Patent ID: 6790258
Filing Date: 2004-09-14
Classification: B01D,C23C,H01J,Y02C,Y10S

Abstract:
A method of trapping condensable AlCl3 from a gaseous effluent of an aluminum etch reaction chamber, comprising:directing the gaseous effluent via an inlet axially into a first stage of a trap chamber in which a first trapping medium is positioned radially outward from the inlet and around at least a portion of the chamber at a radial inlet-to-first medium distance from the inlet and in which a second trapping medium is positioned at an axial inlet-to-second medium distance below the inlet and radially inward in relation to the first trapping medium so that the gaseous effluent can flow from the inlet to the first trapping medium without having to flow first through the second trapping medium and so that the gaseous effluent can flow from the inlet to the second trapping medium without having to flow through the first trapping medium, and, further wherein the axial inlet-to-second medium distance is greater than the radial inlet-to-first medium distance, but wherein the second trapping medium is still close enough to the inlet such that the gaseous effluent flowing through the chamber eventually develops a lower partial pressure of AlCl3, in the effluent gas adjacent the second trapping medium as compared to increasing partial pressure AlCl3 in the effluent gas adjacent increasing build-up of condensed, solid AlCl3, on the first trapping medium, which draws AlCl3, in the effluent gas preferentially toward the second trapping medium before the solid AlCl3 build-up on the first trapping medium occludes the inlet.