Research On The Simulation And Optimization Of CVD Process In Polysilicon Furnace

In this paper,we study on the uniformity of thermal and flow field in CVD furnace 0f the Modified Siemens process.We made simulation and optimization of CVD furnace flow field and thermal field,and the analysis was conducted to guide the production of polysilicon;According to the high power consumption,low production rate of the current production model,we worked on the development of production process and the control method of large scale CVD furnace which is represented by48-pair-rods,and also the 48-pair-rods furnace simulation and optimization was performed.Using software to establish the basic 36-pair-rodfurnace model,simulated and analysis 8 kinds of nozzle arrangement design,compared the flow and thermal field distribution of different nozzle arrangement,and found that the 18 nz 6zones arrangement has the best uniformity of thermal and flow field.Optimized the 48-pair-rods reduction process,utilized the heat of outlet gas;We established the growth model of 48-pair-rods furnace using PolySim simulation software,studied on flow and thermal field distribution,combined with 36-pair-rods nozzle optimization experience Model,An optimized nozzle arrangement and a48-pair-rods recipe were established.Through the optimization and improvement,the production rate improved 21.38%,the power consumption decreased 7.69%,TCS conversion increased about 14.42%,popcorn ratio decreased about 14.85%.Based on the experimental results of 48-pair-rods with different control parameters,combined with thermal and flow field problem of different growth stages in CVD furnace,determined the subsection feeding control method of rod48-pair-rods CVD process,established feeding control curve and furnace temperature control curve.Using temperature control mode,time control mode and constant current control mode,established CVD process current control curve,lay a theoretical basis for the realization of automatic feeding and current auto-control.