Research On The Application Of Microwave Heating Technology And Equipment In The Preparation Of Polysilicon

At present,the annual average growth rate of the world's photovoltaic industry is31.2%,and its growth rate ranks first in the global energy power generation market.It is estimated that by 2030,photovoltaic power generation will account for more than33.3%of the world's total power generation.By 2050,the use of solar power will become an important source of energy for human development.With the introduction of relevant policies and the formulation of corresponding plans in various countries,the development of the photovoltaic industry is truly moving towards a path of rapid development.Yunnan Province has abundant distribution of silicon resources and unique advantages in developing photovoltaic industry.Preparation of the silicon material plays an important role in the photovoltaic industry.Polysilicon is the most important photovoltaic material in silicon materials,which is an important link affecting the development scale of silicon material preparation industry.In this paper,the dielectric properties of polysilicon are studied for the development status of photovoltaic industry,the traditional polysilicon preparation process and equipment,such as high energy consumption and high cost.The research on quality function(QFD),invention problem solving theory(TRIZ)and fuzzy synthesis Based on the evaluation method(FCE),the microwave high-temperature heating system was optimized,and a microwave high-temperature heating system was developed.Finally,the microwave heating polysilicon experiment verified that the technology equipment can be used in the polysilicon preparation process and obtained some valuable results.The main conclusions are as follows:(1)The dielectric test method and test system was introduced.The influence law of polysilicon dielectric properties at 25~oC-800~o C under the conditions of frequency2450MHz and 915MHz is studied.At the frequencies of 2450MHz and 915MHz,the maximum dielectric constant of polysilicon is 18.07 and 19.003 at 800~o C,respectively,and the loss factors are 0.565 and 0.743,respectively.Through the dielectric constant and the loss factor,the polysilicon dielectric loss tangent,microwave penetration depth and reflection loss as a function of temperature are obtained.The experimental results show that polysilicon can absorb microwaves and has good absorbing properties.(2)Combining the theory of quality function development and invention problem solving,transforming user requirements into technical requirements of microwave high-temperature heating system,and obtaining the importance of quality technical requirements;then using the technology conflict relationship matrix to solve the choice of invention in the design process of microwave high-temperature heating system The problem of the principle,find the general solution of the microwave high-temperature heating system program,and then use the fuzzy comprehensive evaluation to judge the parameters of the microwave high-temperature heating system to determine the optimal design of the system.(3)According to the composition of microwave high-temperature heating system,through microwave resonator,microwave power source system,microwave transmission device,cooling system and temperature measurement system design,computer software is used to model,produce and manufacture a set of power0.1kW-6.0kW,Microwave high temperature heating system with a maximum temperature of 1650~oC.(4)The influence of temperature rise rate on temperature variation under microwave power,material quality and material particle size are obtained via analyzing the temperature rise characteristics of polycrystalline silicon in the microwave field.The phosphorus is removal by microwave melting polysilicon.The removal mechanism of impurity phosphorus in the process of polysilicon melting is obtained.And the variation of phosphorus removal rate with influence factor in microwave heating and polysilicon process are revealed.The results of the experiments show that polysilicon can absorb microwave in microwave field and has quickly temperature rise.The results proves that the microwave high-temperature heating system meets the design requirements and is reliable in operation.(5)The parameters of phosphorus dephosphorization in microwave melting polysilicon is optimized using the response surface method.And the regression equation between the influence factor and phosphorus removal rate is established.The fitting results show that the model has high precision and the simulation effect is remarkable.The process of microwave dephosphorization of polycrystalline silicon was optimized,and the phosphorus removal rate was 90.32%under the conditions of melting temperature of 1600~oC,melting time of 2889s and microwave power of 3 kW,which was similar to the model prediction value of 92.41%,which verified the accurate selection of the model.This paper proves that microwave heating melting polycrystalline silicon is a highly efficient and feasible technology process,which can achieve selective removal of phosphorus in polysilicon.At the same time,the applicability and reliability of the microwave high temperature heating system in the preparation of polysilicon were verified.This paper provides new technical equipment and processes for the production and production of polysilicon.It is of great significance to promote the development of silicon-related industries including photovoltaics in order to break through key technologies such as large-scale production,comprehensive recycling,energy conserv-ation and consumption reduction.