Experimental Process And Numerical Analysis Of Large Diameter Silicon Single Crystal Growth

Large diameter silicon single crystal is the key material for micro-electronics industry.According to Semiconductor Equipment and Materials International(SEMI)report,the demand for large diameter silicon single crystal is huge in global market.Presently,400mm silicon crystals with low cost are urgently demand for the manufacturing of integrated circuit(IC)structural components.Accordingly,the development of 400mm preparation process is of great practical and economical significance.At the same time,research and development of the next generation 450mm IC-grade silicon crystal,including the effect mechanism of magnetic fields on crystal growth process,are of vital importance.Based on the theories of crystal growth and fluid mechanics,this dissertation adopts the method of combining experiment and numerical analysis.We take the large diameter crystal preparation as the main research object,carrying out design of thermal field and process parameters.We research the effect of hot-zone design,control parameters and magnetic field on the large diameter single silicon crystal growth.We employ 28inch and 32inch hot zone to prepare 400mm and 450mm single silicon crystal respectively.The crystal growth is analyzed by electrical property and chemical components.The main contents of the thesis are as follows:(1)Numerical analysis is adopted to research the effect of heat shield on crystal growth.Although using steep heat shield could flat the melt/crystal interface shape and reduce the thermal stress,it increases the risk of undercooling at the edge of the melt.We employ slope heat shield in the following experimental process.In addition,we analyze the effect of melt level on the crystal growth.With the increase of melt level position,the thermal stress in the crystal will increase,the melt/crystal interface become more convex to the melt,the v/G ratio fell slightly.(2)Numerical analysis is adopted to study the influence of main control parameters on the crystal preparation.The pull rate affects the crystal temperature field and the heater power.The heat generated at the interface must be conductively transported into the crystal,while maintaining the position of the tri-junction point.The change of the argon flow directly affects the distribution of temperature in the crystal and oxygen content in the melt.The melt flow regime is strongly sensitive to the rate of rotations of both crystal and crucible.Interfaces with low deflection can be achieved for certain combinations of crystal and crucible rotation rates.(3)400mm silicon<100>crystal lightly doped with boron has been prepared from 28inch hot zones.The results show that 28inch hot zones can replace conventional ones to grow 400mm diameter silicon single crystals.The change in crucible diameter can save energy,reduce cost and improve efficiency.The trend of oxygen distribution obtained in calculations is in good agreement with experimental values.The experimental results show that the wafer is fully vacancy rich with a higher precipitation band at the edge but no OISF-ring.(4)We prepare 450mm diameter silicon single crystal under CUSP magnetic field.The magnetic field has a greater ability to control oxygen in the melt at end of body growth.In addition,we research the effect of magnetic field and zero gauss position(ZGP)on the crystal growth.The results show that the turbulence intensities have been effectively dampened by the magnetic field.In consideration of energy saving,we choose 500Gs in the crystal growth process.The oxygen concentration in the melt decrease 27.40%,the oxygen concentration along the interface decrease 25%,radial uniformity along the interface increase 35%during the magnetic field increase to 1000Gs.The oxygen concentration at the interface reaches the minimum when the ZGP locates above the free surface.