loss and the exacerbated within-wafer non-uniformity induced by SC1 cleaning, experiments were designed using the Box-Behnken design (BBD) method, and the response surface methodology (RSM) was integrated to optimize three key parameters of the SC1 cleaning process: Chemical solution temperature, solution ratio (V_\mathrmNH_4\mathrmOH ∶V_\mathrmH_2\mathrmO_2 ∶V_\mathrmH_2\mathrmO ), and process duration. Additionally, the effects of individual factors and their interactive effects on the cleaning performance were systematically investigated. The results indicate the following: When the cleaning time is fixed at 90 s and the thickness of the thermal oxide film to be cleaned is 3 nm, the SC1 solution exhibits the minimal impact on the oxide film surface under the conditions of 30 ℃ and a solution ratio of 1∶9.0∶50; at a temperature of 60 ℃ and a ratio of 1∶3.0∶50, the maximum loss thickness of the thermal oxide film is 0.065 nm, with the increment of within-wafer non-uniformity controlled within 1%; when the solution temperature is 60 ℃ and the solution ratio is 1∶6.5∶50, the maximum loss thickness of the thermal oxide film is reduced to 0.043 nm, and the increment of within-wafer non-uniformity is constrained within 0.5%; under the conditions of 55 ℃ and a solution ratio of 1∶8.0∶50, the loss thickness of the thermal oxide film can be maintained at 0.020 nm, while the increment of surface non-uniformity is limited to 0.24%. This study provides a valuable reference for the parameter selection of the SC1 cleaning process in integrated circuit manufacturing.