A Delivery System for Precursor Vapors Based on Sublimation in a Fluidized Bed

A fluidized‐bed, solid‐precursor delivery system is found to overcome the mass and heat transport problems encountered in a fixed‐bed system. To achieve ideal fluidization behavior, a combination of solid precursor (minor component) and inert particles such as alumina or silica (major component) are charged to the vessel. Using [Al(acac) 3 ] as a test precursor and operating at 423K, the rate of mass transport is measured as a function of the carrier gas flow rate. When operating at carrier gas flow rates above the minimum value required to fluidize the bed, the precursor flow rate significantly exceeds the performance of the fixed‐bed system. A simple model of a solid‐precursor delivery system is developed to quantify the relationship between operating conditions and gas‐phase precursor flow rate. The concept of the fluidized bed, solid‐precursor delivery system is validated by directing the precursor and carrier gas mixture into a CVD reactor where the flow is combined with a source of water vapor and oxygen to deposit amorphous Al 2 O 3 films on coupons of a Ti6242 alloy.