How to avoid concentration unsteadiness with a CVD precursor delivery system employing bubbler?

[摘要] An approach of great certainty is suggested as to avoid concentration unsteadiness with a CVD delivery system employing bubbler. Assuming that the carrier gas has to be saturated of precursor vapour during the entire CVD experiment a set of equations has been selected from the literature for calculating the height of liquid layer in the bubbler which is necessary to this aim. The selection is made on the prerequisites that gas bubbles are spherical, diffusion of precursor vapour in them is molecular and it takes place during their rising only, which has a velocity equal to the terminal bubble velocity of rising. The errors at levels lower than the one for saturation are discussed. Heights of Al(CH3)3calculated using the approach are compared to those at which the bubbler controlling LED indicator of Dow Electronic Materials lights green, amber or red.

[发布机构] University of Chemical Technology and Metallurgy, Department of Chemical Engineering, 8 Kl. Ohridsky Blvd., Sofia; 1756, Bulgaria^1

[效力级别] 材料科学 [学科分类] 材料科学（综合）

[关键词] Bubble velocities;Carrier gas;Delivery systems;Electronic materials;Gas bubble;Liquid layer