Suppression of oxygen and carbon impurity deposition in the thermal system of Czochralski monocrystalline silicon

When preparing large monocrystalline silicon materials,severe carbon etching and silicide deposition often occur to the thermal system.Therefore,a suppression method that optimizes the upper insulation structure has been proposed.Assisted by the finite element method,we calculated temperature distribution and carbon deposition of heater and heat shield,made the rule of silicide and temperature distributing in the system,and we explained the formation of impurity deposition.Our results show that the optimized thermal system reduces carbon etching loss on heat components.The lowered pressure of the furnace brings a rapid decrease of silicide deposition.The increase of the argon flow rate effectively inhibits CO and back diffusion.The simulated results agree well with the experiment observations,validating the effectiveness of the proposed method.