Research On The Unstable Temperature Field Of MOCVD Susceptor Based On Finite Element Method

Metal organic chemical vapor deposition(MOCVD)is the main technology of preparation of semiconductor thin film material that microelectronics and optoelectronics need.These fields are very strict for the uniformity of thickness,uniformity of composition,and boundary between layers and layers of the thin film material.The key factor affecting the properties of the material is the temperature uniformity on the surface of the graphite base in the reaction chamber of the MOCVD equipment.Based on the finite element method,this paper developed a special simulation software for the temperature field of the MOCVD graphite base by using the C++ programming language.And with the software as a platform,the heating process of the graphite base is numerically simulated,and the influence of the structural parameters of the graphite base and heater on the temperature field of the graphite base is studied.The main work and conclusions of this paper are as follows:(1)The basic assumptions about the structure and calculation model of the graphite base and the heater are carried out.Through the study of the principle of heat transfer and radiation heat transfer,the differential equation and the definite solution condition of the two-dimensional axisymmetric unstable temperature field with internal heat source are determined.A method to deal with the nonlinear problem of thermal physical parameters is proposed.The calculation process of temperature field based on finite element method is derived.(2)By using C++ programming language,a special simulation software for temperature field of MOCVD graphite base is developed.Lawson mesh partition algorithm with point by point insertion is improved.The two dimensional chain table storage method for sparse matrix and the solution of matrix equation are studied.Through specific programming,the stability of the grid partition algorithm and the feasibility of the two-dimensional chain table storage method of sparse matrix are verified.(3)Based on the temperature field simulation software developed in this paper,the temperature field of the heating and cooling process of the graphite base is simulated.And the results are compared with the results of the commercial software ABAQUS,based on the temperature field cloud,table and temperature time curves.The numerical algorithm for solving the temperature field based on the finite element method and the correctness of the software developed in this paper are proved.(4)The influence of the structure parameters of graphite base and heater on the temperature field of graphite base is studied on the basis of the software developed in this paper,and some conclusions and experiences are obtained:the greater the thickness of the graphite base and the width of the heating ring,the more smooth the radial temperature distribution curve on the surface of the graphite base;For adjusting the power of the heating ring,the volume power of each heating ring is the same first,then the power of the outer heating ring is adjusted according to the temperature distribution,so that the temperature distribution of the upper surface of the graphite base can be evenly distributed within a certain range.The description of this range is the circular area on the surface of the graphite base,corresponding to the M circle of the second layer heating ring from the extrovert.