Continuous chemical vapor deposition processing with a moving finite thickness susceptor

Chemical vapor deposition (CVD) of thin films onto a moving surface is an i mportant material processing technique for semiconductor fabrication, optic al coatings, and many other applications. Continuous CVD processing offers an attractive solution to meet high volume requirements. In this study,the deposition on a finite thickness moving susceptor, considering surface reac tions, is numerically investigated. When a susceptor is in motion, the reac tion zone residence time and the coupling of conduction heat transfer in th e susceptor with convection heat transfer in the gas flow significantly alt er the deposition rate and film quality. A model is developed to quantify c ontinuous CVD film production for several important design parameters. The numerical model is validated for the deposition of silicon through comparis ons with analytical results and experimental data available in the literatu re. Films produced by continuous CVD are shown to be strongly dependent on susceptor speed, material selection, and susceptor thickness. Susceptor spe ed is directly linked to residence time in the reaction region, with lower residence times resulting in less time for reaction and heating, hence redu cing growth rates, Increased thickness and susceptor thermal diffusivity al ters the thermal energy distribution, thereby reducing the susceptor surfac e temperature and lowering the deposition rate. These effects may be overco me by increasing the length of the heating zone. Film quality is also influ enced by the susceptor temperature, since reaction-controlled deposition ty pically produces different:film structure than deposition under diffusion-c ontrolled conditions. Overall, the results obtained demonstrate the feasibi lity of employing a moving finite thickness susceptor for CVD processing. A correlation of several operational parameters is also obtained for the fil m thickness. This may be used for the design and optimization of continuous CVD systems. The numerical model may also be used for considering depositi on of other materials.