Development of a Vaporizer for Gradual Vaporization Control of Precursor Materials in the CVD Process

Abstract: In recent DRAM processes, obtaining the maximum capacitor presents a difficult challenge. Also, the aspect ratio continually increases during the process. To address these issues, the thickness of the top and bottom layers must be constant. However, the thickness is not constant due to the time difference between the bottom and top processes, and because the source changes in each step. To solve this problem, the same reaction should occur at all times while the density of the gas at the bottom and top is gradually changed. In this study, a new vaporizer is developed and evaluated to ensure a constant rate of density change and a rapid vaporization response of the liquid source. To develop a vaporizer that responds quickly, we experimentally evaluated the structures of the vaporizer's showerhead and vaporizing part. To keesp the density of the liquid source for evaporation constant, several holes were made in the showerhead from which the evaporation source is discharged. Also, to ensure a constant flow of liquid to the chamber where the source droplet meets the carrier gas, a helical structure was proposed and evaluated. In addition, using an orifice, the pressure was decreased to increase the vaporization efficiency. As a result, the settling time decreased from 10 to 3 s, overshooting decreased from 25 to 1%, and flow fluctuation decreased from 2.6 to 1.8%. Therefore, this new vaporizer is well-adapted to the process of new devices and provides greater capacitance design margins. Graphical Abstract: [Figure not available: see fulltext.]